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By M. R. J. Wyllie

Eight laboratory-prepared aqueous base drilling muds representing common mud types, and 15 aqueous base drilling muds sampled in the field, have been used in an experimental investigation of the relationship between the streaming potential developed across a mud filter cake and the differential pressure causing filtrate flow. It has been established that the relationship is of the form, ES = kPy, where Es is the streaming potential, P the differential pressure and k and y are constants for any particular mud system at constant temperature. Beyond a certain minimum thickness this relationship is independent of filter cake thickness. Experiment has shown that both k and y are temperature dependent parameters and that in certain mud systems there is a critical value of P above which the simple relationship Es = kPY ceases to hold. The constant k tends to be a function of the mud resistivity at 77ºF, but the exponent y has not been found to be related to any commonly measured mud property. Certain field experiments are described which serve to demonstrate that the total SP (self potential) developed opposite a formation may be quantitatively accounted for as the algebraic sum of an electrochemical potential and an electrokinetic potential. A chart to permit the simple use of mean solution activities in the interpretation of electrochemical SP data is given and its use described. Various field methods for computing the electrokinetic SP component of the total SP are considered and rejected as being unduly complicated and inaccurate. It is shown that the employment of low resistivity drilling muds is essential if optimum accuracy is desired in the use of the S.P. curve for the purpose of computing connate water salinities by the electrochemical SP method. The use of such low resistivity drilling muds is accordingly recommended. INTRODUCTION In a previous paper' a quantitative analysis of the electrochemical compovent of the SP (self potential) curve was made and it was shown that the electrochemical* emf, E, could be expressed as E = ZtRT/F In a,/a,, where t is the transference number of the chloride ion, R is the gas constant, T the absolute temperature of the formation water and mud, a, the mean activity of the connate water (assumed to be sodium chloride) and a, the mean activity of the mud (as sodium chloride). The essential accuracy of this expression was confirmed by an investigation 2 of the SP kicks opposite sands of known water salinity. The logs examined had been routine runs in oil wells in a number of Mid-Continent states. Further confirmation of the original analysis of the electrochemical SP is implicit in the paper by Tixier3 wherein a relationship between the SP and the ratio of connate water and mud resistivities, based only on field data, is given. Allowing for the fact that mud and connate water resistivities were used instead of activities, and that electrokinetic effects were ignored, the constant reported by Tixier is essentially 2tRT/F. The error involved in the universal substitution of resistivities for activities will receive further reference below. Possible reasons for the fact that the electrochemical properties of shales do not appear to be significantly dependent upon either the nature or the quantity of cation exchange materials, such as clays, they contain has been considered at some length by Wyllie and Patnode.4 In the same paper, the probable effects of shale thickness and compaction on electrochemical efficiency, and hence the inherent difficulty of obtaining reliable laboratory-scale data, were also pointed out. However, it is

Jan 1, 1951

By P. R. Sperry, M. L. Holzworth, P. A. Beck

The basic work of Z. Jeffries 1,2,3 has long ago established the main features of grain growth in the presence of a dispersed second phase. Working with sintered specimens of initially fine grained tungsten, to which various amounts of thoria had been added, Jeffries found that grain growth was inhibited, that is, practically prevented, up to a certain annealing temperature. When this temperature, which increased with the thoria content, was exceeded, extremely large grains developed abruptly from the fine grained matrix. such a a temperature" was later found by Gross-mann~3,14 in certain types of steel, while ~~i~ showed15 that in other steels grain growth was gradual, without inhibition and abrupt coarsening. Later work demonstrated the connection between coarsening and aluminum additions. The viewpoint that the direct cause of inhibition and coarsening in aluminum killed steels is a fine dispersion of aluminum oxide21 appears to be held quite generally, although some doubts have been voiced even very recently, 20 In steels with Ti additions the titanium carbide phase is considered responsible for the inhibition effects found.20 The coarsening temperature increases with the titanium content. That coarsening may occur, as a result of, certain heat treatments, even in low carboil rimmed sheet steel, was shown by Samuels. He also detected coarsening in a steel ingot of similar composition, after giving it the same heat treatment as that used by him for the sheet material. In this instance the identity of the inhibiting phase has not been determined. However, Tangerding found23 that even the few small carbide particles, which occur in carbonyl iron, have a very marked inhibitive effect. As a result of an oxidizing anneal at 850°C, large grains begin to form at the surface of the carbonyl iron specimen, and gradually grow inward as the subsurface oxidation of the carbide particles progresses and eliminates the obstruction. The carbide particles Can be removed also by annealing in hydrogen, with similar results. But if the oxidizing anneal of 10 hr at 850°C in air is followed between in hydrogen for 75 hr at the Same temperature, grain growth is more hibition usually the whole specimen is transformed into a single crystal (approx. 1.5 cm X 5 cm). The reversed procedure, that is, hydrogen annealing followed by oxidizing annealing leads to smaller grains. Tangerding arrived at the logical conclusion that there must have been in his specimens some additional obstruction to grain growth hibition from a minor impurity, other than carbon. It seems likely that this obstruction was caused by an oxide formed during the oxidizing anneal and gradually reduced rtain the subsequent hydrogen-annealing. Other instances of grain growth inhibition of varying severity, associated with a dispersed second phase, have been described by several authors. Notable examples: lead with 0.06 pet Cu or Ni,24 cartridge brass with 0.12 pct Cr,25 or with up to 0.15

