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By Martin A. Moyers

THE nation's effort to win the war speedily is reflected in current trends in coal utilization, as in all other fields of our lives. In all industries, wherever coal is used for the production of heat and power the emphasis is on getting the most useful result with the least expenditure of matt.ria1. In addition to carrying its own share of the load, increased as it is by the demands of war industry, coal has had to fill in for the other fuels, mainly petroleum products, whose distribution from their more distant sources has been crippled by lack of shipping. Thus, the outstanding note in the utilization of coal this year is not the development of new methods of burning or handling coal but the extraordinary job that the industry has done in producing enough coal to serve all needs.

Jan 1, 1943

By W. F. Chiao, R. B. Gordon

Tile sharp-yield point found in magnesium crystals in the solulion-treated and aged condition is studied by dislocation internal-friction experiments. The results show that the sharp yield is not file to the sudden release of pinned dislocations hut is movc likely due to the rapid multiplication of an initially small number of dislocations. Recovery or the dislocation internal friction after deformation is also studied. This yecovery results from the re-pinning of dislocations by a solute, presumably nitrogen, which moves with a relatively small activation energy. SHARP-yield points, when they occur, are a striking feature of the stress-strain curve generated during a tensile test. Although commonly associated with steel, sharp yielding has been found in a variety of metallic and nonmetallic crystalline materials. In particular, sharp-yield points have been found in zinc"' and cadmium3 containing nitrogen. With this background, Geiselman and Guy4 investigated the tensile properties of magnesium single crystals containing nitrogen to see if sharp yielding also occurs in this system. They found that sharp yields did indeed occur in solution-treated and aged specimens tested at elevated temperature but were not able to give conclusive proof that the sharp yield was caused by nitrogen, a yield drop being observed even in their purest crystals. Sharp-yield points have also been found in various polycrystalline magnesium alloys.7'8 In the study of the sharp-yield phenomenon it is desired to observe the behavior of dislocations in the earliest stages of the deformation process. Internal-friction experiments are useful for this purpose because dislocation damping is sensitive to the mobility of free-dislocation segments. At low strain amplitudes the damping, A, due to the the forced vibration of dislocation segments of average length L is ? =KAL4 [1] where A is the dislocation density and K, if the applied frequency is well below the resonant frequency of the dislocation segments? is a constant for the sample under observation.5 Dislocation damping, because of the fourth-power dependence on L, is particularly sensitive to the creation of free-dislocation segments during deformation. Since sharp yielding is associated with the sudden release of pinned-dislocation segments, marked changes in the dislocation damping are expected at the yield point.6 The use of the dislocation-damping observations to help elucidate the incompletely understood mechanism of yielding in magnesium is the primary objective of the experiments reported here. PROCEDURE Many investigations have shown that very marked and rapid changes occur in the dislocation damping of of a deformed material as soon as the straining is stopped.5 It was quite essential, then, for the purpose of this investigation, to make the damping measurements during the deformation of the samples. This can only be accomplished through the use of the ultrasonic-pulse method. In this method traveling sound-wave pulses are used and, in contrast to resonating-bar methods, only the sample ends are set in vibration. Thus, the sample can be gripped along its sides in the tensile-test machine without disturbing the damping measurements. In the pulse method, the decrease in the amplitude of a sound pulse is measured as it travels back and forth through the sample. If A is the amplitude after traversing a distance x and A. is the initial amplitude, A=Aoe-ax [2] and a is called the attenuation. It is commonly measured either in units of cm-I or as db per µ sec. The observed attenuation in a metal sample is due to a number of causes. These include scattering by grain boundaries and impurity particles, thermo-elastic damping, diffraction effects, stress-induced ordering of solute atoms, and dislocation damping. The total observed attenuation in a given sample usually cannot be resolved into these various components, but changes in a due solely to changes in dislocation damping can be accurately determined, provided the experiment is arranged so that all other sources of damping are held constant. It is desired to reduce the extraneous sources of attenuation to a minimum and for this reason the experiments are done on single crystals of high purity. Magnesium crystals offer the further advantage that, when properly oriented, only a single set of slip planes is active during deformation. Crystal Preparation. The method of sample preparation is similar to that of Geiselman and Guy.4 The starting material was high-purity, sublimed magnesium rod supplied by the Dow Chemical Co. Melting under Dow 310 flux was used to reduce the nitrogen content of the starting material: the fluxing was done under an argon atmosphere and the

