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By Rudolf Gahl

Page Tests Conducted in Small Test Mill................... 577 Demonstration Tests Conducted by Minerals Separation Co....... 577 Flotation Tcsts Conducted by Inspiration Co............. 577 Sampling of Orebody........................ 578 Other Results Obtained in Small Test Mill.............. 580 Tests Conducted in Large Test Mill................... 580 Flow Sheet............................. 580 Discussion of the Value of Preliminary Table Treatment......582 Callow Flotation Installation..................... 585 Flinn-Towne ~nstallation...................... 587 Cole-Bergman Installation...................... 588 Methods Followed in Competitive Tests................ 590 Advantage of Pneumatic Flotation Machines.............. 591 Pneumatic Machines of Minerals Separation Co............. 591 Float Skimming Device......................; 594 Experimental Inspiration Flotation Machine.............. 596 Arrangement of Callow Cells in Series ................ 598 Variations of Flow Sheet....................... 599 Coal Tar as Flotation Agent..................... 600 Experience with Primary Slime.................... 602 Influence of Iron on Flotation..................... 605 Influence of Chemicals on Primary Slime............... 607 Fineness of Crushing Desired.................... 607 Operation of Large Concentrator..................... 608 Flow Sheet of Callow Sections.................... 608 Flow Sheet of Inspiration Sections.................• 609 Inspiration Flotation Machine of Steel Construction.......... 610 Minerals Separation Section..................... 613 Filter Plant............................ 613 Results Obtained in Commercial Concentrator............... 616 Tonnage............................... 616 Air and Power Consumption...................... 616 Floor Space............................ 617 Water Consumption......................... 617 Recovery............................. 618 Oil Consumption.......................... 618 Operating Costs for Flotation..................... 620 Discussion of Results Obtained.................... 620 Prospects for Futurc Development of the Flotation Process......... 621 Porous-Bottom Experiments..................... 622 Raising the Grade of Concentrates.................. 624 Recovering Carbonates by Flotation................. 624 Recovery of Silicates by Flotation.................. 627 General Theory......................... 628 Conclusion............................... 630

Jan 1, 1917

By Paul M. Tyler

Higher freight rates and better methods of beneficiation now may make it more economical to open inferior deposits closer to a glass factory than to work higher-grade deposits farther away. Nature of impurities and special treatments as well as common practice of sulphuric acid leaching are described. HISTORICAL concepts of the economics of the glass-sand industry are changing rapidly. The greatly expanded demand for glass containers combined with higher freight rates on raw materials and manufactured products have induced a migration of glass factories toward densely populated centers and the creation of new standards of place value for substandard sand deposits. This migration has been facilitated by the construction of pipelines to bring cheaper natural gas and liquid fuel to large cities and may be further speeded by the adoption of modern mineral dressing methods to permit economical utilization of local raw materials. Our national resources of naturally high-grade silica sand are abundant, but most of the best deposits are situated so far from large centers of population that it now costs $3.00 to $5.00 a ton to carry the sand from the mine to the optimum site for a factory making beverage bottles, scientific and electrical glassware, and miscellaneous blown and pressed ware for local markets. It follows that on the basis of freight savings alone it may be economical to use material from inferior deposits closer to the factory even though the f.O.b. cost of mining and treatment may be much higher than at a higher grade deposit farther away. Particle-size distribution is a feature of glass-sand specifications. As long as glassmakers insisted upon having their sand principally coarser than 100-mesh, any material was automatically excluded from consideration that could not be purified without fine grinding or other drastic treatment which greatly reduces the size of the quartz grains. However, re- cent large-scale tests in Norway' showed that finely-crushed quartz used in a soda-lime-silica glass batch caused it to melt and become refined appreciably faster than when ordinary coarse (Belgian) sand was employed. Dust losses were negligible. Since the pre-war cost of sand was only 3 pct of the manufacturing cost of the glass, it was deemed economical to pay twice as much for crushed quartz because of the saving in wear and tear on the furnace walls. In the author's unverified opinion, sand ranging in size between 150 and 400-mesh would probably be superior to that in the more usual range of 20 to 100-mesh. Former objections to fine sand (other than dust) were doubtless fostered by the natural concentration of impurities in the finer sizes. Ordinarily the most objectionable, as well as the commonest, impurity from the standpoint of the manufacturer of any but the cheaper qualities of colored glass is iron. No natural sands are really pure silica. Even water-clear quartz crystals are likely to contain impurities in the form of solid solution as well as inclusions which cannot be eliminated except by chemical treatment that will break down the silica lattice. Pure white pegmatite quartz will usually analyze 0.01 pct or more of iron oxide, and ordinary vein quartz and the quartz grains in most

