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By E. Miller, J. M. Eldridge, K. L. Komarek

Aclivilies of magnesium in liquid Alg-Si alloys have been delermined between 5 and 60 at. pcl Si, close to the melling point of Mg2Si, by an improved isopieslic melhod. Silicon specinrens, held in alumina crucibles and graplrile conlainevs of special design, were healed in a letrlpevalure gvadient and equilibrated with mag-nesilcrrl rapor in a closed lilanium system. The ther-madynamic Junctions were calculated and compared with the thermodyuamic properties of the other three mg- Gvoup IVB systems. Lattice paramelers of three Mg2X compounds were measured. The bonding in the Mg2X compounds is largely covalent with small and uarying amounts of metallic and ionic conlvibutions. The Mg-Si phase diagram1 has one congruent melting compound, Mg2Si, of essentially stoichiometric composition, two eutectics, and very limited terminal solid solubilities. Little information is available on the thermodynamic properties of this system. The free energy of formation of Mg2Si has been determined by the Knudsen cell technique2 in the range 572" to 680oC, by the transportation method3 between 858" and 950oC, and by the electromotive-force method4 in the range 400o to 600°C. Kubaschewski and villa5 and caulfield6 have measured the heat of formation of Mg2Si. An electromotive-force study of magnesium-rich liquid alloys was recently published by Sryvalin el al.7 The present investigation was undertaken to complete a general survey of the thermodynamic properties of the homologous series of Mg-Group IVB systems, i.e., Mg-Pb,a9,Mg-Sn,10,11 mg-Ge,12and Mg-Si. An isopiestic technique, previously developed for similar measurements on liquid Mg-sn11 and Mg-Ge alloys,12 was modified for the Mg-Si system. Specimens of the nonvolatile component, silicon, were contained in dense alumina crucibles placed inside covered graphite crucibles which were heated in a temperature gradient in an evacuated and sealed titanium reaction tube and equilibrated with magnesium vapor of known vapor pressure. The alumina crucibles prevented contact between the highly corrosive liquid Mg-Si alloys and graphite. The graphite cruci- bles effectively preserved the high-temperature equilibrium composition of the liquid alloys containing highly volatile magnesium on termination of the experiments during the quench to room temperature. EXPERIMENTAL PROCEDURE Silicon of semiconductor-grade purity (E. I. du Pont de Nemours and Co., Brevard, N.C.) and 99.99+ pct Mg (Dominion Magnesium Ltd., Toronto, Canada) were used. Graphite crucibles with press-fitted lids were machined from high-density (1.92 g per cu cm) rods (Basic Carbon Corp., Sanborn, N.Y.) which had a maximum ash content of less than 0.04 pct. The alumina crucibles had a purity of 99.7+ pct (Triangle RR grade, Morganite, Inc., Long Island City, N.Y.). In preliminary runs the liquid alloys were contained in graphite crucibles following the exact procedure developed for the Mg-Ge system.'2 These runs failed due to appreciable reaction between the molten Mg-Si alloys and graphite, and the results have been discarded. The procedure was then modified and the Mg-Si alloys were subsequently held in alumina crucibles. For most of the runs alumina crucibles of known weight and approximately 6.3 mm ID, 12.5 mm height, 1.0 mm wall thickness were loaded with weighed amounts of silicon and encapsuled in tightly covered weighed graphite crucibles 5/16 in. ID, 2 in. helght, 3/32 in. wall thickness). The graphite crucibles were machined from rods which were 85 pct of the theoretical density. These crucibles were therefore sufficiently porous so as to permit magnesium vapor to effuse through the silicon under the experimental conditions of approximately 970O to 1220°C and 1 day equilibration time. However, negligible magnesium was lost from the crucible during the quench due to the slow effusion rate through the pores of the graphite. The inner alumina crucible prevented the liquid alloys from contacting the graphite, and the very tightly fitting graphite crucible lids served to retain any magnesium vaporizing from the alloys inside the crucibles during the quenching step.12 The loaded silicon-alumina-graphite cells were positioned, one above another, on a 16-in.-long titanium thermocouple well and tied securely to the titanium tube with thin molybdenum wires held in grooves around the circumference of the graphite crucibles. A thin (0.005-in.) molybdenum strip prevented contact between the graphite crucibles and the titanium. This assembly was lowered into a titanium reaction tube (la in. ID, 16 in. long, $ in. wall thickness) closed on one end which contained a 11/2-in.-long cylinder of magnesium at the bottom. The inner titanium thermocouple well was positioned eccentrically in the large tube because of the eccentric mounting of the cells on the well. Appropriate modifications of the titanium cap"'12 were made to join the inner and outer titanium

