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By V. S. Gupt, W. H. Somerton

Rock may undergo great changes in physical properties when heated to high temperatures and then cooled, The temperature and intensity of reactions causing rock alterntiorl.s can he controlled by introducing certain chemicals during heat treament. Three typical outcrop sandsone samples were saturuted with common salt solutions, then heated to several maximum temperatures. After cooling, it was found that per-rrreuhilities had increased much more for salt-saturated samples than for samples not saturated with salt but heated to the same temperatures. This was only true, however. for samples heated above the melting points of the particrrlar salts. Potassium chloritle was particularly effective with Bandera sandstone. Samples saturated with potassium chlorirlr. solution and heated to 900C showed an 11-fold increa.se in perrrieahility. Samples without potasrirdrn chloritle but heated to the .same temperature. showed only a 2.7-jold incresre in permecahility. In application, it seems possible that injecting chemicalc into the formations from a wellbore followed by applying intensive borehole heating might promote reactions which would greatly improve permeability of the formalions. INTRODUCTION Great changes in the physical properties of rocks which have been heated to temperatures in the range of 600 to 800C have been reported earlier. Permeability increases of 50 per cent, and equivalent decreases in sonic velocity and breaking strength have been observed. Although there might be some suppression of certain reactions responsiblc for these changes when rock samples are heated under simulated reservoir pressure conditions. recent work has shown that these are more than offset by the increased importance of other reactions at high pressures. The reactions considered responsible for alteration of rock properties by heating include differential thermal expansion. dehydration, phase changes and dissociation of mineral constituents. Ceramists have long known that temperatures at which reactions occur can be raised or lowered by the presence of certain impurities in the sys. tcnl. Thus the possibility exists that by saturating rocks with appropriate solutions. desired reactions might be accelerated and unwanted reactions might be suppressec! when the rock is heated. Purpose of the present work was to investigate the effects of several common salts on the thermal alteration of sandstones. Types of reactions which might occur are reviewed and the findings of a number of thernlochemical alteration tests are presented. THEKMOCHEMICAL ALTERATION OF SANDSTONE MINERALS The most abundant constituent of most sandstones is quartz. Quartz can exist in at least eight different forms, but in the temperature range of immediate interest (to 900C) only two forms are of importance—alpha quartz below 573C and beta quartz above this temperature. Although the alpha-beta inversion of quartz is very important in thermal alteration of rocks. it is not particularly important here because the inversion temperature cannot be changed significantly by the presence of impurities or by the application of pressure. The transition temperature of quartz to tridynlite is 867C. but the transition is very sluggish. Tridymite is considered to be a metastable transition phase between two stable phases: quartz?cristobalite. However. the transition temperature for tridymite to cristobalite is 1,470C.4 The quartz-tridymite-cristobalite transition can be accelerated substantially by the presence of fluxing agents. Finely divided calcium, magnesium and titanium oxides accelerate the conversion while A12O may retard it. A Mixture of NaCl and CsCl reduces the temperature for cristobalite formation by as much as 420°C. Feldspars constitute the second most important mineral in sandstones. The melting points of feldspars range between 1,000 and 1,700°C depending upon the variety. No information available indicated any important role of fluxing agents in the thermal alteration of this group of minerals. Carbonate minerals are subject to dissociation at temperatures within the range of the present investigation. The dissociation of magnesite can start at a temperature of 373°C, but the reaction is sluggish and might not occur untll a temperature of 500°C or ,higher is reached. Dolomite dissociates in two stages at 500°C and 890°C, whereas calcite dissociation temperature is about 885C. Because CO2 is released in the dissociation of carbonates, ail such reactions are somewhat dependent upon CO2 partial pressure. In the absence of CO: in the surrounding atmosphere, the dissociation of calcite starts at 500°C.However. when 1 atm of CO surrounds the sample, the dissociation does not start until 900C. The other carbonates are apparently much less sensitive to a change in partial pressure of CO2. The aragonite calcite transformation can occur an!. where within the temperature range of 357 to 488°C. depending upon the presence of impurities such as barium. strontium. lead and perhaps zinc. The differential thermal analysis (DTA) curves of both magnesitc and dolomite vary with the presence of 'impuritics. The presence of iron in particular seems to affect the magnesitc DTA curve

