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By H. S. Choi, I. Iwasaki

The effect of temperature as a parameter in ore flotation has not been systematically studied, although for some ores it has been known for many years that selectivity and grade of concentrates can be improved by conditioning or flotation at moderately or substantially elevated temperatures. In 1934 Coghill and Clemmer' stated that "elevated temperature seems to make hard water more tolerable" in soap flotation, and a cursory examination of the literature indicates that some earlier investigators were aware of beneficial results obtained by floating above room or mill-water temperatures. Tartaron,2 Mitchell et aL.,3 and particularly Hamilton et al.' have shown that high pulp temperatures give high recovery and selectivity in soap flotation of fluorite from a variety of gangue minerals. As a result of the work of these and of other investigators, high-temperature flotation has been successfully applied to industrial flotation of fluorite. Falconer" stated: "The use of high temperature conditioning (above 35°C and preferably above 60°C) in connection with the soap flotation of nonsulphide ores, as covered in B. Kalinowski's French Patent No. 847,-215, Dec. 7, 1938, is claimed to provide more intense activation, better separation of values from gangue, and reduction in quantity of reagents." The various investigations quoted above clearly demonstrate the improvements to be realized by increasing the temperature at which fluorite is floated, and it is surprising that little or no information has been published on systematic investigation of the same method as applied to other ores. The present article describes comparative results obtained at room temperature and at elevated temperatures by otherwise conventional flotation of iron ores, by single-mineral flotation in the Hallimond tube, and by contact-angle measurements. It is not the purpose of this article to evaluate the commercial feasibility of high-temperature flotation of iron ores, although preliminary calculations show that the cost should not be excessive and that the gains to be realized may well outweigh the extra cost of heating the pulp. LABORATORY FLOTATION TESTS Experimental: All flotation tests reported in this article that use a laboratory Fagergren cell were made on ore A (either containing the primary slimes or deslimed at 20µ as specified) following the preparatory procedures described elsewhere- or this particular ore. Ore A contained hematite, goethite (limonite), quartz, chert, and minor quantities of magnetite. Confirmatory tests made on other ores show that the same general principles apply to ores of similar mineralogy and structure. Conditioning was performed by adding the collector, as a soap, to the vigorously stirred and heated pulp. Conditioning time was 5 min, the pulp contained 60 pct solids, and the equivalent of 0.5 Ib of fatty acid was added per ton of original (unde-slimed) ore. The pH of the pulps ranged from 6.8 to 7.1 (25°C measurement) during conditioning. The pH was adjusted in the flotation cell by addition of either NaOH or H2SO4, the values reported being those of the pulp cooled to 25°C. During conditioning and flotation the pulp temperatures were controlled within l° to 2° by immersion of Variac-controlled Calrod elements in the conditioning beaker and in the cell, and by the use of water, heated to the appropriate temperature, for transferring pulp, adjusting pulp volume, and washing. Selectivity indexes have been calculated on the same basis as those reported in the article by Cooke, Iwasaki, and Choi." Results: Table I gives the results obtained by floating deslimed ore A with pure oleic acid at 25" and 50°C, and Fig. 1 shows the selectivity indexes plotted against pH of flotation. Inspection of Table I

Jan 1, 1961

By S. W. Kennedy, M. Cohen, L. D. Calvert

A high-temperature X-ray diffraction method has been used to study the composition and the kinetics of formation of oxide scales at 800 °C on iron and pure iron-nickel alloys containing 25.6, 75, and 84 pct Ni. This technique has been combined with chemical analysis, and metallographic examination, and determination of weight-gain time curves. The 75 and 84 pct Ni alloys form a three-layer scale consisting of porous NiO next to the metal, a spinel layer, and a -Fe203 on the outside. The 25 pct Ni alloy produces a scale of spinel and Fe,O,, in which, however, traces of FeO and NiO are observed near to the metal. On all the nickel alloys the Fe20, is orieqted with the (107) plane parallel to the surfaces. The exposed surface of the Fe20, is in the form of needles whose axis is perpendicular to the specimen surface. Although the alloys show nonuniform oxidation rates as determined from weight-gain measurements, the X-ray data indicate that the total scale and individml scale layers grow uniformly and parabolically. Deep subscale formation is observed in the 25 pct Ni alloy only. This appeared to be associated with cracking of the scale and penetration of the oxygen along the grain boundaries. ALTHOUGH film formation has been investigated by high-temperature electron-diffraction techniques, for example by Gulbransenl and Hickman,' there have apparently been no investigations of scaling by methods permitting study of the scale during formation at the reaction temperature. Methods involving quenching of scales are based on the working assumption that no significant changes take place on cooling. In general, however, compounds may disproportionate, and the different thermal expansions of constituents may cause disruption of the scale on cooling. In particular, some scales cannot be quenched without spalling. These difficulties are avoided by X-ray diffraction examination at the temperature of formation. High-temperature diffraction procedures also provide a method of determining the kinetics of formation of each phase separately in a multicom-ponent scale. The scaling of binary iron-nickel alloys Containing up to 30 pct Ni at a temperature of 800°C has been studied by Benard and Moreau using cooled specimen~,~ whilst Foley, Druck, and Fryxel14 made an electron-diffraction study of cooled oxide films formed on an iron 42 pci Ni alloy. In the present work the scaling of three iron-nickel alloys containing 25.6, 75, and 84 pct by weight of nickel, at 800°C in oxygen at atmospheric pressure was investigated by X-ray diffraction techniques using a Norelco Geiger-counter diffrac-tometer. The oxidation of iron was investigated for comparison. In addition normal metallographic examinations and chemical and X-ray analyses were made, and weight-gain time curves obtained. EXPERIMENTAL Materials Used—The analyses of the alloys were as follows: Percent by Weight Nickel 25.6 pct 75.4 pct 83.2 pct Aluminum 0.004 None found 0.002 Cobalt — 0.05 0.05 Chromium — — — Silicon — 0.01 None found Carbon All less than 0.05 pct The chemical analysis of the iron was: Al— 0.002 i 0.001 pct, C—0.007 pct, Cr less than 0.001 pct, Cu—0.002 ± 0.001 pct, Mn—0.003 ± 0.001 pct, N—0.0002 pct, 0-0.013 pct, P—less than 0.0002 pct, Pb—not detected, S—0.0017 pct, Si—0.0095 pct, Sn—none detected. This iron was the same as that used to make the alloys and was obtained from the same source-Vacuum Metals Corp. One specimen of pure iron from The British Iron and Steel Research Association was used for preliminary investigation. Specimens were machined to shape from cast rod, polished (the final polish being with 600 Sic paper), degreased in trichlorethylene, washed, and etched. The etching and neutralizing procedure adopted by

