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By Allen D. Graham

The coal industry in South Africa is briefly outlined. Test- work carried out on bulk samples of coal in the laboratory and used in the design of the Van Dyks Drift washery are described. Factors affecting the selection of equipment and the designed capacity of the plant are discussed. A description of the crushing plant, washery and load out section is given together with performance data obtained in the final acceptance tests. New features incorporated in the Van Dyks Drift plant and in more recent plants of the Group are outlined.

Jan 1, 1982

By K. R. Griffin, K. D. Luxbacher, E. C. Jong

The schlieren technique describes an optical analysis method designed to enhance light distortions caused by air movement. The ability to visualize air flow has significant implications for analyzing underground mine ventilation systems, including the enhancement of surveys and models. Currently, traditional schlieren methods are impractical underground. Background-oriented schlieren (BOS) provides a solution to this problem. BOS requires two primary components, a professional quality digital camera and a schlieren background. A schlieren background is composed of a varying contrast repetitive pattern, such as black and white stripes. This background allows the camera’s sensor to capture minor light diffractions, such as those caused by air flow. Although BOS shows great potential for ventilation analysis, sensitivity is an issue. This paper seeks to validate the BOS technique for imaging flow through a regulator by comparing BOS images with traditional schlieren images. This paper also outlines initial experimental efforts used for the validation.

Jan 1, 2011

By Simon W. Houlding

This paper summarizes recent developments in computer modelling and estimation technology. Significant improvements in computational and modelling efficiencies have advanced technical computing to the stage where, for the first time, it can be realistically applied to short-term mine planning and production control. Real-time interactive grade estimation of complex shapes, volumes and grade distributions, based on immediate turn-around of production sample grades, is now possible. An added benefit is the ability to produce complete geostatistical estimates which include confidence limits. These can be incorporated into the decision making and risk assessment processes of production control. Why the need for new technology? What is wrong with the conventional methods which have sufficed for the last thirty years? The response is manyfold. They suffer from inefficient computational processes and conflicts with geostatistical theory. They are responsible for constricting the flow of information between the disciplines involved in the mine production process. Finally, it is illogical to approximate irregular geological and mining volumes with orthogonal sets of rectangular blocks. Geological materials do not occur in block formation; and mining methods which excavate rectangular blocks have yet to be developed. Other computer based technologies have evolved out of the dark ages of rectangular approximations and have successfully dealt with irregular three-dimensional geometries. It is time for computing in the mining industry to follow this example and take full advantage of available technology. To provide the necessary background, consider the basic requirements for successful implementation of technical computing within the mine production process.

Jan 1, 1992

By Paul H. Earl

This paper discusses the evolution of a modeling methodology for explaining price behavior in the aluminum industry. Three generations are described, each utilizing as a foundation a microeconomic stages-of-processing approach. The second generation represents an improvement over the initial version, by incorporating more rigorous specifications of energy cost, and market strength (demand-supply balance) as well as endogenous treatment of market strength. International linkages across prices, costs, and markets, are the major extensions in the third generation. The discussion covers theoretical considerations, data problems and limitations, and model specifications. Simulation and forecasting properties of the models are also addressed.

Jan 1, 1979

By G. D. Hood

The U.S. Bureau of Mines investigated rapid froth flotation through the use of more efficient bubble-particle collisions that improved the overall flotation kinetics. An in-line static mixer efficiently mixed the air bubbles, water, and ore, rapidly attaching the hydrophobic mineral to the bubble surface. As the mixture entered the flotation chamber, the hydrophobic mineral was already attached to the bubbles and was quickly floated away from the remaining ore pulp. A rougher concentrate containing 4.5 pct copper was obtained from a western porphyry copper ore containing 0.67 pct copper. Over 99 pct copper was recovered from the ore at a rate 7 times faster than conventional flotation.

