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By F. R. Hutto Jr., F. L. Kady Jr., L. E. Weymouth

The behavior of particulate non-metallic materials in moving contact with smooth surfaces is of interest and concern to manufacturers and users of abrasives, of fillers, and of pigments alike. The theoretical aspects of the subject have been treated to considerable extent in the literature, and correlatic,ns are available that attempt to relate various methods of hardness determination." 2 The particle size and friability are characteristics of the abrasive that are not related to the smooth surface. The hardness, on the other hand, may be visualized as relative to that of the smooth surface. In a study of abrasive action, the role that hardness, per se, plays is a complicated one. For it is necessary to compare the "hardness" of the abrasive, usually a non-metallic, with that of the smooth surface, generally a metal. Hardness of non-metallics is defined as resistance to scratch and is almost universally described with respect to the Mohs scale.3 Minerals have been rated by Mohs numerically from the softest (talc = 1) to the hardest (diamond = 10). By definition, a mineral has a designated hardness when it is scratched by the standard that is numerically just above it on the scale; and conversely, when it scratches the standard that is just below it. Hardness of metals. however.. implies resistance to indentation, a property that has been measured by a number of methods. In fact, the indentation hardnesses of the standard minerals on the hlohs scale have been determined by the Rockwell tester. Reproduced below are two versions of this correlation. 'A conversion chart, prepared by Wilson Mechanical Instruments Division of American Chain and Cable Co., merely gives the conversion from Rockwell to Knoop hardness. The relation between Knoop indentation hardness and Mohs scale has been reported by G. S. Smith — A New Scale of Hardness, The Engineer, Aug. 26. 1949. G. F. Kinney in Engineerin Properties and Aplications of Plastics reports the Rockwell hardness of the minerals directly in the Mohs scale. The question immediately arises as to whether this relation is valid when applied in reverse; namely,

Jan 1, 1961

By F. E. Lathe, L. Hodnett

This paper summarizes extensive data supplied by 40 copper converter plants in 18 countries, and includes a partial analysis and comments on the effect of converter slag composition and temperature on the fomzation and elimination of magnetite and the life of basic and neutral refractories. APRELIMINARY draft of this paper, including data from 26 companies which had submitted replies to a questionnaire, was presented at the Annual Meeting of the AIME held in New York in February, 1956. Publication was delayed in the expectation that additional replies would be received, and justification for the subsequent delay may be found in the fact that the present revised paper contains data from 40 converter plants situated in 18 different countries. The suggestion that a questionnaire be sent to the major copper and copper-nickel plants outside the U.S.S.R. and associated countries arose at the Los Angeles Annual Meeting in February, 1953, where several papers dealing with converter construction and operation were presented. In private discussions which followed, a group of metallurgists and refractories engineers raised the question why practices varied so much at different plants. Why did magnesite brick give superior service to chrome-magnesite in some plants but chrome-magnesite prove superior in others? Would metallurgical studies point the way to the development of still better refractories? Could magnetite formation be prevented in converter slags and reverber-atory furnace mattes? If this was feasible, why was a heavy circulating load of magnetite tolerated, when, in all probability, it increased copper losses in the reverberatory slags and, in some cases, made it necessary to shut down the furnaces periodically to clean out the accumulated magnetite? Was the sole purpose of coating brick with magnetite that of

Jan 1, 1959

but, returning to South Africa, for the next two years he was assistant general manager of the Simmer Deep Gold Mining Co., at Johannesburg. In June, 1911, he returned to New Zealand as general manager and consulting engineer for the Consolidated Goldfields of New Zealand, at Reefton, which position he held at the time of his admission to the Institute in 1914. Early in September, 1915, he left New Zealand for active service in France. Corporal Sheppard B. Gordy Sheppard B. Gordy, born in Ansonia, Conn., in 1889, graduated from the Sheffield Scientific School in 1910 and with the degree of E. M. in 1912. He entered the employ of the Braden Copper Co. immediately on his graduation and remained with this company four years, working up through the various grades to assistant foreman and foreman to one of the individual mines. The last year he was in its employ, he acted as general mine foreman. He was for a short time with the Chile Exploration Co. and then went with the Andes Exploration Co. (Anaconda) and remained with the latter, doing mine exploration and development work, until he sailed for home in June, 1918, to give a more personal and active service to his country in her need. He declined a tender of induction into an officers' training camp, at the urgent request of Professor McClelland supplemented by Mr. Potter, because they demonstrated to his satisfaction that he could give more valuable service to his country in helping out with the aircraft production. Being within the draft age, in order to carry out this plan, it was necessary for him to be called by his Local Board and sent to camp. This call came Aug. 26. Two weeks before that time he had gone to Dayton, Ohio, to begin the study of aircraft production, and was sent by the Dayton Board to Camp Sherman, Chillicothe, Ohio, where he died of pneumonia on Oct. 9. Lieutenant Thomas Clarence Gorman Thomas C. Gorman, a lieutenant in the Second Tunnelling Company of the Canadian Engineers, was killed in France on Mar. 18, 1918. He was resting in his sleeping hut and was in the act of writing a letter when a bursting shell killed him.

