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By Wilber Stout

In Ohio, the annual output of coke made from native coals has averaged not more than 70,000 tons, or about enough to run a 200-ton blast furnace. Raw coal locally mined from the Sharon, or No. 1, bed was used for iron smelting in Mahoning furnace at Lowellville, Mahoning Co., as early as 1846. This practice was continued in the Youngstown district until the coal became scarce and the Connellsville coke more popular. At present, the Sharon bed contributes a part of the fuel for the production of ferrosilicon iron at Jackson, Jackson CO. About one-third native coal and two-thirds soft coal are used. In this state, coke, on a commercial basis, was first made in Jefferson County probably about 1861 or 1862. The coals used were the Steuben-ville Shaft, or Lower Freeport, and the Strip Vein or Middle Kittanning. The practice, however, was discontinued before 1880 because of the competition of superior foreign cokes. Beehive ovens, later built at Leetonia, Columbiana Co., were operated for only a few years; the coal used at this place is the Lower Kittanning or No. 5. In a desultory way, slack from the Pittsburgh coal has been coked at a few places in eastern Ohio, and attempts, either for experimental or for commercial purposes, have been made in other parts of the state. Small quantities of coke were made from the Upper Freeport coal at Salineville, Columbiana Co., and near Nelsonville, Hocking Co.; the results were poor. Tests were made of the Middle Kittanning coal near Zanesville, Muskingum Co., at Moxahala Furnace, Perry Co., and at Washington Furnace, Lawrence Co.; the cokes were all high in sulfur and ash. Attempts were made to coke the Clarion coal at Vinton Furnace, Vinton Co.; a small battery of molding ovens and a pile of high-sulfur coke yet remain to tell the story. The Pittsburgh coal was coked on a commercial scale at Utley and at Lathrop, Athens Co., but the operations were not successful and were soon abandoned. These failures and indifferent successes are not to be attributed to a lack of demand for a first-class coke, as Ohio has held a commanding place for many years in iron smelting; nor to a deficiency of coals, as the state has a vast reserve of such material. They are to be ascribed to the inferior quality of the native products offered to the trade. The cokes

Jan 1, 1920

By B. Zondek, W. T. Cardwell, J. W. Sheldon

The fundamental equations that are used to describe two-phase fluid flow in porous media are Darcy's law for each phase and an equation of continuity for each component. The special case of one-dimensional, incompressible, two-phase flow has received much attention in the petroleum engineering literature.1-10 The basic paper on the subject is that of Buckley and Leverett.2 Buckley and Leverett showed that one could eliminate the pressure and obtain a single partial differential equation for the saturation. They solved this equation for the case when gravity and capillary forces are negligible. A frequently encountered property of the solution of the basic partial differential equation is that, as time progresses, the saturation becomes a multiple-valued function of the distance coordinate, x. Buckley and Leverett interpreted the formation of multiple values as an indication that the saturation-distance curve had be-come discontinuous. They developed a method of determining the position of the discontinuity from a material balance. We solve the Buckley-Leverett partial differential equation using the method of characteristics and the concept of shocks. Our treatment is analogous to treatments used in the theory of supersonic compressible flow." Although the numerical results obtained are the same as those obtained by previous methods, we believe that this approach is more logical and has broader applicability. It can, for example, be generalized to treat the case when the fluids are compressible. It is not clear how one would go about doing this using the method of Buckley and Leverett. To illustrate the power of the method of characteristics with shocks, we solve a problem in gravity segregation which has not been treated previously in the literature. A special case of the general method developed here was used by Welge, to solve a particular fluid displacement problem. We consider two-phase incompressible flow along the vertical direction x in a porous medium. We assume that there is no flow transverse to .x. We measure positive in the upward direction. The fundamental equations are obtained from Darcy's law and the mass conservation law. Since the two phases are incompressible, mass conservation is equivalent to volume conservation.

