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By Yap Chu-Phay

IN 1923, when the writer began his studies in metallurgy, he came upon an article by Professor Honda on the, Equilibrium Diagram of the Iron-carbon System, 1 which made a profound impression on him. What interested him most was this sentence: "In the recent diagram of the iron-carbon system, the solidus is usually shown as a curve bending considerably downward. But it can be shown by thermodynamics that if the liquidus is straight or slightly curved, the same must also be true for the solidus. Hence, in my constitutional diagram, the lower portion of the solidus is slightly bent upward." Ever since then the writer has been interested in thermodynamics, especially chemical thermodynamics. The applications of thermo-dynamics to the metallic systems have been, in the writer's opinion, sadly neglected, although we continually use the phase rule in our study of equilibria in the liquid and solid states of metallic alloys. Many investigators, among whom may be mentioned Heycock and Neville, and s Honda and his coworkers, have applied the simple Raoult-van't Hoff law of depression of freezing point, mainly to determine the heat of fusion, but no attempt has been made to investigate the applicability of the thermo-dynamic laws of solution (as opposed to the laws of solution derived from other sources) to metallic systems" showing either limited or complete solid solutions. Perhaps the reason for this neglect is that until recently there have been so few reliable data on the solidus, which is much more difficult to determine than the liquidus. The writer has under way at the present time an investigation of a number of systems, the solidi of which have been more or less reliably determined. Recently, the writer has not only shown the valid applicability of the thermodynamic laws of solution as applied to the system antimony-bismuth but has also suggested a method of attacking problems involving complete and incomplete equilibria.2 In the present paper, the same method of approach is employed. For convenience, we shall divide this paper into two parts:

Jan 1, 1931

By H. H. Kellogg

An invitation to address you on the occasion of the one-hundredth anniversary of AIME represents an honor, a challenge and an opportunity: an honor that you judge me worthy; a challenge that I present to you a picture of extractive metallurgy in the years ahead that contains some ideas of value; and finally, an opportunity for me to express some deeply felt beliefs about our profession and our industry. My topic concerns the technology of metal production in the future - the processes, new and old, that will be used to extract metals. The nature of these processes will be shaped by many forces - some technical, some economic, some political or social. A forecast of future technology must recognize the role of each of these forces, and I have endeavored to do this in the analysis that follows. In brief, my outline consists of an analysis of the forces (perhaps better called "problems") that will influence the future of our industry, followed by consideration of likely lines of technological development to meet them. Let me dwell for a moment on the nature of this industry and the profession that serves it. I have been engaged in the profession of extractive metallurgy - teaching, researching and consulting - for 30 years. I have always found the subject stimulating and rife with challenges of a scientific, engineering, economic and socio-political nature. It is a big subject - it encompasses most of the elements of periodic table; we measure the U. S. production of six metals in millions of tons per year; new plant costs range to $100 million and more. The supply of metals from our extractive plants plays an essential role in our modern industrial economy. We could do without DDT, or phosphate detergents or 300-page Sunday newspapers; we cannot do without a huge and increasing supply of metals. The Basic Goal of Extractive Metallurgy Understanding of some basic forces that shape this industry can be gained by consideration of the question: What determines the utility of metals to man? We think immediately of the inherent properties of metals - strength, ductility, electrical conductivity and so forth - but these tell only part of the story. Metal price and the available supply play equally

Jan 1, 1971

By S. L. Hoyt

The writer has long been interested in seeking an explanation of the upper heat effect in the copper-tin alloys over the a + b range, first described in 1913. These notes are offered, not at all as the final explanation 'of this heat effect, but rather to indicate certain progress which has been made toward establishing what happens over this temperature interval. While working on the thermal analysis of the copper-rich kalchoids (copper-tin-zinc alloys), it was noted that those alloys containing major portions of tin and minor portions of zinc exhibited two marked heat effects, one at about 520' C. and the other at about 600" C., instead of the single effect which is generally observed in either of the two binary series. This matter was discussed with Dr. Guertler, who suggested that a heat effect at about 600" C. in the pure copper-tin alloys might be expected. This led to a more searching examination of the thermal critical points in the pure copper-tin alloys, with the result that a marked, although somewhat weak, heat effect was located at about 600. Somewhat later, this upper heat effect was discussed with Dr. Burgess, and it was requested that the Bureau of Standards make heating and cooling curves of one of these alloys for the purpose of removing any possible doubt as to the actual presence of the heat effect. Results obtained by the Bureau are given in Plate I. In an earlier paper1 differential curves were published showing that the heat effect occurred at constant temperature over the a + B range and increased in magnitude with the amount of B up to a point somewhat above 20 per cent. tin. No heat effect was noticed at this temperature in the eutectoid alloy. The existence of this heat effect seems to require a modification of the present copper-tin diagram in the a + B field, and it has been the object of the work here presented to secure the evidence upon which such a change should be based.

