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By Alden B. Greninger, Alexander R. Troiano

THE crystallographic mechanism for the austenite-to-martensite transformation has been deduced from the results of the following new experimental determinations: (I) the accurate evaluation of the lattice relationship between austenite and individual crystals of martensite-and thus the relationship between the martensite lattice and the martensite plate, and (2) the measurement and analysis of the change in positions that a volume of austenite undergoes when it transforms into a crystal of martensite. For the latter study, a new tool was developed, the stereographic analysis of shear. Lattice relationship.-Thirty-five separate 50-gram melts of an alloy containing about 22 per cent nickel and 0.8 per cent carbon were prepared in a high-vacuum furnace. This alloy is all-austenite at room temperature; grain size was about I cm. Specimens of the alloy were cooled to about -70°C. to form a few martensite crystals, and suitable specimens were ground and polished on a surface parallel to a single martensite plate, exposing the martensite crystal for an area of I mm. or more. Four martensite cystals from four different ingots were prepared in this manner; the largest crystal of this group is illustrated in Fig. I. Back-reflection Lane patterns were obtained from martensite [ ] crystals (and the matrix austenite) both before and after tempering. The locations of the basal-plane pole of martensite was checked by means of oscillating crystal X-ray patterns. All four crystals studied yielded the same solution (±0.5°), and these relationships are expressed in gnomonic projection in Fig. 3.* The narrow dark-etching bands often visible in martensite "needles" were found to be parallel to {112} and thus are undoubtedly twin bands in the martensite crystal.

Jan 1, 1941

By Alden B. Greninger, Alexander R. Troiano

The crystallographic mechanism for the austenite-to-martensite trensformation has been deduced from the results of the following new experimental determinations: (I) the accurate evaluation of the lattice relationship between austenite and individual crystals of martensite—and thus the relationship between the martensite lattice and the martensite plate, and (2) the measurement and analysis of the change in positions that a volume of austenite unclergoes when it transforms into a crystal of martensite. For the latter study, a new tool was developed, the stereographic analysis of shear. Lattice relationship.—Thirty-five separate 50-gram melts of an alloy containing about 22 per cent nickel and 0.8 per cent carbon were prepared in a high-vacuum furnace. This alloy is all-austenite at room temperature; grain size was about I cm. Specimens of the alloy were cooled to about — 70°C. to form a few martensite crystals, and suitable specimens were ground and polished on a surface parallel to a single martensite plate, exposing the martensite crystal for an area of 1 mm. or more. Four martensite cystals from four diffierent ingots were prepared in this manner; the largest crystal of this group is illuslratecl in Fig. I. Back-reflection Laue patterns were obtained from martensite crystals (and the matrix austenite) both before and after tempering. The locations of the basal-plane pole of martensite was checked by means of oscillating crystal X-ray patterns. All four crystals studied yielded the same solution ( ± 0.5°), and these relationships are expressed in gnomonic projection in Fig. 3.* The narrow dark-etching bands often visible in martensite "needles" were found to be parallel to (112) and thus are undoubtedly twin bands in the martensite crystal.

Jan 1, 1941

By Carl S. Westerberg

Coal preparation practice and trends follow, among other factors, production trends in any given area. Considering an area the size of a state, some broad predictions may be made after a review of the annual production records. As this paper is concerned with coal cleaning in Utah, data on its production record are pertinent. Table 1 shows the percentage relation of coal production in Utah to the national total as a single figure up to 1935 which includes all recorded production. From 1935 through 1947 these data are presented by years. It is evident from these data that the production of Utah coal is ascending. The reason for this trend is industrial growth in the West resulting in a population shift which accounts for more people than the normal increase would supply together with Utah's relatively fortunate geographical location and its abundance of good-quality coal. Utah is also hopeful of supplying more coal in the future for West Coast power generation.I Utah is not unique among coal-producing states in anticipating greater production in the future. Coal Age states, " . . . it is now evident that a billion-ton yearly production of anthracite and bituminous by 1960 is not impossible." At present it is about 610,000,000 tons, the all-time high in 1947 was approximately 687,803,000 tons. In view of the trend outlined above, obviously more new mines will be required to produce the necessary tonnage. These in turn will require more mechanical cleaning capacity. Whether the required new plants will be built by present operators of mines and mechanical cleaning plants or by others now in the business of producing coal or expecting to enter it is of no consequence in this discussion. The fact is— they will be built.

