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By Erhard Hornbogen

Twins were propagated into large, well-annealed crystals of a, iron-phosphorous and a, iron-molybdenum solid solutions. Strain fields caused by interaction of these twins were made visible by precipitation. These strain fields can be explained by assuming that transmitted and reflected plastic waves are created when a twin strikes an obstacle with high velocity. The twin front itself can be regarded as a shear wave that may be able to develop a one-dimensional shock front. The occurrence of {WO} fracture by the reflected stress is also discussed. The described effects were not found when twins propagated at lout velocity into disturbed crystals, for example, into crystals previously deformed by slip. DEFORMATION twinning leads to shearing of a crystal lattice under external load. The shear appears to be homogeneous over a large number of crystal layers. In a iron, shear occurs on the (112) planes and in the <1ll> directions. The formation of a twin proceeds by the movement of partial dislocations that change the stacking at the twinning plane.l, In the bcc lattice, this partial dislocation can be created by dissociation of a sessile a/2[111] dislocation that lies in the (112) plane: Cottrell and Bilby&apos;s spiral mechanism can explain the homogeneous shear, but has not been proven experimentally. Nevertheless, this mechanism can explain the possible high velocity of formation of a twin. In Cottrell and Bilby&apos;s model, as in other models of twinning or phase transformation, a much higher energy is required to spread the first stacking fault than to add new layers by further movement of the partial dislocations. The dislocations will therefore become accelerated proportional to the difference between the stress, tN, to nucleate and tp to propagate the twin. It has been assumed3,4 that tn is the stress required to make two partial dislocations of apposite sign pass for the first time. After the first layer of new stacking has been formed, the maximum stress is TN=Gb/4pd where G is the shear modulus, b is the Burgers vector of the partial dislocation, and d is their perpendicular spacing so that the amount of shear is S = b/d. From this formula, a value of 25 kg per mm2 has been estimated for twinning in Zn3. The measured values are smaller, but local internal stresses may help to provide the necessary stress. For a iron, a higher value can be expected, mainly due to the higher value of G. That agrees with the observation that "burst" twinning occurs if the yield strength is in-

Jan 1, 1962

By Reinhardt Thiessen

IN THE general study of coal, all evidence points in the one direction -that coals had their origin in a manner analogous to that of peat. The best method of studying coal, whether it concerns its chemistry, composition, or physical condition, is to study peat. The essentials in a study of peat are a knowledge of the chemistry of plants, knowledge of decay and of the transformation process of plant-substances into peat. A number of facts must be emphasized, namely, (1) peat is formed under wet conditions only; (2) plants grow in the place where peat is formed; (3) all the plant substances go into the bog; and (4) all the plant substances are subjected to a series of phases of decay which are (a) in the air completely above the water level but in relatively moist conditions; (b) above the water level, but covered by debris; and (c) completely submerged by both water and debris.

Jan 3, 1925

By F. H. Buttner, E. R. Funk, H. Udin

A. P. Greenough (University College, swansea, Great Britain)—I have recently made some experiments on the deformation of silver wire at high temperature in an atmosphere of oxygen-free nitrogen. The observa-tions which 1 made confirm the main conclusion of this paper, that the most satisfactory mechanism so far suggested to explain the deformation which takes place

Jan 1, 1953

By Harold M. Mooney

WHEN apparent resistivity data are taken with the symmetrical Wenner 4-electrode spread, a fixed center position is used and readings are taken for values of electrode separation. Basic data consist of apparent resistivity plotted against separation of adjacent electrodes. The interpreter attempts to infer geologic structure, such as the depth to discontinuities and the nature of subsurface earth materials. An earlier paper1 described methods for interpreting resistivity data. All of these involve a severe assumption, namely that the earth in the region of interest consists of horizontal layers, electrically homogeneous and isotropic. The actual earth never satisfies this assumption exactly and may deviate from it so much that none of the above methods can be applied. Attempts in three directions have been made to modify the assumption so that it approaches known geologic complexity more closely.

