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By M. Dhainaut

This paper presents computations of the electric field inside a furnace. We first look at the effect of contact between two coke particles from an electrical point of view. We give values for the amount of contact resistance in the total resistance of the system formed by the two coke particles. We show that the effect of contact resistance decreases rapidly with increasing contact area. We then look at the complete electric field inside a full scale furnace. The aim is to evaluate the amount of current that short-cuts the metal bath for different vertical positions of the electrodes. We show that electrodes high above the metal bath are undesirable since they offer a larger surface of conductive charge materials where current can flow through. On the other hand, deeper electrodes force the current to go the whole way down to the metal bath. Ohmic heating along this path ensures a high temperature of coke and slag that are beneficial for metal recovery.

Jan 1, 2004

By A. Fredriksson, R. Christiansson, I. Staub

A theoretical model based on DFN models and 2D DEM numerical modelling has been developed for evaluating the rock mass mechanical properties. The description of the methodology is non-site related and can be applied in any site for this type of characterisation. The methodology was developed in the frame of the Site Investigation programmes for a Deep Repository for spent fuel in Sweden, and validated on sets of data coming from the Äspö Hard Rock Laboratory. Un modèle théorique base sur des modèles probabilistiques de réseaux de fractures et sur un modèle numérique DEM 2D a été développé dans le but de déterminer les propriétés mécaniques de la masse rocheuse. La méthodologie développée peut être appliquée à tout type de site pour ce genre de caractérisation. Le modèle a été élaboré dans le cadre des programmes de recherche d’un site d’enfouissement des déchets nucléaires en Suède, et validé par une application au laboratoire de recherche souterrain à Äspö. Ausgehend von DFN-Modellen und 2D DEM numerischen Modellierungen wurde ein theoretisches Modell für die Auswertung von mechanischen Eigenschaften von Fels entwickelt. Die Methodikbeschreibung ist nicht standortspecifisch sondern kan überall für diesen Typ von Standordkarakteriserung angewendet werden. Die Methodik wurde in Schweden im Rahmen der Standortuntersuchungsprogramme für die Endlagerung von verbrauchten Brennelementen entwickelt und ist mit Hilfe von Daten des Äspö Hard Rock Laboratory validiert worden

Jan 1, 2003

By J. A. Bakken, M. Tangstad, P. A. Eidem

In the submerged arc production of ferromanganese, sillicomanganese and ferrochromium, the coke bed characteristics play an important role. The basic mechanisms of electric current conduction in the coke be dare not yet fully understood, but important parameters are the material resistivity of coke and the contact resistance between the coke particles. Preliminary tests indicate that the contact resistance is of great importance to the bulk resistance of the coke bed. An apparatus measuring the material resistivity and contact resistance of carbon materials has been developed. Both graphite and industrial coke have been tested. The material resistivity tests were performed on single particles to ensure that the effects of pores and cracks were included and the contact resistances were excluded. Two geometries were tested to obtain the contribution of the contact resistance to the total resistance of two connecting particles. The tests were performed in an inert atmosphere at temperatures and current levels found in industrial submerged arc furnaces. The results show that the method has a satisfactory reproducibility. It was found that the contact resistance is about 10 times higher than the resistance of the material when two particles are in perfect contact and that the resistivity of SSAB coke is more than 10 times higher than that of the graphite at room temperature, but with increasing temperature the difference decreases. For SSAB coke the general trend is that both the resistivity and the contact resistance decrease with increasing temperature.

Jan 1, 2007

The captions to Figs. 1 and 2 of the paper by B. J. Parry entitled 'High-strength cold-rolled steels' should read as follows:

Jan 1, 1984

By P. J. Brereton-Stiles, M. S. Rennie, N. Singh

Ferroalloy producers are large-scale users of electrical energy, which in many countries is in short supply and increasingly expensive. Preheating and/or pre-reduction using natural gas, recycled furnace gas or coal fines have lowered the specific use of electricity, but the high energy concentration necessary for most reduction processes can be achieved only by the use of high electric currents. Most countries have insufficient electricity to supply the demands of industry and the domestic consumer, particularly during certain periods of the day and certain times of the year. The generation and distribution of electricity is a large-scale expensive business, which is financed and managed directly or indirectly by government bodies in most countries. Both economic and political imperatives determine how much electrical energy is made available to whom and at what price. In South Africa demand is set to outstrip supply within the next few years, and the local supplier Eskom has moved from a traditional demand tariff pricing structure to a time-of-use tariff pricing so as to limit peak demand usage. This will mean a substantial increase in electricity cost to those users unable or unwilling to reduce consumption during peak periods. The optimal use of the available electrical energy depends both on the process, the furnace size, the configuration and infrastructure of each plant and its cost structure. As the cost and availability of electricity is set to change dynamically, the management of the situation becomes a real time control and optimisation problem. This paper discusses some the process and operational constraints associated with low- or no-load conditions and how to manage the situation. Electrode management will be one of the key issues.