Jan 1, 1950

By T. F. Witherbee

ON the 22d of November, „1879, white iron unexpectedly appeared while working the Cedar Point Furnace, Port Henry, N Y., on the following burden, calculated to turn out mill and foundry iron: Anthracite coal, - 3000 pounds. Connellsville coke, - 1500 pounds. Total, - 4500 pounds. Old Bed ore, - 3750 pounds. New Bed fine ore, - 2000 pounds. New Bed chunk ore, - 1000 pounds. Kearnev hematite ore, - 750 pounds. Total, - 7500 pounds. Magnesian limestone, - 1865 pounds. Common limestone, - 885 pounds. Total, - 2500 pounds. The production per week since making mill iron-from September 1st, 1879, to date, seven weeks-was 412 gross tons. Ore was not immediately taken off, as nothing serious was looked for. The iron for the next week graded from No. 4 to white, and in. six days the make was 274 1/2 tons. At 10 P.M., Friday, the 28th, a slip of-..4 feet occurred, and on Saturday, at 5 A.M., another of 3 feet on the south side and. 7- feet on the north side took place. At this time it was found that the south side had been hanging for over a week--a fact which had not been reported. Throwing off the wind, to produce slips. and reduce pressure, had been tried with no effect. The stock, as seen through the tuyeres, seemed to consist almost entirely of coal, with just enough infusible cinder to cement it into a mass through which the blast could not be forced. At 3.50 A.M., Sunday, the 30th, the first cinder seen in seventeen hours came into tuyeres Nos. 1, 2, 3, and 6, At 9.30 A.M. No. 3 was taken out to see if the stock

Jan 1, 1881

SEVERAL distinctions can rightfully be accorded the Bagdad enterprise. For one thing, it has the most romantic name among the Porphyry Coppers and this is said with all due deference to Copper Queen and Inspiration! Bagdad was one of the richest and most magnificent cities of the glamorous world of the Arabian Nights. The record does not say who was responsible for applying the name Bagdad to the company that in 191 1 took over the property of the Arizona-Nevada Copper Company; but whoever it was must have had visions (or at least hopes) of a fabulously profitable mine. So far as I know, Bagdad is the only Porphyry whose owners, or officials, ran afoul of the law because of alleged sins of omission or commission in vending shares of the company's stock. E. B. Bronson, of New York, had been interested in Bagdad since 1909; and, during the lean period of the 1930's he had, as president of the corporation, endeavored to raise needed funds by the sale of 140,000 shares of treasury stock. Some legal questions arose as to the need for registration under the Securities and Exchange Act; but, when Mr. Bronson finally filed a registration statement, the New York office of the Securities and Exchange Commission found 155 "deficiencies" in the document. According to the judge who later heard the criminal case against Bronson, no evidence was introduced to show that he had personally benefited "to the extent of one dollar." However, it was charged that the setup was such that he was in position to profit if he had wanted to! A somewhat quixotic position, it would seem. In any event, he was convicted, on highly technical

Jan 1, 1957

By Donald C. Moore

INTRODUCTION Published laboratory procedures used by the major crusher manufacturers for estimating crusher size are based upon techniques developed in the mid 1940's. Specifically, the two largest U.S. crusher manufacturers are using the Bond impact procedure. Although the procedure is still in use, there is little confidence in the results. Unless the laboratory results fall within a preconceived range, personal experience is used for selecting the number of crushers and connected horsepower (Coleman, 1978). There have been numerous theoretical studies of the communition of particles. However, no procedure has been widely acclaimed for predicting crusher power requirements. Experimental studies have included breakage by slow compression, slow speed impact and high speed impact. Theoretical results have increased our knowledge of the comminution process, but the procedures have not been capable of analyzing the complex mechanism of industrial crushing machines. The purpose of this chapter is to review the empirical crushing procedures that have been used, including advantages and disadvantages. A new procedure which has been in development at Allis-Chalmers Corp. from 1977 to 1982 is detailed. Actual results of the new procedure on a concentrator feasibility study are included. EXPERIMENTAL GOALS The goals of a laboratory crushability procedure are accurate predictions of: (1) Rock crushability, measured as energy per unit mass. (2) Crusher product size analysis. A procedure capable of predicting these parameters should be inexpensive and require a minimum amount of sample. CRUSHABILITY TESTS Bond Impact Procedure F. C. Bond (1946) detailed the development of the pendulum impact device that is still used by the leading crusher manufacturers (Bond; Rexnord, 1976). The device (Fig. 1) is comprised of two bicycle wheels with 13.6 kg steel hammers tangentially attached to the rims. The hammer faces are 50 mm apart at rest. On opposite ends of the hammers lifting

