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Darwin Conference, 1984. Parkville (Australia), The Australasian Institute of Mining and Metallurgy, 1984. $AI5,00 (surface mail). Reviewer: H.A. Simonsen The theme of the Darwin Conference was 'The Mineral Potential of Northern Australia and Changing Concepts of Development', and the fifty papers that were presented commemorate the 'coming of age' of the Northern Territory of Australia. Rockbursts and seismicity in mines, edited by N.c. Gay and E.H. Wainwright. Johannesburg, The South African Institute of Mining and Metallurgy, Symposium Series no. 6, 1984.363 pp. R75,OOexcl. GST, £50, OS$65. Reviewer: E. T. Brown Black sands, by lan Morley. St Lucia (Australia), University of Queensland Press, 1981. Reviewer: P.W.J. van Rensburg Gravity concentration technology, by R.O. Burt assisted by Chris Mills. London, Elsevier Science Publishers, 1984. Volume 5 in the series Developments in Mineral Processing. Reviewer: D.A. Viljoen

Jan 1, 1985

By R. Kok, N. B. Strydom, P. L. Jooste, W. H. Van Der Walt

Intermittent exposures to heat, and the retention of heat acclimatization by N. B. STRYDOM, M.Sc., Ph.D. (Illinois) (Fellow), R. KOK, M.Sc. (Potch.) (Visitor), P. L. jOOSTE, M.Sc. (Stell.) (Visitor), and W. H. VAN DER WALT, B.Sc. (Potch.) (Visitor) Twenty-one heat acclimatized subjects were assessed for the degree of acclimatization attained with respect to heart rate, rectal temperature, and sweat rate during a standard four-hour heat-stress test. Thereafter, they were put on light duties in cool environm ents for four weeks, except for four hours of exposure to heat every seventh day. Their state of heat acclimatization was again assessed two days after the final week's exposure. Although heart rates and body temperatures showed significant increases over the initial values, no differences were observed in sweat rates and, in general, the subjects were rated as still adequately acclimatized to heat.

Jan 7, 1975

By D. F. Malan

This study Investigates transient closure piles of tabular excavations. Measured closure profiles in stopes indicate that time-dependent acts f the rockmass can be very prominent but such effects have been largely neglected in past analyses and modelling. This was due to a poor understanding of the time-dependent mechanisms controlling closure rates This paper investigates the feas-ibility of representing the rockmass as a visco-elastic medium. Currently, no analytical solution for the viscoelastic convergence of a tabular stope is available in the literature. Therefore, the author derived a solution using the correspondence principle and a known elastic solution. It is assumed that the rockmass behaves elastically in hydrostatic compression and as a Kelvin substance in distortion A parametric study is Included to aid in the calibration of the model parameters, together with a discussion on the correct calibration of these parameters from experimental data.

Jan 1, 1995

By H. A. D. Kirsten

The professions are subject to a wide range of changing conditions, and are as a result forced to become more competitive. Although there is a need for specialization under these circumstances, no formal recognition, definition, or control of specialists exists. Some of the professions have attempted, over extensive periods of time, to resolve the issues involved, and have met with varying degrees of success. It appeared from the replies to a questionnaire sent to over one-hundred-and- .fifty professionals, that both advanced education and experiential training, are considered to be necessary qualifications for specialization. The opinion as to whether it should be lift to the individual to cal himself a specialist, or whether recognition should be based on peer review, was divided The majority did not want the number of specialists to be controlled The response to the reservation of work for specialists was ambivalent.

Jan 1, 1995

By A. Marek

Reduced downtime and maximized availability of mining machines are the key factors in optimizing production rates. As technology moves industry towards an age of ?intelligent machines? it sets the foundation for change in mining equipment design, functionality, and maintenance. Recent mining machine designs are integrating more and more electronic components into the core functionality of individual piece of equipment due to regulatory and legislative requirements, such as TIER rating, as well as from a safety aspect such as personal detection systems. This paper describes the use of existing on-board electronic equipment to increase machine availability through automated maintenance planning and diagnostic fault-finding capability. The automated maintenance planning takes place on the machine itself in order to be independent of the mine?s infrastructure, while the diagnostic capabilities allow for reduced downtime. The paper also presents a concept to transfer operational data to surface to be able to optimize planning of maintenance and to reduce downtime. Case studies are presented where such systems have been commissioned and are currently in operation, the possibilities of this technology application for the future are examined.

