Search Documents

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. All papers must meet the standards set by the Council of the Institute, and for this purpose all papers are referred to at least two referees appointed by Council. STANDARDS FOR ACCEPTANCE To merit consideration papers should conform to the high standards which have been established for publication over many years. Papers on research should contain matter that is new, interpretations that are novel or of new significance and conclusions that cast a fresh light on old ideas. Descriptive papers should not be a repetition of well-known practices or ideas but should incorporate developments which would be of real interest to technical men and of benefit to the mining and metallurgical Industry. In some cases a well prepared review paper can be of value, and will be considered for publication. All papers and particularly research papers no matter how technical the subject, should be written with the average reader of the Journal in mind, to ensure wide interest. The amount of textbook material included in a contribution should be the minimum essential to the argument. The length of a paper is not the criterion of its worth and it should be as brief and concise as possible, consistent with the lucid presentation of the subject. Only in very exceptional circumstances should a paper exceed 15 pages of the Journal (15 000 words, if there are no tables or diagrams). Six to ten pages is more normal. NOTE: Papers in the Journal are printed in 10 point type, which is larger than the 8 point type used on this page. For special publications Council may decide on page sizes smaller than A4 used for this Journal. The text should be typewritten, double-spaced, on one side only on A4 size paper, leaving a left-hand margin of 4 cm, and should be submitted in duplicate to facilitate the work of the referees and editors. LAYOUT AND STYLE Orthodox sequence Title and author's name, with author's degrees, titles, position. Synopsis, including a brief statement of conclusions. Index, only if paper is long and involved. Introduction. Development of the main substance. Conclusions, in more detail. Acknowledgements. References. Title: This should be as brief as possible, yet give a good idea of the subject and character of the paper. Style: Writing should conform to certain prescribed standards. The Institute is guided in its requirements by: Collins, F. H., Authors &, Printers' Dictionary-Oxford University Press. Hart, H. Rules for Compositors and Readers. Humphrey Milford (familiarly known as the Oxford Rules). Fowler. H. W. & F. G. The King's English-Oxford University Press. General: A few well selected diagrams and illustrations are often more pertinent than an amorphous mass of text. Over-statement and dogmatism are jarring and have no place in technical writing. Avoid the use of the first person, be objective and do not include irrelevant or extraneous matter. Avoid unnecessary use of capitals and hyphens, while punctuation should be used sparingly and be governed by the needs of sense and diction. Sentences should be short, uninvolved and unambiguous. Paragraphs should also be short and serve to separate basic ideas into compact groups. Quotation marks should be of the 'single' type for quotations and "double" for quoted matter within quotations. Interpretations in the text should be marked off by parentheses ( ), whereas brackets [ ] are employed to enclose explanatory \matter in the text. Words to be printed in italics should be underlined singly. For small capitals they are to be underlined DOUBLY and for large capitals TREBLY. If there is any problem in producing formulae accurately by typewriter they should be inserted by handwriting in ink in the copy forwarded by authors. Abbreviations and symbols are laid down in British Standard 1991. Abbreviations are the same for the singular and plural, e.g. cm for centimetre and centimetres, kg for kilogram and kilograms. Percentages are written in the text as per cent; the symbol %is restricted to tables. A full stop after an abbreviation is only used if there is likely to be confusion of meaning. Metric System: The Systeme International d'Unites (S.L) is to be used for expressing quantities. This is a coherent system of metric units derived from six basic units (metre, kilogramme, second, ampere, kelvin, and candela), from which are derived all other units, e.g. the unit of force is the newton (N) for kilogramms metre per second per second (kg m/s2). Always use the standard metric abbreviations. Commas must not be used for separating groups of digits. For ease of reading digits should be grouped in threes counting from the decimal point towards the left and the right. Illustrations: Drawings and diagrams are to be in black India ink and should be about 18 cm wide. When submitting graphical representations avoid a fine grid if possible. Curves should be in heavy line to stand out. Lettering too should be bold as a reduction in size is often involved in the printing process. (A single column is 8.5 cm wide.) Numbering of tables should be in Roman numerals: I, n, etc. and figures in Arabic numerals: Fig. 1, Fig. 2, etc. (Always use the abbreviation for figure.) Photographs should be black and white glossy prints. As a guide to the printer the author should indicate by means of notes in the typescript where tables and figures, etc. are to appear in the text. Paragraphs: A decimal system of numbering paragraphs may be used when the paper is long and complicated and there is a need for frequent reference to other parts of the paper. Proof correction: Galley proofs are sent to authors for the correction of printers' errors and not for the purpose of making alterations and additions which may be expensive. Should an author make alterations which are considered excessive, he may be required to pay for them. Standard symbols as laid down in British Standard 1219C should be used. SYNOPSIS It is most important that the synopsis should provide a clear outline of the contents of the paper, the results obtained and the author's conclusions. It should be written concisely and in normal rather than abbreviated English and should not exceed 250 words. While the emphasis is on brevity this should not be laboured to the extent of leaving out important matter or impairing intelligibility. Summaries simplify the task of abstractors and there. fore should present a balanced and complete picture. It is preferable to use standard rather than proprietary terms. FOOTNOTES AND REFERENCES Footnotes should be used only when they are indispensable. In the typescript they should appear immediately below the line to which they refer and not at the foot of the page. References should be indicated by super-script, thus. . .' . . .2. Do not use the word Bibliography. When authors cite publications of other societies or technical and trade journals, titles should be abbreviated in accordance with the standards adopted by this Journal. GENERAL The Council will consider the publication of technical notes taking up to three pages (maximum 3 000 words). Written contributions are invited to the discussion of all papers published in the Journal. The editors, however, are empowered by the Council to edit all contributions. Once a paper or a note has been submitted to the Institute, that document becomes the property of the Institute, which then holds the copyright when it is published. The Institute as a body is, however, not responsible for the statements made or opinions expressed in any of its publications. Reproduction from the Journal is permitted provided there IS full acknowledgement of the source. These points should be borne in mind by authors who may submit their work to other organizations as well as to the Institute.

