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By S. L. Craig, C. Orr, H. G. Blocker

WITHIN recent years gas adsorption methods have been developed for measuring the surface area of finely divided materials and have become extremely valuable in research on the corrosion and the catalytic activity of metals. Rather elaborate apparatus is required, and a single determination is so time-consuming that these methods have not been utilized to the fullest extent; the methods are un-suited for most routine control work such as that encountered in powder metallurgical operations and in processes employing metal catalysts. These difficulties are largely eliminated, and surface area is reduced to a routine determination if the liquid-phase adsorption of a surface-active agent such as a fatty acid can be used. When the affinity of the fatty acid carboxyl group for the solid surface is greater than its affinity for the solvent, a unimolec-ular layer of orientated fatty acid molecules will be formed at the solid-liquid interface in a manner similar to that of a compressed fatty acid film on a water surface. The measurement of surface area is then reduced to a measurement of fatty acid adsorption. This propitious circumstance, first investigated by Harkins and Gans,¹ has been employed with somewhat inconclusive results by a number of investigators in evaluating the surface properties of metals, metal catalysts, and metal oxides. The specific surface area values for nickel and platinum catalysts, determined from the adsorption of a number of fatty acids from various solvents, were found by Smith and Fuzek² to agree with values calculated by the gas adsorption technique of Brunauer, Emmett, and Teller," he so-called BET technique. And recently Orr and Bankston4 have also reported good agreement between nitrogen gas and stearic acid adsorption results in the measurement of the surface areas of clay materials. On the other hand, Ries, Johnson, and Melik5 found only order-of-magnitude agreement between these two methods in studying supported, cobalt catalysts having specific surface areas as great as 420 sq m per g; the reason is partially attributable to the very porous nature of the materials. Greenhill,6 investigating the adsorption of long-chain, polar compounds in organic solvents on a number of metal powders, concluded that a uni-molecular layer of stearic acid was formed on exposure of the solid to the acid solution and that the presence of an oxide or another film did not alter this result. Furthermore, the adsorption process appeared to be the same whether or not the sample was degassed prior to exposure to the solution. Greenhill estimated the surface area of one of the powders he investigated from microscopic diameter measurements, and obtained a rough check with surface area evaluation. Russell and Cochran7 found moderate agreement for alumina surface area results by fatty acid and gas adsorption methods. In addition, they also found that the prolonged heating and evacuating pretreatments previously used by investigators were unnecessary. The present work, however, considerably extends these previous investigations, shows that fatty acid adsorption can be used to determine the surface area of a variety of metals and metal compounds, offers further confirmation of the correctness of gas adsorption methods, and presents a simplified technique for the determination of the metal surface area which is suitable for routine work. Experimental Technique Basically, the fatty acid adsorption method is quite simple. It consists of exposing a sample of the material of which the surface area is desired to a fatty acid solution of known concentration. By analysis of an aliquot of the solution, the concentration after adsorption has occurred may be determined. The difference between the initial quantity of acid in solution and the final quantity is that quantity of acid adsorbed by the sample. The specific surface area of the adsorbent material may be calculated from the quantity adsorbed and the weight of the sample. In agreement with the findings of others as outlined above, it was found entirely unnecessary to degas or pretreat the nonporous materials employed other than by drying them thoroughly. However, precaution was necessary so that the dried sample entered the fatty acid solution with little exposure to moisture. The effect of moisture on the interaction of stearic acid with finely divided materials has been thoroughly investigated by Hirst and Lancaster." They found the presence of water merely reduced the amount of acid adsorbed by powders such as TiO2, SiO2, Tic, and Sic. With reactive materials such as Cu, Cu2O, CuO, Zn, and ZnO, however, water was found to initiate chemical reaction. Only with ZnO was reaction observed when the solid and the solu-

Jan 1, 1953

By R. V. Ramani, Robert Stefanko

The more stringent ventilation requirements of the 1969 Act have created a greater need for improved network analyses. More air is required at the last open crosscut (9000 cfm) and for the first time a minimum quantity is specified for the face (3000 cfm). Severe restrictions are placed on both belt and track haulage, and the intake air cannot contain more than 2 mg per cu m of respirable dust, to be reduced to 1 mg later. Larger tonnage and longer life mines are the trend today, necessitating multiple fans and shafts. Yet relatively little engineering goes into designing the mine ventilation system. In this paper a ventilation system is designed for a typical Pittsburgh block system, manual calculations are made and then checked by a computer solution. The computer is the ideal tool to try out proposed changes on paper to insure that the entire mine is properly ventilated and no costly adjustments need be made by dumping air. While it is theoretically possible to solve complex ventilation network problems by hand, it is not practical to do so because of the tremendous man-hours required and the many opportunities for errors. Thus the digital computer is indispensible to the ventilation engineer and newer improved ventilation programs are being developed to more realistically model mine ventilation networks. Suggested ventilation changes to comply with the new regulations are also critically evaluated.

Jan 1, 1973

By R. R. Brandenthaler

Petroleum producers in the Mid-Continent field, up to the present time, have been more concerned with the mechanical operation and efficiency of the gas-lift than with its possible effects on the physical properties of the oil. As a result few specific data are available on the subject and contradictory opinions exist. Some operators are positive that the gravity of the oil is decreased, while others present data which definitely show that the gravity of the oil is increased. In other localities, some operators have given careful attention to the effect of the gas-lift on the gravity of the oil. When the emulsions formed have given much trouble, the problem has usually been dodged by placing the well on the pump. Certain Fundamentals Certain fundamental results may be expected under ordinary conditions and with all types of crude oil, when gas is the prime mover of oil in producing formations. For example, the gravity of oil will decrease as the rock pressure in the producing formation declines, the change being greater in the higher gravity oils. Furthermore, the character of emulsion formed is primarily dependent on the kind of oil, thus more refractory emulsions are formed from asphaltic-base oils, less refractory from mixcd-base oils, and the least refractory from paraffin-base oils. However, refractory emulsions are sometimes formed from paraffin or mixed-base oils that are difficult to treat by ordinary methods, especially by electrolytic processes. With oils having the same base, those of lighter gravity are less subject to the formation of emulsions, especially of refractory emulsions. There are two types of emulsions formed; namely, water-in-oil emulsions and oil-in-water emulsions. The former are the more common; in fact, very few examples of oil-in-water emulsions have been noted in the oil fields. The amount of water produced with the oil influences the percentage of emulsion formed. Agitation and velocity of flow play an important part in the forming of emulsions.

