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By Kenneth Schellinger

THE terms surface tension and surface energy are well known when applied to liquids and are generally described by referring to the excess energy of the air: liquid interface as a result of unsaturated molecular forces surrounding the surface molecules of the liquid due to the presence of the air phase on one side. Such unbalanced forces produce the familiar water droplet of spherical form and are generally summed up as a surface tension measured in dynes per centimeter which can be shown mathematically to be equal numerically to a corresponding surface energy expressed in ergs per square centimeter. A specific surface energy, however, is best thought of as the energy necessary to produce one unit, of new surface on a substance. Hence, in producing a bubble in a flotation cell the impeller must supply surface energy corresponding to the air: liquid interfacial area on the interior of the bubble. Inasmuch as it is relatively easy to extend or contract the surface of a liquid, there are a number of successful methods for liquid surface tension, or energy, measurement based upon surface deformation. This happy state of affairs does not, however, extend to solids, which are considered to possess surface energies for the same reasons as do liquids, i.e. because of unsaturated ionic bonds at the solid: gas interface. As in the case of the flotation cell producing surface on liquids as new bubbles, it takes energy to produce new surface on solids as new particles. As every mill man knows, this surface is produced on mineral solids in a grinding mill by the action of a tumbling mass of iron balls. But here so much energy usually is wasted by the inefficient action of these balls that a large amount of heat is generated, and the surface energy production may be easily confused with the energy necessary to produce this ineffective heat. The tumbling balls and fracturing minerals ultimately take their energy from a rather large electric motor. It has been variously estimated that from 10 to 20 pct'" only of this energy from the motor does not appear as heat and may be presumed to appear as surface energy on the min- erals present. Such a production of new surface on the mineral phases is accompanied, of course, by a size reduction that is inevitable as more and more mineral interior molecules become surface molecules by the fracture exposure. This size reduction of mineral particles, although the most obvious feature and perhaps the sole object of the milling operation, is from this energy viewpoint the outward manifestation of the production of surface energy only. Measurement of the characteristic surface energies of pure minerals and their various mixtures in ores would be a step towards understanding of the energetics of the commercial grinding operation. In addition, the characteristic surface energy of a mineral is probably a physical property specific for that mineral, and therefore, from a scientific standpoint, should be measured. It is interesting to note that, in contrast to the large body of work on the surface tensions of liquid systems and biological systems, the field of solid surface energies has been neglected. Prior to 1920 it is difficult to find more than one or two references to work on solid surface energies in Chemical Abstracts. Since 1920 such references number somewhat less than 100, while those on liquid systems are numbered in the thousands. Much of this apparent neglect of the field of solid surface energies (the term is intended to be somewhat inclusive at this point and refers both to the solid: gas, and the solid:liquid interface) is because of the lack of a reliable method of measurement rather than any lack of scientific curiosity. It was, and still is, difficult to produce new surface on a solid without the simultaneous production of interior changes in the same solid which may consume part of the energy used. The extension in the surface area can be measured, but the interior crystal-

Jan 1, 1953

By C. P. Lawhon, J. P. Simpson, W. M. Evans

Data obtained under controlled test conditions using a microbit drilling machine showed that oil emulsified in water muds may either increase or decrease the drilling rate, depending upon drilling conditions. A low-viscosity oil such as diesel fuel can give drilling rates in limestone almost equal to that of water. Data obtained for water emulsified in oil muds showed little decrease in the drilling rate in water-saturated cores as the water percentage of the mud was increased above the 5- to 10-percent range. Changes in drilling rate were found to be dependent upon the oil or water concentration of the mud and upon the type of formation drilled. Changes in static filtration on paper (API filtrate) did not correlate with filtration while the mud was circulated across rock. INTRODUCTION Oil additions to water muds have been reported to increase drilling rates, provide hole stability and improve filtration control. Eckel' showed that water-base emulsion muds used in the West Texas area increased drilling rate with increasing oil concentration up to 15 percent oil by volume, but drilling rate decreased at a concentration of 20 percent by volume. Based on laboratory tests using water muds to drill shale, Cunningham and Goins' reported that drilling rates increased and tendency for the bit to ballup decreased with the addition of oil. Percentage increase in drilling rate varied with the particular formation. They showed oil additions to improve drilling rates ap proximately 75 percent in Vicksburg shale and as much as 150 percent in Miocene shale. Each investigation showed an optimum oil content for the particular formation. Most data that indicated improved filtration control due to oil additions were based on static API Eltrates through paper rather than dynamic filtration through permeable rocks. Some types of dynamic test give a better representation of filtration down-hole while drilling and might be more likely to show some correlation with drilling rate. Static filtration would be important, of course, in relation to hole stability and formation damage. This laboratory's drilling tests, conducted on water-raturated Berea sandstone, indicated that improvements in drilling rate were not evident with increasing oil concentration in water-base muds. Investigation also showed similarity between oil-emulsion (water-in-oil) muds and water-emulsion (oil-in-water) muds while drilling these formations. In Lueders limestone high concentration of water-in-oil muds and high concentration of oil-in-water muds provided the same relative drilling rates. In Berea sandstone there was a large reduction in relative drilling rate with both the oil and water muds that contained low percentages of emulsified fluid. Dynamic filtration rates of water muds on rock did not always decrease with increasing oil percentages even though the static API filtration rates on paper did decrease. Data observed in laboratory drilling of limestone and sandstone indicate that improvements in field drilling operations when water- or oil-emulsion muds are wed may not be the result of increased drilling rates but of improved hole conditions. In some cases, actual drilling rates might be slower but improved hole conditions will result in less total time on the hole. DEFINITIONS Mud pressure—Pressure of drilling fluid as measured after leaving the drilling chamber. This is considered as the approximate mud pressure just past the bit and at the face of the formation. Terrastatic pressure—Pressure representing weight of overburden. Formation pressure—Pressure of formation fluid as measured at outlet of drilling chamber. This is considered as approximate pressure of fluid in the pores of the formation. Differential pressure—Difference between the mud pressure and formation pressure. Relative drilling rate, percent—Drilling rate with experimental fluid divided by drilling rate with water times 100 equals percent. LABORATORY EQUiPMENT AND TESTING PROCEDURES The drilling equipment has been described in previous publications The microbit drill is a closed system (capacity, approximately 7 gal) that can be pressurized to 15.000 psi and heated to 500F. Main components are a drilling chamber, filter-heater, rotary-drive and variable-speed cir-

By T. S. Plaskett

A striated structure perpendicular to the growth axis was observed by the copper-decoration tech-nique in dislocation-free, .float-zoned silicon crystals. The striations, which were spaced about 100 p apart, fitted the relationship d = f/u , where d is the spacing, f is the growth rate, and u is the crystal rotation rate. Each stria was resolved into an UNDOPED silicon crystals pulled from quartz crucibles by the Czochralski technique usually exhibit a striated structure perpendicular to the growth axis.'-' This structure has been attributed to oxygen segregation, with the oxygen being introduced from the quartz crucible. If the crucible is rotated, the level of oxygen contamination has been reported as high as 10° atoms per cu cm.10 These striations are similar to solute striations commonly observed in doped Czochralski-grown crystals. The periodic nature of the striations is caused by a periodic variation in the growth rate",12 which is attributed mainly to thermal gradients in the melt.13 A finer striated structure14 attributed to constitutional supercooling is sometimes observed between the coarse striae. The oxygen striations have been observed by infrared transmission techniques,' by the copper-decoration technique,' by X-ray diffraction microscopy,6-8 and by 9 p absorption measurements3 on crystals pulled from the melt both with and without dislocations. In this investigation float-zoned dislocation-free crystals were examined by the copper-decoration technique. The level of oxygen for float-zone material is less than 1016 atoms per cu cm the lower limit of detection by 9 p absorption measurement. EXPERIMENTAL TECHNIQUE The crystals were grown by the float-zone process with the rf heating coil outside of the quartz envelope containing the silicon. All float zoning was done under an atmosphere of purified helium. The Dash technique15 was used to grow the crystal dislocation-free. This involves growing the crystal initially with a diameter between 2 and 3 mm and at array of starlike precipitates of copper. The strucLure was not .found at the surface tor a depth of about 1.5 mm, or in a region of similar width ahead of a dislocation network. The structure is postulated to consist of vacancy clusterings or dislocation loops. very rapid rates, about 20 mm per min, for a distance of about 3 cm. The diameter of the crystal is then increased to the diameter of the source of silicon, which in this case was about 19 mm. Because of the arrangement of the apparatus, the zone was passed downward rather than upward, contrary to the standard float-zoning practice. Also, the source was rotated rather than the seed. ziegler17 has made dislocation-free crystals by a similar technique but has passed the zone upwards. The starting material was zone-refined and had a p-type resistivity of 150 ohm-cm. The major impurity was boron; the total impurity excluding the boron was reported by the supplier (Dow-Corning) to be typically less than 2 x 1013 atoms per cu cm. The crystals were examined by the Dash copper-decoration technique18'19—a method in which about 10" atoms per cu cm of copper are diffused at a temperature between 900" and 1000°C into silicon which is then quenched to room temperature. On quenching, the copper precipitates on crystalline defects which are then visible when viewed by transmission infrared microscopy. The photomicrographs shown were taken either of the infrared image tube screen or directly on infrared film. All sections prior to decorating were chemically polished and, for some sections, given a sirtlZ0 dislocation etch-pit examination. After decorating, the samples were mechanically polished. RESULTS A photomicrograph, taken in transmission of a decorated cross section, is shown in Fig. 1. The portion of the section shown is near the surface of the crystal. The entire cross section showed no dislocation etch pits after being given a Sirtl etch treatment. It is seen that the copper precipitated randomly. Each precipitate, as has been reported by others, was found to have a starlike structure.

