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By M. Lange

The postulation that primary platinum group metal (PGM) matte will chemically react with magnesia-chrome bricks when temperatures exceed 1500°C was tested. Magnesia-chrome brick samples were heated in contact with matte at 1300°C to 1750°C for 30 minutes, after which the refractory samples were analysed using reflected light microscopy and scanning electron microscopy. The samples were all completely penetrated by matte. As the temperature increased the matte also penetrated the fused aggregate grains and disintegrated them. The chromium concentration of the matte inside the refractory samples was found to be slightly higher than that of the bulk matte. At temperatures of 1500°C and higher, MgO, FeO, and magnesium-rich silicate crystals could be identified in the matte directly adjacent to the refractorymatte interface. Phase relations clearly indicated that chemical reactions take place between primary PGM matte and the magnesiachrome refractory material at temperatures above 1500°C, but that these reactions are more complex than expected from FactSAGE® calculations.

Jan 1, 2014

By Didier Kasongo NYEMBWE

The paper circumscribes the base metal casting industry in Southern Africa. It essentially consists in the founding of copper and zinc alloys. The challenge related to the scarcity and the unaffordable quality patterns and dies faced by the industry is discussed. New manufacturing technologies for foundry tooling called Rapid Prototyping that can possibly be used to alleviate the above mentioned challenge are then presented and their benefits assessed.

Jan 1, 2007

By K. Schwerdtfeger

Data are presented on the effect of iron oxide on the electrical conductivity of CaO-SiO2-FeO-Fe2O3melts, and on limiting current and impedance in direct current or alternating current charge transfer at iron electrodes. The strong influence of iron oxide content can be utilized for in situ determination of total iron oxide content and Fe3+/Fe2+ratio. The possible probe designs are presented and the principles and procedures of the measurements are explained. Keywords: in situ probe for iron oxide determination in steelmaking slags, electrical conductivity of CaO-SiO2-FeO-Fe2O3slags, direct current over voltage and alternating current impedance at iron/slag electrodes.

Jan 1, 2004

By H. H. McGregor

SYNOPSIS Changes in the national productivity (gross national product per head of the population) have been assessed in order to derive a target figure for the required annual increase. The conclusion reached IS compared with the targets of the economic development programme of the Republic. Productivity and management structure in the gold mining industry is then analyzed together with investment in plant, machinery and equipment for rock handling purposes. The conclusion is drawn that productivity improvement does not appear to have accorded with the massive expenditures in plant and equipment, and in augmented management. The productivity of the manufacturing and construction sectors of the economy has been examined. The principal difficulty is that the main avenue of approach is the value of product divided by the total labour force. This introduces inflationary questions, and the use of a suitable deflator becomes of prime importance. Severa1 different methods of assessing the productivity improvement in the industrial sector have been used with what is regarded as a comparatively high degree of compatibility. Improvements in productivity in the manufacturing industry up to 1966 appear, from the information available, to have substantially exceeded comparable figures for the mining industry. There is however evidence that thereafter productivity of the manufacturing industry has not maintained this satisfactory rate of increase. If the economy is to achieve the planned rate of expansion, there is no doubt that greater attention to this aspect will be required in the future than has been accorded to it in the past.

1. New Publications Tin and its uses no. 140. Greenford (England), International Tin Research Institute, 1984. Catalogue. English translations of German standards 1984. Berlin, Beuth Verlag GmbH, 1984. Mining and mineral processing operations in Canada 1983. Ottawa, Canadian Government Publishing Centre, 1984. $6.00. Canadian mineral deposits not being mined in 1983. Ottawa, Canadian Government Publishing Centre, 1984. $6.00. 2. Mintek Publications Report M42D The recovery of tantalite and cassiterite from a bulk sample of pegmatite supplied by Falconbridge Explorations Limited. (First issued 1982.) Report M46D Tests on the nature and reduction of the chlorine in fluorspar concentrate from the western Transvaal. (First issued 1982.) Report M58D An electrochemical process for the recycling of tungsten carbide scrap. (First issued 1982.) Report M59D Testwork on samples of oxidized ore from the Potgietersrus Prospect. (First issued 1982.) Report M60D The production of electrolytic manganese dioxide from furnace sludge. (First issued 1983.) Report M64D Isotope-source neutron-activation analysis for the determination of manganese in bulk samples. (First issued 1982.) Report M128 The determination of cyanide in hydrometallurgical process solutions and effluents by ion chromatography. Report M132 Mineralogical parameters influencing the acid-bacterial leachability of low-grade nickel ores. Report Ml34 The NIMROC reference materials: revised values for thorium, yttrium, lanthanum, and the rare-earth elements. ReportM140 The effect of physical and chemical factors on the corrosivity of a synthetic mine water. Report Ml44 The development of standard procedures for the evaluation of magnetite for use in heavy-medium separation. Report M145 A preliminary study of the mineralogy of the nickel occurrence at Mabilikwe Hill, northern Transvaal.

