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By M. J. Robinson, G. E. Blight, J. A. C. Diering

The mechanism of the flow of tailings slurry is examined, and a mathematical model is derived to describe the flow. Predictions based on the model are then compared with the flow that actually occurred near the shaft at Bafokeng after the No. I tailings dam had failed. The predictions are found to be of acceptable accuracy.

Jan 1, 1981

The Iscor Board has given its Mining Division the authority to proceed with detail engineering and design for a Heavy Minerals Project which comprises a mine in Northern Province near Gravelote, a mine in KwaZulu/Natal near Richards Bay and a central processing complex with a beneficiation plant and smelter which will be located near Richards Bay and Empangeni.

Jan 1, 1996

By M. E. Rossi, C. Badenhorst

Conditional bias occurs when the expected value of the true grade conditional on the estimated grade is not equal to the estimated grade. It is a quantification of how the average of estimates differs from the true value. Conditional bias is present in all resource estimates due to the unavoidable properties of kriging, and indeed all linear estimation (regression) methods. In a mining resource estimation context, the degree of conditional bias is dependent on the spacing of the conditioning data; more data leads to the expectation of less conditional bias This paper discusses conditional bias from two perspectives: 1. 2. Estimates seeking to eliminate, as much as possible, conditional bias; and Estimates that accept a larger amount of conditional bias in resource models, in order to achieve a specific outcome. The problem of conditional bias in estimation can only be fully appreciated if the objective or purpose of a resource model is understood. There are instances where conditional bias should be avoided because it is not reasonable to make decisions using estimates that are known to be wrong in expected value; for example, when making a final decision in grade control with respect to the destination of the material. In most instances in the mining resource estimation context, however, the estimated values will not be “final estimates”, but “interim estimates”, meaning that in the future more data will be obtained, and the ”interim estimate” will then be updated. In this context, the most useful resource model is an interim model that is able to predict the final model estimates, despite not having all the data available that will be collected in the future. This is the objective, for example, of a recoverable “long-term” model developed prior to operating a mine, for example at the feasibility stage. It attempts to predict the ore that a processing plant will receive, well into the future. In such cases, it can be unequivocally demonstrated that conditional bias is not only unavoidable, it is a necessity.

Sep 1, 2021

By D. Harbottle, D. Rhodes, T. F. Jones, S. R. Biggs

Multiphase process design and optimization often depends upon the rheological properties of sludges and slurries. In practice the task of determining these important properties is usually carried out by removing small samples from a process line or process unit and performing tests with proprietary bench-top analysers near to site or at a remote laboratory. Sampling will remain an important procedure in industrial processes, but there is also a strong case for augmenting the routine information obtained using an in situ sensor, as suggested below. ?Sampling protocols can result in extensive turnaround periods from sample collection to the generation of results. The delay can have an effect on a variety of factors such as product quality, process operability and efficiency. ?Sampling of toxic or radioactive material can prove an even greater challenge to minimize human involvement. ?Removal often changes the rheology of a specimen, and might lead to incorrect conclusions being drawn about the condition of a sludge. ?Sludge and slurry in a containment suffers a gravitational gradient, so that a removed sample should be paired with its location, particularly in the vertical dimension.

Jan 1, 2007

This paper sets out to consider a specific type of corrosion protection system, which is referred to as a Duplex Coating system. The dictionary describes a duplex system as consisting of two elements or a “twofold” composition. The duplex system described in this presentation is such a two-part corrosion protection coating, viz, hot dip galvanizing as the firm base or primer, followed by a top paint system designed to combat severe corrosive environmental conditions encountered in nature. In principle, the duplex system is a cost effective and balanced, designed coating that is suited to the environmental conditions and service life requirements.