Jan 1, 1960

By C. Cronquist

Since April, 1962, Shell Oil Co. has operated a peripheral line-drive waterflood of the 10.750-ft lower Tuscaloosa (Cretaceous) Denkman sand in the Little Creek field. Located in southwestern Mississippi in the lower Tuscaloosa trend, the field was discovered by Shell in Jan., 1958. Among the largest in the trend, the accumulation is controlled stratigraphically and occurs in an extensive series of alluvial-point bar deposits across a nose that dips gently to the south. The crude oil is 39" API gravity and was highly undersaturated at initial conditions. Early production behavior indicated a depletion drive with slight water influx; primary recovery wm estimated to be 25 million bbl, or 24.5 percent of stock-tank oil originally in place. A.s a result of a favorable mobility ratio and remarkably uniform rock properties, the volumetric sweep eficiency in the waterflood has exceeded 90 percent. Despite the high connate water saturation (56 percent), the displacement efficiency by water injection has been quite efficient, contrary to traditional concepts. Based on observed field flood-out performance, ultimate recovery is calculated to be 46 million bbl. As anticipated, the production rate began declining during 1964 due to a continu ing reducrion in the number of producing wells as flood fronts advanced across the field. Cumulative recovery as of Jan., 1968, was 44.8 million bbl; waterflood operations ~hould be complete by 1970. Introduction Most waterfloods described in reservoir engineering literature involve pattern operations, the most common of which is the five-spot pattern. Only occasiona'lly are linear drives described, even though there probably are increasing numbers being put into operation. Increasing use of linear floods may reflect the accelerating trend towards early application of fluid-injection programs when linear drives are more efficient, as was the case at Little Creek. However. the Little Creek operation is unusual in several respects. It is one of a few successful waterfloods conducted in sands with connate water saturations approaching 60 percent, and it is among the deepest successful water-floods being operated anywhere. Development The Little Creek field was discovered in Jan., 1958, in the lower Tuscaloosa trend in southwestern Mississippi (Fig. 1). The discovery well, Shell-Lemann No. 1, was drilled on a seismic closure about 2 miles southeast of lower Tuscaloosa production at Sweetwater. The well was completed in the Denkman sand at 10,752 ft, and on initial potential it flowed 588 BOPD of 39" API crude on a %+-in. choke; psi was 730 and GOR was 442:l. Development proceeded rapidly on 40-acre spacing, and by the end of 1958 the field was producing approximately 9,100 B/D from 56 wells. Almost all this production came from the northern half of the field. The southern part was discovered in Nov., 1958, at a location almost 2 miles from previously established production. Subsequent drilling established an apparent conneotion about half a mile wide between the twd areas. Development of the field was practically complete by 1961 with the drilling of 155 producers and 35 dry holes. Some early wells were completed open hole but moslt are completed with casing cemented through the productive interval and perforated for production. Geology The lower Tuscaloosa structure in this area is a north-south nose with maximum dips of about 2" on the flanks. There is no discernible faulting at the producing horizon. Productive limits of the field are shown in Fig. 2, which is contoured on a marker just above the main productive zone. A common water level at 10,415 ft subsea was logged at both the northwest and southeast ends of the field. There is a gross oil column of nearly 100 ft (Fig. 2). Since there is less than 40 ft of closure, it is apparent that bhe accumubtion is controlled stratigraphically, being limited by a sand pinch-out across the creslt of the nose. The total produc-

