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By Anil Kumar

In underground mine production units that employ discrete-vehicle face haulage, feeders are used in the belt network so that vehicles can unload rapidly without transmitting to the conveyor network the high material flow rates that result from rapid unloading. They prevent production bottlenecks at the face, while reducing capacity requirements for downstream materials handling equipment. Similarly, surge bins may be installed at intermediate locations in the network to smooth flows from a number of upstream sources, thereby reducing downstream belt capacity requirements. This paper introduces new stochastic process models to temporally describe loading patterns from unit operations and techniques for computing the probability of various fill levels for the feeder or surge bin. These results may be used to analyze the effect of alternative bin or feeder capacities and discharge rates on the performance and costs of the materials handling system.

Jan 1, 1994

By Ernest Koenigsberg

In 1961 Lerchs and Grossman presented a method, based on graph theory, to determine the optimum ultimate pit limits for an open-cast mine. At the same time they demonstrated a dynamic programming algorithm for the optimum pit limits for a two-dimensional open-cast mine. Since then many methods for determining optimum limits for three-dimensional mines have been programed, and even more have been reported in the literature. The methods include computer "simulation" of the manual methods used by engineers, the development of sets of conic sections and fitting to exclude overlap, integer linear programming (and its equivalent network flow model), and dynamic programming. Many of the methods do not guarantee optimal solutions but seem to satisfy the user. Other reported methods have never been applied, partly because they did not yield optimal solutions. We have developed a three-dimensional dynamic programming algorithm which requires a single pass through the data. Large problems can be solved on a small computer because only a small part of the data is required at any time. In this paper we will review the state of the art and to demonstrate the connection between linear programming (and network flow) models and the dynamic programming method.

Jan 1, 1982

By J. C. Cawley, J. Sottile, J. L. Kohler

Control circuit failures contribute significantly to continuous miner downtime. The time required to put the machine back into production is a function of the time required to diagnose the problem, obtain parts and make the repair. Of these, the diagnostic time is often the largest. A microprocessor-based system with the ability to diagnose all of the common control circuit failures was designed, installed on a continuous miner and tested. This paper summarizes the development of the diagnostic system and provides examples of the system's diagnostic capabilities. Implementation issues and the hardware used for the prototype are briefly described. Comments on the system's performance are also presented.

Jan 1, 1995

By E. M. Cukrowska

The evaporative pan complex consists of two adjacent seasonal pans. These pans carry an exceptionally high salt (TDS) load due to over 50 years of effluent discharge via the pipeline from mines. The nutrient, heavy metal, radionuclide load in the water and sediments of the pans are very high affecting groundwater around the pans. The groundwater in the region contains TDS > 40 000 mgl-1 and sulphates > 7000 mgl-1, whereas groundwater in areas assumed to be unpolluted by mining activities have TDS < 500 mgl-1 and sulphates < 200 mgl-1. The extent of continuity between the pans and the groundwater is unknown, although there appears to be seepage of contaminated groundwater into the river system.

Jan 1, 2006

By P. K. Davis, B. Gharib

The results of a previous basic study of the flow and design characteristics of hydrocyclones demonstrated that a recovery as high as 99% with a product rating* of 0.95 can be achieved on a batch+ basis with a single, water-only cyclone if it is configured properly. The next logical step was to demonstrate continuous processing of gob for the efficient recovery of coal by means of a laboratory-size demonstration system. A project to design and construct such a single-¬cyclone system was sponsored by the US Department of Energy, which also sponsored the initial study. A recovery of 93% with a product rating of 0.89 was demonstrated. The system design and the data taken are discussed.

Jan 1, 1990

By N. Edmonson

During the last 30 years, a dramatic increase in the supply of byproduct sulfur substantially reduced the share of the market held by Frasch-mined (non-by-product) sulfur in North America. Even though Canadian sulfur production is not discretionary, the geographic remoteness from the large US markets and the high transportation costs associated with delivering sulfur to those markets has meant that Canadian producers act like discretionary producers in many important ways. They have effectively replaced the US Frasch producers as the cost-marginal sulfur source to large US markets. Implications of this change in market structure include more volatile sulfur prices and longer sulfur price recessions.

Jan 1, 1997

"?irovski Vrh" Uranium deposit in Slovenia is type of mineralized sediments in ore bearing belts of deflected S-structure, in which the belt is less than 25% mineralized. Ore bodies of irregular small thickness, unreliably contoured, made difficult estimation of correct contours, which are necessary for design and exploitation works. The deposit was explored by vertical boreholes made at the surface and by boreholes fanned from drives. For the purpose of application of this estimation method, 1 m composites have been made in slices which were parallel to the referential belt plane. Estimation was made for 1,5m x 1,5m x lm blocks which do correspond to the size of the containers in the ore transport stage. Two variables have been used: the first, indicator of function (ore=1, waste material =0) and kriging method; the second, logarithmical content of Uranium and Minimum Mean Square Error Estimation (MMSEE) method. Based on estimated values of those variables, probability of ore quantity as well as Uranium content over determined cut-off were calculated for each block. Those two parameters enable determination of the most probable form of the ore body in ecah one metter slice. Estimation of sixteen small blocks in a large 1,5m x 1,5m x 1m block made possible estimation of ore quantity and its content for the determined cut-off, as well as categorization of exploration. This method is being used for estimation of ore reserves and planning of exploration operations. The described&apos; methodology was tested in an exploitation block.

