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The South African Institute of Mining and Metallurgy mourns the passing of one of its most distinguished sons. Professor J. de V. Lambrechts died at Franschoek on 30th January, 1988, at the age of 76 years after a long illness. Mintek Application Reports A new series of Mintek reports made its appearance in 1987. These are Application Reports, which present an overall perspective of each of Mintek's technical thrusts to ensure that the existing expertise can continue to be readily accessed. The successful development of an industrial process for the recovery of platinum-group metals from the UG-2 Reef. Application Report no. 1. 1987. 16 pp. The development and implementation of a computer control strategy for conventional milling circuits. Application Report no. 2, 1987. 15 pp. The development of an integrated carbon-in-pulp process for South African conditions. Application Report no. 3. 1987. 17 pp.

Jan 1, 1988

By P. N. Erasmus

This paper considers the fundamental concepts of support design for underground openings in highly stressed ground. It concludes that the conventional deformed reinforcing bar, woven mesh and cable lacing support methods that have been widely used in deep gold mines are quite in appropriate for the support of highly stressed tunnels. The following is suggested as the criterion for adequate dynamic support under rockburst conditions: the energy absorbed by a support unit (yielding through some acceptable limited displacement) should exceed the kinetic energy generated by the mass of rock that is intended to be retained by that unit. Duraset in conjunction with SRK Consulting has developed a yieldable steel tendon called the Durabar®. It is unique in the sense that it cleverly utilizes the property of the ductility of ordinary low-carbon steel from which it is made to accommodate the excessive displacement it is subjected to in the case of rockbursts or swelling ground.

Jan 1, 2009

By G. Blight

As part of an investigation of possible water-saving measures at Anglo American Platinum's Mogalakwena Mine in Limpopo, South Africa, a study was made of conditions on the wet beaches of two adjacent tailings dams, each serving a separate plant on the mine. For one of the dams, a special catamaran was designed and constructed to enable the full length of wet beaches to be accessed and sampled immediately after a layer of tailings had been deposited. For the other dam, the wet beach was accessed using conveyor belting and scaffold planks. The length of the beaches was 400 m on the first dam, and 200 m on the second, and each was sampled at 50 m intervals. The parameters reported in this paper, for both beaches, are: > Water content profiles along each beach from the surface to as deep as 2.5 m, at times ranging from 12 hours to 6 weeks from the end of deposition > Particle size distributions at the surface, down the full length of the beaches > Measurements of feed relative density, tonnage and volume, decant and drain flow volumes, as well as rainfall and evaporation for both dams. The surface water contents shortly after deposition have been used to establish the relative density of the settled, decanted tailings and its variation down the beach. This data, combined with the decant and drainage flows, is used to establish the calculated and actual water recoveries from both dams.

Jan 1, 2012

"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

The Canadian Institute of Mining and Metallurgy. Milling practice in Canada. CIM Special Volume 16. 1978. The purpose of this volume is to up-date The Milling of Canadian Ores, which describes Canadian mineral. processing plants and gives other metallurgical information, and was published by the Sixth Commonwealth Mining and Metallurgical Congress in 1957. NIM reports Report no. 1874 Activation analysis and classification to soune of samples from the Kimberley Reef conglomerates. (10th Mar., 1977; released Jun. 1978). Report no. 1926 The analysis of anode sludges by X-ray-fluorescence spectrometry. (5th Jun., 1978). Report no. 1936 The analysis of mineralogical and metallurgical materials. A guide to the analytical techniques and instrumentation available at the National Institute for Metallurgy. Report no. 1959 The slag-metal equilibrium, and the activities of slag and metal components in the production of high-carbon ferromanganese. (15th May, 1978). Report no. 1965 Analyses, by several laboratories, of three ferromanganese slags. (22nd May, 1978). Report no. 1968 The influence of carbonaceous reducing agents on the rate of reduction of representative manganese and chromium ores. (28th May, 1978). Company Affiliates 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.

