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By R. D. Mollison, C. F. Fogarty

Sulfur is widely distributed in nature. It is present in the earth's crust, the ocean, the meteorites that come to us from cosmic space and in practically all animal and plant life. According to Clarke,9 the earth's crust contains 0.06 pct sulfur. Large quantities of free or combined sulfur are found in coal, natural gas and petroleum. Mineral waters contain sulfates and hydrogen sulfide. Sulfur is rather plentiful in the crust of the earth; however, only under special circumstances can it be produced profitably. Sulfur is one of the cheapest raw materials used by industry; and, therefore, the economic feasibility of a given deposit is strongly dictated by the law of supply and demand on local as well as world-wide levels. The forms which are commercially important are elemental sulfur or brimstone, and the sulfides such as pyrite (FeS2), pyrrhotite (FenSn+1), chalcocite (Cu2S), sphalerite (ZnS), and galena (PbS); the sulfates such as gypsum (CaSO4,2H2O), anhydrite (CaSO4), and kieserite (MgSO4,H2O). Elemental Sulfur Elemental sulfur is found in many localities, generally in solfataras and gypsum type deposits. The solfatara deposits are found commonly in the neighborhood of active or extinct volcanoes as in Italy, Japan and Chile, or fumaroles associated with mineral springs such as the Mammoth Hot Springs in Yellowstone Park. Here the sulfur is deposited in tufas or other porous host rocks. This type of sulfur deposit probably results from the oxidation of hydrogen sulfide or the reaction of hydrogen sulfide with sulfur dioxide. Most of the world's supply of elemental sulfur comes from the gypsum-type deposits. Here the mineral occurs as either crystalline or amorphous sulfur in sedimentary rocks in close association with gypsum and limestone. This association is characteristic and occurs in almost all the great gypsum beds of the world, although sulfur is not always present in quantities of economic importance. Various theories have been advanced to account for this association. Bischof5 suggested that the sulfur came from hydrogen sulfide which resulted from the reduction of calcium sulfate by carbon or methane in accordance with the following reactions: CaSO4 + 2C= CaS + 2CO2 CaS + C02+ H2O = CaCO3 + H2S CaSO4 + CH4= CaS + C02+ 2H20 2H2S + 02= 2H20 + 2S All of the sulfur-bearing domes on the Gulf Coast have calcium sulfate in great quantity in the cap. They all show the presence of hydrocarbons. The oxygen for the final reaction could have been supplied by circulating ground waters. The principal objection to this theory is that temperatures of 700° to 1000°C are needed to reduce the sulfate to sulfide with carbon compounds. The geologic evidence is that the temperature of the sulfur-bearing domes of Texas did not exceed 100°C. Proponents of the theory say that geologic time or a catalyst replaced temperature. According to another theory the sulfur in the salt domes is the result of bacterial action. Sulfate reducing bacteria have been detected in sulfur cores and in the formation water issuing from salt domes. It has, therefore, been suggested that these bacteria converted the sulfate to sulfide which subsequently was converted to elemental sulfur.

Jan 1, 1960

By A. M. Rowe

A considerable quantity of experimental hydrocarbon K-factor data has been correlated as a function of component identity, temperature, pressure and convergence pressure. To utilize these correlations effectively, convergence pressure must be determined accurately, particularly for volatile mixtures near their critical states. This paper presents phase diagrams that illustrate physically the meaning of convergence pressure. A new method, referred to hereafter as the "critical composition method", will be outlined for calculating convergence pressure. An example calculation has been included to illustrate how to use this new technique. INTRODUCTION The principle of hydrocarbon phase composition calculations as applied to such diverse problems as optimizing separator performance or predicting fluid compositions at various stages of reservoir depletion is the same. Usually, temperature, pressure and the numbers of moles of the various components of the fluid contained in a given volume are known. Questions answered by the phase calculation are what fraction of the total mass of fluid exists in each of the equilibrium phases, and what are the mole fractions of the various components in the two phases? To answer these questions the Natural Gasoline Supplymen's Assoc. (NGSMA) has correlated a considerable quantity of K-factor data as a function of temperature, pressure, component identity and convergence pressure.l To use these correlations to obtain the best answers possible, one must be able to calculate the convergence pressure. This is particularly true for over-all fluid compositions in the neighborhood of the critical state. STATEMENT OF THEORY Use of convergence pressure as a correlating parameter is based on a postulate similar to the law of corresponding states used in correlating PVT data of hydrocarbon gases. This postulate, which proposes convergence pressure as a correlating parameter, has been stated as follows: "The equilibrium vaporization constant for one component in a complex system is the same as the equilibrium constant at the same temperature and pressure for the same number or kind of components, providing only that the convergence pressures of the two systems are exactly the same at the same temperature and that the components are of the same homologous series".2 This law, as with all laws of physics, cannot be proven theoretically. It can only be justified by experimental data supporting its premises. Arguments have been made that this law violates Gibb's phase rule. For example, consider a four-component system. By Gibb's phase rule, which is thermodynamically rigorous, f = c — P + 2 =4, for a four-component, two-phase system. Thus, four independent intensive variables must be specified to establish completely all the intensive variables of the equilibrium phases. On the other hand, according to convergence pressure theory, only three variables need be specified for any mixture containing four different components. These variables are temperature, pressure and convergence pressure. Thus, the two laws appear to be in conflict. However, the convergence pressure postulate is more restrictive than Gibb's phase rule. It applies only to mixtures of the same homologous series. Hence, these two concepts are not in disagreement. PHASE DIAGRAMS DESCRIBING CONVERGENCE PRESSURE This paper presents phase diagrams grading from the simple two-component system to the more complex four-component system to illustrate convergence pressure. A less abstract definition of convergence pressure will be stated that is

