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By M. E. Grimes

A method of predicting uranium extraction rate in underground bacterial leaching of as-blasted ore has been developed. The method is based on the hypothesis that extraction is directly proportional to the volume of a piece of ore that is penetrated by the leaching agent, and that each piece of ore, regardless of size, has been penetrated radially from the external surface to the same depth at a given leaching time. Consequently, given an initial size and assay distribution, extraction should be predictable for a given penetration. Two laboratory bacterial leaching tests under simulated stope leaching conditions were carried out for a periods of 89 and 96 weeks. On completion, the residual ore was screened and analyzed. The information so obtained was employed to provide an elapsed time base for the penetration model, from which predictions of future extraction were made. The finding of solubilized uranium trapped within apparently sol id ore pieces was unexpected. However, it is not recoverable except after crushing, and hence does not affect calculations of underground leaching .

Jan 1, 1974

By H. O. McLeod, J. M. Campbell

This paper presents the results of the data obtained in the first stage of a long-range study at high pressures of the system, vapor-hydrate-water rich liquid-hydrocarbon rich liquid. The data presented are for the three-phase systems in which no hydrocarbon liquid exists. Tests were performed on 10 gases at pressures from 1,000 to 10,000 psia. One of these was substantially pure methane, and the remainder were binary mixtures of methane with ethane, propane, iso-butane and normal butane. Several conclusions may be drawn from the data. 1. Contrary to previous extrapolations, the hydrocarbon mixtures tested form straight lines in the range of 6,000 to 10,000 psia which are parallel to the curves for pure methane, when the log of pressure is plotted vs hydrate formation temperature. 2. The hydrate formation temperature may be predicted accurately at pressures from 6,000 to 10,000 psia by using a modified form of the Clapeyron equation. The total hydrate curve may be predicted by using the vapor-solid equilibrium constants of Carson and Katz' to 4,000 psia and joining the two segments with a smooth continuous curve between 4,000 and 6,000 psia. 3. The use of gas specific gravity as a parameter in hydrate correlations is unsatisfactory at elevated pressures. 4. The hydrate crystal lattice is pressure sensitive at elevated pressures. INTRODUCTION Prior to 1950 many studies had been made of the hydrate forming conditions for typical natural gases to pressures of 4,000 psia.""'"'"" Most of these attempted to correlate the log of system pressure vs hydrate formation temperature, with gas specific gravity as a parameter. One of the more promising correlations was made by Katz, et al, which utilized vapor-solid equilibrium constants. The only published data above 4,000 psia are those of Kobayashi and Katz7 for pure methane to a pressure of 11,240 psia. In the intervening years, most published charts for the high-pressure range have represented nothing more than extrapolations of the low-pressure data, with the methane line serving as a general guide. The reliability of these charts has become increasingly doubtful (and critical) in our present technology as we handle more high-pressure systems. The portion of our high-pressure hydrate research program reported here was designed to: (1) investigate the reliability of existing charts; (2) obtain actual data on gas mixtures to 10,000 psia; and (3.) develop a simple hydrate correlation that was more reliable than those which simply used specific gravity as a parameter. Binary mixtures of methane and ethane, propane normal butane, or iso-butane were injected into a high-pressure visual cell containing an excess of distilled water. Hydrates were formed and then melted to observe the decomposition temperature of the hydrates at pressures from 1,000 to 10,000 psia. EQUIPMENT The equipment consisted of a Jerguson 10,000-lb high-pressure visual cell, a 10,000-1b high-pressure blind cell and a Ruska 25,000-1b pressure mercury pump. The visual cell was placed in a constant-temperature water bath controlled by a refrigeration unit and an electric filament heater. A Beckman GC-2 gas chromatograph was used in analyzing the gas mixtures after each run was completed. EXPERIMENTAL PROCEDURE After evacuating the gas system, the heavier hydrocarbon was injected into the high-pressure mixing cell to that pressure necessary to give the desired composition. This cell then was pressured to 1,100 to 1,200 psia by methane from a high-pressure cylinder. The mixing cell holding the gas contained a steel flapper plate and was shaken intermittently over a period of 15 minutes. After mixing, the valve to the high-pressure visual cell containing excess distilled water was opened, and the gas mixture was allowed to flow into the cell. The temperature in the water bath was lowered 10" to 15'F below the estimated hydrate decomposition point. As a first check, the temperature was increased at a rate of 1°F every six minutes to find the approximate point of decomposition. It was again lowered 1.5° to 5°F to form hydrates. The temperature was raised to within l° of the estimated decomposition point and then increased 0.2F every 10 to 15 minutes until the hydrates decomposed. This procedure was repeated at various pressures to obtain 7 to 13 points for each mixture between 1,000 and 10,000 psia. After completion of the hydrate decomposition tests, the gas mixture composition was analyzed with a calibrated gas chromatograph. These gas analyses have an estimated error of ± .1 per cent.

