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By John S. Anderson

The need for fuels and minerals in this country is estimated to double, triple, or even quadruple by the end of the present century. Even assuming more recycling of scrap metals and some priority allocation of energy, as has been done, for instance in war time, the projected increase in the nation's population and ever-increasing wants of that population will require vastly more minerals than are now being produced. Since mineral ores are being mined at lower grades, and since all minerals, including fuels, are having to be mined from deeper deposits, the amount of surface land to be disturbed will, inevitably, be increased. We cannot depend on foreign sources to supply all the extra requirements, since the non-U.S. population is increasing, in most cases, faster than our own. Furthermore, starting from a lower base, their mineral needs may accelerate more rapidly than ours. Restrictions on exports may be applied in foreign countries, if it appears that remaining reserves are not sufficient to fill the national needs. In vice; of the opposition which the mineral industry is receiving, as has been well described at these sessions and elsewhere, what can we, as mineral producers, anticipate as regards our ability to continue to operate, to sway nothing of expanding production? Although not minimizing the problems involved, it seems obvious that, except under emergency conditions, the country cannot tolerate a reduction in the available

Jan 1, 1971

By E. (Walt) van Walsum

The MPTM was first applied in the U.S.A. in 1950 as described by Lewis, W.E., 1951. The method was then abandoned in the USA and rediscovered some 20 years later in France where it was greatly improved and widened in its scope of application. It was subsequently successfully introduced to Italy and Spain. The technique, at its present stage of development, provides solutions to tunneling in soil and in the softer rock types, which often were troublesome geological environments for tunneling. When used in conjunction with drilling-and-blasting, over break, excessive vibration, noise and fissuring of the rock can all be avoided. When used as an alternative to the New Austrian Tunneling Method (NATM), the MPTM provides safe, full face tunneling in stead of multiple headings, excavated sequentially; in addition, surface settlement can be virtually eliminated. When used as an alternative to a TBM, the method's flexibility and low capital cost make it attractive. This attractiveness is enhanced when ground conditions are erratic or when the length of tunnel to be excavated is limited. The method holds promise for tunnels of large cross section, to be excavated in soft ground or rock with unconfined compressive strengths of less than 80 MPa (11 600 psi). While in itself not new, recognition and development of the method's potential are. Further development work, aimed at increasing the range over which the MPTM can be applied, is in progress.

Jan 1, 1993

By John G. Viets, J. Robert Clark

A multielement extraction system is being used successfully to provide essentially interference-free geochemical analyses to aid in gold exploration. The Methyl isobutyl ketone-Amine synerGistic Iodide Complex (MAGIC) extraction system separates Ag, As, Au, Bi, Cd, Cu, Ga, Hg, In, Mo, Pb, Pd, Pt, Sb, Se, Sn, Te, T1, and Zn from interfering geological matrices. Quantitative extraction of these elements is accomplished over a broad range of acid normality, making it possible to economically determine all 19 elements from a single digestion or leach solution. The resulting organic extracts are amenable to analysis by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and flame atomic absorption spectroscopy (FAAS). For many years the principal shortcoming of ICP-AES was the complex spectral and stray-light interferences that were caused by the extreme variability of components such as Fe. Na, and Ca in common geological matrices. The MAGIC extraction allows determination of the extracted elements with enhanced sensitivity, from a virtually uniform matrix, by ICP-AES and FAAS. Because of its simultaneous multichannel capabilities, ICP-AES is the ideal instrumental technique for determining these 19 extracted elements. Ultratrace (sub-part-per-billion) determinations of Au and many of the other extracted elements can be made by graphite furnace atomic absorption spectroscopy (GFAAS), following back stripping of the extracts. The combination of the extraction followed by stripping of the organic phase eliminates 99.999% of potential interferences for Au. Gold determination by GFAAS from these extracts under the specified conditions yields a fourfold improvement in sensitivity over conventional GFAAS methods. This sensitivity enhancement and the interference-free matrix allow highly reliable determinations well into the parts-per-trillion range.