By Wallace W. Wilson

This DaoerAA calls to attention for the first time, to the writer's knowledge, a purported recovery of oil by substantially horizontal gas cycling that is considerably in excess of 50 per cent of the oil originally in place. The average angle of dip along the path of travel of the gas is less than one degree of arc. The best recovery by gas cycling previously brought to the writer's attention1 occurred in the case of the Mile Six Field in Peru, where about 68 per cent of the original oil in place has so far been recovered. In this case, however. the recovery was greatly aided 1)y the high dip angle of about 17.5". An approximate estimate of recovery was made by the method developed by the writer' for the case of the Cook Ranch Field, using an average relative permeability ratio function dictated by past experience with a number of good quality sandstones. A result of about 40 per cent recovery of the original oil in place wa* obtained after the 8.5 pore volumes of cumulative gas cycling undergone by the Cook Ranch Field. Tile writer desires to emphasize what appears to him as the sound engineering practiced at Cook Ranch, and also the care attending the taking of data and the high quality of the calculations made. It is impossible to take issue on factual grounds with any of the conclusions drawn in the paper. It is, however, desired to point out the difficulty of explaining the unexpectedly favorable oil recovery on ordinary theoretical grounds. It would be of interest to know whether relative permeability ratios have been measured on the Cook sand. The operator is inclined to attribute some of the excess benefit to settling of the oil across the bedding planes into the lower part of the sand. It is difficult for the writer to appreciate the importance of such an effect, inasmuch as the concomitant opening of excessive vacated pore space in the upper part of the sand would he expected to cause excessive bypassing of the gas. REFERENCE 1. Welge. H. J.: "A Simplified Method for Computing Oil Recovery by (Gas or Water Drive." Trans. AIME, (1952), 195, 91. AUTHOR'S REPLY TO MR. WELGE Welge has poined out clearly the difficulty of applying material-balance procedures in calculating the Performance of low-pressure, dispersed gas injection operations. There can be no argument that even with the most favorable assumptions of K,/K,, and with cumulative gas cycling in excess of normal expectations, the calculated oil recovery will be considerably less than the 72.5 per cent recovery realized from this project to Jan. 1, 1951. There probably are at least two reasons for the unusually high recovery from this reservoir, the effects of which would be difficult or impossible to calculate by known methods: 1. The operator did not use the same injection wells for the entire operation, and exercised considerable control over producing GOR by changing the locations of injection wells whenever well performance indicated excessive bypassing. Fifty-six wells were used for injection, not over 29 of which were in use simultaneously. This procedure resulted in frequent shifting of the fluid movement patterns in the reservoir and undoubtedly increased the ultimate recovery. The writer knows of no satisfactory procedure for calculating the effect of this practice. 2. Vertical movement of oil across the bedding planes of the reservoir rock hy gravity drainage tended to maintain a relatively high oil saturation, and hence a favorable K,/K, ratio, in the lower sections of the reservoir. As pointed out by Welge, this condition has aggravated the tendency for high producing GOR, but at the same time it has resulted in increased oil recovery. As may be seen from the performance charts for the various battery areas, operating (GOR'S have been quite high for the last several years of reported history.

