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By John Griffen

THE distinguishing principle of the Tromp process is the use of a medium in the bath which is not stable, i.e., the solids will settle and the density of the medium increases with depth. A medium of uniform density can most easily be effected by agitation or by means which increase the viscosity of the medium. Either of these works against the sharpness of separation of coal from its impurities. The Tromp process grinds the medium solids to relative coarseness, allows them to settle downward in the bath without hindrance, and introduces horizontal currents of medium at intermediate levels between top and bottom of the bath. This prevents any accumulation of particles denser than the upper layer of the medium from which the clean coal is conveyed away or an accumulation of particles lighter than the bottom layer or medium whence the refuse is removed. In a relatively shallow bath making a two-product separation, the intermediate horizontal currents sweep these intermediate gravity materials away to be discharged with the refuse removed by the conveyor. Such a system provides a number of advantages. The gravity of separation can be changed simply by changing the density of the medium without changing particle size of medium solids or other conditions, as would be necessary with a system requiring uniform or stable density throughout the bath. Some installations in Europe separate at 1.40 sp gr on one shift, producing a superclean coal, and on the next shift reclean refuse from dry cleaning units and effect a separation at 1.80 sp gr. Medium solids may be much coarser in size consist, which reduces the viscosity of the medium and promotes its fluidity and in turn the sharpness of separation. Coarser medium solids with a more rapid settling rate are much more easily recoverable from the dilute medium rinsed from the products. The Tromp process is not limited to the use of medium solids having magnetic properties. Instal-

Jan 1, 1952

By D. U. Deere

The title of this chapter is "Indexing Rock for Machine Tunneling" or, a simplified approach to a very difficult problem. I do not think that we can divorce the considerations for conventional tunneling from that of the requirements in terms of geologic information that is necessary for machine tunneling. Experience has shown that in conventional tunneling, the rate of progress achieved in driving a tunnel and the cost involved can be almost directly related to the general rock quality and to the water conditions actually encountered. The very method selected for driving the tunnel or perhaps adapted during the construction period, that is, full-face, top-heading and bench, or multiple-drift, is largely determined by the degree of severity of the adverse geological features. The amount and type of support required to stabilize the rock behind the advancing face are also directly related to the ground conditions. The support may range from bald-headed to rock bolts placed as needed- perhaps pattern rock bolting, light steel sets, all the way to closely spaced heavy steel sets with full lagging and invert struts. At times crown bars, spiling, and breast boarding must be used to advance the face. Shotcrcte applied immediately to the arch and upper walls is a fairly recent advance in providing both temporary and permanent support. Ground-water inflows can further reduce the rate of advance, causing stability problems and reducing the overall efficiency of the mining crew. Required pumping may also be very expensive depending on the grade of the tunnel and the amount of water. And in shafts, of course, there is the pumping problem. To offset the adverse effect of the ground-water inflows, one must often resort to grouting ahead of the face. But this very operation which helps cut down the water inflow also increases greatly the time required for mining, and of course, there is additional cost involved in the actual operation. The conditions described above do not occur uniformly throughout the rock mass but rather they are concentrated

Jan 1, 1970

By Franklin R. Carpenter, W. P. Headden

TWO notes have already appeared in the Transactions concerning the columbite or tantalite of the Black Hills tin-mines. In vol. xiii., page 232, Prof. Schaeffer speaks of the mineral as tantalite, and concludes by saying that its separation from the tinstone "is a matter which will, I believe, prove puzzling to the wisest metallurgist." He also observes that he is unable to find by analysis in his specimens the least trace of columbic acid. Prof. W. P. Blake, in the same volume, at page 696, says: " Even if it [tantalite or columbite] were present to a considerable amount, it would not injure the tin in smelting. It does not alloy with tin, but carries a small percentage of tin, which would probably be liberated in smelting." He calls the mineral columbite from the fact that a great number of specificgravity tests invariably indicated that it should be so classed. We have made chemical tests as well as specific-gravity tests upon many samples from many different parts of the Hills. Our analyses have always shown the presence of columbic acid, and the specificgravity tests have always indicated columbite, as we have elsewhere shown.* As Prof. Blake has already observed, it is not found in such close association with the tin as to prevent separation by a rough handsorting, but it is usually present with the stream-tin. As Prof. Schaeffer says, it cannot be separated by ordinary concentration; and while, as declared by Prof. Blake, its columbic acid may not unite with the tin in any form, yet its iron and manganese oxides may be reduced, and thus lower the quality of the tin produced, as is also the case when the smelting charge contains wolfram. To determine the effect of columbite in the ordinary potassium cyanide assay, there were assayed at the Dakota School of Mines four samples containing different proportions of columbite. The results, published in the report of the school for 1888, seemed to indi-