Jan 1, 1928

By A. J. Shaler, J. Prieto Isaza, J. Wulff

Tantalum metal has a number of unique properties which give it widespread application in modern technology and in research. In electronic apparatus involwing high temperatures in vacuo some of the refractory metals 6ecome brittle. Tantalum retains its ductility at elevated temperatures, and this property, together with its low vapor pressure and its ability to absorb gases, make it important in this field. Its chemical inertness in the presence of acids, halogens, and other corrosive media, makes it useful in chemical apparatus and in neuro and orthopedic surgical applications. As an addition to tungsten carbide in steel-cutting grades of cemented-carbide tools, the carbides of tantalum and of its sister element colum-bium have found considerable use. The present-day method1 of manufacturing tantalum is to sinter a powder compact of the metal in vacuo. Because tantalum-columbium alloys are difficult to work and since tantalum ores almost always contain columbium, the two metals must be separated chemically, the products of the separation being generally in the form of potassium tantalum fluoride and potassium columbium oxyfluoride. These salts are used in fused-salt electrolytic baths from which coarse metallic powder is deposited as a sponge at the cathode. Finer powder can be made from the coarse product or from tantalum scrap by first submitting it to an embrittling heat treatment in hydrogen and then crushing it. The fine hydrogen-containing powder may subsequently be degassed in vacuo at a high temperature. Prompted by the success of others2,3 in the magnesium reduction of titanium and zirconium halides; one of the authors undertook4 an investigation of the thermochemistry of the reaction between solid magnesium and gaseous tantalum penta-chloride, a subject which had not previously been studied. He found that the heat of formation of tantalum pentachloride is approximately 364,250 cal per mol at temperatures lower than the melting point of magnesium. A value of 83 units was found for the standard entropy at these temperatures. With these values, it was shown that magnesium and tantalum pentachloride are capable of reacting exo-thermically at temperatures less than the melting point of magnesium, and that no great violence is to be expected when these substances are heated together. The exothermic nature of the reaction indicated that the Drocess should be efficient and should not require much externally applied energy. Tantalum pentachloride is not commonly made commercially, and any process using it therefore involves the subsidiary problem of producing and handling this substance. A series of experiments was carried out in which dried chlorine saturated with carbon tetrachloride was passed over heated tanta-

Jan 1, 1949

By R. P. Fischer

A large production of vanadium during the war helped Germany to meet her critical requirements for the ferroalloy metals. Vanadium was needed not only in the ordinary high-speed too1 steels, but in other as a substitute for chromium, nickel, and molybdenum, which were scarce. Lacking a source of vanadium ore, however, the vanadium was obtained as a by-product of the steel industry—va-nadium-bearing pig iron smelted from iron ores containing about o. I per cellt V was blown in converters to yield vanadium-rich slag, from which vanadium was recovered by chemical treatment. The production capacity obtained was said to be about 6,500,000 lb. of vanadium a Year. Although the general Processes of Preparing vanadium-rich slags as well as the recovery methods described herein are known, some of the details presented may be of interest to both the American steel industry and the vanadium producers. No adequate data on the cost of the vanadium produced in Germany are known, but it seems likely that the cost exceeds the commonly quoted domestic price of about $1.10 per pound of contained VzOa. Information on the German vanadium production was obtained by a team of geologists from the Geological Survey* United States Department of the Interior, during investigations in May and June 1945 of the German utilization of low-grade raw materials. These investigations were sponsored by the Chief of Engineers, War Department. It is a pleasure to acknowledge the aid obtained from Messrs. H. C. Smith and J. D. Dickerson, investigators assigned to the Army Ordnance section of C.I.O.S., and Mr. C. F. Park, Jr., of the Geological Survey team. The data on vanadium recovery from iron ores were obtained from the Kaiser Wilhelm Institut fiir Eisenforschung, the Hermann Goring steel plant at Watenstedt, and from notes made by other investigators at other German steel plants. Preparation of Vanadium-rich Slags Most German iron ores contain only about 0.1 per cent vanadium, or even less, but some of the scandinavian iron ores available to the German iron industry in the past contain a little more than 0.1 per cent. In general German practice of vanadium recovery, nearly all of the vanadium in the ore goes into the pig iron, which is blown in the Thomas converter, yielding a slag containing about I per cent V. This slag is remelted, the vanadium again going with the iron, which is again blown in a converter, yielding a slag that averages about 10 per cent V. This slag is treated at special chemical plants, by the process of a sodadizing roast, water leach, and acid precipitation of vanadium oxide. The Herman Goring steel plant at Watenstedt used the low-grade Salzgitter iron ores, the average composition of which is shown in Table I, column I. The acid and basic iron produced in the blast furnaces contained about 0.3 per cent V. A Thomas

