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By L. W. Saperstein, D. Yeung, L. B. Phelps

Introduction The success of preventive methods for the mitigation of coal mine drainage formation will require a marriage of the minimization of initial coal mine drainage formation, the minimization of toxic fluid formation after toxic material disposal, the minimization of the mobilization and transpor¬tation of formed toxic fluids, and the maximization of the rate of diultion and attenuation of the formed toxic fluids. This paper contributes to the understanding of factors af¬fecting mobilization and dilution and attenuation of formed toxic fluids. When water containing a salt content different from in situ pore water in the soil is passed through a body of soil, the concentration of salts in the outflow will gradually change composition in a manner that depends on the kinds of hydraulic processes that occur in the soil. These processes are molecular diffusion, lateral dispersion, longitudinal dispersion, chemical reactions or exchange, physical adsorp¬tion, and biological retardation. This note considers only the first three processes. These three microscopic processes can be analyzed statistically on a probability basis. Such results, confirmed experimentally, indicate that a tracer introduced instantaneously as a point source will tend to form a Gaussian normal distribution as it moves downstream (Todd, 1964). Dilution During Flow The closed-form soltuion for pulse or instantaneous injec¬tion of a tracer during confined flow in a homogeneous porous medium shows that the maximum tracer concen¬tration at a point in space, x, after the time interval, t*, is given by [ ] where Aa is the effective flow cross-sectional area; A is the column cross-sectional area; a is soil porosity; M is mass of the injected tracer; C is concentration of the tracer in the permeating fluid and is a function of x and t*; D is the longitudinal dispersion coefficient; and va is the interstitial fluid velocity (Klotz and Moser, 1974). Therefore, the following conclusion can be made: • For a medium with a constant longitudinal dispersion coefficient, D, a constant soil porosity, a, a constant cross¬sectional area, A, and a fixed mass of injected tracer, M, Cmax will decrease as the time of peak outflow concen¬tration t* increases. • For a medium with a constant longitudinal dispersion coefficient, D, a constant soil porosity, a, a constant cross¬sectional area, A, a fixed mass of injected tracer, M, and a constant interstitial fluid velocity, va Cmax will decrease as the distance of travel, x, increases. • For a medium of constant cross sectional area, A, con¬stant soil porosity, a, a constant mass of injected tracer, M, and a fixed distance of travel, x, Cmax will decrease as D/va increases. Klotz and Moser (1974) concluded that D is about proportional to no.3 where r) is the kinematic viscosity; D is about proportional to a-3 where a is soil porosity; D in¬creases with increasing grain size; D increases as grains become less spherical; D increases with greater grain rough¬ness and angularity; D increases with increasing uniformity coefficient; and D is significantly affected by grain size and uniformity coefficient. The remaining parameters are not significant. Numerical Simulation Studies Numerical simulation studies were used to investigate the nature of flow and the optimum length of a toxic package within a saturated porous medium of fixed dimensions and configuration (Fig. 1). The width and position of the package was maintained constant (Phelps et al., 1981). Results indicate that if the package extends throughout the length of the model, the flow is vertically downward and

Jan 1, 1984

By E. S. Lenker, H. J. Van Hook

A complete swies of solid solutions has been found between the compounds InAs and GaAs Below the solidus. The melting relations determined by differential thermal and static quenching technzques, indicate that the liquidus and solidus are of the simple ascendant type. No evidence of unmixing of the homogeneous solid solutions was observed at sub-solidus temperatures. A quenching method for locnting the solidus, using X-ray diffraction techniques, is described in some detail. THE semi-conducting properties of compounds formed by various combinations of the less familiar intermetallic elements have created an increasing interest in the phase relations in systems involving these elements. The complete phase diagram of such a system, containing a compound of special interest, will often provide information as to the most favorable conditions for preparing large crystals from a melt, as well as specifying the temperature stability of the crystalline phase or phases produced. In view of the current importance of gallium arsenide in semiconductor research and of the structural similarities of indium arsenide, it was thought that the complete phase relations of the system InAs-GaAs should be investigated. Previous work on the system Ga-As by Koster and homa' and on In-As by Liu and peretti2 has shown that GaAs and InAs are the only compounds formed, having melting points of 1238° and 942°C, respectively. In a survey of various systems of elements from groups IIIb and Vb, spengler3 also re- Mines Ltd., for his continuing encouragement and for permission to publish the results of this work. ports complete miscibility of gallium, indium, and arsenic in the liquid state. In a partial investigation of the InAs-GaAs system, Woolley and smith4 found extensive solid solution throughout the alloy range. Their subsolidus work, however, was inconclusive at temperatures below 900" and they did not determine the liquidus relationships of the system. PRESENT INVESTIGATION The starting materials used were high-purity gallium, indium, and arsenic. The method of preparation of the compounds follows that devised by M. Shafer and is described in detail in a paper by Shafer and eiser.' The end-member compounds, GaAs and InAs, were first prepared by reaction of the elements in the desired proportions in evacuated silica glass vials. The vials were rotated in a furnace as the temperature was slowly raised to insure rapid and complete reaction at low temperatures. Thereafter the starting materials, GaAs and InAs, were melted by heating the sealed vials to 1300" and 1000°C, respectively; the vials in this case were filled as completely as possible to keep the vapor space small and thereby minimize the loss of arsenic to the vapor phase. Ten binary mixtures of these compounds were then prepared by reaction of the powdered material in the solid state just below solidus temperatures. At 900C preparations containing 3, 5, 8, 10, 25, 35, 50, and 75 mol pct GaAs were found to be single homogeneous phases, indicating a complete series of solid solutions between GaAs and InAs. Moreover, it was discovered that the homogeneity of any crystalline binary preparation could be very accurately checked by X-ray diffraction because of the large differences in unit cell dimensions of the end membe5s. The cubic lattice constant ofor GaAs is a = 5.652A and that of InAs is a = 6.061A

