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By L. du Preez, J. D. Steenkamp

This paper introduces the concept of clean steel production from a pyrometallurgist’s perspective to the broader metallurgical community. A simplistic overview of the steelmaking process from iron ore to car body manufacturing is followed by an introduction to the South African steel industry and the technologies that it utilizes. The process is illustrated by an overview of the flow sheet and technologies for the production of clean steel at Saldanha Steel, South Africa.

Jan 1, 2015

By T. Frömmer, H. Wagner

An inter-disciplinary geotechnical study has been carried out in an Austrian magnesite mine. The paper describes the how geological data, in situ and laboratory tests as well as subjective, empirical, geophysical and numerical methods have been used to identify critical areas in the mine. In einem österreichischen Magnesit Bergbau wurde in den letzten Jahren eine interdisziplinäre geotechnische Studie durchgeführt. Der Vortrag beschreibt den Einsatz subjektiver, empirischer, geophysikalischer und numerischer Methoden zur Identifikation geotechnischer Problembereiche Ces dernières années des études géotechniques interdisciplinaires sont effectuées dans une mine souterraine de magnésite en Autriche. Ce rapport trace l’application des méthodes subjectives, empiriques, géophysiques et numériques pour identifier les zones problématiques dans la mine

Jan 1, 2003

The Annual General Meeting of the Johannesburg Branch of The South African Institute of Mining and Metallurgy was held at the Johannesburg Country Club on Tuesday, 21st July, 1992. Big turnout at Lunchtime Lecture The re-introduction of Lunchtime Lectures by the Johannesburg Branch of the South African Institute of Mining and Metallurgy met with resounding success when more than 100 delegates packed the Standard Bank auditorium in Simmonds Street to hear Dr Zach de Beer, leader of the Democratic Party, give his views on the state of the nation.

Jan 1, 1992

By J. Trckova, P. Prochazka

Physical models from equivalent materials satisfying geometrical and physical similarity have been constructed. A special technology of simulating the excavation of an opening at the front part of a tunnel and of measuring the deformation at the tunnel face was applied. The results yielded by the physical models were used to formulate constitution relations in the numerical solution. This coupled modelling enables us to predict the behaviour of tunnel structures more accurately. On a construit des modèles physiques, réalisés en matériaux équivalents et répondant aux conditions de ressemblance géométrique et physique. Sur ces modèles, on a utilisé une technologie intéressante de simulation du forage du tunnel et de la mesure de déformation du front de taille pendant le forage en progression. Les résultats donnés par les modèles physiques ont été utilisés pour formuler les relations de constitution dans la solution numérique. Une telle construction de modèles combinés permet de prévoir plus précisément le comportement de la structure du tunnel. Es wurden physikalische Simulierungsmodelle aus äquivalenten Werkstoffen konstruiert, welche die Bedingungen der geometrischen und physikalischen Ähnlichkeiten erfüllen. Bei diesen Modellen hat man die interessante Simulationstechnologie des Tunnelvortriebs sowie die Verformungsmessung beim Tunnelabbaustoß während des Vortriebsvorgangs eingesetzt. Die Ergebnisse der physikalischen Simulation wurden zur Formulierung von Konstitutionsrelationen in der numerischen Lösung genützt. So eine kombinierte Simulation erlaubt eine genauere Prognose des Benehmens der Tunnelstruktur.

Jan 1, 2003

In today?s high tech world, systems are getting bigger, faster, better. To remain at the leading edge, in any business, depends on accurate but flexible design thereby allowing operational managers to provide alternatives to improve their operations. The ultimate goal is to deliver to plan, with optimum economics. Mining is no different, with falling prices and escalating costs, improved margins become the focal objective. There are many ways to achieve this, ranging from operational efficiency improvements through production scenarios to planning initiatives. Of all, planning usually receives the least attention, yet it is the area of most influence on the NPV of the reserve. With computer technology, numerous concepts and iterations are possible thereby closing the gap between optimal and actual design. This paper discusses the application of the split shell design at the De Beers Venetia open pit in South Africa.

Jan 1, 2001

By D. G. Krige

Using chip sample data and spatial structure parameters from a large mined-out section of a South African gold mine the advantages to be gained from a regular underground borehole drilling programme have been investigated for short- and medium- to long-term planning based on block valuations. The results have been compared with the current position, which relies invariably on the extrapolation of limited peripheral sampling data from raises, gullies or stope faces. Some preliminary work has also been done regarding the implications of such underground drilling on costs used for the present pay limit calculations. The results of the study, though preliminary, show that the net advantage of advance regular underground drilling could be substantial and that a more intensive follow-up research is warranted.