Jan 1, 1920

but, returning to South Africa, for the next two years he was assistant general manager of the Simmer Deep Gold Mining Co., at Johannesburg. In June, 1911, he returned to New Zealand as general manager and consulting engineer for the Consolidated Goldfields of New Zealand, at Reefton, which position he held at the time of his admission to the 1nstitute in 1914. Early in September, 1915, he left New Zealand for active service in France. Corporal Sheppard B. Gordy Sheppard B. Gordy, born in Ansonia, Conn., in 1889, graduated from the Sheffield Scientific School in 1910 and with the degree of E. M. in 1912. He entered the employ of the Braden Copper Co. immediately on his graduation and remained with this company four years, working up through the various grades to assistant foreman and foreman to one of the individual mines. The last year he was in its employ, he acted as general mine foreman. He was for a short time with the Chile Exploration Co. and then went with the Andes Exploration Co. (Anaconda) and remained with the latter, doing mine exploration and development work, until he sailed for home in June, 1918, to give a more personal and active service to his country in her need. He declined a tender of induction into an officers' training camp, at the urgent request of Professor McClelland supplemented by Mr. Potter, because they demonstrated to his satisfaction that he could give more valuable service to his country in helping out with the aircraft production. Being within the draft age, in order to carry out this plan, it was necessary for him to be called by his Local Board and sent to camp. This call came Aug. 26. Two weeks before that time he had gone to Dayton, Ohio, to begin the study of aircraft production, and was sent by the Dayton Board to Camp Sherman, Chillicothe, Ohio, where he died of pneumonia on Oct. 9. Lieutenant Thomas Clarence Gorman Thomas C. Gorman, a lieutenant in the Second Tunnelling Company of the Canadian Engineers, was killed in France on Mar. 18, 1918. He was resting in his sleeping hut and was in the act of writing a letter when a bursting shell killed him.

Jan 1, 1920

[ ] John M. Davis has left Western Machinery Co. to take a job as project engineer with Baroid Sales Div., National Lead Co., and is now located at Houston, Texas. C. W. Allen, general manager of the mining dept. of the Cleveland Cliffs Iron Co., visited the firm's iron mines on the Mesabi iron range of Minnesota recently. Thomas P. Anderson, mining engineer and geologist, has resigned from the Raw Materials Div. of the U. S. Atomic Energy Commission where he was assistant chief of the Denver Exploration Branch. He will enter private practice in Golden, Colo. James E. Atkinson, consulting mining engineer and geologist, left New York for Colombia, S. A., as general manager for Cia Minera Choco-Pacifico, S. A., operating five dredges in gold and platinum on the Pacific coast of Colombia. Russell H. Bennett has been elected a director of Placer Development, Ltd. with head office in Vancouver, B. C., and is also a director of its subsidiary, Canadian Exploration, Ltd., which mines and mills lead, zinc, and tungsten ores at a property near Salmo, B. C.

Jan 1, 1952

By Leslie C. Richards

The competitive position of producers of industrial minerals depends upon the delivered price of their product. Freight charges are a major factor in the sales to consumers. A comparison of freight rates on movements of limestone and silica rock in the Pacific Northwest shows a wide variance in mills per ton mile for like hauls, thereby favoring some localities over others.