Jan 1, 1951

By Paul M. Tyler

Higher freight rates and better methods of beneficiation now may make it more economical to open inferior deposits closer to a glass factory than to work higher-grade deposits farther away. Nature of impurities and special treatments as well as common practice of sulphuric acid leaching are described. HISTORICAL concepts of the economics of the glass-sand industry are changing rapidly. The greatly expanded demand for glass containers combined with higher freight rates on raw materials and manufactured products have induced a migration of glass factories toward densely populated centers and the creation of new standards of place value for substandard sand deposits. This migration has been facilitated by the construction of pipelines to bring cheaper natural gas and liquid fuel to large cities and may be further speeded by the adoption of modern mineral dressing methods to permit economical utilization of local raw materials. Our national resources of naturally high-grade silica sand are abundant, but most of the best deposits are situated so far from large centers of population that it now costs $3.00 to $5.00 a ton to carry the sand from the mine to the optimum site for a factory making beverage bottles, scientific and electrical glassware, and miscellaneous blown and pressed ware for local markets. It follows that on the basis of freight savings alone it may be economical to use material from inferior deposits closer to the factory even though the f.O.b. cost of mining and treatment may be much higher than at a higher grade deposit farther away. Particle-size distribution is a feature of glass-sand specifications. As long as glassmakers insisted upon having their sand principally coarser than 100-mesh, any material was automatically excluded from consideration that could not be purified without fine grinding or other drastic treatment which greatly reduces the size of the quartz grains. However, re- cent large-scale tests in Norway' showed that finely-crushed quartz used in a soda-lime-silica glass batch caused it to melt and become refined appreciably faster than when ordinary coarse (Belgian) sand was employed. Dust losses were negligible. Since the pre-war cost of sand was only 3 pct of the manufacturing cost of the glass, it was deemed economical to pay twice as much for crushed quartz because of the saving in wear and tear on the furnace walls. In the author's unverified opinion, sand ranging in size between 150 and 400-mesh would probably be superior to that in the more usual range of 20 to 100-mesh. Former objections to fine sand (other than dust) were doubtless fostered by the natural concentration of impurities in the finer sizes. Ordinarily the most objectionable, as well as the commonest, impurity from the standpoint of the manufacturer of any but the cheaper qualities of colored glass is iron. No natural sands are really pure silica. Even water-clear quartz crystals are likely to contain impurities in the form of solid solution as well as inclusions which cannot be eliminated except by chemical treatment that will break down the silica lattice. Pure white pegmatite quartz will usually analyze 0.01 pct or more of iron oxide, and ordinary vein quartz and the quartz grains in most

Jan 1, 1951

By W. J. Taylor, H. J. Mutz, A. F. Brock

THE International Kickel Co. of Canada Ltd. operates five underground mines and an open pit. Four of the mines, the Frood-Stobie, Creighton, Murray, and Garson, are on the south range of the Sudbury Basin, map above, within a radius of 10 miles of the city of Sudbury, Ontario. The fifth mine, the Levack, is on the north range of the Sudbury Basin, 30 miles to the northwest of the city. The open pit is operating on surface ores of the Frood-Stobie orebody. Two pits were opened at the Frood-Stobie mine; the Frood section was started in 1938 and the Stobie section in 1942. To meet the heavy demand for nickel during World War 11, open-pit production was accelerated until it constituted over 40 pct of Inco's total tonnage. As a consequence open-pit ore was depleted considerably alhead of schedule; the Stobie pit was completed in the summer of 1951, and it is expected that mining at the Frood pit will be completed in 1953. The major program launched 10 years ago to develop additional underground production as a replacement of open-pit tonnage thus had to be greatly speeded up. This conversion to all-underground mining will be completed within the next two years, and the underground mines will then have an annual hoisting capacity of 13,000,000 tons. One of the new mines in the underground expansion program, the Murray, was brought into production in 1950. Ore production from the new Stobie section of the Frood-Stobie mine was commenced on a limited scale in 1951 and will be increased as the program progresses. Delivery of ore to the new Creighton mill was started in the summer of 1951 from the caving project launched at Creighton mine. When mining was started in the Sudbury district 65 years ago the ore deposits were opened on a small scale and mining methods conformed to a general pattern of small open cast pits, followed by open stopes as mining was extended below the pits. The open stoping methods used were heading-and-bench and shrinkage. In certain cases a type of cut-and-fill mining was used with drywall tramways and dry-wall chutes in the fill. As the mines were deepened,

