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By C. Kirmanli

The purpose of this paper is to develop an expert system for hydraulic excavator and truck selection in surface mining. Hydraulic excavators and trucks are finding increasing applications in mining operations. Hydraulic excavators are extensively used especially when bringing electricity to rural areas is difficult and for small-scale mining. This paper describes an expert system, which selects the optimum hydraulic excavator truck configuration such that unit production cost is minimized and technical constraints such as geological, geotechnical and mining constraints are satisfied. The system has four modules: user interface, rules and an methods, databases and output module. The expert system in this study is developed within KappaPC shell. It supports object-orientated technology for the MS Windows environment. The software provides a very useful tool to practitioners, saving time and cost. Equipment selection is a recurring and expensive problem of mine planning and often involves interdisciplinary experts from different fields. It is very difficult and expensive to bring together all these experts. The capabilities of the expert system developed are illustrated in the paper. The software overcomes the difficulties of selecting the proper equipment for surface mining operations, which is very important, and results in substantial savings. Equipment databases for hydraulic excavators with 15-59 yd3 capacities and trucks with 35-360 tons are constructed and these databases are used to select the proper configuration. A case study is carried out for Soma Surface Coal mines in Turkey. Keywords: surface mining, expert systems, equipment selection, hydraulic excavators, diggability

Jan 1, 2009

By J. E. Forbes, B. K. Loveday

The role of gravity concentration in the recovery of gold from typical South African gold ores is described. The location of the concentrator in the grinding circuit is discussed, and typical capacities and operating costs are given. Some operating problems are mentioned, but the performance of concentrating equipment is not dealt with in detail since this to some extent depends on the nature of the ore. It is concluded that the main benefits are an improved recovery of coarse gold and a reduction in soluble loss. The use of a long leaching time and a carbon-in-pulp recovery system may eliminate the need for gravity concentration. but gravity concentration is seen as an inexpensive way of improving the recovery on existing plants.

Jan 1, 1982

By B. Strohmeier

The role of large, ultra-high-powered arc furnaces in a fully integrated steelworks for the production of flat products is outlined, and an account is given of the technological improvements that have been implemented over the past few years to enable the arc furnace to remain competitive against the conventional route using blast furnaces and top-blown-oxygen steelmaking (LD). Modern secondary refining facilities have been installed, enabling the arc furnace to operate at high production rates in the manufacture of high-quality flat products.

Jan 1, 1985

By S. N. Alecsandrov, BulgakovY. F.

Putting out fires in faces is an extremely complex and dangerous operation from the technological point of view which sometimes is accompanied by human victims. The new technology of fire-extinguishing sets giving directly into a mining face has been developed at the DNTU in order to put out such kinds of fires. The technique presupposes an availability of special installation placed on ventilation and conveyor mining drift. In case of fire a special fire-extinguishing powder is delivered with the help of remote control into mining face. Subjects, allowing to determine powder delivering distance in the frame of mining workings are presented in the report. The given technology substantially increases safety of accident work which are carried out in case of fire.

Jan 1, 2003

By L. M. Falcon

Cassiterite is considered to be the only economically significant tin mineral in the earth's crust. In its purest form, cassiterite contains 76 per cent tin. The mineral is hard and heavy but also extremely brittle. and is therefore ideally suited to gravity recovery techniques. Cassiterite deposits can be categorized into two main types, i.e. alluvial or 'soft' rock deposits, and 'hard' rock deposits. The former are relatively simple to upgrade owing to their relatively coarse nature and their high degree of liberation. Hard-rock deposits, on the other hand, require considerably more sophisticated gravity methods to achieve the required degree of beneficiation. Various types of gravity recovery devices, both old and new, are described, and their respective roles in the flowsheets used are illustrated.

Jan 1, 1982

By C. L. de Jongh

The number and scale of backfilling operations in the South African gold mining industry have grown rapidly in recent years. The application of backfilling as a means of stope support in a wide range of geological conditions and mining systems has resulted in the development of a variety of alternative fill systems. Experience gained in the evaluation of operating fill systems has contributed to a knowledge of the essential concepts to be considered in their design. This knowledge can also influence management's perception of what is expected of a backfilling system. The factors to be assessed in stating and satisfying these objectives are examined. The areas of investigation cover the selection of a suitable material, its preparation, distribution and placement, and the engineering logistics involved in the management of such a system. Finally, the integration of a filling system with an existing mining operation is examined.

