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By P. J. D. Lloyd

An account is given of the development of a process to concentrate gold and other valuable minerals and to produce a discardable waste. In this process, the ore is coarsely milled, a bulk flotation concentrate is prepared, and the flotation tailing is scavenged in a hydrocyclone, which returns coarse gangue, moderately coarse valuable minerals, and locked valuable minerals back to the mill. The engineering developments required by this circuit in order that it will fit underground, and the progress made towards the achievement of those requirements, are reviewed. If the waste is to be suitable for use as a backfill in a deep-level, flat tabular excavation, it should be capable of being placed hydraulically, and should have both low voidage and high rates of drainage. Such a material could be prepared by the fine screening of the overflow from the cyclone in the proposed circuit. Possible methods for the handling of the concentrate and the recovery of its valuable constituents are described. The paper concludes with a discussion of the possible benefits from the use, in deep-level Witwatersrand mines, of a system involving concentration underground, extensive backfilling using the tailings from the concentration process, and hydraulic hoisting of the concentrate.

Jan 1, 1979

By A. N. Brown

The importance of the minerals industry in the economy of the country is discussed, and the tremendous changes that have taken place over the past two decades, including the widespread application of computers and the use of mechanization, are outlined. A discussion of the future of the minerals industry points out that, with the rise in the price of gold, the life of the gold-mining industry can be expected to extend beyond that previously predicted, and that the demand for uranium, which has been depressed, is uncertain. As a result of the oil crisis, the demand for coal has increased and large expansion programmes are planned. These involve coal exports and the use of coal for the generation of electric power, for the production of liquid fuels, and for the smelting of metals. Technical challenges face engineers in every avenue of the minerals industry: in deep gold mines, underground coal mines, strip coal mines, and open-pit mines. Studies indicate that only one-third of the demand for trained mining and metallurgical engineers is being met and that the position is worsening. However, there are indications that the industry is succeeding in attracting more engineering students, and the supply is expected to improve. These efforts should be co-ordinated, expanded, and intensified. There is a need to ensure that sufficient teaching staff of the right calibre and experience are attracted to universities and technikons. The first degree course is comprehensive and basic, and specialization through post-graduate study should be encouraged. The influence of national service on the education and training of engineers is discussed.

Jan 1, 1982

By J. O. Jensen

A method is described for the determination of cyanide in gold slurries, based on amperometry. The measured current is proportional to the concentration of cyanide, and is not effected by pH or by the concentration of oxygen in solution. It is also unaffected by other ions that may be present in gold-leaching solutions, including sulphide, thiocyanate, and thiosulphate. The current depends on the temperature, and an activation energy of 17,9 kJ/mol was determined Since the current is controlled by the mass transfer of cyanide to the anode, it depends on the conditions of agitation. In tests on an operational gold plant, slurry was pumped directly from the top of the leaching tank, through the measuring cell and back into the tank. The results indicate that the instrument is a promising alternative to the instruments currently available. The readings from the instrument remained in calibration for at least two days, showing that the instrument would need to be re-calibrated by the operating staff at regular periods.

Jan 1, 1994

By E. Adlard

This paper sketches an expert system for use underground in pinpointing problem areas in the operation of machines. The system is typically a software 'shell' designed to accommodate a series of 'if-then' rules that are intertinked to systematically search for the cause of the problem. During the search, the system asks a series of questions that have to be answered by the operator and then, when necessary, by an artisan. The rules of the system are generated by a knowledge engineer whose function it is to gather the necessary diagnostic information and prepare it in the required format for the expert system. Much still requires to be done in the development of such systems and in the testing of hardware to withstand the mining environment.

Jan 1, 1990

By M. Splaine, W. Davidson, D. C. Atkinson

Since 1964, Nchanga Consolidated Copper Mines, Ltd., has been developing and using production scheduling methods for optimizing its metallurgical operations in the short term (up to one year). Medium-range metallurgical planning has been possible only by successive evaluations of a single-year LP. A modified version of Rosenbrock's direct search technique has now been developed to allow multi-year optimization of both mining and metallurgy for medium-range planning. The modifications to the search technique have produced a marked increase in computational efficiency for this heavily constrained problem in many variables and the system is a usable planning tool, given a reasonably powerful computer. The plans are 'optimum' in the sense that they yield the maximum present value of the operations. Each of the resulting five-yearly mine plans forms the basis for further detailed metallurgical evaluation by the established production scheduling system.

By A. J. S. Benade, A. J. A. Heyns, N. B. Strydom

The maximum oxygen intakes of samples of about 30 Bantu, weighing less than 50 kg from different tribal groups (Zulu, Xhosa, Sotho and Shangaan) were measured on a treadmill. The mean maximum oxygen intake of the 164 men was 2,12 litresjmin and only 18 men (11 per cent of the sample) had maximum oxygen intakes of 2,5 litres/min or above (the minimum requirement for such tasks as shovelling rocks and tramming it). The samples of the different tribes differ in age, but when the age effect is taken into account then there were no significant differences between tribes in maximum oxygen intakes. An incidental finding was that both age and body weight correlated significantly with the maximum oxygen intakes of these underweight subjects. Not one of the subjects who weighed less than 45 kg or who was older than 40 years had maximum oxygen intakes high enough to permit their being able to do strenuous work underground. It is clear therefore that Bantu who weigh less than 45 kg or are older than 40 years should not be employed on such strenuous tasks as shovelling rock and tramming it.

