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By W. M. Hart

The current Automatic Data Acquisition system developed by some support manufacturers makes it possible to continuously monitor and record changes in leg pressure and advancing ram stroke in every shield, and shearer position at any moment during the mining operation. In order to effectively use the massive data obtained from this system for improving production and maintenance managements as well as providing better roof control at a longwall face, the research currently conducted jointly by West Virginia University and Cyprus-Amax Coal Co. attempts to develop a Longwall Management System for mine operators. The LMS software package runs on a MS Windows NT environment and consists of four sub-systems: (1) Data Interpretation and Analysis; (2) Production Management; (3) Maintenance Management; and (4) Ground Control. This paper presents the details of each sub-system.

Jan 1, 1995

By Robert W. Miller, Rhoda S. Kriesel

INTRODUCTION With each passing year, the general public becomes increasingly aware of the potential hazards associated with many products and services previously considered unharmful. This new consciousness is especially evident in the workplace, both as the result of advances in scientific understanding and the influx of concerned, responsible professionals into the labor movement. For example, data produced by epidemiologists doing retrospective mortality studies which related mortality to toxic substance exposures has often been the prime motivating factor behind reductions in exposure standards. This certainly has been the historical case with many radiation exposure standards, including the limitations set for "Working Level" exposure. The concept of "Working Level" was introduced in PHS Publication No. 494 as a result of both the difficulty in relating radiation units to biological effects and the complexity of interaction of radon daughters with the physical environment. WORKING LEVEL One working level is defined as any combination of radon daughters in one liter of air that will alternately release 1.7 x 105 MEV of alpha energy during decay of 210pb (RaD). Its usefulness is that working level can be readily measured in both the field and the laboratory. Because of this, existing occupational exposure standards for radon daughters in both the U. S. and other countries use working level as their basis. In the U. S., the last twenty years has witnessed a significant reduction in radiation exposure standards from 120 working level months to 4 working level months per year. New international standards are being proposed that would be only slightly higher than these current U. S. standards. POTENTIAL EXPOSURES TO RADON DAUGHTERS The universal use of nuclear power, along with the transfer of nuclear technology to developing nations, has significantly increased the demand for fuels. As a result, uranium mining operations have expanded and increased numbers of miners are regularly exposed to radon daughters. In addition to potential exposures in uranium mines, other deep mines such as tin, gold, platinum and tungsten, also have potential exposures due to the distribution of uranium and its accompanying radium throughout much of the earth's crust. The energy crisis has also prompted interest in general population exposure to radon daughters in buildings. Many homeowners, using additional insulation and caulking to seal cracks and conserve energy, have reduced indoor ventilation to the point where working level exposure could become significant, especially in homes with unventilated crawl spaces. In fact, several serious exposure situations have occurred where mine tailings were used for building materials. MEASUREMENT TECHNIQUES Historically, rapid and convenient measurement techniques have been actively sought to improve the ability of ventilation engineers to limit mining exposures through ventilation control. A number of measurement techniques have been developed, including the Kusnetz method (further elaborated by Shalaynev) and techniques developed by Rolle and Tsivoglou. All, however, suffer from similar handicaps that prevent their usefulness in the mining environment. Their main limitation, in terms of minimizing employee exposure, is the elapsed time from the start of sampling until the results can be calculated. It is usually 40 to 90 minutes. This time delay presents both serious economic limitations as well as the potential for exposing workers to high radon daughter concentrations until calculations are completed and corrections made. Further reducing the utility of the Kusnetz and Tsivoglou techniques is the need for tedious calculations that increase the possibility of human error along with the need for cumbersome sampling equipment that is not ideally suited to the mining environment. INSTANT WORKING LEVEL METER To alleviate these problems, the idea of an Instant Working Level Meter was conceived by several groups. Several such instruments were proposed, built, and tested with disappointing results. Although the concepts behind them were sound, the instruments simply failed to measure working level without excessive distortion. In addition, their cost was relatively high, gamma background presented a problem, and sophisticated computations were necessary to determine working level. In short, these systems lacked the design engineering that would make them suitable for the demands of a mining environment.