By M. R. Geer, H. F. Yancey, P. S. Jacobsen

Two growing problems confront the preparation engineer-still further restrictions on stream pollution and a greater proportion of fine coal as more and more continuous miners come into use. The dewatering screens, centrifuges, and settling ponds that sufficed a few years ago must often be supplemented by more effective equipment, and in some instances the finest solids are now being recovered by vacuum filtration, once considered too costly in many coal washeries. Unfortunately not all slurries can be readily filtered. Some are virtually unfilterable, and others do not permit the high cake rates needed to hold costs within reason. Often, however, these difficult slurries can be rendered filterable by flocculation. Starch and lime have long increased settling rate in thickeners and can also aid filtration. More recently there have been other flocculants, primarily synthetic polymers or gums. Reports of their great effectiveness prompted the U. S. Bureau of Mines to test their use in filtration as part of its program on recovering and cleaning fine coal. The object of the present work was to compare some of the newer flocculants with starch and lime and to test the reaction of different types of slurries to flocculation. Three natural slurries, three synthetic coal-clay mixtures, and five flocculants were tested, all with a laboratory filter leaf.

Jan 7, 1959

Minute of the Board of Directors, Jan. 26, 1917 In the name of all the members of the American Institute of Mining Engineers, this Board extends to. Mr. Herbert C. Hoover, an honored Vice-President of the Institute, on the occasion of his present temporary return to his native land, the cordial welcome of his colleagues, and their congratulations upon the noble work splendidly done by the Commission for Relief in Belgium of which he is the head. It is understood that a leading purpose of Mr. Hoover's visit to America at this time is the collection of additional funds, to be administered by his Commission in the care of the destitute children of Belgium. To this enterprise endorsed by both the belligerent parties, as well as inspired by the purest and tenderest sentiments of humanity, contributions are solicited from engineers, especially through an organization known as the "Belgian Kiddies Limited," which this Board, heartily approving its object and method, recommends to the consideration of the members of the Institute. On motion duly seconded it was unanimously VOTED.-That this minute be spread upon the record of the Board, and published in the Bulletin, and that a copy thereof be transmitted to Mr. Hoover, and to the San Francisco Section of the Institute.

Jan 3, 1917

By D. A. Flanagan, B. L. Landrum, P. B. Crawford, B. C. Norwood

Herern is described a heat conduction model which has been developed to predict the pressure distribution within a reservoir being subjected to rrnsteady-state depletion. Although potentiometric models have been widely used to study reservoir pressure distribution, their application is limited to the study of steady-state cases. Electrical analyzers may be used to study unsteady-state phenomena, but their application and simulation have certain limitations. Much of the now accepted theory of unsteady-state fluid flow in porous media has evolved from previous heat conduction knowledge. An analogy between the flow of fluid in an unsymmetrical reservoir and con-duct ion of heat in a similarly shaped unsymmetrical metal plate is made to show adaptability of the hear conduction principle to transient reservoir cases. A description of the model and necessary instrumenrarion is included. Data show influence of well location on pressure distribution during unsteady-state deple[ion. Application of results is made to a hypothetical reservoir and to a reservoir located in an irregular aquifer. INTRODUCTION Development of methods for predicting behavior of petroleum reservoirs has resulted partially from adaptation of electrical and thermal flow concepts to the flow of fluids through porous media. Extensive investigation of electrical and thermal flow problems has resulted in mathematical solutions applicable to many reservoir problems. The relative ease of measuring electrical flow has brought wide acceptance of the use of the potentiometric model to study certain field problems. Potentiometric models are restricted to the study of steady-state conditions because of the instantaneous response of electrical flow to changes in the applied potential. The electrical reservoir analyzer has been one of our most useful instruments for studying certain phases of unsteady-state behavior1. Other than approximation techniques, no method exists for determining pressure distribution in an irregular reservoir during primary depletion. Heat flow, like fluid flow, is inherently transient. The model described here was developed to use this transient nature of heat flow, measurable in the laboratory, to simulate transient flow of fluids in the porous medium of the reservoir above the bubble point. A metal plate shaped like the reservoir to be studied was heated by a "well" source. Temperature increase in the plate is analogous to pressure decline in the field if the field is being depleted, or pressure increase if fluid is being injected. This study is intended to determine the feasibility of using the transient nature of the heat flow to study the transient behavior of fluid flow. It is hoped that this new technique will aid in the understanding of one of the more complex phases of reservoir engineering. THE FLUID FLOW-HEAT CONDUCTION ANALOGY The similarity of the equations which describe the flow of fluids through a porous medium and the conduction of heat through a solid is well known2. Rate of flow of fluids is given by Darcy's law3. while the rate of flow of heat is given by Fourier', (I,, - KA 4T........(2) Combining Eq. 1 with the equation of continuity for a compressible liquid", i.e.,results in Expressing y in terms of the compressibility, i.e., pr = peey ,..........(5) and by expanding the exponential and neglecting higher orders of cp one can obtain

