Search Documents

By Richard L. Seal, Allan L. Turner

INTRODUCTION The chapter discusses the procedures and operations starting with the actual training of operations personnel with respect to a grinding mill circuit and a typical check-out and start-up of a grinding circuit before turning over the operating circuit to production personnel. For the purposes of this paper, it will be assumed that the mill circuit installation is at a new location or a new operation at an existing operation. Expansion of an existing grinding facility would probably require less time-consuming and less costly procedures than those that will be outlined here. There are numerous arrangements and types of equipment that can be used for grinding circuits. For example, the grinding could be wet or dry. The grinding mill could be a rod or ball mill or some combination. The circuit could be open or closed. The closed circuit classification could be accomplished with rake classifiers, spiral classifiers, cyclones, stationary screens, or vibrating screens. To limit the discussion, the grinding circuit shown on Figure I will be discussed. The circuit includes a dry ore feed by a belt conveyor (feeder) to a wet ball mill. The ball mill discharges to a cyclone feed pump box and pump. The pump feeds a cyclone type classifier with the cyclone underflow returning to the ball mill feed and cyclone overflow being the required grinding circuit product. For the purposes of this paper, it will also be assumed that the extensive overall preparation necessary for every start-up has been accomplished. These preparations are only outlined here as they have been adequately dealt with in recent papers. (1), (2), (3) The items in these preparations would include. 1. Appointment and indoctrination of the start-up organization. 2. Integration of the start-up into the overall project schedule. 3. Development of the specific start-up schedule. 4. Budget determination and monies appropriation.

Jan 1, 1982

By D. A. Thomas, M. F. Comerford

Poly crystalline wires of Fe-3.2 wt pct Si were cold-drawn to 31, 66, and 87 pct reductions of area. Mechanical properties and tnicrostructures were studied after recovery and re crystallization. An initial increase in strength during recovery was ascribed to strain aging, and subsequent softening was largely due to polygonization rather than re-crystallization. No unique actioation energies could be determined for the recovery process. Rather, activation energies ranged from 60,600 cal per mole at 10 pct recovery to 83,200 cal per mole when recovery was 50 pct complete. Sites for the nucleation of recrystallization were found to depend on time and temperature. In the early stages of re-crystallization, nucleation occurred in deformation hands. Later, or at high temperatures, recrystal-lized grains were nucleated primarily al grain boundaries. Polygonized structures did not seem to be preferred sites for nucleation. MUCH of the research on deformation, recovery, and recrystallization processes in bcc materials has been performed on single crystals or lightly worked polycrystals. Little study has been devoted to the relation of mechanical properties to micro-structure in polycrystals after severe deformation and subsequent annealing. This paper presents the results of a study of the tensile properties and microstructures of Fe-Si wires drawn varying amounts and annealed at a series of temperatures. EXPERIMENTAL PROCEDURE The experiments were carried out on an alloy of the following composition: 3.2 wt pct Si, 0.08 Mn, 0.016 C, 0.005 0, 0.0002 N, 0.0001 H, 0.008 P, 0.034 S. The material was received as l-in.-sq bars cut longitudinally from a hot-rolled slab provided by the Armco Steel Corp. The bars were forged to 3/8-in. rounds, centerless-ground to 0.250 in., and swaged to '0.108 in. All subsequent reductions were performed by room-temperature wire drawing at the rate of 2 in. per min. Each preliminary draft gave approximately 30 pct reduction of area and was followed by a l-hr anneal at 1010°C in dry hydrogen. Three lots of wire were made with ultimate cold reductions of 31, 66, and 87 pct reduc-

Jan 1, 1965

By H. J. Modi, P. L. De Bruyn

In recent years interest has been aroused in flotation rate studies both from a technical and a more practical aspect. With increasing fineness of grind becoming a necessity in treatment of low grade ores, differences in flotation rates of various size ranges will assume importance in the evaluation of overall recovery results. Theoretical analysis of flotation kinetics was initiated by Schuhmann, who sought to define flotation rate of a given mineral and specified size range in terms of certain physical variables of the flotation system. Using as a basis for his analysis the bubble- particle encounter hypothesis previously advanced by Gaudin, Schuhmann writes for the rate of flotation (R,) of particles of average size x, [ ]