Jan 1, 1948

By R. P. Fischer

A large production of vanadium during the war helped Germany to meet her critical requirements for the ferroalloy metals. Vanadium was needed not only in the ordinary high-speed too1 steels, but in other as a substitute for chromium, nickel, and molybdenum, which were scarce. Lacking a source of vanadium ore, however, the vanadium was obtained as a by-product of the steel industry—va-nadium-bearing pig iron smelted from iron ores containing about o. I per cellt V was blown in converters to yield vanadium-rich slag, from which vanadium was recovered by chemical treatment. The production capacity obtained was said to be about 6,500,000 lb. of vanadium a Year. Although the general Processes of Preparing vanadium-rich slags as well as the recovery methods described herein are known, some of the details presented may be of interest to both the American steel industry and the vanadium producers. No adequate data on the cost of the vanadium produced in Germany are known, but it seems likely that the cost exceeds the commonly quoted domestic price of about $1.10 per pound of contained VzOa. Information on the German vanadium production was obtained by a team of geologists from the Geological Survey* United States Department of the Interior, during investigations in May and June 1945 of the German utilization of low-grade raw materials. These investigations were sponsored by the Chief of Engineers, War Department. It is a pleasure to acknowledge the aid obtained from Messrs. H. C. Smith and J. D. Dickerson, investigators assigned to the Army Ordnance section of C.I.O.S., and Mr. C. F. Park, Jr., of the Geological Survey team. The data on vanadium recovery from iron ores were obtained from the Kaiser Wilhelm Institut fiir Eisenforschung, the Hermann Goring steel plant at Watenstedt, and from notes made by other investigators at other German steel plants. Preparation of Vanadium-rich Slags Most German iron ores contain only about 0.1 per cent vanadium, or even less, but some of the scandinavian iron ores available to the German iron industry in the past contain a little more than 0.1 per cent. In general German practice of vanadium recovery, nearly all of the vanadium in the ore goes into the pig iron, which is blown in the Thomas converter, yielding a slag containing about I per cent V. This slag is remelted, the vanadium again going with the iron, which is again blown in a converter, yielding a slag that averages about 10 per cent V. This slag is treated at special chemical plants, by the process of a sodadizing roast, water leach, and acid precipitation of vanadium oxide. The Herman Goring steel plant at Watenstedt used the low-grade Salzgitter iron ores, the average composition of which is shown in Table I, column I. The acid and basic iron produced in the blast furnaces contained about 0.3 per cent V. A Thomas

Jan 1, 1948

By M. Prats, D. G. Russell

The performance of a well in a bounded, layered reservoir with interlayer crossflow has been investigated mathematically. The system studied comprises a centrally located well in a bounded cylindrical reservoir composed of two layers of contrasting physical properties. The reservoir contains a single fluid of small and constant compressibility. In the case of a well producing at constant pressure, the production rate of the crossflow system declines exponentially after the early transient behavior dies out. For wells which produce with constant rate, the pressure-time relationship is linear following the transient. For very early production time, the production rate of the two-layer crossflow system behaves as that of the two-layer stratified system (the case in which the layers are in communication at the well only). Except for early time, in most practical cases the performance of a two-layer reservoir with cross-flow can be duplicated by that of a single-layer reservoir. The equivalent single-layer reservoir must have the same pore volume and the same drainage and wellbore radii as in the two-layer case. In addition, the equivalent reservoir must have a "kh" (permeability x thickness) product equal to the sum of the "kh" products of the respective layers in the crossflow system. If the porosity and permeability distributions are known, the production and pressure behavior of a well with and without crossflow can be predicted. From a comparison of the observed pressure or production performance of a well and the theoretical behavior, the occurrence of interlayer crossflow can be detected. INTRODUCTION When flow is possible across the bedding plane from a low-permeability layer into an adjacent layer of moderate or high permeability, the earlier depletion of the more permeable layer will cause such flow to occur. If this situation exists, the oil recovery from tight layers can be appreciable; thus, the economic ramifications of interlayer crossflow are apparent. The possible importance and extent of flow between adjacent and connected layers — whether resulting from capillary, gravitational, or viscous forces — have been the subject of considerable speculation for many years. Jacquard1 presented a rigorous analysis of the crossflow due to single-fluid expansion occurring between two adjacent and connected layers when the well produces at constant rate. His presentation was entirely mathematical, however, and no numerical results from evaluation of the mathematical solutions were presented. Our objectives in the preparation and presentation of the present paper are essentially twofold— (1) to analyze the behavior of a well which produces a single compressible fluid from a bounded, layered reservoir with interlayer crossflow, and (2) to present practical numerical results and simplified formulas to facilitate engineering analysis of reservoirs with crossflow. The constant-terminal-pressure case was analyzed rigorously, whereas the constant-terminal-rate case was treated only for semisteady-state conditions. DESCRIPTION OF THE IDEALIZED TWO-LAYER RESERVOIR The reservoir to be studied is assumed to be bounded and cylindrical in shape, with a completely penetrating well at its center. The reservoir is composed of two adjacent horizontal layers between which fluid is free to flow. Each layer is assumed to be homogeneous, isotropic and completely filled with a fluid of small and constant compressibility. The total thickness of the reservoir is small enough

