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US 4,186,083-An improved collector for use In the froth flotation beneficiation of phosphate rock, barite, fluorspar, scheelite or Iron oxide ore comprises 70 to 99.9% by weight of tall oil fatty acid or the like and the remainder a described anionic perfluorosulfonate compound. Reagent consumption is lessened, and high recovery at high grade is effected. S.S. Wang, E.L. Smith, Jr., and E. F Huliganga, assigned to American Cyanamid Co. Jan 29, 1980. 4 pp. (209-166). Filed. 12-21-77 (863,034).

Jan 1, 1982

By A. N. Holden, J. H. Hollomon

A. H. COTTRELL* and A. T. * Dept. of Metallurgy, Birmingham Univ., England. CHURCHMAN*—We have been making some experiments recently very similar to those reported by Messrs. Holden and Holloman. Wires of Armco iron, 0.077 in. diam. were decarburized in wet hydrogen until the yield point was removed; they were then extended 31/4 pct and annealed at 880°C for 120 hr in dry hydrogen. This process produced large crystals which extended through the cross-section and were about 3/4 in. in length. Since the length of each crystal

Jan 1, 1950

By C. K. Leith

THE purpose of these conferences has been to find some basic principles to guide us in the chaos which confronts us, to arrive at elements of a national policy. None such exists, nor, as a matter of fact, have there been any concerted efforts by the public or the mineral industry to evolve one. In the absence of such a policy the administrative agencies of the government can hardly be expected to be consistent or really effective in their handling of mineral problems, domestic or foreign. Basic Facts MINERAL reserves are unequally distributed among the nations. The principal world supplies are grouped around the north Atlantic, and nearly three-fourths of the world's total is controlled politically and commercially by English-speaking people. No one nation has a complete supply of the minerals necessary for modern industry; specialization, reciprocity, and large-scale movements between the nations are inherent in nature's unequal distribution of them. The principal sources of supply are relatively few compared with the nations to be served-a fact which determines broadly certain natural outlines of the world flow. National isolation with regard to minerals can be accomplished only through backward steps in industry and lower standards of living even in the nations possessing the most of the mineral supplies. A certain measure of unified commercial control, international in scope, is a natural consequence of the limited number of the large sources of supply. Mineral supplies for the world as a whole are so large that there is little need for concern about early exhaustion, but every nation has important problems of early exhaustion of particular minerals, which must affect their policies.

Jan 1, 1933

By D. R. Uhlmann, T. P. Seward, O. Chalmers

A magnetic field has been used to damp out liquid convection during the solidification of castings. Ingots of Al-2 pct Cu were poured from various sperheats (10" to 65°C) into a room-temperature graphite mold located between the poles of an electromagnet. The effect on ingot structure of varying the strength and time of application of the magnetic field was investigated, and the results are interpreted in light 01- current theories of ingot structure. In the solidification of alloy systems, thermal gradients in the melt and differences in density of the constituents are expected to produce convective motion in the liquid. The thermal convection caused by temperature gradients should be present during the freezing of both alloys and pure materials, while the solute convection caused by density differences should be of concern only for alloys. The possible influence of this natural convection on the structure of castings has been discussed by Ruddle,' Chalmers, and Tiller. More recently, an experimental investigation of such effects was carried out by Cole and Bolling. These workers took stationary molds containing lead- and tin-based alloys and. using a brine solution. quenched them from various superheats above their respective liquidus temperatures. When grids were placed across the mold diameter to suppress convection, the grid region was later observed to contain a larger percentage of columnar grains than other parts of the casting or than similar castings poured without the grids present. From thermocouple measurements, they found the temperature in the grid region to be higher than that in the region outside the grids throughout the freezing process, and concluded that convection should be an important mode of heat transfer in normal castings. In addition to such convection arising from thermal gradients or differences in density of the constituents, a further source of convective motion, which we shall call "momentum convection", may be particularly important in small (laboratory-size) castings. By this term we refer to the convective motion produced in the initial pouring process, a motion which is damped out as the linear momentum and angular momentum of the liquid are dissipated. Besides these sources of convection, which are present to some extent in all castings. external influences may also be effective in producing convective motion. Examples of such "forced" convection which have been discussed in the literature include stirring the melt, shaking the mold, rotating the mold, and so forth The purpose of the present study was to examine the effect of convection on the structure of castings poured into a cold mold. In this work, a magnetic field was employed to damp out the convective motions within the liquid, and hence control the extent of con- The effect of a magnetic field on convective currents in a conducting liquid is to induce eddy currents which oppose and damp out the convective motion. vection. The technique of magnetic damping was previously used by Utech and F1emings" in their study of convective effects on impurity banding and other substructure in alloy crystals grown unidirectionally from the melt. In their investigation, fields as small as 200 gauss were found to be effective in damping the convection currents which influence the banding. I) EXPERIMENTAL TECHNIQUE In the present study, alloys of A1-2 wt pct Cu were poured into a room-temperature graphite mold. The mold, in the shape of a circular cylinder, 2 in. ID, 2-3/4 in. OD, 5 in. inside height, and 5-1/2 in. outside