Jan 1, 1988

By R. S. Sarracino, M. J. Louw, S. M. Vather

Two detonation models, IDeX for ideal VOD and CPeX for non-ideal VOD, were used to predict the velocities of detonation (VOD) of five explosives: ANFO, a bulk emulsion, and three repumpable emulsions (R100 Gold, R100 Diamond, and R105). The theoretical VODs were compared with the in-hole VODs of the explosives, and the predicted and actual values were found to be within experimental error for ANFO and the bulk emulsion. The results were not consistent for the repumpable emulsions. The discrepancies can be explained as being due to variations in mining and loading practices. The results show that the detonation models can be effective tools in predicting the behaviour of explosives in different diameters and rock confinements, provided that the user is aware of the factors that can affect the optimal usage of explosives and equipment.

Jan 1, 1993

The kinetics of adsorption of gold di-cyanide onto activated carbon has been investigated extensively over the past two decades. These studies have demonstrated that both film and intra-particle mass transfer affect the kinetics. The dominant mechanism of intra-particle mass transfer has not yet been identified. In the work described, surface diffusion and pore diffusion are considered as possible rate-determining mechanisms of intra-particle mass transfer. Mathematical models are described that incorporate film mass transfer and the respective intra-particle mass transfer mechanism with equilibrium described by a Freundlich isotherm. Rate constants of film mass transfer and pore or surface diffusivities were estimated by the fitting of the respective models to experimental carbon adsorption data. The estimated pore diffusivities, after they had been corrected for the porosity and tortuosity of the carbon, were found in most instances to be higher than the molecular diffusivity of dilute gold di-cyanide in aqueous solution. This situation is not physically viable. The surface diffusion mechanism acting in parallel with the pore-diffusion mechanism is thus responsible for the intra-particle transportation of most of the gold.

Jan 1, 1996

By M. L. Young, J. B. See

Effective thermal conductivities of packed beds of chromite ores by M. L. YOUNG, B.Se. (Rand), M.Sc. (Rand) (Visitor) and J. B. SEE, B.Sc. (Hons), Ph.D. (New South Wales), M.I.M., M.I.M.M. (Member) The effective thermal conductivities in stagnant air of packed beds of fines, lumps, and indurated and pre-reduced pellets of two chromite ores with different chromium-to-iron ratios were determined in the temperature range 300 to I 100°C by the heat-sink technique. Packed beds of fines, whether of the size fraction between 20 and 65 mesh, between 65 and 100 mesh, or between 100 and 150 mesh, were found to have the same values of effective thermal conductivity. For one ore, the effective thermal conductivities of packed beds of fines between 20 and 48 mesh at tem peratures above 600"C were higher than those for finer particles. This difference is explained as being due to the increase in importance of radiation heat transfer, but no definite conclusions are reached about the relative contributions of conduction and radiation heat transfer to the effective thermal conductivities of packed beds of fines between 20 and 48 mesh. Two published models were used for the theoretical prediction of values for thermal conductivities of the indurated and pre-reduced pellets as well as of lump ore. The experimental and theoretical results were in good agreement in view of the uncertainties in the assumed values of emissivity and thermal conductivity of the chromite ore.

