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By E. Dzingayi

Keywords: Pyrometallurgy, furnace, Bindura, nickel The smelter at Bindura Nickel Corporation processes concentrates from its own mines and other external sources. Concentrates are dried, smelted, and converted to a desulphurised matte (leach alloy) for further processing at the refinery. The smelter comprises a drying plant, submerged arc electric furnace, electrostatic precipitator, and three Peirce-Smith type converters capable of treating 150 000 tonnes of concentrates per year. Concentrates are dried in a rotary coal-fired kiln, blended with fluxes, and smelted in a six-in-line submerged-arc 15MW electric furnace. Slag is tapped and granulated for disposal, and matte is tapped at regular intervals for blowing in Peirce-Smith converters. The paper details the 37-year history of the smelter, including furnace rebuilds and operating parameters as they have evolved in response to changing feed compositions. Special challenges, particularly relating to the treatment of high talc concentrates, are also described.

Jan 1, 2006

By B. P. Watson

Uniaxial tests performed on core from instrumented sites at Amandelbult 1 shaft, Impala 10 shaft and Union Section Spud shaft showed a nonlinear elastic relationship between applied load and induced deformation. This nonlinear behaviour does not appear to be dependent on borehole orientation but in the case of the Amandelbult and Union sites appears to have been influenced by the stress condition of the rock mass at the time of drilling. Cores drilled at these two sites under destressed conditions, such as over a stope, showed a linear elastic response to the applied load whereas most of the cores drilled under relatively high radial stresses were nonlinear. The Impala 10 shaft tests, however, all showed strong nonlinear behaviour irrespective of the stress condition of the rock mass at the time of drilling, although high stress conditions may have influenced the severity of the nonlinearity. A comparison between underground stress change measurements and an elastic model indicated that the rock mass became nonlinear when the virgin stress condition was relaxed to about 10 MPa. The cores for laboratory testing were retrieved from vertical boreholes drilled up from the centre of a stope and from horizontal boreholes drilled over pillars and stopes at about 600 m, 1 100 m and 1 400 m below surface for the three sites respectively. The k-ratios under virgin conditions were estimated from sockets, modelling and stress measurements to be 1.0, 1.3, and 0.5 for the Amandelbult, Impala and Union sites respectively. Of the three sites, therefore, Impala 10 shaft appears to have had the highest virgin stress state. Tests performed on similar rocks from shallower depths at Impala Platinum essentially showed a linear relationship between stress and strain. From the small Impala Platinum rock test database available to the project, it appears that the nonlinear elastic behaviour initiates at this mine from about 1 000 m below surface and seems to become progressively more nonlinear below this depth. In addition, the nonlinear elastic rocks are weaker, have a lower Young?s modulus and a higher Poisson?s ratio than their linear elastic equivalents. Interestingly the tangential Poisson?s ratios of the nonlinear elastic materials are often greater than 0.5 at 50% of the failure stress, suggesting an early failure initiation. The paper describes the microscope and modelling work done to determine the causes of the nonlinear behaviour and discusses some implications of the behaviour for deep-level mining.

Jan 1, 2009

By R. T. Jones

Slags have been produced as by-products from pyrometallurgical processes for thousands of years, and have generally been regarded as waste. Many of these slags are no longer seen as residues merely to be discarded, but as potential economic sources of metals, or as useful by-products in their own right. Slag cleaning can enhance the recovery of valuable metals in existing pyrometallurgical processes, or can produce economic value from recycling old slag dumps. For example, a process has been developed and implemented industrially for recovering cobalt from copper smelting slag in a DC arc furnace. The relatively non-leachable behaviour of glassy slags allows them to be used as a very safe means of disposal of metallurgical waste streams, including many that are classified as hazardous. The high temperatures, reducing conditions, and good mixing that can be achieved in a DC arc furnace enable the effective functioning of this environmentally beneficial means of disposal. Lead blast furnace slag can be rendered safe for disposal by treating it using the Enviroplas process, which strips most of the hazardous lead from the slag (and traps the rest in an insoluble glassy slag) and recovers economic quantities of zinc by absorbing (in a lead splash condenser)the zinc vapour that is fumed off in the furnace. Another example can be seen in the recovery of a chromium- and nickel-containing alloy from stainless steel plant dust, while producing a disposable residual slag. The examples presented here illustrate that it is possible to develop processes that are both economic and environmentally beneficial. Keywords: DC arc furnace, plasma, slag cleaning, cobalt recovery, zinc fuming, Enviroplas, jigging, re-melting fines, environmental, economic

