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By N. A. Barcza

An investigation was conducted into the reactions between the slag system MnO-CaO-MgO-SiO2(AI2O3) and the alloy system Mn-Fe-Si-(C). Synthetic slags representative of plant melts and a plant alloy were reacted in alumina crucibles at temperatures of 1400°C, 1450°C, 1550°C, and 1600°C. In similar experiments, slags were used that comprised a South African manganese ore with various amounts of lime and several synthetic alloys with various silicon contents and manganese-to-iron ratios. These experiments were conducted in a vertical molybdenum-wound resistance furnace with full temperature control. Slag-to-alloy ratios were also varied during the tests. The rate of reduction of Mn.O3 and the MnO from the slag by the silicon in the alloy was extremely rapid, most of the reaction being completed within five minutes. The strongly exothermic nature of the reaction resulted in considerable generation of heat at the slag-alloy interface, causing convectional stirring of the contents of the crucible and promoting the rate of reaction. Equilibrium was usually attained after fifteen minutes. The major limitation governing the recovery of manganese is the need for the silicon content of the alloy to meet a maximum specification of 2 per cent. Higher concentrations of silicon in the final alloy of between 8 and 12 per cent favour good recoveries of manganese from the slag, but, since such an alloy is not salable, lower recoveries must apparently be tolerated. In alloys of 2 per cent silicon, low activities of the silicon are responsible for poor recoveries of manganese. The activity of MnO in the slag can be increased by moderate additions of CaO and small amounts of MgO, i.e., by an increase in the basicity of the slag.

Jan 1, 1979

Iron ore pellets with or without additives are commonly used as alternate charge material in both conventional and newer ironmaking processes. The performance characteristics of these pellets are normally assessed on the basis of their reducibility values, reduction strength and resistance to clustering. These properties depend mainly on the type and amount of additives and on the sintering phenomena of the pellets during firing. In the case of composite pellets (ore-coal pellets), reduction and sintering of the iron ore fines occur simultaneously. The thermodynamic and reaction mechanisms of the processes involved in the reduction of iron ore pellets with and without reductants, additives, etc., may not necessarily be identical. The reduction and sintering characteristics of pellets greatly influence the reaction mechanism and the surface morphology of the reduced pellets. The approaches in the literature to the analysis of these reduction and sintering phenomena are broadly categorized as follows: (i) empirical models, (ii) models based on kinetics, and (ill) models based on morphological changes. The relative merits and de-merits of these models are illustrated by their application to the reduction of fluxed ore-coal composite pellets. A critical analysis of the investigations that have been conducted on the reduction and sintering behaviour of such pellets is given. It is shown that, although elegant empirical models and kinetic equations have theoretical significance and can be usefully employed in elucidating the reaction mechanisms of iron ore lumps, they are sometimes not directly applicable to fluxed ore-coal composite pellets. In studies of the latter, the approach should be to correlate the morphological changes with the reduction mechanism. The paper also gives a brief account of an investigation on the reduction and sintering aspects of fluxed composite reduced iron pellets.

Jan 1, 1996

By E. J. Maunders

This paper describes briefly a computerised model of the South African electricity system which has been developed jointly by the Atomic Energy Board and the Electricity Supply Commission. The results of an analysis of this system have been subjected to a fairly extensive sensitivity analysis which reveals that up to the year 1990 between 680 and 700 million tons of coal will be required for electric power generation, together with between 7 000 and 10 000 tons of uranium. This result is fairly insensitive to data variations, but the prediction of a cumulative requirement up to the year 2000, of between 1 300 and 1 800 million tons of coal and 25000 to 70000 tons of uranium, proves to be very data-sensitive.

By D. G. Millenbruch

An account is given of a four-phase system for the appraisal of a mineral project while it is still in the exploration stage, and for continual consideration of a favourable appraisal until the production stage is reached. There are ten stages from the idea of a likely project to the production stage, and all the staff that are eventually to be concerned with the development of the project are involved at an early stage.

