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By F. H. Touwen, N. C. Joughin

"Simulation is a technique for studying the operation of systems by synthetic experimentation. With digital computers it is possible to simulate even the complex production processes in gold mining. This has great potential in that it enables the investigation, analysis and comparison of mining systems to be done accurately, rapidly and at low cost. Two programs have been developed to simulate the principal underground production processes in gold mining.These are the simulation of any stope contract and the simulation of underground transport operations. The programs synthesize these mining activities from a large number of small unit operations. The stope contract program simulates rockbreaking by drilling and blasting and the cleaning of the panels by face and gully scraping. The transport program simulates the functions and movements of all vehicles running on rails on one underground level. The simulation programs provide an effective means for experimenting with mining activities."

Jan 1, 2014

By L. E. Kun, R. O. Oelofsen, E. J. J. van Vuuren

High-rate floc-blanket clarification of gold pregnant rotary filtrate was introduced at the Vaal Reefs South gold plant of the Anglo American Corporation during February 1978. A. daily 12 000 to 15 000 t of filtrate, with an average suspended-solids concentration of 350 mg/I, is continuously clarified to a concentration of less than 2S mg/I of suspended solids in a modified plant pachuca (10 m in diameter) at throughput rates of 7,7 to 8,5 ma/m2.h by the addition of 5 g/t of ferric chloride inorganic coagulant and 0,2 g/t of Superfloc NI00 flocculant. The pachuca overflow is then clarified further in seven Stellar candle pressure filters of 54,S m2 surface area to under 5 mg/I of suspended solids. The combined clarification cost when the hopper clarifier is used in conjunction with the Stellar filters is R0,0032 per ton of liquid treated, which is approximately 60 per cent lower than the cost of Stellar filtration on its own. The savings are mainly due to the reduced use of filter pre-coat, the consumption of which has dropped by 70 per cent since the introduction of hopper clarification.

Jan 1, 1979

It is desirable to have a model, or method, for major project development, which will enable flexible modelling of separation circuits. This ability improves the understanding of circuits and how they should be operated, especially in a design phase, where various options are evaluated and decisions are made on the required number of stages and configuration. This paper describes existing gravity separation circuit modelling theory and concepts, as defined by Holland-Batt1 (separation window, separation efficiency and proportionality of efficiency). The crux of the paperis the application of numerical analysis to fit raw separation data by means of a modified Bézier-Spline. The paper proposes an alternative to the theory developed by Holland-Batt that provides more flexibility in the modelling of separation stages and curves, which include S-shaped curves. The paper proposes a solution to the challenge of continuously extrapolating data, and the first difficulty normally encountered, which is the fitting of an appropriate empirical formula to raw data.

Jan 1, 2007

By R. M. G. Machunter

The dynamic behaviour of plant circuits and the available instrumentation determine the control strategies that are appropriate for the duty of the mineral separation plant. Although steady state modelling is appropriate to provide the main requirements of grade and throughput capability of a plant, it is the dynamic characteristics that determine the tolerance of the plant to disturbances and also its controller ability. This paper explores these issues with respect to the additional use of dynamic modelling to achieve these objectives.

Jan 1, 2007

By D. W. Boydell, E. B. Viljoen

A flowsheet incorporating rotary-drum filtration for the solid-liquid separation step, followed by solvent extraction for uranium purification, is used as a standard against which four flowsheets are compared. These flowsheets employ either counter current decantation or belt filtration for solid-liquid separation, and either solvent extraction or continuous ion exchange plus solvent extraction for the purification step. Sales revenue, taxation, capital expenditure, and operating costs are estimated. These factors are taken into account in the calculation of an incremental net present value for each circuit by the discounting of cash flows at 25 per cent per year over a projected life of 15 years. For the material used in these examples, the highest net present value results from the circuit that employs belt filtration followed by continuous ion exchange and solvent extraction.