Jan 1, 1950

. F. W. SPERR, JR.,* Pittsburgh, Pa.--Mr. Malcolmson states that the Carbocoal process produces ammonium sulfate in excess of that normally recovered in the ordinary byproduct coke process. Table 3 indicates that 20,000 to 25,000 lb. of sulfate of ammonia are obtained in carbonizing 1000 tons of Clinchfield coal. This is a high-grade coal and yields from 26 to 28 lb. of ammonium sulfate per ton in a modern byproduct coke oven. On the next page, 21 lb. is stated as the yield of ammonium sulfate per short ton of raw coal; this is less than the average production from any well operated byproduct coke-oven plant treating coal of the character usually coked, in Pennsylvania and Ohio. The statement as to the comparative yields of light oil is somewhat misleading in view of the results obtained during the past year or two by the more modern byproduct coke plants. The plants put in operation by the H. Koppers Co., during the past two years, are producing about 3.5 gal. of light oil per short ton of coal, and several of these plants are producing more than 4 gal. per ton. The yield of pure toluene runs from 0.45 gal. to 0.55 gal. per ton. .The quality of the light oil .obtained from the Carbocoal process is of much greater importance than would be inferred by one not closely familiar with the subject. The presence of paraffins in the benzol and toluol fractions seriously detracts from their commercial value; the benzol and toluol fractions derived fro in the Carbocoal process contain about 50 per cent, of paraffins. It should be thoroughly understood what these paraffins are. They are simply hydrocarbons that go to make up ordinary petroleum, and if a successful method for the removal of paraffins from benzol and toluol has been developed, this can at once be applied to several well known processes by which benzol and toluol can be made directly from petroleum, which have as yet been total failures on account of the contamination of these products by paraffins.

Jan 11, 1918

By David B. Reger

Extensive drilling for gas and increased pipe-line building were the major petroleum activities in West Virginia during 1937. According to the West Virginia Department of Mines, 1034 permits to drill were issued. A running account of operations from trade journals and other reports shows that 1041 wells were drilled, resulting in 193 oil wells with 1238 bbl. of daily production; 680 gas wells with 1,048,057,000 cu. ft. of daily open flow; and 168 dry holes. The new oil-well average is 6.4 bbl. per well per day; the gas-well average is 1,541,260 cu. ft. per well per day; the ratio of dry holes to completions is 16.13 per cent. Very little attempt was made to develop new supplies of oil. Because of the continued low price, operators evidently considered it good business to leave oil in the ground rather than to produce it at a loss or on a small profit basis. The principal oil wells completed, by counties, are: Calhoun, 16; Clay, 10; Pleasants, 17; Ritchie, 42; Roane, 16; Tyler, 13; Wetzel, 11; Wirt, 14; Wood, 13. The leading counties in gas, with the number of successful wells in each, are: Boone, 54; Braxton, 31; Cabell, 48; Calhoun, 46; Gilmer, 82; Kanawha, 134; Lincoln, 44; Ritchie, 56; and Wayne, 26. General State of the Industry In Table 1 will be found an approximate summary of oil and gas territory and reserves, oil and gas production and number of oil and gas wells. The amount of land under lease is an approximation, because the exact figures are not available through any public or private agency. The proved land and reserves represent the opinion of the writer. The oil production for 1937 is subject to revision, and the gas production for the same year is only an estimate, based on demand and supply. The number of oil and gas wells now active is also an approximation, based on previous studies, and revised for completions and abandonments. Principal, Areas of Activity In Boone County, 62 wells were drilled in various localities, resulting in 4 oil wells and 54 gas wells with 18,170,000 cu. ft. of new production.

Jan 1, 1938

New York Meeting, October 16 and 17, 1913.-The One Hundred and Sixth meeting of the Institute for the reading and discussion of professional papers will be held in New York City, on Thursday and Friday, October 16 and 17, 1913. Headquarters will be at the Institute office in the Engineering Societies Building, 29 West 39th Street. The sessions will be held in one of the assembly rooms of the building. Because of the many valuable papers on iron and steel obtained with the assistance of the Iron and Steel Committee, which papers could not appropriately be presented and discussed at the Montana meeting, this October meeting of the Institute is held for the purpose of reading and discussing these papers, most of which will be printed and distributed in advance. The members of the following societies have been invited to attend the meeting, and several have accepted and declared their intention of taking part in the proceedings: American Society for Testing Materials, American Iron and Steel Institute, American Society of Mechanical Engineers, American Society of Civil Engineers, American Institute of Electrical Engineers, American Foundrymen's Association. The meeting will be conducted under the auspices of the Iron and Steel Committee, and the latest revised program of the proceedings will be found on page xi, under the notes of this Committee.