By T. T. Quirke, L. C. McCabe

The object of the present investigation was to discover a physical basis for rank differentiation of coals, particularly the coals of the Illinois basin. Vitrainl was selected as the most appropriate coal material to use in the investigation, because of its homogeneity and ease of acquisition and handling. Previous Investigations.—Hoffman and Jenker2 have shown that their index of reflection is a characteristic of coal rank and that the Leitz slit microphotometer may be used in determining the different intensities of reflection. Zhemchuzhnikov3 measured the luster of several Russian coals with a color analyzer and found that the degree of luster was indicative of rank. Luster-volatile matter curves based on data from Sucan and Donetz coals were satisfactorily used for determining the rank or volatile content of other coals after the luster strength was determined. In 1934 Fisher4 reported refractive indices of 1.76 for bituminous vitrain and 1.87 for semibituminous vitrain. Investigation of Angle of Polarization.—Early in the present investigation several determinations of the refractive indices of the vitrains were made by immersing the minus 150 plus 200-mesh powder in oils. It was found that all the samples fell within the range 1.6 to 1.8. However, difficulty was encountered in securing oils in this high index range that were closely enough spaced to separate some of the coals. The writers made a number of determinations of the angle of maximum polarization from the polished surfaces of the vitrains and derived their refractive indices by the procedure described in the following paragraphs. Johannsen5 states the fundamental concepts underlying this procedure as follows: In general, in an isotropic medium light vibrates in all directions at right angles to the direction of propagation, and when it meets with another isotropic medium at an angle, part of the light is reflected and part refracted. It has been found that after reflection or refraction, the vibrations do not move with the same freedom in every

Jan 1, 1938

By T. T. Quirke, L. C. McCabe

The object of the present investigation was to discover a physical basis for rank differentiation of coals, particularly the coals of the Illinois basin. Vitrainl was selected as the most appropriate coal material to use in the investigation, because of its homogeneity and ease of acquisition and handling. Previous Investigations.—Hoffman and Jenker2 have shown that their index of reflection is a characteristic of coal rank and that the Leitz slit microphotometer may be used in determining the different intensities of reflection. Zhemchuzhnikov3 measured the luster of several Russian coals with a color analyzer and found that the degree of luster was indicative of rank. Luster-volatile matter curves based on data from Sucan and Donetz coals were satisfactorily used for determining the rank or volatile content of other coals after the luster strength was determined. In 1934 Fisher4 reported refractive indices of 1.76 for bituminous vitrain and 1.87 for semibituminous vitrain. Investigation of Angle of Polarization.—Early in the present investigation several determinations of the refractive indices of the vitrains were made by immersing the minus 150 plus 200-mesh powder in oils. It was found that all the samples fell within the range 1.6 to 1.8. However, difficulty was encountered in securing oils in this high index range that were closely enough spaced to separate some of the coals. The writers made a number of determinations of the angle of maximum polarization from the polished surfaces of the vitrains and derived their refractive indices by the procedure described in the following paragraphs. Johannsen5 states the fundamental concepts underlying this procedure as follows: In general, in an isotropic medium light vibrates in all directions at right angles to the direction of propagation, and when it meets with another isotropic medium at an angle, part of the light is reflected and part refracted. It has been found that after reflection or refraction, the vibrations do not move with the same freedom in every

Jan 1, 1938

By A. M. Gaudin, T. P. Meloy

Based on the equation for single fracture, a formula has been obtained for repeated fracture. Solution of this equation is obtainable analytically for a few examples and numerically for all others. Graphs of the size distribution equations have been obtained; they agree broadly with the experiments of others. In another paper1 we have considered a model and a comminution distribution equation for single fracture of brittle materials. Most comminuting devices, however, depend on the occurrence of repeated fracture. This is especially true of continuous cylindrical mills of the ball, tube, or rod type. But even in primary crushers there is some repetition of the breaking process, so that this paper should be of interest in connection with all comminuting devices. HALF LIFE AND PROBABILITY OF FRACTURE To facilitate the study of fracture it is useful to introduce the concept of the half life of a particle, In the ball mill, for example, we may start with 10,000 feed particles. The time, 7, by which one half of these particles have been broken is the half life of the feed under the prevailing experimental conditions. The probability of breakage bears an inverse relationship to the half life. In a ball mill, for instance, it can be shown that the