By David A. Thomas, John F. Peck

Fibrous microstructures and their development have been studied by metallography and by hardness and quantitative metallographic measurements. Thin, curved grains were observed in transverse sections of commercial tungsten wire and were developed in laboratory-drawn iron wire at reductions greater than about 70 pct. The unusual grain shapes are attributed to the nonuniform mode of deformation of the grains associated with the characteristic [I101 preferred orientation that develops in bcc metals during drawing. Transverse sections of heavily swaged iron wire showed a ospiral nebulao structure that appears to result from the elliptical shape of the cross section of the swaging dies and their rotary motion. Hardness and quantitative metallographic results show unusual trends that parallel the changes in microstructure. Other phenomena are considwed in light of the results, including the strength of fine wires of bcc metals, ocylindricalo textures, and the ductility of fibrous tungsten. 1 HE microstructure of tungsten wire in a longitudinal section shows grains highly elongated in the working direction, giving the appearance of a bundle of parallel fibers, Fig. l(a). Wires of tungsten and other bcc metals show a pronounced preferred orientation in which a [I101 direction is parallel to the wire axis.l The microstructure and texture of tungsten develop during warm working (working above room temperature but below the recrystallization temperature) into wire by swaging and drawing. Fibrous tungsten so produced has limited but useful room-temperature ductility, whereas annealed tungsten is brittle at room temperature. During an investigation of the effect of recovery annealing on the substructure of commerical 0.030 in. diam tungsten wire, it was found that transverse sections of the as-received material showed thin, curved grains, Fig. 1(b), instead of the expected equiaxed grains. The fact that Figs. l(a) and (b) show different sections of the same material at the same magnification is at first disconcerting, because the long dimension of the curved grains in the transverse section is several times the average fiber width in the longitudinal section. However, a longitudinal section cuts most of the curved grains across their narrow dimension, giving the appearance of a multitude of narrow fibers. On the other hand, the plane of a longitudinal section occasionally includes a long dimension of a curved grain, resulting in a broad ofibero, such as A in Fig. l(a). EXPERIMENTS AND RESULTS To investigate the origin of fibrous microstructures and particularly the unusual transverse-section structure of tungsten, rods of iron (also bcc) were drawn and swaged in the laboratory. One rod of annealed Ferrovac E was drawn in six steps to a total reduction in area of 87 pct (0.10 to 0.036 in. diam), and a second rod was swaged to the same reduction, using approximately the same reduction steps. Longitudinal and transverse sections of the swaged and drawn iron wires are shown in Fig. 2, for reductions in area of 39, 73, and 87 pct. A fibrous microstructure in longitudinal section is first evident at 73 pct reduction, and it is further developed at 87 pct reduction. The grains in transverse section remain equiaxed until about 73 pct reduction, when they become somewhat elongated and curved. At 87 pct reduction, the drawn wire shows thin, curved grains in the transverse section, similar to those observed in tungsten. The transverse sections of the iron wires swaged 83 and 87 pct reduction in area show the striking ospiral nebulao structure in Fig. 2(d). This struc-

Jan 1, 1962

By Richard H. Jahns

GRANITIC pegmatite deposits are the chief source of commercial feldspar, sheet mica, beryllium, tantalum-columbium, and lithium minerals, and certain types of kaolin. They also have yielded significant quantities of cassiterite, gems, scrap mica, molybdenite, tungsten minerals, uranium-thorium and rare-earth minerals, and zircon, either directly or as the sources of placer deposits. The output from pegmatite mines in the United States is small as compared to other mineral products in terms of bulk or value, and much of it comprises minor metals and nonmetals. Nevertheless, pegmatite minerals play a vital part in domestic industrial economy, particularly in the ceramic and electrical industries. Numerous special purpose uses also are important, even though they require small quantities of raw materials. Never was United States dependence upon pegmatite mining more clearly emphasized than during World War 11, when greatly expanded demands and uncertainties of foreign sources of supply caused much concern. Such commodities as beryl, tantalite, and sheet muscovite remained high on the critical list for months at a time, and for some minerals there was a real struggle to achieve and maintain a favorable ratio of supply to demand. Satisfactory stock piles of certain sizes and qualities of sheet mica, for example, were not built up until late in 1944, when wartime requirements already had begun to level off or even to decrease. Production of all the strategic pegmatite minerals from domestic deposits during World War I1 constituted only 10 pct or less of the total domestic consumption of these minerals, but the importance of this contribution should not be minimized. Domestic production often represented the difference between increase and further reduction of existing stocks of commodities already in seriously short supply, and in the early stages of the war it was the only assured source if imports were cut off. During the recent war period, the U. S. Geological Survey carried on a program of pegmatite studies in the New England and Southeastern States, in the Black Hills area of South Dakota, in the Rocky Mountain region of Wyoming, Colorado, and New Mexico, and in various parts of Washington, Idaho, Utah, Nevada, Arizona, and California as shown in Fig. 1. Several papers and reports already have appeared as an outgrowth of this work,'-= and others are in preparation. This paper outlines some results of data obtained by the writer during the period 1942 to 1946, when he was engaged in studies of pegmatites in the Southeastern, Southwestern, and Rocky Mountain States. Beryllium Minerals Beryl is the present commercial source of beryllium metal and beryllium compounds, which are used in ceramics, in the preparation of X-ray tubes and fluorescent lamps and screens, in special processes of paint and textile manufacture, and in the optical systems of some electrical instruments. The metal also is used in nuclear physics, chiefly as a source of neutrons. Beryllium is alloyed with aluminum for certain light-metal uses and is a constituent of some nickel and iron alloys. Currently the chief demand, however, is for copper-base alloys, which are exceptionally resistant to fatigue and wear, are responsive to hardening treatments after