Jan 1, 1966

By L. G. Huntley

Discussion of the paper of L. G. HUNTLEY,. presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 102, June, 1915, pp. 1333 to 1349. E. W. SHAW, Washington, D. C. (communication to the Secretary*). -The comparatively great extent and uniform character of the Dakota sandstone make it of great interest to the student of rock pores and the movements of their fluid contents. However, compared with other sands in areas of carbonaceous rocks facts concerning it do not seem to be of such great direct importance to the producer for it has thus far yielded few important pools of oil or gas. Information concerning the sandstone is extensive but scattered, hence a general treatise regarding it-particularly its pores, the fluids they contain, and the movements of the fluids-has been much needed. I therefore feel that the. chief thing to be ,desired concerning Mr. Huntley's paper is that it were more extended, particularly as to the discussion of the data presented. The general structure map of the Dakota is of especial interest. Slight changes in wording seem to be desirable here and there in the paper. For example, at the beginning of the third paragraph one-wonders if flora instead of fauna were not intended. In Figs. 2, 3, 4, and 5 the vertical scale seems incorrect. Concerning the analyses of oil quoted it is noted that they "are given, as indicating what may be expected in different localities." This seems to need modification for the average analysis of oil from Powder River, which indicates for example that this oil begins to boil at 213°C. The fact is that the samples to which this figure refers were taken from seeps long exposed. to the air :find hence the underground Dakota oil of this district no doubt differs profoundly from that which the analysis indicates. The product of a well here would probably differ more in boiling point and other. respects from the samples analyzed than it would from almost any other petroleum in the world. The use of the word synclinorium does not conform to the original definition, but this may be pardonable because misuse of the term, though a different misuse, has become general. Synclinorium is an orographic term and cannot be correctly applied outside of mountain regions, for it is derived in part from the Greek word for mountain. It has, however, been widely used in a purely structural sense for compound syncline. The broad shallow syncline of the Dakota sandstone falls in neither category. Objection might also be made to the use of

Jan 12, 1915

By P. R. Kalischer

IN the production of alloys by powder metallurgical processes it is often necessary or desirable to include one or more components that tend to form very stable oxides. Included in this group of metals are aluminum, manganese, magnesium, silicon, and a few others. In many cases it is not necessary for the sintered compact to have full density and the other physical characteristics of a cast alloy and in that event no undue precautions need be taken. If, however, it is required that the sintered part be entirely homogeneous, and have maximum density and physical properties, some method must be found to reduce the surface films of oxide, which are always present on the metals, and for the metals mentioned above this is always extremely difficult, if not impossible. Since the production of high-density alloys is of particular interest to powder metallurgists, some experiments were undertaken to devise methods of reducing the refractory oxides. For this work, alloys of iron, nickel, and aluminum were chosen because aluminum oxide is one of the most stable oxides and because these alloys in the right compositions form excellent permanent magnets. All of the pertinent properties of the magnets could be accurately and delicately measured by density measurements and magnetic tests of sufficient scope to give a complete demagnetization curve. From such a curve the maximum coercive force, residual magnetism, and energy products could be obtained and compared with the same properties for a cast material. Any lack of homogeneity, density, or solid diffusion would be immediately apparent as a decrease in the magnetic properties. NATURE AND REMOVAL OF SURFACE BARRIERS The early work of the present investigation was based upon published processes.* In the published information it was claimed that by intimately mixing iron, nickel, and iron-aluminum alloy (50 per cent Fe, 50 per cent Al) powders, compressing such a mixture into the desired shape and size, and then sintering (heating to a temperature below the melting point of the component metals) in hydrogen at 1200°C. or higher, a sound, homogeneous article could be made having the desired physical size, shape, and strength, and good magnetic characteristics. However, this early work showed clearly that something in the powder compress was inhibiting diffusion and the process was almost entirely unworkable. In the initial phase of the investigation samples of iron powder, nickel powder, and iron-aluminum alloy powder were pressed into separate bars and sintered in hydrogen. Both the iron and nickel powders sintered

Jan 1, 1941

By Harry Gard Knox, F. R. Harris

This paper covers some of the problems presented to the oil industry in the drilling of oil wells in the open waters of the Gulf of Mexico. The hazards, delays and relative costs of offshore drilling are reviewed and various forms of drilling platforms discussed. The requirements of the offshore drilling rig are summarized together with the principal items affecting the cost of construction. Sea waves and their size and characteristics as affecting offshore platforms are reviewed. Drilling platforms are classified as fixed, or fixed and floating. Fixed platforms of the conventional cofferdam and pile-supported type are discussed together with their good points and their limitations. The desirability is pointed out of eliminating as much offshore work as possible where operations are subjected to constant and expensive delay and substituting therefor the prefabrication of structures ashore or in sheltered waters. Marked economy will come with the standardization of offshore rigs aid special means of transporting them to the site. Several types of structure which are partly pile-supported and partly buoyancy-supported are discussed and their possibilities of future usefulness commented upon. General Considerations The predominant attribute of offshore drilling equipment is that it must be equal to the job in hand. We therefore give first thought to the matter of adequacy. In view of the probable depth of drilling, the investment involved and the per diem labor costs, it is assumed heavy modern drilling equipment will be employed. In order to usc such equipment efficiently, the working deck must be ample in size and strength and supported so as to be relatively free from motion and from green seas even in heavy storms. These requirements necessitate a high and rigid land-based support for the drilling rig and machinery with plenty of space for supplies, such as pipe, mud, water and fuel, with reserves for days when transportation from shore is impracticable. In offshore rigs the crew will be housed onboard in comfortable quarters, probably air conditioned and equipped with a galley and refrigerated food storage. An important consideration will be the ability to transfer stores and crew to and from the rig in all but the heaviest weather and the platforms must be protected from the impact of supply vessels when alongside. It will be essential to maintain continuous communication with shore by radio or cable, not forgetting the possibility of a helicopter landing space for the transfer of crew and light stores as well as a means of general communication. Whatever structure is constructed must be secure from storms of hurricane force and a safe place for the operating crew to work. If the well comes in, the drilling rig will presumably be removed and a small but rugged pile-supported platform will remain to carry the Christmas tree with safe working space around it. It will be protected from damage on all sides by buffer piles or dolphins. It is assumed that the flowing oil will be piped to storage tanks in the vicinity of the well. An individual tank for each well or a