Jan 1, 1962

By P. V. Roundy, G. R. Mansfield

PUBLIC lands in Florida were first withdrawn from entry by President Taft on July 2, 1910, as a conservation measure because of their possible phosphate content. The reserve thus established was subsequently modified by further withdrawals and by restorations, so that on Jan. 1, 1934, it contained 66,796 acres, of which only a small part had been definitely classified. The reserved land was in scattered parcels, ranging from less than 40 acres to 320 or more, distributed in many counties. For administrative purposes and for final disposal of any of the numerous parcels, mineral classification of the land is legally necessary. In 1934 and 1935 the United States Geological Survey, under two successive grants from the Public Works Administration, prospected some 83 tracts of these lands in Polk County, comprising in all about 3300 acres, and six tracts comprising 240 acres in Citrus and Marion Counties. The tracts in Polk County were all in the so-called land-pebble field and the others in the hard-rock field. The Survey field party was under the direction of P. V. Roundy, from whose unpublished report the material in this paper is largely taken. The foreman of the prospecting crew was J. H. Wingate of Zephyrhills, Fla. The individual tracts were identified through the cooperation of the General Land Office, by transitman Hugh B. Crawford. This prospecting work fitted well the classification adopted for Public Works projects in general: it could not be done on any considerable scale under the Survey's usual appropriations; it gave employment to unemployed labor; and it may be expected ultimately to repay the Government in royalties more than the cost of the exploration. COMMERCIAL PROSPECTING METHODS Commercial methods of prospecting for phosphate in Florida have been briefly described by Mansfield.1 In the hard-rock field, where the floor of the phosphate deposit is extremely irregular, it is customary to drill as

Jan 1, 1937

By H. S. Chiang, D. F. Lu, S. S. Peng

INTRODUCTION The most important element in a successful lingual mining is a good roof control. The modern longwall mining employs hydraulic powered supports for roof control at the face area. The application of hydrau¬lic powered support requires the knowledge of over¬burden strata behavior for proper selection of sup¬port type and capacity. Failure to do so could lead so serious loss. There are several methods available for determining the required support capacity (1-3). While these methods are simple for application, they do not include the complicated roof behavior observed in longwall mining. As research progresses and operational experience accumulates (4,5), the concept about the designing and selection of powered support improves. The design of a longwall powered support consists of three major phases: 1. structural integrity and stability of the powered support, 2. external loadings induced by the movements of the overburden strata, and 3. interaction between the support, roof and floor. Phase 1 involves structural analysis (5) and full-sized testing (6) of the supports. Its validity is limited by the accuracy of the assumed external loading because of the uncertainty about the actual loading underground. The third phase includes the reaction of the support and the floor to the movements of the overburden strata and vice versa. Among the three phases, the second phase concer¬ning the external loading seems to be the least known because of the complicated behavior of the roof strata. There are many unresolved problems. For example, does the main roof break periodically and cause periodic roof weighting in the face area? If so, are there any rules governing its behavior? How does the roof load on the support canopy! Finally, how can one determine the required support capacity and select a proper type of support to meet a certain roof behavior? In order to answer those questions, underground instrumentation and observations were performed at 4 longwall panels in 3 separate mines for the past two years. This paper summarizes the current findings. PANEL LAYOUTS AND EQUIPMENT EMPLOYED The three mines selected are all located in West Virginia; two in northern and one in southern West Virginia. As shown in Table 1, seam conditions (i.e. seam, depth and thickness) and panel layouts are different among the three mines. The most significant difference in equipment is the face powered supports. Three mines used three different types of shield; 2-leg caliper, 2-leg lemniscate, and 4-leg lemniscate chock-shield. (Fig. 1) UNDERGROUND INSTRUMENTATION AND OBSERVATION PROGRAM Two events were instrumented in each observed longwall face: one was the hydraulic pressure (resistance) of the powered supports and the other was the canopy load distributions. In addition, the gob caving conditions were visually observed and recorded. Leg and Support Resistances One or two automatic Weksler Pressure Recorders were installed at the designated shield support,. In most cases, the daily charts were used to record the pressure variations in both the front or the rear legs (for the 4-leg shield), or in both the leg and the fore-pole ram (for the 2-leg shield). The recorded pressure w a s then converted to load or resistance by multiplying it by the cross-sectional area of the hydraulic leg or canopy ram piston. Fig. 2 shows the typical pressure-recorded charts for the 4-leg and 2-leg shields in a 23-24 hour period. The support resistance is the summation of the resistance in each of all the legs for that support. Generally, the resistance of the fore-pole ram will not be considered in determining the capacity of the support because of its rather small vertical compo¬nent force at the tip of the fore-pole. Canopy Load Distribution External load distribution on the canopy as exer¬ted by the roof was monitored. The measurements employed 12-14 pieces of pressure cells (6-inch square) that were uniformly arranged in two rows on the canopy. After support setting, the pressure changes in the cells were monitored at various stages of the mining (supporting) cycle while the support leg pressures were recorded continuously by the pressure recorders. Based on the calibration chara¬cteristics of each pressure cell as performed in the laboratory before and after each underground test, the cell pressures were converted to actual loadings. From these load measurements the canopy load distri¬butions and the relations between measured canopy loadings and support leg resistances were determined. Accordingly, the supporting efficiency of the shield support can be determined.