Jan 1, 1979

By M. B. Dunn

Terminals form part of the transportation chain from producer to consumer in the world-wide conveyance of bulk commodities. As such, they are a vital link in providing a buffer between widely differing transporation modes. It is essential in the conceptual design of such terminals that an overall view of the entire system of which they form a part is taken. Only in this way can it be ensured that the system will operate smoothly and without disruption, for in the end such disruptions can have dramatic repercussions, both on the cost of the commodity in the market place and on production. In this respect, computer simulation is a useful tool in arriving at the optimum design for the system. The Richards Bay Coal Terminal provides a good example of such an approach. Commissioned in 1976 to handle 12 Mt per annum, it is now handling 24 Mt per annum, with plans for further expansion to 44 Mt per annum in the future.

Jan 1, 1980

By S. Selmer-Olsen

New trends and developments in the production of ferro-silicon, ferro-manganese and ferro-chrome alloys are discussed, with emphasis on the general trend to the adoption of large production units. Problems which arise, both of a metallurgical and an electrical nature, due to the use of large electric furnaces, are outlined with specific reference to the limitations imposed by the power carrying capacity of Soderberg electrodes, the furnace resistance and the furnace reactance. The implications of combining high resistance within the furnace with good metallurgical operating conditions are illustrated by considering the production of ferro-silicon and ferro-manganese. The possibility of replacing electric furnaces used for ferro-manganese production, by large low shaft blast furnaces using oxygen enriched blast, is mentioned. The continued use of small electric arc furnaces for ferro-chrome production is also mentioned, and is ascribed to lack of ore suitable for treatment in large furnaces. Agglomeration of chromite ores appears to be a possible answer to this problem.

By M. B. Díaz Aguado, I. Á. Fernández, C. González Nicieza, B. S. Menéndez

This paper summarizes the works that the Research “Group of Ground Engineering”, belonging to the Mining Department of the University of Oviedo, Spain, has been developing in close cooperation with the Regional Mining Department, since 2001, in order to control and monitor an experimental underground limestone exploitation by the room and pillars method. The aim of the current research is not only the geotechnical characterization of the rock mass (by means of laboratory and site tests) or the instrumentation of its displacements and stress changes (using convergence meters, INCREX probe, extensometers and rigid inclusion cells), but, moreover, to undertake intensive monitoring and control of such pilot mine, which is mined exclusively in order to accomplish this research. The data transmission was made on line via Internet, to achieve a full understanding of the behaviour of the experimental mine, to access data from remote locations and to visualize results from a website. All the collected information becomes input data for several numerical models using finite differences under a program developed in the research Group, ALMEC. The simulation and a final economical analysis lead to a design of an underground exploitation, at production scale, for a resource that is traditionally mined by means of open-pit process methods that could be worked underground with less environmental impact. The main purpose achieved by this exhaustive analysis is the technical and economic viability of such mine, for their optimisation for a future productive exploitation.

Jan 1, 2003

Published experimental data on thermodynamic behaviour of cobalt-containing slags have been reviewed and used in validating a recently developed thermodynamic model. The results from the exercise show that the model provides a reasonably good description of behaviour of cobalt in multi-component slag systems. The models for cobalt containing slags, matte and oxide solid solution phases were incorporated into CSIRO?s multi-phase equilibrium (MPE) package, which was used to calculate the equilibrium distribution of cobalt between matte and slag phases under various conditions. The results agreed well with the experimental data. Furthermore, the good agreement between the calculation and the plant data indicates that the operating conditions of industrial smelting and converting processes are close to equilibrium. Two diagrams showing the effects of slag chemistry and SO2and O2partial pressures on the distribution of cobalt between phases were generated for conditions similar to smelting and converting processes. These diagrams provide some useful guidelines for developing new strategies to improve cobalt recovery.

Jan 1, 2004

By R. C. O’Ferrall, W. G. Goulding

This paper describes the performance of a Robbins 52R Boxhole Borer from its introduction into the mine in July 1975 until late in 1977. As indicated by the costs involved, the performance has increased considerably and is expected to be even better once further envisaged modifications have been made. The average cost for the first half of 1977 was R275 per metre bored as against an average of R628 for 1975.