Jan 1, 1981

By M. K. Larson

Proper employment of numerical stress analysis design tools is based on the demonstrated ability of a model to capture key elements of the geologic site model and accurately simulate how these elements interact with a mine design. While these tools have progressed markedly, they are, at heart, a gross simplification of the abundant complexity of a natural setting and its response to mining. A generic deep longwall site model was developed that includes aspects of the geology of deep coal mines in the Wasatch Plateau and Book Cliffs coal fields of Utah. The site model contains a set of common features and observations of how these features typically respond to mining. This site model was the basis for evaluating use of empirical, boundary element and volume element stress analysis tools to analyze the distribution of stress around a deep longwall panel. More specifically, this evaluation examined shifting of stress to panel abutments and gob, distribution of stress in the abutment, and deformation and failure of bridging strata. Measurements of abutment stress changes at two sites in the Wasatch Plateau region were used to illustrate model calibration. Overall, these comparisons highlight the considerable differences between methods. Volume element tools can incorporate considerable detail and have fewer underlying assumptions, but this detail carries a considerable computational cost. Boundary element tools are much more efficient. But this efficiency also comes at a cost of added assumptions. These assumptions were challenged by the presence of a strong sandstone unit in the overburden, leading to boundary element results that depart significantly from volume element results. Empirical rules are the simplest, but are even more burdened by assumptions, many of which are implicit in underlying cases. Insight into the nature and impacts of underlying assumptions in each method is essential to proper use of results in mine design. Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health

Jan 1, 2009

By Thomas J. Wright

The evaluation and development of the Eastern North Carolina phosphate deposit resulted in one of the world's largest and most modern phosphate mines and fertilizer complexes at an investment in excess of $90,000,000. The resulting ore beneficiation process showed excellent correlation with pilot plant data. A number of variations from current industrial practices were introduced and projected from bench scale tests through pilot plant to production. Principal among these variations were the following: 1) removal of magnesium by classification, 2) simultaneous flotation of coarse and fine phosphate, 3) the use of saponified fatty acid, 4) utilization of filter wash water for deoiling, 5) utilization of a rougher concentrate for acidulation, 6) calcination of flotation concentrates, and 7) elimination of grinding prior to the manufacture of phosphoric acid.

Jan 1, 1971

By L. G. Martin

Early mining at Manhattan demonstrated that blasthole assays alone were insufficient to control the disposition of material. A program was began using controlled blasting, intense sampling and panning of crushed samples, fire assay checks, and geologic inspections to sort material in the pits. Statistical data confirms that the method provides effective control at minimal cost. This cost is easily offset by additional tonnage found in areas considered to be waste.

Jan 1, 1980

By R. J. Roman

During the refining of primary magnesium metal: a spent flux (sludge) is produced which is considered a dangerous waste by the Washington State Department of Ecology. Four years of research, testing and marketing has identified two beneficial markets for the spent flux: 1) as a fertilizer and soil admendment as a result of the material's high potash and nitrogen content and its high lime equivalence and 2), as a roadway deicing agent to clear roads of ice and snow as a result of both the salt content and the flux containing chemical compounds which exothermically react with water.

Jan 1, 1988

By D. T. Iseley, A. L. Atta-alla

INTRODUCTION The extension project of the East Line Subway of Atlanta's subway network includes the construction of two single track transit tunnels under Interstate Highway 285. The project will be in DeKalb County, Georgia. The length, width, and height of each tunnel are 54.25, 6.3, and 7.2 m (178, 21, and 23 ft) respectively. The ground cover above the tunnel crown ranges from 1.5 to 3.25 m (5 to 11 ft). A soil pillar about 5.5 m (18 ft) wide will remain between the tunnels. The construction of each tunnel includes (i) installation of 21 steel soil support pipes of 75 cm (30 in) diameter, (ii) jet grouting 15 soil cement shafts of 60 cm (24 in) diameter in the soil under the pipes, (iii) contact grouting behind the tunnel lining and between soil support pipes and pavement, (iv) excavation of soil inside the soil support arch, and (v) installation of steel pile foundation, steel sets, and permanent tunnel lining of cast-in-place concrete, all as shown on the cross section in Fig. 1. The soil profile can be described from top to bottom as cement/asphalt concrete pavement, a fill layer consisting mostly of stiff sandy silt/firm silty sand, a residual soil layer consisting mostly of silty sand/sandy silt, partially weathered rock, and solid rock.