Jan 1, 1991

By S. B. Castor

Proceeds from industrial mineral mining in Nevada were approximately equal to those from metal mining during the barite boom in the late 1970s and early 1980s; however, since then the economic importance of industrial minerals has been overshadowed by gold mining (Fig. 1). The total value of industrial minerals mined in Nevada increased by about 60% during the 1980s, reaching an estimated $306 million in 1990 before falling slightly in 1991. The state's most important industrial mineral commodities, in order of estimated value, are aggregate, lithium carbonate, diatomite, lime, cement, gypsum, barite, clay, silica, and magnesia (Fig. 2). Industrial minerals produced on a smaller scale are colemanite, dimension stone, dolomite, perlite, salt, and zeolite. In 1991 industrial mineral commodities other than aggregate were produced at 39 operations in Nevada. Most of these operations are located near the two major metropolitan areas of the state, or along the major transportation routes (Fig. 3).

Jan 1, 1993

By E. J. Rorem

Rockfall and unstable rock slopes can be con-trolled by using steel wire-rope net systems as barriers or as slope draping. The chief advantage of such systems over rigid type barriers is the flexibility of wire rope netting. This flexibility and strength permits kinetic energy dissipation with low maintenance requirements. Mining activities can produce temporary or long-term unnatural slopes and unstable rock faces that may produce rockfall hazards. Such conditions can necessitate efforts to minimize the hazard to workers, structures and equipment.

Jan 1, 1996

By J. Alderman

In modern industry, cost and productivity concerns and environmental concerns are sometimes incompatible, but at other times only appear to be incompatible. Surface disposal of wastes from coal preparation plants appears to be an area of the production system with little opportunity for initiating measures which cut costs and concurrently benefit the environment. However, improving the recovery efficiency of fine coal circuitry can cost-effectively reduce the plant waste environmental burden by a substantial amount. Studies at Jim Walter Resources indicate that fine-coal waste measuring 50% ash contains over 50% recoverable, marketable coal. Modifications to the plant circuitry which reduce the amount of misplaced coal in the fine-coal waste stream could substantially reduce the volume of fine waste disposed aboveground. Studies at Jim Walter Resources indicated that episodic overloads of the vacuum filters in the fine-coal circuits at the preparation plants were a source of misplaced coal in the fine-waste stream of the cleaning plants. To improve the filtration rate and reduce overload episodes, conventional rotary blowers were replaced with high pressure air blasters on most of the filters. Subsequent testing indicated that measurable benefits can be derived from this modification.

Jan 1, 1990

By A. D. Pernichele

Four types of slope failures in waste dumps are recognized; debris flow, foundation failure, edge slump and blowout. The first three types, although at times causing considerable damage to property and interfering with mine operations, are not usually dangerous to personnel because of their slow rate of movement. The fourth type, the blowout, is considered to be the most dangerous because of its explosive mode of failure and lack of forewarning. The December failure at Verona dump is presented as an example of a blowout. Data from piezometer holes indicate that the blowout was due to perched leach solutions near the face of the dump. The level of water in this zone is very closely related to the rate of leach water application on the dump. A detailed analysis of core samples indicated that the impounded water was due to a zonal accumulation of Jarosite which is associated with a buried dump surface. Drain holes proved successful in controlling perched leach solutions in the critical zone near the face of the dump. Monitoring of the water level in the perched zone is considered essential in preventing blowouts. The use of drain and piezometer holes has allowed an increase in the rate of water application on the dump while preventing additional failure.

Jan 1, 1971

By W. C. Baver

Even before the energy crisis developed in the early '70's, considerable research world-wide was being directed towards the development of schemes to both reduce the energy requirements and to reduce air pollution emissions associated with the manufacture of glass. In many cases the sought-for solutions would benefit both objectives. If, for example, the glass batch could be consolidated into such compact forms as briquettes or pellets, they could be preheated in a moving-bed heat exchanger with the high-temperature exhaust gases from the glass furnace. Lower furnace temperatures would thus be possible with a corresponding reduction in heat losses and total fuel consumption. Moreover, the lower temperatures would also reduce the amount of nitrogen oxides generated in the furnace and emitted to the atmosphere. Many tests on consolidated glass batch have been run in many countries. In some cases, extended tests on production furnaces have also been included in the programs. For various reasons, however, none of these has proved to be economically attractive. The current, but temporary lull in the rapidly rising cost of energy which has been with us in recent years, has reduced the push for research for energy saving means for melting glass. A few of the current programs will be discussed. Since raw material requirements, primarily physical in nature, are affected by some of these schemes, these will also be considered.