Jan 1, 1968

By David Turnbull

IN isothermal recrystallization processes, new crystals generally grow into the matrix until they impinge upon other new crystals or an external surface, at constant linear rates G. Before impingement the perceptible course of growth can be described by the equation: 1 = G(t-7) C1I where, G = dl/dt, 1 is a crystal dimension measured in a constant direction, t is the time, and 7, the nucleation period, is a positive intercept on the time axis. Fig. 1 is a schematic representation of I as a function of time for a recrystallizing grain. G is dependent upon temperature, driving energy (strain or surface energy), relative grain and boundary orientations, but is generally independent of time. The frequency of nucleation, fi, (time" volume") can be defined by the equation: N = 1/fV [2] where ? is the mean nucleation period and V is the volume of the specimen that has not recrystallized. The kinetics of primary and secondary recrystallization generally can be described satisfactorily in terms of the parameters N and G only.'-" After recrystallization is complete the average grain size 7 increases with time by "normal grain growth;" didt, the average rate of grain growth, is strongly time dependent and has not yet been precisely related to G for the motion of the individual grain boundaries constituting the system. It has been suggested4* " that the elementary act in grain boundary migration is closely related to the elementary act in grain boundary self-diffusion. Although the distance of atom movement in the two processes may be somewhat different, there is reason to expect that the activated states may be very similar, so that the free energy of activation for grain boundary migration should be of the same order of magnitude as for grain boundary self-diffusion. Therefore, it is desirable to develop a satisfactory basis for comparing data on self-diffusion and grain boundary migration and to make such comparisons where possible. Theory The formal theory of grain boundary migration rates is analogous to the theory for the rate of growth of crystals into supercooled liquids reviewed elsewhere 6-8. Boreliuss has shown that the latter theory describes, within the theoretical uncertainty, the growth of selenium crystals into supercooled liquid selenium. Motto and more recently Smolu-chowski" have derived expressions for the rate of boundary migration in recrystallization. The treatment to be presented is similar to Mott's excepting that the formalism of the absolute reaction rate theory will be used. The atomic mobility, M, in grain boundary migration is defined by: G = -M6p/6x where p is the chemical potential per atom and x is the coordinate measured in the direction of grain boundary movement. Let AF be the free energy difference per gram atom on the two sides of the boundary and k the thickness of the boundary. For RT>>AF the potential gradient across the boundary (6p/6x) is essentially linear and it follows that: SF/8x = - aF/N\ [4] where N is Avogadro's number. According to the Nernst-Einstein equation, M is related to a diffusion coefficient, Do, for matter transport in grain boundary migration by the equation: M = Da/kT [5] Substituting eqs 4 and 5 into eq 3 gives the basic relation between Do and G: G = DoaF/\RT [6] Do values may be calculated from experimental values of G from eq 6 and directly compared with the coefficient of self-diffusion within the crystal, DL, or the grain boundary self-diffusion coefficient D,. However, a more convenient, though equivalent, basis for comparing atomic mobility in grain boundary migration and self-diffusion is through the constants of the absolute reaction rate theory. According to this theory diffusion coefficients may be written:" D = k2(kT/h) exp [-AF,/RT] 171 aFa, the free energy of activation, is related to the measured energy of activation, Q, by the equation: AFA = Q - T aSx - RT [8] where aSa is the entropy of activation. Substituting eqs 8 and 7 into eq 6 gives: G = ek(kT/h) (aF/RT) exp [(AS,,)C/R] exp C-Qc/RTI C91 where the subscript G refers to boundary migration. The relationship between the driving free energy and the free energy of activation in boundary migration is indicated schematically in Fig. 2. Experience indicates that the variation of G with temperature can be described by: G= Go exp [- Qc/RT] [10] where Go and Qc are generally temperature independent over wide ranges of temperature. Comparison of eq 9 with eq 10 gives:

Jan 1, 1952

By D. R. Irving

Prior to this time, ample supplies of high grade mineral fillers, such as clay, have been available close to consuming centers. Now depletion of these accessible deposits, coupled with other factors such as increasing demand due to population expansion and standard of living rise, has made development of upgrading techniques attractive to producers. Various investigations being carried out by the U.S. Bureau of Mines are described. Factors making the development of improved methods for upgrading clays attractive to producers include: depletion of accessible deposits of high-grade clays, rising transportation and labor costs, more exacting specifications, and increased demand resulting from an expanding population and a constantly rising standard of living. Industry recognizes the need for upgrading presently unusable materials and has cooperated with the U.S. Bureau of Mines by providing samples from submarginal deposits and by evaluating the products that USBM upgrades. Following are some examples of recent clay beneficiation work by the Bureau. FIRE CLAY BENEFICIATION At the Rolla Metallurgical Center, Rolla, Mo., the Bureau is conducting research to develop technically and economically feasible mineral-dressing methods to remove quartz, pyrite, and other impurities from submarginal fire clays. The research has been spurred by the growing shortage of high-grade bur-ley, flint, and plastic clays in the Missouri fire-clay district resulting from increased consumption and the low rate of discovery of new deposits of adequate quality. There apparently is ample tonnage of submarginal flint and plastic clays to maintain the industry for many years if such material can be upgraded to commercial quality. Samples have been submitted to USBM by several major producers of refractories, including A. P. Green Fire Brick Co.; Harbison-Walker Refractories Co.; Mexico Refractories Div., Kaiser Aluminum and Chemical Corp.; and Wellsville Fire Brick Co. Research on some samples has been completed and still is in progress on others. The Bureau has found that specimens containing quartz or pyrite in grains coarser than the accompanying clay generally can be upgraded either with a gravity table or hydraulic cyclone. The improvement in quality is notable not only in chemical analysis but in an increase in pyrometric cone equivalent (PCE) of one or more cones. As an example, consider the results attained on a sandy flint—a fine-grained mixture of kaolin and halloysite with quartz and minor quantities of iron and manganese oxides. Chemical analysis was: 35.4 pct alumina (A12O3) and 47.8 pct silica (SiO2). The sample contained 9.2 pct free silica as quartz. The PCE was 33. The sample was crushed to -10-mesh, blunged with water, and then stage-ground to -48-mesh. The ground sample was tabled to yield a clay fraction containing 37.6 pct A12O3, and 45.3 pct SiO2 of which 2.4 pct was free silica. The PCE was 34. Recovery of alumina by this process was 73.6 pct. Concentration of the same clay in the hydraulic cyclone was even more effective in respect to quartz removal. The clay fraction analyzed 38.6 pct A12O3, 45.0 pct SiO2 of which 0.5 pct was free silica as quartz, and had a PCE of 34. Recovery of alumina was 71.9 pct. The hydraulic cyclone was also effective in reducing the pyrite content of a plastic clay which likewise was a mixture of kaolin and halloysite, plus some pyrite, quartz, and carbonaceous material. It analyzed 30.6 pct Al2O3, 52.3 pct SiO2, 2.3 pct Fe2O3, and 0.76 pct S. The sample was blunged and screened through 10-mesh to remove some coarse pyrite, then ground to -65-mesh and cycloned to remove most of the remainder. The final product recovered 81.8 pct of the alumina at a grade of 32.3 pct A12O3, 50.9 pct SiO2, 1.4 pct Fe2O3, and 0.1 pct S. The PCE was 32-1/2, compared with a PCE of 31-1/2 for the crude clay. The fine beneficiated clays, of course, must be pelletized and dried or fired to meet commercial acceptance. This operation has already been solved by industry. Little progress has been made on two remaining problems. One is that of fine-grained impurities, not separable by table or cyclone. Flotation is being investigated to solve this. Although fine pyrite is readily rejected, a satisfactory quartz-clay separation has not been attained. The second problem, a stubborn one, is that of alkali. Samples containing as much as 5 pct potas-