Jan 1, 1919

By John M. Crowl, L. E. Sawyer

5.3-1. General Public Resistance to Strip Mining. Surface (strip) mining is the oldest recorded method of extracting coal and other minerals from the earth. This method of mining completely alters the topography of the earth's surface, leaving an area of more or less parallel ridges or of peaked mounds of the materials which overlay the mineral seam. It destroys all original vegetation and provides materials for new type soil. During the early years the acreage mined by this method was small, land was plentiful, and with a growing young nation no thought was given to the restoration of the disturbed areas to some form of productive use. Early in the present century the development of steam shovels and drag-lines made it possible to remove thicker overburden to recover the products. With the deeper digging, the size of the disturbed areas increased. With this increase in the size of equipment and the improvement of blasting techniques, mining was expanded into more prominent locations and to areas of more valuable land. The more progressive operators became aware of the need to reclaim those areas for some productive use. Electric shovels with capacities of up to 200 cu yd and draglines with capacities of 145 cu yd, capable of uncovering products over 100 ft below the surface, are now in use. Combined with the increase in the size of equipment, the expansion of contour mining or rim stripping in the mountainous areas has focused public attention on the need for a sound reclamation program for all disturbed areas. APPEARANCE. After mining, the areas consist of varying percentages of rock, shale, slate, and soil material devoid of all plant and animal life. Unless a definite reclamation plan is carried out, many of the mined areas will remain bare for a period of years. The topography of the area is completely altered. What may have been level to rolling land in cultivation, in grass, or in timber is thrown up into a series of ridges or mounds.

Jan 1, 1968

By Gifford White

CONSIDERABLE attention has been directed in recent years to methods of electric prospecting other than the conventional direct-current tech-niques. It has been extensively recognized that electrical data of a more general nature than that possible by direct-current methods might be useful in geophysical studies. To this end, a number of different types of electric currents have been employed, such as single-frequency alter-nating currents, square-topped periodic current waves,4 periodic surges of a less specific nature,8 and suddenly applied direct current.1,2 Yet, to the author's knowledge, little analysis of these different types of driving currents has been made from the standpoint of network theory to determine just what type of currents would give the most useful data, and, most important of all, to determine the relation of the data taken by one method to those of another. Without touching on the actual theoretical problem of how currents flow in the earth under specified boundary conditions, some very useful information can be obtained from the study of the fundamental integral equations of electrical networks, throwing light on the problem not ordinarily appreciated by the field worker. Some manipulation of the standard network equations will be made, with the sole purpose in mind of developing expressions leading to practical results. Suppose that four points in the earth have been located and it is wished to obtain the most useful type of electrical data by inserting current into two of them and measuring the potential developed between the other two. The first problem that arises is that of which pair of the four shall be chosen as current grounds. In the direct-current case, where only steady potentials are measured, the selection is of little consequence, but as soon as currents varying with time are used at the current grounds, a new effect arises. The fact that a varying current is flowing in the current-carrying conductor between the current grounds means that magnetic and electric fields varying with time will be produced

Jan 1, 1940

By Charles H. Fettke

The Bradford field of northwestern Pennsylvania and adjacent portions of New York state has attracted world-wide attention in recent years on account of the remarkable success that has been attained in the application of water-flooding as a means of increasing the extraction of oil from a pool that had almost reached the economic limit by ordinary production methods. It is one of the few large oil fields in which artificially conducted water drives have thus far proved successful, although many attempts have been made to apply them elsewhere. As detailed a knowledge as possible of the character of the producing sand in this field is therefore of considerable interest, not only from a scientific but also from a practical standpoint. Outside the Bradford field, such knowledge should aid operators in determining whether or not their sands are amenable to flooding. In the Bradford field itself flooding operations are not uniformly successful over the approximately 85,000 acres of productive area, due in many instances primarily to variations in sand conditions. A knowledge of just what these variations are would often be a great aid in overcoming the difficulties, or else would save considerable sums of money which might otherwise be wasted in experimenting in areas where the chances of success are very small. Realizing that more precise information in regard to the nature of the reservoir rock was essential to improvements in the methods of oil recovery, the Northwestern Pennsylvania Oil Producers Assn., by private subscription of its members, took a core of the Bradford sand from a well 1/2 mile west of Custer City, Pa., during the spring of 1925. The Forest Oil Co. also took a core of the same sand from a well about 8 miles east of Bradford at that time. The cores were submitted to the United States Geological Survey for study and A. F. Melcherl has published the results of porosity determinations on the Custer City core.