Jan 1, 1963

By Lars Rossemyr, Terkel Rosenqvist

The equilibrium Mn + 2 IiCl = MnCl2(g) + H2 has been studied at 1090°C for pure manganese and for Mn-Si alloys. For this reoction a standard free energy of Fo1363, = - 19,700 i 300 col ioas found. Combined with other thermal data, the standard free energy of the reaction Mn(s, ß) + Cl2 = MnCl2(g) was derived: Fo=- 56,140 + 9.78 T log T - 40.10 T For the formation of the various manganese silicides the following free energies were obtained. 5 Mn + 3 Si - M1z5Si3 ?F°1363 = -41,500 i 1500 cal Mn + Si - h.lnSi ?F°1363= -10,000 i 500 cnl Mn + 2 Si = MnSiz ?F°1363= -11,500 ± 500 cal In the search for a method suitable for the study of thermodynamic properties of certain alloy systems, it was found that the heterogeneous equilibrium between the alloy and a gas mixture consisting of hydrogen chloride, hydrogen, and volatile metal chlorides has considerable advantages. In addition to giving thermodynamic information about the alloys, such measurements may be used to derive thermodynamic data for the volatile metal chloride itself. The present paper gives some results which were obtained for manganese silicides and manganous chloride. Similar studies are presently being carried out for the iron silicides. The phase diagram of the Mn-Si system is rather well known,' but no information exists to the authors' knowledge about the thermodynamic properties of manganese silicides or about the chemical activities in molten Mn-Si alloys. At elevated temperature, manganese may react with hydrogen chloride according to the equation: Mn(s, ß ) + 2 HC1 = MnC1, (g ) + H2 [ 1] with the equilibrium constant The value of K, may be determined from measurements of the gas composition in equilibrium with pure manganese. When this value is used in connection with measurements on manganese alloys, the chemical activity of manganese in the alloy may be derived. Initial calculations showed that around 1000" to 1200°C the equilibrium constant K1 has a value of a few thousand, i.e., the reaction is shifted far to the right. In order to study this rather unbalanced gas composition, a flow method was used in two slightly different modifications. For all experiments with manganese silicides and for some experiments with pure manganese the apparatus shown on Fig. 1 was used. A bed of the metal or alloy was placed in a tube furnace. The refractory tube had an internal diameter of 14 mm and the bed was 75 mm long. Electrolytic manganese of high purity and silicon, 99.95 pct Si, were used as raw materials. All alloys were prepared by melting weighed amounts of the elements in a high frequency induction furnace in argon atmosphere. The melting was done in a silica crucible which was placed inside a graphite shell. The alloys were crushed to - 10 +40 mesh and analyzed chemically. Also, for the pure elements, the same size fraction was used. A controlled gas mixture of purified hydrogen and from 3 to 12 pct HC1 was passed through the bed where it reacted with manganese according to Eq. [I]. The volatile manganese chloride was collected in a condenser placed in the cooler part of the furnace tube. The gas mixture before and after the furnace was sampled and analyzed by absorption of

Jan 1, 1962

By A. H. Larson, R. J. McClincy

ALTHOUGH arsenic has a very high vapor pressure and vacuum distillation appears to be a likely method for its removal from lead, the published literature contains virtually no information concerning the vacuum removal of arsenic from lead. Caldwell, Spendlove, and St. Claire1 mention arsenic in their investigation of the removal of volatile metals from lead by vacuum distillation. They do not, however, give any data for arsenic removal or refer to any actual experimental work involving arsenic dissolved in lead. Moriyama, Kozuka, and Miura2 have determined the activity of arsenic in dilute As-Pb alloys in the temperature range from 450" to 600°C using a closed galvanic cell. They found that the activities of both arsenic and lead showed a positive deviation from ideality at 600°C. In view of the lack of experimental data regarding the vaporization of arsenic from As-Pb alloys, a limited vapor pressure study was made on liquid alloys containing from 0.5 to 3.3 wt pct As in lead at 703°C. The pressure of As4(v) above the alloys studied was determined from weight-loss data collected by means of the inert-gas saturation method. The experimental apparatus and procedure used were similar to that discussed by Alcock and Hooper9 with modifications as described by the authors., The technique involved was one of passing a known volume of inert gas over the alloy to be studied in a known amount of time and determining the loss in weight of the sample. Because of the low vapor pressure of lead at 703"C, the observed weight loss could be attributed solely to the vaporization of arsenic as the tetratomic molecule AS43 Measurements of the apparent vapor pressure were repeated at different inert-gas flow rates until from three to five values were obtained which were independent of inert-gas flow rate. This value of the apparent vapor pressure was taken to be the equilibrium vapor pressure of the alloy under consideration. The vapor pressures measured in this investigation have been converted to the activities of arsenic in As-Pb alloys, Table I, by use of the data compiled by Elliott and Gleiser5 for the vapor pressure of pure arsenic. The standard state for arsenic was chosen as the pure, hypothetical, supercooled liquid. The activity of arsenic was calculated from the fourth root of the ratio PAs,/PAS,. The low magnitude of the vapor pressures given in Table I explains the difficulty en- countered by earlier workers in successfully vacuum distilling arsenic from very dilute As-Pb alloys. The data shown in Fig. 1 indicate that the As-Pb system behaves ideally. The apparent outlier represented by the alloy containing 1.43 mol pct As is a result of the fact that the pressure of As, above the alloy was barely detectable by the experimental procedure used in this investigation. Because of this, the apparent vapor pressure determined for this alloy could be in considerable error. Moriyama, Kozuka, and ~iura' have reported that arsenic shows a positive deviation from ideality in dilute solution in lead. However, details of their results have not been made available. This research was made possible by a grant from the National Science Foundation (GK-196) for which the authors are very appreciative.

Jan 1, 1970

By James Kemp

PostScript to a paper presented at the New York meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 129 to 154. The writer looked over the quarry with care in the search for fossils, having in mind shells or corals of fairly large size. In the brilliant summer sunshine, none were observed on the glaring white ledges. The impression was gained that none were present and the statement to this effect was made in the edition of this paper published in the Bulletin' of the Institute for February, 1915, p. 136. On closer examination in the laboratory it has been discovered that the limestone itself is made up of minute organisms, which are clearly revealed by microscopic examination of thin sections. The principal component of the rock is a small foraminifer, 0.1 to 0.3 in. (2.5 to 7 mm.), of the genus Orbitoides, presumably an Oligocenic form. Figs. 1 and 2. illustrate it. The accompanying description has been kindly summarized by Marjorie O'Connell, M. A., Curator in Paleontology in Columbia University, who first detected the evidences of organisms in the rock. Orbitoides kempi O'CONNELL N. SP.1 The foraminiferan which makes up the Seboruco limestone is an Orbitoides of a Species new to North America. The only Orbitoides heretofore described from this country is 0. mantelli from the lower Oligocenic of the Gulf States. This form from Cuba, then, so different in all of its characteristics from the 0. mantelli, is of great interest as perhaps forming a basis of correlation over wide areas. The most closely related Species is 0. dispansa Sowerby, which occurs in the Nummulite limestone of the Eocenic of the Bavarian . Alps, in the Priabona beds of the lower Oligocenic of Massano, and elsewhere in Italy, as described by Gümbel.2 The age of the limestone in Cuba would thus Seem to be of upper Eocenic or lower Oligocenic age, probably the latter. The fossil has the form of a sphere Surrounded by a wavy rim of horizontal extent, the whole resembling two flat-brimmed, round-crowned hats placed base to base. The total extent of the Shell ranges up to 7+ mm., while the thickness of the central sphere is 2.5 mm. in one of the largest individuals. Like all of the other Species of Orbitoides, this form begins with a Single layer of chambers which multiply in one plane and assume a circular outline; but it is in the subsequent growth that the distinguishing specific characters appear, for the chambers at the central portion of the shell increase more rapidly than do those near the periphery and in consequence a Swelling is produced which finally gives the Spherical form which is so characteristic. The rim, on the other hand, shows little chamber-increase and remains thin. This is clearly Shown in the sections figured, where the central row of larger chambers forms the equatorial zone. Radiating from this row, in section, there appear, a number of solid cones alternating with broad reticulated ones. The solid cones mark the more dense structure forming the walls surrounding the reticulated or chambered cones. These appear upon the Surface as distinct pits, whereas the solid part appears as raised walls.

