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By Laurance Reid

HIGH compression ratios, resulting from high injection pressures and relatively low recovery process pressures, constitute a major problem, which has confronted those engaged in gas recycling for condensate production since the beginning of that practice. Despite the numerous process developments and improvements, no entirely satisfactory solution for this prob-lem has been presented to date. Often, where the residue gas from the recovery process must be recompressed for subsurface injection, there is a substantial difference between the required injection pressure and the plant-operating pressure required to produce maximum recovery of condensate. These limitations result in high compression ratios, which, in turn, neces-sitate excessive compressor investment and operating cost. As an alternative, the operating pressure may be increased in order to lessen the compressor requirements but such a saving often is purchased at the expense of decreased condensate recovery, caused by operation at the higher pressure. Regardless of the choice, the net result is a diminished return on the capital invested in the project. The goal of future development in this field must be the complete recovery of all valuable hydrocarbon components in the reservoir fluid at pressures that, regarded as compressor suction pressure, will require minimum compressor horsepower to inject the residue gas into the formation. A com-pression ratio of 1.5 has been established as an optimum for modern compressor equipment." Therefore, in order to con-form to this optimum condition, a 3000-lb. injection pressure would require that the condensate recovery process be operated at 2000 lb. per sq. inch.

Jan 1, 1940

By F. B. Plummer

THE physical properties of oil-producing sands, such as grain size, porosity, and permeability, are becoming more and more important in petroleum production engineering as oil fields are being repressured and rejuvenated. A number of excellent papers have been published recently on all three of these properties. Faucher, Lewis and Barnes1 give a com-plete survey of the work done through 1932 and contribute also much information on sands that they themselves have examined. Muskat and Botset,2 Wykoff, Botset, Muskat and Reed,3 Hurst,4 and Muskat5 have contributed a great deal to the theory and actual measurement of flow of liquids and gases through porous media. Muskat and Botset have measured the permeabilities of different sands with gases and liquids. They find that the radial is always slightly under the linear permeability. However, in most of the previous experiments small samples of the sand were used, and the method of production of fluid or gas through the sands has not been very close to actual oil-field conditions. In addition, so far as the authors are aware, no measurements of linear and radial permeabilities have been made simultaneously under exactly the same conditions. The multiple permeability apparatus described here is a part of the equipment being acquired by this laboratory for thorough investigation of the physical properties of producing sands. It possesses certain advantages for comparative studies of liquid flow. Additional data and descriptions of other instruments will follow in papers to be written later on. The essential features of the permeability apparatus are as follows:

Jan 1, 1934

By John B. Miles

THE present period of depression in the iron industry, with the resultant close approximation of the cost of production to the selling-price of pig-iron, should make the discussion of this subject at this time not only interesting but, profitable. It is possible that it may result, in the collection of data, which when added to those set forth in this paper will clearly indicate the influence of the rate. of driving a blast-furnace upon its fuel-economy. The question is not whether an excessive rate of driving (meaning a rate definitely in excess of the average rate in the United States) results in, an increase in the fuel-consumption, but rather whether a rate considerably less than the average does not result in a marked decrease in the fuel-consumption. The commercial and metallurgical sides of. this problem must be kept separate. With a large margin between the cost of production and the selling-price of pig-iron, and a plant already in operation, it is frequently profitable to sacrifice a couple of hundred pounds of fuel per ton of pig-iron in order to secure the greater gross profits resulting from a larger tonnage. When this margin decreases with a plant in operation, or when the determination of the size of a new furnace intended for a certain production . confronts the management, a clear understanding of the effect of the rate of driving upon fuel-economy becomes necessary. If it be granted that slow driving leads to low fuel-consumption, it should he borne in mind in the design of a new plant for the production of a certain tonnage that the adoption of an economical rate of driving increases only the size of the furnace proper, whereas, due to the decrease in quantity of blast required on account of the decrease in fuel burned, the stoves, the blowing-engines, the boilers and the piping may be de-