Jan 1, 1961

By John F. Elliott, John R. Rawling

The rate of reduction of silica to silicon by carbon at 1550° to 1700°C in iron blast-furnace type slag-metal systems has been investigated. In the tower portion of the temperature range oxygen transport in the metal boundary layer at the slag-tal interface is probably rate limiting. A second step, which apparently involves a chemical process in the slag at the slag-metal interface, appears to be rate limiting when the oxygen-transport limitation is avoided. Above 1650°C rate control of the reduction by carbon probably is mixed between the two steps. INVESTIGATIONS1.2 into the equilibrium distribution of silicon between graphite-saturated slags and metals typical of iron blast-furnace practice show that, under the experimental conditions specified, the reduction of silica to silicon is relatively slow compared with the rates of other slag-metal reactions under similar conditions. For this reason, the reduction of silica in blast-furnace slag-metal systems was considered to be an interesting subject for further study. Investigations of the kinetics of the reaction3-5 suggest that several possible steps may be rate controlling, and that the rate-controlling step depends not only on the physical state of the systems but also on the configuration of the apparatus. The main objects of the investigation reported here were to sug- gest plausible reaction paths for the reduction of silica under the experimental conditions chosen and to determine the step or steps which control the rate of reduction of silica. EXPERIMENTAL Two types of experiments involving the reduction of silica from the slag were carried out. In the first, the only reducing agent present was carbon (graphite), for which the over-all reaction is (SiO2) +2C(gr) —Si + 2Co(g) [l] The second type was a graphite-saturated ferro-silicon-iron concentration cell. In it silica in the slag could be reduced either by carbon according to Eq. [I], or by a reaction of electrochemical nature in which silicon was oxidized at the ferrosilicon-slag interface and silica was reduced at the slag-iron interface without the formation of CO. The two types of experiment are described below. Reduction of Silica with Carbon as the Only Available Reducing Agent. The reduction of silica was accomplished by allowing a liquid lime-alumina-silica slag and graphite-saturated iron to react in an induction-heated graphite crucible. The crucible was 2.25 in. diameter and 5 in. deep; it was fitted with a graphite stirrer which penetrated through the slag and into the metal, Fig. 1. The slag and metal charges weighed 350 g each. Pure carbon monoxide at a pressure of 1 atm was maintained above the melt by passing the purified gas through the crucible at a rate of 0.5 liter per min. The gas did not stir either the slag or metal. Temperature measurements were made by sighting an optical pyrometer down the hollow stirrer rod into a 1/4-in. hole drilled in the stirrer blade. The crucible temperature was maintained within *15"C of the required value by manual control of the power supply to the

Jan 1, 1965

By T. Lane Carter

(Canal Zone Meeting , October , 1910.) INTRODUCTION. IT is a curious fact that while in our Transactions there are papers dealing with mining-districts in all parts of the world, in Europe, Asia, Africa, and Australia, there is not one which describes the mining possibilities of Nicaragua; our near neighbor. To be most interested in distant objects, like the moon, .and to neglect what lies at our feet, appears to be a trait of human nature. The neglect of Nicaragua is not confined to the American Institute of Mining Engineers. In no other transactions am I :able to find papers dealing with mining in Nicaragua, some parts of which are as much in need of discovery and research as the North Pole.. I hope this paper will be the precursor of many others to be printed in our Transactions, dealing not only with the mining possibilities of Nicaragua, but with the whole of Central America, where there are vast areas awaiting skill and capital for their development. Much of this capital and skill should come from the United States in the future, although it is probable that European capitalists, when they appreciate fully the possibilities, will investigate more and more the mining-resources of Nicaragua and other Central American republics. Fig. 1 is a sketch-map of Nicaragua showing the principal mining-districts. II. HISTORY. Mining in Nicaragua did not begin yesterday. It was commenced by civilized man when the Spanish conquerors penetrated into the interior and forced the natives to procure the precious metal for them. It is strange that the Spaniards did not find more gold, and work on a scale as extensive as in Colombia and other parts of South America. Probably in Nicaragua the Indians covered up most of the rich prospects

