Search Documents

[ ]

Jan 1, 1942

By R. R. Nash, W. F. Sheely, E. D. Levine

ThiS note reports on the variation with temperature of critical stress for basal slip of binary solid-solution single crystals of indium and of thorium in magnesium. PROCEDURE Alloy single crystal spheres were acid machined to 3/8-in. diam cylinders with the basal planes of the crystals normal to the cylinder axis and then annealed at 810°K. Stress was applied parallel to the slip system, (0001) [1120]. Experimental details will be presented in another paper.' Two nearly equivalent' techniques of stressing were used. Stress on the magnesium-indium alloy crystals was increased by 1 g per sq mm at 1-min intervals, and the critical flow stress was defined as the lowest stress to pro-

Jan 1, 1960

By G. R. St. Pierre, L. M. Adelsberg, R. Speiser

OXIDE platelets have been observed'-3 in oxidized tantalum adjacent to the metal-oxide interface, Fig. 1. The origin and identity of the platelets are important with respect to the proposal of an acceptable mechanism of tantalum oxidation. At reaction temperatures below 750°C, it has been established that the platelets

Jan 1, 1967

[ ]

Jan 1, 1942

By L. L. Karafiath, S. G. Vick, E. A. Nowatzki

Computer analyses of the trafficability of copper mine tailings by four different commercially available BWEs were performed. A mathematical model incorporating the tailings' Coulomb strength parameters and the vehicles' geometry and operational characteristics was used to study the vehicle terrain interaction. The computer output provides the maximum tractive force (net drawbar pull) that each BWE can develop for given tailings conditions without bnngzng about a state of plastic failure in the tailings. Estimates of sinkage are also provided. The theoretical results for the BWEs and tailings studied compare favorably with the operating experience of similar BWEs used for remining gold tailings in South Africa. This lends some confidence to the validity of the mathematical model. The results of such analyses may be wed to evaluate, on a relative basis, which of a number of different machines would perform better than others under given conditions of a tailings deposit.

Jan 1, 1982

By M. C. Udy, P. C. Rosenthal

The use of minute boron additions to steel has been given considerable attention in recent years. Comparisons made between boron-free and boron-containing heats of otherwise identical analysis have indicated, beyond a doubt, the potent effect of boron for increasing hardenability. The actual hardenability increase has been expressed as a multiplying factor, or in terms of the percentage of other alloying elements boron might replace. The present study presents the results of a systematic survey of the use of boron as an addition to two types of alloyed steels and as a replacement for various percentages of molybdenum in these steels. Both cast and wrought steels of the two basic compositions were prepared. Molybdenum, because of its scarcity at the time the investigation was started, was selected as the element to be replaced by boron. Attention was also given to the effects of boron on other properties of the steels, particularly their notched-bar toughness, to investigate other advantages or limitations of this element as an alloy addition. Experimental Work Steels Investigated The two basic compositions used in this survey of boron as a replacement for molybdenum are given in Table I. The cast steels were higher than the wrought steels in silicon content to improve the casting quality. Table i.—Nominal Composition of the Two Base Alloy Steels composition. Per Cent. steel Mn Si Ni Cr Xi-Cr-Mo Wrought 0.28-0.70-0.15-o.45—o.45-0.32 0.90 0.25 0.55 0.55 Cast 0.28-0.70-0.35-0.45-o.45- 0.32 0.90 0.45 0.55 0.55 hln-&lo Wrought 0.28-I .go-o.0.15-0.32 1.70 0.15 Cast o. 28- I.40- 0.35- 0.31 1.70 0.45 a Sulphur was 0.040 per cent maximum and phosphorus 0.030 per cent maximum. Each of these base steels, both cast and wrought, was made with molybdenum contents of o, 0.10, 0.20, 0.30, or 0.40 per cent, the total comprising 20 steels. In addition, each of these 20 compositions was prepared with boron additions in amounts of o.oo15, 0.003, and 0.006 per cent as ferroboron; and in amounts of 0.002 and 0.005 per cent as two commercial intensifier alloys, designated alloys A and B. The boron-treated steels totaled 100, and the entire series 120. Test Procedure Each steel was melted as an individual heat in a 50-lb., magnesia-lined induction furnace. Ingot iron scrap or mixtures of ingot iron and steel. scrap were used for melting stock. Deoxidation was carried out in the furnace with 0.10 per cent aluminum. The aluminum addition was