Jan 7, 1915

By S. R. Zimmerley, S. F. Ravitz

High-grade cobalt concentrates were produced from the complex Blackbird ore with very good recovery in continuous pilot-plant operations in which a low-grade bulk cobaltite-pyrite flotation concentrate was roasted in a multiple-hearth furnace to oxidize the pyrite selectively. The cobaltite was floated from the resulting calcine. THE existence of the cobalt-copper deposits in the Blackbird district, Lemhi County, Idaho, has been known for many years. However, these deposits have not yet been exploited successfully because of the low grade of the ore, absence of information on ore reserves, and lack of feasible methods for concentrating and recovering cobalt from the ore. In 1941, when it appeared that World War II might interfere seriously with imports of cobalt from overseas, the U. S. Bureau of Mines started an extensive mining and metallurgical investigation of the Blackbird deposits. Exploration by trenching and drilling1 indicated that ore reserves were adequate to warrant consideration of large-scale exploitation. A process for producing high-grade cobalt concentrates from the ore was developed at the Salt Lake City Station of the Bureau,2 and hydrometallurgical procedures for producing cobalt metal or oxide from the concentrates were developed at the Boulder City Station.3 The Howe Sound Co., through a subsidiary, the Calera Mining Co., carried out further exploratory work, which increased probable ore reserves to a tonnage commensurate with a large investment in mine, mill, transportation facilities, and refinery. Simultaneously, the metallurgical staff of the company, working in cooperation with the Bureau of Mines, further investigated the metallurgical problems. It was the opinion of both groups that pilot-plant testing was required to translate laboratory results into plant operation. In general, the Blackbird ore has a high content of pyrite and some pyrrhotite and contains 0.5 to 1 pet cobalt and 1 to 2 pet copper, which are present essentially as cobaltite and chalcopyrite. The copper can be recovered readily as a high-grade concentrate by selective notation. The cobalt then can be recovered as a bulk sulphide concentrate assaying 4 to 5 pct cobalt, but no satisfactory procedure for separating the cobalt from the pyrite and pyrrhotite directly by flotation had been found. The method developed by the Bureau for producing a high-grade cobalt concentrate is essentially an application of the old Horwood process of selective roasting.4 The bulk sulphide concentrate is roasted to form an oxide coating on the iron mineral particles, and the calcine is then treated by flotation. The oxide coating prevents the iron minerals from floating so that it is possible to obtain a high recovery of cobalt in concentrates assaying more than 20 pct cobalt. Laboratory tests by metallurgists of both the Bureau and the Howe Sound Co. had indicated the optimum roasting temperature to be 425° to 450°C. At lower temperatures the rate of oxidation of the iron minerals is too low, whereas at higher temperatures substantial quantities of cobalt are rendered water-soluble. Because of its high sulphur content (35 to 40 pct), the bulk concentrate tends to continue to burn after it has reached the optimum roasting temperature. Although excessive temperatures could be avoided in the small-scale laboratory furnaces, there was considerable doubt that the temperature could be controlled properly in industrial equipment. To provide material for the pilot-plant tests, the Calera Mining Co. installed a small, temporary flotation mill at the Blackbird property and treated

Jan 1, 1951

This volume summarizes characteristics and the geological setting of porphyry copper deposits of the Western Hemisphere. Grouped by characteristics, porphyry copper deposits are described in six regions: Andean orogen, Appalachian orogen, Alaska, northern Cordilleran orogen, southern Cordilleran orogen, and the Caribbean. Each region has its own peculiarities of geologic setting, and those deposit characteristics that may be projected from one chapter to another will be used in reaching the conclusions from which to draw genetic models for porphyry copper deposits. The term porphyry in this volume denotes a type of ore deposit, rather than a rock classification. The classification of intrusive igneous rocks used in this volume is shown in Figs. 36a and 42 (pp. 103, 130). Some modern classifications suggest mineral-ratio definitions other than those used in this volume; however, most literature references cited are based on the classification shown in Figs. 36a and 42. The reader should be aware, therefore, that quartz monzonite in this volume contains from 35% to 65% potassuim feldspar and at least 10% quartz. A term used in this volume is defined where introduced within the context of a specific chapter. Distensional tectonic conditions are used in the sense of Cady (1972) in the Appalachian orogen, for example. Porphyry copper deposits are defined as large bodies of mineralized rock, usually including a porphyritic intrusive phase, that have copper sulfide minerals disseminated through them. The definition has no commercial connotation and is used strictly in a noneconomic sense to encompass the spectrum of copper mineralization associated with these deposits. Terms commonly accepted in the literature are not defined. Porphyry molybdenum and porphyry copper deposits commonly are distinguished by most economic geologists. The basis for the separation is summarized in one chapter of this volume. To permit the reader to more easily peruse the bibliography for any particular region, references will be found at the end of each chapter. The bibliography is not intended to be complete, but is designed to provide adequate minimum coverage for descriptions of deposits in the chapter concerned. Each entry is properly referenced in the text of that chapter to facilitate the reader's research into any particular topic. This volume is written from the point of view of the exploration geologist whose task it is to evaluate the structural, petrographic, mineralogic, and metallogenic characteristics of a porphyry copper deposit. The goal of the evaluation is to determine if, and where, concentrations of metals may exist in an igneous- hydrothermal system that includes the most complex set of geologic factors found in any of the many types of ore deposits. The successful porphyry copper geologist is simultaneously a petrographer, geochemist, structural geologist, and mineralogist. Some porphyry copper deposits have developed in volcanic arcs underlain by a Benioff seismic zone with a trench paralleling the arc. The most convincing example of a deposit known to have developed in an environment where subduction is an active process is the 3.3 m.y. (million years) old Dry Creek occurrence in the Aleutian arc (this volume). On the other hand, the younger deposits in the Cascades appear to have formed in a volcanic arc lacking both the Benioff zone and the offshore trench. Subduction is not widely accepted as an active mechanism for the period when the younger Cascade deposits formed. Subduction has also been questioned for deposits formed at a great distance from a plate boundary (e.g., Bingham). Regardless of the pros and cons regarding subduction, most deposits are associated with regional faults. Strike-slip