Jan 1, 1986

By Manuel R. Lastra

Critical to successful dump and heap leaching for gold, silver, copper and uranium are factors such as permeability, solution delivery to the ore, and solution recovery. This paper deals with possible techniques for successful accomplishment of these three factors. New developments as well as older techniques are discussed, together with rationale for use of some techniques in reference to others. The authors hope to present a checklist so that the ideal application to individual mine situations can be achieved. This involves a discussion of the merits of each different method and the situations for most logical application. It is hoped that such discussion will broaden the geographic areas where dump and heap leaching can be applied to include greater winter cold and tropical regions of large amounts of rainfall.

Jan 1, 1984

By W. Miola

The MSHA prescribed method for the determination of quartz in airborne respirable dust samples from underground coal mines is the P-7 method, a combination of low temperature radio-frequency ashing (LTA) and infrared analysis (lR). There is no prescribed procedure for quartz analysis in bulk samples of coal and host rock. Dispersive Infrared (IR), Fourier-transform Infrared (FTIR), and X-Ray Diffraction (XRD) methods are most commonly used for quartz analysis in powders. Several aspects of the experimental procedures such as the analysis sample preparation from bulk samples, ashing techniques, scanning procedures, peak measurement location, calibration techniques, sample amounts, size consist, and data interpretation affect differently the results from each of the methods. Significant differences in analysis results from X-ray diffraction (XRD) and infrared spectroscopy (IR) on the same samples are reported. All these studies point to the need for reliable quartz analysis methods. In a recent research, a procedure for preparing bulk coal and host rock samples for quantitative quartz analysis was developed. Further the results from X-ray diffractometry and infrared spectroscopy for quartz content on identical samples were compared. Calibrations with pure and mixed standards were used to assess the influence of particle size distribution, matrix, and calibration on analysis results. In this paper, several issues with the measurement of quartz in the samples of coal, host rock, and airborne respirable dust from mines are outlined and quantified.

Jan 1, 1994

By C. Rutter, N. SHEA, K. KOLOBE

Henderson Mine’s primary production transitioned from the main portion of the 7700 level to the 7210 main panel in 2005. On the 7700 level, the southwest (SW) panel was brought into production in 2014 and produced through 2020. A-Panel was brought online in 2019 and took over primary production in 2020. The 7210 north panel is under development with production expected to commence in 2025. The 7700 northwest panel is expected to be the mine’s last production panel.

By James Paone

Subsidence movements have damaged houses, schools, streets, and public utility lines in some undermined sections of Belleville and Maryville, Ill. In cooperation with local officials and the State of Illinois, the Interior Department's Bureau of Mines is sharing experience in backfilling abandoned coal mines to demonstrate that bituminous coal mine workings in south-western Illinois can be successfully backfilled and subsidence-prone areas stabilized. Subsurface investigations revealed that mine workings are dry and underlain by underclay deposits susceptible to instability upon wetting. Backfilling will therefore be accomplished by pneumatic injection instead of the hydraulic methods used in previous subsidence-control projects.

Jan 1, 1977

By R. L. Stone

By means of laboratory balling tests and a procedure for determining bentonite concentration in a green ball the present study revealed that the bentonite savings by mulling concentrate and bentonite prior to balling was sufficient to warrant installation of a full-size unit in a pellet plant. On the basis of this work, a muller was put on stream at Bethlehem Steel Corporation's Cornwall pellet plant in June 1969, and has operated continuously since then. Plant tests showed that the use of the muller resulted in bentonite savings of about -502 without any loss of green, dry, and fired ball quality. Virtually no maintenance problems have been encountered. This information is important to future pelletizing operations both from the standpoint of product quality and economics.