Jan 1, 1949

By J. Orkiszewski

A method i.s presented which can accurately predict, with a precision of about 10 percent, two-phase pressure drops in flowing and gas-lift production wells over a wide range of well conditions. The method is an extension of the work done by Grifith and Wallis and was found to be superior to five other published methods. The precision of the method was verified when its predicted values were compared against 148 measured pressure drops. The unique features of this method over most others are that liquid holdup is derived from observed physical phenomena, the pressure gradient is related to the geometrical distribution of the liquid and gas phase (flow regimes), and the method provides a good analogy of what happens inside the pipe. It takes less than a second to obtain a prediction on the IBM 7044 computer. INTRODUCTION The problem of accurately predicting pressure drops in flowing or gas-lift wells has given rise to many specialized solutions for limited conditions, but not to any generally accepted one for broad conditions. The reason for these many solutions is that the two-phase flow is complex and difficult to analyze even for the limited conditions studied. Under some conditions, the gas moves at a much higher velocity than the liquid. As a result, the down-hole flowing density of the gas-liquid mixture is greater than the corresponding density, corrected for down-hole temperature and pressure, that would be calculated from the produced gas-liquid ratio. Also, the liquid's velocity along the pipe wall can vary appreciably over a short distance and result in a variable friction loss. Under other conditions, the liquid is almost completely entrained in the gas and has very little effect on the wall friction loss. The difference in velocity and the geometry of the two phases strongly influence pressure drop. These factors provide the basis for categorizing two-phase flow. The generally accepted categories (flow regimes) of two-phase flow are bubble, slug, (slug-annular) transition and annular-mist They are ideally depicted in Fig. 1 and briefly described as follows. RUBBLE FLOW (FIG. 1A) The pipe is almost completely filled with the liquid and the free-gas phase is small. The gas is present as small bubbles, randomly distributed, whose diameters also vary randomly. The bubbles move at different velocities depending upon their respective diameters. The liquid moves up the pipe at a fairly uniform velocity and, except for its density, the gas phase has little effect on the pressure gradient. SLUG FLOW (FIG. 1R) In this regime, the gas phase is more pronounced. Although the liquid phase is still continuous, the gas bubbler coalesce and form stable bubbles of approximately the rame size and shape which are nearly the diameter of the pipe. They are separated by slugs of liquid. The bubble velocity is greater than that of the liquid and can be predicted in relation to the velocity of the liquid slug." There is a film of liquid around the gas bubble. The liquid velocity is not constant—whereas the liquid slug always moves upward (in the direction of bulk flow); the liquid in the film may move upward but possibly at a lower velocity, or it may move downward. These varying liquid velocities will result not only in varying wall friction losses, but also in a "liquid holdup" which will influence flowing density. At higher flow velocities, liquid can even be entrained in the gas bubbles. Both the gas and liquid phases have significant effects on the pressure gradient. TRANSITION FLOW (FIG. 1C) The change from a continuous liquid phase to a continuous gas phase occurs in this region. The liquid slug between the bubbles virtually disappears, and a significant amount of liquid becomes entrained in the gas phase. Although the effects of the liquid are significant, the gas phase is more predominant.

By Ludwig Thomas, Klaus Detert

Klaus Detert and Ludwig Thomas (Westinghouse Electric Gorp.)— The results of C. Panseri and co-workers are quite important. The authors came to the same conclusions about the occurrence of zone formation in A1-Mg alloys as was outlined in previous papers.31'32 Because of the sensitivity of their measurements, it was shown that zone formation could also occur at a much lower range of mag- nesium content than previously observed.31, 33 The idea of strong interaction between magnesium atoms and vacancies, as stressed by the authors, so that all of the quenched-in vacancies are kept in solution at lower temperatures but anneal out completely at 150°C, is in disagreement with our results which clearly indicate that zone formation and annealing out of vacancies occur simultane-

Jan 1, 1964

By Eugene A. Stephenson

In November, 1932, Dr. Lacey, of the California Institute of Technology, presented before the American Petroleum Institute some of the results of his research under Project 371. The investigations described dealt particularly with changes in the physical properties of petroleum that result from the solution of natural gas therein. The solubility of Santa Fe Springs dry gas, containing 87 per cent methane, 8 per cent ethane and 5 per cent propane, had been determined in various crudes at 100' F., and 2000 lb. pressure per square inch as shown in Table 1 and Fig. 1 herewith. Originally the computations were made in terms of cubic feet per barrel, but' for a more uniform basis of comparison the results are also shown as cubic feet of gas2 per cubic foot of oil.