By G. A. Wiebols, N. G. W. Cook, N. C. Joughin

Discussion R. E. Rarnes (Member): The original concepts and the pioneering work now brought to the practical test stage by the Mining Research Laboratory team deserve our highest praise. The authors of this comprehensive paper rightly stress the urgency of establishing the extent to which the apparent potential can profitably be realised in practice. It is to be hoped that adequate funds will be made available by individual mining companies, the Chamber of Mines and manufacturers to attract the necessary staff and maintain the high rate of achievement of the last two years. From the Seventy-Eighth Annual Report of the Chamber of Mines and its members we see that, in 1967, with a Working Revenue of R759.8 million from gold and R54.6 million pit mouth coal sales and with profits from gold and uranium and pyrite of R307.9 million, only R1.9 million was spent by the Chamber on all forms of Research. It is considered unlikely that the associated mining companies and manufacturers exceeded this investment expenditure. Assuming a total of R4 million spent by the industry on Research and Development, this is less than half of 1 per cent of sales of gold and coal. This percentage, so low in comparison to North America and Europe, is no worse than that of Exploration expenditure which, in 1967, with South Africa's total mineral production of R1,287 million, was estimated to have been R6 million (Pretorius 1968). In a primary industry with ever present depletion of ore deposits and with cost escalation, expenditure on Exploration and on Research and Development is not a risky luxury but a tactical obligation. The potential rate of return on research expenditure into rock breaking is high. Stores consumed by gold and coal mines, members of the Chamber of Mines, totalled R316.2 million in 1967. Except for purchased power costing R42.2 million the highest cost group was explosives, drills and drill steel totalling R33.8 million or 10.7 per cent of the total stores consumed. In the paper under discussion it is claimed that the low 'effective stoping width' should greatly reduce the likelihood of rock falls or rock bursts to the extent that permanent support can be dispensed with. Insofar as this narrow cut is only 12 in. in advance of the working area which, with a 10 in. channel, is unlikely to be much reduced in width from that achieved by current methods, this claim is not readily understandable. Were it to have been based upon the regional support gained from packed waste it would have been more acceptable. Pre-developed stope drives may give serious trouble at depth and for this reason it is questioned whether a stoping area can avoid periodic sub-development blasting-the spoil and fumes from which will interfere with the rock flow and continuous mining of the rock-cutter. If, in the mining method proposed by the authors, stope drives are cut as small as possible (6 ft by 6 ft) then 25 per cent of the total tons handled (excluding resued waste) and 5 per cent of the gold will be blasted conventionally in the stope. At this stage one cannot envisage tunnelling machines economically or practically capable of such work. The various methods described by the authors and subsequent contributors for breaking waste are most interesting. It was noted that the 'bull wedge' and 'explosives' in Fig. 1 of the paper were no further from the ideal point 'A' than was 'cutting'. The writer considers that the bold and imaginative steps taken by the Mining Research Laboratory Team, the mining companies and the manufacturers concerned will eventually lead to a successful rock cutting machine with universal application largely independent of rock type. This may take many years. In the meantime other methods of improving productivity of saleable metal by rock breaking teams should be investigated even if such methods have local applications only. In 1955 the writer conducted tests with a wire saw similar to those used in quarries in the Northern Transvaal and elsewhere. Jeppestown shale, the immediate footwall of much of the East Rand gold field, was cut at the rate of 6 in. per hour using sand, water and a special endless rope driven by a low h.p. motor. A hypothesis on its application was submitted to the Office of the Government Mining Engineer in 1955 and to other mining institutions in 1966 after the writer returned to South Africa. By inference, rope sawing was classed as less promising than other methods tested in the Orange Free State Goldfields (Parker 1969). With highly resilicified hanging and footwall quartzites this was not surprising and confirmed the writers findings when testing hanging wall quartzite from the East Rand in 1955. The relatively uniform conditions, the low strength, hardness, and silica content of the Merensky Reef platinum deposits (Gray and von Bardeleben 1969) and in particular, the existence of overlying Merensky pyroxenite (Cousins 1964) make this and the East Rand attractive areas for larger scale testing of wire saws. It is envisaged that in suitable rock types the 5/8 in. slot would be advanced down dip or down a minor dip. In undisturbed areas 'faces' of up to 200 ft in length could be cut several feet in advance of breaking which could then consist of light blasting to the second free face or some of the methods now being tested for breaking waste in rock-cutting operations. A wire saw is an inexpensive and simple machine which, in some areas, could make significant and early gains in rock breaking efficiency as well as in ground and stoping width control.

Jan 5, 1968

By J. N. Van der Merwe

Following the Coalbrook disaster in 1960, research into coal pillar strength resulted in the adoption of the concept of a safety factor for the design of stable pillars in South African coal mining. At the time when the original statistical analysis was performed by Salamon and Munro in the early 1960s, 27 cases of failed pillar workings were considered suitable for inclusion in the database of failed pillars. Pillar failure did not stop after the introduction of the safety factor formula by Salamon and Munro (1967). In the ensuing years, pillars that were created before the application of the formula deteriorated and later failed, as did ones that were created after the introduction of the formula. This means that over time, the database of failed pillar cases increased in size, allowing ever more reliable analyses to be performed. The number of failed cases in the database had grown from the original 27 in the 1960s to 86 by 2011. All the failed cases are contained in the updated database. The database of stable pillars, which is also used in the derivation of strength formulae, has now been extended from 125 to 337 cases. The new database of intact pillar cases is more complete as it bridges the time gap between the Salamon and Munro (1967) and the Van der Merwe (2006) databases. The original requirements for inclusion into the database were satisfied in the compilation of this latest collection. The characteristics of the original database of intact pillars did not change in a meaningful way. The mining depth and pillar dimensions of the new database are largely as they were in the original database. Time-related trends with regard to pillar dimensions and depth of mining could not be found, indicating that the geometrical parameters of coal mining in South Africa have not changed meaningfully in approximately a century of mining. The characteristics of cases in the updated database of failed pillars does not differ substantially from the one published by Van der Merwe (2006). The same difference between that database and the original Salamon and Munro database, namely that the average safety factor of the failed cases had increased dramatically, from 1.0 to 1.5, is still apparent. This may be due to the inclusion of more failures from specific areas that exhibit a disproportionate number of failures at higher safety factors. These areas are the Vaal Basin, Klip River, and Free State coalfields. The new database confirms yet again that there is no correlation between the safety factors of failed pillars and their time of failure. The safety factor on its own is thus not a reliable predictor of longterm stability of pillars. Keywords coal pillar, stable pillar cases, pillar collapse, pillar data base.

Nov 1, 2013

By C. A. Snyders

The research presented in this paper investigated the practical aspects of the recovery of platinum group metals (PGMs) from a dilute cyanide leach solution containing base metals, in a manner similar to that used for gold extraction in a typical CIP process, and focuses on both the adsorption and elution stages. The carrier-phase extraction of precious metals using activated carbon offers significant advantages over other processes in terms of simplicity, the high pre-concentration factor, rapid phase separation, and relatively low capital and operating costs. As a sorbent, activated carbon is still by far the most important material because of its large surface area, high adsorption capacity, porous structure, negligible environmental toxicity, low cost, and high purity standards. Adsorption tests were conducted on a pregnant alkaline leach solution (0.15 ppm Pt, 0.38 ppm Pd, 0.1 ppm Au) resulting from cyanide extraction performed in column leach tests. The initial adsorption rates of Pt, Pd, and Au were very fast and recoveries of these three metals were approximately 90 per cent after 2 hours, and 100 per cent for Pt, 97.4 per cent for Pd, and 99.9 per cent for Au after 72 hours. The parameters that influence the extraction of PGMs and Au were examined to assess their relative importance during the adsorption process in order to provide the basis for process optimization. The concentration of thiocyanate was not identified as significant factor for PGMs adsorption, while Ni concentration was the most significant extraction process parameter. Base metal cyanide complexes adsorb and compete with the PGM complexes for sites on activated carbon, and while copper adsorption can be minimized by adjusting the residence time, Ni adsorbs at approximately the same rate as the PGMs, influencing the loading capacity and adsorption kinetics of the PGMs. The feasibility of eluting platinum and palladium cyanide complexes from activated carbon using an analogue of the AARL process was investigated. Platinum and palladium elute from activated carbon almost to completion in 4 to 5 bed volumes at 80°C, while the elution of gold at this temperature is slow, with a significant amount of gold still to be eluted after 16 bed volumes. The equilibrium loading of gold is exothermic in nature (Fleming and Nicol, 1984) which will result in an increase in gold elution kinetics with an increase in temperature at similar pre-treatment conditions. A similar result was found for the elution of Pt and Pd. Cyanide pre-treatment was found to have a significant influence on PGM elution. Higher cyanide concentration in the pre-treatment step results in more efficient elution up to a point, and results suggest the possibility of an optimum cyanide concentration, beyond which elution efficiency starts decreasing due to increased ionic strength.

