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By R. R. Mankowski

The work described here attempts to underscore the importance of the time lag between the end of a loading phase and the instant a winding drum begins its acceleration phase. Traces generated from a computer-simulation model show that the amplitude of the stress oscillations occurring in mine hoisting cable during the constant velocity-of-ascent phase is a direct result of the temporal sequence employed between the loading and the raising phases. While current and early literature indicates that extensive work has been undertaken on the isolated effects of these two independent sequences, the literature does not appear to contain any documented evidence to suggest an optimal control or interfacing between these two dynamic regimes.

Jan 1, 1995

INTRODUCTION The SAIMM publishes technical information on various aspects of the minerals industry through several different media. (a) Monograph Series Books in the Monograph Series are high quality, detailed discussions on specialized topics. (b) Symposium Series This series consists of the proceedings of international conferences which are held in South Africa. (c) Special Publications Series This series covers titles which do not form part of the Monograph and Symposium Series. (d) The SAIMM Journal Papers published in the Journal cover al relevant areas of technical interest by striving for a balanced content and maintaining a consistently high technical standard. (e) School and Colloquia Notes The papers from al local schools and colloquia are published and handed out at registration. Should authors wish to have their papers considered for publication in the Journal, they should adhere to the guidelines outlined below.

Jan 1, 1991

By D. J. Adams, R. G. Gürtunca

In situ measurements and numerical modeling based on elastic theory showed that backfill stresses are considerably higher than originally thought. This has led to a change in understanding of rockmass behaviour. After describing previous work on the behaviour of the rockmass, this paper discusses possible reasons for the high stresses measured in backfil, and identifies the rockmass mechanisms possibly generating these stresses. It is concluded that the joints and the geological stratigraphy can lead to increased elastic convergence, and that the inelastic behaviour of the rockmass is also partly responsible for the increased closure measured in backfill. The use of an in situ modulus is suggested as an interim solution until a new computer model that allows for joints, different layers, and inelastic closures becomes available.

Jan 1, 1991

By F. H. Deist, H. D. Small, J. D. Austin, L. F. Duvel

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 Published in the Journal, December 1972. Discussion by J. W. WILSON and R. W. HAZELL Although the Mine Planning Simulation Programme was originally developed as an aid to coal-mine planning, its extreme flexibility has enabled us to simulate gold-mine planning with equal facility. The initial application of the Mine Planning Simulation Model was in a small area of a large Free State gold mine where the primary aim was to assess the applicability of the programme to the gold-mining situation.

Jan 12, 1972

By R. J. Dippenaar, W. H. Van Niekerk, D. A. Kotze

It is generally accepted that alkalis attack and degrade the carbon fraction of coke in a blast furnace. Because South African cokes contain relatively high amounts of ash, the influence of alkalis on the ash fraction was investigated, the carbon and ash fractions being separated and studied separately. Potassium engenders the formation of liquid, with a resultant expansion of volume and a decrease in the strength of the coke ash. However, the ash did not play a significant part in the degradation of the coke, and it was found that the catalytic effect of potassium on the Boudouard reaction was the overriding factor in the coke-degradation process.

Jan 1, 1986

By D. A. Viljoent

Historical Background The Empire Council of Mining and Metallurgical Institutions was formed during the early 1920s to foster the holding of British Empire Conferences, and today is representative of the following Institutes: Australasian Institute of Mining and Metallurgy Canadian Institute of Mining and Metallurgy Geological Society of South Africa Institute of Petroleum Institution of Metallurgists Institution of Mining and Metallurgy Institution of Mining Engineers Metals Society Mining, Geological and Metallurgical Institute of India South African Institute of Mining and Metallurgy South Wales Institute of Engineers. The first public suggestion for the formation of a Council that would link mining institutions in various parts of the British Empire came from Mr Frank Merricks, who, as President of the Institution of Mining and Metallurgy, was speaking at the annual dinner of the IMM in 1921.

Jan 1, 1981

The value of incentive payments in the mining industry by K. SMITH, A.R.S.M., B.Sc. (London) (Member) This paper reviews the history of incentive payments in the mining industry, and gives some indication of the magnitude of improvement that has been achieved by this means in the past. The objective is to promote a more general belief in the efficacy of these methods, and thus to encourage their wider and more effective application by mining engineers in general, and by the rising generation in particular. It is concluded, from a consideration of current productivity levels in the gold-mining industry (still South Africa's leading revenue earner), that further substantial improvement can be achieved by a better understanding of the time-tested principles of incentive payments.

Jan 5, 1974

By W. Peters, W. A. H. Poppmeier

An overview is given of the present state of traditional and new steelmaking equipment and techniques, and one of the direct steelmaking methods that are currently being developed is described. In steelmaking processes, coal is used to supplement the energy input and to reduce iron oxides in the slag. Foamy slag practice is discussed, and the most widely used types of ladle recarburizers, their properties, and manufacture are described. It is concluded that the use of carbon sources, mainly for supplementing energy and as reductants, will increase in the future, but that demands on the purity of the materials will probably become more stringent. If hydrogen were manufactured at a competitive cost, it could become an alternative fuel and reductant in the field of iron and steelmaking.