Jan 1, 2004

1. New books 1979 Louisville Coal Conference proceedings. Epping (England), Bowker Publishing Co., 1980. 4 vols. $43.00. Proceedings of a joint meeting of the Institution of Mining and Metallurgy, the Society of Mining Engineers of AIME, and the Metallurgical Society of AIME, held in London, 27 to 30 May, 1980, by M. J. Jones (ed.). London, Institution of Mining and Metallurgy, 1981. 350 pp. £46. Economic mineral deposits, by M. L. Jensen and A. M. Bateman. 3rd ed. New York, John Wiley, 1981. 752 pp. $22.95. E & MJ intErnational directory of mining and mineral processing operations. Epping (England), Bowker Publishing Co., 1980. 1314 pp. $67.00. Physical methods in modern chemical analysis, by T. Kuwana (ed.). New York, Academic Press, 1980. Vol. 2. 432 pp. $38.25. English translations of DIN standards. Availablefrom the SABS, Private Bag 191, Pretoria 0001. Mining international year book. London, Financial Times, 1981. 730 pp. $90.00 airmail, £37.50 surface. Analytical atomic absorption spectroscopy. Selected methods, by J. V. van Loon. New York, Academic Press, 1980. 360 pp. $35.00. 2. NIM reports Report no. 1848 An electrochemical and kinetic investigation of the behaviour of gold in chloride solutions. I. The cathodic deposition of gold. (First issued 7th Jul., 1976.) Report no. 1844 An electrochemical and kinetic investigation of the behaviour of gold in chloride solutions. 11. The anodic dissolution of gold. (First issued 7th Jul., 1976.) Report no. 1846 An electrochemical and kinetic investigation of the behaviour of gold in chloride solutions. 111. The gold(II1)- gold(I) eaction on platinum and the disproportionation of gold(I). (First issued 7th Jul., 1976.) Report no. 1979 An electrochemical investigation of the behaviour of gold in chloride solutions. I V. Results obtained from Phase 2 of the investigation. (First issued 30th Jun., 1978.) Report no. 2093 The measurement of electrical variables in a submergedarc furnace. Steels for pipelines Since welding was first introduced as a method of joining pipelines, gas-pipeline engineers have taken the opportunity to increase gas pressures, and hence increase the efficiency and economy of transporting gases. Envitec '83 The International Trade Fair and Congress for Engineering in Environmental Protection - the ENVITEC '83 - will take place in Diisseldorf from 21st to 25th February, 1983.

Jan 1, 1981

By P. K. Hofmeyr

Base Metal (Cu, Ni, Mo, Zn, Co etc.) analysis traditionally has been very slow in conventional analytical laboratories which can lead to additional costs being incurred in waiting time of drill rigs or mining excessively off-reef. Recent developments in the automation of analytical laboratories now allow for very rapid turn-around times for base metal analytical data which can help reduce such costs as well as reduce the unit costs of the analyses themselves. 2.0 CONVENTIONAL ANALYTICAL LABORATORY PRACTICE Conventional analytical laboratories are necessarily are very manual. Sample preparation is slow and laborious, samples are moved from stage to stage manually and, typically, all samples are processed in batches so a sample which is the first to be, say, milled has to wait for the complete milling of the batch before it advances to the next stage eg. mixed with wax prior to pelletising for XRF analysis. Inevitably this results in long sample data turn-around times for laboratories handling large numbers of samples. Manual sample preparation can only be accelerated by increasing staff which increases costs and can lead to additional errors being introduced. Cleaning of sample preparation equipment, eg. crushers and mills, between samples is essential to avoid cross-contamination between samples and this is slow and labour-intensive. In manual sample preparation the correct sample numbers staying with the samples is totally dependent on the efficiency of laboratory operators. It is extremely difficult to detect when errors have occurred due to the switching of sample numbers during the sample preparation stages. Running duplicates and QC samples at best is only partially successful in detecting when sample number switching errors have occurred. Errors of this nature and cross-contamination problems due to incomplete cleaning of sample preparation equipment tend to occur when laboratories are working at pressure due to high sample numbers and when supervisors are not present during 24/7 laboratory operations which is often required on plant process control laboratories. These problems are common to all conventional analytical laboratories and their magnitude is dependent on the level of control and efficiency of QC systems practised by individual laboratories. The disadvantages of conventional manual analytical laboratories can be summarized as follows:- 1. Labour-intensive which is costly especially when multiple shifts have to be used during 24/7 operations.