Jan 1, 1889

By Robert A. Cook

Among the new devices for cheapening the cost of material entering into the manufacture of iron is the mechanical drawing of coke, by which the coke from bee-hive ovens is extracted with a minimum of manual labor. About twenty years ago, an ordinary plate-conveyer was put in use at the plant of bee-hive coke-ovens owned by the firm of Bell Bros. & Co., near Middlesboro, England. This conveyer ran close along the front of the ovens, and carried the coke to the cars. The ovens were drawn by hand, and a very great saving in cost was secured, as one man could draw and clean out twice as many ovens after the conveyer was put in use—he having no forking to do, and the coke being carried away as fast as it was drawn to the mouth of the oven. The next step was further to eliminate hand-labor as far as possible; and Mr. Thomas Smith of the Thorncliffe Iron Works, near Sheffield, patented in 1891 the machine for drawing coke which I here describe. This machine, the outcome of several years of experimenting, has now been in successful use since 1891, and there are between twenty and thirty of them in operation at present, and others building. The machine, as may be seen from Figs. 1 and 2, consists of a wedge-shaped shovel of proper width and thickness, connected with a steel rack of sufficient length to reach the back of the oven. The rack is supported by rolls, and guided by a device operated by a hand-wheel, which directs the shovel in the oven. The rack is driven by a pinion on a vertical shaft carrying a bevel-gear on the upper end. This bevel-gear is driven by another on the engine-shaft. The engine is single-cylinder, with reversible gear; and engine and machine are mounted on a truck, which is propelled

Jan 1, 1897

By Kenneth Cottingham

The number of completions in 1944 in Ohio was only slightly greater than completions in the preceding year, but the initial daily volumes both of oil wells and gas wells declined considerably. The dry-hole ratio was a little lower than in 1943, even though in the year under review considerable effort was made to find new production. No new areas of consequence were discovered. Thirteen new gas pools, the largest of which was 1000 acres and the average 565 acres, were opened during the year. Eleven of these pools were in the Clinton sand, one was in the Oriskany, and one was in the Berea. Approximately 15 small pools might also be rated as discoveries, but because only one or two wells have thus far been completed in each, they cannot at present be properly evaluated. The latter pools average about 120 acres each. Some extensions were made to existing gas pools. The number of oil wells drilled was only one less than in 1943, yet compared with the year 1941, when twice as many oil wells were drilled, the difference is startling. Effective Aug. I, 1944, a blanket subsidy was granted of 35¢ per barrel on all Cleveland-Chatham, Coming, and Lima grades of oil, and 75¢ per barrel on Pennsylvania grade crude. The subsidy was authorized by the Office of Price Administration, with reimbursement to purchasers of the various grades made through the Defense Supplies Corporation, a branch of Reconstruction Finance Corporation. For several years the small operator, particularly the owner of stripper wells, was in a serious position. The subsidy has been a means of real help and, in addition to aiding the operator, it has prolonged the life of many small wells that otherwise would have been abandoned, with consequent loss of daily production and unre-covered reserves. It is questionable whether the price increase is sufficient to revive production of Corning grade, which has

Jan 1, 1945

By C. C. Hagenbuch

Machine loading of coal into mine cars is increasing rapidly. Particular reasons for its use frequently apply to certain localities, but in general, it is profitable to install mechanical coal-loading equipment: (I) when existing hand-loading contract rates prevent further cost reduction; (2) when the height of the coal bed requires that either top or bottom must be taken to place cars in rooms; (3) when labor shortage or limited house-plant capacity prevents the production of desired tonnage ; (4) when tonnage requirements are in excess of possible hand-loaded production from developed areas; (5) when working places are scattered and it is possible to concentrate production, and therefore supervision, by the installation of mechanical equipment; (6) when rapid development is essential. Having decided to install loading equipment, the problem then arises as to what type is best adapted for a particular mine or coal bed, the choice lying between mobile track equipment, pit-car loaders, scrapers, shaker conveyors, belt conveyors and drag conveyors. MajoR FactoRs Influencing Choice of Equipment In determining the type of equipment to be used, the following major factors must be studied: Grades.—Adverse grades, while permitting other types of loading equipment to work successfully, may prevent the success of a shaker conveyor installation. Thickness of Bed.—The thickness of coal governs the choice of equipment. A machine that requires 5 ft. of head room should not be selected for a 3-ft. bed where otherwise it would be unnecessary either to brush top or to lift bottom. Nature of Pavement.—Soft or scaly bottoms are unsuitable for the use of any type of digging loader, shaker conveyors or scraper loaders. nigging loaders and scraper loaders scale the bottom, mixing it with the coal and causing preparation difficulties; shaker-conveyor drives frequently work themselves loose, destroying the conveyor alignment and creating maintenance problems. Nature of Roof.—With any type of loading machine, it is policy to obtain the maximum possible tonnage per move per set-up. This must