Jan 1, 1979

By D. Lunt

This paper describes and sets in context the commercially proven uranium extraction processes. It also discusses some of the technologies that are currently being pursued with the aim of reducing costs and overcoming a number of technical issues that are faced by process designers and operators. In doing so, opportunities for the transfer of extraction technology from other industries/commodities are identified. The key processing areas that are examined include: ?The influence of mineralogy. The type of uranium mineralization and the nature of its association within a particular deposit will have a major impact on process route selection. Uranium minerals are classified according to their influence on extractive metallurgy. As the uranium price has risen in recent times, so opportunities are increasing for the recovery of uranium from less conventional resources such as phosphates and fossil fuels. ?The opportunities for employing techniques aimed at reducing the capital and operating costs of the overall process such as heap leach and beneficiation. Preconcentration by screening, gravity separation and radiometric sorting can potentially reduce the mass flow to the downstream leach and recovery plants. ?Purification or separation of uranium in carbonate systems. While it is possible to directly precipitate uranium from clarified leachate, the presence of impurities such as vanadium, molybdenum and others may dictate that ion exchange or selective precipitation is employed. Advances have been made in other industries in terms of improved ion exchange equipment aimed at reducing resin inventories and hence costs. ?Separation in acid leach systems. Earlier developments included the use of combined SX-IX systems (Eluex or Bufflex) and the introduction of continuous countercurrention exchange (CCIX). Column SX has found a ready application to uranium in view of the rapid extraction kinetics. With the renewed interest in uranium processing, efforts are being redirected towards further development of resin-in-pulp (RIP) as a means of driving down capital and operating costs. ?Extraction in a chloride environment. Australia and Namibia are desert countries where good quality water comes at a cost. However, both have access to saline water from either the ocean or subterranean aquifers. The issues associated with operating a uranium extraction operation in such environments is discussed. ?Extraction from less conventional sources. Recent price increases for U3O8 have resulted in a number of companies examining the recovery of uranium from sources such as fossil fuels and phosphate deposits. Both of these areas were examined in the 1970s and 1980s and a number of approaches were commercialized. The paper reviews the extraction options.

Jan 1, 2007

"Chairman: Mr W. S. GALLAGHERRapporteur: Professor A. M. STARFIELDPapers:Long-term mine production scheduling by G. C. S. BurneAn application of linear programming to investment analysis by A. ErlandssonOptimizing medium-term operational plans for a group of copper mines by M. Splaine, D. C. Atkinson, W. Davison and L. SmithThe simulation of underground stoping and transport operations in gold mining by F. H. Touwen and N. C. JoughinProduction planning is a subject that lies at the interface between the computing centre and mine management. Discus¬sion during this session was thus largely concerned, directly or indirectly, with communication between computing and mining personnel, and as such was relevant to the symposium as a whole.Mr A. Weiss set the tone of this discussion by referring to `user-orientated systems'. He congratulated Mr Burne in this regard, pointing out that his long-term production scheduling program, as a computer system, was similar in approach to the manual system it replaced, and was therefore easily understood by planning engineers. He asked whether the schedule engineer had his 'hands on' the system, to which Mr Burne replied that the engineer did in fact spend several days running alternative schemes through the computer. Mr Weiss commented on the advantage of having terminals on site for this sort of engineer-computer interaction. He also commented on the flexibility of Mr Burne's approach to scheduling and how preferable this was to a one-step optimization package. This was brought home by a question from Mr H. D. Small: Mr Burne's program sometimes found it necessary to temporarily halt an advancing face, and he asked whether the logic of the program could be altered to avoid this (e.g. by suitably slowing down the rate of face advance). Mr Burne replied that it was in fact easier for the planning engineer to sort this problem out manually. The way in which the computer results were presented made it particularly simple for the production engineer to see how to avoid or remedy a stopped face.On the technical side, both Mr Weiss and Mr H. M. Wells questioned Mr Burne on the handling of grade control by his program. From answers by Mr Burne and his colleague Mr K. H. Thomson it emerged that a spot-check on grade every now and then was all that was necessary at Mufulira, and that the idea of actual grade control was more a question of short-term than of long-term planning."