By Enrique Touceda

FOR a number of years prior to the world war, the firm of Geo. H. Thacher & Co., of Albany, N. Y., was engaged in the manufacture of marine and other gray-iron castings. At -the outbreak of the war the firm decided to specialize in the manufacture f propeller wheels. It attacked the problem, therefore, from a foundry point of view, seeking to produce a casting that would be so accurate that no subsequent machining would be required on the blades, also from the point of view of the ship builder. There were two general methods f manufacture, the shortcomings of which have been freely acknowledged. In the sweep method, the nowel, or bottom half-mold, for each blade is swept up by a spindle beam and pitch race, while the top half-mold for each blade is built up individually. In the pattern method one individual blade, with the hub or hub portion, is mounted on a spindle and the individual -blade mold formed, the pattern is then rotated on the spindle to the position- for the next blade, etc. In rare cases wheels were made from a solid pattern. Owing to the cost of the pattern, its failure in many instances to be correctly made, and (when made of wood) its early and sure distortion the disadvantage of this practice is obvious, while metal patterns in most instances were prohibitive in cost. In these methods both green-sand and loam molding was practiced. The casting produced by either method can be considered only as a blank from which the propeller must be machined. The back surface f each blade must be chipped too the templet and through this procedure chipped to such accuracy, as will be required for a static balance. Inasmuch as the' work done by the machine tool is confined to the driving face of the blades, not only is perfection most difficult, but corrosion will be greater because of the removal of the dense skin f the casting and the local strains set up by the pneumatic tool in chipping. To produce a finished 9-ft. propeller for a Navy destroyer required from 8 to 21 days f foundry work and about the same length of, time for the machining. Through the use f the Thacher process, only as many hours are required, besides it is possible to produce a finished casting in perfect conformity, with any particular propeller-wheel design,

Jan 4, 1921

By H. R. Ogden

The notch sensitivity of titanium alloys is affected by impurity content, microstructure, and heat treatment. Using notch tensile properties to evaluate notch sensitivity, three commercial titanium-base alloys were investigated over the temperature range of -320o to 390°F. The alloys studied were Ti-5Al-2.5Sn, Ti-6Al-4V, and Ti-2Fe-2Cr-2Mo. Six interstitial levels were studied for each alloy in four mi-crostmctural conditions. The ff- 0 alloys were studied in both the annealed and heat-treated condition. All tests were conducted using 1/4-in. diam round tensile samples. The notched samples had a 50 pct notch with a notch sharpness (a/r) of 53, corresponding to Kt 6.3. Notch sensitivity was increased by increased interstitial content, low temperature, and acicular-type microstructures. The heat-treated, high-interstitial content - 13 alloys were more notch sensitive than the same alloys in the annealed condition. In addition, minima in the notch tensile-temperature curves were observed at temperatures near 32°F. These minima became more pronounced with increasing interstitial content. 1 HE increaseduse of titanium alloys in high strength applications at subzero temperatures requires that a better under standing of the low-temperature behavior of the alloys be obtained. At low temperatures, metals generally exhibit increased strength with lowered ductility and tohness. Notch sensitivity and the factors which influence it become more important as the strength level is increased and the temperature is decreased. Some of the factor s which affect notch sensitivity in ti- tanium alloys are composition, interstitial content, microstructure, and heat-treatment condition. In this paper, the results of a study of these variables on the notch sensitivity of three titanium alloys at temperatures from —320o to 390o are reported. The notch geometry selected for this program was chosen to provide a severe test of notch sensitivity. The ability of the metal to flow without initiating fracture under these severe conditions is reflected in the notch-strength values. Since notch strength is, in part, determined by the constraint exerted by the combined tensile stresses, the behavior of notch specimens reflects the properties of the material under combined stresses. For example, a material with a high notch-unnotch strength ratio may be expected to withstand the biaxial stresses encountered in a pressure vessel better than a material with a low ratio of notch-unnotch strengths. This implies that maximum strength alone is not a sufficient criterion for applications of this type. It further may be concluded that the various conditions that promote poor notch behavior also will affect adversely the performance of materials under combined stresses. In the alloys studied, these included low temperatures, high interstitial levels, and hasformed microstructures. EXPERIMENTAL PROCEDURES Three alloys, Ti-5Al-2.5Sn, Ti-6Al-4V, and Ti-2Fe-2Cr-2Mo, were purchased from commercial producers as 2-in.-dam rod stock. Oxygen and nitrogen were added to these alloys by remelting to obtain a variety of interstitial contents as shown in Table I. In order to Compensate for the much more potent strengthening effect of nitrogen compared with oxygen, an oxygen equivalent content is used to describe the total oxygen plus nitrogen contents studied. It has been suggested previously1 thatnitro-gen is approximately twice as effective in strengthening as oxygen, and carbon, to the extent it is in so-