Sep 1, 1908

By J. M. Hassler

NOWHERE can there be found a more misleading statement than the old one that "Iron can be manufactured cheaper in the South." During the past decade ironmakers and users of iron have heard varied and sundry stories of the wonderful resources of the Birmingham district, including abundant ore and coal fields, cheap labor, a wonderful climate and similar industrial Utopian statements. Birmingham represents the major portion of the iron business in the South, acid as Birmingham fares so goes the iron business of the South. The intent of this paper is to shed some light on the actual conditions surrounding ironmaking in the South, especially in the Birmingham, or North Alabama, district. By a presentation of facts it is desired to point out that the "cheap iron" of the industrial South is a thing of the past, primarily because of increased labor cost and because labor is radically different in performance to what it was years ago. Also, because most of the raw materials needed in ironmaking that would be classed better than inferior are gone.

Jan 1, 1937

By Scott Turner

HOSTS of friends will rejoice that T. A. Rickard has been given honorary membership in the Institute. It might well have been done long ago, since, when one reviews distinguished services rendered by individuals to our organization and our profession, it is at once apparent that his name ranks high and that he has merited this distinction for more than three decades. Our by-laws restrict this list to twenty names; "T.A." becomes the sixteenth living member. Young engineers should particularly be pleased; Mr. Rickard has had a career rich in human interest, and full of useful suggestions to the younger men; he has given them good advice and set them a notable example; he, more than anyone else, has shown them how technical writing can be clear and concise; he has inspired youngsters to do their best; he has been their friend. No one has more first-hand knowledge of these facts than the writer of this appreciation:

Jan 1, 1935

DR. PeRsifor Frazer, Philadelphia, Pa. (communication to the Secretary):* Mr. Campbell's very interesting contribution, after complimentary mention, finally decides against the acceptance of the classification proposed by me in a paper bearing the same title and read at the Wilkes-Barre meeting, May, 1877.2 That paper was written primarily for the Second Geological

Jan 1, 1906

By H. S. Martin

The Phosphate Recovery Corporation operates three flotation plants, NOS. 1 and 2 concentrators about three miles northeast of Mulberry, Florida, and No. 3 plant at Wales, Tennessee. These plants represent the first commercial phosphate flotation operation and are also believed to be the largest nonmetallic flotation operation in the world at the present time. The details of this paper will be confined to plant No. 2, this being the newest and largest concentrator in Florida, and the flow sheet being practically the same as at plant No. 1. The No. 3 plant has been operated but a short time and has been shut down since December, 1932, on account of the decrease in phosphate rock production. The phosphate washers usually are located centrally on a known deposit so that about two hundred acres of ground can be mined economically to each washer location. The washers are moved to new areas when the distance becomes too great for economical pumping. The flotation plants are built either adjacent to a washer, so that current debris may be utilized, or on the site of a former washer where there is sufficient accumulated debris available for mining, and the flotation plants must also be moved from time to time. Most of the water used in the Florida flotation plants is recovered after passing through a circulating system where most of the fine SUSpended matter is settled out, but some make-up water is obtained from deep wells near the plant. Power is obtained from the Tampa Electric Co. through the distribution facilities of the International Agricultural Corporation. Flotation concentrate is hauled from the plant by trolley over the International Agricultural Corporation's trolley system, to the drying plant at Prairie, one mile northwest of Mulberry. Ore Treated In the pebble phosphate district of Florida, the phosphate mineral, or collophane, is usually found in horizontal beds of varying thickness

