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By M. H. Farjadi, J. Azari

Cost analysis of chrome ore reduction is one of the important issues facing ferrochrome producers in today?s competitive environment. Much of this depends on quality and various ratios in the actual ore. The latter can have a direct bearing on electricity consumption and optimum efficiency of the furnaces. While the industry has been successful in reducing costs by designing larger and more efficient furnaces, the role of the optimum blend of ore has perhaps been given less emphasis. This paper will discuss the general specification and metallurgical characteristics of various chrome ores for producing high carbon ferrochromium on industrial scale. By analysing the results obtained from smelting, including chromium recovery and energy consumption, the determining parameters in total cost of ferrochromium i.e. chrome ore; reductant and energy consumption can be optimized. Our study is based on actual experiences obtained from Faryab Ferroalloy Plant over a period of approximately three years.

Jan 1, 2004

By GA Harrison

The introduction of Extra Low Profile (XLP) mechanised equipment within Anglo Platinum is aligned with the overall New Mining Technologies strategy to focus on continuing modernization of our mining operations to achieve injury free sustainable production and cost effective mining technologies. The method allows for the introduction of a suite of XLP and Low Profile (LP) equipment in a narrow reef (1,2m) mining environment. For the first time it is now possible to achieve total trackless mechanisation at these stoping widths and XLP Breast mining has the potential to add more value when benchmarked with conventional mining and other mechanised methods. Various types of XLP equipment were tested at different sites within Anglo Platinum and this paper describes the XLP equipment evolution to-date. It concludes with recommendations on our future strategy regarding implementation and roll out of the XLP technology within Anglo Platinum.

Jan 1, 2008

By R. P. Mohring

The South African Coal Industry had its beginnings in the Eastern Cape in 1859 when coal was mined to satisfy the fledgling settlements in the Eastern Cape. The growth in the industry was relatively slow up to the early 1970s when, firstly, the export business was expanded coupled with a major increase in the quantity of coal converted to liquid fuels and utilized for power generation. To meet this increased demand the industry developed many new operations employing the latest mining technology and systems. Coal production in South Africa reached 204 million tons in 1996 and revenue from exports reached R8 billion making it the second-largest foreign exchange earner after gold. In his address Rick P. Mohring describes the role coal plays in the international energy scene and outlines South Africa?s position as a producer and consumer of coal, and the challenges facing the industry. A wide range of steam-coals are produced to satisfy both the local market (power generation, coal conversion and the metallurgical industry) and the export steam-coal market. South Africa is in a unique position regarding the export market as it is still a relatively low-cost producer and is geographically well-placed to play in both the European and Far East markets. There are, however, a number of challenges facing the industry. To retain our competitiveness in the international market, ways of minimizing the cost pressures caused by high-cost inflation, increased environmental protection obligations and a decreasing quality resource base need to be sought. Locally the coal mining industry has a major role to play in Eskom?s goal of reducing the real cost of electricity by 15% in the next three years. Safety and health, productivity and the adaptation of the latest technology are issues being addressed by the industry to maintain its dominant position within the South African economy.

Jan 1, 1997

[Ferro Alloys Producers Association The South Africa Institute of Mining and Metallurgy www.saimm.co.za Mintek www.mintek.co.za Eskom www.eskom.co.za ]

Jan 1, 2004

By S. Sarac

In this study, a statistical model is suggested in order to determine the methane emission from a working seam. In the proposed method, methane concentrations which are systematically measured in return airway are the sample values, and the calculated statistical parameter is the upper confidence limit of the average of these values. At any given time, the probability of methane concentration in the return airflow to be lower than the calculated upper confidence limit value is 97.5%. The statistical method has been applied to the panel 206 of Armutcuk Mine, Turkish Hardcoal Enterprises. The calculated methane emission value for the considered shift was 15.18 m3/t.

Jan 1, 2003

By Z. Jin, Q. Yun, C. Lu

This paper presents a quantitative assessment model for the assessment of environmental load in gold production, which is based on environmental ecology, Life-Cycle Assessment and technical conditions of gold production in China. This model can make environmental assessment in terms of a set of indexes and quantitative approach by means of artificial neural network, which also improves the theory of Life-Cycle Assessment. Keywords: Artificial neural networks, Environmental load, Assessment, Utility function, Gold production