Jan 1, 1929

By W. O. Borcherdt

THE 650-ton underground mill of The Empire Zinc Company of Colorado (a subsidiary of The New Jersey Zinc Co.) serves the Eagle mine at Gilman in the Battle Mountain mining district of Colorado, The topography is rough, the mine and mill being under Battle Mountain and the adit entrance in the north wall of the canyon of the Eagle River, which is here a steep gorge. The town of Gilman stands on a shoulder of the mountain at altitude 8975 ft., above sea level, along the Pike's Peak ocean to ocean highway and contains the company office and the usual facilities of a modern mining town. The railway contact is at Belden, altitude 8370 ft., at the bottom of the gorge directly below Gilman, where the westbound track of the Denver and Rio Grande Western Railroad is cut along the north bank and the eastbound track along the south bank of the river. A general description of the mine, mill and service facilities, with an account of the geology, character of the ore and methods of mining and milling having previously been published in a series of articles1, this paper will discuss with as little repetition as practicable the reasons for building the mill underground rather than as a conventional structure, the methods of construction employed and the experiences gained in what is apparently the pioneer plant of this type and extent. There is a large historical background for underground plant construction. From the dim past caves have been used for dwellings, stables, storage and shops. It was natural that where caves were available their many advantages led to their enlargement to suit convenience and where they were not available but the ground conditions, topography and drainage were favorable, to the construction of artificial caves. In the vicinity of Epernay, France, extensive underground chambers protect the manufacture and storage of champagne-an intricate and ingenious application of chemical engineering-and in recent years these plants have been mechanized by the installation of conveyor systems. In the

Jan 1, 1937

INTRODUCTION The geology of porphyry copper deposits in the southern Cordilleran orogen is the subject of this chapter. The area considered extends northwest from southern Mexico to the Columbia volcanic plateau, the Cascade volcanic province, and the Idaho batholith. Transversely it is a belt some 800 km (500 miles) in width bounded on the west by the Sierra Nevada range. Included within this area are many large segments considered unfavorable for hosting porphyry copper deposits, which are mentioned in the text. The region and its porphyry copper deposits have probably been more intensely studied and reported in the literature than any other area in the world. This summary considers regional geologic controls that governed formation of porphyry copper deposits within this province. Geologic factors that influenced the mineralogy and metallogeny of the deposits are also examined. Discussions with H. R. Cornwall have greatly helped in writing this section. GEOLOGIC SETTING The geologic setting has been summarized by Anderson (1966), Burchfiel and Davis (1972), Rogers, et al. (1974), and Lowell (1974). No porphyry copper deposits in this area are known to be pre-Triassic, so Mesozoic and Tertiary events will be stressed. Figs. 40 and 41 show basic data believed most pertinent to the topic of porphyry copper deposits. Pre-Middle Jurassic: Figs. 40 and 41 contain the principal structural and crustal ele¬ments found in the Cordilleran orogen after Anderson (1966), Schmitt (1966), Coney (1972), Rogers, et al. (1974), and Lowell (1974, 1976), together with location of some of the more important porphyry copper deposits. The western limit of the Precambrian craton is shown in Fig. 40 (Rogers, et al., 1974). East of that limit the crustal environment through which the porphyry copper plutons ascended includes the Precambrian basement as well as varying thicknesses of Paleozoic shelf and platform accumulations. The northwestern and western portion of the southern Cordilleran orogen west of the Rogers, et al. (1974) limit of Precambrian basement has what Churkin (1974) calls a thin continental crust. Brooks (1976) and Churkin (1974) describe oceanic volcanic