Jan 1, 1934

By David Cole

THE New Cornelia Copper Co. is mining and treating a 'monzonite " porphyry" copper deposit that is all hard rock. The oxidized surface shell, which constitutes the leachable part of the orebody, is measurably more resistent to crushing and comminution processes than is the underlying sulfide portion. The siliceous ribs running through the whole orebody are harder to crush than the main mass and there is no soft crumbly material to furnish the large volume of primary fines that features the crusher feeds of most other porphyry properties. New Cornelia ore reaches the primary crushers with a greater. proportion of large 'pieces. When the New Cornelia company first equipped its 'property, it used the following machines and flow , scheme to reduce the ore to leaching size:

Jan 1, 1925

By Robert C. Temps

The history of iron ore milling in Chile can be divided into two periods: the first, which lasted about 40 years, ended in 1952 and the second continues today. During the first period, Bethlehem Chile Iron Mines Co. was the sole shipper and El Tofo, the only mine. That situation was forever altered in 1952 when several small independent companies began to sell ore. The success of these companies triggered programs of exploration which can only be described as a "boom" during the past five years.

Jan 1, 1963

By Arthur S. Dwight

The profeseional career of Thomas Septimus Austin, who died at El Paso, Tex., Aug. 23, 1906, was contemporaneous with the growth of the silver-lead smelting-industry of the Far West, to which his talents and zeal contributed in no small degree. Born at Stratford, Conn., Dec. 7, 1853, he was the seventh son in a family of thirteen. His parents were well-to-do; and he received a thorough preliminary training at the Hopkins Grammar School, New Haven, Colin., passing thence to the Columbia School of Mines, in New York, where he was graduated in 1876. His first professional work was that of analytical chemist with a Cuban sugar company. In this position he spent a year, and, whatever else of benefit he may have acquired during that year in Cuba, he gained a facility of speech in the Spanish language which was of inestimable value in his subsequent work in Mexico and the southwestern United States. In 1877, he went to the Rocky Mountains, and, under the firm name of Murphy & Austin, opened an assay-ofice in Lead-ville, Colo., which was just then coming into public notice as a rich silver-lead camp. The next year, however, he entered the service of the Germania Smelting & Refining Co. at Salt Lake City, Utah, where he remained until 1882, first as assayer and chemist, and later as Assistant Superintendent. The Germa-nia bears the honorable distinction of being one of the first of the large " custom" lead-smelters erected in the West. Its founders may be called the pioneers of the modern lead-smeltr ing practice, and the Germania served, to a large extent, as a model for the many plants that sprang into existence during the next few years in Utah, southern Idaho, Colorado and other lead-producing districts. The formulation, for the first

Jan 1, 1908

By J. E. Burke, C. W. Mason

In attempting to study precipitation from a tetragonal lattice, using solid solutione of bismuth in tin, it was found that although a Widmanstätten pattern is observed1,4 only a qualitative analysis of the orientation relationships is possible, because of the unusual structural changes that accompany the precipitation process. Microscopical Studies Alloys were made from Chempur tin (Standard samples 42b and 426, National Bureau of Standards), and bismuth (Kahl-baum C.P.) by melting weighed quantities together under palm oil, stirring well, and castilig in a heated graphite mold. The polishing and etching techniques employed largely govern the visibility of the structural changes. The preliminary surfacing operations were similar to those recommended by Villela and Bergekoff,5 through Behr-Manning 3/0 abrasive papers, lubricated by a solution of paraffin in kerosene. A rough metallographic polish was next given, using a thin cotton cloth charged with relevigated alumina (maximum particle size of about 4µ) and soap solution; repeated etching and polishing served to remove disturbed metal. For high-power examination better preparation was necessary. It was found that on such soft metals the threads of the fabric, rather than the abrasive, cause most of the scratching. Cotton outing flannel, which had been brushed so that the nap lay down, was fairly satisfactory, but a heavy grade of silk velvet (not the noncrushable kind) was found to be better, especially after some use. A better procedure was as follows: The metal lap was warmed slightly, and a 4-in. circle of woolen broadcloth was cemented to its center by a thin film of melted paraffin. The broadcloth was then moistened with water, and a 30 to 40 per cent solution of sodium hydroxide heated to about 50°C. was poured over it, allowed to stand for I to 2 min. and then washed off. It was neither necessary nor desirable to remove all the sodium hydroxide from the cloth, since its etching action aided in the removal of the flowed layer from the sample. The cloth was then charged with a paste of the relevigated alumina in water. Since this lap did not remove deep scratches, it was necessary previously to polish the specimen on some material such as the silk velvet. The sodium hydroxide softens and partly gelatinizes the woolen lap covering, permitting a scratch-free polish, but its action continues, and the cloth deterioratcs after about 24 hr. This is not serious, because a new lap can be prepared in about 5 min., and only small pieces of cloth are used. Etching with a strongly acid solution of ferric chloride was found satisfactory for removing the flowed layer. For the final etching, the most satisfactory reagent was that of Tafls,7 the formula for which is: FeC13.6H2O, 2 grams; HC1, 5 c.c.; H2O, 30 c.c.; C2H5OH (95 per cent), 60 C.C. This etchant reveals differences in com-

