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By N. V. Moraka

In dealing with transformational aspects, the South African Constitution aspires for a balance between attempts to broadly represent the country’s demographics in the way in which organizations are structured and the need to maintain the necessary skills to ensure continual retention of skills for optimum and efficient organizational performance. Through the Mining Charter, government aimed to redress gender and racial imbalances in the mining industry as part of transforming the demographic representation of mining companies to include black people, women, and people living with disabilities in all job levels up to top management. While the Constitution calls for an appropriate balance between demographic representation and competency, this aspiration for mining poses challenges for companies due to the proficient and competent skills needed in this industry. To this end, the South African mining industry has been subjected to substantial criticism from government regarding the slow progress of transformation. The mining industry justifies its slow pace of transformation by pointing at inconsistent, varying legislation and definitions governing transformation, limited skills available from historically disadvantaged groups, and cautioning not to compromise the sustainability of mining companies by marginalizing white males and white youth with the objective of addressing racial imbalances. This lack of understanding between industry and the government has led to considerable confusion regarding the accountability of stakeholders in transforming the industry. This article presents the perspectives of ten mining executives on transformation in the South African mining industry. The theoretical description of transformation, as well as other mining stakeholders’ interpretations of transformation. is presented. Qualitative data from interviews with mining executives demonstrates their understanding of transformation through rich descriptions, interpretations, and implications in their contexts. The findings demonstrate that transformation in the mining industry is not simply about race and gender, but about cultural change, a change in mind-sets, embracing diversity, equalizing rights and opportunities, and attaining social justice. Moreover, transformation is clearly a gradual process. The article concludes with a recommendation for the definition of transformation to be corroborated with the views of mining executives and that of the Constitution of South Africa. This will create an overarching, simplified definition of transformation that can be accepted and interpreted by all stakeholders.

Jan 1, 2016

The Annual General Meeting of the South African Institute of Mining and Metallurgy was held in Kelvin House on Wednesday, 24th August, 1977. Dr M. D. G. Salamon (President) was in the chair and declared the meeting open at 16h00. Obituaries The President: It is my sad duty to announce the death of the following members of the Institute : C. G. Evans, J. P. Rees, Life Fellows ; S. R. Bryant, H. MacConachie, M. Mrost, and A. W. van Zyl, Fellows; L. T. Campbell-Pitt, F. W. Collins, A. J. Duncan, I. G. Evans, F. W. Kleinschmidt, P. L. Vaughan, R. W. Wallace, and H. Wason, Members. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I would ask you to rise and observe a few moments' silence. Minutes The President: May we confirm the minutes of the General Meeting held on 23rd March, 1977, as published in the June issue of the Journal? Agreed.

Jan 1, 1978

By M. Tangstad, D. Lu, G. Tranell, S. Gaal, J. Safarian

The kinetics of MnO reduction from high carbon ferromanganese slag was investigated using a sessile drop technique at 1600 ºC. The effects of reductant type, ambient atmosphere and slag composition on the MnO reduction were illuminated. Two different types of industrial reductants (ground to a particle size of 44 to 106micron and pressed to pellets) were used as substrates for small slag droplets of varying composition, which were reacted in a CO or Ar atmosphere with the reaction studied in-situ. The cross sections of the reacted slag-carbon samples were subsequently studied by EPMA to find the extent of MnO reduction as a function of reaction time. It was found that the rate of MnO reduction is affected by both the type of reductant, the ambient atmosphere and the presence of metallic components in the slag. Higher reduction rates were obtained for charcoal than for coke as reductant while a CO atmosphere unexpectedly yielded faster MnO reduction than an Ar atmosphere. It was also found that metal prills in the initial slag will increase the rate ofMnO reduction.

Jan 1, 2007

By Hao Li, Allan Moss, Richard K. Brummer

At the Palabora Mine, the transition to caving 400 m below the bottom of the 800 m deep pit resulted in a slope failure of the North wall that began in 2003, and is still mobile. This failure can be explained by the daylighting into the cave zone of a prominent joint set. The failure was modelled by the 3-dimensional code 3DEC, which is capable of modelling the nonlinear behaviour of discontinuum materials with large displacement.

