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By Ove Sandberg, Olav Bowitz

The operational characteristics of the Soderberg vertical spike anode are briefly discussed stressing the importance of the flow properties of paste in the fluid zone, the thermal shrinkage in the carbonizing zone, and the surface disintegration in the consumption zone. The requirements for paste recipe and binder quality are combined with design and operation of cell. A low temperature susceptibility of viscosity and low thermal shrinkage of paste together with a low microporosity of the binder coke are important properties. PRACTICAL application of Soderberg's idea of a selfbaking carbon electrode proved successful just before 1920. Shortly after, experimental work was started with the aim of developing a continuous electrode that could be adopted as anode in aluminium reduction cells. The intermittent operation of a large number of small prebaked anodes made the idea of developing a continuous anode for electrolytic production of aluminium especially tempting. Moreover, the electrode consumption in this process, even on a theoretical basis, is very high. Many installations were carried out in the 1930's and during the Second World War. During the tremendous post-war expansion of the aluminium industry, the Soderberg electrode has been steadily more widely adopted. Thus, today more than 60 pct of the Western World's output of aluminium is produced in cells with selfbaking anodes, see Big. 1. The quality of the anode paste of Sfiderberg elec- trodes is considered a major factor influencing the specific carbon consumption. The purpose of this paper is to survey the fundamental requirements which must be met in order to obtain good anode operation. We have limited this paper to a discussion of Elektrokemisk's research on the vertical spike type anode. I) FUNDAMEKI'TALS OF ANODE CARBON PERFORMANCE A) Brief Introduction. The only practical method for producing a conductive carbon anode of the size required is to form and carbonize a mixture of a carbonaceous binder and a precalcined dry aggregate coke. In the Soderberg electrode, the forming and carbonization take place in the electrolytic cell

Jan 1, 1962

By R. F. Shurtz

The author proposes a method used with some success on a magnesite deposit at Gabbs, Nev. He believes this procedure to be more sound than the blind practice of assigning uniform quality to large, soinetimes vast blocks or ore on the basis of analyses made of a small number of samples. When an ore deposit is evaluated on the basis of core sampling, questions always arise as to how much weight should be given the various sample grades and how the deposit should be divided into specific volumes assigned to corresponding grades. For a tabular deposit it is customary to use the so-called zone-of-influence. This zone is usually defined as the polygon in the plane of the deposit having corners halfway between a given core drill intersection and each of the nearest neighboring intersections. The volume of the ore in this polygon is assigned the analysis obtained from the drill core taken at the intersection. In massive or irregular deposits, volumes of various shapes may be defined with respect to the locations of drill core samples. These volumes may be regarded as three-dimensional zones-of-influence; the theory involved in assigning the values of the central analyses to the ore in the volumes is the same as that used in the case of a tabular deposit. The zone-of-influence method was used in evaluating one of the magnesite deposits at Gabbs, Nev.'-"

Jan 1, 1960

By B. C. Craft

The principal events in the oil and gas operations for Louisiana during 1933 have been the rapid development of the Converse field in Sabine Parish, the discovery of three new salt domes, one in North Louisiana and two in South Louisiana, increased development in the Iowa field on the Calcasieu-Jefferson Davis Parish line, and extensive geophysical operations over a wide territory. Other miscellaneous events worthy of mention are the continued leasing of prospective oil lands over a wide area, extension of production at the East Hackberry field, Cameron Parish, discovery of deep sands at Caillou Island, Terrebonne Parish, and the completion of several important wildcats. Despite proration, oil production showed a substantial increase during 1933. The total output for this area was 25,599,802 bbl. as compared with 22,507,387 bbl. during 1932. North Louisiana There were 111 oil wells and 47 gas wells completed in North Louisiana during 1933 as compared with 109 oil wells and 33 gas wells during 1932. North Louisiana oil production decreased approximately 692,625 bbl. in 1933 from its 1932 figure. The normal decline in the old fields was partly offset by increased production at the Zwolle and Converse fields in Sabine Parish. Acid treatment of wells in the Zwolle, Converse and Monroe fields was highly successful. The method of application has been described by H. K. Shearer, Geologist, Pelican Natural Gas Co., as fo1lows:l With tubing in the hole and standing valve removed, the casing is filled with oil to the surface. The limestone solvent is pumped in through the tubing, at the same time bleeding off enough oil from the casinghead to equal the volume contained in the tubing plus the volume of open hole to be treated. The amount of solvent used in most of the wells treated was 1000 gal., which is enough to dissolve about 11 cu. ft. of chalk or limestone. After the computed amount of oil is bled off, the casinghead is closed and the remainder of the solvent is pumped in at whatever pressure is necessary to force it into the oil-producing horizon. The solvent is followed up with enough oil to

