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By O. L. Papendorf

The method presented in this paper can be used, instead of lengthy cash-flow determinations, for the calculation of present values in the face of physical growth and inflation.

Jan 1, 1981

By H. D. Mtegha

The Southern African Development Community (SADC) aims to harmonize mineral policies and regulatory regimes in the minerals sector. This paper provides a review of the progress made towards harmonization of mineral regimes in the region. It singles out only the mining fiscal environment, as this is normally one of the key issues of interest to potential investors as well as the host state. Indications are that the region is slowly progressing towards a more harmonized approach, and there is evidence that the ?race to the bottom? has been prevented, which is the basis for an integrated mineral sector that the region aspires to.

Jan 1, 2011

A theory is presented providing a concise mathematical description of the performance of a percussive rockdrill in terms of its principal mechanical dimensions. The theory defines the relationships between the values of thrust required to produce optimum rates of penetration at different throttle air pressures in terms of the piston areas and derives an equation for the prediction of these rates. An analysis of drillsteel life and bit wear is also made.

By A. V. Z. Brink, D. M. O’Connor

Recent research into the prediction of mining-induced seismic events by the monitoring of small microseismic events at Western Deep levels Gold Mine is described. Measurement and interpretation techniques and results are presented. It was found that the occurrence of the larger events near longwall faces on the Carbon leader reef is preceded for some hours by an increased rate of microseismic emission and spatial concentration of the microseismic events in the zone of eventual failure. The research is currently being expanded with the aim of producing a practical rockburst early-warning system.

Jan 1, 1983

By R. T. White, A. Higginson, M. Phil

Samples of water that had been collected underground from eight gold mines in South Africa were subjected comprehensive analysis of the quality of the waters, and their corrosivity on mild steel was measured by the laboratory techniques of extrapolation from Tafel plots and of polarization resistance. The results indicate that, if such factors as pH, Langelier index, and degree of aeration are beyond certain specified limits, the corrosivity ofthe water is affected. The applicability of the corrosivity index in predictions ofthe degree corrosion is questioned. Suggestions are included for future work involving the fundamental characterization of the corrosivity of mine waters.

Jan 1, 1983

By N. Thorp, S. J. Bluhm

It has long been recognized that the provision of an acceptable thermal environment minimizes the danger and the adverse effect of heat stress, which is directly linked to decreased productivity, increased accident rates, and excessive physiological strain in workmen. Refrigeration in one form or another helps to provide this acceptable thermal environment. This paper outlines the problems encountered in a working area, and the steps taken to alleviate environmental conditions in some stopes with the introduction of selective cooling employing small water-chilling units in conjunction with specially designed stope coolers. Performance figures are given for plant and stope coolers, and the effectiveness of the system is assessed from an evaluation of the improvement achieved in the environmental conditions.

Jan 1, 1986

By B. Z. Weiss, N. R. Comins, F. Blum

Some aspects of the mechanical behaviour of chromium-containing dual-phase 3CR12 steel were investigated as a function of the temperature and strain rate. The yield stress was found to depend on both the temperature and the strain rate, with no substantial differences between the longitudinal and the transverse directions. The strain-rate sensitivity decreased with increasing temperature. The yield stress could be presented as a function of a temperature-strain-rate parameter. Impact test results showed substantial differences between the energy absorption of the transverse and longitudinal specimens above the ductile-brittle transition temperature. Changes in energy absorption with temperature were gradual for specimens in both orientations, and the transition from ductile to brittle behaviour occurred between 373 and 173 K. Strain rates ahead of the tip of notches with different geometries were calculated and measured experimentally.

Jan 1, 1990

By C. Musingwini, M. Woodhall

An often overlooked factor in the analysis of mine layouts and schedules is technical operating flexibility, mainly due to its nebulous nature. If one glosses over technical operating flexibility the resultant mine layouts and schedules tend to be sub-optimal. The need to incorporate technical operating flexibility into the analysis and comparison of mine layouts and schedules is increasing in importance. This paper illustrates the nature of technical operating flexibility, reviews previous work on valuing operating flexibility and proposes how technical operating flexibility can be quantified for tabular reef mines by using a platinum reef deposit as a case study. Once technical operating flexibility is quantified it becomes possible to explore its incorporation into the analysis of mine layouts and schedules and subsequent optimization processes. The work described in this paper is part of a current PhD study at the University of the Witwatersrand. Keywords: mine plans, layouts, schedules, technical operating flexibility, ore availability.