Jan 1, 2012

By A. Buncombe

In March 1984, two years' work by senior metallurgical personnel from the six major mining groups culminated in the formation of the Mine Metallurgical Managers' Association of South Africa. This Association has joined a group of specialist Associations operating within the South African mining industry whose aims are to uphold the standards and promote the interests of their various professions.

Jan 1, 1987

By R. Gebrekristos

It is commonly accepted that three types of aquifers exist in the Bushveld Complex: (a) alluvial aquifers in areas of river courses, (b) weathered bedrock aquifer formed by the in-situ weathering of the bedrocks, (c) fractured aquifers underlying the weathered aquifers controlled by the regional and local fracturing of the crystalline rocks. Hydrogeological studies conducted in the Critical Zone of the Bushveld Complex in the western limb show that the UG2 pyroxenite layer is of a particular interest and has a unique aquifer property. It yields much of the groundwater inflow into some mines and can be classified as the most important aquifer in the vicinity of the mining zone. The UG2 pyroxenite aquifer is restricted to the dipping UG2 pyroxenite unit. The unit weathers more intensely than the surrounding norites and anorthosites and is characterized by deeper weathering horizons (two to three times deeper than the surrounding rocks). For much of the UG2 mining area between depths of 35 ? 80 m, stoping of the UG2 takes place approximately 5 ? 7 m below the UG2 pyroxenite aquifer, and usually there is no groundwater inflow into the mine workings. However, unsealed deep exploration boreholes intersecting the UG2 pyroxenite and reaching underground mine workings, or mine roofbolts penetrating the weathered pyroxenite aquifer from underneath, can result in significant groundwater inflows into the underground workings. The reason as to why the UG2 pyroxenite weathers more than the norites and anorthosites has not been fully studied but is suspected to be due to the bedding planes of the unit and mineralogical composition of the particular pyroxenes forming the unit, which result in preferential physical and chemical weathering under atmospheric conditions. The weathered pyroxenes form sand-sized, rounded grains with improved effective porosity and permeability suitable for the storage and passage of groundwater. The orientation of the pyroxenite aquifer can easily be determined as it dips with the Bushveld layered strata. No-flow boundaries can be assumed on the hanging- and footwall of the pyroxenite aquifer and the flow rates can be estimated using 2-dimentional analytical equations. However, this must be confirmed with strong conceptual models since the existence of a fracture network connecting the pyroxenite aquifer with the overlying weathered and/or underling fractured aquifers can complicate the system, lowering the accuracy of analytical models and necessitating the utilization of numerical models.