Jan 1, 1949

By A. R. Hendrickson, C. F. Smith

Hydrofluoric-hydrochloric acid mixtures have been successfully used to stimulate sandstone reservoirs for a number of years. Hydrofluoric acid (HF) has a specific reactivity with silica which makes it more effective than HCl for use in sandstone. Kinetics of the reactions of HF have been studied to determine the related effects of reservoir composition, temperature, acid concentration and pressure on the spending rate of HF. Secondary effects from by-product formation are noted and described. Predictions are made concerning the improvement in productivity resulting from HF treatment of skin damage. The kinetic order of HF reaction in sandstone was experimentally determined to be first order, i.e., the reaction rate is proportional to concentration. HF reacts faster on calcite than on clay, which, in turn, is faster than the reaction rate of HF on sand. Static conditions retard the HF reaction rate. As HF is forced into cores, there is a temporary reduction as a function of flow rate and acid concentration. Extensive deposition of calcium fluoride in acidized cores was not observed. Although some CaF, was defected, it was not considered a major source of damage in cores containing moderate amounts of carbonate. Other fluosilicates could be potentially more dangerous than CaF, in reducing permeabiliry. INTRODUCTION Hydrofluoric acid has been widely used in stimulation treatments since 1935, when mud acid was introduced to the petroleum industry. Originally, this hydrochloric-hydrofluoric acid mixture was intended to remove mud filter cake, but it has since been successfully applied to many other oilfield problems. Mud acid treatments have been unusually successful in sandstone reservoirs where hydrochloric acid is unreactive due to a lack of enough calcite in the formation. The relatively small amount of hydrofluoric acid present (2.1 per cent) reacts with sand grains, clays and traces of calcite which are generally present in sandstone reservoirs. Since hydrofluoric acid (HF) is the key to mud acid success, this research effort has been dedicated to gaining a more thorough understanding of the basic chemical and physical principles involved as HF reacts. Hydrofluoric acid's reactivity with silica makes it unique in application. Other mineral acids such as hydrochloric, sulfuric or nitric are unreactive with most silicious materials which comprise sandstone formations. A typical sandstone reservoir may contain 50 to 85 per cent silicon dioxide, more commonly called sand or quartz. Hydrofluoric acid reacts as follows: 4HF + SiO2 + SiFO + 2H2O The silicon tetrafluoride (SiF,) is a soluble gas, in some ways similar to CO2, and is capable of undergoing further reaction when held in solution by pressure. These reactions will be considered in detail later. Kinetics of the reactions of HF have been studied to determine the effect of reservoir composition, temperature and pressure on the spending of the acid. Secondary effects from by-product formation have been noted and described. The individual reactions of HF on quartz, glass and clay are reported. Mathematical correlations have been drawn, then applied to studies of HF spending in cores obtained from actual producing sandstone formations. The research reported herein is only the beginning of a continuing approach to better understanding and use of HF in petroleum reservoirs. THEORY AND DEFINITIONS Through the years, a concentrated effort has been made to understand the effects of many variables on hydrochloric acid (HCI) spending in limestone. Hendrickson el al., have given mathematical relationships for HC1 reactions which made possible the engineered approach to acidizing. The same variables—temperature, acid concentration, formation composition, pressure and permeability-porosity relationships—which affect HC1 behavior in limestone also govern HF behavior in sandstone. Insoluble by-products of HF reaction have been isolated and identified. Their effect on fluid flow has been measured under varying conditions in an attempt to evaluate the extent of possible damage and means of eliminating it. In general, HF follows the same reaction paths as HCI. It will react with limestone and dolomite with speed and ease. Thin sections of acidized cores show the reaction of HF with limestone or calcite faster than its reaction with either clay or sand. When HF reacts with calcite (CaCO,), theoretically, calcium fluoride (CaF2) is precipitated, and has been blamed as a major cause of reduced permeability. On the other hand, pH and pressure such as that encountered in an underground formation under acid treatment definitely retard CaF2 formation,' so the whole question of CaF, deposition in wells is a subject for study.

Jan 1, 1966

By Ira B. Jorafemon

In the interesting Institute symposium of the preservation of peace by force, through mineral control, one important aspect of the question was not presented. This is the responsibility the United Nations, and particularly the United States, will incur the through limitation of the economic activities of nations that are now friendly to us, as well as of nations that are enemies or are under the control of enemies. After the war all nations, friends as well as enemies will be poor. Hunger and bankruptcy will, will like the sword of Damocles, hang over the heads of all of us on this blundering planet. When the actual fighting is over, there will be a universal attempt to squirm out from under the sword by resuming production of peacetime goods, for trade as well as immediate consumption.