Jan 12, 1976

By M. J. A. Leal-Gomes

There is a set of settled ideas in the field of the mechanics of rock mass joints, that need a deep revision, after the last experimental works of several authors. In this paper, this theme is approached under several viewpoints, like the following ones: the essential influence of the mating or mismatching of rock joints on their strength (different strength models are applicable to these two situations, one leading preferably to normal scale effects, and the other to inverse scale effects); Patton's model is a bad formulation of the joint strength, whenever there is a dilation effect in the slidings (actually, the essential consideration of the amplitude of the roughess isn't made by any limit equilibrium model, like Patton's model); the joint strength increases as the width perpendicular to the sliding direction is reduced (previous works of other authors suggested the independence of the strength on that width); the reduction of the anisotropy of the roughness, as the sample symmetry and sample dimensions increase; there is no scale effect in the discontinuity mechanics, if there is no roughness heterogeneity; when only the same roughness and undulation orders are involved in the tests, shorter samples have larger peak displacements and lower shear stiffnesses than larger samples (usually, the contrary is admitted). For all these reasons, there isn't an easy correlation between the small scale tests and the natural large joint scale. Only "in situ" large scale tests have some representativeness. All the above mentioned questions are correlated to each other. Es gibt eine Menge eingewurzelter Ideen im Gebiet der Mechanik von Felsklüften, die, nach den letzten experimentellen Arbeiten von mehreren Verfassern, eine tiefe Überprüfung benötigen. In dieser Mitteilung, wird dieses Thema unter mehreren Blickpunkten angegangen, wie die folgenden: der wesentliche Einfluß des Zusammenpassens oder nicht Zusammenpassens von Gesteinsklüften auf ihre Festigkeit (verschiedene Festigkeitsmodelle sind auf diese zwei Situationen anwendbar, eins, das vorzugsweise zu normalen Maßstabseffekten führt, und das andere, das zu umgekehrten Maßstabseffekten führt); Pattons Modell ist eine schlechte Formulierung der Kluftfestigkeit, immer wenn es einen Dilatationseffekt in den Verschiebungen gibt (in Wahrheit, wird die wesentliche Berücksichtigung der Rauheitsamplitude von keinem Grenzgleichgewichtsmodell beachtet, wie Pattons Modell); die Kluftfestigkeit wächst wenn sich die Breite senkrecht zur Verschiebungsrichtung verringert (frühere Arbeiten anderer Verfasser suggerierten die Unabhängigkeit der Festigkeit von jener Breite); die Verringerung der Rauheitsanisotropìe, wenn die Probekörpersymmetrie und Probekörperabmessungen zunehmen; es gibt keinen Maßstabseffekt auf die Trennflächenmechanik, wenn es keine Rauhheitsheterogenität gibt; wenn nur die gleichen Rauheits- und Ondulationsgrößenordnungen in den Versuchen verwickelt sind, haben kürzere Probekörper größere Spitzenverschiebungen und geringere Schersteifigkeiten als größere Probekörper (gewöhnlich, wird das Gegenteil angenommen). Wegen aller dieser Gründe, gibt es keine einfache Korrelation zwischen den Versuchen im kleinen Maßstab und dem natürlichen großen Kluftmaßstab. Nur "in situ" Versuche im großen Maßstab sind einigermaßen repräsentativ. Alle die oben erwähnten Fragen hängen miteinander zusammen. Il y a un ensemble de des bien établies arrière-pensées idées dans le champ de la mécanique des discontinuités en massifs rocheux qui ont besoin d'une profonde revision, après les derniers travaux de divers auteurs. Dans cet article cette matière est abordée sous divers points de vue, comme les suivants: la signification essentiel de l'ajustement ou du désajustement des discontinuités dans leur résistance. Des différents modèles sont applicables à ces deux situations, une conduisant de préference à des effets d'échelle normaux et l'autre à des effets d'échelle inverses; le modèle de Patton est une mauvaise formulation de la résistance des joints quand il y a effet dilatant dans les glissement. En effet la contribuition essentielle de l'amplitude de la rugosité n'est pas consideré par aucun modèle d'équilibre limite comme le modèle de Patton; la résistance des joints croit au fur et à mesure que la largueur perpendiculaire à la direction de glissement est réduite. Des travaux antérieurs d'autres auteurs suggéraient que la résistance était indépendant de cette largueur; la réduction de l'anisotropie de rugosité au fur et à mesure que la symétrie et les

Jan 1, 2003

By F. H. Deist, J. P. E. Morris, E. Georgiadis

For some years the Collieries Research Laboratory of the Chamber of Mines of South Africa has been engaged in the development and application of computer programmes to aid in the solution of rock mechanics problems. It is the purpose of this paper to introduce some of the programmes having general applicability. A system capable of predicting stresses and displacements induced by large-scale tabular excavations is discussed. A finite element programme especially designed for handling layered continuum problems, and which is being used extensively has been supplemented by an automatic mesh generation facility that reduces problem preparation times considerably. Some typical applications of these programmes are described. An entirely new approach, potentially capable of performing linear three-dimensional continuum analysis at practical cost is introduced.