Jan 1, 2009

By H. Brüggemann

The exploration of deposits generates geological data which are suitable for creating a preliminary tectonic and stratigraphic model. Linked with the topographical map and analysis data from exploration drillings, this information forms a numeric representation of the deposit. The following example demonstrates an expert system which connects chemical quality requirements and quarrying criteria, and develops a quarrying strategy based on the calculated model. Additional constraining factors like process technology, quarrying methods, landscape protection regulations, etc. are included. The goal is to guarantee a long-term, homogeneous material flow from the quarry at acceptable production costs - even in the case of an extraordinarily inhomogeneous deposit. In order to fulfil this requirement it is necessary to consider a large number of rules, criteria and instructions which can be structured as an expert system and programmed with LISP at a comparably low cost. The chosen strategy is not necessarily final, but can be changed any time by altering or varying the framework of conditions. The output consists of a block-working sequence which best satisfies the set requirements for appropriate points of quarry opening.

Jan 1, 1987

By R. C. Urquhart, D. D. Howat, R. I. L. Guthrie

Heat losses from ladles during teeming by R. C. URQUHART, M.Eng. (McGiII), Ph.D. (Visitor). R. I. L. GUTHRIE, B.Sc. (Eng.) (London), A.R.S.M., Ph.D., D.I.C. (Visitor), and D. D. HOWAT, B.Sc. (Glas.), Ph.D. (Fellow) In an investigation of the loss of temperature by liquid steel during a teeming operation, a numerical technique was used to calculate the heat flows and the rate of temperature drop over the entire teeming operation. The calculations show that, before teeming, approximately 50 per cent of the heat loss is into the ladle wall at the level of the metal. As teeming progresses, the amount of heat lost by radiation to the wall above the metalline increases. The effect of variables, such as initial metal temperature, the preheat of the ladle and ladle cover, and delays, on the rate of temperature loss by the metal were determined.

Jan 11, 1973

Contribution by W.D. Ortlepp In the Journal of May 1994, the authors first presented the concept and analysis that formed the basis for a design approach for deep tunnels, now expressed more explicitly in the present paper (March/April 1996). In a contribution in the Journal of March/April 1995, I expressed a certain disquiet about the validity of their original approach. The authors responded to these criticisms in the same issue. It is apparent to me now that both the contribution and its rebuttals were written, probably for different reasons, in such an obscure and pedantic way as to further confuse the reader rather than provide enlightenment. My concern still persists. But in order to avoid further confusion I will attempt to pose my uncertainties and difficulties in a much more direct way. On page 98 (top of 2nd column) in the earlier paper, an important statement concluded as follows: '. . . the horizontal ellipse requires 140 per cent less force for equivalent stability'.

Jan 1, 1996

By M. L. Young, J. B. See

Effective thermal conductivities of packed beds of chromite ores by M. L. YOUNG, B.Se. (Rand), M.Sc. (Rand) (Visitor) and J. B. SEE, B.Sc. (Hons), Ph.D. (New South Wales), M.I.M., M.I.M.M. (Member) The effective thermal conductivities in stagnant air of packed beds of fines, lumps, and indurated and pre-reduced pellets of two chromite ores with different chromium-to-iron ratios were determined in the temperature range 300 to I 100°C by the heat-sink technique. Packed beds of fines, whether of the size fraction between 20 and 65 mesh, between 65 and 100 mesh, or between 100 and 150 mesh, were found to have the same values of effective thermal conductivity. For one ore, the effective thermal conductivities of packed beds of fines between 20 and 48 mesh at tem peratures above 600"C were higher than those for finer particles. This difference is explained as being due to the increase in importance of radiation heat transfer, but no definite conclusions are reached about the relative contributions of conduction and radiation heat transfer to the effective thermal conductivities of packed beds of fines between 20 and 48 mesh. Two published models were used for the theoretical prediction of values for thermal conductivities of the indurated and pre-reduced pellets as well as of lump ore. The experimental and theoretical results were in good agreement in view of the uncertainties in the assumed values of emissivity and thermal conductivity of the chromite ore.