Jan 1, 1962

[A AALSETH, Earl P (M 51) Consult Geol Engr 2019 Eldorado Dr, Billings, Monl ABADIE, Henry G (M 43) Asst to Supt of Oper Long Beach Oil Dev Co 925 Harbor Plaza, Long Beach 2, Calif ABBE, T Waldo (A 56) Asst Dist Oper Supt Sun Oil Co PO Box 66, Stowell, Tax ABBOTT, Fred E Jr (M 59) Abqaiq Dist Mgr Arabian American Oil Co Dhahran, Saudi, Arabia ABBOTT, Clifton T (A 60) Apartado 677, Maracaibo, Venezuela ABBOTT, J L (M 56) Partner Pritchard & Abbott 1010 Ft Worth Natl Bk Bldg, Fort Worth 2, Tex ABBOTT, Richard H (J 51) Partner Abbott & Howard 422 W Hermosa San Antonio 12, Tex .ABBOTT, William G (M 50) Div Mgr Rice Engrg & Operating Inc Box 1142, Hobbs, N. M. ABDERHALDEN, Ronald R (J 59) Prod Engr Continental Oil Co Box 100, Carmi, III ABEL, Malcolm D (J 50) Gen Partner Abel & Bancroft PO Box 865, Midland, Tex ABEL, Ramond L (M 28) Prof of Chem Eng Univ of Pittsburgh, Pittsburgh 13, Pa ABEL, Wayne K (M 57) 1513 Patton Drive, Odessa, Tex ABELL, Joseph M (J 55) Petr Engr Tennessee Gas & Oil Co Box 1772, Casper, Wyo ABELS, Thomas A (J 60) Exploit Engr Shell Oil Co Box 193, New Orleans 3, La ABENDROTH, G F (M 46) Dring Prod Supt Lyons & Logan 1500 Beck Bldg, Shreveport, La ABERCROMBIE, Bolling A (M 60) Mgr Product Planning Axelson-Garrett PO Box 2427, Longview, Tex ABERCROMBIE, C T (160) Prod Engr Cities Ser Petr Co Box 472, Brownfield, Tex ABERCROMBIE, H L Jr (J 55) Prod Engr Mobil Oil Co Room 1800 Gr PI Life Bldg, Lubbock, Tex ABERCROMBIE, Robert (J 57) Prod Engr Mobil Oil Co PO Box 1770 Shreveport, La ABERG, Richard S (M 57) Area Prod Geol Shell Oil Co of Canada, Box 100 Calgary, Alta, Canada]

Jan 1, 1961

By Gordon H. Geiger, J. Bruce Wagner

Electrical conductavity and therrnoelectvic nzeasuretnents on synthetic hematite slabs with 0.01 to 0.90 at. pet Ti and with 0.30 at. pet Ca were made. Additions of titanium and of calcium both increased the electronic conductivity with titanium yielding greater n-type behavior and calciurn p-type behavior. Reduction studies of hematite to magnetite in CO-CO2 atmospheres between 600° and 900°C initially exhibited linear kinetics. These linear rates were increased by additions of titanium and decreased by calcium. IN recent years many studies have been reported in the literature on the kinetics of the reduction of hematite and magnetite to iron. In addition, Hansen and Josephl and Schenck and Schultz2 have reported studies on the reduction of hematite to magnetite, the first step in total reduction to iron. In order to evaluate the results of the studies of over-all reduction in terms of the actual mechanism of the reaction and to define further the important factors in the rate- controlling mechanism of the magnetic roasting reaction, the following experiments were undertaken. Specimens of undoped hematite and hematite containing titanium or calcium in solution as doping agents were reduced to magnetite in CO-CO2 mixtures. In addition, electrical-conductivity measurements were correlated with the reduction kinetics using concepts of defect solid-state chemistry. EXPERIMENTAL Fisher certified Fe2O3 powder was used to make specimens for both the electrical and kinetic studies (see Table I for analysis). Doping with titanium and calcium was accomplished by adding TiO2 and CaO powders to the Fe2O3 powder. The powders were mixed in a Waring blender for minimum times of 1/2 hr. Satisfactory blending was achieved based on comparison of analyses of individual specimens af- ter reduction. The specimens were formed in a steel die using opposed punches with a rectangular opening 10.0 by 40.0 mm. The Fe2O3-TiO, platelets were pressed cold at 16,000 psi. They were sintered for approximately 16 hr at 1075°C in air, in accordance with information in the literature3, 4 on the time and temperature needed to obtain solution of the titanium in the hematite. The Fe2O3-CaO mixtures were first cold-pressed at 20,000 psi and sintered for 3 hr at 1225°C to insure solution of CaO. This material was then ground to -325 mesh in a 6-in. ball mill and the resulting powder was used to make platelets in the same manner as above. The sintered platelets were usually between 1/16 and 1/8 in. thick. They were ground on a carborundum wheel and polished on 2/0 paper. Typical dimensions of the kinetic-study specimens were 1.6 by 0.8 by 0.05 cm, and a typical weight was 0.3 g. Conductivity and thermoelectric specimens were approximately the same size, but were subjected to further sintering in order to ensure maximum densification. Finally, all specimens were measured to the nearest 0.0005 in. and weighed on a Mettler H-15 balance to the nearest 0.0001 g and the density calculated. The average density of the specimens used for the reduction studies was 4.87 g per cc, or 7.1 pet total porosity. The standard deviation ranged from 0.14 to 0.063 g per cc within a composition group. In the present study, the apparent surface area as measured with a micrometer was taken as the true surface area. The chemical analyses for calcium and for titanium within a group showed maximum variations of 50.04 pet from the average values used in Figs. 9 and 11. In order to suspend the specimen from the balance for the kinetic studies, a hole, 0.03 in. in

