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By M. G. Ayat

Although other methods of mineral concentration have been developed over the years, gravity separation remains one of the most efficient and economical for cleaning coal. The concentrating table and the spiral separator are popular devices used for the separation of minerals by exploiting the differences in specific gravities of the product material and the gangue. While the former device has been servicing the coal industry for over 75 years, the latter seems to have not been employed extensively for coal cleaning purposes in this country. As far as coal preparation is concerned, both separatory devices seem to be most efficient for intermediate to fine size fractions. As it stands there exists a great deal of confusion amongst preparation engineers and plant managers as to whether spirals can have a place in the coal industry. If so, whether their come back is the beginning of the end for concentrating tables, or can they be employed along with concentrating tables to contribute toward more efficient cleaning processes resulting in an improvement in the overall economics of the coal preparation industry. This paper examines the efficiency of both systems for coal processing operations as well as the basic principles, operational variables, economics, advantages and disadvantages associated with each unit operation. Attempts have been made to draw conclusions and make recommendations as to which system would be more beneficial for coals of known characteristics.

Jan 1, 1986

By [Miroslaw] M. Hajdasinsk

The identification of the real internal rates of return (IRR's) of a project is essential for its economic evaluation. The existing methods for the calculation of IRR's are both cumbersome and unreliable, mainly because of their inability to effectively isolate the real IRR's and incapability of discovering multiple IRR's of even multiplicity. In this paper, a concept of the 'cash flow pattern tree used for isolation of the real IRR's of a project is presented. This concept, combined with the Sturm procedure for counting the real distinct zeros of a polynomial within a specified interval, leads to the development of a method and computer program for isolation and calculation of the real IRR's of a project. The method examines whether or not real IRR's exist, and if they do, isolates them within bounded and narrow intervals in a mathematically founded way. The isolated IRR's, whether simple or multiple, are subsequently calculated either directly or by means of an appropriate approximation procedure. Numerical examples assist the development of the method and the corresponding computer algorithm. Because any Net Present Value treated as a function of interest rate can easily be transformed into a polynomial, the method presented also constitutes a method for finding the real zeros of a polynomial.

Jan 1, 1986

By Alejandro Prieto

Traditionally, Mexico has been a mining country. This industry has played a very important role in our country's development, creating jobs, integrating geographical regions - generally very remote from urban communities - and, an essential factor in our present day economy, generating an influx of foreign currency. The Fluorspar mining industry's development started in the 1920?s, but it was not until World War II that its exploitation became consistent and started growing. During the last few years, Mexico has become the world's leading producer, with an annual output of more than one million tons, which directly generates over 3,000 jobs. The actual proven reserves can guarantee fifty years of production at this same annual rate, and it is due to this fact that the producers have not increased their reserves. However, there is concrete information of the existence of several deposits, extending from the northern border to the gulf of Mexico, forming the "Fluorspar Belt? in Mexico.

Jan 1, 1986

By Donald L. Gaughenbaugh

Under the terms of the 1970 amendments to the Clean Air Act, the EPA established national ambient air quality standards for a number of pollutants. Sulfur dioxide (SO2) was one of these pollutants. These ambient air quality standards have had perhaps their biggest impact on the power utilities. In an effort to meet the air quality standards set forth by the EPA, utilities using high sulfur fuels have been forced to install flue gas desulfurization (FGD) systems. The majority of FGD systems in operation today are nonregenerable systems, that is the by-product of the system is disposed of, usually into settling ponds. Limestone slurry is the most common reagent used to remove SO from the flue gases. The calcium carbonate (limestone) slurry interacts with the flue gas, absorbing the SO2 and forming a by-product of calcium sulfate/sulfite which is disposed of.

