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By H. N. Mead

In a reservoir when gas comes out of solution and rises, additional pressure is created because of the change in position of this gar in the bounded volume. If this pressure effect is not taken into account as a pseudo-influx ill mate rial balance calculations on reservoirs in which there is evolving gas, an error is introduced that is directly proportional to the length of oil column and amount of gas evolved and inversely proportional to the reservoir pressure. In reservoirs with small oil column this pseudo-influx is of little importance. The larger the oil column the more important the effect becomes. The most important application, however, will be for reservoirs with declining pressure in which increasing water entry has been indicated by material balance calculations. It could be that this indication is the result of the cited pseudo-influx and not water entry at all. This paper attempts to explain this phenomenon in relation to material balance calculations and prevents an approximate method of determining tile pseudo-influx. INTRODUCTION Only recently has the pressure-volume relationship of gas rising in a liquid appeared in engineering literature, although its effect has been discussed for several years—especially among engineers engaged in drilling operations. The writer published a paper in 1957 in which this phenomenon was examined in relation to blowouts in drilling wells.' Also, in 1957 Stegemeier and Matthews' authored a paper in which the relationship was presented with respect to pressure build-up tests when shutting in producing wells. In this paper the effect will be called "pressure inversion" which is descriptive of the phenomenon. Fundamentally, the effect just mentioned is the result of changing the position of a quantity of energy contained within the gas itself (as a result of its compression) within the bounded volume in which the gas exists. If the gas were allowed to expand "beyond all bounds" there could be no pressure inversion effect. This is because all of the energy contained within the gas as a result of compression would have been re- PRESSURE INVERSION A phase that has not been discussed in the literature is the effect of pressure inversion upon material balance calculations in reservoirs in which the reservoir pressure drops with reservoir withdrawal and is below the bubble point. This action releases solution gas which, after the critical gas saturation has been reached, will tend to rise and collect at the top of the reservoir. The pseudo-influx caused by this effect could be great enough in reservoirs of large oil column and high permeability to render invalid any analyzer studies made on them — if pressure inversion has not been taken into account. Most suspect would be those reservoirs with large oil column in which increasing water entry has been predicted but the bottom wells have not yet produced water. Example 1 Simply stated, this phenomenon exists in oil reservoirs because of the difference in density and expansibility between gas and oil. For example, if a bubble of gas exists at the bottom of a 1,000-ft column of oil having a gradient of 0.30 psi/ft with the pressure at the top of the column zero, the bubble of gas will be compressed to a pressure of 300 psi. If temperature and the combined volume of the oil column and the gas bubble remain constant, as the gas bubble rises in the oil column it will have the same volume and consequently the same pressure at any point. Under these conditions when thc bubble reaches the top of the oil column, the pressure will be approximately 300 psi at the surface and approximately 600 psi at the bottom of the oil column. If it is assumed that the oil is incompressible the pressures will be exactly 300 and 600 psi, respectively.

