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By F. Ma, F. Yang, T. Zhao, P. Dai, Z. Shao, D. Zuo

With the development of modern digital technique, computers have been widely used to monitor and control in retrofitting traditional industries. In Chinese coal industry, some analog monitoring and control systems have been replaced by the modern computer digital systems. According to the development status of Chinese coal industry, this paper presents some technique and its applications of modern digital computer monitoring and control for safety mining production process. The technique has been used in the full digital monitoring and automation control for hoists, coal mining machines, belt transport machines, and whole coal mining production process. With the technique, it has been achieved the better economical and social benefits in safety mining production in China.

Jan 1, 2003

By R. E. Robinson

On 18th November, 1991, the Department of Chemical Engineering at the University of the Witwatersrand, Johannesburg, held a display of posters to review their R & D activities. Although not a new concept, this series of presentations was the first time that the Department of Chemical Engineering at Wits had undertaken as comprehensive a review in this particular format. It turned out to be a most worth-while exercise, and the many visitors must have been impressed with the quality of the presentations.

Jan 1, 1991

By G. L. Smith

[Research and development conducted by CSR.-Mining Technology in the areas of active continuous miner based coal dust/methane explosion suppression systems, passive 'bag based, atone dust barriers systems, din and positioning of refuge bays, integrated escape and rescue strategies, and neural network based coal dust/methane explosion risk assessment is briefly described. It is concluded that effective catastrophic risk management of coal dust/methane explosions is dependent on an integrated, systems approach drat encompasses fundamental understanding of hazard sources, qualitative and quantitative probability of occurrence, magnitude of consequences and efficacy of control and recovery measures.]

Jan 1, 1999

By A. J. S. Benade, N. B. Strydom, W. H. Van Der Walt

The performance of the improved microclimate suit by N. B. STRYDOM M.Sc., Ph.D. (Illinois) (Fellow), A. J. S. BENADE, B.Sc. (Potch.) (Visitor), and W. H. VAN DERWALT, M.Sc. (Potch.) (Visitor) An assessment has been made of a new improved microclimate jacket when worn by men working for four hours in a hot environment (wet-bulb temperature of 33,9°C and an air speed of 0,4 m/s) and at work rates of 35 Wand 70W. At the lower rate of work in heat, the use of microclimate suits maintained the rectal temperatures of the men at almost the same level as when they worked without that protection at normal room temperature (20°C). At the greater rate of work without protection, the men's rectal temperatures rose to 40°C within two to three hours, so that they could not complete four hours of work. When they wore microclimate suits, they easily completed four hours of work, and their rectal temperatures were lower than when they worked at the lower rate without protection.

Jan 8, 1975

By D. G. Hulbert, I. K. Craig, S. P. Moult

This paper describes the application of a throughput-optimization strategy to a run-of-mine (ROM) mining circuit that is controlled by a multivariable controller. The objective of the optimization strategy is to maximize the ROM throughput at a specific product size. Results from long-term tests, which indicated how 'steady-state' optimization can be achieved, were used for the throughput optimization. This strategy increased the ROM throughput by 11,4 per cent. A mathematical relationship relating residue to grind can be used to calculate the economic benefits of stabilizing control. It was estimated that the throughput optimizer could result in an increase in gold production worth Rl,4 million per annum when waste rock is treated, and that stabilizing control could increase the treatment plants annual revenue by R150 000. If the extra milling capacity brought about by the optimizer is interpreted as a capital cost saving of 10 per cent on the price of a new mil, then a capital cost saving of RI million could result.

Jan 1, 1992

By M. C. van Blerck

Since its introduction in 1956, the capital allowance has been increased and its scope widened. At present the allowance is 10% in respect of two categories of gold mine (post-1973 and other deep level mines) and 6% in respect of natural oil mines. The allowance is a significant incentive encouraging the development of new mines, to the benefit of both the fiscus and the South African economy as a whole. A strong case can be made for increasing the amount and the scope of the allowance. The Margo Report recommendation that the allowance should possibly be replaced with a system of direct grants is, in theory, neutral. However, practical difficulties exist with cash grants and there is concern with the implications elsewhere in the Margo Report that the capital allowance is excessive and that, as a consequence, such direct grants will represent an effective reduction in this incentive. I believe that the best course of action would be the retention (and enhancement) of the capital allowance and the expansion of its scope.