Jan 12, 1976

By More-O&apos, R. C. Ferrall, J. W. Wilson

SYNOPSIS The theory of elasticity has been shown to provide a means of determining the stresses and displacements induced by mining in deep level hard rock mines. This theory has been incorporated into an electrical resistance analogue on which the plane of a reef or ore-body can be modelled to enable the rapid determination of stresses and displacements at points in the plane of the reef. This electrical analogue has been used to determine energy release rates caused by scattered mining, which, to some extent, is a measure of the degree of hangingwall fracture. A correlation between predicted energy release rates and actual underground conditions in stopes in the O.F.S. goldfields has been encouraging enough to define parameters on which future stoping layouts can be based. The use of the elastic theory through the analogue has been extended to the assessment of the influence of stoping operations on off-reef excavations. Underground conditions at damaged and undamaged areas have been compared with predicted elastic stresses at the positions under review, resulting in the derivation of design parameters for use in siting off-reef excavations in the prevailing geological conditions in the O.F.S. and Klerksdorp goldfields. The analogue has also been used to assess the vulnerability of certain un mined dykes to bursting. Correlations between stresses induced on dykes by stoping and dyke behaviour underground has enabled critical stress levels to be determined for several persistent dykes occurring in the O.F.S. and Klerksdorp goldfields. A number of long and short term planning projects at mines operating in the Anglo American Corporation and General Mining and Finance Groups are described, where the data derived from the electrical resistance analogue is processed by computer programmes and assessed on the strength of the design factors derived from the correlation of field work and the elastic theory.

Jan 1, 1970

By J. van Deventer

Ion exchange is widely used in hydrometallurgical operations for the recovery and purification of valuable metals. Special chelating resins have a high affinity for specific elements, allowing the selective removal of low levels of impurities from a background of highly concentrated valuable metal. Solvent-impregnated resins have been added to this group more recently, expanding the treatment options. These products find application in the purification of cobalt-rich liquor prior to the production of high-purity metal or metal salts. Impurities in copper-cobalt circuits that are typically targeted by ion exchange include iron, uranium, copper, zinc, nickel, bismuth, and antimony. Ion-exchange resins can also be used to treat tailings, thereby recovering additional valuable metal and improving the Environmental and Social Governance credentials of the operation. This article takes a look at various applications of ion exchange in copper-cobalt operations

Jan 1, 2023

1. Mintek reports The folowing reports are available from Mintek, Private Bag X3015, Randburg, 2125 South Africa. They are available at R25 (plus R3,25 GST) per copy to South African addressees, and US$25 per copy (including airmail postage) to addressees elsewhere. Report M91D A mineralogical investigation of samples from the Renosterkop tin prospect near Upington, by M.J. Southwood. First issued Jul. 1983, reissued May 1989. 16 pp. Report M256D The upgrading of Mamatwan manganese ores heavy-medium separation, by P. W. Overbeek. First issued Apr. 1986, reissued May 1989. Report M299D A mineralogical investigation of samples from the Eenzaamheid cobalt-molybdenum deposit, by C.D. de Nooy. First issued Jan. 1987; reissued May 1989. Report M301D The evaluation of manganese metal powder by automatic image analysis, by E.J. Oosthuyzen. First issued Feb. 1987, reissued May 1989. 13 pp. Report M311D Mineralogical and beneficiation studies of ore from Lutzputz, by R.N. Guest and C.T. Logan. First issued Mar. 1987, reissued May 1989. 13 pp. Report M314D The beneficiation of a sample of magnesium ca/crete, by L. Jonker. First issued Apr. 1987, reissued May 1989. 13pp. Report M369 The determination, by flow-injection analysis, of thiocyanate, by E.A. Jones and M-J. Hennings. Jun. 1989. 7pp. Report M389 A spectrophotometric method for the determination of zinc by flow-injection analysis, by D.E. Barnes and RA. Jones. Jul. 1989. 15 pp.2. Recent publications Pumps-principles and practice. Available from K. Myles & Associates CC, P .0. Box 2212, Northclif 2115. :200pp. R99 including GST. Standard handbook of hazardous waste treatment and disposal, edited by H.M. Freeman. Bergano Book Co., P .0. Box 190, Fairfield, CT 06430, USA. 1120 pp. US$130.Quality control handbook, by J. Juran and F. Gryna Jr. Bergano Book Co. (address as above). 4th 00. 1536pp. US$125.Refractories in the manufacture and transport of pig iron. Verlag Schmid GMBH, P.O. Box 6609, 7800 Freiburg, West Germany. DM 100. The user-computer interface in process control, byW.E. Gilmore, D.I. Gertman, and H.S. Blackman. London, Harcourt Brace Jovanovich Ltd, 1989. " 312pp. $29.Aluminum alloys-contemporary research and applications, edited by A.K. Vasudevan and R.D. Doherty. London, Harcourt Brace Jovanovich Ltd, 1989. " 676 pp. " £90.3. TMS publications issued recently The folowing publications are available from The Minerals, Metals & Materials Society, 420 Commonwealth Drive, Warendale, PA 15086, USA (Telephone: (412) 776-9000, Telex: 9103809397, Fax: 4127763770). Advances in magnesium alloys and composites, by H. Paris and W.H. Hunt (eds.). 145 pp. $65. Arsenic metallurgy-fundamentals and applications, by R. Reddy (ed.). 515 pp. $104. Casting of near net shape products, by Y. Sahai (ed.). 7oopp. $155.Continuous casting of non-ferous metals and alloys, by H.D. Merchant, D.E. Tyler, and E.H. Chia (eds.). 360 pp. $90.Dislocations and interfaces in semiconductors, by K. Rajan, D. Ast, and J. Narayan (eds.). 210pp. $75.