Jan 1, 1967

By Mary Barrett, Walter Rose

INTRODUCTION The conventional way to program reservoir problems* for solution on the electric analyzer1 is one which concentrates the block units towards the inner radius of the prototype system being represented by the analog model. This is achieved by the device of considering block units of equal value radial resistance, leading to the consequences: (1) the ratio of the external to the internal radius of each block unit is a constant (i.e. r1/ri-l = constant a); (2) the external radius of the nth block unit is equal to the innermost radius of the system times the constant a raised to the nth power: (3) the capacitance of the block units increase by a factor of a2 going out radially from the innermost to the outermost boundaries of the system; (4) given n block units in the radial direction, the capacitance ratio of the outermost to the innermost block unit is a (2n-2); and (5) the vertical resistance of the block units decrease by a factor of a going out radially from the innermost to the outermost boundaries of the system, such that the ratio of the maximum to minimum vertical resistance is also given by the factor a(2n-2) PRESENT PROGRAMMING METHOD While this conventional way of programming problems is quite adequate for routine uses of the electric analyzer, it leads to difficulties in those cases where the inner radius of the prototype system (e.g., the well-bore) is small compared to the external radius (e.g.. the external reservoir boundary). To handle such a case by the conventional method would require either that a large value be selected for the constant a or that a large number n, of radial block units be chosen. In consequence, the capacitance and vertical resistance ratios become impossibly large, as will be evident from the relations given above. In any event, the size of the smallest and largest capacitors will always be limited by the size of commercially available components, and the analyzer itself will determine how many mesh points are available for radial block units. For example, it can be shown that if the maximum capacitance ratio which can be electrically handled is a factor of l04, the maximum external radius of the system which can be considered (assuming an internal wellbore radius of 0.25 ft is: It is thus seen that in direct consequence of having the inner wellbore radius small compared to the external radius, models extending beyond 30 to 40 ft are not possible when the capacitance ratio is limited to l04. (NB. A value of 10-9 farads can perhaps be taken as the minimum electrical capacitance possible if corrections for the capacitance of the lead wires are to be avoided. Values greater than 10-5 farads would require the use of unstable and inaccurate electrolytic capacitors). On the other hand, models extending out to 500 to 5,000 ft may be desired in single-well problems, and hence the need for a revised method of problem programming. * REVISED PROGRAMMING METHOD The revised method of programming is one which attempts to retain the desirable features of the conventional method (viz. concentration of block units towards the inner boundary, simplicity in computation, etc.) without having as a consequence that impossible capacitance and vertical resistance ratios will be required. Other advantages will also be achieved by the revised

Jan 1, 1957

By L. R. Mabson, F. M. Russell

INRODUCTION Roan Consolidated Mines Limited (RCM) operates five underground mines - Mufulira, Luanshya, Baluba, Chambeshi and Chibuluma (figure 1) . Associated metallurgical plants provide for the operations of milling, smelting two refineries for copper and a cobalt plant. Primarily a producer of high quality copper (242,000 tonnes during 1980) the Company is also the world's second largest producer of cobalt metal. RCM's remaining ore reserves at 31st March 1980 were 275 million tonnes at 2.84% copper. Monthly ore production is in excess of 1.2 million tonnes. Sublevel open stoping was the choice of mining method for the first underground operations on the Copperbelt for ore with dips steeper than 30 degrees. This was for use at the Roan Antelope mine, subsequently to be called Luanshya mine. The sublevel open stoping system was planned based on the methods used in many of the iron mines of Michigan and New York and in the copper mines of Tennessee. Peterson (Ref. 1) gave the following reasons for employing sublevel stoping, reasons which are still valid today: (1) the working place could always be barred and made safe, and the sublevel exit was always at hand; (2) the working conditions were similar day by day and drilling operations were repetitive; (3) pillar spacing can be varied as conditions demand; and (4) stoping operations could be shut down completely or opened up to full capacity at short notice, without affecting grade or causing wastage of reserves. Such was the success of the method that it was adopted as the basic mining method at all the RCM mines in their initial stages. Although cut and fill, block caving, and sub- level caving methods have been used, sublevel open stoping in its many variants still accounts for nearly 90% of total ore production in the Company. The following descriptions outline some of the applications of sublevel open stoping within RCM. LUANSHYA Geology There are two main ore deposits at Luanshya: the Roan (Luanshya Mining Area), in which mining began in 1930, and Baluba, in which mining production started in 1973 (figure 2). Both orebodies occur in synclinal and variably folded basins. These basins are underlain and completely surrounded by much older schists and granites. The ore formation, an argillite, lies near the base of the sediments and is underlain by conglomerates, quartzites and arkoses. Copper mineralisation is mainly found in two well defined zones, separated by a varying thickness of pyrite mineralisation. In the eastern part of the Roan deposit only the upper orebody is present, but west of 18 shaft and at Baluba the lower orebody predominates. Locally the subjacent quartzites of the footwall formation are also mineralised with copper. The copper mineralisation is found princi- pally as disseminated sulphides, mainly chalcocite, bornite and chalcopyrite. Near the surface the sulphides have been changed to oxides. At Baluba the cobalt mineral carrollite is found with the sulphides. Mining methods Sublevel open stoping is the basic mining method. In its standard form this method is best suited to steeply inclined orebodies, with simple structures and with a strong foot- wall and hangingwall. In recent years, as more complex folding and flatter dipping orebodies have been encountered, considerable variations have been introduced. Stope drilling is effected with drifters and extension steel.

Jan 1, 1981

By Paul A. Beck, M. N. Parthasarathi

By determining the (220) pole figure for OFHC copper rolled to 96 pct R. .A., the occurrence of four texture components of the type (135) [211] was confirmed. It was found that the total volume fraction of material close to the four symmetrical orientations of this type is larger than the volume fraction of the other components put together. THE rolling texture of copper was described by early investigators1'" as a mixture of components of the (110)[l12] and (112) [11l] types. Other studies, still using the qualitative photographic method of texture determination arrived, instead, at orientations of the type (135) [533] or (135) [211] for copper3'4 and at the closely related "Z-texture" for a fee nickel-iron alloy.5 The prevalence of this type of orientation, near (123) [412], in the rolling texture of aluminum and of copper was later confirmed by means of quantitative diffractometer methods.' However, in a recent paper7 Jones and Fell stated that the (110) [112] and (112) [111] double texture was in better agreement with the measurements of Young's modulus for cold-rolled copper.' These authors also expressed their belief that the "roll texture" can be determined by means of two photographic quasi-fiber texture patterns taken with sheet specimens rotated around the rolling direction and the transverse direction, respectively. Jones and Fell found7 that the results obtained from such patterns for cold-rolled nickel did not agree with any of the orientations mentioned above, but they suggested that the observed diffraction spots may have been brought about by the overlapping of reflections due to the (110) [112] and (112) [11l] double texture components. Jones and Fell concluded that the (123) 14121 type orientation is inconsistent with their patterns. They also stated, without offering any supporting evidence, that this orientation is inconsistent with the (220) pole figure. "Ideal orientations" are often used for a very rough description of the principal orientations encountered in a texture, It is, however, well to remember the fact that, no matter how "accurate", these ideal orientations are only schematic representatives of a continuous distribution9, which often (as in the case of rolled copper) includes extensive orientation spreads. The attempt by Jones and Fell7 to use elastic modulus data in deciding between various ideal orientations in the rolling texture of copper neglects this fact. The inadequacy of two-dimensional "axis density figures" in describing orientation distributions in sheet textures was previously discussed.9 It was also pointed out9 that there is no reliable evidence to prove that orientation distributions derived by the "quasi-fiber method" from rotated sheet specimens are fully equivalent to the corresponding information obtainable from quantitative pole figures. The view that a sheet texture could be adequately determined by means of two photographic quasi-fiber texture patterns is obviously erroneous9. The question as to the consistency with the (220) pole figure of ideal orientations derived from the (111) and (200) pole figures is, on the other hand, certainly very relevant. Since no quantitative (220) pole figure for cold-rolled copper appears to be available in the literature, the following work was undertaken. EXPERIMENTAL METHOD An extruded rod of OFHC copper, 1 in. in diam, was given alternate rolling (30 to 35 pct R.A.) and