Jan 1, 1944

By E. H. Lee, F. J. Fayers

Problems in reservoir analysis can usually he cupressed in terms of a system of nonlinear partial difjerential equations. A rnethod for .setting physically reasonable boundary conditions for these systerrls by ayplication of the theory of characteristics is discussed. A short description i.c. given of the technique for finding chnmcteristics of general first order and second orrler equations. Specific examples are quoted jrorn eqrrations occurring in theoretical reservoir studies. The princip1e. ossocicred wit11 the use of chnracteristic to set physically realistic boundary conditions me developed, and thr method is discussed in terms of boundary condition for the noncupillary, compressible, two-phase flow problen: jor the cupillary, ir~cowlpressible, two-phase flow problems for the tlrtergent flooding prohlenl; as for the compressible. noncapillary, two-phase flow pro11letn. INTRODUCTION In most problcms in reservoir analysis the physical situation is described by a system of nonlinear partial differential equations. The general solution to the set of equations usually comprises a wide range of functions ancl a particular solution is normally selectetl by applying suitable boundary conditions to the problem. In some cases it is clear from the physical situation what form the boundary conditions should take, but it is usually desirable to have an independent mathematical check of the suitability of the chosen conditions. From the mathematical standpoint, a system of partial differential equations with boundary conditions is said to be properly set if the combination determines a unique solution which is continuously dependent on the equation and the boundary conditions. Such a solution is sometimes termed "reasonable". In investigating the properties of the mathematical representation, it is useful to determine the structure of the system by the application of the theory of characteristics. This theory determines in the space of the independent variables, lines or surfaces which play a special role in thc system's behavior. The characteristics determine the possibility and nature of the propagation of discontinuities in the derivatives of the dependent variables. Along the characteristics certain differential relations hold which for some problems allow a so- lution to be obtained analytically. In the case of hyperbolic equations the characteristics can bc used as 3 basis for a numerical solution. If a complicated nonlinear system is to be solved, a study of behavior of the characteristics will indicate what boundary conditions should be chosen. By using the method of characteristics, several advances have rccently been made in solving reservoir engineering problems. Sheldon, Zondek and Cardwell' have discussed how the the method may be used grap-phically to solve the incompressible two-phase displaccmerit problem when the gravity term is included in the equations. Fayers and Perrine' have applied the method to study the equations representing detergent flooding. When compressibility and solution-gas effects are introduced into the two-phase flow problem, the equations and their characteristics become more complicated. It will be seen that in this problem the characteristics are useful for indicating a reasonable set of boundary conditions but cannot readily be used to compute a numerical solution. This problem has been solved on the IBM 701 using normal finite difference methods hy West, Garvin and Sheldon." The material to be prcscntcd in this report is divided into three sections. The first discusses the determination of the characteristics of first and second order partial differential equations; the second describes the selection of suitable boundary conditions by the application of the principle that the future cannot affect the past; the third discusses the use of characteristics for setting the boundary conditions of the two-phase solution-gas flow problem. A useful introduction to the method of characteristics has been given by Hildebrand.' A summary of the method will be given in this section of the paper. The First Order Equation The quasi-linear equation of first order is It is linear in the partial derivations of z. The properly linear equation has the form The characteristics of are curves along which the

By J. B. Austin

In considering so complex a process as the smelting of iron in the blast furnace, there is obviously no single method of calculating efficiency that gives a complete appraisal of the performance of the furnace in all its several functions; such a comprehensive view as is required to evaluate producing ability and manufacturing costs for a given furnace is obtained only by considering a group of efficiencies, each of which measures the performance of the furnace from a specific point of view. For instance, there is the rate of consumption of coke per ton of iron produced, which is probably the most frequently considered, and is certainly one of the most important of the group; there is the efficiency of recovery of iron charged; and there is the efficiency of utilization of energy, both chemical and thermal, in some respects related to the former two yet in other ways independent of either. In each of these cases, the calculation can be made on the basis of the actual input of material or energy, or it may be based upon a comparison with the minimum amount of material or energy that would be required by a "perfect" furnace; that is, an imaginary ideal furnace analogous to the perfect steam engine used in thermodynamic calculations, when this furnace is operating under optimum conditions. Moreover, the furnace itself can be considered either as an apparatus for smelting iron or, taking a somewhat less common point of view, as a gas producer yielding iron and slag as by-products. Some of these efficiencies are more useful than others, yet all are instructive; for a knowledge of them not only leads to good engineering practice from the standpoint of control but also discloses limits to possible improvement in performance and indicates the lines along which improvement is most likely to be profitable. Estimates of some of these efficiencies have appeared from time to time in the literature, but many of them are open to objection because they are based on data of uncertain accuracy or because they have been calculated without due regard to the thermodynamic principles involved. Moreover, so far as the author is aware, no general survey of the blast furnace comparing its performance in all the aspects mentioned has been made.