Dec 1, 1910

By T. D. Tiemann

The extraction of iron oxide from several types of siliceous iron ore by digestion in sulfuric acid solutions was investigated in the temperature range from 80 to 258°F at concentrations from 10-60% H2SO4. Degree and rate of extraction were found to be critical with respect to both temperature and acid concentration, requiring temperatures in excess of 250° F and acid concentrations of 50% to effect 80-90% extraction of iron oxide in 60 min. Rate of extraction is directly related to surface area and apparently controlled by the rate of chemical reaction. The activation energy was found to be approximately 25,000 cal per g mol. Extraction characteristics of the several ores were found to be similar. The Department of Minerals and Metals Engineering at the University of Wisconsin conducts a continuing research program to develop processes for the utilization of low-grade iron ore deposits such as the nonmagnetic taconites of the Wisconsin Gogebic range. Methods under study include high-intensity magnetic and high-tension electrical concentration, flotation, direct reduction and chemical extraction. Concentration of a number of low-grade siliceous iron ores by the extraction of silica in sodium hydroxide solutions has been reported by the writer and others in the literature.1,2,3,4 Residual concentrates containing as much as 65% iron have been obtained from taconites containing less than 30%. Currently an alternative approach is under study, namely the dissolution of iron oxides from siliceous gangue by extraction in acid, with subsequent recovery of the iron from solution. Such a process for extracting iron oxide from the low-grade oclitic deposits of Alberta with hydrochloric acid was investigated and described by Gravenor, Govett and Rigg.5 The current investigation, which is entirely devoted to extraction with sulfuric acid, is the subject of this paper. In part, the objective of this research was to determine the possibility of leaching iron ores in situ with sulfuric acid. The investigation of a recovery method is left to later research. The ores investigated contained hematite (Fe2O3) as the principal iron-bearing mineral and minor amounts of goethite (Fe2O3 .H2O), magnetite (Fe3O4), and iron-bearing silicates. The gangue was essentially quartz occurring as single crystals and microcrystalline aggregates. Detailed description of the ores may be found in the literature.1,2,4,6 A comparison of the specific ores used in this investigation is shown in the partial analyses of Table I. EXPERIMENTAL METHODS All extractions were made at atmospheric pressure using beakers with a mechanical stirrer for those tests run below the boiling point, and Erlenmeyer flasks for those at the boiling point. A thermostatically controlled hot plate was used for heating, and this maintained the mean temperature within the solution to within ±3°F during extraction. The sample of ore for extraction was weighed to + 0.02 g. For tests below the boiling point, the sample was added to the beaker containing the sulfuric acid solution at the desired temperature. For the boiling-point tests, the sample was added to the Erlenmeyer flask followed by distilled water and the

Jan 1, 1968

By EDWARAD A. SIVEDENBORMG

REPORTS have been made at different times on the progress of water encroachment in the Frontier sands in the Salt. Creek oil field, Natrona county, Wyoming. All previous reports have, -however, been largely based on the position of water in the sands as determined by various physical tests. Subsequent information has been secured through a preliminary investigation of the porosity, grain size and degree of saturation of the Frontier sands. Also, a closer differentiation has been made between the waters encountered incident to the production of oil by means of chemical analysis. In view of the more recent developments there has been a need of a water encroachment map of the first Wall Creek based on a field survey and additional information acquired since the water encroachment map of the sand of 1926, by J. S. Ross and E. W. Henderson, petroleum engineers of the U. S. Geological Survey. The present report is confined to a study of the first Wall Creek sand and was written in connection with the preparation of the map, showing water encroachment in this sand. The first Wall Creek sand was the discovery sand in the field, the first well having been drilled in 1908. Its thickness averages 120 ft. and, varies between 90 and 160 ft. The sand is in the Colorado group of the Upper Cretaceous series and is further considered as a part of the Frontier formation found in other parts of Wyoming.

Jan 1, 1930

By Arthur Notman

TO present some idea of the magnitude of the gold-mining industry of Canada and the world, the records of 106 gold-mining companies currently paying dividends have been studied. Forty of these are in Canada, and 37 on the Rand in South Africa, these being all the straight gold-mining companies that paid dividends in the two areas in 1938. None of the base-metal companies that produce gold as a by- product, or even as a major fraction of the value of their total product, have beezl included. In addition, a group of 29 similar companies from Southern Rhodesia and the Gold Coast in Africa, India, Australia, Manchuria, Philippine Islands, the

Jan 1, 1939

By K. R. Janowski, A. B. Chase, E. J. Stofel

Ruby crystals of exceptional optical quality have been grown from fluxes composed of Bi2O3 + PbF2 or Bi2O3 + BiF3. Careful control of growth conditions was required to minimize the number of growth defects consisting primarily of dislocations, occluded flux, and growth twins. Slow growth rates coupled with the addition of small amounts of La2O3 as a flux dopant were helpful in producing nearly perfect crystals. Chromium concentrations up to 1 pet were incorporated into these crystals without adversely affecting their perfection. Crystals up to 10 mm in diameter having as few as one to ten dislocations per crystal were typical of those produced under optimum growth conditions. Under these same conditions the occlusions were eliminated, and growth twins were either eliminated or reduced to one to three twin boundaries per crystal. INTEREST in the nature of lattice imperfections produced during the growth of ruby crystals (Al2O3-corundum structure) has been stimulated recently by the need for ruby lasers of good optical uniformity. As a result, ruby crystals grown by the flame-fusion (Verneuil) process have been studied in detail and have been found to contain high densities of dislocations (106 to 107 dislocations per sq cm) and mosaic structures that impair their optical quality.'-3 Attempts to improve the quality of Verneuil-grown crystals by controlling the growth variables have not been entirely successful. On the other hand, rubies grown by the flux process have received little attention even though their more nearly equilibrium growth conditions suggest that they would have fewer growth defects. Nelson and Remeika have shown recently that small flux-grown rubies can indeed be made into very low-loss lasers. However, they did not report information on crystalline imperfections in these crystals.4 Stephens and Alford have reported briefly on defects found in a flux-grown corundum crystal but they neither described these defects in detail nor related them to the method of growth.5 The present investigation was undertaken to establish the relationship between growth conditions and crystalline perfection of flux-grown rubies, sapphires, and other crystals of the corundum family. EXPERIMENTAL PROCEDURE The corundum crystals used in this study were grown by slowly cooling solutions of A12O3 in molten-salt solvents of PbO + PbF2, Bi2O3 + PbF2 or Bi2O3 + BiF3. The materials employed were Linde A (a Al2O3 powder) with reagent-grade chemicals as solvents. Some of the solutions also contained small additions (1 pet or less) of one or more of the transition metal elements chromium, manganese, iron, and titanium as crystal dopants. La2O3 was added to some of the solutions to alter the growth habit of the crystals. The La2O3 promoted the occurrence of growth facets parallel to (0112) and {1011} planes, where the indexing system is the morphological system described in detail by Kron-berg6 and used throughout this paper. The melts from which the crystals were grown were prepared by mechanically mixing the various constituents and placing them in platinum crucibles. The covered 50- and 100-ml platinum crucibles were heated in muffle furnaces at 1250°C for short periods of time (1 to 4 hr) and then program-cooled at either 2° or 4°C per hr to 1000°C. At this lower

