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By D. S. Loubser

The technique of backfilling in the gold mining industry is dependent on the dewatering of slurry to form a solid support system. In many cases flocculants are added to the slurry to increase the rate of dewatering. To ensure that a stable support is obtained it is important that the chemistry, application and limitations of these flocculant additives are understood. Flocculant additives have to be added at a point where minimum shear will occur. (Shear occurs when a flocculant is exposed to excess energy resulting in breakdown, of the floc.) To ensure that optimum results are obtained it is important that personnel involved are trained to use the flocculant additives and dosing equipment correctly.

Jan 1, 1988

By Stephen Hughes

Ausmelt Top Submerged Lancing (TSL) Technology has gained widespread commercial acceptance in the lead and zinc industries, as an efficient and highly flexible pyrometallurgical reactor with accompanying excellent environmental performance. For the processing of lead and zinc bearing feed materials twenty one (21) Ausmelt furnaces are now in operation, under design or under construction. With recent increases in the value of both lead and zinc and an ever increasing focus on the sustainable use of resources, interest in the processing of secondary feed material sources as well as metal containing residues has substantially increased. Ausmelt Technology has proven to be well suited to the economic recovery of values from such sources. This has for example culminated in Ausmelt?s commitment to the Whyalla Zinc project as the owner/operator of a facility for the treatment of zinc bearing secondary feeds. This paper describes Ausmelt?s recent developments in the fields of lead and zinc processing, as well as further investigations into new processing areas, including the direct smelting of zinc concentrates. Ausmelt?s TSL Technology can now be regarded as Best Available Technology (BAT) for metal production.

Jan 1, 2008

If the Journal is to fulfill its mandate to the mining and metallurgical industry, it needs to expand its readership and, by implication, membership of The South African Institute of Mining and Metallurgy. This we hope to do by increasing the appeal of the Journal to a wider audience through the inclusion, in addition to our high-quality research papers, of equally high-quality papers, articles, and contributions that will be of interest to our less research-minded members.

Jan 1, 1990

By B. C. Alberts

An international conference on 'The Planning and Operation of Open-pit and Strip Mines' was held at University of Pretoria from 9th to 13th April, 1984. The Conference was organized by the Mining Alumni Society the University of Pretoria and The South African Institute Mining and Metallurgy. Delegates of the mining fraternity from all over the world and Southern Africa attended the Conference. These included more than 400 delegates from Australia, Austria, Botswana, Brazil, Canada, Germany, Holland, SWA-Namibia, the United Kingdom, the United States of America, Zimbabwe, and South Africa.

Jan 1, 1984

By Richard J. Robbins

Raise and shaft drilling, a continuing development RICHARD J. ROBBINS* (Visitor) Although the past decade has witnessed many improvements in large-diameter drilling machinery for the boring of raises, there is still room for improvement both in operational use and in the design of equipment. Some of the available machines are described and illustrated, and it is concluded that the possibilities of new systems and designs should continually be re-assessed since the factors that determine their feasibility, such as bore diameter, cutter costs, and penetration rates, are changing rapidly.

By R. O. Heckroodt

After a brief review of the characteristics of clay minerals and their origin, a summary is given of the industrial uses of different types of clay materials. The mining and beneficiation of clays are discussed, with special reference to the upgrading of certain types of materials. The occurrence and resources of the more important varieties of clays are dealt with in some detail, viz residual kaolin derived from granite and sediments, brickmaking clays, refractory clays, bentonite, and palygorskite. The Republic of South Africa is well endowed with a wide spectrum of clay materials, with one important exception. Kaolin suitable for paper coating is not known to occur in the Republic, and efforts to beneficiate and treat local materials to achieve the desired properties have so far been unsuccessful.

Jan 1, 1991

By M. U. Ozbay

This paper presents an overview of the research that has been carried out to improve the understanding of the fracture processes occurring in rock under high levels of stress. The onset and growth of fractures are studied by means of laboratory model testing, and the results obtained are used in the calibration and validation of the numerical model DIGS, which is based on displacement discontinuity. The results obtained so far have shown that, while there are overall similarities between the experimental results and the numerical simulations, improvements to the experimental procedures and the DIGS are required for a detailed mechanistic understanding of shear-band orientations and extension fractures.