Jan 1, 1954

By D. Harker, M. J. Murphy

The mechanism by which age-hardening takes .place is still not completely understood. The principal theories range from the extreme of "precipitaiion-hardening" to that of "order-hardening," with many intermediate gradations. In the hope of obtaining new data on which to base a choice among the many theories, the authors have made electron micrographs of formvar replicas taken from metallic specimens at various stages of age-hardening. The results so obtained on an alloy of 2 per cent beryllium in copper and one of 20 per cent molybdenum in iron will be described in the following pages, as well as the technique used in preparing the replicas. Preparation of Formvae. Replicas of Metallic Specimens This section is concerned with the techniques that have roved successful in preparing formvar replicas for studying the microstructure of metals with the electron microscope. Because of its simplicity and accuracy, the formvar replica1 method developed in the General Electric Research Laboratory has been used exclusively, since it is much simpler than the silica replica method of Heidenreich and Peck2 and produces as good results. The formvar method to be described requires a technique acquired only by practice, and no foolproof set of rules can be given. it is a rapid method and a replica can be obtained in less than five minutes under favorable conditions. This does not mean that perfect replicas can be produced every five minutes, but rather that one can well afford to take several strippings* in order to produce a replica of high quality. The metallographic technique required for replica work—very fine polishing and etching with very dilute solutions—is described here. It can be said, in general, that almost any surface that has been carefully prepared for a photomicrograph at 1000 or more diameters can be used to obtain a replica for the electron microscope. Preparation of Metallographic Specimens The preparation of the metallographic specimens is somewhat more exacting than that usually given to samples to be used for inspection under the light microscope. After much experimentation, it was concluded that the best method consists in polishing the metal through to the coarse cloth, then etching and repolishing on final cloth until the layer of distorted metal is removed. After this procedure has been completed, a dilute etch—to approximately the depth necessary for a micrograph at 1000 diameters—usually produces a sur-

Jan 1, 1945

By R. D. Pehlke, P. D. Goodell, R. W. Dunlap

The rate of dissolution of steel bars in molten pig iron has been measured experimentally in the temperature range 2300° to 2650° F. The rate of solution is shown to be a .function of bath composition, temperature, and stirring. A kinetic model based on carbon diffusion in the liquid phase has been derived to fit the experimental results. THE rate of scrap melting has long been an important variable in steelmaking operations. With the advent of the oxygen steelmaking process and the accompanying shorter heat times, the rate of scrap melting has now become one of the rate-limiting factors in steel production. As observed in commercial practice, the solution rate is influenced by the compositions of liquid and solid, the temperature, agitation, and time. However, no definitive work has been done on the Fe-C system, and there is very little information in the literature regarding the relative effects of these variables in steelmaking systems. A number of questions have been raised in regard to scrap utilization in basic oxygen steelmaking operations. Consideration has been given to the optimum size and shape of scrap, and to the use of preheated scrap as a means for decreasing the pig-iron requirement in oxygen blowing. The determination of an optimum scrap practice for a specific installation depends to a large extent upon the economics of the scrap market and also upon the behavior of scrap in the vessel. The present research was undertaken as a preliminary study in evaluating the behavior of steel in a pig-iron bath under various conditions of temperature, composition, and agitation, as might be encountered in oxygen converter operations or in any steelmaking operation where scrap behavior is an important process variable. Related studies have been carried out on non-ferrous systems. The solution rate of solid aluminum in a molten A1-Si alloy has been studied.' Furthermore, the increasing use of liquid metals has created considerable interest in studies related to dissolution of a solid in a liquid, or mass transfer taking place between a solid interface and a liquid metallic phase.2-10 In an effort to clarify the relative importance of factors influencing the dissolution of scrap in Fe-C alloys, this paper presents the results of a study of the rate of dissolution of a low-carbon steel cylinder in a molten Fe-C bath at various bath compositions, temperatures, and conditions of agitation. An attempt has been made to determine the mechanism of solution, and a model has been derived to fit the experimental results. The rate of heat transfer between the molten pig-iron bath and the solid-steel cylinder has also been studied. EXPERIMENTAL PROCEDURE A molten bath of pig iron (nominal composition 4.2 pct C, 0.5 pct Mn, 0.8 pct Si)* was held in a 200- *In view of the fact that the composition of the pig-iron bath was slowly changing with time because of steel dissolution and reaction with the surrounding atmosphere, intermittent samples of the liquid bath were taken throughout each experiment, Table 1. lb induction melting unit. The internal diameter of the furnace was 8-1/2 in. and the bath depth approximately 14 in. Cold-finished 1020 steel cylinders of 1/2-, 3/4-, 1-, 1-1/2-, and 2-in. diameters were cut into 1 -ft lengths for use as test specimens. One end of each bar was machined to fit a hand-driven, mechanical stirring device which rested on top of the furnace. This fixture permitted 7 to 8 in. of the bar to be immersed in the melt. The steel cylinders were cleaned to free the surface of grease and oxide. The rods, at ambient temperature, were immersed into the molten pig-iron bath. The melt temperatures studied in this investigation were 2300°, 2500°, and 2650°F. Different agitation conditions were achieved by operating with a) the power to the furnace, giving induction stirring; b) induction stirring plus mechanical stirring, using hand rotation with a chain and sprocket assembly at approximately 200 rpm; c) mechanical stirring alone with the power off; and d) the power off and no mechanical stirring resulting in minimum agitation, i.e., only that caused by natural convection currents in the bath. The samples were immersed in the melt for prescribed times ranging from 30 sec up to 6 min. Immersion times were measured with a stopwatch and temperature control of the melt was achieved by power adjustment following temperature measurement with an optical pyrometer. The measurements with the calibrated pyrometer were checked out to within less than 10°F with simultaneous thermocouple measurements. Following immersion, the bars were water-quenched and the diameters were measured with a micrometer at several positions on the reduced area, and by volumetric displacement. The dissolution rates calculated from the

