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A very successful banquet was held in the Ballroom of the Carlton Hotel on 7th March, 1986. The Institute thanks the Organizing Committee and the sponsors (listed on this page), without whose generous support the banquet would not have been possible.

Jan 1, 1986

Pyrometallurgy has played a very important role in southern Africa for at least four centuries. It continues to do so, and recent years have seen many exciting developments in pyrometallurgical technology. The wonderfully diverse rich mineral deposits in this area of the world have provided some unique opportunities for industrial processes to be established. The ?Southern African Pyrometallurgy 2006? conference was set up to showcase southern African pyrometallurgical operations, and to provide a forum for the exchange of ideas between people working at various types of smelters. Papers have been obtained from a wide variety of pyrometallurgical plants in southern Africa. These descriptions of plant operations (as well as some history, and highlights of current work) will provide useful reference information for some time to come. Contributions are also included from universities, research organizations, and engineering companies, so that the full spectrum of pyrometallurgical activities can be covered. The plant descriptions will be published on a website, where they can be updated as and when required, with the eventual goal of having a description of every smelter in the region. The conference venue was selected to be the 'Cradle of Humankind' world heritage area, about 40 km from Johannesburg. Not only does this keep the conference within easy reach of the city and yet far enough out into the countryside to allow people to focus on the conference, it is also within easy reach of many pyrometallurgical plants. There is a particular significance to the choice of location, in that the Swartkrans area close to the Sterkfontein Caves is the site of the earliest evidence of the deliberate controlled use of fire by human beings (about 1.3 million years ago), and this is obviously a necessary precursor to pyrometallurgy. The area also lends itself to a very wide range of outdoor, social, and cultural activities to supplement the technical content of the programme. It is hoped that activities such as a hot air balloon safari and visits to the world-renowned Sterkfontein Caves and Wonder Cave will help to make the conference a memorable one for those able to attend. I trust that the ongoing value of the papers and presentations will make all the hard work of the many contributors most worthwhile.

Jan 1, 2006

By J. L. van Niekerk

The proposed Gautrain Rapid Rail Link (GRRL) will require approximately 15 km of double or twin high-speed rail track tunnels located for the greater part beneath the northern suburbs of Johannesburg, including Houghton, Rosebank and Sandton. During the Environmental Impact Assessment (EIA) it became clear that potential surface vibration above and in the vicinity of the tunnels was a matter of serious concern to the residents of the affected properties and that the impact required assessment. The general method proposed is based on a US Department of Transportation, 1998, publication in which abase vibration curve derived for typical high-speed passenger trains is adjusted for the topological, geological and other features to predict the surface vibration and the associated ground-borne noise. The predictions indicate that some isolated areas might be impacted but that the impact will likely be limited, and it is possible to mitigate the impact using suitable track construction methods and track support systems.

Jan 1, 2004

By E. J. Maunders

This paper describes briefly a computerised model of the South African electricity system which has been developed jointly by the Atomic Energy Board and the Electricity Supply Commission. The results of an analysis of this system have been subjected to a fairly extensive sensitivity analysis which reveals that up to the year 1990 between 680 and 700 million tons of coal will be required for electric power generation, together with between 7 000 and 10 000 tons of uranium. This result is fairly insensitive to data variations, but the prediction of a cumulative requirement up to the year 2000, of between 1 300 and 1 800 million tons of coal and 25000 to 70000 tons of uranium, proves to be very data-sensitive.

By W. van Antwerpen, J. Guzek, A. Lane

Strategy is about making choices. Mining companies choose to do certain things and not to do other things. Mining is a long-term business, and the choices made typically have large investments attached to them, long payback periods, and significant socio-economic consequences. In today’s uncertain world, it is important to make the right choices. The mining industry in South Africa finds itself in a difficult situation. Operating conditions are tough, the socio-political environment is complex, and financial performance is under pressure. The choices made by all the stakeholders in this industry in the short term will shape the future of the industry. This paper characterizes some of the big, difficult decisions faced by the mining industry in the South African context, and discusses how these decisions could be approached in a fact-based and robust way.

Jan 1, 2015

The 88th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at Kelvin House, Johannesburg, on Wednesday, 14th August, 1985. Mr J.D. Austin (President) was in the chair and declared the meeting open at 16h00.

Jan 1, 1985

The 87th Annual General Meeting of the South African Institute of Mining and Metallurgy was held at Kelvin House, Johannesburg, on Wednesday, 15th August, 1984. Professor R.P. King (President) was in the chair, and declared the meeting open at 16h00.