Jan 1, 1938

By J. W. Goss, M. J. Coolbaugh

Most grouting has been done to stop water flaw in mines and for stabilizing foundations of various man-made structures, a survey of the U.S. literature reveals. Apparently Sun Manuel is one of the first mines in this country to use grout extensively underground for strengthening and stabilizing ground in drifts, shafts, and stations. A comparison with other procedures as well as details of the Sun Manuel program are covered. The employment of pressure grouting as a ground stabilizer at the San Manuel Copper Corp. mine reduces delays in both development and production, lowers costs, and makes possible safer working conditions. It specifically reduces delays in haulage operations and permits the maintenance of normal ventilation. In development work this grouting allows faster excavation by cementing together highly fractured or broken ground that otherwise would require extensive cribbing or spiling. In drift repair, it consolidates the loose or fractured rock over the timber or steel drift supports, thus decreasing the frequency of repair, lessening the hazards from falling rock, and curtailing delays due to blockage of drifts by muckpiles and repair operations. Pressure grouting is the process of pumping an accurately controlled mixture of cement and water into loose, fractured, or porous rock. The ratio of water to cement varies according to the nature of the rock encountered, from the thinnest mixture of 30 gal of water per sack of cement, used to fill very fine fissures, to very thick grout of 5 gal of water per sack of cement, used to fill large fissures or extensive areas of loose, broken rock. The pumping pressures at San Manuel vary from about 100 to 1000 psi, depending upon the compactness of the rock, while at other mines the pressures sometimes go as high as 5000 psi. In order to grout an area in which ground water is encountered, the pumping pressure of the grout must be increased by an amount equal to the pressure of the ground water. GROUTING IN DEVELOPMENT WORK The areas under development at San Manuel include many sections of loose, highly fractured rock. Prior to the advent of the grouting program, drifts, shafts, and stations in these areas could not be excavated without utilizing extensive support such as cribbing, spiling, and breast boarding. This slowed down the development work and increased the costs considerably over that required for excavating in more competent ground. Now, when a particularly bad area is contacted, the mining is temporarily stopped while the bad portion of drift or shaft is grouted. After the grouting is completed, the excavating is resumed with an approximate decrease of 50 pct in lost time and costs. Grouting in Drifts and Turnouts: The grouting procedures and patterns used in drifts and turnouts are very similar. The standard procedure for grouting such a turnout is shown in Fig. 1. After the ground is supported as well as possible with cribbing or lagging, the gaps between the back lagging and side lagging are plugged with empty cement sacks or additional timber, if necessary. The ground surrounding the proposed turnout is then grouted in two stages. In the first stage, the broken and caved rock is drilled and grouted to a depth of 5 to 10 ft, depending on the depth of the broken rock. This stage forms a grouted seal that allows higher pressures to be used at depths beyond 10 ft without developing excessive leaks at the face. After a grout hole is drilled, a 10-ft long pipe is wedged tightly into it with empty cement sacks. Grout is then pumped into the hole until the pressure reaches 200 to 300 psi, and the pipe is subsequently removed if it hasn't become cemented in. No more than one hole at a time is drilled and grouted because the grout has a tendency to go from one hole into another, plugging up the latter. Five or six holes are usually adequate for the first 10 ft of grouting. Experience has shown bentonite to be a useful admixture to the grout, particularly when it is indicated that the grout is being lost into large fissures or voids. Bentonite increases the plasticity of the grout enabling it to remain in place more easily until it has begun to set. In the second stage, the longer holes are drilled through the previously grouted rock, after which the

Jan 1, 1961

A filled stope is one in which the support for walls and men and, at times, for the back of ore, is furnished by waste rock or sand tailings. The filling may be rock sorted out in the stope or from the walls, develop-ent, or the surface. The orebody is mined in sections, each practically an open or timbered stope, filled wholly or in part before adjacent ground is attacked. As a rule, the filled-stope method is limited to overhand flat-back, stepped-face, or rill stopes. The examples given are Copper Range, Iron Cap, Verde district, Zaruma district, Lucky Tiger, and Silver King Coalition.

Jan 1, 1925

By Norman P. Goss

What would appear to be a very simple process on paper has proved to be overrun with a multitude of unseen difficulties. For more than 70 years attempts have been made to cast metals in a continuous manner, but it has been only within the last Io years that some degree of success has been achieved.1 Historical Development Bessemer's Experiments—Method I Bessemer was the first to try to cast molten metal in a continuous manner. His method is fully described in U. S. Patent No. 49053, issued in 1865. The patent drawing is shown in Fig. I. In this method the molten metal was poured between a pair of rolls of large diameter, which were cooled by water sprays. Means were provided to prevent moisture from coming into direct coptact with the molten metal. The width of the strip was controlled by the flanges. On paper this should work to perfection, but it is beset with many difficulties still awaiting solution. Bessemer failed to reduce his invention to commercial practice. About 1890 Bessemer's method was revived by Norton and associates (U. S. Patent No. 441375). They formed the Fluid Metal Rolling Co. at Maywood, Ill., and spent $250,000 in endeavoring to develop the technique for this simple method. Finally they had to abandon it. Naturally, they did carry the technical development far beyond anything Bessemer had done, but even so it was far from being a useful commercial success. In recent years it has undergone further development by C. W. Hazelett (U. S. Patent No. 2058447), who has succeeded in obtaining long lengths of copper, brass, aluminum, and even stainless steel. He introduced many' ingenious devices but the greatest obstacle still remained—the disintegration of the roll surface when the surface is heated and chilled in rapid succession. Difficulty is also experienced in maintaining a uniform supply of molten metal to the rolls. The patents pertaining to this method would indicate these to be the major obstacles. Experimental work by Mellen—Method 2 A departure from the method introduced by Bessemer, was tried by Grenville Mellen, of East Orange, K. J., sometime between 1914 and 1920, who obtained a number of patents.2 His method is illustrated in Fig. 2. This method failed to make an impression upon the art; however, it is of value in pointing out the difficulties the inventor ran into and the way in which he tried to meet them. The split mold sections form two endless chains. When going through the center of the apparatus, these sections engage each other to form a complete mold. As the engaged mold section moves downward at a constant speed, molten metal is teemed into it. As this is going on, another set of cooperating mold sections move into position on top of the one being filled. The molten metal is teemed into the mold through a silica tube. According to the teachings of this patent, the level of molten