By R. E. Cook

This work presents the development and application of equations of the form developed by Martin1 to describe gravity segregation performance during natural depletion. One-dimensional depletion analyses are applied to several hypothetical reservoirs. Considerable attention is given to the changes in saturation distribution in the dip direction resulting from depletion at various rates. Vertical gas saturation distribution within a sand having vertical permeability is studied to illustrate conditions which provide For low gus-oil ratio production from wells selectively completed away from sand tops, as observed from well performance. Results of performance calculations are shown graphically and illustrate the rate sensitivity of the gravity segregation mechanism and the influence of reservoir geometry and withdrawal distribution. It is shown that for sufficiently high depletion rates gas saturation distribution in the dip direction is characterized by the formation of two discontinuities, or saturation "fronts"; the updip front being the gas-oil contact of the secondary gas cap and the downdip front occurring at a position dependent upon the reservoir depletion rate, withdrawal distribution and reservoir geometry. The gas saturation in the region between fronts is shown to continually increase with time, while that downdip from the lower front remains very low and relatively stable. The effect of increased depletion rate is to reduce the region of stable gas saturation and thus enlarge the portion of the reservoir producing with continually increasing gas saturation. Special attention is given to the performance of reservoirs having sufficient vertical permeability to permit liberated gas to segregate vertically within the sand section before proceeding in the updip direction. It is shown that reservoirs of this type are far less sensitive to depletion rate due to the mechanical control of producing gas-oil ratios afforded by selective well completions away from sand tops. It is shown that gravity segregation performance is adversely af- fected by decreasing reservoir cross-section area in the updip direction. It is also shown that down-dip withdrawal concentrations can restrict gas segregation rates in the dip direction. INTRODUCTION The natural depletion performance of several large producing reservoirs in Western Venezuela has unmistakably shown the significant role that gravity forces play in governing the gas-oil ratio behavior of individual wells and the over - all pressure-production performance of the reservoirs. Analysis and prediction of the natural depletion performance of these reservoirs is of great importance in determining the economics of pressure maintenance operations. In 1957, a method for the analysis of pressure maintenance performance was presented by Martin1 which, in the original and more general form of the equations involved, provides a physically sound basis for the analysis of one-dimensional gravity segregation performance during natural depletion. The work reported herein is an application and extension of Martin's outstanding developments to a series of hypothetical reservoirs in an attempt to explain the general behavior of the gravity segregation mechanism and the influence of such parameters as depletion rate, reservoir geometry and withdrawal distribution. The study considers two types of flow: "distributed flow", where vertical permeability in the reservoir is zero and fluids flow only in the dip direction while uniformly distributed over the sand thickness; and "segregated flow", where vertical permeability is sufficient to permit gas to segregate against the sand top before proceeding updip. This latter type of flow has been recognized as an important mechanism active in the massive sand reservoirs of Western Venezuela. ANALYSIS OF ONE-DIMENSIONAL DISTRIBUTED FLOW SYSTEMS For an inclined reservoir having zero vertical permeability, the velocities of oil and gas flow at any point in the reservoir can be derived from Darcy's equations as

By D. T. Peterson, F. A. Schmidt, J. D. Verhoeven

The velocity of mig-ration of these solutes in thorium metal due to a high amperage dc current was measured at several temperatures. All three solutes migrated in the same direction as the electron flow. Diffusion coefficients were combined with the migration velocities to predict the steady-state concentration profile. Electrotransport was shown to be an effective method of removing carbon, oxygen, and nitrogen from thorium and resistance ratios several times larger than for crystal bar thorium were achieved. However, the maxirnum attained purification was well below the predicted values, apparently due to some form of contamination. THE migration of solutes in metals when a high current density dc current is passed has been known for many years. This phenomenon has been the subject of a number of reviews published in recent years.l~* Many of the earlier investigators of electromigration of interstitial solutes interpreted the direction and velocity of migration on the basis of a charge on the solute particle. This interpretation is unclear because, in a given experiment, one cannot separate the contributions to the force moving the solute which arise from the charge on the solute in an electric field gradient and the momentum transfer from the scattering of the electrons or holes. There have been only a few quantitative measurements of interstitial migration velocities and some of these have been characterized by poor accuracy or by errors in the analysis of the experiment. The electrotransport mobilities of carbon, nitrogen, and oxygen in thorium were determined by observing the rate of movement of a discontinuity in the concentration profile. This method was used by Carlson el a~.~ to determine the mobilities of interstitial solutes in yttrium and its advantages are discussed in that paper. The specimen is essentially a pair of semi-infinite, bar-type diffusion couples. The electro-transport velocity was measured by observing the displacement of the mean concentration point in a measured length of time. The diffusion coefficients were calculated by the Grube method from the concentration profile. The transport mobilities and diffusion coefficients can be used to predict the concentration profile in an electrotransport experiment of a given time, current density, and specimen length. At long times a steady state will be reached such that the natural logarithm of the concentration of each solute varies linearly along the bar with a slope which is equal to the velocity of the migrating solute divided by its diffusion coefficient. The estimation of the purification potential of electrotransport is discussed by ~erhoeven.' A comparison of the concentration profile and the purification which should be expected from known solute velocities and diffusion coefficients with that which is obtained in an experiment can be very useful in indicating whether the maximum possible purification has been achieved. EXPERIMENTAL METHOD The apparatus used in this study consisted of a sample chamber which was equipped with two electrodes, a sight glass, and a flange for mounting to a high-vacuum system capable of obtaining pressure of 2 x lo-? Torr. The chamber was made of stainless steel and was 4 in. in diam and 6 in. long. The seal between the electrodes and the chamber was made with "0" rings and compression bushings. The thorium specimens were threaded and screwed into tantalum "U"-shaped adapters attached to the ends of the electrodes. This arrangement is shown in Fig. 1