Jan 1, 1965

By Robert L. Hoss

The application of Muskat's differential equations for predicting the performance of a solution gas-drive reservoir to the Fullerton field indicates that a recovery may be expected of 14,030 bbl per acre under primary depletion, and 15,910 and I7,190 bbl per acre, respectively, under the two pressure-maintenance programs analyzed. In this analysis it is assumed that fluid properties are the same throughout the reservoir, that the core data used are typical of the Clear Fork limestone in the locality, and that injected gas is completely diffused through the pay zones. The economic study of the three recovery programs considered indicates that the one in which 60 pct of the produced gas is returned to the formation is the most profitable. Introduction The purpose of this paper is to consider the effect of pressure maintenance by gas injection on the ultimate recovery of oil from a solution gas-drive reservoir. This prediction of reservoir behavior is the result of calculations based on the equations presented by M. Muskat in the Journal of Applied Physics, March 1945. Reservoir The reservoir analyzed is the Fullerton field in Andrews County, West Texas. It is situated on a broad anticlinal structure with approximately 330 ft of closure, and extends approximately eight miles north and south and five miles east and west. The areal extent is taken as 16,642 acres. The producing horizon is the Lower Clear Fork limestone of Permian age, occurring at depths from 6650 to 7350 ft. It is divided into four zones. For the purposes of this study, the fluid characteristics in all zones are assumed to be the same. Therefore an equivalent zone is assumed of thickness equal to the sum of the thicknesses of the four zones, or an average of 216 ft. The reservoir contains 3,586,991 acre feet of producing limestone, with an initial volume of stock tank oil in place of 918,-403,100 bbl. The average connate water saturation is 24.0 pct. The permeability ranges from 6.7 md. to 12.6 md., and the porosity ranges from 7.7 pct to 11.4 pct, except for occasional cavernous streaks. Based on these values, the limestone may be considered intergranu1ar.l Production histories and material-balance studies have indicated that the driving mechanism is solution gas. Water levels have been established. Theory It is possible to express mathematically the change in residual oil saturation with pressure decline in a solution gas-drive reservoir as being equal to the change in the physical properties of the fluids present in the reservoir as this pressure decline occurs. Essentially these equations, in differential form as presented by M. Muskat,2 express quantitatively the instantaneous net effect

Jan 1, 1948

By Robert L. Hoss

The application of Muskat's differential equations for predicting the performance of a solution gas-drive reservoir to the Fullerton field indicates that a recovery may be expected of 14,030 bbl per acre under primary depletion, and 15,910 and I7,190 bbl per acre, respectively, under the two pressure-maintenance programs analyzed. In this analysis it is assumed that fluid properties are the same throughout the reservoir, that the core data used are typical of the Clear Fork limestone in the locality, and that injected gas is completely diffused through the pay zones. The economic study of the three recovery programs considered indicates that the one in which 60 pct of the produced gas is returned to the formation is the most profitable. Introduction The purpose of this paper is to consider the effect of pressure maintenance by gas injection on the ultimate recovery of oil from a solution gas-drive reservoir. This prediction of reservoir behavior is the result of calculations based on the equations presented by M. Muskat in the Journal of Applied Physics, March 1945. Reservoir The reservoir analyzed is the Fullerton field in Andrews County, West Texas. It is situated on a broad anticlinal structure with approximately 330 ft of closure, and extends approximately eight miles north and south and five miles east and west. The areal extent is taken as 16,642 acres. The producing horizon is the Lower Clear Fork limestone of Permian age, occurring at depths from 6650 to 7350 ft. It is divided into four zones. For the purposes of this study, the fluid characteristics in all zones are assumed to be the same. Therefore an equivalent zone is assumed of thickness equal to the sum of the thicknesses of the four zones, or an average of 216 ft. The reservoir contains 3,586,991 acre feet of producing limestone, with an initial volume of stock tank oil in place of 918,-403,100 bbl. The average connate water saturation is 24.0 pct. The permeability ranges from 6.7 md. to 12.6 md., and the porosity ranges from 7.7 pct to 11.4 pct, except for occasional cavernous streaks. Based on these values, the limestone may be considered intergranu1ar.l Production histories and material-balance studies have indicated that the driving mechanism is solution gas. Water levels have been established. Theory It is possible to express mathematically the change in residual oil saturation with pressure decline in a solution gas-drive reservoir as being equal to the change in the physical properties of the fluids present in the reservoir as this pressure decline occurs. Essentially these equations, in differential form as presented by M. Muskat,2 express quantitatively the instantaneous net effect

