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By G. Akdogan, M. Tadie, A. Tapfuma

The Southern African region contains abundant gold tailing heaps that are an environmental concern due to dust pollution and chemical contamination of nearby water bodies. Nevertheless, these heaps contain gold with potential to be extracted for financial gain. In this study, the feasibility of extraction of gold from a Witwatersrand gold tailings using glycine was investigated using a two-level full factorial design. Effects of variables such as glycine concentration at levels of 0.5–1.5 M with a solid–liquid ratio of 50–200 g/L were investigated. Although the solid–liquid ratio used in this study was below the industrial norm, it provides a starting point for investigating the applicability of this technology. To enhance the gold extraction, potassium permanganate pretreatment and copper ion addition were adopted. The results revealed that 91.4% gold extraction was achieved after 24 h pre-treatment of the tailings using 2 g/L potassium permanganate followed by subsequent leaching using 1.5 M glycine at pH 12, with 50 g/L solid–liquid ratio and 2 g/L copper ions. Statistically, the solid–liquid ratio and potassium permanganate pre-treatment of the tailings were found to be significant at 95% confidence interval, whilst interactions of copper ions and glycine concentration were significant factors. The work demonstrates that potassium permanganate pre-treatment prior to glycine leaching of low-grade secondary gold resources, such as tailings, can be beneficial. Furthermore, the methodology developed in this work provides an opportunity for further investigation of the recovery of gold hosted in complex mineralogical matrices.

Apr 14, 2024

By C. H. Wyndham, N. B. Strydom

INTRODUCTION Acclimatization of the labour force to heat is an integral aspect of gold mining in South Africa. A recent survey revealed that about 250,000 Bantu mine workers require to be acclimatized to heat each year. Until 1965 men were acclimatized by means of one of the Chamber of Mines methods (introduced by the Human Sciences Laboratory in 1953). This type of acclimatization was carried out underground where men shovelled rock in hot stopes under careful supervision. However, it has become increasingly difficult in the last few years for mines to provide underground the conditions of work and environmental heat required for adequate acclimatization to heat. In examining an alternative to acclimatization in underground hot stopes, the Human Sciences Laboratory carried out a trial in 1965 of acclimatization in an air-conditioned climatic room on the surface of a mine. The new procedures developed from this trial have been so successful that there are today 26 climatic rooms on different mines. These rooms have been built following a design proposed by Mr Hodgson of the National Mechanical Engineering Research Institute1. Approximately 85 per cent of the total number of men being acclimatized each year are put through the new procedures in these climatic rooms. This paper gives an account of the problems which arose and how they were solved, the inter-relationship between physical conditioning and climatic room acclimatization, the prodecures developed for elimination of labourers with low maximum oxygen intakes, and the advantages of climatic room acclimatization. CLIMATIC ROOMS The majority of the climatic rooms (twenty) have been built on the surface, but a number (six) of mines preferred to establish their acclimatization centres underground in order to decrease the initial costs involved in the construction of such facilities. These underground climatic rooms are usually located near shaft stations in redundant haulages and they can accommodate from 200 to 400 labourers, thus eliminating the need for multiple acclimatization shifts. Figs. 1-4 illustrate various aspects of a surface climatic room. PROBLEMS WHICH AROSE IN INTRODUCING CLIMATIC ROOM ACCLIMATISATION There were four main problems which arose in connection with the introduction of the new method. These were: (i) The type and rate of work to be used. (ii) The air conditions required to obtain optimum acclimatization. (iii) The duration of exposure to heat each day and the total number of days of acclimatization. (iv) The methods of cooling labourers with high body temperatures. Shovelling rock would have been the desirable type of physical work to employ, but the air-conditioned space required to accommodate large numbers of men and the difficulty in standardizing the work rate in shovelling led to the decision to employ instead the work procedure used by the Human Sciences Laboratory in acclimatizing men in the Laboratory. This is the lifting of the body weight against gravity when men step on and off a bench. It has the advantage that large numbers of men can work physically at the required rate in a relatively small space (120 men can be accommodated in an area of 70 ft by 21 ft) and the cost of construction and ventilation of the climatic rooms is thereby reduced. Also the work rate can be standardized by varying the height of the stepping benches in relation to the individuals' body weights. The next problem was the air condition to be used in the climatic rooms. The Laboratory's research experience in acclimatization led it to choose an air temperature of 89°F (with the air almost saturated with water vapour) and an average velocity of air movement of 100 fpm. This air condition was combined with a work rate of 1,560 ft lb/min (oxygen consumption 1.0 litre/min) on day 1, and the work rate was increased gradually over the period of acclimatization to reach a work rate of 3,120 ft lb/min (oxygen consumption 1.6 litres/min) on day 9.

