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By N. Kernahan, T. Zaniewski

Threshold blasting involves the use of small amounts of high explosive to break and fragment hard rock without having to evacuate mining personnel. The method is easily assimilated and effective in rockbreaking, but requires rigid control on drilling, charging and timing. Current underground trials are aimed at fine-tuning the amount of explosive energy and blast hole geometry to allow the firing of multiple sets of shot holes in a continuous manner. Through correct procedures, the after-blast fumes, dust and fly rock can be contained so as to provide a safe working environment. Threshold blasting hugely reduces the volumes of explosives used in mining and brings to maturity the potential of the process begun by Alfred Nobel when he introduced nitroglycerine, and later dynamite, to mining. Its key contribution is its enabling of continuous mining operations with well understood and relatively low cost technologies. The use of batch blasting, employing large burdens holds the greatest potential for delivering high flow rates of ore at minimal cost. There is good potential for rapid evolution of the concept.

Sep 1, 2001

By Monica M. Cole

The Empress nickel/copper deposit west of Gatooma in Rhodesia occurs within gabbro and amphibolite, disposed at the contact of a granodiorite stock (Barebottom Hill) and the surrounding greenstones of the Archaen Bulawayan System. The orebody has a pipelike form and a poor surface expression due to plantation of the area by Miocene (Africa) and later Victoria Falls erosion cycles. Barebottom Hill represents a monadnock remnant in the geomorphological surfaces while traces of the once larger Empress orebody have been removed. Limitations in soil geochemistry necessitated both studies of the vegetation ecology and the biogeochemistry of the area, both of which were anomalous. The use of geobotany was found to be restricted but biogeochemistry offers a most effective prospecting tool and was found to define the sub-outcrop of the ore-body more precisely than soil geochemistry since these methods reflect and differentiate anomalies emanating from bedrock mineralisation and those due to surface phenomena.

By J. C. Coetzee

In this article, a case is made for the importance of the transfer and management of tacit knowledge to ensure continued sustainable competitive advantage within the pyrometallurgical industry in South Africa. The state of knowledge management (KM) is assessed through a theoretical and empirical study. The empirical part of the study was conducted by means of a survey questionnaire. An important prerequisite within the research entailed determining the current state of KM within the pyrometallurgical industry, and the findings are presented throughout this article. The research argues for initiatives to address the high turnover of pyrometallurgical knowledge workers. This industry needs to entrench tacit knowledge and therefore address the problems associated with the continuous loss of inherent specialized knowledge. Appropriately, emphasis is placed on identifying initiatives required to embed and retain not only human capital lost through mobility, but rather retaining tacit knowledge through a practical KM framework.

Jan 1, 2012

1. Book review The geology of some northern Nigerian anorogenic ring complexes, by J.N. Bennet, D.C. Turner, E.C. Ike, and P. Bowden. The British Geological Survey: Overseas Geology and Mineral Resources, no. 61. London, HMSO, 1984. 66 pp. Reviewer: R.H. Ingram 2. Mintek reports Report M226 The separation of tungsten and molybdenum by the formation of sulphide complexes and extraction into a weak-base resin. Report M228 The solvent extraction of zinc, iron, and indium from chloride solutions by neutral organophosphorus compounds. Report M230 Shear flocculation of fines for improved flotation. Report M239 A mineralogical study of residue from the column leaching of a low-grade nickel-copper sulphide ore.3. Recent publication Driger Review, special edition, act. 1985. 48 pp. (Copies obtainable from Roly Nyman, HAMPO PMIE Division, P.O. Box 170, Joham1esburg 2000.) Black Mountain's achievement The 13 689 t consignment of metal concentrate that was loaded aboard the bulk carrier 'George' and shipped out of Saldanha Bay early in December brought the number of tons exported from Black Mountain via the Sishen-Saldanha railway and harbour system to one million.

Jan 1, 1986

By S. K. De Kok

Over a period of three years, since samples first became available, laboratory and pilot plant experiments have been conducted to develop a method of treatment to recover copper and zinc in saleable grades of concentrates from the Prieska complex sulphide orebody. These experiments have been based on adaptations of principles investigated by research workers and applied to similar ore types throughout the world. The differential flotation process finally worked out involves a comparatively coarse grind, flotation of the copper at near-neutral pH with the use of a zinc-cyande sphalerite depressant, followed by flotation of the reactivated sphalerite. This procedure has had such success that the construction of a full-scale plant is proceeding with confidence that the small-scale operations will be duplicated or improved upon. It is to be expected that the large plant will follow the pattern of almost every flotation plant that has been built in that modifications to the circuitry and reagent systems will be made as experience is gained.