By S. Konetschnik, E. Dreyer, A. Filzwieser

"More intense furnace operations require effective cooling in order to achieve low refractory wear and good furnace lifetimes, making cooling technology an important aspect of furnace operations. However, the use of water - today’s standard cooling medium - has some disadvantages, as it can cause problems both during furnace start-up and operation, namely hydration problems, corrosion, and explosions. Apart from these aspects, the energy that is removed by extensive cooling cannot be recovered and is normally lost in the cooling towers.With METTOP’s new patented cooling technology it is possible to overcome the disadvantages of water by using an alternative cooling medium, namely ionic liquids (ILs). The main advantage of ILs is the fact that there is no risk of explosion should this liquid come in contact with molten metal. Furthermore, ILs can be used at higher temperatures than water - up to 200°C. This relatively high cooling medium temperature avoids hydration and corrosion problems and allows recovery of the energy by combining the ILTEC system and the organic Rankine Cycle (ORC) technology, for example.Due to the removal of the explosion risk, much higher safety standards can be achieved, particularly in critical areas such as tap-holes"

Jan 1, 2014

The November General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 18th November, 1970, at 4.00 p.m. V. C. Robinson (President) was in the Chair. There were also present 30 Fellows, including J. K. E. Douglas, R. C. J. Goode, Dr J. P. Hugo, Prof J. de V. Lambrechts, D. G. Maxwell, Prof R. P. Plewman, Dr M. D. G. Salamon, P. W. J. van Rensburg, L. W. P. van den Bosch (Council Members), R. E. Burnton, S. Craib, D. de Villiers Oxford, J. C. Fritz, G. W. Gray, G. H. Henderson, S. D. Hill, C. H. Kruger, B. Leach, C. S. MacPhail, D. J. Molony, W. G. Fyne Mercier, R. A. Scott, M. v. R. Steyn, I. E. van Aswegan, A. D. Vos, J. M. Vosloo and N. Zolezzi. Four Members, including I. G. Evans, R. W. Shearer, W. Wilson. One Associate: P. M. C. Wilson. Four Students: H. G. Albertyn, J. T. Davies, P. G. Henderson and P. J. Pretorius. Fourteen Visitors, including S. R. Barker, F. H. Deist, Dr de Jager, L. F. Duvel, P. du P. Kruger, B. D. Maree, B. R. Meyer, R. Redmond, J. Rietief, A. W. S. Schumann, Mrs A. W. S. Schumann, T. S. Stoffberg, C. A. Visser and R. van der Wait. Secretary, D. C. Visser. Total present 55. The President: "Gentlemen, I would like to welcome all members of the Institute who are present, and visitors, and I would like specially to welcome any members of the Suid-Afrikaanse Akademie who are present this afternoon." OBITUARIES The President: "Before starting on the agenda the first item, of course, is unfortunately obituaries and it is my sad duty to announce the death of the following: I would like to start with a person who is not actually a member of the Institute but who, in his capacity as President of the Chamber of Mines, was Honorary President of this Institute three times and I refer, of course, to Mr Herman Calderwood Koch who passed away last Saturday. Then I would refer to Richard Beaumont Tasker, Life Fellow, who joined this Institute in 1932, and who died on the 22nd of October, 1970. Then, lastly, Mr Jean Francois du Plessis, a student, who joined the Institute on the 19th June, 1968, and passed away on the 11th of November, 1970, as the result of an accident. Mr du Plessis was to have received a Student Prize today for his paper entitled, Displacements and stresses in the vicinity of a horizontal long-wall'. We were all most upset to learn of his death last week, and we are now going to make arrangements to hand his prize to his widow on a suitable special occasion. As a mark of respect to the memory of the deceased, and in sympathy with the bereaved, I would ask you all to stand and observe a few moments' silence. Thank you." CONFIRMATION OF MINUTES The President: "May we confirm the minutes of the monthly general meeting which was held on 16th September, 1970, as published in the November Journal?" Agreed. MEMBERSHIP The President: "I have much pleasure in announcing that the names of the undermentioned candidates having been published in accordance with By-Law 5.2.2, Council has elected them to membership of the Institute in the following grades: Fellow: Ronald White Ballantine. Members: Jan Johannes Hertzog Viljoen, Agge Petrus Rutgerus van der Meer, Peter Anthony Reynolds, Ernest Esdaile Leyde Hans Lutz Klingmann, Ronald Archer.' Graduates: Trevor Stanley Schultz, Thomas Cochrane Meiklejohn, Leslie Harold Heyman, Dennis William Bosch, Sydney Stuart Absolom. Associates:Roderick James.Vermaak, Theodorus Daniel van Wyk, Michael Osmond Savignac Stedman, Leslie Owen Raymer, Bryan Arthur McKay, Leon Ellis Finlay Leask, Dudley Graham Lovedren Hall, John Arthur Gibbon, Richard Reginald de Villiers, Carel Frederik Boshoff. Students: Frederik Wilhelm Christian Coetzer, Phillippus Johannes de Wit, Jan van der Merwe Grimes, Davood Khareghani, Jan Wolvaardt Oberholzer, Johannes Lodewikus Pretorius Pieter Jacobus Strobos, Herbert Gerald Waldeck.' MEMBERS TRANSFERRED TO A HIGHER GRADE From Associate to Fellow: Howard Mitchell Wells. From Associate to Member: Ernest John Dominy. "I welcome the newly elected members to the Institute and congratulate the members who have been transferred to a higher grade." AWARDS The President: "It is with very great pleasure that I can announce that Council has agreed to make the following awards for papers presented to the Institute during the year ended July, 1970. Gold Medals to Prof Plewman and W. D. Ortlepp for their paper entitled 'The development and application of a digital computer method for the solution of strata control problems' written jointly with F. H. Deist (Visitor) and presented in September, 1969. A Silver Medal to Dr Finkelstein for his paper entitled 'The Influence of sulphydryl and cationic flotation reagents on cyanidation of native gold' written jointly with Dr K. G. Ashurst (Visitor), and presented in June 1969 at the Symposium on the Recovery of Pyrite. ' May I congratulate these gentlemen on the high honour they have won with their papers. As new medals are in the process of being designed the actual awards will be made at a later date to be announced to members.