Jan 1, 1969

By R. J. Blackwell, J. R. Rayne, J. R. Henderson, W. M. Terry, D. C. Lindley

This paper presents the results of a laboratory investigation of the efficiency of water-solvent mixtures in recovery of oil. These mixtures may have the high displacement efficiencies characteristic of solvent floods and the high sweep efficiencies characteristic of water floods. Thus, the water-solvent process may increase the number of reservoirs in which a miscible-type displacement can be used profitably. The experiments on the use of water-solvent mixtures for recovery of oil were conducted to find the general applicability of the process. These studies demonstrated that, in flowing through sands, water and solvent segregated into a solvent layer on the top and a water layer on the bottom rather than flowing through the sands as a uniform mixture. Calculations based on the simultaneous flow of the water and solvent in layers were used to predict the effective mobility of the mixtures and the optimum operation of the process in steeply dipping, homogeneous reservoirs. As most reservoirs are not suited for the operation of the process under ideal conditions, experimental studies were conducted with sand-packed models scaled to represent more realistic reservoirs. These studies included the effects on recovery of oil of rate of injection, viscosity of oil, variations of permeablity within a formation and variations in water-solvent ratio. For the range of con-ditions studied, higher recoveries of oil were obtained with water-solvent mixtures than with water or practical volumes of solvent alone. INTRODUCTION A group of intriguing—because of their great possibilities—new oil recovery methods at the disposal of the petroleum engineer are the miscible displacement processes. These processes (high-pressure gas drive, en-riched-gas drive and LPG bank driven by methane) displace all of the oil from the portions of the reservoir swept by the injection fluid. The key question confronting the engineer applying one of these techniques to a particular reservoir is, "What fraction of the reservoir can be swept by injection of a practical volume of solvent?"." Intensive laboratory studies have been made during the past several years in seeking answers to the question of the sweep efficiencies which can be expected in solvent floods.' - These studies provided the answer that low-viscosity, low-density solvents channel and by-pass oil in sands with no dip. In horizontal sands, solvent flooding becomes less efficient as the viscosity of the oil increases, the recovery of oil at solvent breakthrough decreases and larger volumes of solvent are required to achieve a given recovery. More efficient displacement of oil by solvent is observed under certain conditions in sands with dip.".' If the permeability and dip of the sand are sufficiently high, gravity segregation of low-density solvent injected updip can prevent channeling. At rates of depletion below a critical rate,"." no channeling occurs. Unfortunately, in many reservoirs, the critical rate is so low that production of oil at rates below this rate is not economically attractive. And at rates over four times the critical rate, channeling is almost as severe in sands with dip as in horizontal sands. These findings pointed out that, for solvent floods to be generally applicable in recovering oil from all types of reservoirs, new methods of improving their sweep efficiencies are needed. Simultaneous injection of water with the miscible fluid was suggested by Caudle and Dyes7 as a method for improving sweep efficiencies. They theorize that water flowing with the solvent would decrease the effective mobility of the solvent and cause it to contact more oil sand. If, indeed, the water and solvent flowed as a uniform mixture, the process should have the advantages of the high displacement efficiencies characteristic of miscible floods and the high sweep efficiencies of water floods. Thus, the method (at least in theory) would greatly increase the number of reservoirs in which miscible-type displacements would be feasible. A research program was conducted to probe the technical feasibility of the water-solvent process. It

By A. N. Chirico

This paper reviews the three major distillation processes: multiple effect (LTV) evaporation, multi-stage flash distillation and vapor-compression forced circulation evaporation. Scale preventative measures are discussed for all saline water applications. Operational data is presented on the Freeport, Texas, demonstration plant, which is the first government facility to produce one million gallons per day of fresh water for a municipality. There has been much publicity concerning the water crisis that confronts many peoples today. There is little doubt that the arid regions - which include the Middle East, parts of Africa and the Caribbean — have suffered to no slight extent for the lack of this most precious commodity. But what about our own country? Government experts have extrapolated demands and flatly predict that by 1980 we will be faced with a shortage of 80 billion gal per day. The validity of this prediction has been disputed by others; however, it appears certain that there will always be a natural abundance in some areas, a shortage of supply in other areas. Distributing our total natural water resource equitably would be impossible. Transmission of water by means of aqueducts can be an expensive undertaking. The controversial Feather River Project in Calif. is an example. The estimated cost for this venture is a staggering three billion dollars. As our population continues to increase and our standard of living rises, agricultural and industrial requirements will be proportionate. What can be done to avoid a crisis? We can conserve and use our water for industrial and irrigation purposes more judiciously: we can attempt to eliminate pollution of our natural resources from sewage and industrial wastes; we can develop, while there is time, saline water conversion processes for the massive production of low cost fresh water. The scope of this paper will be limited to only the distillation type processes that are commercially feasible. The first step in making potable water is to find a source of raw material. An inexhaustible supply is provided by oceans in coastal regions, but the supply of water is more critical in the inland communities of our country. The source of raw material in these. regions is brackish well water and this must be utilized. There is a significant process difference when handling brackish water compared to seawater and this brings out an important fact: No single conversion method can be universally applied to solve all the water problems. Composition of the raw water and degree of distillate purity are factors which must be considered before a particular process is selected. Local conditions at the plant site, fuel costs, labor costs, disposal facilities, etc. are other equally important factors which must be evaluated. WATER CONVERSION PROCESSES Conversion processes commercially feasible today are: 1) multiple effect evaporation, 2) multiple flash distillation, 3) vapor compression distillation and 4) electrodialysis. The first three are distillation processes which take potable water out of the raw water, while the fourth is a membrane process which takes out the salt. In addition to the above there are a good number of other promising methods for production of potable water, many of them in the basic research stage. Freezing is another promising process with commercial potential. This process hinges upon the formation of ice crystals which are free of salt occulsions. Separation and washing of the crystals are problems that must be solved before this process can be considered commercially feasible. Freezing processes have several advantages mostly attributable to the low temperature of operation. This low temperature reduces the scaling and corrosion problems encountered in higher temperature operations. Several different freezing processes are being considered and will be tested in the pilot plant at Wrightsville Beach. One process is a flash freeze process, a second uses a secondary refrigerant such as butane for freezing, and a third process employs a secondary refrigerant particularly controlled to produce large ice crystals. Of the above processes, only the distillation processes are reliable when water of high purity is re-

