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By James G. Blaine, David A. Summers, L. John Tyler

There has been a considerable amount of research developed which shows that the close contour cutting of an excavation prior to removal of the central core will increase ground stability while concommitantly, reducing the number and size of blastholes required to create the excavation. To date, the industrial development of this technique has however, centered on the development of equipment based on simple cutter movement and mechanical rock cutting. The advent of reliable field operable high pressure waterjet cutting equipment with the very low reactive force required to hold the head in position has opened the way for a much smaller and more manueverable system. The advent of small, micro-computers allows the programming of accurate profiles for cutting tools on excavation equipment. The combination of these two technologies will allow the generation of complex as well as simple, excavation profiles and lead to the potential pre-support of the opening before major excavation is completed. A brief description of the necessary components and their functions is encorporated in the initial prototype design as given.

Jan 1, 1984

By W. A. Hockings, M. E. Volin, A. L. Mular

Batch grinding tests at short times were made in a laboratory rod mill with 10 x 14 mesh quartzite in corn syrup-water mixtures of varying viscosity. The weight fraction broken and size modulus were found to be independent of viscosity up to 20 cp, but at higher viscosities breakage of the feed decreased while the size modulus increased. The mechanisms of the effect of viscosity are discussed on the basis of particle dynamics. The effect of viscosity of the suspending medium on grinding has not been accorded much attention, although both wet and dry grinding are used in bene-ficiation processes and the viscosities of water and air differ greatly. schweyerl investigated the rates of grinding of quartzite in a pebble mill with air, water and glycerol as the suspending media and found the rate in terms of new surface developed per thousand revolutions of the mill to be constant and dependent on viscosity up to 20,000 rev, but to decrease and become independent of viscosity for longer grinding times. Based on considerations of the drag forces exerted on suspended particles and on the grinding media under turbulent and laminar flow conditions, viscosity can be expected to inhibit the rate of grinding in a given system as it changes the flow conditions from turbulent to laminar. The objective of this study was to determine the effect of viscosity of the suspending fluid in the batch grinding of a homogeneous feed of uniform size for short residence times, a region of more practical interest than the long times investigated by Schweyer. In actual grinding operations, the viscosity of the fluid does not change, but the consistency (apparent viscosity) of the pulp increases with additions of fines. In this study the consistency of the pulp was not measured because it was thought that the grinding times were too short to alter the apparent viscosity appreciably.* *Minus 200 mesh quartz at 65% solids has an apparent viscosity of about 25 cp as measured by a simple consistometer. Personal communication from D. F. Kelsall to A. L. Mular. For the purposes of this study, the effect of viscosity on grinding can be shown sufficiently well on the basis of the cumulative weight fraction finer than the feed size at any time, and the size modulus, ku, of the finer than feed sizes. The parameter, ku, is obtained from a form of the Gaudin-Schuhmann equation. METHOD AND MATERIAL The grinding tests were accomplished in a laboratory rod mill 10-1/2 in. long and 8 in. bore with a 20-lb rod charge consisting of two 1-in., eight 3/4-in., eight 1/2-in., and eight 1/4-in. diam rods. The mill speed was 43.2 rpm. Charges of 400 g 10 x 14 mesh Wisconsin quartzite** were ground for times of 60, **Courtesy of Minnesota Mining and Mfg. Co. 120, 180 and 240 sec in 500 cc of fluid made up of corn syrup and water in measured proportions. The temperature of the pulp was measured immediately upon completion of grinding, and the size distribution of the quartzite was determined by a wash-wet-dry screening technique. Corn syrup was chosen because of its high viscosity and ideal viscous behavior, and also because its density is not greatly different from that of water. The viscosity of each fluid mixture was measured with an Ostwald viscometer at 25 C. and a correction was made for the temperature of the pulp according to tabulated values for sucrose solutions. The density differences were so small that they probably did not significantly affect breakage. RESULTS AND DISCUSSION The conditions of the grinding tests, computed viscosities, weight fractions finer than the feed size and values of a and ku are listed in Table I. The values of a and ku were taken from the linear portions of the log-log plots of cumulative weight fraction finer vs size for the various grinding times. The plots for tests in fluids of average viscosity 8.6 cp are shown in Fig. 1. In general all of the sets of curves were linear throughout most of the size