Jan 1, 1965

By W. A. Hoyer

A pulsed high-energy neturon-induced spectral logging tool has been built and field-tested. The reaction of deuterium on tritium is used to generate pulses of 14-Mev neutrons. By detecting only the prompt gamma rays produced by neutron inelastic reactions in the formation, the presence and relative abundance of carbon, oxygen, calcium, silicon and other important elements may be ascertained from a gamma-ray spectrum. Gamma-ray spectra obtained in a shallow test well and in experimental field use show that it is possible to identify formations and their contained fluids. INTRODUCTION The penetrating gamma rays from naturally occurring radioactive elements in subsurface formations have been used for a number of years in well logging as a means of characterizing and distinguishing strata. Still another nuclear logging method which has been employed for some years consists of the bombardment of strata with neutrons and the measurement of the number of gamma rays produced by neutron capture reactions involving elements in subsurface strata.' Since one of the principal elements entering into capture reactions is hydrogen, the latter procedure essentially results in a hydrogen log, whether the hydrogen be in combined form in either oil or water; thus, the log gives an indirect measure of porosity. These methods, with various refinements, have been developed to such an extent that they have become routine procedures in formation evaluation. Neither gamma-ray logging nor conventional neutron logging, however, yields sufficient information to permit unequivocal identification of the mineralogic composition of formations, and neither method gives information which may be used for the positive identification of hydrocarbons in strata. Accordingly, a number of efforts have been made in recent years to gain additional information from nuclear logs. Brannon and Osoba have shown that it is possible to identify naturally occurring radioactive elements in subsurface formations by spectral analysis of gamma rays emanating from these elements. Such an identification is of value in the characterization of strata. A simplified form of spectral analysis of gamma radiation resulting from neutron capture reactions between elements in earth materials and bombarding neutrons has been used with some suc- cess under favorable conditions to differentiate between petroleum and water. This method relies upon the relatively high energy of gamma radiation from neutron capture by chlorine and, in effect, furnishes a chlorine log. In areas in which interstitial water is of sufficiently high salinity, this log can give valuable information on water saturation and, thus, indirectly on hydrocarbon saturation. Still another approach to obtaining more information by nuclear techniques is "activation logging", in which certain elements yield short-lived radioactive isotopes on neutron activation and, thus, can be detected by gamma-ray spectral analysis. From the standpoint of determining by nuclear logging methods the mineralogic composition of strata and the presence or absence of hydrocarbons, it is essential that information be obtained on the presence and relative amounts of several elements such as carbon, oxygen, hydrogen, calcium, silica and others. Some elements, such as hydrogen, chlorine and sulfur, can be determined by spectral analysis of gamma radiation resulting from neutron capture reactions."" Others — carbon and oxygen, for example — do not enter readily into capture reactions but do yield gamma rays of characteristic energies from inelastic scattering reactions with high-energy neutrons. Accordingly, the latter reactions are of particular interest as a means of identifying hydrocarbons in subsurface strata. Several years ago it was recognized that information requisite to the identification of subsurface strata and of contained fluids could be obtained by pulsed operation of a subsurface neutron generator and associated gamma-ray detector. It was contemplated that pulsed operation would be effective in discriminating in time that gamma radiation which results predominantly from inelastic scattering reactions from that gamma radiation arising from neutron capture reactions. Accordingly, research was continued and construction of such a device was initiated. Although many problems were encountered, they were solved successfully. The following sections describe the tool which has evolved, its performance and the results which have been obtained with it to date. THEORY OF OPERATION OF NEUTRON-INDUCED GAMMA-RAY SPECTRAL LOGGING TOOL THEORY OF INDUCED NUCLEAR REACTIONS Of fundamental importance is the fact that an element, when bombarded with neutrons, emits gamma radiation of energy characteristic of that element. In theory, therefore, an element may be identified by

By J. Lohrenz, C. R. Clark, B. G. Bray

Procedures to calculate the viscosities of in situ reservoir gases and liquids from their composition have been developed and evaluated. Given a composition expressed in methane through heptanes-plus, hydrogen sulfide, nitrogen and carbon dioxide together with the molecular weight and specific gravity of the heptanes-plus fraction, the procedures are capable of calculating the viscosity of the gas or liquid at the desired temperature and pressure. The procedure for reservoir liquids was developed using the residual viscosity concept and the theory of corresponding states, and was evaluated by comparing experimental and calculated results for 260 different reservoir oils ranging from black to highly volatile. The average absolute deviation was 16 per cent. This is the first known procedure for calculating the viscosity of reservoir liquids from their compositions as normally available, i.e., including the heptanes-plus fraction. The procedure for reservoir gases uses a sequence of previously published correlations. Evaluation of the procedure was accomplished by comparison of 300 calculated and experimental viscosities for high-pressure gar mixtures in the literature. The average absolute deviation was 4 per cent. The calculations are useful for (I) determining viscosities in compositional material balance computations and (2) predicting the viscosity decrease which occurs when gases, LPG, or carbon dioxide dissolve in reservoir oils. INTRODUCTION Methods to predict viscosities of reservoir fluids from the normally available field-measured variables have been presented. Beal,1 Standing,2 and Chew and Connally3 orrelated oil viscosities with temperature, pressure, oil gravity and gas-oil ratio. Carr, Kobayashi, and Burrows4 and Katz et al.5 have presented correlations for reservoir gas viscosities as a function of temperature, pressure and gas gravity. Lie all intensive physical properties, viscosity is completely described by the following function: Eq. 1 simply states that viscosity is a function of pressure, temperature and composition. These previous correlations1- hay be viewed as modifications of Eq. 1, wherein one assumes more simple functions may be used. The assumptions are practical, because the composition is frequently not known. Further, the assumptions are sufficiently valid so that these correlations are frequently used for reservoir engineering computations. In compositional material balance"' computations, the compositions of the reservoir gases and oils are known. The calculation of the viscosities of these fluids using this composition information is required for a true and complete compositional material balance. For reservoir gases, Carr, Kobayashi and Burrows4 have presented a suitable compositional correlation. For reservoir oils, no correlation is available, and data from reservoir fluid analyses have been used7-9 for compositional material balance calculations.* From a theoretical point of view, this is entirely invalid. The reservoir fluid analysis, whether flash, differential, or other process, does not duplicate the compositions which occur during the actual reservoir depletion process, therefore the viscosities measured during reservoir fluid analysis are not those which occur in the reservoir. From a practical point of view, the "error" of using viscosities from reservoir fluid analysis is of varying and unknown significance. One can say qualitatively that the error is greatest where compositional effects are greatest, i.e., for volatile oil and gas condensate reservoirs and pressure maintenance operations. The first requirement to obtain a quantitative estimate of the significance of the error is to develop a reliable compositional correlation for the viscmities of reservoir oils. No such correlation has been available. Consistent with this requirement, the objective of this study was to develop a procedure to predict the viscosity of reservoir fluids from their compositions. Normally, the compositions of reservoir fluids are available expressed as mole fractions of hydrogen sulfide, nitrogen, carbon dioxide and the hydrocarbons methane through the heptane-plus fraction, with the average molecular weight and specific gravity of the latter. The final correlation was to use the composition in this form. While the more challenging objective of the study was the development of a correlation for the viscosities of reservoir oils, the viscosities of reservoir gases were also studied. The end result of the study was a procedure to calculate the viscosities of reservoir gases and liquids suitable