Jan 1, 1935

By Eric R. Jette

In order to control a chemical process by other than empirical, rule of thumb methods, two types of knowledge concerning the reactions involved must be available: (1) the thermodynamics of the reactions, and (2), by no means less important for efficient operation, the mechanisms and kinetics of the reactions. Information on the thermodynamic side enables the operator to decide upon initial and final conditions, whether heat must be added or removed from the system, whether the reactions proceed farthest in the desired direction at high pressure or low, etc. Knowledge of the mechanisms involves the determination of the individual steps by which an initial set of reactants, under given conditions, proceed to give the desired final products and kinetic studies upon which the mechanisms are based give the speed at which each of these reactions or steps take place. Thus thermodynamic studies of a reaction enable the operator to control the direction and extent to which the reaction can proceed, while kinetic studies enable him to control rates and thus the time efficiency of the operations. The thermodynamics set the limit to which the reacting system approaches; the kinetics tell how fast the system actually approaches this limit. The two types of information are complementary and not antagonistic even though in discussing the mechanism the introduction of thermodynamics is entirely needless and generally of no assistance, while in thermodynamic studies mechanism need not even be mentioned. Heterogeneous Reactions The thermodynamic side of metallurgical reactions has received much attention in the past; the mechanisms, relatively, very little. The main reason for our present lack of information on the mechanisms of these reactions lies in the fact that every one of importance is a heterogenkous reaction; i. e., the substances involved in the reaction exist in more than one phase, while, if we neglect the large amount of work which has been

Jan 1, 1931

By A. G. McGregor

During the past 5 years, five new copper-smelting plants have been built and put into operation in the State of Arizona. The monthly copper output from these plants averages from 5,000,000 to 18,000,000 lb. Previously, there never was as much activity in copper-smelting plant construction in the same length of time in all the rest of the world. Naturally, in this amount of work, some new problems were met and new features in plant design and equipment developed. Some of these features are described in this paper. Concentrate Hauling, Unloading and Sampling System (a) Concentrate Car The International Smelting Co. has provided at its plant at Miami specially designed cars for hauling the concentrates from the mills of the Inspiration Copper Co. and the Miami Copper Co. The car has a bottom that is readily made tight to hold flotation concentrates and is quickly and cheaply unloaded. Figs. 1, 2 and 3 show views and details of the car. The main feature of this car is the slot in the bottom throughout its length, which is closed by means of short planks that overlap like ship-lap as shown by Fig. 1. At one end of the car an iron gate operated by a screw and hand wheel is provided, which clamps or presses the planks together, making the bottom tight. A removable tapered plug rests vertically over this gate when the loading of the concentrates at the mill commences. A concentrate unloading pocket (Fig. 4), 180 ft.long, is provided at the smelting plant, which has a conveyor belt running throughout its length underneath the track. To unload a car, the vertical plug at the end of the car is lifted by means of a chain hoist which is supported by a trolley overhead. The gate at the end of the car is opened approximately 18 in. The removal of the plug leaves a hole down through the concentrates. The concentrates are poked through the hole from the top of the car until it is convenient for a man to stand on the bottom and draw one of the slats in the bottom toward the gate end of the car. The concentrates are then raked down with hoes on their natural angle of repose,

Jan 1, 1917

By K. A. Jackson

An analysis of the conditiom fm the dendrite-eutec-tic transition is presented which takes into account a temperature gradient. The composition and temperature in the liquid ahead of a eutectic interface growing at a particular velocity are used to determine whether dendrites can grow faster than the eutectic interface in the liquid which exists ahead of it. If the dendrites grow faster, then a mixed structure with dendrites growing ahead of the eutectic interface is expected. If the dendrites do not grow faster, then only eutectic will be present. The analysis is presented for Sn-Pb system, for which sufficient experimental data to make the analysis are available. The transition from eutectic to dendrites-plus-eutectic derived by this analysis is in good agreement with the recent experimental observations of Mollard and Flemings on Sn-Pb alloys. In alloys which grow with a lamellar eutectic structure, the lamellar structure can be grown over some range of compositions close to the eutectic composition. When the composition is too far from the eutectic composition, dendrites of one or another of the primary phases grow ahead of the eutectic interface, producing a microstructure consisting of "primary phase" interspersed with a lamellar eutectic. Hunt and Jackson' have recently predicted the range of compositions over which the eutectic phase should grow in Sn-Pb alloys, and the composition-growth rate dependence of the transition from eutectic to dendrites-plus-eutectic. This prediction was based on work on organic eutectics. The model on which the prediction was based assumed that there was no temperature gradient in the system, a condition approximately satisfied in the study of organic eutectics2-5 but not in the growth of metallic alloys. Mollard and Flemings6,7 have recently reported experimental results for Sn-Pb alloys in which they have located the transition from eutectic to eutectic-plus-dendritic growth. The experiments were performed using large temperature gradients (65 to 515 deg per cm), so that the assumption of zero gradient on which the predictions of Hunt and Jackson' were based does not apply. It is not surprising therefore that the predictions' were not born out by the experiments.7 In the present work, a modification of the model used by Hunt and Jackson is presented which takes into account the temperature gradient. The modified form of the theory predicts the transition from eutectic to eutectic-plus-dendritic growth in terms of the composition, growth rate, and temperature gradient. Good agreement with the experimental data of Mollard and Flemings7 is obtained. THE HUNT-JACKSON MODEL The model used by Hunt and Jackson' to predict the transition from eutectic to eutectic-plus-dendritic growth was based on the assumption that dendrites grow ahead of a eutectic interface only if they grow faster than the eutectic interface. Analytic expressions for the growth rate of dendrites and the eutectic in Sn-Pb alloys were obtained by fitting experimental data with equations whose form was indicated by theory.