Jan 12, 1954

By A. B. Kinzel

IT is with sincere appreciation and a deep sense of responsibility that I accept the honor of delivering the Howe Memorial Lecture. In our time metallurgical research has delved into phenomena ever more complex in character, so that much of this work must be done by organized teams. We, of the Union Carbide and Carbon Research Laboratories and the Electro Metallurgical Co., are truly a team and the lecture which is to follow is due largely to a few of the outstanding members of that team here cited and well known to you in their own right: John Lamont, whose work deserves special recognition, Walter Crafts, William Forgeng, William Binder, Robert Fowler, and David Swan. Thus it is a fitting pleasure to accept this honor for the research institution which I represent. Henry Marion Howe was truly inspirational and his breadth of view was such that he could use either the method of rigid proof or implied mechanism to further the broad understanding. But perhaps his outstanding characteristic was his sound judgment and his ability to weigh observations. The following is replete with observations and judgment as to their implication. We would like to feel that it is the type of dissertation which Howe, himself, would have enjoyed. Chromium carbides in stainless steel have, in a sense, been a key to the progress of the stainless steel industry. Brearley&apos;s first stainless steel, containing approximately 0.30 pct C, was successful because it differed from previous Fe-Cr alloys in that the carbides were present in such amount and form as to provide the stainless and cutting properties. Again, the 12 pct Cr die steels with a carbon content of 1.5 pct or more achieved their properties by virtue of the form and distribution of the chromium carbides. In the straight chromium steels with from 12 to 25 pct Cr, chromium carbide amount and distribution are once more the determinants with respect to physical properties and corrosion resistance. In each of the cases just cited the role of the carbide is in essence similar to that of iron carbide in carbon steel and this story is so well known that we need not dwell on it. In the austenitic stainless steels, the chromium carbide plays only a minor positive role with respect to mechanical properties, and for corrosion resistance the objective is to achieve maximum homogeneity. Thus the tendency has been to ever lower the carbon and correlatively the chromium carbide content of the austenitic steels. Today stainless steels with carbon less than 0.03 pct are beginning to find their true place, and this is being aided in major degree by our Company&apos;s introduction of a new type of ferrochromium having negligible carbon. The role of carbon in these austenitic steels has long been recognized, and a truly enormous amount of research has been devoted to the subject. Much has been learned about corrosion resistance, but the attack on the problem from the point of view of carbide precipitation and the nature thereof has left much to be understood. Because of its fundamental importance to the future of stainless steels, further study of the mechanism of carbide formation in austenitic steels is of interest. In the 18-8 Cr-Ni steels, which are typical of the austenitic class of steel, carbon is soluble in the aus-tenite to the extent of approximately 0.15 pct at 1832°F (1000°C). The solubility becomes less with decreasing temperature, so that at 1652°F (900°C) the solubility limit is approximately 0.06 pct, at 1472°F (800°C) it is about 0.03 pct, and at 932°F (500°C) it is approximately 0.01 pct. Obviously this is the ideal situation for the classical precipitation phenomenon. It is true that, in a sense, 18-8 austenite resulting from annealing is in a metastable state, and the phenomenon of ferritic precipitation from this austenite should be considered. However, in a so-called fully austenitic 18-8 steel this is secondary with respect to the carbides and can be neglected. A wide variety of chromium carbides is known. Only one chromium carbide, Cr,,C,,, frequently referred to as Cr,C, has been found in unmodified low carbon 18-8 steel. This, fortunately, simplifies the study of the precipitation phenomena. For this study an A.I.S.I. type 304 stainless steel of commercial quality was selected. Analysis showed C 0.07 pct, Mn 0.49 pct, Si 0.33 pct, Ni 9.34 pct, Cr 18.91 pct, and N 0.033 pct. As expected with this composition the steel was homogeneous after annealing except for a few pools of ferrite, which were disregarded in that their location was not coincident with subsequent carbide precipitation areas. On corrosion testing the steel was normal and typical of good commercial quality. Specimens 1/2xlx4 in. were annealed and subjected to precipitation heat treatment for 100 hr at 100" temperature intervals from 1000° to 1500°F and for ten selected intervals ranging from 5 min to 64 hr at 1300°F. These blocks were then cut into small pieces for metallographic studies. The first problem

Jan 1, 1953

By Thomas V. Falkie

The use of operation research and computer techniques in the mineral industries continued to gain acceptance during 1966. There are generally at least five sources of information for researchers and practitioners in the field: (1) Technical periodicals like MINING ENGINEER- ING, Mining Congress Journal, etc. (2) Proceedings of the Symposium and Short Course on Computers and Operations Re- search in Mineral Industries, held last year at Penn. State University and jointly sponsored by the University of Arizona, Stanford University, Colorado School of Mines, Penn. State University and the Society of Mining Engineers of AIME. (3) Various local conferences, such as the 1966 Rocky Mountain Minerals Conference held in Denver. (4) United States Bureau of Mines publications. (5) The AIME annual meeting in New York and the SME Fall Meeting in Tampa.