Jan 1, 2013

By C. F. Vos, J. D. Miller, J. C. Davidtz

"This work presents the potential for improving the flotation recovery of slow-floating sulphide minerals with the use of starvation dosages of a normal dodecyl (n-C12) trithiocarbonate (TTC) co-collector, together with a sodium isobutyl xanthate (SiBX) and dithiophosphate (DTP) collector mixture.At potentials below –150 mV (SHE), addition of nC12-TTC with SiBX improves the hydrophobicity of pyrrhotite, yielding captive bubble contact angles greater than those measured for SiBX or nC12-TTC alone, suggesting a low potential synergistic effect. This synergistic effect is further studied using Fourier transform infrared (FTIR) spectroscopy, the results indicating an increase in the surface concentration of the collector species when in a mixture. Thus, nC12-TTC with SiBX may act as an immobile surface anchor to which SiBX/SiBX2 molecules bond, increasing the localized concentration of collector species.Bench-scale flotation tests using mixtures of SiBX/DTP/nC12-TTC on a platinum group element (PGE)-bearing ore from the Bushveld Complex in South Africa confirm an improved metallurgical performance at very low substitutions (approx. 5 molar per cent) of SiBX. The improved recoveries for PGE, Cu, and Ni are correlated with improvements in the flotation kinetics of their slow-floating components. IntroductionShort-chain (less than C6) xanthates are very effective for the bulk flotation of sulphides (Fuerstenau, 1982), and early work (Leja, 1968; Gaudin, 1957; Plaksin and Bessonov, 1957; Taggart, Giudice, and Ziehl, 1934) indicated that the presence of oxygen in flotation slurries is necessary for the oxidation of the xanthate collector at the sulphide mineral surface to induce hydrophobicity. Fundamental research into the chemistry and adsorption mechanisms of xanthates over the years (Finkelstein and Poling, 1977; Woods, 1976; Winter and Woods, 1973) has revealed that for iron-bearing sulphide minerals, adsorption occurs predominantly through a charge transfer process. Oxidation of the adsorbed collector to the corresponding dimer takes place if the mixed potential of the system is greater than the reversible potential for dimer formation. In oxygenated slurries the rate of adsorption and oxidation of the collector depends greatly on the substrate surfaces. For chalcopyrite (Guler et al., 2005; Leppinen, 1990; Roos, Celis, and Sudrassono, 1990) and pentlandite (Hodgson and Agar, 1989) a two-step interaction with xanthate is proposed in which the chemisorbed xanthate is further oxidized to the dimer. The initial interaction of xanthate with pyrrhotite is through physisorption where xanthate physisorbs onto positive surface sites followed by oxidation to dixanthogen (Khan and Kellebek, 2004; Bozkurt, Xu, and Finch., 1998). This process is, however, slow and increased reaction time is needed to improve flotation recovery (Buswell and Nicol, 2002)."

Oct 1, 2018

By D. Rankin, H. J. Stucke, W. K. B. Loftus

SYNOPSIS Planning for the Finsch opencast mine is described with particular reference to the proposed stages of mining, the method used to determine the limits of surface waste rock stripping and the derivation of the waste rock mining rate. Actual mining practice is described and the possibility of installing a skipway into the open mine at a later date is discussed. In addition, the waste dumping policy is referred to: this includes the cutting of slots through the hill on the west side of the pipe to increase tramming speeds. The crushing, washing and recovery sections of the treatment plant are described together with the various changes being made to the circuit. The most important of these are the installation of X-ray sorters for the final recovery of + 7 mesh diamonds, and the vibrating grease belt for the recovery of - 7 mesh diamonds. INTRODUCTION The Finsch Mine, a subsidiary of De Beers Consolidated Mines, Limited, is situated approximately 90 miles west of Kimberley, and some two miles from the village of Lime Acres, in the Northern Cape. Lime Acres is a company village shared with the Northern Lime Company which operates a limestone quarry and works near the township. The mine is near the southern end of a well mineralized belt producing limestone, asbestos, diamonds, manganese and iron ore, and the whole area has developed rapidly in the last 20 years. Power for mining operations is drawn from the Electricity Supply Commission. The mine is conveniently close to the main Kimberley-Postmasburg railway line. Water is drawn from the Vaal River through a 57 mile State-owned pipeline at present temporarily operated by mine staff. DISCOVERY AND PROSPECTING OPERATIONS The diamondiferous orebody is situated on the farm Brits, which is State-owned ground that has been leased to the Company for the period of mining operations. There are indications of interest in the area by prospectors (Richter, de Bruin and others) over a period of some 30 years and the discovery would possibly have been made years earlier but for a law preventing prospecting for precious stones on State-owned land. Although the pipe formed a clear depression on the hill where it was situated, it was overlain by some 5 to 40 ft of banded ironstone rubble which was washed into the depression from the hillside above the pipe and obscured the deposit. In 1958, Mr Allister Thornton Fincham applied for, and was granted, the right to prospect for base minerals on the farm Brits. Asbestos is known to occur in the area and, initially, was Mr Fincham's primary interest. However, during the prospecting operations, garnets were discovered and it was realised that diamonds might be present. In 1960, when the Precious Stones Amendment Act was passed, a company

By Franz E. Pawlek

Synopsis This is a summary of investigations in the field of pressure leaching carried out at the Institute for Extractive Metallurgy of the Technical University of Berlin-West during the last seven years. The efficient dispersion of gas in a liquid and its dissolutions as well as the events at the phase boundary when leaching ZnS are reported. At the end two examples are given for the use of pressure leaching in the processing of smelter by-products. INTRODUCTION About 20 years ago, experiments were independently started in Canada and in Berlin on the subject of dissolving sulfidic ores without preliminary treatment by means of leaching under increased oxygen pressure. In Canada ammoniacal solutions were mainly employed, and F. A. Forward and his co-workers were successful in applying this process on a large industrial scale1, 2. This process is used in Fort Saskatchewan to produce about 15,000 tons of Ni per year. In Berlin, investigations were started on leaching with acid solutions3, 4. This process had also been used on a large industrial scale in the D.S.A., but the choice of unfavourable working conditions led to great difficulties, and to giving up this process for industrial use. Later on in Berlin work was carried out especially on the kinetics of pressure leaching 5, 6, 7, 8, 9 and its applications to the processing of smelter by-products, in particular of mattes and speisses10, 11, 12, 13, 14. The dissolution of ores and by-products can be subdivided into four steps: 1. the efficient dispersion of the gas, so that its dissolution occurs over as great a surface area as possible, since only the dissolved oxygen reacts with the solid, 2. the suspension of the solid, so that the entire surface can take part in the reaction, 3. the phase boundary reaction, 4. the removal of the reaction products. The first two steps belong to the field of process engineering and will be discussed from this point of view. The aim of these experiments15 was to find out first of all the limits of efficiency of self-sucking stirrers in solutions of low viscosity with regard to the mass transfer. In addition, the effect of ultrasonics in the same reaction system was studied. The experiments were carried out in a lucite container as shown in Fig. 1. Four baffles of 0.1 d width were in the stirring vessel. The height of these baffles was adjustable. For every experiment one litre of liquid was used. An infinitely variable direct current motor, which was fixed with a hollow shaft, served as the driving power for the stirrer.

By J. H. Viljoen, J. F. Morrison, C. H. Wyndham

SYNOPSIS Heart rates, oral temperatures, shovels/min and number of 3/4 ton cars/hour trammed over distances of up to 350 ft were measured in samples of 6-10 miners, engaged in tram-shovelling, at 76°, 84°, 86°, and 89°F wet bulb temperatures in stopes in a mine. From the results it has been concluded that a man with an 'average' maximum oxygen intake capacity of about 2. 8 litres/min should be able to work: at 6 shovels/min, or 30 cars/shift per two men, at 76°-84°F; at 5 shovels/min, or 27 cars/shift per two men, at 86°F; and at 4 shovels/min, or 24 cars/shift per two men, at 89°F wet bulb air temperatures. INTRODUCTION A number of gold mines in South Africa still use tram-shovelling extensively. In this method of rock removal from the face of the stope, Bantu mine workers load rock into cars and tram the cars to a centre gulley where they are emptied. Previous studies from this Laboratory3 have shown that tram-shovelling is one of the most arduous tasks underground. The rate of energy expenditure is relatively high, being an oxygen consumption of about 1.4 litres/min over a period of some hours. In cool air conditions the upper limit to the rate of production of the well-motivated men employed on tram-shovelling has been shown1 to depend upon their capacities for physical work of an endurance nature (as measured by their maximum oxygen intakes). However, in hot conditions the factors which set the upper limit to the rate of production are different. They are primarily the ability of the body to maintain a heat balance between the rate of heat production, due to physical work, and the hot atmosphere, so that the men do not develop excessively high body temperatures8. In order to give mine managers guidance on the 'optimum' rate of production of Bantu mine workers engaged upon tram-shovelling under different temperature conditions underground a study was carried out in a mine. The number of shovels per minute and cars per hour were recorded and heart rates and oral temperatures were measured throughout the duration of the shift on samples of 6-10 Bantu mine workers in different air conditions. The results of the study are recorded in this paper and conclusions are drawn as to the number of shovels per minute and cars per hour which Bantu mine workers of 'average' maximum oxygen intake capacity should be able to produce at wet bulb air temperatures of between 76° and 89°F without either excessive fatigue or danger of heat illness.

