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By K. P. Madhusudhanan, R. K. Bhatia, K. S. Narasimhan, R. N. Singh

A typical case study of a coal washery of capacity 500 t/h raw coal input has been presented and discussed with particular reference to the techno-economics for flotation column vis-a-vis the conventional flotation cells, keeping parameters like input capacity and product ash same. The results presented indicate that substitution of flotation cells by columns in a coal washery results in advantages of increased fine coal recovery, better quality of concentrates, lower capital and production costs etc.,. The effect of increasing the specific capacity of the column by design modifications on the cost benefit is also analysed.

Jan 1, 1988

By M. W. Harmer, J. M. Quist

Laboratory test work, pilot plant testing and plant experience with wet, fine-mesh screens are discussed. High-frequency, low-amplitude, fine-mesh, wet screens were installed on the 6th cleaner concentrate stream. These screens produce a 60% oversize recovery split of the molybdenite concentrate that is of leached equivalent quality. The undersize stream is leached with hot ferric chloride to remove lead and copper contaminants before roasting or shipment to sulfide customers. This plant modification is a good example of using existing technology in an unconventional flow sheet to yield significant cost savings.

Jan 1, 1991

By Boshou Bian

Air quantity is the primary parameter governing the working condition of a mine fan. In order to improve the fan performance and efficiency, reduce its energy consumption, and guarantee mine safety, it is very important to obtain an accurate value. However, generally speaking, the fan ducting or drift on surface is very short in distance and contains sharp bends. The air quantity of the mine is so concentrated in this way that the air velocity becomes very high, and the airflow, either in the fan drift before the fan impeller or at the downstream diffuser, is very turbulent. Therefore, no anemometer is satisfactory because there is too much difference between the measured value and the actual value of air quantity at the mine fan.

Jan 1, 1989

By D. E. Ranta, George F. Weaton

Estimating the Iron Ore reserves of Minnesota are directly related to both the geology of the deposit and the Scandinavian heritage of its people. The flat lying deposits, when properly prospected, make estimating easy and accurate across wide areas of the Mesabi Range. It also makes taxation simple on the unmined reserves. The reserves are their heritage and all the people should benefit, not just the owners. Heritage also dictates that newly discovered ores were there before discovery, hence, subject to the omitted property tax and liable for six years back taxes.

Jan 1, 1992

By P. M. Lin, P. Tsang, S. S. Peng

This paper presents an overall stabilization method to eliminate the potential of reoccurrence of subsidence over abandoned mine lands (AML). The method considers column grouting at specific locations, including the destressed and stress concentration zones, instead of grouting around and beneath damaged structures. The latter method is currently commonly used for AML subsidence abatement. The finite element method (FEM) can be used to calculate stress distribution in the strata before and after grouting. A grouting pattern is generated that includes the location and number of grouting holes. Stress concentration can be reduced or eliminated. A comparative analysis, including the number of grouting holes, area of grouting influence, stress level and potential of subsidence reoccurrence, is also presented.

Jan 1, 1993

By Joseph A. Zupanick

Methane drainage is a mature technology, now commonly practiced in many highly productive underground coal mines throughout the world. Universally, the practice of pre-draining methane will continue to grow as near-surface coal seams become depleted and mining operations are forced to exploit deeper reserves. These deeper coal reserves inherently have higher gas contents. In addition, increases in productivity and extraction rates have caused higher methane liberations per unit of time. As the cost of providing ventilation air increases, the economic justification for implementing a methane drainage program becomes apparent.

Jan 1, 2005

By J. Iannicelli

A variety of domestic bauxites have been beneficiated to meet refractory grade standards by use of high intensity, high gradient, wet magnetic separation. Besides reducing the iron content to less than 2%, the Ti02 content of the bauxite was also reduced. The beneficiation can be accomplished by means of a simplified wet process flow sheet with an estimated cost comparable to that of water washed, filler grade kaolin. The process has been carried out on a small pilot plant and then scaled to produce 25 tonnes of calcined refractory bauxite meeting National Stockpile Specifications.

Jan 1, 1984

By S. Su, S. Natansohn

This report describes a process for tungsten recovery from Searles Lake brines and upgrading its concentration to useful levels. The method consists of a combination of a liquid-solid and liquid-liquid extraction step and results in a product stream containing more than l00g W03/1. This technique is also effective in substantially reducing the concentration of objectionable impurities in the tungsten product. An ion exchange extraction mechanism is postulated.

Jan 1, 1983

By Don Stainbrook

Over a period of many years a highly automated computerized system of ore control has been developed at the Newmont Gold Company, (NGC). It is the purpose of this paper to review the development of this system, describe the setting in which it functions and to mention some of the future developments and enhancements. Discussion of the evolution of the system in a historical perspective helps to understand its present status and illuminate some thinking about future directions of development.

Jan 1, 1989

By Michael S. Robinson, Serge Moalli

Construction of the CSO Retention - Treatment Tunnel, Segment 1 in Dearborn, Michigan includes excavation for an overflow Structure with a minimum inside diameter of 15.24 m (finished). The excavation extends downward through overburden soil including a 15.2 m thick zone of potentially weak clay. This paper presents the subsurface data for the clay and a geotechnical analysis thereof, together with predictions of the behavior of the planned 15.54 m inside diameter open end caisson as it is sunk through this potentially weak zone. In a companion paper, the writers will compare the behavior observed with that predicted.