Jan 1, 1969

By T. Saburi, C. M. Wayman

The massive and martensitic transformations in ß Cu-Ga alloys were studied by optical microscopy and by transmission electron microscopy and diffraction. These types of transformation are distinct and do not merge into one another. An internal fine structure due to stacking faults was found in both the massive phase (m) and the martensite, but the origin of the faults is believed to be different in each case. The faults in the martensite are due to the lattice invariant or "second" shear of the phenom-enological theory, while those in the are probably growth faults and deformation faults arising from the transformation volume change. Evidence is presented for ordering in the ß phase prior to transformation into martensite, and the crystal structures of and ß' and ßi martensites are discussed. THE results from some previous investigations1,2 have led to the suggestion that martensitic and massive transformations have certain common characteristics. It presently seems established that massive transformations like martensitic transformations are essentially diffusionless,1,2 but unlike martensitic transformations, when a new phase forms massively there is no shape change or surface relief.= If the massive-type transformation is crystallographically similar to martensitic transformations, one would expect a fine structure as a result of the lattice invariant shear4 which is a part of the transformation mechanism. The existence of such a fine structure (i.e., slip, twinning, or faulting), if any, can be verified by transmission electron microscopy, and thus the present investigation was undertaken to compare the internal structure of massively and martensitically formed phases in Cu-Ga alloys which were derived from a parent of the same composition. The transformation characteristics of ß Cu-Ga alloys were also studied. The bcc ß phase in the Cu-Ga system, Fig. 1, is stable above 616oc.' Depending upon the cooling rate, ß Cu-Ga alloys can undergo three different types of phase transformations. The ß phase of eutectoid composition (23.7 at. pct Ga) decomposes into the ? phase (hcp) and the phase (complex cubic) by means of a eutectoid reaction. When the cooling rate is increased so that the decomposition of 0 into [ and ? is suppressed, the ß phase transforms into a nonequilibrium hcp phase, herein denoted ?m by a process of very rapid growth called a "massive" transformation. At even faster quenching rates the massive transformation can be suppressed and the ß transforms martensitically. Massive transformations, apparently similar to those in the Cu-Ga system, have also been studied in the Cu-Zn2,6-8 and Ag-Cd systems.9 Definitive characteristics if the Massive Transformations in 0 Cu-Ga Alloys1 1) The most remarkable feature of the massive transformation in Cu-Ga is that there is no bulk composition change on transformation. According to Massalski,1 the resulting [, phase is a supersaturated extension of the equilibrium [ phase. The lattice parameters continue the trend exhibited

Jan 1, 1965

By Donald D. Smythe

This paper describes briefly the topography and geology of the region where the mica-bearing pegmatites are found and discusses prospecting, the quality of the mica, its preparation, and evaluation of the deposits. Muscovite mica occurs in a number of widely separated localities in Brazil, but production has come largely from deposits in the southeastern and eastern part of the State of Minas Gerais (Fig. I). There the deposits form a discontinuous zone, which starts at a point go km. north of the city of Rio de Janeiro and extends north for some 500 km., roughly parallel to the coast. A maximum width of 180 km. is reached along the Rio Doce. To the west in Minas Gerais, and extending east into the states of Espirito Santo and Rio de Janeiro, the mica zone proper is fringed by areas in which there are scattered occurrences of mica-bearing pegmatites. A few of these outlying deposits have produced commercial mica, but most of them are unimportant. To the southwest, in the State of Sao Paulo, there are a number of mines, which at one time produced a very considerable amount of sheet mica, largely as a byproduct of kaolin mining. These deposits, and a few others lying between them and the main productive areas to the northeast, appear to be the southwestern continuation of the strong Minas Gerais mica zone. In the vicinity of Conquista, just north of the Minas Gerais boundary in the State of Bahia, and still farther north, near Jacobina, there are several known mica deposits. Their location indicates that they may be the northern continuation of the main mica zone. The major part of Brazilian mica production has come from four areas within the mica zone proper; from north to south, Governador Valadares, Raul Soares, Espera Feliz, and Muriaé.. The first is go km. from north to south and reaches a maximum width of 180 km. The Raul Soares area extends 135 km. from northeast to southwest, and in places is 80 km. wide. The Espera Feliz area is 100 km. from north to south, and reaches a width of 35 km. The Muriai. area extends 150 km. from northeast to southwest and its width reaches 40 kilometers. Between the known productive areas, and in the areas directly to the southwest and to the north of them, little mica has been produced. These gaps, as well as certain irregularities in the outline of the mica zone itself, are to be ascribed either to lack of prospecting or to conditions preventing the discovery of mica, rather than to its nonexistence. Elsewhere in Brazil mica has been reported from eastern Goiaz, Ceará, Pernambuco, Rio Grande do Sul, Matto Grosso, and Amazonas. Production from these sources is negligible at present. Because of the inferior quality of the mica from the more accessible of these localities, and the operational difficulties occasioned by the remoteness of others, it is improbable that they will become important producers for some time to come.

