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Tests were carried out in a Hallimond microflotation cell and a Denver D12 cell on typical residue material from a gold mine in the Orange Free State (South Africa), in which 50 per cent of the kerogen was larger than 100 µm in size. Although kerogen is naturally hydrophobic, the observed unexpectedly poor flotation reponse may be due to occlusion of the kerogen by a slime coating and subsequent depression of the slime by guar gums. The recovery of gold from samples spiked with kerogen increased, with no significant reduction in grades, when a petroleum-based collector and tetrasodiumpyrophosphate (a dispersant) were used.

Jan 1, 1985

Frank Michael Gowar Egerton was educated at Jeppe High School for Boys and the University of the Witwatersrand, both in Johannesburg. He holds a B.Sc. degree in mining engineering, and has attended numerous courses on management, finance, and industrial relations. In the Executive Development Programme run by the University's Business School in 1981, he was voted the student who had made the greatest contribution to the programme.

Jan 1, 1993

By R. G. B. Pickering

Conventional mining is an excellent match of mining method and equipment. The result is guaranteed performance. Change in the form of different technology requires change in mining method until the best match is achieved. This paper covers the development of technology and mining method that has occurred in the last five years to arrive at the objective of successful mechanized mining in narrow reef platinum deposits of the Bushveld Complex.

Jan 1, 2004

By R. Hemp

This paper describes in broad outline the development of a computer programme for determining the effects of changes in various factors in the condenser water circuit on the operation of a cooling plant. The programme is used to obtain design figures which result in minimum total power consumption. This was done for a range of different upcast air quantities, and the implications of low air quantities for heat rejection are discussed.

By M. H. M. von Wielligh

"Brick manufacturers supply a variety of uniquely coloured facebricks to the building industry, which requires a high level of colour consistency in the products. Colour variation in bricks is influenced by the composition and consistency of the white clay raw material. By blending varieties of naturally occurring white clay the manufacturers produce a unique range of facebrick products. Homogeneity of the white clay raw materials mined at Lenasia is crucial for producing bricks of consistent colour. Geostatistical investigations of the major element distributions (SiO2, Al2O3, Fe2O3, and K2O) and loss on ignition (LoI) were conducted. An analysis of the spatial continuity of these variables followed by ordinary kriging indicated that the upper white clay layer at Lenasia is richer in K2O and Fe2O3 than the lower layer. Consistency in the colour of facebricks depends critically on careful management of the variability in the K2O and Fe2O3 content of the clays. The geostatistical approach to understanding the distribution of elements in the clay allows miners to construct clay stockpiles of consistent quality for feeding the brick-making process. Geostatistical investigation of the chemical contents in other clay domains within the deposit is recommended, and could be extended to all facebrick manufacturers to assist in improving the colour consistency of their products. IntroductionMost clay in South Africa is used in the manufacturing of tiles, pipes, bricks, whiteware, refractories, and pottery. Bricks are manufactured from a wide variety of clay types, the behaviour of which during firing depends critically on the the clay mineralogy and chemical composition, but this relationship not well understood (Stein, 1982). The variety among clay deposits is related to the different processes of formation (Deer, Howie, and Zussman, 1992). The geochemical composition of the clay can vary between layers and within the same layer in an individual deposit (Lurie, 1984). The properties of clay minerals are determined by their structures and the different combinations of silicate layers, cations, and hydroxyl ions (Kingery, Bowen, and Uhlmann, 1976). South African clays can be classified as either kaolinite or montmorillonite and are seldom found in a pure form (Lurie, 1984). Different clay minerals affect the drying, forming, firing behaviour, colour, and quality of the brick product in different ways. Laboratory tests (full physical analysis) can indicate the suitability of a clay for the manufacture of ceramic products. The minerals most essential for the manufacturing of clay brick products are kaolinite, illite, and quartz (Stein, 1982)."

Jan 1, 2017

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements set out on pages 272 to 277. These financial statements are the responsibility of the Institute's Council. Our responsibility is to report on these financial statements. We have conducted our audit in accordance with generally accepted auditing standards. These standards require that we plan and perform the audit to obtain reasonable assurance that, in all material respects, fair presentation is achieved in the financial statements. The audit included an evaluation of the appropriateness of the accounting policies, an examination, on a test basis, of evidence that supports the amounts and disclosures included in the financial statements, an assessment of the reasonableness of significant estimates, and a consideration of the appropri¬ateness of the overall financial statement presentation. We consider that our auditing procedures were appropriate in the circumstances to enable us to express our opinion presented here. In our opinion these financial statements fairly present the financial position of the Institute at 30th June, 1996, and the results of its operations for the year then ended in conformity with generally accepted accounting practice.