Jan 1, 1986

By D. Panias

Alumina hydroxides such as gibbsite (Al(OH)3) and boehmite (AlOOH) are precursors of many types of alumina that find important industrial applications. The thermal decomposition of AlOOH, which is a more energy saving precursor compared to gibbsite, gives rise to the formation of ?-, d-, ?- and a-aluminas that are used for the production of catalysts. The applications of the aluminas are governed by their properties that are a function of the precursor material and its microstructure. The microstructure in turn is a factor of the method and conditions applied, as well as, in the case of soft chemical processes, on the anions present. Towards these ends, this study was focused on the effect of different anions on the physicochemical characteristics of the alumina hydroxides precipitated in the first 5 minutes after the perturbation of the stability of a supersaturated sodium aluminate solution (Bayer liquor).

Jan 1, 2006

By Andrew M. Garvie, William W. Plotnikoff, Eugenia Y. Kuo

Water infiltrating the surface of waste rock dumps transports pollutants into the environment. Lysimeters have been used to quantify the infiltration rate. To date their design has been guided by modeling under steady-state conditions. Recently a two-dimensional finite element code has been developed to model the response of lysimeters to time-dependent infiltration rates. It was used to investigate the response of lysimeters installed in a waste rock dump and subject to a monsoonal rainfall pattern. The results are presented and compared with field data.

Jan 1, 2000

By Y. Wang

Wet magnetic separation methods for recovering hematite and chromite fines and ultrafines are investigated in this paper. These methods include wet high intensity and high gradient magnetic separations, carrier or "piggy-back" magnetic method, magnetic field-induced aggregation and magnetic seeding. This investigation indicates that wet magnetic separation is more efficient for fines and ultrafines whereas other methods can be used to enhance the particle aggregation and/or the magnetic response. The magnetic behaviour of these minerals with respect to magnetizing field, particle size and temperature is also presented.

Jan 1, 1993

By L. Xu, N. I. Jayaraman, R. Bhaskar

The objective of this study is to develop a better understanding of the collection characteristics of dust measurement instruments used in mine dust control research with respect to properties of quartz and coal dust. Coal and quartz dust of narrow sues, with aerodynamic median diameters being approximately 2 µm, 4 µm and 10 µm, with quartz contents of l0%, 20%, 30%, 40% and 50%, were released in an aerosol characterization chamber using a fluidized bed aerosol generator. Dust was collected in MSA personal gravimetric samplers with l0-mm nylon cyclones, total dust samplers and Sierra 298 inertial cascade impactors. The samples were analyzed for mass and quartz content. A total of 21 experiments were performed for this study. The mass and quartz collection efficiencies of the total and respirable dust samplers and the impactor were determined. The data show that the amount of dust collected by the respirable dust sampler (respirable + oversize dust trapped in the cyclone pre-classifier) was, in general, less than the amount collected by the total dust sampler. The amount of dust collected by the impactor was higher than that collected by the total dust sampler. Quartz analyses of the airborne dust samples showed that the total dust and respirable dust samplers (including oversize dust) collect less quartz dust than at inertial impactor. The larger the median particle sire of the quartz and coal mixture, the lower the quart content of the dust collected in the samplers. For all three sires, the impactor was a better collector of quartz than the other instruments.

Jan 1, 1994

By [Miroslaw] M. Hajdasinsk

The identification of the real internal rates of return (IRR&apos;s) of a project is essential for its economic evaluation. The existing methods for the calculation of IRR&apos;s are both cumbersome and unreliable, mainly because of their inability to effectively isolate the real IRR&apos;s and incapability of discovering multiple IRR&apos;s of even multiplicity. In this paper, a concept of the &apos;cash flow pattern tree used for isolation of the real IRR&apos;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&apos;s of a project. The method examines whether or not real IRR&apos;s exist, and if they do, isolates them within bounded and narrow intervals in a mathematically founded way. The isolated IRR&apos;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

Gold cyanide equilibrium adsorption isotherms in the loading range typical of operating carbon-in-pulp/carbon-in-leach plants have been established and the effect of various cations and the presence of copper cyanide species quantified. It was found that the equilibrium loading of gold was enhanced by the presence of sodium or calcium, with calcium having an order of magnitude stronger effect. The presence of copper has an adverse effect on the equilibrium loading of gold. A unified model was developed to predict the effect of sodium and calcium concentrations in solution and the competitive carbon adsorption of copper on the equilibrium loading of gold on carbon. A satisfactory agreement between the measured gold equilibrium loadings and the model results was obtained over a wide range of solution conditions.