By J. A. C. Diering

All underground openings are three-dimensional, and in many cases it is not valid to analyse two-dimensional sections. This has been a problem in the past owing to the magnitude and complexity of three-dimensional stress analysis. In this paper a three-dimensional boundary element approach, using non-conforming quadratic elements, which is specifically applicable to underground excavations, is described. In addition, the philosophy of application of stress analyses is discussed. Three case histories are presented to demonstrate the practical nature of the approach as a tool in solving mining problems.

Jan 1, 1987

Commissioning of the Cannington processing plant began in October 1997. The nameplate capacity (of 1.55 million tonnes of ore per annum) was achieved relatively quickly. Since then (like many mines) the operation has strived to increase throughput and improve valuable metal recoveries, to offset declining head grades and lift the value of the operation. The processing plant now has the capability of treating over 3.2 million tonnes of ore per annum and in financial year 2005/06 the combined concentrate production exceeded 600 000 wet tonnes, approximately 80 per cent above concentrate output in the first full year of operation (at the design feed rate). This improved performance was achieved by making changes and additions to each of the major unit processes - primary grinding, flotation, leaching, filtering and paste fill preparation. The changes have included: adding a fines flotation circuit, expanding the grinding circuit, adding a pebble crusher, switching from continuous to batch leaching, building paste conveyors and decommissioning the column flotation cleaning circuits. This paper reviews these changes, outlines the current operating practices and discusses the challenges or opportunities that remain.

Jan 1, 2007

The 96th Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room of the Transvaal Automobile Club in Johannesburg on Wednesday, 11th August, 1993. OBITUARIES The President announced the deaths of the following members of the Institute during the past year. Life Fellow E.F. Laschinger. Other Members R.K. Boright, J.S. Jacobi, R.D. Power, J.H. Cannon, C.J. du Plooy, L.B. Mcrae, C.P. Rossouw, A.L. Sillars, A.W. Heugh, R.K. Briggs, P.J. Stark, and C.S. Stott. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1993

By J. P. M. Hojem, C. Dimitriou, N. C. Joughin

This paper describes the design and construction of the first experimental underground rockcutting machine from measurements of cutting forces determined in tests on small rock specimens in the workshop. The deficiencies of this design, revealed by stoping with almost identical rockcutting machines, are described. An account is given of the design and construction of further experimental machines incorporating substantial improvements which made them technically feasible for use in production.

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 E. J. Boome, A. C. Schmidt

Pert, and how Pert techniques can be used in modern mine management By E. J. Boome, A. C. Schmidt C.A. (S.A.) This paper covers the stages of planning required to be performed and the implementation of the plan from grass roots to the partial completion of the sinking of a mine shaft system. The various steps involved in the planning are also examined in some detail. The experience gained in this project and the conclusions reached convince the authors that Pert Planning is a valuable aid to top management.

Notices COMPETITION FOR STUDENT MEMBERS OF THE SOUTH AFRICAN INSTITUTE OF MINING AND METALLURGY Each year the Institute offers a prize (or prizes should the entries warrant it) of up to RlOO for the best paper or dissertation on a topic appropriate to the interests of the Institute. The competition is open to all Student Members of the Institute. APPLICATION AND PRACTICAL OPERATION OF HYDROCYCLONES Dr H. F. Trawinski of Amberger Kaolinwerke, Hirschau, West Germany, gave a very interesting lecture on this subject to an audience of over one hundred, composed largely of members of the Institute, on 15th August, 1973, at the University of the Witwatersrand. ROTARY INTERNATIONAL Applications are invited before 15th March, 1974, for the following awards of The Rotary Foundation: Post-graduate Fellowships Under-graduate Scholarships Awards for Technical Training Awards for Teachers of the Handicapped. NIM REPORTS Report No. 1509 The instrumentation developed for electrochemical studies of the le(Whing of uranium dioxide. Report No. 1550 A fundamental study of the dissolution in (Wid solutions of uranium minerals from South African ores. Report No. 1552 The preparation and analysis of minerals for use as reference material.Progress report No. 2. Report No. 1556 The spectral analysis of solutions.2. The analysis of leach liquors, concentrates, slags, and residues. Report No. 1559 A cost assessment of the production of elemental sulphur by chlorination roasting. Report No. 1562 Application of a flotation model to an industrial plant

Jan 11, 1973

By M. M. Oosterveld

Diamonds are mined from ancient raised beach deposits in southern Namibia where complex geological controls have resulted in patchy diamond distribution, largely related to irregularities (trapsites) in the bedrock. The distribution of the number of diamonds per sample is a discrete, reverse- J shape distribution which can be characterized by two parameters. These parameters have been transformed into a Beta and Theta Contribution which can be interpreted as reflecting the 'quantity' and 'quality' of the trapsites. The relationship of statistical parameters, obtained during the sampling of an ore deposit, to the geology of the deposit is an important element of ore reserve estimation. The large-scale regional trends in the contributions have been explained in terms of the geology.