Jan 1, 2005

By T. Z. Mugodi, D. R. Fleming

Information and Communications Technology (ICT) is defined as ‘The goods and services that support the electronic display, processing, storage and transmission of information’. Early in 2002 the South African Department of Trade and Industry (DTI) commissioned a study into the diffusion and adoption of ICT in eight sectors of the economy. The platinum mining Sector was one of these. The key findings presented in this paper are based on the platinum sector component of that study. The paper examines the theoretical basis behind technology transfer and innovation diffusion and presents the results of an ICT diffusion survey carried out in the South African platinum mining sector. ICT is shown as the modern day technological tool which is an accelerator of economic development. The current state of ICT diffusion in the platinum mining sector is defined and projections for the near future are given. Recommendations which will ensure smooth and full adoption are presented and justified.

Jan 1, 2003

By P. K. Sahoo, C. R. Ray, S. S. Rao

This paper deals with various factors affecting the strength of chromite briquettes which plays a vital role in the smelting of charge chrome / ferro chrome production. Appropriate briquetting parameters like molasses and lime binder level, molasses quality, particle size distribution and segment condition etc. are essential to guarantee quality briquettes in the successful use of briquette and chromite ore fines. In developing a technology for briquetting of chromite ores, it is important not only to study the grain size characteristics of the chrome ore fines but also to make an informed choice of the type and quality of the binder and the condition for producing a physically and chemically competent green and cured briquette. This paper also describes the effect of strength of briquettes on various parameters of charge chrome production as the use of quality briquettes in the production of high carbon ferrochrome alloys has a number of operational, metallurgical and economic advantages. It is also a requirement for submerged arc furnace operation that the charge be adequately porous to allow gaseous products of the reduction reaction to escape from the furnace charge burden without hindrance. Otherwise, furnace material would erupt causing electrodes and furnace other equipments damage and risking the safety of the work force. The briquette, because it replaces lumpy charge but has an advantage of smaller size, allows for an uniform and porous charge so that the ascending gaseous products can escape freely. Finally this paper deals with furnace operational results with varying proportion of briquettes having same strength.

Jan 1, 2007

By Y. Ren, B. Yang

The magnetic field characteristics due to electromagnetic stirring in the secondary cooling zone of an extra-thick slab during continuous casting are numerically determined using Maxwell's equations, with particular emphasis on the distribution of magnetic induction intensity and electromagnetic force, as well as the influence of process parameters on the magnetic field. The orientation of the electromagnetic force is the same when the electromagnetic stirrers at the 30° and 60° posistions of the arc-shaped slab are powered in the same direction; otherwise, the orientation is opposite. The magnetic induction at the centre of the section of the stirrer's central axis at the 30° positio, as well as the current, frequency, and fitting formulae, are as follows: B = {0.075I.(1/A)-0.3} mT and B = {-1.75f.(1/Hz)+22} mT. The electromagnetic force and current fitting formula at the central point of the B-B section is F = {0.03168I2.(1/A2)-03.762I.(1/A)+326.7} N/m3, and the fitting formula of electromagnetic force and frequency at the centre point is divided into two segments. The first takes the form of a parabola: = {-21((f-4.3).(1/Hz)2)+970} N/m3, and the second segment is negative linear: F = {-1.65f.(1/Hz)+51.5} N/m3.