Jan 1, 2014

By M. Loots, E. Van Der Lingen, S. Grobbelaar

The increased adoption of unmanned aerial vehicles (UAVs) may improve the productivity and costeffectiveness of remote sensing in the mining industry. This review’s objective is to enable stakeholders to identify possible application adoption, improvement, and innovation opportunities. The review merges a building block strategy and practical screening criteria to identify possible avenues of research to answer the review questions. After the screening process, 72 documents were included in the review. Papers were classified into four categories: exploration, development, exploitation, and reclamation. Fifteen applications were identified, the majority of which were in the exploration phase. The most often researched applications were topographic surveys, reclamation monitoring, and slope management. From the two UAV types identified, multi-rotor vehicles were the most favoured for all applications. From the eight remote sensing techniques identified, photogrammetry was the one most often used. Other techniques were limited because of complexity, cost, or the incompatibility of sensors and UAVs. The review was limited to published papers in academic journals. Future studies could aim to include empirical data on the latest UAV applications used in the mining industry.

Jul 2, 2022

By M. Rudolph, E. Schach

Tecflote is a new group of nitrile-based collectors for sulfide flotation. Water insolubility results in some interesting implications for the actual mechanism. It is not yet understood if Tecflote is directly adsorbed on the mineral surface as emulsion droplets or if it is only active at the air-water interface, affecting the interfacial rheology or electrostatic- and Van der Waals interactions, which have a direct impact on the bubble-particle contact. Different investigations including contact angle measurements, AFM studies and micro-flotation experiments are conducted to obtain a better understanding of the actual mechanism of Tecflote. Due to the reagent’s insoluble character, the Langmuir-Blodgett technique is used to investigate its behaviour in the air-water interface and to deposit defined layers of Tecflote on mineral substrates for the above-mentioned studies. An interferometric set up is used to investigate the influence of Tecflote on the film thinning between an air bubble and a mineral substrate. In addition, possible synergistic effects for the combination of Tecflote and conventional frothers (e.g. MIBC) are studied. Keywords: Sulfide flotation, insoluble collector

Jan 1, 2020

By J. M. Eriksen, T. Rosenqvist, H. Elstad, S. Seim, A. Hildal

The titanium industry demands high titanium feedstock for their processes. As rutile resources are limited, ilmenite has become the most important titanium source. Ilmenite smelting is an important part of upgrading ilmenite to high titanium feedstock. In the year 2005, upgrading of ilmenite by smelting, producing a slag with 80-90% Ti02, accounted for approximately 40% of the feedstock to the Ti02 pigment industry. In ilmenite smelting molten iron is produced together with a slag, which in addition to titanium oxide contains iron oxide as well as various impurity oxides of manganese, magnesium, silicon, aluminium, etc. Titanium is present mainly as Ti02 but partly also as Ti203. It is known that the concentration of Ti203 increases with decreasing concentration of FeO, but this dependency is affected by the nature of the impurity oxides. Sigurdson and Moore1 showed that slags high in CaO and MgO had a lower concentration of Ti203 than slags high in Si02 for the same amount of FeO. Pistorius2 showed in 2002 that if the impurity oxides MnO and MgO are counted, on a molar basis, as FeO, and Cr203, V203 and part of the A1203*), as Ti203, industrial slags will have a composition close to that of the M305 phase, where M denotes the elements Ti, Fe, Mn, etc, and which has the pseudobrookite structure. However, for equilibrium with liquid metallic iron he computed, by means of a computer program FACT, that the slag equilibrium composition is represented by a curved line in the ternary phase diagram FeTi03-TiO2-Ti2O3, but with a significantly higher concentration of trivalent titanium than actually observed in the industrial slags, and he discussed various mechanisms by which the slag during solidification could change its composition to a lower Ti203 content, but the possibility that the computed compositions might be wrong was not mentioned. Trane113 found in her research on titaniferous silicate slags a lower Ti3+/ Ti4+ ratio than that which is computed by the FACT program. The purpose of the present investigation was to study the equilibrium composition of Fe-Ti-O slag in equilibrium with liquid metallic iron, as well as the effects of impurities such as Si02, CaO and MgO on the slag composition. Industrial slags from TINFOS Titan and Iron KS (TTI) will also be discussed and their compositions will be plotted in the ternary phase diagram. These are slags produced from Tellnes ilmenite, quite high in magnesium and iron. Experimental In the past, equilibrium studies of the Fe-Ti-O slag system were difficult when it came to producing the slag. It was difficult to find a suitable crucible for the meltings. The highly corrosive slag would attack all known refractories, and the metal would attack metallic crucibles such as those made of platinum and molybdenum. In the present investigations the slag-metal combination was prepared in a high-frequency induction furnace with a vertically segmented water-cooled copper crucible. The crucible is shown in Figures 1 a and 1b. It was designed by the Australian Nuclear Science and Technology Organisation (ANSTO) with power from a 75 kVA high-frequency generator (750 kHz) supplied by Farfield Electronics Pty, Ltd, Australia. This enabled the slag-metal combination to be melted with turbulent stirring and is expected to be isothermal. The entire temperature gradient