Jan 1, 1952

By G. J. Dickman, W. N. Thomas

The factors involved in selecting, a drive system for a grinding mill, including gearing arrangement, motor selection, and electric-supply system limitations are reviewed. Equipment costs are evaluated on a dollar per horsepower basis and starting performance is analyzed, the latter making use of a recently developed computer program. The present interest in large-diameter grinding mills and the rapidly rising cost of the drive in proportion to the cost of the mill establishes a need to explore the drive system in detail. The drive for a 7 to 8,000 hp mill will cost from $350 to $600,000 which represents nearly half the total cost of the mill package, and requires as much building space as the mill proper. Some of the drive components require a longer time to manufacture and the installation time and costs are equal to those for the mill. It is apparent that the drive has become a dominant factor in the overall mill design consideration. A new plant requires a tremendous investment in both time and money. With the high degree of competition in the mining industry, low capital cost is an exceedingly important factor in the development of a project. It is just as important, however, to insure that the equipment is going to perform satisfactorily for the anticipated life of the project without adding unplanned operating, maintenance, and replacement costs. This is the position in which the engineer or designer usually finds himself and is really one of his primary functionsestablishing a realistic compromise between cost and performance. Large primary grinding mills can represent a major portion of the cost of a plant and the drive system accounts for a substantial part of this cost. These facts justify a careful analysis of the drive requirements and all of the factors involved in ultimately arriving at the best system for the lowest cost. A number of excellent papers have been published on various aspects of mill drives. The authors have used information from these papers in making a study of a drive for a 7600-hp, 32 x 12-ft autogenous mill. This was a broad investigation, including mechanical and electrical design, layout, performance, and maintenance considerations, and overall economics leading to the selection of the optimum system for that mill. This paper was developed from the study and includes information applicable to large mills in general. For a successful and economical application, the drive must be considered as a system and all of the components analyzed to determine their effect on the system. This requires the participation of the mill designer, gear, and other mechanical component manufacturers, motor manufacturer, plant designer, and operator. A careful analysis of the mill torque requirements is first necessary to provide a basis for selection of the mechanical and electrical drive components. Because of manufacturing limitations on the size and capacity of gearing available for these low-speed applications, an evaluation of costs for various gear ratios and configurations in conjunction with motor speeds is required. Consultation with the power-supply company is necessary to determine limitations on motor-starting disturbances and to analyze operating costs on the basis of existing rate structures and low characteristics. Finally, consideration must be given to the drive arrangement and its affect on plant layout, space requirements, and location of auxiliary equipment for the selected process. There are presently three basic schemes for driving a mill. The first is a direct drive by a motor operating at mill speed with no gearing. The second is by a higher-speed motor through a trunnion-connected gear drive. The third is by a motor through the more conventional pinion and ring-gear with the option of an interposing gear box to permit greater motor speed than pinion shaft speed. [(Fig. 1.)] Several manufacturers have or are presently developing motors which drive the mill directly without the use of gears. One arrangement has the motor armature intimately surrounding the mill shell-discharge spout or extension of the trunnion journal. The motor stator is then supported independently and surrounds the shell or trunnion-mounted rotor. Another variation utilizes an independent mill-speed motor connected to the trunnion by a drive shaft and flexible couplings.

Jan 1, 1972

By Parke A. Dickey

POTENTIAL differences between strata of shale and sandstone have been recognized for about 15 years, and they form the basis of the electrical logging of oil wells. Hitherto these potentials have been ascribed solely to electrochemical reactions caused by the disturbing effects of the water in the drill hole through which they are generally measured. Observations by the author in wells empty of water and in a mine shaft suggest that potential differences between sandstones and shales are natural and specific properties of the rocks, although they are modified to measurement by the disturbing effects of the water in the drill hole. The cause of these potentials probably is to be sought in the relative polar adsorptive capacities of quartz and clay particles.

Jan 1, 1944

Discussion of the paper of C. W. WASHBURNE, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 93,. September, 1914, pp. 2365 to 2378. ROSWELL H. JOHNSON, Pittsburgh, Pa.-It seems to me rather important to bear in mind one thing which is sometimes lost sight of, that the marine sedimentary rocks are laid down in water. We have to start with an initial charge of water. That being so, and the surface tension between the water and the -oil being as slight as it is, as referred to by Mr. Washburne,. the phenomena of capillarity are bound to be most important as between the liquid surface and the gas surface. So far as the liquid-gas surface is concerned, capillarity, in my opinion, is of the utmost importance, and it seems to me this paper of Mr. Washburne's is of great value to us for that reason. Starting out as we have, with our attention concentrated upon gravitational sorting, we have had to wait for the discussion of movement furnished by Munn, and this discussion of capillarity by Washburne, for a more balanced view of the situation. It seems to me that in the accumulation of oil and gas we have a problem of the interworking of gravitational sorting, capillarity, viscosity, immiscibility, and movement. All five things seem to me to be important. I would have expected Mr. Washburne to have given a fuller treatment of the relation of movement to capillarity. In my own experiments I find that gravitation and capillarity alone seem remarkably impotent when everything is at rest, but if I furnish a little movement, gravitation and capillarity step in and accomplish a great many results that one would not expect. Take a horizontal tube and fill a portion at the middle with an ordinary sand saturated with oil, and then put water and sand in each end, and the tube may remain at rest a very long time without that oil distributing itself along the top of the tube. But with a little motion that oil will gradually work up to the upper side. So gravitation and capillarity alone are rather impotent unless they get this element of movement. It would not be necessary to have very extensive movement, but some degree of movement is essential. Now if natural gas, in addition to the method of origin by the action of bacteria on organic matter in mud, may also arise by pressure at great depth, as the overburden is added, a great deal of motion may result. I think more motion is produced in this way than by the descent of meteoric waters.