Jan 1, 1978

By A. Hinde, M. H. Moys

Tailings from metallurgical plants, when deslimed with hydrocyclones, provide a valuable source of material for the backfilling of mines. The effectiveness of this material as a support medium is a sensitive function of its particle- size distribution and water content. It is therefore important that the hydrocyclone-classification plants used to prepare the backfill are operated efficiently, and that the effects of feed disturbances on the composition of the backfil are minimized. This paper addresses the problem of the design, control, and optimization of classification plants to satisfy this need. The development of a computer program to simulate the dynamic behaviour of a hydrocyclone circuit of any given configuration is described. The use of the simulator to investigate the relative performance of conventional and innovative control strategies for single-stage and two-stage circuits is discussed in depth. The results of simulation studies are presented that indicate there is considerable scope for improving the performance and cost-effectiveness of backfill-classification plants.

Jan 1, 1991

By V. M. Lovell, N. P. Finkelstein

The concepts involved in flotation research are discussed and aims are presented. Three different methods of investigation can be used, all of which are applied at the National Institute for Metallurgy (N.I.M.), and these are the empirical, trial and error method, the chemical engineering method, and the physicochemical approaches. This paper is devoted to the last of these. Because of the complexity of the physicochemical interactions involved, the work has, to a large extent, been concentrated on only one aspect, viz. the interaction between the mineral surface and reagents in solution, which was considered of major importance in the understanding of the process. The aspects on which work has been done are the concentration of uranium, the reaction between salt minerals and fatty acids, mixed xanthate-cationic collector systems, and the reaction between sulphide minerals and thiol reagents. Selected problems from the first two of these are discussed in some detail and deal with the agglomeration flotation of uranium and the chemical control of the flotation process for phoscorite. A detailed discussion is also presented of the progress made in the understanding of the interaction between sulphide minerals and thiol reagents, which is of more general application. Finally, an indication is given of the future direction of physicochemical research at the N.I.M.

By H. Zhong, S. Wang, Q. Lin

To improve the flotation performance of chalcopyrite collector, 2-(tert-butoxy)ethyl xanthate (TBEX) and its derivative O-(2-(tert-butoxy)ethyl)-N-ethyl-thionocarbamate (TBEETC) were designed and prepared by the introduction of a 2-(tert-butoxy) ethyl group into xanthate and thionocarbamate. TBEX and TBEETC were both prepared via the one-pot method with superior efficiency, which has significant commercial implications. The micro-flotation tests demonstrated that compared with sodium isobutyl xanthate (SIBX) and O-isopropyl-N-ethyl-thionocarbamate (Z-200), TBEX and TBEETC both possessed better collecting ability and selectivity for chalcopyrite. DFT calculations and XPS were utilised to investigate the flotation mechanism involving TBEX or TBEETC and chalcopyrite. The results demonstrate that although 2-(tert-butoxy) ethyl group does not interact with minerals directly, its introduction reduces the energy of HOMO, so that they can better accept electrons instead of donating electrons which leads to better interaction with copper atoms rather than iron atoms. Keywords: Chalcopyrite, flotation, thionocarbamate, xanthate, synthesis

