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Dr. James Douglas.
TRANSACTIONS
OF THE
/)/
Amekican Institute of Mining AND Metallurgical Engineers
(ixcorpohated) WITH WHICH IS CONSOLIDATED THE
AMERICAN INSTITUTE OF METALS
Vol. LX
Containing the Non-Ferrous and Industrial Management Papers
AND Discussions Presented at the Colorado Meeting,
September, 1918, at the Milwaukee Meeting,
October, 1918, and at the New York
Meeting, February, 1919.
NEW YORK, N. Y. PUBLISHED BY THE INSTITUTE
AT THE OFFICE OF THE SECRETARY
29 WEST 39th street 1919
//I/ /
As
Copyright. 1919, by the American Institute op Mining and Metallurgical Engineers
(Incorporated)
i02/i7
THK MA.1>I,K PSKSB XOMJC r>j
PREFACE
This volume contains the papers and discussions on non-ferrous metallurgy industrial management and kindred subjects that were presented at the Colorado and Milwaukee meetings in the Fall of 1918, and at the New York meeting in Februarj'-, 1919.
These papers were printed in Bulletins 135 to 146 inclusive, but Vol. LX does not completely supersede any Bulletin.
Reports of the Proceedings of the Colorado and ^Milwaukee meetings are also printed in this volume.
m
CONTENTS
PROCEEDINGS
Page
Colorado Meeting, September, 1918 vii
James Douglas Memorial Service xv
Milwaukee Meeting, October, 1918 xxii
PAPERS
Practice of Antimony Smelting in China. By C. Y. Wang 3
First Year of Leaching by the New Cornelia Copper Co. By H. A. Tobei.mann
and J. A. Potter (With Discussion) 22
Elko Prince Mine and Mill. By J. V. N. Dorr and L. D. Dougan ... .78 Fine-grinding Cyanide Plant of Barnes-lving Development Co. B}^ J. H. Mc-
CORMICK 98
Automatic Separation of Solution from Solids in Hydrometallurgical Treat- ment of Ore Pulps. By Bernard MacDonald 107
Effect of Oxygen on Precipitation of Metals from Cyanide Solutions. By
T. B. Crowe (With Discussion) Ill
Roasting for Amalgamating and Cyaniding Cripple Creek Sulfo-telluride Gold
Ores. By A. L. Blomfield and M. J. Trott (With Discussion) 118
Manufacture of Silica Brick. By H. LeChatelier and B. Bogitch 134
Symposium on the Conservation of Tin :
Bronze Bearing Metals. By G. H. Clamer 162
Pennsylvania Railroad Anti-friction and Bell Metals. By F. M. Waring . 166
The Tin-plate Industry. By D. M. Buck (With Discussion) 168
The Aluminum Bronze Industry. By W. M. Corse 171
Bronzes, Bearing Metals, and Solders. By G. K. Burgess and R. W.
Woodward (With Discussion) 175
Babbitts and Solder. By G. W. Thompson 184
The Cadmium Supply of the United States. By C. E. Siebenthal (With
Discussion) 185
Solder, Its Use and Abuse. By M. L. Lissberger 192
Constitution of Tin Bronzes. By S. L. Hoyt (With Discussion) 198
Electrolytic Zinc. By C. A. Hansen (With Discussion) 206
Electrostatic Precipitation. By O. H. Eschholz (With Discussion) 243
Condensation of Zinc from its Vapor. By C. H. Fulton (With Discussion) . 280 Effect of Impurities on Hardness of Cast Zinc or Spelter. By G. C. Stone . . 303 Oxygen and Sulfur in the Melting of Copper Cathodes. By S. Skowronski . 307 Relation of Sulfur to Overpoling of Copper. By S. Skowronski (With Discus- sion) 312
Action of Reducing Gases on Hot Solid Copper. By N. B. Pilling (With Dis- cussion) 322
Spectroscopic Determination of Lead in Copper. By C. W. Hill and G. P.
LucKET 342
V
VI CONTENTS
Page
Volatilization of Cuprous Chloride on Melting Copper Containing Chlorine. By
S. Skowronski and K. W. McComas 354
Automatic Copper Plating. By J. W. Richards (With Discussion) 365
Pure Carbon-free Manganese and Manganese Copper. By Arthur Braid (With
Discussion) 371
Manganese Bronze. By P. E. McKinney (With Discussion) 374
Non-metallic Inclusions in Bronze and Brass. By G. F. Comstock 386
Standards for Brass and Bronze Foundries and Metal-finishing Processes. By
Lillian Erskine (With Discussion) 401
Volatility of Constituents of Brass. By John Johnston (With Discussion) . . . 416 Comparison of Grain-size Measurements and Brinell Hardness of Cartridge Brass.
By W.H.Bassett and C. H.Davis (With Discussion) 428
Babbitt and Babbitted Bearings. By J. L. Jones (With Discussion) 458
Metals and Alloys from a Colloid-chemical Viewpoint. By Jerome Alexander
(With Discussion) 466
Effect of Temperature, Deformation and Grain Size on the Mechanical Properties
of Metals. By Zay Jeffries (With Discussion) 474
Die Castings and their Application to the War Program. By Charles Pack
(With Discussion) 577
Metallography of Tungsten. By Zay Jeffries (With Discussion) 588
Metallographic Phenomena Observed in Amalgams. By A. W. Gray .... 657
Two Instances of Mobility of Gold in Solid State. By E. Keller 698
Radium. By R. B. Moore (With Discussion) 708
Biographical Notice of James Douglas. By Rossiter W. Raymond .... 728
Biographical Notice of Edward Dyer Peters 735
Man Power, By J. Parke Channing 741
Use of Cripples in Industry. By James P. Munroe (With Discussion) . . . 748 Mental Tests in Industry. Presented by Robert M. Yerkes (With Discussion). 752 The New Spirit in Industrial Relations. By Herbert M. Wilson (With
Discussion) 768
Prevention of Illness Among Employees in Mines. By A. J. Lanza (With
Discussion) 783
Need for Vocational Schools in Mining Communities. By J. C. Wright
(With Discussion) 792
Engineering Work of the National Research Council. By Henry M. Howe. 805
Mental Factors in Industrial Organization. By Thomas T. Read 810
Discussion on Housing. By D. Eppelsheimer and Lawrence Veiller. . . 815
PROCEEDINGS OF THE COLORADO MEETING
VI]
PROCEEDINGS OF THE ONE HUNDRED SEVENTEENTH MEET- ING OF THE INSTITUTE, COLORADO
September 1 to 6, 1918
COMMITTEE IN CHABGE
Spencer Penrose, Chairman
A. E. Carlton, Chairman Finance Committee
George M. Taylor, Vice-Chairman J. Dawson Hawkins, Secretary
Denver
Finaru:e
T. B. Stearns Richard A. Parker T. B. Burbridge
Arrangement Dave G. Miller Frank Bulkley Geo. E. Collins
Entertainment F. H. Bostwick F. E. Shepard Howland Bancroft B. P. Morse J. G. Perry
Ladies Mrs.
Mrs. Mrs. Mrs. Mrs. Mrs. Mrs. Mrs.
T. B. Stearns, Chairman C. Loughridge H. Bancroft G. Bancroft W. D. Leonard C. Chase F. H. Bostwick F. Bulkley
Colorado Springs
Finance
A. E. Carlton
Spencer Penrose
George M. Taylor
A. L. Blomfield, Treasurer
Registration
Loren C. Lennox Horace F. Lunt J. M. Tippett
Arrangement and Entertainment George M. Taylor A. L. Blomfield J. D. Hawkins Thomas B. Crowe
A. E. Carlton E. P. Arthur
G. H. Clevenger Etienne A. Ritter
Mrs. G Mrs. G Mrs. S. Mrs. .L Mrs. L. Mrs. H, Mrs. E. Mrs. L. Miss F. Mrs. C.
Cripple Creek
Thomas B. Crowe
E. P. Arthur, Jr. N. S. Greensfelder
A. E. Carlton
B. F. Hill
F. G. Willis NorrisE. Eads W. E. Ryan Fred Jones
F. D. Smale J. H. Haynes L. W. Lennox M. R. \alentine
. M. Taylor, Chairman H. Clevenger
Penrose Mrs. A. E. Carlton D. Hawkins Mrs. A. L. Blomfield C. Lenno.x Mrs. J. M. Tippett
Mrs. E. C. van Diest Mrs. W. Strieby Mrs. C. L. Bailey
Pueblo J. F. Welborn H. B. Carpenter L. B. Eames F. Robinson
F. Lunt A. Ritter S. Harner
Dickerman Mrs. E. P. Shove
L. Tutt
Mrs. F. G. Peck
Mrs. F. D. Pastorius
It was peculiarly fitting that the American mining engineer, holding a war-time conference, should have chosen for the scene of the meeting the State of Colorado, better endowed, perhaps, than any other State to fill the need for war minerals. The 117th meeting of the American In- stitute of Mining Engineers reflected in both technical and social features an enthusiastic effort to support every aim of a war-winning character.
Although avoiding any lavishness of display or extravagant enter- tainment, inappropriate to the times, the Colorado members of the In- stitute provided a week of well varied instruction and recreation such as can only be offered amid the snow-peaked mountains of the State. The fact that during all but one day of the week "nature's dewy tear drops" fell intermittently failed to detract from the successful execution of the Committee's plans.
Two days in Denver and four in Colorado Springs, from which ex- cursions were made to the Cripple Creek district and Pueblo, comprised the program. On Sunday, Sept. 1, the visiting members and their guests arrived in Denver. Registration at the headquarters in the Brown
VUl
PROCEEDINGS OF THE COLORADO MEETING
Palace Hotel showed a total of 275 on Sunday night, which number was increased to more than 500 before the close of the meeting.
Sunday was spent in a visit to the City Park Museum in Denver; attendance at a special recital on the municipal organ, said to be the largest and most complete orchestral organ in the world; a special evening display of the electric fountain at City Park, and automobile processions through the City Parks and Boulevards.
On Monday, Sept. 2, shortly after nine o'clock, the first technical session of the meeting was held. Thomas B. Stearns presided and directed the discussion on Metallurgy.
Two hours later, the delegates, conveyed by automobiles, were in- specting the electric ferromanganese furnaces of the Iron Mountain Alloy Co., at Utah Junction, three miles from Denver. This plant, it
SEPTS-
%- summit' -pikes peak
ABovf sf » tern _
iHf ^^
was said, is being used experimentally for war purposes preparatory to larger developments. It is in many ways similar to the type of plant at Anaconda, though lacking some of the modern improvements.
Monday noon a luncheon was served to the members, and about one hundred ladies who were guests, in the Denver Club. Following the luncheon, Thomas B. Stearns, Chairman of the Denver Finance Com- mittee of the convention, welcomed the party to Denver and made a bit of history by the remark that inclement weather had come "for the first time in 365 days." Mr. Stearns introduced Mayor W. F. R. Mills, who explained some of the scenic features of Denver and then welcomed the delegates with the words "the City is yours." President Sidney
PROCEEDINGS OF THE COLORADO MEETING IX
J. Jennings of the Institute thanked Mayor Mills and the Denver members on behalf of the guests.
Immediately after luncheon the party left in automobiles for Lookout Mountain and Genesee Park, a unique municipal development in that it lies 20 miles from the administrative center. En route, many of the guests were taken to the Herold Pottery Works, at Golden, for an inspec- tion of the process of manufacturing high-grade chemical porcelain.
Following the Lariat trail on Lookout Mountain, over roads built by the City of Denver, the party reached the summit in about one hour and a half. Here is the grave of Col. William F. Cody (Buffalo Bill) covered by native rocks and stones. Many of the party added their pieces to the monument, rough hewn as the man himself, by placing a stone on his resting place.
In the course of the afternoon's tour, which included a trip through Genesee Park and along the banks of the beautiful Bear Creek, a thunder storm broke around the mountains, the greater part being in the clouds beneath the summit of Lookout. It was possible to look down upon the storm from the high altitude and after a few minutes to observe the sun shining through the great white clouds as they parted.
On Monday evening a dinner was served informally in the Denver Country Club to some 300 persons. Following dinner, F. B. Burbridge of Denver established a record as toastmaster by limiting six speakers to a total of 45 minutes. The speakers were Sidney J. Jennings, E. P. Mathewson, H. Foster Bain, C. W. Goodale, Thomas B. Stearns, and Horace V. Winchell.
On the following morning the party journeyed by motor and train to Colorado Springs, arriving at the meeting headquarters, the Broad- moor Hotel, at about noon. At one o'clock a splendid luncheon was served in the hotel dining rooms.
An hour later a memorial service for Dr. James Douglas, in the theatre of the hotel, was attended by every member. President Sidney J. Jennings presided and, after paying a tribute to Dr. Douglas, introduced E. P. Mathewson, representing the Canadian Mining Institute, who, as a fellow Canadian, told of Dr. Douglas' early life in the Dominion; Walter Renton Ingalls, editor of the Engineering and Mining Journal, representing the Mining and Metallurgical Society of America, who spoke of Dr. Douglas as a scientist; and T. H. O'Brien, representing the Phelps- Dodge Corporation. The words of these men made a deep impression upon those present. (A full report of this service is given on pages XV to xxi.)
A series of motion pictures, showing the adaptation to industry of soldiers crippled or disabled in war, were later shown in the theatre. These pictures were made by the Canadian Government and loaned to the Institute by the U. S. Department of the Interior. The opportunities thus far opened to cripples from the war, as pictured, surprised many and, as indicated by informal remarks, strengthened their desire to provide "a better place for the cripple than he had held before and to give him the preference."
The remainder of Tuesday afternoon was given over to two simul- taneous technical sessions, one on Ore-dressing and Cyanidation, pre- sided over by G. H. Clevenger, and the other on Coal and Coke, at which A. E. Carlton presided. At this latter session many members of the Rocky Mountain Coal Mining Institute were present, though not holding
X PEOCEEDINGS OF THE COLORADO MEETING
a joint meeting with the Institute, as planned, because of the absence of their president.
The Ladies' Committee of Colorado Springs furnished an interesting program during the time of the technical sessions, which included visits by automobile to the Garden of the Gods and Glen Eyrie, and tea in the Castle of the Glen. Throughout the week the Ladies' Committee provided man}^ features of special interest to the visiting ladies.
During Tuesday evening a formal reception and dance was held in the Broadmoor Hotel, continuing until after midnight.
Despite a heavy mist on Wednesday morning, Sept. 4, a train of mining engineers was ready for a trip to the Cripple Creek District, at 8 o'clock. A special train on the Colorado Midland Railroad was provided by the hosts, and about 11 o'clock the party was skirting the mountainside in sight of the District. The little town of Altman, said to be the highest incorporated town in the world, was passed and a little later the train reached Victor, where a luncheon was served in a great tent, pitched near the tracks, by the Portland Gold Mining Co. The party then spent some two hours inspecting the Independence mill. During the visit some of the guests were taken through the Cresson mine, producing the highest-grade ore of the district, and others walked or motored down the deserted streets of the town. The romances, the tragedies and the disappointments of gold mining in Cripple Creek were all in evidence, but only as memories. The business of gold mining no longer reads like a story book in Cripple Creek.
The special train returned to Colorado Springs at 6 o'clock. That evening. Dr. Richard B. Moore opened a technical session on Geology and Alining in the theatre of the Broadmoor Hotel, with a series of experiments with radium, presented in a semi-popular manner, and in- dicating the uses to which radium has been put in the war. This was followed by the discussion of other subjects related to the topic of the evening, H. Foster Bain presiding. During this session, the Secretary presented the following resolution, recommended by the Board of Directors, which was unanimously passed by the members:
RESOLVED : That the following minute be entered in the Proceed- ings of this meeting, and that a copy thereof, signed by the President and Secretary-, be sent to the family of Dr. Douglas.
Through the death of James Douglas, this Institute, in common with the pro- fessions of mining and metallurgy, and the representatives of Uberal learning, technical education, wise philanthropy, and social progress throughout the world, is called to deplore the loss of an inspiring leader, tireless laborer, loyal and helpful friend.
Dr. Douglas' sympathies, quick toward every worthy cause, were especially drawn toward the Institute, because its chief purpose, namely, the free interchange of professional knowledge and experience, commanded his life-long allegiance, not only as a dictate of wise policy, but also as the result of an irresistible generous im- pulse. He gave freely; he gave "himself with his gift;" and his reward was known of all, even before the record of it, in the gratitude and grief of innumerable friends, was signed and sealed by his death. To them he was not only great, but dear.
Although greeted by a drizzling rain on the morning of Thursday, Sept. 5, and the prediction that snow was falling on the mountain, some 150 of the delegates set out early to make the ascent of Pikes Peak by automobile. The first motor car reached the top of the Peak through a heavy snow fall in about four hours, and before the last car of the party had turned back there was five inches of snow on the ground. Lunch was
PROCEEDINGS OF THE COLORADO MEETING xi
served at Glen Cove on the Pikes Peak Highway and, despite the obstacles of the trip, those courageous enough to take it were delighted with the novelty of the adventure. During the afternoon, those who had remained at headquarters and some of those returning from the Peak, visited the Golden Cycle mill on the outskirts of Colorado Springs. Here they observed the precipitation of gold on zinc and the cyanidation of low- grade ores on a vast scale.
Thursday evening was perhaps the busiest single period of the week. Five meetings were held between 8 o'clock and midnight, all of the greatest interest. The first meeting featured a series of motion pictures showing mining and milling methods, welfare work, and the patriotic impulse in the daily routine of the Inspiration Consolidated Copper Co., at Inspira- tion, Arizona. Dr. L. D. Ricketts supplemented the title explanations of the "movies" with concise facts that made the exhibition almost as instructive as a visit. The pictures were models in the field of cinemato- graphy, even though made, in some instances, under handicaps.
President Jennings, at 9 o'clock, presided at a meeting in memory of the 15 members of the Institute known to have made the supreme sacri- fice in the war. A service flag of the Institute, showing 845 in service, hung from the stage, and as Secretary Stoughton read the records of those who have died or been killed in the service of the Allies, their pic- tures were thrown upon the screen. Everyone attending at the Conven- tion joined in paying tribute at this service. (The biographical notices read by the Secretary will be printed in Vol. LXI.)
During the remainder of the evening, three technical sessions were held simultaneously, the principal one being on Petroleum, presided over by R. D. George. The others were a continuation of the discussion of electrostatic precipitation, opened at Monday morning's meeting, and a session on coal-mining problems of today.
Friday morning dawned auspiciously for the trip to Pueblo, and an elaborate program of entertainment for the ladies. The majestic hills forming a background for the hotel were bathed in sunlight and the air was mild and balmy. A special train on the Colorado & Southern Rail- road left the Springs at 9 o'clock, taking the party south over the plains to Pueblo and thence to Minnequa, where the works of the Colorado Fuel and Iron Co. are situated.
After an hour's visit to the enormous byproduct coke ovens, installed in July, the members and guests were given luncheon in the company clubhouse situated on the edge of a small lake. The desire of most of the party to spend all their time in the works, which have established, with other steel works, such an important place in war-winning fields, shortened the lunch period, and automobiles were pressed into service in scores to return the delegation to the works. During the afternoon everyone w^as given an opportunity to inspect the Bessemer and open- hearth processes. Some 40 executives of the plant took groups of the engineers on a thorough tour of inspection. The maximum monthly record for these works in production of steel is 55,000 tons. Some 6000 men are employed.
The return to Colorado Springs was made on the special train about 6 o'clock. The advantages of travel by special train, which was achieved so efficiently by the Colorado Committee, relate to more than mere transportation. The opportunity for social intercourse affords a chance to form many new acquaintances, which are renewed year after year
XU PROCEEDINGS OF THE COLORADO MEETING
among the profession, and are often cemented into warm friendships.
During Friday, the ladies of the party were driven by automobile to Crystal Park, where a picnic lunch was served, and at 4.30 o'clock Mrs. Spencer Penrose entertained them at a garden party at El Pomar.
To banquet with a State Food Administrator as toastmaster might seem a dull form of amusement, but the banquet on Friday night, in the dining room of the Broadmoor, which marked the close of the 117th meeting, was a livelj^ finale for the week. Twenty-four songs, printed in booklet form and most of them of a patriotic character, kept the spirits of the party high. A quartet led the singing and their efforts were assisted by various amateur song writers among the diners. Not the least capable among these was one who immortalized the Thursday morning push to the top of the Peak by the following verse — sung to the tune of "There's A Long, Long TraU"—
There's a long, long trail awinding Up to the top of Pikes Peak, WTiere the sun is always shining And the clouds don't leak. There's a long, long time of waiting Until the lunch box comes through, Till all the mining engineers Are sitting down to chew.
Thomas B. Stearns made an inimitable toastmaster; he was in- troduced by A. E. Carlton.
President Sidnej^ J. Jennings, the first speaker, stated that the aim of the Institute now is to win the war, and completely defeat the Hun. Then he told of some of the work being done by members of the Institute in important posts, and closed with a warning to "steel our hearts against the insidious propaganda of the German Government, which is sure to come, and perhaps ver}' soon when they realize the tide has turned against them." He thanked the Institute's hosts for the entertainment which he characterized as delightful in every respect.
Captain Louis Benett, representative of Andre Tardieu, High Com- missioner of France to the L'nited States, electrified the guests by telling them that the present need is not for transportation or food but "to pour as many tons of steel as you have on the heads of your enemy." Tremendous applause greeted his statement that "America is doubtless France's best friend."
Philip N. ]\Ioore then spoke of the importance of the mining engineer in every walk of life, and E. P. Mathewson pictured the work of women in Canadian mining centers. He said they do all kinds of work around smelters except heavy lifting, and that when women take their place in American mining it will be found that "they will do the job better than the men ever did."
C. W. Goodale, who first came to Colorado as a mining engineer in 1876, stated the cardinal necessities to the proper administration of effi- cient mining, as regards the employee.