Jan 1, 1952

By J. Lohrenz, C. R. Clark, B. G. Bray

Procedures to calculate the viscosities of in situ reservoir gases and liquids from their composition have been developed and evaluated. Given a composition expressed in methane through heptanes-plus, hydrogen sulfide, nitrogen and carbon dioxide together with the molecular weight and specific gravity of the heptanes-plus fraction, the procedures are capable of calculating the viscosity of the gas or liquid at the desired temperature and pressure. The procedure for reservoir liquids was developed using the residual viscosity concept and the theory of corresponding states, and was evaluated by comparing experimental and calculated results for 260 different reservoir oils ranging from black to highly volatile. The average absolute deviation was 16 per cent. This is the first known procedure for calculating the viscosity of reservoir liquids from their compositions as normally available, i.e., including the heptanes-plus fraction. The procedure for reservoir gases uses a sequence of previously published correlations. Evaluation of the procedure was accomplished by comparison of 300 calculated and experimental viscosities for high-pressure gar mixtures in the literature. The average absolute deviation was 4 per cent. The calculations are useful for (I) determining viscosities in compositional material balance computations and (2) predicting the viscosity decrease which occurs when gases, LPG, or carbon dioxide dissolve in reservoir oils. INTRODUCTION Methods to predict viscosities of reservoir fluids from the normally available field-measured variables have been presented. Beal,1 Standing,2 and Chew and Connally3 orrelated oil viscosities with temperature, pressure, oil gravity and gas-oil ratio. Carr, Kobayashi, and Burrows4 and Katz et al.5 have presented correlations for reservoir gas viscosities as a function of temperature, pressure and gas gravity. Lie all intensive physical properties, viscosity is completely described by the following function: Eq. 1 simply states that viscosity is a function of pressure, temperature and composition. These previous correlations1- hay be viewed as modifications of Eq. 1, wherein one assumes more simple functions may be used. The assumptions are practical, because the composition is frequently not known. Further, the assumptions are sufficiently valid so that these correlations are frequently used for reservoir engineering computations. In compositional material balance"' computations, the compositions of the reservoir gases and oils are known. The calculation of the viscosities of these fluids using this composition information is required for a true and complete compositional material balance. For reservoir gases, Carr, Kobayashi and Burrows4 have presented a suitable compositional correlation. For reservoir oils, no correlation is available, and data from reservoir fluid analyses have been used7-9 for compositional material balance calculations.* From a theoretical point of view, this is entirely invalid. The reservoir fluid analysis, whether flash, differential, or other process, does not duplicate the compositions which occur during the actual reservoir depletion process, therefore the viscosities measured during reservoir fluid analysis are not those which occur in the reservoir. From a practical point of view, the "error" of using viscosities from reservoir fluid analysis is of varying and unknown significance. One can say qualitatively that the error is greatest where compositional effects are greatest, i.e., for volatile oil and gas condensate reservoirs and pressure maintenance operations. The first requirement to obtain a quantitative estimate of the significance of the error is to develop a reliable compositional correlation for the viscmities of reservoir oils. No such correlation has been available. Consistent with this requirement, the objective of this study was to develop a procedure to predict the viscosity of reservoir fluids from their compositions. Normally, the compositions of reservoir fluids are available expressed as mole fractions of hydrogen sulfide, nitrogen, carbon dioxide and the hydrocarbons methane through the heptane-plus fraction, with the average molecular weight and specific gravity of the latter. The final correlation was to use the composition in this form. While the more challenging objective of the study was the development of a correlation for the viscosities of reservoir oils, the viscosities of reservoir gases were also studied. The end result of the study was a procedure to calculate the viscosities of reservoir gases and liquids suitable

Jan 1, 1965

By Kenneth L. Clifford, Thomas G. White

Many changes have occurred in lead-zinc milling in the U.S. since the 1970 Lead and Zinc Symposium. New mills have been built, novel flowsheets devised, and the use of process control techniques is increasing. The Missouri concentrators produced in 1976 more lead and zinc concentrate than those in any other state. The Tennessee mills produced nearly as much zinc concentrate in 1976 as Missouri and with some very highly developed flowsheets. Progress in the Western U.S. is centered around new operations in Colorado and Utah. New mills in New York and Missouri incorporate many of the newer control concepts. Most of the older concentrators have undergone flowsheet changes to accomodate different ore types or because of the availability of new and better equipment.

Jan 1, 1977

By R. C. Buehl, M. B. Royer

High manganese slags of low phosphorus and iron content are produced by air oxidation of high phosphorus spiegeleisen in a basic-lined converter. Control of phosphorus and iron within specification limits for ferromanganese ore feed is obtained by a unique cyclic operating procedure. Various types of slags, or synthetic manganese ore, can be made. AN affiliated paper' describes the production of high phosphorus spiegeleisen containing 14 to 23 pct Mn and up to 4 pct P in an experimental blast furnace from open-hearth slag or manganiferous iron ore. This phosphorus content is too high for use of the spiegel in normal steel-production operations. Consequently, a preferential separation must be effected whereby the manganese is concentrated in a product that is usable in industrial operations. The preferential separation methods being investigated for this phase of the work are confined to pyrometal-lurgical processes for ready incorporation into steel-plant operations. It is fortunate that manganese is more actively oxidizable than iron or phosphorus, and therein lies a preferential separation method for isolating manganese from these two elements. Silicon is more strongly oxidizable than manganese, and its oxidation precedes, or occurs simultaneously, with manganese. Therefore, manganese and silicon are separable into a high manganese oxide slag phase while the phosphorus and iron remain in the molten metallic state. Complete separation of these elements represents an ideal condition which is not generally attainable in actual operations. This pyro-metallurgical method for separating manganese from phosphorus and iron by preferential oxidation was investigated by blowing 500 lb of metal in a basic-lined vessel to obtain preliminary information on the effectiveness of the procedure. Certain conditions of attainment in the separation process are desirable in any method for removing manganese from high phosphorus spiegeleisen, such as: 1—High recovery of manganese in the oxidation product; 2—the product to be of equal or better quality than ferromanganese-grade ore—48 pct Mn minimum, less than 10 pct SiO2, and Mn-P ratio of 300:1; and 3—attainment of the enumerated objectives in a product amenable to industrial handling, such as a slag of high manganese content that will flow from the processing vessel and of sufficient fluidity for ready separation of metallic granules that may have become mixed with the manganese slag phase. Previous Work Recovery of manganese from low grade ores and industrial byproduct slags by smelting to spiegeleisen, with subsequent oxidation to synthetic ferro-manganese-feed ores, has been a subject for periodic investigation during the past four or five decades in the United States and Germany. Joseph' and associates of the Bureau of Mines North Central Experiment Station, Minneapolis, Minn., smelted manganiferous iron ores of the Cuyuna range, Minn., to spiegeleisen and subsequently tried air and ore oxidation procedures for concentrating the manganese into synthetic ferrograde manganese ore. Joseph's results on the operation of a side-blown basic-lined converter for air oxidation of manganese from molten spiegeleisen were so discouraging that the procedure was abandoned after 11 blowing tests. Much slag was thrown from the converter vessel; phosphorus content was four to five times the maximum allowable for ferro ore; and a manganese-iron ratio of only 2 or 3:1 was obtained in the slag instead of the required 8:1. Oxidation of manganese from spiegeleisen with about 0.5 pct P, by adding iron ore to molten spiegel in an experimental open-hearth furnace, proved moderately successful in Joseph's experiments. The main drawback to the operation was the necessity for over-oreing for effective oxidation of the manganese with consequent too high iron oxide residual in the slag. Furthermore, the phosphorus content was proportional to the iron concentration and therefore much too high, so that several hours of reduction by a carbonaceous material were required to adjust the iron and phosphorus to the desired content of high grade ferro feed. A troublesome feature of the slag product of the spiegel oxidation process was its lack of fluidity if the silica content was less than 10 pct, the concentration considered desirable for the synthetic ore. Approximately twice the desired concentration of silica was required to impart enough fluidity for transfer from the vessel by pouring. The acute shortage of manganese in Germany