Jan 1, 1965

By Harrison R. Cooper

The key to concentrator automation is practical means for obtaining continuous assay data from concentrator streams. The technique most successfully used is x-ray fluorescence analysis. The practical reality of on-stream x-ray analysis has been achieved through effort over the past twenty years, marked by an occasional breakthrough, but more typically a step-by-step development to which many individuals and organizations have contributed. The net result of this progress is the present capability to install on-stream x-ray analyzer systems on a turn-key basis. It is now possible to provide all components of an x-ray analysis system as a completely engineered unit which can be put into immediate use, minimizing needs for specialized application knowledge to benefit from continuous assaying in process control. The economic factors which influence the choice of system and limitations of the x-ray fluorescence technique for slurry analysis are reviewed.

Jan 1, 1976

By Meng-Cherng Sun, Fun-Den Wang, David M. Ropchan

A proposed technique for improving coal-mine roof stability by softening parts of coal pillars along the sides of entries developed from structural analysis is presented. This technique is based on the transference of the high stress concentration in the roof near the upper corners of a rectangular opening to the roof rock and coal over the solid away from the opening. This transferral is accomplished by softening parts of the coal pillars by drilling a series of parallel holes into the coal in the ribs and face of the entry prior to advance. The effectiveness of the pillar softening in terms of reducing the opening width (so that the stress in the roof near the corner is equivalent to that of a narrower opening) ranges from 3 to 5 ft for a 16-ft entry using a series of 4 to 5-ft-deep parallel drill holes of 3 to 6-in.-diam on a 1 to 2-ft spacing for a particular geology. Pillar softening should be highly effective in controlling roof where cutter-roof cave conditions exist, because this technique reduces the high stress concentration in the roof at the upper corners of the opening. It may also be effective for reducing tensile roof failure and coal rib sloughing for certain specific geological conditions. This technique appears to be a simple, effective, and practical method that can be used to supplement conventional roof support methods of roof bolting, timbering, roof truss, and other existing methods in underground coal mines. The authors consider the technique feasible and believe that it merits underground trials.

Jan 1, 1975

By J. E. Warren, J. H. Hartsock

Because of the extensive utilization of hydraulic fracturing for the stimulation of low-productivity wells, the two related problems of fracture design and evaluation have become economically significant and, as a consequence, helve motivated this investigation. The producing characteristics of horizontally fractured wells were studied to determine the fracture configuration that should be employed as the basis for the design of the treatment and to develop a method that can be used to establish the degree to which the design objectives have been achieved. The equations which describe the steady-state flow of a single-phase fluid into, and through. a finite-capacity fracture were solved numerically for an idealized reservoir-fracture model. The numerical results were used to obtain an apparent skin effect for each combination of the parameters considered. Based on the computed results, subject to the limitcitions implied by the assumptions that were made, the following general conclusions were drawn. 1. For a radius of drainage at least four times us large as the radius of the fracture, an apparent skin effect that is independent of the radius of drainage can be calculated. 2. The productivity of the hydraulically fractured system, relative to that of the unfructured well, can be determined from the apparent skin effect and can be used to establish design objectives. 3. In the evaluation of a fracture job, it is not Possible to determine both the radius of the fracture and its flow capacity uniquely from the apparent skin effect; an independent determination of one of the quantities is necessary. lNTRODUCTION Although hydraulic fracturing has been employed as a method for stimulating the productivity of literally hundreds of thousands of wells during the past 10 years, it is only in the last few years that improvements in fracture design1-6 and fracturing technique' have combined to increase the probability of obtaining a successful treatment to such an extent that the mechanics of the method may be considered to be standardized. From an economic point of view, however, two related questions must be satisfactorily answered before hydraulic fracturing can be used in the most profitable manner. The two questions are the following. I. For a particular well in a given formation, what are the optimum design specifications for the fracture treatment? 2. Have the design objectives been achieved by the fracture treatment? The significance of these questions has been recoguized, and some attempts to obtain answers have been made. Howard, et al,8 endeavored to determine the optimum treatment, based on maximizing profits, for any given formation; unfortunately, this work was based on a crude method for approximating the productivity of a well. Carter and Tracy9 utilized the same approximation to study the effect of fracturing on the behavior of a well producing by virtue of a solution-gas drive. Electrolytic models were used by van Poollen10 to investigate the variation in productivity due to fracturing; however, only a limited number of results were presented. Later, from the same model results, van Poollen, et al,11 attempted to justify an approximate expression for determining the productivity of a fractured well. It is quite apparent that there is a definite lack of the practical information necessary for specifying the optimum fracture configuration to be considered for design purposes. The only detailed attempt to develop a procedure for evaluating the result of a given fracture treatment appears to be that of van Dam and Horner.12 These authors described a technique for analyzing pressure build-down data, obtained immediately after fracturing, to determine the final fracture volume, the final fracture porosity, the fracture area, the fracture thickness and the in situ fluid loss of the fracturing fluid. While this approach should be useful whenever acceptable pressure measurements are available, it does not yield a value for the flow capacity of the fracture. Since the problems of fracture design and evaluation are inversely related, it should be sufficient to study the effect of the fracture configuration on the performance of a well. The primary objective of this investigation is to evolve a technique for computing the desired solutions. The secondary objective is to analyze these computed results in order to prescribe a method for evaluating fracture treatments. Because this study is exploratory in nature, its scope