Secretary Bradley Stoughton told the guests of the auspicious begin- ning of the Washington, D. C, Section of the Institute. He then urged the greater use of the library in the Engineering Building in New York, although stating that it is now doing work for more mining engineers and metallurgists than for any other of the great societies in the building. He then explained the value of the Index which first appeared in the
PROCEEDINGS OF THE COLORADO MEETING xiii
September Bulletin; gave new honor to the Woman's Auxiliary for its war work, especially the founding of a dispensary in France, and expressed the great appreciation of the members and friends for the untiring and thorough efforts of the Colorado members in making the meeting highly successful, none, he said, having exceeded it in varied features.
Horace V. Winchell spoke on the Russian situation, and Dr. L. D. Ricketts closed the banquet, telling, in blank verse, the career of the min- ing engineer.
Dancing followed the banquet and the ballroom was filled till a late hour, as it had been on each of the four evenings spent in the Springs.
On Saturdaj^, Sept. 7, several of the engineers went to the Leadville district to view the production of the many war minerals of that locality, but most of the party started for their homes on Saturday morning.
Technical Sessions
Session on Metallurgy
The session on metallurgy was held on ]\Ionday morning, Sept. 2, 1918, at the Brown Palace Hotel, Denver, JNIr. T. B. Stearns presiding. The following papers were presented:
Electroh'tic Zinc. By C. A. Hansen. (Presented by author and discussed by Sidney J. Jennings and the author. Written discussion by J. L. McK. Yardley.)
The iSIanufacture of Ferro-alloys in the Electric Furnace. By R. M. Keeney. (Presented by the author.)
The Metallography of Tungsten. By Zay Jeffries. (Presented by title. Written discussion by Sir Robert A. Hadfield.)
The Condensation of Zinc from Its Vapor. By C. H. Fulton. (Presented by title and discussed by E. E. Thum.)
Electrostatic Precipitation. By 0. H. Eschholz. (Presented bj^ title. Written discussions by Harmon E. F. Fisher and G. B. Rosenblatt.)
Oxygen and Sulfur in the Melting of Copper Cathodes. By S. Skowronski. (Presented by title.)
The Relation of Sulfur to the Overpoling of Copper. By S. Skowronski. (Pre- sented by title. Written discussion by Philip L. Gill.)
The Practice of Antimony Smelting in China. By C. Y. Wang. (Presented by title.)
Session on Coal and Coke
The session on coal and coke was held on Tuesday afternoon, Sept. 3, Mr. A. E. Carlton presiding. The following papers were presented:
The Byproduct Coke Oven and Its Products. By WLUiam Hutton Blauvelt. (Presented by title and discussed by Graham Bright, S. A. Moss, John I. Thompson.)
The Use of Coal in Pulverized" Form. By H. R. Collins. (Presented by the author and discussed by E. A. Holbrook, Captain Walter Graham, Bradley Stoughton, Milnor Roberts, Erskine Ramsay, H. N. Eavenson and the author.)
Carbocoal. By C. T. Malcolmson. (Presented by the author. Written discus- sions by F. W. Sperr, Jr., N. W. Roberts, J. M. Fitzgerald, W. R. Cox, F. R. Wadleigh, Charles Catlett, C. IM. Barnett.)
Development of the Coke Industry in Colorado, Utah and New Mexico. By F. C. Miller. (Presented by the author.)
Price FLxing of Bituminous Coal by the U. S. Fuel Administration. By Cyrus Garnsey, R. V. Xorris and J. H. Allport. (Presented by the Secretary.)
Coal Alining in Washington. By F. A. Hill. (Presented by title. Written discussion by Milnor Roberts.)
Session on Ore-dressing and Cyanidation
The session on ore-dressing and cyanidation was held on Tuesday afternoon, Sept. 3, IMr. G. H. Clevenger presiding. The following papers were presented:
XIV PEOCEEDINGS OF THE COLORADO MEETING
The Effect of Oxygen upon the Precipitation of Metals from Cyanide Solutions. By T. B. Crowe. (Presented by the author and discussed by J. V. N. Dorr. A. L. Blomfield, G. T. Hansen, G. M. Taylor, L. H. Dushak.)
Roastmg for Amalgamating and Cyaniding Cripple Creek Sulfotelluride Gold Ores. By A. L. Blomfield and M. J. Trott, (Presented by A. L. Blomfield and discussed by J. V. N. Dorr and J. M. Tippett.)
The Tailing Excavator at the Plant of the New ComeUa Copper Co., Ajo, Ariz. By Frank Moeller. (Presented by the author and discussed by E. P. Matthewson,
C. A. Hansen and Frank Moeller.)
The Elko Prince Mine and Mill. By J. V. N. Dorr and C. D. Dougan. (Presented by J. V. N. Dorr.)
Crushing Resistance of Various Ores. By L. W. Lennox. (Presented by the author and discussed by R. B. T. KiUani, C. A. Hansen, V. A. Stout, Rudolf Gahl and the author.)
Hand-sorting of Mill Feed. By R. S. Handy. (Presented by title. Written discussions by A. Stanley Hill, W. L. Ziegler, L. O. Howard, Clarence A. Wright,
D. C. Bard, S. A. Easton, F. A. Thomson, W. H. Linney and the author.)
The Automatic Separation of Solution from Solids in the Hydro-metallurgical Treatment of Ore Pulps. By Bernard MacDonald. (Presented by title.)
Fine-grinding Cyanide Plant of Barnes-King Development Co. By J. H. McCor- mick. (Presented by title.)
Session on Economic Geology and Mining Practice
The session on economic geology and mining practice was held on Wednesday evening, Sept. 4, Mr. H. Foster Bain presiding. The fol- lowing papers were presented:
Radium. By R. B. Moore. (Presented by the author and illustrated by experi- ments. Discussed by Dr. W. A. Schlesinger, H. J. Seaman, S. A. Moss and the author.)
Molybdenite Operations at Chmax, Colorado. By D. F. Haley. (Presented by the author.)
Engineering Problems Encountered During Recent Mine Fire at Utah-Apex Mine, Bingham Canyon, Utah. By V. S. Rood and J. A. Norden. (Presented by V. S. Rood and discussed by George S. Rice and V. S. Rood.)
The Relation of Sulfides to Water Level in Mexico. By P. K. Lucke. (Pre- sented by title.)
The Mechanics of Vein Formation. By Stephen Taber. (Presented by title.)
Pyrite Deposits of Leadville, Colorado. By Howard S. Lee. (Presented by the author.)
Fireproofing Mine Shafts of the Anaconda Copper Mining Co. By E. M. Norris. (Presented by title.)
Air Blasts in the Kolar Gold Field, India. By E. S. Moore. (Presented by title.)
Man Power. By J. Parke Channing. (Presented by title.)
Session on Petroleum
The session on petroleum was held on Thursday evening, Sept. 5, Mr. R. D. George presiding. The following papers were presented:
Gagmg and Storage of Oil in the Mid-Continent Field. By O. U. Bradley. (Presented by the author.)
An Interpretation of the So-called Paraffin Dirt of the Gulf Coast Oil Fields. By A. D. Brokaw. (Presented by title. Written discussions by W. E. Wrather, E. G. Woodruff and Lee Hager.)
The Theory of the Volcanic Origin of Salt Domes. By E. L. DeGolyer. (Pre- sented by title. Written discussion by J. A. Udden and E. L. DeGolyer.)
A Concrete Example of the Use of Well Logs. By Mowry Bates. (Presented by the author and discussed by C. A. Hammill, Dorsey Hager and the author.)
Oil in Southern TamauHpas, Mexico. By Ezequiel Ordonez. (Presented by title. Written discussion by V. R. Garfias.)
Geology of the Oil Fields of North Central Texas. By Dorsey Hager. (Presented by the author and discussed by C. A. Hammill, C. H. Beal, M. I. Goldman, J. S. Lewis, A. C. Dennis and the author. Written discussion by W. E. Pratt.)
PROCEEDINGS OF THE COLORADO MEETING XV
Staggering Locations for Oil Wells. By R. H. Johnson. (Presented by title and discussed by J. L. Lewis.)
Losses of Crude Oil in Steel and Earthen Storage. By O. U. Bradley. (Pre- sented by the author.)
The Possible Existence of Deep-seated Oil Deposits on the Gulf Coast. By A. F. Lucas. (Presented by title.)
Lithology of the Berea Sand in Southern Ohio, and Its Effect on Production. By L. S. Panyity. (Presented by title.)
THE JAMES DOUGLAS MEMORIAL SERVICE
On Tuesday afternoon, Sept. 3, the Institute held a service in com- memoration of Dr. James Douglas, who died at New York on June 25, 1918. President Sidney Jennings presided.
President Jennings. — We are met here to show our appreciation of the life of a great man, and we shall gain strength to do our own daily tasks from the contemplation of a career strongly founded, continuously built up, having the star of hope as its guiding light.
Dr. Douglas was an engineer, a scientist, a literateur with a charming sense of stjde, a benefactor with a singularly wide variety of interests, and a man who had acquired wisdom and understanding, which surpass verj^ great riches. As the poet puts it, "When some beloved voice that was to you both sound and sweetness faileth suddenly, and silence against which you dare not cry aches around you like some disease both strong and new, we poor mortals strive to fill that silence with words of sympathy and appreciation." The very limitation of these words shows our need of the light and guidance which we can acquire from the con- templation of the life of Dr. Douglas.
Other speakers will deal with various phases of the life of Dr. Douglas; I can speak from personal knowledge of only one of his many benefactions to the American Institute of Mining Engineers.
In 1905, Mr. Andrew Carnegie gave to the four national engineering societies of America a sum of money sufficient to erect a large and beautiful building in which to house their activities. He wisely coupled with that gift a proviso that the societies should acquire the title to the ground upon which it was to be built. That entailed upon the slender resources of the American Institute of Mining Engineers a very heavy burden. Many attempts were made to lighten it and contributions were made, but still the burden was heavy, and when I was elected to the Boa^d of Directors, it still weighed heavily upon us.
Dr. Douglas, although he had twice filled the office of President of the Institute and had given much of his time and thought as a Director, came to the rescue and undertook to raise the large sum of money that was necessary to free the Institute from debt. In a comparatively short time, in 1914, largely through his own personal contributions and those of members of the firm with which he was associated, this burden was lifted, and the Board of Directors and members of the Institute were able to breathe once more the air of financial freedom.
In addition to the numerous and large gifts that Dr. Douglas has made to the Institute, by the terms of his will the sum of $100,000 has been given it for the use of its library, and it is hoped that this sum, together with the yearly contributions made by the four national societies, will bring the library service to that degree of perfection which all those who are interested in the library and its work aim to achieve.
XVI PROCEEDINGS OF THE COLORADO MEETING
I shall now ask Mr. E. P. Mathewson, a Canadian, to tell us of the early days of Dr. Douglas, who w^as also a Canadian.
E. P. Mathewson. — In my early youth I knew of no name in science to compare with that of Dr. Douglas. He was associated many years with the late Dr. T. Sterry Hunt, and Dr. Hunt was the immediate cause of my coming to the United States from Canada and entering on my professional career in this country.
Dr. Douglas was a man of most benevolent disposition, far-seeing in many ways, who, though possessed of much wealth, thought nothing of money; he had not the love of money at all. The only use he had for money was to do good to those who needed it.
Dr. Douglas was particularlj^ thoughtful of his Canadian fellow countrymen and particularly of those who were engaged in scientific pursuits. The educational institutions of Canada were frequently benefited by his benevolence. McGill University was highly favored by Dr. Douglas, after he learned of the financial difficulties of that in- stitution. McGill, not being granted any aid from the state and relying upon private benevolence, had outstripped its income in giving what it could of educational advantages to Canadians, and it became necessary at one time to have a campaign for more funds. In this campaign Dr. Douglas responded nobly and was the means of getting the necessary funds to go on with the good work of that University. The University from which he graduated, Queens University, was also frequently aided by his benefactions. Altogether, the sums given by him during his life- time to Canadian institutions w^ould be probably up in the millions, but he was so unobtrusive and so retiring in his disposition that he seldom allowed his name to be used in connection with these matters unless it was possible, by using his name, to influence others to similar benevolence. Anywhere in Canada, if you mention the name "Douglas," you will find people who will say at once, "That was a great Canadian, a man we all reverenced."
(Mr. Mathewson next read the biography of Dr. Douglas printed in the July 6, 1918, issue of the Engineering and Mining Journal. As a biography written by Dr. R. W. Raymond is in this volume and an "Appreciation," by Dr. A. R. Ledoux, was published in our Bulletin No. 109, it is hardly necessary to reprint here the account read by Mr. Mathewson.— Ed.)
Dr. Douglas had the broadmindedness to introduce the open door into metallurgy. Prior to his advent into the metallurgical field, the non-ferrous metallurgists in this country, in Canada, and practically all over the world, were absolutely oyster-like toward visitors. No one was admitted who did not have a letter of recommendation from one of the Board of Directors, at least. But Dr. Douglas, early in his career in this country, allowed every one to visit the plant and the mines with which he was connected. He welcomed them, and argued that he was getting as much benefit from the visitors as the visitors were getting from him.
The example of Dr. Douglas was followed by many metallm-gists in this country, and today we may say that there is hardly a non-ferrous metallurgical establishment in the United States and Canada to which a person who is honestly seeking information cannot obtain access. Of course, during war times a few precautions are taken for fear that informa- tion might get to the enemy. This, of itself, is enough to make Dr.
PROCEEDINGS OF THE COLORADO MEETING Xvii
Douglas called a great man, and to let his name go down to posterity as really the father of open-door metallurgy.
President Jennings. — I will ask Mr. W. R. Ingalls, Editor of the Engineering and Mining Journal, who was thrown in contact with many of Dr. Douglas's scientific activities in the United States, to tell us of his achievements as a scientist.
W. R. iNGALLs.^In the death of Dr. Douglas the Institute lost its greatest member, the mining industry lost one of its greatest exponents, and the world lost a philosopher. Fortunate are we all that his works and his inspiration live after him. The results of his material work will doubtless disappear in the course of time, just as did most of the construc- tion work of the Greeks and the Romans, but just as the teachings of their philosophers survive, so will those of Dr. Douglas, and his inspiration will be one of the world's greatest possessions forever.
The appreciation of how great a man he was will be clearer and keener in the future than it is now. No matter how much we may think we understood him, reflection and meditation will surely reveal to us many things about him that not yet do we see.
Dr. Douglas was a very successful man in material things, and it is one of the remarkable features of his career that this kind of success did not begin to accrue until he was nearly 50 years of age. It is even more marvelous to us in his profession that, although he attained a great age, his great accomplishments were achieved during about 33 years, and those the latter years of his life.
He became a captain of industry, which in itself was a distinction for one who was inherently a philosopher, and he acquired great wealth for which he did not care and which he bestowed bounteously upon many worthy causes; but ambition for material power and a sordid interest in acquiring a great fortune were the furthest of anything from his thoughts. His mind and his fiber were different; his habits were simple; his mode of living was most modest. His thoughts were largely of his studies, and those studies were mainly concentrated upon the improve- ment of human welfare.
I do not remember when I first became acquainted with Dr. Douglas. I knew of him, of course, from my introduction into professional studies. The beautiful metallurgical process devised by him in connection with the redoubtable Sterry Hunt was one of the things that we were given to ponder upon in the class-room.
I think I first met Dr. Douglas about 20 years ago in connection with his very ^ingenious muffle roasting furnace, but my intimate association with him was during the last 12 years, when there existed the relations which naturally exist between an editor and his most valued con- tributor, and also the relations that exist between the fellow members of committees engaged in doing public work.
It has not been until his death that I appreciated the demands that I made upon him and the generosity and the alacrity with which he invariably acceded to them. That is simply one of the revelations of the character of this remarkable man that come to us when he is no longer with us.
Considering his multifarious engagements as the head of the great mining, railway, and other industrial enterprises, I am appalled to think that I could ask him, in the interest of the profession and of the public, to put his work aside and do the writing and the speaking that I and
Xviii PROCEEDINGS OF THE COLORADO MEETING
others wanted him to do. For the very reason that he wanted to aid his fellow men, he was so generous. Oftentimes he would suggest to me editorials that should be written and should be published. Many of the most important editorial expressions that we have made to the public during the last 12 years have been the anonymous contributions of Dr. Douglas, besides those to which he so liberally affixed his name. Often- times he would say to me that at the metallurgical works of the Copper Queen Company some important investigations were coming to a head, investigations whereof the profession should be fully informed, and that he would direct his metallurgical men to work up papers on those subjects for the benefit of the industries.
Now, to my mind, the thing that above everything else constitutes Dr. Douglas as one of our great men, a man greater than any of us yet appreciate, is just that interest of his in the promotion of human knowl- edge and the promotion of such knowledge as would better the welfare of the human race and enable men to work more advantageously.
I think perhaps his first declaration of the principle of the open door, of which Mr. Mathewson has spoken so fittingly, is to be found in his presidential address to this body in 1899, and may I read just a few words from that address,^ which give the essence of his ideas?
The motives influencing the great body of writers who, without any pay, use the technical journals and such media of communication as our Transactions, in order to give to the brethren of their craft the results of their dearly earned experience are various and complicated, but in the majority of cases the impulse originates in the desire for reciprocity and in the hope that others will tell what they know in return for what we ourselves communicate and that, therefore, we shall learn at least as much as we can teach.
Dr. Douglas himself practised what he preached. There was never any secret about operations at the Copper Queen or at any of his enter- prises. To every visitor and applicant for information, the helping hand was extended. This spirit spread among other managers, and to that spirit more than anything else ought we attribute the high stage of efficiency to which our American mining and metallurgical industries have come.
If we should turn to the other side of the shield, we should find that in Great Britain these industries have been backward for just the opposite reason. A few years ago I asked a distinguished lead smelter of Great Britain to contribute a paper upon the lead smelting industry of his country. He replied that he could better contribute a paper upon the lead smelting industry of America, for, although he had been engaged in a prominent metallurgical center of Great Britain for 30 years in one of the leading smelting works, and although in the same place there were two other smelting works like his own, he had never, during the 30 years, been into either of them, nor had either of those managers been into his works; but since this great war has been in progress, our British friends have learned the lesson that Dr. Douglas first taught in this country. They are profiting by it, they are collaborating, they are throwing open their doors to one another for an exchange of information to such an extent that they are perhaps outdoing us, and will not unhkely compel us to look to our laurels,
1 Trans. (1899), 29, 648.
PROCEEDINGS OF THE COLORADO MEETING XIX
And so it is that the spirit of Dr. Douglas is spreading all over the world, not only through our own country and Canada, but also through Australia and Great Britain, as it will also spread through other parts of the world, and it is for that reason that the time is going to come when the entire world will know him for the great philosopher and the great prophet that we already know him to be.
President Jennings. — I will now ask Mr. T. H. O'Brien, who has been delegated by the Phelps, Dodge Corporation, as one who was intimately acquainted with the activities of Dr. Douglas, to tell us of his work in Arizona and the Southwest, and in America generally.
T. H. O'Brien. — The death of Dr. Douglas closed a long, honorable, and eventful career, filled with accomplishments that would have oc- cupied fully the lives of several men of less marked ability. Seldom has one man combined in the short span of human life such exceptional achievements. Little can be said regarding his knowledge and ability as an engineer and a scientist that has not already been published, and is known to the members of this Institute. His accomplishments were so varied and extensive that nothing short of the story of his life, written by a competent biographer, can do him justice.
I am not here to give a detailed account of his business career, but rather as a friend and an employee who was associated with him for many years, to tell you something about his work in connection with the com- pany of which he was so long the executive head, and to pay him tribute.
It was in 1880, attracted by some specimens of ore sent from a mine in Arizona, that he paid his first visit to that far off land of which the East then knew so little, which had only lately been made accessible by the construction of a trans-continental railway. It was then that he became associated in a business way with the great Southwest, and this provided the opportunity for his exceptional talents in the development of the mining and railroad possibilities of that part of our country and of Northern Mexico. He never lost the interest thus acquired, and became truly western in his views and preferences.
The Copper Queen mining property at Bisbee had lately been opened, and this attracted him. He interested the late William E. Dodge and D. Willis James, who were at that time metal merchants of New York and partners in the firm of Phelps, Dodge & Co. They began systematic development work. After less than four years the ore began to fail and dark days set in for the enterprise. These reverses only stimulated him to greater effort, and he persisted in his belief that further 'development would culminate in permanent success. The world knows today how well founded were his perseverance and faith in what has now become one of the greatest copper properties in the world, and it is not too much to say that he alone was the moving cause of that suc- cess. It is significant, too, that this achievement came to him when he was nearly fifty years of age, at a time when most men have lost the eager faith and assurance of youth. But this determination was char- acteristic of the man so long as bodily strength was given to him to follow the direction of his ever versatile and orderly mind.
Perhaps the fact that he entered the mining profession at this time in his life accounts for his having been able to avoid the small preju- dices prevalent in the early days of mining and smelting. His was a larger viewpoint, and everything was looked at and considered in a bigger, broader way. His ability to see ahead enabled him to make
XX PROCEEDINGS OP THE COLORADO MEETING
provision that insured the steady growth of his operations, and it was this gift of broad vision, combined with the conservative judgment of the original members of Phelps, Dodge & Co., that accounts for the steady growth of the enterprise. He was a dreamer of dreams; he saw possibilities where others saw none; but he lived to see his dreams come true.
He and his associates extended their operations to a consolidation with the Atlanta Company, and later to the districts of Morenci and Globe, in Arizona, Nacozari in Mexico, and afterward to Tyrone in New Mexico. The satisfactory development of these mining and smelt- ing operations under Dr. Douglas' guiding hand soon led him to acquire for the company the coal mines and coking plant at Dawson, New Mexico.