By H. J. R. Way

Dr H. J. R. Way: In his reply to my queries Mr Bath still adheres to his statement that it may be possible to replace the estimated R200 million reduction in gold revenue in 1980 by exports of ferro-chromium, and apparently based his conclusion on a growth rate in demand for corrosion resistant steels of 10 per cent per annum in the next few years. As I pointed out at the previous discussion at Middelburg this would entail a production of about one million tons of ferro-chromium in 1980. Exact statistics of South African ferro-chromium production are not available, a fact which is very much to be regretted. But statistics of exports of ferro-chromium are available from "Foreign Trade Statistics" of the Customs and Excise. These show that South Africa exported 99,580 short tons in 1967. The quantity of ferro-chromium consumed in South Africa in 1967 was fairly small and we can therefore assume that the production was 99,580 tons. For this amount to grow to 1,000,000 tons in 1980 would require a growth rate of 19.4 per cent per annum. At 10 per cent this would grow to 344,000 tons and at 7 per cent 240,000 tons. The following growth rates in the form of average trends are pertinent: STEEL - Per annum World steel ingot production - 1957-67 – 6.8 per cent Free-world ingot production - 1957-67 – 6.0 per cent Consumptions of crude steel by four major Free-world Consumers - 1957-67 - 5.6 per cent CHROMITE World production - 1952-67 - 2.5 per cent South African total sales - 1948-67 – 5.4 per cent South African exports - 1948-67 – 3.9 per cent United States consumption, very irregular, but - 1962-67 – 6.5 per cent FERRO-CHROMIUM - Per annum United States consumption - 1952-67 - 6.5 per cent South African exports - 1957-62 - 25.2 per cent South African exports - 1962-66 - 41.9 per cent South African exports - 1966-68 - 21.2 per cent These figures show that exports of ferro-chromium have been growing at a very high rate varying from 21.2 per cent to 41.9 per cent since 1957, but in view of the market situation it seems somewhat doubtful if that high rate can be maintained up to 1980. Of our 1966 exports U.S.A. took 63 per cent which was 53 per cent of their total imports. Their average consumption is trending at a growth rate of 6.5 per cent per annum from 1952-67, but the growth from 1964-66 was 5- 2 per cent and 1966-67, -12 per cent!

Mar 1, 1968

By D. V. J. W. Groenewald, T. M. Louw, L. Auret, S. M. Bradshaw, A. V. Cherkaev

Unexpected equipment failures lead to financial losses due to production disruption. Time-based maintenance, based on checks over regular time periods, has been employed to minimise disruption. However, the improvements it can offer are limited as it may lead to unnecessary service of healthy equipment or missed failures occurring between service intervals. Condition-based maintenance (CBM) provides a further improvement to equipment reliability by detecting faults and predicting remaining useful life (RUL) based on equipment health monitoring. Its application in the mineral processing industry is hindered due to the high cost of health monitoring equipment. In this study, two stochastic process models, the adaptive auto-regressive model and the gamma process, are compared in their ability to forecast the degradation state and to provide RUL prediction. The gamma process model was found to be effective in both tasks. Due to its simplicity and minimum hyperparameters requirements, it is proposed to use the gamma process as a baseline for comparison with other models. Keywords: Condition-based maintenance, remaining useful life, slurry pump, adaptive autoregressive mode, gamma process

Jan 1, 2020

By F. H. Deist, M. P. Roberts

"The Collieries Research Laboratory of the Chamber of Mines of South Africa is developing a coherent system of programs to aid in the full spectrum of activities arising in the planning of new as well as operating mining enterprises. It is the purpose of this paper to describe the design and application of two subsystems in the complex.One of these subsystems is an initial version of a production simulator. This program draws upon a model of a mining enterprise and simulates the operational and financial aspects of a set of alternative mine production plans.These plans are specified in terms of proposed sequences of operations. Details such as reserves, production rates, resource requirements and so on, are taken from the model.Physically, the model takes the form of a cross-referenced data base, maintained by means of a general file maintenance system which is another subsystem described.The paper concludes with a description and analysis of the first practical application of the two programs."