By B. Z. Weiss, N. R. Comins, F. Blum

The effect of microstructure on the deformation and fracture properties of 3CR12 steel was investigated at different strain rates in the temperature range -196 to 200°C. The yield stress of the as-received steel, showing a banded dual-phase microstructure, was much lower than that of the flake-like dual-phase microstructure produced by heat treatment. The heat treatment also resulted in an increase in the volume fraction of martensite. The fracture toughness of the as-received 3CR12, on the other hand, was significantly higher than that of the heat-treated material. These changes in both yield stress and fracture toughness were attributed to the effect of microstructural parameters on the constraints imposed on the deformation and subsequent failure of the ferritic phase in the as received and heat-treated steels. The exceptionally low resistance to crack extension in a plane parallel to the roiling plane of the as-received material was ascribed to the delamination process, which is typical for controlled-rolled steels. The yield stress and fracture toughness were found to depend on temperature and strain rate. The appearances of the fracture surfaces were found to be consistent with the mechanical properties.

Jan 1, 1992

By J. M. Stewart

Mining fatality rates in many countries have not changed substantially over the past ten years. This demonstrates not only that there is an inherent risk in mining, but also that current approaches to improving safety need to be rethought. An analysis of productivity and fatality data in the United States, United Kingdom, and South 4frican coalmining industries shows that the impact of legislation on safety is overlain by other significant factors. Although improvements in safety and productivity usually occur together, the data warn that safety legislation can sometimes cause a significant reduction in productivity. Based on the data and experience considered, it is concluded that legislation should be aimed at creating a framework within which a positive attitude towards the implementation of more productive and safer mining methods, work practices, and technology can flourish, rather than attempting to enforce excessively prescriptive provisions. This later approach is even more problematic when safety standards and legislation are transferee from well developed to less developed countries. A legislative framework in which the mine manager is required to take al reasonably practicable measures to procure safe working conditions in accordance with mine-specific codes of practice is outlined. Within that framework, the value of adopting widely accepted standards is recognized. A performance-based external audit arrangement is outlined as a basis for ensuring that detailed attention is focused on those areas most needing improvement.