Jan 1, 2006

By E. R. Davis, R. J. Knott

The paper discusses some of the tools of management in the field of project control, especially in engineering. Project control includes planning and cost engineering, and involves various phases: the conceptual Design and Planning Phase, the Definitive Design and Capital Budgeting Phase, and the Implementation Phase. Each of these phases is discussed in in, together with the use that can be made of data banks, progress reports, and computer systems.

Jan 1, 1982

By N. Sano

The chromium oxide in stainless steel slags usually exists as Cr2O3. However, there is a possibility that it is oxidized to hazardous CrO3 after disposal or during use. Therefore, some technical developments to reduce chromium oxide by using a smelting reduction technique have been reported recently. This paper describes the fundamentals of the technique which have been applied to ferrochromium production and reviews the recent results in literature.

Jan 1, 2004

The distribution of chrome spinels in a magnetically fractionated ilmenite concentrate sourced from the Murray Basin was characterized by XRF assaying, quantitative electron microprobeanalysis, grain mapping, automated mineral phase clustering, and modal analysis. At least 14 distinct chrome spinel types were present in the concentrate. There is considerable variation in the amount of each chrome spinel type present, although a high-Mg, high-Al phase makes up close to 45 per cent of the total spinel population. Magnetic fractionation results showed significant variation in the composition and relative abundance of spinels reporting to each fraction. Low magnetic field strength fractions (ie. high susceptibility grains) were dominated by chrome spinels that are mid-range in Al and Cr. These spinels have the highest magnetite, ulvospinel and Fe(Al,Cr)2O4components. In comparison, the high field strength fractions (i.e. low susceptibility grains) have the majority of the grains with high-Al contents indicating a higher proportion of Mg(Al,Cr)2O4component. Spinels high in a (Al,Cr)2.67O4non-stoichiometriccomponent are absent at low field strengths but tend to be concentrated in the high field strength, non-magnetic fractions. Intermediate field strength fractions tend to exhibit a broad spread in spinel compositional types. A mild roast treatment of the sample had no clear effect on the distribution of chrome spinels between different magnetic fractions, but it did cause a change in the magnetic properties of the accompanying ilmenite grains. The effect of more extreme roasting conditions on the magnetic properties of the chrome spinels is to be determined.

Jan 1, 2003

By J. M. Richards

For most of the 20th century optical petrography has been the primary petrological and mineralogical tool used to characterize coal. The development of quantitative SEM-based techniques, e.g. QEMSCAN®, for coal began only about a decade ago. The application of these techniques for coal lagged behind other commodities, but they are currently being developed with the aim to provide ?one complete analysis? for coal. Quantitative SEM-based techniques are supplemented by quantitative X-ray diffraction (XRD). Recent indications are that these more modern techniques cannot replace the ?standard? petrographic and chemical evaluations, but rather complement them where and when required. The great advantage of quantitative SEM-based techniques is that they are very rapid, with the result that large volumes of samples can be processed on a routine basis. This is ideal for coal type identification, since the results can be used in the creation of ?intelligent? composites. This can lead to the more speedy evaluation of coal deposits by reducing the number of samples on which detailed metallurgical and characterization test work is required, without an increase in the overall statistical error of the resource model. Coal petrography, however, remains important for the prediction of the coking characteristics of certain coals and coal products. As a consequence it is therefore important that any coal laboratory be able to produce data with confidence. This requires strict quality control and assurance protocols that adhere to international standards. Keywords coal petrography, coking strength, scanning electron microscopy, QEMSCAN®.