Jan 1, 2014

By C. T. O’Connor

Since the first IMPC took place in London in 1952 there have been many developments in our understanding of flotation, both in terms of chemical and physical factors influencing the process. Many of these developments have been captured in the proceedings of thirty congresses that have taken place since that first event, as well as in numerous journal papers and special volumes dedicated to flotation. This paper attempts to highlight the individual contributions which many eminent researchers and engineers have made over the past 70 years towards extending our understanding of, especially, the effects of chemical factors on flotation. Although the focus is mainly on more fundamental aspects, it seems that the ‘pull’ of practice has often preceded the ‘push’ from laboratory-based research. As the fundamental understanding of the role of chemical factors on flotation continues to be developed, the major challenge remains to transfer this knowledge effectively into the domain of operations of this profoundly complex process.

Jan 1, 2020

By I. Cerny, M. Vanek, J. Hubácek

"SWOT analyses and the closely related TOWS matrix are frequent starting points for an organization to develop its strategy. The paper deals with the evaluation of the TOWS matrix and presents three novel approaches to evaluate the different factors of the TOWS matrix, namely (1) approach to evaluate the factors with identical weights; (2) approach to evaluate factors with their weights determined within the different quadrants of the TOWS matrix; and (3) approach to evaluate factors with weights determined within the whole TOWS matrix. The third approach has two variants. The proposed approaches to evaluate the TOWS matrix were tested on a SWOT analysis of a significant mining company in the Czech Republic. The results imply that the strategy W-T (weaknesses-threats) is recommended in three cases, while the strategy S-T (strengths-threats) is recommended once. The paper may be valuable for managers responsible for strategic planning.IntroductionThe process of human needs gratification has been closely connected with raw material resources of the planet. In the contemporary socio-economic conditions, the task of the mining company managers, apart from extracting mineral resources, is to meet the owners' intents.The managerial work itself becomes very complex. In mining companies in particular, the complexity is augmented by the characteristics of the business. Undoubtedly, the key factor is that mineral resources cannot be renewed or relocated. Stojanovi (2013) characterizes mining projects as involving great investments in finance and time, as well as consecutive decisions and a 'complex mosaic of numerous unknown factors that affect the value of the project'. He adds that mining projects are typified by a 'number of geological, technological, technical, economic, environmental, social, and financial risks' (Stojanovi , 2013).Inter alia, the managerial work may also be intese due to the dynamic internal and external conditions for the existence of any company (Vane? k, 2014). This tallies with Peter Drucker’s prediction in 1969; that the times at the turn of the millennium could be expected to be turbulent (Drucker, 1969)."

Dec 1, 2018

By E. Córdova, A. Anani, W. Nyaaba

Optimization of panels, haulage fleet, and waiting area involves deterministic and low-fidelity methods and experiential knowledge. The process is challenging because coal recovery and operational capabilities must be considered in the solution. The approach in this manuscript comprises the development of an integrated stochastic simulation model of a coal room-and-pillar system that addresses these challenges. The decision variables evaluated are panel width, number of shuttle cars, and change-out time (COT). The results show that the mine should implement the shortest possible COT, decreasing the cycle time and thereby increasing productivity and continuous miner (CM) utilization. The highest productivity and CM utilization for a fleet size of three shuttle cars is found in the 15-entry panel width. For the evaluated fleet sizes, the 19-entry panel width is optimal for the four and five shuttle cars. Among the three variables studied, panel width and fleet size had the most significant effects (5% increase) on the CM productivity, cycle time, and utilization.

Apr 2, 2022

By J A. H Campbell

AK6 is a Cretaceous aged kimberlite located in the north-east of Botswana, close to Debswana's Drapa and Letlhakane Mines. It was discovered by Debswana in 1969, but was considered unattractive from an economic perspective. In 2003, Debot Prospecting Pty Ltd ('Debot') re-assessed the area and with the advent of new prospecting technology, particularly large diameter drilling ('LDD') and more detailed ground geophysical surveys found AK6 to be of interest. In 2005, the Boteti joint venture was formed between Debot and African Diamonds plc ('AFD'), which covered a number of Prospecting Licenses, including that which contained AK6.