Jan 1, 1988

The first commercial Corex Plant in the world capable of producing liquid iron from a variety of low-grade coals was commissioned in 1990 by Iscor at its Pretoria Works. The Plant has an annual production capacity of 300 kt of liquid iron. Because the compulsory use of coke is eliminated, the new method offers an economic and revolutionary alternative to liquid-iron production. Coke used in traditional blastfurnaces is manufactured from high-grade coal of which the available sources in South Africa are limited.

Jan 1, 1991

Mr R.D. Beck attended Felsted School in Essex (England) and the Royal School of Mines, University of London, where he ob¬tained the degree of B.Sc.(Eng.), A.R.S.M. in mineral technology in 1969. His other qualifications include Pr.Eng. (1976), C.Eng (1975), and M.I.M.M. (1975). He joined Gold Fields of South Africa in December 1969, and worked at Doornfontein Gold Mine, Greenside Colliery, West Driefontein Gold Mine, Zwartkloof Fluorspar, Gold Fields Laboratories, Gold Fields Head Office, Libanon Gold Mine, and Kloof Gold Mine before being appointed Plant Superintendent at East Driefontein Gold Mine in January 1973. In June 1976, he was transferred to Head Office as Group Metallurgist, followed, in November 1978, by his secondment to Black Mountain Mineral Development Company as Plant Superintendent, to take on-site responsibilities for staff training, plant commissioning, and start up. On his return to Head Office in July 1980 as Assistant Consulting Metallurgist, he was responsible for Black Mountain and new metallurgical projects. Then, in January 1984, he was appointed General Manager of the Zinc Corporation of South Africa Limited. He became a member of The South African Institute of Mining and Metallurgy in 1973.

Jan 1, 1985

By W. P. Channon, J. B. See

The reduction of fluxed and non-fluxed manganese, ores by ferromanganese silicide by W. P. CHANNON, B.Se. (Eng.), M.Sce. (Eng.) Wits. (Visitor) and J. B. SEE, B.Sce. Hons., Ph.D. (New South Wales), M.I.M., M.I.M.M. (Member) In South Africa, medium-carbonferromanganese is produced by the silicothermic reduction of slags containing MnO. Because of its importance in the production of refined ferromanganese, a study was made of the reaction between a premelted South African Mamatwan manganese ore and various ferromanganese silicide reducing alloys, with and without fluxing agents. Because the reaction is highly exothermic, temperature appeared to have little effect on the rates of manganese transfer to the metal and silicon transfer to the slag, and an apparent equilibrium was rapidly approached. Limits were determined for the favourable effects of fluxing additions, and manganese recoveries were found to decline as the ratio of CaO to MgO decreased as a result of the addition of basic flux. The recovery of manganese passed through a maximum, and subsequently decreased for variations in the ratio of alloy to ore. The results obtained, when used in conjunction with other physicochemical data related to this slag-metal system, suggest optimum slag compositions for the efficient manufacture of medium-carbon ferromanganese from Mamatwan ore.

Jan 3, 1977

By T. R. Twiddle

The sequential flotation of copper, lead, and zinc in that order is practised at the Broken Hill Concentrator of the Black Mountain Mineral Development Company (Pty) Limited. The minerals of economic importance are chalcopyrite, galena, and sphalerite, with associated silver. The targets for recovery and grade in the lead and zinc circuits were reached quite readily after start-up, but the copper circuit failed to meet the performance requirements with respect to both recovery' and grade. The original circuit for copper is described, together with the subsequent investigations and modifications that were required to produce acceptable metallurgical results. Circuits for semi-bulk and bulk flotation were tried, and the effect of the oxidation state of the pulp was investigated extensively and found to be all important. Tests were conducted on the depression of lead in the cleaning circuit by the use of sodium dichromate, and on heating with the addition of sulphurous acid. The latter technique was ultimately the more successful. The proportion of fresh to recycle water entering the circuit was shown to be important. The original reagent regime was altered and augmented. A more recent problem has been the contamination of the ore with cemented backfill. The changes that this new condition necessitated are described. Success has been measured by a continuous improvement in the economics of the copper recovery.

