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By W. L. Van Heerden

In situ complete stress-strain characteristics of large coal specimens by W. L. VAN HEERDEN, B.Sc. Hons. (Pret.) (Visitor) The significance of ;n situ tests on large coal specimens is briefly reviewed. Tests aimed at obtaining complete stress-strain characteristics of large coal specimens with high width-to-height ratios are described. A formula for the relationship between strength and width-to-height ratios of coal pillars is proposed, and the influence of width to- height ratios on the deformation characteristics of pillars is discussed.

By P. F. S. Jackson, A. Strasheim

In the survey "Analysis of South African raw bullion" the distribution of trace elements within the bullion have been shown to be distinctively dependent on the extraction process. In general the amalgamation process produces the more impure bullion with respect to trace elements. Some chemical and physical explanations are given for the differences that have been observed in the raw bullion as received at the Rand Refinery. The value of the spark source mass spectrographic technique in the study of the elemental impurities in bullion is demonstrated.

By Adams. M. D.

Most of the cyanide lost in carbon-In-pulp plants is due to the reaction of cyanide with base metals and sulphides during leaching. Some cyanide is also lost in the adsorption tanks as a result of oxidative and adsorption reactions with the activated carbon. The high rates of cyanide loss in the elution and electrowinning stages are atributable to hydrolytic decomposition and anodic oxidation, respectively. However, the relative amount of cyanide lost during these two stages is small for a given amount of ore treated.

Jan 1, 1990

By H. C. Voges

The use of heavy-medium separation in the processing of iron ores by H. C. VOGES. B.Sc. (Visitor) The paper discusses various aspects of the application of heavy-medium separation to the processing of hematite ore at Sishen and Thabazimbi. The two main factors to be borne in mind in the design of a plant for such beneficiation are the Iow unit value of the iron ore produced and the high separation densities required. The four factors of importance in the avoidance of high viscosity in the ferrosilicon medium are discussed in turn.

Jan 6, 1975

By D. D. Howat, J. van der Colf

Slags of the system CaO-MgO-AI2O3-TiO2-SiO2at had been reduced in graphite crucibles for selected time Intervals were fully re-oxidized so that an assessment could be made of the rate and extent to which the titanium oxide had been reduced. The derived kinetic parameters were studied as functions of slag composition and temperature. The extent of reduction after selected Intervals of treatment could be correlated with the physical behaviour of the melt (in terms of viscosity and electrical resistivity).

Jan 1, 1979

By P. C. Schutte, N. B. Strydom, A. J. Kielblock

Three groups of unacclimatized men were subjected to five-day climatic-room procedures at wet-bulb temperatures of 29,30, and 31 C respectively. The findings indicated that individuals reach a satisfactory level of heat acclimatization for work in environmental temperature conforming to those at which they were acclimatized. It is, therefore, superfluous to acclimatize men at wet-bulb temperatures that exceed those at which they are destined to work. These methods of acclimatization can be linked advantageously to heat-tolerance testing at mines with suitable underground temperatures.

Jan 1, 1983

By A. V. Z. Brink, D. M. O’Connor

Recent research into the prediction of mining-induced seismic events by the monitoring of small microseismic events at Western Deep levels Gold Mine is described. Measurement and interpretation techniques and results are presented. It was found that the occurrence of the larger events near longwall faces on the Carbon leader reef is preceded for some hours by an increased rate of microseismic emission and spatial concentration of the microseismic events in the zone of eventual failure. The research is currently being expanded with the aim of producing a practical rockburst early-warning system.

Jan 1, 1983

By C. J. Van Niekerk, C. C. Begley

SYNOPSIS The paper opens with brief descriptions of the history, occurrence, and regional geology of South Afri¬can zinc deposits, and follows with descriptions of the resources, mining methods, and processes for the concentration of the sulphide minerals and the extraction of zinc as practised in South Africa. The end uses in the form of alloys or as salts are given in some detail. Statistics on the production and consumption of zinc in South Africa are given, and the current market situation and future prospects are discussed briefly.