Apr 1, 1956

By Sydney H. Ball

MINERALS used primarily for personal adornment and decorative purposes are called precious stones. To be so prized, the stones must possess beauty of color, must not be too common, and must be hard enough to withstand ordinary wear. If transparent, they must have brilliancy and fire. Almost one hundred minerals have been used as precious stones, the noble gems being the diamond, emerald, ruby, and sapphire; pearls are frequently included by courtesy. These gem stones, however, are sometimes equaled in beauty by fine opals, aquamarines, ourmalines, spinels, chrysoberyls (both cat's-eye and alexandrite), and spodumenes (hiddenite and kunzite). The Greeks, Romans, and medieval Europeans grouped together gem stones according to color and degree of transparency, and only as the niceties of mineralogy began to be known, about a century ago, was it realized how many different minerals have the beauty required of gem stones. Pliny, for example, did not distinguish between rubies and the red varieties of spinel and garnet, although he conjectured that the beryl and emerald were one mineral. GENERAL SURVEY Early man treasured bright colored berries, attractive shells, white teeth of wild animals and brightly colored pebbles, and used them as personal ornaments. In the eastern hemisphere, the earliest stones used were members of the quartz family (100,000 to 75,000 B.C.); then obsidian and amber (50,000 to 25,000 B.C.); the jade minerals, fluorspar and jet (22,000 to 7000 B.C.); turquoise (7000 to 3400 B.C.); lapis lazuli and garnet (prior to 3500 B.C.) ; emerald (2000 to 1800 B.C.) ; sapphire, ruby and diamond (800 to 500 B.C.). Indeed, gem mining is the oldest form of mining, and before any metals were known primitive man recognized about 18 gems and decorative stones. At first he sought them in stream gravels and residual deposits but by 3400 B.C. the turquoise mines of the Sinai Peninsula were operated. This was the world's first important hard-rock mining enterprise. The Afghanistan lapis lazuli mines may

Jan 1, 1949

By H. E. Mills

THE local auditorium of a little Alabama mining town was crowded with expectant men, women and children, as the bulletin board had announced the addition of visiting entertainers to supplement the local talent and motion pictures which usually made up the program of the regular monthly safety meeting. In the audience, near the stage, sat a group of bright-faced boys in boy scout uniforms, discussing the picture just completed. As the lights flashed on a crash and scream was heard from the outside, a shrill whistle and word of command from the scoutmaster, and five of the scouts ran out of the hall, while the mine super-intendent stepped on the stage and requested everyone to keep their seats. The scouts returned, three of them carrying a limp figure in their arms, while the other two cleared the doorway and aisle of excited spectators. They marched to the stage and, placing the apparently badly-injured boy on the floor, proceeded to give an expert demonstration of first aid to the injured. The scoutmaster then explained to the audience that the whole affair had been arranged for their benefit, and invited the local first-aid men to come up on the stage to examine and criticize the boys' work. This gave an opening for several talks on the value of first-aid training and accident prevention, which is the main object of the monthly meetings. This demonstration was given by the first-aid team of Troop One, and the entertainment was provided by members of Troop One and Twenty-eight of the Bir-mingham Scout Council, organized by the writer for the purpose of promoting interest in the welfare and safety meetings in the mining villages of the State. During the past year they have visited a number of such meet-ings and presented programs similar to the one men-tioned above. However, in order to assure a good attendance, entertainment features must also be pro-vided, and the serious part of the evening program was interspersed with excellent vocal and instrumental mu-sic, dancing and novelty acrobatic acts furnished by the visiting scouts. In addition to the numerous first-aid teams of the Birmingham Council, there are hundreds of scouts scat-tered throughout the mining district whose knowledge of first aid, safety first, life-saving, personal health and public health are a constant source of protection to their community. All of these subjects are covered by merit badge pamphlets and are required of an eagle scout.

Jan 2, 1927

By T. D. Parris

Within a 30-mile radius of Sudbury, Ontario, the Ontario division of the International Nickel Co. of Canada, Ltd., operates nine underground mines and two open pits. Prior to 1966, ore removal from the underground workings was mainly by scraping, using 125-hp electric slushers in blasthole and caving mining, and 30-hp or less air-operated slushers for fill- method mining. The development and evaluation of low-profile, diesel-powered front-end loaders, designed specifically for underground operations, was followed with keen interest during the period 1964-1965.