Jan 1, 1965

By James Boyd

Scientists and engineers must concern themselves not only with technical problems, but with the socio-economic difficulties of our scciety. The author states that raw materials are basic to the economic process and that mineral raw materials occur naturally in nearly limitless quantities. He feels that the economic pocess will provide sufficient raw materials for man's needs, and discusses in some detail the world economic environment. As our society grows in complexity, it becomes more urgently incumbent upon scientists and engineers to bring their experiences to bear on the solution, not only of technical problems, but also on socio-economic difficulties. It is to this field that I have directed a large part of my energies. RAW MATERIALS BASIC TO THE ECONOMIC PROCESS There are certain premises, frequently overlooked, which bear emphasis. As economics concerns the production, distribution, and consumption of goods, so our whole society is based on raw materials. Without the basic extractive industries of agriculture and mining, there would be no economic problems with which to deal. This principle has been expressed as "All productivity is based on three factors: 1) natural resources, whose form, place, and condition are changed by the expenditure of 2) human energy (both muscular and mental), with the aid of 3) tools.77* It seems strange that such an obvious statement needs to be made. It is forgotten by all of us, however, at one time or another when we get involved in the complicated theories of economics dealing with the financial and fiscal policies of the various governments, in the financing of enterprises, in marketing, and in labor relations. Unless decisions in all of these fields are made with this, and the rest of the "Ten Pillars of Economic Wisdom," consciously in mind, the resultant policies are doomed to eventual failure, whether these are policies of individuals, companies, or governments. The economic process is basic to society. But economics and the social aspects of humanity are inevitably intertwined. If human needs are not provided for within the basic economic structure, conflicts arise to disrupt the most carefully laid social plans. Similarly, it is the failure of society to cope with basic economic prerequisites that leads to discord within the body politic and thus to eventual economic disaster. We who are engaged in the various aspects of the mineral industry, therefore, have a large part to play in society's future development. MINERAL RAW MATERIALS OCCUR NATURALLY IN NEARLY LIMITLESS QUANTITIES Throughout my career in and out of government, I have formed my decisions on two principles: 1) Fundamentally, all mineral raw materials exist within the earth's crust in quantities greatly exceeding man's needs; 2) Any problems of supply of these materials are primarily economic in nature. With respect to my first assumption, analyses by geochemists enable them to estimate the quantities in which each of the known elements exist in the earth's crust. One of the most cautious and famous suggests that the average copper content of the lithosphere to a depth of ten miles is about 55 ppm. If this is valid, then the lithosphere contains about 1.4 quadrillion (1.4 x 10 ") tons of copper metal — an unimaginable quantity. This is 8,500,000-fold that which has been consumed by man in his existence. To illustrate further, consider that the deepest copper mine in history went to about 9000 ft below the surface; the present copper mines of the world now average less than 1500 ft in depth. We can assume that in most continental land areas of the world it is technically feasible to mine to a depth of at least one mile. The land areas of the world to an average depth of one mile, then, contain 343 billion tons (343 x 10') of copper metal, or 2000 times that which has been extracted to date. I don't believe man will ever expend his energies to extract copper from rocks which contain only a few parts per million, but he knows that each element

Jan 1, 1968

By C. G. Dunn, P. K. Koh

THE primary recrystallization texture in cold-rolled silicon iron, which is the matrix texture for developing the Goss texture or the cube-on-edge texture by secondary recrystallization at temperatures near 900°C,1-5,21 has not been adequately described. Thus from the present available information, it is not possible to explain satisfactorily both the grain-growth selectivity of the matrix and the often observed magnetic torque curve, which itself provides some information on the texture. Also lacking is information on the special annealing texture that develops in this material when the annealing temperature is 1200°C or higher and the rate of rise to temperature is extremely rapid. From the work of May and Turnbull5 and from unpublished work, it was known that isothermal annealing near 1200°C tends to reduce the extent of secondary recrystallization and that a much weaker cube-on-edge texture results if appreciable normal grain growth replaces secondary recrystallization. Koh and Dunn6,7 have obtained additional information on complex primary recrystallization textures from further studies made after normal grain growth. In these instances the initial textures were retained during normal grain growth. A similar result reasonably could be expected in the present study except for the presence of a grain growth ihibitor1-5,8,9.21 and its tendency to allow only a few grains to grow. However, any information on the orientations of grains in the special annealing texture, even if far from representative of the initial matrix texture, would provide useful information on the nature of the matrix texture. In the present texture study the method of Newkirk and Bruce,10 which is based on the methods of Geisler" and Schwartz, 12 is used to obtain a complete (110) pole figure of the primary recrystallization texture. The high-temperature annealing texture is determined simply from the orientations of a large number of selected grains. The kinetic nature of the process that produces the annealing texture is treated elsewhere13 and it is shown that a form of secondary recrystallization with a very high rate of nucleation occurs during rapid annealing at high temperatures. EXPERIMENTAL PROCEDURE Commercial 0.014-in. cold-rolled silicon iron strip (3.16 wt pct Si), prepared by two stages of cold rolling with an intermediate short anneal, was given a decarburizing 3-min anneal at 800°C. Me-tallographic studies indicated complete recrystallization. Short-time anneals at 900° C and at higher temperatures proved that secondary recrystallization had not begun at 800°C, in fact, the short additional anneals were still in the induction period of secondary recrystallization. A rapid rise to an annealing temperature of 1260°C (2300°F) was obtained in a BaC12and NaCl fused salt bath. The structures that resulted from anneals in the range 12- to 1000-sec duration were relatively finegrained, even though the growth was a form of exaggerated grain growth13 or secondary recrystallization with a high nucleation frequency.= Many of the grains were large enough for an X-ray study using a 5-mil X-ray beam. A transmission Laue Camera and an optical-mechanical stage for moving the grains into the X-ray beam were used. A total of 325 grains were X-rayed in this manner and the grain orientations determined. Complete (110) pole figures were obtained for the primary recrystallization texture using CoKa radiation at 30 kv in the back-reflection range, such as (220) for (110) poles, as described recently by Newkirk and Bruce.10 The low voltage serves to reduce the spurious white radiation to a minimum. A filter of 0.001-inch iron foil was located in front of the detector slit for transmission and in front of the beam slit for back reflection. A new and improved specimen holder extended the useful tilting angle range for transmission to 70 deg instead of 60 deg as previously reported.' A torque magnetometer was used to obtain the magnetic torque curves for a number of l-in. diam disk specimens. RESULTS The (110) pole figure of the material after recrystallization at 800°C is shown in Fig. 1. The positions of the pole concentrations are found to be