Jan 1, 2020

By H. -U. Lim, C. -H. Kim

The sixth underground pumped powerhouse cavern is under construction now in Korea. For the stability analysis of the five underground powerhouses, finite element method was used. For this analysis, in-situ rock stresses were measured by overcoring method and horizontal to vertical stress ratio was calculated 1.07-1.32 at four sites. Rock mass strength and elasticity were assumed from intact rock properties. The ratio of elasticity of rock mass was 0.16-0.55 of intact rock core elasticity. In general, elasto-plasticity with Mohr-Coulomb failure criterion was applied and the input cohesion and internal friction angle were approximately 0.12-0.22, 0.6-0.87 of intact rock strength parameters, respectively. Der sechste Untergrund-gepumpt-Powerhouse-Cavern ist jetzt im Bau in Korea. Für die vergan-gene Stabilitätsanalyse des fünf unterirdischen Powerhouses in Gebrauch wurde ein begrenztess Elementsmethode benutzt. Für die Analyse wurden In-Situ Felsenspannungen von overcoring Methode gemessen und Horizontale zu senkrechtem Spannungsverhältnis waren als 1.07-1.32 an vier Stellen kalkuliert. Felsenmassenkraft und Elastizität wurden von unversehrtem Felsenei-gentümern angenommen. Das Verhältnis der Elastizität von Felsenmasse war 0.16-0.55 von un-versehrter Felsenkernelastizität. Im allgemeinen wurde Elasto-Plasticity mit Ausfallskriterium des Mohr-Coulombs verwendet. Die Eingabebindekraft und die innere Reibungswinkel waren unge-fähr 0.12-0.22, 0.6-0.87 von unversehrtem Felsenkraftsparametern, jeweilig. En Coree, la sixieme centrale souterraine de la pompe d'accumulation dans la caverne est en construction. La methode d'element fini a ete utilisee pour analyser la stabilite de cinq dernieres centrales en service. Dans cette analyse, la reaction de la roche sur place etait mesuree par la methode d'overcoring et celle du rapport horizontal-vertical etait calculee de 1.07-1.32 en quatre places. L'intensite et l'elasticite de la masse de roche ont ete estimees de la roche intacte. Quant a l'elastic-ite, sa masse de roche etait 0.16-0.55 fois que celle de la roche intacte. En general, elasto-plasticite avec le critere de defaut Mohr-Coulomb etait utilisee et sa cohesion d'energie et son angle de friction interieure etaient supposees respectivement 0.12-0.22, 0.6-0.87 fois que la parametre de l'intensite de roche intacte.

Jan 1, 2003

By I. M. MacGregor

This paper discusses the possible use of petrological data and proximate analyses in the prediction of cutting forces for coal. It is restricted to the development of univariate predictors based on data from thirteen collieries in five major Transvaal and Orange Free State coalfields and three coal provinces. The aim of the work was the identification and development of the best predictors of mean peak cutting force and Hardgrove grindability index from among the independent variables evaluated. The data, which were obtained by use of the penetrometer developed by the Chamber of Mines Research Organization, were processed according to the SPSS computer package. The analysis revealed reasonable correlations between the Hardgrove grindability index and (1) the volatiles and vitrinite content in the Vereeniging-Sasolburg and South Rand Coalfields, (2) the contents of vitrinite, vitrinite plus exinite, and minerals plus inertinite in the Eastern Transvaal Coalfield.

Jan 1, 1985

The rising tide of environmentalism has adversely affected many mineral producers, but it has also provided them with a number of opportunities for mineral applications. These markets are as diverse as water treatment, waste disposal, and flue-gas desulphurization. Whilst legislation is forcing up the industry's environmental standards, the advent of environmental management provides an opportunity for producers to display its 'green' credentials. The picture painted of the extractive industry by environmentalists is undeservedly black, because the more efficient a producer is, the more effectively that producer conserves the very resources he exploits. The 1993 IM Forum examined these issues and how they affect the mineral producer, and this publication comprises the papers presented at that meeting.

Jan 1, 1995

By K. -J. Shou

A special three-dimensional boundary element method has been developed for the simulation of the development of fracture zone in rock mass. This approach comprises a boundary element method and a three-dimensional tessellation mesh generator. By using the tessellation generator, a set of pre-defined potential fractures is defined, and the fractures activate when the failure criterion is exceeded. This approach is justified by the reproduction of features observed in laboratory simulations of fracturing in blocks of rock subjected to compression. An attempt is then made to explain some of the attributes of fracture zone surrounding underground openings. Eine spezielle drei-Dimesionen Grenze Element Methode ist entwickelt zu simulieren die Entwicklung der Fraktur Zone in der Steinmasse. Diese Untersuchung benutzt eine Grenze Element Methode und ein drei-Dimensionen tessellation Masche Generator. Durch das Benutzen des Tessellation Generator, ein Satz der vor-bestimmt potentielle Fraktur ist festgelegt. Die Fraktur wird betaetigen, wenn das gescheiterte Kriterium ist uebersteigt und sind in dem Verscheiben-Abbrechen Element eingeschlossen. Diese Untersuchung ist von der Reproduktion der Fraktur justiert, die ins Labor beobachtet wird, um die Fraktur in der von der Kompression unterworfenen Steine zu simulieren. Ein Versuch ist gemacht, um einige Eigenschaften der Fraktur Zone um die untertageoeffnung zu erklaeren. Une méthode tridimensionelle spéciale de élément frontière a été dévélopée pour la simulation du dévélopment d’une zone fracturée dans la massive roche. Cette approche comprend une méthode de élément frontière et un générateur de maillage de la mosaïque tridimensionelle. En utilisant le générateur de mosaïque, une série des fractures potentielles predéfinies est définie avec d’une procédure de la triangulation de Delaunay. Les fractures activent lorsque le critère de rupture est dépassé et sont inclues dans les éléments du déplacement discontinuité. Cette approche est justifiée par la reproduction des caractéristiques observées dans le laboratoire, les simulations des blocs de roche fracturé et sujetés en compression. La tentative est alors fait pour expliquer quelques arttributs d’une zone fracturée alentours les ouvrages soustérrains.