Jan 1, 1996

By Colin M. Spence

If one is to discuss sensibly and beneficially the whole spectrum of education, training, and employment of engineers, it is not possible to confine oneself to Professional Engineers because the profession of engineering embraces also technologists, technicians, and those people known in South Africa as certificated engineers. It would therefore be imprudent if this seminar were to be limited to certain sectors of the profession and industry. I hope that it will review the full situation from top to bottom and from side to side. New President of FAPA Mr Douglas H. Mills took office as President of the Federation of Societies of Professional Engineers on 1st July, 1985.

Jan 1, 1985

Financial Times Mining International Year Book 1979. London, The Financial Times Limited, 1979. 712 pp. Price: airmail, U .S. $60,00; surface mail, U .S. $42,00. International Wrought Copper Council. Glossary of terms applicable to wrought products in copper and copper alloys. London, the Council (6 Bathurst Street, Sussex Square, London W2 2SD), 1978. 170 pp. 80 Swiss francs (approximately £25). Council of Mining and Metallurgical Institutions At a meeting of the Council of Commonwealth Mining and Metallurgical Institutions held on 15th January, 1979, it was unanimously agreed that the name of the Council should be changed.. Assaying and analytical techniques This year sees the Diamond Jubilee of the South African Institute of Assayers and Analysts, which held its first meeting on the 3rd of May, 1919.

Jan 1, 1979

By D. D. Howat

The first joint colloquium between the South African Institute of Mining and Metallurgy and the South African Branch of the Institution of Metallurgists was held in Kelvin House on 23rd April, 1981. About eighty delegates registered, the majority being associated with the local branch of the Institution of Metallurgists. Types of Abrasion and Wear Professor A. Ball, of the University of Cape Town, gave the opening address, which he entitled 'Some Thoughts on Abrasion and Wear'. In his thoughtprovoking talk, he quoted some figures showing that, in the highly industrialized countries, loss by wear and abrasion might amount to about 4 per cent of the gross national product but, in the Republic of South Africa, it was believed to be about 6 per cent of the gross national productprobably associated with the massive influence of mining in our economy. Professor Ball described wear as being of three main types.

Jan 1, 1981

NOTICES The Institution of Mining and Metallurgy The Institution is to hold a one day meeting entitled "Sampling in the mineral and metallurgical processing industries" at Imperial College, London, on 2nd July, 1973. International Conference on Air Pollution This Conference is organised by the Department of Health and the National Association for clean air. Consas 74 The Fifth Conference of Southern African Surveyorswill be held in Salisbury, Rhodesia, from 3rd to 9th February, 1974.

By B. Litt, D. L. Van Coller

Job evaluation and the changing wage pattern by D. L. VAN COLLER, B.A.(Cape Town), M.A., B.Litt.{Oxon.) (Visitor) This paper sets out to show how changing forces are affecting the techniques that have been used in the evaluation of Black jobs on gold mines in the Anglo American Group since the introduction of job evaluation in 1961. Initially, job evaluation was essentially a management tool designed to differentiate jobs in a limited skill spectrum and thereby permit the establishment of a 'many stepped' job ladder for Black employees to climb. With the changing wage pattern, job evaluation is becoming an industrialrelations tool aimed at recognizing the skill and effort contributed by the worker so that the pay relationships between jobs are seen to be equitable by the employees.

Jan 8, 1974

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 Dr Peter Laxen

Dr Peter Laxen, the Mintek Consultant on gold and uranium, has won the 1982 award of the Percy Fox Foundation. The presentation was made by the Minster of Finance, Mr Owen Horwood, at a banquet on 6 March.

Jan 1, 1982

By X. Jia

The ability to perform three dimensional imaging at micron-scale resolution of real mineral floc sediments and structures using commercially available Micro X-ray Tomography (XMT) instrumentation can be used for the analysis of aggregates and granules, liberation and dewatering of sediments. This paper presents are view of recent work by the authors relevant to the mining and minerals industries. It covers three main topics: X-ray imaging of agglomerates and multi-component mineralic particles,, permeability of sediments, and dissolution of granules with potential application to heap leaching.

