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By S. M. Bradshaw

The principles of microwave heating are discussed with reference to dielectric properties, heating phenomena and microwave equipment. Microwave regeneration of granular activated carbon for the carbon-in-pulp process is examined on a laboratory scale, with special attention being given to highlight the problem areas and specific considerations related to microwave heating. Results indicate that microwave regeneration of carbon with 40% moisture on a wet basis by heating to 650°C with steam addition regenerates the carbon to virgin carbon activity levels but with a higher abrasion resistance. A preliminary economic assessment showed that the capital cost for 120 kg/h microwave unit would be R540 000 with an annual operating cost of R 320/t carbon. These figures yield a return on investment of 12%. The aim of this paper is to provide an introduction to microwave heating and to illustrate its application to the microwave regeneration of granular activated carbon for the carbon-in-pulp (CIP) process.

Jan 1, 1998

By G. Broadbent

It is an honour to be invited as a speaker to this ICCR conference and a pleasure to be with you here in South Africa. I have been asked to talk about the competitiveness of coal versus other energy alternatives. Coal supplies nearly one-quarter of the global primary energy. Its most direct competitors are gas, nuclear and renewables. Oil is predominantly for transport fuels. Fuel oil is competitive with coal when crude is below its long-run average price and has some niche opportunities. But I will confine my comments to nuclear, renewables and particularly natural gas as the most potent current competitive threat to coal. Competitiveness is more than just cost and price; there is environmental acceptability, security or reliability and increasingly image. These factors are more of a spectrum than discrete issues. Dollars and cents remain the key issue for competitiveness but one must recognize the impact of politics in sustainable development and energy security.

Jan 1, 2001

By F. T. Cawood

The new South African Mineral Policy has major implications on the way mineral rent will be collected and shared between the stakeholders in future. Although the policy does not supply details on how this will be done, drastic departures from practices under the previous dispensation require a new approach. For example, there introduction of the ?right to mine? principle implies that the repealed lease consideration concept will be expanded to all minerals. The new policy also makes provision for predetermined standard terms and conditions for all prospecting and mining permissions. It also states that, regardless of whether the mineral rights are state or privately-owned, all prospecting fees and mineral royalties will be determined by state officials after consultation with the registered holder of the mineral rights. This paper proposes a standard mineral royalty formula that complies with the principles mentioned in the White Paper and has been shown to be internationally competitive.

Jan 1, 2001

By J. L. van Niekerk

The proposed Gautrain Rapid Rail Link (GRRL) will require approximately 15 km of double or twin high-speed rail track tunnels located for the greater part beneath the northern suburbs of Johannesburg, including Houghton, Rosebank and Sandton. During the Environmental Impact Assessment (EIA) it became clear that potential surface vibration above and in the vicinity of the tunnels was a matter of serious concern to the residents of the affected properties and that the impact required assessment. The general method proposed is based on a US Department of Transportation, 1998, publication in which abase vibration curve derived for typical high-speed passenger trains is adjusted for the topological, geological and other features to predict the surface vibration and the associated ground-borne noise. The predictions indicate that some isolated areas might be impacted but that the impact will likely be limited, and it is possible to mitigate the impact using suitable track construction methods and track support systems.

Jan 1, 2004

By T. Ramamurthy

ABSTRACT : Rock mass classifications RMR, Q and GSI do not suggest decreasing modulus ratio with the decrease in the quality of rock. These have been linked to joint factor, Jf , for better prediction. An engineering classification is suggested based on strength and modulus applicable to both intact and jointed rocks. ZUSAMMENFASSUNG : Fels Masse Klassifizierungen RMR, schlägt Q und GSI daß das Abnehmen von modulus Verhältnis mit der Abnahme in der Qualität des Felsen nicht vor. Diese sind zu gemeinschaftlichem Faktor, Jf, für bessere Voraussage verknüpft worden. Eine technische Klassifizierung wird auf der Basis auf Kraft und modulus vorgeschlagen die zutreffend sind zu beiden unversehrten und jointed Felsen. RESUME: RMR de classifications de masse de Rocher, Q et GSI ne suggèrent pas la proportion de modulus décroissante avec la diminution dans la qualité de rocher. Ceux-ci ont été reliés au facteur de jointure, Jf, pour mieux la prédiction. Une classification construisant est suggérée basé sur la force et modulus applicables intacts et les rochers de jointed.