Jan 10, 1913

By A. W. Schlechten, R. F. Doelling

Parkes' process crusts were vacuum distilled using a shortened Pidgeon retort. Zinc was effectively removed below 800°C and recovered as a zinc sheet easily stripped from the furnace liner. Lead dasdistillationazinc required about 950°C and the resulting lead condensate tillationtended to stick to the thin metal liner. Final purity of residue is limited only by nonvolatile metals such as copper. THE successful commercial application of vacuum distillation for the removal of zinc from lead, as described by W. T. Isbell,' raises the question of whether or not a similar method can be used for other metal separations. Preliminary laboratory experiments on the vacuum distillation of Parkes' crusts by one of the authors' gave such encouraging results that it was decided to make a series of tests with large scale equipment to determine the results that might be expected in plant operation. The pilot-plant test results are reported in this paper. The great advantages of vacuum dezincing are its simplicity, the relatively low temperature of operation, and the fact that the zinc is recovered in the metallic state ready for use again in the desilveriza-tion of lead bullion. These same advantages and others would be realized from the vacuum distillation of the zinc-lead-silver crusts made in the Parkes' process. Zinc readily will distill over at temperatures of 800" to 900 °C as contrasted with the 1200°C or more used in the Faber du Faur furnace. Furthermore, the recovery of zinc as metal is practically perfect since there is no loss by oxidation or fuming. If the vacuum distillation is continued and hastened by raising the temperature to around 1000°C, the lead will distill over at an appreciable rate and deposit in a warmer zone of the condenser. This lead will contain a small amount of silver, but it can be returned to the desilverizing kettles and there is not the chance of loss that there is in disposing of the rich litharge from cupelling. The lower temperatures required will mean a saving of fuel and less wear on the equipment. One further point is that the vacuum distillation could be run on a small scale practically continuously, so as to avoid the accumulation of large amounts of silver-rich material and the need of assembling a large crew for special cupellation runs. It should be pointed out here that the final purity of the silver residue will depend on the copper or iron content of the crusts, as these and other metals with low vapor pressure will not be eliminated. The idea of treating the silver-zinc-lead crusts from the desilverization of lead bullion by vacuum distillation is not a new one, but such experiments have not been reported, as far as can be determined. In 1912, T. Turner presented a paper3 before the Institute of Metals on the vacuum distillation of brass, and a member of the audience suggested that he try his method on Parkes' crusts. In 1935, W. J. Kroll, noted for his discovery of debismuthiz-ing lead by calcium additions, published a paper' on vacuum distillation of metals and pointed out possible applications in the lead industry. Principles of Separation The successful separation of two or more metals by distillation depends upon an appreciable difference in the effective vapor pressures of the metals in the alloy to be treated. The vapor pressures of the common metals have been determined with considerable accuracy; for example, at 800°C the vapor pressures of the individual metals which are of particular interest in this paper are about .as follows: Zn, 241 mm; Pb, 0.0553 mm; and Ag, 0.0000276 mm. Unfortunately,, data are not available on the activities of the components in the ternary system Zn-Pb-Ag, but it can be estimated that on the basis of the vapor pressures of the individual metals a good separation can be made by distillation. The preliminary laboratory tests previously mentioned' supported this assumption. The pilot-plant size vacuum distilling furnace is shown in Fig. 1. It consisted of an abbreviated Pidgeon retort, 5 ft long with an ID of 8 in., heated by six silicon carbide elements placed symmetrically

Jan 1, 1952

By Thomas T., Read

ALTHOUGH the first colonists in the area that is now the A United States, whether Spanish, French or English in nationality, were usually keenly interested in the possibilities of mineral wealth, it is a curious and interesting fact that none of them happened upon the mineral deposits that eventually were to make this the greatest mineral-producing country; up to 1800 it would probably have been rated as rather poor in minerals. Spanish explorers traversed the southeastern United States with- , out finding the Appalachian gold deposits that aroused so much interest in the early nineteenth century; Coronado sought in vain for the seven golden cities of Cibola; and the important gold \ deposits of California were not discovered until the political sovereignty of the region had passed from Mexico, which had held it for three centuries. The French also held Canada for nearly two centuries (and the British for another century) without finding the mineral deposits in Ontario and Quebec that now are so important. Though they knew of the copper of the Keweenaw peninsula, the lead ores. of Wisconsin and Missouri, and the coal of Illinois in the seventeenth century, these deposits were all too remote for exploitation. In the area held by Great Britain, iron smelting was planned at Jamestown as early as 1619 and was actually begun at Lynn, Mass., in 1643. The industry grew slowly, at first, but had reached considerable importance before the Revolution. Commercial bituminous coal mining began about 1750 in Virginia but anthracite mining in Pennsylvania was not started until 1800. As a result there was naturally little interest in the technical aspects of mineral prodnction here before 1800 by any except the few people who were actually engaged in it. Students of natural science were much interested in minerals, however. The activities of those who rank as geologists are so thoroughly covered in