A. H. Mokken: I am pleased to have been given this opportunity to make a contribution to Dr Muller's paper tonight. The reason for this is that, at one stage in our careers, we were associates in the same undertaking. Dr Muller, then fresh from University, with a degree in pure science, had just stepped onto the first rung of the ladder, which, it was then thought, would lead him to a career in gold extractive metallurgy. However, endowed with an enquiring mind and conscious of a lack of fundamental training in general metallurgy and engineering, he felt a need for further academic study. To meet this need and, more importantly, to meet the necessary finances, he found his opportunity in steel. Armed with a bursary, he bade farewell to gold and proceeded overseas, to the University of Sheffield, to train as a steel metallurgist. The outcome of these academic efforts, which were followed by assignments in the steel industry and a further period at Sheffield, is the man we have listened to tonight-a highly qualified metallurgist who has displayed a sound knowledge of his subject. In choosing Sheffield, Dr Muller became associated with a steelmaking centre of world renown, a centre usually credited with the first systematic production of alloy steels, as far back as the 18th century. Since that time, great advances have been made in the production of alloy steels and this is especially so in the last decade or two, when major developments in civil, mechanical, electrical, aeronautical and nuclear engineering have been made possible by the development of steels with improved properties. In spite of spectacular advances in the technology of non-ferrous alloys, plastics and other materials of construction, steel has maintained its role as a pre-eminent material for engineering use. With the gradual accumulation of data on the properties of steels, and the use of thin film electron microscopy, to study the behaviour and characteristics of such phenomena as dislocations in metals and other microstructural features, the physical metallurgist appears to be approaching the stage of an exact understanding of such phenomena as strength, ductility and brittleness-a knowledge which could lead to close control of such properties and, therefore, to the attainment of the highest goals. An interesting example, illustrating the use of fundamental principles, based on physico-metallurgical research, is the development of the maraging steels developed by Bieber at the International Nickel Company. These steels have met the extreme technological requirements of the space age by providing the material for the cases of large rockets in which qualities, such as high tensile strength, toughness, workability and weldability are most important. Attractive as they might appear to be in considerations of savings of weight, cost of erection, transport of materials and foundations, the use of high strength steels has been accompanied by special problems such as brittle fracture, hydrogen embrittlement, notch-toughness and fatigue. It has been found that high strength steels, which performed acceptably in conventional tension tests, were found to undergo failure, in a brittle manner, in service. Hydrogen embrittlement has caused spectacular failures at a fraction of the normal ultimate tensile strength, and a lack of correlation between fatigue and tensile strengths has diminished the advantages to be obtained from the use of high strength steel in some applications. A new approach to the selection of materials for engineering design has resulted from a consideration of these phenomena in which strength, as such, is no longer as significant as it was previously. Parallel with the development of high strength steel has been the need for suitable techniques for joining component parts and here welding has played an

