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By D. Pohl

The past decade has seen rapid expansion in the West African mineral exploration environment. This expansion has been largely driven by changes in ?Political climate ?Fiscal and legal regimes ?Exploration approaches ?West African geology. Major regional mapping and geochemical surveys by the UNDP, and the BRGM in the late 1970s and early 1980s laid the foundation for the rapid development of mineral exploration and resources during the past decade. An additional driving impetus was the discovery by native artisanal miners of many significant new gold occurrences at Libiri, Essakan, Bouda and Tirahori, during the great droughts of the late seventies and early eighties.

Jan 1, 1998

By G. H. Lind

This paper discusses the traditional costing approach currently used in the underground coal mining industry. Activity Based Costing (ABC) is identified as being a potentially more effective manner in which to cost underground coal mining systems. With the use of a costing framework developed by the author incorporating new thinking to eliminate the shortcomings identified in the traditional costing approach, a comparison of two types of underground coal mining systems, viz. continuous miner and longwall, is conducted. It is found that under certain criteria, in all cases, irrespective of the way in which the systems are costed, the continuous miner system is currently the better investment. It is also observed that when a system is costed using ABC that better investment decisions result when compared to costing the same system using traditional costing techniques. It is further seen that traditional costing techniques tend to overestimate the total costs of a mining system. This paper shows one application of ABC that can be incorporated as a management tool.

Jan 1, 2001

By A. H. Swart

Rock engineering is concerned with the design of rock structures generated by mining activities. Therefore, rock engineering designs have major implications for the safe recovery of mineral deposits and operating costs. The paper deals with a few challenges facing rock mechanics engineers operating in the hard rock underground mining environment in South Africa. Finally, examples are included, which may assist rock mechanics engineers in providing better designs, which could ultimately lead to further improvement in safety and lower operating costs.

Jan 1, 2005

By C. Sensogut

The phenomenon of spontaneous combustion is one of the major hazards encountered in underground coal mines both from the safety aspects and on economic grounds. Every occurrence, however small, if not tackled effectively in the early stages can develop into open fire, or explosion of gas or coal dust. In terms of economy, even dealing with small incidents may be costly in terms of labour and materials, and in case of a sealing off of a district being necessitated, the loss of face equipment and sterilization of reserves is potentially great. Therefore, expense and effort in prevention and detection of such heating, together with a high state of readiness for dealing with likely event, is completely justified and may be considered as a sound investment. In order to achieve this investment, it may be worth to pinpoint the centre of the fire occurring due to autogenously heating which is supposed to be great assistance to inert it at a least cost and time. Therefore, it is the aim of this work to model the spontaneous combustion in the goaf.

Jan 1, 2002

Outsourcing of specialist and non-continuous services is common practice in international mining operations. There is an increasing trend towards this practice in South Africa as a result of the major organisational changes that have taken place in the industry, and as lower revenues and production cost pressures have reduced profit margins. Many specialist functions have been outsourced in the industry for a long time, an example being shaft sinking, which is undertaken by specialist shaft sinking contractors. In the professional services area, some activities have been outsourced, for example the design and construction supervision of tailings dams, but mining related activities such as geology, mine planning and scheduling, engineering, ventilation, and rock engineering, have traditionally been carried out by in-house staff. In this paper some of the industry problems which have led to an increase in outsourcing of professional services are considered. Then the pros and cons of outsourcing are dealt with before outlining the factors which should be taken into account in choosing an outsourcing partner.

Jan 1, 1999

Dr R. E. Robinson, Pr. Eng., obtained a B.sc. (Chem. Eng.) cum laude from the University of the Witwatersrand in 1950 and a Ph.D. (Eng.) from the same University in 1953, where he was awarded the Haikes Memorial Medal for Industrial Chemistry. Professor G. G. Garrett was appointed Professor of Physical and :Fabrication Metallurgy in the Department of Metallurgy at the University of the Witwatersrand in June 1980, and in January 1984 he became Head of the Department. Mr P. A. van Wielligh, Pr. Eng., climbed the mining ladder in the hard way, starting as a Mine Surveyor in 1936 and working his way up as Chief Surveyor, Underground Manager, Mine Manager, and Consulting Engineer, to Executive Director, including the intermediate steps. Mr H. E. James, Pr. Eng., is a graduate in Chemical Engineering from the University of the Witwatersrand. Both his B.sc. degree (1961) and his M.sc. degree (1964) were obtained on bursaries, the former from Gold Fields of South Africa and the latter from the Atomic Energy Board. Mr G. Pienaar, Pr. Eng., obtained a B.Eng. (Met) in 1967 and an M.Eng. in 1973, both from the University of Pretoria. Dr A. K. Haines, Pr. Eng., obtained all his degrees from the University of Natal, finishing with a. Ph.D. in 1971. Mr B. C. Alberts, Pr. Eng., obtained his academic training at the University of Pretoria, where he was awarded B.sc. degrees in both agricultural engineering (1963) and mining engineering (1965). Mr H. C. van Zyl, Pr. Eng., holds B.sc. degrees in mining engineering (1968) and civil engineering (1972), both from the University of Pretoria.