Jan 1, 1991

In this paper, we present design and implementation details of a fuzzy-behavior-based controller for an automated excavator. This robotic excavator must be equipped with sensors, actuators and an embedded control system. The excavator controller uses neural-networks to interpret forces and torques gathered from bucket mounted force sensors during the excavation process. Implementation details and experimental results using the fuzzy behavior based excavation controller are given for several excavation tasks. These excavation tasks demonstrate some of the complex skills that are essential for an autonomous mining excavator controller.

Jan 1, 1996

By Quan Li, Xiang Ren, De Lui, Yumin Zhang

SL-type continuous centrifugal separator with injection flow (Injection Flowing Film Centrifugation, IFFC) for separating fine and ultra-fine minerals has been developed recently in China and it is capable of recovering particles down to one micron in size. In this paper, the principle of its separation is discussed. IFFC is a special transient pulsating film which combines both thin film jigging and thin film concentration functions. It not only can intensify the looseness and stratification of the settled particles, but also create a hydraulic weir effect to improve recovery of fines and ultra- fines and significantly improve the performance of thin film separation. In a Chinese tin gravity concentrator, SL devices, SL-1200s (capacity 1.5-2.0 ton/hr) and SL-600s (capacity 0.5 ton/hr) were applied to treat -1 0 micron cassiterite slime(removed as tailings at the past) and to replace the old tin flotation system(-74+10 micron slime). The plant results show that 50-60% of the cassiterite can be recovered from -10 micron slime with an enrichment ratio of 10-12. Particle down to one micron were recovered. Under optimal conditions, the recovery from -74+10 micron slime can reach more than 85%. The recoverable size range can be determined by calculation.

Jan 1, 1995

By John A. Herbst, William T. Pate

Column flotation is emerging as one of the most important new separation technologies of the decade. Attendant to this development is the need for a quantitative understanding of the dynamic characteristics of columns. An understanding of the many important sub-processes occurring in the cell makes possible the development of dynamic simulators for flotation columns which will aid in the design of control systems for dynamic and steady state optimization. This paper presents a dynamic model for the column flotation cell developed from a population balance point of view similar to that which has been successfully applied to conventional flotation cells. In particular, the mixing that occurs within the pulp is modeled with a distributed-volume, mixer-in-series model as an approximation to the axially dispersed plug flow transport that occurs in the cell. This simpler approach avoids the distributed transport model which often leads to mathematical intractability. Other phenomena dealt with are the attachment and detachment of particles from bubbles in the froth and pulp, the transport of water and the bubble volumes with the froth and pulp phases. Simulation of the flotation of an Illinois No. 6 coal in a pilot plant flotation column were performed to test control strategies.

Jan 1, 1989

By Robert Snow, Yingxue Yu, Howard Hanson, Patrick Zhang

One of the major current efforts by the Florida phosphate industry to reduce deep aquifer water consumption is to use 100% recycle water for flotation. This measure alone could save billions of gallons of deep well water annually. However, this also results in higher suspended solids (slimes) in flotation water, causing poor process performance particularly for amine flotation. Polymers could play a major role in allowing the industry to use high-turbidity recycle water for amine flotation without compromising its impact on the Florida economy. The enhancement of rougher flotation by polymers may also have potential. Most importantly, dramatic efficiency improvement may be realized by floating silica first. Adding polymer to flotation feed and/or water is perhaps the most economically viable way of reversing the Crago "double float" process, in order to reduce operating costs and increase phosphate recovery. This paper presents both laboratory and pilot flotation data showing the effect of different polymers on collector dosage and flotation recovery. There appeared to be an optimal range of polymer concentration beyond which the benefits do not offset the drop in phosphate recovery. The effect of poly mer is slime-level dependent. Pilot testing data show that the "Reverse Crago" process (floating silica first followed by phosphate flotation) can outperform the Crago process.