The industrial relations handbook, by A. Pons. Juta (P.O. Box 14373, Kenwyn 7790). 1989. "'"250 pp. Looseleaf binder. R180 + GST. Industrial laser materials processing. World Business Publications Ltd (4th Floor, Britannia House, 960 High Road, London N12 9RY, England). 1989. 180 pp. £310. Mining 1990. Longmans, Financial Times International Year Books, 1989. 592 pp. £90.00. Innovations in materials processing using aqueous, co/oid and surface chemistry, by F.M. Doyle, S. Raghavan, P. Somasundaran, and G.W. Waren (eds.). 300 pp. $125. Light metals 1989, by P.G. Camp bel (ed.). No. of pp. not available. $150. Process control and automation in extractive metalurgy, by R. Partelpoeg and D.C. Himmesoete. 225 $98. Process mineralogy VIl, by D.J. Carson and A.H. Vassiliou (eds.). 4oopp. $150. Super plasticity and super plastic forming, by C.H. Hamilton and N.E. Paton (eds.). 700 pp. $140. Supera/oys 1988, by S. Reichman, D. Duhl, G. Maurer, S. Antolovich, and C. Lund (eds.). 880pp. $99. Surface modification technologies, by T.S. Sudarshan and D.G. Bhat (eds.). 305 pp. $49. World survey of nonferous smelters, by J .C. Taylor and H.R. Traulsen (eds.). 365 pp. $90. Second Parsons International Turbine Conference. London, The Institute of Metals, 1989.270pp. £40. Mineral processing in the United Kingdom. London, Institution of Mining and Metalurgy, 1989. £25. Today's technology for the mining and metalurgical industries. London, Institution of Mining and Metalurgy, 1989. 623 pp. £60. 1989/1990 E&MJ international directory of mining. Chicago, Mining Information Services (P .0. Box 6500, Chicago, IL 60680, USA). 620 pp. US$95. Advances in project scheduling, edited by R. Stowinski and J. Weglarz. Amsterdam, Elsevier, 1989. 540 pp. Dfl. 270. Proceedings of the 3rd International Conference on Molten Slags and Fluxes. London, Institute of Metals, 1989. 335 pp. £38. Brochure on industrial screens. Obtainable from Philippe Lavernhe, Johnson Filtration Systems S.A., Z.I. Availes-en-Chatelerault, 86538 Naintre, France. 16 pp. Free. Numerical techniques, edited by P. Spiling. London, The Institute of Metals, 1989. 226 pp. £25. Phase diagrams of ternary iron aloys, Part 2, by V. Raghavan. New Delhi, Indian Institute of Metals, 1988. 360 pp. £95 (from the Institute of Metals, London). cas publications These publications are available from the Centre for Resource Studies, Queen's University, Kingston, Ontario K7L 3N6, Canada. Economic aspects of gold exploration: How much is too much, by B.W. Mackenzie and M. Dogget. 30 pp. $10.00. Mineral exploration and mine development potential in Ontario: Economic guidelines for government policy, by B.W. Mackenzie, M. Bilodeau, and M. Dogget. 180 pp. $25.00. Economic potential of base metal and gold mining in Newfoundland: Assessing the impact of regional developmentpolicy options, by B.W. Mackenzie, M. Bilodeau, and M. Dogget. 188 pp. $25.00. Publications of the AusIMM The folowing publications are available from The Australasian Institute of Mining and Metalurgy, P. O. Box 122, Parkvile, Vic 3052, Australia. Prepayment is required with al orders. The AusIMM 1989 Annual Conference 1989. $A 50. Mineral fuel alternatives and the greenhouse efect. July 1989. A$ 35. NQ gold '89. Apr. 1989. $A 50. Second Large Open Pit Mining Conference. Apr. 1989. $A 50. Explo '88. Nov. 1988. $A45. Mineral deposits of New Zealand, edited by Dr D. Kear. Monograph 13. 244 pp. $A 60. Field geologists' manual, compiled by D.A. Berkman. 3rd edition. 1989. : 350pp. $A45. The rocks speak. Essays in geology-some personal responses of a wiling listener, by Haddon F. King. 300pp. $A45.

Jan 1, 1990

COUNCIL The following served on Council during the year under review: Office bearers: Prof D. D. Howat (President), Dr J. P. Hugo and P. W. J. van Rensburg (Vice-Presidents), V. C. Robinson (Immediate Past President) and D. G. Maxwell (Honorary Treasurer). Ordinary Members of Council: H. P. Carlisle, R. C. Espley-Jones, G. H. Grange, Dr D. I. Legge, W. W. Malan, Prof R. P. Plewman, Dr R. E. Robinson, Dr M. D. G. Salamon, L. W. P. van den Bosch and P. A. von Wielligh. Branch Chairmen: A. Bain (Witbank-Middelburg Branch), J. M. Meyer (O.F.S. Branch). Past Presidents serving on Council: R. J. Adamson, M. Barcza, H. Britten, H. E. Cross, J. K. E. Douglas, R. C. J. Goode, P. Lambooy, Prof J. de V. Lambrechts, Dr J. T. McIntyre, J. F. Reid and H. Simon (until March 1972). Ten Council meetings were held during the year with an average attendance of nineteen, and the standing committees held 27 meetings. FINANCE The annual accounts which are attached to this report show an excess of income over expenditure of R21 519. It is very gratifying to be able to report that Council's efforts to stop the depletion of our accumulated funds are meeting with success. The most important contributors to our surplus this year are symposia and colloquia, sales of publications, Company Affiliate subscriptions and the profit on the journal. While we do not expect continued profits from all these sources in the future we do feel that we are now in the process of accumulating a substantial financial foundation. This will give the Council the necessary confidence to initiate the new developments in the activities of the Institute which are now under consideration. The decision to create a new grade of membership, Company Affiliate, is dealt with elsewhere in this report. There has been a generous initial response from companies and this is the cornerstone of our improved financial expectations. The MacArthur Forrest Memorial Fund shows an excess of income over expenditure of R91 and the total fund was, therefore, increased by this amount to R4 502. The balance sheet shows that the market value of quoted shares and debentures increased during the year from R9 160 to RH 331, which is R2 134 in excess of the book value. Accumulated funds now amount to RH 529 compared with R23 010 a year ago. MEMBERSHIP Sixteen Fellows, twenty Members, six Graduates, nine Associates, twelve Students and twenty-four Company Affiliates were elected during the year. One Member and two Associates were reinstated. Twelve members were admitted to retired membership. Transfers: Member to Fellow, three. Graduate to Member, seven Associate to Fellow, one. Student to Member, one. Student to Graduate, four. Student to Fellow, one. Your Council records with deep regret the death during the year of the following: Dr A. J. Orenstein (Honorary Life Fellow), R. A. Cooper, R. J. Spargo, H. Simon and F. Meyer (Life Fellows), S. D. Loxton, W. P. Arnold, G. C. Needham, W. G. Pyne-Mercier, J. Innes and O. T. Wright (Fellows), E. P. Mennell and O. B. Prentis (Members), J. Brits (Associate). After careful consideration of all the implications it was decided during the year to create a new grade of membership to be known as Company Affiliate, in order that there might be a formal and permanent channel for companies to contribute to the important work of the Institute. As recorded above, 24 companies had joined by the end of the year and many further applications have been received since. We extend a hearty welcome to all our new members. A comparative statement of membership as at 30th June, 1972, and the end of the previous year is shown in the following tabulation:-