Jan 1, 1989

By B. Jack, A. Vervoort

During pillar extraction, sidewall fracturing and spalling at some collieries constitute a severe stratacontrol problem. In order to obtain a better understanding of this phenomenon, a survey of pillar corner conditions before and during pillar extraction was conducted at one particular site. For the various successive mining steps, the vertical stresses on the pillar corners were calculated by use of a three-dimensional boundary element program. A significant correlation was found between the calculated vertical stress prior to the extraction of the panel and the sidewall conditions. During the extraction of the panel, a significant deterioration of the sidewall conditions at a pillar occurred only when the adjacent pillar was mined, causing an increase in vertical stress on the remaining pillar.

Jan 1, 1992

"Pressure leaching is an option for copper recovery from chalcopyrite. Leaching takes place at high temperatures and pressures in the presence of an oxidizing agent. This work shows how the performance of pressure leaching circuits may be improved by optimizing the configuration of autoclaves and the heat removal method. The objective was achieved by creating an autoclave model that combines mass balances, energy balances, and population balances. A base case circuit consisting of a single autoclave was chosen, and this base case was compared with options for increasing capacity by adding more autoclaves to the circuit. These capacity increase options include circuits in which the additional autoclave is added in parallel, in series, and in series with thickening between the two autoclaves. The copper extraction, productivity, and cooling requirements for these options are compared. The series circuit with interstage thickening has the highest extraction and productivity; however, the cooling duty in the first autoclave is high. In addition to comparing circuit options, three options for heat removal were investigated: cooling coils, quench water, and flash recycling. The flash recycle option results in the highest copper extraction, and the quench water option the lowest copper extraction. IntroductionBackgroundCopper sulphide ores and concentrates containing chalcopyrite are typically hard to leach under atmospheric conditions. Smelting of these ores may also be a challenge, due to the inability of smelting processes to handle low-grade ores, as well as impurities such as arsenic and antimony. Alternative hydrometallurgical routes to treating chalcopyrite are therefore required. One option is pressure leaching, which is the focus of this work.In the pressure leaching process, sulphide ores and concentrates are leached in autoclaves at temperatures of 200 to 220°C and a pressure of about 3000 kPa (Schlesinger et al., 2011). An oxidizing agent, usually oxygen, is required to oxidize sulphide ions to sulphate ions. The oxidation of sulphur to sulphate is exothermic; consequently, a method of heat removal is necessary in order to maintain the temperature in the autoclave."