Jan 1, 1978

By Malcolm Scobie

"This paper reviews the evolution of Canadian surface and underground mining automation, principally relating to: advances in communications, initial development of machine teleoperation from line-of-sight remote control, and islands of automation. The eventual role of teleroboties and minewide robotic mining remains to be resolved. The progress and approaches adopted have tended to vary within each sector of the mining industry. Recent information technology advances have made possible the Digital Mine; in which information associated with all mining processes, however dispersed, would be integrated with support systems using new communications technology. The Digital Mine will provide the information infrastructure to serve as the foundation for minewide automation. This paper concludes by reviewing the issues likely to govern implementation success, relating to: mining process design, machine design, machine intelligence, and mine planning and control.IntroductionSignificant advances have recently been made in underground hardrock mine communications and teleoperation. Subsequent R&D efforts are mainly focussing on control systems for various types of machines. In underground potash mining, the realization of automated continuous mining systems appears to be imminent. Recent advances in surface mine dispatching, machine monitoring and global positioning systems (GPS) have tended to reactivate some of the initial R&D enthusiasm developed in the '70s for surface mine automation. Mines at large are approaching a major milestone: the implementation of comprehensive communications infrastructure which proves to be sufficiently reliable and economical to support the automation of routine mine production, either using teleoperated or autonomous machines. This then should motivate a deeper commitment to real time monitoring and management. The communications advances make possible the Digital Mine; in which information associated with all mining processes, however dispersed, would be integrated with support systems using information engineering. The Digital Mine will provide the information infrastructure to serve as the likely foundation for a wide range of automation scenarios. This paper surveys the status and directions of automation development in both surface and underground Canadian mines, pointing to what are seen to represent key technology development issues."

Jan 1, 1995

By E. F. Kingsbury

One of the well-known and important uses of the noble or precious metals has been for electrical contacts. In fact, the elements of this group, comprising gold, silver and the six platinum metals, have been called "noble" because of their ability to resist heat and corrosion, properties which were early found to be of importance in good contacts. Of these, platinum and its iridium alloys, palladium, and silver, have been extensively used. In recent years the electrical industry has been responsible for about one-eighth of the total consiimption of the platinum metals in the United States. Information is not available as to what part of this one-eighth has been used for contacts but it is certainly an important one. Substitutes for Platinum During the past 20 years a considerable number of contact alloys have been proposed in the patent literature largely with the aim of more or less replacing platinum by gold or silver, and some of these alloys are finding increasingly widespread application as the reliability of their performance becomes established. From even the partial data at hand it appears that this substitution by the less precious metals has replaced at least one-half of the amount of platinum that the entire electrical industry would otherwise be consuming at the present time. While the subject is of considerable interest to the metallurgist it is even more so to the electrical engineer and it is surprising that the literature records no systematic and comprehensive investigation along these lines. Practically all the scattered work on noble metal contacts has centered around platinum as a standard and has had two more or less distinct aims. One of these has been the replacement of platinum by cheaper matcrials, and the other, the dcveloprnent of materials of superior electrical performance. The merit of a contact metal has been assumed to be dependent on its infusibility, and since thc more precious metals have the higher melting points there has naturally been an association of the two qualities in the sense that the more precious were

By John Norton

IN recent years, the damping capacity of metals has come to be recognized as an important index of certain types of structural change. In a number of instances, this property has proved to be particularly sensitive, but insufficient work has been done to permit a general inter-pretation. There is considerable question at the present time as to just what factors are responsible for the internal dissipation of energy when a metal is carried through a cycle of stress, and these factors must be ascertained if the value of the damping method as a metallurgical tool is to be determined. Since internal stresses are among the chief causes of dissipation of internal energy, or damping capacity, it was thought that a study of the changes in damping during the recovery and recrystalliza-tion of a cold-worked metal might throw some light upon the subject, particularly if the damping changes were correlated with other properties that are better understood. Probably more work has been done on the recrystallization phenomena of alpha brass than on any other metal, so this was chosen as the material for the present investigation. Damping measurements on brass have been made by Förster and Köster.1 They showed that the annealing of a brass that had been cold-drawn to 50 per cent reduction produced a rapid fall in the damping, a flat minimum occurring at approximately the temperature of recrystal-lization. The damping remained at a low value until grain growth was well under way and then it increased rapidly with increasing grain size. Köster and Rosenthal2 continued the work in greater detail. They pointed out that the damping decrease does not correspond to the hard-ness drop but occurs at a lower temperature, suggesting that the relief or redistribution of internal stresses has a large effect while the actual recrystallization effect is small. They also show the increase in damping at the higher annealing temperatures. Their curves are reproduced in Fig. 1.