Jan 1, 2003

This paper presents an initial investigation into the viability of co-kriging the grades of multiple mining cuts in a two dimensional, thin reef scenario. Deposits with gradational mineralized zones, in the perpendicular sense, are not as well served by the use of reef accumulation and thickness as deposits characterized by a sharp distinction between ore and waste rock. South African Bushveld Complex platinum deposits and Witwatersrand gold deposits are examples of this distinction. The calculation of an optimal mining cut is of paramount importance in the mining of Bushveld platinum. Two-dimensional kriging of a constant stoping width mining cut is an effective method for resource calculations once a cut is decided, but this begs the question of how to decide on the cut. Comparison of multiple cuts is used as a way of achieving this decision on many of Anglo Platinum’s operations. Although the kriging of each cut is valid in isolation, occasional negative values occur when incremental grades between overlapping cuts are calculated. Negative incremental grades cannot reflect reality. They are thought to be related to the inability of the method to include the strong continuity in the perpendicular direction demonstrated by the relevant variograms. Co-kriging of related variables has been investigated as a potential means tore impose this inherent order relationship. Various co-kriging options have been investigated. The method has been tested on a real data set from an established platinum operation. One of three types of anomaly has been investigated so far. The results show that co-kriging the mining cut grade as the primary variable, with just one secondary variable, the reef thickness, eliminates most occurrences. Severe anomalies remaining are arguably indicative of population mixing and might be more effectively treated by rezoning the data. Aim—To investigate the viability of co-kriging the grades of multiple mining cuts as a method for resolving anomalies in the estimation of such cuts on Bushveld platinum deposits, with applicability to other thin reef type deposits with a gradational not sharp cut-off between ore and waste in the direction perpendicular to the reef. Keywords: co-kriging, cross variograms, ordinary kriging, platinum, two-dimensional, grade profile

Jan 1, 2003

By A. Galibois, A. Dubé, H. Monette, J. L. Collins

"The start of mining operations often raises serious financial problems. In marginal cases promoters frequently demand financial aid from governments.In the past, the financial assistance has taken the form of gifts, procurement contracts, etc., but aid in such form has been severely criticized. A new formula has been developed to provide a more equitable distribution of the revenues accruing to the government and to private capital.The benefits to these two parties have been evaluated in an hypothetical case and compared in terms of internal rates of return on their investment, their shares of the undiscounted cash flows and their primary profits.The method based on the non-zero sum game theory provides a means for suggesting the lowest feasible annual production and the optimal sum contributed by the government in the form of outright gift, equity capital and convertible bonds. Other financial hypotheses can also be optimized by the computerized analysis."

Jan 1, 2014

Abstract : The computation of reliability index or failure probability of slopes can be transformed into an optimisation problem. In high rock slope engineering, it is usually a multimodal optimization problem. The traditional optimization techniques are difficulty to find out the global optimal solution because of their easily falling into local optimal value. Recently, a new kind of bionic algorithm - ant colony algorithm (ACA) - has been used to solve this problem. In this paper, the structure of ant colony algorithm and the transfer probability of ants are modified to evaluate the failure probability of complicated slopes. A new adaptive ant colony algorithm (AACA) is proposed to determine critical slip surface and its corresponding failure probability of complicated slopes. A case study is given to verify the proposed approach. The results show that the presented method has obvious advantages compared with traditional methods. ZUSAMMENFASSUNG: Die Rechnung des Zuverlaessigkeitindexes oder der Zerstoerungswahrscheinlichkeit kann sich in einer Optimierungsfrage umwandeln, im Bauprojekt an hoehe Gebirgehang, handelt es sich meistens um eine Optimierungsfrage ueber Multi- Spitzenwert. Mit der traditionelle Optimierungsmethode ist es schwer eine umfassende Loesung fuer die Optimierung zu finden wegen des leichte Verfallens in Beschraenkung der Teiloptimierungsloesung. Mit dem neue Bionik- Algorithmus —— Ameisen - Kolonie- Algorithmus wird dieses Problem geloest. In diesem Text hat man eine Strukturverbesserungsloesung fuer das Ameisen- Kolonie -system und die Wahrscheinlichkeit der Ameisenkolonie erwaehnt, und damit wird man die Zerstoerungswahrscheinlichkeit des komplizierte Hangs feststellen. Mit dem neuen Ameisen- Kolonie- Algorithmus kann man die gefaehrlichste Gleitflaeche und die entsprechende Zerstoerungswahrscheinlichkeit herausfinden. Die in diesem Text beschriebene Methode wurde durch Praxis geprueft. Durch die Pruefergebnisse wurde es gezeigt und bestaetigt, dass der neue Bionik- Algorithmus vorteilhafter als der traditionelle Algorithmus ist. Résumé : Le calcul de l’indice la fiabilité ou de la probabilité de ruptures peut être transformé en un problème de l’optimisation. Pour le cas du génie des pentes de haut rocher , le problème se pose en général en l’optimisation de multi-crêtes. Les techniques traditionnelles conduisent facilement à la solution optimal partielle au lieu de celle globale. Récemment un nouveau type de bionique algorithmique a été appliqué pour la solution de ce genre de problèmes, c’est l’Algorithme Colonie de Fourmis. Dans l’article il est proposé de modifier la structure du système de la colonie de fourmis et la probabilité de transfert des fourmis en vue d’évaluer la probabilité de ruptures des pentes de haut rocher complexes, par ailleurs un nouveau algorithme adapté de colonie de fourmis est formulé pour déterminer la surface glissante critique et la probabilité de ruptures correspondante. Les techniques proposées dans l’article sont vérifiées à travers des expérimentations dont les résultats ont prouvé que les techniques présentées dans l’article sont évidemment meilleures que celles traditionnelles.