Jan 1, 2003

By D. E. Ng?andu

The experience of Mufulira concentrator, of the Zambia Consolidated Copper Mines Limited, with underground mine drainage water, which is used in milling operations is discussed. It is shown that the underground mine water has a deleterious effect on flotation performance. The adverse effect of the underground water was successfully negated by adding lime into the primary ball mills and increasing the pH of the slurry, from a ?natural? pH of 8 to the flotation pH of 10.5. Traditionally, the pH modifier, quicklime, had been added downstream of the milling. Changing the lime addition point further reduced lime consumption by 50%,?a key issue as lime accounted for over 60% of the Mufulira flotation reagent costs. The nature of the effect of the underground water at Mufulira, particularly the sensitivity of the flotation to the pH at which the milling was conducted, characterized galvanic interaction. A large-scale plant situation is presented in which the desired electro-chemical response in the flotation was achieved, by a deliberate manipulation of the milling environment. The experience provides practical testimony of a more fundamental role for the milling process, other than the mere physical preparation, i.e. size reduction and liberation, of mineral particles prior to flotation.

Jan 1, 2001

By C. Dixon

This paper is based on the assumption of some knowledge of the National Water Act. It will consider the question of how that Act fits in with: a) existing laws which overlap on the subject matter b) new laws either in draft or in the process of being compiled c) policies which will eventually find their provisions included in new legislation (e.g. minerals policy) d) international practices. The focus will be specifically on the interaction of legislation relating to water use and water pollution in the mining sector as well as the role of the Department of Water Affairs in mining matters. Hence the title of the presentation.

Jan 1, 1999

By L. M. Sekhukhune

The atmospheric leaching of copper-bearing matte by acidic ferric chloride solution was studied at the laboratory scale. The aim was to achieve maximum copper and nickel recovery by investigating the mechanisms of leaching, as well as identifying the effect of temperature, and concentration of ferric chloride and oxygen. Djurleite (Cu1.96S), hazelwoodite (Ni3S2), and Ni alloy were the primary phases detected in the matte. The quantitative composition of the matte was Cu 31%, Ni 50%, S 13%. Fe and Co constituted 2%, with platinum group metals (PGMs) accounting for 0.5%. A maximum nickel extraction of 98% was achieved using two-stage oxidative leaching at 90°C and 11 g/L Fe3+ as compared to 65% under non-oxidative conditions. A copper extraction of 99% was achieved in the first 45 minutes using two-stage non-oxidative leaching, and copper was recovered from solution by cementation. Three processes took place simultaneously throughout the leaching process, namely: dissolution, cementation/ metathesis, and oxidation. The leaching process was found to be diffusioncontrolled.

Jan 1, 2014

By R. J. Forzatti

The production of sulphuric acid from sulphur generates heat. The majority of this heat is recovered as steam and is often used to generate electricity. Heat not recovered as steam is rejected to cooling water systems. The design of the turbine, condenser, and cooling water systems impacts the overall water, energy, and environmental footprint of the plant. This review considers a conceptual 2000 t/d sulphuric acid plant with several alternative cooling water systems. The review utilizes Hatch?s 4 Quadrant sustainable design tool to compare the alternatives on both an economic and a weighted sustainability scale.

Jan 1, 2014

By A. P. I. Popoola, T. J. Olaniyi, A. A. Adeleke

"A laboratory froth flotation experiment was conducted on a low-grade carbonatite copper ore sample obtained from Phalaborwa in the Limpopo province of South Africa. The sample was a homogenous hydrocyclone overflow which serves as the feed to the flotation cells at Palabora Mining Company (PMC). The sample has an average copper assay of 0.59% with predominant copper-bearing minerals being chalcopyrite, bornite and cubanite. The carbonatite nature of the ore comes from the high content of calcium (28.85%) and magnesium (6.84%) minerals. Collectors used were sodium diethyl dithiocarbamate and potassium ethyl xanthate alongside Senfroth 38 supplied by Senmin. The results showed that at 200 g/t mixture of collectors (50:50), an optimum grade of 8.03% Cu in the rougher flotation concentrate was achieved at 74% recovery, while during the second flotation, 24.65% Cu was obtained at 74.4% recovery using a Senfroth 38 dosage of 6 L/t with 100 g/t mixed (50:50) collectors. The particle size and pH value of the pulp played a significant role in that the mixed collectors performed efficiently at pH above 8.3 and at room temperature while particle sizes greater than 53 µm were well concentrated when compared with those of less than 53 µm. INTRODUCTION The need for copper ore concentration research is on the rise as a result of the depletion of deposits and the advent of low-grade copper ores. Although most copper ore deposits have other valuable minerals that support their economic extraction, the increase in technological innovations as regards copper usage and applications has increased the demand for copper. Several factors influence concentration results in a froth flotation column, of which the reagent used is most influential."