Jan 1, 1931

Hugh M. ROBERTS,* Minneapolis, Minn. (written discussion ? ).¬The paper by Messrs. Hall and Row marks a distinct advance in the art of diamond drilling, because it records a systematic-application of a method for directing the path of the diamond bit. Their work is an admirable example of engineering development. They had a definite object to attain; i.e., the drilling of many vertical diamond-drill holes to depths of 2500 or 3000 ft. (762 or 914 m.). They availed them-selves of a method of wedging seldom used, improved the manner of making the wedges, developed a technique of survey, and put the process into practical, continuous operation. So effectively has this been done that they determine the average cost of the work. The publication of the results, in the form of detailed diagrams, makes the application general to whoever has a similar problem. The wedging of diamond-drill holes has been practised in the Lake Superior region for the purpose of making branch holes, particularly where the original hole has penetrated a great thickness of glacial drift. The uneven nature of the iron formations has caused the results to be somewhat uncertain. One operation, in 1907, near the American mine on the Marquette Range, by the firm of Longyear & Hodge, predecessors of the E. J. Longyear Co., resulted in the drilling of a hole 1828 ft. (557 m.) deep, with two branches at depths 100 ft. (30 m.) and 770 ft; (234 m.), respectively. A second hole from the same set-up went to a depth of 2497 ft. (761 in.) with a branch at 185.0 ft. (563 m.). In this instance, the wedges were forged to the desired shapes and angles with respect to each other. A drill hole, sunk in 1915,. in the township of Bates in the. Iron River district of Northern Michigan, which penetrated 385 ft.

Jan 11, 1919

By C. E. Arnold

IN attacking the problems of mining and treating large disseminated copper orebodies such as those occurring in the Miami or the Ray district of Arizona, one of the vital questions to be decided is, "What is the value of the orebody per ton in place?", The importance of this question lies in the fact that its answer helps to reach a decision concerning the method of mining to be employed. Let it be assumed for the moment that milling and smelting practice, especially the latter, is more or less standardized; and has a cost incapable of much variation, while the cost of mining has a considerable range owing to the large number of mining methods by which a mine may be exploited. For instance, a method may be adopted whereby all the available ore can be extracted perfectly clean (i.e., unmixed with barren material) at a relatively high cost; or a method may be used involving the necessary dilution of a portion of the ore with waste, in order to recover that portion, thus giving a relatively poorer extraction but nevertheless a lower working cost than the former method. Naturally, between these two extremes there lie intermediate methods. In order to arrive at a solution of a mining method problem that is of any value, it is necessary that accurate and complete estimates of mining, milling, and smelting performances and costs shall be established. By way of illustration is given a, case of mining, by the system of undercutting and caving, a large orebody with an average content of 1.50 per cent. copper supposedly all in sulphide form, to which case has been applied those results in mining operations which one may fairly assume are to be expected when viewed in the light of G. R. Lehman's ore-drawing experiments, which form the subject of a paper to be presented at this meeting. It is assumed that the total. costs will be as shown in the following table:

Jan 9, 1916

By M. C. Fuerstenau

Enrollment in the mineral engineering departments at many of our universities has decreased substantially over the past few years, a fact that is due to a number of reasons. Some of the more obvious reasons are: (l) lack of student stimulation in the classroom, (2) absence or lack of salesmanship by the mineral industry faculty, (3) minimal financial support of academic programs by industry (some companies have been very generous, while others have given nothing), (4) failure of some companies to utilize the engineering backgrounds of personnel, (5) salary in some instances, and (6) job location in some in- stances. As some of these problems have been recognized, appropriate steps have been taken to correct them. Only one of the reasons listed is not subject to change, and that is job location. One university' that found itself in the position of reduced enrollment in the mineral industries is the University of Utah. Since the author was in the Department of Metallurgical Engineering at that university, and since data on enrollment and scholarship support have been published by that department, that department will be used for illustrative purposes to show the effect that active scholarship incentive can have on undergraduate enrollment. As Fig. I shows, there were approximately 35 total undergraduates in the department in 1966. Extrapolation of the freshman line from 1965 to 1966 (and previous years) suggested that no freshmen would be enrolled in metallurgical engineering by 1969 unless something drastic were done to alter the trend. In the Spring of 1966, 20 scholarships were offered to high school seniors as an incentive to enroll in metallurgical engineering. These scholarships were financed from a private endowment to the department, but at the present time industry is also contributing to the program. With these incentives, the department essentially doubled its total enrollment in three years, as shown in Fig. 1. Cornparison of this figure with the number of students on scholarships (Fig. 2) shows a direct correlation between undergraduate enrollment and the number of students on scholarship support.