Jan 1, 1945

By S. Nakajima, H. Okazaki

Quantitatiue studies of the deformation texture in drawn tungsten wives were made by the X-vay dif-fractottletetr. Experimental results show that the diffraction Intensities are equal to tilose pvedicted from the (1 10). fiber lexlure but the angxla), spreads of. diffraction peaks in the pole distribution curres are different for different diffraction planes and directions. For this reason a modified (110) fiber lextuve model, in which a kind of anisotropy is assumed, is proposed to explain the results. According to this model the poles lying on a line directing front the (110) to the (110) poles in the (1 10) standard stereograpllic projection should show spreads which are different from those lyitlg on a line directing from the (001) to the (001) poles, which is confirmed by the experiments. The anisolvopy and the spveads of the pole positions are large at the outer part of the wires and decrease gradually lowards the inside of the wire. The possibilily of occurrence of such anisolropy in irrelals with fcc stvuctures is discltssed. THE deformation texture of drawn tungsten wires has been assumed by different investigators to be the simple ( 110) fiber texture.' Recently, however, Leber2,3 has shown that a swaged tungsten rod has a cylindrical texture. It changes gradually to the (110) fiber texture by drawing through dies. However, even after drawing to 0.25 mm in diam, the cylindrical texture can still be found in wires together with the (110) fiber texture. This was deduced from the pole figures obtained from the longitudinal section of these wires. Use was made also of quantitative measurements of the pole distribution curves. Leber stated that the angular spread of the pole distribution curves (henceforward called dispersions) are quite different for (400) 45 deg and (400) 90 deg: the former is always larger than the latter. This inequality is accompanied by deviations of the diffraction intensities from the theoretical values for the ( 110) fiber texture. Bhandary and cullity4 have reported similar results on iron wire and explained them by assuming a cylindrical texture. Both Leber3 and Bhandary4 used only the results of the (400) reflection for the determination of the dispersion. The pole figures found by Leber3 and by Rieck5 are largely different. The model given by Leber to explain the effects is in the authors' opinion in some respects unsatisfactory, especially if one looks at other than the (400) reflections. Intensities and dispersions of diffraction peaks are conclusive factors for the determination of the fine structure in wire textures. For this reason we studied them extensively to come to a model which is more suitable to fit the facts. In the following, after giving the experimental set-up, we report about measurements of X-ray diffraction on drawn tungsten wires. Different models to describe the experimental results will be discussed. EXPERIMENTAL GO-SiO2-A12O3 doped tungsten wires drawn to 0.18 mm in diam were used for the measurements. The wires were chemically etched to various diameters down to 0.03 mm. Measurements were carried out for the different wires in order to determine the dependence of the texture on the radius. The wires were cut to pieces of 10 mm length and fixed with paste closely against each other on a flat, polished glass plate. Parallelism of the wires with the surface of the glass plate should be adequate. For the diffraction studies three different X-ray sources were applied, respectively, giving the CuK,, FeK,, and FeKp emission. The measurements were carried out with a diffrac-tometer with a GM counter. The latter was fixed to a certain diffraction angle 20hkl and the diffraction intensity was recorded as a function of the angle of rotation of the specimen around the axis, lying in the specimen surface and perpendicular to the wire axis, as shown in Fig. 1. Measurements were also done with the detector at angles slightly deviating from the diffraction maxima The measured intensities in this case were taken to be equal to the background level. The deviations were chosen as small as possible but large enough to eliminate the influence of the diffraction maxima. The useful range of the rotation angle x of the specimen is generally limited by the wavelength of the X-rays. We have: where and cp is the angle between the wire axis and the normal of the diffraction plane. Intensity measurements were made to find the necessary corrections for counting loss of the GM counter and for distortion resulting from such effects as absorption of X-rays and from inclination of the reflection plane under study with respect to the surface of the specimen. The counting loss was esti-

Jan 1, 1968

By T. L. Joseph

THE extent to which hot metal from the blast furnace affects open-hearth practice and the quality of steel produced has been discussed widely. Open-hearth operators have attributed difficulties experienced in making satisfactory steel to characteristics of the pig iron not disclosed by ordinary analysis. The commonest criticism of the iron has been that it is "physically cold" or "dirty." Often when the blast furnaces are working irregularly the quality of the iron is questioned. A cold hearth, slipping and hanging, the use in the past of unsintered flue dust, and the use of ores difficult to smelt have been associated with the production of iron of poor quality. The difficulty of the situation is that we have no proven yardstick for quality aside from ordinary analysis. Uniformity in analysis is recognized as being important, but the difficulty of changing the open-hearth practice when the iron analysis varies widely may not always be fully appreciated. Although the problem of correlating the characteris-tics of steel with those of pig iron is admittedly obscure, the effort of producers of quality steel to investigate all factors that may have a bear-ing on the final product is justified. This report contains data on the oxides in several hundred casts of basic iron produced in a furnace during the course of normal operation on Lake ores. Incidental to the study of the oxides in the iron, it was desir-able to follow closely the temperature of the iron. The effect of tempera-ture of the iron upon the silicon and sulphur present is discussed. A general relation between the basicity of the slag and the sulphur in the metal was developed. The amount and composition of oxides in the hot metal and in the steel bath during various intervals between melt-down and tap are discussed. Heats of rimmed steel, lulled steel, and semikilled steel were investigated. The hot metal on individual heats was either all taken from a mixer or consisted partly of direct metal and partly of