Jan 1, 1942

By J. E. Burke, C. W. Mason

In attempting to study precipitation from a tetragonal lattice, using solid solutione of bismuth in tin, it was found that although a Widmanstätten pattern is observed1,4 only a qualitative analysis of the orientation relationships is possible, because of the unusual structural changes that accompany the precipitation process. Microscopical Studies Alloys were made from Chempur tin (Standard samples 42b and 426, National Bureau of Standards), and bismuth (Kahl-baum C.P.) by melting weighed quantities together under palm oil, stirring well, and castilig in a heated graphite mold. The polishing and etching techniques employed largely govern the visibility of the structural changes. The preliminary surfacing operations were similar to those recommended by Villela and Bergekoff,5 through Behr-Manning 3/0 abrasive papers, lubricated by a solution of paraffin in kerosene. A rough metallographic polish was next given, using a thin cotton cloth charged with relevigated alumina (maximum particle size of about 4µ) and soap solution; repeated etching and polishing served to remove disturbed metal. For high-power examination better preparation was necessary. It was found that on such soft metals the threads of the fabric, rather than the abrasive, cause most of the scratching. Cotton outing flannel, which had been brushed so that the nap lay down, was fairly satisfactory, but a heavy grade of silk velvet (not the noncrushable kind) was found to be better, especially after some use. A better procedure was as follows: The metal lap was warmed slightly, and a 4-in. circle of woolen broadcloth was cemented to its center by a thin film of melted paraffin. The broadcloth was then moistened with water, and a 30 to 40 per cent solution of sodium hydroxide heated to about 50°C. was poured over it, allowed to stand for I to 2 min. and then washed off. It was neither necessary nor desirable to remove all the sodium hydroxide from the cloth, since its etching action aided in the removal of the flowed layer from the sample. The cloth was then charged with a paste of the relevigated alumina in water. Since this lap did not remove deep scratches, it was necessary previously to polish the specimen on some material such as the silk velvet. The sodium hydroxide softens and partly gelatinizes the woolen lap covering, permitting a scratch-free polish, but its action continues, and the cloth deterioratcs after about 24 hr. This is not serious, because a new lap can be prepared in about 5 min., and only small pieces of cloth are used. Etching with a strongly acid solution of ferric chloride was found satisfactory for removing the flowed layer. For the final etching, the most satisfactory reagent was that of Tafls,7 the formula for which is: FeC13.6H2O, 2 grams; HC1, 5 c.c.; H2O, 30 c.c.; C2H5OH (95 per cent), 60 C.C. This etchant reveals differences in com-