Jan 1, 1970

By E. T. Turkdogan, L. S. Darken

Calcium ferrite melts were equilibrated with sulfur and oxygen-bearing gases at temperatures within the range 1290°C to 1620°C. The results show that at oxygen partial pressures below 10-4 atm the sulfide-reaction occurs and at higher oxygen pressures the sulfur dissolves in the melt principally as sulfate ion. It is also observed that when the product increases, sulfate ions are converted to pyrosulfate ions and the results permit the evaluation of the pyrosulfate/sulfate ratio. It is shown that the ratio y CaSO,/rCaO increases with decreasing concentration of calcium oxide in calcium ferrite, silicate and aluminate melts. Indications are that oxy-acids, e.g. silica, alumina and ferric oxide, increase yCaS0,. A few experiments were carried out within the sul-tide range and the results are in accord with those obtained by other investigators on aluminate and silicate melts. BECAUSE of the industrial importance and theoretical interest, many investigators have studied the reactions between molten oxides, silicates or alumi-nates, and gases containing oxygen and sulfur. The early work reviewed by Schenckl and studies made by Bardenheuer and Geller2 indicates that solution of gaseous sulfur in an oxide melt resulted in the replacement of the oxide ions by the sulfide ions. Measurements made by Grant and Chipman3 on the equilibrium partition of sulfur between molten iron and complex silicate melts also demonstrated that, for a given temperature and silicate composition, the distribution of sulfur between slag and metal increased with decreasing oxygen content of the metal. Fincham and Richardson4 studied the effects of temperature and partial pressures of sulfur and oxygen on the solubility of sulfur in simple silicate and alumino-silicate melts. They observed that at oxygen partial pressures below about 10-5 atm sulfur in the gas dissolved in the melt as sulfide ions, replacing an equal number of oxide ions of the melt. At oxygen partial pressures higher than 10-3 atm, sulfur entered the melt as sulfate ions. Similar studies were made by St. Pierre and Chipman5 using calcium ferrite and calcium silico-ferrite melts. The experimental data presented in this paper were obtained in this Laboratory about 10 years ago; this is the first formal presentation although a preliminary report was given previously.6 In each of these experiments, a pure synthetic CaO-Fe2O3 melt in a platinum crucible was equilibrated with a gas mixture (SO2-O2, SO,-air, SO2-CO, or SO2-CO2-CO) at a temperature ranging from 1296°to 1620°C. The experimental technique was essentially the same as that reported by Darken and Gurry,7 the main difference being that the atmosphere in the reaction chamber contained sulfur dioxide together with oxygen, or carbon dioxide-carbon monoxide

Jan 1, 1962

By L. J. M. Smits

A theoretical equation is developed describing membrane potentials of shaly sands as a function of the cation-exchange capacity per unit pore volume of the rock and saturating water salinity. This equation is based on the same simple physical model as that employed earlier7 describing the electrical conductivity of shaly sands. Experiments conducted with NaCl solutions showed that the equation is obeyed, except in the case of saturated salt solutions where minor deviations were observed. A possible explanation is given for this discrepancy. As the clay content and the porosity of shales may vary appreciably, shale membrane potentials also vary. It was found that membrane potentials of shales can be calculated accurately with the aid of the same theory. Consequently, changes in membrane potentials can be accounted for by simple measurement of cation-exchange capacities per unit pore volume of both shales and shaly sands. Charts are given to facilitate interpretation of the electrochemical part of the SP in terms of cation-exchange capacities and the salinities of mud filtrate and formation water. INTRODUCTION A spontaneous potential (SP) log is a record of the way in which the electrical potential of a sonde varies as it passes down a borehole. Such variations frequently reflect rock texture, e.g., permeable beds intercalated in an impermeable series often are indicated by a sharp change in potential. Nowadays it is recognized that SP logs may be interpreted in terms of formation-water salinity and formation shaliness. The four sources of the SP are illustrated in Fig. 1. El and E4 represent streaming potentials generated by the flow of mud filtrate through mud cake opposite permeable formations and through shale, respectively. An extensive review of the literature on the evaluation of these streaming potentials is given by Lynchl and will not be discussed here. The remaining part of the SP generally is called the electrochemical potential, which is divided into two parts: a membrane potential across the shale (E3, Fig. 1) and a membrane potential in the permeable sand at the diffusion boundary between formation water and mud filtrate (E2, Fig. 1). It was found by wyllie2 that the membrane potential across the shale, E3, is the most important contribution to the electrochemical potential, the shale acting as a semi permeable membrane. When the sand is clean it does not influence the diffusion process, so E2 equals the value of the so-called liquid-liquid junction potential observed when the two solutions diffuse freely into each other. When the sand contains clay, however, this interferes with the diffusion process and affects the diffusion potential generated. The greater the proportion of clay, the stronger this effect will be. Wyllie,3 Doll4 and Poupon et al.5 took this effect into account theoretically, starting from a physical