The growth of these numerous enterprises emphasized the urgent need for better transportation facilities. The ability of their founder was equal to the necessity, and Dr. Douglas now turned his attention to the construction of the El Paso & Southwestern Railway system, connecting the various mining and smelting plants with the newly acquired coal property. He thus became a builder of railroads and a master of trans- portation as successful as he had been in exploiting the mining industry of the Southwest.
What the magnitude of these operations has meant to the Southwest, and especially now, during the great world war, can only be appreciated by those who know the extent of the aid they are giving to the country and its allies in providing raw materials so necessary to the successful carrying on of the war. Truly it may be said that this man did not lay down his cares until he had fully done his part toward winning the great war for permanent peace and equal rights for humanity.
During the development of the different Phelps-Dodge mines, mills, and smelters, there was no man in America, or perhaps in the world, who did more than Dr. Douglas to break down the secrecy as to methods that was prevalent years ago in the great industrial enterprises. He be- lieved in frank, reciprocal relations between competitors in business, and in the greater efficiency that would grow from this policy. Those in charge of his industrial plants were instructed to give every facility to those who earnestly sought to learn. His views on this subject were fully justified, and it became a matter of common knowledge in the busi- ness world that his enterprises occupied a unique and enviable position among like institutions. We can only conjecture what great influence this sound policy had in the economic development of the country and the world.
His sympathetic, kindly and democratic nature toward all classes of his employees, and toward tbose with whom he came in contact, endeared him to each and every one, and to them he was a close personal friend who always had their interests at heart. He was lovingly called "The Professor" by the older prospectors and miners, and was a familiar figure in all southwestern mining camps in the early days.
His philanthropies were many, broad, and effective. In this he avoided publicity, and it will never be known to what extent he aided his fellow man. Individuals alone were not his only charity, but he also went to the assistance of many educational institutions and scientific bodies. He ever stood ready to give counsel, and many* a rough place he made smooth for a younger or less fortunate fellow.
PROCEEDINGS OF THE COLORADO MEETING XXI
He was perhaps the most conversant man on a wide number of sub- jects that one could ever hope to meet — equally at ease with any subject, unusually well informed on all.
He was alwaj^s ready to recognize and reward merit, and cared noth- ing for mere place or position. He was splendidly thoughtful of those who worked with him in his great enterprises, from the highest to the lowest, for their comfort and well being, and no one enjoyed greater loyalty and respect from his associates and employees.
It has seldom been given to one man to see the well ordered success of his life work so completely' realized, leaving it, as he did, with the knowledge that he had earned and received the genuine love and respect of all who knew him.
To us who worked with him, his life is now a splendid memory which we will carry with us as an inspiration to the end of our days.
XXU PROCEEDINGS OF THE MILWAUKEE MEETING
PROCEEDINGS OF THE ONE HUNDRED EIGHTEENTH MEET- ING OF THE INSTITUTE, MILWAUKEE, WIS.
The 118th meeting of the Institute was held at the Milwaukee Auditorium, on Tuesday, Oct. 8, to Thursday, Oct. 10, inclusive, 1918, under the joint auspices of the Committee on Iron and Steel (Chairman, Prof. J. W. Richards), and the Institute of Metals Division (Chairman, William M. Corse), and simultaneously with sessions of the American Foundrymen's Association and of the American Malleable Castings Association. It was preeminently a war meeting. It was attended by 104 members of the Institute.
The social features, so far as the members of this Institute were concerned, were slight, but generous and appropriate entertainment was offered to the ladies, consisting of automobile sight-seeing trips, reception, concert and dance on Tuesday evening, a theatre party Wednes- day evening, and a banquet in the Auditorium Thursday evening, at which the speakers were Charles M. Schwab, Director General of the United States Shipping Board Emergency Fleet Corporation, Major A. Radclyffe Dugmore, and W. H. Blood, Jr., Assistant to the President of the American International Shipbuilding Corporation.
The opening session was a joint meeting with the American Foundry- men's Association and the American Malleable Castings Association, and was presided over by Benjamin D. Fuller, President of the American Foundrymen's Association. At this time Hon. Emanuel L. PhilUpp, Governor of Wisconsin, welcomed the visitors to the city. He said: You will find the people of Milwaukee and of this commonwealth hospitable and above all in complete sjmipathy with you for the splendid work you are doing, and although, as you pass through the great shops of the city some one may answer you in a foreign tongue, we are all Americans.
The uppermost thought in the minds of the American people, wherever they may assemble, is the winning of the great world war. Without that success, there might be no further reason why we should meet : someone else might tell us what we should do. But we have progressed far enough in that struggle to begin to see the end and it is our kind of an end that we are seeing. In the name of humanity, let us hope that that end will come soon; but in the meantime let us stand firmly together, let us keep the wheels turning until the last gun is fired.
Insomuch as there is every reason for beHeving that the war cannot last very much longer, it is time that we began to think of what is going to happen and what we are going to do when the war is over. I take a rather optimistic view of that time. I appreciate that some economic changes will come to us, but I do not believe that the business of the country is going to be immediately stagnated or that in the immediate future, at least, there is going to be anything hke a paralysis of industries. There is so much in waiting that must be done. One of the first demands will be the improvement of our transportation facilities. The great railroads of the country are wearing out, because it is impossible to secure the labor or the material to keep them in proper repair; but we must do more than merely repair them. The demand is going to come for cheaper
PROCEEDINGS OF THE MILWAUKEE MEETING XXIU
transportation. We are urging the young men to go upon the farms. That is right and proper. Agriculture presents the very best field for the young man returning from military service. However, the farmers of this western country are going to demand better prices than they received before the war. One of the things that can be done to help them get better prices is to furnish transportation at a minimum cost. That will necessitate the purchase of millions of tons of steel. Not only must the tracks be rebuilt and the grades cut down, but the equipment of the railroads must be renewed and the balance of the road rebuilt to meet the demands of a really first-class modern railroad. Public building is being delayed until we can better spare the labor and the material than we can now. So, as I look over the needs of the country, I cannot see why there should be any business depression for many years after the war. I do not mean to say that war prices can be maintained; perhaps they ought not to be. Gradually we must get back to the level that nor- mal times can support. However, the prospect for the future is not so gloomy. Europe is going to furnish a market for our agricultural products for some time and will demand our manufactured material. Besides, we are creating a merchant marine, which will open to us the commerce of the world.
You have assembled here for purposes of your own and, as the Gov- ernor of Wisconsin, I am glad you came to us. You brought to us your thoughts and new ideas in manufacture, in the particular line in which you are engaged, and we may be able to give you some information which will be for the mutual good. Happen what will now, let us stand to- gether as one great cooperative organization, keep the wheels going, and, as the boys sing, "Keep the Home Fires Burning."
Secretary Backert introduced the following communication from a former president of the Association:
Major R. A. Bull. — If I occupied with the American Expeditionary Forces a position of exposure to dangers and hardships, or if I performed a relatively important function in the mihtary organization in France, I would hesitate to voice my senti- ments, which in either case might be mistaken for seK-praise.
Many things must be done by the non-combatant branches of the American army in France, back of the battle lines, in what is called the Service of Supplies. Those who are doing this work make no pretensions to performing the tasks of heroes, and feel the more keenly their great obUgations to their comrades at the front, because of their own assignments in the rear. Many of them have seen, as I have, what a wreck of the yet living body can be made by the enemy's bullet, shell, bomb and gas; have witnessed the fortitude of wounded men under intense suffering; have observed the morale of our soldiers detained for treatment in the rear, keenly anxious to return to the trenches to settle the score with Fritz. Seeing all of this, and realizing how effectively he is hitting the Boche line, my respect for the Yankee fighting man, whatever may be his rank, is supreme. Many of the youths who man the guns, who carry the cold steel over the top, who bridge the streams under the enemy's fire, who minister to the wounded where they fall, are your own kinsmen. How proudly you must bear yourselves in the knowledge that those of your own flesh and blood are bearing this burden! And if perchance those whom you love must make the supreme sacrifice, how glorious a heritage their dauntless courage will leave to you!
It is always comforting to know that our own are in good hands. You have been informed through many channels that the American soldier in France is well cared for. I want to add my endorsement. The medical corps is zealous in its care for the sick and wounded, and in sanitary work. The strictest attention is given to drinking water. Troops quartered in barracks are housed with special regard for ventilation and cleanhness. In the camps in France where I have been stationed there are excellent bath houses, better than those at the camp in the states where
XXIV PROCEEDINGS OF THE MILWAUKEE MEETING
I was formerly on duty. The quartermaster corps is rendering very efficient service in procuring and distributing clothing and other supplies. In most localities, and where conditions permit, the army messes have the most wholesome food, in liberal quantities, well prepared. There is no lack of sugar, wheat flour or meat in the American Expeditionary Force, mainly due, as we realize, to the cheerful self-denial of the folks back home. Just as rapidly as our troops arrive do their supplies seem to precede them.
The American Red Cross is surpassing all its magnificent traditions. It is found everywhere in France, seeking to serve, leaving with those who have felt its influence, grateful recollections that will never fade. Its chief function of caring for those selected by fate as the victims of the enemy's instruments of torture and suffering is being performed with the greatest skill and dispatch, in superb defiance of danger to those who minister. The inspiring devotion of its hard-working, consecrated men and women will constitute one of the most glorious memories of this conflict. Linked as its activities are with every patriotic home in America, its appeal to the sentiment of the Yankee in France makes it his ideal of devoted service that never fails.
The needs of the "Armee Am^ricaine" have been thoughtfully considered apart from purely physical comforts. At the convalescent and rest camps every available means is suppUed for cheerful, wholesome entertainment and recreation, with splendid effect on the spirit of the men. By long odds the greatest single factor in maintaining, day in and day out, the morale of the American soldier is the Y. M. C. A. There is the atmosphere of a democratic club, the resort of the finest type of man that has been created — the Yankee buck private.
Tribute has been paid to the splendid work of our allies countless times. After four of the most trying years through which any nation could pass, the French maintain their poise and their vigor to a degree that is amazing. Unstinted praise is demanded by such an inspiring demonstration. The British soldier is entitled to our admiration without bounds. He has been a complete failure — as his own press-agent. As a tenacious, courageous bull-dog who quietly fights on until he or his adversary is done for, he merits our highest esteem. John Bull's allies are under an enormous obhgation to these reticent chaps who went quickly from the British Isles and Colonies to the rescue of Belgium and France, and who, without any fuss, have been doggedly seeing the thing through. Do not forget the debt of America to the British navy. And re- member that the British empire has to date furnished about 8H millions of her very best men to save democracy.
I can appropriately testify to the earnest appreciation of the men in the American Expeditionary Force for the splendid work being done by the industrial army in the states. We realize that millions of men and women and many children must labor in America that the vast numbers of her sons in Europe may have the means to finish their task quickly. And we regard those who are unceasingly rendering this service at home and who are best qualified for it, as equal in devotion to duty with those who wear the overseas cap. You reaUze that every moment of time or ounce of energy wasted in the United States increases the casualty lists of our army. Those who are going through Hell for you and me are confidently looking toward America for that supreme manifestation of speed and efficiency of which her people are capable. Being near to but not of these heroes, without credentials from them but voluntarily speaking for them as an individual, I salute you as brother-patriots, whose sole purpose now is the preservation of liberty for our own and future generations.
The following resolution pledging to the Government the united resources of the iron and steel industry was then unanimously passed^
RESOLVED, by the American Foundrymen's Association, the Institute of Metals Division of the American Institute of Mining Engineers, the Iron and Steel Section of the American Institute of Mining Engineers, the American Malleable Castings Association and the foundry equipment manufacturers of the United States m joint meeting assembled, that every resource of these alUed metal trades is again pledged to the Government not only in the production of materials for the conduct of the war, but for the accelerated manufacture of these materials to enable the Government to greatly intensify its prosecution of the war and to bring about a speedy and crushing defeat of the enemy that will lead to his abject and unconditional surrender.
The activities of the army ordnance department, especially as applied to foundry matters, were told by C. S. Koch, of the Cannon
PROCEEDINGS OF THE MILWAUKEE MEETING XXV
Section of the Production Division, Ordnance Department, Washington. Cooperation between the railroad administration and the metal-working industries was then urged in an address of this title by E. D. Brigham, manager iron ore, coal and grain traffic, United States Railroad Admin- istration, Duluth. The modern methods of transferring skill, illus- trated by mihtary films, were shown by INIajor Frank B. Gilbreth, Providence, R. I.
On Wednesday morning, the Institute of !Metals Division conducted a symposium on the conservation of tin, while the iron and steel section covered the programs of both the iron and steel and the coal and coke sessions.
On Wednesday afternoon and Thursday morning the Institute of Metals Division conducted the sessions previously announced for these occasions, dealing mainly with the metallurgy of copper, zinc, brass, bronze, and amalgams.
The plants opened to inspection by visitors to ^Milwaukee included some very large industrial concerns, such as the Allis-Chalmers ^Xlanufac- turing Co., the Bucj^rus Co., the Wisconsin Gvm Co., the Worthington Pump and Machinerj^ Corporation, and many important iron and steel foundries, as well as the pulverized-coal boiler plant of the Milwaukee Railroad and Electric Power Company.
INSTITUTE OF METALS DIVISION
The first meeting of the Institute of Metals Division was held at the close of the joint session, with Chairman W. ]\I. Corse presiding. In his address, Chairman Corse said:
The most important event of our yesiT is the affiliation of our In- stitute with the American Institute of Mining Engineers. It gives us the opportunity of meeting twice a year and of associating, in at least one of these meetings, with men representing the produce of the metals that we all use. The opportunity to study the raw material end of our business has not been afforded at our meetings heretofore and should prove of great value to our members. The affiliation with the American Institute of ^Mining Engineers gives a permanent headquarters in New York city, the use of the large engineering Hbrary in the Engineering Societies' Building, and a permanent secretarial and editorial staff. We, on the other hand, must do our part in making the meetings of our divi- sion a success, both by writing papers and by participating in the discus- sions. Our meetings are generally considered to be excellent from a discussion standpoint. Let us maintain this feature in our divisional meetings and interest in them men who are informed on subjects related in any way to the non-ferrous metal industry.
In these war times, it is particularly necessary to prepare for the re- construction period to follow by perfecting our manufacturing processes and studying the most efficient methods of transacting our particular business. Any society whose aim is educational has a duty to perform in this respect, and as we represent the non-ferrous alloy and metal industries, it is incumbent on us to see that we are informed of the best and latest practice and furnish the medium for its wide dissemination. The need for maximum production is so great at the present time that it is difficult to find time to do research work, but it seems to be very
XXVI PROCEEDINGS OF THE MILWAUKEE MEETING
necessary that we set aside some money and time in order that we may be ready to produce at the lo\\^st cost and in the most efficient manner, when the times become nonnal. Our efforts in this cUrection, through our cooperative work with the Bureau of Standards, have been halted during the war, but it is our intention to continue this cooperative work as soon as practicable.
Our Institute has been the means through which much help has been rendered to the Government and our present affiliation puts us in a position to be of maximum help in this respect. Many of our members have rendered splendid service in technical capacities to the United States, for which we are very glad.
It gives me pleasure to see the generous manner in which our men have responded to any calls made on their time and experience. Let us resolve to make our Institute of Metals Division more of a power in the metal world and to carry on our meetings in such a way that the Ameri- can Institute of Mining Engineers will feel that they have acquired an energetic and useful member in their household. I want to thank the members for the cooperation they have given me during the year and for the splendid response to our new plan of organization. May the Institute of Metals Division of the American Institute of Mining Engi- neers be a worthy member of the metallurgical family of which we are now a part.
Secretary F. L. Wolf reported that :
The Institute, on July 1, 1918, had an active membership of 337 and an associate membership of 49, making a total of 386. In the active membership are included the corporation members, each corporation having three members.
Beginning July 1, 1918, the American Institute of Metals became the Institute of Metals Division of the American Institute of Mining Engineers. The advantages of this union were explained in the letter sent to the members on April 18. We retain our identity, elect our own officers as heretofore, hold our meetings as before, at the same time and place as that held bj^ the American Foundrymen's Association and, in addition, a meeting in February, which is held at New York with the American Institute of J\Iining Engineers. By this affiliation, we secure all the advantages that are offered by one of the largest and best known scientific societies. A glance at our program will show that an excellent program has been provided by the Papers Committee of which Dr. Paul D. Merica is chairman.
The receipts and disbursements for the period of Julj^ 1, 1917 to Oct. 5, 1918 are as follows:
Receipts
Cash on hand July 1, 1917 $ 740.04
Dues 3610.50
Volumes 783 . 96
Emblems 21 . 00
Interest 2 . 00
Refund from Rumford Pre.ss 19 . 25
Rental of Electros to Metal Industry 5 . 00
A. F. A 250.00
Miscellaneous .37
$5432.12
PROCEEDINGS OF THE MILWAUKEE MEETING XXVU
Disbursements
Printing including Postage S3202.98
Postage 114.15
Salaries 1025.00
Office SuppUes 19.91
Refunds 60.25
Bond 2.50
Insurance 37 . 62
Convention 236. 10
Miscellaneous 25 . 49
Exchange 7.85
Cash on hand Oct. 5, 1918 710.27
$5432.12
As officers for the ensuing year, the nominating committee, consisting of GwUliam H. Clamer, chairman, J. L. Jones, and Alfred Frank, recom- mended the following, for whom the Secretary was instructed to cast the ballot: Chairman, W. M. Corse, Ohio Brass Co., Mansfield, 0.; secretary-treasurer, F. L. Wolf, Ohio Brass Co., Mansfield, 0,; vice-chair- men, who will also form the executive committee, Wm. B. Price, Scovill Mfg. Co., Waterbury, Conn. ; George K. Burgess, Ph. D., Bureau of Stand- ards, Washington, D. C; Harold J. Roast, James Robertson Co., Ltd., Montreal, Can.; C. H. Bierbaum, Lumen Bearing Co., Buffalo, N. Y.; W. A. Cowan, National Lead Co., Brooklyn, N. Y,; Sir Robert A. Had- field, 22 Carlton House Terrace, London, Eng, ; W. K. Frank, Damascus Bronze Co., Pittsburgh, Pa.; C. H. Mathewson, Ph. D., Sheffield Scien- tific School, New Haven, Conn.; Zay Jeffries, Ph. D., Aluminum Castings Co., Cleveland, 0.; W. H. Bassett, American Brass Co., Waterbury, Conn.
TECHNICAL SESSIONS Institute of Metals Division
One session of the Institute of Metals Division was held on Tuesday morning, October 8, Mr. W. M. Corse presiding. The following papers were presented:
The Metallography of Tungsten. By Zay Jeffries. (Presented by the author; discussed by Sir Robert Hadfield, J. C. W. Humfrey, P. D. Merica, and the author.)
Notes on Babbitt and Babbitted Bearings. By Jesse L. Jones. (Presented by the author; discussed by G. H. Clamer and the author.)
The second session was held on Wednesday morning, October 9, Mr. W. M. Corse presiding. The following papers were presented:
Constitution of the Tin Bronzes. By S. L. Hoyt. (Presented by P. D. Merica; discussed by C. H. Bierbaum.)
Oxygen and Sulfur in the Melting of Copper Cathodes. By S. Skowronski.
Relation of Sulfur to the OverpoUng of Copper. By S. Skowronski.
(Both papers were presented by W. H. Bassett, and discussed by F. Johnson (written), G. H. Clamer.)
Pure Carbon-free Manganese and Manganese Copper. By Arthur Braid. (Pre- sented by the author; discussed by W. H. Bassett, G. H. Clamer.)
XXVm PEOCEEDINGS OF THE MILWAUKEE MEETING
The third session, a symposium on the conservation of tin, was held on Wednesday morning, October 9, immediately following the session scheduled above, and was continued on Wednesday afternoon. Mr, G. C. Stone was in the chair. The following papers were presented:
Babbitts and Solder. By G. W. Thompson. (Presented by W. A. Cowan.) Bronze Bearing Metals. By G. H. Clamor. (Presented by the author.) Pennsylvania Railroad Anti-friction and Bell Metals. By F. M. Waring. (Pre- sented by W. M. Corse.)
Solder, Its Use and Abuse. By M. L. Lissberger. (Presented by the author.) The Tin-plate Industry. By D. M. Buck. (Presented by the Chairman; dis- cussed by G. H. Clamer, J. W. Richards.)
The Aluminum Bronze Industry. By W. M. Corse. (Presented by the author.) Bronzes, Bearing Metals, and Solders. By G. K. Burgess and R. W. Woodward. (Presented by P. D. Merica; discussed by G. H. Clamer, R. T. Roberts.)
Cadmium Resources of the United States. By C. L. Siebenthal. (Presented by P. D. Merica; discussed by M. L. Lissberger, C. W. Hill, F. F. Colcord.)
The fourth session was held on Wednesday afternoon, beginning at the clpse of the symposium on tin, Mr. W. M. Corse presided. The following papers were presented.
The Volatility of the Constituents of Brass. By John Johnston. (Presented by the author; discussed by J. W. Richards.)
The Effect of Impurities on the Hardness of Cast Zinc or Spelter. By G. C. Stone. (Presented by the author.)
Dental Amalgams. By A. W. Gray. (Presented by the author, and illustrated by lantern slides.)
The fifth session was held on Thursday morning, October 10, Mr. G. C. Stone presiding. The following papers were presented:
Electrolytic Zinc. By C. A. Hansen. (Presented by title. Written discussions by J. L. McK. Yardley and the author.)
The Condensation of Zinc from its Vapor. By C. H. Fulton. (Presented by C. C. Nitchie; discussed by E. E. Thum.)
The Action of Reducing Gases on Copper. By N. B. PilUng. (Presented by the author.)
Notes on Non-metallic Inclusions in Bronzes and Brasses. By G. F. Comstock. (Presented by title.)
Fusible Plug Manufacture. By G. K. Burgess and L. J. Gurevich. (Presented by title.)