Jan 1, 1963

By S. B. Twiss, P. R. Basford

The relationship between areas of iron powders, briquettes, and sintered compacts and tensile strength has been determined. It has been found necessary to distinguish between two types of areas which exist in such powders—a macroscopic area due to the shape and size of particles and a microscopic area due to pores and cracks in the surface. Only the macroscopic area, specifically the area due to particle irregularity, contributes to tensile strength; the microscopic area cannot be forced into contact with adjacent particles ond does not participate in bond formation. Of the two methods of area measurement employed in this study—permeability to liquids and gas-phase adsorption—only the former is useful for determining the roughness factor. A measure of this roughness, (area measured by permeability to liquid) -f- (orea of powder with the same size distribution, but made up of spherical particles), is shown to be uniquely related to tensile strength at constant density. The other important factors in determining the strength of sintered-metal compacts are the density and presence or absence of surface oxide. THE manufacture of metal parts by the process of powder metallurgy is an important and rapidly growing industry. Progress has been rapid and continuous, largely because of the excellent research in the field. Nevertheless, the process remains inherently complex and empirical. Several investigators have shown that the properties of the final compact must depend on many variables; namely, shape,' size distribution,"-" nd compositiona of the original particles, the pressure necessary to compress to the desired density, the density of the compact, the time and temperature of sintering, and so on. Through the application of some new techniques to the study of powders and compacts, and the correlation of a number of observations of known variables, the present paper attempts to clarify and simplify the underlying theory of the powder-metallurgy process. Any theory must start with the obvious fact that the strength of a compact, its most useful property, is due to the formation of welded areas between adjacent particles, and attempt to deduce what effect other variables will have on (a) the area and (b) the intrinsic strength of these welds. Such welded areas can be demonstrated by electron micrographs, as in Fig. 1. It was believed that (a) could be most directly studied by means of surface-area measurements on the original powders and on the compacts made from them; the area decrease should be related closely to the welded area. A representative group of eleven iron powders from commercial sources, and made by a variety of processes, was chosen for this study. In addition to the surface-area measurements, correlations were established between the tensile strength and all the known variables which might possibly affect it. The results are quite unexpected. They indicate that the situation is much simpler than the authors had anticipated. The strength of the sintered compact is determined, indeed, by no more than three variables; viz., the irregularity of the original particles, the density of the compact and, in exceptional cases, the amount of surface oxide. All three had been recognized previously as having some effect on the tensile strength, but in the absence of the special techniques and interpretations to be developed here, there could be no suspicion that they were the only relevant variables. Materials and Methods Material—All the iron powders were commercial products obtained from the Amplex Division of Chrysler Corporation. Powders A, B, C, and J were very pure electrolytic iron. Powder D was made from oxidized scrap reduced by heating with an excess of cast iron. Powder E was a high-grade iron ore reduced by hydrogen. Powder I was prepared by atomizing molten cast iron in an air blast, quenching the droplets in cold water, and crushing the coarse powder. Mill scale (oxide) is added and the mixture heated to reduce the high carbon content. The other powders were all prepared by reduction of iron oxides, such as mill scale. They

Jan 1, 1959

By H. A. Wriedt

Zinc-vapor pressures in equilibrium with bcc solutions of zinc and iron at 703.5", 757", 793", and 900°C were measured by an isopiestic method. Thermody-na?nic properties of zinc in these solutions were derived directly and those of iron with a Gibbs-Duhem integration. Zirzc and iron exhibit large, positive, and moderately temperature-sensitive deviations from ideality. Excess enthalpies and Gibbs energies are positive in the ranges studied. It has been establzshed in relating published phase equilibria to the Gibbs energies of forming solid solutions that positive departures from ideality also exist in the fcc solutions. Tlze stability, as defined by Darken, of the bcc solutions is small but positive at 703.5"C. Its decrease with decreasing temperature indicates that a miscibility gap may exist in the stable or metastable bcc solutions at lower temperatures. The changes of thertnodynanlic properties relatable to changes in magnetic state are minor compared to other changes due to alloying. The accuracy with which the relation between lattice parameter and composition of the bcc solutions is known has been improved. Zinc increases the lattice parameter of a iron by O.ZOZA per unit atom action zinc to at least NZn = 0.25. TO our knowledge, only Ciganl has previously investigated thermodynamic properties of the bcc solutions of the Fe-Zn system. He measured zinc-vapor pressures in the temperature range from about 320" to 360°C by an effusion technique. We have measured the vapor pressures of zinc in equilibrium with bcc solutions of zinc and iron at 703.5", 757", 793", and 900°C by an isopiestic technique. This investigation and the pursuant thermodynamic computations are part of a program for studying several properties of these solid solutions. In the appendix we report a remeasurement of the relation at room temperature between the lattice parameter and zinc content. Related work not reported herein embraces measuring the diffusivity2 of zinc in ferrite at 700" to 900°C and the Curie point temperature3 as functions of composition. EXPERIMENTAL METHOD AND APPARATUS Purified iron at a series of constant temperatures was saturated with zinc at a series of constant zinc-vapor pressures, the range of conditions being so limited that the equilibrated solid solutions were ferri-tic. The equilibration was conducted in long capsules, Fig. 1, that had been evacuated, gettered with titanium, and sealed. The purified iron, part of a vacuum-melted ingot of electrolytic-iron stock (Glidden Co. 1044-grade), had the impurity contents listed in Table I. It was used in the form of millings about 0.001 in. thick. A zinc of 99.999 pct purity (United Mineral and Chemical Corp.) and later one of 99.9999 pct purity (Cominco Products, Inc.) were used, with no observed difference in results. Sufficient zinc was placed in the capsule (separate from the iron and kept at a different temperature) to supply the vapor phase and the iron alloy, while leaving a pool of pure liquid zinc throughout the run. The imposed temperature of the residual zinc pool fixed the vapor pressure of zinc throughout the capsule; condensation was avoided at other locations by making this the lowest temperature in the capsule. Two common complications of nonisothermal systems were, we believe, effectively absent from ours: first, molecular species other than monatomic have no appreciable concentration in zinc vapor at 700" to 900~~: second, the development of zinc-pressure differentials in the capsules was suppressed by use of relatively large-diameter tubing and the absence of diluents in the zinc vapor other than desorbed impurities. The specimens and zinc pool were located at two isothermal zones (each ranging within 1°C over several inches) of a wire-wound, 37-in.-long vertical-tube furnace. The required temperature distribution was achieved by external adjustment of the currents in three electrically isolated windings. The temperatures of the isothermal zones were controlled independently by ther-