Nov 1, 2013

By H. Lagendijk, I. J. Reinecke

Mintek was contracted by Oriel Resources plc in 2004 to conduct a preliminary assessment study on smelting ferronickel from the large but relatively low grade Shevchenko nickel ore deposit in Kazakhstan. A detailed feasibility study (?DFS?) was awarded to Bateman BV following promising results from the preliminary assessment study (?PAS?) and small-scale pilot plant test work. As part of the DFS, a total of 450metric tons of ore was collected from three different locations in the deposit and shipped to Mintek. After sampling, the bulk sample was prepared for smelting. This comprised crushing, screening and calcining with each step done separately for the three different lots. The chemical composition of the ore from the deposit is relatively high in silica and therefore falls out of the MgO to SiO2 range that is normally processed by pyrometallurgical means to produce ferronickel. The main objective of the testwork was to demonstrate that a method could be found and successfully applied to smelt these siliceous ores and produce an acceptable nickel-containing alloy. A 2-m ID DC arc furnace was installed with a twin-cathode (electrode) configuration to replicate the proposed commercial-scale furnace and also incorporated an advanced design of water-cooled copper panels in the lower furnace sidewalls to withstand the aggressive nature of the high SiO2-containing slags. The reductant used was a high-volatile coal from Karaganda in Kazakhstan. The reductant addition was adjusted to achieve a 90% recovery of nickel. In the assessment of the process metallurgy, some deviation from equilibrium conditions was observed. This deviation is ascribed to the intermittent existence of a smelting bath partially covered with feed during the testwork. Optimization of smelting conditions should result in the metallurgy (slag metal equilibrium) being closer to the theoretical predictions and make the production of a 20% nickel alloy possible at 90% nickel recovery. The solution for the successful processing of these siliceous ores was found in the attainment of the necessary operational stability through the control of arc length, operating temperature, open-bath smelting conditions and flux additions of up to 10% dolime for the most siliceous of the three ore types. The test work carried out by Mintek provided the basis for the process flow sheet and engineering design of the DC arc smelting furnaces for the Shevchenko Nickel project.

Jan 1, 2007

By H. Krogerus, P. Niemelä, P. Oikarinen

High carbon ferrochromium is produced by carbon reduction. No replacement for carbon as reductant has yet been developed. The reduction creates a considerable amount of CO-gas. In open and semi-closed furnaces the gas is burned when leaving the burden. In closed furnaces the formed gas is sucked out by a fan, washed and utilised as fuel. The formation of carbon monoxide is presented briefly starting from thermodynamic considerations up to solid and liquid state reduction. The volume, composition and energy content of the furnace gas are discussed, focusing on the raw materials and pre-treatment processes of the furnace feed as well as on the process equipment and control. Outokumpu has been using closed and sealed furnaces and utilising the CO-gas in its Tornio Ferrochrome Works since 1968. Today in Tornio with an annual ferrochromium production of 260 000 t CO-gas production is 186 million m3, representing 68 MWh an hour. At the same time the furnace power input is 95MW. About 98 % of the CO-gas is utilised, whereof 30% in the ferrochrome production itself. This paper focuses on the characteristics and utilisation of CO-gas. CO-gas is secondary energy, which on one hand saves primary electric and fossil fuel energy in ferrochromium production and, on the other, replaces other fossil fuels at the adjacent steel works. The characteristics of the fuel, requirements for utilisation as well as health and safety aspects are discussed. Utilisation of the gas has a high impact on the total dust and gaseous emissions and on the energy optimisation at the ferrochromium and steel works.

Jan 1, 2004

By A. Varadarajan, M. Hashemi, K. G. Sharma

Quartz mica schist collected from Nathpa-Jhakri Hydropower Project, Himachal Pradesh, North India is tested under triaxial loading using a servo-controlled loading system. Complete stress-strain-volume change behaviour including post peak softening behaviour of the samples, are presented. Strength and deformation parameters are given. Quarz mica schist, der von Nathpa Jhakri Hydropower Projekt, Himachal Pradesh gesammelt wird, wird Nördlich Indien unter triaxial geprüft, der von Gebrauch eines servo kontrollierten Ladesystems beladung. Vollständiges Spannung-Spannung-Band Änderung Verhalten Postens Spitze Erweichung Verhaltens der Proben, wird überreicht. Kraft und Verformung Parameter werden gegeben. Mica à quartz schist recueilli du Projet de Hydropower de Nathpa Jhakri, Himachal Pradesh, l'Inde du nord est essayé sous l'utilisation de chargement de triaxial un système chargeant servo réglé. La tension complète-la tension-comportement de changement de volume y compris la poste sommet amollir le comportement des échantillons, sont présenté. Les paramètres de force et déformation sont donnés.