Jan 1, 1940

By E. A. Barnard

ARSENIC is a very old substance. The ancients speak of it in their writings, and its use has developed very little until recent years. The ancients used it in making pigments, in medicine, and for poison. They also tell of the difficulties of handling it-an experience which is very similar to our own. Until about 10 years ago, arsenic was very cheap and was a drug on the market. About that time the boll weevil began making serious inroads on the American cotton crops, and after much investigation the Depart-ment of Agriculture developed a very successful poison for this pest, consisting of calcium arsenate. The weevil pest has continued, and as the cotton planters have become convinced that calcium arsenate is the best material to use against the weevil, the demands for it have been steadily increasing, resulting not only in a rising price of arsenic but in a very serious shortage so far as our country is concerned. So serious has this shortage become, and so vital is it to the cotton growing industry, that Congress has appointed a committee to investigate and report on the situation. A meeting of arsenic producers and consumers was held in New York last December to take stock of the situation and to see what could be done. The extreme increase in, the market price of arsenic-from 6 c. to 15 c. per lb. in less than a year-has been very harmful to the producers as well as to the consumers. Some very interesting' data were brought out at this meeting, as follows: CONSUMPTION PER YEAR, SHORT TONS Arsenate of lead 2,000 Paris green 1,200 Proprietary mixtures 750 Sheep dips : 1,000 Weed killers 1,500 Glass : 2,000 8,450 1922 Consumption as calcium arsenate 4,000 12,450 1923 Estimated consumption as calcium arsenate... 12,000 Estimated 1923 consumption 20,450

Jan 8, 1923

Trans. Pamphlet Volume Number Title Author Meeting and Page* 1033 Relation of Air Presaure to Drilling H. W. Seamon New York 66, 743. 766 Speeds of Hammer Drills . Feb. 1921 1034 Time Factor in Depletion of Mines J. W. Roberts New York 66, 711 Feb., 1921 1035 Calculation of Ore Tonnage and Grade J. E. Harding New York 66, 117, 122 from Drill-hole Samples Feb., 1921 1038 Diacuasion of Papers Presented in 1920 1041 Run-off and Mine Drainage H. N. Eavenson New York 66. 624. 630 Feb.. 1921 1043 The Health of the Underground Worker A. J. Lanza New York Feb, 1921 1045 Dust-ventilation Studies in Metal D. Harrington New York 66, 272, 288 Mines Feb., 1921 1046 Discussion of Papers Presented at New York Meeting, 1921 1072 Breakage and Heat Treatment of Rock- B. F. Tillson New York 66. 758 drill Steel Feb., 1921 1073 Discussion of Papers Presented at New York Meeting, 1921 1076-M Analysis of Some Drill-ateel Teats F. B. Foley New York 66,789 Feb.. 1921 1077-M Application of Magnetic Analysis to C. W. Burrows New York 66, -796 Rock Drills Feb., 1921 1078-M Heat Treatment of Rock-drill Steel G. H. Gilman New York 66.779 Feb., 1921 1080 What is the Ideal Drill Steel? F. H. kingdon New York 66, 807 Feb.. 1921 1081 Rock Drill-Steels, etc. W. T. Ober New York 66,814 Feb.. 1921 1082-C Underground Mine Development, Its J. B. Dilworth Wilkes-Barre 66,715, 761 Definition and Valuation Sent.. 1921 1081 Drill Steel from Hollow Ingots P. A. E. Armstrong New York 66,809 Feb., 1921 1068 Authors' Replies to Recent Discussion 1092 Heat Treatment of Rock Drill Steel A.E.Perkins New York 66,811 Feb., 1921 1096-M Octagonal Ventilation Shaft of Davis- J. L. Bruce Wilkes-Barre 66. 252, 608 Daly Copper Co. Sept., 1921 1100-C Determination of Electrical Equip- G. Bright Wilkes-Barre 66,580,606 ment for a Mine Hoist Sept., 1921