Jan 1, 1995

SYMPOSIUM ON THE RECOVERY OF PYRITE The proceedings of the Symposium on the Recovery of Pyrite, held in Johannesburg in June 1969, may be ordered from the Secretary, S.A.I.M.M., P.O. Box 61019, Marshalltown, Transvaal, at the reduced price of R5.00. Papers and addresses presented at the Symposium were: Opening Address by Mr J. K. E. Douglas (President). "The world sulphur position," by W. C. J. van Rensburg (Member). "The South African sulphur position," by D. L. Taylor (Member). "The recovery of pyrite at Government Gold Mining Areas Limited," by R. J. Westwood (Member), G. S. Stander (Affiliate) and H. P. Carlisle (Member). "Recovery of pyrite concentrates from colliery-waste discards-A preliminary assessment," by W. A. Gilbert (Visitor) and E. A. Nugent (Member). "The role of pyrite in upgrading the uranium content of Witwatersrand conglomerate ores by means of the heavy-medium separation process," by D. J. Tutt (Associate Member). "Pyrite recovery by jigs at Durban Roodepoort Deep Limited," by E. J. Dominy (Affiliate), F. Diamond (Affiliate) and A. D. Graham (Affiliate). "The storage of pyrite concentrates," by Joan C. Campkin (Visitor) and P. J. Lloyd (Member). "The flotation plants of the Anglo-Transvaal Group," by L. A. Bushell (Member). "Pyrite flotation with amines and cyanidation of the products," by E. H. D. Carman (Member). "Gold recovery by cyanidation from mill products obtained after pyrite flotation," by P. G. Mrkusic (Graduate), M. Sciarone (Visitor) and H. E. Simonsen (Visitor). "The influence of sulphydryl and cationic flotation reagents on cyanidation of native gold," by K. G. Ashurst (Visitor) and W. P. Finkelstein (Member). "Laboratory tests on the flotation of pyrite from Witwatersrand gold ores by cationic collector," by J. Levin (Member), and M. L. Veitch (Visitor). Closing Address, by Dr R. E. Robinson (Director, National Institute for Metallurgy). INCOME TAX: POST-GRADUATE STUDY COURSE CONCESSION As a result of representations made by the Associated Scientific and Technical Societies of S.A. and the Suid-Afrikaanse Akademie vir Wetenskap en Kuns, engineers and scientists will now be allowed to deduct expenses incurred on post-graduate study courses from their taxable income. The conditions of this concession are set out in section 16 of the Income Tax Act, 1969, which reads as follows: 16. (1) The following section is hereby substituted for section 16 of the principal Act: 16. "Notwithstanding the provisions of section 23(a) and (b), there shall be allowed to be deducted from the income of any person who is a dentist or medical practitioner or practises any profession referred to in paragraph (a), so much as the Secretary may allow of any expenditure incurred by such person in the circumstances contemplated in paragraph (c), if the Dental Association of South Africa in the case of a dentist, or the Medical Association of South Africa in the case of a medical practitioner, or the "Suid-Afrikaanse Akademie vir Wetenskap en Kuns" or the Associated Scientific and Technical Societies of South Africa in any other case, certifies in such form as the Secretary may prescribe that such person- (a) if he is not a dentist or medical practitioner, is the holder of a degree in engineering or allied technology or natural sciences awarded by a recognized university on completion of a prescribed minimum period of study of not less than four academic years or the equivalent thereof and enabling the holder thereof to practise the profession of an engineer or a profession for which advanced and specialised scientific knowledge is required which relates directly to- (i) the development or exploitation of natural resources; (ii) mining or prospecting for minerals; (iii) the production of pastoral, agricultural or forest produce ; (iv) the breeding or care of farm animals; (v) any industrial process; or (vi) the training of specialists in any branch of science or technology connected with any aforementioned profession; (b) has practised his profession for not less than three years; and (c) has incurred such expenditure during the year of assessment in respect of the attendance by him of any postgraduate study course approved by such body to improve his qualifications for carrying on his profession in the Republic". (2) The amendments effected by subsection (1) shall first take effect in respect of assessments for the year of assessment ending on the twenty-eighth day of February, 1970. From this section it is clear that the concession will only be granted if the application is accompanied by a certificate, which certificate must be either signed by the Chairman of Die Akademie or the President of the Associated Societies. In terms of the authority granted such certificates must certify that: (i) the taxpayer concerned has practised his profession for not less than three years; (ii) the expenditure was incurred by the taxpayer during the year of assessment indicated in the certificate; (iii) the expenditure was incurred by the taxpayer in respect of the attendance by him of a post-graduate study course approved by the Associated Scientific and Technical Societies of South Africa or Die Suid-Afrikaanse Akademie vir Wetenskap en Kuns, as the case may be, to improve his qualifications for carrying on his profession in South Africa; (iv) the taxpayer is the holder of a degree in engineering or allied technology or natural sciences, which degree was awarded by a recognized university,

By H. J. de Klerk

The metallurgical phenomena in the design and manufacture of high-strength low-alloy (HSLA) steels are reviewed, and some aspects of the production of Supraform TM (thermo-mechanically processed) steel are discussed. . The weldability of Supraform TM is related to changes in the microstructure of its heat-affected zone.

Jan 1, 1984

By D. L. B. Pollnow

Tinplate, and electrolytic tinning at the Iscor works, Vanderbijlpark by D. L. B. POLLNOW, B.Sc. (Chem.), M.Sc. (Met.), D.Se. (France) The paper first describes tinplate as a product, dealing with its structure and its advantages to the packaging industry. It then describes Iscor's electrolytic tinning line, which is one of the largest Halogen units in the world. Details are given of the process and of the equipment used.

Jan 1, 1977

By J. Dvorácek

Mine water poses a significant problem in lignite coal mining. The drainage of mine water is the fundamental prerequisite of mining operations. Under the legislation of the Czech Republic, mine water that discharges into surface watercourse is subject to the permission of the state administration body in the water management sector. The permission also stipulates the limits for mine water pollution. Therefore, mine water has to be purified prior to discharge. Although all mining companies operate mine water treatment plants, there is hardly any utilization of the final effluent. The high expenditure involved in the more sophisticated methods of mine water treatment has fuelled the search for the commercial utilization of the effluent.

Jan 1, 2012

By H. A. D. Kirsten

The effects of the mining of deep-level tabular reefs are usually evaluated by use of continuum, elastic mining simulation analyses. This paper gives the results obtained from a series of analyses in which stopes of limited span are considered to be excavated in a non-linearly non-elastic, jointed and fractured rockmass. In particular, the theoretical influence of soft backfill in these conditions is evaluated. It is shown that the stress distribution and behaviour of the rockmass, alternately taken as an intact-elastic and as a fractured non-elastic medium, are completely different. The relevance of the energy-release rate commonly calculated in mining-simulation analyses, and the efficacy of its correlation with seismicity and the associated rockbursts, are reviewed. In deep-level mining operations, it is not practically feasible to obviate releases of seismic energy. The fact of their occurrence should therefore be accepted and, rather than considering the reduction of energy release as the primary objective, efforts should be concentrated on minimizing the effects of such release. Analytical results are given to demonstrate that this approach is not only correct, but also the only feasible solution to the rockburst-seismicity problem in deep mines.