Jan 4, 1915

By W. R. Shimer

In his valuable report on Finishing Temperatures and Properties of Rails,l Dr. G. X. Burgess, Chief of the Division of Metallurgy, U. S. Bureau of Standards, has begun a line of investigation which should be continued by those interested in the subject, and who have proper facilities for carrying out the work. For the past year or more the Bethlehem Steel Co. has been conducting experiments to learn the effect of rail finishing temperatures on their physical properties and microstructure and the results are here given for the consideration of those interested in the rail situation. Considerable differences of opinion have been expressed by various authorities, in the past, as to the effect of large or small grain size and high or low finishing temperatures of steel rails on their physical properties and wearing qualities. Low finishing temperatures and, therefore, low shrinkage, have been advocated on the theory that the wearing qualities would be improved. Others have recommended high finishing temperatures. The generally accepted cause for rail failures, due to the development of transverse fissures, is excessive wheel pressure on hard rails. One of the causes advanced for hard rails has been that they contain too high percentages of carbon and manganese; another that the rails were finished at too low a temperature, i.e., at or near the critical point. In the experiments herein described the rails were rolled from reheated blooms. All the rail blooms were charged hot in a reheating furnace and brought up to about the original ingot-rolling temperature before rolling into rails. These rails gave better results in deflection, withstood a greater number of drops before breaking, and showed greater ductility than rails of identically the same composition and section which were rolled direct from the ingot. Rails rolled from reheated blooms, finished at somewhat higher temperatures than when rolled direct from the ingot, have a different microstructure, which the writer does not believe is due so much to the difference in finishing temperatures, as to the difference in

Jan 1, 1915

By James E. Hoffmann

This paper reviews the chemistry of selenium and its compounds as it applies to the recovery of selenium from electrolytic copper refinery slimes. Based on this chemistry various processes for the extraction and recovery of selenium from refinery slimes are explained and developed. The optimum selenium technology processes is dependent upon many factors including copper refinery location, environmental and regulatory conditions, local markets for selenium or selenium chemicals, and other plant processes. For this reason there is no one best process but rather a variety of useful processes for winning selenium. Those which have demonstrated consistent utility in both ease of recovery and reliability are discussed in more detail. Recovery of selenium by Doré furnacing of slimes is the topic of a separate paper. The companies that have developed selenium extraction technology are not being cited in this paper for the following reasons: o Their current technology may be different o The actual inventor of a process is difficult to credit since many different organizations have pursued parallel inquiries in developing better processes. Finally, some selenium extraction processes have been omitted; not because they are unworthy of consideration but rather due to limitations of space.

Jan 1, 1984

By Daniel N. Beshers, Ralph H. Condit

An expression for the diffusion coefficient of inlerstitial atoms in the bcc lattice is derived which takes account of jumps between tetrahedral and octahedral interstices. The results are applied to the case of carbon diffusion in iron to find values for jump frequencies of the types, octahedral-tetrahedral, tetra-hedral-tetrahedral, and tetrahedral-octahedral. ThERE has been renewed discussion1-5 concerning the mechanism of diffusion of interstitial atoms in the bcc lattice. This lattice has both octahedral and tetrahedral interstices, and it has been pointed out that the interstitial atoms may make jumps of the octahedral-octahedral type, hereafter called o-o, octahedral-tetrahedral, o-t, and tetrahedral-tetrahedral, t-t. Doubt has been cast on the applicability of snoek's8 model for internal friction to some interstitial migrations in bcc lattices wherein he proposed 0-0 jumps as the principal mechanism of migration. Also, the anomalous excess diffusion of carbon in iron at high temperatures4 has been ascribed to t-t jumps,2,3 even though the sites normally occupied are octahedral. In this paper an expression is derived for the diffusion coefficient, taking account of the three types of jump mentioned. The relationship of the coefficient to the corresponding internal friction relaxation time is found for the limiting case corresponding to Snoek's model. These results are applied to the case of carbon in iron. In Fig. 1, the structure is shown with the locations of the interstices. Each o site has four t site neighbors coplanar with it, and each t site lies halfway between two o sites. There are four t site first neighbors of a t site lying at the vertices of a tetrahedron. Let the average fraction of atoms occupying o sites and t sites be No and Nt, respectively. Since there are six o and twelve t interstices per unit cell having a lattice parameter, a, the concentration of interstitial atoms will It will be assumed that three types of jumps may be distinguished, t — t, t — o, o — t,for which the jump

Jan 1, 1968

Jan 1, 1968

By H. E. Powell, A. A. Cochran, R. E. Coleman

Infrared spectroscopy, employing the internal reflection method in conjunction with solvent extraction techniques, was used to study surface reactions between aqueous potassium ethyl xanthate and both sphalerite and precipitated zinc sulfide, each activated with aqueous copper sulfate. It was determined that reactions occurring on the sphalerite and zinc sulfide surfaces produce the reaction products ethyl dixanthogen and cuprous ethyl xanthate, some of which are adsorbed on the mineral surfaces. As the pH of the xanthate solution increased from 5.6 to 11.0, the amount of cuprous ethyl xanthate on powdered sphalerite surfaces decreased and the amount of ethyl dixanthogen first increased and then decreased. It is generally accepted that the collector potassium ethyl xanthate will not float the mineral sphalerite (ZnS). However, Gaudin1 showed that sphalerite readily floats if activated with certain metal cations before exposure to the xanthate. Copper sulfate (CuSO4) was found to be the best activator for sphalerite. The over-all flotation reagent reaction, as given by Gaudin,3 is as follows: While this is the over-all reaction, the exact mechanism of the reaction and the intermediate compounds that may be formed are not yet known with certainty. Important work has been done in Russia by Plaksin

