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By Donna L. Boreck

In an effort to increase recovery in thick and closely spaced coal seams, the Bureau of Hines, U.S. Department of the Interior, is studying the feasibility of introducing three mining methods-high-face longwall, multi-slice longwall, and longwall caving-in western coal operations. Geology plays a significant role in determining the success of such methods. Some of the factors that will affect development are as follows: (1) thickness and three-dimensional configuration of the seam, (2) cleats, joints, and fractures in the coal and roof rock, (3) roof composition and variability, and (4) coal quality and changes in quality within the seam. Through geologic mapping, the presence of many of these factors is predictable prior to development.

Jan 1, 1987

By Lawrence D. Ramspott

A test of retrievable geologic storage of spent fuel assemblies from an operating commercial nuclear reactor is underway at the Nevada Test Site (NTS) of the U.S. Department of Energy his generic test is located 420 m below the surface in the Climax granitic stock. Eleven canisters of spent fuel approximately 2.5 years out of reactor core (about 1.6 kW/canister thermal output) were emplaced in a storage drift along with 6 electrical simulator canisters. Two adjacent drifts contain electrical heaters, which are operated to simulate within the test array the thermal field of a large repository. Fuel was loaded during April-May 1980 and initial results of the test will be presented.

Jan 1, 1981

By James Thompson

Mine planning at Consolidation Coal Company's (Consol) Glenharold Mine in North Dakota is being constrained by environ¬mental concerns that did not exist when the mine opened in 1965. One such concern which developed in the mid-1970's is the impact of mining on woodlands that are considered impor¬tant wildlife habitat. To better coordinate mine planning with permitting, a cooperative task force was created to evaluate woodlands for their wild¬life habitat potential. The task force included representatives from Consol and state and federal agencies. This cooperative process is seen as a method of communication between industry and government and as a way of developing decision-making tools for mine planners and regulatory agencies.

Jan 1, 1981

By Byron M. Jones

The use of computers in system analysis is well established. Analog computers have been used for this purpose since about 1940. As the power of digital computers increased and their cost decreased, much of the analysis formerly done by analog computers has been diverted to digital computers. The mathematical foundation for system analysis was laid between the years 1700 and 1900. In the 1930?s, telephone repeater amplifiers were designed using systems analysis techniques. From 1940 to 1960 systems were analyzed using either direct simulation or LaPlace transforms. Since 1960 analytical methods have been expanded to include linear vector space theory. All of these methods are being used to analyze the dynamic behavior of mining machinery.

Jan 1, 1974

By R. J. Lutton

The U. S. Army Corps of Engineers is seeking empirical slope data from mining companies and other organizations to help establish guides for engineering Judgment in crater excavation for canals and other civil works. Slopes from about 100 open pits and other excavations range in heights to greater than 1000 ft. Factors known or expected to affect stability (and optimum slope inclination) are: geological structural orientation, geological structural ordering, method and technique of blasting, design life of slope, groundwater conditions, depth of excavation, climate, and height. These and other more subtle factors appear to combine and produce an overall effect brought out best on a family of empirical curves relating slope height and inclination.

Jan 1, 1968

By R. L. Wooten

When discussing what Coal Mine Safety in the future will be, it is important to examine three areas which at present provide significant parameters to the industry. These three areas are: 1) Safety improvements in mining equipment; 2) Labor-management relations; and, 3) The politics of coal mine safety. EQUIPMENT Over the past several decades significant safety improvements have been made in the types of equipment now in use in most operations. Many of these improvements have evolved through mandates from either the U. S. Bureau of Nines, MESA, MSHA; and in some instances, the states. Cabs and canopies are examples of federal mandates while the use of ATRS initially was a state mandate.

Jan 1, 1985

By John Todhunter

Longwall mining is certainly not new in the United States, having first been used in the late 1800's in Illinois, but the surging acceptance of the method is relatively new. The number of longwall installations in this country are nearly doubling annually as this method continues to prove itself as a coal producer's delight terms of operating cost, performance and safety. Since 1951, several longwall installations have been tried in Barnes and Tucker Company operations. Although all efforts actually proved that the system itself could be used in prevailing conditions, it was not until 1967 that a unit was put in use that proved competitive with regular mining equipment, both conventional and Continuous.