Jan 1, 1967

By W. N. Lacey, R. H. Olds, B. H. Sage

Samules of liquid and gas were obtained from the primary separator of a well in the Paloma field. The volumetric properties of the samples and of six systematically chosen mixtures of the samples were experimentally determined at 100°, 190°, and 250°F. at pressures up to 5000 lb. per sq. inch. From these data the influence ,of pressure and temperature upon the composition and specific volume of the bubble-point liquid and of the retrograde dew-point gas was established, The formation volumes and gas-oil ratios of the rnixtures investigated were calculated on the basis of the plant-product oil, which is defined as the isobutane and less volatile portion of each mixture. The results are presented in graphical and tabular form. The volumetric behavior of the mixture corresponding to that produced by the well at the time of sampling was determined for 235ºF., the reported reservoir temperature, by graphical interpolation of the experimental data with respect to composition and temperature. The results indicate that the well-production mixture probably existed as a gas at its retrograde dew point under the conditions of temperature and pressure believed to prevail in the producing zone at the time of sampling. The effect upon the phase behavim occasioned by the omission from the well-production mixture of certain components of intermediate molecular weight was investigated. In the first case, all of the isobutane and 11-butane, and substantially all of the iso-pentane, were removed from the mixture of trap samples corresponding to the well production. In the second case, all the propane, isobutane and n-butane, and substantially all of the isopentane, were removed. Both modifications led to considerable increases in the retrograde dew-point Pressure at 235ºF.; an increase of 558 lb. Per sq. in. above that of the unmodified well-production mixture in the first case, and an increase of 1208 lb. Per sq. in. in the second. It was concluded that the material? remaining after the removal of certain components of intermediate molecular weight could not be injected back into the reservoir in the saqe proportion in which they were produced without entailing appreciable loss of liquid material through condensation within the formation. Introduction Under the usual conditions of production practice, petroleum arrives at the surface of the earth in a physical state considerably different from that in which it existed in the underground reservoir. The relative rates of production and the properties of oil and gas measured at surface conditions do not constitute, in general, even a qualitative description of the fluids existing in the reservoir. The estimation of reserves and the attainment of optimum efficiency with regard to rate, quantity, and cost of production require accurate data concerning the physical properties of petroleum throughout large changes in pressure and temperature. Many schemes have been devised for predicting the behavior of propane, as it is encountered in nature? but the experimental work upon which these predictions are based has not, for the most part, been extended to the higher pressures that occur in practice, nor do these methods permit, as yet, the estima-

Jan 1, 1945

By G. J. Wilson

Difficulties experienced in correlating vertical and lateral locations of subsurface features that are encountered in directional wells prompted critical review of the tangential method of computing directional surveys. Inherent discrepancies were indicated to cause small incremental but significantly large cumulative errors in computed vertical depth and horizontal departure. A radius of curvature method, developed for planning and analyzing directional wells, was studied as a means of more accurately calculating survey data. Errors incurred in the tangential method were not present in the radius of curvature method. Conflicting assumptions in calculating dog-leg severity by the tangential method were resolved by a new procedure that was derived from the radius of curvature method. Results of the investigation showed the radius of curvature method to be an improved method for computing directional surveys. Introduction Many improvements in directional drilling tools and techniques have been made in the past 10 years,' but the method of computing survey data has remained virtually unchanged. While use of computers greatly aids the process of calculation' and eliminates many human errors, manual and computer calculations are still made with the assumption that the wellbore consists of straight-line segments. This paper points out discrepancies in the method and presents an improved method in which the wellbore is assumed to be curved. Tangential Method The method presently used to calculate vertical depth, horizontal departure and direction coordinates with measured values of well depth, inclination angle and direction angle is termed the tangential method. This term stems from performing calculations with a series of straight-line segments, with each segment assumed to be tangent to the wellbore at a corresponding survey point. A segment is defined by inclination and direction angles measured at only the lower or deeper end. Consequently, a discrepancy or error is introduced for each segment. Errors are not of extreme magnitude, but cumulatively are significant due to the need to define as accurately as possible the vertical and lateral location of subsurface features such as pay tops, fluid contacts and fault cuts encountered in expensive directional well bores. In Fig. 1, the curved-line segment ab represents a portion of the actual borehole as viewed in the vertical plane. Points a and b are survey stations and +, is the inclination angle at point b. The curved-line segment ab is assumed to be the straight-line segment arb of a length equal to ab and tangent at point b to the curved-line segment. Lengths a'c' and c'b are equal to a'b cos +, and a'b sin +,, respectively. Point a already has been fixed by calcillations performed with survey data obtained at point a, and calculated lengths m'c' and c'b are projected as lengths from point a, rather than from point a'. Point b1 is thus fixed and assumed to represent the actual point b. Calculated length ac" is shorter than actual length ac, and calculated length c"bl is longer than actual length cb. Since b1 is the point from which the next deeper segment will be projected, errors are cumulative. Cumulative error continues to increase as long as the inclination angle continues to increase. When the inclination angle decreases (Fig. 2), calculated length ac" is longer than actual length ac, and calculated length c"bl is shorter than actual length cb. These errors also are cumulative, but differences between calculated and actual lengths are opposite in mathematical sign to differences demonstrated in