Jan 1, 1990

By J. A. Cervantes

A statistical model for assessing the risk of ground subsidence in abandoned mine areas is presented. The model is based on the relationship that exists between .the frequency and the location-of subsidence events in a given area and the physical conditions of the ground. These conditions can be described by a series of geological, mining, and physical variables. The model suggests the existence of regions in the multidimensional space of variables which are associated .with increases or decreases in the frequency of subsidence events. Regions associated with an increase in the frequency of subsidence events correspond to regions of higher risks, and vice versa. Risk assessment is based on the ability to express the limits of these high and low risk regions in the, space of variables, and on the ability to express the degree of membership of blocks of land within any of these regions. The theoretical framework for the model is extracted, from discriminant analysis. Risk is quantified by the probabilities of membership of blocks of land into any of these regions. Risk maps are produced by displaying membership probabilities in. appropriate contouring levels. The model has been applied in two urban areas where subsidence of the ground has been active in the past. The two areas are Penn Hills, near Pittsburgh, and Scranton/Wilkes-Barre in northeastern Pennsylvania. In this paper, only the results for the Scranton/Wilkes-Barre area are presented. Those for the Penn Hills area have been presented elsewhere (Cervantes, et al, 1990). In the- Scranton/Wilkes-Barre area, geostatistical estimates of variables likely to affect the stability of the ground were made using samples from 53 drillholes. The estimates were made for 2000x2000 ft squared blocks of land covering the study area. Discriminant functions were computed from the estimated variables and used to establish regions for classifying blocks of land into one of these two populations: 1) blocks not likely to have a subsidence event, and ii) blocks likely to have one or more subsidence events. The same, discriminant functions were used to compute membership probabilities for blocks of land to tall within any of these two populations. These probabilities were contoured to produce a risk map. The risk map produced compares well with the location of the subsidence events which have occurred to date in the area.

Jan 1, 1992

By S. Su, S. Natansohn

This report describes a process for tungsten recovery from Searles Lake brines and upgrading its concentration to useful levels. The method consists of a combination of a liquid-solid and liquid-liquid extraction step and results in a product stream containing more than l00g W03/1. This technique is also effective in substantially reducing the concentration of objectionable impurities in the tungsten product. An ion exchange extraction mechanism is postulated.

Jan 1, 1983

By E. P. Chen

This investigation involves the development of a two-dimensional continuum model for the description of jointed media. Specific application of the model developed here is for the potential geological disposal of radioactive waste in the layered sequence of fractured volcanic tuffs under Yucca Mountain, Nevada. This is currently being considered by the Nevada Nuclear Waste Storage Investigations Project, administered by the Nevada Operations Office of the U. S. Department of Energy. The work is a direct extension of the previous constitutive model by Thomas (1982) based on the work of Morland (1974). The main feature of Thomas's model includes two parts: a continuum approximation based on average discontinuous displacements across jointing planes within a representative elementary volume, and a material constitutive description based on linear elastic matrix material behavior and nonlinear normal and shear joint behavior between jointing planes. The mathematical descriptions by Morland based on strain partitioning among matrix material and joint sets allow multiple joint sets to be included in the model. However, the initial effort by Thomas to implement Morland's mathematical model included only a single set of joints. To make the material model reflect more realistically the field characteristics, the current work extended Thomas's model to include orthogonal sets of joints. The nonlinear elastic normal joint behavior is retained in the present model. Joint shear response was treated as linear elastic in the shear stress versus shear displacement relationship prior to attaining the stress level governed by the Coulomb friction criterion. Beyond this critical stress value, a horizontal line is assumed in the work of Thomas for the shear stress versus slip displacement relationship such that the shear stress remains constant while the slip displacement increases. Motivated by experimental observation, the current work generalized the shear response to allow a line with finite slope to govern the slip behavior beyond the critical stress level. The inclusion of an orthogonal joint set led to a fourth order algebraic equation for the calculation of stress increments as compared with a second order equation obtained by Thomas. The nonlinear elastic normal joint behavior provides criteria which allow the selection of the root that yields result consistent with the loading condition of the problem. The addition of one more set of joints provides the potential to more completely study the interaction of various parameters representing the characteristics of jointed media behavior. Material responses to various loading conditions based on the present constitutive model have been obtained. These results and their comparisons to single joint set results are presented. Formulation of the Continuum Model The inclusion of an orthogonal joint set led to a fourth order algebraic equation for the calculation of stress increments as compared with a second order equation obtained by Thomas. The nonlinear elastic normal joint behavior provides criteria which allow the selection of the root that yields result consistent with the loading condition of the problem. The addition of one more set of joints provides the potential to more completely study the interaction of various parameters representing the characteristics of jointed media behavior. Material responses to various loading conditions based on the present constitutive model have been obtained. These results and their comparisons to single joint set results are presented. Let us focus our attention on the set with normal n first. Let the jump dilation displacement and jump slip dasplacement associated with the [ ]