Jan 1, 1948

By M. C. Udy, P. C. Rosenthal

The use of minute boron additions to steel has been given considerable attention in recent years. Comparisons made between boron-free and boron-containing heats of otherwise identical analysis have indicated, beyond a doubt, the potent effect of boron for increasing hardenability. The actual hardenability increase has been expressed as a multiplying factor, or in terms of the percentage of other alloying elements boron might replace. The present study presents the results of a systematic survey of the use of boron as an addition to two types of alloyed steels and as a replacement for various percentages of molybdenum in these steels. Both cast and wrought steels of the two basic compositions were prepared. Molybdenum, because of its scarcity at the time the investigation was started, was selected as the element to be replaced by boron. Attention was also given to the effects of boron on other properties of the steels, particularly their notched-bar toughness, to investigate other advantages or limitations of this element as an alloy addition. Experimental Work Steels Investigated The two basic compositions used in this survey of boron as a replacement for molybdenum are given in Table I. The cast steels were higher than the wrought steels in silicon content to improve the casting quality. Table i.—Nominal Composition of the Two Base Alloy Steels composition. Per Cent. steel Mn Si Ni Cr Xi-Cr-Mo Wrought 0.28-0.70-0.15-o.45—o.45-0.32 0.90 0.25 0.55 0.55 Cast 0.28-0.70-0.35-0.45-o.45- 0.32 0.90 0.45 0.55 0.55 hln-&lo Wrought 0.28-I .go-o.0.15-0.32 1.70 0.15 Cast o. 28- I.40- 0.35- 0.31 1.70 0.45 a Sulphur was 0.040 per cent maximum and phosphorus 0.030 per cent maximum. Each of these base steels, both cast and wrought, was made with molybdenum contents of o, 0.10, 0.20, 0.30, or 0.40 per cent, the total comprising 20 steels. In addition, each of these 20 compositions was prepared with boron additions in amounts of o.oo15, 0.003, and 0.006 per cent as ferroboron; and in amounts of 0.002 and 0.005 per cent as two commercial intensifier alloys, designated alloys A and B. The boron-treated steels totaled 100, and the entire series 120. Test Procedure Each steel was melted as an individual heat in a 50-lb., magnesia-lined induction furnace. Ingot iron scrap or mixtures of ingot iron and steel. scrap were used for melting stock. Deoxidation was carried out in the furnace with 0.10 per cent aluminum. The aluminum addition was

Jan 1, 1948

By D. E. Ranta, M. W. Ganster, A. D. Ward

An ore zoning technique developed by Climax geologists during the past forty years has been used to contour drill-hole assay values on cross-sections for fourteen porphyry molybdenum deposits in western North America, including the Climax and Henderson orebodies. Detailed geological studies of these large, complex deposits are essential in determining ore controls, which are the factors most critical to the zoning of MoS2 and to conceptualizing geologic model s. The technique provides a detailed representation of the size, shape, grade distribution, and geologic continuity of the individual deposits. It demands a disciplined approach and adheres to rigorous rules while maintaining flexibility for adaptation to widely varying geologic conditions. By defining the limits that guide and control manual, computer-assisted conventional, and geostatistical reserve estimates, it exerts a strong geologic influence on the estimation process. A combination of ore zoning and geostatistical analysis of molybdenum deposits produces a significantly more accurate, precise, and defendable geologic reserve estimate than other methods.

Jan 1, 1984

By Stanley Herold

Considerable interest has been shown, during recent years, in the possibilities of developing oil fields in the South American Republics, now that the exhaustion of our present fields can be seen in the not very distant future. The demand for fuel oil and its products has been increasing far more rapidly than our increment of production during the last few years. Increase of consumption has been largely curtailed by the lack of sufficient supply. The main factors that have contributed to our previous neglect of the southern fields have been as follows:, (a) Lack of sufficient demand for the product. (b) Competition with producing fields, having large production, low cost, and better geographical position, such as Tampico, Mexico. (c) Greater interest in home fields with ready market at hand. (d) Our ignorance of southern economic and geologic conditions, clue to the distance between those areas and our financial centers. (e) Economic conditions in the southern countries, necessitating high costs of exploration and exploitation of the fields.