Jan 1, 2003

By S. Kirkpatrick, J. Mukendwa

"The mining operation at Namdeb’s Southern Coastal Mine (SCM) is unique. It targets gravel layers up to 30 m below sea level, which continue to dip deeper, further west, under the Atlantic Ocean. On this storm-dominated coastline, severe water seepage into mining areas, rugged orebody footwall characteristics, and highly variable resource grades all contribute to a challenging operational environment. Namdeb has a proud history of innovation, and as the mine progresses further westwards and associated technical and economic challenges increase, this innovative culture has become essential to the future of the mine. The Theory of Constraints (ToC) has been widely used at SCM, and across the mining discipline, to focus efforts on improving overall business profitability. Through analysis of the mining processes, opportunities were identified, solutions developed, and initiatives implemented with staggering results across all three mining disciplines, i.e. stripping, load and haul, and bedrock bulking and cleaning. This paper outlines the solutions adopted and the results of the ToC analysis. IntroductionSouthern Coastal Mine (SCM) is one of three Namdeb operations located in the southwestern corner of Namibia, between the Orange River in the south, the Namib Desert to the east and the Atlantic Ocean to the west (Figure 1). These three geographical features set the backdrop for the world’s greatest marine diamond mining placer (Badenhorst, 2003). SCM is situated along the coastline extending from the mouth of the Orange River to Chameis Bay approximately 120 km to the north. The active mining area, called Mining Area 1 (MA1) is, however, limited to very narrow strip, 30 km in length, in the south of the licence area, close to the town of Oranjemund.Namdeb, a wholly owned subsidiary of Namdeb Holdings, is a 50/50 joint venture between De Beers and the Government of Namibia. Diamonds were first discovered along the Namibian coastline in April 1908, close to the town of Luderitz, but mining operations started in the SCM mining area only in February 1929 (Schneider, 2009). Initially all Namdeb mining operations exploited massive land-based deposits, producing nearly 40 million carats from MA1 between 1920 and 1977 (Schneider, 2009) when mining targeted onshore raised beaches west of the high water line. Since 1977 however, SCM and Namdeb have developed a unique mining method to economically extract the resource which extends westward under the Atlantic Ocean."

Feb 1, 2019

By J. A. L. Napier

By use of a functional model of capital expenditure developed earlier, a prototype cash-flow model is formulated as a basis for the investigation of the economic consequences when the production rate of a mine is manipulated as fundamental design variable. The optimum production capacities that maximize the common economic criteria of net present value, present-value ratio, and wealth growth rate are determined. It is shown that these choices depend certain key groupings of the economic parameters, and that they have a fixed interrelationship. The basic cash-flow model is extended further to include the effects of a constrained rate of production buildup and the imposition of State taxation on generated income. An approximation to the initial tax-free period of a new mining venture is developed, and, by use of these results, the optimum choice of production level is analysed when both the buildup rate is constrained and tax is imposed. This extended model permits a comparison between the performance of existing mines and the predicted theoretical production levels for these mines.