Jan 1, 1984

By D. F. Malan

This paper presents an overview of work conducted over several years to investigate the continuous stope closure profiles recorded in tabular excavations and the use of this data as a hazard indicator. In spite of the brittle nature of the rock, measurements in gold mines and intermediate depth platinum mines revealed a significant time-dependent closure component. Various approaches to simulate the time-dependent closure have been investigated. Viscoelastic theory is able to simulate the time-dependent closure behaviour, but there are subtle problems with the use of this theory as it cannot simulate the failure processes in the rock. To overcome these problems, continuum and discontinuum elasto-viscoplastic models were developed by the authors. Discontinuum models have the advantage of being able to simulate the creep behaviour of prominent discontinuities. Development of these models has led to useful insights into rock mass deformation and has made the numerical simulation of parameters, such as rate of mining, possible for the first time. A number of practical applications for the mining industry have been developed from this study. Among these are the delineation of geotechnical areas using closure data, use of the data as a hazard indicator and to give warning of large collapses in the platinum mines, identification of areas to be preconditioned in the gold mines, measurement of the effectiveness of preconditioning and improved da

Jan 1, 2007

By W. O. Ortlepp

This note considers the most fundamental concepts of support design for deep underground openings and discusses them briefly in the context of tabular stoping and deep hard-rock tunnelling. It concludes that the conventional re-bar, mesh, and lacing methods that have been widely used in deep gold mines are quite inappropriate for the support of highly stressed tunnels. The following is suggested as the criterion for adequate dynamic support: the energy absorbed by a support unit (yielding through some acceptable limited displacement) should exceed the kinetic energy generated by the mass of rock that is intended to be retained by that unit.

Jan 1, 1995

By W. Abdellah

The purpose of this paper is to establish a qualitative method to estimate the risk level (e.g. rating and ranking) resulting from mining activity. Risk is the product of two factors: probability of failure and cost of consequences. A resultant assessment scale matrix is then used to assign a risk index value which is directly proportional to the potential for excavation instability. A case study, the No. 1 Shear East orebody at Vale?s Garson Mine in Sudbury, Ontario will be examined. A three-dimensional, elastoplastic, finite difference model (FLAC 3D) is presented for a mine development intersection situated 1.5 km below ground surface. The developed assessment scale matrix is used to estimate risk index for intersection (2981) located on 5000 level. The results are presented and categorized with respect to risk-index value, probability of instability, cost of consequence, and mining stage.

Jan 1, 2014

By N. R. Shoko, J. Chirasha

Zimbabwe Alloys has been producing Low Carbon Ferrochrome since 1953. A number of operational and technical advances have been made since then. Some of these advances improved production significantly. Process control, however, remained a challenge not only in the production process itself but also in the handling of finished product. In addition the handling of the slag created an environmental problem. Process control issues were addressed by Zimbabwe Alloys Limited and Japan Metal & Chemicals (JMC) entering into a Technical Transfer Agreement. The aim of the technical transfer was to improve production, alloy quality and, thereby, the financial performance of Zimbabwe Alloys. In addition, the Low Carbon Ferrochrome production process was made environmentally friendlier by modifying the final slag handling methodology. The aspects that are covered and discussed in this paper are, ladle refractory lining changes, improved control of the process, changes in the alloy casting methodology and granulation of the final slag. The improved control of the process was enhanced by the conversion from ladle duplexing to argon purging, introduction of on-line sampling and introduction of second stage process. The combined effect of the above was a significant improvement on on-grade material production, production efficiencies, unit cost of production and a cleaner working environment.