1. Mining directory The mining directory, 1990. Mines and mining equipment companies worldwide. Don Nelson Publications Limited (P.O. Box 193, Barnet, Herts EN4 BLP, England).2. Mintek reports The following 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. There is also an annual-subscription scheme for reports - R400 locally (plus R52 GST) and US$400 (including airmail postage) abroad. The subscription covers al the unrestricted reports published between 1st April and 31st March of successive years, which usualy amount to between 20 and 30. Report M392 Computer programs for optimization by the modified simplex method, by G.L. Moore. Sep. 1989. 25 pp. R25 + R3,25 GST in South Africa; US $25 elsewhere. Report M393 The preparation and certification of fourteen South African silicate rocks for use as reference materials, by E.J. Ring. Sep. 1989.21 pp. R25 + R3,25 GST in South Africa; US $25 elsewhere. Report M395 The separation of trace elements in high-purity rhodium and iridium materials, by R.V.D. Robet and S.M. Graham. Nov. 1989. 10 pp. R25 + R3,25 GST in South Africa; US $25 elsewhere. 3. Publications from Trans Tech The publications listed in this section are available at the prices given from Trans Tech Publications, P .0. Box 1254, D-3392 Clausthal-Zelerfeld, West Germany. Handling of bulk solids. Theory and practice, by P.A. Shamlou. 1988. 200 pp., US$ 59.50. Acoustic emission lmicroseismic activity in geologic structures and materials, by H.R. Hardy and F.W'. Leighton. Vol. I: 1977, 490 pp., US$45.00. Vol. 11: 1980, 500 pp., US$45.00. Vol. Il: 1983, 680pp., US$6O.00. Vol. IV: 1989, 720pp., US$ 75.00. Open pit mine design models. An introduction with FORTRANI77 programs, by E. Alaphia Wright. Early 1990, approx. 200pp., US$75.00. Bucket wheel excavator, by W. Durst and W. Vogt. 988, 450pp., US$118.00. Continuois-surjace mining, by T.S. Golosinski and F.G. Boehm (eds.). 1987, 720pp., US$128.00. Mining-science and technology. 1987, 1430pages, US$ 118.00. Practical handbook for underground rock mechanics, by T.R. Stacey and C.H. Page. 1986, 150pp., US$ 38.00. Professional users handbook for rock bolting, by B. Stilborg. 1986, 150pp., US$38.00. The lighting of underground mines, by D.A. Troter. 1982, 220pp., US$48.00. Elements of hydraulic coal mine design, by M.L. Jeremic. 1982, 16Opp., US$38.00. Continuum theory of rock mechanics, by Cs. Assonyi and R. Richter. 1979, 365 pp., US$ 58.00. Shear and bond in reinforced concrete, by G. Florin.1980, 86 pp., US$ 24.00. Theory and design of surface structures: slabs and plates, by G. Florin. 1980, 222 pp., US$ 24.00. Mineral processing laboratory manual, by A.-Z. Abouzeid. January 1990, approx. 200pp., US$48.00. Weighing and proportioning of bulk solids, by Hendrik Colijn. 2nd ed. 1983, 4OOpp., US$60.00. Solid-liquid flow. Slurry pipeline transportation, E.J. Wasp et al. 1977, 240pp. US$ 58.00. Optimum pipe size selection, by C.B. Nolte. 1978, 304 pp., US$ 60.00.Field instrumentation in geotechnical engineering, T.H. Hanna. 1985, 854pp., US$98.00. The 1990 yearbook and directory. Powder and bulk solids handling and processing. 1989/90, approx. 300 pp., US$ 124.00.

Jan 1, 1990

By Alexandra Amiel

Tarkwa Gold Mine is owned by Gold Fields Ghana, IAMGOLD and the Government of the Republic of Ghana in a 71%, 19% and 10% ratio. The mine is operated by Gold Fields Ghana. This large, low-grade, open pit, gold mining operation is located in Tarkwa, in the Western Region of Ghana, approximately 320 kilometres by road, west of Accra, the capital of Ghana, West Africa. In the Financial year ended June 2007, the operation mined a total of 108 million tonnes of which 22 million tonnes was ore. The mined ore is processed through three gyratory crushers supplying two heap leach pads (North and South) and a carbon-in-leach (CIL) plant. Before the 6 Sigma project commenced, the current fragmentation was resulting in sub-optimal feed size to these crushers. It was decided to use 6 Sigma methodology to improve the fragmentation. A defect was defined as a fragmentation analysis indicating less than 95% passing 750 mm. The objective was to improve fragmentation in order to achieve a constant throughput to the north heap leach crusher of 1500 t/hr, a 5% increase in pit loading efficiency and a 50% decrease in rock breaker hours, equipment damage costs and in-pit sheeting costs respectively. However, this was not to be achieved at the expense of grade control as Tarkwa is exploiting a low grade, high volume deposit and therefore ore dilution must be kept to a minimum. This paper is intended to take the reader through the various 6 Sigma phases of the project (Define ? Measure ? Analyse ? Improve ? Control) which have resulted in a 10% reduction in loading times, of which half has been attributed to improved fragmentation, as well as a substantial increase in blasted stocks. The focus has been on both drilling and blasting parameters as both processes had to be taken into account. These parameters are technical but personnel factors were also identified and dealt with as they arose. In order to measure the impact of any change in the process parameters on the fragmentation size distribution, cameras have been acquired. One has been installed looking into the bowl of the north crusher and the other one was dedicated to field observation, of individual blasts. Both are used for on-going fragmentation analysis. At Tarkwa, mining efficiency is strongly dependent on good fragmentation as well as the presence of un-blasted ?toes? on the pit floors. Crusher throughput depends on an acceptable ore fragment size. Compliance to plan with regards to actual hole depths was temporarily monitored by manual hole dipping, but, this is now being replaced with a fully automated Drill Data Management system developed by Sandvik and Modular Mining. The Six Sigma methodologies, using control charts based on data collected in the field, allowed the mine to improve methods with regards to the control of blasted material. It also enforced the implementation of a quality control programme encompassing the entire Drill and Blast process.

Jan 1, 2008

By Z-P. Song, Z-B. Jiang, A-N. Jiang

"In deep excavations under conditions of high ground stress, even hard rock undergoes creep and other time-dependent effects that may result in instability. This study involves an analysis of the typical damage to the surrounding rock in the deep tunnels of the Jinchuan nickel mine in China. In order to understand the creep mechanism, triaxial creep laboratory tests were conducted under high stress. The creep characteristic curves and the Nishihara model parameters of typical rock were obtained from these tests. The numerical simulations, with which the creep model is developed, were performed using Flac3D. The creep model parameters were back-analysed on the basis of field monitoring data. Finally, appropriate support schemes for deep tunnels are suggested. The creep deformation of rock increases with time and axial load. At the same load level, the creep deformation of unloading is greater than that of loading. The simulated deformations of the surrounding rock are coincident with those from in situ monitoring, indicating the applicability of the presented rock creep model in situations of high ground stress. The results constitute a reference for support design in deep mining tunnels.IntroductionThe excavation of underground caverns can alter the natural stress field of the surrounding rock. In deep engineering projects under conditions of high ground stress, even hard rock shows obvious creep properties and time effects (Yao, 2005; Liu, 1994). The time effect of excavation not only causes decompression of the floor and increases sidewall stress, but also leads to stress concentration at the corners of the excavation, which influences the stability of the surrounding rock in a very complex manner.Many researchers have studied the creep properties of rock. ‘Griggs (1939) showed that creep occurs in sandstone, shale, and silty sandstone rock under the load of 12.5%–80% of the failure load.’ Subsequently, much research has been published on rock creep tests, including the uniaxial compressive creep test, the triaxial compressive creep test, the discontinuity rock shearing test, and field tests (Wawersik, 1974; Amadei et al., 1980; Okubo et al., 1991; Jin et al.,1995). A rheological model is used to describe the complex rheological deformation of material. This model is based on various fundamental parameters including rock elasticity, plasticity, and viscous properties, which can be combined into a constitutive model to reflect the rheological properties of various types of rocks. Wang et al. (2014) studied the creep– damage–rupture characteristics of rock salt by applying a creep-damage model. Munson (1997) developed a multi-mechanism constitutive model of creep of polycrystalline rock salt based on steady-state creep and modified it to incorporate transient creep through work hardening and recovery. An elasto-viscoplastic approach was developed to simulate the timedependent nature of the fracture zone (Malan, 1999). Rheological models were proposed to understand the collapse of iron ore mines in Lorraine by Dragan et al. (2003)."