Jan 1, 1986

By F. L. Kadey

A discussion of fillers would not be complete without allotting adequate time to that unique and different mineral material, diatomaceous silica. Historical references to its use challenge the aesthetic aspect of man's curiosity; whereas modern scientific tools have provided a dimension of measurement that has motivated many of its more recent applications. A brief review of what is already known is in order. The diatom is a unicellular, plant-like, microscopic organism, related to the algae1. Its natural function appears to be that of a food for other marine or lacustrine organisms, The diatom's "claim to fame" from an industrial viewpoint is dependent on the fact that it secretes an opaline siliceous skeleton that must survive, chemically and structurally, the geologic processes that caused its formation in the first place; its subsequent demise, burial, consolidation, and alteration; and finally, its ultimate exploitation by man--in somewhat that order. In addition to its siliceous nature, the skeletal structure of the diatom possesses a variety of shapes, patterns, and sizes that have not only been the intrigue of microscopists for decades, but have served to set diatomite apart as an industrial mineral; and have reserved for it applications that cannot be satisfied by any other material. Its chemical inertness, its intricate structure, and its intrinsic hardness-coupled with fineness and friability-- are generally known and have accounted for its application in a wide range of filtration and filler uses. The increasing use of the electron microscope has considerably expanded our knowledge of heretofore unseen secondary and tertiary structure of submicron dimension in the diatom valve. The development of electro-sensing methods of particle size measurement which seem to supersede sedimentation and microscopic techniques has portrayed size distribution in a more realistic light. Interest in the surface chemistry of these silica structures has further strengthened our understanding for certain uses. Thus, new tools and ideas have made possible the introduction of diatomite into such sophisticated technologies as that of chromatographic supports, its improved utility in paint applications for the control of gloss and sheen, and its usefulness in the entirely new concept of "Dry Acid Concentrates." Each of these applications has been discussed elsewhere before people particularly interested in analytical chemistry, in paint, and in liquid handling, respectively, where the diatom has been a means to an end. The emphasis here, before the mining fraternity, however is on diatomite as a raw material with reference to the uses mentioned above. It is therefore toward an awareness and understanding of diatomite properties pertinent to these newer filler applications that this paper is directed.

Jan 1, 1967

By David R. Cole

Before discussing some of the specific public relations issues in Colorado mining, I would like to define public relations, identify the "publics," review Colorado's population profile, and outline Colorado's mining history. Public Relations In describing public relations, a definition which is frequently quoted appeared in the PUBLIC RELATIONS NEWS, and is as follows: "The Management function which evaluates public attitudes, identifies the policies and procedures of an individual or organization with the public interest, and executes a program of action to earn public understanding and acceptance..' As you can see, this covers a "multitude of sins."

Jan 1, 1975

By Judith A. Marks, Deane K. Smith, Jan M. Mutmansky, Maria Klimkiewicz

The mechanical mining of coal seams where roof, partings, and floor rock are extracted along with the coal often introduces large numbers of quartz particles into the mine atmosphere. This study concentrates on the quartz properties in situ and in the airborne dust to determine how they are released from the source rock and whether they are fractured by the mining machinery. Three mines using drum-type continuous miners from different geographic areas were sampled to provide a data base. The roof and floor rocks were primarily siltstones containing 5% to 25% quartz measured by the X-ray powder diffraction (XRPD) method. Much of the work presented here is based on the morphologies of the mineral grains determined by the scanning electron microscope (SEM). The study concentrated on particles of 0.2 to 10.0 µm and on particles containing > 75% Si. Mechanically-crushed quartz particles were also examined for comparison purposes. Particle shapes from the airborne samples suggested that fractured quartz particles were rare. Particle statistics also show that the average size of quartz particles in the airborne samples were similar to the average size of all particles. The conclusion is that very few quartz particles from the source rocks are fractured during mining due to their small initial size and the protection of the associated clays.