Jan 1, 1968

By H. C. Brassfield, R. E. Fryxell, E. C. Duderstadt, E. A. Aitken, P. K. Conn

Permeation rates of hydrogen through are-cast tungsten were measured at temperatures from 1300" to 2600°C with hydrogen pressure differentials of 1 and 0.1 atm across isothermal membranes. Rates were nearly Proportional to square root of pressure, were inversely ProPortional to membrane thickness, and were temperature-dependent according to the equation: p = permeation coefficient in cu cm (stp)-mm per sq cm-min-atmlr2, R = gas constant in cal per mole-OK, T = absolute temperature in OK. Permeation rates of oxygen through tungsten were deternlined in the range 1965" to 2300°C and at calculated oxygen (02) pressures of 3.3 x 10-4 to 2.2 x at?n using sealed capsules containing Kmown quantities of tungsten oxide. Permeation coefficients obtained in this manner had a temperature dependency in the range of 40 to 45 kcal per mole of permeating species. Permeation coefficients for oxygen were higher than those for hydrogen in the temperature range studied. This is probably the result of oxygen solubility being much greater than hydrogen solubility at these temperatures at a gzven pressure. The purpose of this investigation was to determine experimentally the permeabilities of hydrogen and oxygen through polycrystalline tungsten at temperatures ranging from 1300° to 2600°C. Permeation rates of hydrogen through tungsten have been measured at temperatures up to 925°C,but no previous measurements have been reported for the temperature range covered in this investigation. Some diffusion measurements3&apos;&apos; and solubility measurements3 have been made for hydrogen at temperatures below 2200°C. No previous permeability studies of oxygen through tungsten are known to the authors; however, efforts have been made to determine diffusion rates5-&apos; and solubilities PERMEATION THEQRY Permeation has been defined by ortton" as the overall steady-state flow process from the gas phase on one side of a membrane or wall to the gas phase on the other side and includes the steps of adsorption, solution, diffusion, exsolution, and desorption; in a given temperature range, any of these processes may be rate-controlling. For diatomic gases, which dissociate prior to diffusion, the quantity of gas which permeates through a membrane or wall at a given temperature is directly proportional to the surface area of the membrane, the length of time of permeation, and the difference between the square roots of the pressures on each side of the membrane, and it is inversely proportional to the thickness of the membrane when diffusion-controlled, thus: q = total amount of gas permeating a membrane, p = temperature-de pendent permeation coefficient, A = area of membrane exposed, / = time, p i = gas pressure of high-pressure side, p2 = gas pressure of low-pressure side, d = thickness of membrane. When the surface reactions are not rate-controlling steps and the solution of the gas in the metal follows Henry&apos;s law, the permeation coefficient, P, is equal to the product of diffusivity and solubility. The permeation coefficient is also temperature-dependent according to the equation: Po = permeation constant, Q = activation energy, R = gas constant, T = absolute temperature. MATERIALS The tungsten materials used in this investigation were greater than 99.9 pct pure. The interstitial impurities ranged from < 1 to 50 pprn C, 7 to 35 ppm O, less than 15 pprn N, and undetectable quantities of hydrogen. Previous high-temperature studies of are-cast tungsten have shown that thermal treatment similar to that which the hydrogen permeation cells experienced reduces the carbon content from starting levels of 50 to 60 ppm to about 30 ppm. Metallic impurities were in the low (1 to 50) ppm range. The argon gas used in this investigation contained about 8 ppm N. None of the following gases were