Jan 1, 1941

By R. Kossowsky

Structural changes in Be-Cu, Be-Ni. Be - Ag, and Be-Fc alloys pressurized in a solid medium were invesligated by resistivity measurements , X-ray diffrac lion in situ and metallogvaphic examination. Some limited tests in liquid medium were also conducted. Good correlation was oblained between diauges of slope of relative resistance us pressure and changes in diffraction pattern. Metallographic examination rez:ealed that the copper, silver, and nickel alloys lwiu heauily due to the applicalion of pressure at room temperature. Using polarized light technique {1012}, {1011}, and possible {1010} twinning planes were identified. At eleuated temperature twinning was moslly confined to the {1012} planes. Although twin-ning could be promoted by application of hydroslutic pvessure (liquid medium), it was strongly enhanced by the pvesence of a nonhydvostatic shear component due to pressurizalion in a solid medium. It was further obserced that a decrease in grain size inlnibiled twinnitzg activily. A great deal of effort has been expended in recent years to render beryllium useful for structural applications. Efforts were concentrated towards a possible phase change and to promoting other than basal deformation modes. Quenching experiments to obtain the high-temperature bcc phase have failed,' nor were alloying additions successful in improving ductility of the brittle hcp phase.2 Herman et a1.3 have reported a new {1011} twinning mode in a Be-4.4 wt pct Cu alloy oriented for a C axis compression sustaining loads to 440,000 psi. A new approach using high-pressure techniques was undertaken at Curtiss-Wright, Wright Aeronautical Division Laboratories. Marder4 reported a 25 pct decrease in relative resistance of commercially pure beryllium at 92 kbar. He proposed that this discontinuity corresponded to the bcc phase found at high temperature; however, X-ray diffraction in silu did not confirm a phase transition.5 contre6 has recently shown that the bcc transition in pure beryllium is lowered to 800°C at 80 kbar accompanied by a 50 pct increase in relative resistance. The purpose of this paper is to report on one phase of an investigation of the effects of high pressures and temperatures in beryllium alloys, namely, twinning behavior in Be-Ni, Be-Cu, Be-Fe, and Be-Ag alloys pressurized to nearly 100 kbar and temperatures up to 200°C. EXPERIMENTAL METHODS Material was obtained from Nuclear Metals, Inc., in the form of a 1.5-mm-diam wire extruded in stainless-steel cladding at 1600° F. Nominal composition of the alloys is listed in Table I, and the major impurities are are given in Table 11. Pressures to 100 kbar* were ob- tained using a National Bureau of Standards type 100/400 ton tetrahedral unit supplied by Barogenics, Inc. This type of apparatus contains a retaining sleeve with a conically tapered internal surface and four pressure-intensifying anvil assemblies with tungsten carbide tips. The 10-mm-long specimen fits into a pyro-

Jan 1, 1968

It has been suggested that it would be a desirable feature in connection with the Chicago meeting of the, Institute in September to arrange for a return trip for the fuel men through the coal fields of Illinois, Ohio and Pennsylvania, stopping at various points and possibly touching also Kentucky. Perhaps the petroleum men would be interested in a similar trip and might join them stopping off at different points to visit these oil fields. If the members who would-be interested in such a trip will advise the Secretary before the first of June, indicating their desired stopping points, steps will be taken to perfect arrangements accordingly.

Jan 5, 1919

By WILLIAM SLOAN

B RITISH COLUMBIA in its mining activities is going ahead by leaps and bounds both in development and production. Mineral production for 1925 was $61,492,242 in value as compared to $48,704,- 604 in 1924, or an increase of about 26.2 per cent. This is a new record. It is the first time in the history of mining in British Columbia that we have gone over the fifty million mark. But we have got in the habit of making new records. The year 1924, with its mineral production of almost forty-nine million was a new record. And I am confident that when the mining history of 1926 is written it will be found that we have established yet another new record and that we can report another 25 per cent increase over 1925. What is the explanation? It is not only that the world is settling down, and settling up, after the war. It is not only that in the rebuilding, the refashioning in which all nations are busily engaged, the metals that come from our mines are needed. More than anything else, at least as far as we are concerned, it is because British Columbia has the resources and the fact that the province has been fortunate in recent years in finding men with the enterprise and the vision required to push ahead the labor of their development. From the ranks of our own people in Canada we have prospectors who have faith, energy and requisite knowledge. They are combing our hills season after season and they are of the type of manhood that does not know the meaning of the word quit. More and more these men are learning the importance of the guidance furnished by geological reports, and to an ever increasing extent such reports, thanks to the valuable work of the Canadian Geological Survey, covering areas little known to man, are made available to them-but it is recognized that in the opening up of our Province, containing within itself 372,000 square miles, it is essential that we should have the cooperation of our cousins on this side of the line as well as of our fellow citizens of the Dominion and of the Mother Country.