Jan 1, 1991

By Nicholas C. Lias

Quartz crystals are the raw material from which are made the crystal units utilized in filters and oscillators so vital to the performance of all long distance communications systems. These devices act as the heart of equipment that permits a single telephone cable to carry hundreds of conversations simultaneously. Quartz crystals are of value in communications because of this piezoelectric nature, that is when an electric signal is applied to the quartz, there is a resulting mechanical motion and conversely, a mechanical stress results in an electrical output signal. A plate cut from a quartz crystal will oscillate at some specific frequency, which is determined by the physical dimension of the plate. During the early stages of telephony, all quartz plates were cut from natural quartz, which was imported mainly from Brazil. Since the source of this important raw material was based upon a foreign supply which is located at a great distance from the user and could be vulnerable in time of a national emergent, it became necessary to maintain a large inventory of this strategic material. Also due to the considerable cost of natural crystals of a size and quality suitable for Bell System use, an investigation was made by Bell Laboratories into the possibility of developing a substitute material. The effort was successful and led to a joint development program between Bell Laboratories and Western Electric. This program brought about the design of manufacturing facilities capable of producing large quantities of cultured quartz at Western's Merrimack Valley Works, No. Andover, Massachusetts.

Jan 1, 1973

By C. Duke

The water treatment industry has historically been involved with reducing or inhibiting the inherant scale forming or fouling tendencies of natural waters associated with large industrial cooling water systems. Fouling is an extremely complex phenomenon. From a fundamental point of view, it may be characterized as a combined momentum, heat, and mass transfer problem. Chemical reaction kinetics is involved, as well as the solubility characteristics of salts in water and corrosion technology. It is a routine practice to over size pumps, piping and heat exchangers to compensate for fouling.

Jan 1, 1983

By D. J. Fitzpatrick

The paper reviews current mining subsidence research at The Department of Mining Engineering, University of Notting- ham. Special attention is being devoted to prediction of ground movements between the mining horizon and the surface using physical and computer-based models. The paper presented discusses linear and non- linear finite element methods and compares results with those from physical models and field observations. Special attention is focussed on the determination of the effect of caved zones on overlying and underlying geological structures. The paper presents data from comparisons with U.K. case histories.

Jan 1, 1986

By S. B. Keith

Cerro de Pasco Corporation operates five large base metal mines in Peru having a combined production of some three million tons of ore a year. An integrated complex of concentrators, smelters and refineries produces annually about 25,600 short tons of copper, 48,100 short tons of lead, 60,500 short tons of zinc metal, 102,300 short tons of zinc concentrate, 8,272,000 ounces of silver and substantial amounts of bismuth, cadmium and selenium. Geology plays an important role in these operations. The organization of detail geologic work in and around the Cerro mines was set up by John M. Boutwell in 1918 and a geology department was established in 1920. Growing through the years, the department technical staff now numbers over thirty men and. their work covers all phases of geological investigations. Many outstanding geologists of the past and present, too numerous to name here, have studied and contributed to the knowledge of the deposits and the ever growing list of Cerro "alumni" must rival that of any other mining organization. Numerous papers on the geology of Cerro's mines can be found in the technical literature and several doctoral theses have been presented on Cerro subjects as indicated in the attached bibliography, Specimens of Cerro's ores can be found in museum, college and university collections throughout the world. Yet, as with all mines and mining districts, the geologic knowledge of Cerro's deposits in Peru is being revised and added to constantly. This presentation cannot hope to cover adequately all the phases of the geology and mineralization. For a more complete background and discussion of the mine you are referred to the bibliography. Here I shall outline only briefly the more important geologic features and describe some of the newer developments of recent years The credit for the data presented here belongs to the many geologists who have worked or are now working for Cerro de Pasco Corporation, but I must assume sole responsibility for any omissions or variations in the interpretation of their work.

Jan 1, 1965

By H. Barry Holt, Charles A. Bischoff

On November 15, 1990, President Bush signed the Clean Air Act Amendments of 1990. The new legislation is sweeping in its demands for cuts in smog, acid deposition, toxic air pollutants and ozone-depleting chemicals. The Amendments will siqnificantly alter air quality permitting and compliance and are estimted to cost billions of dollars to implement. This article provides an overview and summary of each of the eleven titles of the Amendments. It also addresses how the Amendments will be implemented.

Jan 1, 1991

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

Roof bolting has been widely used in hard rock underground mines for its many advantages. In this paper, the applicability of roof bolts to mine openings in frozen ground and effects of bolts on the stability of the openings are presented. A comprehensive finite element program ABAQUS, was used to analyze the temperature distribution, the stress field, and the displacement field around a mine opening. Openings supported by roof bolts and unsupported were analyzed. The thermal and mechanical processes were treated as a quasi-coupled problem, with the thermal analyses being conducted first, followed by the mechanical analyses in each case. For the opening under consideration with a roof area of 15 m2, five to seven roof bolts are appropriate. When the number of bolts are less than five, the displacement within the ground can be improved only locally.

