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By R. A. Plumbridge

I am deeply honoured by your invitation to address your great Institute on this centenary occasion. Mining is a cyclic industry that continuously faces enormous challenges as it wrests the treasures of the earth from an often reluctant mother nature. Throughout the ages, those challenges have demanded great skill from mining men and women, who are required to blend a mixture of robust determination with art and science. Pioneer Miners and Scientists It is not surprising therefore that the first blush of euphoria surrounding the discovery of gold on the Witwatersrand quickly gave way to consternation about the need to increase the metallurgical recovery of gold from the then readily identifiable conglomerate. The rugged pioneer miners had to turn to scientists for their salvation.

Jan 1, 1994

By P. C. van Aswegen

The Schools A school on 'Measurement, Process Control and Optimization in the Minerals Industry', organized by The South African Institute of Mining and Metallurgy, was presented twice by course leader Dr Ken Garner, ably assisted by the staff of the Measurement and Control Division of Mintek. The first school was held from 16th to 20th July, 1984, at the University of the Witwatersrand, and the second from 11th to 15th February, 1985, at Mintek. Project development The Sydney Branch of the Australasian Institute of Mining and Metallurgy will hold a second Project Development Symposium in Sydney between 7th and 10th October, 1986. This second symposium will extend the range of topics covered by its predecessor in 1983 to emphasize planning (including strategic planning), construction, and project commissioning.

Jan 1, 1985

By T. R. Marrero, J. W. Wilson

The transportation, by water that flows through a pipeline, of coals in the form of water-impermeable cylinders is discussed, and shown to have distinct advantages over other forms of coal transportation, including significantly reduced costs for larger throughputs. The description of the concept comprises various aspects of the system, such as methods for the manufacture of coal logs, their injection into the pipeline, the manner in which they are conveyed in the water in the pipe, and the methods used for their preparation as feed material to electric power stations at the end of the pipeline. It is pointed out that the technology involved in the transportation of coal in the form of logs via pipelines is applicable also to other minerals and commodities.

Jan 1, 1993

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 N. Thorp, S. J. Bluhm

It has long been recognized that the provision of an acceptable thermal environment minimizes the danger and the adverse effect of heat stress, which is directly linked to decreased productivity, increased accident rates, and excessive physiological strain in workmen. Refrigeration in one form or another helps to provide this acceptable thermal environment. This paper outlines the problems encountered in a working area, and the steps taken to alleviate environmental conditions in some stopes with the introduction of selective cooling employing small water-chilling units in conjunction with specially designed stope coolers. Performance figures are given for plant and stope coolers, and the effectiveness of the system is assessed from an evaluation of the improvement achieved in the environmental conditions.

Jan 1, 1986

By J. N. van de Merwe

CONTRIBUTION BYH. WAGNER AND T.T. OZAN The paper by Dr J.N. van der Merwe makes an important contribution to the design of bord-and-pillar workings in the Vaal basin. It has been recognised for some time that the strength of coal seams in the Vaal basin is markedly lower than that of coal seams in other coal-mining districts in South Africa. However, there was insufficient data to quantify how much weaker the extensively jointed coal the Vaal basin is. A number of recent pillar collapses that occurred at Sigma colliery, the only remaining underground colliery in the Vaal basin, provided Dr Van der Merwe with an opportunity to make this assessment.

Jan 1, 1993

By L. C. Woollacott

Some of the factors that may influence the reliability of a consistent material balance derived from plant data were investigated, data taken from a sampling of the Iow-grade tin-flotation circuit at Rooiberg A Mine being used as the basis for the investigation. The importance of subjecting a calculated balance to a thorough analysis of its sensitivity to erors in assay and flow rate measurements is highlighted. Several simple guidelines are derived from the analysis of the Rooiberg data, and these appear to be generaly applicable to process-evaluation exercises and to the technique used for the smoothing of material balances.