Jan 1, 1934

By Will B. Jamison

Man's material advance from one level of civilization to the next has involved the development of new, more useful tools and the utilization of energy greater than he alone could produce. These two essentials for material progress have developed at an ever increasing rate in the last century. While the first really successful use of mechanical energy derived from burning fuel was in James Watt's steam engine which pumped water from coal mines in Cornwall about 1770, there was still very little use of mechanical energy in mining by 1900 except for pumping and hoisting. Compressed air, having some of the characteristics of steam and which operated engines not unlike steam engines or steam hammers, powered the first attempts to mine coal with energy greater than human muscle could provide. When direct current-powered traction cars replaced horse-drawn transportation cars on city streets, it was natural that direct current locomotives should begin to replace animal and human power in mine haulage. Slowly, trolley and battery locomotives were developed and introduced. With d-c systems being established for haulage, it was natural that improved cutting machines should be developed and powered by d-c motors. Thus began the years of

Jan 5, 1960

THE opening session* was held in the hall of the Franklin Institute, on Tuesday evening, June 20th, President Holley in the chair. The President introduced. Mr. Franklin B. Gowen, who addressed the Institute as follows MR. PRESIDENT AND GENTLEMEN : It has been made my pleasant duty to welcome you to the city of Philadelphia, but in so doing I shrink, with some natural reluctance, from appearing before an audience so much better fitted than I am to cope with the subjects which are usually presented to your association, and I can assure you that no trembling neophyte, first venturing within the groves of the Academy, or walking, with sacred reverence, in the gardens of Plato, felt more natural dread at the consequence of his own temerity than I do in appearing before an audience composed of gentlemen belonging to a scientific society of which I am but too sensible that until now I have been a member only in name. In olden times, upon entering a temple sacred to the worship of any deity, it was customary to lay some offering upon the altar, and, in following this custom, it will be my duty, before entering upon the more pleasant part of the task which is assigned me, to call your attention to a subject with which I have been somewhat familiar, and which is entirely within the scope of your investigations, in the belief that I may throw out some hints or some suggestions of a pro¬cess that may be fully developed by some of you, and eventually lead to the introduction of that which may be of service to the human race. The satirist who described the philosopher whom he met, as engaged in the process of extracting sunbeams from cucumbers, * A joint discussion of the subject of Technical Education, by the members of the American Society of Civil Engineers and the American Institute of Mining Engineers, was held in the hall of the Franklin Institute, on Monday evening, June 19th, and Tuesday morning, June 20th. This discussion has been printed in a separate pamphlet by both societies.

Jan 1, 1877

By Robert E. Green, Edmund G. Henneke

The velocities of the three possible modes of elastic wave propagation have been calculated for single-crystal copper at 1-deg intervals throughout the standard stereographic triangle. The results are presented as isospeed contours. The deviations between the direction of maximum energy flux and specimen axes are presented as arrows drawn on stereographic projections. The orientation factors associated with dislocation motion on the primary slip system only and also on all twelve slip systems have been calculated for all three elastic waves. The orientation factors associated with a longitudinal standing wave resonant specimen have also been calculated. The results of these calculatians are compared with earlier calculations on aluminum crystals and the relevance of these results to ultrasonic attenuation measurements is discussed. GREEN and inton' have recently outlined a procedure for determining the orientation factors for dislocation damping in single crystals. The stress field associated with a given mode of elastic wave propagation is resolved on the slip systems in which it is assumed the dislocations are vibrating due to this stress field. Since, at room temperature, slip has been observed on a limited number of systems in fcc and hcp metal crystals, it is assumed that these systems are the appropriate ones to use for the resolving process. This procedure has been applied to aluminum crystals by Hinton and hreen' and to zinc crystals by Henneke and Green.3 In the present paper the modes of elastic wave propagation have been calculated for copper crystals possessing orientations at 1-deg intervals throughout the standard stereographic triangle. The deviation of the energy flux vectors from the specimen axis have been calculated for each mode. The stress field associated with each mode has been resolved on the (111)(110) slip systems in order to determine the orientation factors for dislocation damping. MODES OF ELASTIC WAVE PROPAGATION For any direction in a linear homogeneous aniso-tropic material three elastic modes can be propagated. In general, each of these modes has both longitudinal and transverse particle displacements associated with it and thus are not "pure" modes. However, there is always one component which is greatest in either a longitudinal or transverse direction and hence the mode may be referred to as quasi-longitudinal or quasi-transverse, accordingly. For certain axes of high symmetry pure modes may be propagated. The phenomenon of refraction of the energy flux vector is also exhibited by elastic wave propagation in ani-