Jan 1, 1962

By F. J. Fayers, R. L. Perrine

For many years the problem of increasing ultimate recovery of oil from a reservoir has been a subject of interest to the oil industry. At present, a standard secondary recovery technique is to flood the reservoir with water once natural forces of the system are depleted. The permeability characteristics of the rock, together with interfacial forces which exist between the two fluids and the porous material. allow only part of the oil in the rock formation to be recovered by the water-flooding process. Laboratory experiments have shown that when detergents are added to the flooding water, the flow properties of oil in a porous rock arc improved. This improvement results in greater oil recovery. Even though higher recoveries are obtained using detergents, the extra cost associated with the method may make it economically unsatisfactory. To establish economic feasibility requires experimental laboratory measurement of fluid and rock properties together with a calculational procedure to predict field results. Pilot tests in the field may also be required. This paper presents a mathematical procedure for predicting detergent flood behavior. A number of reasonable simplifying assumptions are made to obtain a tractable system of equations. The resulting method may be regarded as a generalization of Buckley-Lev-crett' theory to solve simultaneously for water saturation and detergent concentration profiles. Consequently this type of calculation can be used in much the same manner as Buckley-Leverett theory is used to evaluate a water flood. The mathematical method employed is the so-called method of characteristics for solving hyperbolic partial differential equations. This application of the method is instructive because several other problems in reservoir analysis may be analyzed in a similar manner. FLUID FLOW EQUATIONS The flow behavior of oil and water without detergent through porous reservoir rock is usually expressed by Darcy's law and a continuity equation for each phase. If gravitational forces are neglected, vrg = kr (s)µr v p rg.........(1) vrg = kr (s)µr v p rg.........(1) ? pa va = F ?/?t (sd) where v is the volumetric flux, k represents permeability, S is saturation, and P the pressure. Fluid viscosity is denoted by 11, p is the density, 4 is porosity, and I the time. The subscripts w and o refer to water and oil. The capillary forces in the system lead to a difference in pressure between phases. This may be expressed by the relation: Pm -P0 =Pc(S).........(5) The capillary pressure? P,, is determined experimentally as a function of saturation. DETERGENT BALANCE EQUATION Addition of detergent to the water phase affects the flow properties of the system. Capillary pressure and relative permeability become functions of detergent concentration, c, as well as fluid saturation. That is: P--P (S,c) and k,,,.- - -- k,,,. At low oil saturation values, the presence of detergent reduces capillary pressure and reduces the relative permeability ratio. Detergents are surface-active and adsorb on rock surfaces. The quantity adsorbed, a, will depend on the concentration c of detergent solution and may also depend on the saturation; thus, a = a(S,c). In this analysis we have assumed that the detergents used are water soluble but not oil soluble, and their movement is therefore restricted to the water phase. The dispersion of detergent in water is neglected by comparison with transfer by flow within the system. Detergent movement is determined by the water flux and adsorption: ? cv m = -F ?/?t (cs + a) We will assume that the quantity of detergent in solution is too small to significantly change water density or viscosity. When the permeability and capillary pres-

By R. R. Goddard

By use of the frequency response method with a radioactive tracer, it was possible to determine fluid dispersion and distribution in a natural consolidated and an unconsolidated medium. Measurements were made in a linear flow system at oleic saturations of 69 per cent in the consolidated medium, and 100 per cent in both media. Dispersion and distribution were obtained by measuring the amplitude attenuation and the phase velocity of sinusoidal waves with a dual monitor apparatus. The gamma ray emissions permitted in situ measurements at any distance along the porous samples. One result of importance was that the effective diffusivity increased as the wave length increased. As a consequence, a dispersion coefficient appropriate for the injection of large slugs might exceed the value measured by use of small slugs. Since flow models based solely on fluid velocity and an effective diffusivity coefficient imply that the diffusivity should be independent of frequency, such representations were not adequate for the data of this study. A comparison was made with a capacitance model of porous media with deadend PVs, but even this model was not completely adequate. By using attenuation and phase velocity data, fluid dispersion can be predicted without postulating a differential equation satisfied by the tracer concentration, thereby eliminating the need of a complicated model to represent dispersion. INTRODUCTION The flow of similar miscible fluids through a porous medium can be fairly adequately described by two parameters: the average fluid velocity and the effective diffusivity.1-3 It has been pointed out recently, however, that significant discrepancies exist between this representation and the experimental data.4-7 An improved agreement can be obtained by introducing additional parameters based on the concept of dead-end pores. The purpose of the present investigation was to find out whether the frequency response method could be used to measure the relevant parameters. The method was used in the following form. A stream of fluid was flowed at a constant rate through a sample of porous material and the concentration of a radioactive tracer in the fluid was varied sinusoidally at a fixed frequency. The effects of flow through a porous medium are a decrease in the amplitude of the concentration wave and an increase in the velocity of the peaks of the waves above the average velocity. Attenuation and phase veIocity of the waves were measured as a function of frequency and fluid velocity. The simple two-parameter model implies that the diffusivity should be independent of frequency. Data reported in this paper show that the diffusivity decreases as the frequency increases. Hence, as shown also by many others, the two-parameter model is not completely adequate. Coats and Smith 5 used two additional parameters in their model: the volume of the dead-end pores and the rate of mass transfer between dead-end pores and the flowing stream. Their capacitance model of a porous medium containing some stagnant fluid, to which transfer occurs by molecular diffusion, did not explain the dispersion results of either the present study or of theirs. Instead, the capacitance effect can be better described as the result of extreme velocity variations within the pores of the medium, with transfer between the velocity zones by convection. EXPERIMENTAL PREPARATION OF POROUS MEDIA Data reported here were obtained with a natural Berea sandstone, and with two packings of 20/25 mesh sand. Pertinent information about these media is listed in Table 1. The sandstone core was first sealed with a non-