Jan 1, 1969

By Edward Wichers

THE purpose of this paper is to set forth the matters of principal interest in connection with work done in the past few years on the purification of the metals of the platinum group, including the study and modification of methods already in the literature and the development of new procedures. For the most part, the results will be given in summary form, reserving the publication of detailed data and directions for a forthcoming paper to be issued by the Bureau of Standards. In recent years increasing interest has been shown in the preparation of the pure platinum metals, both by those concerned with the manufacture of the metals and their alloys for scientific and industrial purposes and those who are engaged in the study of the chemical or physical properties of the elements. The purification of the metals usually has been regarded as a matter so involved and difficult as to require the attention of specialists. It is hoped that this paper will show that any of the metals can be prepared in any desired degree of purity by relatively simple straightforward chemical methods. For the most part, it is thought that the methods given are suitable for small-scale refineries as well as for the laboratory; also, that they will bring the time required for the purification of any of the metals within reasonable limits. The new procedure suggested for purifying platinum should prove to be much shorter than any methods described in the literature.

Jan 1, 1928

By Mitchell I, Gelfi P, Dunne R, Pyper R

Dump leaching at Teller in its present form began in the fourth quarter of 1988 as an adjunct to milling operations. Initial plans called for a dedicated dump leach facility capable of processing ore at an annual rate of 2.0 million tonnes. Construction of a dump leach pad, collection and process ponds, carbon adsorption system, elution plant as well as reagent addition and ancillary facilities was initiated in mid-1988. During the course of construction, additional reserves were proven. As a result, design throughput was increased to 4.0 Mtpa. Leach pad capacity and solution supply systems were upgraded to handle the larger throughput. However, the carbon adsorption/elution facilities were not upgraded due to space limitations. During 1990 it was decided to expand the dump leach operation to 6.0 Mtpa. Construction of a second leach pad was required which was initiated in early-1991. Plans were again upgraded prior to completion to a target annual throughput of 10.0 million tonnes was. A further two leach pads have been constructed. The first of these being completed during the latter part of 1992. Construction of the latest and largest pad commenced early in 1994.

Jan 1, 1994

THE Geophysics Education Committee has devoted several years to a consideration of the problem of training geophysicists. Past reports have dealt largely with fact finding and with the discussion of particular aspects of geophysical education. In the present report it is proposed to review the subject more comprehensively. This involves the question of what educational qualifications the geophysicist of the highest professional standards should possess, and the related question of what changes must be effected in existing educational institutions in order that prospective professional geophysicists may obtain instruction of the desired quality. The type of geophysicist here contemplated is one familiar with what is known already in the several branches of earth physics, and capable not only of following contemporary progress in any of these branches, but of contributing to that progress in a research capacity. Geophysics in its broadest sense, as has been emphasized repeatedly by this Committee, is the study of the physics of the earth and of terrestrial processes. This includes both the static and the dynamic characteristics of the gaseous, the liquid, and the solid portions of the earth, as well as its gravitational, thermal, and magnetic and electrical manifestations. Some branches of earth physics have been cultivated but slightly; others have reached an advanced state of development. Those branches whose development is sufficient to warrant explicit recognition in the form of organized Sections of the American Geophysical Union are: geodesy, seismology, tectonophysics, and volcanology, dealing with the rock constituents of the earth; oceanography and hydrology with the aqueous constituents; meteorology with the atmospheric constituents; and terrestrial electricity and magnetism with the electromagnetic manifestations. At present, instruction on the professional level in any of these branches of earth physics can be obtained in but few universities in North America. In most institutions where such instruction is undertaken different subjects are given in different and independent departments. Geodesy and hydrology are taught, if at all, as a part of civil engineering. The nearest approach to volcanology and tectonophysics ordinarily is represented by petrology and structural geology given