Jan 1, 2016

1. Publications of the World Mining Congress Series A: Volume 5 World mining data '90. US$25. Series B: Volume 1 Chromite. US$31. 2. Randol publications The folowing publications are available from Randol International Ltd, P.D. Box 150632, Lakewood, CD80215, U.S.A.). Randol Gold Conference, Sacramento '89. 1990. 400 pp. $80. Randol mining directory 1990-1991. 1990. $100. Randol buyer's guide USA and Canada. 1990. $50. 3. New journal Industrial Metrology, edited by A. Choudry et al. Amsterdam, Elsevier Science Publishers, 1990. Dfl. 266 incl. postage for 4 issues per year. 4. Mintek reports The folowing reports are available from Mintek, Private Bag X3015, Randburg, 2125 South Africa. They are available at R35 (including GST) per copy to SouthAfrican addressees, and US$30 per copy (including airmail postage) to addressees elsewhere. Report M130D The application of a standard leaching procedure to tin-tungsten concentrates from Van Roois Vley deposit: Cross-cut bulk samples, by M.M. Fieberg and C.F.B. Coetzee. First issued 1984, reissued 1990. 11 pp. Report M160D The recovery of graphite from the Messina district, by R.N. Guest. First issued 1984, reissued 1990. 22 pp. Report M305D The beneficiation of nickel-copper ore from Uitkomst, by P.W. Dverbeek. First issued 1987, reissued 1990. 55 pp. Report M320D The flotation of pyrite from Bufe/sfontein Gold Mine, by A.M.R. Botelho de Sousa and V.E. Ross. First issued 1988, reissued 1990. Report M347D A utogenous miling of ore from the UG-2 Reef, by J.K.H. Lichter. First issued 1988, reissued 1990. 13 pp. Report M352D Fly ash as an adsorbent or precipitation agent in the removal of ionic species from solution, by C. Pohlandt-Watson, S.M. Graham, and K.F.G. Brackenbury. First issued 1988, reissued 1990. 9pp. Report M360D Beneficiation of limestone from Pienaars River, by R.N. Guest. First issued 1988, reissued 1990. 23 pp. Report M364D The recovery of gold from deposits in the Pilgrim's Rest area, by R.A. Burger. First issued 1988, reissued 1990. 15 pp. Report M396 Reduction of chromite spinels in iron-chromiumcarbon aloys, by R.H. Eric and E. Uslu. Mar. 1990. 33pp. 5. New review Diverless and deepwater technology. Advances in underwater technology, ocean science and ofshore engineering, edited by the Society for Underwater Technology. London, Graham & Trotman Limited, 1989.224 pp. £55.

Jan 1, 1990

Professor R. P. Plewman graduated with a B.Sc. in mining engineering from the University of the Witwatersrand in 1943, after which he had two years of military service. Mr P. W. J. van Rensburg attended St Andrew's College in Grahamstown before proceeding to the University of the Witwatersrand, where he obtained a B.Sc. (Eng.) degree cum laude in mining and metal. lurgy at the end of 1942 and was awarded the Chamber of Mines Scholarship and Gold Medal. Dr M. G. Atmore, Deputy Technical Director of the Anglo American Corporation of South Mrica, is also Manpower and Education Adviser to the Chamber of Mines of South Mrica and a Visiting Professor at the Imperial College of Science and Technology, London. Mr D. A. Vi1joen attended Queen's College, Queenstown, and then Rhodes University, where he gained a diploma in chemistry and a B. Comm. degree. Mr B. E. Protheroe, C.Eng., obtained a degree in Physical Metallurgy at University College, Cardiff, and an M.sc. in corrosion science from Swansea University. Mr N. J. Devine holds a B.Sc. in Metallurgical Engineering and a G.DE Mining Engineering, both from the University of the Witwatersrand. Dr Oskar Steffen graduated as a civil engineer at the University of the Witwatersrand in 1961, and obtained his master's degree in 1963.

Jan 1, 1984

By R. Weideman, K. du Preez

Biological sulfate reduction has become a successful treatment alternative for acid mine drainage and Mintek is developing biological processes for treatment of highsulfate mine waters. Treatment of these high-sulfate waters is achieved by sulfatereducing bacteria that reduce sulfate to produce sulfide as a product, in the form of H2S and HS− at neutral pH. This introduces the opportunity to apply treated effluents from biological treatment processes for the recovery of metals, such as copper, from metallurgical waste streams. This study models the kinetics of copper sulfide precipitation from a complex bioleach liquor. The results indicated a rapid rate of reaction and the formation of covellite, suggesting the potential to use biogenic sulfide to recover copper as a metal sulfide product.