Jan 6, 1969

By Roy Thomas

SOON after the Waelz plant for the fire concentration of low-grade zinc ores was put into operation in the early part of 1929 at Katowice, it was found that the conveyor equipment for transporting the hot residue from the furnace dust chambers was inadequate. Hand tram-ming with water cooling was used for a time, but that method was injurious to the workmen as well as costly. The problem was to find some practical mechanical means of conveying flue dust at temperatures of from 450° to 600° C. as it was drawn from the dust chambers. After considerable preliminary investigation it was decided to install pneu-matic equipment for conveying the hot materials to a central mixing plant, where it would be mixed with slime and from which it would be returned to the furnace feed hoppers. The first pneumatic equipment was installed in 1930, and has been in successful operation since that time. The pneumatic method of transportation has shown a considerable saving in operating costs over the former methods of dust handling and a decided improvement in working and hygienic conditions at the plant, through the elimination of the dust hazard. Additional pneumatic equipment was installed in 1933 for conveying the furnace fume from the baghouses to the roaster plant. At the same time pick-up lines were provided for collecting the cleanings from the vertical and horizontal cooling pipes that are between the furnace dust chambers and the baghouses. The latter installation has practically eliminated a dusty and costly hand-tramming operation.

Jan 1, 1939

By Douglas W. Fuerstenau, Kalanadh V. S. Sastry

Based on an analysis of green pellet size distributions and kinetic data on ball growth with taconite concentrates, a ballability index has been developed to quantify ball growth behavior as a function of moisture and bentonite additions. The applicability of the ballability index to such other particulate materials as pulverized limestone and ground magnesite is shown.

Jan 1, 1973

By R. C. Wilmoth, R. D. Hill, R. B. Scott

A cost breakdown is given for reclamation and mine drainage abatement conducted by the Federal Water Quality Administration's demonstration project near Elkins, W. Va. Costs for construction of control measures have been developed and include backfilling strip mines, sealing subsidence areas, reconstructing stream channels, and installing mine seals to prevent the entrance of water and air.

Jan 1, 1973

By H. I. Najarian

This paper is a companion piece to the description of the electrothermic process that begins on page 141. It will be confined to a brief story of the development. of the Weaton-Najarian vacuum condenserf at this plant, together with up-to-date design and operating data. The Josephtown smelter was designed primarily for production of zinc oxide. However, the development of a method for production of zinc metal had always been under consideration, and accordingly one of the original eight units of the elcctro-thermic furnaces built in 1930 was set up to produce metal. The design of this furnace was identical with that of the oxide furnaces except that in place of oxide tewels opening into oxide manifolds, conventional conical clay condensers—similar to condensers used in horizontal retort smelting—were installed around the periphery of the furnace and in several tiers vertically for condensing the zinc vapors. The early experimental work in trying to condense zinc out of the mixtures of zinc vapor and carbon monoxide gas from the electrothermic furnaces indicated that, while the gases from electrothermic smelting would condense in surface-type condensers, the formation of blue powder was excessive and condenser efficiency low. Furthermore, operating a large unit of electric furnace with several hundred small condensers, with attendant high labor cost and unfavorable operating conditions, did not appeal to us. We also realized that a single unit of surface condenser capable of condensing 12 torg tons of metal per day would be of huge dimensions and possibly difficult of control. So we took as our aim the development of a method whereby a single condenser unit of reasonable dimensions would condense zinc, in one step, from the large volume of gases that the electric furnaces produced. We set about searching for knowledge on zinc metallurgy and design of zinc condensers in particular. Our study of the prior art focused our attention on the oft-repeated statement by earlier experimenters, that the most efficient way to condense metallic vapors, such as zinc vapors, was to bring the vapors into "intimate contact" with molten metal; but the methods offered for securing this "intimate contact" in any practical manner left much to the imagination. We were handicapped by not having some-one on the Josephtown smelter staff who could lay claim to being an expert zinc metallurgist and could give guidance from actual experience on the practicability of various schemes that haunted our imagination. Laboratory Experiments However, we had an expert ex-steam engineer in the person of George I?. Weaton, manager of the Josephtown smelter, who had had long experience with steam-jet condensers and would reiterate his belief at every opportunity that the logical and the most efficient way to condense zinc would be with a jet-type condenser. We became intrigued by the possibilities of a zinc con-