Jan 1, 1982

By R. E. Delavault, H. V. Warren

In normal soils there are usually 10 to 50 parts of copper in every million parts of .soil. Only 0.2 to .5 pct of this copper can be found by any simple cold chemical attack. Now, with rubeanic mid reagent paper, a prospector or field geologist can detect as little us 4 ppm of readily available copper ill soil. This degree, of sensiticity is enough to determine the presence. of copper anamalous an as and, ecentually, to discouer copper mineralization. Circumstances determine whether it is better to make analyses in the field or in a permanent laboratory. The rubeanic acid test described in this article has been designed primarily for field use: it is simple and virtually foolproof, and it requires a minimum of field kit." It is sensitive, easily de- • Ed. Note: Persons Interested in purchasing kits suitable for rubeanic acid prospecting can obtain information by writing Eldrico Geophysical Sales Ltd., 633 Hornby Street. Vancouver 1, B.C. The University of British Columbia does not produce these kits for sale and has no financial interest in their production tecting 4 ppm of readily extractable copper in a soil. This is by no means a quantitative test, but it is accurate enough to provide a valuable indicator of copper anomalous areas for both prospectors and field geologists. The easiest method for detecting metal deposits that do not produce visible float or stains is to make a simple chemical test for the metal in overlying soil, or in the silt of a stream that may have picked up metal farther upstream. In Brief: Testing for copper may be done easily by shaking a soil sample with strong acetic solution in a small test tube and pouring the mud into a small filter, the tip of which rests upon a strip of reagent paper impregnated with rubeanic acid (di-thio-oxamide). When copper is present—and only when it is—a blue spot develops. The more copper, the darker the spot. If the copper content is merely the small amount present everywhere, there is a pale blue or hardly visible spot; if it is abnormally high, the spot will be dark. There are, of course, intermediate cases where the experienced geochemist cannot tell offhand whether a medium-strength spot represents rich agricultural soil, weak copper mineralization, or distant rich copper mineralization. Reagents and material are inexpensive; the test may be readily done on the spot with a simple kit easy to pack and handle. Anyone interested in general problems of soil sampling as applied to prospecting may refer to an article recently presented to the AIME. In exploration work it is the contrast between the metal content of anomalous and background areas that is important; absolute values become of greater interest when an anomalous area is being investigated in detail. With specific reference to copper, it has been the authors' experience that the amounts of metal extracted from anomalous and normal soils with buffer solutions of decreasing pH show better contrast if an acid reagent is used. This contrast tends to increase with increasing acidity until 3 to 4 pH is reached. Using a short cold attack on unheated soil, it has been found that further increases in acidity do not produce better results, and only increase the hazards involved in carrying strong acids. An acidity of about pH 4 is satisfactory for direct determination of copper by dithizone. But dithizone itself introduces some problems: it must be made up fresh at frequent intervals, and with some soils, notably those with much ferric iron, oxidation mag take place before all the copper has reacted with the dithizone. Rubeanic acid keeps its strength unimpaired for long periods, is unaffected by oxidation, and is practically specific for copper at pH 4. Consequently it seems an ideal reagent to use in prospecting for copper. History and Background: Rubeanic acid (systematic name: dithio-oxamide (SC-NH2) has long been known as a spot test reagent for some heavy metals with which it gives a number of compounds. Only copper and some metals of the platinum family are believed capable of providing any ru-beanate compounds under conditions of moderate

Jan 1, 1959

By Melvin H. Podwysocki

Lineament and fracture analysis have enjoyed a resurgence of interest over the last several years, particularly since the advent of the Landsat series of Earth resources satellites. Some applications for lineament analysis include mineral, petroleum and ground- water exploration, engineering studies such as highway routing, mine roof stability, dam and power plant siting and general tectonic studies. The needs of each study may be different, but the general problem of large masses of data is common to all. Methods for efficient handling of the information and some statistical methods for its evaluation are discussed. These include comparing the lengths of the fracture population against known distributions, trend surface analysis of fracture lengths and number per unit area and multivariate analysis of rose diagrams. Examples are shown in an experimental program for predicting the presence of reef structures, areas of potential petroleum production.