Application of the Spectroscope to the Chemical Determination of Lead in Copper. By C. W. HiU and G. P. Luckey. (Presented by C. W. Hill.)
Radium. By R. B. Moore. (Presented by title. Written discussion by W. A. Schlesinger.)
Iron and Steel Section
The session of the Iron and Steel Section was held on Wednesday morning, October 9, Dr. J. W. Richards presiding. The following papers were presented :
The Engineering Work of the National Research Council. By H. M. Howe. (Presented by John Johnston.)
The Limonite Deposits of Mayaguez, Mesa, Porto Rico. By C. R. Fettke and Bela Hubbard. (Presented by title.)
The Manufacture of Ferro-alloys in the Electric Furnace. By R. M. Keeney. (Presented by title. Written discussion by E. S. Bardwell, H. W. Gillett.)
The Manufacture of Sihca Brick. By H. LeChatelier and B. Bogitch. (Presented by title.)
PROCEEDINGS OF THE MILWAUKEE MEETING xxix
Notes on Certain Iron-ore Resources of the World N V 9pn+;f.r. at« +• «
May 23. 1918. (Presented by title. DiscusseS by J. ^. Richard ^ ^^'"'""^ ""^
Recent Geologic Development on the Mesabi Iron Range Minn Disri,.<;,nn
by Anson A. Betts and J. F. Wolff. (Presented by title.) ' i^iscussion
by tWe.)^^' ""'* ""^^ ^^'"^ ^^^ '^' Products. By W. H. Blauvelt. (Presented
The Use of Coal in Pulverized Form. By H R Collin<? CPrPcor^+o^ k +k
Carbocoal. By C. T. Malcolmson. (Presented by N. W. Roberts ) (fr^ZZT'ttllS^T""" °' ^""'^ "•* '°''"- Coals. b;-6. W. Traer.
, Method of Fixing Prices of Bituminous Coal Adopted by the U S Fuel Adrrin \u\^^'Xr -.J^ ^^"^^ Garnsey Jr., R. V. Norris, and J. H. Allport.' (Presence J bv" title. Written discussion by E. McAuUffe.) ^i^uiu i,x-reseniea oy
PAPERS
VOL. LX. 1.
Practice of Antimony Smelting in China
BY CHUNG TU WANG, E. M., A. M., HANKOW, CHINA (Colorado Meeting, September, 1918)
I. Introduction
China now leads the world in antimony production, having contrib- uted during recent 3'ears something over 60 per cent, of the world's pro- duction. The history of the antimonj^ industry of China dates back to 1897 when the Tai Shing Co. was formed, under contract with the Hunan Bureau of jMines, for the smelting of the ore to crude; and in 1908 the Wah Chang Mining & Smelting Co. was formed for the smelting and refining of the ore and crude to regulus. The writer was then asked to take charge of the erection and control of this first plant for regulus production in China and has, since then, been more or less connected with the anti- moivy industry in this country. This paper contains the results of many years' experience in connection with the Wah Chang ]vlining & Smelting Co., Changsha; the Pao Tai Mining & Smelting Co., Wuchow; the Loong Kee Smelting Works and the To-Cheng Smelting Works, Hankow; as well as information gathered from various other small smelters, scattered in different parts of the Provinces of Hunan, Hupeh, Kwangsi, and Kwangtung.
An idea of the growing importance of regulus production in this coun- try can be gleaned from the fact that, within a period of about 8 years, the export of regulus from Hunan alone jumped from 3 tons in 1908 to about 6000 tons in 1915; that a production of about 23,000 tons of regulus per year could easily be effected from all the smelters, as tabulated below, most of which were erected a j^ear or two ago under the stimulus of the war booms, if the price at Hankow were to stay somewhere about S900 (Mexican) per ton, half of what it was at its height, thus enabling the utilization of ores from the hinterlands of the provinces; and even under the present ruhng of prices and the closing of the less favored smelters, the production of regulus should not be less than 12,000 tons per year.
3
PRACTICE OF ANTIMONY SMELTING IN CHINA
The distribution of the number of smelters according to provinces is shown in Table 1:
Table 1.- — Distribution of Chinese Antiinony Smelters
Provinces
Number of Smelters
Approximate
Tons of Kegulus
per Day
General Remarks
Hunan. Hupeh .
Kwangtung. Kwangsi . . . .
Total.
10 4
4
2
20
36
18
6
4
The Wall Chang Co. has a ca- pacity of 20 tons per day.
The Loong Kee smelting works is the largest.
' The Pao Tai Co. is the largest.
04
II. Furnaces and Smelting Appliances
A. Shaft furnaces and condensing chambers for the volatilization process, to roast the low-grade ore or the liquation residue, generally containing 15 to 30 per cent. Sb, and to condense the volatile trioxide.
LONGITUDINAL SECTION
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LONG.ITUDINAL SECTION J-Y
Fig. 1. — Shaft furnaces and condensing chambers, Herrenschmidt t\pe.
Fig. 1 shows the Herrenschmidt type used by the Wah Chang Co. For a full description, refer to the author's book on Antimony.
Fig. 2 shows the first Herrenschmidt type put up at Changsha, 1908.
CHUNG YU WANG 5
Fig. 3 is a plan and section of the To-Cheng smelter, designed by the writer. A, gas producer. B, C, reduction furnaces, for reducing the trioxide. D, E, shaft furnaces, for roasting the low-grade ore or the liquation residue. F, G, condensing chambers.
Fig. 4 shows the water condensation compartments at the end of the condensation chambers, F and G, Fig. 3. a, suction fans, b, basin for collecting the wetted trioxide. c, iron pipe for the escape of the sul- furous fume, still holding particles of trioxide. d, wooden compart- ments, arrow sho^'ing the direction of flow of the sulfurous fume, e, wooden top of the chambers, on which is a constant flow of water, trick-
FiG. 2. — Herrexschmidt furnaces at Chaxgsha, 1908.
ling down into the chambers below, through a series of holes in the top. /, coke, g, wooden chimney.
Fig. 5 shows the shaft furnaces and condensation chambers of the Loong Kee Smelting Works.
B. Long-bedded reverberatory furnaces for dead-roasting the crude or rich ore to the stable tetroxide.
Fig. 6 shows a general type of furnace adopted by many smelters for this kind of work.
C. Reduction furnaces, for the reducing of the trioxide or tetroxide, . or for the direct smelting of crude or rich ore, to regulus.
6
PRACTICE OF ANTIMONY SMELTING IN CHINA
Fig. 7 shows a type of reduction furnace used by most of the small smelters. This furnace has a cast-iron bottom.
Fig, 8 shows a furnace similar to Fig. 7, except that the cast-iron bottom is on wheels, thus facilitating its occasional removal for relining; and that the hot air, from the passage above the roof, can be directed to the inclined grate, producing a partial gas-firing. This type was put up in the To-Cheng Smelter.
1^4^ ^^^
Fig. 3. — Plan axd section of the To-Cheng Smelter.
Z>. Miscellaneous. — Fig. 9 shows the general arrangement in the Loong Kee smelter. Note the elaborate system of flues for condensing.
III. Methods of Smelting
A. Treatment of Poor Ore, from 20 to 35 Per Cent. Sb. — The process of volatilizing roasting is always adopted to roast these products to the volatile trioxide in shaft furnaces, as shown in Figs. 1. 3, and 5, the
CHUNG YU WANG /
trioxide being condensed in different forms of condensation chambers, as already shown.
The Wah Chang Mining & Smelting Co.
(a) Volatilizing Roasting in a Shaft Furnace. — The charge consists of a mixture of 100 lb. (45.3 kg.) of ore, ranging from a peanut to a fist in size, and 15 per cent, charcoal. There are approximately two charges per hour
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FiG. 4. — Water-coxdexsatiox compartmext.s.
per furnace, depending upon furnace conditions, that is, the interval between charges must be lengthened if it is found that there is fritting of the ores inside the furnace, which must be loosened before another charge is put in. If the charge is composed of Uquation residue, the charcoal required for mixing amounts to 20 per cent, for coarse and 24 per cent, for fine. The time interval between charges is about 35 min. for charges of 50 lb. (22.7 kg.j of peanut to fine grain in size; thus the total charge per furnace per 24 hr. amounts to 2240 lb. (1016 kg.). But when the size of the residue ranges from chestnut to fist size, the charges, with the same interval of about 35 min., are then compo.sed of 80 to 90 lb. (36.2 to 40.8 kg.) of residue and 20 to 22 per cent, charcoal, thus mak-
8 PRACTICE OF ANTIMONY SMELTING IN CHINA
ing a total charge of about 3600 lb. (1633 kg.) per furnace per 24 hr. The scoria discharged is generally found to-contain about 3.5 per cent. Sb for ore and about 4.5 per cent, for residue. The average recovery per shaft furnace per 24 hr. from ore of about 25 per cent. Sb, with a total charge of 4480 lb. (2030 kg.), is shown in Table 2:
Table 2
SbaOs
From condensation chambers 1,000 lb. (453.0 kg.)
From the water-basin (on an average 20 per
cent, of the chambers) 200 lb. ( 90 . 6 kg.)
From the mam flue, 420 ft. (128.8 m.) long (on an average 2 per cent, of the cham- bers and basins) 24 lb. ( 10 . 9 kg.)
Total 1,224 lb. (.5.54 . 5 kg.)
Theoretically the trioxide should contain 83.3 per cent. Sb, but as it is always contaminated with sulfur and other impurities, it contains generally 80.5 per cent. Sb.
Hence the percentage loss in antimony is :
(0.25 X 4480) - (1224 X 0.805) , , .. (072^44~80) ^ P^^' '
Each furnace requires two workmen per shift of 12 hours. (6) Reduction of the Trioxide to Regulus. — -The reduction furnace can smelt two charges per 24 hr. of the following composition:
SbzOs 3,000 lb. (1,359 kg.)
Charcoal 600 lb. ( 282 kg.)
Soda 1501b. (70.5 kg.)
These are thoroughly mixed before being charged into the furnace. The yield of regulus per 24 hr. from 6000 lb. (2718 kg.) of trioxide is from 4100 to 4300 lb. (1858 to 1950 kg.), which is about 70 per cent., exclusive of recoveries from furnace bottoms, flue dust and slag skimming, all of which may amount to at least 5 per cent, of the regulus produced or 3.5 per cent, on the trioxide. Hence the percentage of extraction is 73.5 per cent.; i.e., the loss amounts to 7 per cent., taking the trioxide as containing 80.5 per cent. Sb. Summing up, we have a loss of about 19 per cent, of antimony from ore to regulus. The consumption of coal is 0.55 ton per ton of regulus, and the average life of the hearth bottom is 12 weeks. However, a well constructed bottom may last from 4 to 5 months. Two workmen are required per furnace per shift of 12 hours.
CHUNG YU WANG 9
The Loong Kee Smelting Works
(a) Volatilization Process. — The shaft furnace, as shown in Fig. 5, has a capacity of about 3000 lb. (1360 kg.) of Hquation residue per 24 hr. with a consumption of 20 per cent, burnt coal, recovered from the reduc- tion furnace, or 15 per cent. coke. The general practice is to sieve off the fines, to be treated separately from the lumps. Besides the usual con- densation chambers at the back of each shaft furnace, there is a main flue of 4517 ft. (1375 m.) in length, to which all the ends of the condensa-
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PLAN
LONGITUDINAL ELEVATION - SECTION
Fig. 5. — Shaft furnace and condensation chambers, Loong Kee Smelting
Works.
tion chambers are joined, leading finally to a series of gunny bags having a total length of 483.75 ft. (147.3 m.). The total wall area of the main flue, which is built of brick, is 104,395 sq. ft. (9702 sq. m.) and that of the bags is 2012 sq. ft. (188 sq. m.). The relative proportion of the amount of trioxide collected from the different parts of the whole system of conden- sation is as follows: Condensation chambers : Main flue : Bags = 1.65 : 1 : 0.09. As the furnaces treat many grades of liquation residue and ore — the scoria of the residue could be profitably re-treated only when regulus was quoted in New York at $0.45 (U. S. ) per pound — it is almost impossible to estimate the percentage extraction without having re- sorted to an elaborate system of sampling and analysis of the charges.
10 PRACTICE OF ANTIMONY SMELTING IN CHINA
As this has never been done, the following summary of a month's work is given :
Pound
Liquation residue charged, including scoria resulting there- from and poor ore 404,482
Trioxide obtained 64,033
Trioxide smelted 61,250
Trioxide used for couverture (which is equivalent to 1568 lb.
of regulus) 2,450
Trioxide loss 333
Regulus produced 39,052 . 5
Percentage extraction from oxide to regulus, 63.76 per cent.
Slag skimmings from the reduction furnace 5,728
Regulus from re-smelting of the skimmings 849
Regulus from smelting the flue dust, generally 8 per cent, of the
total regulus produced 3,210 . 4
Trioxide from the water basin 1,064
Regulus resulting from the water-basin trioxide 228 . 5
The total regulus amounts to 44,908.4 lb. (20,370.3 kg.). Hence it may be safely assumed that 9 tons of liquation residue are equivalent to 1 ton of regulus. Assuming that the average percentage of antimony in the charges be 17 per cent., the percentage loss from liquation residue to regulus would then be about 30 per cent., which, from my experience, is a close approximation.
Three workmen are required to run two furnaces per 12-hr. shift.
(6) Reduction of the Trioxide. — The reduction furnaces take five charges during 24 hr., each charge having the following composition:
Trioxide 250.0 1b. (113.3 kg.)
Charcoal 37.5 1b. (16.8 kg.)
Soda 5.0 1b. (2.6 kg.)
This mixture is divided into two portions, each being covered with 4 lb. (1.8 kg.) of soda after charging. Hence the total amount of soda required for 250 lb. (113.3 kg.) of trioxide, is 13 lb. (5.9 kg.). Sometimes the charge is not divided up; and, in that case, the charge should contain 13 lb. of soda, instead of 5 lb., and should be covered with 30 lb. (13.6 kg.) of skimmings from the previous charge, which has been mixed with 4 per cent, charcoal and 3 per cent. soda. However, often- times the skimmings from the furnaces are smelted separately with the same proportionate amount of soda and charcoal. The amount of coal required to smelt 1 ton of trioxide is about 1 ton. One workman is required per furnace per 12-hr. shift.
B. Treatment of Crude and Rich Ore. — Formerly, that is before the present war, most of the crude was exported, but since then, under the stimulus of war conditions, many small plants have sprung up in Hunan to smelt the crude into regulus.
CHUNG YU WANG
II
Wah Chang Mining & Smelting Co.
The crude is first ground into powder in a Chilean mill and is then fed into a double-deck roasting furnace, which can dead-roast 2500 lb. (1133 kg.) of crude to the stable tetroxide in 24 hr. with two workmen. In order to increase the output, a long-bedded reverberatory furnace was installed, which can dead-roast 2000 lb. (906 kg.) of crude per 24 hr. with a consumption of 700 lb. (317 kg.) of coal. Two workmen are required per furnace per shift of 12 hr. The tetroxide resulting there- from is mixed with 6 per cent, soda and 20 per cent, charcoal and is charged into the reduction furnace in the same way as in smelting the trioxide. It is claimed that a recovery of 63 to 65 per cent, is possible.
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Fig. 6. — Reverberatory roasting furnace.
The Pao Tai Mining & Smelting Co.
The reverberatory furnace, shown in Fig. 6, can dead-roast 1975 lb. (895 kg.) of crude per 24 hr., with a consumption of 755 lb. (342 kg.) of coal. Two men are required per furnace per shift of 12 hr. The roasted crude, i.e., the tetroxide, after having been mixed with 15 per cent, charcoal and 5 per cent, soda, is then charged into the reduction furnace shown in Fig. 7, which requires about 1300 lb. (589 kg.) of firewood as fuel and two men to work it, per 24 hr. Each charge contains 300 lb. (136 kg.) of tetroxide and requires 6 to 7 hr. for its smelting. On account of the poor quaUty of crude used, the average yield from crude to regulus is 57.68 per cent., including recovery from flue-dust and skim- ming. The treatment of rich ore is exactly the same as that of crude,
12
PRACTICE OF ANTIMONY SMELTING IN CHINA
except that proportionately more soda and less charcoal are required for mixing and that the fuel consumed per ton treated is correspondingly higher, as more heat is required for the fluxing of the siliceous and argillaceous gangue.
f-c 2 7 *1< 27 >+< 2 7 iw<*^9>i
SIDE ELEVATION
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FRONT END ELEVATION
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SECTION C-D BACK END ELEVATION
Fig. 7. — Small reduction furnace.
The Loong Kee Smelling Works
This is the only works in China at which crude has been smelted direct to regulus. Each furnace, shown in Fig. 8, can smelt three charges of 200 lb. (90.6 kg.) crude each, per 24 hr. with two workmen. Each charge contains the following ingredients: 200 lb. (90.6 kg.) of crude, mixed with 20 lb. (9.1 kg.) of charcoal, charged first into the furnace, then on top of the charge is spread 100 lb. (45.3 kg.) of soda, and on top of this 88 lb. (39.8 kg.) of iron scrap, preferably sheet scrap, such as waste tinned sheet. The regulus thus obtained has to be re-smelted with a
CHUNG YU WANG
13
little crude to take up any iron which may be present, sometimes as much as 9 per cent.
Any grade of ore can be smelted directly in this way, but only with proportionate increase of soda and decrease of tin scrap as poorer ores are smelted; but there must come a limit when it is prohibitive to treat any poorer ore this way on account of the amount of soda required and
Fio. 8. — Small reduction fuknace with removable bottom.
of the fuel consumed. An exceptional instance was found in this works in tlie direct smelting of the rich liquation residue, containing at most from 25 to 30 per cent. Sb, when regulus soared up to $0.45 (U. S.) per pound in 1915. In this case the charge was as follows:
Liquation residue 250 lb. (113.3 kg.)
Good soft coal 22 1b. (10.0 kg.)
Sheet-iron scrap 20 lb. (9.1 kg.)
Iron sulfide (a bj^product from the previous charges). . 10 lb. (4.5 kg.)
Soda 60 lb. (27.2 kg.)
14
PRACTICE OF ANTIMONY SMELTING IN CHINA
The time required to smelt this charge is about 9.5 hr., with a pro- duction of 46 lb. (20.8 kg.) of regulus.
C. Treatment of Natural Oxide. — The natural oxide of antimony is found mostly at one locality in Sin Hua District, Hunan, but smaller quantities are also found in Kwangsi Province. Its supply has been gradually decreasing so that, as a source of antimony ore, it is losing its importance and only a very limited quantity is now smelted by the small smelters at Changsha. The percentage content of antimony in
Fig. 9. — Plan of the Loong Kee smelter.
the hand-sorted ore, that can be treated with profit, is from 30 to 50 per cent. Its treatment in the Loong Kee Smelting Works is as follows, the charge having the following composition:
Natural oxide 100 lb. (45.3 kg.)
Soda 10 1b. (4.5 kg.)
Charcoal 13 lb. (5.9 kg.)
Of course, the amount of soda and charcoal required is increased and decreased respectively in proportion to the decreasing antimony content of the ore treated, and vice versa. The coal consumption is generally high, being approximately 5 tons to 1 ton of regulus produced for the particular grade of ore, with a percentage extraction of 33 per cent.
CHUNG YU WANG
15
In some cases when a small amount of the sulfide is so intimately intercalated with the oxide ore as to render their separation by hand impossible, the following proportions for the charge are adopted :
Natural oxide . .100 lb. (45.3 kg.)
Soft coal 91b. (4.1kg.)
Iron sulfide 5 lb. (2.3 kg.)
Soda 30 lb. (13.6 kg.)
D. Discussion of the Use of Couveriure. — As everyone knows, the market always demands good stars with fern-like structure on the slab of regulus before its acceptance. The appearance of such structure does not actually indicate the relative purity of the regulus, but is only the result of cooHng it under the cover of a properly prepared starring mixture — in the absence of a proper English term, I shall call it by its French equivalent couverture — whose fusion point is lower than that of antimony, which is 630° C. Of course, when the regulus contains impurities like sulfur, arsenic, lead or iron to any appreciable quantity, its surface shows it by specks, by a leaden appearance or by an ill-defined appearance of the fern-like structure. On the other hand, I have seen many a slab of regulus, with impurities above what are considered to be the limits imposed by buyers, whose stars are still bright and well-defined with all the appearance of well refined regulus. Now since the buyer demands such unnecessary adornment on the regulus, he has to pay for it; for the costs for starring 1 ton of regulus amount to from $10 to S60 (Mexican), according to the market price of the antimony compound used. I have worked and tried out the different mixtures for preparing the couverture shown in Table 3, which have been adopted, the one or the other, according to local conditions, by various antimony smelters in China:
Table 3. — Couverture Mixtures
|
Ingredients . |
I |
II 1 III |
IV |
1 Vi VI |
VII 1 |
VIII |
IX |
X XI 1 |
XII |
XIII |
XIV |
|||
|
Smelters using, the mixtures |
'S H o |
Pao Tai To-cheng |
M a o o |
1 O ! |
■3 0 |
c a 6 |
C 0 0 |
'3 0 c3 PM |
■5 H 0 el a. |
|||||
|
Crude (high-grade)... |
Sb2S3 |
15 |
15 2.2 |
4H |
7 |
3 to 4 |
5 |
6 |
7 |
|||||
|
Antimony tetroxide |
i=!h„n. |
24 |
24 13.2 |
30 |
14 |
|||||||||
|
20 |
18 32 |
85 |
4 to 5 |
8 40 |
7 |
16* |
||||||||
|
Potash KjCOs |
10 |
11 7.5 |
1 to 2}i |
1 1 |
||||||||||
|
1 |
3 . ... |
5 |
4 2 to 4 |
0 to G |
15 |
4 |
1 |
1 |
>2 |
|||||
|
iH |
IH. 5.7 |
H |
U 1 |
1 |
>2 |
>^ |
||||||||
|
^ |
• Pure flue dust
16 PRACTICE OF ANTIMONY SMELTING IN CHINA
The proper procedure for charging an}^ of the above mixtures is as follows: The compound, after being thoroughly mixed, is immediately charged into the reduction furnace as soon as the skimming is finished. The doors are closed and vigorous firing is maintained; as soon as it is observed that the mixture is completely melted, ladUng commences. Each ladle dips into the molten metal and, in coming out, picks up a certain quantity of the molten couverture, which, when poured out to- gether with the metal into a hot mold, completely covers the metal on all sides. Ladling must be done rapidly for each moldful — four or five ladles to one slab of regulus according to the size of the ladle used. The thick- ness of the sohdified couverture varies from 1 to 2 mm. on all sides except the top, which varies from 5 to 7 mm. The amount of couverture re- quired for each charge varies from one-sixth to one-fourth the weight of the regulus produced. It is remarkable that generally the weight' of the solidified couverture hammered off from the slab after cooling is less than the original weight of the mixture put in by about one-third, due indubitably in part to volatihzation and in part to wall-fluxing during melting. The couverture can be used over again the second or third time, sometimes with an addition of a Httle soda, until it is so contami- nated with impurities that it cannot produce any good stars. Then the wornout couverture is mixed with the ordinary charge of trioxide or tetroxide and is calculated as an equivalent amount of soda required for that charge. In connection with this, the practice at the Loong Kee and the Pao Tai smelters may be mentioned: The Loong Kee smelter uses for every 14 tons of regulus produced 1.14 tons of couverture which, according to Xo. XII of Table 3, contains 1 ton of trioxide and 0.14 ton of soda. The Pao Tai smelter uses 1 ton of couverture X^o. XIV for 14.5 tons of regulus.