Jan 1, 1984

By A. Madowe

This paper discusses the mine planning process for Letseng diamond mine in the Kingdom of Lesotho, in conjunction with the various software packages used during the process. The major pillars of the long-term mine planning process at Letseng are pit optimization followed by pit design and scheduling. Letseng uses Gemcom Whittle and GEMS for pit optimization and design and Runge XPAC for scheduling. The output of the mine planning process results in the generation of published mineral reserves and provides input into the Letseng overall business plan. The process of defining the key inputs for the entire mine planning process is discussed, which covers: ? Pit optimization ? Slope design as an input ? Diamond price inputs ? Operating and capital cost inputs ? Haul road design ? Generation of pit shells ? Selection of an optimum pit shell and interim cutbacks using operational scenarios ? Sensitivity analysis on the selected optimum pit shell. ? Pit design ? Slope design criteria in the detailed design ? Split shell vs concentric pit design ? Practical mining widths to determine cutback design ? Ramp design ? Pit design process in the GEMS software package. ? Detailed scheduling ? Development of scheduling scenarios in the XPAC software package ? Planning through mining production bottlenecks. ? Company-level NPV model ? Comparing scenarios and input of the different schedule scenarios into the company NPV model. Keywords pit optimisation, mine planning, pit shell, recovery, dilution, revenue factor, pit design, split shell, sensitivity analysis, scheduling, production bottleneck, NPV, discounted cashflow.

Jul 1, 2013

By Sönke Schmachtel

Several possible physico-chemical properties of composite electrodes for oxygen evolution are presented to describe experimental data for which a mathematical model had been developed. On this basis, local electrical and electrochemical properties of a composite electrode were investigated with conductive atomic force microscopy (CAFM) and scanning electrochemical microscopy (SECM). It could be shown by CAFM measurement that the boundary between matrix and catalyst particles seemed to have special advantageous electrical properties. The SECM measurements showed the presence of mass transport phenomena with increased surface concentrations, whilst the thickness of the Nernst diffusion layer was very small. An intermediate was detected and assigned to be hydrogen peroxide. From all species involved in the oxygen evolution reaction (H2O2, H+ and O2), it was concluded that local active spots exist on the electrode on which hydrogen peroxide reacts to oxygen and protons. A two?step two-material process was suggested to explain the whole oxygen evolution mechanism.

Jan 1, 2008

By W. C. Joughin

A risk evaluation model has been developed that enables the quantification of expected injuries and economic losses resulting from rockfalls associated with a support system in a given geotechnical environment, which is described in Part I (Joughin et al., 2011b). Part II presents the validation of the risk evaluation model. Underground mapping of joints and rockfalls was carried out to provide data for field calibration of the model. This survey was limited to small rockfalls, due to the relatively short period of mapping. Therefore the model was also correlated with rockfall and rockfall injury data collected by mine personnel. The analyses showed that the model provides a reasonable estimate of the expected frequency and size of rockfalls and the frequency of rockfall injuries, but further work is required to enhance the model. Three case studies are presented, which show the benefits of improved support systems from both economic and safety perspectives. This work has demonstrated that the risk evaluation model and the software developed are immediately useful, but further work is required to develop and improve the tools.

Jan 1, 2012

By S. M. Rupprecht

"Artisanal mining is basic mining characterized by manually intensive work methods utilizing primitive or simple equipment and conducted by individuals or small groups exploiting deposits. Artisanal mining in Rwanda and Burundi is further complicated in that the techniques applied are often inadequate, resulting in low productivity and poor recoveries, and workers are paid low wages with owners reluctant to reinvest in the mining operations. A consequence of this vicious circle is often poor working conditions, with miners operating under unsafe and/or unhealthy working conditions. An additional problem is that mining is conducted in a manner that is detrimental to the environment.Artisanal mining is commonly more dangerous than large-scale modern mining operations. Artisanal operations are generally subsistence activities with the miners focusing more on immediate concerns than the long-term consequences of their activities. When miners have no other source of income, they will usually find ways to evade controls and carry on working. Machinery tends to be expensive and often far beyond the reach of most artisanal miners, and therefore there is a general tendency for workers to focus on labour intensive and riskier mining methods.This paper proposes the introduction of small-scale mechanization with labour-intensive manual mining utilizing a bench mining approach in artisanal mines operating in Central Africa. From the 1950s to the 1980s bench mining was successfully conducted in Burundi utilizing manual labour. In order to achieve a balance between job creation and project economics, the combination of manual and mechanized mining is proposed. Manual mining offers the benefit of local job creation while ensuring good mining techniques, such as minimizing mining loses and dilution. Through the introduction of mechanized loading and hauling activities, areas of high stripping ratios can be viably mined, thus increasing the amount of resources that can be exploited. The use of a loader and tractor-trailer arrangement is proposed, thereby improving throughput, productivity, and worker safety and, reducing the impact on the environment."