By J. A. L. Napier

One of the most important characteristics of tabular mine stress analysis is the need to represent the complex evolution of mining face positions and the accompanying induced stress changes in the rock mass. Integration of seismic activity with numerical modelling requires flexible and efficient solution schemes in which both off-reef damage and large-scale fault slip can be effectively represented. A new approach is investigated in which the stope closure and ride variables can be found using a moving least squares estimator. Some advantages of this approach over traditional element-based tessellation schemes are identified. At the same time, shortcomings of this method are noted when the displacement discontinuity variable is approximated by a polynomial shape function. Difficulties and possible solutions to the shape function formulation near excavation edges are discussed. Une des caractéristiques les plus importantes de l’analyse des contraintes minières tabulaires est la nécessité de représenter la complexe évolution des positions du front de taille et des changements concomitants des contraintes occasionnées dans la masse rocheuse. L’intégration de l’activité sismique avec la modélisation numérique requiert des projets souples et efficaces qui permettent la représentation des dommages hors-filon et des glissements de faille à grande échelle. Une approche nouvelle est étudiée qui permet de trouver la fermeture de la taille et les variables de montage en utilisant un estimateur par les moindres carrés mobile. Certains des avantages de cette approche sur les traditionnels projets basés sur une structure en mosaïque sont identifiés. En même temps, les défauts de cette méthode sont notés lorsqu’on calcule la variable de discontinuité du déplacement approximativement par une fonction de forme polynomiale. Les difficultés et solutions possibles à la formulation de la fonction forme près des bords d’excavation sont discutés. Eine der wichtigsten Charaketeristika der taublaren Grubenspannungsanalayse ist die Notwendigkeit, die komplexe Entwicklung der Abbaupositionen und der damit verbundenen induzierten Spannungsänderungen der Gesteinsmasse neu vorzulegen. Die Integration der seismischen Tätigkeit mit einem numerischen Modell erfordert flexible und effiziente Lösungsschemata, in denen sowohl Schäden ausserhalb des Riffs als auch Verwerfungen großen Ausmaßes effektiv dargestellt werden. Ein neuer Vorstoß wird untersucht in welchem die Strossenschliessung und Schneisenvariablen unter Verwendung des Schätzwertes der kleinsten quadratischen Abweichungen (Gaussscher Schätzwert) gefunden werden. Einige Vorteile dieser Annäherung im Vergleich zu der traditionellen Element-basierenden Tessellation sind identifiziert. Gleichzeitig werden Unzulänglichkeiten dieser Methode vermerkt, wenn die Verschiebungsdiskoniuitätsvariable durch eine polynomische Formfunktion angepaßt wird. Schwierigkeiten und mögliche Lösungen zur Formfunktionsformulierung nahe Exkavationsrändern werden besprochen.

Jan 1, 2003

Introduction to high temperature oxidation of metals, by N. Birks and G. H. Meier, London, Edward Arnold, 1983. 19S pp. R30,25. Reviewers: M. B. Cortie and G. G. Garrett Seam gas drainage with particular reference to the working seam, edited by A. J. Hargraves. Woollongong, The Australasian Institute of Mining and Metallurgy. 370 pp. $A30. Reviewer: C. J. Fauconnier New books Solvent extraction Part I, by G. M. Ritcey and A. Ashbrook. Amsterdam, Elsevier, 1983. Elektronishche Steuerungen und Mikroprozessoren im Bergbau. Sicherheit und Zuverlassigkeit Environmental impact control. Philosophical and procedural guidelines for the planning professions Mineral processing and extractive metallurgy. Reagents in the minerals industry.