Jan 1, 1968

By R. P. Carreker, R. W. Guard

True stress-true strain data are given for nominally pure molybdenum (99.95 pct) over the temperature range -196° to 1540°C (0.027 to 0.63 T/T). Strain rate sensitivity was determined by rate change tests and stress relaxation tests. Inhomogeneous yielding and strain aging effects were observed. The yield stress and tensile strength depend markedly on temperature below 400°C and are insensitive to temperature in the range 400' to 800°C. The ductile to brittle transition range is +25O to -25OC. Strain rate sensitivity and stress relaxation effects are very large near room temperature. THIS report presents data which were obtained as a part of a continuing program designed to document the deformation behavior of nominally pure metals over a wide temperature range.'" This research program is rooted in the conviction that sufficient tensile and creep data of appropriate quality and detail does not exist to provide precise phe-nomenological descriptions of the deformation behavior of pure metals as a function of temperature, strain rate, and grain size. Such knowledge is needed to provide a firm base for alloy design and an experimental framework to which theories of deformation must conform. These data also complement a parallel exploratory program investigating the properties of refractory metals, including molybdenum, and their alloys. Several important reviews and research reports dealing with the tensile properties of molybdenum as a function of temperature have appeared."-lo To a great extent the work to be reported in the present paper parallels that of Bechtold and of Pugh. The authors' results are in general agreement with those of Bechtold and Pugh. The principle differences be- tween the present experiments and those published previously are as follows: 1—Wire specimens prepared from arc cast molybdenum were used in the present experiments, bar specimens were used by others. Pugh used arc cast material while Bechtold's most extensive results" were obtained on powder metallurgy specimens. 2—Several different grain sizes were tested in the present experiments. 3—The testing range was extended to cover from -196°C to 1570°C (0.027 to 0.63 T/Tm). 4—The combination of wire specimens, high speed autographic recording, and a stiff testing machine permitted more detailed study of initial yielding. The principle contribution of the present paper is the demonstration of the relatively consistent mechanical properties of nominally pure arc cast molybdenum specimens of differing metallurgical history. Bechtold and Scotts have shown that arc cast and powder metallurgy molybdenum samples have comparable tensile properties in the range —75" to 200°C when processed to have the same re-crystallized grain size. Material The molybdenum used in this investigation was supplied by the Climax Molybdenum CO. Its metallurgical history is outlined in Table I; the final products were 0,030 in, diam wire specimens annealed at 1100' and 1375°C and 0.060 in. diam wire

Jan 1, 1957

By R. C. Davis, R. F. Berry, G. W. White, B. T. O’Connell, L. A. Stacha

The formation density logging tool provides a radioactivity measurement that yields formation densities in situ. The relationship between bulk density and porosity is well understood. With knowledge of grain and fluid densities, porosity may be computed from the indicated formation bulk densities in shale-free formations. The porosities thus determined may be used with a resistivity log for water-saturation determinations. One technique utilizes a density vs resistivity plut. A plot of density vs Sonic-log transit time is used for porosity determinations in shaly sands. This method is particularly suited to wells drilled with oil-base or salt muds. In shale-free formations, comparisons of density values nnd neutron-log readings are used to identify lithologr and, thus, to select appropriate values of grain density for porosity computations. Through the use of Formation Density, Sonic and neutron logs, the interpretation problems caused by complex matrix lithologies are simplified. Other applications of the Formation Density log are found in the identification of minerals in evaporite deposits and in yield determinations of "oil shales". INTRODUCTION Widespread field application has demonstrated that the measurement of formation density is a useful and revealing technique for well logging. Responding to the bulk density variations of the formation, the Formation Density log affords valuable data on the porosity, lithology and fluid content of the formations. Although not without its own limitations, the Formation Density tool may provide effective interpretation under conditions that hamper or preclude the use of other porosity devices. When used in conjunction with other devices, such as the Sonic or neutron, complex matrix conditions may be better understood, defined and evaluated. A previous paper' described the valuable contribution of the Formation Density tool in the logging of empty, or gas-filled, holes. The purpose of the present paper is to describe applications of the device in liquid-filled holes. THE FORMATION DENSITY TOOL The Formation Density tool was devised to measure the bulk densities of formations in situ. Actually, the device responds to electron density, but in the overwhelming majority of cases of interest, the electron density is very closely proportional to the bulk density. In other cases appropriate corrections can be made if necessary. Comparisons of log-derived densities with true densities for the more common matrix minerals are shown in Table 1. The tool consists of a gamma-ray source and detector mounted in a skid which, during the logging operation, is in contact with the borehole wall (see Ref. 1 for schematic). Gamma rays are emitted by the source and diffused through the formation. The number of diffused gamma rays reaching the detector at a fixed spacing from the source are counted. An increase in counting rate by the detector indicates a decrease in bulk density in front of the skid. Conversely, a decreased counting rate signifies an increase in bulk density. A measurement of hole diameter, between the face of the skid and that of the eccentering arm, is recorded simultaneously with the measurement of diffused gamma rays. Since the tool is a wall-contact device, the size of the borehole has little influence, provided good contact is maintained with the wall of the hole. Only in extremely large or small boreholes does the actual diameter become significant. However, for most accurate measurements the borehole size should be taken into account. Fig. 1 presents the departure curves for the conversion of counting rate to bulk density for liquid-filled holes of various sizes. It is of utmost importance that the skid maintain good contact with the wall of the hole. If, due to roughness or caving, there is mud between the skid and the formation, the tool will include in its response the relatively low-density mud, and the apparent density reading will be too low. Normally, permeable beds do not cave appreciably, so that reliable readings are usually available for zones of interest. Nevertheless, the caliper reading over the zone of interest should be examined for any wall roughness. When mud cake exists between the skid and the formation, the Formation Density log sees it as part of the formation. When thick mud cakes exist, a correction is required. For best results in wells having thick mud cakes,