Jan 1, 1944

By G. Sachs, L. J. Ebert, W. F. Brown

INTRODUCTION ISOTHERMAL transformation, or "austempering," of a carbon-containing austenite at elevated temperatures yields so-called "intermediate products." Their structure and properties are, for a given hardness, rather different from those of "tempered martensite" obtained on conventional quenching and tempering.1 Several investigators2,3 have found that for high carbon and slightly alloyed steels the intermediate products formed at temperatures close to that of the martensite reaction possess strength properties superior to those of tempered martensite. The structure of these low temperature, intermediate products is generally acicular (bainite) but clearly different from that of martensite. However, at higher austempering temperatures, between 1000 and 1300°F (540 and 700°C) carbon steels were found to exhibit a rather low ductility.4-5 Thus notch bar tensile tests showed the ratio between notch strength and regular tensile strength to decrease with increasing austempering temperature. For ductilities below a few percent this notch strength ratio is a measure of ductility, according to investigations on low alloy steels.6-7 Furthermore the presence of intermediate products formed unintentionally on quenching was considered as responsible for the low ductility and impact energy of some heat treated steels.8 These intermediate products could result from partial transformation at the so-called "nose-temperature" where the rate of the transformation is a maximum. Tempering improved such mixtures of martensite and intermediate products, their properties approaching those of tempered martensite of equal hardness. The following investigation constitutes an attempt to determine certain strength properties of a partially austempered and subsequently quenched low alloy steel, namely, a chromium steel (SAE 5140). The structures formed by such a treatment should consist of a mixture of intermediate products formed on austempering and a martensite formed on oil quenching from the austempering temperature. It was intended, by varying the austempering time, to vary the quantity of the intermediate products between zero and 100 pct. The austempering temperature of 860°F was selected after extensive preliminary tests close to the nose-temperature. Austempering at this temperature yielded an acicular intermediate product. Additional tests under less exacting conditions were made for an austempering temperature of 950°F where the intermediate product appeared to be very fine pearlite. To determine the effects of tempering on structures containing various amounts of

Jan 1, 1948

By T. R. Graham, R. S. Dean. J. R. Long

Although considerable information has been published concerning manganese additions to the aluminum bronzes, these data refer principally to the two-phase alloys containing 8 to II pet aluminum, with some incidental information on the single-phase alpha solid solution alloys. Straussl gives an excellent review of the literature on aluminum bronzes up to 1927 and a bulletin2 of the Copper Development Association brings the bibliography up to 1938. The most extensive work on manganese addition is that of Rosenhain and Lantsberry,3 who investigated alloys ranging up to 10 pct aluminum and up to 10 pct manganese, and presented data on the physical properties of sand-cast, chill-cast, and several wrought alloys. The greater portion of the work, however, concerns alloys ranging from 7 to 10 pct aluminum in the cast condition and sheds little light on the properties of wrought single-phase alloys. Corson4 notes that alloys containing 10 pct manganese and 4 pct aluminum are not hardenable by heat-treatment, while one with 15 pct manganese and 5 pct aluminum can be hardened, but he gives no tensile data on it. In fact, no systematic study of the properties of single-phase wrought alloys containing substantial amounts of manganese has been reported. It should also be noted that most of the investigators worked with alloys containing significant amounts of iron and silicon, and that these impurities, whether intentionally added or accrued from the raw materials used in the preparation of the alloys, may be expected to have a direct bearing on the resultant properties. In the work on alloys made with electrolytic manganese, the Bureau of Mines has undertaken an investigation of the copper-manganese-aluminum system for the purpose of establishing the constitution and properties of high-purity alloys. In a recent paper6 the authors reported a metallographic investigation of the alpha solid solution area and the adjoining fields of the copper-manganese-aluminum system up to 50 pct manganese. This study established the alpha-phase boundaries at 50" temperature levels from 400' to 850°C. It was found that the addition of manganese to copper-aluminum alloys decreases the solub%ty of aluminum in the alpha phase (Fig I), curving the boundary toward the copper-manganese base line. The greatest change occurs in the first 20 to 25 pct manganese, which decreases the solubility of aluminum to approximately 4 pct. With larger amounts of manganese the alpha boundary tends to parallel the copper-manganese binary. At 13oo'F and higher,