Jan 1, 1984

By D. Brazier, W. Laing, D. Nixon

Keywords: Pyrometallurgy, furnace, smelter, copper, Palabora The Palabora copper smelter has operated for the past 38 years, treating concentrates produced at the mine site. Palabora has reduced captive material by almost 40 per cent with the transition from a large open-cast to a smaller underground mine. The smelter and refinery complex was designed to treat 120 kt contained copper units per annum, with the underground only supplying 70 per cent of the feed. The agreed strategy was to import enough concentrates to maximise production and reduce operational unit costs. This transition has presented the Palabora management with new challenges both in technical and financial aspects.

Jan 1, 2006

COUNCIL The following served on Council during the year under review Office Bearers Dr J. P. Hugo (President), P. W. J. van Rensburg and Professor R. P. Plewman (Vice-Presidents), Professor D. D. Howat (Immediate Past-President), and D. G. Maxwell (Honorary Treasurer). Ordinary Members of Council H. P. Carlisle (until February), R. C. Espley-Jones, G. H. Grange, Dr D. I. Legge, W. W. Malan, J. B. Mudd, Dr R. E. Robinson, Dr M. D. G. Salamon, L. W. P. van den Bosch, D. A. Viljoen (co-opted May 1973), and P. A. von Wielligh. Branch Chairmen A. Bain (Witbank-Middelburg Branch), C. J. Isaac (O.F.S. Branch). Past Presidents Serving on Council R. J. Adamson, M. Barcza, H. Britten, J. K. E. Douglas, R. C. J. Goode, P. Lambooy, Professor J. de V. Lambrechts, Dr J. T. McIntyre, J. F. Reid, and V. C. Robinson. Ten Council meetings were held during the year, with an average attendance of 18, and the standing committees held 29 meetings. MEMBERSHIP Twelve Fellows, ten Members, twenty-one Graduates, eleven Associates, thirty-one Students, and forty-two Company Affiliates were elected during the year. One Member was reinstated. Eight Fellows, two Members, and two Associates were admitted to retired membership. Four Graduates were transferred to Members, one Associate to Member, three Students to Members, one Graduate to Associate, two Students to Graduates, and one Student to Associate. Your Council records with deep regret the death during the year of the following : D. R. Campbell, J. Daniel, M. J. Dennehy, and F. S. C. Rogers (Life Fellows) ; W. T. balling and T. Pryor (Life Members); C. Boocock, W. Drake R. J. Moore, M. P. Pearse, J. M Pike, W. A. Schwezoff, A. I. Suss man, and L. G. S. Wright (Fellows) ; A. F. Chalmers (Member) ; and W. R. Gerry and G. T. Rimmer(Associates). A comparative statement of membership as at 30th June, 1973, and the end of the previous year it shown in the following tabulation: 30th - 30th June, - June, 1972 - 1973 Honorary Life Fellows 5 - 4 Honorary Fellows 13 - 9 Life Fellows 181 - 177 Fellows 541 - 536 Members 479 - 487 Graduates 115 - 128 Associates 182 - 186 Students 162 - 183 Company Affiliates 24 - 64 1 702 - 1 774 JOURNAL The papers that were published in the Journal during the year are listed below: August, 1972 The effects of chromium oxide, iron oxide, and calcium oxide on the liquidus temperatures, viscosities, and electrical conductivities of slags in the system MgO-Al2O3-SiO2, by M. S. Rennie, D. D. Howat, and P. R. Jochens A study of the dust exposure of South African white gold miners, by R. J. Page-Shipp and Elizabeth Harris A forecast of the coal and uranium requirements for electric power generation in South Africa, by E. J. Maunders September, 1972 Mine management by objectives, by A. A. Hazell Some aspects of the deformation behaviour and temperature rise during instantaneous compression loading of high purity aluminium, by H. J. E. Hamel Computer control of flotation at the Ecstall concentrator, by M. P. Amsden, C. Chapman, and M. G. Reading Optimizing the public gains from the exploitation of mineral resources, by A. Azis and J. Zwartendyk October, 1972 Presidential Address: Nuclear energy: its interactions with mining and metallurgy, by J. P. Hugo Presidentsrede: Kernenergie: sy wissel-werkinge met mynbou en metallurgic, deur J. P. Hugo Raise-boring experiences in the gold mines of the Anglo American Corporation Group, by J. W. Wilson and P. C. Graham November, 1972 Materials for winding plant components, by G. T. van Rooyen An analytical solution to the batch-comminution equation, by R. P. King A new approach to the study of human factors in stope productivity, by A. C. Lawrence Fundamental studies of the flotation process: the work of the National Institute for Metallurgy, by N. P. Finkelstein and V. M. Lovell Growing use of deionised water in surface coating techniques, by W. F. Lorch December, 1972 The development and application of a computer system to aid in the planning of production in mines, by F. H. Deist, L. F. Duvel, J. D. Austin, and H. D. Small PERT, and how PERT techniques can be used in modern mine management, by E. J. Boome and A. C. Schmidt A critical comparison of specific cooling power and the wet kata thermometer in hot mining environments, by J. de V. Lambrechts January, 1973 Liquidus temperatures in the Cr-Fe-Si system in the composition range representative of ferrochromium-silicide produced in South Africa, by J. C. M. Wethmar, D. D. Howat, P. R. Jochens, and O. A. W. Strydom Platinoids in the Witwatersrand System, by C. A. Cousins The development of a continuous recording scintillation counter mounted on a cyclometer, by P. D. Teens and D. Visser February, 1973 Computer analysis, modelling, and optimisation of gold recovery plants of the Anglo American Group, by M. I. Brittan and E. J. J. van Vuuren The significance of the mineralogical and surface characteristics of gold grains in the recovery process, by C. E. Feather and G. M. Keen Statistical valuation of diamondiferous deposits, by H. S. Sichel March, 1973 The effect of the reactivity of lime on desulphurisation efficiency in the basic oxygen furnace, by A. A. Hejja, D. D. Howat, and P. R. Jochens A review of real-time particle size analysers, by A. L. Hinde In situ measurements of the surface heat transfer coefficient in underground airways, by K. R. Vest April, 1973 An investigation into the kinetics and mechanisms of the oxidation of iron (II) by oxygen in aqueous chloride solutions, by R. P. Colborn and M. J. Nicol Electric smelting at Rustenburg Platinum Mines Limited of nickel-copper concentrates containing platinum-group metals, by J. C. Mostert and P. N. Roberts Metallurgical considerations in the