Jan 1, 1996

Report of the independent auditors To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements set out on pages 251 to 257. These financial statements are the responsibility of the institute's Council. Our responsibility is to report on these financial statements. We have conducted our audit in accordance with generally accepted auditing standards. These standards require that we plan and perform the audit to obtain reasonable assurance that, in all material respects, fair presentation is achieved in the financial statements. The audit included an evaluation of the appropriateness of the accounting policies, an examination, on a test basis, of evidence that supports the amounts and disclosures included in the financial statements, an assessment of the reasonableness of significant estimates, and a consideration of the appropri¬ateness of the overall financial statement presentation. We consider that our auditing procedures were appropriate in the circumstances to enable us to express our opinion presented here. In our opinion these financial statements fairly present the financial position of the institute at 30th June, 1998, and the results of its operations for the year then ended in conformity with generally accepted accounting practice.

Jan 1, 1985

By P. N. Harris

On 23rd November, 1982, a party of 80 members of The South African Institute of Mining and Metallurgy left the Wanderers Club grounds at 07hOO, and were driven in two luxury coaches to the stainless-steel mill of Southern Cross at Middelburg. Southern Cross is a trade name adopted by MS & A (Middelburg Steel and Alloys), who operate two Alloy Divisions (at Middelburg and Krugersdorp) and one Steel Division (at Middelburg). METAL '83 The International Precious Metals Institute has scheduled a seminar on the platinum -group metals for Williamsburg, DB.A., on 10th to 13th April, 1983, and has announced its keynote speakers for each of the seminar's five sessions. Metee '83 METEC - the International Exhibition for Metallurgical Technology and Equipment with Congress - which was to have been held in Dusseldorf from 14th to 20th May, 1983, has been cancelled, and will probably take place in June 1984. Sampling Sampling and sample preparation are crucial activities in many areas of chemical engineering, in the energy and food industries, in metallurgical processes, and in mining and mineral engineering.

Jan 1, 1983

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements set out on pages 251 to 257. These financial statements are the responsibility of the institute's Council. Our responsibility is to report on these financial statements. We have conducted our audit in accordance with generally accepted auditing standards. These standards require that we plan and perform the audit to obtain reasonable assurance that, in all material respects, fair presentation is achieved in the financial statements. The audit included an evaluation of the appropriateness of the accounting policies, an examination, on a test basis, of evidence that supports the amounts and disclosures included in the financial statements, an assessment of the reasonableness of significant estimates, and a consideration of the appropri¬ateness of the overall financial statement presentation. We consider that our auditing procedures were appropriate in the circumstances to enable us to express our opinion presented here. In our opinion these financial statements fairly present the financial position of the institute at 30th June, 1998, and the results of its operations for the year then ended in conformity with generally accepted accounting practice.

Jan 1, 1998

Book news 1. Book reviews ? Prospecting in areas of desert terrain. London, The Institution of Mining and Metallurgy, 1985. 283 pp. £28 (members £25,20). Reviewer: J.S. Mostert This publication records the proceedings of a con¬ference convened to deal exclusively with prospecting in areas of desert terrain. The meeting, organized jointly by The Institution of Mining and Metallurgy (London) and the Ministry of Energy and Mines, Morocco, was held in Rabat from 14th to 17th April, 1985, and generated considerable international interest. Exploration cam¬paigns and case studies of successful discoveries in the desert areas of more than 14 lands are described. Since large areas of South Africa, Botswana, and Namibia are characterized by and and semi-arid terrains, this publication should be of considerable interest to explorationists and mining engineers engaged in the search for and development of mineral deposits in southern Africa. The fact that the desert terrains of southern Africa are host to a number of important base-metal (Aggeneys, Gamsberg, Prieska, and O'Okiep) and diamond deposits (Orapa, Jwaneng) has ensured continued interest in these areas from the viewpoints of exploration and mining.