By M. F. Hawkes

Austenite grain size has long been recognized by metallurgists as an important property of steels because of its influence on toughness, hardenability, ma-chinability and creep strength. Much research has been carried out on wrought steels to develop methods for disclosing austenite grain size, and to, provide knowledge of the grain-size characteristics of steels produced and heat-treated in various ways. Much less work in these fields has been done on steel castings; partly because, owing to the variable and complex microstruc-tures of cast steels, it is frequently very difficult to obtain results that are not questionable. The object of this investigation, therefore, was to establish, for a wide variety of carbon and alloy cast steels, suitable methods for disclosing austenite grain size and some knowledge of the grain-size variations to be expected. The steel foundryman is interested in austenite grain size at two different stages in the manufacture of his products; one is just after the steel is cast, and the other is after any reheating operation carried out above the critical temperature range. In both, it must always be kept in mind that the grain size being sought is actually a previous austenite grain size, and that the austenite no longer exists once the steel has cooled to room temperature. The prob-lem of the investigator is always to use evidence obtained from the structure at room temperature to deduce this previous austenite grain size, which was established the last time the steel existed at a temperature above the critical range. Since most steel castings today are at least annealed or normalized, the measurement of austenite grain size established by heat-treatment will he considered first. More than 50 commercially produced cast steels rcpresenting a wide variety of compositions and melting practices were used in the study. For each steel, grain-size determinations were made after each of three widely varying heat-treating schedules namely, one hour at I550'F, one hour at I700°F, and six hours at 1700 F. The list of steels and results obtained on them will be found in the appendix. (See page 530.) A discussion of the knowledge gained on the applicability of various test methods and on grain-size characteristics of cast steels in general follows. MEASUREMENT OF AUSTENITE GRAIN SIZE ESTABLISHED BY HEAT TREATMENT Methods Suitable foR Determining Austenite Grain Size after Heat-treatment at Ordinary Temperatures and Times It was desired, as one of the results of this investigation, to be able to recommend to steel foundries a method, or methods, of disclosing grain size best suited to accurate

Jan 1, 1948

By M. F. Hawkes

Austenite grain size has long been recognized by metallurgists as an important property of steels because of its influence on toughness, hardenability, ma-chinability and creep strength. Much research has been carried out on wrought steels to develop methods for disclosing austenite grain size, and to, provide knowledge of the grain-size characteristics of steels produced and heat-treated in various ways. Much less work in these fields has been done on steel castings; partly because, owing to the variable and complex microstruc-tures of cast steels, it is frequently very difficult to obtain results that are not questionable. The object of this investigation, therefore, was to establish, for a wide variety of carbon and alloy cast steels, suitable methods for disclosing austenite grain size and some knowledge of the grain-size variations to be expected. The steel foundryman is interested in austenite grain size at two different stages in the manufacture of his products; one is just after the steel is cast, and the other is after any reheating operation carried out above the critical temperature range. In both, it must always be kept in mind that the grain size being sought is actually a previous austenite grain size, and that the austenite no longer exists once the steel has cooled to room temperature. The prob-lem of the investigator is always to use evidence obtained from the structure at room temperature to deduce this previous austenite grain size, which was established the last time the steel existed at a temperature above the critical range. Since most steel castings today are at least annealed or normalized, the measurement of austenite grain size established by heat-treatment will he considered first. More than 50 commercially produced cast steels rcpresenting a wide variety of compositions and melting practices were used in the study. For each steel, grain-size determinations were made after each of three widely varying heat-treating schedules namely, one hour at I550'F, one hour at I700°F, and six hours at 1700 F. The list of steels and results obtained on them will be found in the appendix. (See page 530.) A discussion of the knowledge gained on the applicability of various test methods and on grain-size characteristics of cast steels in general follows. MEASUREMENT OF AUSTENITE GRAIN SIZE ESTABLISHED BY HEAT TREATMENT Methods Suitable foR Determining Austenite Grain Size after Heat-treatment at Ordinary Temperatures and Times It was desired, as one of the results of this investigation, to be able to recommend to steel foundries a method, or methods, of disclosing grain size best suited to accurate