E. General Discussion on Smelting. — Practically all of the shaft furnaces mentioned for the volatilization process are of the same type, except with minor differences in details as to the form of the grate- bottom and as to size. The ideal ore for treatment in such furnaces is one containing antimony from 15 to 25 per cent.; ore above 40 per cent. Sb would partly volatilize and partly liquate, and part of the Hquated product would combine with the volatilized trioxide to form an oxysul- fide compound, commonly known as antimony glass, which causes fritting at the lower zone of the furnace. Even with ore from 30 to 35 per cent. Sb, some fritting would occur, necessitating the mainte- nance of the furnace at a higher temperature than necessary for poorer ores. Hence the paradox: the richer the ore, the higher the percentage of coke required for the charge. It is possible to volatilize an ore of about 20 per cent, with 4 to 6 per cent, charcoal, the temperature being thus kept at low red-heat. On the other hand, with liquation residue, which ranges from 15 to 25 per cent., the problem is different. Here
CHUNG YU WANG 17
we have a material that loosens up at a very low red-heat, thus partially blocking up the furnace and preventing the free passage of the air upward. To remedy this, some works use a forced draft, while others use an excess of coke, amounting to 30 to 50 per cent, of the charge, thus increasing the porosity of the charge. One can frequently tell when the furnace is blockaded or when the suction fan is choked with the trioxide, espe- cially if water is introduced into it, by observing the appearance of a reddish tint in the issuing trioxide fume, which would be otherwise white with the furnace working under normal conditions. A plausible expla- nation for the appearance of this reddish tint in the otherwise white trioxide is found in the formation of the compounds Sb2S20, Sb203-2Sb2S3, Sb203-2Sb2S3-4H20 or Sb2S3-2H20. Some sulfide particles, from want of free oxygen, might be volatilized as such at temperatures above 550° C, and, taking up the moisture still in the ore, would form a hydrated sul- fide, which is red in color. Another fact, which seems to substantiate such an explanation, is that whenever a new furnace, or one which has been standing idle for some time, is started, the trioxide fume is frequently colored red at the commencement and continues so until the furnace is well under way. The explanation here is that there must be present a certain amount of moisture in the furnace, and it is this moisture that is taken up by the volatilized sulfide to form the above-mentioned red hydrated sulfide.
As to the different forms of condensation chambers, not enough data are available to enable one to decide definitely which is best. It is obvious that the elaborate flue and bag systems of the Loong Kee Smelt- ing Works should recover more of the volatile trioxide than others with- out such equipment.
One must have been struck by the comparative smallness of the reverberatory furnaces adopted for the reduction and smelting of the oxide or crude. Some of the reasons that can be enumerated for such practice are:
1. Facility in the ladling of the metal together with the couverture.
2. Comparatively small output of the smelters.
3. Cheapness of installation and of repairing.
4. The production of better stars on the slab of regulus.
Undoubtedly for such small types of furnace the fuel consumption is high ; but it is still questionable whether, in view of the above reasons, one is justified in installing reduction furnaces larger than those of the Wah Chang Works, already described.
Regarding fluxes for smelting the trioxide, tetroxide, or crude, the best flux from standpoint of higher percentage of extraction, lower con- sumption of coal and of cheapness, is soda a"=h. That this is so is indicated in Table 4, and has been borne out in my personal experience :
VOL. LX. 2.
18
PRACTICE OF ANTIMONY SMELTING IN CHINA
|
Table 4. |
• — Fluxes for Antimony Smelting |
|||||
|
Flux |
Formula |
Mole- cular Weight |
Ratio of Equiv- alent Fluxing Power |
Melting Temp., Deg. C* |
Price per Ton at Hankow, Pre-war |
Actual Price of Equivalent Amount |
|
Soda ash Common salt. . . . Potash Glauber's salt. . . . |
NasCOs NaaClj K2CO3 NasSOi + IOH2O |
106 117 138 322 |
1.00 0.91 0.77 0.33 |
920 960 1,150 1,280 |
$84 140 117 45 |
$84 154 152 135 |
* Taken from Physico-Chemical Tables, by J. Castell-Evans.
At one time, toward the end of 1915, when soda was so scarce as to command a price of about $450 per ton, several trials were made of some cheaper fluxes, such as common salt, potash, and Glauber's salt, but invariably the results obtained were unsatisfactory. Among the many experiments tried, Table 5 illustrates the proportionate amount of the different fluxes used to smelt the trioxide:
Table 5. — Amounts of Flux Required
|
1 |
2 |
3 |
4 |
|
|
Antimony trioxide |
250.0 8.0 9.5 37.5 |
250.0 6.5 3.0 3.0 6.0 37.5 |
250.0 19.0 37.5 |
250 0 |
|
Soda |
||||
|
Common salt |
||||
|
Potash |
||||
|
Glauber's salt . . . Charcoal |
37.5 37 5 |
|||
Using charges made up of the sulfide and the oxide, either trioxide or tetroxide, according to the compositions given by Herrenschmidt, Pelatan or Basse, ^ I have repeatedly obtained very poor results. We should not be surprised that this is so if we remember that chemically the sulfide and the oxide of antimony do not decompose each other, but combine to form what is known as antimony glass, which is irreducible by means of charcoal.
IV. Cost of Smelting
I shall give two detailed cost sheets, one before the war and one during the war, to show the difference in the cost of smelting as affected by the price of materials.
» C, y. Wang: "Antimony", 107, 120 and 121. London, Griffin, 1909.
CHUNG YU WANG
19
A. The Pao Tai Mining & Smelting Co. (1911). — ^Cost of materials and labor:
General labor per shift of 12 hr $0 . 233
Furnace men per shift of 12 hr 0. 25
Coal per ton 11 20
Firewood per 100 lb 0 . 30
Charcoal per 100 lb 1 . 00
Soda per 100 1b 4.00
T.\BLE 6. — Cost of Smelting Per Ton of Regulus
From Crude
From Hokong (Ore of about 34 1 Per Cent. Ext.
Crushing crude or ore
Crushing the oxide
General labor ,
Labor for roasting furnace
Coal for roasting furnace
Labor for reduction furnace . . . . Firewood for reduction furnace.
Coal for reduction furnace
Labor for mixing charges
Coal in charges
Soda in charges
Other miscellaneous labor
Couverture
$2.52 0.39 0.31 5.87
11.45 1.83
13.47 0.60 0.36 2.26 7.85
6.53
Add:
Cleaning and boxing
Iron ware
Repair to furnaces . . .
0 52 0.14 4.23
10.05 3.42
26.69 1.30 0.54 3.24
17.86 0.20
10.05
|
$53.44 |
$82.92 |
|
$5.95 |
|
|
1.64 |
|
|
1.80 9.39 |
9.39 |
$62.83 $92.31
B. The Loong Kee Smelting Works (1915).- labor:
-Cost of materials and
Coal per pound $0.0046
Charcoal per pound 0 . 017
Soda per pound 0 . 03
Coke per pound 0 . 007
Tinned scrap iron per pound 0 . 013
Antimony trioxide per pound 0.25
Labor per shift of 12 hr 0.40
20
PRACTICE OF ANTIMONY SMELTING IN CHINA
Table 7. — Cost of Smelting Per Ton of Regulus
Liquation
Natural Natural
RpsiHiiphv Direct Oxide Oxide
Vnlnfnf^a i Smelting ! about 33 about 14
tion ProcSs °^ ^rude i Per Cent. Per Cent, tionrrocess ^^ ^
Direct Smelting of Rich Sul- fide Ore 40 Per Cent Ext.
mixing
Volatilization process:
Power plant
Furnace men
Labor for spalling and
charges
Miscellaneous labor for carrying charges and discharging oxide
Coke
Reduction furnace :
Soda, charcoal, etc., for charge
Coal for reduction furnace
Furnace men
Other miscellaneous labor
Crushing oxide
Boxes, labor for cleaning regulus and for mixing charges for re- duction furnace S8 . 60
Couverture 60 . 00
$17.70 15.00
7.06
2.81 31.25
17, 21.
2.
0.
S80.00
25.00
6.60
0.20
S43 . 00
54.00
8.00
0.50
9.00
$139.20
200.00
15.00
1.50
21.00
$100.00
45.00
6.00
0.40
68.60^ 68.60 68.60' 68.60 68.60
8183.17 8180.40 8183.10 8445.30 $220.00
V. Some Suggestions for Future Improvement
Due to the lack of capital, and of mutual coordination and cooperation among the smelters and the short-sighted policy of the directors of the different companies, there has not been any marked progress in the metal- lurg}^ of antimony in China. Obviously an important line of future prog- ress should be in the direction of eliminating the heavy losses due to volatili- zation of the metal during the successive steps of treatment. To be con- servative, let us assume the total loss to be 20 per cent. ; then for an annual production of, say, 20,000 tons of regulus, the loss would amount to 4000 tons of regulus, which, at the present market price at Hankow of S300 per ton, would give an appalhng dead loss of $1,200,000 to the w^hole industiy. I do not believe that we can totally eliminate this loss, but I do believe that, with the adoption of some such proposals as outlined below, the loss could be kept down to 10 per cent., or possibly less, thus effecting an annual saving of at least $600,000, which would more than pay back the capital outlay for such alterations and additions to the existing plants.
CHUNG YU WANG 21
My proposals are:
A. Adoption of a mechanical roaster, such as the Herreshoff or the Wedge type, for roasting the crude or the rich ore.
B. Adoption of a special type of reverberatory fui-nace for the hqua-
tion process.
C. Adoption of gas-firing for the reduction furnace.
D. Adoption of the Cottrell electrical precipitation process.
E. Investigation of the possibihties of electric smelting of the oxide
or ore.
F. Investigation of the possibilities of the recovery of the sulfur from the fume by means of the thiogen process, as suggested by Prof. Young.
22 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
First Year of Leaching by the New CorneUa Copper Co.
BY HENRY A. TOBELMANN,* B. S., AND JAMES A. POTTER, f AJO, ARIZ.
Contents
Page
Introduction 22
Crashing 25
Leaching 28
Reduction 47
Electrolytic Deposition 51
Discard for Purification of Electrolyte 60
Recovery of Copper from Discard Solution 62
Resolution of Cement Copper 64
Summary 64
Appendix 66
Discussion 69
Introduction
The location, mode of occurrence of ore, and preliminary tests leading to the development of the present leaching process and the building of the present plant on the property of the New Cornelia Copper Co. at Ajo, have been described in previous papers presented to the Institute and in the discussions thereof.^ It is sufficient to say that these tests began early in July, 1912, and were continued to the close of January, 1916; that small tests at Douglas were followed by the construction of a 1-ton plant at the mine; and this was followed by the operation of a 40-ton plant for 11 mo. In all about 15,000 T. of ore were treated experiment-
* Metallurgist, New Cornelia Copper Co.
t Superintendent of Leaching Plant, New Cornelia Copper Co.
1 Stuart Croasdale: Leaching Experiments on the Ajo ores. Trans. (1914) 49, 610.
Ira B. Joraleman: The Ajo Copper Mining District. Trans. (1914) 49, 593.
L. D. Ricketts: Some Problems in Copper Leaching. Trans. (1915) 62, 737.
H. W. Mor.se and H. A. Tobelmann: Leaching Tests at New Cornelia. Trans (1916) 66,.^830.
HENRY A. TOBELMANN AND JAMES A. POTTER 23
ally during the period mentioned, and those intimately connected with the work came to the conclusion that the process finally developed was right in principle. Accordingly a 5000-ton plant has been constructed and in operation 1 year at the writing of this article. It is proposed here to describe the result of this year's work, the difficulties that have been encountered, and the steps taken to overcome them, and to give an opportunity for those interested to compare the results of the experi- ments that have been described with the actual operation of a large plant.
The plant was completed on May 1, 1917. The first charge of ore was finished on May 17, and by June 1 the great bulk of solutions in circulation had become sufficiently saturated with copper to permit the operation of the electrolytic plant. On June 18, the first car of cathodes was shipped east to be melted and cast into the finished shapes.
The process adopted was as follows:
1. Mining by steam shovels; the maximum size to be controlled by the size of a fragment that will pass the shovel dipper.
2. Transportation of the ores in cars that will stand up to the rough service and discharge freely any fragments that passed through the dip- per of the steam shovel.
3. The delivery of the ore, without any storage other than cars, directly into a crusher that will receive any fragment discharged by the car.
4. Crushing of steam-shovel size to as near 3^ in. as practicable.
5. Leaching the crushed ore 8 days by a counter-current system and upward circulation, using sulfuric acid and such ferric sulfate as is in- herent in the process.
6. Reduction by sulfur-dioxide gas of the ferric iron remaining in the neutral solutions from the leaching tanks.
7. The electrolytic deposition of part of the copper from this reduced solution, which is then returned to the leaching solution.
8. The continuous discharge of such portion of the neutral solution as is necessary to prevent accumulation of sulfates, other than copper, to the saturation point.
9. The recovery of the copper content of such discarded solution as cement copper precipitated on iron.
10. The treatment of a part of this cement copper with solution from the electrolytic tank house to the end that the copper be returned to the circulation and a part of ferric sulfate be reduced.
Crushing
The ore is mined by steam shovels and is loaded and delivered to the crushing plant in side dump cars. The crushing plant is divided into two departments, coarse and fine, which are separated by a 10,000-ton storage bin. The coarse-crushing department consists of a No. 24
24 FIRST YEAR OF LEACHIXG BY THE NEW CORNELIA COPPER CO.
Table 1. — Summary of Results. May 1, 1917 to May 1, 1918
Total tons of dry ore charged to leaching plant 1,345,000
Total number of tanks charged 269
Total copper contents, per cent 1 . 631
Soluble copper contents, per cent 1 . 577
Insoluble copper, probably present as sulfide, per cent 0 . 054
Average proportion of ore on 4-mesh screen, per cent 41 .9
Average proportion of ore through 20-mesh screen, per oent. ... Ij9.1
Total number of tanks excavated 259
Average moisture in tailings, per cent 11.1
Total copper in tailings, per cent ^; 0 . 338
Copper in laboratory washed tailings, per cent 0 . 254
Water-soluble copper in taiUngs, per cent 0 . 084
Average pounds of water-soluble copper per ton of tailings 1.6
Average number of days leached 9.7
Average gallons per minute advance through ore 1069
Circulation in tank, gallons per minute 4500
Average specific gravity of neutral advance 1 .344
Average free sulfuric acid going on oldest ore, per cent 2.85
Average sulfuric acid in solution coming off newest ore, per cent . . 0.5
Average gallons advance per minute through towers 1005
Total iron in neutral advance to towers, per cent 2. 36
Ferric iron in neutral advance to towers, per cent 1 . 06
Ferric iron in neutral advance from towers, per cent 0.46
Number of roasters in service 3
Average tons of ore roasted per day 68 . 5
Average sulfur contents of ore, per cent 42.7
Average sulfur contents of calcines, per cent 7.1
Average sulfur dioxide in gas towers, per cent 8.1
Average sulfur dioxide in gas from towers, per cent 1.9
Average pounds of sulfur consumed per pound of ferric iron
reduced 0 . 57
Average gallons per minute through tank house 1005
Average copper content of solution entering tank house, per cent . 3.01
Average copper content of solution leaving tank house, per cent. . 2 . 53 Average copper content removed from solution through tank
house, per cent 0 . 48
Average ferric iron contents of solution entering tank house, per
cent 0.45
Average ferric iron contents of solution leaving tank house, per
cent 0.99
Per cent, of theoretical oxidation 65. 6
Average current density, amperes per square foot 6.6
HENRY A. TOBELMANN AND JAMES A. POTTER 25
Average voltage between anode and cathode 2.00
Average weight of cathode shipped, pounds 127
Number of tanks on cathodes 120
Number of tanks on starting sheets 23
Number of starting sheets made 266,453
Per cent, of starting sheets scrapped 11.4
Pounds of electrolytic copper produced 24,400,532
Total kw. hr., A. C. charged to electrolysis 34,865,096
Pounds of copper per kw. hr., A. C 0. 70
Pounds of copper per kw. hr., D. C 0 . 82
Total tons of acid (60° B. sulfuric acid) charged to plant 59,809
Pounds of 60° B. acid per ton of ore leached 90 . 3
Pounds of 60° B. acid per pound of copper dissolved 3.56
Pounds of 100 per cent, acid per pound of copper dissolved 2.76
Average pounds of copper dissolved per ton of ore leached 26 . 06
Average per cent, of total copper dissolved 79 . 89
Per cent, of total copper into process shipped as electrolytic cop- per 53.70
Per cent, of total copper into process shipped as cement copper . . 15.13
Per cent, of total copper tied up in process 10.00
Per cent, of total copper produced as electrolytic 75.33
Per cent, of total copper produced as cement 24 . 67
Per Cent.
Total pounds of copper to process 43,847,000 100.00
Total pounds of copper produced 32,392,565 73.88
As electrolytic 24,400,532 lb.
As cement 7,992,033 lb.
Total pounds of copper in solution May 1, 1918 1,902,768 4.34
Total copper unrecovered,
In tailings as insoluble copper 6,381,242 14.55
In tailings as water-soluble copper 2,110,332 4.81
. Unaccounted for 1,060,907 2.42
gyratory crusher set on a high concrete pedestal. Four No. 8 crushers of the same type, two on each side, receive the product from the large crusher and reduce it to about 4-in. (101 mm.) cubes. This product is taken by two 36-in. (91 cm.) conveyors to the storage bins. The con- veyors have magnetic head pulleys; there are also powerful 53-in. (134 cm.) magnets hung over each belt.
The superstructure provides a runway and a 40-ton crane is installed over a No. 24 gyratory crusher for handling parts in repair and for breaking jams in the bowl of the crusher. The 10,000-ton storage bin between the coarse and fine crushers is of steel built on an elevated reinforced-concrete platform. It is flat-bottomed and the ore is drawn
26 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
from it automatical!}' onto a set of four 20-in. belt conveyors, equipped with magnetic head pulleys, which deliver the ore to four units of Symons 48-in. vertical-shaft disk crushers. Each unit consists of three crushers, which are interchangeable in every respect. The first is set to crush to inch cubes. The material so crushed is elevated and screened ; the undersize by-passes the remaining two crushers, which are set in parallel. The oversize passes to these two crushers which are set to crush to the desired size. The entire product is fed to a system of belt conveyors, which lead through a sampling plant to the leaching vats, which furnish the only storage for the crushed ore. The disk crushers are run by direct-connected 7o-hp. alternating-current motors at 400 r.p.m. The pinion shaft is long, permitting the motors to be set in a separate room, thus being protected from dust.
In determining the proper size to which ore should be crushed for leaching, two main ideas are kept in view, crushing for extraction and crushing for percolation. The coarser the product, and the smaller the amount of fines, the freer the circulation will be; but the extraction will tend to vary with the size of the particles. The finer the ore is crushed the higher the extraction will be until such fine crushing materially inter- feres with the circulation of the solutions. The more uniform the prod- uct the better the circulation will be, and, other things being equal, the higher the extraction. The ore used in early leaching tests was crushed by rolls that produced a large amount of fine material. Later a Symons vertical 48-in. disk crusher was used; Symons disk crushers were in- stalled in the 5000-ton plant.
Table 2 gives screen analyses of the ore crushed at Ajo during the first 3'ear and represents the analyses on about 1,345,000 T. of ore. The fracture planes of the porphyry are such that the ore has a tendency to break into thin flat pieces, so that the leaching product is better than the screen tests indicate. All fracture planes in the Ajo ore contain more or less malachite and, as a result of crushing, the fine material contains more copper than the coarse. The screen analysis in Table 3, representing a sample from 150,000 T. of ore treated during the month of March, 1918, shows the distribution of the copper values.
The mine is operated in two 8-hr. shifts and the coarse-crushing plant is necessarily operated for the same length of time, there being no storage between the plant and the mine. The fine-crushing plant is run from 3 p. m. to 7 a. m., during which time the charge for a 5000-ton tank is crushed; but as there is a storage bin between the two crushing plants the fine plant can be operated for the full 24 hr. if necessary. Serious trouble has been experienced froi^ the fine dust in the crushing plant. This nuisance has been somewhat abated by wetting down the ore on the cars as it comes from the mine, and a dust-collecting sj-stem is now being installed in the fine-crushing plant.