Jan 1, 2004

By M. A. W. Bryson

Platinum group metals are extracted almost exclusively in South Africa from three very different zones in the Bushveld Igneous Complex, called the Plat, Merensky, and the UG-2 reefs. The Plat reef is currently being exploited only by Anglo American Platinum, whereas the Merensky reef is exploited by them, Impala Platinum, Northam, and Lonplats. The UG-2 reef, on the other hand, is also processed by these producers, but Kroondal and Barplats have operations that exclusively treat ore from this reef. At present the extraction of pgms from ores in South Africa follows the traditional route of upgrading to a concentrate in a minerals processing circuit, further upgrading to a matte in a smelter, and final upgrading and separation of the individual metals in a refinery. Thus all operations that extract pgms require a minerals processing circuit, the design and performance of which is a topic of much interest, as it is a poorly understood and not a very efficient process in relative terms, compared to the other processes. Recoveries across the minerals processing circuit of between 75 and 90% are the norm.

Jan 1, 2004

By A. Rejeb, A. Millard

ABSTRACT: An evaluation of the importance of the thermo-hydro-mechanical couplings (THM) on the performance assessment of a deep underground storage design has been made as part of the international DECOVALEX III project. It is a numerical study that simulates a generic repository configuration in the near field in a granite medium. The thermo-hydro-mechanical evolution of the whole configuration is simulated over a period of 100 years. The model used to represent the unsaturated behaviour of the various porous media makes allowance for moisture transfers through the effect of thermal and water gradients. The paper presents a comparison of the temperature, water pressure and stress fields obtained by TM, TH, HM and THM coupled calculations. The results demonstrate that temperature is hardly affected by the couplings. In contrast the influence of the couplings on the mechanical stresses is considerable. This is attributed to the key role that water has on bentonite swelling or shrinkage effects that are dependent on its saturation level variations. KEY WORDS: Modelling, thermo-hydro-mechanical couplings, temperature, pressure, stress. ZUSAMMENFASSUNG : Im Rahmen des internationalen Projekts DECOVALEX III wurde untersucht, wie groß der Einfluss thermisch-hydraulisch-mechanischer Kopplungen (THM) auf die Leistungsfähigkeit eines Konzeptes zur Lagerung hoch radioaktiver Abfälle zu bewerten ist. Bei dieser numerischen Behandlung wird eine generelle Lagerungskonfiguration in granitartigem Milieu simuliert. Die thermisch-hydraulisch-mechanischen Prozesse werden für eine Dauer von 100 Jahren simuliert. Bei dem Modell, mit dem das Verhalten der verschiedenen, unterschiedlich porösen Milieus in ungesättigtem Zustand dargestellt werden soll, werden die Feuchtigkeitstransporte infolge thermischer und hydraulischer Vorgänge berücksichtigt. Verglichen werden in diesem Artikel verschiedene Temperatur-, Wasserdruck- und Beanspruchungsfelder, die sich aus TM-, TH-, HM- und THM gekoppelten Berechnungen ergaben. Dabei stellte sich heraus, dass die Temperatur nur gering von den Kopplungen berührt wird. Die Einflüsse der Kopplungen auf die Mechanik sind hingegen bedeutend; ausschlaggebend dafür ist der Faktor Wasser, der den Bentonit je nach Sättigungsgrad quellen oder trocknen lässt. SCHLÜSSELWÖRTER: Modellbildung, thermisch-hydraulisch-mechanische Kopplungen, Temperatur, Druck, Beanspruchung. RESUME : Dans le cadre du projet international DECOVALEX III, une évaluation de l’importance des couplages thermo-hydro-mécaniques (THM) sur les performances d’un concept de stockage de déchets fortement radioactifs a été menée. Il s’agit d’une étude numérique simulant une configuration générique de stockage en champ proche dans un milieu granitique. L’évolution thermo-hydro-mécanique de l’ensemble est simulée sur une période de 100 ans. Le modèle utilisé pour représenter le comportement non saturé des différents milieux poreux prend en compte les transferts d’humidité sous l’effet de gradients thermiques et hydriques. L'article présente une comparaison des champs de température, de pression d’eau et de contraintes obtenues par des calculs couplés TM, TH, HM et THM. Les résultats montrent que la température est peu affectée par les couplages. En revanche, l’incidence des couplages sur la mécanique est importante; ce qui est attribué au rôle majeur joué par l’eau à travers les effets de gonflement ou de retrait de la bentonite selon la variation de son degré de saturation. MOTS-CLEFS : modélisation, couplages thermo-hydro-mécanique, température, pression, contrainte.