Jan 1, 1927

By M. D. Cooper

For the purpose of obtaining some first-hand data in regard to the shooting down of coal in bituminous mines, it was the writer's good fortune to be employed as a shot-firer for almost one year. In all, 6020 shots were fired by him during this period. All of the work was done in what is known as the South Main section of the No. 2 Mine of the Ellsworth Collieries Co., Ellsworth, Pa., a subsidiary of the Lackawanna Steel Go. Position of Shot-firing in the Cycle of Operations The established practice of the Ellsworth Collieries Co. calls first for the undercutting of the coal by electric chain machines across the face of the entry or room. This is followed by replacing any posts removed by the machine-runners, or the setting of new posts or timber, as may be required. After this has been done the machine cuttings are loaded into cars. Then the coal is spragged, and a shot hole drilled to the depth of the undercut. Next in order, the shot-firer loads the hole and fires the charge. The working place is then cleaned up, timbered if necessary, the sides and face squared up, and loose material taken down. The face is again ready to be undercut. Materials Used Permissible explosives were used exclusively in blasting coal. These were Carbonite No. 2, a nitroglyccrine explosive; and three different makes of ammonium nitrate explosives, Tunnelite, Red H, and Mine-ite 5-D. The last-named was used during the greater part of the period. It is interesting to note that even at the beginning of this work, the gases resulting from the explosions of the charges caused no especial distress on. the shot-firer's part and this continued to be the case except on the occasions when a change was made from one class of explosive to another.

Jan 1, 1918

By I. A. Ettlinger

THE formation that the writer has chosen to call "The Central Arizona Batholith" is included in the Globe, Miami, Ray, Pioneer, Troy, and Silver King mining districts. Its extension to the southeast is in the Banner mining field. Basing his argument on what is known of batholithic intrusions, the author offers reasons for considering all these granitic outcrops as parts of a single great mass of plutonic rock. The United States Geological Survey has subdivided this area into three -quadrangles-the Globe, the Ray, and the Florence. Of the first two, geologic atlases1 have been published, but of the last, the topographic map alone is available. These mining districts include such prominent present-day producers as Inspiration, Miami, Old Dominion, Arizona Commercial, Iron Cap, Superior and Boston, Magma, Belmont, and Ray Consolidated. Among those well known in the past are Silver King mine and Gibson mine. Fig. 1 is a geologic map of the Central Arizona Batholith region. F. L. Ransome's excellent work on The Copper Deposits of Ray and Miami, Arizona,' is of great value to all workers in those districts. His geologic map for the Ray and Globe quadrangles has been incorporated in Fig. 1, and the stratigraphic names employed are those first applied and defined by him in his pioneer work in this region. The purpose of this paper is to show that the ores are related to post-Carboniferous granitic intrusions; that while there does not seem to be any adequate explanation for the distribution of all the igneous stocks, a preexisting structure does appear responsible for at least the location of the largest igneous stock of the region; that the principal producing vein mines are located in the sedimentary rocks in the roof of this batholith, while the disseminated copper deposits are found bordering the lower portions of the batholith exposed by erosion; that primary zoning is illustrated not only on a broad (district) scale but also on a small (individual

Jan 1, 1928

By Howard N. Eavenson

One who has been trained in belief in the law of supply and demand and its effect upon prices finds it difficult to adjust himself to the minute regulations imposed by the New Deal, and also to the bewildering changes of government policy as expressed within a short period of time between the antitrust laws and the N.R.A., and later by the Bituminous Coal Conservation Act of 1935. A survey of the coal industry since the World War, both in this country and Great Britain, however, shows that regulation of some sort is needed if any stabilization is to be achieved and if the wage structure and economic welfare of the many communities dependent solely upon coal are to be maintained. Let us look at what has happened to the industry since 1920, which can be considered as the end of the period affected by the war influence. This discussion will be confined solely to bituminous coal, although many of the general conditions are equally applicable to anthracite, the position of which now is at least as bad as that of the softer variety. Since 1920—to the end of 1934—the production of coal has decreased from 568.7 million to 358.4 million tons, or 37 per cent; the number of mines from 14,766 to 6,258, or 58 per cent; the average annual production per mine has changed from 38,512 to 57,425 tons, or 50 per cent. The number of large mines has increased considerably, and the number of men employed has decreased from 639,547 to 458,011, a reduction of 28 per cent, while the average output per employee has changed from 4.0 to 4.4 tons, or an increase of 10 per cent. The average price per ton of coal at the mine has varied from $3.75 to $1.75. During that time wages decreased largely until 1933 and since that time have increased, until now the rates paid are considerably above those in other occupations, although the actual yearly earnings are low, because of part-time work. From 1920 to the signing of the Jacksonville wage agreement in 1924, about two-thirds of the men were union members and practically all of the nonunion mines were south of the Ohio River; with the fixing of the high wage scale of that agreement, which soon proved to be an uneconomic one, many of the mines found that they could not retain their business, so gradually changed to nonunion. By 1928 the proportion