Jan 1, 1944

By Alfredo Valdivia, Hamed Nejad, Vincent Monaco, William Cao

"The East Side Access (ESA) CM005 Contract - Manhattan South Structures - consists of the installation of the waterproofing and final concrete lining for railroad tunnels, 3-Level Wye track turnout structures, segments of the Main Cavern Station, and a series of Ventilation Structures excavated beneath the existing Metro North Railroad (MNR) Grand Central Terminal. Several key team decisions made collectively by the Construction Manager (CM), Designer, and the Contractor has allowed the scheduled construction duration of 29 months to be maintained. These strategies include the use of alternate design and construction methods, including the use of pneumatically applied concrete lining and precast lining. This paper discusses these strategies, and illustrates how successful teamwork and cooperation during the execution of a large-scale construction project can lead to lowering costs, improving quality, and maintaining the overall project schedule. INTRODUCTION The East Side Access Project The Long Island Railroad (LIRR) currently transports commuters from Long Island into Manhattan, terminating at the already over congested Penn Station on the west side of Manhattan. Once completed, the ESA Project will provide LIRR commuters direct access to the east side of Manhattan underneath Grand Central Terminal. The ESA Project will help alleviate the congestion at Penn Station, which currently accommodate the NJ Transit, Amtrak, and LIRR lines; reduce travel time for LIRR passengers traveling to the east side of Manhattan and facilitate connections to the NYCT Subway System and Metro North Rail Road. The ESA Project includes building new tunnels and facilities under Manhattan and Queens. (See Figure 1).The Manhattan Alignment In the Manhattan segment of the ESA Project the excavation in hard rock of tunnels, cross passages, caverns and shafts has been completed by tunnel boring machines, drill and blast, and road header. The construction of the structural concrete final lining, interior structures and fit-out of the previously excavated caverns and tunnels are currently being performed under Contract CM005 Manhattan South Structures awarded to Michels Corporation and Contract CM006 Manhattan North Structures awarded to Frontier Kemper Constructors Inc. This paper focuses on the design and construction aspects of Contract CM005 which is the first ESA Contract in Manhattan to successfully construct concrete final linings in pre-existing excavated areas."

Jan 1, 2016

By L. Li

Iron removal is a common procedure in hydrometallurgy of non-ferrous metallic ores. Chemical precipitation and solvent extraction are currently the main methods employed for separation of iron from copper leach solution. However, chemical precipitation methods have the problem of producing large amounts of iron precipitates, and/or requiring high temperature and high pressure conditions for precipitation. The precipitates are difficult to separate from the solution. Emulsification is a general problem for solvent extraction, which causes loss of extractants and contamination of the electrolyte. A common problem for solvent extraction and chelating ion exchange processes is the difficult iron stripping process. Therefore, finding an efficient and environmentally friendly method for iron removal is of great significance. In this paper, new processes of using ion exchange resins to remove iron from copper leach solution have been investigated. Salicylic acid, amino carboxylic acid, amino phosphonic acid and hydroxy-oxime resins were employed to adsorb iron from a simulated copper leach solution containing 40 g/L of Cu2+ and 36 g/L of Fe3+. It was found that a hydroxy-oxime resin, named Z-Fe, has excellent adsorption selectivity on Fe3+. Desorption behavior of the resin was studied by two step elution using dilute H2SO4 and oxalic acid solution, respectively. After optimizing the adsorption-elution processes, the extent of removal of iron from the simulated copper leach solution using resin Z-Fe was 90%, while copper recovery could reach 100% in closed circuit processing.

Jan 1, 2016

By J. Huot

It has been shown that magnesium-based metal hydrides such as Mg2Ni could be synthesized by high energy mechanical alloying. This process creates a nanocrystalline alloy that has enhanced hydrogen sorption properties due to the high density of defects and grain boundaries. Unfortunately, this process also requires a long synthesis time (up to 100 hours in some cases). In order lo reduce processing time and cost of synthesis, we have investigated the effect of milling at elevated temperature under an inert atmosphere. Milling at high temperature improves interdiffusion of the elements and reduces the number of structural defects such as vacancies, dislocations and internal strain. It was found that by milling elemental powders at 200°C. a complete synthesis of Mg2Ni could be achieved in 8 hours. This synthesis time is roughly an order of magnitude lower than that of the process conducted at room temperature. The hydrogen sorption kinetics and capacity of this material are comparable to Mg2Ni synthesized at room temperature.