Jan 1, 1987

By C. Mueller

In many automated mines, multi media video and audio funtionality has to be combined with sensor information or steering commands, which is the idea of a new, PC based integrated and multi media capable control system. The new control system (Multimedia Control - MMC) bases entirely on TCP/IP networking and internet technology. For the first time, this enables the ‘intelligent’ use of video and audio information: pictures and voice sequences may be forwarded on request only, they may be stored if particular events occur (e.g. video black boxes) and sensor signals as well as actions from the automation system can directly be assigned with multi media sequences. MultiMedia Control entirely bases on object oriented software. It uses most modern software technology. As user interface, only a standard web browser is required. This makes the handling of different machines easy. By using mobile web pads, dedicated local operator interfaces are not required any longer. The service staff just connects to the automated equipment by – wireless –LAN to make required adjustments. Customization is easy using an open Application Programming Interface. Software modules may be added to the system without touching or recompiling existing components. The system was prototyped in 2000 using a demo-application. The performance tests showed very positive results both regarding the control system behaviour and the speed/latency timing behaviour of the multi-media information processed. The system now is slightly reshaped to completely meet the final product requirements. It is expected to be available by the end of 2001. Key words: Machine Automation; Control System; Multi Media; Remote Control; Teleoperation; Ethernet; TCP/IP; Internet Technology; Streaming Video; Quality Assurance; Service; Control Centre.

Sep 1, 2001

By K. I. Afewu, L. C. Woollacott

The design of in-pulp adsorption vessels in the gold industry has, for the most part, been seen as a problem involving the suspension of fine particles o ore in a slurry. The need for the vessel to be designed as a mass-transfer contactor has received insufficient attention. The current series of papers addresses this need The previous paper considered the question of the scale dependence of the film transfer coefficient. This paper examines the mixing considerations that are relevant. A review of the literature and an examination of a limited set of data provide some insight into the mixing conditions needed for the dispersion of the particles of adsorbent. The mixing requirements for the suspension of the ore particles are also considered, and conclusions are drawn in regard to the design of mechanically agitated vessels for gold in-pulp adsorption circuits.

Jan 1, 1995

By K. Shin

Determining the anisotropy of rocks has in the past been difficult and rarely attempted in engineering practice. Here we have developed a new practical methodology for measuring orthotropic anisotropy that requires only one hollow cylinder specimen to determine the anisotropy of a set, even when the directions of the anisotropic axes are unknown. Autrefois, la détermination de l’anisotropie des roches était difficile et elle a été rarement essayée dans la pratique de l’ingénierie. Voilà c’est nous qui avons mis au point une nouvelle méthodologie pratique pour mesurer le coefficient de conductibilité thermique de l’anisotropie qui exige un seul spécimen du cylindre creux afin de déterminer l’anisotropie d’une série, même si les directions des axes anisotropiques sont inconnues. Früher war die Bestimmung der Anisotropie von Gesteinen ein schwieriges Verfahren, das in der technologischen Praxis nur selten in Angriff genommen wurde. Wir haben hier eine neue praktische Methodik zur Messung der orthotropen Anisotropie entwickelt, bei der nur ein Hohlzylinder an Gesteinsproben benötigt wird, um die Anisotropie einer Reihe von Steinen zu bestimmen, selbst wenn die Richtungen der Anisotropieachsen unbekannt sind.

Jan 1, 2003

By J. L. Taylor, E. N. Lawson, Hulse. G. A.

It is generally recognized that a large proportion of the gold remaining in the residues from metallurgical plants on the Witwatersrand is occluded in pyrite. The conventional flotation-roasting process typically recovers approximately 40 per cent of this gold. The process described here is an unconventional route involving bacterial oxidation, which can achieve a gold recovery of approximately80 per cent. The paper describes tests carried out in the laboratory, as well as on a slimes dam. The results show that recovery of gold can be noticeably enhanced through the use of bacteria under conditions of controlled pH, moisture, and aeration. Biological oxidation of the pyrite releases the occluded gold, which then becomes amenable cyanidation.

Jan 1, 1990

By J. J. van Vuuren

Pipe-stick support in deep-level gold mines is first described and illustrated, a pipe-stick being a mine pole trimmed to the required size and sleeved by a pipe. An account is then given of an investigation into this form of support that involved load-compression tests in a 1000-ton press, tests in a rapid loading machine simulating rock-burst conditions, a study of the load-compression behaviour of pipesticks installed underground, and a cost evaluation. Pipe-stick support was found to be very effective on the face and to cost less than conventional matpacks.

Jan 1, 1979