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By M. J. Deats

INTRODUCTION To prepare the reader adequately, reference should be made to the paper 'The Pioneering of Fully Mechanized Longwall Coal Mining in South Africa' by R. T. Naude and M. J. Deats, published in the February, 1967, edition of the Journal. At the time mechanized longwalling had been proved operationally feasible with encouraging results since its inception in South Africa in mid 1965. Subsequently, further top seam panels were successfully extracted with improved productivity and with some modification to equipment. In 1968, after an overseas visit by mine officials, equipment specific to suit local conditions was acquired and lower seam trials commenced. Despite initial obstacles and difficulties the first panel was successfully mined. Modification and improvements to equipment and techniques resulted in the second lower seam panel being extracted economically during 1969-1970 and with productivity exceeding even that of top seam faces. During extraction of the second lower seam panel, gradual and complete surface subsidence occurred over the panel without affecting face operations. Rock mechanics investigations had originally indicated some uncertainty regarding adverse dolerite sill behaviour which could have caused longwall mining to be hazardous. All such doubts have now been removed. RESUMÉ AS AT FEBRUARY, 1967 Mechanized longwalling was introduced in 1965 on an experimental basis in an effort to improve productivity in the newer area of the mine and to increase the quality of the comparatively dirty run of mine feed to the washing plant. In addition advantages could be predicted in the long term by better utilizing reserves of straight coking coal and increasing the life of the mine. The top seam unit was obtained on a rental basis and by the beginning of 1967, two panels, the first having a face length of 215 m, a panel length of 345 m, seam section of 1 219 mm, and the second the same face length, a panel length of 453 m and a seam section of 1 067 mm had been successfully longwalled. At this stage a best month of 24 602 metric tons with an average of 17 364 metric tons per full working month could be reported. Results were sufficiently encouraging for the company to exercise its right to acquire the equipment as its own asset and from 1967 onward, the unit has operated on this basis. From the point of view of rock mechanics, the dolerite sill over the first two panels was known to have 'bridged', only the material below the base of the sill having truly 'goafed'. No adverse pressure effects had significantly affected face operations except for two 'bumps' towards the end of operations in each panel. Gate road maintenance presented no problem. The strong inflows of water experienced on the first face were now known to be associated with an isolated water bearing fault plane and were not experienced on the second face. TOP SEAM EXPERIENCE - MAY, 1966, TO DATE Panel 2 (February, 1966, to November, 1966) The operations in panel 2 (see Fig. 1 for location of panels) continued uneventfully until the final month in this panel. At this stage, the chocks behaved most inconsistently often lowering under the weight of the canopies alone. Roof trouble became so severe that the unit was unable to produce adequately and blasting of chocks became a daily occurrence. Finally 24 m short of the planned limit it was decided that a complete overhaul was the only solution and the extraction operations commenced. At this time, the only fatal accident associated with longwalling occurred when a Non-White inadvertently fell into the panzer conveyor transfer point at the main gate. Some gate road difficulties in this panel were overcome by bolting tapes to the roof as decking and allowing them to pass over the gate chocks and collapse into the goaf. Two cribbed roof falls were also negotiated by the gate chocks at the face ends without undue difficulties. It was decided in the light of maintenance problems encountered on this face that the best solution would be to appoint a foreman solely in charge of face maintenance crews. This step has to a large extent contributed to success achieved subsequently. Panel 2-face length 213 m panel length 456 m cutting height 1 092 mm average monthly output 16 443 t best month 19 130 t Panel 3 (December, 1966, to June, 1967) By the end of 1966 results were sufficiently encouraging for the company to exercise its right to acquire the equipment. This was negotiated and the unit has operated as such to the present date. Prior to installation in panel 3, all face equipment was thoroughly overhauled underground and the chocks boost-tested to yield-load. The costs of overhauling, including almost complete hose replacement, were much higher than anticipated. Advice had been received that complete hose replacement was common practice after +/- 18 months' operation. Shortly after commencement of operations in panel 3 the chocks again failed as they had towards the end of panel 2. At this stage, the suppliers advised that the valve gear should have been repaired during the overhaul as the needle and seat seals could no longer be relied upon. This operation was impossible to carry out on the face and would have been e1ttremely time consuming. Fortunately a new type of valve gear was then available from the suppliers, termed the capsule-type valve, and a complete change over could be made on the face. The encapsulated valve has a delrin pad sealing over a raised