Jan 1, 1977

By D. J. Carney, R. R. Burt, E. J. Whittenberger

Hardenability (multiplying) factors for carbon, mongonese, silicon, chromium, nickel, and molybdenum have been developed for hypereutectoid low-alloy steels in which bainite is the first subcritical transformation product. These factors permit the calculation of 95, 80, and 50 pct martensite hardenability from chemical composition when steels with spheroidized structures are quenched from 1475°, 1525°, and 1575°F. The strong contributions to hardenability of the less expensive elements, silicon and manganese, suggest their use to obtain additional hardenability in hypereutectoid low-alloy steels. DURING the past decade a number of investigators'"11 have carefully developed information which permits calculation of the hardenability of medium -carbon low-alloy steels from chemical composition and grain size. These data have been especially valuable in developing less costly low-alloy steel compositions with equivalent or Improved

Jan 1, 1957

By R. L. Wiegel

This article proposes a physical model for an idealized binary mineral system and for the process of liberation by size reduction. Based on this model, equations are derived relating the amount of each component liberated as a function of the ratio of the volumetric abundance of the two mineral components and the ratio of the mineral grain size to particle size. A definite relationship is shown to exist between the mineral concentration within a locked particle and the frequency of occurrence of such a particle. These relationships are used to obtain theoretical expressions for the concentration-recovery diagram. Physical mineral beneficiation processes are based on breaking a mineral aggregate to liberate the dissimilar mineral grains and then making use of their physical properties to separate the mixture into its components. The effectiveness of the process is therefore dependent on how well the minerals are liberated and how efficiently they are separated. Although a substantial amount of work is being done to improve our understanding of mineral separation processes, the study of mineral liberation itself has been almost completely neglected. The purpose of this theoretical study is to shed some light on the liberation phenomenon by: 1) proposing a physical model for an ideal binary mineral system, 2) treating mathematically the fracture of this system into liberated and locked particles, and 3) deriving an expression for the liberation characteristics of this system. The results of this study are useful in understanding the effect and importance of various parameters in liberation, and provide a basis for comparison with real mineral systems. 'RANDOM' MODEL It is recognized that liberation can be caused by detachment which results from fractures occurring at the mineral grain boundaries, or by size reduction which restricts the occurrence of dissimilar mineral locking to a portion of the resulting particles. The detachment effect is dependent on the relative strengths of the mineral grains and the bonds between them, and must be treated empirically for each mineral system. The size reduction effect, however, can be treated analytically if certain assumptions are made concerning the shape and geometrical arrangement of the mineral grains.

Jan 1, 1968

By L. H. Marshall

MALLEABLE-IRON castings frequently are made brittle by hot-dip galvanizing. The castings may be and usually are perfectly normal before the hot-dip treatment, in that they will stand a remarkable amount of distortion and punishment before fracturing, yet, after galvanizing, a single blow with a hammer will often cause a break. One such casting broke when accidentally dropped on a concrete floor. Such weakness causes galvanizers to view malleable cast iron with misgivings, and, in turn, is a source of worry to the manufacturer of the castings. It is felt, therefore, that a practical method of overcoming this embrittlement, a method that has already been used on several thousand tons of castings, will be of general interest. The purpose of this paper is to describe this immunizing process. DEVELOPMENT OF THE PROBLEM In the early days the trade was not much concerned with the finish of the castings and in most cases the only protection given to the parts placed in service was a coat of paint. It was soon found that this form of protection was inadequate and the user demanded a better type of rustproofing. In compliance with this demand, the use of zinc for coating gradually spread until it became general practice. More than half of all the zinc produced today is used for coating iron and steel, and, in spite of the recent use of cadmium and chromium, zinc coatings are still recognized as among the best general rust inhibitors for atmospheric exposure.

