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By G. Apsey

Eutectic freeze crystallization (EFC) is a novel technique for the recovery of pure salt and pure water from hypersaline waste brines. It is therefore a promising technology for the treatment of industrial waste waters. The impurities caused by crystallizing salt out of multi-component brines by EFC have not yet been investigated, however. To these ends, the selenium impurity found in sodium sulphate, produced from the waste brine of a platinum operation, was investigated. It was believed that the similarity between sulphate and selenate ions allowed isomorphous substitution of selenate ions into the sodium sulphate crystals, which was the likely cause of impurity uptake. It was found that the presence of sodium chloride in the industrial brine promotes the uptake of selenium, while ionic strength of the brine and mass deposition rate of sodium sulphate did not have a significant effect on the selenium uptake. Isomorphous substitution is predicted to be the most significant mechanism by which all impurities will be taken up when applying EFC to other industrial waste brines.

Jan 1, 2013

By R. M. Lamya

The kinetics of copper cementation during atmosphere leaching of a Ni-Cu matte in CuSO4-H2SO4 solution was studied as a function of initial copper ion concentration, initial acid concentration, temperature, stirring rate, particle size distribution and pulp density. It was found that all these process variables influenced the rate of cementation. A two-stage rate of reaction was observed inmost of the experiments, with the rate of cementation in the initial stage being slower than that of the subsequent second stage. The increased rate of cementation in the second stage was attributed to the enhancing effect of the surface deposit. The cementation process was found to take place by two different rate-controlling mechanisms. At a temperature range of 50?70°C, an activation energy of 74.6 kJ/mol was obtained, indicating a surface reaction controlled process. At higher temperatures (70?80°C) a lower value of activation energy was observed (18.2 kJ/mol), indicative of a process controlled by diffusion through surface layers. The structural characteristics of the cemented deposit could not be determined in the investigated system where the deposit was mixed with the leach solid residue.

Jan 1, 2005

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

Conventionally low carbon ferromanganese is manufactured globally by refining high carbon ferromanganese in liquid state. This process is an expensive and lengthy technique. Hence, the present work was undertaken with the objective of understanding the feasibility and kinetics of the solid state refining of ferromanganese. The process involved transformation of carbon rich carbides viz. Mn3C2, Mn7C3 into metal rich carbide i.e. Mn15C4, Mn23C6 by subjecting the alloy powder to a flowing stream of carbon dioxide. Effect of the process governing parameters such as time, temperature, particle size, pressure on the extent of decarburization was studied. Without any loss of manganese in the form of fumes or slag, it was observed that, there was substantial reduction, viz. 65 per cent in the total carbon content, by this technique. Subsequently, the process was investigated to find out the mechanism of carbon removal. Depending upon the temperature and the particle size, it was found that the rate controlling mechanism changes from chemical reaction control to product layer (ash) diffusion control. The activation energy for each of the aforesaid mechanism was computed. The values thus obtained substantiated the aforesaid mechanisms.

Jan 1, 2004

The 109th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at The Country Club, Johannesburg, Napier Road, Auckland Park on Wednesday, 16 August 2006. Special General Meeting A Special General Meeting to consider the changes to the Constitution was held immediately prior to the AGM. 1. Purpose In order for the SAIMM to remain relevant and ensure maximum value to all members, Council propose three changes to the Constitution. 2. Background Three changes to the Constitution were proposed by the Council on 21 July 2006. These changes now have to be approved by means of a ballot at a Special General Meeting. These three proposed changes are discussed briefly below:

Jan 1, 2006

By S. T. Johansen, C. Colomb, B. Ravary

Combustion and thermal NOx formation have been modelled using the Computational Fluid Dynamics (CFD) commercial code Fluent 6.1. The aim was to predict and give a better understanding of the combustion in electric arc furnaces for the production of ferro-silicon and silicon metal. Another important objective was to assess the impact of a number of operating parameters on the NOx formation. The CFD tools used are de-scribed with a special focus on models for species and turbulence transport. Sensitivity studies have been carried out to study the influence of several parameters: sub-models, process gas composition and distribution at the charge surface and influence of the presence of SiO. The main conclusions are: ?Using the combination of a realistic design, boundary conditions and models, the simulated NOx level is in quantitative agreement with measurements. The presence of water vapor is particularly important because of its influence on the specific heat of the mixture and resulting temperature. ?Release of significant amounts of SiO from the charge surface results in an important increase of NOx, even if we applied a simplified combustion model for SiO gas. However, because of lack of thermal and compositional data for blowing situations (when SiO flows directly from the arc cavity through open channels to the charge surface), no quantitative validation is possible. The way SiO is distributed (uniformly or as a jet) has a limited impact on the result in our computations.