Jan 1, 1969

By A. G. Preban, R. J. De Angelis, J. B. Cohen, P. Gordon, D. C. Brillhart

Changes in stored energy, resistivity, density, X-ray line broadening, and dislocation arrangements (from transmission electron microscopy) have been mensured on copper specimens shock-loaded at 75 to 435 kbars. The stored energy in shock-loaded copper and changes in density and resistivity are larger than those after conventional deformation. A high density of twins makes an appreciable contribution to all the measured quantities. Dislocation densities rise to values of 1011 lines per sq cm at the highest pressure. The resistivity, density, and X-ray In a study of the effects of shock loading on copper, changes in stored energy, resistivity, density, hardness, lattice parameter, line broadening, and dislocation structure have been examined after subsequent annealing of specimens shocked to various pressures. This paper presents certain aspects of the data, taken by two groups, one at the Illinois Institute of Technology, and the other at Northwestern University, and compares the changes in these properties, and what they indicate about the effects of shock deformation. measurements yield dislocation densities in substantial agreement at all pressures, after correcting for the effects due to the twins. At the higher pressures, electron microscopy yields dislocation densities that are lower by a factor of about 5 to 10. Dislocation densities from stored -energy measurements are high; this finding can be rationalized by the consideration that the deformation twin boundaries present are largely incoherent. There is no evidence for homogeneous dislocation nucleation during shock loading. Shock loading any metal or alloy, such as copper, causes a large increase in yield strength, with dimensional changes of the order of only a few percent."' Other properties have not been extensively studied, but this result clearly indicates the importance of examining the substructure. Previous studies of the substructure of conventionally deformed specimens have been made using electron microscopy,3-6 X-ray diffraction,7,8 and etch pitting.9,10 The dislocation density can reach values of about 10" per sq cm; and the dislocations are arranged in cells approximately 0.15 in size. The substructure varies widely, however, from point to point in the specimen. The substructure of explosively loaded copper consists of cells of about the same dimensions6,11 but their size is more uniform.6 Profuse twinning occurs12,13 and the twins are often too small to be detected optically.6,13 The boundaries outlining these twins appear to be incoherent.14 There is now ample evidence 13-15 that twinning is a strengthening mechanism in fcc metals but this is only part of the strengthening effect in shock-loaded copper.* From the twinning systems which operate in shock-loaded single crystals,13 and from changes in texture on shock loading,17 it has been shown that both the

Jan 1, 1968

By H. J. Snyder

Both the room-temperature and 600°F (315°C) primary solid-solution phase boundaries for the silver comer of the Ag-Cd-In temary system have been determined using X-ray diffraction and metallo-graphic techniques. Solid solubility of indium in silver at room temperature and 600°F (315°C) is shown to be between 20.3 and 21.7 wt pct, and corrects the previously extrapolated value of 18 wt pct appearing in the literature. The solid solubility of cadmium in silver at room temperature, not previously established, is shown to be between 34.9 and 41.3 wt pct. The solid solubility of cadmium in silver at 600°F (315°C) is confirmed as 43.2 wt pct. The shape of the primary phase boundary line for the subject temary system appears straight at room temperature and curves con-vexly towards the solvent (silver) comer at 600°F (315°C). THIS investigation was undertaken to initiate development of the Ag-Cd-In ternary diagram by establishing the primary solid-solution phase boundary in the silver corner of the diagram. At the present time, a diagram for this ternary system is not available, while this system appears to offer potential for a variety of uses. One alloy in the system has already proven to be useful as a control rod material in nuclear reactors.1"3 To encourage additional exploration of the potential of the system an understanding of its ternary diagram would be beneficial. It is towards this end that the present study is directed. LITERATURE SURVEY In undertaking this study, a comprehensive literature survey was first conducted to find information that would be useful for guidance. Useful knowledge did result from investigating the respective solubilities of indium and cadmium in silver as indicated in the binary constitutional diagrams of the systems Ag-In and Ag-Cd and also reviewing possible shapes of ternary primary phase boundaries. Weibke and Eggers~ used metallographic techniques to establish the system In-Ag as illustrated in Fig. Is This diagram shows that silver in the solid state is capable of dissolving approximately 18 wt pct In. This solid solubility of indium in silver holds true from room temperature up to 1276°F (691°C), then decreases continuously up to 1'761°F (960.5"C), the melting point of the silver. The solid-solubility limit of indium in silver established by Weibke and Eggers has been confirmed by Hume-Rothery and Reyno1ds. G Durrant' used a method which consisted of microscopic examination of quenched specimens to establish the Cd-Ag system as displayed in Fig. 2.' The primary phase boundary of Fig. 2 proved to be in good agreement (ie., within 1 wt pct) with other studies*'1' of the Ag-Cd system made using X-rays and metallog-