Jan 1, 1978

By James A. McGurty, Walter J. Koshuba, Samuel G. Gordon, Gilbert E. Klein

ONE of the problems encountered in working with metals at elevated temperatures is the instability resulting from solid-solid diffusion at a -common interface. A determination of the nature and magnitude of this phenomenon is important as related to structural properties of materials potentially useful in high temperature applications. This paper is concerned with the solid state reaction between metallic molybdenum and beryllium at elevated temperatures. In the older literature,' there were no known inter-metallic compounds in the system Be-Mo, and the list of beryllium intermetallics was rather small. New compilations have been made by Smithells' and by Taylor," listing all the then known beryllium binary intermetallic compounds. In addition to these, some new phases have just been reported' in the system Zr-Be and some further compounds of the type MBe,3 have been currently described. The new compound MoBe,, which is reported upon in this paper differs considerably from the above mentioned MBe13 group, and will be discussed in detail. Diffusion Study The nature of the solid diffusion at a Mo-Be interface was determined by sealing a beryllium rod inside a molybdenum capsule and heating at a temperature of 2000°F' (1100°C) for 100 hr. The molybdenum capsule was fabricated from % in. swaged molybdenum rod obtained from the Fansteel Metallurgical Corp. The beryllium metal was obtained from Brush Beryllium Corp. as % in. cold-drawn rod. This material assayed 99.05 pct Be and contained as impurities 0.84 pct Be0 and 0.19 pct Be2C. The molybdenum capsule was % in. in OD x 2 in. long. To prepare it, a concentric hole 0.250 in. + 0.001 in. — 0.000 in. in diam was drilled and reamed in one end of a rod to a depth of 1 '/2 in. A 1 in. long beryllium rod 0.250 in. + 0.000 in. — 0.001 in. in diam was pressed into the molybdenum capsule. A molybdenum plug 0.250 in. & 0.001 in. in diam x 9/16 in. long was then used to seal the beryllium in place. The capsules were placed in a molybdenum resistance furnace and heated at 2000°F (1100°C) for 100 hr. On cooling, the specimens were cut and examined metallographically. Fig. 1 is a micrograph at X250 of a portion of the interface from a transverse section. Four phases are clearly visible, with sharp boundaries between them. Phase A is a section of the molybdenum capsule; phase B is the molybdenum-rich intermetallic composition MoBe,; phase C is the beryllium-rich compound MoBe13; phase D is a section of the beryllium rod. All phases were readily polished to a high metallic luster. The molybdenum-rich phase has a pronounced purple tinge. The beryllium-rich phase (C) is only slightly darker than the pure beryllium. In polarized reflected light, however, it shows striking birefringence between crossed Nicols. The black areas represent flaws or pores in the material. A small representative amount of powdered material from each of the phases was carefully removed under the microscope with a diamond tool. With this material, powder X-ray diffraction patterns were made for the identification of each phase. Table I lists the X-ray diffraction spacings and corresponding indexes characteristic of these intermetallic compounds. Synthesis To establish the formula of the new intermetallic compound, X-ray diffraction patterns were made from powders obtained from solidified melts of known composition. The syntheses were made by

Jan 1, 1952

By Mark J. Klein, Robert A. Haggins

The pesence of a small amount of oxygen was found to cause significant grain growth restraint in 99.99 pct Ag. This behavior does not seem to be due to the presence of an oxide dispersion, but instead, to be related to the existence of minute amounts of oxygen m solid solution. In the amounts necessary to cause the observed effects it was found that oxygen migrates with extreme rapidity, probably along extended structural imperfections, such as dislocations and grain boundaries. A number of years ago, hastton' observed that the presence of small amounts of oxygen caused a retardation of grain growth in silver. He attributed this behavior to the formation of a fine dispersion of oxide particles by the internal oxidation of trace impurities. More recently, wood2 also found that oxygen caused grain growth restraint in copper. Experiments using both copper and a dilute solution of aluminum in copper led to the conclusion that the effects observed in copper were due to oxygen in solid solution, rather than an oxide dispersion. During the course of a study of the influence of several solutes on the recrystallization of Silver, the presence of minute amounts of oxygen was found to exert a very significant influence on grain growth. The experiments reported here were undertaken to determine whether the grain growth restraint observed in silver due to the presence of oxygen is related to oxygen in solution or to an oxide dispersion. Because of the difficulty in measurement and control of the very small oxygen concentrations causing the observed effects no attempt was made to treat the data in a quantitative manner. EXPERIMENTAL PROCEDURE AND RESULTS Silver of 99.99 pct purity was melted and cast into slabs in a vacuum of better than 0.1 p. These slabs were reduced 50 pct by cold rolling to a thickness of approximately 2.5 mm. Samples cut from this material were annealed in vacuum for a series of different times at 803°C. Another group of samples was similarly annealed in air. This temperature is well above the recrystallization range for silver of this purity (150" to 200°C). The mean grain diameter of these samples was measured, both in the center and near the edge, using the line-intel-cept method, and is shown as a function of annealing time in Fig. 1. The grain size in the centers of the samples annealed in air was found to be larger than that of the surface regions, while the grain growth behavior of the edge and center regions annealed in a vacuum was approximately the same. he edge measurements were taken at a distance of 0.2 mm from the surface.) A few samples were annealed in nitrogen. Their behavior was identical to that of the vacuum-annealed samples. Samples annealed in oxygen had approximately the same grain growth behavior as those annealed in air, leading to the conclusion that this behaviouer is due to oxygen. The microstructure of a sample annealed in air at 803" for. 30 minutes is shown in Fig. 2. The smaller grain size near the surface is characteristic of the iir-annealed specimens. Possible causes of this grain growth restraint in the air-annealed specimen are the formation of an im-

Jan 1, 1962

By Charles L. Guettel

The temperature coefficients of electrical resistance of 31 alloys in the nickel-rich corner of the Ni-Cr-Fe system were determined. The results indicate that a range of binary Ni-Cr alloys has lower temperature coefficients than a specific region of Ni-Cr-Fe alloys which has been reported and quoted by others as providing the lowest coefficients in the ternary system. DESIRABLE properties of resistivity and temperature coefficients of resistance have been the basis for the successful commercial application of various Ni-Cr and Ni-Cr-Fe alloys. In particular, low or negligible temperature coefficients of resistance are necessary for wire used in precision wire wound resistors and potentiometers involved in closely controlled electrical and electronic circuitry. Alloys most successfully applied to this purpose basically have not been ternary Ni-Cr-Fe alloys but rather heat-treated Ni-Cr alloys in the region of approximately 73 to 79 pct Ni and 20 pct Cr with significant additions of other elements such as aluminum, silicon, iron, copper, manganese, and cobalt. While the addition elements play a vital role in the nature and control of the temperature-resistance curve of any one of these alloys, the inherent relatively low temperature coefficient of the binary Ni-Cr base composition itself in the approximate region of 80 pct Ni and 20 pct Cr contributes fundamentally to the eventual negligible temperature coefficient obtained with the applied alloys. W. A. Dean 1 has reported mean temperature coefficients (20' to 100oC) of as-cast samples for the Ni-Cr-Fe system, the nickel corner of which is given in Fig. 1. Dean had to use as-cast samples because alloys from a considerable region of the system were unworkable. Dean refers to the work of Hunter and sebast2 who used annealed wire samples to show that, for chromium contents of 10 to 25 pct, the temperature coefficient increases as the iron content is increased at the expense of nickel. Although the data of Hunter and Sebast were limited in the nickel-rich areas to eight samples of 60 to 91 pct Ni with only four samples containing iron, the possibility that no Ni-Cr-Fe alloy has a lower temperature coefficient than certain binary Ni-Cr alloys should have been given serious consideration. However, Dean's work has been referred to by J. S. Marsh,3 who, quoting Dean, states that for the temperature coefficients "the smallest values-about 0.0001 per oC (100 ppm)—were found for alloys containing about 55 pct Ni and 20 pct Cr" (balance iron). A region such as that reported by Dean would be significant to those trying to develop alloys for the applications described. Therefore, a series of three-pound laboratory open-air induction melts of Ni-Cr and Ni-Cr-Fe alloys were melted, conventionally processed to 0.005 in. diam wire, and continuously strand annealed at 1900° F. The basic Ni-Cr compositions, with balances essentially iron other than usual minor impurities, and the corresponding temperature coefficients of resistance and resistivities are given in Table I. The resistivities are approximate and are not to be considered as a basis for relating them to their position of composition in the ternary system. The wire diameters were determined with a micrometer, and not by weight and density measurements which would be required for accurate resistivity values. However,