Jan 1, 1948

By L. L. McMurray

ILMENITE is the most important raw material for manufacture of titanium dioxide.1 Industrially, several other products are made from ilmenite, the most important of which are: ferrotitanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic production of ilmenite has here-tofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent Ti02 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in Caldwell County, North Carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent Ti02 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.4 It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, 02, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus 150-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. THE ORE Five samples of ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: I. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1944

By L. L. McMurray

Ilmenite is the most important raw material for manufacture of titanium dioxide.' Industrially, several other products are made from ilmenite, the most important of which are: ferro titanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic produttion of ilmenite has heretofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent TiO2 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in caldwell county, North carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent TiO2 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.' It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, O2, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus Iso-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. The Ore Five samples of Ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: 1. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1948

By L. L. McMurray

Ilmenite is the most important raw material for manufacture of titanium dioxide.' Industrially, several other products are made from ilmenite, the most important of which are: ferro titanium, ferro carbon-titanium, copper-titanium, titanium carbide and titanium nitride. The production of titanium metal is still in the laboratory stage because of the difficulty of extraction and as yet no important application for the metal has been found. Ilmenite has received considerable attention as an industrial raw material. Imports of ilmenite concentrates for the first nine months of 1941 were 156,737 short tons, the chief source being Travancore, India.2 Domestic produttion of ilmenite has heretofore been confined to Amherst and Nelson Counties, Virginia, where a complex rutile, ilmenite, and apatite ore is mined and treated to utilize all three of these minerals. A recent report3 has described development of the large titaniferous magnetite ore body at Tahawas, New York, where it is expected that 800 tons of ilmenite concentrates, containing 48 per cent TiO2 will be produced daily. Additional domestic production is expected from a large ilmenite deposit recently opened in caldwell county, North carolina. Flotation tests indicate that a high-grade concentrate containing 53 per cent TiO2 can be made from the North Carolina ore. Prospecting of domestic ores in other areas has been reported.' It appears that increased domestic production of ilmenite may well save considerable shipping space so vitally needed in these times. The composition and chemical structure of pure ilmenite is given by Dana as: FeO, TiO2; Ti, 31.6 per cent, Fe, 36.8 per cent, O2, 31.6 per cent. This composition is variable in that some iron or titanium may be replaced, giving a variable iron-titanium ratio. As an example, the iron-titanium weight ratio of ilmenite in Caldwell County, North Carolina, has been determined to be 0.94 (using 97.1 per cent ilmenite concentrate obtained by heavy liquids on minus Iso-mesh ore) compared with theoretical 1.16. No rutile was noted in this ore to account for the low value. This North Carolina ore is free of magnetite, which is a common associate of ilmenite ores. In view of a large potential production from North Carolina, the Tennessee Valley Authority conducted a study of methods of concentration of that ore, of which the results are reported herein. The Ore Five samples of Ore were taken from the deposit at various exposed locations and were mixed for the study and testing. An attempt was made to proportion the amount of weathered and unweathered portions in making the composite sample, so as to approximate actual operating conditions. An examination of representative specimens of the sample showed the following general facts: 1. The black mineral comprising nearly 70 per cent of the ore is ilmenite.