Jan 1, 1981

Contribution by W. Assibey-Bonsu I congratulate Mr N.O. Lotter on his paper. There are two main aspects of the paper on which I would like to comment. One aspect is his review of P. Gy's sampling theory under the heading 'Sampling the mill feed' (p. 153). The other aspect relates to his reference to one of our papers1 that was published in the Journal (p. 152). My comments on the former will be given elsewhere'. Authors' reply: Dr Assibey-Bonsu's contribution to the subject is appreciated.

Jan 1, 1996

By R. D. Beck

The minerals industry needs the support of al sections of the population if it is going to be able to supply the new materials required for future development. It will achieve this support only if its image is good. Perceived images of the minerals industry are examined in respect of history, technology, environment, safety, education, and economics. Concern is expressed about the low technological image of the industry and the declining number of students enrolling in minerals-related disciplines. It is concluded that it is the professionals, through institutes like The South African Institute of Mining and Metallurgy, who must take the lead in improving the image of the minerals industry. The Presidential Address gives data to support this thesis; data that, is hoped, can be used in efforts to educate people about the minerals industry.

Jan 1, 1991

By J. -M. Chautru

A geostatistical simulation of a typical mining site for polymetallic nodules in the North Pacific Ocean is presented. This is the first stage in the design of an industrial mining system. Two variables which have a major effect on the orebody's economic potential are considered, namely: the maximum slope of the ground inside a mining block of 50 x 100 m; and the average quantity of nodules on the same support. Two geostatistical problems have emerged in this study. The first is due to the lack of a change of support model for the maximum of a variable. A provisional solution, considering an experimentally accessible 'equivalent' support, is proposed. The second is due to a non-linear link between the two variables. To be able to take this into account in the simulation, we propose a new method based on the decomposition: X = E(X/Y) + Residue (X). Satisfactory results were obtained with this approach.

Jan 1, 1987

By R. M. S. Falcon, L. M. Falcon

The prediction of the mechanical behaviour of South African coal on the basis of current proximate and other chemical parameters gives rise to problems, and the use of ultimate analyses and inferred maceral and rank analyses, although it has improved the situation to some extent, is still not satisfactory. In an attempt to reach a new level of understanding, this paper gives an in-depth review of the fundamental petrographic characteristics of coal and compares these parameters with the main types of mechanical performance. A two-tiered system of primary and secondary parameters is proposed for the prediction of coal behaviour. The primary or inherent parameters include rank and organic composition. The secondary or extraneous factors include such parameters as mineral mater, cracks or cleats, degree of oxidation, and size. In addition, an explanation is offered of several anomalous behavioural conditions in some South African coals.

Jan 1, 1987

By M. J. U. T. Van Wijngaarden

SYNOPSIS The corrosion characteristics of a new steel, 14Cr, which is a modification of the well-known 3CR12, in aqueous sulphate solution were studied through polarization diagrams and a computer analysis based on the polarization¬resistance technique. It was found that the corrosion rate of 14Cr steel is independent of pH for pH values above 6, but, below a pH value of 4, the corrosion rate increases sharply with decreasing pH. In air-saturated solutions of neutral and mildly alkaline pH, the corrosion rate is approximately 60 µm per year. The 14Cr steel shows a twentyfold improvement in corrosion resistance over that of 3CR12 in sulphate solutions at pH 2,0. This is considered to be due to the beneficial effect of its higher chromium and nickel contents.

Jan 1, 1985

By F. Smit

Mining and plant practices can benefit from preconcentration of UG2 platinum ores in a dense medium separation (DMS) plant. The main benefit of DMS is the selective discard of waste from the feed stream, thus improving project economics while reducing the power and water requirements for processing. On the mining side, with the correct combination of variables, implementing DMS as a pre-concentration step can reduce cut-off grades and, as a result, increase ore reserves. In addition, the use of DMS technology gives the mine team the opportunity to consider alternative mining methods for an operation. The challenges of balancing the mining tonnage, methods, and resulting grades with the process plant size, recoveries, and DMS discard volumes have resulted in the development of a model to optimize value on new projects or existing operations. This paper will focus on these benefits from a mining and plant perspective, quantifying the water and power savings, and look at the economic benefits of preconcentration and the effect of metal prices, plant feed grade, and DMS efficiency in different mining environments.

Jan 1, 2013