Jan 1, 1968

By L. W. Holm

This study shows that in the presence of foam, gas and liquid flow separately through porous media representative of reservoir rock. These results were obtained by using tracer techniques to measure the flow of the gas and liquid comprising the foam. Foam does not flow through the porous medium as a body even when the liquid and gas are combined outside the system and injected as foam. Instead, the liquid and gas forming the foam separate as the foam films break and then re-form in the porous system. Liquid moves through the porous medium via the film network of the bubbles and gas moves progressively through the system by breaking and re-forming bubbles throughout the length of the flow path. The flow rates of the gas and liquid are a function of the number and strength of the films in the porous medium. There is no free flow of gas; i.e., no continuous gas phase. On the basis of these results, foam can be expected to improve a water flood or gas drive by decreasing the permeability of the reseruoir rock to a displacing liquid or gas. This improves the mobility ratio and thus the conformance of the flood. INTRODUCTION Foam is formed when gas and a solution of a surface active agent are injected into a porous medium either simultaneously or intermittently. During the past few years, several papers have been published on the subject of foam flow in Dorous media. Foam has been used successfully in the removal of capillary water blocks from producing formations.&apos;&apos;2 The use of foam in gas storage reservoirs to reduce gas leaks and to increase storage capacity has been considered in recent years. Foam has also been investigated as an oil displacing agent,3-5 and as an agent to improve the mobility ratio in a waterflood.6-10 However, the mechanism by which the gas and liquid phases comprising the foam flow through a porous medium has nor been described adequately. Normally, when two immiscible phases (gas and liquid) flow concurrently through a porous medium, each phase follows separate paths or channels. At given saturations of the two phases, a certain number of channels are available to each phase, and as saturations change, the number and configuration of the channels available for each phase also change. The effective permeability of each phase is a function of the saturation of that phase only, and the flow of each phase can be described by Darcy&apos;s law. When foam is present, the effective permeability of the porous medium to each phase is greatly reduced compaced with permeabilities measured in the absence of foam.6,11-13 Based upon the observed flow of surfactant solutions and gas in capillaries, it has been concluded that the gas and liquid may flow separately or they may flow combined as foam. At least four mechanisms have been postulated to explain how fluids flow with foam present: 1. A large portion of the gas is trapped in the porous medium and a small fraction flows as free gas, following Darcy&apos;s law.9 2. The foam structure moves as a body; the rate of gas flow is the same as the rate of liquid flow. 6,13 3. Gas flows as a discontinuous phase by breaking and re-forming films. Liquid flows as a free phase.12 4. A portion of the liquid and gas move as a foam body while excess surfactant solution moves as a free phase.14 It also has been suggested that different flow mechanisms exist for high quality (dry) foams made from dilute surfactant solutions and for foams made from more concentrated solutions. Studies conducted on the flow of foam through capillaries have shown that a plug-type flow occurs and that foam flows as a body.6,15 Fried also has described the flow of foam through porous media as

Jan 1, 1969

R. V. Norris, Wilkes-Barre, Pa. (communication to the Secretary*):—Mr. Stow&apos;s paper presents a series of arguments, numbered from 1 to 18, concerning the relative merits of four systems of colliery-ventilation, designated by the author as " plain pressure-ventilation," " plain exhaust-ventilation," " obstructed pressure-ventilation," and " obstructed exhaust-ventilation." These arguments are subsequently compared by means of tables, in which an arbitrary numerical value is assigned to each, and which consequently serve no other purpose than that of showing his opinions and predilections, as indicated by his assignment of the said numerical values. In addition to this general summary, Mr. Stow intimates his preference for a fifth method of colliery-ventilation—namely, what he calls " alternating pressure-ventilation," which consists in the running of the fan at "pressure " during working-hours, and as an " exhaust" between shifts—a system which he proposes as, perhaps, new, yet which he thinks deserves recognition " as a standard form." This proposed " standard form " is not to be found in practice ; and I think it would be impracticable in gaseous mines of large extent, for the following reasons: 1. It takes considerable time to reverse the air-current in a large mine; and the reversal would involve a period of complete stoppage of ventilation, long enough to permit serious accumulations of gas. 2. In shaft- and slope-mines, at least, it is hardly practicable to have " every man out of the mine" during the night, and certainly impracticable to avoid keeping mules and horses inside. 3. The doors necessary to divide and direct the air-current are properly hung to open against the air-pressure; and, unless

Jan 1, 1910

By E. DeGolyer

WAR has wrought sharp and sudden changes in the pattern of the oil industry. The most obvious and most striking of such changes have been in the fields of transportation and refining. A third of the world&apos;s total oil production formerly started to market, tanker-borne, over the waters of the Gulf and Caribbean. Most of this oil went to our North Atlantic ports, supply points for the world&apos;s greatest consuming center. This tremendous traffic, disrupted by the loss of tankers as a result of requisition for military purposes and by the activity of enemy submarines, has had to be substituted largely by such lines of supply as could be improvised without loss of too much time. No single solution for this gigantic problem has been found nor is it likely to be entirely solved for some time to come. It has been solved in part, however, by rearrangement, reversals, and patching up of existing pipe-line systems; by overland transport of crude and products in tank cars on a scale never before attempted; by barging over inland waterways; and through the construction at long last of the "big-inch" line, the first leg of which is just being put into operation as far as Norris City, III. The tank-car traffic alone, reaching a peak of deliveries of 856,710 barrels per day into District 1 during the week ending Sept. 19, 1942, and accomplished at an expense of millions of dollars in extraordinary transportation costs, defrayed by the Defense Supply Corp. and by the mobilization of tank cars from all over the nation, is a story worth the telling but by some of those who directed it.