Jan 1, 1984

1. Book review Technology of metal powders- recent developments, edited by L. H. Yaverbaum. New Jersey, Noyes Data Corporation, 1980. 400 pp. (Reviewer: B. K. Loveday) 2. New books The use of microprocessors, by M. Aumiaux. New York, Wiley, 1980. 176 pp. $25,50. Aluminium smelter technology, a pure and applied approach, by K. Grojtheim and B. J. Welch. Diisseldorf, Aluminium-Verlag GmbH (P.O. Box 1207, D-4000, Federal Republic of Germany). 146 pp. DM48. Coal-bridge to the future. New York, Harper & Row, 1980. $35. System modeling and response.. theoretical and experimental approaches, by O. Doebelin. New York, Wiley, 1980. 576 pp. $26. Environmental and climatic impact of coal utilization, edited by J. J. Singh and A. Deepak. New York, Academic Press, 1980. 646 pp. $39,50. Proceedings of the Third European Conference on Mixing, York, England, April 1979, edited by H. S. Stephens and C. A. Stapleton. BHRA Fluid Engineering (Cranfield, Bedford Mk43 OAJ, U.K.), 1980. 2 volumes. 500 pp. $50. Lignite technology, edited by P. Nowacki. New Jersey, Noyes Data Corporation, 1980. 228 pp. $42. The application of rock mechanics to cut-and jill mining. London, Institution of Mining and Metallurgy, 1980. Papers presented at the Fifth International Symposium on Jet Cutting Technology, Hanover, Federal Republic of Germany, June 1980, edited by H. S. Stephens and B. Jawis. BHRA Fluid Engineering (Cranfield, Bedford Mk 43 OAJ, U.K.), 1980. 438 pp. £38. World coal resources.. methods of assessment and results, by G. Fettweis. Amsterdam, Elsevier, 1979. 425 pp. $80,50. Geophysical and geochemical techniques for exploration of hydrocarbons and minerals, edited by M. Sittig. New Jersey, Noyes Data Corporation, 1980. 300 pp. $40. Financial Times mining international year book 1980. Longman Group Ltd (Periodicals and Directories Division, Longman House, Burnt Mill, Harlow, Essex CM20 2JE, England). £24 surface, £34 airmail. National Symposium on the Availability of Strategic Minerals, edited by M. J. Jones. London, Institution of Mining and Metallurgy, 1980. 109 pp. 3. NIM reports Report No. 1941 The recovery of chromite and platinum from the UG-2 Upper Chromitite Layer .of the Bushveld Complex at the Pandora Mine (first published 10th Mar., 1978). Report No. .2012 A mineralogical investigation of borehole cores from the Trompsburg Complex (first published 6th Apr., 1979). Report No. 2038 The leaching of sphalerite in acidic ferric sulphate media in the absence of elemental oxygen. Report No. 2052 An investigation of the impurities in native gold by neutron-activation analysis. Report No. 2056 The mineralogy and geochemistry of the copper, lead, and zinc sulphides of the Otavi Mountainland. Report No. 2058 A n elementary introduction to image analysis - a new field of interest at the National Institute for Metallurgy. Report No. 2059 Distributed computer control of industrial processes. Report No. 2060 The analysis, by atomic-absorption spectrophotometry, of activated charcoal.

Jan 1, 1980

The 102nd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 18th August, 1999. Obituaries The President announced the death, during the year, of the following members: Honorary Life Fellows and Past Presidents D.D. Howat Life Fellows O. Deane, J.S. van Zijl Fellow A.A. Hejja Retired Fellows A.L. Forder, C.B. Parker, A.C. Petersen, F.W.J. Ross Members J.S. Stanko, D.H. Gray Retired Member P.K. Bredell Retired Associate I.S. van Eyssen In memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1999

By Y. Tanaka, H. Miki, Y. Aoki, H. Okamoto, G. P. W. Suyantar, T. Hirajima

Due to environmental limitations and the scarcity of freshwater, flotation using seawater or desalinated seawater as process water becomes more common for mining operations. On the other hand, seawater has been reported to affect the flotation behavior of sulfide minerals. Few reports are available on influence of pyrite depression, recycled seawater and lime consumption on flotation by using seawater. In this study, the flotation tests were performed using ore sample to investigate the effect of pH with seawater and process water used in plant on the flotation behavior in a laboratory-scale flotation cell and a pilot plant-scale. The results of laboratory scale flotation indicated that copper and molybdenum flotation kinetics decreased with increasing pH. Furthermore, the iron (mainly pyrite) recovery decreased with increasing pH. The pilot plant-scale flotation test showed that water with a higher concentration of magnesium and calcium (plant processes water) consumed a higher amount of lime. Because of low lime consumption and high copper and molybdenum recovery and grade, pH 8 is suitable compared with pH 8.5 for flotation. Keywords: seawater, process water, copper-molybdenum rougher flotation, pH, pilot test