Jan 1, 2016

By S. Budavari, F. M. C. C. Vieira

For several decades, the deep, gold-bearing reefs of the Witwatersrand basin have been mined predominantly according to layouts characterised by longwalls with strike pillars to provide regional support. During the past few years, a new generation of mining layouts has been introduced. These layouts are based on the concept of grid-type, scattered mining with dip pillars for regional support. As the extraction of the gold reefs extends to depths below 3500 m, the hazards associated with mining at these ultra-depths are expected to increase to unacceptable levels. Therefore, the question arises as to, which of the currently applied mining layouts is most acceptable for the economic and safe extraction of an ultra-deep orebody. The purpose of this paper is to describe a research investigation carried out to evaluate the degree of acceptability, from the rock engineering view point, of four currently used mining layouts for application at a depth-range of between 3500 and 5000 m. Pendant plusieurs décades, les filons d’or profonds du bassin du Witwatersrand ont été exploités d’une manière prédominante selon des dispositions caractérisées par des longues tailles avec des piliers directionnels pour donner un support local. Les dernières années ont vu la naissance d’une nouvelle génération de dispositions de mine. Ces dispositions sont basées sur le concept d’extraction type grille, éparpillée, avec des piliers au pendage pour le support local. Comme l’extraction des filons d’or va à des profondeurs en dessous de 3500m, il faut s’attendre à ce que les risques associés à l’exploitation à ces profondeurs extrêmes atteignent des niveaux inacceptables. Par conséquent, la question se pose de savoir laquelle des dispositions de mine couramment utilisées est la plus acceptable pour l’extraction rentable et sans danger d’un gisement ultra profond. Le but de l’étude présente est de décrire les recherches exécutées pour évaluer le degré d’acceptabilité, du point de vue d’ingénierie de roche, de quatre dispositions de mine couramment utilisées pour application à un rayon de profondeur entre 3500 et 5000m. Die tiefen, goldträchtigen Riffs des Witwatersrandbeckens wurden über einige Jahrzehnte hindurch vorwiegend nach jenen Layouts abgebaut, die von Langfrontstreben mit Schlagpfeilern charakterisiert waren, um regionale Unterstützung zu gewährleisten. Während der letzten Jahre wurde eine neue Generation von Grubenlayouts eingeführt. Diese Layouts basieren auf dem Konzept der Rasterfeld-Art, gestreuter Bergbau mit Neigungspfeilern für regionale Unterstützung. Es kann erwartet werden, daß auf Grund der Tatsache, daß sich die Extraktion der Goldriffs auf Tiefen unterhalb 3500 m verlagert, die Gefahren, die mit dem Bergbau an diesen Ultratiefen verbunden sind, sich auf ein nicht annehmbares Niveau erhöhen. Folglich erhebt sich die Frage, welche der gegenwärtig angewendete Abbaulayouts für die ökonomische und sichere Extraktion eines ultra-tiefen Erzkörpers am annehmbarsten ist. Zweck dieser Arbeit ist es, eine durchgeführte Untersuchung zu beschreiben, die vom Gesichtspunkt der Gesteinstechnik gesehen, vier gegenwärtig angewandte Abbaulayouts für den Einsatz in einem Tiefenbereich zwischen 3.500 und 5.000 m evaluiert.

Jan 1, 2003

By N. A. Barcza

This paper describes the development of large-scale thermal-plasma systems, which was motivated, in general, by the potential cost savings that could be achieved by their use as a replacement for the more conventional methods used in the generation of thermal energy. The anticipated cost savings arise not only from the use of plasma-generating devices but from the manner in which they have been interfaced with a furnace to process particular materials, mostly as fines. Thermal-plasma systems fall into two categories: non-transferred-arc and transferred-arc devices. In general, transferred-arc devices have been interfaced with open-bath furnaces in which melting or smelting processes carried out, while non-transferred-arc devices have normally been applied to shaft furnaces. Water-cooled transferred-arc devices are somewhat limited in power (about 5 MW) because of the relatively voltages (300 to 500 V) that can be attained in open-bath furnaces, where very long arcs are undesirable, and because only relatively low levels of current can be carried. Graphite electrodes can overcome the restriction current, and power levels of 30 to 50 MW seem feasible, even with one electrode, if direct current is used. Multiple water-cooled devices are capable of attaining similar power levels, but the capital costs are much higher. Costs due to electrode wear are lower for water-cooled systems, but expensive gases are needed for transferred-arc devices. Mintek conducted extensive pilot-plant work in which water-cooled devices were used initially but graphite electrodes were used subsequently to produce ferochromium from fines. Transferred-arc open-bath configurations were used. This work led to a decision by Middelburg Steel & Alloys (MS&A) to install a 16 MVA furnace of semindustrial scale to produce ferochromium aloys based on the ASEA d.c. arc furnace developed for the Elred process. Non-transferred-arc devices have atained reasonable scale-up to the 6 to8 MW power level, and high-voltage operation, which is inherent in such devices, has enabled lower currents to be used. Nevertheless, multiple systems are still necessary to accommodate large-scale applications, and this can be costly from a capital point of view. The cooling requirements are large, and can represent a considerable loss of electric energy. Shaft furnaces equipped with non-transferred-arc devices are suitable for the processing of materials that have volatile species, e.g. silica or manganese, or where the shaft is used to prereduce oxides that are amenable to gas-solid reactions. It is probably in the treatment of light and refractory metals that plasma technology will achieve its greatest development in the years to come. The energy requirements for the production of these metals are high, and very low oxygen potentials are necessary. These are factors that favour thermal plasma. Much developmental work is still needed in this interesting field. It should be remembered that electrically generated thermal energy is a unique temperature source that, in many instances, cannot be replaced technically or economically by the combustion of a fuel.

Jan 1, 1986

1. Book reviews Mill Operators' Conference. Parkville (Australia), Australasian Institute of Mining and Metallurgy, 1982. 425 pp. Reviewer: B. K. Loveday Off highway truck haulage. Newman Combined Group, the Australian Institute of Mining and Metallurgy and the Institute of Engineers in Australia. Sep. 1982. Reviewer: B. J. Vorster Environmental engineering in South African mines.Johannesburg, Mine Ventilation Society of South Africa, 1982. 974 pp. Reviewer: A. N. Brown Underground Operators Conference. West Coast Tasmania Branch. Australasian Institute of Mining and Metallurgy. Reviewer: D. R. Aspeling 2. New publications Electric steelimaking in the eighties: challenges and opportunities. Rotterdam, Balkema, 1982. 362 pp. $50.00 or £33. Tungsten: a review, by P. M. Harris and D. S. C. Humphreys. London, Institution of Mining and Metallurgy (Occasional Paper 2), 1983. Members: £3, nonmembers £6. The platinum industry - prospects in recovery. London, Shearson{American Express Ltd (St. Alphage House, Fore Street, London EC2Y 5DA), 1983. £75. The best of E&MJ mining and processing idea book' New York, Engineering and Mining Journal, 1983. 128 pp. Free with subscription to Engineering and Mining Journal. Mining 1983. Harlow (U.K.), Longman Group Limited, 1983. 500 pp. £39.50. Ooncise guide to world coalfields. London, World Coal Resources and Reserves Data Bank Service (14/15 Lower Grosvenor Place, London SW1W OEX), 1983. 380 pp. £45. 3. Canadian publications Asbestos, by G. O. Vagt, 9 pp. Ooal and Coke, by J. A. Aylsworth, 16 pp. Orude oil and natural gas, by R. L. Thomas, 12 pp. Phosphate, by G. S. Barry, 8 pp. Rhenium, by S. A. Hamilton, 3 pp. 4. Mintek reports Report 2102D The recovery of magnesite from dump fines from the Strathmore Mine. (First issued Feb. 1981.) Report 2106D The evaluation of drill cores and a bulk sample from a deposit of andalusite near Thabazimbi. (First issued Mar., 1981.) Report 2108D Evaluation of a grinding aid in batch grinding, classification, and gravity concentration. (First issued Jul. 1981.) Report 2109D The evaluation of an andalusite deposit from Kleinfontein, Groot Marico. (First issued Apr. 1981.) Report M7D The beneficiation of chromite ore from the Ma-l seam near Marikana. (First issued Nov. 1981.) Report M62 A preliminary investigation into the extraction of zinc by direct oxidative leaching of high-manganese sphalerite. Report M76 A mineralogical investigation of a refractory gold ore, and of a sulphide concentrate and calcined tailing from that ore. Report M85 List of unrestricted Mintek publications issued from 1966 to 1982. Report M97 Reduction in metal consumption by the use of alternating lines of higher and lower lifter bars in a rod mill. Report M98 Multivariable control and optimization of the operation of a milling circuit at East Driefontein Gold Mine. Report M101 The potentiality of heat-treated balls in the grinding of gold ores. X-ray diffraction The Southern Transvaal Section of the South Mrican Chemical Institute is to present a mini-course on 'X-ray Diffraction: Theory and Application' in Johannesburg on 18th and 19th October, 1983.