Jan 1, 1965

By A. Long, A. Silverman, J. L. Kulp

Garth Crosby has written an excellent geologic description of the deposits surrounding the Gem stocks in the Coeur d'Alene district. The ore deposits in the area of the Gem stocks may hold the key to the age and mineralization history of the entire Coeur d'Alene district. A recent isotopic study10 of the Coeur d'Alene district in this laboratory illustrates that a classical geologic interpretation of these deposits, with its implications for the whole district, may lead to erroneous conclusions. For this reason it seems pertinent to submit a summary of these results and an interpretation of the mineralizing history of the Coeur d'Alene districts. Pitchblende from the Sunshine mine has been dated as 1100-1200 million years (m.y.) by Kerr and Kulp,11 and Eckelmann and Kulp.12 This pitchblende is known to predate the major sulphide introduction in the Sunshine mine, but it clearly follows the metamorphism and folding of the Belt Series. Recently, Goldich (personal communication) dated sericite from the Belt rocks as 1200 m.y. by the potassium-argon method. This date establishes a minimum Belt age if the sericite is of metamorphic origin and a maximum age if detrital. The Belt Series, therefore, is not latest Precambrian. Lead isotope ratios of galenas have been measured and model ages calculated by Bate, et all3 for the Sunshine mine, Farquhar and Cummingl4 or the Bunker Hill and Sullivan mine, and Cannonl6,18 for a few other deposits in the district. Galenas from similar deposits in Southern British Columbia have been measured by Bate, et al,23 Farquhar and Gumming,11 and Wanless and Leech." The new work in this laboratory includes leads from ten widely scattered mines north and south of the Osburn fault, and through a vertical distance of over 5000 ft (Star mine). Included in this group are the Hercules, Sunset, and Mountain Goat mines, which are adjacent to the Gem stocks. In addition, galenas from stringers which cut the Gem stocks in the Success and Sunrise mines and the Hercules hanging wall dike in the lower western portion of the Hercules mine, were included in the study. All of the above leads, except one, give model ages of 1300-1400 m.y. for the time of segregation from the parent material. The concordance of the common lead and U-Pb ages, the great horizontal and vertical uniformity of the lead ratios, the sulphur ratios of two Sunshine mine galenas and three galenas from the Edith, Page, and Hercules mines indicating average crustal sulphur, and the U23/Pb204 ratio inferred for the original lead environment, indicate that the entire mineralization of the Coeur d'Alene-British Columbia base metal belt was derived from a deep source and emplaced in the Precambrian. One sample of galena from sulphide stringers cutting the North Gem stock at the Sunrise Prospect mine gave a modern (i.e., Tertiary) lead ratio. This mine is located at the northern tip of the stock. The presence of modern lead suggests mobilization of some rock lead during the intrusion of the Gem stocks and their outliers. Larsen et al.l8 have dated the Gem stocks as Tertiary by the lead alpha method. If Coeur d'Alene mineralization was genetically related to Tertiary magma formation and intrusion

Jan 1, 1961

By Herbert H. Kellogg

C. M. Decroly (University of Brussels, Belgium) — The importance of the fluorides in the process metallurgy of special metals has already been accepted and it will probably increase in the future. Free energy diagrams as such established by Professor Kellogg are therefore very useful. It is interesting to note that the absolute value of the standard free energy of formation of HF increases with temperature, whereas for almost all the other fluorides it decreases; consequently it should be theoretically possible to reduce all the fluorides of the metals which, at low temperature, have a greater affinity for fluorine than hydrogen by this last element, provided a sufficiently high temperature is used in order to have a good efficiency. However, with regard to the reduction of UFe by hydrogen, I doubt that it will be possible to obtain directly the metal at comparatively low temperatures. There are other uranium fluorides which are more stable than UF6 and it is very likely that such fluorides will be obtained first. For example, in considering the reaction: UF6gas + H2gas + UF1so1id + 2 HFgas it is found, using the thermodynamic data of Brewer et al, that ?H298 = —66 kcal and ?G°298, = —65.2 kcal. As a result, the reduction of UF6 to UF4solld should proceed spontaneously even at ordinary temperature. On the other hand, the standard free energy of formation of UF4solid at 298°K is AG°298 = -209 kcal per mol of F2. The reduction of UF4 by hydrogen will be practically difficult and, as it is known, the only practical way of reducing this compound is to use alkaline-earth metals such as calcium or magnesium. I should like to point out, further, that the fluorination of many metal oxides can be carried out very easily by using the ammonium difluoride method of preparation, which renders the use of fluoride gas unnecessary. The first compound formed is generally a double fluoride of the metal and ammonium. This compound can be decomposed by heating either in a vacuum or in an inert atmosphere, ammonium fluoride being volatilized leaving the metal fluoride in a very pure state. H. H. Kellogg (author's reply)—Professor Decroly is quite right in pointing out that the formation of lower halides of uranium may complicate the reduction of UF6 by H2. I was unable to find his reference to the free energy of formation of UF4 in the compilation of Brewer.13 however. The value of AG°298, = —209 kcal for formation of ½ UFa seems rather high, and I hope the source of this value may be made clear.