Jan 1, 1942

By Roman Y. Poderny, Vladimir V. Rjevskii

In the USSR, the Moscow Institute of Radio Electronics tronics and Mining Electro-Mechanics (MIRGEM) has started what it hopes will become a nationwide movement to educate mining students in the precise specialties that industry has come to require. Courses for mining engineers, the MIRGEM faculty proposes, should dovetail as exactly as possible with specific jobs available in the mining profession. Acting upon this thesis, MIRGEM revised its own curriculum in 1962 and has since presented an over-all plan for Soviet mining education before two mining school conferences as well as the Ministry of Higher Education and a number of major Soviet industrial ministries. The plan was universally approved with some suggested revisions. SOVIET MINING EDUCATION TODAY At present, mining education in the Soviet Union covers the exploitation of solid minerals and raw materials, including coal as well as ferrous and nonferrous metals. The extraction, storage, and refining of oil and gas is treated as a separate discipline. In all, there are 33 Soviet universities and institutes that train mining engineers for careers in the industrial, research and educational fields.

Jan 9, 1966

B. S. and E. M. from the School of Mines at Socorro, New Mexico, in May, 1912. Immediately after graduating, he began as a practical miner in the U. S. mines at Bingham, Utah, but in November, 1912, he entered the operating department of the Chino Copper Co.'s concentrator at Hurley, New Mexico, where he stayed until July, 1913. During the latter half of 1913, he was employed as chemist in the laboratory of the El Paso smelter, at El Paso, Texas. In December, 1913, he became engineer and geologist with the Empire Zinc Co., at Socorro, New Mexico, which position he held at the time of his admission to the Institute in 1914, and until he entered the army in June, 1918. Before beginning the study of mining, Mr. Ringlund had completed a course in pharmacy, which accounts for his enlisting in the Medical Corps. Lieutenant George Roper, Jr. George Roper, Jr., a Junior Member of the Institute, was killed in an aeroplane accident near Shotwich, England, on Play 25, 1918. He was born at Steubenville, Ohio, in 1893, and at the time of his admi~sion to the Institute in 1916 was a student in mining and metallurgy at the Massachusetts Institute of Technology, Boston, Mass., from which he received the degree of S. B. in June, 1917. In August, 1917, he enlisted in the Royal Flying Corps, and after preliminary training on this side of the water, was sent to England. He was making the final cross-country flight of his course of training when the accident occurred.

Jan 1, 1920

The following is a 'partial list of members and guests who called at Institute headquarters during the period Oct. 10, 1917, to Nov. 10, 1917. Edwin T. Blake, Berkeley, Cal. Alfred C. Lane, Tufts College, Mass. H. M. Boylston, Cambridge, Mass. W. G. Matteson, Houston, Texas. W. B. Cogswell, Syracuse, N. Y. E. Francis M'Crossin, Birmingham, Ala. Paul R. Cook, Zaruma, Ecuador. R. E. Murray, Butte, Mont. F. W. DeWolf, Washington, D. C. Edmund Newton, Minneapolis, Minn. A. Faison Dixon, Venezuela. J. J. Ormsbee, El Paso, Texas. W. H. Dufur,, Oil City, Pa. Pablo Ortega, Havana, Cuba. Maxwell E. Erdofy, Lieut. Engr. Officers'. W. E. Pomeroy, El Paso, Texas Reserve Corps, New York. J. C. Ralston, Spokane, Wash. Evan Fraser-Campbell, Scotland. W. L. Remick, Chrome, N. J. David B. Gemmill, Crown King, Ariz. Howard D. Smith, San Francisco, Cal. F. Lynwood Garrison, Philadelphia, Pa. Harold C. E. Spence, Steeple Rock, N. M. C. J. Hall, Spassky, Siberia. R. K. Stockwell, Salt Lake City, Utah. H. Hamada, Tokyo, Japan. Maurice W. Summerhayes, Timmins, Rush M. Hess, Bouse, Ariz. Ont., Canada. A. Howard Higgin, London, England Malcolm M. Thompson, Morsemere; N. J. A. O. Ihlseng, Joplin, Mo. Nicholas Truschkoff, Petrograd, Russia. T. Ishikawa, Japan. H. J. Wendler, Los Angeles, Cal. C. H. James, Tucson, Ariz. Ira T. Wright, Hurley, N. M. R. R. Landon, Philippine Islands. C. Yabe, Japan. Robert W. Bissell has now become associated with Gunn, Richards & Co., of New York, N. Y. Major Reginald W. Brock is giving a course in a school for commanding officers in England.