Jan 1, 1965

By S. L. Sass

DURING an electron microscope study of the w phase in zirconium-base alloys,1 a stereographic technique was devised which allows the synthesis of high energy electron diffraction patterns from a single crystal containing several variants of a second phase. The technique will be described using as an example the w phase which forms in a bcc matrix. The w phase was suggested by Silcock et al.2 and Bagaryatskii et al.3 to have a hexagonal structure with (0001)111(111)^, [001]B//[110]B* *The subscripts B and 1 are used to refer to the bcc phase and one particular orientation of the w phase, respectively. and with cell parameters aw = v2aB, where a^ is the lattice parameter of the bcc struc-ture. Since there are four <lll>B directions there should be four orientations of the w phase. In approaching this problem the question to be answered is, "What reciprocal lattice vectors from the B phase and the four w variants lie in the particular reciprocal lattice plane of interest?" One may restate the question in the form, "What plane normals from the B phase and the four w variants lie in the particular reciprocal lattice plane of interest?" The question is answered and the desired diffraction patterns are plotted using the following stereographic technique. Knowing the cw/aw ratio (=0.613 for the as-quenched form of the w phase), a stereographic projection of plane normals from one w variant can be constructed relative to a cubic projection using the above orientation relations, with the direction of the projection along the [001]B direction, Fig. 1. Let us now synthesize the diffraction pattern observed by looking along

Jan 1, 1970

By Walter J. Johnson

The coals in northern Wyoming and Montana are free-burning and non-caking and range from lignite to bituminous C in rank. Strip and underground mining are employed to supply railroad, utility, industrial, and domestic fuel. The market area includes Iowa, Nebraska, Minnesota, North and South Dakotas, Wyoming, Montana, the Pacific Northwest, and western Canada. THE larger producing coal mines in northern Wyoming are located in the Powder River Basin lying between the Black Hills region of South Dakota, eastern Wyoming, and the Big Horn Mountains in north central Wyoming, see Fig. 1. The mines are located particularly in the area along the route of the Chicago, Burlington & Quincy Railroad from Gillette, Wyo., to a point approximately 15 miles northeast of Sheridan, Wyo. Fig. 2 is a graph of coal production in the state of Wyoming from 1918 to 1951. Across the Big Horn Mountains lies the Big Horn Basin, situated between the Big Horn Mountains and the Rocky Mountains proper. Mining in the Big Horn Basin is almost entirely confined to a small area known as the Gebo Field, near the town of Kirby, which is located on the Chicago, Burlington & Quincy Railroad. This paper will describe present operating areas, making only brief reference to the history of mining and marketing primarily because of the large area to be discussed. The coal beds presently mined in the Powder River Basin are all of Tertiary age and are of Fort Union and Wasatch formations of Paleocene and Eocene ages, see Fig. 3. The Fort Union formation, consisting of 2000 to 3200 ft of alternate sandstone, shale, and coal, is divided from oldest to youngest into the Tullock, Lebo Shale, and Tongue River members. Most of the mineable coal is in the Tongue River member, which is 500 to 800 ft thick. The Carney coal bed, varying from 7 to 20 ft in thickness, is considered the base of the Tongue River member. About 85 ft above the Carney is the Monarch bed, ranging from 18 to 42 ft in thickness. At approximately 210 ft above the Monarch is what is locally known in the Sheridan district as Dietz No. 3 bed, which varies from 12 to 30 ft in thickness. One hundred feet above the Dietz No. 3 is Dietz No. 2 bed, which is 7 to 12 ft thick. At about 100 ft above the Dietz No. 2 is Dietz No. 1 bed, 7 to 15 feet in thickness. Two hundred and fifteen feet above Dietz No. 1 is the Smith bed, approximately 5 ft thick. One hundred twenty-five feet above the Smith is the Roland bed, which is estimated to be approximately 13 ft thick. The Roland bed is considered the base of the Wasatch formation, which in the Powder River Basin is 1000 to 3500 ft thick and is composed largely of shale, sandstone, and coal. The foregoing measures are the only ones above the Tongue River member that have been mined in the Sheridan field. To the east of the Sheridan field, particularly in the area of Gillette, the Roland bed is considerably thicker and is considered the thickest and most extensive coal bed in Wyoming, reaching a maximum thickness of 106 ft. From 125 to 225 ft above the Roland lies the Arvada bed, average thickness 9 ft. Three hundred seventy-five to four hundred feet above the Arvada is the Felix bed, which reaches its maximum thickness of 30 ft near Echeta on the Chicago, Burlington & Quincy Railroad. East of the Powder River the bed averages more than 10 ft in thickness, but it thins in a northwesterly direction. The highest mineable coal in the Powder River field is the Healy bed, about 400 ft above the Felix bed and exposed only in the highest parts of the area where much of it has been burned along the outcrop. Where it has not been burned, the thickness at most of the outcrops is 10 to 15 ft.