Jan 1, 2012

Book reviews Natural gas substitutes from coal and oil, by S.A. Qadar. Amsterdam, Elsevier Science Publishers, 1985. U.S.$83.25. Reviewer: U. Grimsehl High heat production (HHP) granites, hydrothermal circulation and ore genesis. London, The Institution of Mining and Metalurgy, 1985. 593 pp. £30. Reviewer: S.A. de Waal 2. Recent publications Uranium recovery from phosphates and phosphoric acid, by S. Huwyler. 3rd edition. Wirenlingen (Switzerland), Swiss Federal Institute of Reactor Research, EIR-Bericht (C) no. 1. Apr. 1985. 56 pp. Geological aspects of mining productivity. Canada's base metal resources, by B.W. MacKenzie. Kingston (Canada), Centre for Resource Studies, Queen's University, Technical Paper no. 6, Aug. 1985. 115 pp. $10.Taxation policies in the Canadian minerals industry, edited by M. Wojciechowski. Kingston (Canada), Centre for Resource Studies, Queen's University, 1985. Mineral policy update 1984: Policy and program changes afecting the Canadian mineral industry, by M.l. Wojciechowski and M.L. McAlister. Kingston (Canada), Centre for Resource Studies, Queen's University, 1985. $12. 3. Mintek reports Report MU7 The selective solvent extraction of pal/adium by the useof di-normal hexyl sulphide. Report M218 Modification of the design of screen boxes for carbonin-pulp and resin-in-pulp plants. Report M225 The commissioning, operation, and maintenance of an on-line corosion-monitoring station for the mining industry. Report M231The determination of selected lanthanoid elements by atomic-absorption spectroscopy using electrothermal atomization. Report M233 A computer programme for the prediction of hydrocyclone performance, parameters, and product size distributions. Report M234 The solvent extraction of base metals by mixtures of carboxylic acids and non-chelating oximes. 6 The efect of particle size and coloid stability on the wet high-intensity magnetic separation of uranium from cyanidation residues. Report M238 The beneficiation of fine coal. Report M240 The spectrophotometric determination of tin in silicates and tungsten-bearing materials. Report M242 Wear and performance of materials in pipelines for the hydraulic conveyance of fused ash. IPMI award for distinguished achievementThe International Precious Metals Institute has announced that Professor Henry C. Taube, Nobel Laureate, wil be the recipient of their 1986 Distinguished Achievement Award. Dr Taube is Professor of Chemistry at Stanford University, Palo Alto, California.

Jan 1, 1986

By Oaitse Medupe

The feed to the BCL concentrator is made of the ore from Phikwe No3 shaft, Selebi shaft and Selebi North shaft. The receiving bin of the concentrator has daily throughput of 7869mt live capacity of ore with feed grade from underground operation of 0.70%Ni, 0.75% Cu and 0.05% Co. The valuable minerals in the ore are Pentlandite, Chalcopyrite. Cobalt is present mainly in the solid solution in pentlandite. The common non-sulphides minerals are Amphibolites, quartz, micas, and Feldspar while pyrite and pyrrhotite are the major gangue sulphides. Pyrrhotite contains between 0.1% and 1% Ni in solid solution. From the mineralogical investigation, it was found that approximately 65% of the pentlandite in the ore occurs as exsolutions in the pyrrhotite and the grain sizes ranges from 8 to 38µm. about 25% of the nickel bearing pentlandite is medium grained and subhedral. This kind of pentlandite occurs along the cracks of pyrrhotite or as inclusions in pyrrhotite. The rest of pentlandite present is disseminated in the gangue matrix. Because of the fine occurrence of pentlandite, fine grinding was conducted in order to improve the recovery as well as the concentrate quality. A series of subsequent flotation test were performed in order to evaluate grinds of 35, 40, 45, 50, 60 and 80% passing 75µm. It was observed that ? The mass pull increased together with increasing fineness of grind ? Similar nickel recoveries were obtained at 35 and 40% passing 75µm but from 50% and 60% the grind was seen to adversely affect the nickel recovery. At 80% passing 75µm the recovery increased by small amount. ? Flotation kinetics showed higher initial nickel recoveries but these did not translate into higher final recoveries. ? Grinding finer than 80% passing 75µm yield very high grades of the concentrate in the first minute of the flotation test, and the grade is dramatically reduced in the fifth minute of the test. It was concluded that the current grind of approximately 48% passing 75µm is close to the optimum and no significant benefit were found to be associated with finer primary grinds. The inconsistence of the grade and recovery as well as the pentlandite losses will be discussed. Keywords: Pentlandite, Nickel losses, Grain size, Flotation