Jan 1, 1995

By Norbert Patzelt

The high-pressure grinding roll was introduced about 10 years ago and has established itself in many applications. Most of these machines are used in grinding circuits in the cement industry. A few operate in conventional mineral-processing plants. Polysius has sold more than 350 Polycoms worldwide. An exception is diamond-ore processing in South Africa and Australia. This type of grinding system increases diamond liberation and reduces the capital costs for the downstream processing plant. There are several reasons why high-pressure grinding rolls have not been used more extensively in the mining industry: - The mining industry adheres to conventional grinding technology and regional preference for certain comminution circuits. - Design, scale-up and flowsheet assessment procedures are viewed as being immature and reduce confidence in the potential application of the technology. - Downstream process benefits are unproven on a plant scale.

Jan 1, 1995

By J. R. Blair, D. P. Lindroth, W. R. Berglund, R. J. Morrell

The objective of this US Bureau of Mines (Bureau) research was to determine the technical feasibility, principles and effectiveness of a combination energy method for drilling and cutting hard rocks. Experimental test results of microwave heating and drilling in basalt and granodiorite are given. The experiments were performed with pilot-scale, commercially available equipment employing microwave energy at a standard industrial frequency of 2.45 GHz. The data indicate that penetration rates, well in excess of the state of the art, are possible.

Jan 1, 1993

By B. Towson, R. F. Dalton, G. W. Seward

This paper reviews the successful application of oxime reagents for the solvent extraction of copper and considers the role that well focussed research initiatives can play in bringing further radical change to the metallurgical industry. Particular reference is made to the Cuprex Metal Extraction Process (CMEP), for the treatment of low grade or difficult to treat sulfide concentrates, using the reagent Acorga CLX- 50 to recover the copper and the reagent Acorga ZNX-50 for the recovery of zinc from chloride solutions. Other new extractants, currently in development, are also referenced.

Jan 1, 1994

By Anthony Busigin, Charlett Busigin, Colin R. Phillips

For the purposes of measurement and dosimetry of airborne radon daughters in uranium mines and elsewhere, it is important to understand their physicochemical state. This work deals with the chemical fate of 218Po in air. Extensive experiments were performed to determine the rate of neutralization, diffusion coefficient and fraction born charged of 218Po in air. The experiments were performed in a specially constructed apparatus of well-defined geometry. Careful control of experimental conditions made it possible to obtain more precise and detailed quantitative data than previously possible.

Jan 1, 1981

By Y. H. Kim

A simulation procedure has been developed that realistically portrays aggregate growth and disintegration for particular types of floc structures in water and wastewater treatment processes. The procedure requires local dissipation rates and specification of an interaction distance between colliding particles. A principal difficulty encountered in polymer flocculation, however, arises from changes in conformation of adsorbed macromolecules. Therefore, in systems where polymer flocculation occurs by bridging, dynamic changes in the particle size distribution depend upon the interaction of nonlinear. stochastic hydrodynamics with particles whose growth results from a number of concurrent and sequential random processes.

Jan 1, 1988

By Y. V. Vasylchuk

An algorithm is presented for optimizing the classification of surface mine material subject to excavating constraints. High-resolution, expected-profit models are optimized to classification maps subject to site-specific excavating constraints. This optimization problem defies traditional closed-form analytical solutions. A practical heuristic algorithm quickly determines the optimum final destination for material subject to realistic selectivity constraints. The expected profit could be calculated from an estimated model if the value calculations are all linear; otherwise, simulation could be used. In both cases, a single expected profit for all destinations on a high-resolution grid is the starting point for dig limits optimization. Maximizing expected profit in a risk-neutral manner is correct given the repeated nature of grade-control decisions over relatively short timeframes.

By Pieter C. van Aswegen, J. A. Brierley, C. L. Brierley

The bacterial-oxidation (BIOX®) process for the pre-treatment of refractory ores for gold recovery is marketed by BlOMlN Technologies S.A. The process was originally developed by GENMIN who is still providing testwork, design and commissioning assistance to BIOMIN. Since 1986 three BIOX® plants have been commissioned by GENMIN. A further two plants will be commissioned during 1993 and 1994. The commissioning and operational experiences from these plants are described in the paper.

Jan 1, 1993

By W. Douglas Gould, Mei-Lin K. Stichbury, Jeffrey G. Bain, Blowes David W.

The mechanisms of release of arsenic in gold mine tailings were investigated. The highest concentration of dissolved As (75 mg/L) was observed near the base of the tailings impoundment, in close association with a peat layer. Elevated concentrations of reduced iron and hydrogen sulfide were also measured at the base of the impoundment. High numbers of iron-reducing and sulfate-reducing bacteria were detected at depths within the impoundment which correlated with dissolved As, Fe and H2S. The data presented in this paper suggest that arsenic is released from the tailings by bacterially-mediated reductive dissolution of As-bearing iron minerals.

Jan 1, 2000

By A. C. T. Bigg, A. F. Colombo, A. R. MacPherson

The step-by-step study of the Stronsay ores follows the testwork through the initial determination of Bond Rod and Ball mill work indices, the MacPherson Autogenous work indices and the production of a preliminary flowsheet. These results are then used to design a pilot plant program to test the effectiveness of fully autogenous primary and secondary grinding and to determine the feasibility of controlling feed rate by the use of variable speed mill drive and/or varying the mill load. A final flowsheet is recommended with mill sizes and power requirements.

Jan 1, 1992

By Lawrence A. Ph. D. Hansen, J. David Deatherage

Laboratory testing programs were conducted to investigate the performance under compression loading of several types of geomembranes and geotextiles proposed for use in heap and dump leach projects. Synthetic liners of several thicknesses were sandwiched between representative subgrade soils and cover materials, thus modeling in the laboratory the actual installation conditions expected. Performance was evaluated by visual inspection and vacuum testing. Several testing procedures and equipment were used to investigate the effect of these testing parameters on the predicted performance.

Jan 1, 1987