Jan 2, 1967

Jan 1, 1904

By B. F. Bush

THE coal-fields of Missouri, situated hi the northern and western portion of the State, are distributed, in whole or in part, over 57 counties, embracing an area estimated by Mr. Broad-head to be practically 23,000 sq. miles, including small detached beds and outliers in St. Louis, St. Charles, Lincoln and Warren counties in the eastern part of the State. This area includes about 8,000 sq. miles of Upper or Barren Measures, 2,000 sq. miles of exposed Middle, and 12,420 sq. miles of exposed Lower Measures. In a general way, the Missouri coal-field is bounded on the east by an imaginary line entering the northern part of the State just east of the 92c1 Meridian and passing across the State in a southwesterly direction to a point on the Kansas-Missouri line a little below the southern boundary of Barton county. An important part of the field overlaps this line and extends down the northern side of the Missouri river, under¬lying the greater part of Randolph, Howard, Boone and Audrain counties. In all, 34 counties produced coal during the year 1903. Fig. 1 shows the position of the coal-fields in Missouri. GEOLOGICAL FEATURES. The Coal Measure formations, all of the Carboniferous age, rest unconformably upon the rocks of the sub-Carboniferous or Mississippian series, and, in some cases, upon the rocks of the Devonian and Silurian ages. From their outcrop on the eastern and southeastern borders of the field, the Measures dip west to northwest at the rate of 10 ft. per mile, reaching a maximum thickness estimated by

Jan 1, 1905

By Carl R. Christiansen, James J. Scott

Advance mine planning, coupled with good mining practice, can be employed to develop underground space in stone mines for future industrial usage. To assure the developer the maximum return on his investment, initial planning should consider all aspects of the commercial operation, including surface layout, mining, and underground industrialization. The modular concept of mining to compartmentalize the space offers several advantages over conventional methods. Some expenditures can be considered as mining costs with a reduction of profit from stone production while lowering the capital requirements for conversion for usable space.

Jan 1, 1977

By W. M. Rust, W. D. Mounce

THE almost universal acceptance of electrical logging by the petroleum industry calls for a critical examination of the physical bases of the common methods. This is particularly needed for the natural potential log. The conventional explanations are based on the phenomena of electrofiltration and electro-osmosis. However, experimental data show that they fail to give a basis that is quantitatively sound. Moreover, they lead to interpretations of details of electrical logs that are erroneous. It was found experimentally that when a plug of shale is placed in a chain of dissimilar electrolytes, a current flow results. Experiments on oil-well cores and fluids similar to those existing in wells show that potentials are set up which are in reasonable agreement with those encountered in electrical logging. Doubt- less other sources of potential are important but this explanation not only accounts for much of the potential but also clarifies some fairly familiar examples of misinterpretations.

Jan 1, 1944

By Barry S. Epstein

Financing the acquisition of a going coal mine operation has not had the exposure other finance-oriented projects have had. Therefore, C.I.T. feels that coal mining people and financial people should improve their understanding of the factors involved in this important type of acquisition. The discussion consists of two major subjects: analysis of the acquisition of the property, and sources and terms of funding the acquisition. Source and Terms of Funding There is a need to keep the competent medium-sized independent operator in the coal business, especially in these times of energy shortage. The creation of a resale market for coal mines encourages new investment in the coal mining business by medium-sized operators and their financial backers. Who provides debt and equity financing to acquire going coal mine operations and on what terms?