Jan 1, 1936

By S. Floreen

Measurements have been mode of the effects of tempering and austenitizing heat treatments, the work-hardening characteristics, and the effects of test temperature and strain rate on the properties of a low-carbon Fe-18 pet Ni martensitic alloy. In many respects the alloy behaved quite similarly to cold-worked iron. One notable quality was the excellent ductility at temperatures as low as 20°K. Many of the qualities of the maraging steels could he related to the properties of the Fe-Ni matrix. THE 18 pet Ni maraging steels have demonstrated that unusual combinations of strength and toughness may be obtained by age hardening a low-carbon Fe-Ni martensite matrix.' These properties must, to some extent, reflect the properties of this Fe-Ni matrix, and therefore an understanding of the properties of this matrix is a prerequisite to a complete understanding of the steels. There have been several recent studies of Fe-Ni-C martensites, but not much attention has been paid to alloys with very low carbon contents. At low carbon levels the crystal structure of these alloys is essentially bee.2 Electron transmission microscopic examination of a 20 pet Ni binary alloy showed martensite platelets separated by low angle boundaries.3 Plastic deformation of the low-carbon alloys has been shown to proceed by wavy glide.4 The hardness of these martensites is typically RC 28, and their yield strengths are 70 to 80 kg per sq mm.2, 5 Their ductility is excellent. Room-temperature tensile elongations of 18 pet and reductions of area of 70 pet have been observed in an Fe-18 pet Ni binary alloy.5 These observations have provided a qualitative understanding of the flow characteristics of these alloys. To date, however, no thorough study of their properties has been made. In particular, it is not known to what extent the deformation characteristics of low-carbon martensites are similar or dissimilar to those of pure iron or other bee metals. The present work was undertaken to provide more detailed information on the flow characteristics of a low-carbon Fe-18 pet Ni martensite. PROCEDURES, RESULTS, AND DISCUSSION Materials. A 40-lb heat of the Fe-18 pet Ni alloy used in this study was made by vacuum-induction melting. The charge materials were electrolytic iron and electrolytic nickel. A carbon boil was used to achieve deoxidation. After the boil the heat was refined by additions of 0.1 wt pet Ti and Al. These additions are commonly used in the maraging steels to keep the carbon and nitrogen contents in solid solution at a minimum. After casting, the heat was

Jan 1, 1964

By Nathan C. Rockwood

The title of this paper, I understand, was suggested by professional mining engineers as an opportunity for someone to pose problems rather than to offer solutions for them, but the paper will merely attempt to pose some of the production problems of the mineral aggregates industry in such manner as to create professional interest in their solution by the mining engineer, geologist, geochemist and the metallurgical engineer versed in mineral-dressing technique. Definition of Mineral Aggregates " Mineral aggregates" may be defined as fragments of any rock or mineral used to supply bulk or volume or substance for a given purpose. For example, mineral aggregates are used in portland-cement concrete to provide bulk with the expenditure of the least feasible amount of cement binder. Mineral aggregates are used without port-land cement or bituminous binder in highway and railway roadbeds to provide substance, to carry loads. provide aggregates are used in filters for water and sewage, to provide substance for the liquid to trickle through. These are only a few typical uses of mineral aggregates. For all these uses, strength, toughness, resistance to abrasion, and durability are usually prime requisites; so, while theeretically mineral aggregates may be of any mineral composition, what really is desired is a mineral composition as nearly inert under the conditions of use as anything of earthly origin can be. Exploration and Possibilities of Development The distribution of deposits of mineral aggregate is universal, since almost any part of the earth,s crust can be used; even the top soil is sometimes used in stabilized surfacing for highways or airport runways. Nevertheless there is ample opportunity for exercise of the talents of the mining engineer and the geologist in finding the particular deposit that will be most economical to develop, keeping in mind such considerations as: (i) quality and mineralogical characteristics of the material; (2) size and permanency of the market; (3) final cost of opening and development of the deposit; (4) selection of location of plant; (5) methods and costs of distribution of the product in comparison with both present and possible future competition; (6) selection of the proper type of operating equipment; (7) estimation of probable waste products and their disposal. These are typical but there are other considerations also. Because profit margins are far smaller than in any comparable mining operation, it is all the more logical to assume that a higher degree of expert knowledge is desirable to make a success of a mineral-aggregates business. The industry has much engilleering talent in its operating branch, but it lacks, to a considerable degree, engineering talent with experience