Jan 1, 2004

A Life Cycle Assessment (LCA) of stainless steel production, including that of the nickel, ferronickel, ferrochromium and iron feedstocks was carried out using inventory data derived from the literature. The environmental impact categories considered in the study were Global Warming Potential (GWP), Acidification Potential (AP) and total (or full cycle) energy consumption. The effects of different sources of electricity (black coal, natural gas and hydroelectricity) were also examined in the study. The results of the LCA showed that when ferronickel is used as the nickel source, the total energy consumption for stainless steel production is approximately 50% higher than when nickel metal is used as the nickel source (75 MJ/kg cf. 49 MJ/kg). This result comes about largely because the Fe units in ferronickel have a much higher energy intensity than do the Fe units in pig iron, and the greater the use of the former at the expense of the latter, the greater is the total energy consumption. The results also showed that the production of ferronickel made by far the largest contribution (59%) to the total energy consumption for stainless steel production when this feedstock is used as the nickel source, but when nickel metal is used as the nickel source the contributions of the various stages are more evenly distributed. It was also observed that the electricity consumption of the electric furnaces used in the production of ferronickel, ferrochromium and stainless steel contributed approximately 50% to the total energy consumed in stainless steel production. Given the relatively low efficiencies associated with electrical power generation, significant reductions in the total energy of stainless steel production could be anticipated if more direct use of thermal energy was made in the ferronickel, ferrochromium and/or stainless steel smelting stages, for example by utilising bath smelting processes.

Jan 1, 2004

By V. I. Zhuchkov, L. A. Smirnov, E. I. Arzamastsev, A. A. Babenko

A brief analysis is given for state-of-the-art of manganese and chromium ferroalloy production in Russia and their consumption by metallurgy plants. The main causes of low output of manganese and chromium ferroalloys, and ways to resolve the issue of ferroalloy production development are considered.

Jan 1, 2004

By C. Lumley

The management of the Anglo Platinum (AP) mining technical systems (MTS) embarked upon a process of defining the strategy for the MTS department. The newly established department forms part of the greater Group Information Technology (IT). The strategic process took place within an environment that had witnessed a dramatic proliferation of IT implementations across the group within the last three years. The IT department has been structured in terms of the classical plan, build and run functions with the applications and integration streams running perpendicular across these three functions. The application stream is divided into commercial and mining technical systems with business systems integration the third stream. The mining technical systems department supports mine management to effectively gather, analyse and disseminate data relating to the ore reserve by integrating a number of strategically selected IT applications to ensure that the safety, legal and operational requirements are met. This service to business is rendered by management of a strategic outsource partner via tightly controlled service level agreements (SLAs). The framework used for creating a mining technical systems department that is empowered to add value to business was formulated using the AP value chain as both the starting point and guiding process to ensure alignment to the greater internal strategy of the business. Keywords: Platinum, Mine planning, Mining technical systems, Value chain.

Jan 1, 2003

By C. C. Oosthuizen

Paper written on project work carried out in partial fulfilment of Technikon Practical Training Frank shaft is mining both Merensky reef and UG2 reef. The Merensky orebody is almost depleted and this was the reason for starting to mine the UG2 ore reserves. It was decided to mine the UG2 orebody with trackless equipment using a bord and pillar mining method. Frank shaft has been mining the UG2 orebody for nearly 5 years. The T-cut mining method was introduced to see if it could improve the grade of the run of mine (ROM) as well the extraction percentage.