Jan 9, 1918

By A. T. Corey, J. H. Henderson, M. R. J. Wyllie, C. H. Rathjens

The results of three-phase relative permeability tests on nine water-wet consolidated Berea sandstone samples are presented as composite ternary diagranls showing isoperms of oil, water and gas. Capillary pressure control was exercised over the flow of gas and oil in the presence of water. The water saturations ranged from 17 to 71 per cent pore volume. A method of calculating both the oil and water permeabilities of a three-phase system from the easily measured gas relative permeability is presented. EXPERIMENTAL PROCEDURE AND RESULTS A renewed interest has been shown in three-phase relative permeability as a result of recent developments involving underground combustion processes, steam injection, and other multiphase displacement processes. The experiments and results described here involved simultaneous flow of oil and gas in consolidated Berea sand with brine present as the wetting phase. Gas and oil relative permeabilities were measured on nine cores with CaC12 brine present as the wetting phase in saturations ranging from 17 to 71 per cent. The average residual liquid saturation of the cores was approximately 20 per cent. In order to make certain that brine was the wetting phase, the test cores were saturated with brine before contact with hydrocarbons. As an added precaution to avoid having oil displace brine from the wetting position as a result of changing wettability, each core was only used twice, i.e., first with a fixed percentage of brine and then for a gas-oil permeability determination with no brine present. The results, therefore, are presented as composite ternary diagrams representing the flow tests on nine individual cores having very similar properties. All tests were made using a modification of the capillary pressure techniquc described elsewhere. The effective oil permeability was measured before gas was introduced using a very small pressure gradient (a few centimeters of oil). This determination was made without selectively wet barriers in contact with the core. The cores were then placed between capillary barriers and gas-oil relative permeability curves obtained. The capillary barriers had been made water repellent with a silicone treatment. In determining gas-oil-water relative permeability in this fashion, control was exercised over the capillary pressure existing between the gas and oil. No control was exercised over the pressure difference existing between the oil and water. Athough an equal pressure gradient was applied to the gas and the oil phases, this pressure gradient does not exist in the water phase. Since the pressure gradient across the core was always much less than the displacement pressure of the fully saturated core, the pressure gradient can have caused only a very slight distortion of the oil-water interfaces. This slight distortion of the oil-water interfaces had a negligible effect on the validity of the oil permeabilities measured. The oil permeability, measured in the presence of water but with no gas present, was in every case equal. within experimental error, to the gas permeability of the gas-oil system when the oil saturation was the same as that of the water. Gas and oil relative permeabilities were plotted as a function of total liquid saturation. It was found that the gas relative permeability curves obtained on cores with brine present were identical with those obtained on the same cores with no brine present. The denominator for calculating oil relative permeabilities was the permeability found by extrapolation to infinite mean pressure (A la Klinken-berg). Fig. 1 illustrates gas-oil relative permeability results obtained on a typical core. The solid permeability curves represent the experimental data. The dashed oil relative permeability curve was calculated using the relationship;

Jan 1, 1957

By A. M. Gaudin, D. W. Fuerstenau, M. M. Turkanis

SOLUBLE silver salts are effective activators for flotation of sphalerite with potassium ethyl xanthate as collector.' Since sphalerite takes up large quantities of silver ions rapidly," investigation of this system appeared fruitful for studying the mechanism of sphalerite activation and deactivation. Experimental data presented here comprise studies of the mechanism and rates of activation and deactivation of sphalerite with silver and cyanide ions. A 20-lb sample of sphalerite from Ottawa County, Oklahoma, was handpicked, crushed, screened, hydrosized to produce a 65/100-mesh fraction, and purified by electrostatic separation. The sphalerite was then leached with benzene and absolute ethyl alcohol to remove possible organic contaminants and with 0.1 M NaCN to remove any copper that might have been picked up during screening. The benzene had been specially purified by grinding with fine sphalerite for 12 hr to remove trace impurities that might have had a specific affinity for sphalerite. Finally, the mineral was washed, dried in flowing nitrogen, and stored in large ground-glass stoppered weighing bottles under a small nitrogen pressure.

