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The following diagrams should replace the Figs. 4, 5, and 6 that appeared on pages 412 and 413 of the October 1986 issue. These relate to the paper entitled' A new method for the rapid float-sink analysis of coal fines' by J-P. Franzidis and M.C. Harris Womanpower In 1981 the Publicity Committee of the Federation of Societies of Professional Engineers (FSPE) decided that one way in which the engineering manpower pool could be increased would be by the introduction of womanpower to the profession. Since then, Std 9 and 10 girls have been invited to attend the engineering winterschools held annually at the various universities under the auspices of SAFUES. Coal-mining wastes The 2nd International Symposium on the Reclamation, Treatment and Utilization of Coal Mining Wastes will be held in Nottingham (England) from 7th to 11th September, 1987.

Jan 1, 1986

By D. D. Hawat

The locations of potential reserves of chromite ores throughout the world are discussed. Reference is made to the marked changes in international trade in chromite ores during the past ten to fifteen years, and to the change in locality of the production of ferochromium aloys, which is curently largely carried out in the country of origin of the ores. The influence of these changes has been very profound in South Africa, which has the largest smelting capacity and the largest production of ferochromium aloys in the world. A proportion of South African ore is stil exported to meet the demands for the production of chromium chemicals and refractories, including a large tonnage of foundry sands. Ferochromium smelters in South Africa have a capacity of virtualy 1 Mt of aloy per annum. Nearly al this development has taken place since the introduction of the argon-oxygen decarburization (A.O.D.) process for the smelting of stainless steels. Formerly, expensive Iow-carbon ferochromium aloys were required as raw materials, but the AO.D. process, which is being used world wide, permits the use of high-carbon ferrochromium, the main product of the smelters in this country. The production in South Africa of chromium-containing corrosion- and heat-resistant steels is stil on a relatively smal scale, but serious atention is being paid to the exploitation of low-carbon weldable feritic chromium steel.

Jan 1, 1986

1. Book reviews Stainless Steels '84. London, Institute of Metals, 1985. £39 (U.K.), US$62 (elsewhere) Reviewer: J.B. Oalton Process engineering of size reduction: bal miling, by LG. Austin, R.R. Klimpel, andP.T. Luckie. New York, AIME, 1984. 561 pp. Reviewer: M.J. Lazer 2. Recent publications Hard and superhard materials. New York, Worltech Report Inc. (44 Woodbine Avenue, P.O. Box 212, Northport, 11768 U.S.A.), 1985. 270 pp. $1500.International comparison of standard materials-steel and cast iron, compiled by W. Oto and K. Schaning, and edited by DIN German Standards Institute e.V. Berlin, Beuth Verlag GmbH, 1985. 3rd edition, 416 pp. DM 158. Tin and its uses no. 146. Greenford (England), International Tin Research Institute, 1985. Write your own CV, by Max Kowen. Johannesburg, Legal Personnel Selections (404 Medical Centre, Cor Jeppe and Delvers Sts, Johannesburg 2001), Nov. 1985. 40 pp. R12,50 + GST.

Jan 1, 1986

Underground operators' conference. Parkvile (Australia), Australasian Institute of Mining and Metallurgy, $A25 (surface). Reviewer: G.R. Stil Reagents in the minerals industry: A review, edited by M.J. Jones and R. Oblat. London, Institution of Mining and Metallurgy, 1986, £50. Reviewer: L. Goold

Jan 1, 1986

By B. G. Russell

A wide range of minerals is found within the Republic of South Africa, many of which are exploited to a greater extent than in similar deposits found elsewhere. It is often asked whether this is atributed to the high grade of the ores encountered in this country, or whether such factors as fiscal and Infrastructural incentives create an economic climate that has en bled the mining industry to successfully extract and market minerals at a profit. This paper views South Africa's mineral resources in a regional and global context In an attempt to place the country's geological wealth in perspective. It represents the author's own Views, and not necessarily those of the Department of Mine al and Energy Affairs.

Jan 1, 1986

By O. G. Pauw

The relationships between mill power and pebble load, bulk density of the load, and circulating load were investigated on the pebble mills in the grinding circuit at Buffelsfontein Gold Mine. This paper describes the most significant relationships among the operating and control variables on the plant, and illustrates these by reference to experimental data gathered from the plant during operation. The results were used for the development of very successful multivariable peak-seeking controllers for the pebble load and bulk density of the load on these pebble mills. The peak-seeking control algorithms are described in detail. The control system has operated successfully at Buffelsfontein for more than 18 months and is still in operation.

Jan 1, 1985

By D. J. Crowe

I read with considerable interest the recent articles on copper by Mr C.O. Beale as published in the Journal. However, in Part 11 the section dealing with Prieska Copper Mines (Pty) Limited contained several factual errors, details of which are given below.

Jan 1, 1985

Mr R. w.o. Kersten joined the Geological Department of Anglovaal in 1964 after obtaining a B.Sc. Honours degree in Geology at the University of Pretoria. Mr H.G. Mosenthal was educated at Pretoria Boys' High School and the University of the Witwatersrand. He holds a B.Sc. in Mining Engineering and a GDE.

Jan 1, 1985

By P. F. Sorensen

A simple mathematical model is presented that relates the 'head' developed at the surface of pulp in a tank to the power dissipated by the air in producing it. The value for the head is then used in the calculation of the superficial circulating velocity of the pulp and the area of the overflow, and the product of these two values gives the pumping rate of the pulp. Thus, the superficial circulating velocity, and hence pumping rate of the pulp, are related directly to the flow-rate of the air. This hypothesis was tested with good results in an air-agitated pachuca tank (of 1 m in diameter) fitted with a draught tube. The method can also be used for the prediction of the pumping rates in production-scale vessels.