Jan 1, 2003

By G. van Aswegen

Large structures in mines (faults, dykes, pillars, abutments) fail when the load exceeds the strength. If the loading system stiffness (LSS, also referred to as the ‘local mine stiffness’) is lower than the stiffness of the structure the failure will be unstable. The greater the difference between these stiffnesses, the greater the energy release during unstable failure. A method has been formulated by which the LSS is established through cost-effective numerical modelling while insight into the structure stiffness (source stiffness - SS) is provided by apparent stiffness, a parameter based on the empirical relation between seismic moment and radiated seismic energy of small seismic events from the area/volume of interest. By plotting LSS vs SS a ‘stiffness diagram’ is constructed that is useful for seismic hazard ranking of different structures. A comparative back-analysis of the Dagbreek fault in Welkom, South Africa, (source of the 1990 Matjhabeng earthquake) and two other nearby faults confirm the applicability of the method. An extension of the method, where ‘hazard magnitude’ is used as a measure of the LSS, allows a ‘stiffness diagram’ to be constructed using seismic data only. Les larges structures dans les exploitations minières (failles, dikes, piliers, culées) s’écroulent lorsque la charge dépasse la résistance. Si la raideur du système de chargement (LSS, aussi appelé la « raideur de la mine locale ») est plus basse que la raideur de la structure, l’éboulement sera instable. Plus la différence est grande entre ces deux raideurs, plus l’énergie dégagée pendant l’éboulement instable est grande. Une méthode a été formulée selon laquelle le LSS est établi par modélisation numérique rentable, tandis que la raideur de la structure (SS – raideur de la source) est établie par la raideur apparente, un paramètre basé sur la relation empirique entre le moment sismique et l’énergie sismique radiée de petits moments sismiques dans l’aire/volume en question. On trace le « diagramme de raideur » en relevant les deux mesures (LSS et SS), ce qui est utile pour classer les risques sismiques de structures différentes. On vérifie l’applicabilité de la méthode en comparant la faille de Welkom, Afrique du Sud (foyer du séisme de Matjhabeng en 1990) avec deux autres failles proches. Une extension de cette méthode, dans laquelle on utilise la « magnitude du risque » comme mesure du LSS, permet de construire le « diagramme de raideur » avec des données sismiques seulement. Große Strukturen in den Gruben (Verwerfungen, Dämme, Pfeiler, Auflager) scheitern, wenn die Last die Stärke übersteigt. Wenn die Steifheit des Ladesystems (LSS, auch bezeichnet als `lokale Grubensteifheit’) niedriger ist als die Steifheit der Struktur wird der Bruch instabil. Je grösser der Unterschied zwischen diesen Steifheiten, desto grösser die Energiefreigabe während des instabilen Bruches. Es wurde eine Methode formuliert, durch die das LSS durch eine kosteneffektive numerisches Modell erstellt wird, während ein Einblick von der offensichtlichen Steifheit in die Struktursteifheit (Quellensteifheit - SS) gegeben ist, ein Parameter der auf der emipirischen Relation zwischen seismischem Moment und ausgestrahlter seismischer Energie von kleinen seismischen Ereignissen vom Interessens-/Volumenbereich basiert. Durch das Kartograpahieren der LSS in Bezug auf die SS wird ein `Steifheitsdiagramm ' konstruiert, welches für seismische Gefahrklassifizierung der unterschiedlichen Strukturen nützlich ist. Eine vergleichende Postanalyse der Dagbreek Verwerfung in Welkom, Südafrika, (Zentrum des Matjhabeng Erdbebens 1990) und in zwei anderen nahe gelegenen Verwerfungen bestätigen die Anwendbarkeit der Methode. Eine Verlängerung der Methode, in der die `Gefahrengröße' als Maß für das LSS verwendet wird, gestattet, daß ein `Steifheitsdiagramm' konstruiert wird, welches nur seismische Daten verwendet.