Jan 1, 1965

By G. P. Tiwari

Recrystallization and grain growth in thoria dispersed nickel and nichrome were recently studied by Webster as a function of temperature and deformation. The unexpected part of these results was that specimens which had received heavier deformation developed greater resistance to recrystallization. Retardation of recrystallization was accompanied by the formation of voids around thoria dispersion. To explain these results, Webster suggested that the formation of void around the particles increased the effective size of thoria particles. This resulted in greater impediment to the grain-boundary migration and as a consequence the recrystallization of the matrix is retarded. In the present note an alternative and more probable explanation for the effect of voids on recrystallization is presented. The exact mechanism of void formation in thoria dispersed nickel or nichrome is not known. However, it is reasonably certain that it must be preceded by the stress concentration in the matrix around thoria dispersion during the deformation.'' The resulting stress concentration must be sufficient enough to supply the surface energy for the new surfaces created. Further, the decrease in the strain energy of the matrix surrounding the potential void nucleus must be larger than the surface energy of the newly created surface. The release of strain energy due to formation of crack results in a strain free cylinder of the material around the voids.13 If the void formation is not localized, at few points only (as is the case here), this process may lead to considerable amount of release of strain energy of the matrix. The pattern of recrystallization behavior of single phase homogeneous matrix as well as the matrix having a second phase dispersion is same except for the fact recovery and recrystallization are more clearly delineated.14 In general, the recrystallization temperature is lowered (i.e., recrystallization is easier) with increase in the amount of cold work. This is due to the increase in stored energy in the matrix with increasing amount of deformation. If somehow there is a relaxation of strain energy in the matrix, the recrystallization should become difficult because of the decrease in the amount of stored energy available for recrystallization. Since the formation of voids leads to a decrease in the strain energy of matrix, the recrystallization of the matrix would be inhibited due to the formation of voids during deformation prior to recrystallization. It has been observed by earlier workers15'16 that the presence of preexisting voids in a matrix retards the recrystallization. The essential issue here is how do the voids act to produce this effect. If the voids influence recrystallization only by blocking the grain boundary migration, then the effect should be maximum when they are present almost exclusively along grain boundary. These conditions are obtained during high temperature deformation. However, the voids produced due to creep along grain boundary are not able to prevent recrystallization17 suggesting that they are not effective in blocking grain boundary movement. Recently it was shown by Davies and Williams that the voids can act as sinks for vacancies." As a result the processes dependent on vacancy diffusion like recovery, recrystallization, dislocation climb, and so forth, will be hindered. This fact may be responsible for inhibition of recrystallization during subsequent deformation and annealing cycles. It is to be noted here that there is a large difference between the density of voids in creep experiments and the other experiments where retarding effect of voids on recrystallization is seen. The voids in former may number up to l04 to l05 per sq cm whereas in latter cases the voids density is typically around 1010 to 1013 per sq cm. It appears that the decrease in supply of vacancies in creep is insufficient to adversely affect the recrystallization due to low void population. The author is grateful to P. Das Gupta and S. P. Ray for helpful discussions. Author's Reply D. Webster Tiwari appears to have misunderstood the nature of grain boundary-particle interactions. Tiwari (quoting Cahn) states that second phase particles become more effective as they become smaller, therefore as the voids in TDNiC make the thoria particles effectively bigger their ability to resist grain boundary movement is impaired. This particle size argument was originally proposed in the form of an equation by Zener 20 years agol9 and is not necessarily valid as is discussed below. However, assuming it is valid, it predicts a greater boundary restraining effect by smaller particles simply because their combined cross sectional area is greater at a constant volume. If the number of particles remains the same and their effective size increases, as in the present case, Zener's equation predicts a greatly reduced grain size. This is because the effect