Jan 1, 2007

By S. R. Xie, S. Gong, E. P. Li, S. S. He, Y. J. Sun, S. J. Li

"Based on the complicated geological production conditions and abnormal strata behavior of the fully mechanized caving face No. 102 in the Xinyang Coal Mine, we analyze the breaking and forming process of distinguishing key block structures in close spaced coal seams. This analysis establishes an integrated mechanical model of these distinguishing structures. Furthermore, the horizontal force TAB generated by downward key blocks A and B is quantified, as is the Pressure PG exerted by key block B on caved gangue. Finally, the interaction mechanism is revealed. Analysis of the results using Mathematica reveal the following: 1. Both TAB and PG exhibit approximately inverse relationships to coal pillar width b; 2. TAB exhibits an approximately exponential relationship with mining height M of which the base is greater than 1; 3. PG exhibits an approximately arctangent relationship with mining height M. Combining these results with field observations, we conclude that the area in the vicinity of supports 100#–120# in the upper area of working face No. 102 is the likely zone of abnormal strata behavior. Thus, this area was classified as a key control area. Based on these results, the graded support control technique is proposed. Application of this technique in the field resulted in a reduction in the rate of hydraulic support system malfunction from 47% to 7% in the key control area. In addition, during times of periodic mining pressure, the roof caving height value never exceeded 0.3 m and the maximum spalling depth never exceeded 0.2 m. Overall, the results indicate that this new technique has markedly increased the stability of surrounding support rock material. IntroductionClose-spaced coal seams are widely distributed in China, and mining proceeds from the uppermost to the lowermost seam (Zhang et al., 2008). In the case of coal seams in close proximity, a particular set of risk factors becomes pertinent. These include disturbance of lower seams during the mining of overlying ones and the decrease in mechanical stability of lower coal seams following repeated movement of key blocks in main coal seam roofs. This inevitably results in behaviour such as heavy wall spalling and support damage to fully mechanized caving faces in lower-lying coal seams, which necessitates a significantly increase in the measures to support surrounding rock material (Zhang et al., 2010; Huang et al., 2013; Xie et al., 2013)."

Jan 1, 2016

By L. Lorig

"Two types of extreme event, earthquakes and rainfall, potentially affect open pit slope stability. In the case of earthquakes, there are rather well-developed analysis procedures and acceptability criteria. The analysis procedures relate mainly to selection of the dynamic loading either through design earthquakes and/or pseudo-static seismic coefficients. The acceptance criteria are typically expressed in terms of a minimum safety factor in pseudo-static analyses. The acceptance criteria are often promulgated by governments despite the fact that no open pit slope has ever been adversely affected by an earthquake. This paper explains why open pit slopes are seemingly more resistant to dynamic loads than natural landforms, which can experience catastrophic landslides.Extreme rainfall events are much more likely to cause open pit slope problems than earthquakes. Two types of problem are common – slope erosion and slope instability. Slope erosion is often mitigated by appropriate surface water controls. Slope instability due to elevated transient water pressures is more difficult to mitigate. Analysis procedures and acceptability criteria are rare. This paper will discuss the mechanisms for rainfall-induced slope instability, as well as analysis methods. Examples will be discussed and analysis methods are proposed. IntroductionTwo types of extreme event, earthquakes and rainfall, potentially affect open pit slope stability. In the case of earthquakes, there are rather well-developed analysis procedures and acceptability criteria. The analysis procedures relate mainly to selection of the dynamic loading either through design earthquakes and/or pseudo-static seismic coefficients. The acceptance criteria are typically expressed in terms of a minimum safety factor in pseudostatic analyses. The acceptance criteria are often promulgated by governments (e.g., Peru, Chile) despite the fact that no open pit slope has ever been adversely affected by an earthquake. This paper explains why open pit slopes are seemingly more resistant to dynamic loads than natural landforms, which can experience catastrophic landslides.Extreme rainfall events are much more likely to cause open pit slope problems when compared to earthquakes. Two types of problems are common – slope erosion and slope instability. Slope erosion is often mitigated by appropriate surface water controls. Slope instability due to elevated transient water pressures is more difficult to mitigate. Analysis procedures and acceptability criteria are rare, but do exist. In Peru, for example, slopes are required by law to be designed for a 100-year storm."