Jan 1, 2017

By L. Woollacott, R. P. King

This paper presents data collected from full-scale plants in order to verify the predictions of a new simulator of CIP or CL operations. Good agreement was found between the experimental data and the simulator predictions. The simulator is able to predict the effects of many of the complex operating phenomena in GIP and CL plants that previous simulation techniques could not describe. This is illustrated by predictions of how factors, such as the manner of carbon transfer, concurrent leaching, and gold loading on eluted carbon, can affect the performance of an adsorption plant.

Jan 1, 1990

Guide Io Ihe Preparailon Of Papers For Publication In The Journal Of The South African Institute Of Mining And Metallurgy The following notes have been compiled to assist authors in the preparation of papers for presentation to the Institute and for publication in the Journal. All papers must meet the standards set by the Council of the Institute, and for this purpose all papers are referred to at least two referees appointed by the Council.

Jan 1, 1975

By P. S. Pashkovsky

Theoretical and experimental investigations of the process of self-heating the coal accumulation with use of geological and mining conditions of development of the seams, as well of mass recoil parameters, factors of oxygen diffusion in coals, critical temperatures of self-ignition, incubation times received under laboratory conditions allowed working out the method of the local prognosis of the hazard of coal self-ignition in the course of carrying out the mining operations. New relationships of calculation of critical dimensions of the coal accumulation and of the incubation time are proposed.

Jan 1, 2003

By A. Smith

The practice of leaving barrier pillars between adjacent longwall panels at The Durban Navigation Collieries (Pty) Ltd (Dumacol) has resulted in a considerable loss of coal reserves. Dumacol has now modified the layout of its longwall panels to allow the concurrent mining of barri9f pillars and the extraction of the longwalls. The Implementation of the new panel layout has increased the percentage extraction of reserves and will result in an extension in the life of the mine. The method of extracting barrier pillars between adjacent longwall panels is described in this paper.

Jan 1, 1985

By K. Bryan, O&apos

A 10-year program to integrate crushing and screening models into daily flowsheet design practice has proven successful. A Circuit Analysis Program (CAP) is used worldwide to design and evaluate new and existing crushing flowsheets. To gain user acceptance of CAP and maximize effectiveness, model development, simulation flexibility, ease of use, and developing international access are key issues. These issues have been resolved effectively resulting in flowsheet simulations to assist in justifying increased capital investment. CAP is presently utilized in Canada, United States, and South Africa with intentions to expand to Europe and Asia.

Jan 1, 1987

By A. Chryss, L. Pullum

Shear-thickening suspensions abound throughout the hydraulic conveying industry; at least this is the perception of many engineers running plants where hydraulic conveying is commonplace. In reality, shear thickening behaviour is limited, in the main, to high concentrations of fine particles, including colloidal and biological suspensions, at moderate to high shear rates. In the authors? experience most cases of shear-thickening behaviour have been either simple ?coarse? particle interactions, poor instrumentation techniques, or both. In some cases these were obviously heterogeneous flows, while in others flows that were homogenous, or were thought to be homogenous. Examples, which illustrate this erroneous perception are given. However, the trend towards pastes and complex suspensions that use high concentration carrier fluids means that the underlying slurries for many of these flows may now be truly shear-thickening. Unfortunately, suspensions that might exhibit shear thickening also invariably exhibit slip, or wall-particle depletion. These separate phenomena are difficult to resolve experimentally and many observations of apparent shear-thickening behaviour are in fact obscured or convoluted by slip effects. A method is presented whereby the true flow properties of these high concentration suspensions, and hence accurate prediction of pipeline flows, can be made using a parallel plate rheometer.

Jan 1, 2007