Jan 1, 2005

By Phillip J. Mackey, Rodney T. Jones

"Copper and copper alloys remain key materials for society today, with important uses found in the electrical, transportation, and construction industries. Copper demand is rising, with projections indicating that by 2025 global refined copper demand will increase to 29.5 million tons, up from the 22.4 million tons anticipated for 2015. This will require the opening up of dozens of new mines and numerous new smelters over this time period. Fortunately, Africa has significant reserves of copper, and African copper can once again play a key role in contributing to meeting the rising global demand for copper. This paper provides a brief overview of the current copper smelting operations in Southern Africa. INTRODUCTION Copper and copper alloys are essential materials for today’s modern world. The familiar green copper patina colour seen on buildings and other structures sometimes belies its true “green” characteristic – copper is essential for key emerging technologies such as wind turbines, tidal generating systems, solar energy systems, electric cars and the like. Consequently, it is believed that there will be continued growth in copper demand in the years ahead. Projections indicate that by 2025, as an example, global refined copper demand will increase to 29.5 million metric tons, up from the 22.4 million ton level anticipated for 2015. This will require dozens of new mines, and of the order of the equivalent of 10 to 12 new 0.5 million tons of copper/year-sized copper smelters (after factoring projected copper produced by electrowinning (EW))—overall, a huge undertaking. Fortunately, Africa has significant reserves of copper, and African copper can once again play a key role in supplying this rising global demand for copper. Africa’s share of global mined copper production was about 10% in 2014; however this will increase significantly in future if announced new projects eventuate. Southern Africa has an important role to play in this process. The present paper provides a brief overview of copper smelting in Southern 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

1. Book reviews Geophysical and geochemical techniques for exploration of hydrocarbons and minerals, edited by M. Sittig. (Reviewer: J. Keenan) Separation procedures in inorganic analysis. A practical handbook, by Roland S. Young. Charles Griffin, 1980. £23.00. (Reviewer: R. Murray-Smith) 2. Historical reprints Theinin~rs dictionary, by William Hooson. £14. Discovery of subterraneal treasure, by Gabriel Plattes. £12. Fodinae Regales (The Mines Royal), by Sir John Pettus. 3. De Beers' booklets Amborite - a remarkable new cutting material, by De Beers Industrial Diamond Division (P.O. Box 916, Johannesburg 2000). Booklet, 14 pp., free of charge. Natural and synthetic micron powders, by De Becrs Industrial Diamond Division (P.O. Box 916, Johannesburg 2000). Leaflet, 5 pp., free of charge. 4. New books Nickel in the environment, edited by J. O. Nriagu. New York, Wiley, 1980.928 pp. $65. Underwater minerals, by D. S. Cronan. London, Academic Press, 1980. 364 pp. $57.50. Data conversion integrated circuits, edited by D. Dooley. New York, Wiley, 1980.298 pp. $26.95 (cloth), $17.50 (paper). 5. NIM reports Report 2057 A mineralogical study of the Rooibokkop- Boschhoek copper deposit in the Marble Hall area. Report 2069 A utomatic setting of the distance between sample and detector in gamma-ray spectroscopy. Report 2070 The prereduction of chromites from the UG-2 Reef. Report 2075 The optimization of some of the conditions for analysis by spark-source mass spectrometry. Report 2082 A survey of the literature on gravity separation.

Jan 1, 1981

By K. Ford, R. Urquhart, D. Hobbs

CIS countries are home to some of the world's largest producers of chrome, manganese and silicon ferro alloys and leading suppliers to world export markets. The region's ferro alloys production is rising faster than demand from its domestic steel industry - unit alloy consumption in domestic steelmaking is in fact falling as process efficiencies improve - and there is significant spare capacity available to increase production. CIS producers enjoy certain strategic advantages in the production of ferro alloys - for example, captive ore sup-plies, low power and labour costs - but must also meet certain challenges - such as lower labour productivity and greater distance to market than some of their competitors. CIS producers are ambitious but new investment is needed to upgrade some aging plants and overhaul outdated process technologies if they are to be more competitive with the world's leading producers and address the environmental issues that are now moving up the agenda. This paper describes the structure of the region's ferro alloys industry and discusses its advantages and disadvantages by alloy and by country. It considers how the ongoing process of restructuring and new investment in the industry might move forwards, based on its strengths and weaknesses, technical and environmental factors and the strategies of the main players. It asks how the industry might maximise its substantial potential - in particular, for the production of chrome and manganese ferro alloys - and examines the implications this holds for all global ferro alloys players.