Jan 1, 1986

By Richard M. Crowell, Laurie M. Tahija, Keith D. Dagel

Echo Bay Mines Ltd. operates a gold heap leach in Round Mountain, Nevada, U.S.A. In the past two years, the mine has expanded operations from 13.5 kt/d (15 kst/d) to 41.0 kt/d (45 kst/d), making it the world's largest gold heap leach operation. The expansion is a separate system from the previous 12 year old plant, yet very similar. The flowsheet contains open circuit primary, secondary, and tertiary crushing with interstage screening. A leach pad stacker loads reusable asphalt leach pads. The process plant features carbon adsorption, pressure strip, electrowinning, and electrorefining.

Jan 1, 1990

This paper reviews the technical advice available to support companies in the delivery of social aspects of sustainable development. It will draw on diverse experience from the sparsely populated plains of the Central African Republic, one of the poorest countries in the world, to the densely populated villages of the Carpathian Mountains in Slovakia. It will review basic requirements for the consideration of social issues, as well as guidance on international best practice. It will review: the legal basis; coverage; consideration of alternatives; scope; inclusive decision-making; indicator development; impact monitoring and evaluation. The paper will discuss the breadth and depth of social issues for consideration, including the realms of responsibility of a company in terms of social development in different operating environments. The extractive industries invest substantial amounts of money which typically dwarfs local development, health or education budgets. Capacity building for local authorities is not directly the role of the company, but when understood as a strategy for risk management, it can play a vital part of sustainable development that benefits the local community and reduces the risk of social problems impacting profits. The paper will argue that social impact assessment is most effective when the outcomes are in line with a company?s principles and support core business practices. It is important that social impact assessment is viewed as an integral part of project decision-making and moves away from mistrusted PR and unsustainable philanthropy toward partnership, which finds suitable and appropriate solutions delivering ?win-win? outcomes. While development should not be seen as a direct company objective, engaging with development actors to better understand the operating context can ensure that social investment complements existing initiatives. The paper will also present different mechanisms for engaging with local actors, as well as developing successful social programmes.

Jan 1, 2007

By A. R. Bath

During the late 1970s, pilot mining tests carried out on manganese nodules in the Pacific Ocean and metalliferous mud in the Red Sea demonstrated the technical feasibility of deep sea mining operations. However, the production of manganese nodules on a commercial scale is subject to numerous technical problems. As a result, a German-French joint development project has been underway since 1985. This venture focused on three key points: nodule pick-up device, locomotion of self-propelled collectors and hydraulic lifting of nodules. This paper presents the scope of this research and development program, its main results to date and future prospects.

Jan 1, 1992

By Jon A. Hummer, Aleksandar D. Bugarski, Shawn Vanderslice, Teresa Barone

A study was conducted to examine the potential of diesel emissions control strategies based on retrofitting existing power packages with exhaust aftertreatment devices and repowering with advanced power packages. The retrofit systems, a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), were evaluated individually using a US EPA tier 2 (ter 2) engine operated under four steady-state conditions and one transient cycle. The DOC effectively curtailed emissions of CO, and to some extent organic carbon (OC), elemental carbon (EC), and aerosol number concentration. The DPF system offered substantially higher reductions in OC and EC mass and aerosol number concentrations. Both, the DOC and DPF achieved reductions in the aforementioned emissions without adversely affecting emissions of NO2 and nano-sized aerosols. The strategy of repowering with an advanced system was examined using a US EPA tier 4 final (tier 4f) engine equipped with a cooled exhaust gas recirculation system and diesel exhaust fluid-based selective catalytic reduction system, but not with a DPF system. The tier 4f engine contributed substantially less than the tier 2 engine to the EC and OC mass, aerosol number, and CO, NO, and NO2 concentrations. The tier 4f engine was very effective in reducing aerosol mass, NO, and NO2 concentrations, but it was not equally effective in reducing aerosol number concentrations. The implementation of viable exhaust after treatment systems and advanced diesel power packages could be instrumental to the underground mining industry to secure a clean, economical, and dependable source of power for mobile equipment.