Jan 1, 1968

By F. L. Fayers, J. W. Sheldon

It has been a matter of concern to the petroleum industry to determine what effect the capillary term has on saturation profiles, since these profiles determine ultimate economic oil recovery. In their original solution of the non-capillary two-phase flow problem, Buckley and Leverett&apos; showed that solutions of the two-phase flow equations became multiple-valued in saturation. Since it is physically unrealistic for saturation to have more than one value at a given position, Buckley and Leverett resolved this difficulty by introducing a saturation discontinuity or "shock". They evaluated the strength and position of the shock from material balance considerations. Recently Sheldon, Zondek and Cardwell&apos; have demonstrated that the method of characteristics can be used to solve this and related problems. Owing to capillarity it is physically unlikely that saturation shocks occur in an oil reservoir. Buckley and Leverett suggested that the effects of interfacial tensions should be included in the fluid flow equations, if the solutions are to give continuous single-valued saturation distributions. An analogy to this problem is encountered in the theory of wpersonic compressible flow where the introduction of the viscous term eliminates shock behavior. However, the mathematical form of the capillary term in the porous medium fluid flow equations differs from the viscosity term in the Navier-Stokes equation. This paper demons~rates that capillarity does eliminate the triple-valued behavior and indicates the magnitude of capillary and gravity effects on the saturation profile for a variety of systems. DERIVATION OF LAGRANGIAN AND EULERIAN FORMS OF THE DISPLACEMENT EQUATION The equations representing capillary, two-phase flow are given by applying Darcy&apos;s law and a material balance condition for each phase. The familiar Darcy and material balance equations are as follows. ^U*^0......<3, ^^r=°......c« S is the saturation of the water phase, and B the inclination of the porous medium. Pressures in the oil and water phases differ by the capillary pressure associated with the interfacial tensions, P.-P.=pAS)..........(5) where p, is determined experimentally. The porous medium is said to be oil-wet if P, > Po and water-wet if P, < Po. If the fluids are incompressible and the total volumetric flow rate, q, is constant, then v, f v,, = q...........(6) By eliminating P.. /»,, and v, from Eqs. 1, 2, 5 and 6 it follows that It is convenient to normalize the variables in the problem after the manner of Handy and Hadley% so that Eqs. 3 and 7 become where j,, = —, the fractional flow of water; (F, is a capillary pressure normalizing constant.) Substitution of Eq. 9 into Eq. 8 gives In this partial differential equation for an initial value

By G. W. Gross

A commercial deposit of white kaolinite clay contained in the sandy overburden of the Cambrian Gatesburg formation in Central Pennsylvania was successfully mapped by combined SP and resistivity methods and results were checked by drilling. Resistivity minima in the range between roughly 2000 and 3500 ohm-meters coupled with second-order SP maxima of 50-60 mV contrast were found to characterize commercial white kaolinite clay beneath not more than 30-40 ft. of sandy overburden in the area stdied. This investigation supports the hypothesis, established previously, that certain SP phenomena may reasonably be ascribed to diffusion and membrane potentials produced by interaction of clay lenses, sandy matrix, and ground waters. The success of this test proves that this prospecting technique can assist in locating clay deposits in sandy overburden derived from the weathering of sandstones and carbonate rocks such as the Cambrian formations of Central Pennsylvania. In a recent paper, Gross and Moore (1959) described broad self-potential minima above the outcrops of the Cambrian Gatesburg formation. These "first-order" SP anomalies, of 220-350 mV contrast (Figure 7), are related to the peculiar sandy residual soil covering the Gatesburg formation. Small positive ("second-order") peaks of 50-60 mV contrast are superposed on the bottom or flanks of the first-order troughs. They appear to be related to lenses and layers of kaolinite clays within the sandy Gatesburg overburden. Both first-order and second-order anomalies show a characteristic inverse relationship with apparent resistivity profiles in most cases. An explanation in terns of liquid-junction and shale potentials was advanced. According to this working hypothesis, shale potentials are generated: 1) at the contact of the sandy Gatesburg overburden with the more argillaceous soils of surrounding formations; 2) at the boundary of clay lenses contained in the sandy matrix of that overburden. Concentration gradients between interstitial infiltration waters and perched water tables within the Gatesburg overburden are believed to give rise to the liquid-junction potentials. In order to test this hypothesis further, a detailed study was carried out of a second-order positive anomaly on the property of the Woodbury Clay Co. at Mines (Blair County, Pa., Hollidaysburg folio of the U.S. Geological Survey). A second aim was to establish if combined SP and resistivity surveys are suitable as a practical method for delimiting favorable areas in which commercial kaolinite clay de~osits may be found by drilling. Drilling control was provided by the Woodbury Clay Co. PROCEDURES Instrumentation used for SP measurements was the same as described in the paper mentioned. For resistivity surveys, a direct-current voltmeter-ammeter device built by Georator Gorp. of Manassas (Va.) was used in combination with non-polarizing electrodes from the same manufacturer. Power was supplied by one to six 45-volt, heavy-duty B-batteries