Jan 1, 2015

By F. T. Cawood

One of the consequences of globalizing mine finance is a necessity to apply uniform accountancy and valuation standards that are clearly understood and consistently applied by the global investment community. However, each country has unique circumstances, which sometimes make it difficult to align domestic practice with international requirements. South Africa is no exception and issues such as its political history, a taxation regime enforcing different rules on different mineral producers and a unique mineral rights ownership distribution, are barriers to internationalization. The economy is in a transitional phase as a result of the many and diverse policy documents following the change in political dispensation in 1994. Many of these documents have recently been implemented through new legislation and, in the case of mining, negotiations are continuing in order to ensure an acceptable outcome. This paper discusses the challenges that the South African minerals industry faces in the field of mineral property valuation. It draws on international experience and includes a discussion on the unique considerations that the South African mineral property market must take into account in establishing a code for this purpose, as such a code could later be aligned with international practice.

Jan 1, 2004

By M. Hakala

A computer program was developed to simulate transient strains and stresses during an overcoring in the situ stress measurement. The solution is based on superpositioning of elastic stresses. The measured strains can be compared with the calculated ones to check if the measured transient behaviour is accordant with the interpreted in situ state of stress. If not, the in situ state of stress can be calculated based on any transient or final strain values. The transient stresses can be compared with the strength envelope of intact rock and thereby estimate the core damage potential. Technically, the developed code fulfilled all the objectives, and the numerical error was found to be less than 5%. The basic idea can be applied also for different overcoring probes with minor modifications and recalculation of stress tensors. The analysed case studies showed clearly the advance of having an objective and practical quality control method to study the reliability of the in situ stress measurement data. The study was set up and funded by the nuclear waste management companies Posiva Oy ( Finland ) and Svensk Kärnbränslehantering AB ( Sweden ). Un programme informatique a été développé pour simuler des tensions et des contraintes passagères pendant la mesure in situ de contrainte de surcarottage. La solution se fonde sur une superposition de contraintes élastiques. Les contraintes mesurées peuvent être comparées avec celles calculées pour vérifier si le comportement passager mesuré correspond à l'état de contrainte in situ interprété. Sinon, l'état de contrainte in situ peut être calculé à partir de n'importe quelle valeur de contrainte passagère ou finale. Les contraintes passagères peuvent être comparées avec l'enveloppe de force de roche intacte et ainsi il est possible d'évaluer le potentiel de dégâts au noyau. Techniquement le code développé a rempli tous les objectifs, et le taux d'erreur s'est révélé être inférieur à 5 %. L'idée de base peut être appliquée aussi pour différentes expériences de surcarottage avec des modifications mineures et le recalcul de tenseurs de contrainte. Les études de cas analysées ont montré clairement l'avantage d'avoir une méthode de contrôle de qualité objective et pratique pour étudier la fiabilité de données de mesure de contrainte in situ. L'étude a été fondée et financée par les sociétés de gestion de déchets nucléaires Posiva Oy (Finlande) et Svensk Kärnbränslehantering AB (Suède). Es wurde ein Computerprogramm entwickelt, um Transient-Beanspruchungen und Spannungen während eines Überentkernens in situ-Spannung-Messung zu simulieren. Die Lösung beruht auf Superpositionierung von elastischen Spannungen. Die gemessenen Beanspruchungen können mit den berechneten Daten verglichen werden, um nachzuprüfen, ob das abgemessene Transient-Verhalten mit dem interpretierten in situ-Zustand der Spannung übereinstimmt. Wenn nicht, kann der situ-Zustand der Spannung auf irgendwelchen Transient- oder endgültigen Beanspruchungswerten berechnet werden. Die Transiet-Spannungen können mit dem Stärke-Umschlag des intakten Felsens verglichen werden und dadurch ein Kernbeschädigungspotential kalkulieren. Technisch erkannte der entwickelte Code alle Ziele und hat gefunden, dass die numerische Fehler weniger als 5 % waren. Grundsätzlich können auch verschiedene Überentkernen-Untersuchungen mit kleineren Modifizierungen und Wiederberechnung des Spannung-Tensors angewandt werden. Die analysierten Fallstudien zeigten deutlich den Fortschritt, objektive und praktische Qualitätskontrollmethode zu haben, die Zuverlässigkeit in Situ-Spannung-Messung-Daten zu studieren. Die Studie wurde aufgestellt und durch Atommüll-Management-Firmen Posiva Oy (Finnland) und Svensk Kärnbränslehantering AB (Schweden) finanziert.

Jan 1, 2003

By J. H. Potgieter

The method used to assess the reactivity of lime was evaluated to gauge it usefulness as a quality control tool. The effect of particle sizes, different lime and water masses for a fixed s:l ratio and the same for various s:l ratios on the reactivity values obtained, were investigated. An attempt to introduce the amount of grit produced during the slaking reaction as an additional measure of limeís quality and reactivity, proved to be unsuccessful. It was also found that the relative amount of lime slaked during the different tests was independent of the reactivity value of the lime. The investigation confirmed the usefulness of the accepted test procedure as are liable method to measure the reactivity of lime, despite various reservations expressed from a theoretical point of view.