By Charles Bruce

Three years ago, at a reception given during the Steel Institute meeting in New York, I heard the remark, "A new formula must be found for foreign investment." This was immediately following the takeover of U. S. Steel's Matilde operation in Bolivia. Recently, at the World Mining Congress in Lima, Peru, the subject of foreign investment was still a lively topic of conversation. The nationalization of the copper mines in Chile and recent trends in the "Third World" have made all but a few extremely wary of investment anywhere other than in the ?stable? countries. Now, the fallibility of this philosophy has been demonstrated in such "stable" countries as Canada, Australia, and Ireland. Yet, nationalization is not new to us. The events in Chile were classified as disastrous to the affected companies, but so were the effects of nationalization to the majors in Bolivia in 1952. Mexicanization of the mining industry in Mexico was considered impractical by many. Now, those who accepted it are finding it to be workable.

Jan 1, 1975

By James N. L. Lukanuski

Three porphyry copper districts in southern Arizona are partly overlain by post-ore fanglomerates which share certain physical and petrologic characteris¬tics and which may comprise a distinct and significant class of rock. These units are the Locomotive fanglomerate of Ajo, the Helmet fanglomerate of Twin Buttes-Mission-Pima, and the Cloudburst formation of San Manuel-Kalamazoo, termed "Locomotive-type fanglomerates" herein. Post-ore units at Poston Butte and Lakeshore, Arizona, and Sar Chesmeh, Iran, also appear to fit this class. "Locomotive-type fanglomerates" are composed of poorly sorted conglomerates, lenticular sandstone beds, andesitic to rhyolitic flows and tuffs, and unique monothologic landslide breccias. They contain fragments of holyokeite - - a rare oligoclase lava of porcellaneous appearance. Their basal contacts are considered to be depositional and overlapping, sometimes complicated by later low-angle faulting. They arc quite different than the younger Cila, Pantano, and most "Whitetail" alluvial beds, and the older Amole, Recreation, Claflin Ranch, etc. elastics; in particular they are thinner and less widespread. Their ages are Eocene to late Oligocene. "Locomotive-type fanglomerates" may be genetically related to porphyry coppers as products of subsequent differentiation and volcanism, and sedimentation in short-lived basins of restricted area and extreme relief. They might be utilized as reconnaissance guides to target areas and as structural guides within target areas in the southwestern U.S., Northern Mexico, and elsewhere.

Jan 1, 1975

By Robert D. Brown, Charles A. Sorrell

The decade of the 1980's saw "advanced materials" become a key factor among the industrialized nations, with the United States, Japan, and the European Economic Community being the major competitors. All three have identified communications technology, advanced materials, and biotechnology as the keys to future industrial leadership and the closing decade of the 20th Century is expected to be an era of rapid development and restructuring. The progress of EC'92, the effort to develop uniform standards and remove trade barriers in Europe; the determination of Japan to commercialize advanced structural ceramics, alloys, composites, and superconductors; and the emergence of less developed countries as major supplies of commodity materials pose enormous challenges to the position of the United States as an industrial and financial leader. A consensus is developing that the industries that are first to commercialize the large array of new structural materials and electronic, optical, and magnetic materials and devices will be those who determine the structure of national and world economics. Many technical, economic, legal, political, social, and cultural factors are important determinants in the race to commercialize new materials. Millions of words have been written about these factors and their interdependence; yet the sheer complexity of the problems, the rate at which changes are taking place, and the economic risks involved are so great that government policy makers and industrial decision makers find adequate understanding to be very difficult. Of the many factors involved in advanced materials, the Bureau of Mines has the statutory responsibility to provide information on where materials can be found and how they are mined, extracted, purified, combined, and recycled. It is obvious that minerals availability is essential to implementation of any new technology just as there can be no commodity metals industry if the ores are not available. Because "minerals availability" for commercialization of advanced materials and devices is more complex than for commodity materials and a new mix of materials and processes is emerging, the Information and Analysis Directorate of the Bureau of Mines is redirecting resources to provide reliable information for policy and decision making. The Office of Advanced Materials Coordination (OAMC) was established as a staff operation in July 1987 to assist the efforts of the divisions and branches. The key issues and problems were defined and the role of the Bureau was outlined (Sorrell, 1987, 1988). In February 1990, the functions of OAMC were transferred to the new Branch of Advanced Materials, a line organization parallel with the Branches of Ferrous, Nonferrous, and Industrial Minerals, and was given the responsibility for developing new methods to acquire, analyze, and disseminate information about new materials. The purpose of this paper is to provide definitions, a summary of major issues and problems, an overview of minerals and processing availability problems, and a perspective of the ways in which the mining and materials industries can help to ensure domestic availability of raw and processed materials.