Jan 1, 2003

By H. Ozturk

In this paper, the computer program ‘SHAFT’ developed for estimation of support requirements for circular mine shafts is introduced. Theory of support design is based on the analytical solutions of circular excavations under non-hydrostatic loading (Detourney and St. John1), and Lame’s thick-wall cylinder theory (Timoshenko6). For rock mass strength property determination Hoek-Brown failure criterion (Hoek et al.2) is used. Mainly two types of support, concrete and steel are taken into consideration as a support member. Program is written in Quick Basic language. Input parameters of the program are shaft radius, number of zones having the same properties along the shaft depth, and depth, unit weight, horizontal to vertical stress ratio, GSI, and uniaxial compressive strength of intact rock of each zone, and compressive strength and safety factor of support member. Output of the program is the graphical representation of shaft with the required support member and thickness throughout the depth of the shaft.

Jan 1, 2003

ADVANCES IN EXTRACTION METALLURGY AND REFINING A symposium organised by the Institution of Mining and Metallurgy will be held in London from 4th to 6th October, 1971. Particulars can be obtained from: The Secretary, Institution of Mining and Metallurgy, 44 Portland Place, London WIN 4BR, ENGLAND. ICAMC -71 - HUNGARY The Third International Conference on Automatic Control of Mines and Collieries will be held at Balantsfured, Hungary from 27th to 30th September, 1971. Further particulars can be obtained from: ICAMC - 71, Budapest 3, P.O. Box 115, HUNGARY. AUSTRALIAN INSTITUTE OF MINING AND METALLURGY Illawarra Branch A symposium on "Blast Furnace Injection" is to be held at Wollongong University College from 15th to 17th February, 1972. About 20 papers on various aspects of blast furnace injection will be presented, including two on nonferrous furnaces. Further particulars may be obtained from: N. Standish, Chairman, Symposium Committee, Wollongong University, Australia 2600.

By D. F. Malan

This paper describes the development and implementation of amine-wide continuous stability monitoring system at the Declines Section, Anglo Platinum Union JV. The Declines Section at Union JV experienced a number of large panel collapses during 2005 and 2006. As well as posing a major safety risk, the panel collapses had a major effect on production since the Declines Section is a semi-mechanized operation. The collapses would often extend into the mechanized strike roadways, resulting in a loss of access to both current and future production faces. The collapses have been largely overcome owing to a change in support design and the implementation of a mine-wide stability monitoring programme. This paper describes the precursors to collapses, which were identified using continuous closure measurements and the remedial measures taken. It also outlines the design and introduction of a robust and reliable monitoring tool, which is now used on a mine-wide basis to provide early warning of large-scale collapses.

Jan 1, 2010

Book review Proceedings of the Symposium on Mining Methods. London, Institution of Mining and Metallurgy, 1974. 160 pp. The Symposium was held from 30th October to 1st November, 1974, and the papers include an interesting range of subjects in coal-mining operations, covering the improvements achieved to date, current practice, and required development for the future. Salamon, M.D.G., and Oravecz, K. 1. Rock Mechanics in Coal Mining. 119 pp. NIM reports Report no. 1822 Stability constants and linear free-energy relations for the platimtm-group metals. (22nd Oct., 1976). Report no. 1852 A revised method for the dissolution of platiniferous materials by the sealed-tube technique. (18th Oct., 1976). Report no. 1828 y-picoline adducts of the nickel, copper, and zinc chelates of 2-thenoyltrifluoroacetone. (26th Nov., 1976) Report no. 1847 A pilot-plant investigation of a kinetic model for flotation.(19th Nov., 1976)

Jan 2, 1977

By R. Meyjes, P. Davies

Keywords: Pyrometallurgy, furnace, smelter, engineering company Metix is a private smelter engineering company wholly owned by its management. Its main lines of business in the ferro-alloy industry being: - turnkey smelter projects (LSTK) - engineering, project, and construction management projects (EPCM) - specialised furnace equipment comprising: ? complete electrode columns, including forged copper pressure rings and contact shoes, as well as fail-safe slipping devices ? water-cooled roofs ? bus-tube systems ? feed systems ? cooling systems ? linings ? off-gas systems ? tap-hole drills & clay guns - furnace power supply systems - ore agglomeration & sinter plants - feasibility studies & due diligence reports - technical consulting for investment banks - project procurement & cost control Metix management experience includes around 130 combined years of contacts and experience in the South African smelter industries. Over 30 furnaces have been built, for processes including FeCr (high, medium, and low carbon), FeSi, FeMn (high and medium carbon), SiMn (ultra low carbon), Si metal, and FeV.