By K. M. Myles

The vapor pressure of palladium over a series of Rlz-Pd alloys has been measured by the torsion-effusion method. The thermodynamic properties of the alloy system at 1575=K have been calculated from the vapor pressure data. The activities and the free energies of formation exhibit large positive deviations from ideal behavior. The enthalpies of formation are endother-mic. The entropies of formation are positive and larger than the ideal entropy of mixing. All of the thermodynamic properties suggest that a strong tendency toward phase separation exists in the solid solutions. The possible origin of the phase instability and the various factors that influence the thermodynamic properties are discussed. RECENT studies of the thermodynamic properties of alloys of palladium with nontransition elements have indicated that a significant contribution to the enthalpy of formation is related to the redistribution of the conduction electrons upon alloy formation.'-' The present work was undertaken to ascertain the importance of this contribution in Pd/transition-metal alloys. The Rh-Pd system was chosen for this investigation for several reasons: 1) The thermodynamics of the system were unknown. 2) Rhodium and palladium are completely soluble at high temperatures; below 1118OK the solid solution becomes immiscible.', 3) The difference in magnitude between the vapor pressures of rhodium and palladium permitted the use of an existing effusion apparatus. 4) Additional information was known about the alloy system that would facilitate the interpretation of the thermodynamic results. EXPERIMENTAL PROCEDURE The thermodynamic properties of the Rh-Pd alloy system were calculated from the vapor pressure of palladium over solid palladium and over several solid Rh-Pd alloys. The vapor pressure was measured by means of the torsion-effusion apparatus that has been described previously. In this method, an effusion cell is suspended from a tungsten filament inside a high-temperature furnace. Two orifices are located eccentrically such that the effusion of the vapor creates a rotational torque in the filament. The angle of rotation is directly related to the total vapor pressure within the cell. As the vapor pressures of rhodium and palladium are approximately five orders of magnitude apart," the total vapor pressure was considered to be effectively equal to the equilibrium vapor pressure of palladium. The effusion cells were made from high-purity alumina since auxiliary experiments indicated that essentially no reaction occurs between alumina and solid Rh-Pd alloys. Unfortunately, because the orifices were irregular, an accurate calculation of the Free- man-Searcy correction factors" could not be made. The constants were determined in an independent experiment where the vapor pressure of copper, as measured in the alumina cell, was compared with an accurate value of the vapor pressure, which had been determined previously.4 Depletion of palladium from the surfaces of the specimens was minimal as the deflection of the cell remained constant, for at least 15 minutes, at each of the experimental temperatures. Lattice parameter measurements of the postrun alloys also indicated that no changes in the composition of the surfaces had occurred. The alloys were prepared by arc melting the requisite amounts of the 99.99 pct pure elements. The four most palladium-rich alloys were remelted in a levita-tion furnace since complete melting of the components had not occurred in the arc furnace. All of the alloys were subsequently homogenized at elevated temperatures in sealed alumina thimbles. After heat treatment, the alloys were analyzed chemically and were in essential agreement with the nominal compositions. The thermal histories and nominal compositions of the alloys are given in Table I. Lattice parameters of the heat-treated alloys were computed, by means of the method described by Mueller et a1. ,I2 from X-ray diffraction powder patterns obtained with filtered copper radiation in a 114.6-mm-diam Straumanis-type Debye-Scherrer camera. The results, which are tabulated in Table I, exhibit a slightly greater negative deviation from Vegards' law than the values reported by Raub et al.13 The diffraction lines were sharp and well-resolved and thus indicated that the alloys were homogenous. RESULTS The logarithms of the individual values of the vapor pressure of palladium were fit, by the least-squares method, as a linear function of the reciprocal of the absolute temperatures. The constants of the equations are given in Table I along with the temperature range over which the data was accumulated. The latent heat of vaporization at 298.15"K for pure palladium, calculated by the third-law method,14 showed no systematic temperature dependence. The average value of 88,920 * 20 cal per g-atom agrees favorably with the average of the results obtained in the most reliable previous investigations.15"19 The activities of palladium were computed from the vapor pressure data at 1525', 1575", and 1625OK. Consistent with the mass spectrometric study of the atomicity of palladium vapor,lg the vapor was assumed to be monoatomic. The activities of rhodium were determined by integrating the Gibbs-Duhem equation with the aid of the a function.20 In the calculations, the activities of the pure solid metals were assigned the value of unity. From the activities, the partial and integral free energies, entropies, and enthalpies of formation at 1575° K were computed; they are assembled in Table 11.

Jan 1, 1969

By T. K. McMahon

Formally, a mathematical model could be defined as: A set of equations whose solution will approximate the response of a physical process or system to a set of stimuli which appear as parameters in the equations. The purpose of a mathematical model is to permit the rationalization of experience to proceed by simulation rather than by physical experimentation. In the application of digital computer control to an industrial process, the mathematical model of the process (subsequently called the process model) is needed to calculate the present process performance from the measured variables and to predict the response of the process to a control change. Functionally, the cardinal element in process model development is a concise set of control objectives. These, besides implicitly defining the boundaries of the system to be modeled, will determine the accuracy demanded of the model its nature: dynamic or steady-state, and so forth, The objectives should explicitly define what process efficiencies, production rates, qualities are to lie within the scope of the computer control project, thereby providing a basis for simplifying assumptions in the development of the model. This requirement, a limited set of control objectives, is so often disregarded in formulating industrial control problems that its repetition can scarcely be avoided.

Jan 1, 1965

By J. H. Swisher

The rate of internal sulfidation of austenitic Fe-Ti alloys in H2S-H2 gas mixtures is controlled primarily by sulfur diffusion, with counterdiffusion of titanium playing a minor role. At temperatures below 1100°C, enhanced diffusion along grain boundaries becomes important. The rate of internal sulfidation at 1300°C is approximately equal to the rate computed from the sulfur diffusion coefficient. The diffusion coefficient of titanium in y iron has been determined from electron microprobe traces in the base alloy near the subscale interface. The solubility of sulfur in Fe-Ti alloys has been measured in the temperature range from 1150° to 1300°C. The equilibrium sulfur content is found to increase with titanium content, due to the large effect of titanium on the activity coefficient of sulfur. The Ti-S interaction becomes stronger as the temperature decreases. TITANIUM as an alloying element in stainless steels is an effective scavenger for interstitial impurities, carbon in particular. Titanium is known to form stable sulfides; however extensive thermodynamic data on the Ti-S system are not available. Schindlerova and Buzek1 have shown that the Ti-S interaction in liquid iron is moderately strong. There have been no previous studies of the Ti-S interaction in solid iron. Internal sulfidation of Fe-Mn alloys was the subject of a recent investigation by Herrnstein.2 He found the rate of internal sulfidation to be an order of magnitude greater than predicted from available solubility and diffusivity data. A satisfactory explanation for the discrepancy could not be given. In the present study, the solubility of sulfur in austenitic Fe-Ti alloys was measured using a standard gas equilibration technique. Fe-Ti alloy specimens were also internally sulfidized. The rate of internal sulfidation was measured as a function of temperature and alloy composition. Supplementary electron micro-probe measurements were made to provide additional information on the nature of the internal sulfidation process. EXPERIMENTAL The starting materials were alloys containing 0.12, 0.24, 0.38, and 0.54 wt pct Ti. The alloys were made in an induction furnace by adding titanium to electrolytic iron that previously had been vacuum-carbon-deoxidized. The major impurity in the alloys as determined by chemical analysis was carbon. The carbon content of the alloys averaged about 100 ppm; metallic impurities were presented in concentrations of 50 ppm or less. Specimens were made in the form of flat plates, 0.03 by 2 by 4 cm for the equilibrium measurements and 0.5 by 1.5 by 3 cm for the rate measurements. The experiments were performed in a vertical resistance furnace wound with molybdenum wire and containing a recrystallized alumina reaction tube. In the gas train, flow rates of the reacting gases were measured using capillary flow meters. The source of H2S was a mixture of approximately 2 pct H2S in H2, which was obtained in cylinders from the Matheson Co. A chemical analysis was provided with each cylinder. The H2-H2S mixture was diluted with additional hydrogen to obtain the desired ratio of H2S to H2, and the resulting mixture was diluted with 30 pct Ar to minimize thermal segregation of H2S in the furnace. Argon was purified by passage over copper chips at 350°C and subsequently over anhydrone. Hydrogen was purified by passage over platinized asbestos at 450°C and then over anhydrone. The H2-H2S mixture was purified by passage over platinized asbestos and then over Pas. The samples used in the solubility measurements were analyzed for sulfur by combustion and iodometric titration. The subscale thickness in the internally sulfidized samples was measured on a polished cross section, using a microscope with a micrometer stage. Electron microprobe traces for titanium in solution were made on several samples that had been internally sulfidized. A Cambridge microanalyzer was used, and the known titanium content at the center of the specimen was used as a calibration standard. The procedure for the microprobe measurements will be described further when the results are presented. RESULTS AND DISCUSSION Equilibrium Data. Fig. 1 shows the sulfur concentration as a function of gas composition for three alloys equilibrated at 1300°C. The dashed line is based on data published by Turkdogan, Ignatowicz, and pearson3 for pure iron. The breaks in the curves are the saturation points for the alloys. The fact that the initial slope decreases with increasing titanium content indicates that titanium interacts strongly with sulfur in solution. To obtain information on the composition of the precipitating sulfide phase, the measurements described in Fig. 1 were extended to higher sulfur partial pressures. These results are shown in Fig. 2. (The initial portions of the curves are reproduced from Fig. 1.) The highest PH2s /pH2 ratio used is believed to be below the ratio required for the formation of a liquid sulfide phase. Time series experiments were used to study the approach to equilibrium in the samples. It was found that equilibrium with the gas phase was reached in less than 4 hr at 1300°C.