Jan 1, 2007

The Skorpion process comprises three processing steps, atmospheric leaching in sulphuric acid, zinc solvent extraction and electrowinning to produce special high grade zinc. The major mode of impurity transfer was attributed to crud runs in the solvent extraction circuit. Crud may be described as a heterogeneous, partly inorganic, partly organic mass of material which accumulates predominantly at the interface between organic and aqueous solutions. The paper describes the route causes of the crud formation in the solvent extraction circuit and optimisation strategies which are being followed to prevent impurity excursions in electrowinning. Keywords: zinc oxide, solvent extraction, crud formation, colloidal silica

Jan 1, 2007

By F. B. Samani, B. Stabel

The 1,000 MW Hydro Power Station Masjed-e-Soleiman (formerly called Godar-e-Landar) in Iran is under construction since 1992. The rock engineering aspects of the major underground structure, i.e. the powerhouse cavern shall be reported on in detail. The geotechnical investigations are described and results given. The results of several geotechnical analyses are presented. The designed and executed rock support is given. A description of the monitoring systems and typical measurement results obtained during and after excavation are presented. The lessons learnt during construction of the Stage-I powerhouse cavern were applied on the extension of the powerhouse cavern, which is to house an additional 1000 MW. Details regarding the unexpected behaviour of the Mudstones are given. Die 1000 MW Wasserkraftanlage Masjed-e-Soleiman (vormals Godar-e-Landar genannt) befindet sich seit 1992 in Bau. Dieser Artikel berichtet im Detail über die felsbaulichen Aspekte der Untertagebauwerke, insb. der Maschinenkaverne. Die geotechnischen Untersuchungen werden beschrieben und deren Ergebnisse wie die Ergebnisse verschiedener Berechnungen werden präsentiert. Die geplante und die ausgeführte Felssicherung wird angegeben. Die eingebauten Überwachungseinrichtungen werden beschrieben und typische Ergebnisse während des Aushubs und danach werden dargestellt. Die Erfahrungen beim Aushub der Kaverne der Stufe I wurden beim Entwurf der Kaverne der Erweiterungsstufe II, die weitere 1000 MW beherbergen wird, berücksichtigt. Details zum unerwarteten Verhalten des Schluff-/Tonsteins werden angegeben. La centrale hydroélectrique de Masjed-e-Soleiman (dénommée anciennement Godar-e-Landar), d’une puissance de 1.000 MW, est en construction depuis 1992. Un rapport détaillé sera présenté sur les aspects relatifs à la construction en enrochements de l’aménagement souterrain principal, à savoir la caverne abritant la salle des machines. Une description des investigations géotechniques réalisées y est fournie ainsi que les résultats correspondants. En outre sont présentés les résultats de plusieurs analyses géotechniques. L’ancrage dans la roche tel que projeté et réalisé est présenté. Une description des systèmes de contrôle ainsi que les résultats de mesures typiques obtenus au cours des travaux d’excavation sont donnés. Les leçons tirées lors de la construction de la Phase 1 de la caverne de la salle des machines furent appliquées à l’extension de la caverne de la salle des machines, qui doit abriter une unité supplémentaire d’une puissance de 1.000 MW. Par ailleurs, des détails sont donnés sur le comportement inattendu des argilites.

Jan 1, 2003

By M. Reuter, C. Schuffeneger, T. Seppälä, L. Holappa

Reaction kinetics of solid-state reduction of chromite pellets (laboratory made and industrial) and lumpy ore was investigated by the thermogravimetric analysis (TGA) technique. Carbon monoxide was used as the reducing agent, with the presence of graphite in proximity to chromite. The experiments were carried out at both rising temperature and constant temperature in the range of 1450 - 1550°C. Scanning electron microscopy was employed to observe and analyse the structure and composition changes of the chromite samples. For the lab-made chromite pellets, the effects of particle size and bentonite addition on the reduction behaviour were studied. The pellet with smaller particle size gave a higher reduction rate. Bentonite addition had slightly negative effect on the reduction rate. When reducing industrial pellets, temperature and CO flow rate had positive influence on the reduction rate. Reduction of lumpy ore took place slower than reduction of a pellet. In all samples, chromite reduction proceeded longer in the outer part of the sample than in the centre part. The porosity of the chromite samples was determined before and after the experiments. The porosity of lumpy chromite increased significantly during the reduction. However, the porosity of lab-made chromite pellet decreases due to sintering effect. The reaction mechanism is discussed on the basis of experimental results and earlier investigations.