Jan 1, 1963

By M. E. Learmont, R. J. Lipp, I. Iwasaki

In the selective flocculation of iron ores, the concentration of alkaline earth ions in pulp solutions plays a critical role. Sodium silicate, alone or with sodium tripolyphosphate, has been used as a dispersant. When Ca+ + concentration exceeds 15 to 20 ppm, however, only a strong complexing agent, such as ethylenediaminetetraacetate (EDTA) was found to be effective (Heerema, Lipp, and Iwasaki, 1979). Some iron ores release Ca+ + in excess of 20 ppm. With ores that contain gypsum, the Ca+ + concentration may reach several hundred ppm. The purpose of this investigation was to compare the effectiveness of EDTA with nitrilotriacetate (NTA) in countering the adverse effects of Ca+ +, particularly at high Ca+ + concentrations. Emphasis was placed on the use of NTA since it is more cost-effective than EDTA. It is also used in detergents in some countries (Malaiyandi, Williams, and O'Grady, 1979). NTA, like EDTA, forms a soluble complex with Ca+ + with a 1:1 molar ratio. Its structure and the value of log Kca are given below together with EDTA (Shibata, 1963). [ ] For experimental materials, an equal weight mixture of Lac Jeannine hematite and a high-purity quartzite from Thompson, MN, both ground to - 30 µm (- 560 mesh) was used. Selective flocculation test conditions and procedures were identical to those used in previous investigations (Heerema, Lipp, and Iwasaki, 1979). The optimum level of starch addition for the above mixture was determined to be at 300 g/t (0.6 lb per st). Initially, a series of selective flocculation tests were performed on the mixture pulped with 10-3M CaC12 (40 ppm Ca + +) at pH 11. With no NTA present, flocculation of the entire suspension resulted. The selectivities achieved in tests with 90, 100, and 150% of the stoichiometric amount of NTA were virtually identical to each other and also to the selectivity of separation obtained in the absence of Ca+ + Such an observation could have been expected since Ca+ + concentrations up to a few ppm may be tolerated in selective flocculation (Krishnan and Iwasaki, 1982). A similar series of tests were performed at 10-2M CaC12 (400 ppm Ca+ +). The results are shown in Fig. 1 as grade¬recovery curves. For comparison, the results obtained in the absence of Ca++ are included. At 90% of the stoichiometric amount of NTA, a large enough concentration of uncomplexed Ca+ + was left in solution to cause indiscriminate flocculation. Note in this figure that NTA is capable of countering the adverse effect of Ca+ + even at this high concentration when it is used in excess of stoichiometric amounts. The free Ca+ + concentrations at 100 and 150% are calculated to be 2.5 and 0 ppm, respectively. [ ] The relative effectiveness of NTA and EDTA was then compared at 100% of the stoichiometric amount using 10-2M and 10-3M CaCI2 (Fig. 2). EDTA appears to be slightly more effective than NTA. The free Ca++ of 0.02 ppm in 10-2M CaC12 with EDTA compared to 2.5 ppm free Ca+ + with NTA might account for the difference. As evident, prohibitively high additions of EDTA and NTA were required to complex high concentrations of calcium ion. The use of both of these agents would result in the accumulation of complexed Ca+ + in recycle water.

Jan 1, 1985

By John K. Hammes

INTRODUCTION This introductory paper presents a description and definition of what the finance function is and what it specifically means for the mining industry. In its simplest terms, finance is, "management of money matters". As an area within the discipline of business administration it draws heavily on the related fields of economics and accounting, and to a lesser extent on marketing and production. MINING FINANCE DEFINED In preparing to write about what finance means to the mining industry, I asked a number of mining people the question, "What does mining finance mean to you?" Most responded that mining finance was "How a company borrowed money for mine development", and perhaps half those questioned included "raising equity" in the definition. It is not surprising that the mining industry concept of finance is the providing of funds needed for the objectives of the business, for that was once a view shared by authorities in the field of business administration. Further, it is certainly the area where much of the emphasis has been placed in the past ten to fifteen years as the industry struggled with the development of more remote and more refractory or lower-grade orebodies while profitability and internal cash flow were below expectations. No wonder project finance became such a popular topic. Twenty years ago it is probable that the emphasis would have been on mine valuation, for that subject was the area of finance then most often examined in industry publications. Papers concerning the pros and cons of payback, internal rate of return, and discounted cash flow appeared regularly. Let's examine the following situations, each the result of a financial decision: - Funding the exploration program in a developing country was accomplished by buying the next six-months budget needs in local currency. One week later the currency devalued 30 percent. If the purchase had been delayed or the local currency borrowed short term, a substantial saving would have been made in funding the program. - A major mining company borrows heavily to finance both expansion of its primary mining business and its entry into several new industry segments. When markets for all of the commodities it produces turn down for a prolonged period, there is concern over the adequacy of cashflow to cover debt service in addition to other company needs. The company's financial officers, however, had arranged very large committed credit facilities from numerous financial institutions which assured the availability of funds for several years. This enabled the company to implement a strategy to conserve cash, sell assets and survive until conditions improved. Further, short term suppliers of credit also were comfortable with the assurance that longer term credit was there to support them. -A medium size mining company financed several mines independently with limited obligations on the part of the parent company. The company decided to refinance the operations under one agreement. More flexible terms, lower interest cost and a longer tenor financing were achieved in return for assuming the risk as a direct obligor. - The exploration and development group of a large mining company proposes to develop a new mine in a country in which the company does not presently operate. When the investment is rejected they are advised that one reason was that the reinvestment assumption inherent in the discounted