Jan 1, 1947

By R. S. Dean. J. R. Long, T. R. Graham

Although considerable information has been published concerning manganese additions to the aluminum bronzes, these data refer principally to the two-phase alloys containing 8 to II pet aluminum, with some incidental information on the single-phase alpha solid solution alloys. Straussl gives an excellent review of the literature on aluminum bronzes up to 1927 and a bulletin2 of the Copper Development Association brings the bibliography up to 1938. The most extensive work on manganese addition is that of Rosenhain and Lantsberry,3 who investigated alloys ranging up to 10 pct aluminum and up to 10 pct manganese, and presented data on the physical properties of sand-cast, chill-cast, and several wrought alloys. The greater portion of the work, however, concerns alloys ranging from 7 to 10 pct aluminum in the cast condition and sheds little light on the properties of wrought single-phase alloys. Corson4 notes that alloys containing 10 pct manganese and 4 pct aluminum are not hardenable by heat-treatment, while one with 15 pct manganese and 5 pct aluminum can be hardened, but he gives no tensile data on it. In fact, no systematic study of the properties of single-phase wrought alloys containing substantial amounts of manganese has been reported. It should also be noted that most of the investigators worked with alloys containing significant amounts of iron and silicon, and that these impurities, whether intentionally added or accrued from the raw materials used in the preparation of the alloys, may be expected to have a direct bearing on the resultant properties. In the work on alloys made with electrolytic manganese, the Bureau of Mines has undertaken an investigation of the copper-manganese-aluminum system for the purpose of establishing the constitution and properties of high-purity alloys. In a recent paper6 the authors reported a metallographic investigation of the alpha solid solution area and the adjoining fields of the copper-manganese-aluminum system up to 50 pct manganese. This study established the alpha-phase boundaries at 50" temperature levels from 400' to 850°C. It was found that the addition of manganese to copper-aluminum alloys decreases the solub%ty of aluminum in the alpha phase (Fig I), curving the boundary toward the copper-manganese base line. The greatest change occurs in the first 20 to 25 pct manganese, which decreases the solubility of aluminum to approximately 4 pct. With larger amounts of manganese the alpha boundary tends to parallel the copper-manganese binary. At 13oo'F and higher,

Jan 1, 1947

By J. R. Long, T. R. Graham, R. S. Dean

ALTHOUGH considerable information has been published concerning manganese additions to the aluminum bronzes, these data refer principally to the two-phase alloys containing 8 to 11 pct aluminum, with some incidental information on the single-phase alpha solid solution alloys. Strauss1 gives an excellent review of the literature on aluminum bronzes up to 1927 and a bulletin2 of the Copper Development Association brings the bibliography up to 1938. The most extensive work on manganese addition is that of Rosenhain and Lantsberry,3 who investigated alloys ranging up to 10 pct aluminum and up to 10 pct manganese, and presented data on the physical properties of sand-cast, chill-cast, and several wrought alloys. The greater portion of the work, however, concerns alloys ranging from 7 to 10 pct aluminum in the cast condition and sheds little light on the properties of wrought single-phase alloys. Corson4 notes that alloys containing 10 pct manganese and 4 pct aluminum are not hardenable by heat-treatment, while one with 15 pct manganese and 5 pct aluminum can be hardened, but he gives no tensile data on it. In fact, no systematic study of the properties of single-phase wrought alloys containing substantial amounts of manganese has been reported. It should also be noted that most of the investigators worked with alloys containing significant amounts of iron and silicon, and that these impurities, whether intentionally added or accrued from the raw materials used in the preparation of the alloys, may be expected to have a direct bearing on the resultant properties. In the work on alloys made with electrolytic manganese, the Bureau of Mines has undertaken an investigation of the copper-manganese-aluminum system for the purpose of establishing the constitution and properties of high-purity alloys. In a recent paper5 the authors reported a metallographic investigation of the alpha solid solution area and the adjoining fields of the copper-manganese-aluminum system up to 50 pct manganese. This study established the alpha-phase boundaries at 50° temperature levels from 400° to 850°C. It was found that the addition of manganese to copper-aluminum alloys decreases the solubility of aluminum in the alpha phase (Fig I), curving the boundary toward the copper-manganese base line. The greatest change occurs in the first 20 to 25 pct manganese, which decreases the solubility of aluminum to approximately 4 pct. With larger amounts of manganese the alpha boundary tends to parallel the copper-manganese binary. At 1300°F and higher,