Apr 16, 2024

By John E. Leitch

The cost of corrosion as measured by such cost components as the renovation or replacement of coated steel, or the use of expensive coating systems on steel, is considerable. Extrapolating from figures for the USA would place the overall cost of corrosion for South Africa as a figure of the order of magnitude of something over 1% of the GNP. This is a sizeable amount, of which costs associated with atmospheric corrosion would be a significant proportion. The corrosivity of an atmosphere can be defined as the ability of the atmosphere to cause corrosion in a given metal or alloy (International Standards Organization [1]). The ISO Standard 9223 specifies the key factors in the atmospheric corrosion of metals and alloys, and defines categories of corrosivity on the basis of these factors. Prior to the publication of that ISO standard, Callaghan published the results of his twenty-year exposure programme and his excellent corrosivity map of Southern Africa [2]. The present author published updates of the corrosivity map in 1999 [3] and again in 2003 [4]. The summary of the individual areas of corrosivity around Southern Africa was published in the latter paper, and is reproduced here as the following TABLE 1. Of significance in TABLE 1 are the numerous regions of very high corrosivity (C5 or beyond), particularly the rural West Coast shoreline, the North East Coast (KZN) shoreline, and the coastal cities Cape Town, Durban and Richards Bay. The corrosivity map as published is obviously based on much extrapolation as only a small number of points have been measured. During the past three years further measurements have been made, mostly however at the same sites in order to give greater reliability and to monitor long-term trends with changes in pollution. These two aspects are incorporated in this update. There has become available a greater amount of air pollution data for centres in South Africa than was the case some years ago. In this present paper the pollution data are used to extrapolate the corrosivity over areas where little or no direct corrosivity measurement has been made. This methodology is described in ISO 9223.

Jan 1, 2006

By R. Abela

Heavy mineral sands are usually beneficiated in a spiral concentrator circuit prior to separation of heavy minerals into streams of zircon, rutile and ilmenite. The performance of the spiral concentrators is heavily affected by the presence of slimes in the rougher feed. The paper quantifies the effect of slimes content and discusses the beneficial effect of spiral feed de-sliming. The net effect of inefficient slimes removal can cause significant recovery losses of the heavy minerals present in the feed.

Jan 1, 2003

By R. Boom, K. C. Mills, S. Riaz

This paper details the recent trends in slag-related research from 1999 to 2003. The trends in thefollowing are outlined: • Annual publication rate • Geographical origin of the work • Nature of the research (e.g. thermodynamics, kinetics) • Nature of the slag studied. This study has revealed that slag research in the USA and Europe has decreased to about a half over the last 20 years and that there has been a significant decrease in Japanese research in this area in recent years. However, these decreases have been offset by significant increases in Chinese and Korean research activity. There has been a significant increase in the amount of work carried out on the recycling and environmental aspects of slags in recent years.

Jan 1, 2004

By John Austin, Graham Pingram

The idea of GOLD 100, an international conference on gold, was first conceived by Mr Les Haughton of Mintek in mid 1984. By the beginning of 1985, plans were well advanced to hold what was to be the most comprehensive conference on gold ever organized. Appropriately, GOLD 100 was timed to coincide with the celebration of Johannesburg's centenary. Leaching The South African Institute of Mining and Metallurgy will hold a two-day colloquium on the topic of leaching on 8th and 9th November, 1988, with the objective of bringing the latest developments in leaching technology to the attention of the mineral-processing industry.

Jan 1, 1988

By S. C. Gouws

"SynopsisSustainable infrastructure development has long been identified as a key enabler for socio-economic growth and poverty reduction in societies globally. Twenty-one years into the young South African democracy, economic prospects are fragile and unemployment statistics are high. According to Trading Economics (2015) the GDP growth rate in South Africa averaged 3.07% from 1993 until 2015.Through the National Development Plan 2030, the government has responded by instituting the Presidential Infrastructure Coordinating Commission (PICC) to direct national growth and drive job creation by effecting a long-term infrastructure investment programme. The Commission is mandated by Cabinet to coordinate, integrate, and accelerate implementation of more than 150 individual social and economic infrastructure plans.In the civil infrastructure development sector, increased urbanization is compelling governments and the public sector to expand safe and reliable public amenities, but the availability of real estate for construction in congested cities is a challenge. Within the mining infrastructure construction industry safe, rapid, and efficient mine extraction strategies are imperative to realize increased production, business hurdle rates, and stakeholder expectations.Asset owners and stakeholders are obliged to consider advanced mechanized underground excavation and support technologies in order to present feasible solutions timeously. From an engineering design, procurement, and construction management (EPCM) perspective tunnelling technology and boring applications have a distinct advantage over conventional excavation techniques. These solutions may enhance commerce and transportation by expanding infrastructure in concentrations of national economic activity, providing crucial linkages with rural areas, between cities, and across international borders.This paper explores the contribution by mechanized tunnelling technology and boring applications applied in conjunction with digital and automation technologies compared with conventional methodologies. The technological expertise, combined with a paradigm shift in delivery of project objectives, will promote economic growth, aid recovery from the economic downturn, and improve social development."