Jan 1, 1967

By G. V. Jere, V. Krishnan, C. C. Patel

Standard free energy and standard enthalpy changes as a function of temperature have been calculated for the chlorination reactions of different oxides constituting columbite and tantalite. The tallies of standard lee-energy change (F) indicate the possibility of pvefeential chlorination of different oxides but the ease 0.f chlorination of columbium pentoxide at about 250°C and the chlorinating tendency of columbium pentachloride in promoting the chlorination of tantalum and other metal oxides, p7-evetzt the separation of columbiu?n and tantalum from other oxides and pom each othel.. It is likely that low temperatuves of chlorination and continuous 1err2oval of columbium pentachloride from the ..eaction zone may help partial separation of columbium from tantalum as well as from titanium. The standavd enthaply change (AH?) values shotr that 1ou.-temperature chlorination around 300" to 500°C is likely to sustain the chlorination , without external heating. COLUMBIUM (niobium) and tantalum metals, their alloys and interstitial compounds are finding extensive uses in nuclear reactors and high-temperature equipment.la-3 These metals also find uses in chemical process plants, electrical rectifiers and capacitors and as "getters" in electronic tubes.la With the development of Kroll process of reduction of volatilized titanium tetrachloride by magnesium for the production of titanium metal, chlorine metallurgy is receiving greater attention. Chlorine metallurgy has several advantages, the foremost amongst them are: the ease of chloride formation, separation of the different constituents of minerals by selective chlorination, and the reduction of the chlorides in vapor phase to the respective metals. Recently, Si-bert, Kolk, and Steinberg4 have considered a number of methods for the preparation of columbium metal and the most promising is found to be the halide reduction. Since the minerals columbite and tantalite are comparatively abundant in nature, the future of the metallurgical processes depends on the utilization of these minerals for the production of columbium and tantalum chlorides by chlorination. In this paper, an attempt has been made to interpret thermodynamically the chlorination of individual oxides constituting columbite and tantalite, with the help of the recent thermodynamic data.5-8 For this purpose, standard free energy and standard enthalpy changes of the chlorination reactions of the oxides with chlorine, both in absence and presence of carbon as the reductant, have been calculated as a function of temperature and represented graphically. Similar calculations for the reactions employing carbon tetrachloride and carbonyl chloride as chlorinating agents have also been incorporated in this paper. REPORTED WORK ON CHLORINATION Cuvelliezg has patented a process for the separation of columbium and tantalum from their concentrate, wherein 75 pct Cb05 is claimed to be chlorinated at 1050°C in the course of 7 hr using chlorine or chlorine containing nonreducing gases, the products of reaction being CbC1, or CbOC1,. At this temperature, Ta,05 is claimed to remain unaffected. It is further claimed1° that at higher temperatures, the proportion of Ta205 chlorinated increases while that of Cb205 diminishes. During the studies on the action of chlorine on individual metal oxides, Kangro and Jahn" have observed that Ta,05 is not chlorinated even at 1200" in the stream of chlorine, while 75 pct of Cb,05 is converted into CbOC1, around 900 to 1100°C. The chlorination of Cb205 by chlorine in the presence of carbon, investigated by Lind and Ingle,' and

Jan 1, 1962

By R. G. Davies, R. H. Richman

Several techniques, X-ray diffraction, transmission electron microscopy, conventional, metallography, and mechanical property measurements are combined to investigate decomposition in the suPersaturated solid solution Fe-27 at. pct Be. The following sequence of structures for aging temperatures below 400°C is established: massive short-range order, pseudo-FeBe (L2o) order, Fe3Be (DU3) order, sinusoidal modulation of composition, general or continuous precipitation, and discontinuous or cellular precipitation. In addition to this sequence itself, several features of the individual stages are noteworthy; for example, when coherent modulations occur, their development is parallel to (100) everywhere in the specimen apparently without incubation, and both the wavelength and the composition amplitude of the modulations increase with aging time. Two types of discontinuous reaction are observed, depending upon the aging temperature. At low temperatures (<550°C) the boundary-nucleated variety of discontinuous precipitate predominates; but at higher temperatures (>600°C) the crystallographic variety occurs instead. Hardness and flow-stress measurements clearly reflect the quoted structure sequence. Some qualitative aspects of the structure changes and of the relationship between mechanical properties and structure are discussed. BERYLLIUM in solid solution markedly strengthens iron.&apos;" A recent study demonstrated that not only were supersaturated single crystals of Fe-27 at. pct Be very strong, but they deformed primarily by mechanical twinning.3 Such behavior, coupled with the decrease in solid solubility of beryllium in a Fe from about 33 at. pct at 1165°C to about 10 at. pct at 500°C4 as shown in Fig. 1, leads naturally to questions about property changes with aging in this system. In 1929 roll,1 and later Seljesater and Rogers,5 reported that useful increases in strength could be obtained by aging quenched Fe-Be alloys, but it was not until quite recently that any of the details of precipitation in these alloys were studied. Richman6 observed that both an Fe3Be superlattice (with a DO3 crystal structure the same as Fe3A1, illustrated in Fig. 2) and a modulated structure preceded the appearance of a discrete second phase in the 20 at. pct Be composition. Here, a modulated structure refers to a periodic composition fluctuation within one crystal, while its lattice remains coherent. Subsequent work on a Fe-Be alloys by Heubner7 and von Heimendahl and Heubner8 confirmed the existence of the modulated structure, although only an FeBe (L20) ordered structure was detected (also shown in Fig. 2). Both Rich-man and Heubner corroborated the large increases in hardness during aging reported earlier, but other mechanical properties were not examined. Since modulated systems are encountered relatively infrequently, the influence of coherent modulation upon mechanical properties is not well-known. With the accumulation of information about age-hardening systems, it has become clear that many precipitation reactions cannot always be described by the concept of heterogeneous nucleation at some lattice discontinuity followed by diffusional growth. Rather, complex sequences involving prior "preparation" of the matrix are quite common; that is, a transition structure occurs in the parent phase, instead of in some "nucleus" form. Delineation of such subtle sequences appears to be a worthwhile step toward the understanding of solid-state precipitation. Since not many structural progressions of comparable nature have been reported, the objectives of the present survey are to identify and elucidate the various