Jan 1, 1969

By K. L. Komarek

Based on theoretical and experimental evidence a discussion follows of the behavior of phosphorus -bearing iron ores in the R-N Direct Reduction Process and suggestions are made of methods of reducing the amount of phosphorus in the metallic end product. In ferrous metallurgy a direct reduction process is one in which iron ores are reduced to metallic iron with gaseous or solid reductants without the appearance of a liquid phase. A number of attractive features have induced several companies and government agencies to invest in the development of direct reduction processes. A summary of all direct reduction processes up to 1954 has been given by Barrett,' and Wiberg,2 and Willems3 have reviewed the most recent developments in this rapidly expanding field. Many difficulties have been encountered in direct reduction processes and the nature of these difficulties has varied from process to process. One problem common to almost all of them is the removal of phosphorus which is one of the reasons for the rather pessimistic outlook given by some government publications4'5 to direct reduction processes. In this paper an attempt is made to give a theoretical explanation of the variations in phosphorus removal observed in the R-NY Direct Reduction Process. However, many conclusions are general enough to be applicable to other processes. Most iron ores treated by the R-N process yield products lower in phosphorus than the original ore. A qualitative account of the factors has been given by Stewart, Reed, and Herasymenkoe but the erratic removal of phosphorus from some ores and the general importance of this problem make a more careful analysis of the theoretical aspects desirable. In the R-N process mixed ore or balled fines, ex-

Jan 1, 1963

By Albert F. Hill

The manufacture of structural shapes in steel of uniform quality, which shall command the full confidence of the engineer, is a problem in practical metallurgy which is beginning to attract much attention in this country. The progress of the past fern years in the improvement of plant and processes has placed it within the power of the steel-maker to supply a material of such chemical composition as will meet the requirements; but this solves only in part the difficulties of the constractor. It is well understood that the influence of shop manipulations is a most decisive one upon the mechanical properties of the finished product; in many cases so great, in fact, as to cause an entire transformation in the character of the material, and to render it unfit for the service for which it was intended. On the other hand, mechanical treatment is frequently resorted to as an efficient corrective of certain undesirable properties, which may be due either to chemical composition or previous manipulation. This understood and accepted, it is evident that careful investigation of the effects of mechanical treatment is fully as necessary to the successful use of steel in engineering structures, as the investigation of the influence exerted by its chemical composition. All structural material has to undergo more or less mechanical treatment, such as shearing, punching, upsetting, etc. Each of these operations produces effects which are far more marked and decisive in steel than they are in iron, and means must therefore be adopted to counteract, or at least to modify, these effects before the material is permitted to enter the structure. The fact that both shearing and punching affect the tenacity and elasticity of steel has long been recognized; bat, through more recent investigations, it has been established that these effects are purely local, and are therefore susceptible of correction by other and simpler means than annealing. The importance of this discovery to the use of steel in structures is very great. The impracticability of

Jan 1, 1883

By D. T. MacRoberts

This paper embodies the results of theoretical studies concerning gas reservoirs, especially the effect of drilling programs of various intensities upon pressure depletion and ultimate recoveries. The primary objective has been to determine the net quantity of recoverable gas that could be obtained as a result of each additional well, in comparison with the gas . that might be secured from a single well ideally placed with respect to both acreage and geological structure. No method is yet known whereby the relative merits of intensive and sparse drilling can be compared experimentally; a reservoir must either be drilled closely or developed with wide spacing, but both programs cannot be conducted simultaneously. Hence, the analytical method seems to be the only approach to the problem. While the present state of our theoretical knowledge does not offer a precise solution to the problem of gas flow in sand bodies, it takes such appropriate cognizance of the limitations of the methods used as to restrict any answer obtained to the realm of engineering accuracy. In solving the problem for the average gas field, it was found that practically the same answers resulted as to pressure distribution, regardless of the size of the drainage radius, even though the latter was assumed to vary from a few feet as a minimum to that of the entire reservoir as a maximum. Such limits represent extreme possibilities; therefore, the practical conditions that are associated with normal development programs, in which wells are placed in the center of tracts varying in size from 40 to 640 acres, will of necessity result in less extreme variations than those indicated in the tables accompanying this paper. Stated more concisely, the amount of gas unrecovered at abandonment (of the particular field used for illustrative purposes) will lie somewhere between 4.6 and 6 per cent of the total original content, no matter how intensively the field is drilled. Gas reservoirs may be divided into two general types, those in which the energy is intrinsic, and those of which the energy is extrinsic. † The first type contains energy in the form of a compressed gas, which expands