Jan 1, 1943

By Lysle E. Shaffer

TEACHING engineering students how to write and speak effectively -is one of the greatest problems facing the technical schools today. No phase of engineering education has received more criticism, and rightly so, for the criticism is justified. Year after year we continue to graduate men that are indifferent to the use of a tool they will need every day of their lives. Our young engineers cannot write a clear, concise report, and their business letters are a disgrace to the profession that takes pride in precision. The problem is not new. The remark ascribed to Sir James Barrie, that "The man of science appears to be the only man who has something to say, just now-and the only man who does not know how to say it" is as uncomfortably true today as it was thirty years ago. The records of meetings of engineering educators and the transactions of the engineering societies show that the inability of the engineer to communicate his ideas has been discussed for years. Engineering educators, prodded by industry, have recognized that the problem exists, but they have not solved it. Instead they continue to expose the student to composition and rhetoric, hustle him through English and American literature, and then blame his high school because he does not know enough English grammar to write a clear sentence. We must face the fact that the graduate is not going to reflect on the high school, but on his college. If the high school has shirked the job, the responsibility for correction rests on the faculty of the professional school.

Jan 1, 1948

By Karl S. Hughes

ANY one of the mining engineers who spent three years under the benevolent and protective custody of the military forces of His Imperial Nipponese Majesty will admit that he has survived a most disagreeable experience, but our friends here in the States all demand that we tell them something about our thrilling adventure. Many of the younger men who were on Luzon in December 1941 joined up with the Army, either as civilian technical employees or through their reserve officer status. They served through the Bataan and Corregidor defense and had five months of thrills and hardship, if that is what constitutes adventure. Unfortunately, too many of them are not alive to tell their stories. But for most of us, our internment as alien civilians was just one long, drawn-out pain in the neck. Yes, we starved; yes, we contracted beriberi, dysentery, typhus, dengue, and for a while had no quinine to fight the ever-present malaria; but these things are not exciting, neither is the account of them interesting. Our contingent from Mindanao, 250 .in number including 25 mining men, went through one period of starvation at Davao. When the activity of the Allied fleet interfered with the importation of staple foodstuffs, and the natives stopped bringing fruit and vegetables into the market, the food situation became acute, and in December 1943, with stocks in sight and in prospect insufficient to provision their own soldiers, our custodians decided that we must be moved to Manila. The story of that ten-day voyage in an antiquated Jap freighter is too disgusting to tell, but hardly more adventurous than the account of a game of solitaire.

Jan 1, 1945

G. R. GOHN. l-1n Table I11 of The Sager, Brown, and Mears paper, which was presented on the screen, data were given showing the results of accelerated corrosion tests of certain magnesium alloys. Mention was made that these were carried to a certain time which was used as a measure of failure but no mention was made as to the period of time. I would like enlightenment on that. G. F. SAGER (Author).-In reply to Mr. Gohn&apos;s question regarding the times of exposure for the accelerated stress-corrosion tests referred to in Table I11 of our paper, which shows the correlation between accelerated and atmospheric stress-corrosion tests on magnesium alloys, I can say that we usually run the accelerated tests on such alloys for at least 500 hr. We feel that this is long enough to reveal any marked susceptibility to stress-corrosion cracking. In the case of the atmospheric tests on such alloys, we have not yet decided how long we should expose the specimens. Most of them are being exposed for indefinite periods and a good many of our specimens have now been exposed for several years. We may want to continue some of the tests for five or ten years. The period of six months mentioned in connection with the times of exposure for the atmospheric specimens was a rather arbitrarily selected minimum time for which specimens had to be exposed before we counted them with those that had not failed. A fairly large number of magnesium- alloy specimens have been exposed in the atmospheric stress-corrosion tests at var-

Jan 1, 1945

By David Baker

IN a paper presented to the American Institute of Mining Engineers, September, 1904, entitled ? Improvements in the Mechanical Charging of the Modern Blast-Furnace,"&apos; I showed the great fault of mechanical charging-devices to be that the materials charged by the dumping of the skip were separated, the coarse materials having high velocity, and the fine, low-thus giving paths of low resistance through the stock in the furnace, which resulted in unequal distribution of the furnace gases, unequal reduction, slips, scaffolds, irregular cutting of the. inwall, " off " iron, and increased fuel-consumption. I showed how this could be prevented by rotary distribution, through which the irregular distribution in one layer charged is compensated by charging the subsequent layers from successively varied positions of the charger, and becomes practically eliminated when the angle between two successive positions is a little more or less than an even fraction of a full circle. Of all the devices then on the market, the nearest approach to the ideal arrangement was found in the Brown distributor, a full description of which was given. The one defect pointed out, however, was the difficulty of maintaining so much mechanism on the top of a blast-furnace. Since the presentation of that paper, I have designed a very simple form of rotary distributor, which may be applied to any form of double-bell charger, retaining the perfect gas-seal, which is so admirably obtained by that construction. In seeking protection for this invention, I found no similar distributor on record in the patent offices of the various countries where application was made; but an application show-

Jul 1, 1906

By Vincent P. Gianella

THE most intense earthquake on the Pacific coast in the last several years, and probably the second most intense shock to occur in Nevada since it was settled, was felt in many Western States shortly after 10 p.m. on Dec. 20, 1932. Be- cause the rifted area contered about the northern end of Cedar Mountain it is referred to as the Cedar Mountain, Nevada, earthquake. An idea of the intensity of the shock may be gathered from the distance at which it was felt: in Wyoming, Utah, Idaho, Nevada, Washing- ton, Oregon, California and Arizona. It is the strongest quake centering in Nevada since the Pleasant Valley earthquake on Oct. 2, 1915. Despite the strength of the vibrations and the large area over which they were felt, relatively little damage was done. The extent of the damage consisted of a few old stone buildings demolished as shown in Fig. 1, much cracked and fallen plaster, many chimneys shaken down and considerable cracking of brick walls. There were no deaths and four people were but slightly injured. The small amount of damage was due, largely, to the scarcity of structures within the area of strong vibrations, but an important factor was the aridity of the region (see Fig. 2) and the shallowness of soil cover so that there was but little water-saturated loose material in which strong secondary vibrations could be formed. Had this earthquake occurred in a region of heavy precipitation and dense population the damage to property and loss of life would undoubtedly have been large, with consequently much more newspaper publicity.