Jan 1, 1957

By R. D. Pehlke

THE impending commercial importance of iron-aluminum alloys has served as a stimulus for re- search on the preparation and properties of these alloys. However, the activities of the components of the binary system remain undetermined. The experimental determination of the thermodynamic properties of binary solutions of iron and aluminum has been hindered by the high liquidus temperatures

Jan 1, 1959

By G. Howell Clevenger

PAGE Introduction,............891 L Nature of Precipitates,.........892 11. Experimental Work Upon Alloys,......895 Silver,............895 Gold,............896 Conclusions,............896 111. Present Methods of Refining,.......897 1. Refining by Roasting,.........897 2 Refining with Acid,..........898 3. Smelting with Lead,.........902 Tavener's Method,..........903 Merrill a Method,.,........903 Comparison of Costs of Acid-Refining and Smelting Processes,. . 904 Detailed Costs of Refining Cyanide Precipitates at Lead, So. Dak., September 29, 1903,.........904 Cost of Acid-Refining at the Horseshoe Mill, Terry, So. Dak.,. . 907 IV. The Removal of Zinc by Distillation,.....908 Experimental Distillations,.....,...910 Analysis of Precipitates Used for Distillation-Experiments,. . 910 Discussion of the Results of the Distillation-Experiments,. . 915 V. General Conclusions,.........917 VI. Outline of a Proposed MEthod OF Treatment,.... 917 Introduction. Attempts to discover, for the cyanide process, a better precipitant than zinc have been unsuccessful. Hydrogen sulphide, sulphurous acid, ferrous sulphate, etc., precipitate gold and silver from cyanide solutions either not all or incompletely.

Jan 1, 1904

By T. E. Scott, D. H. Sherman, C. V. Owen

It has been established' that vanadium exhibits a ductile to brittle transition temperature which increases with increasing hydrogen content. Optical microscopic examination at room temperature revealed no evidence of hydride precipitate in fractured specimens containing 100 ppm H, but hydrides were present in samples with 800 ppm H. More recently2 the strain rate and temperature dependences of the ductility drop in vanadium containing 6 ppm H were reported. It was argued that the ductile-brittle transition, while dependent on the presence of hydrogen, probably could not be explained by the precipitation of hydride. The bases of the argument were that 6 ppm H would not produce sufficient hydride to alter the ductility to the extent observed and no visual evidence of hydride was obtained. However, the data were not sufficient in these investigations 1,2 to define accurately the ductile-brittle transition temperature. Also, no information was available concerning the terminal solubility of hydrogen in vanadium at the low concentrations employed. westlake 3 has studied the electrical resistivity of vanadium at several hydrogen concentrations. He was able to detect the precipitation of hydride and to extend the hydrogen solvus to the composition and temperature range pertinent to the observed ductile-brittle transition behavior, Westlake compared his