Jan 1, 1999

By R. R. Bhappu

The metallurgical processing industry is in the midst of a hydrometallurgical revolution with mining companies looking for low cost, energy efficient and environmentally friendly technologies for processing sulfide ores and concentrates. The Intec Copper Process is one of the most advanced of these technologies and has the potential to greatly change the way copper concentrates are treated in the future. Specifically, the Intec process has the ability to be built on a small scale and at mine sites while being much more economic than conventional smelting. Intec Copper has constructed a I tonne of copper per day demonstration plant in Sydney, Australia designed to verify metallurgical and operational performance. This paper will describe the process in more detail and provide preliminary results of the process based on the plant's performance. It will also compare the Intec Copper Process with a few of the competing technologies and evaluate the relative economic merits of Intec.

Jan 1, 1999

By L. E. Murr

Solution flow in leach dumps and heaps or in columns of representative rock has been the subject of only limited studies. This is a regime involving unsaturated flow in semiconsolidated rock with a wide size distribution. Even the concepts of continuous flow systems are fairly recent, and have evolved from the search for better methods of operating industrial chemical reactors. (1-3) Waste rock consolidation and permeability play a key role in solution flow characteristics. Harris (4) suggested that bulk density variations in a leach dump could alter the particle-to-particle contact, and that large particle aggregates could act like single, large particles . In the limiting case where the bulk density approaches that of the undisturbed, consolidated rock, the entire waste unit would behave as a single particle. Roman (5) treated the phenomenon of bulk density and its effect on consolidation in terms of lixiviant flow paths or solution channeling in leach dumps. Like Harris, he assumed that no solution moved through particles or particle aggregates associated with zones of high bulk density. Solution flow paths are thus effectively separated by particle regimes, creating solution channels in the waste body. While some attempts have been made to describe solution flow in leach dumps and related systems by utilizing computer model approaches and laboratory- scale simulations (5,6), there have been no direct, large-scale observations of solution movement in channels or of the actual channel sizes and distributions within a waste body. This paper describes a series of experiments involving large-scale, controlled waste leaching tests, conducted over a period of several years, and aimed at providing some direct observation of the changes in waste consolidation and permeability, the size and distribution of solution channels, the movement of such channels with continued solution application, and other features relating to solution flow during the leaching of low-grade waste. These results are then combined with mineralogical information to explain observed leach behavior.

Jan 1, 1981

By B. M. Davis

The Colosseum Mine is within the Clark Mountain mining district located approximately 72 km (42 miles) southwest of Las Vegas. Nevada in San Bernardino County, California. Gold mineralization at the Colosseum Mine is hosted in two 150 m by 210 m (500 ft X 700 ft) interconnected. rhyolitic intrusive breccia pipes that intruded Precambrian crystalline basement rocks and over-lying Paleozoic marine sedimentary rocks. Sub-sequent erosion (de-roofing) of all of the Paleozoic section and a portion of the Precambrian section has exposed the pipes to the present level (probably a significant depth in the original breccia pipe system).

Jan 1, 1989

By T. Y. Yan

An effective elution technique has been developed for recovering uranium from ion exchange resins loaded in the carbonate leaching process. The procedure employs direct elution with acid. In comparison with conventional base elution, the procedure yields eluate of higher uranium concentration, results in a more complete elution, keeps the performance of the ion exchange resin at the fresh stage, reduces acid consumption, eliminates carbonate consumption and reduces waste for disposal. The technique has been successfully demonstrated in the field and patented. It lends itself to commercialization.