Jan 1, 2023

"Chairman: Prof A. E. H. BLEKSLEY Rapporteur: Prof J. ELBRONDPanel Members: Prof J. C. Griffiths, Prof T. E. Hawkins, Mr A. C. Langton, Mr M. Splaine, Mr A. WeissThe reasons for failure of computer applications in the mineral industry and the direction of future developments.The Chairman opened the discussion by elaborating on the disappointment felt by some authorities with the lack of progress in the application of computers in the mineral industry during the last ten years, and posed the question to the panel : 'Do you agree that the computer age has not come up to expectations?'Mr Langton said that although there seemed to be a tremendous amount of brainpower applied to the theoretical side, he thought that the production men had not got all the help from computers that could have been given to them. The computer, said Prof Griffiths, is as yet a new tool which should not be used to do old things in old ways. To learn to use the computer will take time. After all, he said, it had taken 400 years after the introduction of the printing press to achieve general literacy, and perhaps it will take 40 years after the introduction of the computer to achieve `numeracy'.In Mr Weiss' view, the reason for the feeling of disappoint¬ment lay in the focussing of attention on the computer. The blame, if any, lay with the people surrounding the computer, that is, the analysts and programmers, to whom the emphasis should be shifted.Prof Hawkins said that he thought that some applications of the computer in the mineral industry had been successful, such as, for example, the compilation of payrolls. Reasons for failures in other areas were to be sought in the fact that the people connected with computers had failed to realise that they were merely part of a system. They had not understood the power structure of the organization which their work tended to change, and were therefore not prepared for the inevitable conflict with the production men.In Mr Splaine's view the production man had not received the assistance he could have had from the computer people because he may possibly not have allowed this to happen.Prof Bleksley concluded from these opinions that the promise which computers had ton years ago had not been fulfilled and added that the opinions expressed by the panel had intruded on his next question which was: 'Is the reason for this that people are involved?Prof Hawkins elaborated on his previous theme, namely, that of computer people in relation to management. Com-puter people, he said, were trying to impose change on management but were not prepared to share the responsibility for these changes. In fact, they wanted their work to be distinct and separate, and, as far as management was concerned, changes would be made when management believed that these would be less agonizing than no change at all."

Jan 1, 2014

By A. J. S. Benade, N. B. Strydom, W. H. Van Der Walt

The performance of the improved microclimate suit by N. B. STRYDOM M.Sc., Ph.D. (Illinois) (Fellow), A. J. S. BENADE, B.Sc. (Potch.) (Visitor), and W. H. VAN DERWALT, M.Sc. (Potch.) (Visitor) An assessment has been made of a new improved microclimate jacket when worn by men working for four hours in a hot environment (wet-bulb temperature of 33,9°C and an air speed of 0,4 m/s) and at work rates of 35 Wand 70W. At the lower rate of work in heat, the use of microclimate suits maintained the rectal temperatures of the men at almost the same level as when they worked without that protection at normal room temperature (20°C). At the greater rate of work without protection, the men's rectal temperatures rose to 40°C within two to three hours, so that they could not complete four hours of work. When they wore microclimate suits, they easily completed four hours of work, and their rectal temperatures were lower than when they worked at the lower rate without protection.

Jan 8, 1975

By H. P. Carlisle

The significance of the mineralogical and surface characteristics of gold grains in the recovery process by C. E. FEATHER and G. M. KOEN Published in the Journal. February 1973. DISCUSSION H. P. Carlisle. B.Sc. (Eng.) Rand (Fellow) The authors are to be congratulated on drawing attention to the importance of surface characteristics in the treatment of gold grains. I must, however, confess to considerable doubts about the validity of the distribution of gold in "free" and "locked" form set out in Tables I to IV.