Jan 1, 1937

By John E. Hockett

The need for basic information about the relationship between resistance to dejormatim (flow stress), temperature, strain, and strain rate, for the solution of metal-fovming problems, is pointed out. Some early attempts to satisfy the need are mentioned. A brief description of a machine called a Cam Plastome-ter is given, including the processing of results of testing in the machine. Next, a program of testing aluminum in compression over a wide range of constant true-strain rates (0.1 to > 200 sec-1) and a modevately broad range of temperatures (223° to 673°K) is described. The results of this program are presented in the form of true-stress us true-strain cuvves. The data in these curves are presented in the form of relationships between true stress and true-strain rate in sermilogarithmic and log-log form, as functions of temperatures—for several true strains. Finally, true stress, for a given true strain, is displayed as a function of log true-strain rate and absolute temperature, i.e., a surface. SINCE the publication of Hill's book1 on plasticity theory, increasingly rapid advances have been made in analytical solutions to forming problems. Methods in common use are the slab method, the uniform deformation energy method, the limit analysis method, the slipline field method, and the semiexperimental method called "visioplasticity". These approaches, and examples of their use, are covered in detail by Johnson and Melloor2 and by Thornsen, Yang, and Kobayashi.3 unfortunately, practically all of the above work has had to rely upon a number of basic assumptions, e.g., homogeneous deformation and Coulomb (sliding) friction; and virtually no dependence of the mechanical behavior of the deforming metal, upon temperature, strain, and strain rate, has been included. It is with this dependency that this paper is concerned. Loizou and sims4 looked at the above relationship for lead using both a constant compression-speed Cam Plastometer and a constant true-strain-rate Cam Plastometer designed by Orowan.5 Alder and Phillips8 investigated the relationships for aluminum, copper, and steel in the same constant true-strain-rate Plastometer. cook7 tested twelve steels at temperatures ranging from 1170° to 1473°K in the same Plastometer over a range of true-strain rates of 1.5 to 100 sec-'. The writer tested commercially pure aluminum at room temperature and depleted uranium at temperatures from 573" to 873°K at strain rates from 10-3 to 1.0 sec-1 in a Cam Plastometer designed and built at Los Alamos Scientific Laboratory.8 During the past few years the Cam Plastometer at Los Alamos has been used for a number of relatively minor experiments on brass, mild steel, duralumin, Armco iron, and depleted uranium. In this time the machine has been continually modified and improved. It was decided to utilize fully the wide range of strain rates now available with the machine by testing a material about which some information was already in the literature. Prior work on commercially pure aluminum6 appeared to deserve confirmation and expansion. So it was decided to explore the resistance to compression of this material over the currently available range of constant true-strain rates and a convenient range of temperatures. This paper is a report of that exploration. I) EQUIPMENT AND PROCEDURE The principal item of equipment is, of course, the Cam Plastometer, the working part of which is shown in Fig. 1. In this figure, an aluminum specimen may be seen between two tungsten carbide platens, in position for a room-temperature test. Above the upper carbide platen is a load cell. Output from the load cell is amplified and applied to a galvanometer in a recording oscillograph. Auxiliary equipment includes the oscillograph, the control console, a counter, and a time-mark generator. The counter is first used in adjusting the time base. Then it registers the count, of sixty pips per revolution generated by the rotating cam, in each second. These pips and the time base are also applied to galvanometers in the oscillograph. Thus, load, time, and cam position are recorded simultaneously. Heating of a specimen prior to compression is done

Jan 1, 1968

Readers of recent Bulletins have doubtless observed that the problem of improving both material and moral condition of employees is receiving close attention from influential members of the Institute. This will lend interest to certain developments and investigations that have been reported elsewhere.

Jan 5, 1918

By F. F. Peng, A. D. Walters, M. R. Geer, J. W. Leonard

INTRODUCTION Washability characteristics derived from float-and-sink analysis in Chapter 4 demonstrate that coal is intrinsically heterogeneous, and this heterogeneity is also evident in the proximate, ultimate, and size analyses. A range of particles from high to low specific gravity is usually seen in the run-of-mine coal. One objective of coal preparation is to recover the high quality float material (the particles of lower specific gravity) such that the recovered product meets certain quality specifications, as well as to reject or recycle low quality particles of higher specific gravity. The maximum recovery of cleaned coal at the required quality is of major concern to plant operators. However, the quantity and quality of products of coal cleaning, determined in the operation of actual commercial cleaning plants and by theoretical calculation based on run-of-mine washability studies, are known to be different with each coal. Therefore, during the last half century, coal preparation engineers have repeatedly sought methods to predict the technical and economical efficiency of separation of cleaning equipment and systems. Many formulas have been proposed by international investigators to evaluate the efficiency of various coal cleaning operations, primarily based on the yield and/or ash of the various products of coal cleaning. Performance criteria in use today are capable of defining all of the important aspects of a given concentrating operation; however each criterion has certain restrictions or limitations. It is important, therefore, to understand how such formulas can be used and the problems involved in their construction. Technical Measure of Plant Performance Conventional means for evaluating a preparation plant's performance are generally approached through the use of equipment performance mea-