Jan 1, 2015

By K. P. Kavun, M. N. Denisov

Discussed in the paper is the redesigned reserve/resource classification for solid minerals being put forth by the authors to replace the acting Russian classification of 19961. The new version is based on the traditional foundations of former Russian classifications and the principles of the ‘McKelvey box’, both categorizing mineral resources according to the degree of geological assurance and economic viability. Based on these approaches the classification deliberately deals with both reserve and resource categories very similar to those established by the Geneva Accords in terms of definitions implied. The authors proceed from the UN-ECE proposed concept of ‘reserves’ being a part of ‘total resources’ explored in great detail by geological and feasibility studies and economically mineable at the time of reporting. The draft classification distinguishes ‘proved’, ‘probable’ and ‘possible’ categories of reserves depending on the stage of feasibility assessment carried out, i.e. the degree of detail and accuracy with which modifying factors affecting mineability of an orebody are taken into account. The reserves are regarded as a product of feasibility assessment of ‘measured’, ‘indicated’ and ‘inferred’ resources. The portions of them not having been classified as ‘reserves’ are regarded as composed of two classes: ‘subeconomic’ and ‘potentially economic’ resources (or ‘resource base’). All the cells of the classification matrix are provided with traditional for Russia alphanumeric designations and appropriate UNFC codes. The classification scheme recommended is viewed as a step forward in improvement of the State inventory and reporting mineral resources in market conditions, conducive to cross-border professional collaboration in the field of providing reliable information on the mineral rawmaterials base of the world’s economy. Besides, it recommends an easy way to get rid of amethodological error in the UNFC classification scheme where consecutive stages of geologicalexploration are identified with a single inherent degree of geological assurance. Keywords: mineral resources, mineral reserves, classification, geological assurance, feasibility studies, subeconomic resources, undiscovered resources, competent person.

Jan 1, 2003

By R. E. Wilmot

The problem of corrosion of reinforcement in concrete structures is internationally recognised and represents the single biggest expenditure in the preservation of steel reinforced concrete structures. While the corrosion protection of the reinforcing steel is no substitute for design and the placement of good quality concrete, it does provide for a viable and economical extension of structural integrity and service life in the day-to-day and practical environment in which concrete structures are constructed. The mechanism of corrosion attack and consequent deterioration of reinforced concrete structures is well understood and documented. New structures can be designed and built to withstand corrosion. However, due to short-term economical restraints, many new reinforced concrete structures continue to suffer as a result of corrosion damage, which results from the corrosion of the steel reinforcing. This paper explores the economic and practical benefits offered by the application of hot dip galvanizing as a viable means of protecting reinforcing steel concrete structures. The paper also discusses technical misconceptions that exist with respect to the application and performance provided by the use of hot dip galvanized reinforcing steel.

Jan 1, 2006

By G. Cockburn

Nkomati Nickel JV exploits the ores of the Uitkomst Complex near Machadodorp in the Waterval Boven district in South Africa?s Mpumalanga Province. Due to factors such as the remote location, stellar growth in production, opencast mining methods, and ore characteristics, a number of innovative processing options were selected. Nkomati has undertaken numerous initiatives over the last few years to improve plant running times, metallurgical performance, and operational profitability. Great emphasis has been placed on effectiveness of management control systems. A number of initiatives such as short interval control and time?in-state metrics have been implemented. A focus on improvement on availability and asset utilization of key items of equipment has been particularly effective. While the ores are remarkably similar to the Merensky and UG2 reefs, the relatively high base metal sulphide content and mineralogical characteristics make metallurgical treatment somewhat different to the ores of the Bushveld Complex. The low head grades and flotation kinetics distinguish Nkomati from other base metal operations. Numerous milling and flotation optimization initiatives have resulted in dramatic improvements in throughput, recoveries, and concentrate grades. This paper discusses the metallurgical, operational, and management challenges and the outcomes obtained.

