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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. -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

By M. M. Bwalya, F. K. Mulenga

"SynopsisThe application of the attainable region (AR) technique to the analysis of ball milling is currently limited to batch data. This paper introduces the use of the technique to continuous milling.To this end, an industrial open milling circuit processing a platinum ore was surveyed. Samples were collected and later characterized by means of laboratory batch testing. On site, several milling parameters were varied systematically so as to collect data for modelling purposes. These paramters included ball filling, slurry concentration, and feed flow rate. After data analysis, a simulation model of the open milling circuit was developed under MODSIM®, a modular simulator for mineral processing operations. The mill was then simulated and the data generated was analysed within the AR framework.Initial findings reveal an opportunity to gain valuable insight by studying milling using the AR technique. From an exploratory perspective and inasmuch as this study is concerned, feed flow rate, ball size, and ball filling were identified as being pivotal for the optimization of open ballmilling circuits. Mill speed, on the other hand, had only a limited effect on the production of particles in the size range -75 +10 µm.IntroductionGlasser and Hildebrandt (1997) propounded the attainable region (AR) as a technique for the analysis of chemical engineering reactor systems. Results have since been produced and tested on both the laboratory and pilot scales. The method results in a graphical description of chemical reactions by considering the fundamental processes taking place in the system, rather than the equipment. From the plotted graphs, the process and the reactors can be synthesized optimally into a flow sheet.The use of the AR method still has a long way to go as far as mineral processing is concerned. For instance, several articles have reported the application of the AR technique to ball milling: Khumalo et al. (2006, 2007, 2008); Khumalo (2007); Metzger et al. (2009, 2012); Metzger (2011); Katubilwa et al. (2011); Hlabangana et al. (2012). Their main shortcoming has been the exclusive use of laboratory batch grinding data.To address this deficiency, Mulenga and Chimwani (2013) proposed a way by which the technique could be extended to continuous milling. In effect, the batch milling characteristics of a platinum-bearing ore (Chimwani et al., 2013) were used and scaled up to an open milling circuit. Then, with simplifying assumptions, an attempt was made to optimize the residence time of particles inside the mill. Later, Chimwani et al. (2014a) presented some optimization examples involving various milling parameters. The sequence of published articles then paved the way for the study of industrial milling systems with the AR methodology."

Jan 1, 2015

By F. P. Agterberg, A. G. Fabbri

"A statistical analysis was done on the locations of 718 copper and 1 257 gold deposits in Abitibi. This area of about 20 000 square miles is one of the better-explored metal-producing areas of Canada.Patterns of clusters were studied by harmonic analysis. Several two-dimensional power spectra showed a number of distinct peaks. Sets of crest lines for patterns of interfering waves were constructed on the basis of these peaks. They pass through elongated clusters of deposits which are spaced more or less equally. For copper these periodic regularities in location may coincide with geological structures largely of Archean age (major fractures and sedimentary belts indicating synclinal structures). A directional relationship with swarms of diabase dykes of known ages and distinct attitudes indicates that the gold mineralization is, in part, younger than the copper mineralization."

Jan 1, 2014

By D. F. Williams

The modelling, simulation, and design of processes for the recovery of gold from solution by absorption on carbon require the combination of a suitable rate expression with a description of the flow conflguration of the system. By the use of a suitable rate expression from the literature, methods are presented for the design of multi-stage countercurrent absorption systems corresponding to the commonly used carbon-in-pulp and carbon-in-column contacting systems. The sensitivity of the recovery to various design parameters is illustrated. These results have important implications in the choice and design of equipment.

Jan 1, 1985

By W. Soetaert, P. Dhar, H. R. Kota, M. Thornhill, S. Roelants, I. V. Chernyshova

Yeast-derived bola-amphiphiles have attracted considerable attention for their applications in various industrial sectors in recent years. However, only a few studies on this class of surfactant were reported to be relevant to mineral processing applications. In this paper, one of the novel surfactants, acidic glucolipid obtained from Candida bombicola sophorolipids and modified by using Penicillium decumbens naringinase substrate has been evaluated for its interaction with chalcocite and calcite minerals because of a new Cu-ore Nussir deposit in Norway containing calcite impurity. The interaction of glucolipid biosurfactant with copper sulphide and carbonate minerals was investigated with zeta potential, adsorption and FTIR studies, and also by Hallimond tube and bench scale flotation tests using pure minerals and Nussir copper ore, respectively. The results illustrate collector adsorption and flotation of copper sulfides at neutral pH. The bench-scale flotation results demonstrate that copper sulphides can be selectively floated from carbonate and silicate gangue minerals. This study underlines the glycolipid’s high potential for its use as collector for flotation of valuable copper sulphide minerals. Keywords: Flotation, biosurfactants, adsorption