Jan 1, 2007

By Timo Niitti, Antti Rinne, Janne Turunen, Klaus Schommarz, Sami Grönstrand

This paper captures the essential steps employed in developing Outotec?s new FloatForceTM mechanism. The development of a flotation mechanism essentially revolves around the efficient transfer of installed power, or capital cost, to optimum flotation performance. Optimum flotation performance will be achieved if a balance between metallurgical results, operating and capital costs is maintained. The development of the FloatForceTM mechanism was done by careful evaluation of each of these three areas. This paper focuses on how experience, CFD and laboratory equipment, pilot and plant tests are used to test and evaluate a new flotation mechanism. Validated variables include mixing profile, power draw and local air hold-up. Metallurgical and mechanical design considerations are not covered in this paper. Besides using the FloatForceTM mechanism in new flotation equipment, the FloatForceTM mechanism can be used in existing flotation cell installations, thus enabling improvements in the mixing profiles, solids suspension and metallurgical performance of operating flotation circuits. Results of several tests carried out in existing plant operations are presented.

Jan 1, 2007

By J. R. Dixon

Gold mining has been undertaken in South Africa for more than a century. A great proportion of that mining has been from the Witwatersrand Basin; a geological phenomenon that has few parallels throughout the world. It has produced some 47 000 tonnes of gold mainly from underground mines, many of which have been truly world class gold mines. The gold mines of the Witwatersrand Basin have dominated world gold production from their inception and their production has been one of the cornerstones of the development of South Africa as a whole. The mines have some very specific characteristics; their sheer size, the depth of extraction, the nature of the orebodies, and their labour-intensive methods. The mines have also been part of the Mining House concept-a concept unique to South Africa. South African production has declined from a maximum of 1000 tonnes in 1970 to 470 tonnes in 1997. This, as a percentage of western world production, has declined from a maximum of 79 per cent (in 1970) to 21 per cent of world production (in 1997). The nineties' have seen South Africa and its mining companies move onto the world stage and face the harsh realities of having to compete in all spheres of business with their aggressive counterparts principally in Australia, Canada and the USA. The fight is for investment funds with the owners looking for the best returns on their money. In his address Roger Dixon will examine the current situation in the gold mining industry and examine the competitiveness of the mines of the Witwatersrand Basin compared with their peers worldwide. He will also discuss some of the fundamental challenges facing South African gold mines in the areas of legislation, technology, industrial relations, and health and safety. The environment in which the mines operate has changed radically in recent years and their ability to respond to these challenges will determine their future existence.

Jan 1, 1998

By A. Yamik

This research study includes studies carried out on the recovery of unburned carbon in the ashes of Tuncbilek Thermal Power Plant. Bottom ashes have been identified by X-ray diffraction and X-ray fluorescence. These samples are potentially of class F type and have significant amounts of unburned coal. According to the ash amount that units in the thermal power plant produce, and the analyses of the samples mixed, which used certain amounts in flotation tests, it was found that the bottom ash includes 91.47% ash in dry form and 8.53% combustible matter, and the lower calorific value is 491 kcal/kg. Optimum flotation conditions to get the unburned carbon were subsequently determined by examination of the optimum flotation grain size, pulp density, collector type and amount, depressant type and amount, frother type and amount, agitation speed, and froth-taking time. While the lower calorific value of the thermal power plant bottom ashes of the 3rd , 4th and 5th units and the mixed bottom ash sample was, respectively, 959, 469, 279 and 491 kcal/kg in dry form, it increased to 2490, 1312, 786 and 1348 kcal/kg in the product obtained as a result of flotation in optimum conditions. Key words: ash, conventional flotation, unburned carbon