Jan 12, 1917

By James W. Malcolmson

This paper treats of the history and development of the Sierra Mojada mines in the north of Mexico, the character and extent of the ore-deposits, and the methods of mining the ore. The growth of the smelting industry in Mexico in recent years is, to a large degree, due directly to the output of the lead-bearing ores from the Sierra Mojada mines, and at the present time (1901) new smelters are being built, looking to this district for their supply of lead-ores. These mines are located in the southern part of the State of Coahuila, in the Republic of Mexico, in latitude 27 24' N. and longitude 103O 43' W. of Greenwich. The last account of the Sierra Mojada published in our transactions was contributed by Mr. Richard E. Chism, in October, 1886.* Since that time some 3,000,000 tons of ore have been extracted from the mines, and much additional information has been developed regarding the mineral deposits. Since 1886, the Mexican Northern railroad, 78 miles in length, has been built from Escalon, connecting the camp with the Mexican Central railway, a trunk-line from El Paso, Texas, to Mexico City. The distances by rail from Sierra Mojada to the principal smelting-centers are as follows : To Torreon, Coahuila, Mex., 179 miles; to Monterey, Nuevo Leon, Mex., 422 miles; to El Paso, Tex., U. S., 494 miles; to Aguas Calientes, A. C., Mex., 522 miles; to San Luis Potosi, 8. L. P., Mex., 644 miles; to Pueblo, Colorado, U. S., 1158 miles; to Argentine, Kans., U. S.,

Jan 1, 1902

By John V. Beall, William F. Haddon

A long the mighty Andean Cordillera, there is splendor beyond imagination-in the natural beauty of the mountains and in daring engineering and lavish investment in the mines. This is the story of the great copper mines of Chile and Peru. Each mine has a special quality which has tested the physical and spiritual resources of the founder. In the early days of the older mines, the mining engineer of song and story was more the rule than the exception. He was physically tough, ingenious and a leader of men. In the current political and social environment of Chile and Peru, the foreign contract mining engineer is still needed; but he must be a different type of man. To John J. Selters at Cerro's Rio Blanco, the principal ingredient is still "toughness," but it is "toughness of mind" that is needed. "He probably should be a teacher." The copper mines are not new. They were, almost without exception, worked by Indians (La Exotica might prove the rule), and later by the intrepid Spaniards. Modern mining began after the turn of the century. In Chile, the first of the big ones was the Braden Copper Co. founded on the El Teniente deposit. This development was followed by Chile Exploration Co. at Chuquicamata and Andes Copper at Potrerillos. These properties have been developed over the years by vast expenditures of money and a monumental amount of labor. None was free of technical problems-metallurgy at Chuqui, marginal grade of the old mine at Andes, avalanches and the great fire at El Teniente. The evolution which has brought the established mines of Chile, and the new ones coming on stream, to their present state of development is in reality the work of wonders of input-money, engineering and responsible management in an atmosphere of political stability. Without any one of these, the result would have been failure.