Jan 1, 1968

By P. A. Tucker, C. R. Hudgens, D. E. Etter, D. L. Roesch, D. B. Martin

The equilibrium phase diagram of the Pu-Cd system is presented based on data obtained by differential thermal analysis, metallography, and electron-microprobe X-ray analysis. Liquidus temperatures range from 320° to 934°C. The system contains one congruently melting compound, PuCd, (945°C), and three incongruently melting compounds, PuCd, (800°C), PuCd, (730°C), and PuCd11 (410°C). A liquid-miscibility gap extends from 2 to 60 at. pet Cd with the monotectic reaction isotherm at 910°C. INTEREST in the potential use of plutonium alloys as reactor-fuel materials has prompted investigation of the phase equilibria in plutonium binary systems. A cursory investigation of the phase equilibria in the Pu-Cd binary system was conducted by differential thermal analysis (DTA), metallography, and electron-microprobe X-ray analysis (EMX). Extensive solid solubility of cadmium in both e and 6 plutonium was predicted1 based on atomic radii and electronegativities. Liquid immiscibility between these two elements was also predicted based on Mott's extension of Hildebrand's method. In the only previous investigation of the Pu-Cd system,2 two intermetallic compounds, PuCd11 (incon-gruent melting point 406°C) and PuCd8, were identified. EXPERIMENTAL The plutonium metal used in this work had a total impurity content of 500 ppm; the major impurities were: carbon (215 pprn), silicon (75 ppm), iron (60 ppm), nickel (40 ppm), and aluminum (25 ppm). The cadmium was reagent grade with a purity of 99.99 pet. The DTA technique for the study of plutonium alloys was previously described in detail.3 The alloys to be studied were prepared in tantalum DTA specimen capsules which were sealed by inert-gas welding. The alloys were homogenized in the liquid state in these sealed capsules which prevented the loss of cadmium by vaporization. Only the thermal arrests in the DTA heating curves were used to define the transformation temperatures of the system since supercooling affected many of the results during cooling. After the alloys were analyzed by DTA, the same alloys were used for the metallographic studies. Metallographic examinations were conducted in the manner described for plutonium alloys., No reaction was detected between the alloys and the tantalum capsules. Alloys for EMX analysis were placed in metallographic mounts together with specimens of unalloyed plutonium and cadmium which served as standards. The samples were highly polished but unetched. No protective coatings were applied to the surfaces of these radioactive specimens. Such coatings are detrimental to the excitation conditions and have been found to be unnecessary for the control of radioactive contamination. RESULTS The results of the DTA studies are presented in Table I. The phase diagram, constructed from these data plus the metallographic and EMX results, is presented in Fig. 1. The congruently melting compound, PuCd2, was identified by the occurrence of a maximum melting point (945°C) at 33.3 at. pet Pu-66.7 at. pet Cd and by the presence of a single phase in this composition.

Jan 1, 1965

By R. D. Coleman, A. E. McIlhinney, C. E. Capes

tentially valuable. These losses will probably increase with the expansion of production and will require the development of effective disposal and utilization processes under pressure of the lack of adequate disposal areas, the enforcement of air and stream pollution laws, and the economic need to obtain the maximum yield of salable product.1 Fine Coal Treatment Processes Most coal cleaning methods depend upon the density difference between coal and its impurities to effect separation. These gravity concentration methods, however, are not practical for particles finer than about 100 mesh and cleaning methods dependent upon the differences in

Jan 1, 1971

By R. A. Vik, C. B. Daellenbach, W. M. Mahan

The influence of reduction roasting and thermal shock on the grindability of a refractory low-grade Michigan iron ore was examined in bench-scale tests. The quantitative effects of the various treatments were evaluated at three sieve levels, 48, 100, and 400 mesh, with ball-mill-grindability and work-index parameters as response indicators. Data from the testing program were statistically analyzed to isolate the effects of cooling rate, roasting temperature, mesh level, and ore chemical condition. All four variables were found to have an important influence on the grindability of the treated ore. Ore chemical condition and roasting temperature had the most pronounced effects.

Jan 1, 1972

By W. D. Felix, R. D. Smith, J. A. Campbell

The mechanism most consistent with available information on atmospheric trace element emissions involves the volatilization of a significant fraction of many trace elements during coal combustion, with subsequent condensation on fly ash as the combustion gases cool. The larger surface-td-volume ratio of the smaller particles leads to an enrichment of the volatile trace elements. From an environmental viewpoint, the submicron size particles are of greatest concern. These particles show the highest concentrations of trace elements, are least efficiently collected by pollution control devices, have high atmospheric mobilities, and are deposited preferentially in the pulmonary and bronchial regions of the respiratory system. The mechanisms for trace element enrichment and formation of submicron particles will be described.

Jan 1, 1981

By Zhengbo Pan, Fujun Gou, Jifei Chen

This paper discusses the various alternatives that are technically feasible for "over-the-raise" continuous advancing in gently inclined coal seams and the computer-aided selection of the optimal mining option. Examples in Wangshiao Coal Mine and Chaohua Coal Mine are cited to illustrate the interval between raises, face length, single or double raise layout and single or double face layout.

Jan 1, 1983

By E. H. Crabtree, T. G. Chapman, V. W. Winters

This paper traces the experimental and pilot plant work completed by the authors since 1939 including the various methods which have been developed in applying coarse activated carbon to cyanidation. The methods and results developed by the authors in desorbing gold and silver from carbons are given and the possibilities for the re-use of the desorbed carbons are discussed.

Jan 2, 1950