Jan 1, 1926

By William H. Grady

FactoRs entering into the market value of coal are its grade, and the cost of labor, material, and capital. Reduction in these costs cannot be expected in the future, and it therefore follows that greater economy in their use must be accomplished if it is desired to hold the present markets; more tons of product per unit must be obtained in a given time from both men and material, and means devised for increasing the percentage of lump and domestic sizes. This paper is presented for the purpose of inviting discussion and stimulating thought in regard to the influence of methods of procedure and plans of mining, upon the quality of coal, the economical use of labor, material, and capital, and the cost of production. Even the better methods of the present day leave much to be desired, and a review of the reasons and necessities for their use may be of value in pointing the way to more economical mining. The writer does not attempt to discuss untried methods of mining, but rather to state clearly and concisely a summary of the results obtained under the several methods of procedure that have been adopted. In some instances a high degree of concentration has been effected, and comparisons of the results obtained with the results of lesser degrees of concentration form an interesting study. It is believed that much may be accomplished in improving the quality, and in the more economical use of labor, material, and capital, by concentration, and it is to concentration in particular that your study is invited. The writer, who has occasion to visit many mines, most of which are under different management, has been inclined to the opinion that improvement has been retarded in many ways and that mining has not as yet been entirely freed from the early-day practices which were forced upon it. Practices resulting in lack of concentration, to which reference will be made, are: The absence of robbing, necessitating the frequent interposition of barrier pillars; lack of system and of proper supervision, resulting in losses of life and coal. These practices could not well be

Jan 1, 1915

By John Johnston

ONLY two of the Institute's 26 Local Sections were unrepresented at the delegates' three sessions, held on Monday morning and afternoon and Thursday afternoon of the annual meeting. The Philadelphia and Wyoming Sections alone sent no delegates. In all, seven hours were spent most profitably in reviewing the work done by the Institute at headquarters and in the field, comparing ideas and practices in varied activities, and in establishing personal contacts. Cordiality and the co¬operative spirit marked the meeting and apparently no one had any serious grievances to air. Four motions were introduced and unanimously passed. The first, which was introduced by B. L. Sackett, was a recommendation by the delegates that a national committee be appointed to cooperate with Local Sections in the matter of student activities, to promote Institute welfare. It was agreed that this recommendation be made simultaneously to the Board of Directors and to the Mineral Industry Education Division. A subsequent resolution by A. M. Smith was passed asking that a part of the duties of this committee be to secure the opinions of Local Sections as to the most desirable methods of interesting students in the preparation of technical papers, by giving prizes or otherwise, and to report their findings at the Section Delegates' meeting next year.

Jan 1, 1933

A LARGE attendance at the annual dinner of the Institute, to be held this year on Tuesday eve-ning of convention week, is already assured. Presentation of the Douglas, Hunt and Saunders medals will attract unusual attention since not only in Blaylock, Mathews and Hoover the Institute will be honoring men who have made notable contributions to the advance-ment of their profession, but as to one of them each person as he passes down the reception line will be won-dering whether in renewing acquaintance with our past-president and present Secretary of Commerce, he is not greeting the next president of the United States. Elsewhere in this issue accounts of the professional careers of these three men appear as also of the two younger men, Charles H. Herty, Jr., and P. H. Royster, who are to receive the Robert W. Hunt and the J. E. Johnson awards. Institute honors go for technical achievement, but the Institute will be proud and happy if the nation should later confirm its own judgment by placing larger responsibilities on one of its members. The medals are to be presented at the annual dinner following the President's reception and preceding the dance. There will be no. other speeches and since the occasion falls on Carnival Night a particularly gay evening is anticipated. The event will be at the Wal-dorf as usual, and members are urged to return prompt-ly the reservation cards sent them by mail. Other entertainment features will include a Smoker, Monday evening at 8.15, held at Mecca Temple and in charge of a new committee with Fred Kay of the Petro-leum Division as chairman. He promises that vocal music will not be allowed to interrupt conversation. Lunch will be served each day on the Fifth Floor of the Engineering Societies Building, and ten special luncheons and dinners have been arranged for particu-lar committees and groups as shown by the detailed program. The Woman's Auxiliary has laid out a gen-erous program including luncheons, teas, a theater party on the night the men folks go to the Smoker, visits to museums and, not the least important, a round of the leading shops. The Excursion Committee is arranging for an excur-sion sure to be of interest. The American Smelting and Refining Co. has opened its great Perth Amboy plant to the Institute, and on Thursday, Feb. 23, a party will be taken to it by bus traveling through the Holland Tunnel en route. Full opportunity will be afforded those interested to see the workings of the ventilation system of that great public work. If a sufficient number indicate interest, arrangements will be made for group excursions to other plants in the vicinity of the city.