Jan 1, 1953

By William A. Edmiston, R. E. Grace

A simplified model for the theory of reaction rates near equilibrium has been applied to the reduction of wustite. A linear relationship between the net rate of reaction and the Gibbs free-energy change, ?F, is predicted. The reduction of wustite in H2 -H2O gas mixtures was studied with a microbalance technique at temperatures from 850° to 950 °C. The predicted model was found to be valid to -?F/RT = 0.1 or approximately -200 cal per mole away from equilibrium. ThE theory of reaction rates near equilibrium has been developed by a number of authors. Prigogine, Outer, and Herbo1 have studied the catalytic hydrogena tion of benzene in an attempt to deduce some intrinsic connection between reaction rates near equilibrium and thermodynamics. Manes, Hofer, and weller2 have derived more general expressions for reaction rates near equilibrium from classical thermodynamics. Hollingsworth3,4 has commented briefly on the work of Manes et al. Benson5 has summarized in a general way the results of the earlier contributions. It is the purpose of this paper to apply the theory of reaction rates near equilibrium specifically to the reduction of wustite in H2-H2O gas mixtures. The basic premise is that the reduction of wustite proceeds by a surface reaction, rather than by solid-state diffusion ,or gaseous diffusion. Richardson and Dancy6 and Gellner and Richardson7 have suggested that the reduction of wustite may be governed by iron diffusion in wustite. Mckewan8-11 has proposed that reduced iron layers on various oxides are sufficiently porous to offer a negligible impedance to the reducing gas. The linear motion of interfaces reported by McKewan and discussed by Themelis and Gauvin12 indicates the lack of diffusive control during reduction. The reduction studies of magnetite reported by Quets, Wadsworth, and Lewis13 give additional evidence that reduction rates are linear when the reaction products are porous and nonprotective. The interpretation of measurements reported in this paper is predicated upon a surface-controlled reduction reaction, at least in the earliest stages of reduction when the reduced iron layer is thin.

Jan 1, 1967

By W. L. Prehn, Adele Chambers, R. L. Slobod

The centrifuge has been found to be an extremely useful tool for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. The use of the centrifuge for determining the properties of small core plugs has been discussed in the literature,',' but practically no experimental evidence has been presented justifying the use of this method in preference to other methods (mainly disc method) now in use. Data have been accumulated and are now presented demonstrating the advantages of the centrifugal method, some of which are: (1) rapid establishment of equilibrium, (2) excellent precision yielding very reproducible results, (3) availability of high pressure differences between phases, (4) simple operational procedure, and (5) ability to establish connate water, residual oil, or to obtain complete capillary pressure curve in one day or less. A commercially available centrifuge capable of speeds up to 3,800 rpm, and a high speed attachment providing a maximum rate of rotation of 18,000 rpm were used in this work in conjunction with core holding tubes designed specifically for this application. In view of the outstanding advantages associated with the use of the centrifuge the conclusion has been drawn that this method should be used in place of the more tedious, slower, and less reliable disc method for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. INTRODUCTION The need for accurate values of connate water, residual oil, and capillary pressure curves in reservoir engineering has been recognized for many years, and the extent of the effort devoted toward solving these problems is reflected in the large number of papers3-" which have appeared in the literature during the past decade. Most of the methods discussed in the recent literature employ a porous disc as a semi-permeable membrane to separate two immiscible phases and make pos-ible the application of an explicit difference in pressure between two phases in the core. Thus, in the determination of the capillary pressure curve the wetting phase (water) is displaced by the non-wetting phase (air or oil). Several investigators1,2 have used centrifugal forces to develop pressure differences between phases. As a result of the first work' in this field the conclusion was reached that "the more rapid centrifugal method for measuring irreducible saturation may have equal value, (compared to use of discs) but more work is required to establish this point." This work was followed in 1945 by a more detailed study2 in which the concepts of this experimental work were more clearly enunciated. A method for calculating saturation for any given speed of rotation based on the observed volume of water displaced was developed and a wider application of the method was suggested. The absence of any subsequent pertinent literature on this subject is interpreted as indicating that no additional work has been completed to substantiate or deny the earlier claims and suggestions of promise contained in the original papers on this subject. One purpose of this report is to provide evidence designed to establish the practical value of centrifugal methods in determining core properties such as connate water and capillary pressure curves. It is also our purpose to suggest a broadening of the scope of this tool to include determinations of residual oil by gas or water drives. THEORY AND PRACTICE IN USE OF CENTRIFUGE Hassler and Brunner2 have clearly presented the basic concepts involved in the use of the centrifuge by relating the performance of a small core in a field of high acceleration to the