Jan 1, 2002

By Yoshiaki Suzuki

Since 1973, Saganoseki Smelter & Refinery had operated two flash smelting furnaces together to produce 330,000 mtpy of copper. However, in 1990's, economical situation required the smelter more increased productivity to remain competitive. The program, to integrate two flash furnaces into one was carried out maintaining the same production. Modifications were done on the pneumatic concentrate drying system, concentrate feeding system, concentrate burner and furnace cooling system, etc. to double the, furnace throughput. A new large cryogenic oxygen plant was constructed replacing two old plants. Single flash smelting furnace operation has started in March 1996. This paper describes about details of modifications and operational results.

Jan 1, 1998

GEORGE F. KUNZ, New York, N. Y. (written discussion*).-We have been informed that the nickeliferous ores of Sudbury could furnish more palladium than the whole of the present world supply, together with a large amount of platinum. As the quantity of ore melted in Sudbury in 1916 totaled 1,521,689 tons, giving 80,010 tons of matte, and as the average of 3 years, up to 1915, are stated to show an average of 0.10 oz. of platinum and 0.15 oz. of palladium per ton of matte, this would indicate the presence of 12,000 oz. of palladium and 8000 oz. of platinum in the ore mined in 1916.1 Interest in the platinum situation is now more intense than it has ever been, and the great importance of this metal for many special uses is being increasingly appreciated. For munition manufacture, for chemical apparatus, in dentistry, and for jewelry, it has been and continues to be in great demand in spite of the phenomenal rise in its value. It is true that this has necessarily led to a search for substitutes, especially for dentistry and chemical uses, but while some of these have been found to answer the needs fairly well, for many 'other purposes platinum is still employed in spite of its great cost. As to the jewelry industry, the most public-spirited efforts have been made to restrict its use, and its employment in the manufacture of watchcases, purses, bracelets, and catches has been abandoned, gold being used in its place. The prime cause of the present shortage is, of course, the elimination of 'the Russian supply which, in normal times, constituted probably more than 90 per cent. of the world's production. This makes an intensive

Jan 4, 1918

By Nelson Severinghaus

THE Rock Chapel plant of Consolidated Quarries Corporation (Fig, 1) is three miles northeast of Lithonia, DeKalb County, Georgia, It was opened about eight years ago for crushed stone aggregate. This paper reviews a number of experiments that have been tried in drilling and blasting, and gives the practice in use today. It also presents several theories on the action of explosives in this type of blasting. FIG, 1.-PLANT OF CONSOLIDATED QUARRIES CORPORATION, WITH QUARRY AT UPPER LEFT. The rock worked is a bare dome of granite gneiss about 3000 ft. in diameter, rising 150 ft. above the surrounding ground (Fig. 2). It is uniform in composition and quality, without seams, and extends down-ward to unknown depth below the quarry floor. A water well drilled 600 ft. remained in the same rock. The principal difficulty encountered in blasting is an easy split, which tends to break down the rock in large blocks.

Jan 1, 1938

To reuse chromium, nickel, and molybdenum now lost in stainless and specialty steel-making wastes, and simultaneously to overcome the current environmental problem resulting from landfilling these wastes. Approach A variety of stainless and specialty steelmaking wastes are agglomerated and recharged into the plant's electric arc furnaces. How It Works Stainless and specialty steel-making wastes such as bag-house dust from the electric arc furnace, dust from the argon-oxygen decarburization unit, grinding swart, and mill scale are blended in proportion to the ratio in which they are generated. Next they are agglomerated on a pelletizer with an addition of a small amount of carbonaceous reducing agent, and air-dried in preparation for being recharged into the furnace. Some mixtures of wastes tested in the laboratory required the addition of binders and/or the use of ovens in lieu of air-drying to produce sufficient pellet strength. Although the optimal maximum particle size of wastes being pelletized is 35 mesh, somewhat larger particle sizes were satisfactorily pelletized during in-plant tests. The photograph shows a typical mixture of wastes and the pellets made from them.