Jan 1, 1971

By Richard Louis Viner, William D. Leech, Walter A. Mergelsberg

With the construction management team established and a full funding agreement secured the Washington Metropolitan Area Transit Authority (WMATA) now has the manpower and the financial resources to continue Metrorail construction into the 1990's. This paper describes WMATA's new role as construction manager after the transition from Bechtel Associates and gaining the full funding agreement with the Urban Mass Transit Administration (UMTA) and regional governments to complete 84.7 Metrorail miles (136km). The authors review the most recent station and line tunneling projects. WMATA's contractors have employed the state of the art soft ground and hard rock tunneling equipment and methods - an earth pressure balance TBM, a closed face TBM, and the New Austrian Tunneling Method (NATM). In final, the paper previews future underground work to be let under the funding agreement.

Jan 1, 1987

By G. V. Sullivan

The Federal Bureau of Mines examined tailings samples from 13 western copper operations to determine the potential for recovering rutile. Results showed that six of the samples contained sufficient liberated titania to be considered potential sources. One sample contained 0.75 percent Ti02 or 0.40 percent liberated rutile. Batch flotation studies developed a procedure that recovered 70 percent of the liberated rutile at a grade of 34.7 percent TiO2. Sulfuric acid leaching studies on 12 of the samples dissolved 100 to 2,200 grams Cu per ton of tailings; leaching of the slimes showed slightly more copper was dissolved, 1,800 to 3,300 grams Cu per ton of minus lo-micrometer material. Bulk sulfide flotation of nine of the samples resulted in concentrates that contained 0.38 to 2.0 percent Cu and 0.7 to 2.1 and 6.9 to 42.9 grams per ton Au and Ag, respectively.

Jan 1, 1981

By W. H. Strickland

The research reported here characterizes ultrasonic ranging sensors for autonomous navigation on underground mine mobile equipment. Because ultrasonic rangers are inexpensive, have no moving parts, have no lenses to clean, are small and unobtrusive, and can measure distances in dusty environments, they are especially sui ted to underground mi ne environments. The investigation began with laboratory tests of field of view, angle of incidence, intersensor variation, and ranging accuracy of individual rangers and a ring array of 24 sensors. The results showed the sensors have good accuracy and low variability. Additional experiments at AHAX' s Henderson mine Showed the sensors could accurately and reliably measure rib features, convex and concave corners, and drift intersections. The results showed that when used and analyzed properly, the sensor data may be used reliably for underground mobile equipment navigation.

Jan 1, 1990

The dissolution behavior of gold and silver from Au/Ag alloys in aerated cyanide solutions has been investigated using rotating disc electrodes. The variables studied included concentration of cyanide, oxygen partial pressure and rotating speed of the disc. The dissolution potential and the rate of dissolution were obtained in view of the anodic and cathodic current-potential relationships. The results were discussed in terms of a mixed potential theory. The results showed that the dissolution rate of gold and silver from the alloys was partially controlled by chemical reaction, but largely by transport of either oxygen or cyanide, depending on their relative concentration under the experimental conditions employed in this study.

Jan 1, 1995

By A. House

Newmont Mining Corporation owns and operates the Phoenix Mine near Battle Mountain, Nevada, USA. The existing milling facility has operated since 2006. Following the startup of the milling operation, and coupled with the upswing in the copper market, Newmont realized that Phoenix needed a process option to treat lowgrade transition and oxide copper ores. This meant that potentially revenue generating ore was being mined as waste. With no system in place to treat the transition and oxide copper, work began to determine the most feasible approach. After evaluating multiple options, the flow sheet was set for a run-of-mine (ROM) heap leach pad and solvent extraction/electrowinning plant (L-SX/EW). This paper will discuss the synergies and challenges of developing a copper L-SX/EW plant at the Phoenix copper-gold mill.

Jan 1, 2010