Jan 1, 2003

An investigation into the stability of large open stopes at Premier diamond mine, Culinan, South Africa, is described. The open stopes are located in a weak kimberlite orebody, directly underneath a 75 m-thick sill of gabbro. Two and three-dimensional stress analyses were carried out in a back-analysis of the stresses and failure around the first open stope created under the sill. The results were used in the prediction of the future stability of the planned open stopes, intervening pillars, and sill.

Jan 1, 1987

By J. N. van de Merwe

CONTRIBUTION BYH. WAGNER AND T.T. OZAN The paper by Dr J.N. van der Merwe makes an important contribution to the design of bord-and-pillar workings in the Vaal basin. It has been recognised for some time that the strength of coal seams in the Vaal basin is markedly lower than that of coal seams in other coal-mining districts in South Africa. However, there was insufficient data to quantify how much weaker the extensively jointed coal the Vaal basin is. A number of recent pillar collapses that occurred at Sigma colliery, the only remaining underground colliery in the Vaal basin, provided Dr Van der Merwe with an opportunity to make this assessment.

Jan 1, 1993

By O. A. W. Strydom, J. C. M. Wethmar, P. R. Jochens, D. D. Howat

Liquidus temperatures in the Cr-Fe-Si system in the composition range representative of ferrochromium-silicide produced in South Africa J. C. M. Wethmar, B.Se. (Eng.) Rand D. D. Howat,U B.Se. (Glas.), Ph.D.. F.I.M. P. R. Joehens, Pr.Eng., M.Sc. (Eng.) Rand, Ph.D., A.I.M. O. A. W. Strydom, M.Sc., Ph.D. Alloys in the composition range of chromium, 20 to 50 per cent, iron, 10 to 30 per cent, and silicon, 25 to 55 per cent, were subjected to both differential thermal analysis and the classical quench method so that the liquidus temperatures of ferrochromium-silicide alloys could be determined. The results are presented as liquidus curves on pseudo-binary sections at various ratios of chromium to iron and as liquidus isotherms in the ternary section.

By M. Gericke

Over the past few decades the commercial application of heap bioleaching technology for the extraction of base metals has become increasingly important, due mainly to the depletion of high-grade ore reserves. Heap bioleaching is widely used for the extraction of copper from secondary copper sulphide ores. The design and engineering aspects of the process have received considerable attention, but issues related to the microbiology of the process have been subjected to less rigorous scrutiny. The major role of micro-organisms in bioleaching processes is to catalyse the regeneration of ferric iron and protons, from ferrous iron and by sulphur oxidation respectively. It is accepted that even the most carefully engineered heaps are heterogeneous in terms of temperature, pH, the presence of anaerobic pockets, irrigation efficiency, and dissolved solutes. Since interactions between solution chemistry, mineralogy, and microbial populations exist in heaps, a better understanding of the correlation between microbial numbers and types with changes in these chemical and physical profiles with time would be beneficial during process design and operation of heaps, and could result in faster start-up times and higher metal recoveries. This paper reviews the role of microbiology in heap bioleaching processes. Aspects such as microbial diversity, identification and monitoring of cultures, inoculation strategies, colonization behaviour, and tolerance to metals and salts are discussed, and the potential contribution of the knowledge to the improvement of the operation and design of heap bioleach processes assessed. Conclusions are drawn with respect to the role of genetic engineering, heap inoculation practises, and remaining areas for future heap bioleaching research and development.