Jan 1, 2007

By S. L. Bell

Most Australian longwall coal mines are currently working coal faces up to nine kilometres from the surface. In the event of a mine emergency walking this sort of distance wearing breathing apparatus becomes very difficult if not impossible. Self-rescue continues to remain the focus of mines rescue in Australian coal mines and this paper describes a vehicle modification which will improve the chances of a miner rescuing himself. Existing mine personnel transport vehicles are not designed to operate in some types of atmospheres that may be present following a mine fire or explosion event. An Australian Coal Association Research program (ACARP) funded research project recently completed in Australia has developed a specification for a vehicle that is able to operate safely in some types of post emergency atmospheres. During the course of this investigation, diesel and electric vehicles were examined prior to making a final decision on vehicle suitability. Based on the fact that there are already some 1500 diesel vehicles in use in underground coal mines in Australia it was decided that modifications to existing diesel engines would be the best option. This presentation will outline the proposed specification for the vehicle and the reasons behind the decisions that were made with respect to the specification.

Jan 1, 2003

By Darelle T. Janse van Rensburg

Some of the more recent developments in Paint Technology are solvent free materials. These coatings have mainly been formulated to overcome the negative attributes of solvent-based coatings, i.e. environmental, safety and health risks, potential for solvent entrapment and osmotic blistering, as well as the formation of micro-pores during the curing process. Two solvent free liquid epoxy coatings have been used extensively on power generation plant. However, very little is known regarding their long-term performance under different exposure conditions, as well as whether these coatings actually perform better than their solvent-borne counterparts. In addition, solvent free materials are generally used where outage periods are restricted and coatings need to be applied within a very short period. Though these materials have reportedly much shorter curing times than other conventional solvent-borne coatings, little is known regarding their limits with respect to maximum film thicknesses and being put into service while still being wet/partially uncured. The latter has become common practice at many power stations in the past two years or so. In addition, the application and curing methods of solvent free materials are different to that of solvent-borne materials, and may require equipment and application process changes. This paper covers the application and performance properties of solvent free coatings in comparison to solvent-borne materials primarily intended for immersion service. Numerous coatings were evaluated under immersed static and cyclic hydrostatic pressures. Other tests included short curing / early immersion tests, dry-to-touch and dry-through curing times, adhesion tests, surface tolerance tests, etc. The results show that the solvent free materials have clear benefits with respect to safety, health, environmental and long-term performance, but will be more difficult to apply compared to solvent-borne materials.

Jan 1, 2006

By S. Ganguly, R. Kononov

Carbothermal reduction of manganese oxides and manganese ores in the solid state was studied in hydrogen, helium and argon at different temperatures, ore compositions and carbon to manganese oxide ratios. Wesselsore (South Africa) and two grades of the Groote Eylandt ore (Australia) with different level of impurities were examined. Ores were characterised by XRD, X-ray fluorescence, optical microscopy and scanning electronmicroscopy. Isothermal and temperature programmed carbothermal reduction experiments were conducted in a fixed bed reactor in a vertical tube furnace, with on-line monitoring of gas composition by the CO-CO2 infrared sensor. The reduced samples were characterised by XRD, SEM and LECO analyses. Extent of reduction was calculated using data on the off-gas composition, and LECO carbon and oxygen contents in the reduced sample. Manganese oxides in the ore were reduced to a-Mn and carbides Mn23C6 and Mn7C3 depending on the carbon to ore ratio. The reduction rate of manganese ores in hydrogen was higher than in helium and argon. Key words: Manganese, Carbothermal Reduction, Hydrogen, Argon, Carbon Monoxide, Helium, Kinetics.