Jan 1, 1933

THE discussion at the annual meeting of the paper on "Devices for Detecting Dangerous Gases in Mine Air" (published in. MINING AND METAL-LURGY, February 1, 1927, p. 69) was prefaced by the following description of a new portable methane indi-cator, presented by D. C. Ashmead: Two comparatively recent disasters in Utah are directly responsible for the perfection of the new methane detector. The first of these occurred on May 1, 1900, when 200 work-men lost their lives. The second disaster did not occur for more than two decades, when, on March 8, 1924, at the Castle Gate Mine No. 2, 172 workmen were killed. A dis-sembled safety lamp was later found at the seat of the ex-plosion. This indicated, as a possible cause, that the safety lamp had gone out and the fire boss had tried to relight it. These two disasters brought, the mine operators of the State of Utah to the concentrated attempt to end the loss of life through mine explosions. The Governor of the State appointed a committee, known as the Utah Mine Op-erators Committee, to study the phases of the problem, and this Committee in turn enlisted scientists all over the country in cooperative research. One group, under the direction of E. K. Judd, of the Union Carbide and Carbon Research Laboratories, of Long Island City, New York, concentrated its efforts on develop-ing a methane detector which would be completely ade-quate. This is now successful, since in laboratory as well as actual coal-mine tests the apparatus has instantaneously and accurately detected the presence of extremely small amounts of methane.

Jan 3, 1927

By Charles B. Dudley

It is evident that, as the size and weight of cars have increased, the demands on the cast-iron car-wheel have become more and more severe. Fortunately, the factor of safety in the cast-iron wheel, as originally made, was so large that it was only when freight-cars approached the capacity of from 80,000 to 100,000 lb. that the question of wheels began to give some anxiety. A moment&apos;s thought will show that, as freight- and passenger-cars have increased in weight and size, a much greater duty is required of the same eight wheels than was formerly the case. In other words, although the cars have increased in capacity from 15 tons to 50 tons each, the number of wheels under a car has not been generally increased. It is true, some cars have been equipped with 12 wheels, but this construction is not the rule. Hence the duty which the wheel must perform has become much more severe, and although it was clearly able to stand some increase, there must evidently be a limit somewhere which cannot be exceeded. Meanwhile, it is the part of wisdom to make better wheels if possible, and accordingly, no little study is now being devoted to the requirements for cast-iron car-wheels; and modifications are being made, both by increasing the weight of the wheel and by improving the quality of the metal of which it is made. The desire to improve the quality of the wheel has led to the preparation of specifications for its manufacture; and within the last 15 years a more rigid scrutiny of the wheel is char-

Jan 1, 1905

By Edward Steidle

IT has been said that "the command of nature has been put into the hands of man before he knows how to command himself," and what we see about us gives particular emphasis to this observation. If this condition be granted, the vaunted boast of school and college, of the institution that had the training of this generation, and of its fathers, and of its grandfathers, the boast that education is a "preparation for life," stands exposed as a hollow claim, or as a ghastly, cynical conception of life, or else education has fallen far short of its intentions. It has been evident for some time that education was not meeting the fullest expectations of society. In recent years there has been a deal of speculation indulged in by both laity and faculty in regard to American education and American civilization, and some few and sporadic changes have been effected. Today, however, there is no longer time for mere hypothetical considerations; we are faced with certain definite facts and confronted with obvious conditions that will not wait for fine-spun theories. If educators do not put their house in order, someone else will do it for them. The trends in mineral industries education must be in harmony with this general realignment that is today visible on the educational horizon, and only as these trends are in conformity with this movement can they be called sound. Two questions, then, confront mineral industries educators: (1) What are the trends in mineral industries education, and (2) how do these trends correlate with the major educational movements of the day?

Jan 1, 1933

By A. F. Knoll, T. Clinton Taylor

Qualitatively, galena (native lead sulfide) reacts with aqueous solutions of the xanthates,1 and has its surface sufficiently altered so that there is a tendency for air bubbles to attach themselves to the mineral crystals where there was no such effect before the treatment. This property is utilized in froth flotation operations where the mineral sulfide particles are raised into the froth and the gangue whose surface is not altered remains behind. The results of a study of this reaction were reported2 recently and certain tentative suggestions about the interaction of galena and the alkali xanthates were offered. In this paper, there is set down the results of a detailed quantitative investigation of the ions involved in this interaction with a view to finding out more about the condition existing immediately at the surface of a crystal like a heavy metal sulfide after treatment with an organic reagent. Past experimental experience showed that finely ground galena shaken with aqueous potassium xanthate abstracts xanthate ion and at the same time sulfate ion, reducing ions of the type (SmOn)= where the ratio of m to n is less than 4:l (as in sulfate), sometimes hydroxyl ion, are thrown into solution.3 Ions Involved in Xanthate-galena Interaction The present quantitative study of the galena-aqueous potassium xanthate system shows that at the lower concentrations of potassium xanthate (less than about 25 mg. per liter) the amount of xanthate ion abstracted by the galena can be accounted for by the amount of reducing ions of the (SmOn)= type and sulfate ion thrown into solution. At these

Jan 1, 1935