Jan 1, 1948

By N. Christensen, B. Augland, T. H. Johansen

Samples of an Fe-Nb alloy were brought to equilibriurtr with hydrogen-methane mixtures in the temperature range from 950° to 1050°C, and subsequently analyzed on their carbon contents. The solubility pvoduct L = [%Nb] [%C] may be represented by the equation Approximate solubilities indirectly assessed through hardness measurements have been included from a previous report. These data are shown to be in a fair agreement with the present solubility measurements. IN an investigation based on hardness measurements by de Kazinczy, Ms, and pachleitnerl the molal heat of solution of NbC was estimated to 11.5 kcal per mole. This value was considered rather small, and an investigation using a similar technique was carried out. The results indicated a heat of solution about 35 kcal per mole.2 At this stage it was decided to determine the solubility under conditions of true equilibrium . During the course of this work a similar investigation was published by Smith. 3 His heat of solution, 41.6 kcal per mole, is not very different from the value resulting from the present work (42.5 kcal per mole). Our solubility product, on the other hand, is at considerable variance with that reported by Smith. Possible reasons for these differences are discussed below. Mori, Tokizane, and saheki 7 have studied the behavior of niobium in commercial steels, with special attention to the formation of niobium carbide, nitride, and sulfide. Assuming a carbide composition Nbco.87 based on X-ray diffraction and chemical analysis of residues extracted from Fe-Nb-C-S alloys, the molal heat of solution of niobium carbide was estimated to 35.2 kcal per mole. MATERIALS AND EQUIPMENT The chemical analysis of the materials is given in Table I. Electrolytic iron* was used in the preparation of

Jan 1, 1968

By R. P. Smith

IN 1937 the employees of the Hollinger Consolidated Gold Mines Ltd., at Timmins, Ont., Canada, approached organized medicine for a plan to provide themselves and their families with a complete medical service including hospitalization. This approach was made because of two conditions: (1) the necessity for some organization whereby contributions could be made in instalments to offset the sudden and large expense connected with illness for which the average employee is not prepared, and (2) the need for a more cohesive quality of service to replace a contract practice then in vogue, which did not take care of the employee's family or dependents. In different parts of the United States and Canada similar plans were in force, not only for employed groups but for numbers of people in circumscribed areas. In Europe different countries had adopted various forms of health insurance plans. It then was no surprise that these employees as a group should ask for some similar plan. With the cooperation of the management, a plan was instituted. The plan has one object only-the provision of medical services, including the accessory services such as hospitalization, X-rays, nursing, and necessary drugs and medicines. It is not concerned with cash benefits, sickness and accident payments, or any form of monetary return as the result of illness, but is simply an organization to provide medical services and pay for them from a central fund. It is a nonprofit organization and the only shareholders are the employees and their families who contribute and who in turn receive services. The Hollinger plan is limited to the employees of the Hollinger mine, who live in Timmins and the immediate vicinity. At first, the membership was voluntary. In the third year, it was made a condition of employment, with the proviso that at the end of any Association financial year an employee may withdraw if he wishes to do so. After withdrawal, he cannot again become a member until the end of the next Association year, and then only by the payment of the back dues. This step was taken to ensure continuity, and to prevent employees from withdrawing when well and reentering when faced with impending illness or operations. The employee himself is subject to medical examination on application for employment, and if accepted is subject to further examination by a specialist in chest diseases under the Workmen's Compensation Board of Ontario. Thus it is possible to exclude those who have heart disease, tuberculosis, or other disabling conditions when first employed. Wives and families of employees are not subject to medical examination but other dependents of an employee-mother, father, or other relative-who are declared by the employee to be wholly dependent upon him must be examined. The employee

Jan 1, 1944

By E. C. Robertson

Observations of faults in mines, at outcrops, and in the laboratory lead to the conclusion that the displacement d of a fault increases irregularly but monotonically with the thickness t of its associated fault gouge and breccia, not including adjacent undisplaced jointed rock. The general trend of data points has a slope d/t of about 100. (The correlation coefficient of a logarithmic regression line is r = 0.94.) The rather wide scatter of the points can be accounted for by inaccuracies in measurement of d and t, and by variation in the conditions at faulting of confining pressure, rock type, water pressure, and deformation history. Limestone is an exception to the relation. Until the data can be corrected and refined, the relation should be used only qualitatively for estimating displacement of ore bodies in mines. The suggested relation is based on observations of 48 steeply- dipping normal and reverse faults and nine small flat-dipping thrust faults, with displacement less than 5 km (3 miles). It does not apply to large strike-slip and low-angle overthrust faults because their large displacements are poorly determined and their breccia thicknesses are widely variable.

Jan 1, 1984

By AIME AIME

QUALITY and size do not ordinarily go hand in hand, but there is good evidence that both these attributes reached a new peak at the Annual Meeting of the Institute in New York just concluded. Certainly, the total attendance of 2500 was far above any yet attained, as might be expected with the recent rapid growth of Institute member- ship. General comment indicates that the quality of the papers also was notable, though not measurable by so definite a yardstick as attendance. During the meeting 49 technical sessions were held, at which more than 250 formal papers were presented. In addition, there were some thirty special meetings of committees, Divisions, and other Institute groups. In reporting the Annual Meeting eleven years ago the statement was made that "unless the Engineering Societies should build for themselves a new building it is probable that no meeting can be larger," and "the fifth floor, where a buffet lunch is served each day, has reached its full capacity and it seems quite evident that any future development of Institute meetings must be along the lines of quality, not size." Unfortunately the angel to succeed Andrew Carnegie, who financed the building of the present home of the Institute 35 years ago, has not yet ' appeared. Even if some one would merely build another elevator or two in the present building it would help. Fortunately, the modern auditorium of the American Radiator & Standard