Jan 1, 2006

By V. J. Moore

Introduction Although months have passed since APCOM 87, held from 19th to 23rd September, 1987, the vivid memories of all aspects of its activities remain as clear in one's mind as if it all happened only yesterday. The Symposium, which was held at the Johannesburg Sun Hotel, was organized by The South African Institute of Mining and Metallurgy in collaboration with the Council for Mineral Technology (Mintek), supported by The Geostatistical Association of South Africa, The Operations Research Society of South Africa, and the Computer Society of South Africa, and was backed financially by the Chamber of Mines of South Africa. The total number of registrants amounted to 375 delegates and 50 affiliates: 100 of the delegates were from outside the Republic of South Africa and represented 15 countries, namely Australia, Brazil, Canada, Chile, France, Great Britain, Greece, Italy, Namibia, Phillipines, Sweden, Turkey, United States of America, West Germany, and Zimbabwe.

Jan 1, 1988

By D. G. Krige

The scope and salient features of a general risk-analysis model for the main types of new mining ventures are covered in brief outline. The following special features and their effects on the investment criteria are discussed: - various criteria for viability, - the maximum shortfall of funds, - correlations between the grades of up to five ore constituents and between the corresponding product prices. differential inflation and escalation rates for costs and prices, - the estimation, if relevant, of a pay limit based either on the major product only, or on the two major products jointly, - the likely recovery grades of all the products to be obtained when the ore-body is mined to any such pay limit. - an option to take account of the effect on the pay limit of any negative taxation on marginal ore, - investment analyses in current and real terms for individual groups of investors subscribing for equity and any loan capital on differential terms.

Jan 1, 1979

By M. J. Gouws, T. P. Knoetze

The spontaneous combustion of coal and the explosion of coal dust are two phenomena that were identified by the South African mining industry as requiring investigation. Research contracts were awarded to the G.P. Badenhorst Research Facility of the CSIR and the Department of Mining Engineering of the university of the Witwatersrand by the now defunct National Energy Council. Both projects entailed tests on numerous coal samples in specially designed apparatus. Since the completion of the project, attempts have been made to predict experimental results without incurring the cost of performing experiments. This paper describes predictive indices, based on routine laboratory tests, that were developed by the different research teams for their particular projects. A comparison of the results obtained by applying the spontaneous combustion liability index and the explosibility index to common coal samples indicates that, in general, propensity to spontaneous combustion and explosibility exhibit an inverse relationship. A brief overview is given of some major South African coal-mine disasters.

Jan 1, 1995

1. Book review Steels- microstructure and properties, by R. W. K. Honeycombe. London, Edward Arnold, 1981. 244 pp. Rl9,90. (Reviewer: P. T. Wedepohl) 2. New books Decision making in continuous steel casting, by Mark A. Vonderembse. New York, Bowker Publishing Co., 1981. U8 pp. Handbook on continuous casting, by E. Herrmann' Diisseldorf, Aluminium-Verlag GmbH, 1980. 742 pp. Cloth DM 1250, leather DM 1500. Pore structure analysis from a nitrogen adsorption study of porous materials using a volumetric method. User's guide to the FORTRAN programs: PORESl and PORES2, by E. G. K. Woods. Pretoria, CERGCSIR (P.O. Box 395, Pretoria 0001), May 1981. Oil and gas from coal, by Dick Olliver. London, Financial Times (10 Cannon Street, London EC4P 4BY), 1980. £120. The seventies: a review, the eighties, a preview, by W. Hibbard (editor). Oxford, Pergamon, 1981. 120 pp. £12.50. Computers in materials technology, by T. Ericsson editor). Oxford, Pergamon, 1981. 230 pp. £14.50.