Jan 2, 1928

By J. F. Shirley, H. K. Burke

In January, 1964, three years of laboratory and pilot plant test work reached its culmination. The San Manuel Div. of the Magma Copper Co. switched its molybdenite extraction circuit from the sodium hypochlorite-ferrocyanide process to the new process described in this paper. The San Manuel Div. Concentrator of the Magma Copper Co. is located near San Manuel, Ariz., approximately 45 miles northeast of Tucson. The concentrator treats approximately 35,000 tons of ore per day containing about 0.85% copper and 0.025% molybdenite. The San Manuel ore body is a disseminated copper deposit in quartz monzonite and quartz monzonite porphyry. The primary copper mineral is chalcopyrite; minor amounts of chalcocite, bornite and covellite are also present in varying degrees. Pyrite makes up somewhat more than half the sulfide content of the rock. The molybdenite is nearly always found on fracture faces or associated with quartz veinlets.' On January 9, 1964, the sodium hypochlorite-ferrocyanide process that had been used for molybdenite recovery was replaced by the following process: 1) A conditioning step with hydrogen peroxide, sulfuric acid, sodium cyanide and zinc sulfate. 2) A two stage rougher flotation step with stove oil and sodium ferrocyanide. 3) One cleaning step with sodium ferrocyanide. 4) One cleaning step with sodium hypochlorite and potassium ferricyanide. 5) Four cleaning steps with an anti-foam Exfoam 636 and potassium ferricyanide. COPPER CONCENTRATOR Since molybdenite recovery is closely allied with previous steps in the operation, the copper concentrator will be briefly described first. The ore is ground to approximately 5% plus 65-mesh and 65% minus 200-mesh in a two-step grinding circuit consisting of rod mills in open circuit and ball mills in closed circuit with rake classifiers. A straight forward rougher circuit producing only one concentrate is used. The rougher concentrate is combined with the discharge from the regrind ball mills and is then cycloned, with the overflow going directly to the cleaner circuit and the underflow going to the regrind mills. The feed to the cleaner circuit is approximately 90% to 94% minus 325 mesh. The cleaner circuit consists of two stages in which the tailing from the final cleaner stage is returned to the primary cleaner and the primary cleaner tailing is returned to the rod mill discharge at the head of the circuit. Approximately 0.013 lb of the allyl ester of amyl xanthate (S-3302) per ton of ore is added to the rod mills and approximately 0.006 lb of sodium isopropyl xanthate (2-11) per ton of ore is stage added down the rougher banks. The frother used is methyl iso-butyl carbinol (MIBC) and it is added at various points in the grinding and the rougher flotation circuits. Lime is added to the ball mills and/or to the rod mills to maintain the desired pH in the rougher flotation. The rougher flotation has been operated at various pH levels between 10.5 and 11.5. Fuel oil is added in the regrind mills at a loading of approximately 0.01 lb per ton of ore. Factors Which Directly Affect Molybdenite Recovery: It has been found at San Manuel that, to obtain maximum molybdenite recovery, an oily type flotation collector must be added in the grinding circuit. When molybdenite is crystallized in the characteristic platy form, which appears to be the case almost all of the time at San Manuel, its surface has a greater tendency to adhere to oils than water. 2 Of the several oily type collectors available on the market, the allyl ester of amyl xanthate seems to be the best molybdenite promoter. The floatability of San Manuel's molybdenite does not appear to be affected, at least up to a pH of 11.5, by lime. It has been reported that at several plant operations high lime alkaline circuits have adversely affected the molybdenite recovery.3,4 It has been found through microscopic studies that the bulk of the chalcopyrite will float before the molybdenite in both the rougher and cleaner circuits. It is necessary to add fuel oil to the regrind mills to enhance the