Jan 1, 1991

By P. J. Kinver

The paper presents details of the costs and outputs being achieved by South African mechanized tunneling and stoping drillings. The information was gathered from various hard-rock mining and tunneling operations ranging from deep-level gold mines to shallow base-metal mines. The survey included older pneumatic rigs and the newer electro-hydraulic rigs, but excluded shaft drilling and the stope drillings that were developed recently for narrow reefs. The information presented is intended as a guide to those having to decide whether to use mechanized drillings and, if so, what type and quantity

Jan 1, 1990

From a consideration of the functional requirements of a stope-support pack, simple design principles were developed. The material and dimensional properties of the different components of the pack were determined from a series of laboratory tests. The most important requirement for an adequate pack is that the cushioning layers of timber between the concrete brick layers should provide sufficient transverse reinforcement. The tendency of the compressed timber to creep is shown to be a serious limitation to pack performance and must therefore be an important consideration in the overall design of supports.

Jan 1, 1978

By D. R. Hardman

Coal mining has been practised in South Africa for over one hundred years. The total production increased gradually in the early pat of the twentieth century, but over the past twenty years the rate of growth has been considerable. Although opencast mining has contributed largely to this increase in production in recent years, underground bordand- pillar operations still contribute slightly less than 50 per cent of the total production. The paper highlights problems arising from old bord-and-pillar workings, and an indication is given of how some of the problems have been addressed.

Jan 1, 1990

By P. R. Jochens, D. D. Howat, R. B. Atmore

INTRODUCTION The Miller chlorination process has assumed a preeminent position in the refining of gold bullion, a position it has maintained for over half a century. In the early sixties considerable interest was aroused by the idea of producing a consistently high grade bullion at the mine smelthouses themselves. However, as the use of chlorine in industrial plants is associated with considerable hazards, oxygen was considered a natural alternative, apart from bing less expensive than chlorine. Partial refining at the mine smelthouses would considerably decrease the requirements made on Rand Refinery Limited as well as indicating the possibility of reducing final refining costs. An added factor would be the purer silver chloride obtainable, after prior removal of the base metals by oxygen injection, which would facilitate the production of high-purity silver. The free energies of formation of the oxides of the metals;- silver, copper, lead, zinc, iron and bismuth indicate that, with the exception of silver, these metals should be capable of removal as oxides by oxygen injection. Rose1 had shown that during injection of gold bullion, considerable loss of silver to the boraxsilver slag occurred and, furthermore, that copper removal was not efficient and oxide attack on the refractories was severe. Plant test work2 had confirmed the difficulty of copper removal, but had shown that zinc and lead were almost completely removed. The difficulty of copper removal by oxygen injection warranted further investigation. Also, the high decomposition pressure of silver oxide suggested that by suitable control of the slag composition it might be possible to reduce to very small proportions the silver carried into the slag as oxide. The oxidation of copper by oxygen injection and subsequent dissolution of the oxide in a slag may occur according to the following reactions; Reactions 4 and 5 were considered because of the relatively high solubility of oxygen in molten silver and silver alloys. Thermodynamic data indicate that there is little possibility of any reaction involving the formation of CuO occurring at temperatures above 1 000 °C. To ensure that the operative reactions 1 and 4 take place to the maximum extent, the following factors He significant. (a) an increase in the activity of the copper in the bullion, (b) an increase in the partial pressure of oxygen in the system, (c) an increase in the activity of the oxygen in solution in the metal, (d) a decrease in the activity of cuprous oxide in the slag. From practical considerations, the operative variable most easily susceptible to control is the composition of the slag. SOLUBILITY OF COPPER OXIDES IN BOROSILICATE SLAGS Very scanty information exists on systems containing copper oxides but the indications are that slags containing considerable amounts of boric oxide would possibly prove to be the best solvents for cuprous and cupric oxides. This is attributed to the fact that the activities of copper oxides are much lower in boric oxide slags than in slags in which silica is the main network former. The number of possible slags containing boric oxide was limited by consideration of liquidus temperature, viscosity, corrosive action on refractories, volatilization, and ultimately cost (for industrial application). Slags in the systems soda-boric oxide-silica and lime-boric oxide-silica were selected paying due attention to the above limitations. Additions of 5, 10 and 15 per cent cupric oxide were made to the finely ground, premelted slags. These mixtures were then reground and 2g quantities held in re crystallized alumina crucibles at temperatures of 1150°C and 1 250°C respectively for 30 minutes. The crucibles were removed from the furnace, rapidly cooled, cut in half longitudinally, and a thin section taken from one half was subjected to microscopic examination.