Jan 1, 1961

By J. C. Holm

ALTHOUGH the main constituents of Portland cement are the oxides of calcium, silicon, aluminum, and iron, characteristics of the cement are seriously affected by such contaminants in the raw materials as magnesium, phosphorus, sodium, potassium, sulfur, and others of lesser importance. Sources of cement raw materials comprise a long list of minerals occurring in nature in various degrees of purity. The calcareous raw materials are generally limestone of purity varying from calcite to cement rock (a low-grade limestone of natural, almost correct chemical composition), chalk, marl, seashells, coral, and coral sand. The argillaceous raw materials supplying silicon, aluminum, and iron are mainly various forms of clay and shale, to which may be added silicious sand, iron ore, bauxite, or kaolin for minor adjustment of the chemical composition. The quality of Portland cement in this country, as in most parts of the world, is controlled by rigid specifications limiting both its chemical and physical characteristics, and cement manufacturers must comply with these specifications to market their products. Brandon Raw Materials: An unusual deposit of marl, limestone, and clay occurs 12 miles east of Jackson, Miss., near the village of Brandon. The deposit is of sedimentary origin and of relatively young geological age. Layers of marl vary from putty-like consistency to such hardness that it can be cut with a knife. Interspersed between the layers of marl are bands of limestone varying from very soft to hard. the compressive strength of the hardest layers exceeding 15,000 lb per sq in. The layers of marl range in thickness from a few inches to about 25 ft. The limestone bands seldom exceed 2 to 3 ft but often occur in thinner veins in the quarry face. Above the top layer of the deposit, which may be marl or limestone, a layer of clay ranges in thickness from a few inches to more than 20 ft. Part of this clay is harvested with the raw material to supply part of the argillaceous components, but most of it is stripped as overburden and wasted. A highly silicious clay of extreme fineness, harvested from the bottom of the quarry below the marl and limestone bands, is to correct the silica content. Fig. 1 shows typical examples of the interrelation of the various materials, based on drill logs obtained during exploration of the deposit. The marls vary in moisture content in the bank from 15 to 30 pct and contain up to 70 pct -200 mesh particles and up to 40 pct —10 p particles. A large percentage of the fine fraction is within the colloidal range, making the marl extremely sticky. The limestone beds range in hardness from that of the hardest marl to a medium hard limestone and in moisture content from 2 pct to approximately 14 pct. The line of demarcation is often difficult to draw and the moisture content is possibly the best means of classification. The ratio of soft to hard material is not constant throughout the deposit, but the average is approximately 70 pct soft to 30 pct hard material. Through the years this deposit had been repeatedly explored by cement companies and rejected as unsuitable for cement manufacture, mainly because of physical characteristics. In 1950, after careful exploration of the deposit and comprehensive laboratory and pilot plant tests of the raw materials, officials of Marquette Cement Mfg. Co. of Chicago were convinced that a practical and economical method of processing the raw materials had been devised and authorized construction of a new plant that began production in December 1951. Marl and limestone, common raw materials for Portland cement, usually occur in such a manner that they can be worked separately. Their harvesting and processing normally have presented no difficult problems, as standard equipment and methods are available for handling either sticky or hard materials. No other cement plant utilizes a deposit of the nature of that at Brandon, however, and for this reason no prior art was available for design. When properly blended, the raw materials produced an excellent cement without additives. Basic problems to be solved in designing the cement plant were:

Jan 1, 1957

By R. Q. Shotts

This paper is a review of recoverable reserves of bituminous coal in the Southern Appalachian area, according to the latest published estimates. A few comparisons are made, some apparent trends are discussed, and some comments are made regarding the limitations of present estimates. The definition of Southern Appalachian area used in this report is somewhat arbitrary. It includes all the bituminous coal deposits of Alabama, Georgia, and Tennessee. All of West Virginia has been excluded. The East Kentucky and Virginia counties included were selected in connection with a literature study the writer made in 1959 of possible coal supply areas for the Tennessee Valley Authority. The selected counties were considered to be the only ones from which TVA might expect to obtain coal. The availability of coal from some of these counties is doubtful, but no other East Kentucky counties were considered more than remote possibilities. With these limitations, the Appalachian area covered is that from which producers of electric power and steel and commercial coal users, located in the Southeastern U. S., may expect to obtain their supplies of coal. Of course, it is recognized that coal from the eastern interior fields is also available to many of these same organizations. RANK AND QUALITY OF THE COALS Practically all the coals in the Southern Appalachian region are of high volatile A bituminous rank. An occasional sample indicates a slightly lower rank, but such samples may be oxidized or otherwise not representative. Some thin beds in Lookout Mountain and Sand Mountain in Alabama and Georgia, are low volatile bituminous coals, but they have not been mined extensively in modern times. There is a possibility that some of the deeper beds along the southeastern edge of the Warrior field of Alabama are near the Low-medium volatile bituminous dividing line. The Sewanee bed and some other minor ones of the Southern Tennessee field, some of the lower beds in Virginia, many beds in Sand and Lookout Mountains in Georgia and Alabama, one or more beds in the Coosa field, possibly some lower beds in the Cahaba field, and most of the beds along the southeastern edge of the Warrior field and the southern end of the Sequatchie anticline of Alabama, are of medium volatile bituminous rank. The quality of the Southern Appalachian coals is highly variable. Some of them, particularly such prevailingly thin ones as the Black Creek bed of Alabama and the Straight Creek bed of Kentucky, are unusually low in mineral matter— probably the lowest in the U. S. With the exception of certain beds and local areas, Alabama and East Kentucky coals probably have as low average ash and sulfur content as can be found in any sizeable coal area in the country. The sulfur content of Southern Appalachian coals is also variable, but few beds are consistently high in sulfur. In Alabama, sulfur generally increases from southeast to northwest across the Warrior field, but this trend is not quite as clear in the other states. A few beds in Northern Tennessee are prevailingly high in sulfur. All Southern Appalachian coals are potential coking coals if they can be prepared to meet chemical requirements. Only a comparatively small part of the medium volatile A bituminous coal, but most of the medium volatile bituminous coal mined is actually used for coking purposes. An estimate of reserves of coking coal under the requirements of present practice, could be compiled comparatively easily, but this probably has never been done. The reserve of coal that can be coked as an ingredient of a suitable blend is probably many times the size of the reserves of coal that will yield suitable blast furnace and foundary coke without blending. WHAT CONSTITUTES ECONOMICALLY RECOVERABLE COAL RESERVES? When one first realizes the vast extent of the coal-bearing rocks in the Southern Appalachian area, (see Fig. 1) the thought is likely to occur that the supply of coal is inexhaustible. This is particularly true on realizing that in some of the basins of thicker coal-

Jan 1, 1962

By D. T. Camp, J. A. Clum

WITH experience, the indexing of back-reflection Laue patterns for cubic crystals is usually a straightforward matter. However, for noncubic systems where in general tables of interplanar angles are not available or when inexperienced personnel are involved, properly indexing a crystal is normally a tedious, time-consuming affair. The authors have written a digital-computer program which calculates and prints out a table of interplanar angles for an arbitrary crystal structure and then systematically searches through this table attempting to obtain a consistent fit to back-reflection Laue data supplied by the user. Of course it is possible simply to calculate a desired set of interplanar angles should this be the only requirement. The program was originally written in ALGOL for use on a Control Data G-21 computer and a preliminary version is described elsewhere.' A version in FORTRAN TV which has been run on an IBM 7040 and one in FORTRAN II run on an IBM 1620 are also available. While it is not the purpose of this communication to describe the program in detail, an indication of how the program operates may help one to decide whether the program would be useful under particular circumstances. The hypothetical example chosen involves the indexing of the zinc crystal which has a hexagonal structure and a c/a ratio of 1.856. Input data for this example consists of only nine cards: The first card controls the list of families of planes to be considered. If the Miller indices of a prospective family are (h k 1), the first digit places a limit, in this case 3, on the absolute values of any individual index. The second digit limits the sum (h +k + l + 1), in this case to 5. Therefore the families (013) and (112) are considered but the family (122) is not. All systems, including the hexagonal, are treated using three-digit Miller indices. The second card contains the crystallographic parameters required to define the system. The first digit is 0 if the system is rectangular, that is all angles are 90 deg. If the system is nonrectangular, as in this example, the digit 1 so indicates. The next three values are the lengths of the sides of the reference cell, a, b, c. The final three entries on the card are the angles, a, 8, y between the sides. The digit 0 on the third card indicates that more data follows, the digit 6 shows that a set of six planes is to be indexed, and the value 2.0 indicates that agreement between a tabulated angle and an input angle is considered adequate if their absolute difference is less than 2 deg. The fourth card lists the measured input angles. a12 = 38 deg, a13 = 24 deg, and so forth. More input angles are listed on cards five to eight with the latter giving the input angle 058 = 40 deg. The final card in this series indicates by the digit 1 that no more data is to be processed. The program operates in the following manner: 1) The input data from cards 1 and 2 is read, thereby indicating the crystal system to be examined and the crystallographic parameters of the particular crystal to be indexed. 2) A table of interplanar angles is generated. 3) The input angles contained on cards 4 to 8 are read. 4) The measured input data is systematically compared with the generated table of standard angles. All combinations of poles whose interplanar angles compare with the requisite, specified accuracy are printed out. If no adequate fit is found an indication of this is printed. A typical line from the generated table of interplanar angles is: (001) - (111) 74.92 64.99 It can be shown that in the Miller-Bravais system the first value corresponds to the angles between (0001)-(1121) and the second to that between (0001)-(1011). This particular set of data gave the following result for the planes 1 to 6: (011) (110) (121) (111) (112) (010) The ALGOL version also has the option of simply providing the Greninger-chart coordinates ? and 6