Jan 1, 2016

By O. K. H. Sheff

An editorial in the April 1990 edition of Mining Magazine is worth a wider audience in South Africa, particularly as the SAIMM enters its own centenary decade and the process of change in the minerals industry world-wide makes increasing demands on the professionalism of its leaders. The editorial considers the changing status of engineers, who up to the 1880s had been held in high regard by society. Alumina and bauxite Economists forecast a slower economic growth rate in 1990, but expect continued increase in demand for aluminum at a 3 per cent annual rate during the decade. Structural and numerical analysis Struceng & Femcad (structural analysis and finiteelement method) is a conference and exhibition that is to be held in Grenoble (France) on 17th and 18th October, 1990. It is sponsored by the Institute for Industrial Technology Transfer (ITT-International).

Jan 1, 1990

By I. Zh. Bunin, M. V. Ryazantseva, V. A. Chanturiya

The paper proposes a new method for selective calciferous separation. The effect was achieved through the application of the combination of high-power electromagnetic pulses (HPEMP) and a specific reagent regime of the flotation. The combined application of HPEMP with the special reagent regime allowed for the improvement of the scheelite floatability: the recovery of CaWO4 rises from 41.2 % (untreated sample) to 58.5 (sample treated at 103 pulses). In contrast, the floatability of calcite decreases significantly: the recovery of calcite drops from 74.7% (untreated sample) to 41.1 % (sample treated at 103 pulses). The conditions were found for the selective separation of the minerals with very close flotation properties. Keywords: Calcite, scheelite, flotation, high-power electromagnetic pulses, DRIFT, XPS

Jan 1, 2020

By Mr P. W. J. van Rensburg

SOUTH AFRICAN NATIONAL COMMITTEE ON TUNNELLING In 1970, the South African Institution of Civil Engineers, the South African Institute of Mining and Metallurgy, the South African Institute of Mechanical Engineers, and the Geological Society of South Africa held an international conference on tunnelling, known as Tuncon 1970. SUID-AFRIKAANSE NASIONALE TONNELBOUKOMITEE In 1970 het die Suid-Afrikaanse Instituut van Siviele Ingenieurs, die Suid-Afrikaanse Instituut vir Mynbou en Metallurgie, die Suid-Afrikaanse Instituut van Meganiese Ingenieurs en Die Geologiese Vereniging van Suid-Afrika 'n internasionale konferensie in verband met tonnelbou gehou, wat bekend gestaan het as Tonkon 1970.

Jan 5, 1974

By T. B. Beeton

In view of the limited reserves of good-quality coking coals in South Africa, Iscor has been involved in direct reduction since the middle sixties. Since the early seventies, its interest in direct reduction was stimulated further by a swing towards' continuous casting, which, in turn, contributed to a shortage of the scrap supply for electric-arc-furnace (EAP) steelmaking. Rock engineering The First International Conference-Rock Enginet:ring and Excavation in an Urban Environmentorganized by The Institution of Mining and Metallurgy and the Hong Kong Section of the Institution, in association with the Hong Kong Institution of Engineers, will be held in Hong Kong from 23rd to 28th February, 1986. SPOTLIGHT on Gold Fields National Engineering Awards For the Gold Fields Foundation National Engineering Awards, each university affiliated to the South African Federation of University Engineering Students (S.A.F.U.E.S.) selected a candidate who, in their opinion, presented the most outstanding design project in their final year during 1984.

Jan 1, 1985

By S. Adams, J. R. C. von Holdt, J. L. Broadhurst

Fugitive dust from mineral extraction and processing activities can significantly influence air quality, the environment, and the health and quality of life of workers and surrounding communities. Poor engagement and communication between experts and lay persons, disciplinary silos and polarised viewpoints have made it difficult to develop a holistic understanding of the complex health issues associated with environmental emissions of mine dusts, and consequently to design meaningful and integrated approaches to address such issues. The collaborative Global Challenges Research Fund (GCRF) Mine Dust and Health Network, hosted by Minerals to Metals at the University of Cape Town, serves as a collaborative think-tank to inform research directions within and across disciplines, government policy and regulations, health monitoring programmes at public clinics, industry best practice, community healthcare and impact prevention programmes. It focuses initially on the southern African region, but with the intention to expand to mining-intensive developing countries within the rest of Africa, South America and Asia. This paper outlines the approach and activities of this global transdisciplinary and intersectoral network and presents some of the key outputs and achievements to date. Keywords: Mine dust, Global Challenges Research Fund Mine Dust and Health Network