Jan 1, 2003

By D Reddy

Rosh Pinah Zinc Corporation is a zinc-lead mine located in southern of Namibia. It is currently considering the development of a low grade ore body containing about 2.8% zinc. This ore can be utilised by the concentrator if it could be upgraded prior to the ball mill. Preliminary work indicated that the ore may be upgraded in a pre-beneficiating stage by using dense medium separation, X-ray sorting or a combination thereof to a feed grade of minimum 9% zinc. This paper describes the process followed in evaluating the technologies for pre-beneficiation. The results from test work indicated that the low grade ore is amenable to pre-beneficiation by both dense medium separation and X-ray sorting. A comparison between the two technologies showed that dense medium separation marginally outperformed X-ray sorting on grade and recovery. The results for the X-ray sorting were achieved by tuning the calibration curve specifically for the samples tested.

Jan 1, 2008

By Swapan Ghosh, Amitava Sengupta, Proloy Das

Ferro-alloys are very important ingredients used for making of quality steel with desired composition. In view of high demand in various types of ferro-alloys, it has become necessary to produce the same efficiently, safely and cost-effectively with consistent quality maintaining the anti-pollution norms. To achieve this goal, it is necessary to adopt latest process/equipment with the state-of-the-art instrumentation and automation system. A Programmable Logic Controller (PLC) based automation system with suitable Human Machine Interface(HMI) terminals along with intelligent field mounted sensing/control devices allows to monitor and control the complete plant effectively with optimum deployment of man-power. In association with this, use of process optimization controllers enables to achieve specialised functionalities of the submerged arc furnaces like material management, lining management, electrode management, power management, overall production management etc.

Jan 1, 2007

By M. Lu, E. Broch

Abstract: The formation and mechanism of rock cavern roof arches are studied and effects of rockbolts reinforcement are evaluated. It is concluded that a self-supported roof arch may be formed by the excavation. To stabilize such a roof arch, fully grouted rockbolts are effective. Tensioned cable anchors may have a negative influence on the arch stability. Zusammenfassung: Die Formation und der Mechanismus von Deckenbögen in Bergkavernen wird studiert und der Effekt von Verstärkung mit Bergbolzen wird bewertet. Es wird festgestellt, dass die Exkavation einen selbst-stützenden / freitragenden Deckenbogen formen kann. Eingegossene Bergbolzen sind effektiv um einen solchen Deckenbogen zu stabilisieren. Spannkabel können unter Umständen eine negative Einwirkung auf die Stabilität des Bogens haben. Résumé: Le mécanisme et la formation de voûtes dans les cavernes rocheures sont étudiés et l'effet du renforcement par boulonnage est évalué. Nous arrivons à la conclusion qu'une voûte autosupportêe peut être formée par excavation. Des boulons entièrement scellés par coulis de bêton s'avèrent efficaces pour stabiliser de telles voûtes. Les tirants d'ancrage peuvent quant à eux nuire à la stabilité de la voûte.

Jan 1, 2003

Due to the reduction in frictional resistance, the characteristics of joint infill have a major role to play on rock mass instability. This paper elucidates the laboratory behaviour of graphite infilled joints based on a large-scale shear apparatus under constant normal stiffness (CNS). Discontinuities in a graphite mine have been simulated using high strength gypsum plaster, with the joints infilled with compressed graphite layers. The Fourier series was employed to characterize the joint surface, and the method of using the Fourier coefficients for the prediction of dilation and normal stress with displacement is explained. Die Charateristik von Verbindungsfüllungen hat einen wichtigen Einfluss auf Felsmassenstabilität aufgrund der Verringerung des Reibwiderstandes. Diese Veröffentlichung untersucht das Verhalten von Graphit gefüllten Verbindungen im Labormaßstab mit einer Methode die auf einem gross-umfang Apparateprinzip unter konstanter Normal-Steifheit beruht. Unregelmässigkeiten in einer Graphit Mine wurden mit Gypsum Gips von hoher Festigkeit simuliert, die Verbindungen wurden mit kompressierten Graphitschichten gefüllt. Fourier Reihen wurden angewandt um die Verbindungs Fläche zu Characterisieren. Die Methode die verwendet wurde um die Ausdehnung und Normalkraft mit der Verschiebung mit Hilfe von Fourierkoeffizienten zu bestimmen wird beschrieben. Due à diminution des résistances par frottements, les caractéristiques des joints de remplissage joue un rôle majeur sur les instabilités de la roche. Cet article étudie le comportement en laboratoire des joints de remplissage en graphite à partir d’un dispositif de friction à grande échelle sous rigidité normale constante. Les discontinuités dans une mine de graphite ont été simulées grâce à un plâtre à haute teneur en gypse, dont les joints ont été remplis de couches de graphite compressées. La caractérisation de la surface des joints a été réalisée avec les séries de Fourier. La méthode utilisant le coefficient de Fourrier pour la prédiction de la dilatation et de la compression en fonction du déplacement est également expliquée.