Jan 1, 2002

By J. S. Harington

Our purpose is to record and to explain the widely changing numbers of the huge total of black workers on the gold mines of South Africa over the century from 1896 to 1996. These men were recruited from up to twenty territories, and their contributions are examined. The major areas providing labour over this long period have been Lesotho, the former Transkei within South Africa and Mozambique. From 1989 to 1996, for instance, these three areas accounted for over sixty per cent of the total labour force (tlf). Our principal Figure 1 shows the tlf fluctuating through time to reach a peak of 480 000 in 1988. Irregular falls are also documented with the most serious in 1995 to 180 000. Based on this graph we consider the political, economic, sociological and historical reasons behind these changing employment opportunities. These have included external world-scale events such as war or depression, as well as internal changes of national economy and policy. We show the importance for numbers employed of the discovery of gold in the Orange Free State in 1946, the influence generally of the ?Winds of Change? and the firm maintenance by the State of law and order. Varying gold production costs and profitability against high tax rates, allied with increasing wages and a lack of development capital, have led in the last decade to employment falling by fifty per cent, despite an actually higher value of gold output. Finally, this analysis considers the role of the migrant labour system as it affects, and is affected by, conditions in the gold mining industry, with special reference to its less than humane consequences in the numerically dominant territories of Lesotho and Transkei.

Jan 1, 2004

By H. Simonsen

Risk assessment consists of a search for the answers to: ?What can happen? ?How likely it is that it can happen? ?What are the consequences if it does happen? Perhaps the most important aim of risk analysis is to predict the likelihood that a planned profit will be achieved over a given period of time. A typical risk model employed for this purpose includes a stochastic connection between the dependent variable of an expression that describes a process and independent variables represented as random quantities. The output will be a probabilistic distribution. The uncertainties in a planned mining operation include: ?Commodity market characteristics, particularly price ?Ore reserves and mineralogical composition ?Mining method ?Process performance ?Capital and operating costs ?Schedule duration ?Economic environment effects. The processes employed in the probabilistic estimation of a project?s outcome include both Monte Carlo simulations and simulations where variable correlation is considered important. The risk model, once developed and tested, provides a framework for a rational approach to risk analysis and the testing of alternatives.

Jan 1, 1999

By J. Bongardt

Ecologically acceptable techniques are described for the handling of waste materials from the fabrication industry. New production methods and the recycling of sludges from grinding and other waste materials are suggested.

Jan 1, 1997

By H. C. de Wet

The predevelopment and preparation of a total infrastructure in a deep level mining environment, prior to the shaft system being commissioned has major advantages. This paper intends to indicate these advantages and outline an understanding of the disadvantages. These benefits can be classified in three basic groups: the financial and timing advantages, a knowledge of the ore body and the development of required technology to meet the design parameters. The required technology in many aspects was still to be developed prior to successful application. Stemming from the technological evolution are some secondary advantages which will be described in each of the groups. Safety and health considerations and some practicalities made some of the new technology redundant prior to the actual application. In each case the actual achievements and the anticipated benefits will be indicated to allow the reader to distinguish clearly between planned and actual achieved advantages.

Jan 1, 1997

By S. N. Opperman

Testwork at Goedehoop Colliery showed that fine coal, essentially?150 microns can be successfully beneficiated using froth flotation. Both conventional and column flotation were tested. It was found that the traditional stirred tank type of flotation machines used in conventional flotation produced the best recovery of fine coal. After extensive testwork it was decided to develop a flotation machine on Goedehoop Colliery that would combine stirred tank and quiescent column technology. It was thought that this design would give the best combination of recovery and selectivity. The Multicell was developed and is producing results acceptable for Witbank coal flotation. Keywords: Multicell, Witbank coal flotation, froth, stirred tank, quiescent column.

Jan 1, 2002

By A. A. Smithen

There is an increasing awareness of the importance of including an assessment of environmental liabilities in the preparation of bankable feasibility documents. This means that environmental assessments of proposed, existing and decommissioned mine sites have to be undertaken for the purposes of quantifying environmental liabilities and assessing potential risks. This paper examines the need for considering environmental liabilities before describing the approach adopted in undertaking due diligence studies for the preparation of bankable feasibility documents and some of the difficulties experienced. Finally, some concluding remarks are made and the implications for the mining industry are discussed.

Jan 1, 1999