Jan 1, 1951

By R. L. Slobod, W. L. Prehn, Adele Chambers

The centrifuge has been found to be an extremely useful tool for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. The use of the centrifuge for determining the properties of small core plugs has been discussed in the literature,',' but practically no experimental evidence has been presented justifying the use of this method in preference to other methods (mainly disc method) now in use. Data have been accumulated and are now presented demonstrating the advantages of the centrifugal method, some of which are: (1) rapid establishment of equilibrium, (2) excellent precision yielding very reproducible results, (3) availability of high pressure differences between phases, (4) simple operational procedure, and (5) ability to establish connate water, residual oil, or to obtain complete capillary pressure curve in one day or less. A commercially available centrifuge capable of speeds up to 3,800 rpm, and a high speed attachment providing a maximum rate of rotation of 18,000 rpm were used in this work in conjunction with core holding tubes designed specifically for this application. In view of the outstanding advantages associated with the use of the centrifuge the conclusion has been drawn that this method should be used in place of the more tedious, slower, and less reliable disc method for determining capillary pressure curves and for establishing connate water and residual oil in small core plugs. INTRODUCTION The need for accurate values of connate water, residual oil, and capillary pressure curves in reservoir engineering has been recognized for many years, and the extent of the effort devoted toward solving these problems is reflected in the large number of papers3-" which have appeared in the literature during the past decade. Most of the methods discussed in the recent literature employ a porous disc as a semi-permeable membrane to separate two immiscible phases and make pos-ible the application of an explicit difference in pressure between two phases in the core. Thus, in the determination of the capillary pressure curve the wetting phase (water) is displaced by the non-wetting phase (air or oil). Several investigators1,2 have used centrifugal forces to develop pressure differences between phases. As a result of the first work' in this field the conclusion was reached that "the more rapid centrifugal method for measuring irreducible saturation may have equal value, (compared to use of discs) but more work is required to establish this point." This work was followed in 1945 by a more detailed study2 in which the concepts of this experimental work were more clearly enunciated. A method for calculating saturation for any given speed of rotation based on the observed volume of water displaced was developed and a wider application of the method was suggested. The absence of any subsequent pertinent literature on this subject is interpreted as indicating that no additional work has been completed to substantiate or deny the earlier claims and suggestions of promise contained in the original papers on this subject. One purpose of this report is to provide evidence designed to establish the practical value of centrifugal methods in determining core properties such as connate water and capillary pressure curves. It is also our purpose to suggest a broadening of the scope of this tool to include determinations of residual oil by gas or water drives. THEORY AND PRACTICE IN USE OF CENTRIFUGE Hassler and Brunner2 have clearly presented the basic concepts involved in the use of the centrifuge by relating the performance of a small core in a field of high acceleration to the

Jan 1, 1951

By Ian Wark

SODIUM sulfide is used extensively to increase the recovery of oxidized copper and lead minerals by flotation, particularly when using xanthates as collectors. It is generally assumed that the sodium sulfide converts a film of the oxidized mineral to the sulfide, and that the xanthate, while not a very effective collector for the oxidized minerals, is a good collector for the sulfide. On the other hand, Taggart and his collaborators' claim that unless sulfide minerals are oxidized they cannot adsorb xanthates and do not float. Gaudin2 states that amyl xanthate, used in conjunction with sodium sulfide, gives better results than ethyl xanthate. Rabone3 and Mayer-Schranz4 agree that excess of sulfide functions as a depressant. Owing to the greater solubilities of the oxidized minerals than of the sulfides, the consumption of sodium sulfide is greater than that of most other flotation reagents, up to 10 lb. per ton of ore being used in some plants. Luyken and Bierbrauer5 recommend a water washing to remove soluble heavy metal salts; by this means sulfide consumption may be reduced. It was desirable to determine the limits of the sulfide concentrations between which contact is possible at surfaces of anglesite and cerussite in xanthate solutions. Similar determinations were desirable for the sulfide minerals with which the oxidized minerals are usually associated, since conditions should be chosen, if possible, so that the two types of mineral will float together. Because of the formation, especially in acid solutions, of hydrogen sulfide and of the hydrosulfide ion (HS-), the permissible limits of sulfide addition are obviously dependent upon the pH value. Sphalerite responds to ethyl xanthate only in the presence of an activator; for example, copper sulfate. It was necessary, therefore, to determine whether sodium sulfide interferes with the activation of sphalerite by copper sulfate. The combined effect of sulfide and copper sulfate was determined also for galena, chalcopyrite and pyrite.

Jan 1, 1936

By Earl A. Trager

The broad picture of world petroleum production at the present time is one of an excessive supply. In any consideration of corrective measures to be applied in the future, it will be necessary to include all the producing areas of the entire world. To illustrate, United States production during 1931 was 48 million barrels1 less than 1930, whereas world production exclusive of the United States increased, owing principally to increases in Russia, Rumania and Persia. Domestic Peoduction Let us first consider the domestic production situation. Due to the fact that United States production was maintained below current demand, about 40 million barrels of oil were withdrawn from storage during 1931. Consumption increased about 1.5 per cent over 1930, which is less than the recent annual rate of increase of 8 to 11 per cent. If the machinery to prevent waste in the petroleum industry operative for more than a year will continue during the coming year and drilling is held to the 1931 level, there will be a decided improvement in the domestic situation by the close of 1932. This will be due in large measure to the drastic reduction in exploratory work and drilling which has been in effect for more than a year. Looking ahead for two or more years, probably there will be a shortage of domestic production in relation to domestic demand, unless there are discovered several large pools comparable to Oklahoma City or East Texas. Were the United States isolated, our problems in so far as petroleum production is concerned might be considered well along the road to recovery. To maintain this perspective will require the cooperation of foreign producers in the future, or protection of United Statcs markets from foreign invasion. Let us review briefly the present situation in the United States. East Texas has been the most important factor during 1931. The large initial production of individual wells and the rapid rate of drilling

