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By R. E. H. Pomeroy

EARLY in 1917, it became evident, owing to existing and pending market conditions, that a substitute for crude petroleum must be found for firing the smelter furnaces. After a review of the plants then existing, it was deemed advisable to depart from their practice and to adopt the following described system of distributing pulverized coal to the furnaces. The principal advantages of the proposed system, which influenced this decision, were: (1) Equal safety; no pulverized coal is stored at the furnaces; (2) greater ease of operation, furnace fires being controlled by regulating valves in burner branches, as in gas firing; (3) better organization; all machinery, including pulverized coal feed, is under one roof, and the organization is separate from the furnace department; (4) greater cleanliness; all machinery is under vacuum; (5) greater flexibility of application; the coal and air mixture can be piped where needed. The design of the plant is the result of the combined efforts of the local engineering staff and of the machinery manufacturers. Many new features were embodied in this design to insure greater safety, cleanliness, and efficiency of handling. After 14 months of continuous operation, the plant has proved entirely satisfactory. The building is of structural steel, covered with corrugated steel, with many windows and is painted light gray inside and out. The building floor is of concrete with ample drains to the sewer, and the building is equipped with fire and service water piping. Fig. 1 shows the east side of the building and the incline conveyor from the raw-coal bins.

Jan 2, 1920

By L. W. McKeehan, W. C. Elmore

The magnetic powder method, long used for roughly mapping magnetic fields, has recently been refined1, "or investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter2 first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators:' have used Bitter's original technique, with slight modifications, to study the variation of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement ill the powder technique which led us to the discovery of a new effect throwing considerable light on the magnetic secondary structure of alpha iron4 and of nickel5 single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure. Specimens The following list describes the specimens used in the present investigation. Designation Description A1 Silicon ferrite furnished to us by Dr. W. E. Ruder, of the General Electric Co., for which lie gave the following typical analysis: C, 0.05; P, 0.038; S, 0.026; Mn, 0.15; Si, 3.24. Disk, 0.60 cm. diameter, about 0.05 cm. thick. By X-ray analysis angles between disk normal and [100] 75o, [0101 76" [00l] 21o. A2 Same as A1 except: diameter 0.75 cm. A, Same as A1 except: diameter 0.68 cm.

Jan 1, 1936

By L. W. McKeehan, W. C. Elmore

The magnetic powder method, long used for roughly mapping magnetic fields, has recently been refined1, "or investigating the microscopic variations in the surface magnetization of ferromagnetic crystals. Bitter2 first discovered regular powder patterns connected with the crystal structure of such specimens. Several other investigators:' have used Bitter's original technique, with slight modifications, to study the variation of the patterns with variations in the magnetizing field applied parallel to the surface, and their dependence upon the state of strain, of polish and of crystal cut. All of the explanations of these patterns on metallic ferromagnetics have been couched in general terms. In a preliminary report we have described an improvement ill the powder technique which led us to the discovery of a new effect throwing considerable light on the magnetic secondary structure of alpha iron4 and of nickel5 single crystals. We now report additional evidence confirming the existence and stability of a magnetic block secondary structure. Specimens The following list describes the specimens used in the present investigation. Designation Description A1 Silicon ferrite furnished to us by Dr. W. E. Ruder, of the General Electric Co., for which lie gave the following typical analysis: C, 0.05; P, 0.038; S, 0.026; Mn, 0.15; Si, 3.24. Disk, 0.60 cm. diameter, about 0.05 cm. thick. By X-ray analysis angles between disk normal and [100] 75o, [0101 76" [00l] 21o. A2 Same as A1 except: diameter 0.75 cm. A, Same as A1 except: diameter 0.68 cm.

Jan 1, 1936

By W. S. N. Waring, E. C. Bain, E. S. Davenport

The more familiar compositions of both the iron-carbon-chromium' and the iron-carbon-tungsten2 systems have been investigated with a degree of thoroughness which has permitted the construction of their three-dimensional equilibrium diagrams; and it is probable that these equilibrium diagrams are sufficiently accurate for the present metallo-graphic needs. Strangely enough, in spite of their importance, the alloys of iron, carbon and manganese apparently have not been investigated in the same systematic manner, and so far as is known, no three-component equilibrium diagram for this system is available. Even iron-carbon-nickel alloys3 have been studied rather more thoroughly; for these the solidus and liquidus surfaces have already been determined, but the solid transformations in this, as in the manganese system, have not been reported systematically. The present paper deals with the constitution at equilibrium of a series of 36 iron-carbon-manganese alloys of commercial purity limited by 1.5 per cent carbon and 15 per cent manganese, a range of compositions including most of the manganese steels. The temperature range of melting has not been determined, nor has the high-temperature (delta iron) ferrite equilibrium been included in the study, it being considered that the more important characteristics of the manganese steels are their ordinary transformations in the solid state. The delta iron region is almost certain to be a small tetrahedron not very different in magnitude or contour from that in the iron-carbon-nickel diagram. It is probably true