Jan 1, 2010

By L. Roux

The initial evaluation of a coal deposit often raises uncertainty with regard to the accuracy of the reported Resources and Reserves. Reconciliation of results from mining and beneficiation with the original raw field data highlights deficiencies in original estimations. Credible Resource and Reserve estimation forms the basis on which an entire mining enterprise is motivated, initiated, funded, and established as a commercially viable proposition. This is required for sustainable extraction purposes and to support vital downstream industries such as power generation. Accurate determination of the density of the matrix of the material being evaluated is the key to credible values being obtained for Resources and Reserves. Losses between 15% and 20% of the Resource/Reserve can be realized if incorrect densities are applied to the tonnage derivation. Coal plies and particles have different relative densities, determined by the maceral composition, rank, and mineral and moisture content. These factors in turn contribute to the moisture, volatile matter, ash and carbon contents of a coal, which affect the overall density of the raw coal. More specifically, the relationship of ash to density and the effective matrix porosity were found to be critical in solving the greater majority of the problems in predictive calculations. A major deficiency identified is the inability to determine effective porosity, allowing absorption of adventitious moisture and altering the mass of the core sample. Although the volume of the raw material is altered through crushing, the change in mass after controlled air-drying, used with the original geometrical volume of the raw material, provides a credible air-dry density and allows the determination of the volumetric change related to effective porosity. This parameter can be validated through the evaluation of proximate ash using the ash-adjusted algorithm and a correction for the inherent moisture applied to also give a credible relative density value for an air-dried sample. A combination of theoretical, empirical, and reconciliatory evaluations of the available data, taken from the exploration phase through the mining process to final production, has shown that an integrated approach using the ash-adjusted density (AAD) methodology, in conjunction with other evaluative techniques, provides credible results with a considerably higher degree of accuracy than is currently possible.

May 1, 2021

By P. O. Akinseye, F. T. Cawood

Mineral royalties are one of the oldest forms of mining taxation, and were initially introduced to extract economic rents from mining. Over time, the royalty regime has become more complex as it was identified as an important policy instrument that can achieve more multi-faceted outcomes. Such a multi-tiered approach in the use of the royalty instrument is also the case with South Africa. With South Africa’s new mineral royalty regime now in place for ten years, it is perhaps time to assess its impact and effectiveness. To carry out this assessment, an econometric evaluative study was undertaken using four major commodities in South Africa, namely gold, platinum, iron ore, and coal. The study explored five different policy options for government to consider and tested them to determine the most favourable one that will realize the regime’s policy objectives. After the assessment, two major options stood out. Hence, this paper seeks to highlight which of the two options is the most favourable for consideration by policymakers. Based on that study, we find that the current structure is effective, but also recommend that the factors in the formula for refined minerals be ‘modified’ to reduce the capped profitability ratio from the current 60% to 30% and the maximum royalty rate for refined minerals from 5% to 3%. The minimum rate of 0.5% during times of depressed mineral prices and no or low profitability will not be affected.

Dec 1, 2021

By G. Akdogan, S. M. Bradshaw, A. P. Van Wyk

In the mineral processing industry, Ni-Cu-Fe-S converter matte is leached to remove base metals from a concentrate containing platinum group metals (PGMs). We investigated the atmospheric leaching process to develop a better understanding of the leaching behaviour of the base metals (Cu, Fe, and Ni) and the PGMs, in particular Ru, Ir, and Rh with respect to key process variables, acid concentration, and Cu concentration under oxidative and non-oxidative conditions. With oxidative leaching, a higher initial acid concentration resulted in higher Cu, Ni, and Fe extractions, as well as faster leaching reaction rates. A higher initial acid concentration also resulted in faster precipitation of Cu, Ru, and Ir under oxidizing conditions. Under non-oxidative conditions, Ni and Fe extraction was much slower, and the effect of initial acid concentration on Cu precipitation was less pronounced. The initial Cu concentration had a slightly smaller effect on the leaching behaviour of Fe and Ni, as well as precipitation of Ru, Ir and Rh. Moreover, a higher initial Cu concentration suppressed both Ni and Fe leaching and had a slight inhibiting effect on the precipitation behaviour of Cu, Ru, and Ir.