Jan 9, 1975

By Richard P. Rothwell

The anthracite coals of Pennsylvania are all mined from large veins. A seam less than four feet. in thickness is generally considered as unworkable, those from which most of the coal now comes being from 8 &apos;to 30 feet thick. The system of mining employed is, almost without exception, that known as " chamber and pillar work;" that is, the coal is taken out of chambers of from 18 to 30 feet in width, and pillars of from 12 to 20 feet are left between these to support the roof. In general, the entire thickness of the seam, even

By P. L. Russell

The use of nuclear explosives for excavation has been demonstrated to be feasible and practical. Application of nuclear explosives for overburden removal from large ore deposits appears to offer economic advantages over present methods, but under the present pricing schedule, high-yield devices must be used to obtain an economic advantage. The use of nuclear explosives presents problems not inherent in the use of conventional explosives, and thus they can be used only in areas where large explosions and associated phenomena can be tolerated. Stripping of coal with nuclear explosives does not appear practical at this time, but stripping overburden from copper or iron ore deposits may be a potential use. Even here, however, the use of nuclear explosives would require isolation, favorable topography, favorable ground-water conditions, and a low population density. If these basic requirements can be met, the use of nuclear explosives for overburden removal would offer both economic and time advantages. The possibility of using nuclear explosives for peaceful purposes was a subject for speculation as early as 1945. The PLOWSHARE Program was formally established by the AEC in June 1957 for the purpose of developing and demonstrating peaceful applications for nuclear explosives. The technical direction of the program is the responsibility of the Lawrence Radiation Laboratory, Livermore, Calif. Mining and excavation were two fields that received early consideration as areas in which nuclear explosives might be used. Knowledge gained from underground weapons testing increased this possibility, and the development of the thermonuclear device which has a small fission-to-fission ratio, reduced the hazard of radiation, and spurred interest. Nuclear explosives appear to have the greatest potential in the following mining operations: 1.— Surface Mining a) Stripping of waste for open-pit excavation b) Breaking of ore in open-pit mining c) Quarrying d) Blasting for production of aggregate, riprap, etc. 2. — Underground Mining a) Block caving application b) Crushing of ore for in-situ leaching, etc. c) Preparation of underground waste disposal areas Of the potential applications, excavation is perhaps the most obvious and the best understood, and probably the most practical for use in the near future. Large quantities of rock and earth can be moved by proper emplacement of nuclear explosives, but economic and practical relationship must be determined between the known capabilities of nuclear explosives and the required excavating to remove overburden. REMOVING OVERBURDEN IN OPEN-PIT MINING Removing the overburden is one of the largest jobs in open-pit mining. In 1960 open-pit mines produced approximately 130 million tons of coal, 108 million tons of copper ore, and 135 million tons of iron ore. To obtain this much production, an estimated 3-billion tons of overburden were removed from the coal, 216 million tons from the copper ore, and 135 million tons from the iron ore. These figures do not include the initial stripping required before ore production. For example, the ASARCO Mission mine started stripping operations in August 1959 and by mid-November 1961 had removed 46.3 million tons of material including 1.2 million tons of ore.* Initial excavation of this type offers the most favorable conditions for utilizing the earth-moving ability of nuclear explosives. EXPLOSIVE CASTING FOR REMOVING OVERBURDEN The use of explosives to remove overburden is not a new idea. Conventional explosives have been used for this purpose for many years with varying degrees of success. Several small coal strip operators have used this idea to increase production. At these mines about one-third or more of the overburden is thrown by explosives across the pit and onto spoil piles. The additional costs of drilling more blast holes and more explosives are more than compensated for by a reduction in the time required to uncover the coal, and by an increase in coal production.

Jan 1, 1964

By B. D. Cullity, A. Freda

It is well known that deformation by cold drawing or swaging produces a kind of preferred orientation called fiber texture in metal wires. Such textures have been extensively studied by means of X-ray diffraction, chiefly by techniques in which the diffracted X-rays are recorded photographically. This paper describes some results obtained with a new method, involving the use of a diffractometer. X-RAY METHOD Since the pole figure of a material having a fiber texture is symmetrical about the fiber axis, there is no need to present the entire pole figure. Instead, texture data can be summarized by means of a curve showing the variation of pole density along any meridian of the pole figure, if the north-south axis of the latter is made parallel to the fiber axis. The position of a pole on the meridian is specified by the angle 9 between the pole and the fiber axis (wire axis). The X-ray method1 used here to measure pole density as a function of 9 actually consists of two methods, referred to as A and B. In method a, X-rays are reflected from the wire surface. Pole densities can be measured by this method from O = 90 deg down to a limiting value which is dependent on the Bragg angle 8 and is typically of the order of 30 to 40 deg. Method B involves diffraction from the wire cross section and covers a range of 0 values from 0 up to an angle sufficient to overlap the measurements made by method A. By a combination of the two methods, a complete pole-density curve can be obtained. However, method A alone, which requires no specimen preparation other than etching, can often reveal enough of the pole-density curve to provide complete information about texture components. Both methods require that the measured diffracted intensities be corrected for changes in absorption and diffracting volume with changes in 9. A11 intensities I reported in this paper are corrected diffracted intensities; they are propor-