Jan 1, 1970

By E. H. Crabtree

IN an ideal mill, with perfect milling operations, the mineral extraction would be 100 per cent, the, concentrate would be 100 per cent mineral, the tailing would assay zer.0 mineral and the milling cost would be zero dollars. Such an operation can, of course, never be attained. We can only strive to approach it as nearly as possible and in doing so most recognize .the fact that the three primary factors in milling: assay of concentrate, assay of tailing, and cost of operation bear a definite economic relationship to each other. This relation will change from time to time and will be different for different mills, depending on milling equipment, character and quality of feed, market conditions, and other factors. It is granted that for a given operation there is an economic point, but the location of this point is difficult. It is for the purpose of making some of these economic points a little more tangible that this paper has been prepared.

Jan 1, 1930

By S. F. Shaw

IT IS generally recognized that the natural gas absorbed in petroleum plays the leading r6le in moving the oil through the sands to the well and supplies the energy that delivers the oil to the surface when the wells are flowing. It is the purpose of this paper to note the amount of oil that could be lifted by this gas if 100 per cent. efficiency were obtained and the efficiencies actually obtained in the use of this gas. An article in MINING AND METALLURGY,' stated that in a Wyoming field, with a pressure of 300 lb. per sq. in., there would be absorbed 65 cu. ft. of gas per barrel, or 1.55 cu. ft. per gal. of oil. The writer does not know if data have been obtained, by experiment, for pressures beyond those indicated in this article, therefore, for the purpose of illustration, he has projected this curve to obtain figures for pressures greater than 300 lb., although probably experiment will show that the extended line is not quite correct.

Jan 1, 1926

By J. F. K. Brown

ANTHRACITE?S satisfactory showing in 1942 was accomplished in the face of adverse conditions, such as the loss of man power to the active services and to other industries, and the difficulty and delay in obtaining the necessary materials and equipment required in mining operations. Although the in- creased output was stimulated by the war, and thus does not impress one as contributing to continuing improvement in the industry, nevertheless the year witnessed several efforts ant1 consideration of others that have the appearance of permanent progress.

Jan 1, 1943

By Murl R., Schrock

THE use of diamond-drill holes at the Moctezuma Copper Co., Pilares mine, Pilares de Nacozari, Sonora, Mexico, for the ventilation of raises has resulted from experiments that were made in an effort to secure continuous and efficient ventilation in hot and gaseous raises. The method is particularly applicable in long raises and in raises run from development levels where the source of fresh air is distant. In order that the CO, concentration shall not become excessive, 30 cu. ft. per min. per man must be supplied to a heading for breathing purposes:' The quantity of air that will pass through a diamond-drill hole by

Jan 1, 1929

By D. W. Brunton

THE maps of our large mines are usually prepared with the greatest care; and it is somewhat singular that, in comparison with the great amount of time and money spent in surveying and platting, so little actual use is made of them. Almost the only purpose for which a completed survey-map is afterwards consulted, is the determination of the relative position of the different workings to each other, and to the boundary-lines of the property. After the completion of such a map, it should be made the beginning of another, and in most cases a far more important, undertaking, namely, its utilization as -a starting-point for a complete inventory of the company's underground possessions. The ordinary mine-survey map, being nothing but a record of what has been done, is, in one sense, only ancient history. To increase its value, such additions should be made as will render it a complete statement of the amount and value of ore in sight at any particular time, and a guide for future develop¬ments. Comparatively little extra labor is involved in this undertaking, since the larger and most expensive part of the work has already been completed when the mine has been surveyed and mapped. The necessary additions consist in working out, and platting on the maps, the geology of the mine as exposed in the workings, in such a manner that the geological survey may be of daily use in the development and operation of the mine. The first step towards the production of a geological map consists in tracing individual level-sheets from the general or composite map. The area to be included, outside of the property in question, will depend very much on local conditions; but, for geological, legal and commercial reasons, it should be extended as far as reasonably practicable. The scale to be