Jan 1, 2003

By T. V. Nguyen

The feedwell performance in gravity thickeners and clarifiers relies on the efficient mixing between solid particles and flocculant to achieve effective flocculation, as well as energy dissipation of the incoming feed stream. A population balance-computational fluid dynamics (PB-CFD) model has been developed and validated to provide new insights into the operation and performance of industrial feedwells. In particular, the PB-CFD model enables the efficacy of the main functions of a feedwell to be investigated for a wide range of feedwell designs and process conditions. This paper describes how PB-CFD was used in the design and development of a new feedwell concept for the flocculation of particles in a solid-liquid stream. The patented feedwell design includes an upwardly converging flow diverter to create two separate compartments for energy dissipation and flocculation. PB-CFD simulations of this simple and easy-to-retrofit feedwell design illustrate a superior performance in terms of flocculation and energy dissipation compared to typical feedwells over a wide range of flow conditions. The potential benefits include reduced flocculant consumption, better de-aeration, greater stability and the ability to cope with a wider variation in volumetric throughput, better flocculation and fines capture, and a more symmetrical discharge that may also offer improved overflow clarity in some applications. The new feedwell design has been installed in a full-scale thickener at an Anglo American Platinum site in South Africa. A number of operational factors complicate this application, but indications are that the new feedwell has led to improvements in stability and underflow properties.

Jan 1, 2012

By D. Tsweleng

In the Evraz Highveld production process, iron ore is prereduced in rotary kilns prior to charging into submerged arc furnaces (SAFs). Owing to the highly aggressive slags that are formed within the combustion zones of these kilns, chrome-oxide-containing lowcement castables have been used for some years in the kiln lining. Due to concerns around the potentially harmful effects should Cr(V1) be present in the spent linings, Highveld and its suppliers of kiln castables devoted time to developing alternative chrome-free lining materials. Such materials needed to be cost-effective and ensure good performance and improved kiln availability. This paper discusses all the parameters surrounding this development. Keywords Low-cement castable, chrome-oxide free, chrome (VI), titaniferous magnetite ore, rotary kiln, submerged arc furnace, open slag bath furnace, Evraz Highveld Steel & Vanadium Limited.

Aug 1, 2013

By N. L. Ayres

Tendon support systems have been successfully used to stabilize excavations. Tendon support systems are routinely designed using the axial load-bearing capacity of tendons, namely the tensile strength. To attain tensile strength the tendon must be loaded along its length, which often does not occur in practice. Tendons should optimally be installed at 90° to the surface of the excavation to achieve maximum penetration depth, yet this is often not physically or practically possible, and installations at angles less than 90° occur. Furthermore, the intersection of geological features within the rock mass frequently results in complex loading situations on tendons. The position and angle at which loading occurs results in different combinations of tensile and shear forces acting on the tendon, which can impact on the support performance of each unit and ultimately the whole system. All factors that influence the support system should be understood and taken into account to ensure a sound support design. Combination loading situations are further investigated and tested to obtain a better understanding of the mechanisms involved and the effects on tendon load-bearing capacity. Tendon support units were tested at different installation angles to establish the tendon performance, mechanical behaviour, and load capacity during these loading situations. The results and outcomes are aimed at providing rock engineers with additional data and improved understanding of how tendons could perform under certain conditions.