Jan 1, 1968

By D. R. Nagaraj

There are few organic ligands that can adsorb effectively on noble metals, especially gold, in aqueous media. Ligands containing sulfur and nitrogen donors are known to be the most effective. Dithiophosphorous acids, for example, are known to adsorb on gold under certain conditions and these, along with xanthates, are used traditionally to recover gold values by flotation from ores. These compounds, however, are not necessarily selective for gold since most of the associated sulfide minerals are also floated. Monothiophosphorous acids, on the other hand, were recently discovered to float gold values selectively from sulfide-containing ores in a mildly alkaline medium; thus the dicresyl monothiophosphate is now used commercially in a gold flotation operation in the U.S.

Jan 1, 1991

By J. R. Beeder

Minerals Engineering Company (MECO) is a relatively small, promotionally oriented mineral exploration company founded in Colorado in 1948 during the height of the uranium boom. The company has been: 1. in uranium exploration and production 2. a drilling company 3. a manufacturer of Geiger counters 4. a major tungsten producer 5. then dormat for several years and 6. now we are back into exploration on a broad scale. We have been in underground lead and zinc production in the 1970's but we are now involved primarily in "wheeling and dealing" in mineral exploration. The company has had diverse interests in the past and we are presently diversifying to some extent into oil and gas ventures.

Jan 1, 1979

By Richard P. Killmeyer

In 1985 the Pittsburgh Energy Technology Center (PETC) of the U.S. Department of Energy (DOE) conducted a study to evaluate the emerging selective agglomeration processes (Killmeyer, 1985). This paper covers a recent similar study evaluating an associated technology, the emerging advanced froth flotation processes. This study has goals similar to those of the 1985 study: to evaluate the emerging froth flotation technologies collectively and determine how far they have progressed in their ability to clean ultrafine coal, and to assess the differences among the participants. The major concern again in this study was not the level of development, nor the economics of each individual process but only the current technical performance.

Jan 1, 1989

By C. D. Harrison

The 1990 Clean Air Act Amendments specify national objectives for reducing sulfur dioxide emissions from coal-fired power plants System-wide reductions can be achieved by combining various emissions controls technologies and allowances, or compliance credits, that can be purchased, sold, or traded. As part of the Coal Quality Expert development project funded by U.S. Department of Energy and the Electric Power Research Institute (EPRI), Black & Veatch has developed an interactive computer tool, the Acid Rain Advisor (ARA). ARA allows the user to develop integrated system-wide compliance plans by comparing the costs and emissions reduction benefits for emissions allowances and various SO2 control technologies such as coal cleaning, fuel switching, and scrubber retrofits.

Jan 1, 1992

By E. J. Berentsen, R. F. Nanna, D. Dell’ Elce, R. Lougheed

Apollo Gold’s Black Fox project is located 10 km (6.2 miles) east of Matheson, Ontario, Canada, on Hwy 101 East It is located within the prolific Destor Porcupine Fault Zone, which is also the host for the Dome and Hollmger mines to the west and the Holt and Holloway mines to the east. The local host rocks are intensely deformed and carbonized ultramafic volcanics, pillow basalts, syenitic felsic intrusives and argillaceous sediments. Gold occurs with pyrite and as spectacular specimens in native form. Past production accounted for a total of 195,337 oz (6,075,606 g) of gold. Apollo Gold Exploration, Inc. is conducting an intense drilling program aimed at expanding the reserve base.

Jan 1, 2004

By Thomas F. Pedersen, J. Jay McNee, Alan J. Martin

Field sampling was conducted in Lake Junin, Peru in order to assess the post-depositional reactivity of the highly contaminated lake sediments. High resolution profiles of dissolved Fe, Mn, SO42- and H2S across the sediment-water interface illustrate that the organic-rich sediments in the main basin become anoxic within several millimetres of the sediment-water interface. These permanently submerged deposits in the main basin serve as a diffusive sink for dissolved Zn and Cu. Conversely, the periodically unsaturated deposits in shallow areas are characterized by the remobilization of Zn and Cu in the deep acidic (pH < 4) pore waters, resulting in the release of these metals to the overlying water column.