Jan 1, 1982

By W. L. Maxson

GRINDING is one of the major problems in present-day milling practice, and in many cases, it represents one of the main items of expense. It becomes necessary from time to time, to compare grinding practice in one plant with that in another plant, and in making such comparisons, it would be very desirable were there available accepted standards of grinding resistance for the materials involved. Such a set of grinding constants would also be of considerable value in planning new grind-ing installations. There have been some tests published, notably those of Lennox,1 which have been generally cited as a basis for such comparisons. Most of the tests made have been based upon open-circuit grinding, in which a weighed sample of the ore was crushed to pass a certain mesh, and was .then ground under certain conditions, either wet or dry. Grinding was continued until a certain desired fineness was attained, and the compari-sons based on the grinding time, or the samples were all ground for a certain specified length of time and comparison based upon the screen analysis of the products. Such methods have been acceptable where the ore was to be ground in open circuit. However, in modern milling practice, many grinding problems involve closed circuits wherein the oversize returns to the mill and a large circulating, load builds up. A method of testing that does not take the circulating load into consideration might yield results quite different from those to he expected in practice, because the minerals in the ore that offer maximum resistance to grinding will accumulate in the circulating load up to an equilibrium value. Thus the nature of the ore charge in the mill at any instant may differ greatly from that of the new feed, with a consequent error in the rate of grinding determined by such a method.

Jan 1, 1933

By Oliver Hopkins

As prefatory to the body of this paper, a few general statements will be made (1) in regard to the history and importance of the asbestos industry, (2) as to the principal sources of the raw material, and (3) as to the types and modes of occurrence of asbestos. While the modern asbestos industry is comparatively new and its growth during the last decade or two has been marvelous, asbestos has been known and used in a small way for probably 2,000 years-at least since the time of the Roman Empire. Pliny refers to it as "the funeral dress of kings" and Plutarch records its use as lamp wicks. In the middle of the 18th century the deposits of the Ural mountains were opened up and the first factory for the manufacture of asbestos goods was established. But, owing to the limited demand for the goods, the industry disappeared and interest lapsed until about 50 years ago. Since 1860, the asbestos industry has made wonderful strides, and each year sees new uses to which the material can be put, and hence an increased demand and an increased output. Of the three great producers of asbestos, Canada, Russia, and the United States, Canada stands pre-eminent, producing from one-half to three-fourths of the world's supply; Russia comes second, producing ,in 1911 about two and one-half times ,is much as the United States. In 1912 the Canadian production,1 including both asbestos and asbestic, was 131,260 short tons, valued at $2,979,384; while during the same year the production of the United States2 was 4,403 tons, valued at $57,959. Canada holds the first place in the production of raw asbestos, while the United States holds the first place in its manufacture.

Jan 9, 1914

By Bertrand S. Summers

The technologist who has devoted much attention to the foundry-business will perhaps have noticed that the present scientific development of foundry-practice is in a condition similar to that of the steel-business some twenty years ago. In many cases chemistry is looked upon with suspicion, and the old cutand-try-methods are still in vogue, especially in the smaller foundries. The larger works have laboratories and more extensive means for applying science, and have devoted considerable time and attention to the improvement of foundry-practice. This is more especially true in the East, although in the West there are numerous firms devoting considerable attention to improving their metllods through the application of chemistry to work in the iron-foundry. It is hardly necessary to dwell extensively upon the effects of the different metalloids associated with iron, in pig- or castiron, in the way they are given in most text-books. The writer has thought proper to consider more particularly new developments in eupola-practice, particularly those pertinent to the discussion of the physics of cast-iron. In this connection some new ideas which recent practice has developed will be mentioned, and some results of practical tests along the same line will be described. Yet it has been deemed advisable also, by way of introduction, to outline the effects of the metalloids as they are described in most text-books, without going into detail. The question is sometimes asked, What is the most important element governing the quality of cast-iron 'for any particular purpose ? It would seem that right here lies the basis for the greatest difference of opinion. Some twenty years or more ago, silicon was regarded by foundrymen as one of their worst