Jan 1, 2003

By V. Labiouse, P. K. Kaiser, F. Descoeudres, F. Rojat

In this paper some failure phenomena observed in the crossing of brittle rock formations at the Lötschberg base tunnel are presented. A brittle failure criteria, recently developed by Canadian researchers, is applied through finite element calculations together with a semi-empirical failure criterion, to explain these behaviours. Good agreement is found between predicted and observed failures at the tunnel walls. This study also shows some of the limitations of this approach. Dans cet article sont présentés certains phénomènes de rupture observés durant la traversée de zones de roches fragiles lors de l’excavation du tunnel du Lötschberg. Un critère de rupture développé récemment par la recherche canadienne est utilisé à travers des calculs par éléments finis. En parallèle, les résultats sont comparés avec ceux d’un critère semi-empirique. Au niveau des parements, l’ampleur des ruptures observées est assez proche des résultats de calcul. Cette étude a également permis de mettre en avant certaines limites de l’approche choisie. In diesem Artikel werden verschiedene Brucharten dargestellt, die bei der Durchfahrung von sprödem Gestein im Rahmen des Ausbaus des Lötschberg-Basistunnels beobachtet wurden. Zur Erklärung des vorliegenden Verhaltens wurden die erst kürzlich in Kanada entwickelten Theorien zur Beschreibung von Sprödbrüchen herangezogen und bei der Berechnung mittels der Finite-Elemente-Methode und eines semi-empirischen Kriteriums angewendet. Die so vorhergesagten Versagenszonen an den Tunnelwänden stimmen mit den Beobachtungen gut überein. Die Studie hat auch dazu beigetragen, die bei der Anwendung des Lösungsansatzes angetroffenen Schwierigkeiten aufzuzeigen.

Jan 1, 2003

By J. P. W. Bennie, A. de Jong, G. M. Denton

Mintek together with Middelburg Steel & Alloys, developed the DC arc furnace process for the production of ferroalloys with the expressed objective of smelting ore fines (<1mm) without the need for agglomeration. In the case of ferrochrome production, the DC arc furnace, being a semi-open bath operation, loses radiant energy directly from the bath to the furnace roof and sidewalls above the melt. This energy loss is reflected in a higher electrical energy usage per ton of alloy than for a submerged-arc operation smelting lumpy ores or sintered pellets. The difference increases still further when pre-heated sintered pellet feed is used in a submerged-arc operation. This shortcoming of the DC arc furnace can however be overcome by preheating the feed to the furnace in a fluidized bed or flash reactor fuelled by cold furnace off-gas. In addition to fluidization and preheating testwork, various preheating flowsheets with associated mass and energy balances have been developed and compared from a techno-economic viewpoint. The three major advantages identified were: a) fluidized beds can preheat ores and fluxes up to 950°C without sticking and defluidizing, b) the open bath DC arc furnace does not require expensive coke or char to maintain the burden porosity and, c) the capital cost associated with the milling, pelletising and sintering plant falls away since ore fines are used directly.

Jan 1, 2004

By Mike McWha

Drivers to increasing RM use ?Compliance issues ?Section 12 JSE Listing Rules ?Canadian NI 43-101 ?Sarbanes Oxley ?Shortage of African ore reference materials ?Poor perceptions about quality of some local RM?s

Jan 1, 2005

By Simon St J Tose

The objective of this paper and presentation is to review the different criteria and methodology used by AEL and other organisations to create a pre-split design which delivers a stable highwall for the life of that part of the mining operation. It will look at the need to adapt and change the way, size and direction of the production blasts as the mining phase approaches the highwall position for which a pre-split has been created. Key Words: Pre-split: Design; Highwall; Perimeter

Jan 1, 2006