Jan 1, 1967

By G. W. P. Rengstorff, H. B. Goodwin

A method is described for purifying iron in batches of 150 Ib or more. Oxygen, carbon, nitrogen, and sulphur are removed from flakes of electrolytic iron by treatment in wet and then dry hydrogen. A special consumable-electrode arc furnace is used to remove hydrogen and to melt the flakes into ingots. A LTHOUGH iron and steel have been made and used for hundreds of years, there are still wide gaps in the knowledge of these metals. One reason for this is that the true properties of the base metal, iron, are not well known, simply because really pure iron has never been readily available for research purposes. Commercial iron, and even the "pure" irons which are readily available, are really complex alloys of iron with oxygen, nitrogen, hydrogen, carbon, sulphur, silicon, and other elements. With such materials, it has not been possible to prepare steels and other iron-base alloys in which all elements are present in exactly controlled amounts. It is an almost impossible task to determine the separate effects of each element or the intereffects of several elements unless alloys can be prepared containing only the desired elements. The ability to make controlled alloys of low impurity content is of far more than academic interest. It will assist in the study of such practical problems as the brittle failure of ship hulls or high pressure gas pipelines, determination of the factors which affect the deep-drawing properties of steels, the improvement of magnetic and electrical properties, the phenomenon of aging, and many others. In 1949, the American Iron and Steel Institute asked Battelle Memorial Institute to prepare high purity iron on a larger scale than had been attempted up to that time. The work was directed toward the preparation of iron as low as possible in carbon, oxygen, nitrogen, hydrogen, and sulphur because these are the contaminating elements of major interest in many research investigations on iron-base alloys. The initial goal was to prepare iron with not more than a few thousandths of one percent of each of these impurities. The purpose was to set up a "bank" of high purity iron on which researchers could draw when a supply was needed and which could be replenished from time to time as the stock became depleted. Of several possible purification methods, heating in hydrogen was selected as the most promising for the removal of both carbon and oxygen from solid iron. Metallic impurities are not removed by hydrogen. Electrolytic iron was chosen as a starting material because it is the most readily available form of iron low in metallic impurities. Decarburization and desulphurization were obtained by annealing in wet hydrogen at relatively low temperatures. The optimum temperature, as found by previous investigators,' is about 1400°F. This treatment also removes nitrogen. Deoxidation is favored by dry hydrogen and higher temperature. There is evidence from previous work that an anneal at 2200°F in dry hydrogen will deoxidize the iron, reduce the nitrogen content, and reduce the sulphur content. These facts suggested the use of a two-stage process: treatment in wet hydrogen followed by treatment in dry hydrogen. To carry out the purification process in a reasonable time, it was necessary that the iron be in thin pieces. Flakes of electrolytic iron were used. Because most research requires that the iron be in massive form, it was nccessary to melt the purified iron to consolidate it into large pieces. For this work, it was decided to prepare ingots weighing at least 15 lb by using a cold hearth arc-melting process in which the iron was melted in an inert atmosphere of argon or helium. This method of melting was selected because the water-cooled copper crucible is not wet by the iron and does not contaminate it as a refractory crucible would. Because the crucible is also the ingot mold, contamination from mold materials was also eliminated. Contamination from electrodes was avoided by making them from purified electrolytic iron. The melting procedure finally developed was an adaptation of the Kellogg electric ingot process.' Two batches of purified iron weighing about 100 Ib each in ingot form were prepared with analyses as shown in Table I. The remainder of this paper describes the procedures in more detail. In general, the process con-

Jan 1, 1956

By R. D. Russell, R. M. Farquhar

SOTOPIC tracers have become an important aid in following the progress of chemical processes in the laboratory. It has recently been found possible to utilize a system of naturally existing iso-topic tracers to obtain information about the geological history of lead ores. Common lead, such as is found in lead deposits, is a mixture of four stable isotopes having atomic weights 204, 206, 207, and 208. Of these, the last three are identical with the lead isotopes produced as stable end products of the radioactive decays of uranium and thorium: the first, lead-204, is not known to be produced on the surface of the earth by any process. Since uranium and thorium Occur in the surface regions of the earth in amounts comparable with lead, and since the half-lives of uranium and thorium isotopes are of the same order as the age of the earth, they produce the radiogenic lead isotopes in amounts comparable to the amount of nonradiogenic lead present. Every significant exposure of a sample of lead to uranium and thorium will therefore lead to the permanent alteration of the lead isotope ratios in that sample. It is this unique property of lead that serves as a means of tracing the history of a lead sample in terms of its contacts with the radioactive elements. If lead from a lead mineral has been analyzed with a mass spectrometer, the measured isotope ratios are determined entirely by the isotope ratios of primeval lead, which are identical for all minerals, and by the particular history of the sample. It follows that for samples from any particular geological area, observed differences in the isotopic composition are enough to distinguish different geological histories. An illustration of the qualitative application of this statement is given in Table I by analyses of some galenas from the western Cordillera. Samples from deposits in Pre-Cambrian sediments have very different lead isotope ratios from those of the ores in the Paleozoic sediments. Although the two types are associated closely geographically, it is apparent that they have had quite different histories and have probably been emplaced at quite different times, as the ideas outlined in the following section suggest. Even when applied quantitatively, a lead isotope analysis can never indicate a unique history of any lead sample. However, it greatly restricts the choices available and combined with other geological and geochemical data can lead to a much better understanding of the genesis of lead ores. General Character of Lead Isotope Variations: Early isotopic analyses of common leads by Nierl showed that geologically younger leads were generally richer in isotopes of masses 206, 207, and 208, with respect to that of mass 204. This regularity of measured lead isotope ratios can be easily observed by plotting each of the ratios Pb207/Pbm and Pb205/ Pb204 against the ratio Pb206/Pb204. In both graphs the points lie scattered closely about a well defined mean curve. It was immediately supposed that this regularity resulted from the growth of all leads from a common primeval lead present at some time, To, early in the earth's history. Lead in the outer part of the earth would become continually enriched in the radiogenic isotopes as a result of the uranium and thorium intimately associated with it. The subsequent extraction of some of this lead and formation of a lead mineral free of the radioactive parents provide samples of lead existing in the earth at the time of mineralization, T. Younger leads in general will be richer in the radiogenic isotopes because they have been associated with uranium and thorium for a longer time. Then lead ratios would be given by the formulae: (Pb206/Pb204)YTPb^/Pb204) +f "(u201) kdt T (Pb207Pb204)r = (Pb208/Pb204)T0 + J (U295/Pb204) k' dt T (Pb208/Pb204) t = (Pb208Pb204 + J (Th204) A." dt [1] where A, A', and A" are the decay constants of U238, U285 and Th232. Summaries of measurements of radioactivity of surface rocks, such as given by Faul,2 are of limited