Nov 1, 2021

By O. S. L. Bruinsma, M. J. Matsela, D. J. van der Westhuizen

The free ligand (FL) model is an intuitive model to calculate the equilibrium concentrations in solvent extraction (SX) based on the distribution coefficient (Kd) at infinite dilution and the fraction of free ligand available for extraction. In this work, the FL model is validated to account for co-extraction of Ni and for designing the extraction and scrubbing sections of Co/Ni separation in a base metal refinery. Cyanex 272 is employed as a selective Co extractant in the process to yield high purity Ni. To enhance the loading capacity of the extractant, 50 mol% of NaOH is pre-loaded into it. Experimental and FL modelling results show that four equilibrium stages are required to purify the 99% Ni feed to a 99.97% Ni raffinate. The 53.59% co-extract with 26.76% free ligand is purified with a reflux scrub of 30 g Co/L in one equilibrium stage to 99.01%, Co in the scrubbed extract. The FL model as well as the Co/Ni/Na-analysis of the aqueous phase confirm that in the scrubbing section, Ni in the extract is mainly replaced by Co. Finally, in the one stage stripper the Co concentration in the scrubbed extract is increased from 5.6 g Co/L in the extract to 30.5 g Co/L that is partially used as reflux scrub liquor.

Dec 11, 2024

2nd CONGRESS OF THE INTERNATIONAL SOCIETY FOR ROCK MECHANICS The 2nd Congress of the International Society for Rock Mechanics will be held in Belgrade, 21-26 September, 1970. The Congress will include: working sessions, study tours, receptions, excursions introduced in the working sessions and post-congress excursions and special programme for accompanying persons. Anyone interested in rock mechanics and its applicarion may take part in the 2nd Congress. Official languages of the Congress are: English, French and German. Simultaneous translation service will be provided during the Congress. All the correspondence concerning the 2nd Congress of the International Society for Rock Mechanics should be addressed to: Sekretarijat 2. kongresa Medjunarodnog drustva za mehaniku stena Institut za vodoprivredu "Jaroslav Cerni" Bulevar vojvode Misica 43, Postanski fah 530 Beograd - Jugoslavija NINTH INTERNATIONAL SYMPOSIUM TECHNIQUES FOR DECISION MAKING IN THE MINERAL INDUSTRY The Symposium which is to be held in Montreal during the week of June 14-19, 1970, follows the Computer Symposium held in Salt Lake City this year. The purpose of the Symposium is to define the role of decision making techniques within the mineral industry and to stimulate the development of specific applications. The subject of the Symposium-mathematics, operations research and computers as applied to the mineral industry-allows a complete picture of the mineral industry in its public policy, corporate, financial and technological environment to emerge. This is another of the series of symposia on this and related subjects started in the early 1960's at the University of Arizona. Sponsorship has included a number of Universities and the Society of Mining Engineers of the American Institute of Mining. This 1970 symposium is the first to be held outside of America, and is being sponsored by the Canadian Institute of Mining, McGill University and Ecole Polytechnique. A number of delegates from South Africa have participated in these symposia and several have already arranged to attend this symposium in Montreal. Enquiries should be directed to: Secretariat, The 9th International Symposium, Department of Mining Engineering, Ecole Polytechnique, P.O. Box 50l, Snowden, Montreal 248, Quebec, Canada. 24th INTERNATIONAL GEOLOGICAL CONGRESS This Congress is to be held in Montreal, Canada, from August 21 to 30, 1972. A very detailed and extensive programme has been proposed, and includes a number of excursions. Copies of the first circular are obtainable from: The Organizing Committee, 24th International Geological Congress, 601 Booth Street, Ottawa 4, Ontario, CANADA. SYMPOSIUM ON THE RECOVERY OF PYRITE The proceedings of the Symposium on the Recovery of Pyrite, held in Johannesburg on 12th to 13th June 1969 are now available. Copies may be ordered from the Secretary, S.A.I.M.M., P.O. Box 61019, Marshalltown, Transvaal at a cost of R10.00. Papers and addresses presented at the Symposium were: Opening Address by Mr J. K. E. Douglas (President). 'The world sulphur position,' by W. C. J. van Rensburg (Member). 'The South African sulphur position,' by D. L. Taylor (Member). 'The recovery of pyrite at Government Gold Mining Areas Limited,' by R. J. Westwood (Member), G. S. Stander (Affiliate) and H. R. Carlisle (Member). 'Recovery of pyrite concentrates from colliery-waste discards-A preliminary assessment,' by W. A. Gilbert (Visitor) and E. A. Nugent (Member). 'The role of pyrite in upgrading the uranium content of Witwatersrand conglomerate ores by means of the heavy-medium separation process,' by D. J. Tutt (Associate Member). 'Pyrite recovery by jigs at Durban Roodepoort Deep Limited,' by E. J. Dominy (Affiliate), F. Diamond (Affiliate) and A. D. Graham (Affiliate). 'The storage of pyrite concentrates,' by Joan C. Campkin (Visitor) and P. J. Lloyd (Member). 'The flotation plants of the Anglo- Transvaal Group,' by L. A. Bushell (Member). 'Pyrite flotation with amines and cyanidation of the products,' by E. H. D. Carman (Member). 'Gold recovery by cyanidation from mill products obtained after pyrite flotation,' by P. G. Mrkusic (Graduate), M. Sciarone (Visitor) and H. E. Simonsen (Visitor). 'The influence of sulphydral and cationic flotation reagents on cyanidation of native gold,' by K. G. Ashurst (Visitor) and W. P. Finkelstein (Member). 'Laboratory tests on the flotation of pyrite from Witwatersrand gold ores by cationic collector,' by J. Levin (Member), and M. L. Veitch (Visitor). Closing Address, by Dr R. E. Robinson (Director, National Institute for Metallurgy).