By D. A. Augenstein, L. V. Amundson

Operators of coal preparation plants use equipment such as large-capacity dump trucks and bulldozers to haul, spread, and compact refuse material to conform to federal and state regulations governing the disposal of solid waste. For example, federal regulations require that refuse be spread and compacted in layers not more than 0.6 m (2 ft) thick. If the refuse layers or piles have poor load-bearing characteristics, movement of equipment over them becomes extremely difficult. The increasing cost and limited space for the construction of settling ponds extensively used for fine refuse disposal are leading to the growing practice of dewatering the fine refuse by means of vacuum disk filters and combining the resulting filter cake with coarse refuse for waste bank disposal. However, this filter cake usually contains more than 25% moisture. Therefore, when it is combined with coarse refuse, the moisture level of the total refuse may become high enough to impair the load-bearing strength of the refuse. Precisely this problem and the attendant difficulties of moving heavy equipment arose when vacuum disk filters were installed at a preparation plant in West Virginia. Combining the moist filter cake with the coarse refuse generally results in a 12% moisture level for the total refuse at this plant. At this moisture level, the refuse can still be handled with some dif¬ficulty by the equipment. However, the problem has frequently been compounded after rains. The experimental program described in this paper tested the following methods of improving the load-bearing properties of coal refuse: moisture reduction, addition of crushed coarse refuse, addition of fly ash, addition of lime, and addition of a mixture of lime and fly ash. In terms of a balance between economic and technical considerations, the most effective method was demonstrated by laboratory and plant tests to be a 2% to 5% addition of lime. Test Program During formulation of a test program aimed at improving coal refuse stability, a number of treatment techniques were selected for evaluation of their effect on refuse load-bearing characteristics. The reduction of refuse moisture was the first technique considered, since moisture content plays a key role in the bearing strength of a bulk solid. The reasoning was that a very small reduction in refuse moisture, provided it could be accomplished with minimal effort and cost, would be sufficient for eliminating refuse disposal problems most of the time. At the same time, it was recognized that periods of rainy weather would offset moisture-reduction measures. Other techniques selected for evaluation because of their potential for improving refuse-bearing strength at reasonable cost were: addition of crushed coarse refuse, the addition of fly ash, and the addition of lime. A simple one-dimensional laboratory compaction test was designed for evaluating the effect of each of these techniques on refuse-bearing strength. Those techniques that gave best results in the laboratory would then be tested in the preparation plant in West Virginia. Laboratory Tests The laboratory test for evaluating each of the techniques involved the application of weight to a load module placed on a refuse sample in a container. The distance the load module sank with an increasing amount of applied weight was measured, and the relationship between module displacement and loading was obtained. The refuse container was large enough to minimize the influence of wall effects, and to decrease the effect of the container bottom, a test was terminated when the load module sank to about three fourths the depth of the container. Initially, an attempt was made to conduct compaction experiments with samples of total plant refuse. However, the presence of + 0.13 m (+ 5 in.) material in the refuse interfered with the mechanics of the test, and the large amount of material required for a representative sample made testing extremely tedious and time-consuming. To avoid this problem and because it was believed that only the fine components of the refuse were the major cause of the stability problem, tests were conducted with 13 mm X 0 (1/2 in. X 0) material from the total plant refuse. The equipment consisted of a 0.46 m (18 in.) cubic container, a loading module with 62 cm2 loading area, weights totaling 450 kg, and a portable concrete mixer for combining water and additives with the refuse. Refuse samples of about 110 kg dry weight were used for each test. Experimental compaction test data were evaluated by plotting the linear displacement of the load module vs. loading. During compaction tests, the vertical displacement of the load module was measured at each loading value. The plot of

Jan 1, 1980

By Burton Atkinson, David Johnston

Evaluation of Ellenburger reservoirs in West Texas has been an uncertain matker at best because of the lack of cores and suitable core-analysis method. Large amounts of oil arc produced from sections from which sample cuttings are obtained that contain litile porosity and no oil saturation. It has long been realized that the formation in some areas contained numerous fractures and solulion cavities that probably contained the major part of the oil present but the magnitude of the porous system conltaining oil has been unknown. Diamond coring cquipmene, used in the mining industry lor many years, has been developed for oil-field use to obtain high core recovery in fractured dolomite that is not possible with conventional coring equipment. A 36ft section of the core recovered from a fractured Ellenburger reseivoir waS analyzed by a unique but simple method to obtain the first defmite evaluation of one section of the producing formation. The cores and the method of analysis used are described and the results arc discussed in some detail. Discussion The first successful known analyses of cores recovered from the Ellenburger formation in the Permian Basin area were made on cores recovered with the use of diamond core heads. Conventionul coring methods previously used have had lour core recovery and standard methods of analysis have proved to be inadequate for evaluation of those cores that were recovered. Core Descriplion The Ellenburger formation to be dis cussed was cored using diamond core heads and oil-base drilling fluid. Of the total 103 ft cored to a depth of 8893 ft in the Ellenburger, 99 ft or 96 pct was recovered. The dolomite cores were described as gray to white, crystalline to coarscIy crystalline, with chert and calcite inclusions. Occasional shale partings ? to ¼ in. in width were noted. A small amount of green clay was found in some of the coarsely crystalline material. So intergranular porosity was found by inspection in any of the cores. The core urns highly fractured over most of its length with not more than two continuous feet that failed to contain fractures. The fractures Were nearly vertical and varied in width from those harely visible to as much as one millimeter. Scattered solution voids, or vugs, as large as 3 cm in diameter occurred in association with same •a