Jan 1, 1969

By H. A. Lesser, H. L. Stone, G. H. Bruce

ESSO PRODUCTION RESEARCH CO., HOUSTON, TEX. A mathematical model that represents the conduction heating of a rock formation of limited permeability is formulated. Heat is introduced by the injection of a hot condensing gas into horizontal fractures through the formation. The fractures are assumed to be equally spaced; the flow of fluid is linear. The model consists of three coupled partial differential equations and two functional relationships. Temperature histories for both fractures and formation are obtained by numerical procedures. Application of the model in predicting in situ heating of oil shale is illustrated with four sample cases. Influences of shale thermal diffusivity, fluid pressure in the fracture and fracture spacing upon heating rate are demonstrated. In all cases considered, several years were required to heat all the formation to 700F with 1,000F steam. Less than 32 per cent of the injected heat was utilized for heating the shale. To facilitate extensive calculations of this type, a set of seven dimension-less quantities are derived. With this dimensionless system, the effect of controllable parameters on economics can be explored. INTRODUCTION Vast deposits of hydrocarbons are contained in oil shale formations in the western United States and in other countries. These hydrocarbons, known as kerogen, are difficult to recover because they are immobile solids and because the rock formations in which they are found have very limited permeability. The kerogen can be converted through pyrolysis to recoverable liquids and gases if the formation temperature is elevated to the range 600 to 800F. To accomplish this heating, the formation might be artificially fractured and a hot fluid injected into the fractures. If the injection and production wells are vertical and the fractures horizontal, interwell communication will be established and the hot fluid will flow from an injection well to a production well. In this process, some of the heat in the fluid will be given up and conducted into the formation. Products of pyrolysis will flow from the heated rock matrix into the fractures and be produced, commingled with the injected fluid. The practicality of such a process is strongly influenced by the rate at which heat can be transferred from the hot fluids to the formation. An analysis of this heat conduction problem is the subject of this paper. Linear flow of a condensing gas through a set of horizontal, equally spaced fractures is considered. Temperature histories for both fractures and formation are obtained from numerical procedures. The analysis also applies to formations containing streaks of natural permeability instead of fractures. Heat flow problems similar to the one treated here have been studied by other workers. Thomas1 has solved a radial problem in which he considers the injection of a noncondensing gas into a single, horizontal fracture and approximates the temperature profile in the fracture by a step function. The solutions to other problems, which are less similar to the present problem than the one treated by Thomas, have been reviewed by Spillette.2 In addition to these mathematical studies, a field test of an in situ shale oil recovery process using hot natural gas as the injected fluid has been reported.3 The first part of this paper is concerned with the mathematical development of the problem. The differential equations, boundary conditions and functional relationships which describe the physical model are formulated and the equations are cast into finite difference form. The method of solution of the difference equations is discussed (Appendix B). The second part of this paper presents results computed for a typical oil shale formation for which steam at 1,000F is the injected fluid. Fracture spacing, horizontal and vertical thermal diffusivities