Jan 1, 2020

By J. L. Havenga

South Africa produces about 400 Kt zircon (ZrSiO4) per annum. This represents about 30 percent of the global demand. However, very little is beneficiated locally and more than 95 percent is exported with little or no value addition. Zircon is a very inert material and needs to undergo high-temperature alkaline melting processes to produce valuable zirconium products. The conversion of zircon to plasma-dissociated zircon (PDZ) produces a chemically reactive species (ZrO2.SiO2) which consist of finely divided submicron monoclinic ZrO2 crystals dispersed in a SiO2 matrix. In this paper, an in-flight, non-transferred arc pilot plasma plant with a capacity of 100 kg/h and which consists of three 150 kW DC plasma torches, is described. The optimization of the plant, which includes the use of different zircon concentrates, the influence of particle size, feed rates, plasma gas, and energy utilization, is discussed.

Jan 1, 2012

By J. L. Havenga

South Africa produces about 400 Kt zircon (ZrSiO4) per annum. This represents about 30 percent of the global demand. However, very little is beneficiated locally and more than 95 percent is exported with little or no value addition. Zircon is a very inert material and needs to undergo high-temperature alkaline melting processes to produce valuable zirconium products. The conversion of zircon to plasma-dissociated zircon (PDZ) produces a chemically reactive species (ZrO2.SiO2) which consist of finely divided submicron monoclinic ZrO2 crystals dispersed in a SiO2 matrix. In this paper, an in-flight, non-transferred arc pilot plasma plant with a capacity of 100 kg/h and which consists of three 150 kW DC plasma torches, is described. The optimization of the plant, which includes the use of different zircon concentrates, the influence of particle size, feed rates, plasma gas, and energy utilization, is discussed.

Jan 1, 2012

Book Review Gold Metallurgy in South Africa, edited by R. J. Adamson and published by the Chamber of Mines of South Africa, Johannesburg, 1972. The metallurgical processes used for the recovery of gold from Witwatersrand ores were first described in A Text Book of Rand Metallurgical Practice, published in 1912 and subsequently revised in 1926. This was followed by Gold M etall1trgy on the Witwatersrand by A. King in 1949. New Publications Elements of Practical Coalmining, S. M. Cassidy (editor), New York, Society of Mining Engineers of AIME, 1973, $16.50. Future Enerey Outlook, J. A. Pederson (editor), Colorado School of Mines Quarterly, vol. 68, no. 2, April 1973, $6.00. Guide To The Preparation Of Papers For Publication In The Journal Of The South African Institute Of Mining And Metallurgy The following notes have been compiled to assist authors in the preparation of papers for presentation to the Institute and for publication in the .Journal.

1. Book reviews Stainless Steels '84. London, Institute of Metals, 1985. £39 (U.K.), US$62 (elsewhere) Reviewer: J.B. Oalton Process engineering of size reduction: bal miling, by LG. Austin, R.R. Klimpel, andP.T. Luckie. New York, AIME, 1984. 561 pp. Reviewer: M.J. Lazer 2. Recent publications Hard and superhard materials. New York, Worltech Report Inc. (44 Woodbine Avenue, P.O. Box 212, Northport, 11768 U.S.A.), 1985. 270 pp. $1500.International comparison of standard materials-steel and cast iron, compiled by W. Oto and K. Schaning, and edited by DIN German Standards Institute e.V. Berlin, Beuth Verlag GmbH, 1985. 3rd edition, 416 pp. DM 158. Tin and its uses no. 146. Greenford (England), International Tin Research Institute, 1985. Write your own CV, by Max Kowen. Johannesburg, Legal Personnel Selections (404 Medical Centre, Cor Jeppe and Delvers Sts, Johannesburg 2001), Nov. 1985. 40 pp. R12,50 + GST.

Jan 1, 1986