Jan 1, 2010

By R. G. Robins

The dissolution of metallic copper powder in aqueous solutions of cupric sulfate with ethylene under low pressure was investigated. The reaction stoichiometry obtained was:

Jan 1, 1988

By Frederick H. Parkinson, Joseph Fernandez, David E. Westfall

The April 13, 1992, flooding in the freight tunnel network under the city of Chicago had a profound effect on the nearby Chicago Transit Authority (CTA) subway service. This paper provides an overview of the evaluation techniques, mitigation measures, and water control efforts used to maintain the integrity of the subway tubes. Specific topics discussed include visual inspections, inflow monitoring, structure and soil testing and sampling techniques, and the development and implementation of chemical and cementitious grouting programs.

Jan 1, 1993

By Peter L. Hofmann

Significant quantities of nuclear wastes were first generated in 1944 as a byproduct of the national defense program. To establish the current inventories and future projections of nuclear waste products is not a simple task. The Oak Ridge National Laboratory recently issued a report which now constitutes the official basis for nuclear waste inventories and projections. Radioactive wastes originate from five major sources (U .S. Department of Energy, 1980b) : (1) From the commercial nuclear fuel cycle related to the production of electricity , (2) From defense related activities, (3) From institutions such as hospitals, universities, and research foundations, (4) From industrial uses of radioisotopes, and (5) From mining and milling of uranium ores.

Jan 1, 1981

By M. M. Rajkovich, L. Adams, J. J. Zaluski, S. Gardner

In 1998, a group called Kentuckians for the Commonwealth filed an Administrative Petition with the Kentucky Natural Resources and Environmental Protection Cabinet to designate 8,903± hm2 (22,000± acres) on Black Mountain, which contains the state&apos;s highest point, as unsuitable for mining. A fast track legislative process was triggered that could have "taken" 91 Mt (100 million st) of coal reserves or, in the alternative, imposed severe restrictions on mining. Even with all parties represented by reasonable individuals, this process can be extremely cumbersome and expensive. The legal and technical preparation for this unusual hearing process as well as issues and strategies of the negotiated resolution are reviewed

Jan 1, 2002

By J. P. Rider

Along with increased production from longwall units has come the likelihood of increased worker noise exposures. In recent years, equipment has become larger, more powerful, and noisier than its predecessors. For these reasons, the Mining Division of the National Institute for Occupational Safety and Health (NIOSH) is investigating worker noise exposure on longwall faces and researching possible solutions to reduce this exposure. Part of this research effort involves studying the effect of covering the underside of longwall shields with acoustical material to reduce reverberating noise along the face. Experiments using acoustical absorptive insulation to cover the undersides of the shields, shearer body, and the shield supports were conducted at the full scale simulated longwall test facility located at the Pittsburgh Research Center. Sound levels were recorded every l.5 m [5 ft] along a 15.2 m [50 ft] section of the simulated face for all of the conditions tested. The analysis of the data indicated that a 2.0-3.0 dBA noise reduction was achieved between the shearer drums and a 4.0-5.5 dBA attenuation was attained upwind of the headgate drum.

Jan 1, 1997

By J. R. Mattern

The engineering geology of the Rio Tinto Borax Boron Mine creates challenges in providing practical slope design recommendations to mine planning engineers. Low strength sedimentary units interbedded with very low strength lakebed clays surround the orebody. Faulting has offset and juxtaposed these units into variably adverse orientations, while groundwater is compartmentalized both vertically and horizontally within fault blocks. A collective program of geologic data collection, geomechanical strength testing, geologic modeling, slope depressurization, confirmation of underground stope locations, and documentation of slope behavior provides vital information for design investigations and sensitivities. Analysis results lead to risk assessments and operational procedures that add value to the business by optimizing slope configurations and minimizing risk.

Jan 1, 2004

By B. R. Green, Ms. M. H. Kotze

Ion-exchange fibres (IEF) were prepared by the ir­radiation grafting of styrene onto polypropylene, which was then subsequently functionalized. Strong- and weak-base exchangers were prepared and evaluated Tor their ability to extract gold cyanide selectively. The IEF prepared had loading capacities similar to those of the corresponding resins and they had good selectivities for gold cyanide when contacted with a mixed metal-cyanide solution. The expected advantage of IEF over granular exchangers, that of faster kinetics, was illustrated. The strong-base Iibre in particular seemed to be very effective for the extraction of gold cyanide from dilute solutions such as return-dam waters.

Jan 1, 1990