Jan 1, 2004

By B. W. Lee, P. O?Shaughnessy

The practice of manganese ferroalloy smelting has traditionally been based on utilising oxide ores which typically contain a high level of manganese. This preference for oxides has even been extended to the modification of natural carbonates into nodulized oxides. However smelting practices developed over the past 30 years have created a market for natural manganese carbonate ores, driven in part by the unique properties that this type of ore can offer. An understanding of the mineralogy of carbonate ore and its thermal properties has provided important information which enables furnace operators to take full advantage of the chemical differences. However changes to traditional operating practices have been necessary. Once furnace operations using natural and unmodified carbonate ore have been mastered, the unique chemical features of manganese carbonate ore are able to contribute, not only to new product development, but also to cost savings. The use of natural manganese carbonate ore is now a well-established aspect of the industry. The sustained increase in demand for carbonate ore worldwide over the past several years confirms acceptance of its quality. There are effectively few limits to its successful use.

Jan 1, 2004

By D. M. MacHunter, T. Lawson, D. K. Henderson

The development and commercialization of new generation high tension electrostatic separators has provided a basis for simplifying mineral separation plant circuitry. The inclusion of new design features including insulated plate electrodes that have resulted insignificantly improved separation efficiencies in electrostatic separators are described. The increase in separation efficiency has resulted in a reduction in the number of treatment stages required to produce final high grade mineral products. Comparative performance data on different feed types are presented. A comparison between mineral separation plant flowsheets using both conventional and new generation high tension electrostatic separation technology is presented. A 55% reduction in the number of installed electrostatic separators and a 36% reduction in plant area was achieved through the use of this new electrostatic separation technology.

Jan 1, 2003

By Y. Mao, D. Xie

The viscosity of TiO2-containing blast furnace slags may increase rapidly (commonly referred to as thickening) under strong reducing conditions in the blast furnace. To elucidate the mechanisms for slag thickening, measurements have been made of changes in the composition and rheological properties of TiO2-CaO-SiO2-Al2O3-MgO slags during the reduction process. The slag composition covered the range of 17–33 wt% TiO2, 9–19% Al2O3, 8–16% MgO and theCaO/SiO2from 0.8 to 1.4. The viscosities were measured using the rotating cylinder method at temperatures up to 1550ºC and the fusibility temperatures were determined from ‘breaks’ in the viscosity-temperature curves. The reduction of the slag was carried out in graphite crucibles at1500ºC for 2–6 hours The rheological properties of the slags during reduction were predominantly influenced by the slag basicity (CaO/SiO2), and the effect of other components depended largely on basic or acidic behaviour of the oxide. The reduction of TiO2in the slag by carbon was initially fast to formTi2O3, followed by further reduction to TiO and TiC. Correspondingly, the viscosity showed initially a slight decrease, followed by a gradual and then rapid increase. The thickening was found to be accelerated by an increase in TiO2content and a decrease in the CaO/SiO2in the slag. In addition to the existence of 1~3 wt% TiC, the thickened slags also had a significant amount of TiO (3~7 wt%), suggesting that TiO may play an important role in the ‘thickening phenomena’ ,possibly by forming solid solutions with TiC to significantly increase the number of solid particles in the heterogeneous slag. Keywords: TiO2slags, viscosity

Jan 1, 2004

By P. J. Bhonde, R. D. Angal, R. H. Tupkary

Manganese imparts numerous beneficial mechanical properties. Hence it finds extensive application in iron, steel and non-ferrous sector. Prevalently, it is incorporated in the form of master alloys i.e. 'ferromanganese'. In India, ferromanganese is mainly the inexpensive and paramount source of availability of manganese. Various conventional and non-conventional techniques of ferromanganese production have been adopted in past and present. However, these techniques have demerits viz. high refractory, energy consumption, losses of valuables in slag and fumes. Also geographical co-ordinates of the plant restricted the manufacturer to prefer an appropriate process. Accordingly, the industrially implemented methods had reliance on availability of infrastructure, energy, mineral resources, grade of raw material, outlay of labor, environmental compatibility of technique etc. In view of the liberalized economy and the gap scenario in the supply and demand of ferromanganese, the authors felt it indispensable to explicitly bridge up this vacuum by initially designing a simple energy conserving, eco-friendly, low capital investment technique for decarburization of ferromanganese. Measurement of the data involved studying the impact of rate governing parameters on the process kinetics. This laboratory scale investigation is expected to escalate the Mn/C quotient of high carbon ferromanganese. Key Words: ferromanganese, carbon, carbide, decarburization, rate, kinetic

Jan 1, 2007