By D. A. Viljoen

While coal can be used as a chemical feedstock instead of oil for the production of the petrochemical based commodities that are so important to our modern way of life, the impact that coal is going to make on the world-energy scene is without doubt its more important role in the short- to medium-term. After inflation, energy is probably today's most talked-about and controversial economic issue. It is a plentiful supply of energy that has permitted each of us to live a life of convenience that is matched only by the most fortunate of the aristocracy in history.

Jan 1, 1979

For many of us, formal academic education slows abruptly when we leave a tertiary institute of learning. We start applying and connecting newly acquired knowledge with the practicalities of a career, and begin to think in a manner that is technology-oriented. Subsequent vocational advancement is offered by the .many mining and professional journals that circulate through departments, and by conferences and schools that are organized in-house and via the SAIMM and other professional institutions. The importance of these schools cannot be overstated: they combine people and developing technology to the benefit of the industry as a whole.

Jan 1, 1992

By H. E. James

The 13th Congress of the Council of Mining and Metallurgical Institutions (CMMI) was held in Singapore from 11th to 16th May, 1986. Tours to Australia, Malaysia, Thailand, South Korea, and Japan took place the week before and the week after the Congress. Registrations By far the largest contingents at the Congress were from Australia (157 delegates and 65 affiliates) and South Africa (127 delegates and 99 affiliates). The other 25 countries represented at the Congress accounted for 118 delegates and 37 affiliates. Thus the total registrations amounted to 402 delegates and 201 affiliates.

Jan 1, 1986

By L. Dison

This technical note is issued in two parts, as follows: Part I, after a brief introduction, discusses the value of patents and the law of patents, including patent applications and the exploitation of inventions. This is followed by some comments for the benefit of would-be inventors and potential users of patents. Part II, which will appear in the February issue of this Journal, focuses on the mining industry and then discusses views on patents that were Quoted in Part I. The last section makes recommendations as to how II1ventors and users (including mining authorities) should handle patents.

Jan 1, 1992

By deur J. V. D. M. Grimes

Sishen Iron Ore Mine is one of the largest open-pit mines in the world, and loading and hauling constitutes one of the major cost items on the mine. Because high productivity in loading and hauling results in large financial benefits, the following projects to improve productivity were implemented at Sishen: - a computerized truck-allocation system, - an overhead power-supply system for the dieselelectric driven rear-dump trucks, - an in-pit crusher and a belt-conveyor system. This paper concentrates on the truck-allocation system, with special reference to the improved productivity of loading and hauling resulting from the implementation of this system.

Jan 1, 1984

Introduction and Background For many years people were aware of the vast deposits of titaniferous magnetite containing vanadium in the Bushveld Complex. From 1957 onwards some exploitation of this ore was carried out by Minerals Engineering of S.A. (later the Vantra Division of Highveld Steel and Vanadium Corporation Limited), who produced vanadium pentoxide via a roast-leach process. Canadian Institute of Mining and Metallurgy The Finance and Executive Committees of the Canadian Institute of Mining and Metallurgy have agreed that members of SAIMM should be invited to register at all future CIM meetings at the same rate as CIM members.

Jan 1, 1980

By R. P. King

An Analytical Solution to the Batch comminution Equation R. P. King, Pr. Eng., B.Sc. (Eng.), M. Se. (Eng.), Ph.D. (Visitor). An analytical solution to the batch-grinding equation is presented in terms of the generalized hypergeometric series and the confluent hypergeometnc function. This solution is valid for selection functions that are describe~ piece-wise by functional forms of the type KOXB and by normalized breakage functions of the type B(x,x') = (x/x')x. These functional forms are sufficiently general to Include most practical cases. In particular, they can be used to describe selection functions that have a maximum.

By R. T. White, A. Higginson, M. Phil

Samples of water that had been collected underground from eight gold mines in South Africa were subjected comprehensive analysis of the quality of the waters, and their corrosivity on mild steel was measured by the laboratory techniques of extrapolation from Tafel plots and of polarization resistance. The results indicate that, if such factors as pH, Langelier index, and degree of aeration are beyond certain specified limits, the corrosivity ofthe water is affected. The applicability of the corrosivity index in predictions ofthe degree corrosion is questioned. Suggestions are included for future work involving the fundamental characterization of the corrosivity of mine waters.

Jan 1, 1983