Jan 1, 1987

By A. G. W. Knock

Logistic curves are used in the prediction of the primary production of tin metal from estimated worldwide resources. Such curves are asymptotic to the total cumulative reserves, which are a function of prevailing metal prices and total resources. The figures for tin resources are based on the findings of Robertson and of Brobst and Pratt, the latter authors including estimates of undiscovered deposits. It is suggested that tin production will slump from the present level to 100000 long tons per annum by the end of the century, but will reach a new peak of 200 000 long tons some thirty years later. It appears that production will never exceed 300000 long tons per annum unless substantial new resources, excluding those predicted, are discovered.

Jan 1, 1979

By D. E. Scheck

A computer-aided blast design consultant system has been developed. The software consists of two modules: one uses theoretical and empirical formulae and procedures to design a blast based on user supplied geological and mechanical data, while the other is an expert system that analyzes blast vibration problems and recommends remedial action using knowledge based rules. The system is currently undergoing field evaluation.

Jan 1, 1987

By R. D. C. Shone

Consideration is given to the technical and economic feasibility of freeze desalination as a technique for the simultaneous provision of ice to cool deep mines and for the desalination of mine water. Freeze desalination has not been developed fully or commercially. For sea-water applications, it may not offer significant advantages over other methods of desalination but, for the unique mining application, a single dual purpose plant that produces desalinated ice could offer significant cost savings over combinations of separate desalinators and ice-makers. The current status 01 freeze desalination is reviewed, and the important aspects relating to mines are discussed. Some freezing processes that could be suitably modified are described. The possible use of conventional ice-making machines for desalinating mine water is also discussed.

Jan 1, 1987

By R. Hemp

The first part of this paper describes the collection of barometric pressure measurements in a mine and their statistical analysis, which shows the effect of variations in barometric pressure, both on the primary emissions of methane gas into the workings (whether from fissures or from the surrounding strata), and on the flow of air to and from large unventilated, or poorly ventilated, areas. The second part of the paper deals with a study, based on computer simulations, of leakage flows of air into and out of sealed areas, and the reduction of such flows by the use of adequate seals.

Jan 1, 1994

It is shown that, when a flat-bottomed indentor is pressed into the surface of a strong rock, the normal force necessary to cause failure of the rock is reduced substantially if a shear force is applied to the indentor. A mathematical analysis is described, which shows that higher stresses are induced in an elastic material close to the free surface of the material ahead of a punch when a shear force together with a normal force is applied to the punch. Therefore, failure of the material would occur with lower forces applied to the punch. Stress trajectories show that fractures develop in the rock along lines of maximum principal stresses.

Jan 1, 1978

By P. Kohler, T. D. Sampson, T. H. Tunley

The Metsep Process for the separation and recovery of zinc, iron, and hydrochloric acid from spent pickle liquors by T. H. TUNLEY, B.Sc. (Ch em. Eng.) (Visitor), P. KOHLER (Visitor), and T. D. SAMPSON, Pr. Eng., B.Sc. (Chem. Eng.), B.Econ. (Visitor) A spray roaster has been installed in the Johannesburg area for the treatment of spent liquors from a variety of small pickling operations. A new process was developed for the processing of the liquor that is contaminated with zinc chloride, and a commercial plant was built incorporating this process. An ionexchange plant separates the zinc from the iron chloride, and a liquid-liquid-extraction plant converts the zinc chloride to zinc sulphate and recovers the hydrochloric acid.

Jan 5, 1976

By N. C. Joughin, H. Wagner

Research is a business activity, and is as different from other business activities as banking is from mining. attempting to use research to solve their problems, managers do not always recognize its unique features, are frequently disillusioned with the outcome. With a view to enabling managers to use research more effectively, an outline is given of the features of research as applied to mining. Types of research are distinguished, and stages in the research-and-development process are identified. The time-scales and resource requirements of the various types and phases of research are explained. Examples of research that have reached implementation in gold mining are given to illustrate the features mentioned. Practical and economic considerations are discussed, and pitfals and recommendations in the use of research are highlighted.