Jan 1, 1967

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

By Raynor Linzey, Karl M. Busen

The formation of thin films of silicon oxide by anodic oxidation of silicon and the subsequent removal of these films by an etch is a process often used for the evaluation of concentration distributions Profiles) in silicon layers by the differential sheet conductance method. The accuracy of the resulting profile is very strongly influenced by the uniformity of the thickness of the reacted silicon. Normally, it would be expected that for a constant number of coulombs passed the thickness would be the same from oxidation to oxidation. Investigations show that in certain electrolytes, for a given number of coulombs passed through an n-type silicon sample, the thickness of the reacted silicon increased with increasing resistivity. Even for the same resistivity the thickness varied sometimes by a factor of 1.5. When an electrolyte was used which consisted of 10 pct water by volume in ethylene glycol with 4.0 g KNO per 1000 ml of solution, anodiza-tion at 5 ma per sq cm led to satisfying results. Short-time anodizations gave oxide layers of a higher apparent density than those experienced from thermally gown silicon oxides. THE functioning and the electrical characteristics of semiconductor devices are based upon the incorporation of "impurities" into a single-crystalline body of suitable material and on the concentration distribution (profile) of this impurity. The incorporation can be achieved by well-known processes as, for example, by diffusion, epitaxial growth, alloying, or ion implantation. Often the profile resulting from these processes is not known. A powerful tool to learn about a concentration distribution is given by the method of differential sheet conductance which employs successive four-probe measurements on a layer subjected to stepwise removal of thin sublayers. Differential sheet conductance vs position (or penetration depth) of a sublayer is plotted and a smooth curve is drawn through the data. From this curve the profile is then calculated. When the semiconductor material is silicon, the sublayers are removed suitably by anodic oxidation of the silicon and subsequent dissolving of the formed silicon oxide by an etch. The accuracy of the resulting profile is very strongly influenced by the uniformity of the sublayer thickness. Normally, it would be expected that, for a constant number of coulombs passed, the thickness would be constant from oxidation to oxidation. Investigations showed that for sublayers several hundred angstroms thick the reproducibility can be rather poor. Therefore, efforts were made to obtain a reliable technique for uniform removal. The present paper describes such a technique and certain phenomena which were encountered during the investigations. APPARATUS AND TECHNIQUE The first report on the investigation of concentration distributions, where for differential sheet conductance measurements thin silicon sublayers were removed from a diffused layer by anodic oxidation, was given by Tannenbaum. The author reports the removal of sublayers which for the most part were 400 thick. More advanced device designs now require much narrower layers. When it was tried in these laboratories to determine profiles within such layers, difficulties were encountered with respect to sublayers which by necessity had to be thinner than the ones reported by Tannenbaum. The apparatus used for the investigations is sketched in Fig. 1. Two cylindrical containers connected by a wide tube are filled with an electrolyte. The left container receives the cathode whereas the right container is closed at the bottom end by a sample support consisting of a Teflon base and a copper pedestal. The silicon sample (1 by 1 cm) is mounted to the pedestal embedded flush in the Teflon base using silver paint (Degussa) for electrical contact. Pyseal is applied to the edges of the sample to protect the copper pedestal from the electrolyte. The base is mounted to the container using a water-tight silicon rubber gasket. Fig. 2 gives a view of the sample support. The copper pedestal is connected to the positive side of a power supply operating at a constant current output (Kepco Model ABC 425M). The electrolyte which has been reported by Duffek et al. consisted of either 2 or 10 pct water by volume in ethylene glycol and 4.0 g KNO3 in 1000-ml solution. The electrolyte is best prepared

Jan 1, 1967

This study relates to continuous face haulage systems in underground coal mines, and was performed by Joy Manufacturing Company for the U. S. Bureau of Mines under the Bureau of Mines Contract No. HO 242025. The effective starting date for this work was June 14, 1974. There were two main reasons for making this study, the first being to find a safer system to move coal away from the face than the currently predominant shuttle car system, and the second being to seek ways to advance the state-of-the-art of continuous face haulage as a means of increasing coal production.

Jan 1, 1975

By Chris A. Fleming, Daan Seymore

The Golden Jubilee Mine in South Africa is the first mine in the Western World to introduce resin-in­pulp technology for the recovery of gold from a cyanide-leached slurry. Located in the Eastern Transvaal region of the country, the plant processes approximately 375 metric tons• of ore per day, of which over 90 per cent is mined in an open pit adjacent to the metaflurgical plant, while the remaining 5 to 10 per cent is trucl<ed in from two small high-grade deposits, located about 10 kilometers from the plant. The gold grade in the open pit is about 1 git, while the values m the two high-grade deposits range between 5 and 15 git. At the current treatment rate, the proven reserves m the three locations will last about another 10 years. Early testwork indicated that the ore was not well suited to conventional filtration processing or to heap leaching because of its high cfay content, and that carbon-m-pulp (CIP) would probably prove to be the most viable metallurgical route. Tcstwork to establish the feasibility of CIP for this application was carried out at Mintek in 1985. This worl<, which was based on batch-leaching and carbon-loading tests, indicated that CIP was technically feasible, but that both the rate of gold loading and the gold-loading capacity of the carbon were inferior to those obtained with Witwatersrand ores. The poor adsorption characteristics of the carbon were attributed to the abnormally high concentration of natural organic compounds (humates and fulvates) in the ore. Batch tests were therefore also carried out with strong-base resins, since resins are known (1] to be far less susceptible to organic fouling than is activated carbon. The results were very promising, and pointed to fast kinetics and a high loading capacity. (Fig. 1 ). Notwithstanding these findings, it was decided to recover gold with activated carbon at Golden Jubilee Mine because the CIP process was, by then, well established in South Africa and elsewhere in the world, whereas resin-in-pulp (RIP) was unproven technology. The r>lant was commissioned in September 1986 and, for 18 months, operated in a carbon-in-leach (CIL) configuration, i.e. with a total of . six leach tanks, the last four of which contained activated carbon. As could have been predicted from the laboratory results, the performance of the CIL plant was generally poor, low gold loadings on the carbon (less than 1500 git) and high losses of soluble gold (0.2 to 0.3 p.p.m.) bemg characteristic of the operation. Consequently, it

Jan 1, 1990

By Raymond W. Henn

The 32nd annual short course ?Grouting Fundamentals and Current Practice? was held at the Colorado School of Mines, June 13-17, 2011. The field demonstration portion of the course was conducted June 16 at Baski Inc.?s yard in Denver, CO. The full-scale field demonstration presents many types of drilling and grouting equipment in operation as well as numerous grouting methods per-formed under various field conditions. As part of the field demonstration, the class was shown the proportioning, mixing, testing and injection of various cement grout mixes into sand columns under controlled and recorded conditions. These sand column demonstrations have been conducted under controlled and measured conditions each year since 1999 as part of the short course. The sand column demonstrations were conducted prior to 1999, but with less quality control and minimal record keeping of the proportioning, mixing, testing, injection pressures and the final permeation results.