Stochastic methods are normally invoked / used to assist with the understanding of risks, when there is uncertainty around a particular outcome. Uncertainty implies that there is a risk that the desired outcome will not be realized. Stochastics and probability theory has long held out the promise to answering this need, but has often been maligned because of its misuse. This paper takes a critical look need for Monte Carlo simulation to project risk evaluation and highlights what is considered to be the fundamental issues that should be thoughtfully considered to avoid the abuse of this technique. The upside of avoiding the abuse of this technique will be the wider acceptance by practitioners that it is a credible technique to quantify this important aspect of valuation.

Jan 1, 2007

By M. Cortie, L. Iorio

The amount of nitrogen contained in an austenitic stainless steel affects its properties significantly. The maximum content of nitrogen feasible in a range of experimental low-nickel austenitic stainless steels containing significant additions of copper is evaluated The nitrogen content is calculated based on published interaction coefficients, and by use of the FACT thermodynamic computer program and database. The differences between the two methods of prediction can be attributed to inaccuracies in the published interaction coefficients. The calculated nitrogen contents of some experimental alloys are compared with the actual nitrogen contents obtained when the alloys were produced in an induction furnace. The actual nitrogen contents obtained were higher than those predicted by either method, and this is believed to be due to a super saturation of nitrogen occurring in the melt, which was not relieved during the short period in which the charge was molten. It was evident that the experimental alloys can contain between 0,25 and 0,40 per cent nitrogen (depending on temperature, composition, and nitrogen pressure) when melted in a sealed induction furnace, and this is more than adequate for the purpose of forming and stabilizing the austenite phase.

Jan 1, 1994

By Z. Weisheng

The lift system is the main part in manganese nodule mining on the ocean bed. It connects the nodule collection system (miner) with the surface platform (mining vessel) and transports the nodules from the ocean bed to the surface. China started the research on lift technology in deep ocean mining in 1991, and a slurry pump hydraulic lift method has been developed for the nodule mining system. The detailed slurry pump hydraulic lift experiments have been undertaken with crushed nodules in the vertical pipe. The lift parameters to lift coarse particles in the lift pipeline have been discussed, including the pressure drop, the solid concentration, and the mixture velocity. The author of this paper not only took part in all these studies on the lifting technology, but was also responsible for some of this research. This paper will present the component parts of the lift system and the research results of coarse particle mixture flow in the vertical lift pipeline. Keywords: deep sea mining, slurry pump lift, lifting parameters.

Jan 1, 2007

By S. M. Spottiswoode, A. J. Jager, N. C. Gay, J. A. Ryder

The South African mining industry is at present planning to extract orebodies at depths of up to 4 km. To do this cost effectively and, at the same time, ensure safe working conditions for mining, the personnel will require both the development of new strategies and the implementation of current rock-engineering technological developments on a wide scale. This paper covers most of the technological developments likely to be required for mining at very high stresses, but it is clear that improved regional support systems will need to be developed to ensure defective stability of the rockmass during mining operations. Similarly, it is clear that improved strategies for mining in large-scale geologically disturbed areas, where slip on faults or dykes can result in wide-spread rockburst damage, will have to be addressed

Jan 1, 1995

By M. W. Hildyard, J. A. L. Napier

The improved design of support systems and stoping strategies when changes in depth, stratigraphy, or mine layouts are considered must rely on the designer's fundamental understanding of the deformation mechanisms adjacent to underground openings so that he can extrapolate and predict expected mining conditions. This paper presents a numerical approach to the modeling of the growth and interaction of mining-induced fractures near the edges of deep tabular excavations in brittle rock. Fractures are represented by displacement-discontinuity elements that are allowed to propagate according to prescribed growth rules. This procedure is justified by the reproduction of several features observed in laboratory simulations of fracturing around openings in blocks of rock subjected to uniaxial and biaxial compression. An attempt is then made to explain some of the attributes of the fracture zone surrounding tabular stopes. Particular questions of interest are the sequence in which fractures form and are mobilized in front of the mining face, the effect of parting planes parallel to the plane of the excavation, and the distribution of stress parallel to the hangingwall and footwall.

Jan 1, 1992

By X. M. Prevost

A computer system to store, retrieve and process coal borehole and analytical data together with other geological, geographical or topographical information is described. As a result of the large volume and variety of data stored since its inception in 1979, as well as the basic versatility of the system, the National Coal Data Base has been performing a number of new tasks for which it was not originally designed. As considerable sets of data are used on almost every project, the use of statistical application programs has become an important processing tool.