Jan 1, 1938

By C. D. Broadbent

INTRODUCTION The slope stability research plan at Kennecott was developed to serve the specific needs of large, open pit mines; primarily those developed in faulted and highly-fractured intrusive deposits. The program emphasis is on applied research; being defined in this case as research into the engineering mechanics of discontinuous rock and into the related rock property survey and slope design techniques. The program has been developed in phases, with each phase organized to explore more thoroughly the most significant findings of previous work and to improve on techniques found to be applicable. The current work is based on principles developed early in the program and that show promise of having engineering and economic value. A brief summary of the conceptual principles of the program is given to put our current work in context. This is followed by a review of the two cooperative programs done with the U. S. Bureau of Mines. Most recent work is described and interpreted in terms of practical slope design. Although failure-free slopes are a desirable goal, it is recognized that some failures will occur when overall slope designs approach a calculated safety factor of one. A discussion of failure control research is therefore offered. BACKGROUND In 1965 Kennecott management specified that a slope stability technology must be used to achieve optimum development of ore resources. The subject was carefully explored and by 1960 it had been established that there was no technology readily applicable to open pit slope design. Therefore, in 1962, Kennecott Copper Corporation and the U. S. Bureau of Mines agreed upon a cooperative research program having the objective of developing a mine slope stability science. One of the first decisions made by the cooperating groups was that the research must be conducted primarily in the field and not in the unrealistic environments of a laboratory. Accordingly, the Kimbley Pit, an abandoned mine once operated by Kennecott's Nevada Mines Division in Nevada, was selected for the full-scale research. Fortunately, there was near-universal agreement on the basic stability parameters and thus on the areas to be investigated. These parameters were acknowledged to be: (1) anisotropy (generally due to faults or joints), (2) stress, and (3) water; in that order of importance.

Jan 1, 1972

By R. E. H. Pomeroy

The statistical data given in this paper are taken from the actual performance of the No. 2 reverberatory furnace of the Nevada Consolidated Copper Co., Mc Gill, Nev., for a period of four months, from April to July, 1914. The principal furnace dimensions are: Length, 132 ft. % in. at the skim-line level; average width, 18 ft., 10 in. at the skim-line level. The roof is 7 ft. above the skim-line level at the firing end. The average area in the uptake flue is 36 sq. ft., and the area above the skim line under the vulcatory arch is 24.3 sq. ft. Fig. 1 shows a diagrammatic plan and sectional elevation of this furnace. The furnace is equipped with two 400-b.h.p. Stirling waste-heat boilers set in parallel. California crude petroleum is used for fuel and has a specific gravity of 16.5" B., flashing in open test at 199" F. The oil is heated to about 200" F. in a steam heater before going to the burners, requiring about 9 b.h.p. per furnace day to heat it from the line temperature to the burning temperature. Measurement is made by oil meter, checked daily by reservoir readings. The oil is fed by gravity (34 Ib. static pressure) to seven low-pressure blast burners of the Steptoe type (Fig. 2). The blast for these burners is supplied at about 40-08. pressure by a motor-driven Connersville blower of 42 cu. ft. capacity per revolution. The air supplied by the blower through the burners for atomizing the oil amounts to about 10 per cent. of the theoretical air necessary for complete combustion of the oil. The remainder of the necessary air enters the furnace through the burner openings in the firing wall. No checker holes are provided, and the charge holes in the roof are equipped with slide gates and " dog houses" to minimize air leakages. The combustion of the fuel, as shown by gas analysis at the front of the furnace, is practically complete, the carbon monoxide in the gases being less than 0.5 per cent. The draft at the firing end of the furnace is 0.18 in. of water. At the throat or in the uptake above the "verb" the draft is about 1 in.

Jan 1, 1915

By Henry F. Cooper, Scott E. Blouin

Large jacking test procedures that have been applied to obtain static in-situ rock properties (Ref. 1) have shown that the in-situ rock modulus and strength can be considerably less than what would be obtained from laboratory tests on intact samples. This trend is also expected to be true for dynamic properties, but few dynamic in- situ rock property tests have been conducted. During the past several years, high explosive test procedures have been developed to simulate the airblast and direct induced ground motions (Ref. 2) produced by nuclear explosions . These test procedures load large volumes (up to 10 7 f t3) of the earth with stress levels sufficiently high to produc5 feet of particle displacement over surface areas up to l0 5 ft2. This paper discusses some of the data obtained, and the implications of these results for our understanding of the dynamic response of in-situ rock. DESCRIPTION OF TEST PROCEDURES As shown in Fig. 1, the High Explosive Simulation Technique (HEST) consists of a cavity of uniform height bounded on the sides by a soil berm, above by an overburden of uniform thickness, and below by the test bed on the earth's surface. Horizontal racks of detonating cord are placed in the cavity and detonated at one end of the test bed. This detonation produces an explosive wave that propagates across the test bed, loading the earth with an overpressure pulse that decays with time because of the compression and lifting of the overburden. Since 1964, there have been approximately 40 such tests on test bed areas ranging from a few hundred to l0 5 sq ft., simulating peak overpressure conditions between about 100 and 6000 psi and specific impulses between a few and over 100 psi-sec.