Jan 1, 2008

By J. H. van Laar, L. J. van der Walt, P. L. Crouse, H. Bissett, G. J. Puts

"SynopsisSilicon carbide nanopowders were produced using a microwave-induced plasma process operating at 15 kPa absolute and at atmospheric pressure. Methyltrichlorosilane (MTS) served as precursor, due to its advantageous stoichiometric silicon-to-carbon ratio of unity, allowing it to act as both carbon and silicon source. Argon served as carrier gas, and an additional hydrogen feed helped ensure a fully reducing reaction environment. The parameters under investigation were the H2:MTS molar ratio and the total enthalpy. The particle size distribution ranged from 20 nm upwards, as determined by SEM and TEM micrographs. It was found that an increase in enthalpy and a higher H2:MTS ratio resulted in smaller SiC particle sizes. The adhesion of particles was a common occurrence during the process, resulting in larger agglomerate sizes. SiC layers were deposited at 15 kPa with thicknesses ranging from 5.8 to 15 µm.IntroductionIt is well known that methyltrichlorosilane (CH3SiCl3 or MTS) decomposes to form silicon carbide (SiC) and hydrogen chloride (HCl) as shown in Equation [1]. The reaction kinetics and mechanisms for this reaction are thoroughly reported in the literature (Sone et al., 2000; Papasouliotis and Sotirchos, 1999; Kaneko et al., 2002; Wang et al., 2011)."

Jan 1, 2015

By R. du Preez

Tati Nickel is currently operating a hydrometallurgical demonstration plant in Botswana, using the Activox® process developed by LionOre Technology to produce nickel cathode and a cobalt salt from a sulphide concentrate. Cobalt is extracted using Cyanex 272. This reagent also extracts all the iron, aluminium, copper, zinc, and manganese from the nickel stream. Versatic 10 carboxylic acid is then used as extractant to recover nickel from the stream, separating it from calcium and magnesium, and upgrading it to provide a suitable advance electrolyte for nickel electrowinning. However, the selectivity of Versatic 10 for nickel over calcium is limited, and gypsum formation in the extraction circuit is a problem when attempts are made to maximize the recovery of nickel. Mintek has developed a synergistic system with Versatic 10 for improved separation of nickel from calcium and magnesium. Laboratory testwork was conducted on the raffinate of the cobalt solvent extraction circuit to optimize the Versatic 10/Nicksyn? (Mintek synergist) system to be employed. Extraction and stripping parameters suitable for this stream were optimized in the laboratory and then applied on the demonstration plant. A commercial batch (0.5 tons) of Nicksyn? reagent was produced for the demonstration plant. The laboratory testwork results and the demonstration plant performance are discussed in detail in this paper.

Jan 1, 2007

1. Book review • World mineral statistics 1974 to 1978. Production: Exports: Imports. London, H.M.S.O., Institute of Geological Sciences, 1980. (Reviewer: R. P. King) This edition is the third in a regular series prepared by the Institute of Geological Sciences. It is a useful compilation of statistics on the production, export, and import of fifty-eight different mineral commodities. Each mineral is listed by country, and a table is provided for the annual production, the annual imports, and the annual exports for each commodity included. However, some commodities are treated in considerably more detail; for example, aluminium and bauxite have tables under the following headings: Production of Bauxite, Production of Alumina, Production of Primary Aluminium, Exports of Bauxite, Alumina and Aluminium, Imports of Bauxite, Alumina and Aluminium. The information presented is the latest official information available from primary sources; the compilers have not relied on data from secondary compilations. This publication will be of considerable assistance to all who are concerned with the trading of mineral commodities and their production.

Jan 1, 1981

By RT White

For a number of years the steel tube and pipe industry has worked on resolving problems of product quality. These have largely been resolved and new products have been developed to take advantage of new developments. To fully coordinate market acceptance guidance on use of galvanized piping was also required. This was largely achieved locally in 2004 with the publication by the SABS of ARP 060 - Guidance on the use and application of hot dip galvanized steel piping for the transportation of potable water in South Africa. Use of this document is not easy however and a need to have a simple computer model to assist the specifier was identified. Working with a major tube and pipe manufacturer this is now being developed and this paper will provide the background to the model?s development and its intended use. There is still a need for a partner Code of Practice on the performance of galvanized piping in buried conditions and the need for this will be highlighted together with current available information.