Jan 1, 1958

By Josiah Royce

To evaluate chemically the sample of rock obtained by diamond drilling, it has long been recognized that the analyses of the two components of the sample, core and sludge, must be given appropriate influence in computing the average analysis of any unit of depth. The purpose of this investigation is to set forth what means are available for apportioning the effect of core and sludge on the final analysis, what variables affect the problem, and what combination of applied mathematics will closest approximate the truth under each condition as these variables proceed within their limitations. A drill hole is bored in iron ore exploration principally to test variations in rock composition with depth and is usually directed as nearly normal to the bedding of a horizon to be tested as possible. This practice has a tendency to minimize variation in composition laterally which in any event is not likely to be great. It is obvious that the opportunity for change in analysis of a particular rock is not statistically as great radially in a diamond drill hole where the distance in which such a change may occur is from 0.719 in. (EX bit) to 1.469 in. (NX bit) as there would be longitudinally even in a' run as short as 5 ft. Variations in composition of bedded or layered rocks are usually greater normal to the bedding than parallel thereto. Even in massive rocks, like porphyries, variations are functions of distance. Hence. in either case, variations along the hole are of greater effect than across it. Let us examine Fig 1 briefly to observe a cross section of a unit of depth of a typical diamond drill hole. If we neglect radial change in chemical composition, which we have seen is small compared to lengthwise variation, we can see that if core recovery was 100 pct, the core and its surrounding area, which would be recovered as cuttings (assuming 100 pct sludge recovery), must analyze the same if the sampling is perfect. This is the foundation of this paper, namely, that if core recovery is complete we may assume that the core constitutes as nearly as possible a perfect sample of the ground drilled. Now let us pass to the methods of weighting core and sludge in the final analysis and then develop each in turn. One might employ core analyses only, sludge analyses only, or apportion the influence of each by one of several methods. The most common apportionment is by direct proportion to relative theoretical vol- ' ume occupied by each component in the cylinder hollowed out by the drill, known as the Longyear formula. Another logical treatment would be to consider core and sludge in the final analysis according to the weight of each recovered. This procedure was elaborately set forth and refined by R. S. Moeh1man.l Then to be sure that we have embraced all the possibilities, we must admit that some other method or methods may be devised empirically or by mathematical maneuvers. Should a drill machine be capable of recovering 100 pct of the core in all types of rock, certainly core alone need be analyzed and no complicated mathematics are required; but although some companies have had fair success in obtaining high percentages of core in certain homogeneous ores on the Mar-quette Range, their same methods have proved disappointing on the Menominee, Cuyuna, and Gogebic Ranges where the iron formation often varies widely from flinty chert beds interstratified with soft hematite to wholly leached ore material composed of an unpredictable mixture of hematite and limonite with occasional zones of sugary, recrystallized chert. In spite of numerous mechanical improvements in core barrels, few drilling programs can count on complete core recovery. The sludge alone might be analyzed but for practical reasons this is inadvisable when core is obtained due to the numerous opportunities for contaminating or losing portions of the cuttings. The Longyear formula involves a weighting of the core and sludge in proportion to the theoretical volume of each, that is, where the volume of the core recovered is one-third of the total cubic volume of the cylindrical hole made by the drill, the analysis of the core is given one-third of the weight in the final analysis. This approach to

Jan 1, 1950

By Edward Hanrahan

September 1981 I'm here today to report on a revolution -- a revolution in the way the Federal Government looks at energy. I'm not talking about a simple change in the relative emphasis on sources -- such as more recognition for coal and nuclear power, with less rhetoric about "soft- technology." Nor am I describing a mere change in focus -- from the demand side to the supply side. And I am not referring exclusively to our obvious goal of budget cuts. No, I'm here to discuss a fundamental change in Federal direction -- one that started as soon as President Reagan was inaugurated, and one that is articulated in the National Energy Policy Plan he sent to Congress in July. That brief policy document was backed up by three volumes of supporting data; but I think I can catch it's flavor for you in just three phrases: * First, various energy forms complete with each other and complement one another. * Second, fair competition among them (which includes honest pricing) will give us the best "energy mix." • And, finally there may be ligitimate arguments about where Federal responsibility in regard to energy spills over into Federal interference; but it's about time we drew the distinction -- and eliminated the latter. This Administration's national energy policy is quite different from any we have had in recent years. It is tuned to human nature and changing times. We are seeking the best practical solutions in the energy -a lot better than the ones we have been offered before, but still something less than perfection. One way we do that is by counting on a fully informed public to guide it's own destiny. And, instead of treating energy as an isolated entity, we recognize it as part of the overall economy. The President's Program for Economic Recovery is as much a factor in energy policy as the specific actions of the Department of Energy. One striking difference from the past energy policy 1s that this policy plan does not say: "In 1985 we will -produce so many hundreds of millions of tons of coal: . . . or . . . "By the end of this century the Nation will be deriving X percent of it's electricity from wind generators." Unfortunately, targets like these are what many people have come to expect from the Federal Government -- and what they think of as energy policy, whether the figures hold up in the long run or not. But . . . think about it! Nether the Department of Energy nor any other part of the Federal Government produces coal, or mines uranium, or manufactures solar collectors. There are only a few sections of the country where the Federal Government generates and sells electricity. So it does not take any great insight to recognize that the amount of energy we will produce or consume as a Nation In the future depends on many factors beyond direct government action. And those future totals cannot be predicted precisely, anyway -- by the Government or by anybody else. According to our way of thinking, the choices should be up to the people. When the free market works within a healthy economy, individuals express their preferences in the marketplace -- adjusting the balance of all energy factors continually in a way that no computer could be programmed to reflect perfectly. So, instead of having the Government issue a rigid set of numerical goals, our main concern simply is that there be enough energy. We want the Nation itself to decide how much that should be, what form it should take, and how that energy should reach consumers. The marketplace decides. Considering the recent past, this is indeed a revolutionary idea. It has some pitfalls, and we won't reach this ideal of free choice overnight. But that is where we are headed. And I'll offer some evidence in a few minutes that the policy has already started working. First, let me give you some of it's highlights: 1) Nobody who appreciates the philosophical underpinnings of this Administration will be surprised that the energy policy shows faith In domestic energy production and the supply side of the economy; but it also recognizes the important role of energy conservation -- the wise and efficient use of energy resources.

Jan 1, 1982

By D. E. Wolfson, D. A. Reynolds, F. W. Smith

IN 1948 the U. S. Bureau of Mines began a three-phase program to evaluate the extent and quality of U. S. coking coal: 1) a factual appraisal of known recoverable reserves in beds of mineable thickness, 2) a study of preparation characteristics, and 3) a study of carbonization properties. A previous paper presented the methods used in assessing reserves.' Although this investigation is only partly completed, data on coking properties of the Pittsburgh district coals are now available. The results are presented in this article. When coals are selected for manufacture of metallurgical coke more factors must be considered than for any other major use, as no basic industry requires coal of such high quality and uniformity. This is particularly true in the Pittsburgh district, where blast furnace practice is based on use of cokes from high quality coals. Although it is true that inferior coals are carbonized in other industrial areas, both here and abroad, the Pittsburgh coals are the best economically obtainable in the required tonnages, even though they are not the most desirable for metallurgical use. In the general evaluation of suitability of coals for coke making, particular attention is given to: 1) reserve, 2) ash and sulfur content, 3) inherent properties of forming strong, well fused coke, 4) expanding characteristics, and 5) blending properties. Items 1 and 2 are covered in detail in the first two phases of the survey, and coking behavior is considered in items 3 through 5. Problems is Coal Evaluation: Although not all coal beds of immediate or potential use to the coking industry in the Pittsburgh area have been tested for their coking properties, enough tests have been made to permit certain generalized statements. Virtually all the coals that will be used in this district are from the Appalachian region, and except for high oxygen coals from outcrops or stripping operations, they are coking coals. Hence the evaluation problem is not so much that of distinguishing between coking and noncoking coals as attempting to measure quantitatively differences in the coking and expanding properties of the better coking coals. Quantitative differentiation between good coking coals, is complex, since differences in their coking abilities are frequently of about the same magnitude as the precision of the test. Small-scale tests are generally unsuitable for measuring these slight differences, and there has been gradual acceptance of pilot-scale tests. Test Methods Employed: All the data reported here were obtained in two units known as the Bureau of Mines-American Gas Association (BM-AGA) carbonization apparatus and the sole-heated expansion oven. The BM-AGA unit, which consists essentially of a cylindrical steel retort about 18 in. diam and 26 in. high, carbonizes enough coal (180 lb) to allow evaluation of the coke by standard methods of the American Society for Testing Materials. The BM-AGA carbonization procedure and methods of testing the gas, liquid, and solid products have been described.' Expanding characteristics of the coals were determined in the sole-heated expansion oven," wherein the coal charge, heated from the bottom only, is carbonized under a constant applied force and the linear expansion or contraction is measured. Although results in this oven have never been quantitatively correlated with the expansion behavior of coals in conventional slot ovens, they are useful in assessing expansion behavior. In this report discussion will be confined to results obtained from these pilot-scale units, although the following data are available for most coals: proximate and ultimate analyses, free swelling index, agglutinating value, and plasticity. Sources of Coals Tested: In selection of coals for coke manufacture, economic considerations are as important as quality, and each coke plant balances these two factors to meet requirements of the most satisfactory coke at lowest price. Although these economic factors may in some instances outbalance small differences in coke quality, they are usually specific to each coke plant and cannot be given in any general statement. Recognizing that coal and plant operating costs are beyond the scope of the survey, the USBM evaluates the coking quality of various coals without regard to their competitive economic status. For the purpose of this article, coals of interest to the Pittsburgh district are arbitrarily defined as