Jan 1, 1967

By W. R. Kube, W. H. Oppelt

Five low-rank coals, including two lignites, a steam-dried lignite, and two subbituminous coals, were carbonized at 940°F, in a bench-scale carbon-ize~ with a nitrogen and hydrogen atmosphere, or both, using pressures from atmospheric to 1000 psig. Coking characteristics were observed, and yields, composition, and distribution of products from thermal degradation were determined. The influence of pressure on yields from coal carbonization, as well as on modification of coke structure, has long been of interest. One of the first attempts at pressure carbonization was that of Capps and Hulett1 who in 1917 investigated the effects of pressure ranging from 1 to 20 atm on yields at 600° C for bituminous and subbituminous coals. High-pressure carbonization has not been used commercially for coke production. More recently, carbonization at relatively high pressure in the presence of catalysts and hydrogen has been proposed for the production of metallurgical-grade coke from low-rank fuels.&apos; Another approach involves carbonization at high pressure in a hydrogen atmosphere to produce heating gas and a solid residue that is gasified with oxygen and steam to produce the hydrogen required for hydro-genation 3-4 or, alternatively, is burned to raise steam. Recently it has been proposed to carbonize coal under pressure, burn the gas in a gas turbine to produce power, and use the solid residue as fuel in a conventional steam-power plant.5 Our primary interest in pressure carbonization stems from an attempt to determine the influence of pressure on the coking characteristics of lignite to design a high-pressure slagging gasifier using oxygen and steam. At atmospheric pressure, North Dakota lignite is generally considered to be non-coking. However, lignite and subbituminous coals have been reported to show increased agglomeration properties in steam, hydrogen, or carbon-dioxide atmospheres at elevated pressures, although no strong coke was formed at pressures up to 3000 psig.6 If lignite would agglomerate seriously under gasification conditions, proper flow of charge through the gasifier could not be maintained without installing a mechanical stirring device or destroying the caking properties of the coal before gasification. Data on the caking properties of lignite or other gasification fuel, as well as on yields of products under conditions simulating the carbonization process in the pregasification zone, were required in the preliminary design stage of the gasifier. No information was available concerning the influence of pressure and type of atmosphere on North Dakota lignite. To provide this basic data, the U. S. Bureau of Mines investigated the effect of pressure and a hydrogen or nitrogen-rich atmosphere on the yield of products and on coke formation in a bench-scale pressure carbon-izer. SCOPE OF INVESTIGATION Five coals were tested at 940°F in nitrogen and hydrogen atmospheres, at pressures from atmospheric to 1000 psig. Yields and composition of solid, liquid, and gaseous products were determined as a function of the process pressure, and attention was given to the physical appearance of the solid residue. Percentage of carbon converted, sulfur retained in char, and thermal balances were calculated. In this paper, primary consideration is given to carbonization in a nitrogen atmosphere and to data concerning the solid phase. The effect of pressure in hydrogen is presented in detail for only one lignite. More complete information on the response of the other coals in a hydrogen atmosphere will be published in a USBM Report of Investigations. DESCRIPTION OF EQUIPMENT Details of the bench-scale pressure carbonizer are given in Fig. 1. The body of the carbonizer was

Jan 1, 1961

By H. S. Price, D. A. T. Donohue

The system of equations describing displacement of a hydrocarbon liquid by a hydrocarbon vapor in a porous medium where mass transfer takes place between the phases is solved numerically for a variety of gas injection processes. Even though the method of solution is quite general, only systems with three hydrocarbon components are considered. Computer simulations of displacement processes wherein mass transfer between phases is both considered and neglected are compared, and it is shown that neglecting mass transfer can give pessimistic displacement efficiencies. INTRODUCTION The role of the gas displacement process in the recovery of petroleum has been subjected to a series of detailed analyses; as a result, a number of predictive models have been published in the literature. However, because of major simplifying assumptions, most of these models do not completely represent the physical system. As a result, the effect of making the simplifying assumptions is unknown. Therefore, a complete representation of this process — one without major simplifying assumptions —should lead to a fuller understanding of the process, and perhaps to methods of improving it. The general method of developing a model for two-phase fluid flow in a porous medium is to solve simultaneously the continuity equation, the energy equations and the equation-of-state for each phase under the prescribed initial and boundary conditions. For an isothermal system, the energy equations reduce to the momentum equation. Darcy&apos;s law. However, since natural gas is the vapor state of the reservoir liquid, interphase mass transfer may take place with concomitant changes in both the intensive and extensive thermodynamic properties of each phase. It is this phenomenon that has often been omitted in previous mathematical models. An additional relation, then, which accounts for mass transfer between the phases, must be included with the other equations to specify a complete model. Completely formulating the equations to be solved is not a difficult task1 but obtaining their solution has been intractable up to now. Availability of large-memory, high-speed digital computers now makes an attack on this formidable problem possible. This paper presents a preliminary study of the problem. Since this investigation is intended to be exploratory, it is restricted to the linear, horizontal, isothermal, two-phase viscous flow of oil and gas in an oil reservoir. In the early development of predictive models of this process, the reservoir system was considered as a unit and various forms of the material balance equation were proposed.2-4 Pressure and saturation gradients were then added in the Buckley-Leverett model.5 The Buckley-Leverett formulation considered the fluids to be incompressible; thus, the mathematical model reduces to a steady-state system. In the 1950&apos;s, studies incorporating numerical techniques were being published.6-9 These mathematical models differed in the efficiency of finite difference techniques, the inclusion or exclusion of capillarity or the number of space dimensions considered. To solve these nonlinear, partial differential equations, each phase was considered to be homogeneous with time; therefore, mass transfer between phases was neglected. The effect of mass transfer on the gas displacement process was first reported by Attra. 10 He simulated the one-dimension flow system by a series of cells in each of which the fluids were equilibrated during a time step. In addition, the pressure throughout the system during each time step was predetermined and constant-phase velocities were calculated according to the Buckley-Leverett incompressible fluid flow model. Welge et al.11 developed a model for the displacement of oil by an enriched gas where composition is considered to be a dependent variable. Fluid