Jan 1, 2006

By P. R. Labrum, H. A. D. Kirsten

The literature on shotcrete is reviewed with the object of identifying aspects that have not been addressed specifically in terms of its structural performance and manufacture as applied to underground mines. The programme and results of a series of full-scale tests on mesh- and fibre-reinforced shotcrete panels are presented, from which it is concluded that fibre-reinforced shotcrete is competent, especialy at large deformations, and is equivalent in structural performance to mesh-reinforced shotcrete for a fibre content of 3 per cent by mass: furthermore, that the support design systems developed for mesh-reinforced shotcrete are directly applicable to fibre-reinforced shotcrete. The Q-NATM system for the design of temporary tunnel support is presented briefly as one such system. It provides for the integrity of the excavation to be considered in terms of its competence and displacement determinateness, and represents the first systematic procedure for the design of temporary tunnel support. Finally, the support designed on the basis of the Q-NATM system for the main and cross-cut tunnels on the production level in the proposed BA5 block cave at Premier Mine is presented as a practical example of the design of fibre-reinforced shotcrete as part of an overall support system.

Jan 1, 1990

By O. Fenn

Earlier work had shown that the use of water jets at moderate pressure enhances mechanical cutting in hard rock. To assess the potential of this technique for use in conjunction with free-rolling cutters, a series of laboratory tests was conducted with disc and button cutters to determine the effect of variations in the jet and cutting parameters on the cuter performance. In these tests it was found that the use of water jets at pressure in the range 5 to 40 MPa can reduce the forces on a free-rolling cuter by 40 per cent, which represents a significant improvement in cutting performance. The reduction in thrust force was found to be dependent on jet pressure: the greater the pressure, the greater the reduction. The reduction in rolling force was independent of jet pressure over the range investigated. The results indicate that no additional improvements in cutting performance of any significance are to be gained by an increase in jet pressure above 40 MPa. The most effective jet configuration for the reduction of cuter forces was found to be four coherent water jets, two lateraly disposed on each side of the cuter and directed at the arc of contact between the cutting edge and the rock.

Jan 1, 1987

It is suggested that an increase in the production from thin coal seams in South Africa is necessary, and that a substantial amount of any increase will be mined by the bord-and-pillar method. For the purpose of this study, a thin coal seam was regarded as any seam 1,5 m thick or less to the minimum thickness at which mechanized equipment can operate in bord-and-pillar workings. The equipment being utilized in thin-seam bord-and-pillar layouts includes conventional equipment, load-hauldump cars (scoops), and drum-type and Fairchild-Wilcox continuous miners. Comparisons are made of these types of equipment for bord-and-pillar mining at various seam thicknesses within the thin-seam range. The evaluations involved production rates and the cost of extraction for South African conditions, use being made of an existing computer modelling technique in the generation of production rates. The indications are that, for seam thicknesses greater than 0,9 m, drum-type continuous miners utilizing continuous haulage are the most productive and cost-effective equipment at present operating in thin-seam bord-and- pillar workings. Where seams thinner than 0,9 m are to be exploited, Fairchild-Wilcox continuous miners, particularly the Mark 22, produce the most coal at the lowest cost.

Jan 1, 1984

By A. Singh, R. R. Maclachlan

SYNOPSIS A back-analysis procedure based upon 35 mm photography was developed on a laboratory scale for the pur¬pose of determining the percentage of oversize particles known to be present in heaps of fragmented rock. Eight simple blends of crushed stone containing varying percentages of oversize on a 1:40 modelled scale were examined. Simulated test conditions for the following were subjected to the photographic study: (1) a bench heap, (2) the surface exposure of a partially excavated heap, (3) a gravity-sorted surface as occurs on an apron dump, and (4) four quadrant views of an incrementally built conical heap of rock fragments. The best back-analysis determinations were obtained from (4), the cone, over all eight blends of fragments. The mean error was within -0,16 per cent of the true value, with a range of ± 1,872. This was for oversize contents of 5 to 20 per cent where a minimum 25 per cent of the photograph area was processed by digitizer. The worst results were from the apron dump at - 1,462 per cent for a mean error of ± 4,174 per cent. The intermediate results were from the undisturbed bench at -0,186 per cent with a mean error of ±2,862 per cent.

Jan 1, 1989