Jan 1, 2020

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 K. Shame, H. H. Thiele

South Africa holds approximately 70% of the world’s total chrome reserves. Chromium is an important raw material for the production of stainless steel and ferrochrome alloys. Over the years, China’s ferrochrome market has been dependent on chrome ore imports from South Africa. In 2018, China imported about 75% of its chrome ore from South Africa. With the low platinum price and the rising demand for stainless steel, a growing demand to evaluate new beneficiation technologies for fine chromite was identified. Gravity separation of fine chromite (<75 μm) is inefficient, due to the limitations of the technology to upgrade fine particle size distributions. Potential for the recovery of chromite, specifically fines (<75μm), lost to UG2 PGM flotation tails, but also from MG and LG6 spiral circuit tailings exist. Flotation of podiform chromite ores from India and Kazhkhstan is successful in generating saleable product grade, following acid or alkaline flotation routes. Application to South African stratiform chromite is being evaluated, with the emphasis on evaluating reagent type, optimising dosages and the effect of pH in optimising flotation performance. Flotation can unlock additional value from chromite tailings material. The effect of ore characteristics such as gangue mineralogy, particle size distribution and headgrade are reported. The performance in terms of product quality and yield are evaluated and compared. The impact of this paper will not only prolong life of mine and increase revenue but will also alleviate environmental burdens associated with tailings dams. Keywords: Chromite, flotation, fine material, performance optimisation

Jan 1, 2020

By D. F. Malan, W. J. Theron

Practical mining aspects should be considered when conducting pillar designs for bord-and-pillar layouts. The current methodology for pillar design will result in increasing pillar sizes with depth. This affects the extraction ratio and will result in onerous ventilation requirements when cutting large pillars. A holistic approach, including all mining engineering requirements, is required to ensure that the rock engineering designs are optimized to ensure efficient mining operations and sustainable production. Bord widths should not only be a function of the rock mass ratings, but should also be selected to fit the specifications of the mechanized equipment. The use of a ‘squat pillar’ formula for hard rock is discussed in the paper and the formula based on the exponents of the Hedley and Grant pillar formula, is explored. The effect of abutments and geological losses on average pillar stress is also explored. These factors must be considered when designing layouts at increasing depths.

Nov 27, 2024

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&apos;s sampling theory under the heading &apos;Sampling the mill feed&apos; (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&apos;. Authors&apos; reply: Dr Assibey-Bonsu&apos;s contribution to the subject is appreciated.

Jan 1, 1996

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

Jan 1, 1988

By B. A. Dukas

The diamond-drilling machine has for many years been the most important exploration tool In the search for and subsequent evaluation of Witwatersrand-type ore deposits. With a view to increasing the range of services that can be provided and, at the same time, counteracting rising drilling costs, new techniques are continuously being developed. Many of these techniques have equal application in surface and in underground exploration. This paper reviews drilling techniques such as non-coring pilot holes and deep wire-line drilling, as well as the design of core-barrels and drilling bits to cater for the specific nature of the job on hand. Special drilling fluids and aluminium rods to assist in normal drilling operations are also discussed. Special mention is made of a bore hole&apos;s natural tendency to deviate in a certain direction. The factors that cause deviation are used to the advantage of controlled drilling techniques.

Jan 1, 1983

By E. Spicer

X-Ray diffraction (XRD) provides useful information about the composition of an ore sample in terms of quantification of crystalline phases and amorphous content. The use of new, fast detection systems in XRD creates the opportunity to use this technique in modern process control. In the analysis of heavy mineral sands, XRD can identify the main mineral phases, such as ilmenite FeTiO3, rutile TiO2, Zircon ZrSiO4and quartz SiO2, and any other minor components present, such as anatase TiO2, magnetite Fe3O4, haematite Fe2O3or monazite (Ce, REE)PO4. Quantitative analysis is possible by various classical methods such as straight line or polynomial calibration with standards, but modern quantification analysis techniques such as Rietveld analysis (Bish and Howard, 1988) are attractive alternatives, as they do not require any standards or monitors. These methods offer impressive accuracy and speed of analysis. The Rietveld method compares calculated versus experimentally derived X-ray powder diffraction patterns for the sum of all crystalline phases. Another analysis technique offering great benefit to mining industries is cluster analysis. Enormous amounts of XRD measurement data are generated during the process control and material evaluation. New ways of handling such vast amounts of data are required to produce meaningful information for the end users. Cluster analysis greatly simplifies the analysis of a large amount of data from different processes or different raw materials, and automatically sorts closely related scans of an experiment into clusters and marks the most representative scan of each cluster as well as outlying patterns. The use of cluster analysis to evaluate the XRD data allows fast and reliable tracking of the process. It is the most economical procedure to have automatic data evaluation without involving any dedicated personnel in the process. Details of the techniques used, sample optimization methodologies, results, data precision and limitations will be discussed. The approach has potential as a relatively inexpensive, reliable tool, useful in the characterization of heavy minerals sand materials.