Jan 1, 2012

YEAR 1943-1944 Vol. 44 Page A major change-over in the ventilation of a deep level mine, by F. G. Hill and E. C. Ranson, 27; Discussion 56, 62, 67, 71, 72, 79, 123, 129 131 A note on the quarrying of surface limestone in the Sinai Desert, by V. L. Bosazza.. .. 59 Mining with diamond drills at the Nkana Mine of the Rhokana Corporation, Limited, Northern Rhodesia, by W. A. Odgers and A. G. Stirling, 95; Discussion 117, 121, 122 123 On silicates and dusts from the Witwatersrand gold mines (some preliminary notes), by J. J. Frankel, 169; Discussion .. 178 Presidential Address-Review of the rock pressure problem, by C. Biccard Jeppe, 3; Discussion 11,15 17 The chemistry, production and application of plastics, by P. N. Lategan, 138; Discussion 151 153 YEAR 1944-1945 Vol. 45 Page A microtechnique for the size-grading of mine dust, by S. R. Rabson, 34; Discussion 49, 50, 52 55 Activated carbon for regenerating used lubricating oil, by F. J. Tromp and J. J. Matthee 90 A contribution to the study of the production of zeolites, by C. C. le Grange and A. J. Petrick 235 A laboratory method for the determination of the suitability of South African coal and coal blends for the manufacture of metallurgical coke, by R. F. J. Teichmann .. .. 202 Copper containing cements for self-sanitising surfaces, by R. S. Young and H. L. Talbot 156 Notes on some sulphide minerals from the Far East Rand, by E. Mendelssohn, 84; Discussion, 88 89 Presidential Address-A review of underground support on the Witwatersrand with its Bearing on the Problem of ultradeep mining, by P. J. Louis Bok, 3; Discussion, 24, 25 27 Scientific management with particular application to a Witwatersrand gold mine, by J. S. Ford, 63; Discussion, 77, 80, 82 83 Some aspects of rock-drilling practice (the Witwatersrand gold field), by C. J. Irving, 163; Discussion, 185, 190 *197 Temperature measurements in a mine on the Witwatersrand with an electrical resistance thermometer, by O. Weiss, 127; Discussion, 136 137 The measurement of the geo-thermic gradient by means of the clinical thermometer, by R. A. H. Flugge-de Smidt, 105; Discussion, 136 137 The micro-chemical determination of free and combined silica in mine dust, by S. R. Rabson, 43; Discussion, 49, 50, 52 55 The oxidation of pyrites associated with South African coals, by R. F. J. Teichmann 141 YEAR 1945-1946 Vol. 46 Page Air cooling plant, No. 4 Shaft, City Deep, Limited. A review of layout and results achieved, by H. W. Unwin, A. Malcolm and R. E. Campbell Pitt, 66; Discussion, 100, 102, 103, 106, 110 115 A preliminary note on the Waterberg coal field as a possible source of coking coal, by P. E. Hall 124

By K. N. Karparov

The classical limit equilibrium methods are suspected to be ineffective in predicting the potential for highwall failure in many instances in coal mines around the world. Slope engineers have for many years recognized a block thrust failure mechanism for slope failures, but little work had been done before 2000 to explain the actual mechanisms which must be responsible for the failure. The main reason for this is that limit equilibrium methods implicitly assume rigid blocks, and the resulting force equations must be satisfied everywhere simultaneously for them to have any meaning. This paper will show that the material involved in the slope failure is not rigid; indeed it undergoes considerable permanent deformation during failure. This observation allows the authors to treat the block boundaries independently, because they need not maintain a constant spatial relationship with one another, as is assumed in other methods. To enable analysis of this type the authors assume that the weight of the blocks is evenly distributed. This is reasonable, because the slope material is not strong enough to be self-supporting without some sort of constraint, or strong enough to be able to apply point loads to the surrounding material. The purpose of this paper is to extend the practical application of the analytical method developed from mechanism studies to provide an objective assessment of the risk of slope failure, and therefore guidelines for more stable slope designs. This work is based on studies carried out on two failures in an open pit coal mine in South Africa, and provides a methodology to assess the potential for failure more objectively than is possible with currently accepted methods, while at the same time remaining sufficiently simple to allow a ?back of the cigarette box? assessment by geotechnical engineers on site.