Jan 1, 1932

By M. L. Samuels

In a recent paper the authors1 discussed the reactions to tempering of hypereutectoid steels quenched from 1000' C., as revealed by studies on changes in hardness, electrical resistivity, coercive force and metallo-graphic charaeteristics. The data, which related specifically to tempering temperatures of 550°, 650" and 710" C., for varying periods up to 125 hr., permitted the following important conclusions: 1. The rate of softening of the steels at the temperatures examined differed markedly although the steels were of "similar" general chemical composition. 2. The temperature of maximum softening spread over a range from about 650" C, to the eutectoid inversion. 3. The divergence in behavior was ascribed, at least in part, to a profound difference in tendency to graphitization on annealing at sub-eutectoid temperatures. 4. The mode of spheroidization of the cementite, as revealed by metallographic studies, also varied considerably in the different steels. The purpose of the present investigation is to pursue further the study of the difference in behavior of the steels on tempering over a wider range of temperature. To this end the following features have received particular attention: 1. Comparison of temperatures of maximum softening of the various steels when the quenched samples were tempered for 5 hi. and for 75 hr. followed by furnace cooling and by quenching in water. 2. Deterrnirlation of the effect of quenching temperature, prior to tempering, on the rate of softening. Quenching temperatures of 1000" and 850" C. were used in the investigations. 3. Examination of the microstructures obtained with the various heat-treatments employed.

Jan 1, 1938

By M. L. Samuels

In a recent paper the authors1 discussed the reactions to tempering of hypereutectoid steels quenched from 1000' C., as revealed by studies on changes in hardness, electrical resistivity, coercive force and metallo-graphic charaeteristics. The data, which related specifically to tempering temperatures of 550°, 650" and 710" C., for varying periods up to 125 hr., permitted the following important conclusions: 1. The rate of softening of the steels at the temperatures examined differed markedly although the steels were of "similar" general chemical composition. 2. The temperature of maximum softening spread over a range from about 650" C, to the eutectoid inversion. 3. The divergence in behavior was ascribed, at least in part, to a profound difference in tendency to graphitization on annealing at sub-eutectoid temperatures. 4. The mode of spheroidization of the cementite, as revealed by metallographic studies, also varied considerably in the different steels. The purpose of the present investigation is to pursue further the study of the difference in behavior of the steels on tempering over a wider range of temperature. To this end the following features have received particular attention: 1. Comparison of temperatures of maximum softening of the various steels when the quenched samples were tempered for 5 hi. and for 75 hr. followed by furnace cooling and by quenching in water. 2. Deterrnirlation of the effect of quenching temperature, prior to tempering, on the rate of softening. Quenching temperatures of 1000" and 850" C. were used in the investigations. 3. Examination of the microstructures obtained with the various heat-treatments employed.

Jan 1, 1938

By Frank Harwood Riddle

Products made from the ores of the sillimanite group, and synthetic substitutes for them, have unique properties, and service tests prove that they are playing, and will continue to play, a major part in improvements in metallurgical processes. Also, they are examples of how comparatively useless, rare, or "museum" minerals have been made available in commercial quantities. Until research developed uses for them, the minerals had been observed only in small, scattered masses, or crystals. Improvements in ceramic processes and compositions have come about very gradually. In the last 10 or 15 years, several outstanding developments have been made. Of greatest interest to the mining and metallurgical engineers are those affecting the composition, necessitating the mining of new minerals, and improvements in ceramic products used in metallurgical processes. Sillimanite and Mullite Sillimanite (Al2O3.SiO2), then known as Fibrolite, according to Dana,' was first reported in 1792. In 1796, cyanite (Al2O3.SiO2) was first described.2 In 1873, Behrens published results of his microscopic study8 of porcelain. He showed that it contained what appeared to be crystals, which dissolved less readily than quartz and glass in hydrofluoric acid. Hussak4 described the presence of needlelike crystals as occurring in some instances in small amounts in certain porcelains. In 1908, Plenske and Zoellner both studied porcelain structure.5 Plenske observed that "sillimanite" might be present in masses of exceedingly minute grains which apparently were amorphous. Zoellner advanced the theory that the needlelike crystals were formed by a molecular change in the clay,