Jan 1, 1971

By A. A. Scheil, S. I. Hoyt

In technological studies on steel considerable emphasis has been placed on the identification of the foreign inclusions, testimony of which is adequately given in the metallographic literature covering methods for their identification. The outstanding accomplishment in this field is the scheme devised by Campbell, Comstock and Wohrman for identifying various oxides, sulfides, silicates and other constituents by systematic etching tests and microscopic examination.' The time involved in carrying out this procedure has led to attempts to secure quicker methods, or at least to shorten the time required to secure essential information. An example of this is the use of dark field illuminatin,2 but when this was tried out by the authors it was found that cavities and pits on the polished surface appeared bright on a dark field and could not be distinguished from small glassy inclusions. Still another means is the Leitz Ultropak, an instrument equipped with optical units for the illumination of the specimen by reflected light to secure an effect similar to dark field illumination. The structures are made visible in exceedingly sharp details by utilizing the inherent properties of the samples, such as refractive index, absorption coefficients and reflection powers. We have had no experience with the Ultropak, but a recent paper by Benedicks and Löfquist3 describes methods for determining the refractive index of (Fe, Mn) O and MnS by the use of this equipment. Presumably this method would be subject to about the same limitations as dark field illumination, though the, feature added by Benedicks and Löfquist appears to offer great promise in inclusion identification.

Jan 1, 1935

By R. M. Rose, K. A. Jones

Resistive measurements ulere made on superconducting niobium single crystals in transverse magnetic fields. Crystals were grouln in both high and ulfrahigh vacua, doped with stnall quantities of oxygen, and annealed in ultrahigh vacua at temperatures from 900' to 1350°C. Maxima in the fluxoid pinr~ir~g force were observedfor the [100] and [210] directions. The increase of the critical current density with dissoved oxygen was seen to saturate at relatively low concentration. This behavior, and the variation of J, and residual resistivity (as a function of oxygen content and annealing) of both clean and dirty gassy) crystals, is seen as a consequence of the formation of clusters with (210)~b habit planes and (200)ffo common boundaries. These suboxide clusters are apparenlly stable at high temperatures and very low oxygen concentrations. It is generally known that dissolved oxygen at concentrations well below the solubility limit sharply increases the critical current density of superconducting niobium.' Such a result would not be expected if Nb-0 solutions were random, not even as the result of segregation on the scale usually encountered in solid solutions. According to the Kim-Anderson theory of flux creep,' the critical transport current density is determined by the pinning force Fp associated with some feature of the microstructure. As the Lorentz force. a or (J X R), of the transport current in the magnetic field approaches Fp, flux creep and then flux flow occur. The pinning force is expected to be quite small if the heterogeneity involved is significantly smaller than tte range of coherency which for niobium is circa 250~.~ Although the strain field of an individual oxygen atom in the niobium lattice is relatively large, it does not seem plausible that individual atoms could be so effective as to account for the data. Also, ~ramer~ found that straining and strain aging specimens containing small amounts of oxygen on occasion decreased the residual resistivity. A possible explanation for the above behavior may be found in the work of van Ooijen and van der Goot,= who found that annealing changed J, for niobium foils containing oxygen, and they attributed the changes to ordering of the oxygen atoms. This phenomenon has been observed by other investigators using X-ray and PROCEDURE Cylindrical 4-in.-diam niobium single crystals with axial orientations [ill], [110], [112], and [oo~] were grown from pure niobium, see Table I for analysis, in an ion-pumped ultrahigh-vacuum system using the electron beam floating zone technique. Total pressure during growth was lo-'9 torr: the oxygen partial pressure was less than lo-" torr, as determined by a mass spectrometer. These crystals will be referred to as the "clean" crystals. Similar crystals were also grown in another system at a pressure of 5 X 10"6 torr. These crystals will be referred to as the "dirty" crystals. Specimens 14 in. long were cut from the as-grown crystals and one end was polished down to no. 600 carbide paper smoothness. A back-reflection Laue photograph was then taken in order to fix the crystallo-graphic directions transverse to the crystal. The critical current density J,, the current density necessary to produce a voltage drop of 1.0 pv between voltage leads placed a in. apart, was determined as a function of the magnitude and direction of the transverse magnetic field and of the oxygen concentration. The technique and experimental arrangement was essentially similar to that of Tedmon et al.' In the remainder of this paper, the azjmuthal angle $ for the field H is referenced to the [ I101 direction in all four crystals, and oxygen was added in small equal increments by anodization and annealing.7 The resistivity ratio, RR, of the resistance at room ternperature to that at 4.2"K (H =7.00 kG) was determined as well.