Jan 1, 1984

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 A. Hammel

This paper summarizes indigenous mining methods used to collectmetal ores in pre-colonial southern Africa, south of 15°S. These methods, for the purposes of discussion, are divided into sections inorder of increasing organizational complexity, from scavenging,which only required basic equipment and a relatively minimal division of labour, to underground mines, which necessitated complex planning to overcome obstacles such as the need for illumination and ventilation. Examples concerning the pre-colonial exploitation of iron, copper, tin, and gold have been taken from the archaeological literature. This review paper provides an introduction to the technology that was available to and used by miners in the past, illuminates some of the factors limiting their operations, and supports the claim to the indigenous nature of this activity

Jan 1, 2000

By J. Nell

An overview is given of the matte melting process used for the beneficiation of South African platinum group metal (PGM) ores. Most producers use six-electrode furnaces to melt the concentrate and Pierce Smith converters to oxidize excess iron sulphide from the furnace matte. Concentrates from two reef types (the so-called Merensky and UG-2 reefs) dominate the feedstock supply. Concentrate from the Merensky Reef is low in chromium and does not pose significant melting problems. Concentrates from the UG-2reef contain much higher levels of chromium, which results in the formation of chromium-rich spinels during melting. This is attributed to the low solubility of chromium in furnace slag under typical operating conditions (an oxygen partial pressure of 10-8?10-9bar at temperatures of 1550°C to 1600°C). During the converting process, care is needed to avoid excessively oxidizing conditions, which result in cobalt, nickel and copper losses to the slag. High nickel losses result in the formation of Fe2NiO4 (trevorite), which often forms solid solutions with FeCr2O4and Fe3O4. In future, the main challenge in the processing of South African PGM ores will be to cope with ever-increasing levels of chromium in the concentrate. A short-term solution to the problem would be to melt the concentrate under slightly reducing conditions to promote the formation of CrO, which is more soluble in the slag than Cr2O3.A longer-term solution to the problem would be to abandon the current matte-smelting process in favour of an alloy-based process, which would offer total flexibility with respect to the amount of chromium that can be tolerated in the feed. Keywords: Merensky, UG-2, furnace, slag, matte, converting, spinel, chromium

Jan 1, 2004

By R. L. Lawson

I?ve been asked to appraise the global role of coal and mining, and the best place I can think of to begin is with the World watch Institute, which purports to monitor all things global. Last fall the institute?s magazine, entitled World Watch, in a cover story called for a worldwide campaign to outlaw the use of coal before this century?s end. To my mind the article began the campaign. However, the institute had to admit that no such ban will be possible unless there is special help and heavy intervention?that is, novel policies and punitive taxes. I?ll quote directly from the magazine to underscore the point: ?without them the market will continue to deceive us into thinking coal is cheap, abundant and irreplaceable?.

Jan 1, 2001

The typical reactions which the reductants undergo during ferroalloy production are reviewed, and identified as reaction with CO2 and with SiO, and dissolution in metal. Available reactivity tests for these three reactions are reviewed. It is proposed that it is worthwhile considering dissolution kinetics as a reactivity parameter. Greater crystallinity of the reductant decreases CO2 and SiO reactivity, but increases dissolution rates.

Jan 1, 2002

By D. Mkhwanazi

The purpose of the project was to optimize load haul dump (LHD) machinery use as they were spending too much time doing what they should not be doing. During the investigation, the author found that the machine's actual availability was 86% and the utilization ranged between 30% and 42%. This shows that the availability of the machine has met its target. Therefore the main problem was with the LHD utilization and that is what the project focuses on. To satisfy the objectives, the author firstly studied the existing mining data like the key performance indicators (KPIs) in order to analyse the machine's availability and utilization; this is what gave direction to the problem. Secondly the author did a literature review on mines with similar problems. This gave the author ideas on what to look at in approaching such a situation. Thirdly, the author gathered information on what the LHDs are doing on a daily basis by doing a time study. This gave the author an idea of how long it took the LHDs to complete a specific task. The author also interviewed operators and their supervisors in order to find the best practice work. This helped in identifying the problem areas when comparing the best practice work with what the LHDs are actually doing. According to the project results, it was found that the LHDs are underutilized due to shortage of drivers and the long distances the LHDs have to travel for material loading and refuelling. The author recommended that the machine utilization should be improved by training more operators in order to eliminate the 'no operator' downtime; the cost arrangement of this recommendation is included in the report. The author also recommended that the travelling time should be reduced by using tractors instead of LHDs when long distances need to be travelled for material loading. Another recommendation for reducing travelling time was to bring the mobile fuel tank closer to a section; the cost arrangement for this recommendation is also included in the report. Keywords Optimizing, LHD utilization, LHD availability, key performance indicators (KPI), shortage of drivers, long distances, mobile fuel tanks.