By T. P. Papazoglou, N. A. D. Parlee, W. C. Phelps

PRACTICAL designs for good "home made" molybdenum furnaces are hard to find in the literature. The one described briefly below left something to be desired but was good enough to operate as a rather long (30 in.) two-zone furnace for periods of over 2 months at temperature (1400° to 1600°C) without shutdown. The principal problem in our application was to establish a temperature profile with two distinct constant-temperature zones and no dip between the zones. This and other problems mentioned below would not arise, however, if both zones were operated at the same temperature and if a shorter furnace were acceptable. Since molybdenum windings oxidize very rapidly when heated in air, impervious refractory tubes were used for both the furnace core and the outer jacket tube shown in the accompanying figures. A protective atmosphere of forming gas (10 pct H2, 90 pct N2) was continuously passed through the gas-tight annular volume between the core and outer jacket. The water-cooled copper ends shown in Figs. 1 to 3 sealed the ends of the tubes. Annealed molybdenum wire (40 mil) was wound on the recrys-tallized alumina core (35.5 mm OD by 28.5 mm ID by 30 in.) at a spacing of 0.36 in. The spacing was reduced to 0.29 in. close to the ends to partially compensate for end heat losses. Fig. 2 shows two molybdenum-ground lead taps off the center of the winding to produce the two independect temperature zones. The ground lead was insulated with 1/4-in. alumina tubing and connected to the grounded copper end by passing the wires through the gas port tube and crimping each wire into notches cut at the mouth. To prevent sagging of the core at high temperatures, refractory "troughs" were cut from alumina and mullite tubing to cradle the core. The support "troughs" which were 6 in. long and located about 5 in. from each end of the annular volume also served as radiation shields. In view of the different expansion coefficients and operating temperatures of the core and outer jacket (3.5 in. OD by 3 in. ID by 30 in.), the ends of the tubes were smoothed and squared to produce good sealing surfaces, and the core was ground 1/32 in. shorter than the outer tube. The power terminals were passed through their respective conductor ports which were internally lined with alumina tubing and sealed with Armstrong adhesive A-6 leaving about 1 in. of protruding lead wire for external connections. (Adhesive A-6 is a two-component system consisting of an epoxy-type resin with a mineral fibrous filler and an amine catalyst.) Figs. 1 and 3 show the entire assembly of concentric refractory tubes, copper ends, and sealing o rings, held together with two brass flanges and 3/8-in. bolts with heavy springs for dimensional flexibility. The furnace shell (19 by 19 by 30 in.) consisted of a steel frame with sheets of transite forming a box. The copper ends protruded through two 3.75-in. circular holes cut at the center of each transite square end. Thermal insulation next to the transite exterior was effected by K-23 B&W bricks alld in a central volume of approximately 9 by 9 by 30 in. a row of K-30 bricks was lined up to support the hot assembly. The rest of the volume around the outer

Jan 1, 1965

By D. Silverman, A. R. Brown

EquipmENT and methods for locating the points of entry of salt water into oil wells are described. These techniques make it possible to delineate accurately the top and bottom boundaries of water zones whether bottom water or intermediate zones of production, Data are given on tests by this survey method on a number of producing wells, Complete results were obtained on wells shelving water percentages ranging from high values to as Little as 10 pct salt water. A number of the wells tested were plugged back and the results are reported in detail. While not all the work-overs were successful, evidence, including the results of reruns by this survey method, points to failure of the plugback operations. The data provided in the tests discussed show, contrary to general opinion, that a large percentage approaching 50 pct of the wells showed intermediate water instead of bottom water. Furthermore, approximately a third of the wells tested showed multiple zones of water production. The equipment comprises a long pipelike assembly carrying 10 pairs of electrodes spaced apart a distance of 4 ft. A surface-controlled solenoid-operated switch is provided to connect each of the individual pairs of electrodes in turn to a single-conductor steel-armored cable by means of which the conductivity of the fluid in the vicinity of each of the electrode pairs can be continuously recorded at the surface. Any number of electrode pairs and any spacing can be used. This assembly is lowered on tubing and placed in position opposite the section of the well to be studied. A conventional rod pump is used to produce the well for the survey. The pump inlet is placed below the lowest electrode pair. The well is conditioned by pumping Out the salt water normally standing in the well and introducing fresh water into the annulus at the surface. When the resistivity of the water standing in the well has been increased to a sufficiently high value, the inflowing fresh water is stopped and the drawdown operation of the survey is started. As the fluid head is lowered by pumping, fluids flow into the well and the entry Of salt water is indicated by the change in resistivity of the fresh water opposite the &apos;Ones Of water entry, The process can be repeated as Often as necessary with little effort and without moving any well equipment to be sure that the fluids produced from each zone are representative Of the true reservoir content. Introduction The oil industry has been concerned from its inception with the control of fluids entering its wells. In order to effect the greatest economy of operation and to get the greatest total production of petroleum liquids out of the ground, the flow of gas and water must be controlled and often extensive workovers are planned and carried Out for this purpose. This has become even more important in recent Years because of the need for the conservation of natural resources. Whereas producing operations concerned with the original completion of a well are assisted to a great extent by a wide variety of instruments developed and perfected for that purpose, workover operations on oil wells have been greatly hindered by a lack of suitable instrumentation. The industry has searched for many years for a satisfactory instrument and process that