Jan 1, 1948

By Donald D. Smythe

This paper describes briefly the topography and geology of the region where the mica-bearing pegmatites are found and discusses prospecting, the quality of the mica, its preparation, and evaluation of the deposits. Muscovite mica occurs in a number of widely separated localities in Brazil, but production has come largely from deposits in the southeastern and eastern part of the State of Minas Gerais (Fig. I). There the deposits form a discontinuous zone, which starts at a point go km. north of the city of Rio de Janeiro and extends north for some 500 km., roughly parallel to the coast. A maximum width of 180 km. is reached along the Rio Doce. To the west in Minas Gerais, and extending east into the states of Espirito Santo and Rio de Janeiro, the mica zone proper is fringed by areas in which there are scattered occurrences of mica-bearing pegmatites. A few of these outlying deposits have produced commercial mica, but most of them are unimportant. To the southwest, in the State of Sao Paulo, there are a number of mines, which at one time produced a very considerable amount of sheet mica, largely as a byproduct of kaolin mining. These deposits, and a few others lying between them and the main productive areas to the northeast, appear to be the southwestern continuation of the strong Minas Gerais mica zone. In the vicinity of Conquista, just north of the Minas Gerais boundary in the State of Bahia, and still farther north, near Jacobina, there are several known mica deposits. Their location indicates that they may be the northern continuation of the main mica zone. The major part of Brazilian mica production has come from four areas within the mica zone proper; from north to south, Governador Valadares, Raul Soares, Espera Feliz, and Muriaé.. The first is go km. from north to south and reaches a maximum width of 180 km. The Raul Soares area extends 135 km. from northeast to southwest, and in places is 80 km. wide. The Espera Feliz area is 100 km. from north to south, and reaches a width of 35 km. The Muriai. area extends 150 km. from northeast to southwest and its width reaches 40 kilometers. Between the known productive areas, and in the areas directly to the southwest and to the north of them, little mica has been produced. These gaps, as well as certain irregularities in the outline of the mica zone itself, are to be ascribed either to lack of prospecting or to conditions preventing the discovery of mica, rather than to its nonexistence. Elsewhere in Brazil mica has been reported from eastern Goiaz, Ceará, Pernambuco, Rio Grande do Sul, Matto Grosso, and Amazonas. Production from these sources is negligible at present. Because of the inferior quality of the mica from the more accessible of these localities, and the operational difficulties occasioned by the remoteness of others, it is improbable that they will become important producers for some time to come.

Jan 1, 1948

By J. N. Hummel

The methods of electrical prospecting, which employ contact electrodes to produce an electric field in the ground, furnish information concerning the constitution of the material beneath the surface, as indicated by the distortion of this artificially produced field and anomalies therein. To reveal the distortion of such field of known character, it is only necessary to measure qualitatively the direction of the field, using sensitive compensation methods. In such a case, the survey is relatively simple, and that is an important factor from a practical point of view. The distortion of the normal field thus determined permits an easy interpretation and gives approximate information as to the subsurface conditions, without the necessity of a thorough theoretical knowledge of the electrical field. The true field of application of the equipotential lines and search-coil methods, which are based on this principle of directional determination of the electrical field in the ground, is that of search for deposits of economic minerals for the mining industry, although they can also be used in solution of other problems; for example, in the determination of the strike of anisotropic beds. The distortion of the electric field as represented by the picture of equipotential lines or other measured curves is striking only when bodies having conductivities different from that of the country rock are embedded in the underground, or when the underground is anisotropic. It is obvious that methods based on such a simple principle and capable of solving directly many of the practical problems of mining geology have found a widespread application. However, these methods are unable to furnish any information as to the presence, depth and physical properties of layers in the underground, which have different conductivities, but are parallel, or only slightly inclined, to the surface. Where such conditions exist in the underground, the picture of the field