Jan 1, 1989

By C. Dechert, J. Norwood

Compañia Minera Antamina, Peru has recently completed a fifth year of operation of their 301-km concentrate pipeline. The pipeline was commissioned by PSI in May of 2001. The Antamina pipeline is generally accepted as one of the most complex slurry pipeline operations worldwide. The pipeline transports an average of 1.6 million tonnes of copper and zinc concentrates from the Yanacancha mine site at an elevation of 4 155 metres above sea level (masl) to the port of Huarmey at an elevation of 62 masl. Currently ten different types of concentrates are being transported as separate batches. The pipeline traverses oneof the most rugged areas in the world. It utilizes three different pipe diameters, and four remote valve stations to optimize the hydraulic design. PSI has recently completed an overall operational audi tof the Antamina pipeline. This paper evaluates the operational effectiveness of specific design features and operating philosophies, implemented during the engineering phase, over the last five years of operation.

Jan 1, 2007

By Allan Jansen, Robin Bissett

[Power-Point Presentation]

Jan 1, 2005

By G. J. McDougall

After defining activated carbon, the author describes its structure and outlines the physical characteristics distinguishing one type of activated carbon from another. The adsorptive properties of these carbons, the raw materials used, and the manufacturing processes-chemical activation, and physical or thermal activation-are outlined. The high-temperature thermal route (which is the most important for the products employed in gold recovery) using coconut shells or coal as the raw material is then discussed In some detail.

Jan 1, 1991

By C. J. Fauconnier

The various methods of detecting fires and heatings in collieries are reviewed. The methods described range from those relying principally on human senses to sophisticated methods employing infrared technology to detect traces of the products of oxidation and combustion. The advantages and disadvantages of various gases employed as indicator gases for the early detection of heatings and fires are discussed, and recommendations are made in this regard. The operation of a modern infrared carbon monoxide detection system is described, and the differences in operation and application of telemetric systems, tube-bundle systems, and up cast-shaft monitors are discussed In conclusion, some indication is given of the capital outlay required for typical early-detection systems.

Jan 1, 1981

By T. P. Katakwa

The utilization of software is now inherent to virtually every activity along the mining value chain. However, apart from the software survey done by Gibbs in the 1990s and work on the extent of diffusion of information and communication technology (ICT) in the South African platinum sector by Mugodi and Fleming in 2003, the nature and extent of software utilization in the South African mining industry has never been evaluated. The Mine Planning, Optimisation and Valuation (MPOV) Research Group in the School of Mining Engineering, University of Witwatersrand, therefore initiated a project to collate and analyse the current utilization of software in the South African mining industry. This was done through the development of a web-based database of the relevant software. Snowball sampling was used to collect the data because the South African mining industry is diverse and software utilization is fragmented across and within the sectors of the industry. The data was then organized into distinct categories so that the information from a variety of sources could be evaluated on the same basis. A beta version of the database can be accessed online through a user-friendly front-end platform at http://db.mining.wits.ac.za. The database is expected to help at least 13 educational institutions with decisions on facilities and training that are vital to the education of mining and mining-related professionals. Exploration, mining, and consulting companies will also benefit from information in the database relating to availability and useful combinations of software solutions. The database is also strategic to software providers by providing a better understanding of their respective relative market share along the mining value chain. An analysis of the data collated in this research shows that about 77% of the software users are mining companies, 17% are consulting companies, 3% are mineral exploration companies, and the rest are software providers and educational institutions. The software used in the South African mining industry is largely provided by Gemcom Software International, MineRP Solutions, and MRM Mining Services. CAE Mining, who in 2010 acquired the Datamine Group providing Datamine software, is also widely acknowledged as a major software supplier in South Africa, but data from them had not been obtained at the time of producing the beta version of the database due to proprietary constraints. The work reported in this paper is part of an MSc research study in the School of Mining Engineering at the University of the Witwatersrand. Keywords mine planning, mining, value chain, software, database, South African mining industry, utilization.

Jun 1, 2013