Jan 1, 2011

By F. Lanaro, K. Röshoff, R. Christiansson, L. Jing

This paper presents the results of a project for developing a methodology for empirically determining some of the mechanical properties of the rock mass at the Äspö Hard Rock Laboratory, Southern Sweden. Using the equations available in the literature, the deformation modulus, friction angle, cohesion and unconfined compressive strength of the rock mass were estimated. A comparison of the results using different classification methods (Q, RMR, GSI, RMi, Ramamurthy’s) was made to estimate the range of variations in the mechanical properties with the considerations of: i) the quality/quantity of the geological data; ii) the technique for partitioning of the rock mass into homogeneous domains; iii) the sensitivity and subjectivity of the empirical methods; and iv) the need for validating the empirical methods against a test case. Cet article présente les résultats d’un projet visant à établir une méthodologie, pour déterminer, de façon empirique, les propriétés mécaniques de la masse rocheuse. En utilisant les corrélations disponibles dans la littérature, quelques-unes des propriétés de la masse rocheuse ont pu être déterminées (module de déformation, angle de friction, cohésion, force de compression illimitée). Une comparaison des résultats obtenus par différentes méthodes (Q, RMR, GSI, RMi, de Ramamurthy) a permis d’établir une échelle de variations des propriétés mécaniques et de formuler une série de recommandations concernant : i) la qualité/quantité des données géologiques ; ii) la technique de partition de la masse rocheuse dans des domaines homogènes ; iii) la sensibilité et la subjectivité des méthodes empiriques ; iv) la nécessité de valider les méthodes empiriques à l’aide de nouvelles études de cas. Dieses Paper präsentiert die Ergebnisse eines Projekts mit dem Ziel, eine Methodik für die empirische Festhellung von mechanischen Eigenschaften im Gesteinmassiv zu etablieren. Durch Verwendung der in der Literatur zugänglichen Korrelationen, wurden einige Eigenschaften des Gesteinmassivs festgestellt (Entstellungsmodul, Reibungswinkel, Kohäsion, unbeschränkte Kompressionsstärke). Ein Vergleich der Ergebnisse unterschiedlicher Methoden (Q, RMR, GSI, RMi, Ramamurthy’s) wurde durchgeführt und dies erlaubte die Feststellung der Variationsskala von den mechanischen Eigenschaften, sowie eine Reihe Empfehlungen für: i) Qualität/Quantität der geologischen Dateien; ii) die Technik für Teilung des Gesteinmassivs in homogene Domäne; iii)die Empfindlichkeit und Subjektivität der empirischen Methoden; iv) das Bedarf die empirische Methoden gegen neue Fallgeschichten zu validieren.

Jan 1, 2003

By O. Gunaydin

Performance measurements of large-diameter circular saws were conducted on eight different carbonate rocks in marble factories located in some areas of Turkey. Rock samples were collected from these factories for laboratory tests. Uniaxial compressive strength, tensile strength and impact strength were determined in the laboratory. The brittleness of B3 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength), the brittleness of B5 (the product of percentage fines in the impact strength test and compressive strength) and the brittleness of B8 (half of the product of compressive strength and tensile strength) were calculated from the test results. Hourly slab productions were correlated with brittleness indexes. It was concluded that sawability of carbonate rocks can best be predicted from the brittleness of B8.

Jan 1, 2004

By E. Yalçin

The data set often contains one or more secondary variables. These secondary variables are usually spatially cross correlated with the primary variable. The addition of the cross-correlated information reduces the variance of the estimation error by using the cokriging method. The grade estimation results of ordinary kriging and cokriging methods are evaluated and it was found that the estimation variance of cokriging method is slightly lower than ordinary kriging. The effect of variation of block dimension on the estimation results is also investigated and it was seen that the cokriging estimation variance values also decrease as the block dimension increases.