Jan 1, 1952

By R. J. Sherman, M. R. Achter

Creep rates have been measured for nickel at 1200°F in air and in vacuum, and related to the depth of surface cracks in the specimens tested in the two environments. The surface cracks were observed to grow faster in air than in vacuum in both short-time and long-time tests. Crack depths, however, could be correlated with creep rates only in the short-time tests. Although no cracks were observed in a relatively brittle Ni-Cr-A1 alloy creep tested at 1300°F, the appearance of alloy specimens fractured after interruption in creep indicated that there was a decrease of intergranular cohesion resulting from the diffusion of atmospheric gases into grain boundaries. PREVIOUS investigations1-3 have demonstrated that the effect of atmosphere on the high-temperature strength of nickel and nickel-base alloys may be reversed by changes in the stress or temperature of the test. At high stress and low temperature the creep-rupture life is longer in vacuum than in air, while at high temperature and low stress the relative strengths are reversed. A mechanism to explain this behavior was proposed based on two competing processes. Oxidation hardens and strengthens a metal, but adsorption of gas, by lowering surface energy, reduces the work required to propagate an intergranular crack. The controlling process is determined by temperature and stress. Basic to this mechanism is the concept that environment determines the ease of propagation of intergranular cracks and thus affects creep rate and rupture life. To explore the mechanism in greater detail, this investigation was undertaken to determine the effect of atmosphere on crack initiation and propagation rates in nickel1 and a relatively brittle Ni-Cr-A1 alloy.3 EXPERIMENTAL PROCEDURE The materials were the same as used previously. Nickel of 99.8 pct purity had the following impurity content: 0.02 pct Co, 0.03 pct Fe, 0.02 pct Mg, 0.03 pct Si, and 0.008 pct C. Rods were cold swaged from 1/2 in. to 3/8 in. in diam and machined into speci- mens with gage sections 1/4 in. in diam by 1-1/4 in. long. They were annealed in vacuum at 1600" F for 1 hr to achieve a grain size of 0.07 mm. The alloy was composed of 19.1 pct Cr, 3.6 pct Al, 1.7 pct Si, 0.57 pct Fe, 0.10 pct Mg, 0.027 pct C, 0.004 pct S, and the balance Ni. Sheet specimens of 0.500-in. width and 1.25-in. gage length were machined from 0.033-in.-thick strip and annealed in vacuum at 2000° F for 2 hr, resulting in a grain size of 0.036 mm. Large amounts of an intergranular phase were introduced as a result of the anneal. Creep tests on both materials, using equipment previously described by Shahinian; were conducted in air and in a vacuum of 1 x 10-5 mm Hg. They were continued to rupture and interrupted at various stages of the test. Although extensions were measured from dial gage readings of movement of the lever arm, it is considered that valid comparisons of creep rate may be made in this manner.l Two parameters were measured metallograph-ically* on longitudinal sections of nickel specimens interrupted during creep—the mean depth of surface cracks 2, and the density n as the number of cracks per unit length of surface. They were combined into one parameter by the relation p = n-d [1] As used here, p is equal to the total of crack depths per unit length of surface. RESULTS Nickel. It is well known that the incidence of intergranular cracking is increased with increasing rupture life. Indeed, it is evident in Tables I and I1

Jan 1, 1962

By A. Hultgren, G. Phragmén

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939

By G. Phragmén, A. Hultgren

Page Outline of Progress of Knowledge and Theories about Gas Evolution in Steel Ingots. and Its Influence on Crystallization and Segregation................ 134 Object of Present Investigation........................................... 148 Theoretical Discussion of Process of Solidification........................... 149 Gas Given Off from Rimming Steel during Solidification................... 149 Equilibrium Diagram of the Iron-carbon-oxygen Alloys................... 151 Solidification of Pure Iron-carbon-oxygen Alloys.......................... 157 Solidification when Carbon Monoxide Is Given Off at Constant Pressure... 157 Solidification when Gas Evolution Is Suppressed....................... 158 Schematic Application on Solidification of Rimming-steel Ingots.......... 159 Influence of Manganese, Sulphur and Phosphorus......................... 160 Experimental work..................................................... 162 Liquid Steel and the Mold Gas......................................... 162 Ingots Investigated and Methods Used.................................. 165 Ingot structure....................................................... 174 Structure of Rim Zone.............................................. 174 Structure of Core................................................... 181 Structures Obtained under Special Conditions of Freezing................ 182 Distribution of Metalloids............................................. 187 Other Observations Made............................................. 192 General Discussion of Solidification Process................................. 195 Condition of Liquid Steel before Casting................................. 195 Rimming Period...................................................... 202 Composition of Rim Zone............................................. 225 Freezing after Top Is Closed........................................... 228 Slag Inclusions and Ingot Scum........................................ 234 Reaction between Gas in Blowholes and Surrounding Solid Steel during Cooling 235 Summary.............................................................. 237 Appendix—Preparation and Etching of Ingot Sections....................... 238 References............................................................. 239 In 1934, Jernkontoret (The Swedish Ironmasters' Association) appointed a committee for the study of the structure of rimming-steel ingots and the various phenomena associated with their solidification. The members of the committee, including those who have joined it later, have been: I. Bohm, B. D. Enlund, B. Kalling, M. Tigerschiöld, S. Wohlfahrt and the authors. The present paper‡ is a somewhat

Jan 1, 1939

By Howard H. Fields

Any mining engineer with a desire to operate independently, with some financial backing, and with no fear of heavy responsibility and long hours, should be able to make a comfortable living in Mexico. Barring a few inconveniences such as a lack of satisfactory liability or accident insurance, the difficulty of obtaining repair parts for vehicles, and the length of time required receive returns from shipments, the operation of a small mine is not at all difficult. It is, in fact, a little easier to find a good prospect in Mexico than in the U.S.