Jan 1, 1995

By M. Hardy, K. Nielsen, M. Ramey

American Soda, LLP has commissioned the first solution mine for recovery of naturally formed sodium bicarbonate (nahcolite) from low-grade deposits using high-pressure, high-temperature injection fluid. This project, known as the Yankee Gulch Project, was commissioned33 years after discovery of the deposit and followed an intensive four-year feasibility study that included a full-scale pilot test. The nahcoliteis co-mingled with oil shale and is impermeable. Solution mining is achieved by a combination of thermo-mechanical cracking and dissolution. Elevated temperatures are required to initiate the thermally induced cracking and to enhance solubility of the nahcolite, which is highly temperature dependent. This paper will provide an overview of the development of the project from discovery, characterization, pilot testing, permitting and commissioning, with emphasis on the solution mining aspects.

Jan 1, 2003

By Reed S. C. Rogers

The most widely used machines for grinding coal to the sizes prescribed for the pulverized coal firing of furnaces, boilers, and kilns are the vertical ball-race, roller-race and roller-bowl types of mills. However, the increased use of coal has led to an increased use of tumbling ball mills for coal grinding. Specifically, air-swept ball mills are now a part of many dry pulverized coal firing systems, offering the advantages over vertical mills of lower maintenance costs and the ability to handle strong or abrasive (high ash) coals. The current use of wet ball mills is to prepare coal-water slurries for direct combustion, although in time they may also find routine application for preparing slurry feed for coal gasifiers. In either application, wet ball mills ofer the advantages that coal grinding and wetting can be accomplished in a single step, and that the mills are readily used with fine wet screens to assure top size control in the slurry product. The simulation of tumbling ball mills with mathematical models has reached a fairly advanced stage, but the concepts have been applied only recently to coal grinding. As this paper will demonstrate, however, significant progress has been made in the use of models in ball mill circuit design for coal grinding. Included is a description of the techniques used for simulation, recommended parameter estimation methods, and demonstrations of process engineering calculations for large scale coal grinding circuits.

Jan 1, 1986

By D. E. Ranta, G. H. Giroux, A. W. Randall, D. A. Barr

Zinc-lead ores of the Pine Point District, Northwest Territories, Canada, are hosted in paleokarst cavities within a Middle Devonian carbonate barrier complex. Of the nearly 100 deposits found, most are irregularly distributed along two main regional stratigraphically controlled trends. The ores, which occur predominantly as open space filling, form deposits most of which average one million tonnes in size with an average grade of 10% combined zinc plus lead. Geological features related to karsting control not only distribution of deposits but also their shape, size and grade. The higher grade ore in these deposits generally occurs in a relatively small core area. Consequently, accuracy of reserve estimation is dependent on drill-hole density and understanding of karst geometry. Several case examples will be reviewed to demonstrate the relationship between shape, size and grade of deposit, geological reserves and drill-hole density, along with a discussion of geological ore reserve estimation methods.