HENRY A. TOBELMANN AND JAMES A. POTTER 27
Table 2. — Summary of Screen Sizing Tests for First Year of Operation
|
3 |
4 |
6 |
8 |
10 |
14 |
+ 20 |
-20 |
|
|
Month |
Mesh, |
Mesh, |
Mesh, |
Mesh, |
Mesh, |
Mesh, |
Mesh, |
Mesh, |
|
Per |
Per |
Per |
Per |
Per |
Per |
Per |
Per |
|
|
Cent. |
Cent. |
Cent. |
Cent. |
Cent. |
Cent. |
Cent. |
Cent. |
May I 25.8
June 15.5
July 20.6
August 24.7
September 26 . 9
October 23.3
November 28 . 9
December 41.4
January 37 . 6
February 30.0
March 24.3
April 19.8
Average 26 . 3
Extremes — j
Charge No. 144 (1917) 56.6
Charge No. 15 (1917) 7.6
Charge No. 85 (1917) 16.1
40-ton Test Plant:
Average 290 charges 9.7
18.8 18.6 18.8 16.0 17.5 17.8 16.9 13.2 12.6 14.7 15.4 17.1 16.6
9.6
15.2 11.3
14.2
I 15.7
; 14.9
12.2
13.2
13.9
12.4
9.7
10.8
j 11.9
: 13.9
' 13.5
12.8
6.6 19.5 12.2
9.7 11.7 9.7 8.6 9.1 9.5 8.5 7.2 7.3 8.5 9.0 9.9 9.1
7.2 8.1 7.5 7.0 6.9 7.2 7.1 5.2 6.1 6.8 7.6 7.6 7.0
5.0 4.0
14.3 [10.1
9.9 9.0
4.1 5.5 5.2 5.3 4.9 4.5 4.9 4.1 4.5 4.8 5.6 5.6 5.0
3.6
4.2 4.1 4.4 3.8 4.2 3.8 3.3 3.8 3.7 4.9 4.8 4.2
16
20
19
21
17
19
17.5
15.9
17.2
19.4
19.3
21.7
19.0
3.1 2.3 12.8
5.2 5.2 22.9 7.1 6.0 : 28.4
21.0 20.0 14.1 ; 8.0 6.0 \ 4.2
17.0
Table 3. — Screen Analysis of Ore Treated During March, 1918
|
Mesh |
Per Cent. |
Copper, , Per Cent. i |
Mesh |
Per Cent. |
Copper, Per Cent. |
|
|
On 3.. |
... 24.3 ...: 15.4 ... 13.9 9.0 |
1.41 1.35 1.38 1.46 |
On 10 |
7.6 5.6 4.9 19.3 |
1.50 |
|
|
On 4.. |
On 14 |
1.61 |
||||
|
On 6.. |
On 20 |
1.71 |
||||
|
On 8.. |
Through 20 |
2.03 |
||||
Calculated — 1.548 per cent, copper Actual analyses — 1.530 per cent, copper
The ore, as finally crushed, is conveyed by a system of 28-m. (71 cm.) belt conveyors through an automatic sampling plant and thence con- tinuously to the leaching plant. There are twelve leaching tanks arranged in two parallel rows of six each. The aisle between the two rows of tanks is 108 ft. (32.9 m.) wide and contains what is known as the central structure. This so-called central structure consists of six heavy reinforced-concrete piers supporting steel trusses that span from pier to pier. This central structure has two decks, the upper carrying the belt conveyor, the lower, the solution launders and pipe lines. Each unit pier consists of four smaller piers, each supporting a pump and its pipe
28
FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
connections. Underneath this central structure and parallel to it are two drainage launders used to carry the solutions from the leaching tanks to the solution storage.
Leaching
The leaching tanks, 88 ft. (26.8 m.) square and 17 ft. 4 in. (5.28 m.) deep inside, are built of reinforced concrete with wooden bottoms. These have a capacity of 5000 T. each of crushed ore. The walls are 9}/^ in. (24.1 cm.) thick and are strengthened outside by concrete buttresses. The bottom is of 3 by 8-in. (7.6 by 20.3 cm.) Oregon pine laid edgewise, and is supported by concrete foundations. The sides and launders of the tanks are lined with 8-lb. (3.6 kg.) lead and the bottom with 6-lb. 4- per cent, antimonial lead. The filter bottom is laid over the lead bottom and consists of 5 by 12-in. (12.7 by 30.4 cm.) joists on edge laid on 16-in.
Fig. 1. — Leaching tanks and excavator, New Cornelia Copper Co.
(40.6 cm.) centers, covered with 2-in. ship-lap planks that are bored with %-in. (9.5 mm.) holes on 2-in. (50.8 mm.) centers countersunk from below. Under the center of the filter bottom, and at right angles to the wooden floor joists, there is a distributing launder 5 ft. (1.5 m.) wide by 2 ft. 9 in. (0.8 m.) deep, set in the floor through which the solution enters and from which it is distributed under the filter bottom. The lead lining on the sides of the tanks is protected from abrasion by a covering of 2-in. planks held in place by 6 by 8-in. (15.2 by 20.3 cm.) vertical posts clamped at the bottom and top. At the top and sides of each leaching tank are two overflow launders extending the length of the
HENRY A. TOBELMANN AND JAMES A. POTTER
29
tank, one end being connected with the suction of a circulating pump. The charging is done by means of a machine especially designed for this plant and known as the spreader bridge; it consists of a traveling bridge of structural steel which spans the tanks and travels, as desired, lengthwise with the row. The bridge supports a 28-in. (71.1 cm.) belt conveyor, which receives the crushed ore from the belt on the central structure. A tripper on this belt spreads the ore in the leaching tanks. At the present time the tanks are charged by filling to the top of the tank at one side, allowing the ore to assume its natural slope, or about 45°, and then continuing at one side and discharging the ore at the top of the slope, allowing the coarser material to run to the bottom and the finer to remain somewhat higher up, thus giving a rough classification.
Fig. 2. — Leaching tanks and roasters, New Cornelia Copper Co.
The bridge is moved slowly forward as the filling of the tank progresses. This plan was suggested by the engineers of the Chile Copper Co., who have obtained the best results through this method of filling.
The crushed ore is leached from six to eight days by a counter-current system and upward percolation, using dilute sulfuric acid as the principal solvent of the oxidized copper minerals.
The solution in each tank is circulated by two 15-in. (38.1 cm.) vertical- centrifugal pumps of 3500 gal. (13,248 1.) per min. capacity each. These are driven by direct-connected 40-hp. vertical motors. The head against which the pumps work is 28 ft. (8.5 m.), which is virtually equivalent to the friction head of the solution passing through the ore. The discharge from one of these pumps is provided with a by-pass which permits a portion of the solution to be advanced to the next tank. Both pumps are
30 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
throttled to give a circulation of about 4000 to 5000 gal. per min. through the ore. Of this amount about 1000 gal. (3785 1.), called the solution advance, is continuously passing through from tank to tank. The high- acid solution (3 per cent, free sulfuric acid) coming from either or both the tank house and the solution storage and going on the oldest ore, is called the "acid advance." The nearly neutral solution coming off the newest charge and going to the reduction towers is known as the "neutral advance."
Cycle of Leaching Operation
To understand more clearlj^ the various operations taking place dur- ing a leach cycle, the accompanying flow sheet for a day's operation should be followed. The arrangement of the piping and launders permits the advance of solution in but one direction, clockwise. The tanks are also charged in this order. Of the twelve tanks, eleven are used as leaching tanks and one as a solution settler. Of the eleven tanks, seven always con- tain ore in the process of leaching. Referring to flow sheet, Fig. 4, if we assume the ore in tank 10 to be the oldest and that in tank 5 to be the newest in circuit, then tank 6 is being charged with ore, tank 7 is empty, tank 8 is being excavated, and tank 9 is in the various stages of washing and draining.
When the charging of tank 6 has been completed and the tank is ready for the leaching cj'cle, the acid advance is increased to the maxi- mum (2000 gal, per min. for 4 hr.) by the addition of solution from the storage tanks A or E. Meanwhile the usual advance of about 1000 gal. per min. continues to go from tank 5 to the reduction towers and the excess solution is advanced to tank 6 until the ore is covered; this is to prevent any interruption in the solution flow to the towers. When the ore is covered this additional advance is cut off and the normal advance resumed. The solution on the new charge is now circulated on itself for about 4 hr., or until clarified. Tank 6 is now put into circuit and the neutral advance to the towers comes off tank 6 in place of tank 5.
The leaching of the ore in tank 6, now begun, continues for 7 da3's, during which period the free acid in the solution has varied from 0.5 per cent, on the first day to 3.0 per cent, on the seventh. To show the acid concentrations during a leach cycle, the daily analyses of the solution going on each day were averaged for some 18 consecutive charges. The results were as follows:
Per Cent.
Free H2SO4 going on the ore the seventh day 3.0
Free H2SO4 going on the ore the sixth day 2.6
Free H2SO4 going on the ore the fifth day 2.2
Free H2SO4 going on the ore the fourth day 1.9
Free H2SO4 going on the ore the third day 1.6
Free H2SO4 going on the ore the second day 1.2
Free H2SO4 going on the ore the first day 0.9
HENRY A. TOBELMANN AND JAMES A. POTTER
31
oooo
32 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
At the end of the seventh day, the acid advance from the tank house is transferred from tank 10 to tank 11. Upon the entrance of a new charge into the circuit tlie solution remaining in the oldest tank is drained to the solution storage, where it is standardized with acid and is later used as acid advance. After thorough draining, the tank is ready for the wash water.
As the copper entrained in a charge after leaching is about one-third of the total copper dissolved, the question of thorough washing is very important. Four successive wash waters with drainings are used. During the 3 hr. circulation that each wash is given, an equilibrium be- tween the dissolved copper in the tailings and that of the wash water being applied is expected to be reached. To follow more readily the method of washing a charge, the flow sheet is referred to. When tank 9 has been thoroughly drained, the charge is covered with wash water from wash-water tank 1, circulated, and then drained to solution storage tank A or E; this constitutes the first wash. The charge is now covered with wash water from wash-water tank 2 and similarly circulated, and then drained into wash-water tank 1. In the same manner, the wash water from wash-water tank 3 is put on, circulated, and drained. The fourth or last wash, consisting entirely of fresh water, is pumped, circu- lated, and drained into wash-water tank 3.
In this manner the fourth wash of any one charge is used as the third wash of the succeeding charge, the third used as the second, and the second as the first. In other words, each wash water is used four times, the copper contents increasing each time, when it is incorporated into the system to make up the continuous losses of solution. These losses are due to evaporation, discard, and solution entrained in tailings.
The average analyses of the wash waters for ]\Iarch, 1918, were as shown in Table 4.
T.\BLE 4:.—A72aIyses of Wash Waters for March, 1918
Solution First Second , Third Fourth
j Off I Wash I Wash Wash i Wash
Free HoSO^, per cent 2 . 56
Copper, per cent 2 . 40
P'errous iron, per cent 1 . 58
Ferric iron, per cent 0 . 72
Specific gravity 1 . 30
To obtain the best results in washing a charge, the tanks should be thoroughly drained after each wash and the circulation should be limited by the time required to reach an equilibrium. As each 0.1 per cent, of cop- per in the last wash water means a loss of over 1000 lb. of dissolved copper
|
1.02 |
0.68 |
0.48 |
0.10 |
|
1.61 |
1.15 |
0.74 |
0.38 |
|
1.06 |
0..70 |
0.47 |
0.04 |
|
0.48 |
0.31 |
0.17 |
0.26 |
|
1.20 |
1.13 |
1.08 |
1.05 |
HENRY A. TOBELMANN AND JAMES A. POTTER
33
TftriK Hoo&E Retuki
UEGEMD
f? - ClWCUl-ATIt-tO Al-lO
AovftMce Ou/^os.
(J - 5ETT1.1MO Tf^r-iK Pump. P^— P>u/^o ToTAnm HoofcE, P.,-Tftr-iKHoue>e i?etu(«m Pof-io. 5,-i^&5i- SO^TowERa.
W,- WAfoM Wft-TEK Ho. I.
Wj,-V^«&" WoTER Mo.Z.
Wj,-WAe>iA Water r-to.J>.
W4.-WASM Water Mo.*..
HI?2TORrt FRocvTfet-iK. House. M«KE<Jt> SoL-lJTlOn, Ot-ID AovoMce FROnlAriKToTrariK.
• CiRcui_A-rlori On LeAOMtno
Ta,m k?>.
ADVAt~ic6 To T»tiK Hoo&e
o-oooSOi Gi«fc.
A leraowtjIl-IDiC- AXE DtR6OTI0ri
Op Fi-osrv.
34 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
per day, it is evident that the washing has not yet been perfected. Lim- ited solution storage and launder installation during the first year has made the use of a fifth wash water impracticable. Probably the best recommendation made in connection with the use of a fifth wash water was the precipitation of its copper contents on scrap iron simultaneously with its use, using the same water repeatedly until it reaches a point where ft is no longer effective. Plans are now being considered for this installation. The losses that the wash waters replace are shown in Table 5. The total is about the volume of one wash water. The average moisture in the tailings for the first year of operation was 11.12 per cent.
Table 5. — Losses of Solution
i Gallons per Ton of Ore Gallons per Day
Evaporation 5 to 10 25,000- 50,000
Discard 28 to 30 140,000-150,000
Entrained in tailings 24 to 26 120,000-130,000
Total 57 to 66 285,000-330,000
Removal of Tailings
After a charge has been washed and drained, the tailings are removed from the tank by means of a Hulett unloader. The machine was fur- nished by the Wellman-Seaver-Morgan Co., and is similar to unloaders used on the Great Lakes for unloading iron ore from boats. A heavy steel bridge on trucks spans the leaching tanks and travels their entire length. On this bridge travels a trolley carrying a walking beam, bucket leg, and bucket of 12 T. capacity. The unloader has a rated capacity of 500 T, per hr. and will generally excavate a tank of tailings in 10 to 11 hr. An engineer and an oiler are required to operate it. A description of this machine has been written by Franklin Moeller, Engineer for the Well- man-Seaver-Morgan Co.^ Two eight-car trains are released from the mine service at 4.30 p. m. for the transportation of tailings. Twenty-one to twenty-three train loads of eight cars each are required to excavate a tank. The tailings are taken to a dumping ground located about a mile from the plant. The dump is on gently sloping ground with a uniform grade of 1 per cent., the end of the present dump being about 80 ft. (24.3 m.) above the original ground.
Solution
The acid advance during the first year has varied from 869 to 1324 gal. (3289 to 5011 1.) per min. While we found that the more rapid
» Trans. (1919) 61.
HENRY A. TOBELMANN AND JAMES A. POTTER
35
r «
o
f=H
36 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
advance appeared to give better extractions, we also found that the acid consumption was greatly increased. It is of interest to note that the per cent, of free acid coming off the newest charge averaged practically the same for an advance of 869 gal. per min. as for an advance of 1324 gal. per min. To show the normal decrease in acid and increase in copper and other constituents in the solution advance in one passage through the leaching tanks, the average analyses for the month of March, 1918, are given in Table 6.
Table 6. — Analyses of Solution for March, 1918
Free sulfuric acid, per cent 3.00 0. 48
Copper, per cent 2 . 38 3 . 04
Iron as ferrous iron, per cent 1 . 57 1.61
Iron as ferric iron, per cent 0.69 0.72
Alumina, per cent 2 . 53 2 . 60
Specific gravity ■ 1 . 290 1 . 305
There were originally some 13,000,000 T. of thoroughly oxidized ore, consisting principally of malachite together with small amounts of cuprite and chrysocolla distributed through a monzonite-porphyry gangue. Of this tonnage over 10 per cent has already been treated. It came in nearly equal quantities from three widely separated parts of the orebody. From this it is reasonable to believe that equally good or better results may be expected from the remainder. The ore so far mined has been better than the sampling of the property indicated, averaging 1.631 per cent, total copper as against 1.54 per cent, reported. Occasionally small quantities of sulfides are encountered, but not enough to make it worth while to treat this ore separately. Both the total and the soluble copper content of each charge of ore bedded is determined. The differ- ence between the total copper and the soluble copper is an indication of the quantity of copper present as sulfides; for the first year of operation it was 0.054 per cent.
Comparing the analyses and assays on corresponding composite sam- ples of the ore before and after leaching, it is found that a measurable quantity of iron, alumina, and magnesia has been dissolved. Table 7 gives the analyses of the ore before and after treatment during February, 1918. A study of the table will show relative solubiHties of the various constituents of the ore in our present leaching solution. This was one of the first things to be determined in developing this process. Mr. Croasdale showed that the quantity of soluble material other than copper is comparatively small. Furthermore, comparison of the sizing tests of the ore before and after treatment shows that no appreciable physical
HENRY A. TOBELMANN AND JAMES A. POTTER
37
Table 1 .—Analyses of Ore Before and After Leaching, FehrvAxry, 1918
SiOz 67.04
Fe, total 5.05
AI2O3 12.30
CaO 0.63
MgO 1.52
Mn 0.025
S 0.05
S (sol. inH,0)
Cu, total 1.57
Cu, (sol. in HjSOi) ^ 1.51
C\i, in laboratory washed ■ tailings
69.28 4.33
11.50 0.60 1.24 0.02 0.26 0.16
i 0.28
0.22
P2O6 I 0.13
NaaO 1 . 73
K2O 3.34
TiOz 0.44
CaO as CaS04
Fe as ferrous iron 3 57
Fe as ferric iron 1 . 48
H2O 0.95
Au, ounces per ton 0 014
Ag, ounces per ton 0 161
0.110
1.60
3.31
0.48
0.27
2.05
2.28
0.93
0.014
0.157
change has taken place as a result of the solution of these constituents. A part of the regular daily laboratory work consists of making analyses of a composite of hourly samples of the solutions on and off all leaching tanks An average of the analyses of 18 consecutive charges is shown in Table 8. The results proved so interesting that 94 charges were similarly
Table 8.' — Composite Analyses of Solutions on and off Tanks
Gain in Copper
Concentration,
Per Cent.
Drop in Acid
Concentration,
Per Cent.
Converted Pounds per Ton of Ore Treated
Pounds of
Copper Dissolved
Pounds of 60° B. H-SO4 Consumed
1st day 0.094
2d day 0.138
3d day 0.111
4th day 0.108
5th day 0.098
6th day 0.063
7th day 0.015
8th day* 0 032
Total 0.659
|
0.194 |
3.66 |
9.74 |
|
0.288 |
5.37 |
14.45 |
|
0.318 |
4.32 |
15.90 |
|
0.388 |
4.58 |
19.40 |
|
0.278 ; |
3.81 |
13.85 |
|
0.350 |
2.45 |
17.55 |
|
0.394 |
0.58 |
19.60 |
|
0.394 |
1.24 |
19.60 |
2.604
20.01
130.09
* The eighth day represents the maximum acid solution.
averaged, including some charges that for various reasons were per- mitted to remain in the leaching tanks for 10 days. The results for the first eight days on these 94 charges checked very closely those of the 18 eight-day charges; therefore, a comparison will be made only
38 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
of the last four days of the leaching period. From this, it is obvious that the 0.7 lb. of copper gained per ton of ore leached on the last two days was obtained at a cost of nearly 43 lb. (19.5 kg.) of 60° B. sulfuric acid,
|
Table 9.— |
-Copper Dissolved and Acid Consumed |
||
|
Number of Charges Averaged |
Pounds of Copper Dissolved per Pounds of 60° B. Acid Consumed Ton of Ore Treated per Ton of Ore Treated |
||
|
94 |
18 1 94 |
18 |
7-day leach ! 25 . 7
8-day leach 26.9
9-day leach 27.3
10-day leach 27.6
24.8 26.0
109.2 129.6 150 . 9
172.2
112.7 130.0
and that there is a well-defined point where a high extraction is not profit- able, if it is obtained by prolonging the time of contact between ore and acid. The pounds of material dissolved per ton of ore leached and the pounds of acid consumed appeared to be as shown in Table 10.