Jan 1, 1987

By D. D. Howat, J. van der Colf

This paper is the first in a series of three dealing with this subject and also with the rate of oxygen removal from the slags in the presence of solid carbon and with the physicochemical properties of the reduced slags. For selected members of the system, the melting temperatures and primary crystallization products were determined. as were the viscosity and the electrical resistivity of the corresponding melts. All the experiments were conducted in a neutral atmosphere. Where determined, the primary phase was found to be either perovskite or magnesium aluminium titanate. The composition variable exerting the most pronounced influence on viscosity or resistivity was found to be the basicity expressed as the mass ratio (CaO + MgO)jSiO,. The ratio CaOjMgO became important only at Iow basi<:ity values. Although generally there is a direct proportionality between log (viscosity) and log (resistivity), slags h&apos;lving either a very high silica content or a very high titania content have anomalously Iow electrical resistance.

Jan 1, 1979

By S. K. Lahiri, K. C. Ghanta

Design of industrial slurry pipelines is usually performed by applying semi-empirical procedures, requiring a significant experimental study for each project. The mechanisms of suspension flow are not yet completely understood and existing predictive models cover only some aspects of uniform or closely graded particle slurry flows. This paper presents a computational technique for prediction of the velocity and concentration profile in slurry pipelines based on computational fluid dynamics. This model gives numerical solutions for the concentration and velocity distributions in the pipeline cross-section. The model prediction and experimental concentration and velocity profiles were found to be in good agreement. Keywords: pressure drop; concentration profile; particle diffusivity; slurry flow.

Jan 1, 2007

By G. A. Bezuidenhout

Lonmin Platinum installed a concentrated mode dual-alkali scrubber at the smelter in Marikana in 2002. The dual-alkali scrubber was the technology of choice at that time as a sulphur fixation plant, due to the perceived benefits of handling both the high SO2 concentrations of converter off-gas and the swings in SO2 concentration that are linked to Peirce-Smith operation. Owing to current and impending legislative requirements for air quality and waste, Lonmin is currently considering additions to the dual-alkali plant, but is also evaluating alternative technologies for sulphur fixation. This paper reviews the decision of Lonmin to install a concentrated mode dual-alkali scrubber and presents plant performance achieved. It also describes the important control variables and sensitivities of the plant, and the final product that is produced by the operation of the plant. The legislative requirement that drives the Lonmin technology evaluation is also discussed.

Jan 1, 2012

1. Book review Assay and analytical practice in the South African mining industry, byW.C. Lenahan and R. de L. Muray- Smith. Johannesburg, The South African Institute of Mining and Metalurgy, 1986. RlOO (R80 to Members). Reviewer: N.G. Randolph 2. Canadian publications A market profile for industrial minerals in Canadian manufacturing sectors, by M. Prud&apos;homme and D. Francis. 1987. Micromedia Limited (144 Front Street, Toronto, M5J 1G2, Canada).The following three publications are available from the Centre for Resource Studies, Queen&apos;s University, Kingston, Ontario, Canada K7L 3N6. An analysis of Japanese coking coal procurement policies: The Canadian and Australian experience, by D.L. Anderson. Feb. 1987. $25. Technology policies in the Canadian mineral industry, edited by M.J. Wojciechowski. Sep. 1986. $20.Value-added taxation: Issues and impact for Canadian mines, by B.l. Dyack. Nov. 1986. $7.3. Mintek reports Report M295 A mineralogical investigation of refractory gold ores and their beneficiation, by P.M. Swash. Report M296 The determination, by distilation-spectrophotometry, of chlorine in apatite-type materials containing fluorine, by M. Solomons. Report M297 The interference of zirconium in atomic-emission spectroscopy using inductively coupled plasma, by P.l. Wright.

Jan 1, 1987

By NONEn NA

1. Book reviews . Rudiments of mining practice, oy C.E. Gregory.Clausthal-Zellerfeld (West Germany), Trans Tech Publications.OS$24.Reviewer: A.N. BrownProfessor Gregory has had a wide experience of hardrockmetalliferous mining throughout the world, beinga well-known academic who has taught at many universitiesin the Western World. His basic training was obtainedin his native land of Australia. In this publication he identified the need for a basic, simple book on miningpractice to provide new students of mining with a backgroundto their studies. He also designed the book to providea background to persons operating on the fringesof the industry such as students of economics and journalists.The text extends to only some 120 pages, and containsa sufficient number of monochrome sketches, diagrams,and photographs. It is written in a straight-forward, easyto-read style. The book contains an index and elementarytable of conversion from imperial to SI (metric) units,and there is also a glossary of mining terms that mostreaders would find useful.The author has succeeded in keeping the contentssimple, as indicated by the title. However, after each chapter, there are references to further recommendedreading. The book could be useful in the South African context, although the coverage of coal and opencast mining operations is slender.