Jan 1, 2007

By R. J. Pine, J. M. Rance, J. S. Coggan

ABSTRACT: The safe design of excavations created in a fractured rock mass is of paramount importance in rock engineering. Depending on the nature of the stress regime acting on an excavation, and the associated deformational behaviour of the rock mass surrounding the excavation, a number of potential failure mechanisms exist. These involve a combination of shear failure on existing joints, extension of critically oriented joints and propagation of new fractures through previously intact rock. Conventional numerical codes usually adopt either a continuum or discontinuum approach; this often results in significant over simplification and kinematic limitations particularly when modelling complex rock mass behaviour in the close vicinity of excavations. This paper describes the results from several case examples using a combined finite element-discrete element code, ELFEN that incorporates a crack propagation mode. Through the use of selected rock engineering examples, the authors demonstrate the potential of the code in the realistic simulation of complex rock failure both in underground and surface excavation applications. RÉSUMÉ: La conception sûre des excavations créées dans une masse de roche fracturée est d'importance primordiale dans la géotechnique. Selon la nature du régime d'effort autour d’une excavation, et le déformation associé de la masse de roche autour de l'excavation, il exsite un certain nombre de mécanismes potentiels d'échec. Ceux-ci comportent une combinaison d'échec de cisaillement sur les joints existants, la prolongation des joints d’orientation critique et la propagation de nouvelles ruptures dans la roche précédemment intacte. Les codes numériques conventionnels adoptent habituellement l’approche, soit d’un continuum, soit de discontinuum; ceci a souvent comme conséquence une sursimplification significative et les limitations cinématiques en particulier en modelant le comportement complexe de la masse de roche très proche des excavations. Cet article décrit les résultats de plusieurs exemples de cas en utilisant un code qui s’agit d’une combination d’élément discret et d'élément fini, ELFEN qui incorpore un mode de propagation de fissure. Par l'utilisation des exemples choisis géotechniques, les auteurs démontrent le potentiel du code dans la simulation réaliste de l'échec complexe de roche pour les applications aux excavations soit au fond soit à l’extérieure. ZUSAMMENFASSUNG: Das sichere Design der Aushöhlungen, die in einer zerbrochenen Felsenmasse verursacht werden, ist vom paramount Wert in der Felsentechnik. Abhängig von der Natur des Druckregimes, das auf einer Aushöhlung und dem dazugehörigen deformationalen Verhalten der Felsenmasse umgibt die Aushöhlung fungiert, bestehen eine Anzahl von möglichen Ausfalleinheiten. Diese beziehen eine Kombination des Scherausfalls auf vorhandenen Verbindungen, Verlängerung der kritisch orientierten Verbindungen und Ausbreitung der neuen Brüche durch vorher intakten Felsen. Herkömmliche numerische Codes nehmen normalerweise entweder ein kontinuum oder discontinuum Annäherung an; dieses ergibt häufig bedeutende Übervereinfachung und kinematische Beschränkungen, besonders wenn es kompliziertes Felsenmasseverhalten in der Nähe der Aushöhlungen modelliert. Dieses Papier beschreibt die Resultate von einigen Fallbeispielen mit einem kombinierten begrenzten Element - getrennten Elementcode, ELFEN, das einen Sprungausbreitungmodus enthält. Durch den Gebrauch von vorgewählten Felsentechnikbeispielen, demonstrieren die Autoren das Potential des Codes in der realistischen Simulation des komplizierten Felsenausfalls bei Anwendungen für beide Tagebaue und Untergrundsaushöhlungen.

Jan 1, 2003

By J. P. Bergh

The advent of low-quality export coal demand has brought a new range of possibilities to the South African coal industry. Products that traditionally were only of value to the domestic or combustion industry sectors now have the potential to be exported, with only minor amounts of upgrading required through beneficiation. Comparatively high steam-coal export prices can be obtained for lowquality export coal, which enhances the economic feasibility of expanding low-quality thermal coal exports. There are, however, increasing concerns about the feasibility of lower quality thermal coal exports and the broader implications. These concerns relate to the environmental impact of low-quality thermal coal production for export and the inherent threat to the security of domestic thermal coal supply in South Africa. Against this background, this paper serves to explain the extended value chain in the production of export coal. The technical and economic advantages and disadvantages of low-grade exports versus coal production for domestic use are evaluated. The value chain estimation is calculated by the beneficiation modelling and characterization of two coals. Based on the value estimation, the lowgrade export production scenario, and finally the modelling of potential pollutant distribution, are described. Keywords coal beneficiation, techno-economics, thermal coal, dense medium processing, dry processing, fine coal processing, environmental impact.

