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By J. H. deur Potgieter

This paper, 'A review of the biological treatment of cyanide-bearing waste water' discusses the necessity for the treatment of cyanide-bearing waste water with a view to the avoidance of environmental pollution, and the limitations of the available chemical and physical processes are referred to briefly. The sources of cyanide-bearing waste waters are mentioned. The mechanisms of production and utilization of cyanide by fungi and bacteria are discussed. The work done in connection with the biological removal and destruction of cyanide is summarized, the successes achieved are described, and the relevant processes are listed. In conclusion, some advantages of biological processes for the removal of cyanide are mentioned.

Jan 1, 1991

1. Publications of The Institute of Metals The following publications are available from The Institute of Metals, Sales and Marketing Dept, 1 Carlton House Terrace, London SWIY 5DB, England. . Intermediate temperature embrittlement processes in duplex stainless steels. 1990. £15.00. This is a special issue of Materials Science and Technology containing the full proceedings of the international workshop held in Oxford in August 1989. . Worked examples in dislocations, by M.J. Whelan. 112 pp. £16.00. This is a concise introductory text that examines aspects of the theory of dislocations. . Introduction to creep mechanisms, by B. Wilshire. 1991. 112 pp. Well-supported by diagrams and illustrations, this concise introductory textbook allows students and engineers to increase their knowledge of modern theoretical and practical approaches to creep and creep fracture. . Powder metallurgy. A series of lectures. 1991. (Looseleaf binder). Originally published in 1986 by the Fachverband Pulvermetallurgie, this course book provides an introduction to PM technology. Divided into eight thematically distinct sections, it also contains numerous illustrations and tables, as well as 150 slides. The concluding section contains an extensive reference list to the literature for readers wishing to study topics in greater detail.

Jan 1, 1991

Tunnel Construction 90. London, Institution of Mining and Metallurgy, 1990. Reviewer: J.A. Cruise This is the published volume of papers presented at the Tunnel Construction 90 Conference, which was held in London in April 1990 under the auspices of The Institute of Mining and Metallurgy. Twenty papers are presented and their titles are listed below.

Jan 1, 1991

The following are available from Metal Bulletin Books Ltd, Park House, Park Terrace, Worcester Park, Surrey KT4 7HY, England. . World aluminium-a Metal Bulletin databook. 2nd ed. 1990. £71.50 surface, £76.50 airmail. This is a compendium of information listing salient details of companies mining bauxite and producing alumina, primary aluminium, secondary ingot, master alloys, and semi-fabricated products; aluminium trading companies; and a memoranda section listing associations, brand names, and other useful information. It is a userfriendly international reference book for aluminium buyers, traders, and producers.

Jan 1, 1991

1. Reviews Extraction metallurgy, by J.D. Gilchrist. 3rd ed. Oxford, Pergamon, 1989. 431 pp. £50.00 (hard cover), £14.95 (soft cover). Reviewer. Prof. M.D. Brayshaw. Reviewer. Prof. M.D. Brayshaw This third edition bears testimony to a work that contains much of value for lecturers, students, and practising metallurgists. Mineral processing in the United Kingdom, edited by P.A. Dowd. London, Institution of Mining and Metallurgy, 1988. 223 pp. £25.00. Reviewer: Prof. M.D. Brayshaw It came as both a pleasure and a challenge for a resident of South Africa (with its volume and diversity of minerals) to review a book focusing on the beneficiation of ores from the sparsely endowed mineral chests of the United Kingdom. 2. Recent issues Rock mechanics. Theory and applications with case histories, by W. Wittke. Translated from German by R. Sykes. Berlin, Springer-Verlag, 1990. 1076pp. DM248. McGregor's quick reference to the JSE. Pretoria, Juta & Co., 1990. R39,95. McGregor's economic alternatives. Pretoria, Juta & Co., 1990. 400 pp. R34,95. 3. New journals Journal of Materials Chemistry, edited by A.R. West and J. Leader, and published two-monthly by The Royal Society of Chemistry (Blackhorse Road, Letchworth, Herts SG6 IHN, OK). £195 per year, starting in 1991. New Materials World, published monthly by Lawrence Cooklin (15 Selvage Lane, Mill Hill, London NW? 3SS, OK). £180 per year. Mendeleev Communications 4. Books from The Institute of Metals The following were published recently, or are to be published soon, by The Institute of Metals, 1 Carlton House Terrace, London SWl Y SOB, OK. Illustrated case histories of marine corrosion. 1990. Modern steelmaking methods, by C. Moore and R.I. Marshall. 2nd ed. 1990. Grain boundary fractures, by S.F. Pugh. 1991. 160 pp.