Jan 1, 1985

By R. B. Rosene, G. L. Foster, A. R. Hendrickson

he properties of some of the common fracturing oils, such as sand-falling rate, fluid loss and viscasity, are a function of the three major constituents of the oil. These are: asphaltic material, parafin waxes and a base oil. The base oil can be either high or low viscosity. Asphaltic material increases viscosity by thickening the oil, decreasing the rate of fall of sand through the oil. at temperatures up to 200" F. When large arnorrnts of parafin wax are present, much of the wax i.s not dissolved, but is present in the form of rnicroscopic crystals. 7'his, of course is limited to temperatures below the melting points of waxe.s. As a result, parafin waxes clo not function primarily as thickener.7, but rother as bullting materials. The functiori of wax, without asphaltic material, in a low viscosity base oil is uniquely unlike that of wax with asphalt coexistent in the oil. The resulting difierence in wax crystal size governs the sand-falling rate to a large extent. An ideal type of fracturing oil is one containing neither asphalt nor waxes. In such cases, the viscosity and resulting low sand-falling rate are apparently due to soluble resin- ous hydrocarbons, which are compatible with formation oils. INTRODUCTION Since the introduction of hydraulic fracturing as a method of stimulating production from oil and gas wells, a variety of fluids have been employed to open the fractures and carry the propping agent. Such fluids include gels, emulsions, and oils. In the latter category, the use of refined oils has increased tremendously, and it is probably safe to assume that such oils represent more than one-half of the total fluid used in fracturing. The general acceptance of refined oils for fracturing can be accounted for on the basis of their relatively low cost and general applicability. To minimize transportation costs, such refined oils are generally obtained within the local areas of operation. As a result there are several kinds of oil used in different areas, with a wide variation in the basic composition. These types may vary from a fair grade of lubricating stock to a highly viscous cut-back asphalt. or road oil. Originally, little attention was paid to the composition of the oils used for fracturing, and any oil which would carry sand was considered satisfactory. Recently, however, service companies and well operators have become more concerned with the type of oils used for fracturing. With this in mind, the present work was undertaken to evaluate and compare many widely used fracturing oils to determine which constituents were most desirable for fracturing purposes. Some of the important properties of fracturing fluids are sand-falling rate, viscosity, and fluid loss. Other properties, that are actually of no less importance, include flash point, pour point, emulsifying tendencies with formation brines, and compatability with the formation oils. This discussion has been limited, however, to the first mentioned properties in order to give some idea of the general composition of the refined oils, how they function, and why. PROPERTIES OF FRACTURING OILS The properties of fracturing oils are a function of the three major constituents of the oil. These may be designated as: (1) asphaltic material, (2) paraffin waxes and (3) a base oil, which may be of either high or low viscosity. The asphaltic material clas-

Jan 1, 1956

By Evert Hoek

Summarising a conference is never an easy task, but I will try to keep my comments brief and to the point. There are a number of lessons which we have learned from our deliberations together during these past three days, and I will try to give you my impressions of these lessons and of their practical implications in open pit mining. The first thing that has become increasingly obvious during these discussions is that it is no longer acceptable to offer an 'Act of God' as an excuse for a major slope or tailings dam failure. Disasters such as that at Aberfan in the United Kingdom have focussed the world's attention on the activities of the mining industry and the report of the commission set up to investigate the Aberfan disaster clearly showed that adequate knowledge was available and that failure to apply this knowledge did not qualify as an 'Act of God'. The courts and the world's press are certain to impose increasingly harsher penalties and criticism on those held responsible for major failures, particularly of tailings dams, in the future. One of the major problems in applying available knowledge to slope problems is that attempts to apply this knowledge are frequently left too late. To provide an engineering solution in the case of a slope in an advanced state of failure is an almost impossible task, and it is essential that those responsible for the stability of a slope must learn to recognise signs of distress at an early enough stage for effective remedial measures to be taken. As our ability to solve slope problems improves, the time at which slope stability problems are considered in a mining project must move forward to a stage at which these problems can be anticipated and dealt with before they arise. Conferences such as this are important in that they enable us to exchange ideas and advance our knowledge to a level at which such predictive engineering will be possible. It has been encouraging to hear of mining projects such as the Bougainville Copper operation where slope stability studies were carried out as part of the overall evaluation programme and it is hoped that this will become a more common procedure in the future. Providing a safe slope in an opencast mine obviously costs money, either in terms of the reduced ore to waste ratio given by flat slopes or because of the cost of stabilization techniques such as drainage or the use of rock anchors. An optimum slope design will provide maximum safety at minimum cost but achieving this optimum is not an easy task. Any one of us could design a slope which would be stable to the end of time, but it is probable that that slope would be so flat as to be totally uneconomic in most open pit mining situations. On the other hand, if the overall economics of a mining project are so critical as to require slope angles which the engineer responsible for these slopes considers to be unsafe, it is his duty to make us could design a slope which would be stable to the end of time, but it is probable that that slope would be so flat as to be totally uneconomic in most open pit mining situations. On the other hand, if the overall economics of a mining project are so critical as to require slope angles which the engineer responsible for these slopes considers to be unsafe, it is his duty to make

Jan 1, 1971

By W. W. Krysko

In order to calculate the critical particle size of lead oxide entrapped in lead, Stoke's Formula may be applied. All data were available except figures for the density of lead oxide at elevated temperatwes. The density of lead oxide was determined by means of dilatometmetrc and volumetric methods up to 1010°C. Graphs of the density of lead and lead oxide as well as the viscosity of lead are given and discussed, with the conclusion that the most unfavorable region for the separation of lead oxide from molten lead lies just above the melting point of lead. DURING previous investigations, particularly on the dedrossing of lead with aluminum1 and the oxygen solubility in lead,' the critical particle size of lead oxide which could be entrapped in solidifying lead was estimated by calculation, and it was shown that high values found for the oxygen content of lead may be due to the method of sampling and the entrapped particles of dross. Unfortunately, due to lack of data, an exact mathematical solution was not possible. The particle size which will separate under a given condition can be estimated from Stoke's Law, which states that where: d = diameter of the critical particle size ¦q = viscosity of lead in Poise V = constant velocity in cm sec-I g = 981 cm sec-2 61= specific gravity of lead 62= specific gravity of lead oxide The depth of the lead bath and the time before solidifying define the velocity. The viscosity of molten lead is known from earlier work by Krysko and is given in Table I. The specific gravity of lead is also known, see Table II. These values are according to Hofmann. A careful survey of literature revealed no values for the density of lead oxide at elevated temperatures. The present investigation was therefore conducted to provide this information. RESEARCH INVESTIGATIONS The density of lead oxide was determined from the following experiments: 1) Determination of the density of lead oxide at room temperature. 2) Dilatometric investigations on the same samples. 3) Determination of the shrinkage at the liquid-solid trans£ormation. 4) Density determinations on liquid lead oxide. 5) Time temperature curves during cooling. 1) The samples for the determination of the density of lead oxide in the solid state were prepared in the following manner. Molten lead oxide was cast into I hot mold which could be opened along the longitudinal (vertical) axis. The cast samples were cylinders of approximately 10 mm diam and approximately 80 mm length. The cylindrical hot mold was open at both ends and was placed on a large copper chill plate shortly before casting. The solidification of the lead oxides proceeded upwards without any formation of internal cavities. The sample was carefully checked with respect to density and crystalline appearance, and only the lower portions which were crystalline and free from porosity were used. The density was determined in a specially made pyknometer-like container, where the surplus liquid was squeezed out through an orifice approximately 1/10 mm in diameter. Mercury or water was used as the liquid. The densities of the samples were calculated from the weight, volume, and mean specific gravity of eight samples was 9.62 * 0.05 g cm"3 at 22"~. 2) The samples were machined to approximately 1 1/2 in. in length and fitted into a dilatometer. A