Jan 2, 1926

By J. A. Herbst, K. Rajamani

INTRODUCTION Recent research has shown that popu- lation balance models hold considerabl e promise as a basis for accurate mill scale-up from laboratory batch grinding tests. It has been shown that entire product size distributions from large ball mills can be predicted from data obtained in tests in small mills with errors of less than one or two percent. This level of accuracy has been demonstrated for batch grinding scale-up (Herbst and Fuerstenau, 1980; Austin, 1973; and Malghan and Fuerstenau, 1976) and for continuous grinding scale-up (Herbst, et a1., 1976; Herbst, Rajamani and Sanchez, 1982; and Herbst, Rajamani and Lo, 1982) in commercial mills up to 14.5 x 32 feet. A procedure which has been proposed for commercial mill design using the population balance approach and specific power information is shown in Figure 1 (Herbst and Fuerstenau, 1980). Here batch grinding data (size distributions for various energy inputs) obtained in a small batch mill is input to an estimation program which determines the "best" set of breakage rate parameters from the data provided. In turn, these breakage rate parameters are input to a scale-up program along with traditional inputs such as: a) desired circuit throughput and product size b) circuit operating conditions including fraction of critical speed and fractional ball load, size distribution and % solids in feed and circulating load (if closed circuit). In addition, since the population balance approach relies on more detailed models of the grinding circuit sub- processes than the classical design methods do, it is necessary to provide input to the scale-up program on the nature of material transport through the mill (e.g. residence time distribution information) and classifier performance characteristics (e .g. selectivity functions). The scale-up program will make the design calculations including the selection of mill dimensions and drive requirements, will predict product size distributions throughout the commercial circuit and will provide information on the sensitivity of the design to errors in the design assumptions. In order to implement such a scale- up scheme it is necessary to have a computer program for parameter estimation and a program for scale-up prediction. A program which is suitable for parameter estimation, ESTIMILL, has been developed and tested on a wide variety of ores at the University of Utah. This program has been in use in

Jan 1, 1982

By Meng-Cherng Sun, Fun-Den Wang, David M. Ropchan

A proposed technique for improving coal-mine roof stability by softening parts of coal pillars along the sides of entries developed from structural analysis is presented. This technique is based on the transference of the high stress concentration in the roof near the upper corners of a rectangular opening to the roof rock and coal over the solid away from the opening. This transferral is accomplished by softening parts of the coal pillars by drilling a series of parallel holes into the coal in the ribs and face of the entry prior to advance. The effectiveness of the pillar softening in terms of reducing the opening width (so that the stress in the roof near the corner is equivalent to that of a narrower opening) ranges from 3 to 5 ft for a 16-ft entry using a series of 4 to 5-ft-deep parallel drill holes of 3 to 6-in.-diam on a 1 to 2-ft spacing for a particular geology. Pillar softening should be highly effective in controlling roof where cutter-roof cave conditions exist, because this technique reduces the high stress concentration in the roof at the upper corners of the opening. It may also be effective for reducing tensile roof failure and coal rib sloughing for certain specific geological conditions. This technique appears to be a simple, effective, and practical method that can be used to supplement conventional roof support methods of roof bolting, timbering, roof truss, and other existing methods in underground coal mines. The authors consider the technique feasible and believe that it merits underground trials.