Jan 1, 1992

By Mark R. Bowie

Air-fall tuffs have been altered to zeolite via reaction of volcanic glass with local pore solutions at the six localities discussed in this paper. These are in the southern Basin and Range Province of Arizona and New Mexico, and in the Trans-Pecos and Coastal Plain regions of Texas. Zeolitization occurred in either closed- hydrologic, open-hydrologic, or hydrothermal groundwater systems. The tripping Spring Valley (DSV) chabazite in Arizona and the Buckhorn clinoptilolite in New Mexico originated in a late Cenozoic network of closed-hydrologic, lacustrine basins extending from southeast Arizona into southwest New Mexico. At DSV, two potentially commercial chabazite-rich tuffs are interbedded with lacustine mudstone. The main zeolite tuft contains up to 90 percent chabazite. The upper zeolite tuff averages approximately 67 precent chabazite. At the Buckhorn deposit, two clinoptilolite-rich tuffs are interbedded with lacustrine m udstone in the upper part of the Gila Conglomerate. The lower zeolite tuff contains up to 90 percent clinoptilolite. The upper zeolite tuff contains over 60 percent clinoptilolite. The Casa Piedra clinoptilolite is in the Trans-Pecos region of Texas. It formed during the Tertiary in a closed basin containing a playa lake. The Casa Piedra tuff averages about 60 percent clinoptilolite. Air-fall tuffs of the Cuchillo Negro, New Mexico and Tilden, Texas clinoptilolite deposits were zeolitically altered by either percolating ground waters in open-hydrologic systems or locally by ponded, saline, alkaline solutions. Cuchillo Negro tuffs are Tertiary and average approximately 50 percent clinoptilolite. Clinoptilolite-rich tuffs of Ebcene age have been mined from four quarries at the Tilden deposits. Tufts from the Kuykendall and Buck Martin quarries contain approximately 50 to 60 percent clinoptilolite. Low temperature, SiO2 - rich, hydrothermal solutions altered air-fall tuff to clinoptilolite and chabazite in the Foster Canyon area of the Tertiary Cedar Hills and Seldon Hills volcanic-vent zone in southcentral New Mexico. Poster Canyon tuffs contain up to 60 percent zeolite and average 40 to 50 percent clinoptilolite. The dominant mineral in the zeolite tufts at the six deposits studied is generally microcrystalline and either chabazite or clinoptilolite. Lithic fragments, unaltered volcanic glass, other zeolites, quartz, calcite, opal-CT, cristobalite, feldspar, evaporites, clays, and mafic minerals are also constituents of the tufts.

Jan 1, 1987

By Neal P. Cochran

The United States is faced with increasing demands for electricity, coupled with continuing demands for crude oil and gas. Superimposed on these' national requirements are our national requirements for clean air and elimination of thermal pollution of our rivers. From the coal viewpoint, this situation is complicated still more by the rapid advances in nuclear power. In this paper, I hope to show a way to use our Western coals as a solution to this involved national problem by producing: 1. High quality crude 2. Low cost power 3. Economic byproducts We could expect these products to be made at one site in an integrated plant that would mine (extract) coal, process it, and convert it to electricity. Perhaps the most important attribute of the plant is its reduced water requirement and the elimination of air pollution from the power cycle. Quite logically, such a plant would probably recover valuable byproducts, such as pipeline gas, sulphur, cement, aluminum, and the like. Although the plant projected in this paper is a conceptual one, it is based on work now underway by Government and industry. Prediction of the future is a most hazardous occupation, but plants such as the one projected are based on current knowledge and can be expected to reach commercial operation in the near term future.

Jan 1, 1967

By Alexander Sutulov

It is calculated that since the beginning of last century, which practically coincides with the beginning of the Industrial Revolution, our civilization has consumed around 239.5 million tons of copper (see: Table 1). According to the most pessimistic projections of today, with only a 2.5% annual growth rate in demand, we are bound until the end of this century to consume another 200 million tons of copper in remaining 17 years. A recent study made by US Bureau of Mines (1) indicates that the proven ore reserves of 150 major operating mines and about 120 deposits sufficiently explored for development and feasibility studies accumulate a total mass of 49.3 billion tons of ore, assaying an average of 0.82% Cu and containing around 324 million tons of recoverable copper. Consequently, there is a high grade of probability that the bulk of our future ore supplies, for our demand of, say, next 25 years will cane precisely from these mines. The interesting point in USBM study is that it indicates the recoverable byproduct content of these ores and which is: 118.2 million troy ounces of gold 2277.4 million troy ounces of silver 7.1 million tons of lead 24.7 million tons of zinc 1.3 million tons of nickel 3.1 million tons of molybdenum 765 thousand tons of cobalt, and 720 thousand troy ounces of platinum. This information gives us a relatively reliable profile of our future ores for next 25 years, and thus makes possible evaluation of byproduct credits in our future copper mining and producing activities.

Jan 1, 1983