Nov 1, 2013

By D. Xie

An in situ gravimetric technique based on wetting and capillary action principles has been used to investigate the wetting and penetration of synthesized alumina samples and commercial magnesia spinel refractories by CaO-SiO2-Al2O3-Fe2O3slags. Synthetic slags of 40CaO-40SiO2-20Al2O3 (in weight per cent) with 0 to 9 weight per cent Fe2O3were used and the experiments were conducted at temperatures 1370 to 1470ºC under argon. The contact time between the sample and the slag was 30 minutes. The results show that the wetting and penetration are enhanced by the iron oxide addition in the slags. Addition of Fe2O3from 0 to 9 weight per cent resulted in a significant increase in the slag penetration into the magnesia spinel refractory by a factor of about 7 and a moderate increase in the synthesized alumina by about 60 per cent. The addition of Fe2O3enhanced the wetting (??cos?, where ? is the surface tension of the slag and the contact angle between the slag and the refractory) by 5 to 18 per cent. An increase in temperature from 1370ºC to 1470ºC resulted in a significant increase in the penetration of a 6 weight per cent Fe2O3slag in the alumina and magnesia samples by a factor of4 to 5 and a decrease in wetting by approximately 30 per cent. Keywords: refractories, slag penetration, wetting.

Jan 1, 2004

By M. Matema

Paper written on project work carried out in partial fulfilment of BSc (Eng.) Metallurgy and Materials Engineering Small and large welded aluminium specimens were tested in fatigue and the results compared with design curves for aluminium in specification BS8118. Metallurgical tests were also performed on the specimens in order to correlate microscopic and macroscopic phenomena. The small-scale fatigue test results were in reasonable agreement with results in BS8118, whereas the large-scale fatigue tests showed that BS8118 is conservative.

Jan 1, 2005

By S. Montes

Mineral floatability is strongly connected with mineral structure and composition. The complexity of mineral surfaces has meant that few attempts have been made to understand the effect of impurities (trace elements) on the flotation process. Zeta potential technique has been extensively used to evaluate the surface charge of mineral particles. Nevertheless, those measurements consider only an average of mineral particles surface charge. The presence of fine particles and inclusions covering a mineral may influence the local reagent adsorption process, which will ultimately be reflected in the subsequent global response of the mineral froth flotation efficiency. The current work assesses the iron oxide mineral, haematite (Fe2O3). Zeta potential and streaming potential techniques were used to determine the surface charge of fine and coarser particles of haematite. Further analysis was performed to determine the point of zero charge (PZC) of the mineral. In addition, adsorption isotherms of alkyl ammonium chloride reagents with different lengths of carbon chains were carried out. It was found haematite floatability depends strongly on the isoelectric point (IEP) value, which is affected by other mineral species present at the mineral surface. Haematite floatability became significant only at relatively high tetradecyl ammonium chloride collector concentrations (concentration greater than 4 10-4M), which does not happen with other oxides such as quartz. Unlike quartz, haematite develops a low surface charge over a wide range of pH, disabling all long-range attractive interactions between the mineral and the collector. Therefore, hydrophobic chain interaction is probably the most likely mechanism acting to promote collector adsorption and enhance further floatability. Diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to suggest a possible mechanism to understand the sequence of collector adsorption and the effect of trace species on it. Keywords: floatability, haematite, adsorption, electrochemistry, zeta potential.