Jan 1, 1954

By J. W. Freeman, J. P. Rowe, R. F. Decker

HEAT-to-heat variations in properties of an alloy of constant nominal chemical composition have been a perplexing problem to the metallurgist. These heat-to-heat differences have been especially baffling in high-temperature metallurgy. In order to establish fundamental reasons for these heat-to-heat variations, the National Advisory Committee for Aeronautics has sponsored and financially assisted an extended research program on heat-resistant alloys at the University of Michigan. As part of the program to find the contribution of processing variables, Frey, Freeman, and white&apos; studied effects of heat treating on nickel-base alloys and Ewing and reeman&apos; investigated effects of hot-working practice on N155 alloy. To extend the program to the study of effects of melting practice on high-temperature properties, a 55 Ni-20 Cr-15 Co-4 Mo-3 Ti-3 pct A1 composition was selected for experimentation. The objective of this program was to establish the melting-practice variables which influenced the hot-working characteristics and creep-rupture properties and, at the same time, establish the metallurgical mechanisms for the effects. During the course of the investigation of practices using vacuum melting, it became increasingly evident through chemical analyses supplied by industrial concerns that a major variable was melt reaction with the crucible. This paper is devoted to the results of this phase of the melting-practice study. EXPERIMENTAL PROCEDURES Experimental 10-lb heats were induction melted in the University of Michigan vacuum-melting unit with the melting practices outlined in Table I. Aim analysis for the basic alloy, in wt pct, for all heats was as follows: Cr Co Mo Ti Al 20.0 15.0 4.0 3.1 3.1 Mn Si C Ni 0.12 0.12 0.08-0.15 Bal. Small amounts of boron and zirconium were added to certain heats as listed in Table I. These additions

Jan 1, 1959

By D. Kramer

HASEN1 has published a phase diagram for the zirconium-nickel system. This phase diagram has been redetermined by Hayes, Roberson, and paasche2 in the range 0 to 50 at. pct Ni. Recently, Smith and Guard3 have published a tentative diagram for the

Jan 1, 1960

New York Meets first Wednesday after first Tuesday of each month. DAVID H. BROWNE, Chairman. PERCY E. BARBOUR, Vice-Chairman. A. D. BEERS, Secretary, 55 Wall St., New York, N. Y. C. A. BOHN, Treasurer. Boston Meets first Monday of each winter month. W. E. C. EUSTIS, Chairman. - R. L. AGASSIZ, Vice-Chairman E. E. BUGBEE, Secretary-Treasurer, Mass. Inst. of Technology, Boston, Mass. ALBERT SAUVEUR, H. L. SMYTH. Columbia Holds four sessions during year. Annual meeting in September or October. STANLY A. EASTON, Chairman. FREDERIC KEFFER, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. D. C. LIVINGSTON. FRANK A. ROSS.

Jan 12, 1916

By E. H. Jr. Dix

THE consideration of alloying elements for aluminum has led to a series of investigations of the equilibrium relations between aluminum and those alloying elements. Therefore, the aluminum end of the aluminum-antimony diagram has been studied. The general form of the aluminum-antimony equilibrium diagram has been worked out by Campbell and Mathews1 and by Tammann.2 Campbell and Mathews described principally the beginning of solidification. They found the curve of beginning of solidification to rise gradually from the melting point of pure aluminum to a maximum at about 67 per cent. aluminum. After a slight lowering of the curve at a little greater antimony concentration the curve again rises to a maximum at 18.4 per cent. aluminum, which corresponds to the compound AlSb. The curve then drops to the melting point of pure antimony. Tammann explained the maximum occurring at about 67 per cent. aluminum as the result of the slow formation of the single compound AlSb. The space lattice of the compound AlSb, according to Owen and Preston,3 is face-centered cubic, the antimony atoms being intermeshed with an identical aluminum lattice. Very little, if any, work has been done on aluminum alloys containing small amounts of antimony.