Jan 1, 1970

By A. A. Scheil, S. I. Hoyt

In technological studies on steel considerable emphasis has been placed on the identification of the foreign inclusions, testimony of which is adequately given in the metallographic literature covering methods for their identification. The outstanding accomplishment in this field is the scheme devised by Campbell, Comstock and Wohrman for identifying various oxides, sulfides, silicates and other constituents by systematic etching tests and microscopic examination.' The time involved in carrying out this procedure has led to attempts to secure quicker methods, or at least to shorten the time required to secure essential information. An example of this is the use of dark field illuminatin,2 but when this was tried out by the authors it was found that cavities and pits on the polished surface appeared bright on a dark field and could not be distinguished from small glassy inclusions. Still another means is the Leitz Ultropak, an instrument equipped with optical units for the illumination of the specimen by reflected light to secure an effect similar to dark field illumination. The structures are made visible in exceedingly sharp details by utilizing the inherent properties of the samples, such as refractive index, absorption coefficients and reflection powers. We have had no experience with the Ultropak, but a recent paper by Benedicks and Löfquist3 describes methods for determining the refractive index of (Fe, Mn) O and MnS by the use of this equipment. Presumably this method would be subject to about the same limitations as dark field illumination, though the, feature added by Benedicks and Löfquist appears to offer great promise in inclusion identification.

Jan 1, 1935

By W. F. Stowasser

downdraft traveling grate process to agglomerate pelletized iron ore concentrates has been successfully demonstrated in a pilot plant at Carrollville, Wis. Work there followed several years of development in the Allis-Chalmers Mfg. Co. laboratories, and the pilot plant phase was carried out in cooperation with Arthur G. McKee & Co., consultants and engineers to the iron and steel industry. End result of the process is conversion of iron ore concentrates into a form which can easily be transported and smelted in the blast furnace. Process Description The first of two process steps incorporates the art of balling and prepares the concentrates for burning. The second step consists of burning the green balls on the grate machine to the hardness required for shipping and handling purposes and for reduction in blast furnaces, see Fig. 1. Facilities are provided at the pilot plant to receive carload quantities of concentrate. The concentrates are loaded into a 50-ton bin direct from railroad cars. Because of the variable moisture content of the concentrates after shipment in an open railroad car it is necessary to repulp and refilter the concentrates to maintain a uniform and proper moisture content for the balling operation. Concentrates are conveyed to slurry tanks, and the slurry, at 50 to 60 pct solids, is pumped to a 4x4-ft drum filter. The filter provides feed of uniform moisture to the plant. Magnetite concentrates are normally filtered to produce a cake containing about 10 pct moisture, a necessary requirement for the following balling operation. The filtered concentrate is conveyed to a rotary bin table feeder which acts as a surge bin for the filter cake and delivers a steady flow of concentrates to the balling drum. It is often desirable to make additions to the concentrates as they are fed to the balling drum. These additives, such as bentonite, increase the strength of the finished green pellet and improve ballability of the concentrate. A vibrating feeder supplies additive to the feed belt, and the additive is mixed with the concentrate in the balling drum. The balling drum, shown in Fig. 3, is 8x3-ft diam. An oscillating cutting bar maintains the lining in the drum by trimming off the buildup of excess concentrate as it forms. The drum is operated in closed circuit with a lx4-ft rod-deck vibrating screen. Undersize pellets or seed pellets from the screen are returned to the balling drum until they grow to the desired size. Size of pellets is controlled by the opening in the screen deck. The formation of pellets in the balling drum is affected by many variables. Some of these are: the size distribution of the feed, the particle shape of the concentrate, the feed rate to the drum, the moisture in the concentrate, the speed of rotation of the drum, the slope of the drum, and the type of trimming obtained with the cutting bar. In this process, attempts are made to control the pellet size within the limits of % to 5/8 in. diam. The screened oversize pellets are conveyed under a coal feeder where sufficient powdered coal is added to the belt to produce desired results in the burning process. The top size of the coal successfully used has been 20 mesh, and anthracite was used in the test program. Fig. 4 illustrates the vibrating screen and the coal feeder. The pellets and free coal are conveyed together to the 5x3-ft diam- reroll drum that rolls the coal onto the surface of the pellets. This drum is also equipped with a cutting bar. The prepared pellets, containing bentonite, water, and surface coal, are elevated to the traveling grate, which consists of a continuous strand of 37 pallets. Each pallet, with a grate bar area 2 ft wide by 1 1/2 ft long, has 14-in. high side plates, Fig. 5. Feeding and distribution of the green balls to the grate is handled by a short conveyor which oscillates back and forth across the 2-ft width of the grate. An adjustable vertical plate located several inches in front of the head pulley of the oscillating conveyor controls the height of the bed and levels the moving bed of pellets. This method of feeding prevents segregation of various size pellets as well as fines and produces a uniform, permeable bed. The pallet train moves under the furnace and across four windboxes, located beneath the pallet frames, see Fig. 2. As the green pellets are deposited on the grate, partial drying of the pellets begins over a 2-ft long updraft windbox. The low temperature air reduces the moisture in the pellets in the lower level of the bed and this operation is essential to prevent sagging of the bed during later stages of the Process. The air used for this drying is recuperated from cooling the pellets on the grate, and supplemental heat, required for starting the Process, is obtained from an auxiliary burner. The pellets are then moved by the grate into the furnace and over an 8-ft windbox, designated as the downdraft waste windbox. Products of combustion are exhausted from this windbox to atmosphere. The furnace, shown in Fig. 6, is constructed with three chambers to provide downdraft drying, preheating, and ignition, respectively, to the pellet bed as it passes through. Overall length of the furnace is 5.57 ft; however, the exterior wall ends may be moved to reduce the length and also adjusted to Obtain the bed height desired, The drying, preheating, and ignition sections of the furnace are supplied with medium temperature