Jan 11, 1950

By K. L. Clark, Nicholas Kowall

MAXIMUM furnace efficiency and close control of final steel composition demand that the steel melter be able to follow closely the variations in the carbon content of the bath. For many years, the fracture test has been used by melters for estimating carbon, because it requires only a very short time to pour a sample into a chill mold, cool it in water, break it with a sledge hammer, and observe the fracture. After long experience gained from the observation of such fractures, most melters are able to estimate the carbon content of steel with amazing accuracy, particularly in the lower carbon ranges. Notwithstanding the utility of the fracture test, there has been widespread interest in other methods for rapid carbon determination to supplement it and to ensure against possible errors in human judgment. Several methods, based upon measurement of magnetic properties as functions of carbon content, have been described in the literature1-6 and have been found to give reasonably reliable results in plant practice when scrap composition is known and controlled. A difficulty encountered in the use of analyzers of the magnetic type is that alloying elements do change the relationship between carbon content and magnetic properties and it becomes necessary to establish calibration curves for all the expected combinations of alloy residuals that are not oxidized in the bath. The work reported here is of an investigation of a method that is independent of alloying elements normally present in constructional steels, being based upon the relatively well-known fact that in plain carbon and low-alloy steels martensitic hardness is a function of carbon content alone. WORK OF OTHER INVESTIGATORS In 1938, Burns, Moore and Archer published a curve7 that showed that the hardness of martensite is a function of carbon from 0.10 to 0.50 per cent and is independent of grain size or alloy content, at least within the range found in constructional S.A.E. compositions. Some of the deeper hardening types investigated, however, contained carbon to a maximum of only 0.20 per cent. Using this principle, Kern8 developed a method of rapid carbon determination for S.A.E. 43xx steels. His procedure consisted of chill-casting a test bar that was large enough to give a surface that could be prepared for Brinell indentations. The test piece was quenched immediately after solidification was complete and hardness readings were taken, so that the carbon content could be read from an experimentally determined curve giving the relationship between as-quenched hardness and carbon. EXPERIMENTAL WORK Although Kern's work had been done with a relatively deep-hardening steel, it

Jan 1, 1944

Silver ore was first discovered in 1866 at Manhattan, and a few ore shipments were treated in a mill at nearby Belmont. The district was abandoned from 1869 to April 1, 1905, when rich gold float was discovered on what was to be called the April Fool claim. By early 1906, 4, 000 people lived in Manhattan. The San Francisco earthquake, in April of 1906, caused the withdrawal of capital from Manhattan and most of the mines were shut down. Later that year and in 1907, however, more strikes were made. The camp prospered until the mid-1920s, but a steady production of several hundred thousand dollars per year was sustained even during the great depression. Then, in 1939, Nevada's first bucket-line dredge was installed below the town and operated until 1947, producing $4.6 million in gold. The Houston International Minerals operation at Manhattan was started in July of 1980 at a throughput of about 545 mt per day (600 st per day). In contrast to the early day underground operations, Houston's mine is open-pit and processes low-grade disseminated ores. The ore is a metamorphic schist containing 2. 7 g Au and 1. 03 g Ag per mt (0. 08 oz Au and 0. 03 oz Ag per st). Some coarse gold, up to 1 mm in size, is present. Mining and haulage is done by a contractor. Stockpiled mine-run ore is crushed in three stages comprising a jaw crusher and two cone crushers, with screens ahead of the cone crushers. Crushed product, at about 19 mm (3/4 in.) size, is stored in a silo. Grinding is by single stage ball mill with the discharge passing over two hydraulic traps for coarse gold removal. These traps will be replaced in late 1980 by a two-cell Pan American jig treating the cyclone underflow. The jig hutch product, along with the hydraulic trap product that has been stored, will be treated further for gold recovery. The gravity tails will then be cycloned with the underflow being recirculated in the ball mill and the overflow being treated by flotation. A rougher concentrate is made in twelve No. 48 Galigher cells with the float tails being cycloned. Cyclone underflow is refloated in another four No. 48 cells; the overflow is treated in sluice boxes for further gold recovery before being sent by gravity to the tailings pond. Bulk flotation concentrates are cleaned three times with the final concentrate being thickened. The thickener underflow is then batch cyanided in mechanically agitated tanks and washed with barren liquor

Jan 1, 1981

By Leo H. Glanville

Until 1934, natural ventilation was depended upon in the mine of the Climax Molybdenum Co. at Climax, Colorado. In that year a 7-ft. axial-flow, low-pressure fan was installed as an exhausting unit. In 1936, three more fans of the same kind were installed, all as exhausting units, with a total capacity of 115 000 cu, ft. per min., and since then fans and sprays have been added as required. Atmospheric Conditions Adverse atmospheric conditions at this elevation of 11,500 ft. account in part for difficulty in maintaining adequate ventilation throughout the mine. Barometric pressures range from 18.99 to 20.01 in. of mercury; the norma1 average being 19.70 in. Air weight is 0.051 lb. per cu. ft., and humidity is low—about a 30 per cent yearly average. This makes the use of mechanical humidity aids mandatory the Year around to prevent excessive dryness of the mine workings and the resultant dust hazard. The yearly temperature range is from minus 24" to 75°F.; typically, in February 1942 the mean low was minus 3.25°F. and the mean high, 21.3°F. In August the mean low was 34.8°F.; the mean high, 64.26°F. Even during the summer month air filtration through the openings of the cave area is 32°F., owing to accumulation of snow in the glory hole and in Part to glacial ice, which, combined with a rock temperature of 39°F. on the upper levels (elevation 11,945 ft.) and 42°F. on the main haulage level (elevation 11,470 ft.], makes it difficult to maintain a comfortable working temperature. The one advantage in ventilation of mine workings at the altitude of the Climax mine is that the power required to circulate a given air volume is 32 per cent less than would be required at sea level. Problems since 1936 the mine management has studied intensively plans for providing adequate ventilation for the entire mine for its expected life. As the ore breaks into large pieces, much secondary blasting is necessary, therefore there is a considerable amount of smoke, gas and dust, which requires circulation of a large amount of air to remove the contamination, It is undesirable to use haulage drifts and manways as air passages because some would be passageways for contaminated air also, and there would be undesirable high velocities in some drifts. High velocities and large volumes of subfreezing air dry out the passageways through which they pass, and thus increase the amount of dust. Regulating doors in haulage drifts are difficult of upkeep and interfere with production. It was decided as a general principle to distribute fresh air to each working place at low velocities and low pressures and to remove contaminated air as soon as possible with a minimum of travel through working places.