Jan 1, 1930

By R. W. Gurry

In a series of charts this paper presents the composition of all gas mixtures, composed of the elements carbon, hydrogen, oxygen and nitrogen, which at temperatures from 1000° to 1800°F are in equilibrium with (1) austenite of various carbon contents, (2) iron and iron carbide, (3) graphite, (4) iron and its oxide. THIS paper presents the results of calculations made to determine the proportions of CO, CO2, CH4, H2, H2O and N2 in gas mixtures which, at temperatures from 1000" to 1800°F, satisfy, individually, the following conditions: (1) equilibrium with carbon steel of specified carbon content throughout the stable 7 iron region; (2) equilibrium with iron and iron carbide, both above and below the eutectoid temperature; (3) equilibrium with graphite; (4) equilibrium with iron and its oxide. From these data a new type of chart has been prepared which permits one to determine, from a room-temperature analysis of the furnace gas in question, the effect of the gas upon the steel at furnace temperature. Thus a guide is provided as to the carbon content which will result and as to the possibility of oxidation or sooting. All of the atmospheres commonly used in the commercial heat treatment of steel are composed of some or all of the simple constituents CO, CO2, CH4, H2, H2O and N2, and also in some cases oxygen or higher hydrocarbons. As the gas mixture is heated certain alterations in the proportions of the constituents take place, and at the temperature of the furnace the composition is, in general, not at all that of the entering gas. If equilibrium in the gas phase is presumed a calculation involving the use of certain fundamental data predicts for a certain temperature the carburizing, decarburizing, or sooting characteristics of a given atmosphere, and, upon the additional assumption of equilibrium between gas and metal, also the oxidizing ability of the gas and the ultimate carbon content of the steel. The extent to which these predictions are fulfilled will depend upon how closely the assumptions of equilibrium are realized in any particular case. Although at lower temperatures equilibrium is often not reached, there is considerable evidence indicating that above about 1000°F the approach to equilibrium in the gas phase is generally substantially complete, particularly in the vicinity of the steel which acts as a powerful catalyst in promoting reactions in the gas phase. The extent of the gas-metal reactions is commonly affected essentially by the sojourn at temperature; equilibrium with respect to carbon, for example, is accomplished simply by continuing the treatment long enough. However close the approximation of equilibrium may be in any instance, the above mentioned calculation indicates the condition of the steel at equilibrium, and at the present time this is the only basis of control of a furnace atmosphere. The effect at elevated temperature of a gas of a certain composition at room temperature upon a given steel has customarily been judged by first calculating from gas equilibrium constants the proportions of the gas constituents at the temperature of the steel, then comparing certain of these with the proportions known to be in carbon or oxygen equilibrium. This process is tedious and time-consuming, in particular because the calculation generally involves a series of successive approximations; and since some knowledge and familiarity with this type of computation are required, not everyone needing the information has been, in the past, in a position to obtain it. By making a series of equilibrium calculations, combining with fundamental data for gas-metal reactions, and plotting the results in a special way, a chart has been prepared which enables anyone

Jan 1, 1951

By F. L. Wolf

The catenary system of line construction possesses so many desirable characteristics from the operating standpoint that it has wide application for all types of electric traction. Many steam roads are electrifying sections of their lines, and in most cases are operating both steam and electric locomotives over the same track. This means that the overhead catenary system is subjected to the severe corrosive action of locomotive smoke, and data concerning the resistance of various alloys to this form of corrosion are very desirable from every point of view. Reliable and specific information and data on the subject of corrosion due to steam and smoke from locomotives are extremely meager and, on this account, extensive service tests, together with accelerated tests, have been made on a number of commercial metals and alloys. The observations and data recorded in this paper are the result of a preliminary test which was started in 1923 and which has been carried on to the present time. The recognition of the need for even more detailed and accurate data has resulted in the undertaking of another test which has been in progress for about a year. The result of this test will be published in due course. Some years ago The Ohio Brass Co. was asked by one of the large steam railroad companies to furnish data on construction details for a catenary system which it was considering for one of its divisions. The selection of materials which would give the necessary physical characteristics as well as withstand the severe corrosive action of locomotive gases caused electrical railroad engineers considerable concern. At that time, there were available no specific or authentic data on these important questions: no systematic investigation of the problem appeared to have been made, even though it&apos;s importance was generally recognized. Such observations as had been made were crude in that they had been limited largely to visual inspection which too frequently is most misleading. However, the scattered information which was collected gave important clues as to how best to start an investigation. Technical literature was studied, metallurgical experts were consulted, and the problem was discussed with engineers who were in close contact