Sep 1, 1905

By V. H. Wilhelm

WITH rapidly diminishing oil reserves: a great percentage of which are uneconomical at present prices, some of the existing methods of development and production will have to undergo radical re- visions to meet the changes continually taking place in the petroleum industry. Imagination in an engineer is a great asset. The fancy of today is found to be the realization of tomorrow, and with this thought in mind, there is here presented a more or less imaginative picture which, to my mind, has a meritorious basis. Directed drilling has reached a stage of accuracy sufficient to allow the prediction that this art will be used in the future development of oil structures, especially those \\,it11 thin sand bodies 'and steep dips. Directional drilling in a number of fields in California has gratifying results. Wells which practically laid pipe lines through the oil sands have enjoyed a greater drainage radius with a consequent greater initial and cumulative production. In one field where the vertical thickness of sands was approximately 550 ft., wells drifting at an angle as great as 55 deg. fro111 vertical had over 1100 ft. of perforated pipe in contact with these sands. These wells were, and are, remarkable for their great initial pro-

Jan 1, 1936

By E. R. Kaiser

COAL research during 1942 was directed in an important degree toward the solution of problems of wartime importance. A wider selection of coals for carbonization to meet the increased demand for coke, and the improved utilization of lower-grade coals for boiler fuel were made possible by fundamental studies on cod and ash behavior that had been started several years ago. The coal industry's interest in the work of the various laboratories brightened significantly as results were demonstrated on smokeless combustion in stoves, on stokers without coke trees, and on pulverized firing of forge furnaces. Despite the limitations of priorities and scarcity of materials, the mineral industries building of the West Virginia University was completed and equipped with facilities for research on coal min

Jan 1, 1943

By J. P. BONARDI, William F. Boericke

BOULDER COUNTY, Colorado, ranked during the war years and until the end of 1918 as one of the foremost tungsten-producing districts of the world. In 1919 production fell off drastically, due to heavy importations of foreign ores from China, Burma and South America. So large were the imports that even after the enactment of a protective tariff in 1922 of 45c. per lb. on tungsten metal, equivalent to $7.14 per unit (201b.) of tungstic acid? (WO,), the stocks of metal in this country were extensive enough to supply the demands of industry, and prevent general resumption of mining by domestic producers. Even today there are only two producers in the Boulder district though at one time as many as twenty separate companies were in operation. About the same ratio holds for other tungsten-producing districts in the country, including California and Nevada. Total consumption of tungsten concentrate in terms of 60 per cent WO2 in the United States amounted to approximately 3790 tons in 1928, according to Frank L. Hess.' Of this amount, domestic mines contributed 1290 tons, and the rest, 2500 tons, was imported. Yet in 1917, with tungsten concentrate selling at $20 per unit, the Boulder district alone produced 2707 tons, indicating the effect of enhanced ore price upon production. It is believed by American tungsten miners that, given a sufficiently high tariff, all the demands of industry can be met by domestic production without placing a prohibitive burden on consumers. For instance, in steel manufacturing the percentage of tungsten entering into the manufacture is so small that, ?regardless of cost, it can constitute but a small fraction of the cost of steel to the buyer.