Jan 1, 1932

By V. Jares

DESPITE the fact that a combination of metals-aluminum-zinc-tin, and sometimes aluminum-zinc-cadmium-is extensively used for aluminum solders, as well as for die-castings, the constitution of these alloys has not yet been made clear. I. BINARY SYSTEMS The system aluminum-zinc is the basis of the ternary alloys under consideration. Their composition was made sufficiently clear by the investigations of Rosenhain and Archbutt,1 Bauer and Vogel,2 Sander and Meissner,3 Hanson and Gayler4 and Isihara.5 Only the temperature of decomposition of the crystals 0 seems still to be doubtful, whether it is considered as a compound of Al2Zn3 (according to Bauer and Vogel) or as an intermediate phase of variant composition (according to Hanson and Gayler). This temperature is given by most of the authors as in the neighborhood of 256° C., only Isihara giving 280° C. As its accurate determination is of special importance in the study of the ternary alloys under consideration it was experimentally controlled in the following manner: An alloy corresponding in composition to the formula Al2Zn3 was made, in which the temperature effect was found to be the greatest. This was drilled and a silver-constantan thermoelement inserted into the cavity so as to be in direct contact with the alloy. The whole was then very slowly heated and the heating and cooling curves determined. The transition temperature from the heating curve was found to be 281° C., whereas from the cooling curve it was 252° C.

Jan 1, 1927

By Joseph Chalmers, E. L. Rawlins, D. B. Taliaferro

PRoblems dealing with the movement or migration of fluids through porous beds have been the subject of much research. The subject is not peculiar to the production of oil and gas, as many investigators have studied the nature of this movement and its relationship to the problems of other industries. Darcyl conducted a series of experiments relating to the percolation of water through filter beds. King2 carried on an extensive series of laboratory experiments with the object of formulating some conception of the rate of movement of water through soils and sand strata in the drainage of surface water into underground channels and subsequent recovery of this water through wells drilled into the source beds for irrigation purposes. Slichter3 undertook a study of the same problem from a mathematical standpoint, and more recently Furnas4 has investigated the flow of gases through beds of broken solids with particular reference to blast-furnace operation. With specific reference to gas production, Muskat and Botset5 of the Gulf Research Laboratory undertook an experimental study to establish quantitatively the characteristics of and laws governing the flow of gases through consolidated and unconsolidated porous materials of fine texture with a view of predicting the performance of gas in an underground reservoir. There seems to be a general agreement that many of the relationships between the numerousfactors influencing the flow of fluids through porous materials are far too complicated to be attacked by analytical methods based upon a knowledge of hydrodynamics. For gases, the laws of

Jan 1, 1932

By Willard L. Cumings, Benjamin L. Miller

The Camaguey brown iron-ore deposit covers the top of Sari Felipe hill, the nearest point of which lies 14 miles NW. of the city of Camaguey. While there are several low flat-topped hills in the vicinity covered with a more or less continuous mantle of brown iron-ore, the deposit of San Felipe hill is the only one of any size and importance, and the name " San Belipe district" is proposed for the region. The deposit extends in a NW-SE. direction for a distance of about 10 miles, with an average width of 5 miles. The location is shown in Fig. 1, a sketch-map of the eastern part of Cuba. Fig. 2 is a map of the San Felipe district. 2. Description. The district is mentioned by Spencer,' who says: " The Cubitas iron-ore fields are situated from 12 to 15 miles north of Camagueg City, in the province of Camagueg.....Within an area measuring roughly 10 miles east and west and 4 miles north and south, there are several flat-topped mesas rising 300 to 400 ft. above the level of an almost featureless plain which extends for many miles in all directions except toward the north." With the exception of the discrepancy in his statements .as to the distance from Camaguey and the area of the hill, which is over 50 sq. miles, his description is a very good one. Kemp2 has the following to say of ores in Camaguey Province:

Jan 1, 1912

By T. F. Archbold, P. G. McCormick

Silica fiber 11arkevs and hardness irzdentatiozs have been used to study the thermal diffusion of racancies in zinc placed in temperature gradients of 460o and 706oK per Cm All markers mored toward the higher temperatures, and the data show that the heat of trarlsport Q is greater than the eizthalpy of z,acancj3 forrjalion E by an amount equal to 3.5 kcal per mole. These results ore not in agreement with those obtained in either of the two previous studies with zinc. The problem is discussed in terms of experimental differences and racancy source and sink efficiencies. THE general interest in thermal-diffusion phenomena over the past several years has prompted a number of marker movement studies using pure metals. In order to understand better the relationships between thermal and mass flow, a general goal of the experiments has been to obtain values for the net enthalpies carried by the diffusing atoms. For self-diffusion by means of the vacancy mechanism, the determination of relative marker positions before and after an anneal in a temperature gradient permits a calculation of a value for (Q - Ef). Q is the transferred enthalpy, and Ef is the enthalpy of vacancy formation in the metal being investigated. The initial experimental study of thermal diffusion in pure metals was accomplished by Shewmon who found essentially no movement of surface-hardness indentation markers in single and bicrystals of zinc held for 20 days in a temperature gradient of 310°C per

Jan 1, 1967

By E. T. Dumble

In the Bosquejo Geoldgico de Mexico, published in 1897 by the Secretaria de Fomento as Nos. 4, 5 and 6 of the Boletin del Institute Geologico de Mexico, the Director, Jose C. Aguilera, after a detailed account of the geological observations made by himself and his assistants on their several trips through the various districts of the Republic, gives in Part 2 a synopsis of the geology of Mexico, describing . al1 the formations recognized, the rocks comprised in them, their geographical distribution, disturbances, principal eruptions and economic features, as explanatory of the Geological Map of Mexico. In Part 3 Prof. Ordonez describes many of the interesting eruptive rocks of Mexico." This work brings together in a very satisfactory way about all of the published results of geological investigations in Mexico; and although the determinations of the authors with reference to some of the sedimentary deposits are very different from those of other writers, they seem to be based upon good paleontological grounds in each instance. From the map and the text of this paper it appears that the condition of knowledge in regard to the geology of the State of Sonora, at the time of its publication, was about as follows: The western portion of the State, lying between the coast line of the Gulf of California and the foot-hills of the Sierra Madre mountains, is largely Quaternary, interrupted by areas of Azoic rocks and of later eruptives, with two or three limited exposures of limestones of the Cretaceous; while the eastern or

Jan 1, 1900

By H. S. Bell

IT SEEMS unnecessary to dwell upon the advantages of the modern pipe still as compared with the older type of distillation equipment used by oil refiners. The relatively low installation cost, coupled with remarkable operating efficiencies of pipe stills, precludes the consideration of other types except in rare instances where some peculiarity of product or plant may have an influence. The question of the actual heat required to distil petroleum is quite involved. We have extensive data on the latent heats of the various hydrocarbons under different conditions of pressure. We also have information regarding the specific heats of various oils and the effect of temperature thereon. Because of the complexity of petroleum and of each fraction, it seems impossible to theoretically analyze the partial-pressure effect of the great number of hydrocarbons upon one another during distillation. If a distillation curve and percentage analysis of any crude or product are available, it is possible to construct a curve with ordinates representing per cent. distilled and B. t. u. per pound or per gallon, or other desired unit. To do so the crude is split into fractions, of 5 or 10 per cent. The boiling point and gravity of each fraction being determined, it is possible to evaluate the heat required. As each fraction is removed, the residue must be raised to a higher temperature and latent heat supplied for the successive fraction. As the calculations progress, the latent heats decrease while the specific heats increase. Such a curve is illustrated by Fig. 1 for a typical 39.9 B° North Texas crude.

Jan 1, 1928

By J. F. Kemp

PAGE I. Introduction,.......269 11. Topogmphical Features,.....270 III. Geological Relations of the Mineralized Area,.272 1. Structural Features,.....272 2. Occurrence of the Copper,....274 3. Granite-Contacts,.......274 IV. Descriptions of the Rocks,.....274 1. Granite,........274 2. Limestone,.......276 3. Porphyritic Eruptions,.....278 (a) Quartz-Porphyry,.....278 (b) Trachyte-Porphyry,.....280 V. Contact Phenomena,......285 1. Comparative Immunity of the Limestone, . 285 2. Contact Phenomena in the Quartz-Porphyry,.... 285 3. The Form and Distribution of the Ore-Bodies,290 VI. Method of Deposition,......293 I. Introduction. The White Knob copper-deposits are situated about three miles south of Mackay, on the Salmon River branch of the Oregon Short Line Railroad, in Custer county, Idaho. An outline-map of this district is given in Fig. 1. The deposits have been known and spasmodically worked for many years, and a total of over 3.5 miles of tunnels, shafts and other workings has been driven with a view to their development. These extensive excavations have exposed the deposits sufficiently to permit a careful geological examination. The peculiar features which give special interest to this paper are the branching, tree-like form of the ore-bodies; the absence of zones of secondary enrichment in the partly oxidized pyritic deposits, and the fact that while the deposits are associated in a general way with the contact of an eruptive rock with limeetone, which it penetrates, the garnetization has taken place not in the limestone, as is the usual case, but in the igneous