Jan 1, 2008

Professor G.T. van Rooyen has guided the Department of Materials Science and Metallurgical Engineering at the University of Pretoria in South Africa for the past 32 years. During this period, 54 masters' degrees have been awarded in the Department, and 17 doctorandi promoted. He has also made a major contribution to industry by his incisive analysis, relevant and practical synthesis, and his exceptional talent in innovative design. He is still active in fracture analysis, thermal fatigue, weld simulation transformation kinetics, and fracture mechanics, and continues to contribute to a better understanding of metallurgical problems encountered in practice. He has advised many companies, and has received many honours and recognitions.

Jan 1, 1994

By L. A. Vermeulen, D. D. Howat

A study was made of the performance of a rod mil operating without liter bars and with different arrangements of liter bars in the lining. . The results show that striking improvements in performance, increased throughput, and reduced consumption of liner metal and electrical energy can be obtained by a change in the geometry of the liter-bar arrangements within a mil. Rod mils of equal size fitted with the same arrangement of liter bars but operating at different speeds presented apparent anomalies in the relative consumption efficiency of electrical energy for the production of material smaller than 75 µ m. Marked savings in the consumption of liner metal were achieved by the use of an arrangement of alternating lines of higher and lower liter bars. A study of the relative performances of two large tube mils showed that the use of liter bars in one of the mils resulted in a marked reduction in the consumption of liner metal and electrical energy per ton of material smaller than 75 µ m in the product.

Jan 1, 1986

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 E. J. Magri, D. M. Hawkins

This paper deals with an experimental programme carried out with a gold analyser in the period June to September 1979 at Loraine Gold Mines. The results were found to be reproducible, with no overall or conditional bias when the measurements were compared with those obtained from chip samples. The standard error of estimation of a 3 m reef exposure, which was the sampling interval, can be reduced by a factor of 2,5 if the complete stretch is scanned, rather than the taking of one chip sample in its centre. Complete statistical and computational procedures were developed for the fitting of the normal-Iognormal model to observed analyser data and for the determination of the most likely gold grade for a particular analyser measurement. (This corection procedure is necessary since a significant number of negative analyser measurements can be observed.) Panel averages of uncorrected scans showed a small conditional bias relative to those of corrected scans. However, uncorrected panel averages can be used for on-the-spot decisions regarding whole panels. For standard calculations of ore reserves, use should be made of corrected scans. Under reasonable assumptions, the use of the detector in the selective mining of low-grade narrow reefs such as the Basal Reef at Loraine Gold Mines, when compared with the conventional chip-sampling method, can result in a saving of as high as R40 million in present-money terms over the life of a project. The difference could be even larger in a highly variable reef like the B Reef at Loraine Gold Mines.

Jan 1, 1987

Mixtures of MnO and graphite were reacted under argon at temperatures ranging from 1200 to 1425°C, and the loss in mass of the mixture was recorded continuously. The results showed that the rate of reduction of MnO increased as the temperature increased and the ratio of MnO to C decreased. The effect of the particle size of MnO and of graphite on the rate of reduction at I350°C was very small in the range 63 to 250 µm for MnO and 45 to 355 µm for graphite. The rate of reduction at I350°C was increased markedly by the addition of Na2CO2 and K2CO3, was slightly increased by the addition of Fe2O3, was unaffected by the addition of CaO, MgO, and AI2O., and was decreased by the addition of SiO2. Some CO2 was always present in the effluent gas, and this was taken as evidence that the reduction of MnO occurred by way of CO2 as an intermediate product. The activation energy of the ratecontrolling step was 57,5 kcal, and this was similar to the measured activation energy for the gasification of graphite by CO., namely, 61,S kcal per mole of graphite. A simple kinetic model was derived on the assumption that the gasification of graphite was the ratecontrolling step, and the results over the temperature range 1200 to I425°C, when plotted in the appropriate form, yielded straight lines as predicted by the model.

Jan 1, 1980