Jan 1, 1985

Contribution by G. Narsimhan It was with much pleasure that I went through D.F. Malan's excellent paper. The following explanatory and critical note has been the result of my deep study of the paper. Although by qualifications and experience I have been a chemical engineer, involved over four decades with problems in the modeling and simulation of transport-limited (heat and mass) chemical reactions in multi-phase systems, I have of and on interested myself in challenging problems in extractive metallurgy. This is the first time I have veered of to continuum mechanics, at the age of 71! Author's reply. I thank Professor Narsimhan for his extensive contribution to the paper. It provided me with the stimulus to derive an extended model. However, there are some inaccuracies in his arguments that need further discussion. Professor Narsimhan's main concern is that there is not a good enough fit between the derived viscoelastic Kelvin model and the experimental data supplied by Güler1 (see Figure l1 on page 218 of my paper). I will therefore explain the choice of a viscoelastic model in more detail and also make specific comments on the arguments given in his contribution.

Jan 1, 1996

By M. I. Brittan

SYNOPSIS The key reactions of the copper segregation process have been studied with a view to establishing the kinetics of the system. The investigation was carried out using two refractory copper ores from the Zambian Copperbelt in a small-scale, fluidized bed, chloridization reactor. The rate of chloridization of the copper in the ores is compared with the rate of volatilization of the cuprous chloride produced and with the rate of reduction of the cuprous chloride to form segregated metallic copper. In conjunction with available data on the rate of production of hydrogen chloride in a segregation system and with due regard to the conditions applicable in a TORCO reactor, it is concluded that the chloridization reaction is the major rate limiting step of the process. Factors influencing the rate of this extraction step and aspects of its mechanism are examined. The findings have confirmed the validity of the existing theory of segregation and provide insight as to the viability of the system of reactions involved in the copper segregation phenomenon. Experimental results which relate to observations made in the course of TORCO plant operation and segregation studies are discussed.

By H. A. D. Kirsten

The effects of the mining of deep-level tabular reefs are usually evaluated by use of continuum, elastic mining simulation analyses. This paper gives the results obtained from a series of analyses in which stopes of limited span are considered to be excavated in a non-linearly non-elastic, jointed and fractured rockmass. In particular, the theoretical influence of soft backfill in these conditions is evaluated. It is shown that the stress distribution and behaviour of the rockmass, alternately taken as an intact-elastic and as a fractured non-elastic medium, are completely different. The relevance of the energy-release rate commonly calculated in mining-simulation analyses, and the efficacy of its correlation with seismicity and the associated rockbursts, are reviewed. In deep-level mining operations, it is not practically feasible to obviate releases of seismic energy. The fact of their occurrence should therefore be accepted and, rather than considering the reduction of energy release as the primary objective, efforts should be concentrated on minimizing the effects of such release. Analytical results are given to demonstrate that this approach is not only correct, but also the only feasible solution to the rockburst-seismicity problem in deep mines.

Jan 1, 1989

By P. van Niekerk, V. J. Solomon

Improvements in the drilling and blasting techniques used in the stopes of narrow reefs have caused the clearing of broken rock to become the major cause of delay in the achievement of a regular cyclic operation. This paper discusses the development of a scoop in accordance with a predetermined set of performance parameters. The test results obtained to date have shown that the basic objectives have been achieved within tolerable limits of variation.

Jan 1, 1979

Measurements of the rates of penetration at various throttle air pressures are presented as a function of thrust for three different rockdrills when drilling quartzites with strengths of 45 000 lb/in2 and 39 000 lb/in2, The rate of penetration at optimum thrust is shown to agree well with the predictions of theory and curves of air consumption as a function of throttle air pressure are presented. Man-held machines are shown to be under-thrusted at throttle air pressures above 40 lb/in2g. Measurements of bit wear as a function of distance drilled are presented graphically and discussed in terms of the theory developed in Part 1.

By F. F. Roxborough, P. King, E. J. Pedroncelli

This paper describes tests on the performance of a continuous miner in cutting South African coal. Although coal cutting has been investigated extensively overseas, the results have not led to significant changes in machine design because these machines find little difficulty in cutting the softer overseas coals at a fast rate. In general, the results of the tests show that cutting efficiency improves markedly as the depth of cut per revolution of the drum increases, and that the best spacing of picks on the drum is twice the depth of cut. Pick shape is of secon¬dary importance in terms of cutting efficiency, only small differences having been found between the performances of conical- and chisel-shaped tools.