Jan 1, 2007

By A. J. Geldenhuys

This paper will focus on two topics, namely (1) an innovative process for the neutralization and partial sulphate removal of acid streams produced during coal mining and processing and (2)optimization of this integrated neutralization process by adding small amounts of synthetic organic polymers. The integrated lime and limestone process has been developed to neutralize acid mine water and to remove sulphate (to less than1 200 mg/l), magnesium and metals. Limestone and lime treatment is the most cost-effective technology for neutralization and partial sulphate removal of acidic/sulphate-rich water to sulphate levels of less than 1 500 mg/l due to precipitation of magnesium and removal of the associated sulphate fraction (through gypsum crystallization). Neutralized mine water of this quality may be suitable for irrigation. The process consists of the following stages: 1. Limestone (CaCO3) neutralization to raise the pH to 7 and CO2-production. 2. Lime (Ca(OH)2) treatment to pH 12 for Mg(OH)2precipi-tation and gypsum (CaSO4.2H2O) crystallization. 3. pH adjustment with CO2recovered from stage 1 and CaCO3 precipitation. Retention times of 1 hour, 4 hours and 1/2an hour were required by stages 1, 2, and 3 respectively. The sulphate level was reduced to 1 094 mg/l, which is less than the original aim of 1 200mg/l. Chemical costs associated with neutralization, using limestone instead of lime, are reduced by 69% in the integrated limestone/lime process. The overflow water from the clarifier of each of the above stages generally contains a wide variety of colloidal impurities that may cause the water to appear turbid or may impart colour. This results in very slow sludge settling rates that cause overflow water with a high degree of turbidity and colour. There are a number of successive or simultaneous stages involved in the agglomeration of particles. To get optimum neutralisation of the acid water and partial sulphate removal to below the saturation level of gypsum (i.e. 1 500mg/l), maximum sludge recovery is needed. The higher the concentration of seed crystals, the larger the surface area. Therefore, effective removal of suspended and colloidal matter from the overflow of each stage is required and can be achieved by coagulation and flocculation. The polymers PAC6 and 3095 were effectively used as coagulant and flocculant respectively. The addition of these polymers resulted in a clear overflow in each of the above stages with a very low turbidity.

Jan 1, 2003

The 108th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at The Country Club, Johannesburg, Napier Road, Auckland Park on Thursday, 11 August, 2005. Welcome The President extended a special welcome to the guests and representatives of our sister institutes and other associations, also to recipients of awards, senior members of industry, Honorary Life Fellows, past-presidents, our members and other guests, among them the following: Dr Con Fauconnier, President, Chamber of Mines of South Africa Prof. Jay Barton, President, The Geological Society of South Africa V. Townshend, President, Institute of Certificated Mechanical and Electric Engineering, South Africa M. Livingstone-Blevins, President, Institute of Certificated Mechanical and Electrical Engineers, South Africa Prof. B. Lacquet, President, South African Institute of Electrical Engineers Dr F. Malan, President, South African National Institute of Rock Engineering

Jan 1, 2005

By K. Drescher

Excavations in deep level hard rock mines show rheological or time-dependent deformation responses to mining-induced stresses. These are generally not as dramatic as those seen in soft rock environments, such as potash and salt mines, but these deformations can nevertheless become substantial in time. It is usual to see total excavation closure at a much earlier stage than predicted by numerical models, and real-time measurements underground have confirmed that closure takes place on a more-or-less continuous basis, with highest closure rates observed after a blast and then slowly diminishing with passing time. This paper describes laboratory tests to determine the time-dependent response of hard rocks to loading, the results of the tests, and then quantifies these effects to explain the time-dependent phenomena observed underground. The primary intention of this work is to help explain the various time-dependent deformation processes around typical deep level hard rock tabular excavations. Three mechanisms were investigated in two typical hard rock types present in the deep level gold mines in South Africa, namely Ventersdorp Lava and Elsburg Quartzite. Uniaxial compression creep studies were done as the first part of the study followed by shear creep studies on discontinuities where crushed lava and crushed quartzite as well as a natural gouge were used as infilling. The last part of the study consisted of triaxial post-failure relaxation tests. The compression creep tests and the triaxial post-failure relaxation tests showed that the amount of energy dissipated by the lava is significantly less than for quartzite. For mines operating at depths greater than 2000 m the implication is that the lava must show a greater rockburst-proneness than the quartzite. Since the lava shows a lower post-failure stress relaxation, it can store sufficient energy for multiple rockbursts, which is seen in the clustering of multiple seismic events in the deep level mines. This study provides the first data available for energy change calculations in fractured rock masses, and provides the first general indications for rockburst intensities ahead of active mining faces.