Jan 1, 1932

By J. D. Lubahn

The Bauschinger effect, or rounding of the corner of the stress-strain curve upon reloading, represents a temporary apparent softness that is more pronounced at large strains than small and for complete unloading than for partial unloading. Interrupted creep tests on copper exhibit a similar temporary softness (high creep rate) upon reloading. The fact that the strainwise dying-out time of these effects is the same in both tensile and creep tests shows that they are related. Thus, the term Bauschinger effect appears to embrace behavior following partial or complete unloading and reloading in addition to behavior following reversed loading. It is suggested that the term may properly apply also to certain creep behaviors following a small load decrement. INTERRUPTED tensile tests at low temperatures show1 a rounding of the corner of the stress-strain curve for reloading, which indicates a temporarily low deformation resistance. In the absence of recovery, the curve soon rises to the value that would have prevailed if the test had not been interrupted. The rounding of the reloading tensile curve has sometimes been referred to1 as the Bauschinger effect, although the term is more commonly applied to low deformation resistance in compression following tensile prestrain. The unusually broad usage of the term Bauschinger eflect in ref. 1 seems justified by the obvious interconnection of the various behaviors to which it has been applied.' In fact, the following discussion will indicate that still broader usage might be desirable. The Bauschinger effect is common at room temperature but apparently disappears at higher temperatures.2 Interrupted creep tests and tensile tests were made on certified OFHC copper (nongaseous impurities exclusive of silver were 0.004 pct), cold drawn 84 pct to ½ in. diam, and annealed at 600" (about 0.025 mm grains) or 850°C (about 0.2 mm grains). The tests were made in standard creep or tensile machines, using an O.S. Peters microformer-type extensometer or, for the small plastic strains, a special arrangement employing General Electric magnetic gage heads.' Interrupted creep tests at room temperature show3,4 an initial softness after reloading, manifested by an initial creep rate that is higher than that which would have prevailed if the test had not been interrupted. Fig. 1 shows some typical examples. This effect is apparently temporary (as is that in tensile tests): in four of the five tests shown, the log rate vs strain curve becomes parallel to an

Jan 1, 1956

By A. Karim, T. G. Langdon, C. Y. Cheng, J. E. Dorn

The effect of changes in temperature and stress on the creep behavior of Fe-4 pct Si was investigated over the temperature range from 650° to 1175K Over the temperature range of 799° to 110l°K, the shear strain rate, ?', obeys the relationship: where K is a constant, 7 the applied shear stress, G the shear modulus, g the free activation energy for diflusion, R the gas constant, and T the absolute temperature. The results strongly suggest that the creep in this alloy is controlled by a dislocation climb mechanism. In a recent investigation, Ishida, Cheng, and Dorn1 observed that the apparent activation energy for creep of a! Fe from 480" to 775°K corresponded to that for self-diffusion. Over the magnetic transformation range (775" to 1045"K), the apparent activation energy for creep increased steeply with increasing temperature in agreement with the known decrease in the free activation energy for self-diffusion. Passing through the Curie temperature, the apparent activation energy decreased abruptly following which it then increased mildly as the temperature further increased. Inasmuch as the apparent activation energy for creep of a! Fe below the Curie transformation range of temperatures appeared to decrease with increasing values of the stress, the data were analyzed in terms of a model based on the nonconservative motion of jogged screw dislocations. But since the observed creep rate was much higher than that which could be accounted for on the basis of usual models, the authors found it necessary to assume that pipe diffusion became significant over the lower temperature range. Furthermore, the abnormally high activation energy for creep above the Curie temperature was attributed to grain boundary migration which became prevalent in this temperature range. It was thought that a number of the interesting issues that arose in the creep of a Fe might be resolved by investigating the creep of Fe-4 pct Si alloy: This alloy has about the same Curie range and therefore should give creep results that closely parallel those for a Fe and in this way provide comparable data for analysis of creep mechanisms. Furthermore, it can be annealed at higher temperatures which could provide some stabilization against grain boundary migration. In addition, it might serve to illustrate the possible effects of short-range ordering on creep.

Jan 1, 1969

By B. B. Zavoico

After showing continued and very satisfactory progress until the close of 1931, the oil industry of the Soviet, Union experienced very great difficulties, and since 1932 has not only failed to complete its assigned quotas but has fallen farther and farther behind them, and in fact during 1932 and 1933 Russian production has been below production in 1931. In 1934 the total crude oil production of 169,200,000 bbl. exceeded that of the former peak year, 1931, when 156,100,000 bbl. were produced. The production during 1934 amounted to 78.65 per cent of the plan. The failure to complete the plan has been due to the inability of the oil trusts to develop new fields; the fields that have been producing since 1917 still account for between 75 to 80 per cent of total production. The failure of the Soviet Government to develop new fields has been due to unsatisfactory organization of the geological work, to the extremely slow drilling of wells and their exploitation, and to the very much delayed development of the few areas that have been discovered. The official overestimation of the proven reserves of the country has undoubtedly been an important factor in giving the Soviet industry too much confidence when actually such reserves have been small. The official Soviet estimate of proven reserves of Russia is now placed at 21,000,000,000, bbl., while in fact such reserves, if estimated on a conservative basis, do not exceed 4,200,000,000 bbl., as will be shown later in this review. The refinery branch of the industry also showed unsatisfactory results with a recovery of gasoline, both straight-run and cracked, of only some 16 per cent of the total runs to stills. In fact, the showing of the refineries has been so unsatisfactory that the exports of gasoline have been greatly curtailed from 1933 to 1934, dropping to 10,000,000 bbl. in 1934 from 12,230,000 bbl. in 1933. With the indicated increase in domestic demand, together with but slightly increased refining capacity, the volume of available gasoline for export probably will be reduced to about 6,000,000 bbl. during 1935. The geographic distribution of constructed refineries has been unsatisfactory and the crude oils from Baku had to be transported by tankers