Jan 1, 1961

By C. G. Dunn

MANY investigations have been made concerning the nature of plastic deformation and recrystallization of metals either in the form of polycrystalline materials or in the form of single crystals. However, similar work on strip materials composed of large grains as thick as the strip and having a high degree of preferred crystal orientation has not been carried out extensively. Such materials are ideal not only for studying changes in single crystals under conditions where neighboring grains exert their influences but also for obtaining the, complete change in orientation of a grain or group of grains during the course of plastic deformation and subsequent recrystallization. It is well known that first-order twins in the form of Neumann bands may be produced during the plastic deformation of ferrite crystals, particularly silicon ferrite crystals.1-3 Furthermore, it is believe that high-stress regions exist in the vicinity of these bands4a and it has been said that these banded regions would be active in recrystallization processes.5 Evidence to that effect in silicon ferrite had already been presented with photomicrographs showing recrystallization among Neumann bands during the early stages of recrystallization.5,6 Similar evidence has been published for nonferrous metals.5 Merging of fine parallel deformation bands during annealing to form twin bands of ordinary appearance in alpha brass has been offered not only as evidence of an active role being played by mechanical twins but also as evidence that such twins existed prior to recrystallization.5 Proof that such new structures are actually first-order twins, or even twins at all, must be considered inadequate except for those cases where X-ray or optical data have been obtained to confirm the necessary orientation relationship.7,8 A. B. Greninger has obtained excellent iliustrations of annealing twins in alpha irons Since his material was previously deformed by sharp hammering, a process that generally induces Neumann bands, the existence of twins following annealing might suggest that they grew from mechanical twins. In connection with transformation twins in alpha iron, Greninger reported that grains containing. three twin orientations occurred rarely and none occurred with three sets of well-developed bands.9 The work at the Pittsfield Works Laboratory on silicon ferrite in the form of large-grained strip steel deformed a small amount and annealed to partially recrystallize the grains indicates that the deformation and recrystallization processes that lead to annealing twins involve more complex processes than the formation of Neumann bands and the growth of such bands. Some groups of annealing twins are obtained which contain not only three well-developed twin structures, but also contain more than one order of twins. It is also shown, in one case, that an interrelated group of twins did not arise within one single parent grain and, furthermore, orientations of grains in the group

Jan 1, 1944

By T&apos Ke, ing-sui

Accoriding to the classical theory of elasticity, the elastic portion of the stress-strain curve is represented by a straight line. such a representation implies that there is a linear relationship between strain and stress and also that strain is a single-valued function of stress and vice versa. Actually, such a one-to-one correspondence between strain and stress does not exist in real metals. A well-known example is the elastic after-effect on unloading. Another familiar example is damping or internal friction, that is, the dissipation of energy attending vibration. In an extensive review of such phenomena, zener1,2 has proposed the term "anelasticity" to denote that property of a solid in virtue of which strain is not a unique function of stress in the non-plastic region. The phenomena arising from anelasticity are called anelastic effects. The measurements on anelastic effects are important in many fields of metals technology. The, in precise instruments such as watch springs, difficulties often arise from the slight dimensional changes after fabrication. The internal friction or damping capacity of metals is often an important factor in deciding whether they are appropriate for instruments in which there are accompanying vibrations.3 However, for metal scientists, the study of anelastic effects furnishes a powerful tool for understanding many properties Of meta1s in terms of their microstructures or atomic interactions. In order to utilize the anelastic measurements to their fullest extent for acquiring such information, the experimental studies Of anelasticity must be interpreted by appropriate mathematical analysis. For a great many problems, however, the necessary information often Can be Obtained by general qualitative arguments. From the definition of anelasticity, any physical changes occurring in a specimen as a result Of the applied stress will cause anelastic effects if such physical changes are accompanied by a delayed change of elastic strain. Under these circumstances, we have the condition that strain lags behind the stress. We may mention the stress-induced transportation phenomena as examples. These include the stress-induced thermal diffusion,4-7 the stress-induced diffusion of particles,8-l2 and the stress-induced viscous slip along the microelements in metals.12-15 The differential equations describing the microscopic mechanism in these phenomena lead to relations in which stress is linear with respect to strain (and/or their derivatives). Thus if we Can demonstrate that the superposition principle is valid under the circumstances in which the anelastic effects are observed, we would expect in the macroscopic relation a linear relationship between stress and strain and their derivatives. This report is to describe a number of anelastic effects observed in alpha-iron, and an attempt is made to derive valuable information from a critical study of these

Jan 1, 1949

By T&apos Ke, ing-sui

Accoriding to the classical theory of elasticity, the elastic portion of the stress-strain curve is represented by a straight line. such a representation implies that there is a linear relationship between strain and stress and also that strain is a single-valued function of stress and vice versa. Actually, such a one-to-one correspondence between strain and stress does not exist in real metals. A well-known example is the elastic after-effect on unloading. Another familiar example is damping or internal friction, that is, the dissipation of energy attending vibration. In an extensive review of such phenomena, zener1,2 has proposed the term "anelasticity" to denote that property of a solid in virtue of which strain is not a unique function of stress in the non-plastic region. The phenomena arising from anelasticity are called anelastic effects. The measurements on anelastic effects are important in many fields of metals technology. The, in precise instruments such as watch springs, difficulties often arise from the slight dimensional changes after fabrication. The internal friction or damping capacity of metals is often an important factor in deciding whether they are appropriate for instruments in which there are accompanying vibrations.3 However, for metal scientists, the study of anelastic effects furnishes a powerful tool for understanding many properties Of meta1s in terms of their microstructures or atomic interactions. In order to utilize the anelastic measurements to their fullest extent for acquiring such information, the experimental studies Of anelasticity must be interpreted by appropriate mathematical analysis. For a great many problems, however, the necessary information often Can be Obtained by general qualitative arguments. From the definition of anelasticity, any physical changes occurring in a specimen as a result Of the applied stress will cause anelastic effects if such physical changes are accompanied by a delayed change of elastic strain. Under these circumstances, we have the condition that strain lags behind the stress. We may mention the stress-induced transportation phenomena as examples. These include the stress-induced thermal diffusion,4-7 the stress-induced diffusion of particles,8-l2 and the stress-induced viscous slip along the microelements in metals.12-15 The differential equations describing the microscopic mechanism in these phenomena lead to relations in which stress is linear with respect to strain (and/or their derivatives). Thus if we Can demonstrate that the superposition principle is valid under the circumstances in which the anelastic effects are observed, we would expect in the macroscopic relation a linear relationship between stress and strain and their derivatives. This report is to describe a number of anelastic effects observed in alpha-iron, and an attempt is made to derive valuable information from a critical study of these