Jan 1, 1988

By K. V. Raj, T. Bhowmick

"The control of fugitive dust in high-latitude openpit mines is challenging due to unique atmospheric phenomena resulting in complicated flow regimes as well as atmospheric inversion due to the lack of adequate insolation during prolonged winter seasons. In this study, two idealized (one conical and one trapezoidal) three-dimensional openpit mine geometries were simulated for different seasonal conditions using a computational-fluid-dynamics package from Software Cradle. The airflow was solved by Reynolds-averaged Navier-Stokes equations using the standard kappa-epsilon turbulence model. The concept of particle tracking was used to predict the flow patterns of dust particles. For various climatic conditions and two different pit geometries, fugitive dust particles varying in size, from PM0.1 to PM10, and concentration were generated at various locations and dispersed by the airflows inside the openpit mine. The amount and location of dust particles inside the pit were reported at various time intervals. In the summer season, airborne dust particles were quickly transported outside the openpit domain. In the winter season, however, the development of atmospheric inversion significantly affected the amount of dust retention inside the openpit domain. IntroductionThe computational-fluid-dynamics (CFD) modeling of openpit mines is challenging. In a recent paper (2015), we presented different constraints and challenges in developing a three-dimensional CFD model. In order to obtain realistic results from a simulation, however, appropriate values of various inputs are required. The simulation results of a three-dimensional nonhydrostatic model by Shi et al. (2000) showed that both the mechanical and thermal forces are important mechanisms, controlling the development of the atmosphere inside an openpit mine. Alvarez et al. (2007) used a CFD model for predicting dust dispersions in a medium-sized limestone quarry, and presented several iso-surfaces of varying dust concentrations using ANSYS CFX. A similar study by Torno et al. (2010) introduced a more sophisticated parameterization of the dust sources. Flores et al. (2014) used an OpenFOAM CFD simulation package to simulate and predict pollutant dispersion in an idealized and an actual openpit mine in Chile with an intense insolation condition. The model was simulated for three different conditions: (1) air-advection (10 m/s, or 33 ft/ sec)-driven mechanical turbulence, (2) surface-heat-flux (240 W/m2, or 76 Btu/ ft2-h)-driven thermal buoyancy and (3) both air-advection- and surfaceheat- flux-driven conditions. The results of the simulations showed that the buoyant currents contribute to the removal of a large percentage of the dust particles. The buoyant currents modify the purely mechanical-turbulence- induced flow pattern and reduce the particle residence time, commonly observed in a purely mechanical turbulent flow (nonbuoyant case)."

Jan 1, 2015

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 A. B. Cecala

The Bureau of Mines has been performing research to lower the dust exposure of workers at mineral processing operations for a number of years. This research has mainly been directed at source control techniques in an effort to lower a worker's dust exposure at a particular job function. In some cases, this control technology provided a carryover effect in lowering the exposure of workers at other locations, but for the most part had very little effect in lowering dust levels throughout an entire mill building. Recently, the Bureau became aware of several mineral processing operations having problems with high over-all mill dust levels. These operations were all using baghouse-type collectors to address their most serious dust contamination areas. Although these major dust sources were being controlled, there were numerous minor dust sources that were not. These minor dust sources were causing dust levels in these operations to gradually increase as the day or shift progressed. The intent of this work was to determine general guidelines and design criteria for operations that may be interested in implementing a total mill ventilation system. Most mill buildings can be considered a closed system and thus any dust that is not being controlled within the structure, will cause dust levels to gradually increase over the shift. A total mill ventilation system should be designed to draw clean make-up air in near the base of the mill. This air provides general purging and may clear some dust laden areas throughout the mill structure. This air should be discharged at or near the top of the structure, where it is not a contaminant to plant personnel working outside. Without this exhaust system, dust can exit the building through open doors, windows, etc., and contaminate outside plant workers. This dust can also be recirculated back into the mill building causing additional contamination problems. A total mill ventilation system is not a stand-alone technique, but is a supplemental technique to assist other localized dust control systems.

Jan 1, 1994

By Charles S. Robinson

The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains about 50 miles west of Denver. The ore body is being developed for mining by workings that extend more than 3500 feet below the topographic surface. During construction of the mine workings, ground water in fractures in crystalline rocks has been encountered. From 1969 to 1973, Charles S. Robinson & Associates, Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic records of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentary rocks and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past. Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreased with tire!. The rate of decrease in flow (or pressure) is exponential. By measuring the change in flow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 1, 1976

By D. R. Baughman

Copper oxide deposits that may be considered for in situ leaching exist in unique geologic settings, different from uranium deposits. A large number of interrelated factors must be considered in wellfield design. Many of these factors are hard to quantify and are directly related to geologic features of the orebody. This paper discusses some of the important factors in wellfield design and suggests an outline for a design procedure.

Jan 1, 1988