Jan 1, 1981

As a token of their gratitude, former pupils of Professor Lucien Denoel, a lecturer on coal-mining in the University of Liege, over a period of forty years, have founded the LUCIEN DENOEL prize. It is awarded, regardless of nationality and diplomas, to the author of a thesis dealing with coal-mining, ventilation, mine-draining methods, the use of explosives in the mine or coal-preparation. The thesis must show a truly scientific approach and considerable originality, and must not have been dealt with in a previous publication. The prize is 60.000 Belgian francs. The articles must be written in French, Dutch, German or English, and contain not more than 10,000 words, figures included. They must be forwarded, in triplicate, to the 'Jury du Prix Lucien DENOEL, c/o A.I.Lg., 22, rue Forgeur, Liege, Belgium,' before 1st July, 1970. The examining board reserves the right to publish the winning thesis in a Belgian magazine.

I am a partner in a minerals' development company called A.B.F. Limited, that does minerals development in Africa and Asia. I have read your very fine magazine often at the Colorado School of Mines Library in Golden, Colorado. I would like to ask your assistance in trying to locate a South African smelter; preferably on the coast, but not totally necessary for the project, that can separate the first four metals (Au, Ag, Cu, and Pb).

Jan 1, 1980

An International Ferro-alloys Congress, arranged by the Ferro Alloy Producers' Association of South Africa, the South African Institute of Mining and Metallurgy, and the National Institute for Metallurgy, will be held in Johannesburg, South Africa, in April 1974. The technical programme, occupying five days, will cover the following topics in relation to all ferro-alloys: 1. Burden preparation, blending, pelletization, handling, reducing agents. 2. Electric smelting furnaces-design, operation, management,- smelting optimization, shop practice, refractories. 3. Mineralogy, reduction behaviour, smelting reactions, slags. 4. Automation, Pollution control. 5. Applications, trends in comsumption, trends in composition specifications. There will be no parallel sessions. Papers in the above topics are invited; review papers will also be welcome. Proposed titles and abstracts in not more than 200 words should be submitted before the 30th of November, 1972, to The Chairman, Programme Committee, INFACON 74, Private Bag 7, AUCKLAND PARK, South Africa. The abstracts will be considered during January 1973, and papers accepted for the Congress must be submitted in final form before the 31st of July, 1973. The proceedings of the Congress will be published as a special volume. There will be a series of post-Congress tours to ferroalloy plants and other places of both technical and scenic interest. A full ladies' programme will be arranged. The First Circular, giving further details, can be obtained from: The Secretary of the Organizing Committee, INFACON 74, Private Bag 7, AUCKLAND PARK, South Africa.

By E. Pothas, P. R. Jochens, L. B. McRae, D. D. Howat

SYNOPSIS The phase equilibria, viscosities and sulphur capacities of titaniferous slags were determined in the composition range of CaO = 30 to 0 per cent, MgO = 0 to 30 per cent, SiO2 = 19.69 per cent, AI.O. = 13.12 per cent and TiO2 = 37.19 per cent. The phase equilibria were determined by high temperature microscopy, the viscosities were measured using a rotating outer cylinder viscometer and the sulphur capacities were evaluated from the results obtained by equilibrating the slag in a gas stream of CO, CO2 and SO2. The behaviour of these titaniferous slags under reducing conditions was examined. Possible use of the slags for aggregate, or slag-cement, and the possibility of extracting the TiO2 are discussed. CONTENTS INTRODUCTION PHASE EQUILIBRIA VISCOSITIES DISCUSSION OF THE PHASE EQUILlBRIA AND THE VISCOSITY VALUES EFFECT OF REDUCING CONDITIONS SULPHUR CAPACITY DISCUSSION OF THE SULPHUR CAPACITY VALUES POSSIBLE USES CONCLUSIONS ACKNOWLEDGEMENTS REFERENCES INTRODUCTION The latest phase in the exploitation of the mineral wealth of the Bushveld Igneous Complex is the erection of a plant by the Highveld Steel and Vanadium Corporation Limited near Witbank to produce steel and vanadium-rich slag from the titaniferous magnetites occurring in this rock formation. These titaniferous magnetites occur as segregations in the gabbro body and the TiO2 is mainly present within the structure of other constituent minerals but also occurs in smaller amounts as ilmenite and ulvospinel. The vanadium is thought to be present in the iron oxide phase due to isomorphous replacement of the iron. Until very recently, it was feared that the high titania content of these titaniferous magnetites would militate against their value as useful iron ores. However, the design of an integrated plant to produce both steel and vanadium-rich slag, and in which the iron-making process is conducted in submerged arc furnaces instead of in