Jan 1, 2011

By W. C. Phalen

SALT-MAKING PROCESSES THE production of salt in the United States divides itself at the outset into two distinct classes: (1) The mining of rock salt and its purification and separation into marketable sizes, and (2) the production of salt by evaporation from brines, bitterns, and other solutions. The processes employed at the present time in the manufacture of salt by evaporation may be outlined as follows: 1. Solar evaporation. 2. Direct-heat evaporation (a) in open kettles; (b) in open pans. 3. Steam evaporation, (a) in jacketed kettles, (b) in grainers. 4. Vacuum-pan evaporation. In this paper only the solar-evaporation processes practised in different parts of the United States will be described. SOLAR EVAPORATION Localities In the Eastern States the solar-evaporation process is not generally employed for climatic reasons. In the Western States, particularly in California and Utah, the great bulk of the salt produced originates in the solar-evaporation process. Of the Eastern States producing salt, this process, so far as the writer is aware, is employed in New York State only.

Jan 9, 1914

By Peter A. Rona

Hydrothermal mineralization along slow-spreading oceanic ridges and rift -zones that comprise more than half the global length of the seafloor spreading center system is related to anomalous physical and chemical conditions acting within the geologic settings that characterize early and advanced stages of opening of an ocean basin. Mineralization in the early stage of opening is represented by the Atlantis II Deep of the Red Sea. There, hypersaline hydrothermal solutions discharging as density stratified brines into an axial basin, have formed the largest massive sulfide deposit (70 x 106 metric tons) known at a spreading center. Mineralization at the advanced stage of opening is represented by two types of sites: (1) oceanic crust on the wall of a rift valley; and (2) oceanic crust exposed on the wall of a transform fault zone. The first type of site is the TAG Hydrothermal Field, located on a wall of the rift valley of the Mid-Atlantic Ridge at the top of the basaltic layer of oceanic crust. Evidence is presented for multi-stage, high- and low-temperature hydrothermal activity that produces Cu, Fe, and Zn enrichments within the thin sediment column and stratiform interlayered deposits of manganese oxides, iron oxides, hydroxides and silicates, on the seafloor. The second type of site occurs along walls of transform fault zones of the equatorial Mid-Atlantic Ridge and Carlsberg Ridge, which exhibit stockwork-type Cu-Fe sulfide mineralization

Jan 1, 1985

By D. F. Atkins, B. A. Rogers

The constitutional diagram presented herein is relatively simple. Complete mutual solid solubility exists for an interval below the solidus line, a continuous curve with a flat minimum near 22 pct Cb and 1740°C. Upon cooling, the solid solution breaks up, except at the columbium-rich side, from two causes: zirconium-rich alloys transform under the influence of the ß-a transformation in zirconium; alloys of intermediate composition decompose into two solid solutions below 1000°C. The combined effect is the formation of a eutectoid at a temperature of 610°C and a composition of 17.5 pct Cb. The eutectoid horizontal extends from 6.5 to 87.0 pct Cb. Some age hardening effects have been observed in the zirconium-rich alloys but the positions of the solvus lines remain uncertain. IN recent years, zirconium has been produced in much larger quantities than were available previously. Correspondingly, the incentive for studying its alloy systems has increased, as the number of recent publications on alloy systems testifies. However, only a partial diagram of the Zr-Cb system has been published and relatively few references have been made to alloys of the two metals. Hodge&apos; investigated the Zr-Cb system up to about 25 pct Cb. His data on melting points were not sufficiently numerous to distinguish with certainty between the alternatives of a narrow eutec-tic horizontal and a wide flat minimum in the solidus curve. Although Hodge considered his results on transformations in the solid state to be only tentative, he suggested that the eutectoid in the zirconium-rich alloys lay at about 625 °C and 10 pct Cb and estimated that the solubility of colum-bium in zirconium at 625 °C was near 6 pct. According to Simcoe and Mudge,2 less than 0.5 pct Cb is soluble in zirconium at 800°C. These authors observed an increased strength in both the 0.5 and I pct Cb alloys made with hafnium-containing zirconium. According to Keeler,3 the strength of zirconium is increased by addition of columbium to a content of at least 3 pct. Keeler&apos; also observed a maximum in hardness at about 10 atomic pct Cb and commented on the brittleness of alloys of this composition. Anderson, Hayes, Rober-son, and Kroll5 investigated the tensile properties of Zr-Cb alloys containing 5.1 and 12.9 pct Cb at room temperature and at 343°C. The 12.9 pct alloy had a high tensile strength at room temperature but also a low percentage of elongation. All alloys had high elongation at 343 °C. Littona measured strength and elongation values of annealed alloys containing up to 27.5 pct Cb and found low elongation values for all of the alloys of high columbium content. Some observations on the resistance of Zr-Cb alloys to corrosion in water at high temperature have been published by Lustman, De Paul, Glatter, and Thomas&apos; who found that additions of columbium up to 1 pct had only a minor effect on the corrosion resistance of zirconium. Preparation of the Alloys Raw Material: Zirconium of a relatively good grade was available for making the alloys. It was obtained as scrap pieces that had been left over from an operation that included production by the iodide process, melting under a protecting atmosphere, and fabrication to plates. The individual pieces had hardness values of 24 to 32 Ra and a typical analysis is shown in Table I. The columbium also was scrap trimmed from sheets. It was furnished by the Fansteel Metallurgical Corp. and had a high ductility but its analysis was known only approximately. The metal probably contained about 0.5 pct Ta, perhaps 0.25 pct C, and a few hundredths percent each of iron, silicon, and titanium. Melting: The alloys were melted in a tungsten-electrode copper-crucible arc furnace similar to units that have been described recently in the metallurgical journals.&apos;.&apos; The crucible of this furnace is provided with a cavity in which a getter charge can be melted before the melting of the alloy charges. Hardness measurements on the ingots indicate that the getter charge takes up a considerable fraction of the oxygen and nitrogen from the helium atmosphere of the furnace. The alloys used in the investigation are given with their intended compositions, hardness, and melting points in Table 11. Fabrication: All alloys of the Zr-Cb system appear to be amenable to fabrication. At least, all of the compositions listed in Table II could be reduced to wires in a rotary swaging machine. The starting material was either slabs cut from ingots and ground by hand to rough cylinders or narrow strips trimmed from sheets made by cold rolling slabs. However, not all of the alloys could be fabricated satisfactorily by the same method. From 0 to 4 pct Cb and from 20 to 30 pct Cb or more, the alloys could be swaged cold from ¼ in. cylinders to 0.80 mm wires with only one intermediate annealing, sometimes with none. From 40 to 90 pct Cb, the alloys were difficult to swage either hot or cold but could