Jan 1, 1975

By A. E. Worthington, R. F. Meldau

An analog computer study was made of the reduction of the magnitude of the SP by formation geometry and resistivity effects. Practical field .situations were studied. The analog data were converted to the form of departure charts. These charts may he used to determine the reduction in the SP due to the above eflects pith good precision Quantitative interpretation of the SP log in terms of formation water resistivity is presently based on the premise that the observed SP is equal to the electrochemical potential developed across a shale between the mud filtrate and the formation water. This procedure inherently assumes that, first, no electro kinetic (streaming) potential is present, and, second, that the SP is not reduced by resistivity or geometry effects in the formation. When, however, such a reduction of the observed SP does occur, one may write, SP = b,E, b, E, (1) where SP is the observed self-potential opposite the center of the bed under consideration. In this case, E, is the electrochemical potential, E, is the electrokinetic potential, b, is the electrochemical reduction factor, and h, is the electrokinetic reduction factor. The first assumption above is equivalent to assuming E, = O in Eq. 1 and the second assumption is equivalent to h, = b, = 1. Examination of electric logs shows that for many formations of interest the observed SP is reduced below its maximum value. The object of this work is to aid quantitative SP interpretation in at least some of these situations by obtaining values for b, and b, in Eq. 1 as functions of realistic combinations of bed thickness, depth of invasion, and formation resistivity. The only previously published work in this field known to the authors is by H. G. Doll' in 1948. He evaluated b, under conditions permitting exact analytical solution. His work clearly established the importance and qualitative nature of formation geometry and resistivity effects upon the SP, but the necessity of obtaining analytical solutions restricted his study to situations of limited practical interest. In order to extend such studies to practical combinations of formation parameters which do not lend themselves to feasible analytical solutions, the results reported in this paper were obtained by use of a special analog computer. THE ANALOG MODEL The analog model used for this study was the Guyed Analog Computer which originally was designed and built for resistivity log departure curve studies. It consists of a two-dimensional mesh of resistors, with the vertical mesh corresponding linearly to vertical distance along the borehole, and the horizontal mesh corresponding to radial distance from the borehole axis. By proper choice of horizontal resistor values, a three-dimensional, axially symmetric, borehole-formation problem can be modeled with this two-dimensional array. These and other details of the model are contained in a paper by H. Guyod'. The geometry used for the SP studies with the analog is depicted in Fig. 1. This configuration has a horizontal plane of symmetry, and, hence, the model, and the following discussion, need only to be concerned with one quadrant such as shown in Fig. 2. A further simplification arises by considering that both the natural potential sources and those used in the model have fixed internal impedance. Therefore, the current flows produced by these sources can be separated and studied independently ( i.e., the superposition theorem can be applied). SP = SP, i SP, = h,E, + b,E, ,(7)

By T. S. Lundy, F. R. Winslow

DIFFUSION coefficients of Hf181 in the high-tem-perature bcc phase of reactor-grade hafnium were determined at temperatures of 1795° to 1995°C by standard lathe-sectioning techniques. The temperature dependence of the data may be described by an Arrhenius-type expression for this limited temperature interval. However, hafnium is classed with the "anomalous" bcc metals zirconium, titanium, and y uranium by the low values of Do and Q observed in this study. The hafnium metal was received as 1/2-in.-diameter crystal bar. Analyses by the Analytical Chemistry Division of Oak Ridge National Laboratory showed the major impurity to be zirconium— about 2.1 pct. The total interstitial content was about 225 ppm with 190 ppm of this oxygen. The Hf"' was supplied as HfC12 in HC1 solution by the Isotopes Division of Oak Ridge National Laboratory. The hafnium bar was cut into disk-shaped specimens 3/8 in. long. One of the flat faces of each specimen was metallographically treated and then the isotope was deposited by vacuum evaporation from a tungsten filament. A 3 by 3 in. NaI (Tl) crystal with a single-channel analyzer was used for counting y rays with energies of 0.3 to 0.7 Mev. The as-deposited layers of isotope had counting rates of about 200 counts per sec. Specimens were annealed in argon in a tantalum resistance furnace. Temperatures were measured with a microoptical pyrometer calibrated for the particular furnace sighting conditions. All sectioning was done by standard lathe techniques. Section weights were determined on a semimicrobalance. A density of 12.5 g per cu cm was used in determinations of section thicknesses. Activities associated with the various sections were measured and the penetration data were treated using the computer code by winslow.' In all cases, except for specimens annealed at temperatures below 1795°C, normal Gaussian penetration behavior resulted. At lower temperatures, plots of In A(x) vs x2 were nonlinear [~(x) = relative activity at a distance x from the

Jan 1, 1965

By Vytas Svalbonas

Sophisticated computer analysis methods such as finite elements, finite differences, and numerical integration have become tools in the mineral processing industry for design of large mill shells. While use of such methods allows the analyst-designer to take new freedom with his designed structure, there are also pitfalls and dangers which must be recognized for the proper use of such sophisticated tools. One of the worst of these is treating any computer answers as "gospel truth." The present paper discusses the knowledge required by the analyst-designer for proper use of computer analysis, as well as explaining to the layman how to identify questionable areas in such structural analyses.