Jan 1, 2000

By Robert J. Watters, Peter C. Kelsall, Joseph G. Franzone

Two separate studies investigated the compressive strength of basic igneous rocks and its relation to index properties such as porosity, density and soundrave velocity. The rocks tested were weathered dolerite from S. W. England and vesicular lavas from California. In both cases strength was affected considerably by porosity. In the dolerite, strength was also affected by fissures (microcracks) which were formed in the parent rock by shearing and later accentuated by weathering. While test results show that porosity, density and sound velocity are not reliable indices of rock strength, these properties are useful in interpretation of strength test results. Index testing can be used to classify samples according to similar behavior and to recognize the influence of fissures.

Jan 1, 1986

By Chun K. Ip, Simon T. Johnson, Robert J. Fowell

Laboratory conducted cutting tests at traverse speeds up to 1 m/s have been undertaken with high pressure water jets assisting the cutting action of drag tools. Four sandstones and one limestone have been investigated, which represents a wide range of compressive strength. Variables investigated include water jet pressure, nozzle diameter, depth of cut, traverse speed, jet position, and tool bluntness. The test programme has allowed a model to be developed which describes the action of water jet assistance for three conditions dependent on the ability of the jet to penetrate the rock: where no significant penetration occurs, where penetration is greater than 50% of the tool depth, and an optimum condition around 30% of tool depth.

Jan 1, 1986

By Ulf Marklund, Stig Markstrom

Pioneering work with pilot scale autogenous grinding started in Boliden 1956. From 1961 to 1991 eleven fully autogenous grinding (AG) circuits have been installed at various concentrators within the Boliden company. A compact two-stage grinding system was de- signed in the beginning of 1970s. The system included a pebble extractor which feed the secondary grinding stage with grinding media. The APC grinding system (Autogenous/Pebble/Crusher) is a further development of the AG concept. A new design of the Boliden pebble extractor together with improved control strategy make the performance of the APC system suitable to almost any ore quality. The Boliden AG concept is probably the most cost efficient grinding system of today.

Jan 1, 1998

By J. A. Brierley, Arpad E. Torma, Victor C. Storhok, C. L. Brierley, Batric Pesic

Chemical and electrochemical studies were performed during bioleaching of cobaltite concentrate with Thiobacillus ferrooxidans. The two principal minerals present in the concentrate were pyrite and cobaltite (CoAsS). During chemical studies, the effect of pH on dissolution rates was examined under uncontrolled and pH-controlled conditions. It was found that in the pH range 1.5-3.0 there was no pH effect if the initial pH was not controlled (maintained). When the initial pH was controlled, the leaching of Co, As, and Fe depended strongly on pH. Electrochemical studies were performed by using cyclic voltammetry and constant potential techniques. A sequential reaction mechanism was proposed for dissolution of cobaltite.

Jan 1, 1993

By Vaughn Astley, Hassan El-Shall, Ponisseril Somasundaran, Regis Stana, Patrick Zhang

In the past, when phosphate rock quality was good, few paid attention to any of the impurities or other qualities associated with phosphate rock. In general, they had little or no effect on the ability to make the phosphate products for the market. However, as phosphate rock quality declined, it was apparent to the rock consumers that the individual impurities had a significant impact on their processes. FIPR is presently funding an analysis of operating plant data to determine the range of the effects of rock impurities on production plant performance. The study will not be completed until 2002. IMC has agreed to share some of the information they had developed in the early 1990s.

Jan 1, 2002

By H. Y. Sohn, M. Pérez-Tello, J. Löttiger

An investigation of the oxidation reactions of two industrial copper mattes was performed using dflerential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) at heating rates of 20°C and 8°C/min, respectively. The temperature of incipient reaction, the total exothermic and endothermic heats of reaction and the weight change during the oxidation process were measured as functions of the oxygen concentration in the oxidizing gas, matte grade and matte particle size. The temperatures of incipient reaction measured from the DSC experiments were found to increase monotonically with all three input variables. TGA experiments showed that Cu2O and CuO CuSO4 are formed before the complete oxidation of Cu2S to CuO.

Jan 1, 2000

By D. W. Horsfall

The different types of processes used in fine coal beneficiation in the Republic of South Africa are listed, together with data giving an indication of their separating efficiencies The two classes of coal, fines and ultra-fines, present in the -0,s m fraction of the run of mine coal are discussed, with special reference to their beneficiation characteristics. Using those properties, together with the data on plant efficiency, case studies are worked out to indicate the advantages and disadvantages of the different processing routes available. The paper closes with an indication of areas where research is required to enable some of the processes to be applied to a greater extent than is presently the case.

Jan 1, 1988