Jan 1, 1947

Iron Ore Resources of the World (Die Eisenersvorrate der Welt)_ By G. Einicke. Verlag Stahleisen, Dusseldorf, 1950. 418 p., with 192 tables and an atlas volume containing 100 p. of reaps. 66 German Marks.-A notable work in which the latest available information on iron ore deposits has been compiled by diligent work, continent by continent, country by country. The author reveals the effect of geological formations, iron content of ore, accessability, cost of transportation, political and economic considerations. Ore beds of importance to the German iron and steel industry are given more space than others. The bibliography contains almost 250 references. A tragic comic feature is the author's complaint that as soon as a map of iron ore resources of a country has been completed, the country's boundaries are changed. Reviewed by W. Trinks, Carnegie Institute of Technology. Industrial Research Laboratories of the United States. National Research Council, Washington, D. C. Ninth Edition. 1950. 445 p. $5.-Contains information on the research laboratories of 2845 industrial and commercial organizations, including names of research executives, location of labs, types of activity, whether any consulting services are offered. There are two appendices, one of which lists data on government labo ratories which cooperate with industry, and the :)ibex naming universities and colleges offering research services to industry.

Jan 2, 1951

WHILE papers on cleaning coal and mining coal were presented at the iron and steel and mining methods sessions, respectively, the first general session on coal was held on Wednesday afternoon. Howard Eavenson of Pittsburgh, Pa., as chairman of the session,* reported progress by the Committee on the Valuation of Coal for Blast-Furnace Coke. A paper on blasting coal effectively and safely in Southern Illinois, by J. E. Tiffany and S. S. Lubelsky, was abstracted and commented on by Dan Harrington, of the U. S. Bureau of Mines. W. J. German commented on some conditions mentioned in the paper as unsafe or bad practices, and added to these some further ex-amples; he made a strong plea for holes to be: drilled parallel to the bedding as the easiest way to determine the proper length or depth to agree, with the depth of kerf cut. Mr. Barron called attention to proper cutting and-drilling and rate of detonation of the explosive used, as effective aids in blasting coal. Another speaker mentioned an odd case where compressed black powder or "pellet powder," had decreased accidents at a non-gaseous mine where permissible explosives had been formerly used; the permissible cracked or shattered the roof, with a resulting high accident rate from falls of roof, and pellet black powder overcame this trouble. Eugene McAuliffe of the Union Pacific Coal Co. told of difficulties in changing from black powder to permissible in Wyoming mines. J. B. Dilworth read a paper on valuation of coal prop-erties, expressing a preference for the method of capi-talizing the earning power of a property. Eli T. Con-ner of Scranton, Pa., with much experience in valuation work, stated that the method was undoubtedly good, but many times failed because of inability to forecast accurately future earnings, and further contended that total valuation -and royalty rates could generally be fixed fairly when based on similar neighboring proper-ties' rates when these had recently been established by a free bargaining. S. A. Taylor of Pittsburgh, Pa., stated that a leasehold value could be fairly established by figuring based on 10 to 20 per cent of the profit resulting from operation. The chairman read a written discussion from Henry Louis of England, called atten-tion to differences in valuation resulting from whether gross or net profit or earnings were used as a basis for capitalizing. John A. Garcia of Allen & Garcia gave a most inter-esting account of coal mining and general conditions in Russia as noted in his recent extensive visit there, which appears elsewhere in this issue. Although agree-ing with most thinking Americans that government operation is incompatible with progress, he showed that mining conditions were far from impossible in present-day Russia. Charles E. Stuart gave motion pictures of parts of the trip, with, his own comments supple-menting those of Mr. Garcia.

Jan 3, 1928

Coal Transport Via Pipe Line Claimed Feasible Moving coal via pipe line is a project proposed by the U. S. Bureau of Mines. A pipe line 100 miles long capable of transporting 5000 tons of coal a day with water could be built for about $10 million. The cost of moving the coal 100 miles would be between $1.28 and $2.01 a ton.