Jan 1, 1940

By Byoung Whie Lee

In order to investigate the change in surface energy as a function of cold work ad environment, the contact angles between a liquid and the surface of elec-tropolislzed aluminum with various degrees of cold work were measured. Specinlens cut from aluminum rod (99.99 pct Al) were annealed at 600°C for 24 hr and then cold compressed parallel to the drawing di-rectzon of the rod in increments of approximately 10 pcl from 0 to 70 pct. The sections, taken transversely to the drawing direction, were mechanically and electro chemically polished. Contact angles between the sessile drop of distilled water, glycerin, and glycol and the specimen surface were measured optically. The differences in interfacial energy were calculated from the contact angle data. The effects of chemical washing and surface roughness of the specimen on the contact angle were also studied. The liquid contact angle was a linear function of the degree of cold working (D) ad changed markedly with differed liquids. THE plastic deformation of polycrystalline metals induces a preferred orientation in crystal structure. A preferred orientation changes the atomic density of a metal surface. This change in surface atomic density brings about the changes in surface interactions of the metals."' Also, the plastic deformation of metals raises the internal energy by increasing the stored energy.' Consequently, the total Helmholtz free energy of the metal increases and, in turn, the surface free energy of the metal. In order to study the effect of plastic deformation on solid surface phenomena, the liquid contact angle of a sessile drop made on cold compressed and elec-trochemically polished aluminum was measured. The preferred orientation in aluminum, due to uniaxial compression, is known to be [110] direction parallel to the compression axis. However, this description is only a first approximation of a rather complex orientation. In actuality, half the crystallites are more than 10 deg from this orientation, regardless of the amount of compression." For randomly oriented fcc crystals, the average surface atomic density can be calculated as follows: The number of atoms in a unit volume is 4/a3, where a is a lattice constant. Hence, the number of atoms per unit surface area is about (4/a3)2/3 = 2.52/a2 However, when the preferred orientation took place along [110] direction, the surface atomic density is as follows: The area of (110) plane of a unit cell, considering ridges and valleys, is BYOUNG WHlE LEE, Member AIME, is Research Metallurgist, Atomic Energy Research Institute of the Republic of Korea, Seoul, Korea. Manuscript submitted May 29, 1968. IMD 2 x J2- a x Ga = 6a2 Since this plane contains 4 atoms, the surface atomic density is 4i6a2 = 2.3/a2 Upon changing from random to preferred orientations, the surface atomic density decreases about 10 pct. The increase in the stored energy and the change in surface atomic density due to plastic deformation would certainly alter the surface tension of a metal. EXPERIMENT High purity aluminum rod of 6-mm diam (99.99 pct Al, obtained from Johnson, Matthey & Co., Ltd, London, England) was cut into sections approximately 1 cm long. The transverse cross section was mechanically polished. Then, the specimens were annealed in air at 600°C for 24 hr. Thus, eight annealed specimens were uniaxially compressed at room temperature from 0 to 70 pct of cold working with an increment of 10 pct. The extent of cold working was determined by the percentage of reduction in axial length to the original length. The specimens were further polished mechanically and, then, electrochemically with the Modern Battelle Type 1 electropolishing solution with a current density of 0.3 to 0.4 amp per sq cm and an electrode potential of 8 to 12 v at the solution temperature of 78" to 82°C for approxirr~ately 5 min. The Modern Whlte Diffusing Screen \t/ --------------- re Goniometer for Mercury Lamp ^-^ Sessile Drop ¦=• Condenser c=> Microscope l_*~_i bJ Mlcromster Filer with Protmcter Fig. 1—Schematic diagram of apparatus set-up for liquid contact angle measurement.

Jan 1, 1970

By E. I. Larsen, F. R. Hensel

According to statements by Guertler1 Smith and Hamilton were the first to study the copper-titanium alloys, but owing to the presence of large amounts of impurities their data are inconclusive. M. A. Hunter and I. W. Bacon later investigated the electrical conductivity and the temperature coefficients at room temperature. The present writers reported their results2 in November, 1930. Recently Kroll published data on copper-titanium alloys3 which agree closely with those obtained by the authors. Material Tested The titanium used was in the form of square sintered rods, the analysis of which runs as follows: titanium, 95.4 per cent; silicon, 0.7; iron,l.8; aluminum, 1.4; copper, 0.1; manganese, 0.05. The ingots were prepared in a high-frequency induction furnace in air atmosphere. Their analyses are given in Table 1. Up to 5 per cent titanium the alloys could be forged. Above that amount they were red short and broke up easily. Owing to their rapid absorption of nitrogen and oxygen from the air, the alloys with the higher amounts of titanium tend to form surface films which greatly increase the casting difficulties, especially when small masses of metal are handled. It was, however, possible to prepare sound ingots up to 25 per cent titanium. Thermal and X-ray Investigation The cooling curves of some of the alloys are plotted in Fig. 1, and R tentative diagram constructed from these data is given in Fig. 2. From this it is evident that the solid solubility of copper for titanium is approxi-mately 4 to 5 weight per cent titanium at 878" C., which is the eutectic temperature. The melting point of copper is lowered gradually by adding

Jan 1, 1932

By AIME AIME

EVERYONE enjoyed the coal meeting and found it profitable. At least your correspondent did, and those to whom he talked. Close to a hundred were there. The Coronado proved an excellent headquarters hotel, though it is two miles or more from the business district of St. Louis; its Crystal Room was suitable for the technical sessions; its Lounge adequate for registration and informal chats; its Club Caprice made an artistic setting for the informal banquet; and its Coal Hole in the basement presumably served other needs-unfortunately we passed up an invitation to find out, and never got another. To be sure, the first day of the meeting (Monday, Oct. 28) was a drizzly one, but that only served to keep people inside where they belonged. Believe it or not, the first technical session was only five minutes late in getting tinder way, with H. N. Eavenson's words of welcome. M. M. Leighton then took over the conduct of the meeting, and invited Eugene McAuliffe to read his paper on how much coal the railroads are likely to use in the future. E. G. Bailey then presented some written discussion; among other things he wondered about the success of stokers on locomotives, and whether or not the burning of coal in locomotives could not he made a cleaner operation. Mr. McAuliffe pointed out that railroads are built to haul coal rather than to burn it. Maximum firebox efficiency is often subordinated to the traffic situation. Powdered-coal firing has not been a success because of limited firebox space. Stokers have resulted in economies indirectly, because large locomotives cannot he hand-fired and stokers thus make them possible. Nowadays it is not so important to do away with smoke, cinders, and soot, because most trains are sealed up and air-conditioned.