Jan 1, 1962

INTRODUCTION Besides the European export credit agencies covered in Ted Rides' paper in this Chapter, other agencies are also active (see Appendix) but the most notable for mining projects are The Export-Import Bank of the United States ("US Exim") and the Export Development Corporation ("EDC") of Canada. Mexico's Fomex is basically a short-term trade-finance fund administered by the Central Bank. US Exim This independent agency can provide loans, guarantees, and insurance. Like all export-credit agencies, its mandate is to support the export of goods and services from the US as a means of competing against other countries' products. If a piece of mining equipment can only he made in the US, the US Exim may very well not provide any financial assistance. (It is important not to place the order for any item for which export credit is sought because, once ordered, the situation is no longer competitive in US Exim's eyes.) Direct Credits and financial guarantees ("buyer credits") are commonly in amounts greater than 85 million and for terms longer than six years. An example here is the $48.5 million provided to PT International Nickel Indonesia (see Robert de Gavre's paper in Chapter 12). US Exim usually requires a 15% downpayment and, therefore, finances up to 857 of the goods; less if the US content is lower. The dollar funding can he US prime, London Interbank Offered Rate (LIBOR), or other sources. Exim can fund in either or both of the following ways: 1. Under a US bank Letter of Credit ("L/C") 2. Reimbursement to the buyer/borrower via a US bank account. US Exim will, without charge, issue a preliminary commitment. It will, however, need to approve the various credit agreements and prefers to tie other parallel financings into one loan agreement. US Exim's total commitments are large, up to $5R billion in aggregate under various programs. US Exim has been the world's leader in medium-to long-term minerals project financings/ co-financings but suffers from (i) aggressive foreign export-credit competition whereby other nations mix in soft-loans or aid programs ("mixed credits") to increase the percentage financed and lower the interest margin and (ii) an imbalance in its own cost of funds. A common US Exim package would be as follows: 15% Banks under US Exim guarantee, floating rate over prime or LIBOR. 35% US Exim funding, fixed rate 35% Pefco funding, fixed rate 857 Drawn down pro-rata under US bank L/C 15% Cash down payment (may have been financed within a project/corporate credit) 100% Repayment usually begins six months after planned start-up in equal semi-annual instalments, with the banks usually paid out first, Pefco next, and US Exim last. Medium-term credits ("supplier credits") are issued for US equipment exports for terms up to five years, again for 85% of the equipment costs although the exporter is expected to bear at least 10% out of that 857 for its own risk. The buyer is required to be a first-class credit such as some governments or highly credit-worthy companies. Otherwise a bank L/C would be required. (This may be wrapped into an overall project-finance package for a minerals development. The project-finance banks provide an L/C to US Exim instead of funding that portion themselves.) US Exim guarantees 100% of the political risk and either 85% or 95% of the commercial risk for

Jan 1, 1985

By P. Schwarzkopf, J. H. Brophy

A modification of the Mendenhall wedge blackbody1 has been used to determine solidus temperatures and to anneal alloys in the tantalum-rhenium binary system. The technique has proven to be simple and accurate with modest power requirements. For temperatures up to 2800° C a piece of 10-mil tantalum sheet was folded double and formed as shown in Fig. 1. The middle of the resulting ribbon filament was a cylindrical-shaped crucible with less than a 1/8-in. opening. After inserting a specimen in the cavity, the filament was clamped between molybdenum electrodes in a high vacuum chamber. A representative filament 2 in. long and % in. deep was heated to 2800°C with a current of 700 amp at 4 v. The specimen temperature was determined by sighting into the cavity with a Leeds and Northrup optical pyrometer. The twisted filament shape was necessary to avoid serious geometric changes during thermal expansion. For temperatures between 2800" and 3000°C a 4-mil tungsten filament was employed. To facilitate fabrication it was warm-folded, and a twisted segment of 10-mil tantalum was used to support one end to absorb thermal expansion. This element assembly required about 700 amp at 10 v to reach 3000°C. Two geometric modifications of the filament were helpful for solidus temperature determinations. A shallow chamber, with depth to opening ratio of 3 to 1, permitted direct observation of the specimen through the optical pyrometer. The fact that the specimen was visible permitted the melting point to be determined when sharp features on the specimen surface became rounded; it also indicated that blackbody conditions did not prevail. By standardizing against the melting point of molybdenum, the observed melting temperature was corrected by the following form of Wien's Law: in which T is the true temperature, To is the observed temperature, and K is a constant characteristic of the filament geometry and determined experimentally for the molybdenum standard. The resulting corrected melting point for each alloy served as a reference temperature for the second more precise filament geometry. With a 6 to 1 depth to opening ratio, the specimen was indistinguishable from the filament interior, indicating good blackbody conditions. Using this technique, a series of specimens was isothermally treated at temperatures above and below the corrected direct reading. Incipient melting was detected by visual or micrographic examination of the specimen after cooling. This procedure was checked with specimens of pure chromium, molybdenum, and tantalum. Table I represents the values obtained, together with the solidus temperatures in the tantalum-rhenium binary system determined by the same technique. The alloy specimens were approximately 1/8 in. in diam. They were pieces of 10-g buttons melted four times in a nonconsumable tungsten electrode arc furnace on a water cooled copper hearth in 2/3 atmos of titanium gettered helium. Several sources of error are possible in such temperature measurements. Within the accuracy of the pyrometer no gradients were detectable near the specimen, and element distortion was virtually eliminated by twisting the tantalum. Compensation was made for the 1/8-in. sight glass by inserting several identical thicknesses and extrapolating to zero thickness. As a result an additional 10°C correction was added to all observations in the temperature range of 2500" to 3000°C. The principal source of error was then in the operation of the