Jan 1, 1979

By A. B. Kinzel

IT has often been stated that the steel industry did no research or development work in the decades preceding 1920. If restricted to organized research on the quality and field of application of structural and engineering steels, this statement may be true. But the industry did conduct a vast amount of process research during this period, although some of the projects were not carried out as separate organized research programs. Securing a low cost of tonnage production was the sole problem receiving serious attention from the industry prior to 1920, and today this is still the major problem. Those in the industry deserve much commendation for the important increase in production capacity per dollar invested and for the markedly lowered cost of production. In recent years, a distinct change may be noted in the attitude of the steel industry toward research involving its product. With the advent of high-speed machinery both in the manufacturing and transportation industries, steel as a quality engineering material has come to the fore. In the past, high-quality carbon steels and alloy steels have been introduced over a period of years, largely at the insistence of the consumer and partly prompted by research carried out by those interested in the use of the alloys. The commercial introduction of these materials made slow progress.

Jan 1, 1935

By J. B. Newsom

IN the September 1936 issue of MINING AND METALLURGY the pioneer work of boring a 5-ft. shaft to a depth of 1125 ft. at the Idaho Maryland mine in California was described. Later, a Bureau of Mines Information Circular (No. 6923) gave additional data. In re¬cent months still further progress has been made in this technique through the sinking of a 5 1/2-ft. shaft for Pickands, Mather & Co. at their Zenith mine, Ely, Minn. The present work was done with new carefully designed equipment and several experienced men so that progress, as shown below has been much better:

Jan 1, 1938

By Arthur F. Taggart

The major portion of the work described in this paper was performed by R. W. Young, † a graduate student in the department of Mining and Metallurgy, Sheffield Scientific School, Yale University, working under a cooperative agreement between the Hardinge Conical Mill Co., the Sheffield Scientific School, and himself. Since this cooperative scheme is at present in effect in the case of a considerable number of other students in the department and since it is the hope of the school that the privilege thus extended may be utilized even more freely in the future by mining and manufacturing companies, it may not be amiss at this point to give a summary of the general plan. Briefly it is as follows: A graduate student, whose undergraduate work in this or other universities shows promise of ability to handle research work, is chosen by conference between the company and instructor involved. The aim of the company in the agreement then entered into is to obtain the solution of one or more of the technical problems with which it may be confronted, or, at the end of 1 or 2 years, to obtain as an employee a man especially trained in its work. As a means to accomplish one or both of these ends, the company furnishes the machine, apparatus, or material to be tested and pays the student during his graduate work a small salary, usually just sufficient to cover his living expenses, tuition and fees. The aim of the student is special training along a line in which he is particularly interested, the attainment of his advanced degree, and the chance to show to his future employer ability to handle such problems as may be presented to him. In return for the financial aid which he receives he agrees to devote at least half of his working time to the special problem submitted by his company. The other half is devoted to study of the collateral subjects required by the department for the granting of the degree which the student seeks. The student further agrees to enter the employ of the company in question at a wage not greater than that paid in like positions to recent graduates not specially trained and to remain with his employer at such wage for at east 1 year. If the student is to obtain a degree, the special work forming the basis of his investigation must be such as will involve real research and not mere routine manipulation. The subject is chosen by conference between the three parties to the agreement. The work is carried on under the direct supervision of the instructor involved. The school furnishes the general laboratory and library equipment essential to the pursuit of any extended investigation. In

Jan 1, 1918

By G. K. Burgess

THE question of the allotropy of iron, in spite of a vast amount of experimental work and perhaps an even greater amount of theorizing, is not yet settled. That there is a definite transformation in iron near 900,° the A3 point, is generally recognized, as well as the fact that the temperature of this transformation is lowered by the addition of carbon and metallic elements. On heating, the transformation Ac3 is always found at a higher temperature than the transformation on cooling, Ar3. Whether the A3 transformation is sharp like the melting point of a pure substance, or extends over a considerable range of temperatures, embracing perhaps as a lower limit the A2 change, appears to be still an open question for pure iron. The nature and identity of the A2 transformation, it would appear from recent publications, has not yet been satisfactorily settled. In the present paper a critical, historical summary is given of the experimental investigations of the location of A2 and A.3 in pure iron, together with brief mention of some of the theoretical aspects of the subject, and an account is given of a series ?of experiments carried out with several samples of very pure iron which were studied by two methods of thermal analysis in the range from 5000 C. to 1,000° C., and which it is believed furnish a contribution of considerable interest as to the location and nature of the A3 and A2 transformations. Great attention has been given to the details of experimental manipulation and to the preparation of the samples, as it was soon found that some of the discrepancies noted in the work of many experimenters may be traced largely to lack of precautions which we have found essential. For example, to anticipate somewhat, it is necessary to provide a suitable practically gas-free furnace, the heating and cooling of which may be regulated to a nicety. To render a minimum the deforming effects on the cooling and heating curves of the poor conduction of the sample, it must be of a form and mass to pass on its heat rapidly and completely to the thermocouple; and finally the sample itself must be freed from gases which, if present, further mask the definiteness of the heating and cooling curves. We, have also varied within wide limits the several factors which may influence the determination of the exact location and shape of the transformation ranges, especially the mass and preparation of sample, rate of heating and cooling, design of furnace; and finally, as nearly as it is experimentally possible, we have worked with a substance approaching pure iron, free from occluded gases and other impurities, and contained within a vacuum.