Jan 1, 1930

By H. K. Birnbaum, H. B. Aaron

he authors suggest that a number of the types of yield phenomena which have been observed in high-purity fcc metals are due to dislocation interactions bccurring at the surface of the crystals rather than due to volume effects. Since rather different inter-pretationS2,7,12,14,15,21-23 of these effects have been suggested, it is of some importance to ascertain the role of the surface in these yield phenomena. It should be first noted that the high-purity fcc metals appear to exhibit several distinct types of yield phenomena. The "unloading yield point" which is observed on reloading the specimen after removing the applied load has been found to be independent of the time of holding in the unloaded condition. If however the specimen is aged while under load and re-tested without removing the load, a yield point is observed which does depend on the aging time and tem-perature. Feng and Kramer suggest that the removal of the unloading yield point on removing sufficient material from the surface of the specimen indicates that the effect is associated with dislocation interactions at the specimen surface. Their observations are counter to those of Haasen and Kelly5 and Birnbaum.12 Since the unloading yield points are extremely small (-2 pct of the flow stress) the results of the surface removal will depend on whether the material is removed uniformly over the gage length. The introduction of small etch pits or the removal of more material from one portion of the specimen than from another will result in preferential yielding and obliteration of the yield point. With the normal electropolishing techniques it would be difficult to avoid these effects. The data obtained by Aaron and Birnbaum, Fig. 10, on aluminum polycrystalline specimens indicate that, although the unloading yield point and the strain-aging yield point are not simply additive, a time- and temperature-dependent yield point is observed under conditions where no creep is observed. This does not agree with the results of Feng and Kramer but does agree with the results on copper15 and gold.7~23 The source of the discrepancy may be the procedure used by Feng and Kramer to correct their time-dependent yield points for the effect of creep. Since the strain-aging yield point is not independent of the pre-aging strain rate, Fig. 11, the effects of creep cannot

Jan 1, 1967

By Irwin Roman

NUMEROUS results and formulas have been published for analyzing seismic records, but most of them apply only to large-scale phenomena such as are encountered in studying earthquakes. In a few cases,1 formulas have been published for some of the simpler structures. In the present paper, an attempt will be made to analyze several types of struc-tures without using methods more advanced than those of a first course in calculus. In, tracing a disturbance through a medium, it is almost always possible to base the analysis on Fermat&apos;s Principle of Extreme Time, which states that waves of displacement travel between points in such a manner as to make the time of travel an extremum with respect to all neighboring paths. In the simpler cases, comprising most of those used in optics or geophysical prospecting, this time is a minimum and the principle is often referred to as the Principle of Least Time. Within a homogeneous medium, having a uniform speed of transmission of the disturbance in all directions and throughout the medium, the paths are straight and are refracted at the interfaces in accordance with the Snell law of refraction, which states that the ratio of the sine of the angle, made by the ray with the normal to the interface, to the speed of trans-mission is the same on both sides of the interface. Thus, in any medium composed of homogeneous sections, this same ratio has a constant value at all points. In particular, if all interfaces are horizontal, it is apparent that the angles of incidence are the angles made by the ray with the vertical direction. Furthermore, the incident ray, the refracted ray and the normal to the interface are all in the same plane at each refraction;

Jan 1, 1933

By M. G. Nicholas

The influence of deformation, relative movement and surface cleanliness on the strength of room -temperature "interparticle" bonds between copper surfaces has been studied. No bonding resulted when clean surfaces were merely pressed together, even under pressures of 50,000 psi. Bonding resulted, however, when clean surfaces were simultaneously pressed and moved relative to each other, some bonding occurring no matter how small the pressure or relative movement. Exposure of the clean surfaces to various chemicals inhibited bonding, none at all being produced by small relative movements. The size of the movements which first produce bonding between exposed surfaces depends on the nature of the chemical, being less than 0.002 in. for cleansing reagents and greater than 0.004 in. for lubricants, water and hydrogen sulfide. It is concluded from the experimental data that the prime requirement for bonding is the dispersal of surface films such as oxides and adsorbed contaminants. THE formation of interparticle bonds during the room-temperature compaction of powder metallurgy components greatly increases the ease of handling in subsequent production operations prior to sintering. The strength of unsintered compacts follows the same general trends as their density and hardness, but quantitative data are extremely Scarce. Quantitative correlation of the data on the overall strength of a compact with that of the individual interparticle bonds is virtually impossible due to the extremely complex geometry of powder compacts. Qualitatively, however, the strengths of unsintered compacts can be correlated with variations in parameters known to influence the extent of cold bonding, and hence interparticle bonding, such as surface cleanliness, relative movement, and deformation of the mating surfaces. Kuzmic and seelig4 found that contamination of powder particle surfaces with lubricants reduced the strength of unsintered iron and copper compacts. Interparticle shear has been shown to promote bonding by Train and Hersey7 while Gregory has shown that die rotation is beneficial. Eilender and schwalbe6 concluded that most bonding occurred during the early stages of pressing iron powder compacts when interparticle shear is one of the principal processes occurring. mile there can be little doubt that these and other factors, such as particle size and shape, affect the extent of interparticle bonding produced by compaction, evaluation of the influence of individual factors is not easy. Particle deformation and relative movement, for example, occur simultaneously during compaction, making any precise measurement of their relative influences difficult. Because of these and other difficulties encountered in studying interparticle bonding in actual powder compacts, the approach adopted in this study was to