Jan 1, 2020

By O. O. Ogunmodimu, D. K. Weatherley, M. S. Powell

Discrete element methods (DEM) have provided the ability to resolve the complex phenomena experienced by ore within comminution devices such as tumbling mills. The new developments in DEM techniques and the corresponding increase in computational power have made it more feasible to study the movement of individual ore particles as they traverse a tumbling mill. A range of information can be extracted on individual particle impact histories, such as kinetic energy at the time of collision, velocities of individual particles, per-particle stress tensors, impulse, and collision energy. DEM codes have been modified to provide required information that can be analysed in associated software to investigate the impact of varied operational parameters on the resultant granular dynamics. This paper explores the reaction of individual ore particles to the breakage environment within a tumbling mill using DEM techniques and studies the stressing conditions that would lead to either impact or abrasive breakage. Keywords: DEM, comminution, tumbling mill, breakage

Jan 1, 2020

One of the seminal pioneering papers in reserve evaluation was published by Danie Krige in 1951. In that paper he introduced the concept of regression techniques in providing better estimates for stope grades and correcting for what later became known as the ‘conditional bias’. In South Africa, the development of this approach led to the phenomenon being dubbed the ‘regression effect’, and regression techniques ultimately formed the basis of simple kriging in Krige’s later papers. In the late 1950s and early 1960s, Georges Matheron (1965) formulated the general theory of ‘regionalized variables’ and included copious discussion on what he termed the ‘volume-variance’ effect. Matheron defined mathematically the reason for, and quantification of, the difference in variability between estimated values and the actual unknown values. In 1983, this author published a paper that combined these two philosophies so that the ‘regression effect’ could be quantified before actual mining block values were available. In 1996 and in some earlier presentations, Krige revisited the regression effect in terms of the conditional bias and suggested two measures that might enable a practitioner of geostatistics to assess the ‘efficiency’ of the kriging estimator in any particular case. In this article, we revisit the trail from ‘regression effect’ to ‘kriging efficiency’ in conceptual terms and endeavour to explain exactly what is measured by these parameters and how to use (or abuse) them in practical cases.

Jan 1, 2015

By M. H. Moys, J. Engelbrecht, N. Terblanche

Interface levels in flotation columns are generally measured with the aid of a pressure-sensitive Instrument, e.g. a differential-pressure cell. This paper criticizes the use of this type of measurement, and discusses other methods that are claimed to give more accurate measures of interface levels. The paper focuses on the development of methods based on the measurement of conductivity across the froth-slurry interface. These are often sabotaged by variations in the conductivity of the feed slurry, particularly when the pH of the slurry IS being controlled, e.g. In sulphide flotation. Methods of improving the accuracy and reliability of this technique are described. The result IS a robust, easy-to maintain level-control scheme that successfully rejects large disturbances in plant operation (including a 5:1 change in slurry conductivity) while controlling levels to an accuracy of I 4 cm.

Jan 1, 1992

By J. Kuijpers

Failure and fracturing are often regarded as synonymous. While this is obviously true in an environment dominated by tensile stresses, it is still not clear how failure and macro fracturing are related in a compressive stress environment. Excavations at great depths are typically subjected to compressive stresses only. The fracturing observed around such excavations is therefore commonly assumed to be induced by such compressive stresses. The physics of such a phenomenon have unfortunately never been explained properly, so that the formation of these so-called extension fractures still remains a mystery. As the presence of fractures is an important factor affecting the stability of underground excavations, it is of practical relevance to understand their formation. In this paper, a possible explanation is proposed. It is argued that fracturing in a compressive stress environment is a secondary effect. Primary failure, in the form of micro fracturing and associated damage is assumed to precede the major fracture processes. The fractures are thus generated in response to material failure and may not directly be the cause of failure. The implications for material response and behaviour are discussed. Keywords: micro fracturing, macro fracturing, extension fractures, failure, compressive stresses, damage, excavations.