Jan 1, 1961

By Mark E. Emerson

INTRODUCTION A long time has passed since geologists encountered encouraging mineralization in their regional exploration program for base metals deposits. Detailed drilling during the following two field seasons served to delineate the configuration of the deposit. Various statistical techniques were employed to provide confidence levels regarding the extent of the reserves and to categorize them according to whether proved, indicated or inferred. At this juncture, it appears that the company has an orebody. Time elapsed? - three years; money spent? - $2.5 million. Much remains to be done before the orebody becomes a mine. The company urgently needs to develop new orebodies to replace its existing mines which are being depleted. It therefore has expended sizable amounts in exploration, the life blood of the company. A staff of specialists is maintained to evaluate new projects and to conduct feasibility studies. The scale of new mining projects today is beyond the resources of most mining companies. Bank financing, therefore, is often vital if the company is to survive. The following scenario describes how a company goes about evaluating mine projects and what is needed to meet lender's criteria in securing the needed financing. MINE PLANNING Now that the company engineers have taken over the project, their concern is no longer with finding ore but in developing it. An exploration shaft has been put down and a tunnel driven into the orebody to verify, on a large scale, what has been seen so far only in pencil- like drill cores. A large tonnage bulk sample is mined and shipped off to an independent metallurgical process laboratory for beneficiation testing. The budget is expended to cover engineering studies. Preliminary capical and operating costs are developed in- house and profitability studies are made based or1 assumptions concerning the markets for the main product and the indicated gold, silver, and other by-products. Time elapsed? - four years; cost to date? - $3.5-$4.5 million. The staff prepares its own pre-feasibility study. After review, the Executive Committee authorizes management to proceed with full-scale studies. The task is to make preliminary designs and to develop definitive capital and operating cost estimates. Specialized consultants will be engaged to study slope stability for the open pit and rock strength if underground recovery proves more feasible. If it is near the sea, an oceanographic report might be commissioned to see if the tailings can be disposed of off shore. Environmental impact studies are commissioned from a firm familiar with government requirements and regulations in this important area. The company subscribes for an expensive multi-client study of the supply- demand-price outlook for the product to support its own long-range price forecast. Now all the numbers are available to make a definitive appraisal of the value of the project. Cash flow analyses and sensitivity studies follow. Reams of computer printouts are generated. Time elapsed: five years. Amount spent? - up to $9 million, depending on the size, complexity and attractiveness of the project. Marginal projects always take longer. Finally, an engineering and construction (E&C) company is given the task of integrating and compiling all the data into a feasibility study. The results of dozens of reports, memoranda, computer printouts, and charts are boiled down to one final summary report of a few hundred pages together with conclusions and recommendations. After thoughtful review at a board meeting, the directors authorize management to proceed with detailed engineering work - provided that

Jan 1, 1985

By O. N. Carlson, D. G. Alexander

THE hardness anisotropy of metals and alloys has been of increasing interest in recent years but silicon ferrite,1 niobium,2 and tungsten3,4 are the only bcc metals about which this type of information has been reported. This investigation was carried out on vanadium and chromium single crystals in an effort to determine to what degree the hardness variations observed in these metals are due to orientation effects and to compare their behavior with other bcc metals. In earlier work the authors had observed a small angular dependence in the Diamond Pyramid Hardness of single crystalline vanadium on the (100) plane but no anisotropic effects were noted on either the (110) or (111) planes. At the suggestion of R. G. wheeler5 it was decided to investigate this effect in greater detail using the more asymmetric Knoop indentor. The vanadium metal used in the study was prepared by the aluminothermic reduction of V2O5 followed by electron beam melting.6 The principal analyzed impurities were 230 ppm C, 230 ppm O, 65 ppm N, 90 pprn Al, Cr not detected, 50 ppm Fe, 60 ppm Ni, and 200 ppm Si. The chromium was an iodide-refined product obtained from the Chromalloy Corporation. Analysis of this material showed the following amounts of impurities present: 10 ppm C, 9 ppm O, 2 ppm N, 0.4 ppm H, 3 ppm Al, 2 ppm Ca, 2 ppm Cu, 20 ppm Fe, 1 ppm Mg, 0.3 ppm Mn, 1 ppm Mo, 3 ppm Ni, 10 ppm Si, and 1 ppm V. Single crystals of both metals about 1 cm in diam and 10 cm in length were grown by an arc-zone melt- ing technique.7 The chromium crystal was annealed at 1600°C for 6 hr in a purified argon atmosphere to remove any strains or inhomogeneities, but the vanadium was tested in the as-grown condition. The crystals were oriented by the Laue back-reflection method and then sectioned with a spark cutter into individual specimens with a (loo), (110), or (111) plane parallel to the crystal surface. They were mounted in Lucite and carefully ground to a flat surface. The vanadium specimens were then electropolished in a 6 pct perchloric acid-methanol mixture while the chromium specimens were mechanically polished on a Syntron vibratory polisher using an alumina abrasive. The orientation of each crystal was then rechecked by the back-reflection X-ray method. All of them were found to lie within 2 deg of the desired orientation with the exception of the (110)-Oriented chromium crystal which was within 4 deg. Microhardness impressions were taken at 10 deg intervals from the common (110) direction by rotating the crystal in the plane of the crystal surface. A Knoop indentor was used with a 400-g load on the vanadium crystals and an 800-g load on the chromium. The hardness values are averages of 6 impressions and standard deviations were calculated for each set of data. The values reported for the (111) plane of vanadium are based on from 10 to 15 measurements for each point. The microhardness results for vanadium and chromium are plotted as a function of the angular rotation of the long axis of a Knoop indentor from the (110)

Jan 1, 1970

By C. A. Hartinagel

During 1941, the total production of crude oil in New York state was 5,185,000 bbl. This represents a small increase over the average for the past five years. From 1921, when the annual production of the state amounted to only 988,000 bbl., there was a regular annual increase in production (excepting one or two years) until the 5,000,000-bbl. mark was reached in 1937, After more than 20 years of oil recovery by flooding methods, it was generally believed, until a few months ago, that the rate of production was nearly at its peak and within a few years the fields would experience a gradual decline as the thicker sands became exhausted and the thinner ones could be worked only at increasing costs. As a result of the present emergency, however, unusual efforts are being made, in spite of higher costs of operation, to increase the output of Pennsylvania grade oil, to which the New York product belongs. Since most of any increased production would be obtained by flooding, and since floods travel slowly, no large increase in production can be expected for some months to come. During the first year, 10 or 15 per cent increase could be obtained, but maximum production, an increase of perhaps 40 per cent, could not be expected until some time during the second or third year. In the Allegany fields, which account for two thirds of the state's oil production, 1246 wells, including water-intake wells, were drilled during the year; 390 more than in the preceding year and 590 more than in 1939. It is evident that much of the best oil territory has already been developed. As producers move toward edge properties and thinner sands, returns will be smaller, whereas costs remain the same or, under war conditions, become higher. It is estimated that at least 60 million barrels of oil is in sight and will be produced from the thicker sands by present recovery methods. In the thinner sands and edge properties, some 35 million additional barrels can be produced at a profit only if prices become higher. In view of the fact that there is little hope of finding new oil pools in New York, one of the future problems of the oil producer will be to obtain adequate returns for increased production costs. The year started with a posted price of $2.15 per barrel of crude. There were five successive price increases until the high of the year was reached at $2.98 on Aug. 14. Eight days later the Office of Price Administration directed that the price be reduced to the June level of $2.75 a barrel, which remained in effect to the end of the year. With rising costs of operation, it is feared that many of the smaller properties cannot continue production unless the Federal price cut is revoked. During the year, Allegany Refiners Inc., a local enterprise founded in 1933, with plant at Bolivar, western Allegany County, increased its refining capacity from 1000 to 1500 bbl. daily. At the same time equipment was added to make the plant a complete lubricating-oil refinery, including facilities for the refining of wax into the finished product. Previous to the enlargement, it was necessary to sell the wax

Jan 1, 1942