Jan 1, 1958

By H. W. Schull

The Alligator Ridge gold deposits are located in northwest White Pine County at the southwest end of Alligator Ridge. Alligator Ridge is on the west side of Long Valley in the range of hills that separates Long and Newark valleys. The nearest population center is Ely, about 113 km (70 miles) to the southeast. Access to the Alligator Ridge gold mine from Ely is via US Highway 50 and the Long Valley Ruby Marsh Road. The latitude and longitude is approximately 39° 45' north and 116° 30' west. The Alligator Ridge gold deposits occur in the lower 61 m (200 ft) of the Mississippian-Devonian Pilot Shale formation, a laminated calcareous carbonaceous siltstone. The gold deposits contain carbonaceous, oxide, and jasperoid type gold ore. For more details on the geologic features of the deposits, see Schull, Sutherland, and Ilchik (in press). The discovery story of Alligator Ridge began in the spring of 1976 when the areas mapped as jasperoid on the 1:250,000 scale geologic map of White Pine County (Hose and Blake, 1976) were examined and sampled. Seventeen samples, about 23 kg (50 lb), were collected from an area about 0.65 km2 (0.25 sq mile). Of these 17 samples 10 reported atomic absorption values of less than 0. 1 ppm Au and 7 reported values in the 0.1 to 1.0 ppm Au range. In June of 1976 20 lode claims were staked to claim the area of the rock chip sampling. The claims' end and side center lines were used as a grid for soil sampling. Sample stations were 91 m (300 ft) apart and sample lines were 229 m (750 ft) apart. The samples were sieved to - 180 µm (- 80 mesh). Out of 99 soil samples, seven samples reported Au values in the 0.1 to 1.0 ppm range. Of the seven auriferous samples, five were located over the jasperoid outcrops previously sampled; one over unmineralized Pilot Shale a few hundred m (ft) downslope from some Au-bearing jasperoid; and one from a 15 x 15 m (50 x 50 ft) talus outcrop area of hitherto unnoticed mineralized Pilot Shale. Subsequent sampling, mapping and drilling would show that this 15 X 15 m (50 x 50 ft) outcrop area was the top of the Vantage 1 ore body, about 1.27 Mt (1,400,000 st) of over 3 g/0.9 t (0.11 oz/st) Au. Late in the summer of 1976 about 30 more 1.4 to 2.2 kg (3 to 5 lb) rock chip samples were collected in the course of preliminary geologic mapping. This mapping and sampling showed that the gold-bearing jasperoids occurred at the contact between the Pilot Shale and the underlying Devils Gate Limestone. Rock chip samples of 0.1 ppm Au or greater were restricted to the jasperoids and the mineralized outcrop area of Pilot Shale located by the soil sample survey. Rock chip samples from the area of mineralized Pilot Shale were in the 3 to 5 ppm Au range. Activity resumed in the summer of 1977 with a more detailed soil geochemical survey. The jasperoid areas were defined as large geochemical gold anomalies of values greater than 0.1 ppm and locally greater than 0.2 ppm Au. Soil samples from the area of mineralized Pilot Shale outlined a greater than 0.1 ppm gold anomaly 61 x 152 m (200 x 500 ft) in size. Further geologic mapping showed that elsewhere, even where bleached and silicified, the Pilot Shale areas were geochemically very low in gold (less than 0.1 ppm Au). In November, 1977 twelve rotary percussion drill holes were drilled to test the gold-bearing jasperoid areas and the mineralized Pilot Shale area. Drilling of the jasperoid areas showed that the jasperoids gave way at shallow depths [less than 24 m (80 ft)] to unmineralized unaltered Devils Gate Limestone. A five hole cross pattern was drilled to test the area of mineralized Pilot Shale. Four of the five holes re-

Jan 1, 1985

By V. Koump, T. F. Perzak, R. G. Olsson

The rate of dissolution of recrystallized alumina in molten iron oxide in equilibrium with iron at 1450°C was studied by rotating alumina disks in the melt. The samples were rotated from 1 to 12 min at speeds from 54 to 3270 rpm. It is concluded from the experimental results that the process is limited by diffusion in the liquid boundary layer. The interdiffusion coefficient for the dissolution of alumina disks in pure molten iron oxide was estimated to be about 3 xl0-5= sq cm per sec. THE erosion of refractory materials is of considerable importance in iron- and steelmaking processes. Since many refractories contain alumina, this investigation was undertaken to develop a further understanding of the erosion mechanism. Shurygin et al.1-3 have investigated the rate of dissolution of alumina in molten silicates and molten fluorides by rotating alumina disks in various melts. The rates were reported to be limited by diffusion in the liquid boundary layer. In the present investigation the rate of dissolution of alumina in molten iron oxide in equilibrium with iron was studied in a similar manner; alumina disks were rotated at different speeds in molten iron oxide at 1450°C. The relationship between the rate of dissolution of the flat surface of the disk and the speed of rotation was used to determine whether the process is limited by diffusion in the liquid boundary layer or by some chemical reaction mechanism. APPARATUS AND EXPERIMENTAL PROCEDURE A schematic diagram of the experimental apparatus is shown in Fig. 1. The iron oxide melts were contained in 2-in.-diam high-purity iron crucibles that were centered in a cylindrical graphite susceptor. Prior to each sequence of experiments, sufficient reagent-grade ferric oxide was added to a crucible to form approximately 350 g of molten iron oxide; the depth of the melt was about 11/2 in. To prevent excessive erosion of the crucible, about 70 pct of the required iron was added to the crucible in the form of iron powder. The mixture was melted in an atmosphere of purified argon by induction heating with a 250-kc generator. After the oxide was molten, a Pt/Pt-10 pct Rh thermocouple at the exterior of the crucible was calibrated against an iron-sheathed thermocouple immersed in the melt and was thereafter used to regulate the melt temperature. All experiments were conducted at 1450°C with a probable error of 10°C. The alumina disks were constructed from pure re-crystallized alumina having a density of 3.7 g per cu cm (porosity approximately 6 pct). For each disk sample a 1-cm-diam alumina cylinder of known length (0.9 to 1.0 cm) was cemented into a ground seat at the end of a 1.27-cm-OD centerless ground alumina tube. The ends of the tube and cylinder were flush and served as the disk surface. When mounted in the apparatus the alumina tube was guided by tungsten carbide bearings and rotated by a variable-speed motor. The bearing and drive assembly could be raised and lowered in order to allow the sample to be quickly moved in and out of the melt. At the start of an experiment, a sample was preheated for several minutes directly above the melt, and then immersed in the middle of the melt to a depth of a in. and rotated for 1 to 12 min at speeds of 64 to 3270 rpm. The speed of rotation was measured by a hand tachometer. At the start and completion of each experiment, a melt sample was withdrawn with a cold copper rod and the alumina content was determined by chemical analysis. During individual experiments the alumina concentration of the melt changed by the order of 0.25 wt pct. Average melt compositions for individual experiments were used in the subsequent computations and were in the range between 0.12 and 4.3 wt pct alumina. The extent of dissolution was determined by sectioning the end of the sample and measuring the final length of the alumina cylinder with a microscope. Since the exposed end of the cylinder, i.e., the disk surface, was etched in a manner characteristic of this geometry, a number of measurements were made on