Jan 1, 1899

By Alexander Gow

THE object of this paper is to discuss the fundamental principles of ball milling and to present some observations which have been made in laboratory and plant investigations. The discussion will be limited to wet grinding of ores in cylindrical mills, but doubtless many of the principles involved will be equally applicable in the other fields of fine grinding in which mills of the same type are used. In the concentrators of the United States there are about 650 ball, rod, or pebble mills, operating or ready to operate, and these have about 100,000 connected horsepower. For grinding in cement plants there is about three times this connected horsepower, and other industries have an unestimated amount, all used for the general type of grinding that is to be discussed here. It is true that these figures do not represent stupendous amounts of power, but when one considers that ball milling is often the "bottle neck" in a concentrator and that it often accounts for the largest single item in the cost sheet, the importance of a compre-hensive understanding of the principles of ball milling can be appreciated. Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses, or with the exclusive consideration of certain specific varia-bles, such as mill speed or circulating load, irrespective of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison, a new philosophy in the study of ball milling. Briefly, this "new philosophy" consists of using power as an index of the mill operation, and investigating grind-ing from the standpoint of set and induced variables, with emphasis on the latter.

Jan 1, 1934

By W. H. Coghill, A. M. Gow, M. Guggenheim, A. B. Campbell

The object of this paper is to discuss the fundamental principles of ball milling and to present some observations which have been made in laboratory and plant investigations. The discussion will be limited to wet grinding of ores in cylindrical mills, but doubtless many of the principles involved will be equally applicable in the other fields of fine grinding in which mills of the same type are used. In the concentrators of the United States there are about 650 ball, rod, or pebble mills, operating or ready to operate, and these have about 100,000 connected horsepower. For grinding in cement plants there is about three times this connected horsepower, and other industries have an unestimated amount, all used for the general type of grinding that is to be discussed here. It is true that these figures do not represent stupendous amounts of power, but when one considers that ball milling is often the ((bottle neck" in a concentrator and that it often accounts for the largest single item in the cost sheet, the importance of a comprehensive understanding of the principles of ball milling can be appreciated. Much of the past literature devoted to the subject has been concerned with the Kick-Rittinger dispute over evaluating grinding, or with dissertations on ball paths and the closely allied impact versus attrition hypotheses, or with the exclusive consideration of certain specific variables, such as mill speed or circulating load, irrespective of the other factors in operation. Such subjects may be dismissed with but little discussion in what may be called, by comparison, a new philosophy in the study of ball milling. Briefly, this '(new philosophy" consists of using power as an index of the mill operation, and investigating grinding from the standpoint of set and induced varisbles, with emphasis on the latter.

Jan 1, 1935

Jan 1, 1932

By EUGENE MCAULIFE

Jan 1, 1934

Jan 1, 1932

Jan 1, 1932

By W. S. Ayres

The protractor here to be described embodies several important improvements that have been suggested by the use of other protractors and by observing the errors occurring in practice with them. It is more particularly an improvement

Jan 1, 1896

By John A. Riddle

Some of the pitfalls and problems in selecting and applying corrosion-resistant materials in uranium plants are discussed, together with some suggested solutions. Includes some cost data.

Jan 1, 1982

By I. R. M. Chaston

Radial layout’s guiding principle is the grouping under one roof of the operating processes which require continuous supervision. Separate treatment sections are isolated by outside stockpiles fed with radiating conveyors. Hence the name ‘radial’ layout. Many plants are designed with ‘linear’ layout where successive operating stages are dotted like beads along a string of conveyors. [Figures 1 through 5] show the development of the radial concept in the layout of heavy-media diamond recovery plants over

Jan 1, 1979

By Hamish D. S. Miller

Currently the underground potash mines in Canada extract about 40% of the available ore, leaving the other 60% behind in the form of stabilizing pillars. The presence of water in the overlying formations requires that any disturbance due to mining be such that no water will enter the workings. This paper deals with the factors that influence the stability of the rock surrounding the mine excavations and looks at the effects of these factors when a system of increasing the extraction is considered.

Jan 1, 1983

By Oswald J. Heinrich

AT the Baltimore meeting of the Institute in February, 1879, Mr. Eckley B. Coxe, then president of the Institute, called attention in his address to the subject of Secondary Technical Education, and

Jan 1, 1881