Jan 1, 1948

By Victor A. Phillips

A series of specimens of a Cu- 3.23 pct Co alloy were prepared with particle diameters from zero to 590A. The samples were then cold-rolled 95 pct and the effects of the particle size on the behavior on annealing for hr at temperatures between 100" and 900°C were studied (by hardness, light, and electron metallography). Particles, particularly for d r 105 to 590A, greatly impeded softening and vecvystallizn-tion, and tended to give elongated grains. Particles deformed fairly homogeneously with the ,matrix, be- IN a previous study by the author,' the growth of cobalt-rich precipitates was followed electron microscopically in Cu-3.12 Co alloy as a function of aging, typically at 650°C. The coherent spherical precipitates grew to 520 + lOOA average diam before spontaneously losing coherency and developing (111) facets. Stretching a few percent after precipitation 2aused loss of coherency to occur sooner at about 220A average particle diam. The particles apparently retained their fcc structure after loss of coherency. coming lau2ellae. For d = 55 to 180A, these lamellae gave streak-contrast effects apparently due to coherency strains , and spheroidized on annealing at 600" to 650°C, forming coherent particles. Particles of d = 250 ov 320A lost coherency during t-olling, giving incoherent lamellae. Recrystallization apparently occured by growth of new grains into unrecrystallized (recovered) material at temperatures below that at which cobalt atoms had much mobility. The present study was undertaken to explore the effect of cobalt-rjch particles of various average sizes from 50 to 600A diam on the isochronal annealing behavior of copper after heavy cold rolling. The previous work' was used as a guide in preparing the two-phase series of prerolling structures. The solution-treated alloy was also rolled for comparison. A further question of interest in the present study was whether dislocation and particle hardening were additive, since the prerolling structures covered the full range unaged - peak aged — overaged, and further precipitation might occur on annealing after cold rolling. Although there have been exhaustive studies of the isothermal2"6 and is~chronal annealing behavior of

Jan 1, 1967

By Sherwin F. Kelly

THE principal interest in the meeting sings arranged by the Geophysical Committee this year centered around the many papers dealing with the practical applications of geophysical methods to solving geological problems in many other parts of the world. The program Wednesday morning dealt with work in South Africa, Poland, and South America. Rudolph Krahmann's first paper gave a perspective of the geophysical investigations upon mineral deposits in South Africa. A striking point in his story was the tremendous increase in magnetic work during the last two or three years. This is largely accounted for by the intensive exploration for the extension of the Witwatersrand gold mining area. The author mentioned many surveys in which other methods were used for the search for ores of copper, lead, and zinc, and in the study of water-bearing and oil-bearing structures.

Jan 1, 1935

By J. C. Mertz

ACCURATE knowledge of the solid solubilities of the elements that dissolve in the important base metals is needed for guidance in the preparation and heat-treatment of the alloys derived from these compo-nents. While there is still difference of opinion concerning the merits of the X-ray and microscopic methods of determining such solubilities, it is certainly true that the recent extensive use of X-ray diffraction to review the existing constitutional data has revealed many glaring inaccu-racies and has brought about a much improved knowledge of phase-boundary locations, which will inevitably come to include all of the important alloy systems. When the work is done with all necessary precautions it appears that in the majority of cases where the solubilities extend beyond a few tenths of a per cent the X-ray back-reflection technique is capable of furnishing the best of information in this field. For the most prolonged and thorough studies it is obviously advisable to combine the results of several methods, in particular, to obtain an agreement between X-ray and microscopic data. This paper reviews the work previously done on the solubilities of phosphorus, arsenic, antimony and bismuth in copper and, in considera-tion of the uncertainties thus made apparent, presents, new X-ray data obtained with the first three members of this group.