Jan 1, 1932

By M. G. Nicholas

The influence of deformation, relative movement and surface cleanliness on the strength of room -temperature "interparticle" bonds between copper surfaces has been studied. No bonding resulted when clean surfaces were merely pressed together, even under pressures of 50,000 psi. Bonding resulted, however, when clean surfaces were simultaneously pressed and moved relative to each other, some bonding occurring no matter how small the pressure or relative movement. Exposure of the clean surfaces to various chemicals inhibited bonding, none at all being produced by small relative movements. The size of the movements which first produce bonding between exposed surfaces depends on the nature of the chemical, being less than 0.002 in. for cleansing reagents and greater than 0.004 in. for lubricants, water and hydrogen sulfide. It is concluded from the experimental data that the prime requirement for bonding is the dispersal of surface films such as oxides and adsorbed contaminants. THE formation of interparticle bonds during the room-temperature compaction of powder metallurgy components greatly increases the ease of handling in subsequent production operations prior to sintering. The strength of unsintered compacts follows the same general trends as their density and hardness, but quantitative data are extremely Scarce. Quantitative correlation of the data on the overall strength of a compact with that of the individual interparticle bonds is virtually impossible due to the extremely complex geometry of powder compacts. Qualitatively, however, the strengths of unsintered compacts can be correlated with variations in parameters known to influence the extent of cold bonding, and hence interparticle bonding, such as surface cleanliness, relative movement, and deformation of the mating surfaces. Kuzmic and seelig4 found that contamination of powder particle surfaces with lubricants reduced the strength of unsintered iron and copper compacts. Interparticle shear has been shown to promote bonding by Train and Hersey7 while Gregory has shown that die rotation is beneficial. Eilender and schwalbe6 concluded that most bonding occurred during the early stages of pressing iron powder compacts when interparticle shear is one of the principal processes occurring. mile there can be little doubt that these and other factors, such as particle size and shape, affect the extent of interparticle bonding produced by compaction, evaluation of the influence of individual factors is not easy. Particle deformation and relative movement, for example, occur simultaneously during compaction, making any precise measurement of their relative influences difficult. Because of these and other difficulties encountered in studying interparticle bonding in actual powder compacts, the approach adopted in this study was to

Jan 1, 1963

By Alwyn Birchmore Cox, Ian William Wark

Sodium sulfide is used extensively to increase the recovery of oxidized copper and lead minerals by flotation, particularly when using xanthates as collectors. It is generally assumed that the sodium sulfide converts a film of the oxidized mineral to the sulfide, and that the xanthate, while not a very effective collector for the oxidized minerals, is a good collector for the sulfide. On the other hand, Taggart and his collaborators1 claim that unless sulfide minerals are oxidized they cannot adsorb xanthates and do not float. Gaudin2 states that amyl xanthate, used in conjunction with sodium sulfide, gives better results than ethyl xanthate. Rabone3 and Mayer-Schranz4 agree that excess of sulfide functions as a depressant. Owing to the greater solubilities of the oxidized minerals than of the sulfides, the consumption of sodium sulfide is greater than that of most other flotation reagents, up to 10 lb. per ton of ore being used in some plants. Luyken and Bierbrauer5 recommend a water washing to remove soluble heavy metal salts; by this means sulfide consumption may be reduced. It was desirable to determine the limits of the sulfide concentrations between which contact is possible at surfaces of anglesite and cerussite in xanthate solutions. Similar determinations were desirable for the sulfide minerals with which the oxidized minerals are usually associated, since conditions should be chosen, if possible, so that the two types of mineral will float together. Because of the formation, especially in acid solutions, of hydrogen sulfide and of the hydrosulfide ion (HS-), the permissible limits of sulfide addition are obviously dependent upon the pH value. Sphalerite responds to ethyl xanthate only in the presence of an activator; for example, copper sulfate. It was necessary, therefore, to determine whether sodium sulfide interferes with the activation of sphalerite by copper sulfate. The combined effect of sulfide and copper sulfate was determined also for galena, chalcopyrite and pyrite.

Jan 1, 1939

By Ian William Wark, Alwyn Birchmore Cox

Sodium sulfide is used extensively to increase the recovery of oxidized copper and lead minerals by flotation, particularly when using xanthates as collectors. It is generally assumed that the sodium sulfide converts a film of the oxidized mineral to the sulfide, and that the xanthate, while not a very effective collector for the oxidized minerals, is a good collector for the sulfide. On the other hand, Taggart and his collaborators1 claim that unless sulfide minerals are oxidized they cannot adsorb xanthates and do not float. Gaudin2 states that amyl xanthate, used in conjunction with sodium sulfide, gives better results than ethyl xanthate. Rabone3 and Mayer-Schranz4 agree that excess of sulfide functions as a depressant. Owing to the greater solubilities of the oxidized minerals than of the sulfides, the consumption of sodium sulfide is greater than that of most other flotation reagents, up to 10 lb. per ton of ore being used in some plants. Luyken and Bierbrauer5 recommend a water washing to remove soluble heavy metal salts; by this means sulfide consumption may be reduced. It was desirable to determine the limits of the sulfide concentrations between which contact is possible at surfaces of anglesite and cerussite in xanthate solutions. Similar determinations were desirable for the sulfide minerals with which the oxidized minerals are usually associated, since conditions should be chosen, if possible, so that the two types of mineral will float together. Because of the formation, especially in acid solutions, of hydrogen sulfide and of the hydrosulfide ion (HS-), the permissible limits of sulfide addition are obviously dependent upon the pH value. Sphalerite responds to ethyl xanthate only in the presence of an activator; for example, copper sulfate. It was necessary, therefore, to determine whether sodium sulfide interferes with the activation of sphalerite by copper sulfate. The combined effect of sulfide and copper sulfate was determined also for galena, chalcopyrite and pyrite.

Jan 1, 1939