Jan 1, 2000

By N. Mangadoddy, M. Padhi

The simulation of multi-component classification with modified viscosity model is the key focus in the current study. The classification of the ores using hydrocyclone is a renowned process and has a convoluted flow separation phenomenon. The highly turbulent flow inside hydrocyclone depends on the operating and design parameters apart from the feed mixture. Slurry viscosity also plays a dominant role in the classification of solid particles under the centrifugal settling action. A heterogeneous mixture with different components would result in different settling and rheological behaviour of particles’ suspension in the water medium. The newly proposed multi-component viscosity model (Mandakini et al. 2020) is implemented as a user-defined function to define the material property during the CFD study of the mixture rheology inside hydrocyclone classifier. The multiphase and turbulence model is solved using the modified Algebraic Slip Model and Large Eddy Simulation model. A comparison of the predicted component performance curves is evaluated with and without the corrected viscosity model. The density and size effect on the particle phase distribution inside the classifier are compared, where the misplacements of the finer particles are carefully assessed. Validation of the component classification in hydrocyclone with the laboratory experiments found a close agreement with the rheology based CFD data. Keywords: Dual-component, multi-component viscosity model, double-gap rheometer, computational fluid dynamics, high solids concentration

Jan 1, 2020

By M. Ndabeni, J. H. van Vreden, M. Le Roux, Q. P. Campbell

It is not uncommon for gold slurry ponds or screen oversize dumps to contain several different types of carbon-rich contaminants. These contaminants act as robbers of dissolved gold which has a detrimental effect during the downstream carbon-in-leach (CIL) or carbon-in-pulp (CIP) processes. With a renewed interest in the reprocessing of contaminated gold waste ponds and dumps, preconcentration of the feed to either the CIL or CIP process becomes important to maximise profits from these resources. An added advantage in removing these resources, which were once thought of as being uneconomical, is the availability of land that can further be rehabilitated for community development projects. For gravity separation, an example of suitable technology is the Reflux Classifier (RC), which can be used for the separation of materials of different densities and can be used as a pre-concentration step. In this project, a laboratory-scale Reflux Classifier was used to pre-concentrate a gold-bearing sample obtained from a waste dump situated to the east of Johannesburg, South Africa. The material had an average gold grade of 1.9 g/ton and a carbon content of 10%. This material was first fed to a semi-batch Reflux Classifier that was used to fractionate it into several different density intervals by varying the fluidisation water feed rate, followed by continuous runs at fixed water flow rates. The results showed that a cumulative gold recovery of 60%, carbon recovery of 85%, and mass pull of 41% was possible for a fluidisation water feed rate of 15 L/min, while a rate of 20 L/min resulted in a gold recovery, carbon recovery and mass pull of 83%, 92% and 79% respectively, which translated into a concentrate gold grade above the set target of 3 g/ton. Continuous operation at 20 L/min yielded an underflow stream with 84% gold recovery at a grade of 5.4 g/ton. Keywords: Reflux Classification, gold recovery

Jan 1, 2020

The 93rd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Highveld Room of the Carlton Hotel in Johannesburg on Wednesday, 15th August, 1990. Obituaries The President announced the deaths of the following Members of the Institute:

Jan 1, 1990

The Gold Medal of the Institution for Mining and Metallurgy for 1978 was awarded to Adriaan Louw at the Annual General Meeting of that Institution in London on 17th May, 1979. The award was made for distinguished services to the mining industry in South Africa.

Jan 1, 1979

By A. Nhasengo

Paper written on project work carried out in partial fulfilment of B. sc. Eng (Mining Engineering) The purpose of this investigation was to assess the mining strategy for steep reefs at Mine A mine in 2005 and 2006. Reefs steeper than 35° were discovered when production commenced at the mine. At that time reefs steeper than 35° were not popular in South African tabular gold mines, therefore new techniques of mining them had to be developed. The underhand mining method was chosen for this purpose. The project was about assessing ventilation, support costs, local support cycles, adherence to the mine?s support standards, mine planning and efficiencies of the underhand mining method. The project work was covered by doing a literature research for underhand mining methods and performing a literature review of the mining methods, support methods, ventilation standards at Mine A. Underground visits were conducted at Mine A mine for data collection, and Mine B was visited to obtain information on support costs and efficiencies. During the investigation it was realized that the underhand mining method was an appropriate method for mining steep reefs; however, there were some challenges related to ventilation and support installation. Efficiencies could be realized with the underhand mining method and planning and scheduling were not different from breast mining.

Jan 1, 2007

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Jan 1, 2009