Jan 1, 1993

By J. E. Friant, R. P. H. Willis, J. Maaren

Considerable effort is currently directed towards the development of non-explosive mining methods with the potential to allow continuous mining in narrow reef conditions. Besides improving productivity, continuous mining results in concentrated mining which has a significant impact on reducing infrastructure costs. CSIR: Miningtek recognized the potential of mini-disc cutters in a long or short wall application for selective hard rock mining in 1999. EEA was chartered to build a 780 mm diameter by 800 mm deep drum cutter head. While EEA designed and built the head, CSIR designed and built the drive mechanism and chassis for the trial machine. After assembly and shop testing at CSIR’s facility, the machine was shipped to a platinum mine for trials. This paper traces the development of mini-disc cutters and their application in South Africa.

Sep 1, 2001

By B. P. Gilbertson

In her wonderful book, 'The Guns of August', historian Barbara Tuchman tells us that the French war plan for 1914 was dedicated entirely to an offensive strategy, not a defensive one. Plan 17, as it was called, concentrated everything on a French advance to the Rhine, leaving the French left virtually unguarded. This strategy could only be justified by the fixed belief that the Germans could not deploy sufficient manpower to extend their invasion around through western Belgium and the low provinces; and this in turn was based on the belief that the Germans would never use reserve troops in the front line. Al evidence to the contrary was ignored. But when the war came, the Germans followed Count Von Schlieffen's plan; they did use reserves in the front line and they did come the long way around on the west. The result- as you know-was a protracted war, with fearful consequences for the rest of our century.

Jan 1, 1994

By P. A. Von Wielligh

Without minerals, man cannot possibly hope to maintain his present standard of living. Professional mining men throughout the world, particularly in mineral-exporting countries like South Africa, are faced with the increasingly difficult task of ensuring adequate supplies of minerals. The problems of gradually diminishing mineral reserves and rapidly rising mining costs can to a certain extent be overcome by the use of more-sophisticated technological techniques and by the improvement of efficiency wherever possible. However, there is growing concern in some quarters, that, despite the ingenuity of engineers, geologists, metallurgists, and scientists, the earth's mineral reserves will eventually become insufficient to meet man's needs. In order to ensure the continued well-being of the earth's population, it is therefore imperative that more attention should be paid to mineral research and the training of specialists in the field of mineral reclamation.

Jan 1, 1978

By J. C. Mostert, P. N. Roberts

Electric smelting at Rustenburg Platinum Mines Limited of nickel - copper concentrates containing platinum-group metals By J. C. MOSTERT Pr. Eng.. B.Sc. (Stellenboseh). M.Sc. Met. Eng. (Fellow) and P. N. ROBERTS Pr. Eng.. B.Sc. Eng. (Rand) (Fellow) The processes involved in the smelting in an electric furnace of nickel-copper concentrates containing platinumgroup metals are described. These are concentrate drying, pelletizing, pellet drying, and flux and pellets proportioning, followed by smelting of the concentrate in a submersible-electrode electric furnace, which is discussed in more detail. The furnace matte is blown in a converter to the white-metal stage and is cast in moulds, whilst the slag is granulated, ground, and floated for recovery of valuable metals and afterwards pumped to the tailing dam.

By M. Splaine, C. E. Dohm, S. J. Browner

As the grade of the gold (head grade) in the ore supplied to a reduction plants falls, the efficiency of recovery of the metal drops. This is not simply due to a fixed grade lost in the residue, since the residue grade is itself a function of the head grade. A multi-disciplinary approach was used in the construction of a model to represent the relationship between head grade and recovery efficiency. The model is a physicochemical one based on (i) the reaction characteristics of cyanidation, (ii) the milled-ore selection characteristics of gravity concentration, and (iii) the nearly log normal distribution of gold grades and particle sizes in ore reserves. The model was used to set sound target levels for recovery efficiency for a given head grade at a given plant, against which the performances of the plant equipment can be judged for control purposes.

Jan 1, 1982

Infacon 74 The National Institute for Metallurgy, the South African Institute of Mining and Metallurgy, and the Ferro-Alloy Producers' Association of South Africa extend a cordial invitation to participate in the International Ferro-alloys Congress to be held in Johannesburg, South Africa, in April 1974. Obituary RICHARD AUSTIN COOPER On the 31st March 1972, a once very active member of the Institute, R. A. Cooper, died at the age of 82. He had served on the Council for many years and was Vice-President in 1933/34. ALEXANDER JEREMIAH ORENSTEIN CB., CM.G., C.B.E., LLD., D.Se., M.D., M.R.C.S., F.R.CP., F.R.S.H. Dr Orenstein, who died on the 7th July 1972 at the age of 92, was so well known and so widely acclaimed during his lifetime that it is difficult to add to the tributes which have already been paid to him.