Jan 1, 1981

By J. Svoboda, W. J. C. Venter, R. N. Guest

SYNOPSIS Wet high-intensity magnetic separation was examined as a method for the recovery of copper and lead from Tsumeb flotation tailings. Bench-scale and pilot-plant tests were conducted and, despite the very low magnetic susceptibilities of all the complex copper and lead minerals, copper and lead recoveries of over 60 per cent and almost 50 per cent respectively were obtained at a combined copper and lead grade of up to 13,5 per cent. The recoveries were found to be practically independent of magnetic induction in the range 0,5 to 2,2 T, and the grade of the magnetic concentrate decreased with increasing magnetic induction. The grade of the magnetic concen¬trate improved when the flowrate of the slurry was increased, and desliming was found to have a profound effect on the. metallurgical process. Particles smaller than 10 µm were not recovered, and their presence in inefficiently deslimed samples impaired the overall performance of the magnetic separation

Jan 1, 1988

By M. W. Grodner, J. Maaren, G. Guler, J. K. Schweitzer

The selection of the most suitable mechanized mining strategy has to consider the geotechnical environment in which it will be operating. A mechanized mining method or machine is designed to a given set of specifications to work within an environment. The geological conditions that define this environment are fixed—detailed information of these conditions for design specifications is thus critical. Two major classes of geotechnical parameters are defined—critical and design. The critical controlling factors are a result of mineral composition, size, shape, abundance, assemblage and associated texture, as well as discontinuity type and orientation. Design parameters are specific to each deposit, and their nature cannot be broadly described, as with the critical factors. It is shown that for major deposits in South Africa, namely the Witwatersrand Basin (gold), the Bushveld Igneous Complex (PGEs) and the Karoo Coalfields that by incorporating geological and geotechnical information that appropriate mechanized mining methods can be deduced, and that the performance and design parameters of specific technologies can be determined

Sep 1, 2001

By J. Kitagawa

The principal objectives of a metallurgical test programme for a 'grass roots' mining project are twofold. The first requirement is to establish the metallurgical viability of the project by demonstrating that acceptable results can be obtained by processing of the ore. The second goal is to obtain essential supporting data to determine whether the project is economically feasible. This involves several functions, which include the establishment of a workable flowsheet, the obtaining of design criteria for the commercial plant, and the collection of the evidence necessary to convince management, and often a third-party expert, that the metallurgy predicted for the ore can be achieved in a full-scale operation. The latter task is facilitated if a coherent overall picture is presented considering the geology of the orebody, the mining plan, and the mineralogy and metallurgy of the ore. The purpose of this paper is to provide guidance in the establishment of a test programme to meet the above objectives.

Jan 1, 1978

By W. A. Lenhardt

During the past five years, several research projects on the causes of mining induced seismicity have been carried out by the Rockburst Research Department at Western Deep levels Limited. This paper summarizes the results of these investigations. Several types of mining-induced seismic events are addressed, and models of their mechanisms are presented. It is shown that most of the seismicity results from mining in geologically disturbed areas, and ways and means are discussed to reduce the seismic potential. Stabilizing pillars, for instance, have been introduced to reduce stresses at the stope face and to alleviate the facebursting problem. Facebursts still occur in areas of very low stresses, and pillars became the source of very large seismic events (M >3). At this stage, the understanding gained of pillar-associated events allows a review of current mining practices. Further, it makes possible an examination of the efficiency of measures to alleviate the effects of various seismically prone situations.

Jan 1, 1992

A method is proposed for the evaluation of the influence of grout prestressing systems on the support resistance offered by timber packs. It is shown that, in order not to reduce the load-carrying capacity of timber packs, grout prestressing systems need to be at least as stiff as a single timber rise. The method was used to establish strength specifications for the grout prestressing systems to be used under non-seismic and seismic conditions. For non-seismic requirements, the 24-hour grout strength needs to be at least 1,7 MPa, and the 7-day grout strength 4,9 MPa. The investigation showed that the proposed strength specification is realistic in the light of current grout-strength capabilities. For seismic requirements, the grout strength needs to be at least 4 MPa and 8 MPa to prevent extensive damage to the grout during seismic events with a peak velocity of 1m/s 3 m/s respectively.

Jan 1, 1996

By M. H. Moys

Accurate models of mill power are becoming more necessary as the design, operational, and control requirements for grinding mills become more stringent. Models of mill power are reviewed briefly, and a new semi-phenomenological model is derived. The conventional torque-arm model for mill power is combined with a model of the tendency of the load in a mill to centrifuge at high speeds, to describe mill power that can be related to several design variables (such as mil geometry, mill speed, and liner design) and control variables (such as load volume, slurry rheology, and mill speed in the case of variable-speed milling). The semiphenomenological nature of the model allows rational conclusions to be reached concerning the effect of various aspects of mill-load behaviour on mill power. The model is shown to be capable of describing reality with much greater accuracy than is achieved by empirical models such as the Bond model.

Jan 1, 1993