Jan 1, 1960

By Francis L. Vinton

THE eccentric theodolite I exhibit is one constructed by the Stack-poles of New York, from drawings, considerably modified, of Combes&apos;s theodolite. The telescope is on one side of the horizontal limb, and the vertical circle is opposite to the telescope; thus they nearly balance each other, making already the construction lighter than in the instrument of Combes, where the telescope and vertical circle are together on the same side, and are both balanced by a considerable weight. The instrument stands upon three levelling screws or feet, an improvement upon the old or general style of mounting a transit on four feet-for indeed the instrument is easier levelled, and, more-over, stands more stable on three than on four points of support. The general advantage of an eccentric theodolite is evident, namely, that it can measure any and all vertical angles, from 0 to 360, without being interfered with by the horizontal limb as is the transit; besides this advantage, it needs no preparatory adjustment or correction for eccentricity ; on the other hand, however, that correction

Jan 1, 1873

By M. J. Humenick, K. Garwacka

A laboratory experimental research project was conducted to evaluate the use of chlorine for the oxidative destruction of residual ammonia that may remain in ground water after in-situ uranium solution mining operations. The work tested the idea of injecting high strength calcium hypochlorite solution into the mining zone to convert ammonia to nitrogen gas as a final cleanup process for ammonia removal from the ground water system. This paper details ammonia removal efficiency as a function of chlorine dose, reactant, and product material balances, and how the concept may be used as a final ground water restoration process.

Jan 1, 1985

By Thomas E. Ban, Charles D. Thompson, Charles A. Czako

Continuous sintering-a metallurgical process for more than 50 years-has broadened from its origin in nonferrous metallurgy to present-day applications in ferrous, chemical, and nonmetallic fields. During the past year, self-fluxing sinter production has been a subject of active interest to iron metallurgists in North America. Accomplishments however, have come predominantly from Europe and proper interpretation of these reports requires an understanding of European raw materials and European economics. The technology, of course, can be applied universally.

Jan 10, 1959

By Francis L. Vinton

THE eccentric theodolite I exhibit is one constructed by the Stack poles of New York, from drawings, considerably modified, of Combes&apos;s theodolite. The telescope is on one side of the horizontal limb, and the vertical circle is opposite to the telescope ; thus they nearly balance each other, making already the construction lighter than in the instrument of Combes, where the telescope and vertical circle are together on the same side, and are both balanced by a considerable weight. The instrument stands upon three levelling screws or feet, an improvement upon the old or general style of mounting a transit on four feet for indeed the instrument is easier levelled, and, moreover, stands more stable on three than on four points of support. The general advantage of an eccentric theodolite is evident, namely, that it can measure Any and all vertical angles, from 0 to 360, without being interfered with by the horizontal limb as is the transit; besides this advantage, it needs no preparatory adjustment or correction for eccentricity; on the other hand, however, that correction

Jan 1, 1909

By E. M. MacKevett

The only source of uranium ore in Alaska that has been mined commercially is the Ross-Adams de- posit, a gently inclined, fusiform orebody in alkali granite in which uranothorite and uranoan thorianlte are the chief ore minerals. In mode of occurrence, apparent genetic association with the granite, and to a lesser extent in mineralogy, this type of deposit is uncommon. The mine is in the southern part of Prince of Wales Island (Fig. 1) at an altitude of about 950 ft on the southeast flank of Bokan Mountain. A steep unpaved road 1 ¾ miles long leads to the dock on the West Arm of Kendrick Bay, which can be reached by boat or seaplane from Ketchikan, some 35 miles to the northeast.

Jan 9, 1959