Jan 10, 1913

By Henri V. Reibell

Deep open pit optimization supposes very long and sedious calculations in order to assign the best shape of the pit and the best bottom level, which will give the biggest profit. Computers give the possibility to make these calculations. More over, they allow to multiply trial calculations so that it is possible to obtain more reliable results. The paper does not expose the computer program but only the way in which mining engineers can use it.

Jan 1, 1969

By E. I. Gordon

The electronic pickup tube is the image-to-video signal-converter or transducer in tele vision-like systems. Images may relate to visible light or IR excitation as in conventional TV systems, X-ray excitation as in some medical and production control applications, or electron excitation as in electron microscopy. The latter process is also important in some forms of light or X-ray sensitive pickup tubes as an intermediate step. In virtually all of these devices the image ends up as a stored charge pattern on a suitable target electrode and the video signal is created by periodically scanning the target with a low energy electron beam and removing the stored charge. In a major group of tubes radiation induced conductivity creates the charge pattern. In others, photoemission is used. In this paper an attempt is made to illuminate some of the device requirements placed on materials exhibiting radiation induced conductivity, some of the materials and techniques that are used, and the problems. The emphasis will be on visible light and IR sensitive targets although some attention will be given to X-ray and electron imaging. Photoconducting films as well as diode arrays will be discussed. ELECTRONIC pickup tubes find their greatest use in commercial, entertainment television, and in industrial and educational closed-circuit television. Video telephone systems, such as AT&T's PICTURE-PHONE System will become eventually the greatest user. Military use is also very important. Nevertheless the use of electronic pickup tubes in technology, science, and medicine is assuming ever greater relevance and demands the greatest diversity and perfection in the pickup tube art. Commercial television and closed-circuit television use requires visible light response, high resolution, low lag, and uniform response. Video telephone use requires the same plus extreme reliability, stability, and low cost. Military use emphasizes, in addition, sensitivity, IR response, and ruggedness. (Devices for far IR response will not be considered here.) The use of pickup tubes in medicine and biology emphasizes UV response for microscopy, X-ray response for radiology, and energetic electron response for electron microscopy. Astronomy and nuclear physics demands low light level response, storage ability, and resolution (here the tube is a successful replacement for film). The interested reader might profitably read Advances in Electronics and Electron Physics, vol. 12,' 16,2 and 22A3 and 22B4 for detailed discussion of the use, properties, and technology of electronic pickup tubes. In general, because of the importance of these uses, none of the above properties will be ignored. Nevertheless attention will be restricted to only those imaging devices, called pickup tubes, using a scanning electron beam to dissect the image with a resulting video signal for conventional CRT display. However pickup tubes have become so complex that many of them include components such as image in-tensifiers which would be normally excluded by this restriction. Thus some of the other imaging devices will not be ignored entirely. We will first review the fundamental elements and physical phenomena involved in modern electronic pickup tubes, then the relevant materials and some of the material problems and then an interesting goal yet to be achieved. REVIEW OF PICKUP TUBE PRINCIPLES In all modern television systems using pickup tubes there is an interval called the frame interval, during which the incoming radiation flux is allowed to produce a cumulative effect in the form of a stored charge pattern which is a replica of the radiation image, and a scan interval during which the stored charge pattern is converted into a video signal. The frame interval bears no fixed relation to the scan interval and may be shorter or longer. In conventional, real time television the scan interval including retrace is identical to the frame interval. Integration and storage is the key to the sensitivity of modern pickup tubes, in contrast to earlier tubes such as the image dissector. At equivalent light levels and without integration, the number of photons contributing to the video signal in the image dissector is lower by a factor approximating the number of picture elements in the displayed image, a number of order 10. Statistical fluctuations in the number of contributing photons represent a serious limitation to the attainable signal to noise ratio, resolution and contrast. As a result considerably greater light levels have to be used then in targets which integrate over the full frame period. Thus the crucial elements, common to all modern pickup tubes, are the charge storage surface and the scanning electron beam which is incident on the charge storage surface at very low energy. These are shown in Fig. 1(a). The charge storage insulator is generally very thin with a thickness of several microns or less. The surface of the insulator is held near cathode potential. The backplate potential is held at cathode potential or at a small positive voltage relative to cathode. The combination of storage insulator and backplate electrode is commonly called the "target". In the absence of incident radiation flux the electron beam scans over the storage surface depositing negative charge uniformly over the scanned part of the surface by virtue of the fact that the effective secondary

Jan 1, 1970