Jan 1, 1991

Written contribution by J.F. Curtist The paper is an interesting exercise in the application of mathematics to a theoretical situation presumed to oc¬cur underground. However, some of the assumptions on which the calculations are based are unlikely to occur in any actual mining situation. Assumptions made in the paper Objections to these assumptions are noted seriatim. (1) `it is assumed that any loading-rate effect will be small and can be ignored' (p. 3). A loading rate of the order of 50 kN-12 per cent of the maximum load-is customary to prevent the props being dislodged by the blast. (2) `it is unlikely that all the props will be installed with their full stroke available, but for the purpose of this analysis, it is assumed that this is the case' (p. 3). A more reasonable assumption would be that, with the most careful selection of prop length and the most rigid control of stope width, the available stroke length would on average be reduced by the order of 70 mm on installation-20 per cent of full stroke. (3) `each support unit supports a block of 3,3 m2 bound¬ed by vertical fractures with zero cohesion that are parallel and at right-angles to the stope face respec¬tively' (p. 5). Joughin and Jager have shown this to be an unwar¬ranted assumption in respect of the positioning, the direction, and the dip of the fractures present in a stope in rockburst conditions. If, as assumed, there was `zero cohesion' between such blocks, the removal of a hydraulic prop in row 3 supporting such a block would ensure that it fell out before a profile prop could be installed in the same position. (4) `the height of each of these blocks is 3,0 m, the volume of each block is 9,9M3, the mass of each block is 27 225 kg' (p. 5). The concept of individual props being affected by dis¬crete blocks of known and uniform dimensions of relatively low ground velocities (less than or equal to 2,16 m/s) acting in line with the axis of the prop is one that lends itself to neat mathematical calcula¬tions. It does not, however, bear much similarity to the actual conditions that are exposed underground in excavations where rockbursts occur. Ortlepp and co-workers concluded that `the impulse of the shockwave can cause the displacement of the

Jan 1, 1991

Publications of the IMM These two titles have just been published as part of the popular series of Special Reference Lists being issued by the Institution of Mining and Metalurgy, 44 Portland Place, London WIN BR, England.

Jan 1, 1991

1. Books on management The following are available from Knowledge Resources, P.O. Box 3954, Randburg 2125. . Competitive advantage of nations, by Professor Michael Porter from Harvard Business School. This book highlights the importance of industries in contributing towards national competitiveness. It is being regarded as one of the 10 best business books published during 1990. . The borderless world, by Kenichi Ohmae, Managing Director of McKinsey in Japan. This deals with business in the new interlinked economy. . Megatrends 2000, by John Naisbitt and Patricia Aburdene. This book outlines the mega/macro trends that will

Jan 1, 1991

Students The South African Institute of Mining and Metallurgy (SAlMM) places a high value on its student members, for these people will ultimately become corporate members and will, it is hoped, play an active role in the affairs of the Institute. Why should young persons at University or Technikon want to become members of our Institute? There are several reasons.

Jan 1, 1991

'Gee Whiz', a nationwide schools' science and technology competition, is being screened on SATY1 on Friday evenings at 18:00. Twenty-seven schools from al over South Africa are taking part in the series, which will run for 13 weeks. The participating schools were selected on the basis of their performance in the National Youth Science Olympiad and in Mintek's Minsa science competition, which has been organized on an annual basis since 1988.

Jan 1, 1991

I appreciate the honour that has been bestowed upon me by my election as President of this Institute. We are starting what I believe will be a challenging year. The first challenge facing the Institute is financial. From the accounts for you will note that the Institute operated at a loss for the first time since 1987. average membership subscription was increased by only 10 per cent, reflecting desire to keep costs down in the minerals industry. The Institute will therefore to rely on other income to meet its budget requirements and break even financially. source of these funds will be the activities of the Technical Programme Committees. disciplines-Mining, Extraction Metallurgy, and Metals Technology are planning programmes for the coming year. I urge al members to increase their support of colloquia schools. Increased membership would also bring in more funds. Please, therefore, encourage colleagues who are not yet members of the Institute to join it.

Jan 1, 1991

By M. B. Cortie, J. H. Potgieter

An account is given of the production of three types of experimental high-chromium duplex stainless steel. The alloys had chromium contents of 22, 29, and 35 per cent. The partitioning of the main alloying elements between the austenite and ferite phases was determined, and the effect of the alloying elements chromium, nickel, and molybdenum on the mechanical properties and corrosion resistance of the duplex stainless steels is summarized. The phase compositions of the different duplex stainless steels were measured by different techniques, and the values obtained were correlated. The cracking occasionally observed during the thermo mechanical processing of these alloys was studied, and is explained as being the result of known embritlement processes.

Jan 1, 1990

Mr G H Park was born and brought up in Zimbabwe, in mining from the University of the Witwatersrand. Starting as a Learner Official at Rand Mines, he went Mr D J van Niekerk was educated at Helpmekaar Boys' High School in Johannesburg and the University of Pretoria. Mr C J C Janse van Vuuren was educated at Klerksdorp High School, Pretoria Technical Colege, the University of Pretoria, and Unisa. He holds the folowing degrees: BSc (I&S), BSc Hons (Met Pta), ND (Met Tech), AEP (Unisa). Prof. R F Sandenbergh was educated at the Afrikaanse Hoerskool Germiston and the University of Pretoria. He holds the degrees of B Ing (Chem), M Ing (Chem), and D Ing (Metal). President's Award Professor Jannie van Deventer, Head of the Department of Metalurgical Engineering at the University of Stelenbosch, has been honoured with one of the five President's Awards for 1990. These awards are made by the CSIR's Foundation for Research Development. G R Bozzoli Awards* Prof. Alan Kemp, Dean of the Faculty of Engineering at the University of the Witwatersrand, has appealed to industry not to cut bursary funding during recessionary times.