Jan 1, 1990

By R. J. Roman

Introduction This paper attempts to describe the characteristics of the industrial minerals segment of the minerals industry that make it different from the other segments. Also described are the trends, strengths, and shortcomings in the industrial minerals segment. This may help professionals in the minerals industry determine if there is a place for them in industrial minerals. Industry Overview It is difficult to generalize when describing the industrial minerals industry. Some products, such as cement and potash, are produced exclusively by large, well capitalized and technically sophisticated companies. Others, such as sand and gravel, are generally produced by small, family-owned companies operating on a shoestring budget. Still other products, such as feldspar, are produced by both types of companies. Not only are the companies vastly different, the products and marketing of their products are also different. Industrial mineral products are sold based on their physical characteristics (abrasives), or their chemical characteristics (trona), or both (glass sand). Marketing can be direct by the producing plant, a corporate office handling products form several plants, or through distributors. The geologic, mining, and processing skills needed can be minimal or sophisticated. There can even be large differences in the technical skills needed in two plants producing the same product. One feldspar producer may only need to mine and grind his ore, while another may use a delicate flotation process. One easy generalization is that there are industrial mineral operations in all geographic locations. A second is that industrial minerals offers more opportunities to entrepreneurs than the metals field because of the variety in the sizes and types of operations. Industry Growth Industrial minerals must be considered a mature industry. Consequently, little exciting growth can be expected. Over the past 30 years, industry sales have grown at a rate of 6.2%, compared to a 6.7% growth rate of the GNP (Kliff, 1978). A 3.8% growth rate has been forecast for the remainder of this century. The fortunes of those plants producing a product for local consumption will depend on the prosperity of the local economy. The fortunes of those plants that sell into the national market will depend on their competitiveness in their industry. Major industrial mineral products are shown in Table 1. The first three commodities account for 66% of the industrial minerals market. Typically, deposits of stone, sand and gravel, and the limestone, silica, and clay needed for cement are easy to find and mine. Role of Mining Engineers and Geologists Because a sophisticated techcical knowledge of geology or mining is not required, very few geologists and mining engineers are employed in industrial minerals. Geologists working for these companies function less as geologists than managers and executives dealing with permitting and land acquisition. Likewise, mining is done mostly by open-pit methods. It is generally supervised by an individual experienced in the operation and maintenance of heavy equipment, not a mining engineer trained in rock mechanics or computer methods of mine planning. What of the geologists and mining engineers employed by the industrial minerals industry? Many gained their positions as a result of their experience dealing with the regulatory agencies that control the operations of all mines and mills. Their technical expertise in geology or mining becomes only a side benefit. Finding and mining industrial minerals does not generally require the concentrated efforts of geologists and mining engineers. But the processing of the ores does

Jan 2, 1985

By C. F. Curry

In the early 1940's Humphreys Mining Company in Florida pioneered heavy mineral mining with a dredge in the United States, In 1948 Du Pont, in conjunction with Humphreys, opened their first of two mining operations recovering a titanium dioxide product in Florida. Later on in 1952 Du Pont opened their second plant, both of which used a cutterhead suction type of operation. This process is also used in heavy mineral mining in Australia and Africa. In 1957 ASARCO started prospecting in New Jersey. Test borings indicated a large deposit of ilmenite bearing heavy mineral sands had been deposited and concentrated in an area near Lakehurst in central New Jersey. Humphreys Mining Company was contacted about the possibility of mining the ASARCO New Jersey property in much the same way as Du Pont and themselves were doing in Florida. An extensive study was made to determine the economic feasibility of mining the ASARCO property. During this study, extensive test drilling and samples for a pilot plant were taken.

Jan 1, 1975

By Siegmund Babendererde

Introduction Lyon, with 1.1 million inhabitants, is the third largest city in France after Paris and Marseille. It is a lively industrial centre. Lyon lies at the intersection of many transport routes and at the fluence of Rhone and Saone. Like all large cities, Lyon is attempting to alleviate inner city traffic problems by constructing a metro. Metro construction in Lyon began with tunnels built by cut and cover methods along the streets. Deep diaphram walls, which were back anchored and toed into imperveous strata, formed the excavation walls. It is a very economic and simple method. However during the construction period, it has the disavantage of strangling urban life for several years. It is therefore increasingly being replaced by subsurface tunnelling methods. As it was decided to build the metro tunnel between the Guillotiere and St. Jean stations, and thus cross under the Rhone and Saone, the client, Semaly, put the contract out for a competitive tender in which the general parameters were defined. Line, level and construction method were left to the contractor. There was an extensive examination of the tenders, during which reference projects from competitors in Japan were visited, as well as in Germany. Finally the consortium of Dragages, Campenon Bernard, Colas and Hochtief was awarded the contract to drive this tunnel section with an hydro-shield and an extruded steel fibre concrete lining, a Hochtief design.