Jan 1, 1981

By David Bigby

Room and pillar mining with full pillar extraction is one of the most hazardous systems of underground coal mining, a significant hazard being the potential for sudden goaf override. The Autowarning Telltale (AWTT) is a new development for pillar extraction operations, based on the well proven and simple Rockbolting Telltale safety monitoring device. It is now being applied in room and pillar coal mines in India, with significant potential for application worldwide. The Autowarning Telltale is an intrinsically safe low-cost, self-contained unit installed into the roof either during pillar development or prior to pillar extraction. It provides a highly visible warning via flashing Light Emitting Diodes (LEDs) when a preset level of roof movement has been exceeded. The paper provides a full description of the instrument and two case histories of its initial application at fully-mechanized Indian sites using the split and fender technique.

Jan 1, 2011

By Peng Bing

Stainless steelmaking dust is classified as a hazardous waste due to higher than acceptable heavy metal leachabilities such as zinc, lead, cadmium and chromium. In addition to being an environmental hazard, the flue dust is also an economical concern to stainless steelmakers as it contains large amounts of valuable alloying elements, especially for iron, chromium and nickel. A new technology of direct recycling of stainless steelmaking dust has been developed to recover the metals from the dust. But it was found that zinc was accumulated in the dust collection system in practical run of direct recycling. This study focuses on the effect of the operating parameters such as temperature, dust feed rate and the ratio of CO to dust on the reduction of zinc oxides present in the dust. The mathematical model for the reduction process was setup based on the experimental research. According to the mathematical model, the temperature has obvious effect on the reduction of zinc. It is benefit to the process of zinc reduction to increase the temperature. But the temperature will not be the main factor for the reduction process after 1228C. It will promote zinc reduction to decrease the dust feed rate and control the ratio of dust to CO. It was also found from the experiments that ZnFe2O4 in the dust could be decomposed at high temperature. Decomposing ZnFe2O4 in the dust increases the recovery of zinc from the dust distinctly.

Jan 1, 2006

By Leigh J. Wardle

Significant coal reserves in New South Wales lie under areas with steep topography such as valley slopes and cliffs. Subsidence predictions are difficult to make for these locations as existing empirical databases cannot cover all permutations of topography and mining geometry. Two dimensional numerical model alternatives are of limited applicability. Consequently a novel three-dimensional numerical model is developed including the detailed panel layout, realistic rock mass properties including the full stratigraphy, goat behaviour and actual surface topography. Model results show the same trends as subsidence measurements from Baal Bone Colliery in the Western Coalfield of New South Wales

Jan 1, 1992

By John W. King

Uranium ore was first discovered in the Edgemont district of the southern Black Hills in the summer of 1951. The discovery was not made known for some time, but after the news leaked out prospecting became intense, and several hundred claims were staked in the spring of 1952. The Hot Springs Sub Office of the Atomic Energy Commission was established at that time and airborne radiometric surveys were commenced by the Government and by private companies. During the succeeding summer another important discovery was made by private airborne surveys in the northern Black Hills, and the area favorable for uranium ore was expanded many times. Between that summer of 1952 and the present, many individuals and groups have explored, developed, and exploited their claims until now uranium ore is produced in significant quantities and substantial reserves have been developed. The Black Hills portion of the geologic map of the U. S. issued by the U. S. Geological Survey is shown in Fig. 1. Sedimentary formations are exposed as a series of cuestas and hogbacks in a roughly annular pattern with the older sediments resting on the pre-Cambrian core, which is exposed in the eastern and southern portions of the dome.

Jan 1, 1956

By K. C. Li

TITANIUM, because of its high strength, weight ratio, and high melting point, became the metal of the jet age. Zirconium, because of its low neutron cross section and high corrosion resistance to hot water, became an integral part of the nuclear era. Since both metals are very similar chemically, more or less the same process is used for their production. The sudden rise of this new industry of titanium and zirconium seems to have caused some uncertainty as to the future development of processes for making these metals. Although zirconium was discovered in 1789 and titanium in 1790, it was not until 1945, six years after W. J. Kroll patented his process, that F, S. Wartman of the U. S. Bureau of Mines perfected the technique of producing ductile titanium, and it was not until 1946 that Kroll perfected the technique of producing ductile zirconium in commercial quantities. Since then the Government and private industry have spent millions of dollars each year constantly searching for new methods, with the hope that some day titanium can be produced as economically as aluminum and magnesium or as cheaply as stainless steel.

Jan 11, 1957