Jan 1, 1985

By Peter Smith

The construction of one of the world's largest goldrecovery plants to treat run-of-mine ore is progressing on schedule at the President Brand Gold Mine in the Orange Free State. Designed to treat 390 kt per month, the plant will recover 96 per cent of the gold from the ore at a capital cost of 160 million rands in terms of January 1983 money. It will replace the existing gold-treatment installation, as well as provide a 30 per cent increase in capacity. Mintek reports Report M161 Improved recoveries of gold from auriferous calcines and pyrites by fine milling. Report M171 The development of a versatile computer programme for the evaluation of batchflotation results. Report M178 The reduction of chromite in a transferred-arc plasma furnace. Report M179 Optimization of an inductively coupled plasma by the simplex method.

Jan 1, 1985

Council for 1998/99 President R.P. Mohring President Elect J.R. Dixon Vice Presidents Senior junior M.H. Rogers Dr L.A. Cramer Immediate Past President Honorary Treasurer Dr N.A. Barcza J.A. Cruise

Jan 1, 1985

By Pamela Binstead

The Institute's ninetieth anniversary was celebrated in grand style with a banquet and dance in the ballroom of the Carlton Hotel in Johannesburg, on 22nd March. Some six hundred and thirty members and guests filled the room to capacity, and many remained to enjoy the festivities until well past midnight.

Jan 1, 1985

By B. Rohrmann

The paper deals briefly with the history of vanadium, and its uses, price movement, and world resources. It then describes the titanomagnetite ore of the Bushveld Complex, and the production of vanadium from this ore at Highveld Steel & Vanadium Corporation Limited, giving details of the various processes used, including the roast-leach, rotary-kiln, electric-smelting, shaking-ladle, and basic-oxygen-furnace operations. The paper concludes with a very brief account of the treatment of Highveld slags in Europe for the production of vanadium pentoxlde and ferrovanadium.

Jan 1, 1985

By C. A. Hunt

The problem of materials balancing is reviewed with particular reference to the minerals industry. A broad statistical framework is established that, besides extending the classical estimation problem, allows questions concerning the value of sample information to be addressed. The following are examples of such questions: How much money should be spent on sampling? Which streams in a plant should be sampled? What should be sampled? The approach adopted makes use of Bayesian analysis. The discussion includes an illustrative example involving a simple flotation circuit.

Jan 1, 1985

By R. N. Guest

The Tromp distribution curve was used in an evaluation of gravity separators treating a synthetic ore made up of silica and marker minerals of various relative densities. The results pinpoint differences in the concentration of particles of different sizes, and indicate how the grade of a concentrate is likely to vary with particle size. An increase in the feed rate increased the efficiency of the 'waterless' spiral concentrator that was tested, but the multiport spiral concentrator tested was more efficient. Both spiral concentrators were found to be more efficient than the pinched sluice and the shaking table that were tested. The method was found to be a useful way of evaluating gravity concentrators, but, for ease of analysis, care must be taken in the choice of marker minerals.

Jan 1, 1985

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

Mr D. Twigg graduated in Metallurgy at the Sheffield Polytechnic, and later obtained a Master of Science degree at the University of Bradford. Mr I.D. Matthews matriculated at Roosevelt High School and joined the No. 1 Parachute Battalion in 1968. He worked in Zimbabwe for 31 years in geological prospecting, civil engineering, and open-pit mining.

Jan 1, 1985

By G. B. Lundstrom

SYNOPSIS For some time, Vaal Reefs South has operated blindhole borers successfully as an integral part of the mining cycle of operations. To date, over 13 000 m of mechanized boxholing has been completed, and from time to time impressive performances have been achieved. The paper describes the machines, the modus operandi, and the structure of the boring organization at the Mine, with some of the results recorded. The Mine recently took delivery of two new machines with interesting design features. The introduction and early experiences with these two machines are also described.

Jan 1, 1985

Die Suid-Afrikaanse Instituut vir Mynbou en Metallurgie het 'n paar jaar gelede 'n toekenning vir voortreflike akademiese prestasie deur vierdejaarstudente aan technikons ingestel. Disinvestment campaign by COLIN M.SPENCE As President of the Federation of Societies of Professional Engineers, which is an organization representing twelve institutions of the engineering profession comprising over 18 000 engineers of all kinds-of whom over 15 000 are either professional engineers or engineering graduates-I have been asked to make a statement on the disinvestment campaign on behalf of the profession.

Jan 1, 1985

By I. M. MacGregor

This paper discusses the possible use of petrological data and proximate analyses in the prediction of cutting forces for coal. It is restricted to the development of univariate predictors based on data from thirteen collieries in five major Transvaal and Orange Free State coalfields and three coal provinces. The aim of the work was the identification and development of the best predictors of mean peak cutting force and Hardgrove grindability index from among the independent variables evaluated. The data, which were obtained by use of the penetrometer developed by the Chamber of Mines Research Organization, were processed according to the SPSS computer package. The analysis revealed reasonable correlations between the Hardgrove grindability index and (1) the volatiles and vitrinite content in the Vereeniging-Sasolburg and South Rand Coalfields, (2) the contents of vitrinite, vitrinite plus exinite, and minerals plus inertinite in the Eastern Transvaal Coalfield.

Jan 1, 1985