Jan 1, 1929

By R. H. Coats

MINING occupies a position of less importance than manufacturing or agriculture in Canada, but its relative contribution has increased greatly during the post- war period. Mineral production was only 5.14 per cent of the net value I of production of all kinds of commodities in 1919, but by 1936 the pro- portion had risen steadily to 12.76 per cent. Mining felt the depression, hut unlike agriculture, which is still ' sorely stricken, it has passed from early convalescence to complete recovery. For each of the last two years new high records were established for the industry as a whole and for the quantity of most metals produced. Mining has had a notable effect on - the growth of the power industry in Canada. Water power has been developed in the same or adjacent areas wherever mining camps have been 1 established, with few exceptions. Consumption of electrical energy by the mining industry gained 72 per cent within a decade, rising from 1604 million kw.-hr. in 1926 to 2754 in 1935. In. 1935 alone the mining industry purchased electric power

Jan 1, 1937

By AIME AIME

THE 1941 fall meeting of the Iron and Steel and the Institute- of Metal, Division held at the Ritz-Carlton Hotel, Philadelphia, during the first three days (Oct. 20-22) of the National Metal Congress was well attended as usual, and the seven technical sessions and the joint round table on order-disorder transformations were this year of considerably more than routine interest. Despite unseasonably warm weather, a scarcity of hotels (there were rumors, apparently well-founded, that , some of the metal man attending the Congress had to stay in tourist camp), and a multiplicity of technical and other ions of the co-operating societies that gave the Congress this year the general air of a three-ring circus the A.I.M.E. sessions attracted audiences that ragged from seventy or eighty up to 350

Jan 1, 1941

By E. J. KENNEDY

THE annual dinner-dance was held in the large ball room of the Commodore hotel Wednesday evening. A total of 577 were seated at the dinner, over which President Eavenson presided as chairman and toastmaster. In introducing George C. Stone, the James Douglas Medalist, W. R. Ingalls outlined the former's association with the zinc industry. He said, in part In designing and building Palmerton, Stone erected a metallurgical monument and won the title of chief engineer of the New Jersey Zinc Co., with transferal to its New York office in 1900. There lie held forth in dignity, efficiency, and with appreciation until his retirement from active service in 1929. After a few years lie was diverted from the position of chief engineer for his company to the superior one of chief metallurgist and that gave to Stone his next big chance.... This was the conception of a research department and the ability to persuade his directors to adopt it. I shall not pretend to summarize the great things that afterward developed. I shall mention only the institution of the manufacture of lithopone in this country, the charging of the Wetherill furnace with briquets, the mechanicalization of the Wetherills, the accomplishment of continuous distilling, and most recently the introduction of reflux-refining.

Jan 1, 1935

By Frank J. Tolonen

BENEFICIATION of iron-bearing formations is one of the major problems of research at the Michigan College of Mining arid Technology. Funds for this purpose hate been supplied by the State of Michigan supplemented by contributions of labor and some supplies from the Federal Government during the depression. The iron-mining companies have cooperated in securing samples and have also furnished much valuable information relative to the various formations.

Jan 1, 1937

By PHILIP N. MOORE

PHILIP NORTH MOORE was born on July 8, 1849, at Connersville, Ind. His father, a civil engineer, was descended from Henry Moore who came from Ireland in 1773 to live in Washington, Pa. Through his mother, Philip Moore was descended from John North, who came to America in 1635 and settled in Connecticut. The story of Mr. Moore's life as told by himself is given on pages 373-386 of T. A. Rickard's "Interviews with Mining Engineers." He studied at Miami University, where he gained the degree of A.B. in 1870, and A.M. in 1873. In 1920 his alma muter conferred on him the honorary degree of LL.D. He, as a special student, was a member of the class of 1872 at the School of Mines of Columbia University.