Jan 1, 1978

By H. S. Sichel

Statistical valuation of diamondiferous deposits By H. S. SICHEL, D.Sc The valuation of diamondiferous deposits depends on (i) the density distribution, (ii) the size distribution of stones and (iii) the selling price structure prevailing at a particular time. In the density distribution the stochastic variable is defined as the number of individual stones found per sample unit irrespective of the stone size. The density distribution is discrete and allows for barren sample units. As diamonds often occur in clusters, a Poisson mixture distribution is derived which is entirely new, as existing discrete distributions cannot represent the stone number frequencies found in nature. For the sizes of diamonds, which are measured by weight, a new compound logarithmic normal distribution is developed. Combination of (i), (il) and (iii) leads to a meaningful appraisal of diamondiferous ground expressed in monetary value per production unit of mining. Finally, confidence limits are calculated which allow for inferences from sampling to recovery.

By E. Cetin

Orebodies that contain more than one economically important mineral are generally evaluated by parametric cut-off grades. This approach often leads to mis-valuation of mineral deposits because cut-off grades are not based on the grades of each individual mineral and, because of the parametric formulation, are only indirectly related to the individual grade distributions. The only realistic approach is a formulation that accounts separately for each component mineral. The grid search method can be used as a means of multi-mineral cut-off grade optimization in this context. This paper describes the use of the grid search method in cut-off grade optimization for multi-mineral deposits. The authors introduce the general concepts of the method and formulate its application to cut-off grade optimization; they describe a software implementation of the method that can accommodate cut-off grade optimization for mineral deposits that contain up to three economic minerals. Keywords cut-off grade, optimization, grid search, multi-mineral deposits.

Aug 1, 2013

By D. W. Horsfall

The coal-preparation techniques used in South Africa over the past ten years are reviewed, the term preparation being taken to refer to processes involving beneficiation techniques. The success of the preparation methods adopted can be gauged from the fact that, although South African coals are generally of a fairly low quality, the country is producing coals both that are used locally for the raising of steam and for metallurgical purposes, and that compete successfully on world export markets.

Jan 1, 1980

By S. M. Bradshaw

In order to assess the requirements for online matching when using a transverse electric field (E-field) applicator to treat mineral ores continuously, the effect of varying load properties on matching has been investigated by simulation. The effective permittivity of the ore to be treated is expected to show variation on both short (< 1 s ) and long (minutes) time scales. By modelling the ore as a series of slices with alternating effective permittivity values, it was shown that permittivity variations on the scale of the expected particle size are attenuated significantly and matching is not required. For variations in permittivity on the length scale of the free-space wavelength, variations in reflected power are at most within ±10% of the mean. This is not considered operationally significant, as extreme permittivity variation over this length scale is unlikely, given the expected distribution of ore particle sizes to be treated. At typical ore transport speeds through the applicator, these variations occur on a time scale an order of magnitude shorter than the response time of typical industrial online matching equipment. This implies that online matching is neither required nor possible for short time scale variation. Long-term variations in dielectric properties can be adequately compensated for by current matching technologies. It is concluded that the transverse E-field applicator is robust to changes in the dielectric properties of crushed ores within the expected range of their variation.

Jan 1, 2012

By R. V. Ramani

Managers need quality information for effective decision making. This demand, at the present time, is being fulfilled by the increased use of computers via information systems, decision support systems and management information systems. The idea of incorporating intelligence into computers to aid decision-makers has been evolving for over two decades. In recent years, significant progress is reported on applications to business and sciences. In engineering functions, the Artificial Intelligence approach that seems to have great potential is the application of Knowledge Based Systems. The primary objective of this paper is to identify domains in mining engineering where application of knowledge based systems could be beneficial. In- corporation of the expertise required during the analysis and interpretation stages of an engineering design problem through knowledge based systems is recognized as an area of significant benefit. To this end, the components of knowledge based systems for mine ventilation and strata control design are described. The potential applications and limitations of knowledge based systems are outlined.