Table 10. — Material Dissolved and Acid Consumed
Number of Days Leached
|
1 |
2 |
! 3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
|
|
Cu, lb. per ton ore leached |
3.60 |
8.75 |
14.50 |
19.11 |
22.47 |
25.00 |
26.72 |
27.93 |
28.26 |
28,65 |
|
Fe, lb. per ton ore leached |
0.00 |
0.00 |
0.00 |
0.98 |
2.28 |
4.62 |
5.70 |
6.80 |
8.42 |
9.22 |
|
AI2O1, lb. per ton ore leached |
0.00 |
0.17 |
1.69 |
1.40 |
2.29 |
2.76 |
4.61 |
7.33 |
10.22 |
13.65 |
|
MgO, lb. per ton ore leaohed |
0.00 |
0.08 |
0.58 |
i 0.63 |
1.03 |
1.24 |
2.08 |
3.31 |
4.60 |
6.15 |
|
Pounds of 100 per cent. acid used per ton of |
8.1 |
19.1 |
32.4 |
i '47.2 |
59.4 |
71.7 |
84.8 |
100.6 |
117.2 |
133.8 |
Leaching tests made on individual screen sizes in a small lead Pachuca tank holding approximately 200 lb. (90 kg.) of ore showed the rates at which the various impurities dissolve compared to that of copper. The ore was carefully screened, dried and weighed. The acid was weighed and the solution measured. The acid concentration was kept as near as was possible to that of the 5000-ton plant for the corresponding day. So far, tests have been completed on three screen sizes: Minus 0.525 in. plus 0.371 in., minus 3 mesh plus 4 mesh, and minus 6 mesh plus 8 mesh. The cumulative pounds of material dissolved per ton of ore leached are as follows:
HENRY A. TOBELMANN AND JAMES A. POTTER 39
Test I.— Minus 0.525 Plus 0.371-mesh Screen
|
Hours Leached |
||||||
|
24 |
48 |
72 |
96 |
120 |
144 |
|
|
Cu |
10.34 0.43 1 04 0.23 1.19 0.25 |
14.36 0.79 1.71 0.31 1.36 0.35 |
16.97 1.21 2.19 0.35 1.18 |
18.82 1.64 2.64 0.40 1.22 |
21.22 2.03 3.26 0.70 1.19 0.63 |
22.14 |
|
Fe |
2.57 |
|||||
|
AlaOj |
3.36 |
|||||
|
MgO |
0.80 |
|||||
|
GbO |
0.98 |
|||||
|
P2O, |
0.44 |
0.47 |
0.64 |
Test 2. — Minus 3-mesh Plus 4:-mesh Screen
|
Hours Leached |
|||||||
|
\ |
13 |
30 |
48 |
72 |
97 |
125 |
144 |
|
Cu Fe AI2O3 |
14.80 0.65 1.18 0.25 1.52 0.34 |
18.30 0.89 1.99 0.32 1.15 0.47 |
21.10 1.29 2.47 0.34 1.08 0.58 |
22.30 1.74 2.46 0.39 1.01 0.66 |
24.10 2.16 2.79 0.49 0.92 0.85 |
25.60 2.96 3 71 0.73 1.05 1.05 |
26.60 3. 90 4 08 |
|
MgO CaO PjOfi |
0 90 1.08 1.03 |
||||||
Test 3.- — Minus (\-mesh Plus 8-'-nesh Screen
Hours Leaclied
|
12 |
24 |
36 |
60 |
• 72 |
|
|
Cu |
18 ..20 |
21.10 |
22.50 |
22.60 |
23.40 |
|
Fe |
0 70 |
1.00 |
1.15 |
1.55 |
1.85 |
|
AI2O3 . |
1.G9 |
2.28 |
2.59 |
2.88 |
3.01 |
|
MgO |
0.26 |
0.34 |
0.37 |
0.31 |
0.42 |
|
CaO |
1.27 |
1.18 |
1.08 |
1.08 |
1.08 |
|
P2O6 |
0.25 |
0.37 |
0 43 |
0.76 |
0 83 |
Calculating these results so as to show the solubility of impurities, in pounds per pound of copper dissolved, we have Table 11. These results indicate that fine crushing gives the highest extraction in the least time and with the minimum acid consumption.
40 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
Table 11.^ — Impurities Dissolved per Pound of Copper
24-hr. Leach 72-hr. Leach 144-hr. Leach
Test 1
Test 2 I Test 3
Test 1 Test 2 I Test 3 Test 1 Test 2
Fe 0.042 0.043 0.044 0.071' 0.078 0.079 0.116 0.162
AUCa 0.109 0.080 0.108 0.129 0.110 0.129 0.152 0.166
MgO 0.021 0.016 0.016 0.021 0.017 0.018 0.036 0.037
CaO 0.11.5 0.102 0.060 0.069 0.045 0.046, 0.044 0.044
P2O5 0.024 0.023 0.017 0.026^ 0.029 0.035 0.029^ 0.042
Totalcopperdissolved, per cent.. 31.6 |55.6 iSO.O 51.9 174.9 jgi.S j 67.7 [89.2
Pounds of acid consumed per lb. ' ! I'll
of copper dissolved 2.0 2.0 2.4 2.3 2.2 2.7 2.4 2.6
Acid Consumption
Upon the amount of acid consumed per pound of copper may depend largely the profit to be derived from the ore. During some 300 charges, the average acid consumption for the 40-ton plant was 2.8 lb. (1.3 kg.) of 100 per cent, acid per pound of copper dissolved. This does not in- clude that part regenerated in the tank house by the electrolytic deposi- tion of copper or that obtained by the oxidation of the SO2 to H2SO4 by the ferric iron. Mr. Croasdale's experiments showed a probable acid consumption of about 3.15 lb. (1.4 kg.) of 100 per cent. H2SO4 per pound of copper dissolved. This was of course the net consumption, as there was none produced or regenerated.
The amount of new acid introduced into the system during the first year has varied from month to month. By new acid we mean that part of the acid that must be brought in from an outside source, and repre- sents only about 60 per cent, of that actually consumed in dissolving the copper in the ore; of the remaining 40 per cent., 32 per cent, is that gener- ated in the towers by the oxidation of SO2 and 8 per cent, is that regener- ated in the tank house by the deposition of copper. In the final report on the experimental work, we stated that this acid consumption on the 5000-ton plant would not exceed 3 lb. of 100 per cent. H2SO4 per pound of copper dissolved.
For the first 5 mo. of the year, both the development work at the mine and the usual troubles in starting a plant prevented the delivery of 5000 T. of ore per day. This condition resulted in many of the charges being in process from 10 to 16 days, during which time great quantities of acid were consumed and but little copper extracted. For the last 7 mo. these conditions have been continually bettered and the average acid consumption for the first year of operation is 2.76 lb. (1.25 kg.) of 100 per cent. H2SO4 per pound of copper, or 3.36 lb. (1.5 kg.) of 60° B. acid per pound of copper, while the average for the last 4 mo. is 2.75 lb. (1.24 kg.) of 60° B. or 2.14 lb. (0.96 kg.) of 100 per cent. acid.
tlENRY A. TOBELMANN AND JAMES A. POTTER
41
Approximately 60,000 T. of 60° B. sulfuric acid have been charged out to the leaching process during this first year of operation, or an average of 164.4 T. per day. During this period, some 1,345,000 T. of ore have been put into process, making an average acid consumption of 89.6 lb. (40.5 kg.) of 60° B. acid per ton of ore. The acid used is purchased from the Calumet & Arizona Mining Co. acid plant at Douglas, Ariz., and is delivered to Ajo, some 300 miles distant, in 50-ton iron tank cars at the rate of about three cars a day. Ample storage has been provided by the erection of four 1000-ton steel tanks, which permit of keeping 3500 to 4000 tons of acid in stock. A 6-in. (15 cm.) pipe line delivers the acid by gravity to the electrolytic tank house and to the solution storage.
Since the Ajo ores carry neither arsenic nor antimony, which are very deleterious impurities in cathode copper, the only other source of intro- duction for these impurities would be sulfuric acid. As the ore used for the production of the acid at Douglas carries but very small quantities of these impurities, the acid is of good quality, and there is no trouble from this source.
Table 12. — Analysis of Sulfuric Acid {Oct. 1, 1917 to Jan. 1, 1918)
|
1 Per Cent. |
Per Cent. 1 |
; Per Cent. i |
|||
|
H2SO4 |
80.86 |
Cu Pb Sb As |
0.0618 0.0032 0 0063 0.0058 |
Fe Zn Bi CI '. |
' 0.0219 |
|
N2O3 HXO3 |
(Equivalent to 61.5° B.) .... 0.0064 .... None |
0.0161 None ; None |
|||
|
' |
An analysis of three months' composite sample of the acid is shown in Table 12. The acid occasionally has a pinkish tint, which upon exami- nation was found to be due to a trace of selenium. After operating several months, a blood-red scum appeared in spots on the oil on the sur- face of the electrolyte. Anodes withdrawn at about that time showed a similar coating on the porcelain insulators. This scum or deposit was tested and found to be selenium.
To show how the acid is consumed, a typical solution analysis is given in Table 13. This is the analysis of a composite sample represent- ing solution from the whole leaching and electrolytic cycle on Dec. 27, 1917. The specific gravity is 1.319. There are about 6,000,000 gal. (22,710,000 1.) or approximately 30,000 to 35,000 T. of such solution on hand at all times throughout the plant, representing a tie-up on the average of some 900 T. of copper and 500 T. of acid (100 per cent.) . Large
42 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
as this may appear it is believed that it will not equal the quantity of copper that is tied up at the average smelter with an equal production.
|
Table 13.' — A Typical |
Solution Analysis |
||||
|
Per Cent. |
Per Cent. |
Per Cent. |
|||
|
Cu |
2 7.^6 |
P2O6 |
0.192 |
H,S04,free.. As Sb Zn Se |
1 . 500 |
|
AI2O3 |
2.758 |
CaO MnO.... CI SO3 |
.. 0.055 ..' 0.038 .. 0.012 .. 17.004 |
0 . 003 |
|
|
Fe, total Fe as ferrous |
2.456 1.511 0.945 |
1 0.002 0.033 |
|||
|
Fe as ferric |
' Trace |
||||
|
MgO |
1.420 |
The free acid in the solution going through the ore has been main- tained at practically a constant percentage during the first year, but on comparing the per cent, of copper in the tailings of charges of like size and equal time of contact with the solution, wide variations are noted. No reason could be found for many of these variations.
To determine whether the copper contents of the tailings in the different parts of a tank are uniform, several tanks were sampled, The results on two of these tanks are shown. Each train-load was sampled separately. The tailings were sampled by taking eight 8-oz. (178 gm.) scoops full from the top of each car in predetermined places. The loca- tion in the cross-section of the tank from which the different samples were drawn was recorded. Since there was a difference in the per cent, of coarse and fine material in the different parts of the tank, the amount of copper was determined only in the tailings between 3 and 4 mesh. Figures in parenthesis are the cut number, while the others give the per cent, copper in the samples from these cuts.
Charge 61, Tank 6. — This tank was charged by filling one side to the top and then advancing from the south to the north side, as shown below.
|
.20 .21 |
(1) (2) |
.23 .19 |
(4) (5) |
.20 (7) .19 (8) |
.20 .21 |
(10) _^,..--" (11) /.28 (13) |
||
|
North |
.21 |
(3) |
.19 19 |
(6) (16) |
.18 (9) .25 (17) |
.20 |
(12)/ .34 (14) / / / t |
South |
|
.23 |
(15) |
.23 (18) |
.23 (19) / .33 (20) / |
HENRY A. TOBELMANN AND JAMES A. POTTER 43
Tank charged, March 10, 2.10 p. m. Solution on, ]March 10, 6.30 p. m. Solution off, March 17, 4.00 a. m. Total time of leaching, 6 days, 9 hr., 30 min. Excavating began, 5 p. m. Finished, 4.00 a. m. Time, 11 hr. The last train-load was a general clean-up of the floor and showed 0 . 20 per cent, copper.
Copper, Per Cknt.
Average of above 21 train-loads, 4 mesh 0 . 223
Regular tailings sample, 4 mesh 0.24
Regular tailings sample, all mesh 0. 24
Sizing Test, Mesh
10
+ 20
Tailings
On, per cent. Cu, per cent.
23.80 0.44
21.90 0.24
13.30 0.15
9.10 7.50 0.14 ! 0.14
4.50 0.15
3.80 0.14
16.10 0.22
Regular head sample, per cent, copper 1.51
Copper dissolved, per cent 84 . 1
Charge 127, Tank 6.- — The tank was charged by filling both sides tx) the top and then advancing from the south to the north side, as shown in the following diagram.
|
.27 .28 .27 |
(1) (2) |
.23 .22 |
(5) (6) |
.31 .27 |
(7) .24 (10) .29 (13) (8) .25 (11) .37 (14) |
||
|
North |
{sy .23 |
.24 |
(9) .23 (12) i .31 (15) |
South |
|||
|
^ |
.<21 (22) |
.22 |
(20) |
.23 (18) |
.25(16) |
||
|
,-''.22 |
(25) .21 |
(23) |
.20 |
(21) |
|||
|
'' |
.20 (24) |
.25 (19) |
.28(17) |
Tank charged. May 14, .8.10 a.m. Solution on. May 14, 11 p. m. Solution off. May 21, 3.30 p. m. Total time of leaching, 6 days, 4 hr., 30 min. Excavating began, 5.20 p. m. Finished, 3.30 a. m. Time, 10 hr. 10 min.
The space within the dotted Unes represents the zone of highest cir- culation and hence the most intense leaching action. The close agree- ment between the average of all the segregation assays and that of the regular tailings sizing test on similar sized material indicates consistent sampling. This is further emphasized by a comparison of the head sizing test (automatic sample) and the tailings sizing test, which is a hand sample.
44 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
Copper, Per Cent.
Average of 25 train-loads, assay of 4-mesh material 0 . 25
Regular tailings sample 0.25
Sizing test on regular sample, 4 mesh 0. 27
Total copper calculated from sizing test 0 . 25
Sizing Test, i •? 4. > r sin
Mesh "^ i I '^ I ** I ^"
+ 20
Heads '
On.percent 19.60 17.30 15.00 10.40 7.60 550 4.20
Cu, percent 1.29 1.30 1.24 1.27 1.34 1 1.43; 1.44
20.40
1.86
Tailings I I
On, percent....! 14.70 20.40 14.60 10.00 8.40 5 40 4.40 22.10
Cu, percent.... 0.38 0.27 0.21 0.18 0 19 0 19 0 18 0.27
Regular head sample, per cent, copper 1 . 36
Calculated copper from sizing test, per cent, copper 1.42
Copper dissolved, per cent 81 . 60
Effect of Variation in Circulation
Charges were run with various rates of circulation, but no decided effect could be noted. Samples of ore taken from the top of a charge at regular intervals showed that where the solution had free access to the ore only 3 days were required to dissolve 80 per cent, of the copper in the ore, as against 6 days for the whole charge. These results and others lead to the belief that the crushing and the bedding of a charge so as to give the best circulation is of prime importance. In other words, the greatest care should be exercised in bedding and in regulating the circula- tion so as to prevent channeling of the solution. Upward circulation was selected because it reduces the tendency toward channeling and also effects more rapid solution of the copper.
Results obtained show that small variations in the density have no appreciable effect on the solubility of copper in the solution. In spite of the self-evident fact that a light solution is a more active lixiviant than a heavy one, a certain density must be maintained to keep the remainder of the process in balance.
At the beginning of operations the lead lining of the leaching tanks was exposed to the channeling of the ore and serious abrasion was noticed. The ore buoyed up by the heavy solution circulating at a high rate had completely worn through the lead in places. This condition was remedied by lining the tanks with 2 by 12-in. (5 by 30 cm ) planks and no further trouble has been experienced from this source. The solution was pre- vented from coming up between the plank and the lead lining by calking with oakum and asphalt. The bottoms of the leaching tanks are lined
HENRY A. TOBELMANN AND JAMES A. POTTER 45
with 4-per cent, antimonial lead, while the sides are of chemical lead. Some trouble was at first experienced from splitting at the seams, between the hard and soft lead lining. This was caused by expansion, contrac- tion, and defective burning. These seams were repaired and no further trouble was experienced. There were no important changes made either in the equipment or operation of the leaching division. The only- change of interest was the reduction in the time of leaching from the original 8-day period to that of 6 to 7 days.
Water Supply
At the time the property was taken over, the nearest known water supply in sufficient quantity for our purpose was the Gila River, some 45 mi. (72.42 km.) to the north. The development of a closer water supply was one of the important problems to be solved. A large valley about 8 mi. (12.875 km.) northeast of Ajo was selected as a likely place and two wells were drilled. In both water was found at a depth of about 600 ft. (182 m.) having a temperature of 104° F. At one of these places a two- compartment shaft was put down and a modern pumping plant installed. This shaft is now delivering 800,000 to 1,000,000 gal. (3,028,000 to 3,785,000 1.) of water per day, without any sign of decrease in volume. The pumping installation consists of a duplex double-acting high-pres- sure pump driven by a direct-connected synchronous motor. The water is pumped 6.7 mi. (10.7 km.) through a 10-in. (25 cm.) iron pipe line against a 1375-ft. (419 m.) head, including friction.
The sinking of another well, about a year later, by a rancher, some 6 mi. east of Ajo and about 12 mi. from the present well, proved the ex- tent of the water course. The water found was of practically the same temperature and analysis. This made reasonably certain a continuous and plentiful supply. In this connection a comparison of the analyses of the water at these wells will be of interest. The analyses were made ac- cording to a well-known method of boiler-water analysis and are therefore comparable, see Table 14. Samples 1 and 2 were taken during develop- ment of the present supply. The analyses were made in the Calumet & Arizona laboratory, Bisbee, Ariz. Sample 3 was taken from plant tap near the end of the construction period, after pumping approximately 100,000,000 gal. from the well; sample 4 was taken after pumping ap- proximately 400,000,000 gal., and sample 5 is water from the ranch well southeast of Ajo. The water from our main well is used for all purposes, including leaching plant, mine, railroad, and townsite. The great depth of the well and its distance from any possible sources of contamination make it an unusually good potable water. Further drifting in the present well would no doubt increase the flow should more water be required.
46 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
Table 14. — Analyses of Water in Grains per U. S. Gallon
Sample 1 4-15-14
Sample 2 5-18-15
Sample 3 11-16-16
Sample 4 4-15-18
Sample 5 3-20-17
SiOa, insoluble. FezOs + lAliOs
CaCOa
CaS04
CaCU
MgCOa
MgSOi
MgCh
NasCOa
NaS04
NaCl
3.90 0.17 3.00 none none 0.73 none none 4.34 8.52 16.93
2.71 0.11 2.20 none none 0.71 none none 4.21 7.78 16.76
2.28 1.14 1.95 none none 0.84 none none 4.95 7.70 19.30
2.5? '0.05
1.90 none none
0.80 none none
5.04
7.66 14.83
2.22 0.37 2.10 none none 1.13 none none 4.71 8.99 19.11
Reduction
In the electro-deposition of copper from a sulfuric-acid solution, iron if present will consume electric energy, by its alternate oxidation and reduction, thereby reducing the quantity of copper deposited per unit of current. During the experimental work the control of the ferric iron proved one of the hardest problems to solve. A patent diaphragm-anode was tried and gave good results, but was cumbersome and difficult to keep in order. Later, tests made on a process in which iron and alumina were precipitated as hydrated oxides by the addition of roasted copper ores gave good results. This method was considered too complicated for an ore of this character. The idea was then suggested of using the natural oxides and carbonates in the ore itself as the precipitant of the ferric sulfate; in other words, the precipitation of the principal impurities in the solutions upon the charge itself. Early tests made on a small scale were very promising, but tests carried out later on a larger scale failed to give the desired results. For the first 15 or 20 days, the copper in the newest charge of ore was sufficient to precipitate all the ferric iron that was contained in the solution passing through the ore. However, as the acid concentration on each charge increased, the precipitated fer- ric iron was redissolved and eventually accumulated to such an extent that the iron in the solution was in excess of the copper available as a precipitant.
Use of Sulfur Dioxide
It was now decided to resort to SO2 reduction. The general opinion was that this was both unsatisfactory and difficult. This proved to be the case in solutions decidedly acid, but in the case where neutral or slightly acid solutions were used reduction proved quite easy. For these
HENRY A. TOBELMANN AND JAMES A. POTTER 47
tests elemental sulfur was used, as it was believed that a gas with the maximum percentage of SO2 was most essential and that a rich gas could only be produced bj^ burning elemental sulfur. Owing to lack of knowl- edge of the operation of sulfur burners considerable trouble was experi- enced from volatilizing sulfur.
In the sulfite-pulp industry large quantities of sulfur gas are pro- duced and absorbed, and accordingly the method of producing and ab- sorbing the gas used in that industry was investigated. It was found that similar trouble from volatilized sulfur was experienced when making a gas containing above 12 per cent, of sulfur dioxide from elemental sulfur. It was also found that at some plants pyrites were used and that under proper conditions a gas of 12 per cent. SO2 could be produced. The only objection in the sulfite-pulp industry to the use of pyrites was the tendency of small calcined particles to be carried into the solution and thence into the pulp. I'pon investigation it was decided to make use of the cheap and abundant supply of the high-sulfur low-copper ores of the Bisbee district.
The ore, some 75 T. per day, is unloaded from a trestle on a stock pile, underneath which there is a tunnel provided with a 24-in. (60.9 cm.) belt conveyor. The conveyor delivers the ore to a 13 by 20-in. (33 by 50.4 cm.) Blake jaw crusher, thence to a vertical-shaft 48-in. Symons disk crusher, giving a final product of about 3 mesh. A bucket elevator and a 20-in. conveyor equipped with automatic tripper delivers this crushed ore to eight hoppers situated above four Wedge roasters. These roasters are 22 ft. 6 in. in diameter, have seven hearths, and are belt- driven by 73^^-hp. motors.
The gas leaving the roasters passes through a short balloon flue to a Cottrell precipitator, where the gas is cleaned of dust before it enters the spray or cooling chamber. The precipitator has forty-eight 13-in. collector tubes and a 65,000-volt circuit is used. At the beginning of operations, the gas cooled to such an extent before reaching the precipitator that sul- furic acid vapor present was condensed and prevented efficient precipita- tion. Insulating both the balloon flue and the precipitator with magnesia covering and cement remedied this condition. The gas, now practically clean, enters a large sheet-lead chamber locally called the cooling chamber. This chamber is 14 ft. (4.2 m.) square, 94 ft. (286 m.) long, and is built of 8 lb. (3.6 kg.) lead supported on a wooden framework. There are 38 nozzles distributed over the top and sides through which "neutral ad- vance" is sprayed to cool the gas before it enters the towers. Between 90 and 100 gal. (340 and 378 1.) of solution per min. are required to sup- ply these sprays. The ferric iron in the solution used in cooling the gas is practically all reduced and the solution joins that coming from the towers. The temperature of the gas in its passage through the spray chamber is reduced from 600 to 150° F. A flue, 20 ft. (6 m.) long and 6 ft.
48 FIEST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
(1.8 m.) square, connects the spray chamber with the bottom of the first pair of towers, dividing the gas equally between them.