Jan 1, 1963

By Henry F. Adams, Guy H. Ruggles

IN this paper the authors aim to chronicle the experience and salient points brought out in changing flotation reagents at a concentrator which had probably been using a mininium amount of oil at a minimum cost per ton, to a more complicated system requiring a partial chemical control. The original oils were coal tar and pine oil. The new reagents are lime, xanthate and pine oil. It was found that there were no insurmountable difficulties and eventually the cost of the new reagents per ton of ore proved to be very little more than that of the old. LIME PLANT When the question of handling lime came up there were two propositions open: (1) to handle the lime dry; (2) to handle it wet in the form of an emulsion. Granting that a dry lime feeder would function properly, delivering lime uniformly, the chief objection was the dust that would be raised when these feeders were being charged or operated, as the only possible location was on a gallery beneath which men were working. With this objection the handling of lime as an emulsion seemed to be the better scheme. The lime plant which was first installed was for experimental work on one section. This was gradually changed and developed until it was of sufficient size to accommodate 20 sections. The various changes will not be discussed and the following description deals only with the fully developed plant. Crude as it is, and perhaps somewhat expensive to operate, the lime-handling plant has been quite successful. Much has been learned which will pave the way for a better installation in the future. Burnt lime is received loose in standard gage box cars. This is the product of the kilns and has had no screening or sorting. A grab sample is taken from each car as it is unloaded. An average of the analyses of samples from 44 cars gave the following: [ ]

Jan 1, 1928

By Hertha R. Freche

The diffusion of magnesium and silicon from the core into the high-purity coating of Alclad sheet is important commercially, and led to the use of a duplex product for the study of diffusion by means of spectro-graphic analysis of successive layers. It has been found that in the duplex materials the diffusion of magncsium from an undersaturated aluminum-magnesium alloy into its high-purity aluminum coating is approximately of the same order of magnitude as the diffusion of silicon from a saturated aluminum-silicon alloy into its high-purity aluminum coating. However, if magnesium and silicon are both present in the alloy in the ratio of Mg2Si, they appear to diffuse in the approximate ratio of this compound. Finally, if the alloy contains silicon in excess of the amount required by magnesium silicide, the amount of diffused silicon in the high-purity aluminum coating will also be in excess. The interdiffusion of metals in the solid state is of both scientific and technical interest, because it is helpful in the study of the alloy structure and in the solution of problems pertaining to the strength and surface condition of the fabricated product. W. C. Roberts-Austenlt carried out the first quantitative determination of the coefficient of diffusion of gold into lead. This classical experiment was followed by a series of investigations on the diffusion of metals and nonmetals in iron and steel and in nonferrous metals and alloys. Recently the diffusion of copper in coated strong aluminum alloys was investigated by A. Burkhardt2. This appeared to be the first published investigation on the diffusion of metals into aluminum. The present investigation was the direct result of a technical question in connection with alloy fabrication and is a summary of some preliminary work pertaining to the diffusion of magnesium and silicon into aluminum. The results necessarily will be subject to some variations, since this is the first attempt to evaluate the coefficients of diffusion of magnesium and silicon into aluminum according to this method of procedure. This

Jan 1, 1936

By Andrew Hyslop

In our never ending search for new and better ways of underground mining, we find that transportation has had its share of new ideas in the past few years. The old and still effective method of track haulage has had some competition from rubber-tired cars and belt conveyors, each of which has its own safety hazards which demand close scrutiny in any safety study. The use of shuttle cars, in particular, has introduced clearance hazards caused by the absence of the more or less positive guides formed by the rails of a track sys- tem; likewise the requirement of greater clearance tends to increase roof hazards which we all know to be great enough with the best of methods. However, the subject of transportation hazards is too broad to be covered entirely in one paper, so I will confine myself to track methods which carry the preponderance of underground tonnage. I am quite sure that to this group it is an evident fact that haulage accidents are of major importance. However, to stress the point, it may be well to look at a few figures. Safety statistics can be quite boring and often are subject to question as to mathematical accuracy because of different

Jan 1, 1949