Jan 1, 1948

By C. W. Phillips, R. S. Busk

With most cast metals the grain size may vary within wide limits, depending upon the conditions at the moment of freezing. These conditions are subject to control in magnesium-base alloys, by proper melting and superheating techniques, enabling production of quite uniform and fine-grained castings, almost independent of section thickness. However, such variations of grain size as do exist, in common with all metals, are reflected in corresponding changes in mechanical properties. It is the intent of this paper to present data giving the relationship between grain size and mechanical properties. Data are also included on the combined effects of grain size and micro-porosity. In addition, a short discussion of factors influencing the grain size of sand castings is included. Measurement OF Grain Size By grain size is meant the statistical distribution of volumes occupied by the individual crystallites in a metal section. Since this is almost always impossible of direct measurement, several methods of estimating and expressing the size have been evolved. Most exact methods make use of the microscope. This involves study of a single plane cut at random through the metal. What is seen in the microscopc are polygons, each the cross section of a grain. The diameters or areas of these polygons are then measured and the grain size is expressed as an average diameter, number of grains per unit area, average area per grain, or, rarely, average volume per grain. Rutherford, Abom, and Bain3 have discussed extensively the errors involved when using a plane section to estimate volume. They clearly point out that the tendency is to underestimate the true grain size because of the nature of the measurcment. The A.S.T.M. recommends that measurement be made by comparison with a standard chart, by means of Jeffries' planimetric method4 or Heyn's intercept method. The Society recommends that the notation be in terms of the number of grains per unit area (as is the grain-size number used for steel) or as an average diameter, expressed in inches or millimeters (as for copper and brass). The method of measurement used for this study was comparison with a standard chart, which has been described by P. F. George.5 The chart was constructed by photographing at Ioo diameters a uniform specimen with an average grain diameter of 0.003 in. The average diameter of this specimen was determined by numerous measurements, using both the Jeffries and Heyn methods. The other grain sizes were then obtained by appropriate enlargemcnt of the master sample. Careful comparison of the chart method with other methods on identical samples indicates that though the differences be-

Jan 1, 1945

By Hans Neuberger

In our everyday life, visual perception plays perhaps a more important role than any of the other senses with which we are equipped by nature. It is, therefore, quite understandable that the average person associates with the term ''atmospheric pollution," clouds of dust, palls of smoke or deposits of soot, phenomena which are so familiar to the residents of industrial cities. On the other hand, "air" is usually considered the prototype of the invisible, of the intangible, and any suspensions in the air which do not conform to this concept, are regarded as foreign to the atmosphere and thus as "pollution." According to Webster, the term "pollution" implies uncleanness, impurity, in short, something undesirable. Although the scientist often accepts popular concepts, he is generally inclined to suspect that apparently "obvious" phenomena imply, literally, "more than meets the eye." To show that this suspicion is also justified with regard to atmospheric pollution, is the objective of this discussion. It will be shown that what seems foreign to the air at first sight, is by nature an integral part of it, and that the more important aspects of pollution generally escape attention. The Atmospheric Constituents We can distinguish two classes of atmos-pheric constituents: the Permanent gases, chiefly nitrogen, oxygen, traces of argon, neon, and others, and the variable constituents which include water in its different states, carbon dioxide, ozone, and various suspensions, either in gaseous, liquid or solid form. These suspensions, known by the collective term "Aerosol,"20 will be considered in detail. Dust There are two general types of aerosols: the first type is represented by the socalled "neutral" particles,3 commonly known as dust and experienced by everyone, as it is the more conspicuous type of suspensions. It often represents a special problem to the mining engineer, the mechanical engineer, the industrial engineer, and many other professional men. Dust consists of finely divided solids derived from weathering, drilling, handling and preparation of rocks and coal. Dust may also consist of organic or inorganic particles resulting from manufacture of a variety of products such as flour, rubber, lime and steel, from traffic on land be it on the highways, on rails or in city streets, from decomposed vegetation or from volcanic eruptions. Perhaps the most reviled member of this class of suspensions is the soot and fly ashes from coal fires and other combustion processes. The cosmic source of dust, namely the injection of meteoric matter into the atmos-,,here, is of minor significance because the concentration of particles is exceedingly small despite the relatively large mass of material which invades the earth's atmos-phere from space.

Jan 1, 1949