Jan 1, 1956

By G. W. Tracy, R. D. Carter

Numerical calculations were made to determine the behavior of reservoirs with high-pressure drawdown and wide well spacing where the initial productivity is low and the wells are completed by hydraulic fracturing. The two-phase flow equations were solved for the flow into a single well. This well was assumed to be producing from a reservoir with hydraulically created horizontal fractures (four different systems with fractures were studied). For comparison purposes, additional two-phase flow calculations were made assuming a reservoir with uniform rock properties. The two-phase flow results were also compared with the conventional calculation methods, which do not include the effect of saturation gradients resulting from a simultaneous flow of oil and gas which are normal to this type reservoir. It was found that the conventional methods predict (1) a high and too optimistic value of ultimate recovery, (2) a high producing rate and a high reservoir pressure at a given oil recovery and (3) a low trend of gas-oil ratio with oil recovery. Included in the two-phase flow calculations were provisions to control the oil production rate by an allowable rate and, also, by a gas-oil ratio penalty rule. For the systems with hydraulic fractures, the producing rate was controlled by the gas-oil ratio penalty rule for most of the life. This is in contrast to the system with uniform rock properties which went "on decline" almost immediately. An unexpected characteristic of the systems which included fractures was the early rise in producing gas-oil ratio from 730 cu ft/bbl to approximately 1,200 cu ft/bbl, followed by a "leveling off" before the normally expected gas-oil ratio rise began. Additional features which are a result of hydraulic fracturing are (I) greater ultimate recovery, (2) higher average producing rates and (3) a lower average reservoir pressure at a given oil recovery. INTRODUCTION Some oil fields discovered during the past few years are producing from certain volumetric ally controlled reservoirs (often referred to as solution or internal gas- drive reservoirs) which are characterized by high-pressure drawdown at the wells. Since the available pressure drawdown at a well is limited by the static reservoir pressure and the producing rate is controlled by the available drawdown, wells completed in this type of reservoir usually produce at a rate less than the allowable from the time of completion. Because of this, this type of reservoir is referred to as a low productivity reservoir. Economic considerations require the use of wide well spacing and well stimulation by hydraulic fracturing to make commercial wells in this type of reservoir. Performance predictions for volumetrically controlled reservoirs have been made using a combination of two standard equations. 1. The "Schilthuis" or "Muskat" type material balance equation is used to relate the average reservoir pressure and the cumulative oil recovery. 2. The results from the material balance equation and the productivity factor as described by Pirson' are used to relate the cumulative recovery with producing rate and time. The material balance equation assumed uniform pressure and liquid saturation conditions throughout a reservoir. The steady-state radial flow formula allows for a pressure gradient toward a well but assumes uniform liquid saturation. These calculation methods are adequate for application to reservoirs wherein the drawdown at the well to realize satisfactory producing rates is small compared to the total pressure. In low productivity, volumetrically controlled reservoirs, the pressure drawdown at the well is large cornpared to the total pressure. Although a precise number cannot be given for the magnitude of a large pressure drawdown, values in excess of 1,000 psi would definitely be included. For practical considerations, this usually occurs when the formation flow capacity is less than about 100 md-ft. However, this limit of formation flow capacity will vary with the well producing rate. The low pressure in the neighborhood of the well which results from a high drawdown causes evolution of large volumes of gas. This causes the gas saturation to be higher near the well than at a greater distance—-hence, a non-uniform gas saturation. Also, the relationship between the relative permeability to oil (K/K) and gas saturation is nonlinear but decreases approximately in an exponential way with increases in gas saturation. Because of this, the following chain reaction is established.