Jan 1, 1943

By Leo H. Glanville

Until 1934, natural ventilation was depended upon in the mine of the Climax Molybdenum Co. at Climax, Colorado. In that year a 7-ft. axial-flow, low-pressure fan was installed as an exhausting unit. In 1936, three more fans of the same kind were installed, all as exhausting units, with a total capacity of 115 000 cu, ft. per min., and since then fans and sprays have been added as required. Atmospheric Conditions Adverse atmospheric conditions at this elevation of 11,500 ft. account in part for difficulty in maintaining adequate ventilation throughout the mine. Barometric pressures range from 18.99 to 20.01 in. of mercury; the norma1 average being 19.70 in. Air weight is 0.051 lb. per cu. ft., and humidity is low—about a 30 per cent yearly average. This makes the use of mechanical humidity aids mandatory the Year around to prevent excessive dryness of the mine workings and the resultant dust hazard. The yearly temperature range is from minus 24" to 75°F.; typically, in February 1942 the mean low was minus 3.25°F. and the mean high, 21.3°F. In August the mean low was 34.8°F.; the mean high, 64.26°F. Even during the summer month air filtration through the openings of the cave area is 32°F., owing to accumulation of snow in the glory hole and in Part to glacial ice, which, combined with a rock temperature of 39°F. on the upper levels (elevation 11,945 ft.) and 42°F. on the main haulage level (elevation 11,470 ft.], makes it difficult to maintain a comfortable working temperature. The one advantage in ventilation of mine workings at the altitude of the Climax mine is that the power required to circulate a given air volume is 32 per cent less than would be required at sea level. Problems since 1936 the mine management has studied intensively plans for providing adequate ventilation for the entire mine for its expected life. As the ore breaks into large pieces, much secondary blasting is necessary, therefore there is a considerable amount of smoke, gas and dust, which requires circulation of a large amount of air to remove the contamination, It is undesirable to use haulage drifts and manways as air passages because some would be passageways for contaminated air also, and there would be undesirable high velocities in some drifts. High velocities and large volumes of subfreezing air dry out the passageways through which they pass, and thus increase the amount of dust. Regulating doors in haulage drifts are difficult of upkeep and interfere with production. It was decided as a general principle to distribute fresh air to each working place at low velocities and low pressures and to remove contaminated air as soon as possible with a minimum of travel through working places.

Jan 1, 1943

By R. J. Murphy, N. J. Grant, J. W. Dowding

A large number of blast furnace slag-metal tests were examined to determine if the manganese reduction could be used as a primary indicator of the degree of oxidation or reduction of the slag and of its desulphurizing power. Slag basicity and temperature were also evaluated. Two laboratory heats were made and sampled prior to reaching equilibrium to check blast furnace data. IN a recent investigation of the factors affecting desulphurization in the blast furnace, is was evident that manganese reduction appeared to parallel the course of desulphurization. Grant, Kalling, and Chipman1 pointed this out in a series of time studies utilizing closely controlled laboratory melts. Fig. 1 is a composite plot of sulphur removal and manganese reduction as a function of time under two slags of different basicity. Manganese reduction appears to approach equilibrium at approximately the same rate as does sulphur. It was also demonstrated that the addition of oxygen to the slag, as manganese oxide, caused a sharp reversal of sulphur from the slag to the metal.' It has been shown that "Excess CaO" was a primary factor in measuring the degree of desulphurization under ideal reducing conditions,1,2 the following reaction being representative of the process: CaO (slag) + S + C (solid) = CaS(slag) + CO (gas) It was also evident that a second reaction could drive the sulphur from the slag into the metal. A suggested reaction was' CaS (slag) + 0 = CaO (slag) + S Any change in the oxidizing power of the system would thus affect both the sulphur and the manganese without causing any change in the calculated basicity of the slag. "Excess CaO," "Excess Base," and other similar basicity values, under such oxidizing conditions, would therefore not be the best measure of desulphurizing power; instead, as was shown by and Chipman" he oxygen content of the slag at low oxygen levels would be the controlling factor. Unfortunately, the extent to which FeO is reduced in the blast furnace makes it difficult to utilize slag FeO as an accurate indicator of the degree of oxidation. By comparison, manganese reduction in the blast furnace proceeds more slowly and is generally only about 40 to 70 pct complete. manganese, which is present in significant amounts and is readily analyzed, offers an opportun-

Jan 1, 1954