Jan 1, 1956

By O. R. Wagner, R. O. Leach

Immiscible displacement tests were performed in a consolidated sandstone core over the interfacial tension range from less thdn 0.01 to 5 dynes/cm to better define how interfacial tension (IFTJ reduction can lead to increased oil recovery. Data obtained were displacement efficiency at breakthbrough vs IFT for both drainage and imbibition conditions. These tests simulate water flooding under oil-wet and water-wet conditions, respectively. Results of the study have shown that displacement efficiency under both oil-wet and water-wet conditions can be markedly improved by a sufficient reduction in IFT. In the particular porous media used and for the low pressure gradients employed, the IFT must be reduced to a value less than about 0.07 dynes/cm to achieve increased recovery at the time of breakthrough of the injected phase. Below 0.07 dynes /cm, further small reductions in IFT result in large increases in displacement efficiency. Observed increases in recovery were obtained at pressure gradients which are well below those which can exist in the interwell area of a reservoir under water flood. The effect of pressure gradient on recovery is discussed. INTRODUCTION A residual oil saturation remains in rock which has been water flooded because, under usual reservoir conditions, the driving force which can be generated is inadequate to expel oil trapped by capillary forces. Since these capillary forces can be reduced by reducing the IFT a frequently studied method of increasing oil recovery has been the use of surfactants to reduce the water-oil interfacial tension. Mungan l observed improved recovery in both water-wet and oil-wet systems at 1.1 dyne /cm IFT, finding that the amount of improvement was greater in oil-wet systems. Moore and Blum,2 working with visual flow cell micro-models, con- cluded that recovery cannot be improved in water-wet systems by injecting surfactant solutions. They calculated that, for a pressure gadient of 1 psi/ft in their model, the IFT must be reduced to 0.03 dynes/cm to release oil trapped under water-wet conditions. Berkeley et al.3 indicated that, at representative field flooding rates, the IFT must be reduced to 0.001 dyne/cm to improve recovery, Thus, there is a wide variation of opinion about the IFT levels needed to improve recovery under field conditions. These previous investigators all have used as their experimental method the addition of surfactants to the injected water. The use of surfactant solutions to reduce IFT creates two experimental problems: (1) the loss of surfactant through adsorption on reservoir rock can obscure the true IFT value which exists at the displacement front, and (2) at very low values of IFT emulsifica-tion of oil and water commonly occurs. It is difficult, therefore, to determine whether the increased recovery is caused by IFT reduction as such, or is instead caused by emulsification. Also the properties of the available surfactants limit the IFT range which can be studied. In the present study the purpose is to better define how interfacial tension reduction can lead to increased oil recovery. A matter of great interest is the amount of recovery improvement potentially achievable in this way. The study was made using very low pressure gradients which was well within the range achievable by water flooding in the interwell region of petroleum reservoirs. A unique experimental approach was chosen to avoid adsorption and emulsification problems, and to allow convenient control of IFT. The fluid phases used were the equilibrium vapor and liquid phases of the methane-n-pentane system. The interfacial tension level was varied by changing the equilibrium pressure of the methane-pentane system over the range from 1,200 psia to near the critical pressure (2,420 psia). All tests were performed at a controlled temperature of 100F. The IFT-vs-pressure relationship for the methane-pentane system was based on the data of Stegemeier and Hough,6 and on new data obtained in this study. With this experimental approach it has been possible to study displacement at lower values of IFT than have been previously investigated.

Jan 1, 1967

By M. M. Papic, G. M. Kimber

"Hat Creek coal was treated by the liquid solvent extraction process in a continuous plant at the U.K. National Coal Board Coal Research Establishment.Extraction levels of over 80 per cent dry-mineral-matter-free (dmmf) coal were achieved.Total light oil yield was around 47 per cent of the dmmf coal. The light oil was shown to be a good feedstock for secondary refining into gasoline, jet fuel and diesel fuel.In spite of the high mineral matter content of the coal the solid residue was successfully removed from the coal extract by filtration.IntroductionBritish Columbia Hydro (BCH) and the National Coal Board of Great Britain (NCB) undertook a joint project to test the Hat Creek coal from British Columbia in the NCB&apos;s coal liquefaction process designed to produce transport fuels and feedstocks for the chemical industry by the liquid solvent extraction of coal(1), In this process most of the coal is dissolved in an aromatic solvent and the residual solids consisting of mineral matter and undissolved coal are removed by filtration. The resultant coal extract solution is fed to a hydrocracker for conversion to light liquid products and a fraction suitable for recycling as solvent. The light liquid products can be converted to gasoline and diesel fuel in a secondary refining stage.The dissolution of the coal is effected by heat-treating a slurry at a temperature in the region of 400°C which causes some bonds in the coal to rupture with the formation of radicals(2,3). These radicals are stabilized by hydrogen transfer from the hydroaromatic groups in the solvent, resulting in a reduction in the molecular weight of the coal. In the absence of donor groups the radicals combine to form an insoluble high molecular weight product(4). From studies of the kinetics of these reactions it has been shown that the formation and stabilization of the radicals is rapid at temperatures around 400°C(2,3). The dissolution of the depolymerizing coal is, however, relatively slow and the need to ensure complete dissolution in order to achieve a high extraction restricts the selection of digestion time(5). Further, it is important that digests do not contain depolymerizing coal as it may re-form under the applied stress in the filter cake inhibiting flow through the bed and resulting in low filtration rates(6).Thus, in practice relatively long digestion times are generally required in order to ensure complete dissolution of the depolymerizing coal, while it is also important to avoid depletion of the hydrogen donor groups in the solvent which would lower the rate of hydrogen donation to the coal and thus reduce the extraction yield and adversely affect the filtration(7). Clearly it is desirable to optimize the digestion time and temperature with regard to the extraction yield and filtration properties.The precise control of the distribution of products from the hydro-cracker is important for the composition of the recycle process solvent. The principal functions of the solvent are to provide a source of donatable hydrogen and a vehicle for the dissolution of the depolymerizing coal. Hydrogen transfer from the solvent, achieved by the conversion of hydroaromatic to aromatic groups, stabilizes the radicals formed by thermal cleavage of some of the bonds in the coal resulting in a progressive reduction in the size of the coal molecules(8,9) and dissolution in the solvent. The combination of radicals would result in the formation of insoluble material and a reduced extraction yield of the coal(4). Thus to achieve a high extraction yield the solvent should contain sufficient hydrogen donor groups to prevent extensive radical combination. The composition of the solvent should also be controlled to allow dissolution of the depolymerizing coal and to prevent precipitation of this material during the subsequent processing of the coal digest and extract solution. The formation of a precipitate not only reduces the extraction yield of the coal and adve"