Jan 1, 2005

By R. J. Davidson

Arguments are presented in favour of a new interpretation of the chemistry pertaining to the dissolution of gold, when this takes place in typical gold plant leach circuits where calcium is present in solution. It is suggested that under these conditions the standard chemistry, as it applies in the absence of calcium, is no longer valid. Thus the concept of very soluble sodium and aurocyanide ionic species in solution is replaced by the presence of weakly soluble calcium aurocyanide, which is a covalent coordination complex that is non-ionic. Supporting evidence for this is provided and the implications that the presence of calcium in gold plant circuits may have for operational efficiency are discussed. In particular, because of the formation of this weakly soluble calcium complex, the addition of lime to the leach circuit is questioned. Arguments for the use of a sodium hydroxide/sodium carbonate/sodium bicarbonate buffer solution as a means of controlling pH and of increasing ionic strength in a so-called ?soft? leach are presented. Such a lime-free system, besides benefiting the leaching of gold, would have many downstream benefits in existing CIP circuits. Furthermore, the direct electrowinning of gold from the leach now becomes potentially feasible.

Jan 1, 2007

By W. Pulles

Mining can adversely affect water quality and poses a significant risk to South Africa?s water resources. Proactive management of environmental impacts is required from the outset of mining activities in order to reduce this risk. Major strides have been made over the last 7 to 8 years, by both the Department of Water Affairs & Forestry (DWAF) and the mining industry, in developing strategies and management plans for the effective management of water within the industry. This has largely been achieved through the development of joint structures where problems have been discussed and addressed through cooperation. This process, which was started around 1991, has continued through to the present time. The mining sector management strategy has been developed at a number of different levels as follows: ?A detailed Management Plan, that sets out strategic objectives, broad strategies and functional and organizational arrangements. ?Operational Guidelines, that define and document specific operational procedures. ?Technical Guidelines, that define and document best practices for pollution prevention and impact minimization from mining operations. The Technical Guidelines consist of Best Practice Guidelines (BPGs) and Regulations.

Jan 1, 1999

By G. Broadbent

It is an honour to be invited as a speaker to this ICCR conference and a pleasure to be with you here in South Africa. I have been asked to talk about the competitiveness of coal versus other energy alternatives. Coal supplies nearly one-quarter of the global primary energy. Its most direct competitors are gas, nuclear and renewables. Oil is predominantly for transport fuels. Fuel oil is competitive with coal when crude is below its long-run average price and has some niche opportunities. But I will confine my comments to nuclear, renewables and particularly natural gas as the most potent current competitive threat to coal. Competitiveness is more than just cost and price; there is environmental acceptability, security or reliability and increasingly image. These factors are more of a spectrum than discrete issues. Dollars and cents remain the key issue for competitiveness but one must recognize the impact of politics in sustainable development and energy security.

Jan 1, 2001

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements set out on pages 269 to 276. These financial statements are the responsibility of the Institute?s Council. Our responsibility is to report on these financial statements. We have conducted our audit in accordance with generally accepted auditing standards. These standards require that we plan and perform the audit to obtain reasonable assurance that, in all material respects, fair presentation is achieved in the financial statements. The audit included an evaluation of the appropriateness of the accounting policies, an examination, on a test basis, of evidence that supports the amounts and disclosures included in the financial statements, an assessment of the reasonableness of significant estimates, and a consideration of the appropriateness of the overall financial statement presentation. We consider that our auditing procedures were appropriate in the circumstances to enable us to express our opinion presented here. In our opinion these financial statements fairly present the financial position of the Institute at 30th June, 1999, and the results of its operations for the year then ended in conformity with generally accepted accounting practice.

Jan 1, 1999

By F. T. Cawood

The definition of mineral rents has historically been somewhat unclear, but a growing understanding of the source and composition of the revenues that comprise these rents mean that they can be more easily identified and quantified. Furthermore the way in which the flow of the rents from mineral developments are captured and then distributed has been a point of contention amongst the various stakeholders. Investors, the host government, the resource owners, environmental interests, indigenous groups and land owners are identified in this paper as the principal participants in mineral development and while each is entitled to a portion of the rent, the size of their portions will differ. A competitive rent-sharing model for southern African countries has been established and indicates how the range of stakeholders could be rewarded for their contribution. Acceptance of the sharing ratios amongst the recipients is a function of their understanding of the size of the rent and their position in the hierarchy of stakeholders. At first glance investors appear to receive the largest share of the rent, but they disburse some of the rent to hidden costs, which when all is said and done, means that investors and host governments retain approximately equal shares of the mineral rent. Both the investor and government are faced with the dilemma of how to equitably distribute the rents they have captured to minority stakeholders. Government captures corporate tax, mineral royalties and a wide range of subordinate taxes, but is required to construct policies that will ensure distributional equity among the various levels of government as well as among the provinces that comprise the country. Investors will have to ensure that a portion of the rents they capture are diverted to other stakeholders namely resource owners, environmental interests, indigenous peoples groups and the landowners. This paper identifies the major recipients of rent and provides some indication of equitable distribution ratios for mineral wealth among them?a first step in ensuring that mineral development is compatible with long-term sustainable development and in the best national interests.

Jan 1, 2002