There are six towers arranged in pairs. Two pairs of the towers are part of the original equipment and are 40 ft. (12 m.) high and 20 ft. in diameter. These are built of sheet lead, supported on a steel fr^iiework. The top 10 ft. is made of 8-lb. lead, the second 10 ft. of 10-lb. lead, and the bottom 20 ft. of 12-lb. lead. The other pair, built during February, 1918, are 28 ft. (8.5 m.) in diameter, 40 ft. (12 m.) high, and are built of ordinary redwood tank construction, hooped together with iron rods. As an additional precaution against -gas leakage, the wooden towers are painted with asphalt and covered with three-ply roofing paper under the hoops. The towers rest upon a reinforced concrete base, provided with a lead pan. All towers are filled with boards ^g in. (9.5 mm.) thick, 11 in. (32.9 cm.) wide, and placed on edge, the width of a board apart, and in layers. Each layer is laid at right angles to the one immediately below it. The solution is distributed over the top of the towers by a system of launders provided with gas seals. Between the second and third pair of towers is a 60-in. (152 cm.) lead fan. This fan draws the gas from the roasters through the Cottrell precipitator, spray chamber, and third set of towers, and forces it through the second and first sets to the atmosphere. The temperature of the escaping gas is that of the atmosphere.
The solution (or neutral advance) to be reduced travels counter- current to the flow of gas, that is, the most reduced solution comes in contact with the strongest gas. The solution coming from the newest tank of ore is pumped to the top of the third pair of towers by a 9-iii. (21.8 cm.) 1600-gal. (6056 1.) per min. centrifugal pump. These are of the Antisell type and work against a 70-ft. head. The solution distrib- uted by launders and gas seals flows down over the filling, thus coming into intimate contact with the rising gas. At the bottom of each pair of towers there is a concrete lead-lined sump, 6 ft. deep and 50 ft. long, into which the solution flows and is then pumped through the next pair of towers. From the first pair of towers the solution is pumped to the second pair, then to the third pair, and then to the so-called settling tank whence it goes to the tank house. The purpose of this settling tank is two-fold: one, to settle out the slime; the other, to get the benefit of the additional reduction that was found to take place in a neutral or slightly acid solution on standing. That the reduction of ferric iron in solution continues for some time after leaving the towers was first pointed out by G. D. Van Arsdale, who observed it during his work with SO2 gas as a reducing agent.
A summary of the reduction data for the first year of operation and for March, 1918, is given in Table 15. The successful operation of the electrolytic plant depends, to a large extent, on the operation of the
|
7-1918 |
March, 1918 |
|
68.5 |
75.6 |
|
42.7 |
42.6 |
|
7.1 |
6.0 |
|
3.G |
4.0 |
|
0.45 |
0.10 |
|
0.61 |
0.69 |
|
57.8 |
87.3 |
Henry a. tobelmanjst and james a. pottbR 49
Table 15. — Reduction Data for First Year and for March, 1918
Average tons of sulfide ore roasted per day. . .
Average per cent, sulfur in ore
Average per cent, sulfur in calcines
Average roasters in operation
Average per cent, ferric iron in solution enter- ing towers 1 . 06 0 . 79
Average per cent, ferric iron in solution leaving
towers 0.46 0.17
Average per cent, ferric iron in solution entering
tank house
Average per cent, ferric iron reduced
Average per cent, of total iron reduced
Average circulation through towers, gal. per
min 1005 1324
Average specific gravity of solution through
towers 1 . 344 1 . 305
Average per cent, total iron in solution through
towers 2.36 2.40
Average per cent, sulfur dioxide by volume in
gas entering towers 81 9.9
Average percent, sulfur dioxide by volume in
gas leaving towers 1-9 08
Pounds of sulfur consumed per pound of ferric
iron reduced 0 . 57 0 . 40
Average tons of new acid produced per day
(estimated)
Average free acid in solution entering towers. . . Average free acid in solution leaving towers ....
reduction plant. The reduction plant should be so designed that it will be capable of reducing more ferric iron than will be oxidized during the deposition in the tank house of the maximum quantity of copper. The less ferric iron there is in the electrolyte the higher will be the current efficiency. From the data obtained during the experimental work, only 50 per cent of the theoretical tank-house oxidation took place. Based on these calculations, only four reduction towers were built. After the plant had been in operation a while it was found that the oxidation in the tank house was more nearly 70 per cent, of the theoretical and that four towers were insufficient to meet the conditions that would be imposed upon them by maximum tank-house capacity. Two more towers with a combined capacity of those already in use were then constructed.
To show the relative reduction in the various towers, an average was made of the solution analyses in and out of each tower for a period extending over one month; see Table 16. These results show the highest reduction taking place in the solution coming in contact with the gas
|
38.3 |
66.3 |
|
0.37 |
0.48 |
|
1.54 |
1.70 |
50 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
containing the lowest per cent, of SO2. This is partly due to the facts that the solution entering the first set of towers contains the lowest per cent, of free acid and the highest ferric iron content, and that these towers have the largest capacity. It is evident that the lower the density of the solution, the better will be the absorption and subsequent reduction. The lowering of the density is limited, however, by the operation of the remainder of the process; but it is believed that this fact should be con- sidered as an important point in the operation of the towers.
Table 16. — A7ialyses of Solution In and Out of Reduction Towers
Ferrous Iron, Ferric Iron, 1 RpHn^Mon Percent. Per Cent. ^"er Cent '
Neutral advance entering towers ' 1 . 61 0 . 79
Solution leaving first pair of towers ' 1 .95 0. 45 ' 49.5
Solution leaving second pair of towers ! 2. 14 0.26 27.5
Solution leaving third pair of towers 2.25 j 0.15 160
Solution leaving settling tank 2.30 ' 0.10 7.0
It is of interest to note that during the first year 33 per cent, of the total acid required in dissolving the copper content of the ore is produced in the reduction towers according to the reaction:
Fe2 (SOOs + SO2 + 2 H2O -> 2 FeS04 + 2 H2SO4
This, however, represents an increase of only 1.2 per cent, free sul- furic acid in the solution through the towers.
Electrolytic Deposition
The electrolytic tanks are housed in a structural steel building, 166 ft. (50 m.) wide and 280 ft. (85 m.) long, having sides only partly enclosed to give good ventilation. The operating floor is about 15 in. below the top of the electrolytic tanks. The floor in the aisles is of wood grating with the exception of the reinforced-concrete center aisle. The floors at the ends of the building are planks placed at the same level as those of the aisles. The electrolytic tanks are all on the same level, none in cascade.
The cellar, which is open on all sides, had an asphalt floor draining to gutters that lead to a sump at each end of the building. There is 8 ft. of headroom throughout the cellar to permit regular inspection of tanks, piping, and feed-wires.
The electrolytic tanks are arranged in banks with aisles between. There are 12 banks of 10 tanks each and 4 banks of 8 tanks each, making a total of 152 tanks. Each tank is separated from the adjacent tank by
HENRY A. TOBELMANN AND JAMES A. POTTER 51
a 3-in. (76.2 mm.) air space. All tanks are made of Oregon pine, lined with 7 lb. (3 kg.) chemical lead. The inside dimensions of the tanks are 29 ft. 7 in. (9 m.) long, 4 ft. 9 in. (1.4 m.) wide, and 4 ft. 3 in. (1.3 m.) deep. These tanks are supported on concrete columns, and are insulated by tile blocks covered with sheet-lead caps. Each tank is provided with a 4-in. clean-out plug. There are also two perforated lead diaphragms, one at each end of the tanks, to assure a uniform circulation. The inlet to each tank is fitted with a 33>^-in. diaphragm valve and a 33^-in. glazed stoneware goose-neck for insulating purposes. At the outlet end there is a lead overflow pan fitted with a 4-in. tile pipe suspended in a 10-in. lead boot connected to the discharge pipe. '
Lead Anodes
Each tank has 84 anodes, making a total of 12,768 in the tank house. The anodes are of lead containing 3.5 per cent, antimony. The average weight of a lead anode is 215 lb. (97 kg.). They are 40 by 51 by 3^ in. (101.6 by 129.5 cm. by 6.3 mm.) thick, and are suspended by two }^'i by 13-^-in. copper bars secured to the tops of the anodes. The submerged surface of all anodes is 41 by 41 in. The spacing of anodes is 4^^ ft. on centers. The distance from the bottom of an anode to the bottom of the tank is 8 in., while that of the cathode is 7 in. Short circuits are prevented to some extent by providing the anodes with eight conical glazed porcelain insulators distributed over the anode faces.
Much doubt was expressed about the life of the lead anode and some very positive statements were made regarding their probable length of life. Continuous service extending for over 1 year has failed to show appreciable oxidation. To obtain definite figures on the disintegration of lead anodes operating under such conditions as these, nine new anodes were carefully marked, weighed, and put into operation. These have been taken out at various times, weighed, and examined. During the first period of operation of 70 days, these anodes showed an increase in weight, due to oxidation, of about 0.94 lb. (0.42 kg.) per anode, or about 0.44 per cent, of the total weight. This amounted to 36 lb. (16 kg.) of lead per ton of copper deposited. During the second period of 42 days, there was an apparent loss in weight of lead; while during the third period, there was no change in weight within the limit of error in weighing. Basing calculations on these figures, it is evident that the ' oxidation of anodes will not be an important factor.
Previous to our 40-ton tests, little appeared to be known regarding the action of chlorine on lead anodes and much doubt was expressed as to the effect of small amounts of chlorine in a sulfate electrolyte. The water that was used in the 40-ton plant contained only about one-third of the amount of chlorine that is present in the water used in the 5000-ton
52 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
plant. Something over 183,000 lb. of electrolytic copper analyzing 99.73 per cent, copper and 0.042 per cent, chlorine were produced in the 40-ton plant, and when checking back on the chlorine introduced into the system, it appeared that about 65 per cent, of it was deposited with the copper. Such also proved to be the case in the 5000-ton plant. The water used for all purposes at the plant averages 0.015 per cent, total chlorine. When starting up the plant and making up leach solution, the chlorine content of the solution gradually increased from 0.015 to 0.021 per cent, when the electrolytic tank house started operations, then decreased until it reached about 0.010 per cent, where it appears to be constant.
Cathodes and Starting Sheets
There are 77 cathodes to a tank, or 9779 cathodes in the tank house, exclusive of starting-sheet blanks. The cathodes are 42 in. (106 cm.) square and are totally submerged. They are suspended upon H by l3':^-in. (12.7 by 31.7 mm.) copper bars by loops made from starting sheets. The original starting sheets weighed about 15 to 18 lb. (6 to 8 kg.) while the finished cathodes weigh 130 to 140 lb. (58 to 63 kg.). At the present time 127 tanks are used for making cathodes and about 14 to 16 days are required to produce cathodes of the desired weight.
Crane service is provided by two 80-ft. (24 m.) span 5-ton Shaw cranes, operating the length of the building, each serving one-haK of the electrolytic tanks. One section of 11 cathodes is removed' at a time and carried to the center aisle, where they are washed with hot water to remove the salts and soluble copper. They are then landed on an iron frame to facilitate the hand trucking to the freight cars. Each car is sampled by drilling every twentieth cathode in the center and in diag- onally opposite corners. All electrolytic copper, whether cathode or scrap, is shipped to the Raritan Copper Works at Perth Amboy, N. J., where it is melted, brought up to pitch, and cast into commercial shapes.
The cathodes produced have varied from 99.15 to 99.85 per cent, in copper content, the impurities being principallj^ slimes, held by mechan- ical entanglement. The greater the density of the electrolyte, the lower is the copper content in the cathodes and the greater the insoluble matter, iron, and alumina. The cathodes always contain more or less chlorine, varying from 0.05 to 0.35 per cent. There being no arsenic or antimony in the ore, and very little in the acid, the average arsenic content of the anodes is less than 0.0015 and the antimony less than 0.0005 per cent.
There are 25 tanks operating on starting sheets, each tank containing 77 starting blanks, or a total of 1925 blanks. These are located in the eight-tank banks at the north end of the building. The starting blanks are of rolled 3.5 per cent, antimonial lead 53 by 43 by }i-in. (134.6 by
HENRY A. TOBELMANN AND JAMES A. POTTER
53
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54 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
109 cm. by 6.3 mm.) and are large enough to allow a small amount of trim- ming, which is done with a squaring shear. Grooved redwood sticks are used at the edge and bottom of the blank to cut the sheet to facilitate stripping, and are found to be satisfactory. The anodes in these tanks are 3.5 per cent, antimonial lead, and are 41 by 52 by 3^^ inches. They do not have porcelain insulators, as these tend to spot the starting sheets. The spacing of anodes in these tanks is the same as in the commercial tanks. The tank construction and other details are likewise similar.
Eleven blanks are handled at one time by the crane, and placed on an iron stripping rack provided with a crawl so that the blanks can be car- ried, one at a time, to the center of the rack, where the starting sheets are removed by two strippers, one stripping from each side. After stripping, the blanks are oiled and placed on the opposite end of the rack to be returned by the crane to the tanks. Four men will strip, under favor- able conditions, 924 sheets in 5 hr. The starting sheets, after being stripped and trimmed, are looped on a standard Morrow machine.
The electrodes hang parallel to the flow of solution (or parallel to the length of the tanks) to give a free circulation of the electrolyte. This method of hanging the electrodes was first brought to our attention by the work done at the Butte and Duluth leaching plant.
Electric Arrangement
Alternate busbars extending across the tanks connect the electrodes in parallel and the tanks in series (see illustration). These busbars, placed across the tank, divide it into seven sections or cells. The inter- mediate busbars are l}^ in. (38 mm.) wide and 4 in. (101.6 mm.) deep, while the end busbars are 1 in. wide and 4 in. deep. Soldered along the top of each busbar is a triangular piece of copper, 1 9 in. high, giving a point contact to the electrode bars. Small maple blocks impregnated with linseed oil insulate cathodes and anodes from opposite busbars. These busbars are supported on insulated iron castings, which in turn rest on the tank cleats. The current for the deposition of the copper is supplied to the tank house by two identical 15,000-amp. circuits, each circuit having 76 tanks in series. This arrangement gives the maximum current density of 8 amp. per sq. ft. of cathode surface when operating under normal conditions. With an average current efficiency of 80 per cent, this means a daily gain of about 10.25 lb. (4.6 kg.) per cathode, or a total capacity of 120,000 lb. of electrolytic copper per day. The drop of potential between anodes and cathodes has averaged very close to 2.00 volts. There is a tendency for the voltage to drop during the summer due to increase in temperature of the electrolyte.
HENRY A. TOBELMANN AND JAMES A. POTTER
55
56 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
Electrolyte
The solution flow in the tank house is part of a closed circuit with the leaching and reduction plant, receiving a continuous flow of solution from them. This flow, coming always off the newest ore, then through the towers and settler, is regulated by means of weirs and has varied from 800 to 1500 gal. (3028 to 5677 1.) per min., depending on operating conditions. This volume is divided among the 16 banks of tanks, those on starting sheets getting generally a little more than those on cathodes. By this arrangement each bank of tanks on cathodes receives between 60 and 70 gal. per min. of reduced solution. Each bank unit consists of either 8 or 10 tanks, a sump, and a 9-in. (22.8-cm.) vertical type centrif- ugal pump of 1600 gal. per min. capacity. Each bank has an individual circulation of 1600 gal. per min. between it and the sump, while an over- flow arrangement provides for the return of such a portion of the electro- lyte as is equivalent to reduced solution added. Daily analyses are made of the solution entering and leaving the tank house. Since the operating conditions for the month of March were more nearly uniform for the plant as a whole, the analyses of the solution for this period is given in Table 17. The specific gravity of the solution to the tank house (neutral advance) is 1.310 and of the solution from the tank house (acid advance) is 1.305.
Table 17. — Analyses of Solution Entering and Leaving Tank House
Solution to
Tank House
Neutral
Advance,
Per Cent.
Solution from Tank House Acid
Advance, Per Cent.
Cu 2.985 2.51.3
Fe (ferrous) 2.315 1.660
Fe (ferric) 0.0S5 0.745
Fe (total) 2.400 2.405
AI.O3 2.470 2.465
MgO 1.360 1.360
Solution to Tank House Neutral Advance. | Per Cent, i
Solution
from Tank
House Acid
Advance,
Per Cent.
MnO 0.040 0.040
CaO 0.060 0.062
P2O6.. 0.130 0.130
CI 0.0123 0.0110
H2SO4, free 1.70 2.10
The current efficiency depends on the quantity of ferric sulfate pres- ent due to the reaction between ferric sulfate and metallic copper. The ferric iron content in the solution is kept as low as possible and the conditions shown are as good as can be expected. No doubt with a smaller quantity of total iron present in the solution less would be oxi- dized and it was recommended that the total iron be kept below 2 per cent. With the total iron not over 2 per cent., the ferric iron in the elec-
HENRY A. TOBELMANN AND JAMES A. POTTER 57
trolyte will probably not exceed 0.5 per cent., the current efficiency will be increased, and more acid wUl be regenerated.
At the beginning of operations in the tank house, a great deal of diffi- culty was encountered by the dropping of cathodes in the electrolytic tanks, due principally to the corrosive action of the ferric sulfate on the loops at the solution level, and on that part of the cathode covered by the ends of the loops. Corrosion at the solution line was easily remedied by raising and lowering the solution level in the electrolytic tanks, but the corrosion of the cathode sheet between the loop ends was far more difficult to overcome. Later this condition became worse with the in- crease in the ferric iron and higher temperature of the electrolyte. The dropping of cathodes not only caused bad short circuits in the tanks but made it necessary, when pulling cathodes for shipment, to pull individual sheets with tongs, which made it almost impossible to handle the daily output of cathodes. Considerable damage was also done to the lead lining of the tanks and the danger from accidents was more than usual. Numerous schemes to overcome this difficulty were sug- gested and tried, until it was found that by splitting the ends of the loop and attaching them with a Alorrow machine in such a manner that the portion of the starting sheet adjacent to the loop was exposed to the deposition of copper, not only the loop, but also the sheet built up, making a good firm joint. Since the adoption of this method no further trouble has been experienced with dropping sheets. Patents have been applied for and allowed covering this improved loop.
The average weight of copper per kw. hr., gross a. c, for the first year was 0.70 lb. (0.3 kg.). It is expected that it will be increased to 0.80 lb. for the coming year.
Since the oxidation of the ferrous sulfate diverts oxygen from the for- mation of acid, the actual acid regenerated is only about 65 to 70 per cent, of the theoretical. This again shows the importance of keeping down the oxidation to the minimum. This could be done by increasing the flow of solution through the tank house to the permissible limit, or by reducing the quantity of total iron in the solution.
It was originally recommended that the electrolyte be filtered before entering the tank house, with the idea that a purer electrolyte would give better cathodes and starting sheets; this was not done. During the first 6 or 7 mo. the solution coming off the ore went directly to and through the tower into the tank house. As the density of the solution in- creased more slime was carried from the leaching tanks to the tank house and the quahty of the copper produced deteriorated. During Novem- ber it was decided to settle the solution and one of the leaching tanks was converted for this purpose. This settHng, crude as it is, produced a notable difference in both the chemical composition and the physical character of the copper.
58 FIRST YEAR OF LEACHING BY THE NEW CORNELIA COPPER CO.
Some trouble was experienced in the tank house from anode gases. This was remedied, in the usual waj'-, by keeping a small quantity of oil on top of the electrolyte.
When there was practically complete reduction of the ferric iron in the solution entering the tank house, annoyance was experienced by sulfur dioxide being given off from the solution as it entered the tank house. During this time the free acid in the electrolyte was kept at 3 per cent, and was added prior to the entrance of the solution to the tank house. On adding the acid to the return solution from the tank house, this trouble practically ceased. The tank house was started on June 1, 1917, and has been in continuous operation since that time. On June 18, the first electrolytic copper was shipped.
A summary of the tank-house data for March, 1918, is shown in Table 18.
Table 18. — Tank-house Operation, March, 1918
Total pounds of electrolytic copper produced 3,152,800
Total pounds of electrolytic copper shipped 3,134,500
Per cent, of total copper shipped as scrap 3.9
Average weight per cathode, pounds 130
Total gross kw. hr., a. c, charged to tank house 4,141,763
Average pounds of copper produced per gross kw. hr., a. c 0.76
Average temperature of air in tank house 61 .5° F.
Average temperature of solution entering tank house 86 . 5° F.
Average temperature of solution leaving tank house 93 . 4° F.
Average current density, amperes per square foot of cathode 7.56
Average drop between anode and cathode, volts 2.08
Average advance through tank house, gallons per minute 1300
Average number of tanks on cathode copper 127
Average number of tanks on starting sheets 25
Average number of tanks to discard 20
Average per cent, copper in solution entering tank house 2.99
Average per cent, copper solution leaving tank house 2.62
Average per cent, ferric iron in solution entering tank house 0.09
Average per cent, ferric iron in solution leaving tank house 0.75
Average per cent, total iron in electrolyte 2.40
Average per cent, free acid in solution entering tank house 1.7
Average per cent, free acid in solution leaving tank house 2.1
Average specific gravity of solution entering tank house 1 .310
Average specific gravity of solution leaving tank house 1 .305
Adjoining the tank house on the west is the power house. This was designed by C. C. Moore & Co., of San Francisco, and is a structural steel building 200 ft. (60 m.) long, 126 ft. (38 m.) wide. Five 822.6-hp. Sterling boilers equipped with economizers and automatic fuel-oil control generate the steam. The steam, at 240 lb. (108 kg.) pres- sure and a total steam temperature of 520°, is delivered to one of two
HENRY A. TOBELMANN AND JAMES A. POTTER 59
turbo-generators with a normal rating of 7500 kw. each. Either of these generators is capable of handling the entire plant load. Each exhausts into a Wheeler surface-type condenser. The circulating water used for the condensers is cooled by means of a 150 X 400-ft. spray pond. By drawing water for the leaching plant from this spray pond, the salts and incrusting solids are prevented from accumulating.
All power generated is delivered to the station buses, which are en- closed in a concrete structure. Leading from these buses are ten 2300- volt feeders, the three largest carrying power to three Westinghouse motor-generator sets, each consisting of a 2400-hp. synchronous motor, direct-connected to two 170-volts,