||Abad, Leopoldo F, College of Min, Univ of California Berkeley, Cal '23 ||Abarquez, Ramon F, Met, Bureau of Science Manila, P I '24 ||Abbey, Robert Graham, Student, Case School of Applied Science Cleveland, Ohio '21 Abbott, A N , Mines Supt , Mazapel Copper Co , Ltd Concepcion del Oro, Zacatecas, Mexico '23 Abbott, Clarence E, Gen'l Supt, Iron Mines Div, Tenn Coal, Iron & R R Co, 1405 Minnesota Ave, Bessemer, Ala '04 Abbott, Louis Benjamin, Chief Engr, Consolidation Coal Co, Elkhorn Div 'Jenkins, Ky '15 Abbott, Robert R , Met Engr, Peerless Motor Car Co Cleveland, Ohio '12 ||Abbott, Wells Osborn, Ray Consolidated Copper Co Hayden, Ariz '23 Abeel, George H, Jr, Cons Min Engr 4612 W 17th St, Los Angeles, Cal '18 Abel, Albert E, Asst to Pres, Valley Mould & Iron Corpn Sharpsville, Pa '19 ?Abeloff, Miran S Address Wanted '21 Abernathy, G E, Kansas State Teachers College Pittsburgh, Kans '20 Abey, Hiroshi, Min & Met Engr, Takata & Co, 2 Yeirakucho, Nechome, Kojimachi-ku,

Jan 1, 1923

By Alwyn Birchmore Cox, Ian William Wark

In defending the chemical theory of flotation, Taggart, del Giudice and Ziehl have criticized1 the views of those who prefer to attribute the effects of certain flotation agents to adsorption. Perhaps with some justification, they describe the latter term as the "haven of refuge of writers lost in a morass of shaky experiment and muddy thinking." We prefer to regard it, however, as a haven of refuge for writers who seek a conventional term to describe the formation of films of flotation reagents on solid surfaces, because in many cases it is not yet possible to specify the forces that hold them there. Originally, as Taggart and his associates state, adsorption connoted a concentration difference and nothing more. In recent years, workers in the field of surface chemistry have tacitly added other meanings, and they now speak of orientated adsorption of unimolecular films on a solid sub-strate, of chemi-adsorption, and of exchange adsorption. Thus the term adsorption may connote simply the Gibbs layer of excess concentration at the surface of a solution, or a unimolecular film at the surface of a solid. Perhaps this has led to the misunderstanding of Taggart, del Giudice and Ziehl concerning the relationship between surface tension and adsorption at solid surfaces. The change in "surface tension" accompanying adsorption at a liquid surface can be used as a measure of the adsorption, and the Gibbs equation as quoted by these authors correlates these two conceptions. But, to correlate two conceptions docs not necessarily imply an attempt to explain either, although sometimes such an "explanation" is carelessly inferred. Use of "surface energy per unit area" instead of the numerically equal but more difficult and less definite conception of "surface tension per unit length " would lessen many of the present difficulties. (Compare with Adam.2) At interfaces involving a solid phase, neither '" surface tension " nor " interfacial tension "can have any meaning, but the conception "interfacial energy per unit area" call be understood by anyone who is familiar with the concept of free energy. While it is true that surface energy cannot be directly measured at a solid surface,

Jan 1, 1939

By Sherwin F. Kelly

The Geophysics Education Committee was organized in 1938 and presented its first report at the A.I.M.E. annual meeting in February, 1939, at a session held jointly with the Committee on Geophysical Methods of Exploration. REPORT OF 1939 The first task the Committee set itself was to find out in which universities the subject of geophysics was being taught, and the manner in which such instruction was given. A questionnaire was drawn up and sent out to 147 universities in the United States, Canada, and abroad. Of these 100 replied. Their answers were then tabulated and analyzed, yielding the information summarized in the following pages. Two universities, Colorado School of Mines and St. Louis University, actually maintain departments of geophysics, while 3 Canadian and 31 American universities give courses on the subject. In other institutions, 45 in the United States and 5 in Canada, more or less extended reference is made to geophysics in lectures on other subjects. Altogether, there are at least 86 universities in the United States and Canada at which students may obtain instruction of some kind in geophysics. To enter the courses in geophysics given by 33 American universities, certain prerequisites are demanded, varying with the level at which the subject matter is treated. In analyzing the prerequisites, some assumptions had to be made: one year of college mathematics was taken to mean up to, but not including, calculus, while three years was presumed to embrace a course in differential equations. On this basis, 16 per cent require only elementary college mathematics, 40 per cent require differential and integral calculus, and 31 per cent require differential equations. A few demand even more advanced mathematics, while some list no prerequisite mathematics beyond high school. Evidently a student contemplating the study of geophysics should ground himself in calculus and differential equations. In physics, similar assumptions have been made as to time required in the subject. All of the universities giving geophysics require their students to take physics first, and 34 per cent require a standing in

Jan 1, 1940