Jan 1, 2009

By W. J. Kempson

As a result of the rising electrical energy costs in South Africa, a method was sought to reduce the overall electrical consumption of typical shaft systems. A typical shaft configuration was analysed and the primary energy consumers were identified. The ventilation fans for this system were found to consume 15% of the total energy of the shaft system. It was calculated that more than 50% of this energy is consumed by the shaft itself, more specifically, by the pressure losses that occur in the shaft as the ventilation air passes through it. In order to ensure that the theory being used for the evaluation of these shaft systems is accurate, a total of five shafts were instrumented and the actual pressure losses over the shafts plotted against time. These shafts were then analysed from a theoretical perspective. Finally, in order to ensure a thorough understanding of the behaviour of the ventilation air in shaft systems, the systems were simulated using computational fluid dynamics (CFD) techniques. There were significant discrepancies between the theoretical analysis and the CFD simulation during the initial comparisons. This discrepancy lessened as the complexity of the CFD models increased, until when the complete shaft was modelled using the full bunton sets, the pipes, and the flanges, the difference between the theoretical evaluation and the CFD simulation was small. This result demonstrates that the theory is insufficient and that the interrelated effect of the buntons and fittings has not been fully appreciated by current theory. The final phase of the work presented here was to evaluate the costeffectiveness of using different bunton shapes and shaft configurations. It is shown that the increase in the pressure losses and therefore the direct operating costs of the shaft can vary by as much as 80%, depending on the bunton configuration chosen. The placement of the piping in the shaft can increase the pressure losses, and therefore the direct operating costs of the shaft, by as much as 12%, depending on the placement of the piping in the shaft; this effect includes the use of flanges. The use of fairings on a large cage can reduce the resistance that the cage offers to the ventilation flow by as much as 30%. This, however, does not translate into a direct saving because as the cage moves through the shaft, the overall effect is transitory. These savings can be significant when the items highlighted in this work are applied correctly. Keywords shaft design, ventilation, energy consumption, modelling, CFD.

Dec 1, 2013

Proceedings of the Ninth International Symposium on Techniques for Decision-Making in the Mineral Industry, Montreal, June 1970. The Ninth International Symposium on Techniques for Decision-Making in the Mineral Industry was sponsored by The Canadian Institute of Mining and Metallurgy, McGill University and Ecole Poly technique. The programme included 71 papers on various topics, as follows: Market Analysis and Logistics Planning; Quantification of Geological Variables; Blending; Capital Investment Decisions; Mining; Financial and Economic Analysis; Search for Mineral Deposits; Market Forecasting and Strategies; Operations Research in Process Modelling; Ore Reserve Estimation; Management Information Systems; Optimization and Control of Mineral Processes. In addition to general sessions, a special feature of the Symposium was Executives' Day, which was held to provide top and middle management with a broad understanding of the usefulness of decision-making techniques and their role in the mining organization. Panel Discussions and two keynote speakers provided a review, in non-technical terms, of the areas in which decision-making techniques have proven valuable. The present volume contains 65 papers submitted for publication, along with a complete account of the Executives' Day discussion. It is broadly divided according to the above subject headings. Approximately 550 pages, illustrated. Price: $15.00; $12.00 to students, plus 50 cents for handling costs. Order now from CIM headquarters: Canadian Institute of Mining and Metallurgy, 906-1117 Ste. Catherine St. W. Montreal 110, Quebec.

By R. K. Brummer

A simplified two-dimensional plane strain numerical technique for the non- linear modelling of a tabular mining excavation in brittle host rock under high stress conditions is described. The model has been developed using relatively straightforward assumptions based on extensive underground investigation of the fracturing and deformation of rock at the stope face in deep gold mines on the Witwatersrand, together with observed rock behaviour under laboratory conditions. The reef rock is modelled as a linear string of yielding elements which interact horizontally, while the elastic rockmass remote from the reef is modelled using boundary element techniques. This elementary technique is shown to produce results which agree closely with the observed behaviour of the fractured rock during the mining of a remnant pillar

Jan 1, 1987