By J. C. Zachariades, D. M. Fraser

The leaching of pyrolusite in acidic ferous sulphate solution was studied so that the important factors governing the kinetics of the reaction could be determined. The reaction is very rapid, and was monitored by continuous measurement and logging of the redox potential in solution by use of a microcomputer. The relationship between redox potential and manganese extraction was established empiricaly for each set of conditions by the use of a technique in which a calibration run was conducted in paralel with each leaching run. The study involved a number of batch leaching runs, and demonstrated that, of the variables investigated, only the initial ferous ion concentration and the reaction temperature afect the rate of manganese extraction. The final extraction did not vary. The reaction was modeled from the results by use of the shrinking-core model and Britan's activation-energy model. The later was found to provide a significantly better fit to the data.

Jan 1, 1991

By E. H. R. Schümann, H. Wagner

SYNOPSIS The paper gives a detailed overview of the history of subsidence engineering on South African collieries. Surface displacements resulting from total-seam extraction are discussed, and the important role of local geology is highlighted. It is shown that the differences in subsidence behaviour between South African and European collieries can be attributed to the presence of competent strata in the overburden of South African coal seams. Criteria are given for the prediction of the most important subsidence parameters, and a new model for the simulation of surface subsidence above total-extraction panels is introduced. The final section of the paper deals with the damage to surface structures caused by total-seam extraction. A brief summary of the most important undermining experiments on South African collieries is given, and it is concluded that local experiences of damage compare with those in Europe.

Jan 1, 1991

By J. R. de Wet

The behaviour of mild steel in aqueous cyanide solutions similar to caustic cyanide elution solutions was investigated at high temperature in electrochemical experiments. The anodic polarization diagrams of mild steel indicated that steel may undergo active dissolution under these conditions. The rare occurrence of gold plating in practice is the result of the limiting of the anodic dissolution of the steel by the presence of a passive layer on the steel. This passive layer is stable only in a certain potential range, and the free corrosion potential attained determines whether the steel will be passive or active. For conditions typical of elution columns, several corrosion potentials are possible, depending primarily on the initial condition of the steel and the concentration of oxygen in the solution. If these conditions result in the formation of a passive layer on the steel, changes in concentration and temperature will not necessarily result in plating since the layer may exist in a metastable form.

Jan 1, 1993

By R F. Sandenbergh, Y Wei

The flotation separation of the Rosh Pinah ore into lead and zinc concentrates are based on the selective flotation of the lead containing minerals followed by the activation and recovery of the zinc sulfides. In the present work the influence of the composition of the water on the selective flotation of the lead containing minerals is reviewed and the results given of the laboratory investigation of the influence of activating species such as silver, lead and copper, on the selective recovery of lead minerals from the Rosh Pinah ore. It was found that it was difficult to prevent the activation of the sphalerite by the metal species in solution in the absence of cyanide, and that colloidal precipitates most probably also serves as a significant carrier of these activators in the flotation circuit. Removal of heavy metal species from the solution by means of an adsorbent is possible, but most probably not practical.

Jan 1, 2007

By A. L. Bleloch, A. M. Starfield

This paper is concerned with heat flow in the plane of a typical cross-section of a deep underground airway. A new algorithm, called the quasi-steady method, is presented for the calculation of rock temperatures in that plane. The algorithm is used in the computation of heat and moisture transfer rates from the rock to the ventilating air for an airway that is wet on part of its circumference and dry elsewhere. The speed and accuracy of the new method are demonstrated on a microcomputer, and it is argued that this method offers a considerably more versatile and physically meaningful alternative to previous methods for the prediction of increases in air temperature along mine airways. The algorithm is also used to explore the concept of a uniformly wet airway that is equivalent to a partly wet airway in terms of its effect on the ventilating air. The concept is shown to be reasonable, but more complex than one might have anticipated. Finally, several useful extensions and applications of the new method are suggested.

Jan 1, 1983

By Nareetsile S., J. Kabwe

In the past few years Orapa and Letlhakane Mines have investigated various new technologies to enhance and improve production. The goal has been to improve productivity, reduce operating costs and make the mines more profitable The advent of Global Positioning Systems (GPS) in the early ’80s brought about the realization of this concept. Orapa and Letlhakane Mines started using GPS in 1999 and it is now used atLetlhakane mine for surveying, vehicle tracking and dispatching and for floor control system. Orapa Mine uses GPS in surveying, floor control and drill navigation. It will also be used for vehicle tracking and dispatching in mid-2001 following the installation of a fleet management and control system. The introduction of GPS at both Orapa and Letlhakane mines have improved productivity and reduced operating costs in the areas of drilling, topographic survey and floor control. In vehicle tracking and dispatching GPS has allowed for real-time information management for timeous decision-making which optimized fleet run time hours.

Sep 1, 2001