Jan 1, 2014

By R. C. D. Phillis

Conventional stoping in hard rock mining is largely considered an operational environment. This paper suggests that stoping falls within the realm of a project management environment typified by uncertainty, variation, and large numbers of interdependencies. Stoping was then equated to a micro-project with many simultaneous activities that had to be executed accurately using finite resources within limited shift durations in order to reach specific goals. Critical chain project management (CCPM) principles were applied to the stoping activities, and the results showed that the number of blasts per panel can be significantly increased by successfully moving the distribution of work as close as possible to the start of shift. Critical chain principles also assisted in facilitating re-focusing and teamwork among stoping crews as well as between day- and night-shift crews. The main recorded success was in managing inherent protective capacities/local contingencies/fat/buffers that are found in all projects. The impact on mine health and safety (MHS) was significant as individual operators and crews became convinced that they could perform all stoping tasks (activities) without compromising accuracy or speed.

Jan 1, 2011

By L. W. Burger

The need to establish and harmonise methodologies to quantify air emissions, atmospheric dispersion and the consequences of air pollutants (especially hexavalent chromium) from the ferrochrome industry became important aspects with the increasing demands for comprehensive impact assessments. The paper includes a synthesis of current knowledge on the following aspects: ? Locally and internationally accepted methodologies for the quantification of chromium emissions, including sampling methods and emission factors; ? A compilation of recognised and accepted air quality sampling and laboratory analysing techniques; and, ? Dispersion modelling and impact assessment tools. Depositing and removing materials from the chromium ore stockpile and wind erosion of exposed stockpiles result in mainly chromite emissions unlikely to contain significant amounts of hexavalent chromium. Pre-treatment processes such as drying, crushing and screening also produces chromium emissions, but mainly as trivalent chromium. The smelting of chromium is the major source of chromium emissions - open furnaces have the highest uncontrolled chromium emissions, followed by semi-closed and closed furnaces, respectively. Based on the current knowledge on emission rates, interim emission factors for particulate, total chromium and hexavalent chromium releases are provided. Ambient sampling and analytical methods to determine environmental exposure of the general public require that hexavalent chromium needs to be quantified in very low concentrations. Suggested sampling and analytical methods for both source characterisation and ambient monitoring are provided. The selection between dispersion models needs to be based on the size of the modelling domain and the complexity of the terrain. The discussion on dispersion models includes the US EPA?s Industrial Source Complex Model (Version 3), the AERMET/AERMOD suite of models and the CALMET/CALPUFF suite of models. Guidelines are also proposed for environmental exposure assessments including cancer and non-cancer health effects.

Jan 1, 2004

By F. T. Cawood

This paper focuses on the role of the coal mine surveyor at the start of the 21st century. It demonstrates that surveyors must look beyond their legal appointment and pursue opportunities to add value at an operational or corporate level of the company. It also exposes the shortfall of statutory appointments in defining the surveyor?s role in terms of key business drivers of the company. One such an opportunity is the potential role of the surveyor in mineral accounting and quality assurance to meet mine requirements, market specifications and standards pertaining to corporate governance and reporting. Finally, some thoughts are expressed on what can be done to elevate current practice to best practice and how to achieve this goal

Jan 1, 2007

By M. Yavuz

Two different methods of fuzzy multiple criteria decision making have been proposed to solve the problem of mining method selection in the paper titled ?Mining method selection by multiple criteria decision making tool, by Bitarafan and Ataei. This problem is really important and also difficult to solve because of the need of handling many criteria simultaneously in the process of decision making. Bitarafan and Ataei have selected 15 criteria for the case study in their paper and those criteria have not been clustered/grouped yet. The number of selected criteria is only 15, although there are more criteria that should be handled in a real case, because they have used Saaty?s method in the section ?Fuzzy multiple attribute decision making? in their paper. Saaty?s method considers the pair wise comparison of criteria and uses random indexed which have already been derived and published. Available random indexes, however, have been derived for maximum 15 criteria so far.

Jan 1, 2007