Jan 1, 1980

By E. T. Dumbles

Prof. Edward Orton, in his Report on the Occurrence of Petroleum, Natural Gas and Asphalt Rock in Western Kentucky, thus clearly states his ideas of the universal dissemination and rare accumulations of the bitumens:I "We need to bear in mind that the various members 'of the bituminous series are abundantly and almost universally distributed among the unaltered sedimentary rocks of the earth's crust. The valuable accumulations of these substances are rare, it is true, but one can scarcely go amiss' of petroleum, asphalt or gas, at least in small quantities, among the stratified rocks that retain their original structure." Speaking of the Ohio valley, he adds: "A fifth of one per cent. of petroleum, if distributed through a thousand feet of rock, would make a total to the acre, or square mile far beyond any production that has ever been realized from the richest oil field, and -percentages of this amount are not only not rare to find, but are even hard to miss." Dr. F. W Clarke in his Data of Geochemistry (Bulletin No. 491, U. S. Geological Survey, 1911), discussing these views of Orton with similar views of T. Sterry Hunt and Szajnocha, says that they "lead to the conviction that the formation of bitumens is a general process and by no means exceptional. Wherever sediments are laid down, inclosing either animal or vegetable matter, there bitumens may be produced." The organic origin of the bitumens, including petroleum, Gas long been an accepted fact with nearly all geologists, but the method, place, and time of the transformation into petroleum or other bitumen is still under 'discussion. Dr. Orton says? "The statements now presented........bring before us two main views as to the origin of petroleum, viz.: " (1) Petroleum is produced by the primary decomposition of organic

Jan 1, 1915

By W. B. Lilienthal

A considerable saving in time and money has been effected by use of a specially designed stainless steel container for laboratory drilling mud test work. This container involves use of a standard tall-form stainless steel beaker for service in which the mud sample is heated to an elevated temperature and maintained there for protracted periods of time, while undergoing agitation to facilitate mixing of mud components. Agitation is accomplished by rotating the filled containers on motor-driven rollers within an oven. Several porcelain balls are generally placed in the containers to further improve agitation. Soft glass containers (.Mason jars) were used in this service in early work, and were found to be unsuitable for the following reasons: 1. Poor resistance to thermal shock. 2. Containers could withstand only relatively low pressures. 3. Accidental breakage in handling. 4. Chemical deterioration and subsequent mud contamination from reaction of high pH muds with the glass at elevated temperatures. Pyrex containers were also considered, but, inasmuch as they provided improvement only in items 1 and 4 listed above the additional cost was not believed to be justified. A scale drawing of the container is shown in the figure illustrating details in cross-section. A pressed stainless steel lid was fabricated to match the rolled edge of the beaker

Jan 1, 1950

By H. R. Barnhurst

IT would be a difficult matter to trace from the beginning the very few improvements made in the burning of fuels prior to 1860. Doubtless the crossing of the sticks of wood in building a, wood fire early appealed to our savage ancestry as a means of expediting its effectiveness for their crude culinary purposes. Stones and andirons came later in assisting the admission of air to the under part of the fuel bed, while beacons and cressets utilized metal bars as supports for the same purpose. It is probable that Tubal Cain owed his success to the use of bellows making possible the use of mixed fuel and charge upon a hearth. With the development of working in east iron, grate bars cane in, and they are still with us doing duty in every household and almost every art where heat is a factor. Little was done beyond these crude methods prior to 1860. With the advancement of knowledge came the fuel-gas producer, a. natural child of the retorts employed in supplying illuminating gas. It is only within the last 15 years that the conclusion became general that complicated systems for saving heat would not remedy deficiencies in its primary development, and within that tine there has been great advancement in the means of producing initially fire of high efficiency, so that to clay we are moving rapidly toward loth high development and high absorption, with the resultant of high efficiencies. In studying the subject of the availability of pulverized coal as a fuel, it may occur to ask, why has this not come up earlier? This question would be naturally prompted by recalling the fact that Thomas Crompton's English patents upon his methods were issued to Min nearly 40 years ago. A conclusive answer to this, however, is that Crompton at that time had very crude facilities for raking what was at best a, very imperfect pulverization of the coal, and the expense of preparation was very great. He does not seem to have been aware of the advantage of a thorough drying of the coal in the

Jan 10, 1913