Jan 1, 1987

By Isobel Clark

This paper reviews some of the traditional methods of reserves estimation based on lognormal distribution with or without an additive constant. In the rush to computerize mine planning and grade control generaly, proven estimation methods, such as Sichel&apos;s t, seem to have been overlooked. By use of a personal microcomputer, the traditional methods were investigated thoroughly, the results being tested against existing tables and figures. The fitting of a lognormal distribution, including estimation of the additive constant, is discussed, and the calculation of Sichel&apos;s t estimator and its associated confidence limits is described in detail. Payability calculations for a lognormal distribution are also covered briefly. The advantages of personal computers, particularly speed and ease of use, are emphasized. This low-cost approach permits detailed investigation of some of the assumptions and approximations inherent in the established methods of calculation. Several disturbing discrepancies are revealed in various factors, and some generalized statements made by previous authors are found to be over-simplistic. Full details are given of acceptable approximations and computer algorithms, and concern is expressed over the possible loss of proven methods under the welter of new, sophisticated computer software.

Jan 1, 1987

By P. D. K. Robinson

In the second of a series of five colloquia with the theme Rescue 91 ..Survival Initiatives for the Mining Industry, the emphasis was placed on the harnessing of improved technology for the benefit of all the industry. The Colloquium was held at Mintek, Randburg, and attracted some 150 delegates and speakers from a cross-section of the industry. Eight papers were presented, and panel discussions were held to round off the morning and afternoon sessions. The purpose of the Colloquium was to allow mines and other groups to put forward innovative schemes in the management of technology that could be shared by everyone in their determination to ensure the survival of the gold-mining industry in the current difficult times. PAPERS The papers presented were as follows: The introduction of detachable bits at Cooke No. 1 Shaft, by C.A.F. Sweet of Randfontein Estates Survival through cost-saving measures in the engineering field, by E.J. Jurgensen of Freddies Survival through innovation, action, and a positive vision for the future, by G.C.V. Wade of Vaal Reefs Measuring misaligned guides, by H. Sperling of CSIR Rock-crushing innovations, by E. Trueman of Nordberg Improved explosives technology-has it been worth the effort? by RA. Lindsay of Sasol Cost savings through corrosion monitoring, by M. Tullmin of CSIR Enhanced efficiencies through technical developments in the survey departments, by D. Maree of Beatrix.

Jan 1, 1992

By C. C. Johnson

In the fourteen years that Rössing Uranium Limited has been in production, the metallurgical operations and controls on the leaching plant have evolved through four basic stages. Initially, the emphasis was placed on the achievement of consistent plant operation by overcoming severe startup difficulties. The second stage involved the attainment of the design operating targets, and also the commissioning of the ferric-leaching reactors in order to achieve a ferric ion concentration of more than 3,0 g/l. Improvements in control then became the priority, with the emphasis on consistently achieving the target concentrations of ferric ions, total iron, and terminal acidity. The latest phase has concentrated on the optimization of costs by means of adjustments to the historically established operating parameters in order to achieve large savings on consumables while maintaining the leaching efficiencies. Apart from the obvious incentive of reducing costs in an inflationary economy and a depressed uranium market, impetus for this work was given by a change in the type of ore from the open pit, which has the effect of reducing the extraction efficiency while increasing the consumption of consumable materials. These problems and their solutions are discussed in detail, and the importance to cost-effective optimization of an accurate, up-to-date cost-reporting structure is stressed.

Jan 1, 1990

By S. J. Patchet

The use of fill in deep-level gold mining presents the possibility of achieving considerable economic and operational benefits if conventional support can be eliminated. Unfortunately, the combination of the properties of tailings from gold reduction plants and the narrow, flat, tabular reefs being exploited make conventional hydraulic filling very unpractical. Laboratory tests indicate that, with careful control of water content, these tailings can provide an adequate fill material. A variety of bonding agents have been investigated, and the most practical seems to be ordinary Portland cement. Even at very low cement contents some cohesion is achieved. The design and layout for a complete fill support system using hydraulic transport, dewatering, and pneumatic placement are discussed, and a surface field trial indicated that the principles involved are correct and that acceptable results can be achieved. This system and material would completely eliminate conventional timber and brick support, and a preliminary economic analysis indicates that filling is cost competitive on a direct replacement basis. All the operations for a full-scale operation are available or have been developed to a stage sufficient to indicate that the system is practical, although certain operations require further refinement.

Jan 1, 1978