Jan 10, 1973

By J. Githiria, C. Musingwini

"Cut-off grade is a decision-making criterion often used for determining the quantities of material (ore and waste) to be mined, ore processed, and saleable product. It therefore directly affects the cash flows from a mining operation and the net present value (NPV) of a mining project. A series of different cut-off grades that are applied over the life of mine (LOM) of an operation defines a cut-off grade policy. Due to the complexity of the calculation process, previous work on cut-off grade calculation has mostly focused on deterministic approaches. However, deterministic approaches fail to capture the uncertainty inherent in input parameters such as commodity price and grade-tonnage distribution. This paper presents a stochastic cut-off grade optimization model that extends Lane’s deterministic theory for calculating optimal cut-off grades over the LOM. The model, code-named ‘NPVMining’, uses realistic grade-tonnage realizations and commodity price distribution to account for uncertainty. NPVMining was applied to a gold mine case study and produced an NPV ranging between 7% and 186% higher than NPVs from deterministic approaches, thus demonstrating improved project value from using stochastic optimization approaches. Background on cut-off grade calculation and optimizationCut-off grade is a decision-making criterion that is generally used in mining to distinguish ore from waste material. Consequently, it is used to determine the quantities of material (ore and waste) to be mined, ore processed, and saleable product. A series of different cutoff grades that are applied over the life-ofmine (LOM) of a mining operation defines the cut-off grade policy for that particular operation. The cut-off grade therefore directly affects the cash flows to be produced and the net present value (NPV) of a project at the mine planning or feasibility study stage."

Mar 1, 2019

By P. A. P. Fouché

Processing confidence for a bankable feasibility study on a green field heavy mineral deposit is inmost cases achieved only through bulk sample processing. Bulk sample is classified as a large enough concentrate sample that is processed into final products to satisfy market sample demand as well as further processing demands such as smelting. In this case study the demand was to produce 500 tons of heavy mineral concentrate from more than 5 000 tons run-of-mine on are mote location with limited to no infrastructure. The various challenges faced and lessons learned are documented as an outcome of the success of this mission.

Jan 1, 2007