Jan 11, 1969

By E. D. Hummer

During the planning of the fine coal cleaning addition at the Gary, W. Va., Coal Preparation Plant of United States Steel Corp. careful consideration was directed toward the problem of minus 48 mesh refuse disposal. The plant flow sheet included wet screening the raw coal at ¼ in., pumping the minus ¼ in. raw coal to bowl desiltors for desliming, and then cleaning the deslimed raw coal on tables. The material to be removed from the circuit as minus 48 mesh refuse consisted of the minus 100 mesh desiltor overflow thickened in two 120 ft diam thickeners and minus 1 mm screened from the table refuse. Later a flotation plant was added to recover coal from the desiltor overflow, and a classifier replaced the screens to make a sharper size separation of the table refuse at 48 mesh. Today the minus 48 mesh refuse at Gary consists of thickened flotation tailing and thickened spiral classifier overflow. The transportation of large quantities of fine, wet refuse filter cake mixed with jig and table refuse over existing conveying equipment would have been neither dependable nor economical. Filtration was therefore impractical, and disposal of the fine materials was a problem. The decision was to pump the material to storage ponds.

Jan 3, 1965

By F. H. Gilpin

SINCE Noah pitched his ark within and without with pitch, the use of asphalt in human endeavor has been increasing-for Noah's pitch was asphalt. Asphalt is a bituminous material found in nature, either pure or admixed with smaller or greater quanti-ties of mineral and non-mineral materials, or obtained by the refining of crude asphaltic-base petroleum under proper methods of control. Native or "natural" asphalts are scattered through-out the world, though the commercial value of the various deposits varies greatly, depending upon both their accessibility and magnitude and the quality of the material found. It is an acknowledged fact that such asphalts have been produced through natural causes by practically the same application of tempera-ture and pressure as are used in the modern refining of crude asphaltic-base petroleum. The best known of all the native asphalt deposits are those of Trinidad Lake in the Island of Trinidad, British West Indies, and of Bermudez Lake in Vene-zuela. Asphalt from Trinidad Lake, after refining to remove organic and some inorganic diluents, contains approximately 35 per cent, of inorganic residue, and the asphalt thus produced must be fluxed with lighter asphaltic or semi-asphaltic base oil to make it com-mercially utilizable. The refined asphalt obtained from the Bermudez Lake deposit contains from 4 to 6 per cent. of inorganic material which cannot be removed. This asphalt, also, must be fluxed to produce com-mercial products. Small quantities of similar materials are available in other locations. The best pure native asphalt' is known as. gilsonite and is mined in com-mercial quantities in the State of Utah. In numerous places in the United States, particularly Oklahoma and Kentucky, there are deposits of sand¬stone and limestone impregnated with bitumen, which are known as rock asphalts. These rock asphalts may be used, particularly in the paving industry, either as found or by slight fluxing; from some deposits the asphalt is extracted and marketed commercially.

Jan 2, 1923

By David Cole

AT the time flotation appeared upon the metallurgical horizon in Arizona, the writer, under the direction of Dr. Ricketts, was engaged in remodeling and enlarging the No. 6 Concentration Plant of the Arizona Copper Co. at Morenci, and the work had been in progress nearly a year before the Inspiration experiments with flotation had disclosed the revolution in concentration that was at that timè impending. The simplified flowsheet worked out for the remodeling of the Morenci plant had been based upon the removal of the freed metal in a minimum number of stages by treatment upon tables equipped with Butchart riffles, the latter being adapted to accomplish both classification of feed and removal of the metal at one operation, substantially as described in my previous paper.1 The scheme of treatment for the slime was based upon the well-known fact that after copper sulphides, such as chalcocite and chalcopyrite, etc., are reduced to a certain extremely fine state of comminution they are definitely beyond the reach of separation upon any of the concentrating devices then known. By using drag-belt classifiers (which served as conveyors as well as separators), the overflow would be of the usual "slimes" class. Experiment had shown that when these drag-belt overflows were, properly diluted (that is, to about 5 to 7 per cent. solids in the feed under treatment) . the very fine sand, and especially the very fine but still granular sulphide particle's, would, if given a short distance to fall, quickly settle out in prime condition to yield an excellent recovery on vanners; a further valuable feature would be that the very fine non-separable final overflow tonnage might be discharged direct to tailing, thus conserving space requirements so as to permit within the old building, without embarrass-ment, the increase of capacity required.

Jan 9, 1916