Jan 1, 1983

By W. J. Jordaan

The ability of soils to retain and hold cations is called the cation exchange capacity (CEC). Adsorbed cations, however, can be replaced by other cations through the process of cation exchange. Heavy mineral deposits contain a significant portion of slimes including the very fine clay minerals. In most circuits the slimes fraction hampers efficiency and has to be removed during early stages of the process. Being a nonvaluable process stream, the processing of the slimes is a costly exercise. In thickening applications it might be possible to manipulate the ability of clay minerals to retain and hold positively charged cations in order to optimize flocculation and therefore reduce flocculation costs. The CEC value of the slimes could be a measure of this possibility. To investigate this hypothesis, different slimes samples were characterized for size, chemical composition and clay minerals present. The CEC value of each sample was determined and explained in terms of the mineral phases present. Settling tests were conducted and an attempt was made to explain the CEC characteristics of the clay minerals in terms of settling rate. The scope of this investigation was to test the hypothesis and should not be seen as an in-depth study of the subject matter. A greater number of samples and detailed analyses to identify and quantify minerals and phases present would be required to investigate further the relationships between clay minerals in the deposit, CEC and settling rates. Location and geological setting Exxaro KZN Sands is mining a heavy minerals deposit at Hillendale mine located at Richards Bay, South Africa. The orebody consist of a dune some 8 km inland from the coast to the north of eSikhawini. A geological synopsis undertaken by Botha1 concluded that the Hillendale mining area represents a coastal dune sequence that accumulated north of the Tugela River. The northward movement of sediment by long shore drift currents result in a high sand budget on the beaches north of the river youth and is the dominant contributing factor to the accretion of the coastline and development of parallel dune systems along the coastal zone in this area. Beach swash zone processes and enrichment of the fine sand fraction occurs during wind transport off the beach by ascending parabolic dunes that form the coastal barrier dunes. This process results in heavy mineral concentration on the windward dune face and localized enrichment parallel to the dune forms. The aeolian sedimentary facies processes result in the primary concentration of higher grades in the upper silt-enriched reddish brown horizons of the profile. The synopsis by Botha1 further showed that an additional component of heavy mineral concentration can be ascribed to the post-depositional relative enrichment of heavy minerals due to weathering. Therefore, it is likely that the Hillendale orebody protolith was pedogenically weathered to form the homogeneous, silt-enriched, clayey reddish brown to dark red, palaeosol profile that grades downwards into yellowish brown, less clay-enriched sand. Slimes characterization Samples The Hillendale orebody was divided into geochemically discretized zones based on the concentration of ilmenite and other specific minerals and/or phases. Six composite samples were made up from exploration samples taken from Zone 9, Zone 11 and Zone 12. The red and orange horizons within these composite samples were separated and test samples were prepared to conduct test work and analyses. The test samples were submitted for preparation and analysis to characterize the slimes properties. Each test sample was deslimed at 45 µm representing the slimes fraction (-45 µm) and dried at 40°C. The -45 µm slimes samples were then split to conduct size analysis, chemical analysis, XRD and to determine the CEC. Size analysis The size distribution of the composite samples is shown in Table I. The size analysis shows that there is a difference in size distribution between the orange and red horizons of each zone. The orange horizons contain less 850 µ material as well as less slimes (-45 µm). The red horizons contain yore slimes (-45 µm). The size distribution of the slimes fraction (-45 µm) was determined using Malvern size analysis. The cumulative particle size distribution of the slimes is shown in Figure 1. The red horizons of the different zones show similar size distributions. The orange horizons show some differences. However, there is a difference in size distributions between the red and orange horizons.

Jan 1, 2007

MEMBERSHIP In terms of By-laws7.7.1 members are hereby notified that the membership of the following has been cancelled and their names removed from the Membership Register: H. Digby Roberts, R. J. P. van Tonder, S. D. Williams (Members), A. I. de Klerk, M. F. Ford, A. W. Hine, H. A. Johnston, R. T. Joyner, H. D. Small, P. White (Associate Members), J. de F. Agrella, A. Leibowitz (Affiliates), J. P. M. Maidment, C. P. J. M. Steyn (Graduates), H. C. M. Fourie, B. C. P. Job, J. P. Kruger, E. C. Nicolas, A. P. Prinsloo, B. Schuitema (Students). INSTITUTE PUBLICATION Transactions of the Seventh Commonwealth Mining and Metallurgical Congress Requests are still being received by the Institute for sets of the above transactions. Members who wish to dispose of sets in good condition are requested to contact the Secretary, P.O. Box 1183, Johannesburg or 304 Kelvin House, Johannesburg. As these are for resale a price of not more than R10.00 can be offered per set of three volumes. INTERNATIONAL SOLVENT EXTRACTION CONFERENCE, 1971 The Society of Chemical Industry has agreed to sponsor an International Conference devoted to the science and technology of solvent extraction. This will be held in The Hague in the Netherlands during the week commencing 19th April, 1971. The organisation of the Conference will be in the hands of a Conference Committee under the chairmanship of Mr B. F. Warner. The emphasis of the Conference will be on technical solvent extraction of both inorganic and organic substances, including basic principles and practical applications. Sessions are envisaged covering the chemistry of solvent extraction, industrial processes and economics, the performance of contacting equipment and the underlying phenomena involved, and the response characteristics and control of such units. The Conference Committee will welcome offers of papers for presentation at the Conference. In the firts instance, intending authors should submit a preliminary title and an indication of the scope of their contribution to the Conference Secretary: Dr. C. Hanson, University of Bradford 7, U.K. It is hoped to have available in September a first circular giving further details of the Conference. Copies may be obtained from: International Solvent Extraction Conference, 1971, 14, Belgrave Square, London, S.W.1. SOUTH AFRICAN TUNNELLING CONFERENCE TO BE HELD IN 1970 A South African Tunnelling Conference, to be known as TUNCON 70, is to be held in Johannesburg during the latter half of July, 1970. South Africa, in common with other countries, has a vital and growing interest in tunnelling. Apart from the 800 kilometres of tunnel excavated annually in the gold mines, the 82 kilometre-long Orange-Fish Tunnel is being driven to carry water from the Orange River to the drier areas of the Eastern Cape Province. This and the realization that services such as water and transport are increasingly being carried underground in various parts of the world have emphasized the need for a forum at which the technology and potential of tunnelling can be discussed. TUNCON 70 is being supported by three professional engineering societies representing some 6,000 engineers, namely, the South African Institute of Mining and Metallurgy, the South African Institute of Civil Engineers and the South African Institution of Mechanical Engineers, as well as by the Geological Society of South Africa. The conference has three main purposes. Firstly, to pool and exchange expertise by authorities on tunnelling; secondly, to discuss future developments in tunnelling technology with the aim of making those concerned with long-term planning aware of the potentialities of tunnelling; thirdly, to propose standards for tunnel shapes and sizes. Adoption of standards for tunnelling equipment and accessories would be a major step forward in improving tunnelling efficiency. The five themes of the conference will be: tunnel utilisation, exploration, design, construction and standards. The conference will be held at the University of the Witwatersrand, Johannesburg, from 21st to 24th July, 1970. Arrangements will be made for visits to be paid to mines and tunnelling projects before the start of the conference. Further information is obtainable from the Organising Committee, TUNCON 70, P.O. Box 1183, Johannesburg, South Africa.