Jan 1, 1949

By W. L. Phillips

The plastic properties of lithium fluoride and magnesium oxide under compression were investigated in the temperature range 25° to 1000°C. At the higher test temperatures, the critical resolved shear stress and the rate of work-hardening of both materials decreased. At the same time, the number of stress lines decreased and the individual stress lines became wider. The density of dislocations decreased for a given strain the higher the test temperature for lithium fluoride. The decrease in the critical resolved shear stress as a function of temperature could be fitted by the equation 7 = Toe-KT. THE influence of temperature on the stress-strain curves of a variety of metal single crystals has been studied for a wide range of temperature.1"5 In general, it has been found that both the critical resolved shear stress and the rate of work-hardening decrease rapidly with increasing temperature and fall to a value of essentially zero well before the melting point is reached. AS the test temperature is increased, the density of slip lines has been found to decrease, while the width of the individual lines increases. Recently, Gallagher,' Graf et al.,7 and Pate1 and Alexander8 have found that single crystals of germanium and silicon, which have a covalent bond, can be plastically deformed at elevated temperatures. In compressing germanium it has been found that the strain-hardening coefficient decreased very rapidly as the temperature was increased. The coefficient did not tend to zero, however, as the melting point was approached. The plastic properties of ionic crystals at elevated temperatures have not been extensively investigated. In the only work previously reported Tamman and salge9 and Theile10 have shown that the yield point of sodium chloride single crystals tested in tension and compression decreased slowly with increasing temperature, falling to zero at the melting point. As the temperature was increased, they found a substantial increase in the amount of plastic deformation that could be sustained before fracture; and at temperatures above 400°C in tension tests there was an obvious necking which produced local extensions of up to 3000 pct. The purpose of the present work is to extend the knowledge of high-temperature deformation to the ionic crystals, lithium fluoride and magnesium oxide. The following were investigated: 1) The gross shape of the stress-strain curve at several temperatures. 2) The change in the critical resolved shear stress as a function of temperature. 3) The appearance of slip bands and the density of dislocations as a function of strain and temperature. EXPERIMENTAL TECHNIQUES The lithium fluoride and magnesium oxide used in this investigation were purchased from the Harshaw

Jan 1, 1961

By Carl Floe

A NUMBER of proposals have been made for the hydrometallurgical recovery of copper from flotation concentrates, but as yet no process has been developed that has demonstrated an ability to compete with the present smelting methods under ordinary conditions. The treat-ment of copper concentrates by hydrometallurgical methods is in general similar to that used in the present electrolytic zinc process and involves roasting, leaching with H2S04 solution, separation of solutions, control of impurities and electrodeposition. While many of these steps are simpler and more readily carried out for copper than for zinc, a number of inherent difficulties have prevented the general adoption of the process. To compete with smelting, the following problems must still be con-fronted, although many solutions for their have been proposed: (1) con-duction of the roast in such a way that leaching will give an extraction of copper comparable to that obtained by smelting; (2) regulation of the ferric iron content of the solutions during electrolysis; (3) disposal of the excess acid regenerated from the sulphates formed in roasting; (4) eco-nomical recovery of the precious metals from the leach residues. The roasting problem is largely one of preventing the formation of copper ferrites, CuO.Fe2O, and Cu20.Fe2O3, which are quite insoluble in dilute sulphuric acid. These ferrites are apparently formed' to a small extent even at low temperatures and above 650° C. their formation is rapid1. While it is possible to carry out laboratory roasts in such a way that less than 5 per cent of the total copper is present in the insoluble ferrite form, a closer temperature control is required than can readily be obtained in industrial furnaces. The flash" roasting effects and consequent high temperatures that occur as the calcine falls from hearth to hearth in the ordinary multiple-hearth roaster are probably largely responsible for the inevitable formation of some ferrites. The result is that in a commercial plant the extraction of copper would not average more than 90 per cent in a single 10 per cent H2SO4 leach. This is