Jan 1, 1985

By M. C. Mulligan

Counter current decantation (CCD) thickener circuits are used to recover soluble metal as pregnant liquor solution from ore leach residue. The basis of CCD operation is to concentrate suspended solids thereby minimizing liquor content in underflow slurry that flow in one direction. Then the underflow slurry liquor is diluted with wash liquor that flows in the opposite direction and the suspended solids are concentrated again and again. The amount of liquor in the thickener underflow contributes to determining the number of CCD stages required to recover the desired amount of soluble metal. Furthermore, similar results could be achieved at a lower wash quantity, reducing the size of downstream equipment. High density thickeners (HDT) are designed to use gravity and compression, and minimize the amount of liquor in the underflow thus minimizing the number of CCD stages. This paper reviews the process used to select HDTs rather than high rate thickeners (HRT) for the Ruashi II copper-cobalt hydrometallurgical process in the Democratic Republic of Congo (DRC), using laboratory HDT simulations, to CCD simulations and thickener design details.

Jan 1, 2009

By J. R. Long, A. H. Roberson, T. R. Graham, R. S. Dean

Experimental work on the properties of high-purity alloys of the copper-man-ganese-zinc system has necessarily required extensive metallographic work to determine the equilibrium conditions in this system. Previous work on these alloys is fragmentary and, unfortunately, based on alloys made with impure grades of manganese, thus introducing significant amounts of iron, silicon, aluminum and carbon. Since these elements are known to affect equilibrium conditions, it became desirable to re-examine these alloys made from the pure metals. The alpha solid solution field was of particular interest and, therefore, was chosen for the initial work, which was outlined to determine the composition limits of this field. Previous Work Heuslerl conducted an extensive survey of the liquid-solid regions of this system and also made an estimate of the solid-phase boundaries at 340°C. The pertinent part of his diagram is given in Fig. I, but it is of limited usefulness, since it applied to a single temperature only and is based on impure alloys under admittedly nonequilib- rium conditions. Bauer and Hansen,2 likewise working with impure alloys, have determined the phase boundaries for alpha-beta brasses containing small amounts of manganese and indicate an increase in the extent of the alpha field with increasing manganese. This is not in accordance with Heusler or with data obtained on pure alloys.3 They also described a third constituent precipitating in the alpha plus beta field below 350&apos; to 400°C. but did not identify this constituent. Guillet4 and Heike and Ledibur6 have also noted this precipitate. Each of these investigators recognized that impurities present in the manganese could and did have an effect on the structure and properties of their alloys. Corson6 in particular pointed out the hardening effects of silicon, aluminum, and carbon in copper-manganese alloys and Heusler reported that his alloys containing more than 25 per cent manganese were extremely brittle. In all probability this brittleness was due to the impurities present. This early work, therefore, should be taken as a general guide for preliminary studies only, and high-purity alloys may be expected to produce different results. The work of the Bureau of Mines laboratories with electrolytic manganese has been briefly summarized by Dean7 but includes only a short section on this system. Later work3 outlined a limited portion of the alpha field in the neighborhood of 65 per cent copper, 10 per cent manganese, and 25 per cent zinc. The present work was under-

Jan 1, 1945

By A. S. Odeh

This paper analyzes the effect of limited entry to flow at the wellbore on the steady-state productivity of a well. Wells that have been opened to flow along a fraction of their productive interval are termed wells with limited entry. Previous work treated the cases of a partially penetrating well, a well producing from the central portion of the productive interval and a well in which several intervals equally spaced were open to flow. In this paper the open interval can be located anywhere within the productive interval. Thus, in a sense, it generalizes previous work. The finite cosine transform was used to arrive at a solution for steady-state flow of a slightly compressible fluid. The solution was programmed for a CDC 1604 computer. Numerical vaIues for rd = 660 ft, r, = 1/4 ft, and range of sand thickness of 20 to 200 ft are presented in graphical form. The effect of rd and r, values on the result is shown in a table. The correct calculation of skin and damage ratio in the presence of limited entry to flow is explained and illustrated by examples. Moreover, the paper shows how to calculate the net decrease in productivity due to the combined effect of limited entry and perforations. INTRODUCTION In some wells only a fraction of the productive interval is open to flow. Location of this fraction is usually dictated by formation characteristics and reservoir behavior. For instance, if a gas cap exists, the open interval is located away from the gas-oil contact to prevent any possible gas coning. Wells that intentionally have been opened to flow along a fraction of their productive formation are tened wells with limited entry. Obviously, unintentional completions of this type also exist. Limited entry to flow decreases well productivity. Magnitude of the loss depends on the fraction of the formation open to flow, on the thickness of the sand, on the location of the open interval and on the ratio of rd /r, where r , is well radius and rd is the drainage radius of the well. The use of pressure buildup data on producing wells to calculate the condition of the formation around the wellbore is an accepted practice. van Everdingenl and Hurst2 introduced the concept of she skin factor s considered to be due to a thin layer of different permeability immediately around the wellbore. These authors dealt with the case of a well of complete radial geometry, i.e., a well with open-hole completion that completely penetrates the formation. The presence of a low-permeability skin results in a loss of productivity, as does limited entry. Therefore, if pressure buildup data obtained on a well with limited entry are used to establish the presence or absence of skin (i.e., formation damage), and a correction is not made for this loss of productivity, the calculations would result in an erroneous skin value. They might indicate the presence of formation damage when in reality there is none, or they might indicate a value larger than the true value. This could lead to an incorrect basis for planning remedial measures. Muskat3 studied the problem of partially penetrating wells for the case of incompressible flow. He presented equations and figures which allow estimation of loss in productivity. Brons and Marting,4 using equations based on Nisle&apos;s work,5 studied the loss of productivity for three cases. The first was for a partially penetrating well; the second was for a well producing from only the central portion of a productive interval; and the third was for a well in which several intervals equally spaced were open to flow. Their work was for steady-state depletion-type reservoirs wherein the well radius of drainage is established and the fluid is considered to be slightly compressible. Considered in this paper is the problem of wells with limited entry in which the open intervals are located anywhere within the productive sand. The finite cosine transform is used to arrive at a