Jan 1, 1949

By John J. Schanz

INTRODUCTION The two prior Seeley W. Mudd books on mineral economics devoted their final chapters to themes having to do with the future. In 1932, the last chapter in Mineral Economics8 was "The Future Value of Mineral Property" by J. R. Finlay. Both the first edition (1959) of Economics of the Mineral Industries7 and the slightly revised second edition (1964) closed with "Minerals and Man&apos;s Future" by Zay Jeffries. We are not inclined in this third AIME volume on mineral economics to ignore the tradition of the prior volumes. Moreover, it always is fitting and proper to close a book about the mineral industries by examining in a rather general way the challenges and uncertainties that are perpetually strewn in our path as we pick our way into the future. Unlike its predecessor volumes, which were written to acquaint the nonspecialist with the economic characteristics of mineral resources and to provide data about the mineral industries, this edition was also designed with the mineral economics student and practicing specialist in mind. Thus it is anticipated that it will be both a reference as well as suitable for use as a textbook. Consequently, this closing examination of our changing perspectives about mineral resources devotes some space to the past events and current status of mineral economics as a field of study. The fears and forecasts of the past can be a perceptive and usually deflating way to begin an examination of the future. As we look up and down the track of time from the 1975 platform, we find that many of the past views of the future were transient in character, others were imperfect in their prognosis, while others were based on fears that now seemed unfounded. But down through the years some of the observations or expressions of concern have a persistency which perhaps reflects some elemental characteristics of mineral resources. On these "truths" rest our contemporary understanding of the economics of the mineral industries. The uncertainties and priorities for the next 25 or more years, not surprisingly, have a somewhat different mix than those that seemed most compelling to our predecessors in 1932 or 1959. So it is appropriate that we review how the perspective of the mineral economist has changed over the span of a half century. In light of the particular interest of AIME on the role technology must play, it is fitting that we close with some observations on that topic. THE EMERGENCE OF MINERAL ECONOMICS AS A FIELD OF STUDY The publication of Mineral Economics by the AIME in 1932 as a Seeley W. Mudd volume marked the end of emerging interest in

Jan 1, 1976

By A. W. Jenike

A theory of gravity flow of bulk solids like ores, concentrates, coal is outlined and an example of design for unobstructed flow is given. Mass-flow and plug-flow patterns are defined and related to the geometry of the bin. The effect of these patterns on segregation, first in-first out flow, and caking is described. This paper is a report on the results from the AIME sponsored project "Flow of Bulk Solids" which was carried out under the author&apos;s direction at the Utah Engineering Experiment Station, University of Utah, during the period 1956-1962. The theory has been applied to the design of numerous industrial storage plants. A QUANTITATIVE METHOD OF DESIGN FOR FLOW There is hardly an industry which does not store and handle solid materials in bulk form. When the volume of the solids is large, gravity is invariably relied upon to cause the solids to flow out of storage, through channels and chemical reactors. Such materials as ore, coal, cement, flour, plastics, clay, soil, to which a general term of bulk solids is applied, flow by gravity or are expected to flow by gravity in thousands of installations and by billions of tons annually. The chemical and process industry depends on gravity flow of solids in process and out of storage. Mining relies on gravity flow in block-caving, in ore passes, as well as in storage and loading bins. Agriculture uses gravity flow in elevators, in feed plants, and in farm silos. In practice, satisfactory gravity flow is seldom attained. Such problems as doming, piping (rat-holing), lack of live capacity, segregation, deterioration in storage, harass industry. In spite of the universality of these problems, until recently, there has been no theory of solids flow, no method of predicting how a solid would behave, and how the channel, bin, or hopper should be designed. In the late nineteen forties and early fifties, the theory of plasticity came of age and simultaneously the computer became widely available. These two factors permitted the development of a theory of flow of bulk solids. The work was conducted during the years 1953-1961. In conjunction with the development of the theory a method to measure the flowability of solids was also developed1-7 and the theory was ap-plied to the design of ore pockets, storage plants,16 chemical reactors and adsorption columns. A comprehensive report of this work is given in a previous work." THEORY OF FLOW The most important question which a theory of flow has to answer is: what conditions need to be satisfied for a given solid to flow uniformly and without obstructions through a channel? First of all, the following observations are made:

Jan 1, 1967