Jan 1, 1930

By Sherwin F. Kelly

THE joint meetings of the Mining Geology Committee and the Society of Economic Geologists proved to be deservedly popular, and the interesting papers drew an attendance which strained the capacity of one of the large meeting rooms.. As might be expected these days when even the Supreme Court can't keep away from the subject of gold, the discussions opened on Thursday morning with several papers devoted to questions of structural and mineralogical relationships of the deposits of this metal. The presentation of Ira B. Joralemon's paper, "Veins and Faults in the Bralorne Mine," by Reno Sales, elicited considerable discussion on the relation of mariposite to gold, and the situation of the gold deposits with respect -to the Coast Range batholith. H. V. Warren stated that lie had observed mariposite always to be associated with gold in this region, but that gold was not always associated with mariposite. He pointed out that there is a series of veins on the west side of the batholith with a different mineralogy that, because of their richness but small size could quite easily make good, small mines. John A. Dresser concurred in this, and said lie thought this region was one of great promise for the mining geologist. He also reported having found mariposite associated with gold values below commercial limits, in the Appalachian regions.

Jan 1, 1935

By A. H. Smallbone, R. Lathe

Considerable efforts have been expended to apply multiple regression techniques to quantitative determinations in x-ray fluorescence analysis. Multiple regression has been shown to be an effective method for correlating x-ray fluorescence intensities to elemental concentrations. Although many other techniques have been devised to solve the problem of matrix effects in x-ray fluorescence analysis, there are few as efficient in terms of storage requirement or ease of programming for digital computers as the multiple regression method. In the case of ore slurry, it has the additional advantage of allowing a unified approach to the problems of slurry density correction and matrix effect corrections. The data used in the present work were obtained with an on-stream x-ray analyzer capable of analyzing 15 slurry streams for as many as nine elements simultaneously. One of its fixed monochromators was set to accept scattered radiation at a discretely selected wavelength as a means of monitoring the slurry's pulp density. The data were reduced to obtain the correlation equations and a computer program combining slurry density with matrix corrections was written in FORTRAN IV to calculate concentrations.

Jan 8, 1969

By Charles A. Thomson

RECENTLY a prominent Brazilian' doctor wrote to an American friend: "I feel that cultural relations between the American and Brazilian people could be promoted in a very speedy and effective way by establishing contacts between men of the same professions. . . . A Brazilian mechanical engineer could be immediately interested in relations with American colleagues, even if he had never heard of Longfellow and was not interested in Stokowski's orchestra. . . . A large number of cultural ties could be established between specific groups of men who have already some common interest, and who, whenever they meet, can do something that naturally brings them closer, that is, `talk shop."' In appointing a committee on Inter-American Engineering Relations to cooperate with the Department of State in its program of fostering cultural relations with the other republics of this hemisphere, the American Engineering Council has taken a step which should lead to a greater sense of unity and fraternity among engineers of the Americas. That such unity and fraternity are part and parcel of the moral defense of the hemisphere is obvious. For years engineers of the United States have been traveling South and South-east to construct roads and bridges, dam rivers, harness waterfalls, build ports, install and operate mining equipment, and erect buildings and plants, often at the risk of life. Those in the teaching profession in this country have had as pupils a growing number of students from our neighboring republics whom they have sent back home trained in the most efficient engineering methods. In a sense, however, these relations with the other nations on this side of the globe have been haphazard and left to chance. Personal acquaintance among engineers has played its role but no organized attempt appears to have been made to take advantage of the natural relationship which geographical and historical factors should encourage.

Jan 1, 1940

By C. E. BOCKUSD

WHEN Mr. Bain asked me to lunch with you he requested that I say a few words as to how the Institute could be helpful to the bituminous coal industry. I feel like saying, "Thank you, what have you?" I do not want to trace in detail the story that is old already to many of you. On the other hand it does take some little stage-setting to illustrate what is the matter in the bituminous coal industry, a trouble that must some day be cured. There has been something over a century of bituminous coal production as a real business in this country. True, Joliet and Marquette discovered coal in Illinois in 1673, according to published accounts of their travels, and shortly thereafter Father Hennepin also found Illinois coal in 1689. Coal was mined near Richmond in 1750, and Richmond shipped coal to New York and Philadelphia in 1789. But it was not until 1838 that the production of bituminous coal in this country totaled a yearly output equal to the minimum for one class A mine today, for that was the first year that production exceeded 200,000 tons.

Jan 1, 1930