Jan 1, 1969

By C. E. Munroe

In order to meet the emergencies of the world wr, tne quantities of explosivea produced in the Unitecl States, and the number of explosives plants were onti:.1.1.:l,lly ncreased so that when the armistice was declared the Government had on hand larg ..mounts oi militazy explosives in excess of existing military needs. Tle stor3.gs of these explosives entailed a liirge expense and their protection neessitatei the employment of m'3.l'lY men who could be better employed otherwise in the military estlish.11ent. Moreover, mar.y ex.ploives, like QJ.l other material, deteriorate on prolonged storage, They lose tht precise definiteness of properties and behavior on which reliance· is placed in military operations, The continued expen3e and d3.nger ttending storage of theae explosives might be diminished by dcst1et1on of the surplus beyond immediate needs, but such·deetniction is danger• ou5 qnd coetly. Hence, the evident solution o! the problem was the salvage d prompt ut111zation of the ru.rplua •

Aug 1, 1922

RUSSIA was the United States Number One source of manganese ore in 1948 when 34 pet of imports were received from that source, stated Norwood B. Melcher, assistant chief, ferrous metals and alloys branch, Bureau of Mines. In 1949, this country received only 20 pet of 1948 shipments from Russia, and only token amounts are now being received. Aggressive programming by industry and government resulted in prompt increases in shipments from major, producing sources; India, Gold Coast, and the Union of South Africa all increased exports to fill the vacuum left by Russia and provided an excess adequate to increase total imports approximately 290,000 short tons in 1949. Again in 1950, and with, even less ore from Russia, imports increased another 290,000 short tons. Since the shift from Russia as a source of manganese, the United States has received in total about 85 pet of its imports from India, Union of South Africa, Gold Coast, and Brazil in that order of importance. Producers of both home consumed and merchant ferromanganese have been able to adjust downward the manganese content of the home-consumed product and so obtain partial relief. Millions of tons of steel were produced in 1951 with a relatively low grade ferromanganese. This adjustment has been made without decreasing the quality of the steel, although with some increase in cost through introduction of new problems, including increased hand- . ding of material and additional removal of carbon. Forced into a pattern of price and grade structure such as exists today, the producer of ferromanganese must adopt one of three possible courses as a short-range program: 1-He may continue to deplete his stocks by producing standard (78 pet) ferromanganese and hope that the future will bring some form of relief; 2-he may attempt to produce 78 pet ferromanganese by paying higher prices for premium ores; or 3-he may drop the grade of ferromanganese and stretch stocks and future supplies of ore as far as possible. The present rundown condition of Indian railroads is attributed to the fact that the service has had no opportunity to recuperate since the beginning of World War II, while the demand for the movement of commodities has probably increased. The Union of South Africa has expanded its exports to the United States greatly since 1948, but, the showing of that country in 1951 was disappointing. Efforts have been made for some time by firms in the United States, at the urging of the manganese miners in the Union, to prevail on the railroad authority to grant and make available larger allocations of cars for manganese ore movement. As a whole, such efforts have been unsuccessful. Although the allocation of rail shipping has been the obvious factor in the decreased movement of ore, many other less determinate factors appear to be involved. Brazil, long an important supplier of manganese to the United States, has important manganese deposits in three areas, all of which are significant to this country. The Gold Coast is an important source of supply. Its metallurgical ore is particularly of significance because of its unusually high grade which permits considerable latitude in blending with the lower grade materials of South Africa and India. The Belgian Congo should have an output of 100,000 tons or more annually beginning this year. R. S. Dean presented two papers. One with K. M. Leute on hydrometallurgical methods for recovery of manganese from domestic ores and one as sole author on the so-called carbamate or Dean process. The two papers tied into each other. In the first mentioned he reviewed the various processes applicable to oxidized, and nonoxidized and reduced ores. The advantages of each .were pointed out. So far the only process tried on a substantial scale on oxidized ores was the SO2 process used at Las Vegas, Nev., on Three Kids ore during World War II. Many problems were encountered. Some of them were whipped while some of those remaining perhaps would have been whipped had time permitted. Since then work has been done elsewhere to avoid the formation of the troublesome thionates encountered at the Three Kids plant. Dean discussed the thionate and NO, processes as applied to oxidized ores. The only commercially used process on reduced ores is that of making electrolytic manganese. Among others that have been considered are the nitric acid process, the Bradley-Fitch ammonium sulphate process, and Dean&apos;s ammonium carbamate process. Dean&apos;s thesis was that extremely large tonnages of so-called low grade manganese ores are available, and that these should not be depleted in attempting to simulate a foreign metallurgical grade ore. He pointed out that the grade of the domestic manganese ores would be considered high if the same grade were found in copper ores. The selling price of electrolytic manganese and electrolytic copper are roughly the same. In addition to electrolytic manganese, he believes that domestic ores should be used to make exceptionally high grade products. These might be battery grade oxide or substantially pure oxide sinter, which might be used for high manganese alloys or for upgrading metallurgical grade manganese to produce a high manganese ferroalloy. The carbamate process is based on the fact that manganous oxide is readily soluble in concentrated ammonia solutions containing ammonium salts. In solutions of sufficiently high concentration the manganese exists as an anion. Lixiviants of ammonia and ammonium carbonate permit extraction of the manganese from reduced ores and the manganese can be recovered as carbonate by heating or by driving off ammonia. R. V. Lundquist presented a paper on upgrading high-silica ores or concentrates with sodium hydroxide to extract silica and to yield a product with a more favorable manganese: silica ratio. The NaOH is, regenerated in part by CaO.

Jan 1, 1952