Jan 1, 1936

By G. Y. Chin, M. T. Dolan, W. L. Mammel

We have obtained by computer methods the solutions of the Taylor analysis1 for axisymmetric flow in bcc metals. Four modes of slip have been treated in detail:2-4 (111), {112}(111), {123}( 111), and a mixture of all three. In addition to obtaining anisotropy of strength data for randomly oriented or textured polycrystalline material,4 we have also obtained the lattice rotation resulting from slip on the predicted systems. The patterns of lattice rotation are essential to an improved understanding of texture development during deformation. The present note shows the results of lattice rotation for 5 pct axisymmetric compression, for fifty-two axial orientations distributed at 5-deg intervals throughout the standard stereographic triangle. The data are presented in Figs. 1 to 4 for the four modes of slip. The lattice rotation is indicated by a vector, the ends of which correspond to the positions before and after the deformation. The different vectors emanated from a given orientation represent different combinations of five slip systems that satisfy Taylor&apos;s minimum shear criterion.&apos; Fig. 1 shows the results for {110}< 111> slip. They are similar to those obtained by Bishop5 for the case of (111 )(110) slip in axisymrnetric tension, since in axisymmetric flow the sense of lattice rotation for {111)( 110) in tension is the same as that for (110) (111) in compression. The pattern of lattice rotation may be divided into three regions: region A in which the rotation is toward [100]; region B, toward [lll]; and region C, toward either [ loo] or L lll]. Although some slip combinations in region C lead to [1101, the latter is not stable as continued activity of the same combinations will eventually move the axis toward [loo] or Llll]. It may also be noted that [loo] is itself not stable. However, close inspection of the vectors in region A shows that it is impossible for an axial orientation within A to rotate outside its boundary. Hence after heavy compression, all orientations from A and some from C are expected to form a diffuse band in the [100] vicinity. By far the largest region is B. Here all orientations rotate to [lll], which is a truly stable position. Thus the [111] texture component is expected to be rather sharp. For the case of (112 }( 111) slip, Fig. 2, region C is enlarged at the expense of A, with B about the same as for {110}( 111) slip. A significant difference, however, is that [loo], as well as [Ill], is now truly stable. Fig. 3 shows the results of slip on {123}( 111) systems. Region B is substantially enlarged at the expense of C, with A being intermediate in size between the {110}(111) and {112}(111) cases. Like the case of {110)( 111) slip, [100] is itself unstable. However, the lattice rotations here are confined to less than 5 deg; hence it may be considered "stable" for practical purposes. Finally, Fig. 4 shows the results of mixed slip. Here region B is the largest, and C the smallest, of all the cases considered. Both [loo] and [ill] are stable. The behavior of the three corner positions is, in fact, identical to the case of {112)( 111) slip, Fig. 2; it turns out that in these positions for the mixed slip case, all the active slip systems (based on Taylor&apos;s criterion) belong to pure {112}( 111) .4 In summing up the results for the four modes of

Jan 1, 1968

By Jon Kogut

This paper describes three programs, currently in use within MSHA, for graphic analysis of accident frequency data. The first program, TREND, plots confidence bands for curved trends in data compiled over a period of time. In addition to detecting statistically significant upward or downward trends, the program can be used to determine whether an observation at a particular time deviates significantly from the historical pattern. The second program, POIPORP, plots interval estimates for the risk of accident in each of several environments, given an observed number of incidents and exposure time at each environment. POIPORP is designed to quantify the uncertainty implicit in incidence rates based on limited information and to facilitate statistically valid comparisons among the rates. The third program, CINDY, plots dynamically adaptive control charts for accident or injury experience at a given location. These charts are used to detect statistically significant departures from a changing standard or a previously established trend. All three programs are written in FORTRAN IV, utilizing DISSPLA and IMSL. They exemplify forms of statistical analysis that would not be practical without a computer. Use of the programs is illustrated with applications to coal mine fatality and injury experience.

Jan 1, 1983

By T. J. O’Neil, S. J. Kirk

In 1978, a multidisciplinary team from the University of Arizona, the Mines Project Group, conducted a study to examine reclamation alternatives for a proposed open-pit copper mine. The cost of a waste dumping plan designed by a mining consulting firm was determined as well as the cost of dumping configuration prepared by the Mines Project Group. The latter dumps were designed to be more socially acceptable and aesthetically pleasing, in addition to serving more creative end land uses than the dumps designed by the mining consultant. One dump configuration designed by the interdisciplinary team was the least expensive plan of all the alternatives considered.

Jan 1, 1984

By A. U. Seybolt

DURING the course of an investigation of hot corrosion of nickel-base superalloys (combination oxidation-sulfidation attack at high temperature), it was considered possible that sulfur might gain entrance to the alloy in part, at least, by diffusion through the scale. Cr203 is nearly always observed as a prominent component of the oxide scale, and hence some experiments were carried out to examine the tracer diffusion of sulfur through Cr203 at 1000° C in the upper temperature range experienced by jet engine blades and vanes. Some hot-pressed Cr203 discs of quite high density were available from an earlier investigation1 on the rate of crf3 migration through Cr203. The Cr203 was 99.3 pct pure and contained -0.06 pct Fe as the largest metallic impurity. Additional data is given in Ref. 1. In this earlier work it was found that the rate of cation diffusion was independent of the atmosphere of thermal equilibration when using nitrogen, argon, or air, and also that the electrical conductivity of the hot-pressed Cr203 compacts was likewise independent of atmosphere in this range, thus indicating that the de-