Jan 1, 2007

With a number of new mines at the feasibility stage and beyond and with several pellet capacity expansions well underway to reduce sintering activity, Alex Broad looks at the impact of worldwide environmental legislation on the iron ore industry. &apos;Environmental impact assessment&apos; has become something of a buzz term in the metals and mining industry over the last few years and is sure to be an integral part of any green or brown-field project worldwide by the turn of the century, if it is not already. Given the number of iron ore projects springing up, most notably in deposit-blessed Australia, it is not surprising that the subject of environmental approval has been raising its green head. At the very least the process can slow down a new mine project, or at worst have it deemed unfeasible but in general a government is unlikely to put up unnecessary barriers to a project with the beneficial financial implications of an iron ore deposit.

Jan 1, 1996

By G. C. S. Burns

"A system has been developed to simulate the mining of the Mufulira orebody. The main output from the system is a picture-gram from which the start date and effective life of all proposed mining faces can be measured. This information provides schedule dates for the completion of major capital development projects and stope preparation activities.The orebody must be divided horizontally into main levels and vertically into blocks of equal interval. Ore reserves are defined by specifying the tonnage contained in each block and main level. Mining faces are defined by their co-ordinates, and may themselves be split into sublevels. The simulation maintains an echelon between contiguous sublevels. Other face parameters control the speed of mining, the availability and relative priority of the face.The required production from each crusher/shaft system is specified. The technique of simulating the mining process in order to achieve the required production is described."

Jan 1, 2014

By B. K. Loveday

The use of large flotation machines is well established, resulting in substantial savings in both capital and operating costs. Therefore, when a new plant is designed, laboratory and pilot-plant tests should be used to simulate large flotation cells, or appropriate scale-up factors should be employed. &apos;Conference on titanium The Fifth International Conference on Titanium will be held from 10th to 14th September, 1984, in Munich, West Germany, organized by the Deutsche Gesellschaft fur Metallkunde e.V., in association with the American Society for Metals, Societe Francaise de Metallurgie, The Academie of Sciences U.S.S.R., The Japan Institute of Metals, The Metallurgical Society of A.I.M.E., and The Metals Society.

Jan 1, 1983

By G. T. van Rooyen

In this overview of materials engineering, the author, drawing on his long experience from his student days until the present (emeritus professorship), briefly recounts the main developments in this field: dislocation theory, fracture problems, and the development of alternative materials such as ceramics and polymers. He then takes a look at the future, in which he foresees a greater demand for materials engineers, and leading roles for universities and technikons in collaboration with industry.

Jan 1, 1996

By D. J. Bosman

Rapid fouling of condenser tubes in underground refrigeration plants is a frequent occurrence. It leads to low heat transfer efficiencies, with consequent serious reduction in capacity and increase in the horse-power requirement of the units. High pressures develop in the condensers, and frequent cleaning of the tube bundles is required. The cleaning operation takes up to 8 hours and in some cases results in significant loss of production. One of the possible causes of fouling is deposition of scale, but this can be readily overcome by controlling the concentration of the water. When water evaporates, the dissolved solids remain behind; thus evaporation increases the amount of dissolved solids per unit volume. If half the original volume evaporates, the concentration of the dissolved solids is doubled and the water is said to have a &apos;concentration&apos; of two. Concentration may be controlled by regulating the amount of water allowed to bleed from the system. The actual concentration value required is a function of the chemical analysis of the circulating cooling water. In one instance, where the problem of scale formation had been eliminated, fouling still persisted, and the possibility of excessive quantities of dust in the re-circulating water was investigated. A dispersing reagent was added to the condenser cooling water as a means of preventing sludge deposition in the condenser tubes. As shown by curve A in Fig. 1 the reagent addition did not decrease the rate of fouling.

By E. H. R. Schümann, H. Wagner

SYNOPSIS The paper gives a detailed overview of the history of subsidence engineering on South African collieries. Surface displacements resulting from total-seam extraction are discussed, and the important role of local geology is highlighted. It is shown that the differences in subsidence behaviour between South African and European collieries can be attributed to the presence of competent strata in the overburden of South African coal seams. Criteria are given for the prediction of the most important subsidence parameters, and a new model for the simulation of surface subsidence above total-extraction panels is introduced. The final section of the paper deals with the damage to surface structures caused by total-seam extraction. A brief summary of the most important undermining experiments on South African collieries is given, and it is concluded that local experiences of damage compare with those in Europe.

Jan 1, 1991