Jan 1, 1965

By Hollis L. Caswell

The present status of integrated circuits utilizing. superconductive switching. elements is reviewed with special attention given to fabrication techniques, methods for interconnecting completed circuits, and refrigeration requirements. Cryoelectronics has been largely an "inte- grated-circuit" technology since its conception because the switching speed of superconductive devices is attractive only when these devices are fabricated with thin-film techniques. It is true that cryotron circuits can be constructed from wires of appropriate materials (as indeed was done by Dudley Buck 1 in his early investigations) but these circuits will switch in times characteristic of milliseconds whereas similar circuits fabricated by thin-film methods have potential switching times of nanoseconds. Furthermore, cryo-electronic devices such as the cryotron lend themselves readily to fabrication by thin-film techniques since these components may be made from polycrys-talline thin films and are relatively insensitive to the presence of impurities (as measured by semiconductor standards). Therefore, during the past decade considerable effort has been devoted to developing techniques for batch fabricating circuit arrays containing superconductive switching elements. Technology had developed to the point several years ago that fabrication of cryoelectronic arrays containing up to one hundred devices was rather straightforward. However, larger arrays containing between lo4 and 106 components which are required for commercial development of cryoelectronics still pose very severe yield problems. Thus in a sense cryoelectronics found itself in 1962 at the point semiconductor technology finds itself today; namely, individual devices and small groups of integrated devices could be fabricated with acceptable yield and the outlook for building larger integrated-circuit arrays was bright. Unfortunately, problems associated largely with yield have made fabrication of these larger arrays difficult. Unlike semiconductor technology, cryoelectronics had to solve the problems of large-scale integration before it could become economically attractive. This has proven to be a sizable burden to bear. Since several reviews exist on superconductivity,2 superconductive devices,3 and cryoelectronic technology, no attempt will be made in this paper to summarize these areas. Instead a few specific topics will be dealt with in more detail. First, a brief description is given of selected superconducting switching and storage devices with special attention to several metallurgical techniques which improve the performance of these devices. Second, techniques used to fabricate cryoelectronic devices are described with emphasis on problems affecting yield. Third, techniques for interconnecting a number of cryoelectronic planes are described. And last, refrigeration of cryoelectronic components is discussed briefly since the low operating temperature of superconductive devices is an important consideration in this technology. SUPERCONDUCTING STORAGE AND SWITCHING DEVICES The basic superconductive switching device is the thin-film cryotron. The geometry of this device is attractively simple, since it involves only the intersection of two lines that are electrically insulated from each other. The switching element (gate) and control element (control) of a crossed-film cryotron are arranged as illustrated in Fig. 1. The material for the gate is selected to permit the gate to be switched from the superconducting to the normal (resistive) state by the application of a control current. Tin, which has a critical temperature (T,) of 3.7°K, is commonly used for the gate and the cryotron is operated at a temperature just below T, (for example, 3.5°K). The control material (normally lead, with T, = 7.2°K) is chosen so that the control is never driven normal during circuit operation. To improve cryotron operation, a ground plane, also of lead, is placed under all of the circuitry to act as a diamagnetic shield and improve the current-density uniformity across the width of various thin-film elements. Normally, line widths vary from 0.005 to ^ 0.020 in. and film thicknesses from 300 to 10,000A, although new fabrication techniques make narrower lines feasible. In fabricating cryotrons it is important that the edges of the gate elements be geometrically sharp to avoid undesirable switching characteristics associated with a thinner edge region, Fig. 2. One technique which has been used extensively to form patterns consists of placing a physical mask containing the film pattern between the evaporation source and the substrate and depositing through the mask. Film strips formed in this manner possess a penumbra at the film edges due to shadowing of the evapor-ant under the mask. Several techniques have been proposed for minimizing effects due to this penumbra. One of the more promising metallurgical techniques

Jan 1, 1967

By AIME AIME

Award of a Gold Medal : to the Institute. The Jury of Awards of the Jamestown Ter-Centennial Exposition has conferred a gold medal, the highest distinction within its power,. on the American Institute of Mining Engineers for the excellence of its publications during the past decade. ; A half-tone photographic reproduction of both sides of the medal is given in the accompanying illustration.

Jan 7, 1908