Jan 9, 1951

By Lowell S. Thomas

I have been asked to speak to you on the subject of "Scrap Metals from the Army." With your kind permission I'd like to change this subject to "Scrap Metals from Ordnance," as the Property and Salvage Section, which I head, is a part of the Office, Chief of Ordnance, and only handles Scrap, Cuttings and By-products produced by Ordnance establishments. Scrap, Cuttings and By-prod-

Jan 1, 1943

By R. I. Jaffee, H. P. Nielsen

In recent years much attention has been given to high melting alloy systems. It has been of interest in this respect to investigate the alloys of platinum and tungsten, which were known from the literature to have very high melting points up to about 50 pct tungsten, but about which little had been published on the high-tungsten side of the system. Powder metallurgical methods were used throughout this investigation for the preparation of the alloys, utilizing electrical sintering techniques such as are used for tungsten and molybdenum. In the course of the work it was found desirable to determine fusion temperatures of the alloys, and it was possible from these and other data to draw a tentative constitutional diagram (solidus, mostly) applicable to the high-temperature part of the system. No attempt was made to determine solid solubility vs. temperature data, nor to investigate the lower temperature transformations in the solid state. Data on the microstructure, hardness, and a note on oxidation resistance of the sintered alloys were obtained. Past Work Miillerl determined liquidus temperatures of platinum-rich alloys to 50 pct tungsten, using a radiation method employing a photoelectric cell, and found that the melting points increased progressively from I771 C for platinum to 2350°C for the 50 pct alloy. Microscopic evidence by Miiller that complete solid solutions exist to 50 pct tungsten was not checked by Kremer2 who, according to Vines and Wise,3 found that "although the 8 pct tungsten alloy was a solid solution, the 26 pct tungsten alloy contained a eutectic or an intermediate phase." Hultgren and Jaffee4 using X ray methods found continuous solid solutions to at least 33.6 pct tungsten (35 at. pct) after annealing in vacuum for 6 days at I000 C. Vines and WiseS report work communicated to them by E. C. Rhodes on wrought alloys to 7 pct tungsten, which showed that tungsten hardened platinum extremely rapidly, and was one of the most potent hardeners of the binary additions to platinum. Considerable quantities of 4 pct tungsten platinum wire have been produced for grids in radar tubes and for aircraft spark plugs. Some of the alloy for the latter application is made by sintering, the remainder by smelting and casting. Materials The platinum powder used in this work was kindly supplied by the Research and Development Laboratory of the Owens-Corning Fiberglas Corp., Newark, Ohio. It was prepared from scrap platinum. After dissolving in aqua regia and evaporating almost to dryness, the solution was worked up several times with concentrated HC1. The resultant platinic chloride was diluted considerably, and metallic zinc was added, which precipitated the platinum in a very finely divided form. After dissolving the

Jan 1, 1949

By J. E. Cannaday, R. J. Austin, R. K. Saxer

PREVIOUS investigators have determined activation energies and have postulated various controlling mechanisms for creep.'-' Recently Barrett et 01.I5 have suggested, as the result of their work with cadmium, that the apparent activation energies for creep (AHc) above 0.5 T, could be correlated by means of activation energies for self-diffusion (AHSD) and modulus of elasticity functions: AHC = AHSD - (5RT/E) dE/dT. The wide disparity of apparent activation energies previously obtained with nickel compared to those reported for other fcc metals and the desire to test the postulate of Barrett el al. prompted this study. The as-received 17.5-mil nickel wire used during this work assayed 99.87 pct pure, Table I. X-ray analysis indicated that the wire was in a stress-re- lieved state and metallographic examination revealed an equiaxed grain size of approximately 0.01 mm. Specimens degreased in acetone and cut to 1-1/2 in. lengths were tested in a cam-mechanized constant-stress creep machine. A vacuum of at least lo-5 mm Hg was maintained during all tests. Stresses were applied when thermal equilibrium was established. When a measurable (at least 0.5 pct) secondary creep was observed, the temperature was pulsed to a higher temperature. Pulsing time varied from 30 sec at 480°C to 2 min at 1300'C and above. Slopes of creep curves were determined after the initial acceleration in the strain rate had subsided and steady-state creep was achieved. To confirm the results obtained, additional tests were performed incorporating a temperature pulsing method suggested by sherby. In this method the load was removed during temperature pulsing and reapplied after thermal expansion had occurred. No appreciable differences in results were obtained. Tests were performed over a wide range of temperature (470" to 1310°C) and stresses (250 to 17,000 psi). The expression was used to calculate activation energies. In this expression T1 and T2 are the initial and final temperatures, and el and i2 are the creep rates at T, and T2. The variation of the apparent activation energies with the mean test temperature calculated by means of Eq. [I] are shown in Fig. 1. The mean test temperature (Tmean) was calculated from the relationship

Jan 1, 1967