Jan 1, 1935

By J. Alfred Berger, O. M. Katz

Selected samples of hydrided Zr-Hf alloys were rapidly quenched to voom temperature and exrtrnined metallographically, by X-ray diffraction, and through micro hardness studies to confirm high-temperutuve data Confirming experiments sllowed that there were five phases in this Lernary system: 1) hextrgonal with lattice parameters similar to that of the initia1 Zr-Hf alloy but slightly enlarged due to dissolved hydrogen; 2) fee with properties of a brittle, intermediate, hydride compound; 3) fct with c/a crvoltnd 1.07 and which appeared as a neetilelike precipitale; 4) hexagonal, designated ?, with c/a ratio of 2.37; and 5) orthorhombic, designated X, with a = 4.67, b = 4.49, and c = 5.093 and whose tnicro-st?ruct~ival nppetrl-nnce depcncled o/i, heat lvecrt~r~ent. The tetragonrrl phase never crppeal-erl witkorct the cubic hydricle. Abpecrrtrnce of 0 and A also tlependet on the hafnium content of the zirconium. A previous paper' on the Zr-Hf-H system described the thermochemical data obtained with a high-vacuum, high-sensitivity mirrogravimetric apparatus. This data presented a fairly complete picture of the phase relationships at elevated temperatures. However, it could not establish the actual crystal structures, lattice parameters, or metallographic disposition of the hydride phases. The present complementary study utilizes X-ray powder patterns along with light and electron microscopy to characterize completely the five hydrided phases found in Zr-Hf-H alloys quenched to room temperature. Crystallographic features of the zr-Hf,2,4 zr-H,5-7 and Hf-H8 systems have been summarized in Table I. Designations of a, ß, and ? were retained in the Zr-Hf-H system for the phase regions through which the pressure-composition isotherms always sloped. However, it was not firmly agreed that these were single-phase regions.' In fact, the region designated y always contained a cubic as well as a tetragonal phase after quenching to -196°C. MATERIALS Preparation of the high-purity Zr-Hf alloys has been described.' The four zirconium alloys which were hydrided contained 37 wt pct Hf (23 at. pct), 51 wt pct Hf (37 at. pct), 73 wt pct Hf (58 at. pct), and 91 wt pct Hf (82 at. pct), respectively. These were designated B-2, B-4, B-6, and B-8. Photomicrographs of the initial alloys showed the material to be quite clean as would be expected from the precautions exercised in producing them. However, there were a number of annealing twins but no other subgrain structure. In addition to the four original alloys, fifteen hydrided samples were observed at room temperature. Hydrogen compositions are given at the top of Tables I1 to V. APPARATUS The phases present at elevated temperatures were studied by quenching hydrided samples to room temperature by two different methods, both under vacuum: 1) fast cooling of the sample tubes of the microgravimetric apparatus1'9 with flowing air and 2) rapid quenching into liquid nitrogen. The cooling rate for 1) was 750° to 250°C in 30 sec. Since the microbalance chamber was not designed to permit very rapid cooling of a hydride sample, all liquid-nitrogen quenching was done in an auxiliary experiment. The auxiliary quenching apparatus consisted of a small-bore, high-temperature furnace, a sealed SiO2 tube containing the sample, and a dewar quenching flask filled with liquid nitrogen. The hydrided sample, previously quenched in the microgravimetric reaction chamber, was placed in a platinum boat in a vacuum-degassed SiO2 tube. A zirconium wire getter and degassed SiO2 rod, to reduce the internal volume, were also in the tube. After sealing the tube under vacuum the zirconium getter was heated to absorb the last traces of gas. Only the sample was heated at the reaction temperature for the desired length of time, and then the tube dropped through the opposite end of the furnace into the dewar. A quenching rate of 200" to 400° C per sec was estimated. Analyses of samples after the auxiliary experiment also showed practically no increase in oxygen or nitrogen content from heating in the SiO2 tube. All of the samples were examined at room temperature by the X-ray powder method. The majority of the powder patterns were obtained with double nickel-filtered CuKa radiation after 8- and 16-hr exposures in an 11.48-cm-diam camera. Cobalt and chromium radiation were also used to spread out the high d value end of the Pattern. Such patterns readily identified the minor phases. NO oxide or nitride lines were found. Where sharp back-reflection lines existed it was possible to reduce the

Jan 1, 1965

By J. C. Williams, M. J. Blackburn

MANY aspects of the formation of the metastable w phase in titanium-transition metal alloys have been described in several recent papers.1-4 These papers have reviewed earlier work on the w phase and have further defined most of the important features related to the formation of this phase, e.g-., its crystal structure, composition, and morphology. There are, however, several important points regarding formation of the w phase in titanium alloys which have been described in less detail. Two of these are the relationship between lattice misfit and w phase morphology and the influence of lattice misfit on the mode of formation of the equilibrium a phase. In this communi- cation we will present transmission electron microscopy results relevant to these two points. The alloys used in this study were prepared by non-consumable electrode arc melting, each 30-g button being remelted a minimum of twelve times. The alloy compositions we have studied are listed in Table I. Thin foils were prepared using standard techniques described elsewhere. Two distinct c' phase morphologies have been reported in earlier papers. The phase is ellipsoidal in the Ti-Mo3 and Ti-Nbl system and cubical in the Ti-V3 system. Results of the present study show that the w phase is also cubical in Ti-Mn, Ti-Fe, and Ti-Cr alloys as illustrated in Fig. l(b) to (d). Fig. l(a) shows the ellipsoidal morphology in Ti-MO3 for comparison purposes. It was suggested in an earlier paper3 that the w phase morphology may be controlled by the lat-

Jan 1, 1970