Jan 1, 1948

By A. R. Brown, D. Silverman

EquipmENT and methods for locating the points of entry of salt water into oil wells are described. These techniques make it possible to delineate accurately the top and bottom boundaries of water zones whether bottom water or intermediate zones of production, Data are given on tests by this survey method on a number of producing wells, Complete results were obtained on wells shelving water percentages ranging from high values to as Little as 10 pct salt water. A number of the wells tested were plugged back and the results are reported in detail. While not all the work-overs were successful, evidence, including the results of reruns by this survey method, points to failure of the plugback operations. The data provided in the tests discussed show, contrary to general opinion, that a large percentage approaching 50 pct of the wells showed intermediate water instead of bottom water. Furthermore, approximately a third of the wells tested showed multiple zones of water production. The equipment comprises a long pipelike assembly carrying 10 pairs of electrodes spaced apart a distance of 4 ft. A surface-controlled solenoid-operated switch is provided to connect each of the individual pairs of electrodes in turn to a single-conductor steel-armored cable by means of which the conductivity of the fluid in the vicinity of each of the electrode pairs can be continuously recorded at the surface. Any number of electrode pairs and any spacing can be used. This assembly is lowered on tubing and placed in position opposite the section of the well to be studied. A conventional rod pump is used to produce the well for the survey. The pump inlet is placed below the lowest electrode pair. The well is conditioned by pumping Out the salt water normally standing in the well and introducing fresh water into the annulus at the surface. When the resistivity of the water standing in the well has been increased to a sufficiently high value, the inflowing fresh water is stopped and the drawdown operation of the survey is started. As the fluid head is lowered by pumping, fluids flow into the well and the entry Of salt water is indicated by the change in resistivity of the fresh water opposite the &apos;Ones Of water entry, The process can be repeated as Often as necessary with little effort and without moving any well equipment to be sure that the fluids produced from each zone are representative Of the true reservoir content. Introduction The oil industry has been concerned from its inception with the control of fluids entering its wells. In order to effect the greatest economy of operation and to get the greatest total production of petroleum liquids out of the ground, the flow of gas and water must be controlled and often extensive workovers are planned and carried Out for this purpose. This has become even more important in recent Years because of the need for the conservation of natural resources. Whereas producing operations concerned with the original completion of a well are assisted to a great extent by a wide variety of instruments developed and perfected for that purpose, workover operations on oil wells have been greatly hindered by a lack of suitable instrumentation. The industry has searched for many years for a satisfactory instrument and process that

Jan 1, 1948

By Pramod C. Thakur

Introduction Methane is contained under pressure within the fractures and adsorbed on the surface of the coal seams and adjacent strata. It is released into the mine atmosphere during mining of the seam creating explosive gas-air mixtures. Large volumes of air, sometimes as high as 20 tons of air for each ton of coal mined, are circulated constantly to dilute and carry away methane from coal mines. Removal of methane from solid coal, wherever high methane emissions occur, has been discussed by Spindler and Poundstone (1960) and Thakur and Davis (1977). Methane control in longwall gobs is much more complicated. As longwall mining progresses, the overburden continually subsides, and the immediate roof caves behind the roof supports. Even the underlying strata heave and open up communication channels feeding gas to the longwall gobs. The pressure of gas in the underlying and overlying strata is usually higher than the ambient air pressure in the mine. Thus the mine workings become natural pressure sinks, into which gas flows from the entire disturbed zone. Winter (1975) defines this zone as the "gas emission space". Depending on the number of gas-bearing zones in the gas emission space and their gas contents, the total methane emission from longwall gobs could vary from a few to more than one hundred cubic meters of gas per ton of mined coal. Hence the ventilation of longwall faces demands a large quantity of air. This ventilation need is further enhanced by high air losses specially on caving faces (with no stowing of the gobs). The old system of longwall ventilation, the &apos;U&apos; pattern, where all the air was brought down one gate road and exited through the other gate road, loses large quantities of air through gobs giving a high methane concentration at the return end of the face. The &apos;Y&apos; ventilation pattern where intake air is brought down both head and tail gate roads relieves the situation to some extent but, on most longwalls, some kind of methane control is still needed. With the onset of longwall mining in Europe several decades ago, the initial work on methane control on longwall has naturally been done there. The basic principle of methane control has always been, and still remains, some means of "bypassing methane from the gas emission space without letting it mix with the mine air". In most cases the bypassing mechanism is either a strategically located borehole or a roadway. A successful methane control program depends on the following basic premises: a. Determination of the geometry of the gas emission space and location of gas bearing horizons therein. b. Estimation of the rate of methane influx into the longwall gob. c. A scheme to bypass the gas in the most economic and efficient manner and thus prevent it from entering the mine atmosphere. In successful methane drainage programs a high proportion, usually between 50 and 70 percent, of the total gas emissions in a working district is removed before it can enter the mine airways. Advantages of methane drainage can be summarized as: 1. Generally reduced methane levels in the mine leading to increased safety and productivity. 2. Reduced air requirements and corresponding savings in ventilation horsepower. 3. Faster rate of advance for development headings and economy in the size of headings. 4. Possible use of mine gas as an additional source of fuel. The purpose of this paper is to briefly review the geometry of gas emission space and methane influx therein and discuss more successful European and U.S. longwall gob gas control techniques.

Jan 1, 1981

By A. M. Skov, L. F. Elkins

Inclusion of anisotropic permeability in mathematical analysis of pressure transients observed during development of the huge Spraberry field indicates a major fracture trend which is in good agreement with that observed by fluid-injection tests spread over a 12- by 17-mile area. Delineation of this trend is important in selecting a pattern of injection for the pending large-scale water flooding in this field. Determination of reservoir parameters yielding best agreement between calculated pressures and observed reservoir pressures in newly completed wells was made using an IBM 650 computer. INTRODUCTION The Spraberry field covering 400,000 acres is a tight sand of less than 1-md permeability cut by an extensive system of vertical fractures. Primary recovery dominated by capillary retention of oil in the fractured sand matrix blocks is less than 10 per cent of oil in place. Strong forces of capillary imbibition of water into the sand, coupled with water flow under dynamic pressure gradient, indicate considerable increase in oil recovery can be achieved through water flooding. Best results will occur if the pattern of water injection is selected to force the water flow across the grain of the major fracture system. Existence of an oriented vertical fracture system in the Spraberry, observed first in cores, was highlighted more recently by the 144-fold contrast in permeability along and at right angles to the major fracture trend required to match relative water breakthrough times in Humble Oil & Refining Co.&apos;s waterflood test there. Spraberry operators since have conducted two gas-injection tracer tests for further areal confirmation of the fracture trend. Re-analysis of early reservoir pressure transients for evidence of anisotropic permeability has permitted many more local determinations of major fracture trend without resort to further field tests. This paper is limited to updating analysis of reservoir pressure transients to include anisotropic permeability as a test for orientation of the major fracture trend in the Spraberry. The reader is referred to Refs. 1 and 2 for information about general Spraberry reservoir performance and to Refs. 3 and 4 for information about significance of fracture orientation in selection of the injection-well pattern for water flooding the Spraberry. RESERVOIR PRESSURE DATA—DRIVER AREA During early development of the Spraberry Driver area, Sohio Petroleum Co. made the extra effort to measure the initial pressure in each of the 71 wells in a 5-mile-long area immediately after completion. Progressively greater reductions in pressure ranging up to 400 psi were observed throughout the six-month development period. Detailed data are presented in Ref. 1. Since the reservoir oil was undersaturated some 300 psi initially, early reservoir performance involving 55 new well pressures is subject to analysis as flow of a single compressible fluid in a porous media. Assumption of uniform permeability in all directions yielded good agreement between calculated pressures and observed pressures of these wells in the earlier study,&apos; but subsequent, additional, mathematical development to include anisotropic permeability in the transient pressure considerations and present availability of electronic computers to perform the much more extensive arithmetical calculations now yield even better agreement. The previous analysis, assuming uniform permeability, consisted essentially of calculating pressure reduction expanding circularly around each producing well and summing these effects at the time and location of each newly completed well for comparison with the measured pressure reduction. Permeability, effective fluid and rock compressibility, and permeability X thickness were varied until the best match with measured pressures was obtained. The present analysis, assuming anisotropic