Jan 1, 2003

By E. M. Bloomfield, C. A. Jermy

Geotechnical tests were carried out within an area of the coastal sand dune cordon of northern KwaZulu-Natal which is currently being exploited through mining of heavy mineral sands. In situ and laboratory tests were carried out to assess the density, strength and stability of the dune sand material before and after mining. The most stable combination of sand (>63µm) and fines(<63µm) material was determined as well as the effects of compaction on the strength and permeability of the sand dune samples. In situ DCP and density tests showed that the sand dunes fall in density immediately after mining has taken place. However, settlement of the dunes occurs with time and the density increases within the top 2 metres, and particularly once the dunes become re-vegetated. Laboratory tests carried out showed that the dune sand with between 20% and 30% added fines had the highest shear strength and dry density, but the permeability was shown to decrease steadily with increasing fines up to 40% fines added. The addition of fines would result in steadily increasing water flow problems. Compaction of the dune sands was shown to significantly increase the density and the shear strength, but with a corresponding dramatic decrease in the permeability of the material. Slope stability analysis carried out on models of the dunes with increasing fines showed that the addition of fines increases the stability of the dune sands up to a peak of about 30% fines added, and compaction further increases the stability of the dune sands. Despite the benefits of compaction on the stability of the tailings dunes, the loss of permeability is thought to outweigh the benefits as well as the high costs involved. The stability of the tailings dunes greatly increases after re-vegetation. Compaction and densification of the tailings dunes may be necessary within the top 2 m interval if large-scale construction takes place on the sand dunes. Petrographic analysis was performed to understand the granular interactions of the sand and fines fractions, and the effect of the in situ weathering of the dune sands on the stability of the sand dunes. As the fines contents increase the gaps between the sand grains are filled, until a point where the percentage of fines begins to push the sand grains apart.

Jan 1, 2003

By S. Frimpong, S. R. Dindarloo

Material handling in open pit mining accounts for about 50% of production costs. The selection and deployment of efficient, safe, and economic loading and haulage systems is thus critical to the production process. The problems of truck and shovel selection and sizing include determination of the optimal number and capacities of haulage and loading units, as well as their allocation and operational strategies. Critical survey and analysis of the literature has shown that deterministic, stochastic, and experimental approaches to these problems result in considerably different outputs. This paper presents a comprehensive simulation framework for the problem of truck and shovel selection and sizing based on the random processes underlying the network-continuous-discrete event nature of the mining operation. The framework builds on previous research in this field and attempts to address limitations of available methodologies in the form of a comprehensive algorithm. To test the validity of the framework a large open pit mine was evaluated. The stochastic processes governing the uncertainties underlying the material loading and haulage input variables were defined and built into the stochastic model. Discrete event simulation was used to simulate the stochastic model. The proposed model resulted in several modifications to the case study.

Jan 1, 2015

By H Zimba, S Sondashi, M Chitambo

By the time a reagent is finally accepted by a mine for use on its plant it could have gone through several screening and evaluation stages. These stages may include laboratory and plant evaluation testwork. This paper outlines the steps that were followed to select, design and implement a frother for KONKOLA COPPER MINES PLC Nchanga Copper Concentrator in Zambia. It discusses initial frother screening work conducted at the Betachem metallurgical laboratory and the subsequent laboratory screening testwork conducted at Nchanga Concentrator. A modified Bikerman test method is discussed which was used to design a frother for the Nchanga flotation plant. The paper also gives an account of several plant scale trials conducted on Nchanga flotation plant and discusses the plant results, frother consumption patterns and some commercial concerns, before the product was finally accepted by the mine.

Jan 1, 2007

By L. Holappa

Ferroalloys like FeCr and FeMn are mostly produced in submerged electric arc furnaces. Typical of these processes is that the amount of slag is quite high. The role of slag for the process is thus essential and specific chemical, physical and electrical properties are required. Slags in FeCr process are Al2O3-MgO-SiO2 based with minor contents of CaO and CrOx. Slags in the FeMn process are principally similar, originating from silicate minerals but can have quite large composition range depending on the manganese ore and its gangue minerals. Characteristic of the FeMn process is that the slag is rich in manganese oxide up to above 30%. A common feature is that the ?ore oxides?, CrOx and MnOx in slag are not only divalent oxides but also contain some higher valent of Cr3+and Mn3+, respectively. In FeMn production conditions the slag consists mainly of Mn2+. This is a clear difference from CrOx containing slags in which both two and three valent coexist in slags in FeCr process conditions. Oxidation state of the slag depends on the ambient oxygen partial pressure and temperature in the examined process. The thermodynamics of slags in ferroalloys, production are discussed in terms of phase diagrams, activities and oxidation state of chromium and manganese oxides. Further, slag properties influencing reduction kinetics and furnace operation i.e. viscosity and electrical resistivity are discussed. Keywords: review, slags, ferroalloys, ferrochromium, ferromanganese, thermodynamics, physical properties

Jan 1, 2004