Jan 1, 1989

By M. J. Southwood

SYNOPSIS Experiments carried out under atmospheric pressure and temperature (25°C) and sterile conditions show that the dissolution rate of nickel and copper from a pyrrhotite-pentlandite-chalcopyrite ore in a lixiviant of sulphuric acid is greatly enhanced in the presence of pyrite. At a pH value of 1,8 and in the presence of pyrite of equal mass to that of the ore, the recoveries of nickel and copper improved dramatically (21 and 80 per cent respectively). At a pH value of 4,0 the recovery of nickel was enhanced, but the chalcopyrite was refractory. A galvanic mechanism is probable, but cannot be proved from these experiments. The economic implications of the results are discussed.

Jan 1, 1985

By R. G. B. Pickering, H. H. Haase

CONTRIBUTION BY D. O'CONNOR Mechanical extraction of rock has been a goal sought after for some decades in the South African gold-mining industry. There are factors distinct from the mode of mechanical extraction that may have considerable influence on its prospects for extensive adoption; the rockburst factor is one of these. REPLY BY H.H. HAASE AND R.G.B PICKERING We agree with Professor O'Connor that, in conventional gold-mining operations, a disproportionate number of seismic events occur in the period immediately following a blast; rockburst activity follows the same pattern, and it has been calculated that, if the rockburst peak were spread evenly across the day, the rockburst exposure of stope workers would nearly double.

Jan 1, 1992

By H. J. E. Hamel

Some aspects of the deformation behaviour and temperature rise during instantaneous compression loading of high purity aluminium By H. J. E. HAMEL The influence of deformation speed on the deformation behaviour of high purity aluminium was investigated. By varying the initial height-to-diameter ratio a considerable influence on the deformation behaviour could be noticed. Lubrication of the specimen end faces was found to have an influence on the flow behaviour and on the roughness of the specimen interface at pressing platens. The results of temperature measurements during deformation agree with work-hardening behaviour of the specimens. Flow curves calculated with the measured temperature rises do not agree with results obtained at lower strains by other workers. The possible reasons are discussed.

By J. D. Austin, D. G. Kringe

Rates of return realized on investments in the gold mines of the newer goldfields outside the Witwatersrand were calculated and analysed over various time intervals and on various bases. It is shown that these rates of return are strongly correlated with changes in the gold price and cannot be equated with the returns that are expected when investments are made, and that the changes in gold price also affect the rates of return on the Johannesburg Stock Exchange as a whole. These correlations are used, together with a limited application of the Capital Asset Pricing Model, to suggest the expected levels of threshold returns in real terms for new mining projects, for projects on existing mines, and for share valuations.

Jan 1, 1980

By G. R. Marchant, B. K. Loveday

A mathematical model has been developed for flotation circuit simulation. This model was designed to investigate the effect of varying the circulating loads and to determine whether an improvement in overall efficiency could be gained by a size separation prior to flotation. Model parameters were obtained by regression to plant data. Highly correlated parameters in the model were combined to reduce the number of parameters so that the need for excessive data gathering was eliminated. Mass balance smoothing was used to obtain a consistent data set for regression. The results of the simulation indicate that for the same grade of concentrate, an increase in copper recovery of 0.6 per cent may be possible by increasing the circulating loads. The results of the simulation also indicated that recleaning of the plus 200-mesh material may be beneficial.

By P. J. D. Lloyd

The Witwatersrand reefs contain gold, uranium, and pyrite in the following average concentrations: 0,001 per cent, 0,02 per cent, and 1,7 per cent respectively. The paper discusses the flotation of pyrite to produce a s,ulphide concentrate, reviews work done on the production of gold concentrates, discusses attempts to produce maximum concentrates, and closes with a review of processes for the simultaneous flotation of these three species. It is concluded that high recoveries of all three species can be achieved only if a rougher concentrate of perhaps 20 per cent of the feed (by mass) IS produced, and it is suggested that reverse leaching (leaching before cyanidation) of this concentrate, followed by a cleaning flotation step for the recovery of the pyrite, would be more efficient than the routes employed at present.

Jan 1, 1981