Jan 1, 1908

By D. T. Peters, C. R. Cupp

Aging of commercial 18 pct Ni maraging steel and of related binary, ternary, and quaternary alloys has been studied by electrical resistivity, X-ray diffrac-tion, and hardness measurements. The aging process is in three stages: 1) recovery of martensite; 2) two precipitation reactions; 3) formation of nickel- rich austenite. The main objective of this work was to discover the nature of the Co-Mu interaction. Addition of cobalt to the Fe-18 pct Ni-5pct Mo alloy results in acceleration of the pvecipitation reaction by increasing the super-sat~lration 0f molybdenum. The cobalt-containing al- loys show no incubation period for the precipitation reaction, but the alloy without cobalt shows an initial slow reaction. These results are interpreted in terms of precipitation on dislocations. At low aging temperatures, the presence of cobalt leads to the appearance of a second type of precipitate which is a particularly effective hardener. Cobalt was found to retard the formation of austenite. Overaging is a combination of classical overaging and the formation of austenite in the structure. he- activation energy for the precipitation reaction determined from resistivity ,measurements is 42.8 kcal per mole and the growth of the precipitate is found to obey at law at high tenzperatures and a tU3 law at low temperatures. HE mechanism of strengthening of the 18 pct Ni maraging steels has been studied extensively since 1962.'-? The strengthening is due to precipitation hardening of the martensitic matrix. The main precipitate is an inter metallic compound involving molybdenum, but there is disagreement about its identity.

Jan 1, 1967

By William Campbell

In the olden days the making of alloys was an art, and the secrete of the craft were jealously guarded. To-day it has become a science, though the old ideas in regard to the secrets and formulæ are dying hard. Modern progress may be attributed to scientific research and testing of materials, and the substitution of chemical analytical control for " cook-book " methods. We know to-day a great deal about the constitution of alloys, the reasons of the change in structure and physical properties by heat and mechanical treatment; and this new knowledge is due for the most part to the physical chemist and metallographist, who have shown us that alloys are simply solutions, and as such obey definite laws. The application of the theories of solutions and of the phase rule tells us what ought to happen when our alloys are in a state of equilibrium. The working-out of the temperature-composition diagram (thermal diagram) for numerous alloys has thrown a light on the structure and constitution which has dispelled most of the darkness in which we labored before the advent of metallography. The work began with the determination of the freezing-point curves, and here the research of Le Chatelier,' Gautier,2 Roberts-Austen,3 and the other pioneers broke the ground. Next the physical chemists, Tammann,4 Rooseboom,5 Bancroft,6 and their colleagues, showed us the complete thermal diagram and its meaning. Then the researches of Heycock and Neville7 on the Cu-Sn series and of Shepherd 8 on the

Jan 1, 1913

By S. R. Gilbert, B. W. Burdett, L. B. Hales

INTRODUCTION Grinding control is currently the most publicized control subject in the minerals industry. Flotation control and crushing control have not as yet received the widespread attention that grinding control has. The primary reasons for this center around the high capital costs of grinding equipment and the fact that grinding mills are extremely energy inefficient. In a typical copper concentrator the energy requirements to produce refined copper are: (1) [Total Energy Distribution (Kw-hr/yr)% Mining4.93 x 10817.3 Mineral Processing9.63 x 10833.8 Smelting and Refining13.9 x 10848.9] One-third of the total energy used for copper production is for mineral processing. A breakdown of this energy into process steps yields the following: [Total Energy Distribution (Kw-hr/yr)% Crushing and Grinding 7.16 x 108 73.8 Flotation 0.76 x 108 7.8 Materials Handling1.78 x 10818.4] It is apparent that comminution operations consume the largest proportion of the energy for processing and as such become major targets for improvements in efficiency. Unfortunately, size reduction operations are extremely inefficient. Efficiency calculations for grinding range from less than 0.1% to about 5% depending on the evaluation criteria. Because of these facts, grinding control has been and will continue to be the focus of major process control efforts. OBJECTIVES AND BENEFITS All benefits achieved as the result of grinding control are derived from modifying physical parameters which improve the efficiency of the grinding mill. These parameters include:

Jan 1, 1982

By Edward H. Robie

THOUGH the final figures are not available as this is written, it seems certain that the Institute accounts will show $7000 to $8000 surplus for the year 1951. This is the first time this has happened since 1941. No money had to be taken from any of the Funds to bring about this happy condition. Furthermore, the amounts allowed for depreciation, bad debts, and inventory adjustment were more liberal than in the past. Income increased some $29,000 over 1950. Dues received from old members increased moderately, but dues from new members dropped off $2000 and from initiation fees quite severely-from $17,000 to $11,000. The number of new members did not come up to expectations and a change in procedure caused a delay in getting some of them on the rolls. A large number of the new members paid an installment of $5 on their initiation instead of the full $20. Junior Members, of course, pay no initiation fee. Brightest spot in the income picture was the increase in advertising income-from $103,000 in 1950 to $143,000 in 1951. All three of the journals shared in this, Mining being up $18,000; Metals, $9000; and Petroleum $13,000. Nonmember sales of the journals dropped off slightly, and sales of Transactions volumes more so from $35,000 in 1950 to $27,000 in 1951, with a further drop of $5000 accounted for by a change in accounting procedure. On the other hand, sales of other publications increased by $10,000.

Jan 1, 1952

By MARIUS R. CIMPBELL, Edward W. Parker

DESCRIPTION. ACCORDING to the estimates prepared by the U. S. Geological Survey, the area underlain by workable coal-beds in the United States is 496,776 sq. miles. Of this total area, 480 sq. miles contain the entire anthracite coal-fields of Pennsylvania. The bituminous coal-fields are estimated to be contained in areas aggregating 250,051 sq. miles. The grade of coal between bituminous and lignite, and which is designated by the Geological Survey as " sub-bituminous," is estimated to be contained within areas aggregating 97,636 sq. miles, while the areas containing lignite aggregate 148,609 sq. miles. The coal-fields are divided, for the sake of convenience in classification, into six main provinces, as follows: 1. The Eastern. Province, containing the anthracite coal-fields of Pennsylvania and the bituminous coal-fields of the Appalachian region-namely, those of western Pennsylvania, Ohio, Virginia, West Virginia, Kentucky, Tennessee, Georgia, Alabama, and small outlying areas in North Carolina. 2. The Interior .Province, containing the bituminous coal-producing regions of Michigan, Illinois, Indiana, western Kentucky, Iowa, Kansas, Missouri, Oklahoma, Arkansas, and Texas. 3. The Gulf Province, containing the lignite-areas of Alabama, Mississippi, Louisiana, Arkansas, and Texas. 4. The Northern or Great Plains Province, containing the lignite and sub-bituminous areas of North and South Dakota, eastern Montana, and northeastern Wyoming. 5. The Rocky Mountain Province, containing the bituminous and sub-bituminous areas of western Montana and western Wyoming, Colorado, Utah, and New Mexico. 6. The Pacific Coast Province, containing-the areas of Washington, Oregon, and California.

Apr 1, 1909

By D. O. Noel, E. B. Gebert, J. D. Shaw

IT. is, of course, expected that manufacture of the various metal powders should involve numerous methods adapted to the specific characteristics of the metals themselves. Several methods for powdering a particular metal may be available, but the physical characteristics of the powder as produced by the several methods may be quite different. In the final analysis, the application of the metal powder dictates the physical properties that the metal powder must possess, and this, to a very large extent, will determine which of several possible methods of. manufacture is adopted. Sometimes powder of the same metal is produced by more than one method, each powder having specific characteristics .that make it particularly suitable for its application. For purposes of classification, the various methods of powdering metals can be grouped as follows: 1. Machining. 2. Milling (by ball mills, stamps, attrition mills, etc.). 3. Shotting (pouring molten metal into water, air, etc.). 4. Granulation (by stirring molten metal while solidifying). 5. Atomizing (disintegrating by steam, compressed air, etc.). 6. Condensation of metal vapor. 7. Reduction of oxide powders. 8. Chemical precipitation. 9. Electrolytic deposition. 10. Sintering (for producing alloy powders). 11. Formation of an alloy followed by dissolving or otherwise removing one of the alloying constituents. MACHINING Turnings, cuttings, filings, etc., are, of course, produced as by-products in machine work of various kinds, and find certain applications as metal powders. For example, iron powder so produced is used extensively as a reducing or precipitating agent and as a constituent in certain hard-finish cements.

Jan 1, 1938