Jan 1, 1987

Statistics is essentially a study of variability, the use of some suitable mathematical model representative of such variability, and the application of this inferred pattern of behaviour to practical problems. Probability theory is the mathematical structure devised for providing models for chance happenings. Perhaps the simplest example of a chance happening is the result obtained in tossing a coin. Although the result of a single toss can never be predicted with certainty, there is no reason why in repeated tosses the expectancy of heads and tails should not be equal. In such a case the outcomes of the experiment are said to be equally likely, so that the probability of obtaining heads (or tails) is 1 in 2, that is, 0,5. This simple probability .model refers to a &apos;mathematical&apos; or &apos;unbiased&apos; coin. Whether such probabilities are meaningful for actual coins tossed in any particular way is a matter for experience to determine. Probability models have also provided the basis for representing observed variability in cases where the actual under- lying probabilities are only partly known or defy analysis. A typical example of the latter case is the variability observed in the values obtained from gold or other ore samples. The interacting natural forces which gave rise to this variability are obviously very complex and are unlikely ever to be unravelled completely. In spite of this, probability theory and the more recent geostatistical theories have provided us with models which can represent this variability on a reasonable basis. Applied statistics and geostatistics must therefore never be accepted as exact mathematical sciences. Furthermore, a basic and essential concept is that in the type of applications covered in these notes, no model must ever be accepted as necessarily the final and exact answer to the problem; thus, any model must prove and continue to prove its appropriateness in practice, preferably by follow-up comparisons.

Jan 1, 1981

Book reviews Jones, M. J. (editor). Process engineering of pyrometallurgy. Proceedings of a joint meeting of the Institution of Mining and Metallurgy and the Institution of Chemical Engineers. London, Institution of Mining and Metallurgy, 1974. 105 pp. £6,50. Nim reports Report No. 1656 The analysis of geological samples for trace elements by direct-reading emission spectrometry. Report No. 1669 An assessment of the carbon-rod atomizer for the determination of silver.

Jan 12, 1974

By M. M. Makhofane

Anhydrous zirconium tetrafluoride can be used as a precursor for the manufacturing of nuclear-grade zirconium metal. This can be done by fluorinating plasma-dissociated zircon with ammonium bifluoride in a batch reactor. This paper describes the batch process. It was proved that anhydrous zirconium tetrafluoride can be manufactured by this route as confirmed by X-ray diffraction. The process shows potential for scaling up to the kilogram scale and possibly the tonnage scale.

Jan 1, 2012

Foamed cement packs offer a viable alternative to conventional timber or other forms of packs for permanent underground support. These packs comprise steel mesh and hoop containment with an outer bag for the grout; woven, laminated polypropylene fabric being ideal for the purpose. The grout is supplied in 25kg bags and fed into a purpose ? designed foam placer machine which delivers the foamed grout directly to the packs from 60 metre long delivery hose. Foamed cement grout as a fill material offers attractive properties for support packs, in summary these are: Variable Grout Strength Grout strength is controlled by the grout density being delivered from the placer machine. This can be changed by the machine settings. Strength Development Fast rate of strength development is possible so that support is available quickly. Pack yield The foamed grouts are compressible so that yielding of the grout pack can be achieved without loss of support. Rate of Filling Three sizes of placer machine are available, these use one, two, or three 25kg bags per minute of grout, pack filling time is therefore a matter of minutes, a typical 0.75m diameter pack x 1.2m high taking some 17 minutes to fill. Tests in a 1000 tonne press have confirmed that the above characteristics can be achieved with foamed cement packs at acceptable cost. This will be illustrated in the paper with experience to date.

Jan 1, 2008

NIM Reports Report no. 1549 Thermodynamic and related physicochemical factors pertaining to the production of ferromanganese. A literature survey. Report no. 1568 A computer programme for the estimation of parameters in flotation. Report no. 1571 The commissioning of a directreading spectrometer for the analysis of silicate rocks by use of the graphitepellet technique. Report no. 1582 The construction and testing of a precision calorimeter. Report no. 1587 A preliminary investigation of the flotation of copper-activated sphalerite without the use of collectors.

Jan 2, 1974