Jan 1, 1990

By J. M. Barnard, M. P. Brandt, L. E. Korwin-Kossakowski, W. H. Smith

Petrographic analyses of coal rank and maceral-group composition are widely used in the characterization of coal. This paper describes the use of an image analyser (IBAS Kontron) for fuly automated measurements of the rank and maceral groups of seam coals. The rank is then derived from reflectance histograms, or 'fingerprints', of coal reflectance distributions (being expressed as the mean random reflectance of vitrinite). The volume proportions of the maceral groups are calculated from the histograms. The results obtained with the IBAS were generally in agreement with those obtained by conventional methods of reflectance measurement and point-count analysis. However, the results were inconsistent for coals with a bimodal character or a wide V-class distribution. The rank of the analysed coals ranged from 0,50 to 1,10 per cent mean random reflectance. The lowest reflectance that can be analysed with the IBAS is 0,4 per cent. The speed, objectiveness, and repeatability of this technique make it exceptionally suitable for use in the quality control of large numbers of samples.

Jan 1, 1990

Gerhardus Paulus Badenhorst passed away on 2nd December, 1989. Badie, as he was known to all, will be missed by his many friends and colleagues, and will be remembered by al who knew him as a warm-hearted person who was totally dedicated to the safety and health of the workers in the mining industry.

Jan 1, 1990

By D. W. de Vos

A school on the principles and practices of ladle metallurgy, organized by the Technical Committee: Metals Technology of The South African Institute of Mining and Metallurgy, was held at the University of Pretoria from 13th to 16th November, 1989. The course leader, Professor R.J. Fruehan from the Carnegie Melon University, Pittsburgh, Pennsylvania, presented the main part of the course. Three papers were read by local steelmakers on the experience gained in the field of ladle metallurgy in South Africa. The School also included a special half day seminar on new and innovative steelmaking and casting processes presented by Professor Fruehan.

Jan 1, 1990

By R. R. Mankowski

The work described here is an extension of current theory applied to obtaining the power dissipated at the wavefront of a transverse disturbance traveling along a mine hoisting cable. A previously derived empirical relation is adapted to the present problem, and is solved by use of a Lagrange-type reference frame moving with the wavefront. As a result of tie limitations inherent in the original relation, only a lower-bound for the domain of predicted power losses is defined. A qualitative assessment of conditions leading to the undesirable effects of internal frictional losses at the wavefronts are discussed in terms of the operating environment found on typical mining installations

Jan 1, 1990

By R. P. King, L. C. Woollacott

To date developments in the simulation of carbon-in-pulp (CIP) adsorption circuits have focused primarily on the modeling of adsorption. This series of three papers describes a development in a direction that has received less attention, i.e. the need for a detailed description of the movement of carbon and slurry in continuous CIP and carbon-in-leach (CIL) plants. A new simulator has been developed based on the population-balance approach for modeling the movement of carbon and slurry. Existing adsorption and leaching models are evaluated in this paper in order to establish which are appropriate for use in the new simulator. The details of the simulator are given in Part 2 of this series.

Jan 1, 1990

By L. Woollacott, R. P. King

Although several models for the carbon-in-pulp (CIP) or carbon-in-leach (CIL) processes have been published, most of these models do not consider in detail the way in which the carbon phase flows on large-scale plants. This paper illustrates the importance of these details if the CIP or CIL process is to be modeled correctly. An appropriate model, based on population-balance techniques, is then derived. Suitable mathematical techniques for the solution of the model equations are also described. Finally, a method for estimating the model parameters for a full-scale plant is described.

Jan 1, 1990

By H. G. Mosenthal

In any mining enterprise, the extraction of the ore from the orebody is of vital importance. This activity is stoping. The gold mines of the Witwatersrand and its extensions in the Klerksdorp, Welkom, and Evander areas form the most extensive goldfield in the world. This address reviews stoping technology and improvements in this technology since the end of the Second World War. Although the reefs that make up the Witwatersrand orebody are uniquely extensive, they are not suited to mechanized mining. This is due to a number of factors such as the depth of the orebody, its narrowness, and the hardness and abrasiveness of the quartzite forming the orebody. The most notable improvements in stoping technology have been brought about because of our beter understanding of rock-engineering problems. This has resulted in beter layouts, stoping geometry, systems of aleviating rock stresses, and support systems. It has enabled the industry, at ever-greater mining depths, to maintain and even increase productivity. These improvements, based on rock engineering, have significantly reduced the accidents due to rockbursts. There are many diferences between today's stoping and that practised forty years ago. Panels are shorter, concentrated mining has superseded bench mining, and the support systems are certainly better. Yet the face scraper is still used extensively, as are pneumatic rock drills. Some innovative stoping systems that have given rise to improved productivity are discussed. Explosives technology has shown spectacular advances during the period under review. Sadly, our local industry has had little to do with this research and development, but has been most adaptive in using the new products on offer.

Jan 1, 1990