By D. Borman

The location of underground positions in mines has usually fallen to their survey department's. Their usual tasks include: ? installation of a high-precision peg network like the National Survey grid as beacons ? offset measurements to the sidewalls, and sometimes hangingwall and footwalls, of development tunnels and excavations ? offsetting of stoping panels for the calculation of face ? advance and the square meterage of area removed. Other departments build their observations into the plans produced by the surveyors. If more precision is required, they ask the surveyors to `elevate' their points with a theodolite. Apart from the survey peg network and `elevations' these measurements are usually planer measurements suitable for producing plans, sections and projection sheets. When the only representation medium was a sheet of paper or transparency, this was perfectly suitable. However the development of CAD models of the workings has changed all this. Full 3D representation is not properly catered for in the tool sets in current use, and needless hours are spent converting analogue-type observations into digital form. The basic survey models need to be augmented by the observations of other disciplines that are also required to locate positions underground. These include: ? the need for geologists to plott their mapping and ? borehole logs into 3D space ? the need for samplers to position their sample points accurately because the geostatistical models are biased and inaccurate ? the need for stoping width recorders to position their thickness observations to prevent errant evaluation and bonuses ? the need for rock engineers to place their mappings into 3D to build true geotechnical models to manage geotechnical stresses ? the need for production officials to receive updated face ? positions during the month so that they can manage the ? production and utilize their resources properly. This paper covers a new method of positioning profiling points to a suitable degree of accuracy. I believe the method is sufficiently simple and cheap for all to use. Historical methods Platinum and gold orebodies, especially in South Africa, are generally narrow tabular deposits. This made them suitable for depicting on a 2D medium like paper. The determination of stoping or face widths was not a problem, as the ore is removed in a single stoping process. Such 2D representations could be easily positioned using tape offsetting between survey pegs or points tied in from survey pegs. Problems of dip were handled by using 'Stope Sheets' which chose a best fit projection for the whole area depicted or by using true dip section sheets for inclined tunnels. Rolling reef and potholes were the common areas of difficulty. Most mines now model their orebody and plan the extraction in computer graphics. This means that the representation of the current workings has to change to support this trend. It now becomes a truly 3D problem. Mining officials find it inconvenient to have their actual workings in single-line depictions while their orebody is depicted with top and bottom contacts and the planned tunnels in 3D shapes. Geological models which form the basis for the resource model and planning process are often out of date, as the updating process is slow. The geological mapping has to be plotted onto sections and plans. These are then digitized into graphics by a draughtsman and checked by the geologist. Only then does the interpretation and model update take place. Potential methods to create 3D 'Actuals' Global positioning systems (GPS) Surface mines have been blessed by the advent of GPS technology. These simple-to-operate pieces of equipment and compatible software make it possible for all types of mine employees to locate themselves, and therefore to locate their observations. GPS are often inexpensive and give an acceptable degree of accuracy. Only in deep pits or close to the highwalls are observations hindered. Such technology cannot however, work underground. Ground penetrating radar (GPR) GPR is reported to be very useful for estimating the positions of potholes and faults. However it is still considered as providing an estimate, not a definite measurement. GPR is good for seeing into solid rock, not into open spaces. Inertia reading devices Experiments with inertia reading devices have been conducted on the mines. They were the forerunners of GPS for military guidance systems, and were even used for city navigation in the early 70s. They do however work best with heavy or fast-spinning gyros. Anglogold Ashanti's attempt to use them were discontinued in the mid-90s when the developers asked for an additional few million rand for a device that would weigh more than 12 kg and have a limited operational life.

Jan 1, 2006

COUNCIL AND STANDING COMMITTEES - 1973-1974 Office Bearers: P. W. J. van Rensburg (President), Professor R. P. Plewman and Dr R. E. Robinson (Vice Presidents), J. K. E. Douglas (Honorary Treasurer), and Dr J. P. Hugo (Immediate Past President). Elected Members of Council: Dr M. G. Atmore, G. H. Grange, Dr P. R. Jochens, J. G. Kirchner, Dr D. I. Legge, W. W. Malan, Dr M. D. G. Salamon, L. W. P. van den Bosch, D. A. Viljoen, P. A. von Wielligh. Branch Chairmen: B. T. Hosking (Witbank-Middelburg Branch), E. T. Wilson (Orange Free State Branch). Past Presidents Serving on Council: R. J. Adamson, M. Barcza, H. Britten, H. E. Cross, Professor J. de V. Lambrechts, R. C. J. Goode, Professor D. D. Howat, D. M. Jamieson, D. G. Maxwell, Dr J. T. McIntyre, V. C. Robinson. Ten Council meetings were held during the year, with an average attendance of 19, and the standing committees held 30 meetings. COMMITTEE CHAIRMEN Membership, Dr R. E. Robinson ; Metallurgical Colloquia, Dr R. E. Robinson ; Mining Colloquia, L. W. P. van den Bosch; Awards, P. W. J. van Rensburg; Excursions, P. A. von Wielligh; Dinner, G. H. Grange ; Constitution, Rules and Policy, Dr J. P. Hugo; Adjudicating, P. W. J. van Rensburg; Mines and Works, W. W. Malan; Education, Dr J. P. Hugo. REPRESENTATIVES ON OTHER BODIES Associated Scientific and Technical Societies: Members : V. C. Robinson and D. G. Maxwell Alternates : P. W. J. van Rensburg and Dr J. P. Hugo. Federation of Societies of Professional Engineers Members : J. K. E. Douglas and P. W. J. van Rensburg Alternates : Dr J. P. Hugo and G. H. Grange. South African Council for Professional Engineers Members : R. C. J. Goode and J. K. E. Douglas Alternates: G. H. Grange and Dr R. E. Robinson. Engineers' Liaison Committee (Pretoria): Member: Professor J. de V. Lambrechts Alternate : Dr J. P. Hugo. MEMBERSHIP Seventeen Fellows and Members, twenty-three Graduates, ten Associate Members, twenty-two Associates, thirty-four Students, and seven Company Affiliates were elected during the year. Eleven Fellows and four Members were admitted to retired membership. Five Fellows were elected to Honorary Life Membership. Four Members, two Graduates, and one Student were transferred to Fellows ; eleven Graduates and Students were transferred to Members ; eight Students to Graduates; and four Students to Associates. A statement of membership as at June 30th 1974 and the end of the previous year is given in the following tabulation 30th - 30th June, - June, 1973 - 1974 Honorary Life Fellows 4 - 9 Honorary Fellows 9 - 8 Life Fellows 177 - 170 Fellows 536 - 544 Members 487 - 512 Associate Members - - 10 Graduates 128 - 130 Associates 186 - 194 Students 183 - 173 Company Affiliates 64 - 70 1 774 - 1 820 OBITUARIES Your Council records with deep regret the death during the year of the following members : Dr P. N. Lategan and Dr O. A. Jackson, Honorary Life Fellows and Past Presidents; C. Airth, T. L. Blunt, J. B. Dennison, A. E. Frazer, C. L. Lamb, V. O. Reid, K. Richardson and D. G. Roberts, Life Fellows ; H. F. Allan, J. T. Beaumont, M. Eisenstein, J. C. Hall, C. F. Louw, H. H. McGregor, R. Murchison, and J. E. Williamson, Fellows; and R. B. Miles, Associate. FINANCE The annual accounts, which follow this report, reflect a healthy position and show that measures taken by Council over the last few years to boost income have been successful. A higher income was needed not only to meet rising costs but also so that the services provided by the Institute for its members could be expanded. This year's income of R55 025 showed a further increase compared with last year's figure of R48 307. Income from subscriptions was higher mainly owing to an increased number of Company Affiliates, and this is indicative of the support given by mining and metallurgical companies to the good work being done by the Institute. Further sales of publications of the symposia held over the last few years again made a useful contribution to income of R4560. The first Winter School held in 1973 yielded a surplus of R7495 after the expenses had been deducted from the income received from registration fees. The cost of administering the Institute increased by R2212 compared with the previous year. Included in this was a donation of R1000 to the A.S. & T.S. Trust Fund. The cost of publishing and printing the Journal increased by R2034, but advertising and extraneous sales of the Journal were higher, with the result that the net cost of the

Jan 10, 1974