Jan 1, 1969

DESPITE the very small number of engineers who can get away from their tasks to New York, a point so far from the Mid-Continent and Cali-fornia oil fields, where the real important, engineering progress in the industry is being made, the attendance was remarkably good, and it was generally remarked that all the sessions were "snappy," and there was no drag. This was largely because, under instructions from the chairman, very few papers were permitted to be read, and the "high lights" of each paper were pre-sented orally as an introduction to the large and varied discussions, many of which were prepared in advance. The round table discussion on petroleum engineering research problems, conducted by W. E. Wrather, proved a greater success than was anticipated, considering the difficulty in getting many of the men to discuss such problems. There has been no crystallization of opinion heretofore of what are important engineering research problems, as distinguished from pure science problems, and a digest of the discussion will be made available so as to present the results obtained. It is hoped that further round table discussions, as well as committee work, in the meantime summarizing problems appear-ing in papers published the last two to three years, will enable the oil industry to determine intelligently which of the problems are most important for immediate attack. The roundtable discussion on petroleum engineering educational problems, conducted by H. C. George of the University of Oklahoma, was equally fruitful, and since managers of companies, consulting engineers, and pro-fessors cooperated in these sessions, a cross-section of their opinions on improving the curricula for training the large number of petroleum engineers, which the industry can absorb in-the next few years, was obtained.

Jan 3, 1927

By George A. Bell

THE mine and milling plant of Demonstration Gold Mines, Ltd., is near the city limits of Baguio, Mt. Province, P. I. The mine road connects with the main highway to Manila. The nearest railway point is near sea level, approximately 40 miles distant. The Baguio district is very mountainous and has one of the heaviest rainfalls in the world. It is therefore difficult to maintain roads or to impound tailings and mine dumps. All supplies are trucked into the district direct from Manila or the nearest railway point, which means uncertain deliveries and high freight rates. Installation of equipment is difficult and costly. The average elevation at the mine is 4000 ft. and the climatic conditions are ideal except for a three months rainy season. The company generates its own power for mining and milling operations with three 400-hp. Ruston Diesel engines direct connected to 250-kw. General Electric alternating current generators. Labor conditions have been excellent, although at present social security laws are causing some unrest. Labor receives a higher average wage rate in this district than other labor in the Islands. The company also furnishes free living quarters, hospitalization and work- men&apos;s compensation. Taxation has been reasonable up to the present time, but some of the new mining legislation may make it difficult to operate and pay dividends. The future depends largely upon the continuation of $35 gold and the political outcome in the Islands. HISTORY The Demonstration ore body was worked by the Igorots for many years, as evidenced by old stopes and fill encountered in present operations. Attention of Americans was first attracted soon after the Spanish- American war. During the building of the Benguet road to Baguio, the engineers and foreman became interested in the geology of the district.

Jan 1, 1939

By Paul Klopstock

(Butte Meeting, August, 1913.) THE Kennedy mining district is situated about 55 miles in a southerly direction from Winnemucca, and about the same distance south-east from Battle Mountain : two towns situated oil t the main line of the Southern Pacific railroad. History. Prospectors were first attracted to the district by the reported discovery of gold by Chinamen in Cinnabar creek in the early 90&apos;s. The prospectors came from the rich placer workings in and about American canyon ; but the new diggings were not found sufficiently rich to justify their being, worked as placer properties, and the prospectors started work in a number of places, looking for the veins which had fed the canyon. In 1893, Charles E. Kennedy, a prospector who had been attracted by the reported discoveries in the vicinity, left Hawthorne and came to the present site of the town of Kennedy. Within a short time he discovered the vein known as the Imperial, and proceeded, with the aid of some friends, to develop it. The vein was readily traced for a distance of about a mile, and about $10,000 worth of high-grade ore was shipped to the Utah smelters. At about the same time the Lawler Brothers, who had been prospecting in the district for some time, located the ?Gold Note group," which showed some extremely rich ore. Within a very short time they extracted from &apos;the Gold Note vein 150 tons of ore, which was shipped to the Utah smelters, and netted about $105 per ton above all expenses. Their good fortune attracted attention to the camp, and within .a short time a town was laid out, with a population of about 500 people. It was named in honor of Kennedy, who had made the first discovery of pay ore in the district.

Jan 6, 1913