By J. E. Hilliard

Various methods are given for estimating the number per unit volume and average size of convex particles from measurements on a projection through a slice of the structure. The determination of the size distribution is considered specifically for spherical particles. The results are applicable to any type of transmission microscopy and also to the correction of measurements made by reflected light on semitransparent materials. WITH the advent of electron transmission microscopy, the metallurgist is confronted with the problem of relating a projected image to the three-dimensional properties of the structure. This paper deals with the estimation of the number per unit volume and size of particles dispersed in a matrix. The case of convex particles will first be treated (the results will be applicable as approximations to particles of more general shape) and then spherical particles will be considered specifically. The latter represent a special case frequently encountered in practice and one which is also amenable to a calculation of the effect of overlap on the observed particle-size distribution. Although the present treatment was prompted by the needs of the electron microscopist, the results are applicable to transmission studies with any type of radiation. In addition, they can be used in the analysis of semitransparent materials by reflected light, the depth of light penetration corresponding to the thickness of the slice or section used in the transmission studies. 1) CONVEX PARTICLES 1.1) General Expression for N,. We will suppose that a "center" (such as the center of mass) is assigned to each particle. The convention used for defining the center is immaterial providing it does not depend on the orientation or location of the particle. Consider a slice through the structure having a pair of parallel faces a distance t apart. It will be assumed that the slice is randomly located with respect to its perpendicular distance from some fixed point, but it is not necessary to assume that its orientation is random. Our problem is to deduce the relationship between the number of par- ticle images seen on an orthogonal projection through the slice with the number, Nv, of particles per unit volume in the original structure.* *Symbols are listed in the Table. The expected number of particles with centers lying within the slice is Nvt per unit area. In addition, there will be elements in the slice contributed by particles whose centers lie without. The number of such elements will be the same as the number of intersections occurring on a two-dimensional plane through the structure; namely N~K, where K is the mean distance, Fig. 1, between tangent planes to a particle averaged over all particles, i.e., Where Ni is the number of particles of class i having the same shape and size, and pi (4, 8) is the probability that an i particle will have a given orientation with respect to the slice. If the particles are randomly oriented, then K is independent of the orientation of the slice and equal to the mean cali-per diameter. The total number of particle elements in the slice is therefore Nv(t + K) per unit area, but fewer will be seen as separate images on the projection plane because of overlap. If MA is the number of elements "lost" by overlap, the number of images per unit area will be NA = Nv(t + K) -MA 121 MA is a function of the slice thickness and must vanish at t = 0. As t increases, NA at first increases, reaches a maximum, and thereafter decreases as the overlap term MA becomes predomi-

Jan 1, 1962

By C. L. T. Edwards

In the preparation of this paper, the author has drawn upon experience with the operation of a blast furnace on Ioo per cent scrap burden, which he believes was the first operation of its kind in the country. It is the writer&apos;s further belief that much of the controversy attending discussions of this subject may be obviated by the presentation of a group of facts that should be known by blast-furnace men and open-hearth men alike. The following question has been raised: "Is iron made with scrap in the blastfurnace charge as good iron as that made without scrap—made with straight ore?" This question may he answered in part by the fact that the open-hearth men of the Bethlehem Steel Co. who used pig iron from a blast furnace that operated on Ioo per cent steel scrap found no difficulty in the processing of such iron other than that to be expected from the known analysis. Operation with ioo PeR Cent Steel Scrap During World War I, there was accumulated at the Bethlehem plant of the Bethlehem Steel Co. some 22,000 tons of alloy-steel turnings and borings. This scrap material was highly corroded and, like alloy-steel turnings of that period, were as a drug on the market. There was also a small tonnage of scale, rich in valuable metal. If this scrap could be worked up into pig iron, it would become readily available for use in the open hearth. In order that the pig iron should contain the maximum percentage of nickel, permission was obtained from the Management to try a Ioo per cent scrap operation. Accordingly, a blast furnace was swung over on July 25, 1919; the percentage of steel scrap increased more or less irregularly until July 29, when Ioo per cent steel turnings were charged. Except for occasional charges of nickel scale as an "cxtra," the operation continued uninterruptedly until Aug. 27, when the furnace was swung back to the regular ore—ore and scrap—operation. During this period, the furnace production ranged from a low of 568.60 tons to a maximum of 766.07 tons. At the swing-over from Ioo per cent scrap to the regular burden, the charge I hung up rather severely. While the latter condition has nothing to do with the object of the paper, a brief discussion of the experience will appear later because of the interest it may have for blast-furnace operators. In Table I, results of the first and last days of the ore charge are shown, July 25 and July 29. The last column shows a summary for the period of maximum scrap &apos; charge. The furnace employed had a hearth 16 ft. o in., bosh 22 ft. o in., stock line 15 ft. 6 in., bell 11 ft. 6 in., batter in., bosh angle 73&apos; 27&apos; and a Balrer-Neuman top, with gas-engine blowers. Analyses Range of material charged Gravel: SiO2, 64.40 to 70.54 per cent; A1203, 3.52 to 4.58; CaO, 7.27 to 9.49; MgO, 5.09 to 6.14; FeO, 1.67 to 3.34, ignition loss, 9.50 to 13.83. I

Jan 1, 1942