Jan 1, 1969

By Anthony Tuke

Members of the Society of Mining Engineers may well regard it as rather unusual that a paper on this subject is being presented by someone whose first taste of mining came at the age of 60 or so - someone who last heard of cathodes and anodes in 1938. On the other hand, the title does refer to the financing of a mine and at least I can claim to have spent all my business life since the war until 1981 in the world of banking, though this inevitably means that I have been used to looking at these and other problems through what you might regard as the wrong end of the telescope. The lending of money, and more particularly the provision of finance for commerce and industry, is the central job of a banker and I have been involved in this in various ways over many years, but regrettably only very marginally in the world of mining. As you will see from what follows, the rather specialised form of finance which RTZ required was, to my regret, not provided by the British banking community since the great majority of the finance came from American banks and, to a lesser extent, from German banks. I am most indebted to Mr. Roy Wright for a great deal of the nuts and bolts in this paper. He was one of the three central figures in the growth and expansion of RTZ during the 1950's and 1960's and was right at the centre of the negotiations with bankers, with governments and with many others. The going, as you will see, was far from easy. The essential basis for the financing of each of the RTZ group's mining projects was a firm long-term sales contract for sufficient of the output of the particular mine to produce the cash flow necessary to service the loans. Wherever possible, loans were raised in the same currency as the sales contracts were made. Each sales contract was designed to give the customer the product he wanted with a long-term assurance of supply and at the same time to give the bankers the protection they required. Thus the marketing concept and the financing concept for a particular mine formed one overall plan, and talks with the customers and the bankers were conducted in parallel until a satisfactory marketing/financial package was agreed in principle. Preliminary talks were begun soon after the discovery of a potentially viable orebody. As confidence about a discovery increased, customers were persuaded to enter into contingent sales contracts before the very detailed and costly business of the economic and technical feasibility study of the mine was launched; such a study might cost 10% or more of the estimated total capital cost. At the same time provisional understandings were reached with the bankers. The contingent sales contracts usually gave a period of grace of eighteen months to two years, during which time the decision whether or not to continue with the mine had to be made. This decision rested mainly on the result of the feasibility study and also on coming to a firm agreement with the bankers. If all went well and the mine went ahead, then the contingent sales contracts became firm, but they fell away if the decision was negative. The Company was fortunate that during the whole period when its major mines were being developed, world trade was increasing rapidly and Japan was becoming a dominant industrial power. The Japanese supported many of the mines, including Hamersley Iron Ore, Lornex Copper, Bougainville Copper to name a few, with the basic long-term sales contracts that enabled their development. The Germans supported Palabora and to a lesser extent Bougainville. The mines were financed as individual projects generally with a loan/equity ratio of about 65/35, without legal recourse to RTZ for the loans. RTZ was, however, responsible for providing any capital overruns required to bring the mines into commercial operations. Nevertheless, the RTZ management regarded itself as morally responsible to the lenders because, Palabora aside, the sales contracts had either a fixed selling price (like Hamersley), an indexed price (like the Elliot Lake Uranium Mines and Mary Kathleen), or a floor price (as in Lornex, Bougainville and Rossing). Thus the Company believed that any financial failure would have been due to poor management or technical

Jan 1, 1985

By M. R. Tek, K. H. Coats, D. L. Katz

The nature and the limits of validity of Darcy's law US applied to the flow of natural gas through reservoirs has been considered in order to resolve some controversial aspects of the effect of turbulence on pressure drops. The equivalence between various concepts and viewpoints advanced in the past by several investigators to explain how and why a gas well does not necessarily perform according to Darcy's law is shown. Starting with generalized equations of flow of fluids through porous media, a partial differential equation has been derived which accurately represents the flow at all rates. This equation has been numerically solved using an IBM 704 digital computer. The results permit plots of unsteady radial pressure distribution curves from which specific isochronal backpressure curves may be constructed. These back-pressure curves show the effect of the ,8 factor on the slope of the back-pressure curve. The calculations further indicate that the drainage radius for a gas well in turbulent flow propagates at a rate dependent upon the rate of production at the wellbore. This is quite different from the case with liquid flow or natural-gas flow in laminar regime. Additionally, the effect of reservoir inhomogeneities and crossflow between layers of different permeability on the back-pressure performance of gas wells has been conridered. In light of the current numerical results the significance and linlitation of the rate of flow function Y proposed by Smith" has been discussed. INTRODUCTION The relationship between the pressure drop and flow rate in problems of fluid flow through porous media is known to be affected by the nature of flow through the porous matrix. It has been observed by many that, for a range of flow rates, the pressure drop remains proportional to the rate of flow. When some flow rate is reached, however, it is usually observed that the pressure drop gradually begins to increase more than proportionally to the flow rate. It is well known that this phenomenon was first observed by Osborne Reynolds in 1901 in experimenting with flow through pipes. In his classical experiments, Reynolds made visual observations on the condition of streamlines evidenced by injecting a dye into water flowing through glass tubes. In these experiments, the abrupt transition between steady, "streamline, laminar" flow and unsteady random turbulent flow was found to be a function of the dimensionless group (Dvp/u), now known as the Reynolds number. During these experiments, in addition to observations on the nature of flow regimes, the proportionality between flow rate and pressure drop in laminar flow was contrasted with the nonlinearity between these variables in turbulent flow. Fancher and Lewis' reported data on various consolidated and unconsolidated sands in 1933. Their conclusions were that ". . . the flow of fluids through these porous materials closely resembles that through pipes; that there is a condition of flow in porous systems which resembles viscous flow, another which corresponds to turbulent; that the change from one type to the other takes place at a definite and reproducible condition for each system". In 1947, Brownell and Katz published a method to predict the laminar and turbulent flow behavior from the particle size, bed porosity and the particle sphericity, employing the friction factor-Reynolds number charts for pipes. Several investigators have verified the work of Fancher, Lewis and Barnes and presented their data as friction factor-vs-Reynolds number plots.' The equation which would represent the pressure gradient over the whole range of velocity must have an added term over that represented by Darcy's law. Accordingly, the pressure gradient necessary to sustain flow at the velocity (v) through a porous medium may be represented by the following equation, suggested by Forscheimer." The nature and the range of validity of Darcy's law has been the subject of studies by many investigators over the past years. While everyone seemed to agree on the need for a quadratic correction term to Darcy's law to make it effective over the range of velocities, the concept of inception of turbulence and the use of the term "turbulent flow" remained controversial. Some fluid dynamicists define turbulence as a flow

By A. L. Bailey, B. A. Landry

All who are even generally aware of the tremendous rate of increase in coal washing operations must realize the growing importance of the float-and-sink test. I believe it is conservative to estimate that, in the past decade, the dollar volume of float-and-sink testing has increased tenfold. It is a simple matter of economy, then, to examine the factors that determine the cost of adequate float-and-sink testing. When the Coal Preparation Section of the Bureau of Mines entered upon a greatly expanded program of such work in connection with the synthetic liquid fuels investigations, it seemed advisable to examine these factors experimentally. The principal consideration that differentiates float-and-sink test sampling from general purpose sampling, is that the original particle size must be preserved. Therefore, the total cost of the test will be directly affected by any standard that might be proposed to limit sample bulk reduction at any given particle size. For this reason, the relationship of sample size to variability of results was the first factor to be studied experimentally. Of course, the matter is rendered complex by the circumstance that the float-and-sink test, not a simple analytical measurement but a process test, comprehends a number of more-or-less independent items of fundamental data; and as shown in the report, the' variability of the samples differs with respect to these different items. This condition and the wide variety of situations in which float-and-sink test data are used, in combination with other factors, to study complex process operations, indicate the difficulty of setting up fixed standards for float-and-sink sampling and testing. At this stage at least, it is the intent rather to obtain experimental data on the principal Factors involved so that the reader may arrive more intelligently at a procedure adapted to his problem. The authors of this paper have presented experimental data showing the relationship between size of sample and particle size for different variability tolerances with respect to percentage of sink. In further studies, data are being collected to appraise also the variability of the samples with respect to float-ash content and size consist. The scope of this work will be broadened to cover particle sizes up to 4 in., and a third series of tests has yielded similar data for a much cleaner type of raw coal. Thus, the further studies will make available a fairly comprehensive meas- ure of variability with respect to size consist, percentage of sink, percentage of middlings, and percentage of ash in the float, for three coals ranging from 3.87 to 17.68 pct in refuse content (heavy sink material) and from 4.18 to 17.52 pct in middlings. Introduction At present there are no published standards for float-and-sink test sampling. During the rapid expansion of float-and-sink test work, varying procedures have been based on adaptations of the ASTM standards for sampling coal for analyses. For this reason, a special study of gross sample reduction has been undertaken to determine the limits for this step in the operation where no reduction in particle size is to be made before testing. Float-and-sink tests are made whenever a thorough study of coal characteristics is desired. The tests may be made on samples from coal-cleaning units such as jigs or tables, or coal samples may be tested which are taken from a loading boom, railroad car, or the coal seam itself. The resultant gross sample may be large and pose a problem of sample reduction. The question is, then, how much can the sample be reduced and still fall within preassigned limits of accuracy of the original gross sample of coal? Coal from channel samples may be crushed to liberate impurities and then separated into various gravity fractions from which washability curves are drawn; from these curves, it is possible to determine the cleaning characteristics of the coal. However, coal samples from coal-cleaning units cannot be

Jan 1, 1950