Jan 1, 2014

By H. T. Chiwaye

Risk analysis is an important step in the design of rock slopes in open pit mining. Risk is defined as the product of the probability of slope failure and the consequences of the failure, and is generally evaluated in terms of safety and economic risk. Most of the risk analysis done at present is based on the use of limit equilibrium (LE) techniques in evaluating the probability of failure (POF) of the slopes. The approach typically makes use of full Monte Carlo simulations of the limit equilibrium models, with all uncertain variables randomly varied. The number of required simulations is generally over a thousand, at times as high as 20 000, in order to produce statistically valid results of the POF. Such an approach is clearly not practical when using numerical modelling programs dueto the high computational effort required. This paper explores the impact of using numerical modelling instead of the traditional LE techniques in evaluating the probability of slope failure. The difference in the overall assessed risk, in terms of economic impact, for the mining operation is then evaluated. With numerical models, approximate methods are used in the calculation of the probability of failure instead of full Monte Carlo simulations. This paper will use a method called the response surface methodology (RSM) for estimating the POF from numerical analyses. Simple slope models were used to verify the accuracy of the RSM method by comparing the results with those obtained from full Monte Carlo simulations. It is shown that there is good agreement between the POF values computed using full Monte Carlo simulation and those obtained using the RSM method. Finally, the use of numerical modelling in the assessment of risk is shown to bring a significant difference in the result compared with that from LE methods. One of the reasons for the difference is that LE models tend to underestimate the failure volumes and hence the consequences of slope failure.

Jan 1, 2010

By Willem J. Marais

The management of unpaved mine road networks on large surface mines rarely results in optimal road maintenance strategies and minimised total road-user costs. This is ascribed mostly to the complex and dynamic combination of variable road networks and loading and discharge points. In a dynamic mining environment - typically those mines in which production is managed by a centralised truck dispatch system ? there is no guarantee that a particular road maintenance intervention will contribute significantly to reducing total road-user costs or increasing productivity. Most large surface mines operating ultra-heavy mine trucks rely on an integrated on-board diagnostic data collation, communication and GPS-asset location system as a real-time fleet management tool. By extending this system to incorporate a multi-sensor analytical procedure in which specific truck vital signs are monitored and filtered, a road defect can be recognised and a trigger level set to relay the location of defects on the mine haul road to the centralised truck data management system. Previous work established the feasibility of the multi-sensor approach to road defect recognition on large mine haul trucks, and outlined the defect recognition, analytical and modelling issues and system limitations. This paper presents the development of the analytical procedure used as a basis for evaluating the truck on-board data to establish maintenance priorities amongst a network of mine roads. Following an introduction to the system architecture, the results of system field trials are analysed and the results discussed in the light of defect density and traffic volume as the primary variables in an approach to prioritising road maintenance. The paper concludes that by supplementing the existing mine communication and asset management systems, road maintenance can be managed on a near real-time basis and maintenance equipment dispatched to where most immediate benefit will realised from a maintenance intervention on the network, thereby generating the maximum improvement in service and reduction in cost per ton hauled.

Jan 1, 2008

By W. P. Nel

A fuel cell is an electrochemical engine that converts the chemical energy of a fuel, such as hydrogen, and an oxidant, such as oxygen, directly into electricity. The emerging fuel cell industry may represent a major opportunity for the global platinum mining industry. This is because low temperature fuel cell systems use platinum group metals as catalysts. Fuel cell vehicles may become the most important driver of future platinum demand within years of their commercialization. A great number of factors impact on and drive the diffusion of fuel cell vehicle innovation. Such drivers range from energy security to environmental concerns and the technological development of fuel cells and systems. Such factors and drivers of fuel cell vehicle diffusion are combined with the generic ?body of knowledge? on ?technology forecasting? and ?diffusion of innovation? to design a framework that provides a holistic approach to the analysis of this complex enterprise. An attempt is made in this paper to address the following questions: Which types of fuel cells require platinum group metals? Which types of fuel cells will achieve dominant design status? Will fuel cell vehicles diffuse successfully? How big will the impact of successful fuel cell vehicle diffusion be on future platinum demand? How well do fuel cell vehicles compete with incumbent technologies such as spark-ignited and compression-ignited internal combustion engine-driven vehicles? How soon will oil depletion start to drive the diffusion of fuel cell vehicles? How important is hydrogen as a fuel? What impact does the inadequate hydrogen fuelling infrastructure have on fuel cell vehicle diffusion? The paper contains some initial results of a research project that has the aim of producing a schedule of future platinum demand generated from fuel cell vehicles. Keywords: diffusion of fuel cell vehicles, technology forecasting, platinum demand forecasting.