Jan 1, 1987

By Richard Klimpel

1. Introduction Laboratory and industrial grinding tests have shown that the process of size reduction can be significantly influenced by chemicals added to the powder or slurry being ground. The terms grinding aid or grinding additive refers to a substance which when mixed into the mill contents causes an increase in the rate of size reduction. The increased rate can be used to grind a higher feed rate to the desired product size or it can be used to produce a finer product size at a fixed feed rate. Whether the use of a grinding aid is justified in any given situation depends on the cost of the substance versus the improvement of output or product quality obtained with its use. Obviously, an expensive chemical must be effective in very small concentrations if it is to be economically justifiable; the cost criteria is calculated on the basis of the cost of the grinding additive per ton of material ground. Although there is direct experimental verification of the advantageous effect of grinding additives, no sound scientific explanation has yet been offered which explains or predicts the general behavior of additives. Rose and Sullivan have summarized most of the work undertaken prior to 1950 and Hartley, Prisbrey, and Wick have recently prepared an updated synopsis of the grinding additive literature. Many of the studies reported consist of subjecting materials with simple geometric shapes to some type of hardness or controlled single fracture test. On the other hand, a number of the studies were carried out on operating industrial scale mills, with little control or precise monitoring of the effect of the additives.

Jan 1, 1977

In this presentation, CiDRA?s patented technology platform and its applications will be described. CiDRA's non-invasive, passive sonar array-based flow meter technology provides the volumetric flow rate of single or multiphase fluids by measuring the speed at which naturally occurring structures such as turbulent eddies or density variations convect with the flow past an axial array of sensors. These sensors are incorporated in a band that is wrapped around the outside of the pipe, resulting in no process downtimes for installation and unprecedented reliability. This technology has resulted in a unique ability to measure the flow rate of most fluids ? clean liquids, high solids content slurries, pastes, and liquids and slurries with entrained air. Unique and difficult minerals processing flow measurement problems and their solutions will be described. Examples of these problems include flow measurements in froth lines and flotation feed lines with entrained air, slurry lines with magnetite and other magnetic ore, slurry lines with abrasive or corrosive materials, high pressure lines, and lines exhibiting scale buildup. Recent technology developments will be covered.

Jan 1, 2008

By William J. Francart, Edward J. Miller

The utilization of computer based monitoring systems for fire detection in underground coal mines has grown significantly in the past seven years. In 1984, an annual MSHA survey identified a total of 38 systems being used in U.S. underground coal mines, while a 1990 survey indicated the number has risen to 112. The applications for mine monitoring have also changed according to the annual surveys. From April 24 to June 21, 1990, investigations were conducted by personnel of the Ventilation Division, Pittsburgh Health Technology Center, in cooperation with Coal Mine Safety and Health, concerning the installation and operation of Atmospheric Monitoring Systems in underground coal mines. These investigations were conducted to gather information concerning the ability of the AMS to detect fires and heatings, false and nuisance alarm frequencies, information related to system maintenance, and information related to employee training on system operations. This paper addresses current applications of the systems, fire and heating identification rates, application of systems in dieselized coal mines, system maintenance, and employee training requirements. While deficiencies were identified in some applications, results of the studies and survey indicate the use of atmospheric monitoring systems can be effective in identifying mine fires and heatings.

Jan 1, 1991

By B. Govindarajan, L. S. Rao, T. C. Rao, B. R. Rao

Laboratory leaching experiments were conducted to extract potassium from glauconitic sandstone, and the effects of important variables were studied. The reduced time plot (RTP) for all of the variables obtained from the experimental data has been quantified by this simple equation: R = 100 (1 - exp (-0.693 *(T/T50)0.605) The time required for 50% extraction (T50) has been correlated by a regression equation to variables such as acid strength, temperature, fluorite: glauconite ratio and % solids. Both of these equations were used to predict the extraction percentage at different process-variable levels. In addition, several other experiments were conducted at arbitrary levels of the variables to verify the equations developed.

Jan 1, 1994