Jan 1, 1935

By J. Norman Bulkley

Discussion of the paper of J. NORMAN BULKLEY, presented at the New York meeting, February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 355 to 373. GRAHAM BRIGHT, E.. Pittsburgh, Pa.-On p. 265 mention is made of a change from steam hoist to electric hoist. The arrangement mentioned, of using a geared motor, and having the gearing and counter-shaft in a separate, self-contained unit, and then connecting that to the hoist by means of a flexible coupling, is very good. Sometimes, however, it is necessary to change a geared hoist over to an electric hoist. 'In that case the motor could be either direct-connected to the countershaft or geared to the countershaft, making a double-reduction gearing. Trouble has been experienced with this method on account of the hoist not being designed for electric drive. It may be of a rather light construction which will not stand the forces obtained by steam operation, the maximum being determined by the steam pressure which can be obtained in the cylinder. With motors of hoisting types, torques, can be obtained, which are so far in excess of anything that the steam engine could give, that this sometimes results in disaster when a motor is applied to a hoist of that type. If the operator gets a little careless, he may overstrain the hoist, And cause damage, so that this question should be looked into when changing from a steam hoist to an electric hoist. The hoist should be rugged enough to stand the torques which may be attained by careless operation, in which case, instead of using a three-bearing motor, with a pinion between two of the bearings, it is much better to arrange for a two-bearing motor, arranging for a coupling through a flexible coupler. In another place trouble is mentioned as due to the vibration of a geared hoisting motor. That can be overcome by supplying a flexible coupling between the motor and the hoist proper. You will find, if a flexible coupling is furnished, that the motor troubles will largely disappear. K. A. PAULY (communication to the Secretary*), Schenectady, N. Y. -This paper is deserving of careful consideration by all interested in general electrical mining problems and the recommendations made should be given weight because of the author's long experience in dealing with various problems encountered from the beginning of mine electrification.

Jan 5, 1916

By R. A. Perry

DURING 1943, supplies of lead, like those of most base metals, moved from a position of scarcity to one of ample supply for all possible war requirements. The principal worry in the market, as 1944 began, was that surplus stocks might increase too rapidly to maintain price stability. The problem of postwar stockpiling had definitely entered the picture. The end of the year finds the lead industry having met all use demands, but not without depleting stocks to a critical low in spite of heavy importations. The principal reason for this dangerously reduced stock position is lack of adequate man power, which, without question, has become the lead industry's number one problem. This condition became obvious about the middle of the year, after Selective Service placed in effect orders that no deferments would be given employees under 26 years of age, and to a complacent attitude toward the industry assumed by the War Manpower Commission. It has become progressively worse since then. The WPB continued its policy, started during 1943, of easing restrictions on materials to be used for maintenance, repairs, and operating supplies. The policy of premium payments established by the Metals Reserve Co. was continued and, in spite of expressions to the contrary, has proved quite satisfactory. In short, the Government continued its program of stimulating the lead industry in practically all

Jan 1, 1945

By Richard W. Lodge

In the crucible-method of assaying ores for silver a certain amount of litharge is essential to supply sufficient lead to collect the precious metals. The object of this paper is to point out that the use of a large excess of' litharge in the assay of some ores will give results for silver that are uneven as well as low. So far as I know, however, an excess of litharge does not affect the results obtained in the crucible-assay of ores for gold. The main reasons for using, in the crucible-assay, much more litharge than is required to givc the necessary lead button are: 1, its action as a flux; 2, its action as a desulphur-izer; and 3, its action as an oxidizer, especially on metals like copper and nickel, whereby they are forced into the slag as oxides and thus prevented from passing into the lead button. Hence, by the use of much litharge in the crucible-assay more ore call often be taken than in the scorification-process, and a lead button obtained which call possibly be cupelled at once or after a single scorification. The method is specially advantageous with an ore carrying much copper or similar impurity and poor in silver, when the assayer does not wish to resort to a wet-analysis for the determination of the silver. It is well known that some ores give better results when assayed by the scorification-method, while others give better results by the crucible-method. For several years I have noticed that, when much litharge was used with certain sulphide and arsenical ores, the results were considerably lower than when the scarification-method was used. This fact was more forcibly brought out in connection with certain work carried on this year by Messrs. H. A. Frame and

Jan 1, 1908