Jan 1, 1937

By Charles W. Wright

At most mines where large tonnages are handled, "bulldozing" or secondary blasting is an important and costly operation. To reduce the large blocks from primary blasting operations or stoping so that they will be small enough to pass through the chutes into the cars at the haulage level, and not too large for the crushing plant, requires blasting. Often this is done by placing a few sticks of dynamite on top of a block with or without a capping of mud, but to consume less dynamite and to promote safety, most secondary blasting is now done by blockholing, or the drilling of holes 6 to 12 in. long in the blocks, using only a part of a stick of dynamite per hole. Regardless of the method of blasting, however, the term "bulldozing chamber" is applied to the room where this work is done. Bulldozing chambers permit secondary blasting at all times in a safe place without disturbance to the other mining operations. The chambers are usually high above the haulage level and well below the stope level or open-pit floor. In most instances the material is passed through a grizzly in the bulldozing chamber, but sometimes no grizzlies are used. One to four raises extend from the chamber to the stope floor and one or two from the haulage level to the chamber floor. Occasionally large slabs of ore or rock choke the raises above the bulldozing chamber, and these have to be blasted by attaching a bundle of dynamite sticks on the end of a long pole and placing them up in the raise between the pieces causing the choke. This is called "chute-blasting." To give a picture of the progressive developments in the use of the bulldozing chamber, a few typical mines that show the application of this method to both metal and limestone mines have been selected for description here. Limestone mines have been included because many metal miners do not realize to what extent the nonmetallic, or rock, miners' are now applying metal-mining methods successfully in their operations. The bulldozing chamber is the "neck of the bottle" for some mines.

Jan 1, 1937

By R. E. Miner, J. K. Jackson, T. L. Wilson

THE nature of the decomposition reactions producing hardening in aluminum-rich A1-Ag alloys is now fairly well understood. The silver is not uniformly dispersed even at temperatures above the solvus line: rather, it is clustered into zones and associated with dislocations.' During quenching, nearly all of the silver segregates into zones' and some is attracted to dislocations, producing stacking faults. Growth of these faults produces the semicoherent y precipitate.1 During aging, the larger zones and the y precipitates grow at the expense of the smaller zones. The large zones persist up to about 350°C; where they redissolve in favor of the y' and y precipitates.' The equilibrium hcp y precipitate occurs both by a cellular reaction at the grain boundaries1 and by growth of the Y' plates to a critical size where incoherency results. Damask and Nowick 4 observed an internal friction peak in an A1-6 at. pct Ag alloy at about 140°C (0.25 cps). The peak was found to exhibit a systematic instability. After aging at successively higher temperatures between 155' and 23Z°C, the peak first migrated to higher temperatures while increasing in height, then returned to lower temperatures and decreased in height. After aging at temperatures above about 200°C, the peak position remained constant while the height decreased very slowly. In quenched specimens, elastic after-effect measurements inhcated a rapid initial transient in peak position from low temperatures up to 155°C. The authors concluded that a stress induced growth and resolution of the clusters and the 7' was the most reasonable mechanism to account for the behavior. It would seem, however, very unlikely that both the clusters and the y' precipitate would provide damping contributions whose relaxation time and activation energies were identical, which is required for them to produce the same internal friction peak. The present investigation was motivated by this apparent anomaly and the development of a very low thermal inertia torsion pendulum5 capable of monitoring transient behavior. Low frequency internal friction measurements were made on four binary A1-Ag alloys nominally containing 5, 10: 15, and 20 at. pct Ag. The results of measurements made on a 10 at. pct Ag alloy in the quenched condition are shown in Fig. 1. There are two peaks apparent in the spectrum, one centered at about 160°C, the second at about 210°C. The two peak spectrum was observed in each alloy, but it was best resolved in the 10 pct Ag specimens. Because of the instability in the internal friction, 4 it seemed possible that the second peak was not a peak at all, but simply a manifestation of a single, sharply transient, peak. This effect has been observed in Au-Ni alloys.6 The existence of the higher tempera-

Jan 1, 1970

By Arthur Lake

Within the past few months I have had occasion to visit and examine the area of country in Gunnison county locally called the Gold Belt and extending from the Cebolla river on the west to the head of Taylor Park and the Sawatch range on the east. The region including the "belt" may be hided topographically into two parts, a northern and a southern one. The former is characterized by lofty mountains and deep canons, with occasional parks and wide valleys. Most of it is included in the granitic system of the Sawatch range, with local patches of the Palaeozoic sedimentary rocks, more or less traversed by great bodies of porphyry and other eruptive rocks. The southern portion, on the other hand, is characterized by comparatively low, rounded hills of schist and sahistose gneisses, underlain by coarse, massive granite, which outcrops locally in small, and sometimes in large, patches. These hills also sometimes form table-lands by reason of overflows of lavas, such as andesitic breccia, rhyolite, trachyte and basalt. The leading geological feature is that of a schistose area of width and extent unusual for Colorado. These schists and gneisses are of pre-Cambrian age; but whether assignable to the Algonkian or to some older system has not been determined. The granite which occasionally outcrops from beneath these schists is, I think, of true eruptive character, since its mode of occurrence indicates a once molten, or at least highly viscous or plastic, condition. Thus, we may observe, included in its mass, numerous fragments of schist, almost like a coarse, volcanic breccia. Again, at its immediate contact with the schists, which often stand vertically upon it, the pediments of the latter are fused into the granite, and granite tongues and veins run up amongst the schists, as only a molten or viscous

Jan 1, 1897