Jan 1, 2004

By G. Wendel

Uranium is a naturally occurring radioactive material in the earth?s crust. Geological processes have resulted in concentration of uranium into ore mined for its gold content in South Africa. This uranium is present in the form of discrete particles of uranium minerals, generally oxides, which are normally insoluble. Chemical and physical processes during gold mining and extraction, particularly when carried out in conjunction with uranium extraction and sulphuric acid manufacture, act on the uranium minerals and the radioactive decay products of uranium. This may result insignificant accumulations of radioactive materials in certain parts of the process. There are a number of naturally occurring radioactive materials in the earth?s crust, such as Uranium-235, Thorium-232, andPotassium-40. This paper focuses on Uranium-238, together with its decay products, and how they affect the gold mines. Water plays a significant role in the redistribution of radionuclides, both as a physical transport medium, and as a solvent in which chemical reactions take place.

Jan 1, 1998

By J. de Villiers

Through the application of the Rietveld method, X-ray diffraction analysis has developed into a fully quantitative method for phase analysis. The Rietveld method itself has progressed from an unstable method that required constant operator intervention to a stable and robust method suited even for routine analysis. The method, however, requires a good initial calibration and periodic checks on its precision and accuracy. Several examples from minerals processing, pyrometallurgy, and materials science show the strengths and applicability of the method. The limitations and sources of error are also discussed.

Jan 1, 2007

By A. F. Lee

A pick-up apparatus capable of yielding quantitative results has been described. Studies of some collector-mineral systems have been presented to illustrate the versatility of the apparatus and prove the validity of results.

By I. L. Follington

This paper describes the research and development programme to develop a prototype underground auger mining system aimed at developing and demonstrating an underground auger mining system able to provide economic access to thinner (<1.8 m) coal reserves of South Africa. Data concerning the performance of modern coal augers under South African coal mining conditions were gained from a proven surface auger which operated across a range of coal types. These data were analysed and considered in conjunction with historical information regarding previous attempts at building underground augers dating back to the 1950s. Drawing on these data a prototype underground auger mining system, the BryDet BUA 600 underground coal recovery auger, was designed and manufactured by the BryDet Development Corporation in collaboration with Eskom and Cutting Edge Technology Pty Ltd with support from Anglo Coal and the Ingwe Coal Corporation Ltd. The prototype BryDet BUA 600 underground coal recovery auger commenced trials in March 2000 at the Matla Mine near Witbank in South Africa. The initial trials were undertaken in an open cut to facilitate the commissioning and training associated with a prototype mining machine. A total of 30 holes was augered in the box cut before the machine moved underground. The prototype BUA 600 first achieved the target penetration depth of 80 m in its third hole. The prototype BUA 600 is a new underground mining system which has passed early testing with ?flying colours? and could provide access to extensive underground coal reserves unmineable by conventional mining techniques both in South Africa and elsewhere around the world.

Jan 1, 2001

By O. Naiker

Xstrata has modified and improved on the solid state reduction of chromite (SRC) process that was pioneered by Showa Denko in Japan and previously used at Xstrata?s Lydenburg plant. The history of pre-reduction is a long one, with the SRC process being the first and only commercially successful one prior to Premus. Krupp developed the chromite direct reduction and the rotary hearth for the pre-reduction of chromite. However, these processes have not been successfully commercialised. The are a number of significant differences between Xstrata?s patented Premus and the original Consolidated Metallurgical Industries (CMI) process. These include, the use of lower cost anthracite fines as the reductant source together with the use of unactivated bentonite as the binding agent. In addition the use of oxygen as an energy source is used in Premus but not in the original CMI process. There was a fundamental change in the operational philosophy of the process in that while the original CMI process aimed to maximize metallization of the pellets, the Premus process seeks to maximize the energy output from the kiln while still achieving the required efficiencies and hence increasing furnace output. Premus is designed to reduce electrical energy consumption, provide high recoveries of metallic oxides, and utilizes low cost reductant and energy sources such as anthracite and oxygen respectively. Due to the fact that Premus is one of the most technologically advanced and competitive processes used today in the production of ferrochrome it was the process selected for Xstrata?s new ferrochrome facility, Project Lion, that is due to be commissioned in the third quarter of 2006 in the Steelpoort Valley in Mpumulanga, South Africa.

Jan 1, 2007