By R. Kuyvenhoven, A. Parbhakar-Fox, X. Prieto, J. Quevedo, L. V. Danyushevsky

This paper presents the results of a study focussed on determining the distribution of cobalt in different types of pyrite of the La Estrella IOCG deposit in Chile. In the IOCG mineral deposits, where copper is the main product, the quantification and distribution of cobalt is required to correctly define the technical and economic viability of recovering cobalt as a by-product. In the La Estrella mineral deposit, seven alteration and mineralisation events were recognised through both optical and automated electronic mineralogical analysis. Of these seven events, five different types of pyrites were identified, each with unique characteristics of the pyrite crystals. Through advanced elemental analysis of these five types of pyrites, it was determined that the concentration and distribution of cobalt within the pyrite crystal is dependent on the mineralisation event. The results indicate high cobalt concentrations in the early pyrite mineralisation events, associated with relatively fine pyrite grains, and cobalt generally occurring in a solid form in the pyrite core. The late pyrite mineralisation event exhibits the lowest concentrations of cobalt, with cobalt predominantly present along the outer periphery of the pyrite. These results are relevant from a metallurgical point of view because the preferential location of cobalt within the pyrite crystal will influence the maximum metallurgical recovery of cobalt. For this, a cobaltiferous pyrite concentrate must be formed which, according to the characteristics of pyrite, must be processed with the optimal solubilisation method. The overall objective is to ensure both good cobalt recovery and a high concentration of cobalt in the leach solution resulting from pyrite leaching. Keywords: Cobalt, pyrite, IOCG, copper, metallurgical recovery, solubilisation, Chile

Jan 1, 2020

By G. Sahasrabudh, G. DeIulii, K. P. Galvin

A novel agglomeration process has been developed, utilising a concentrated water in oil emulsion as a binder. The binder is typically 95 wt% water, the remainder being an organic phase containing kerosene and the emulsifier— sorbitan mono oleate (SMO) in equal mass portions. The binder can selectively agglomerate hydrophobic particles in less than 7 seconds. The agglomeration has proven to be highly effective in recovering any particle of virtually any size, provided the particle is hydrophobic. The approach has previously been applied to coal, magnetite and silica. In the paper, sodium isobutyl xanthate (SIBX) and its much longer chain version, potassium tetradecyl xanthate (C14X), were used separately as collectors to selectively agglomerate chalcopyrite from the ore. Xanthates attach to metal sulphides, thus hydrophobising sulphide mineral particles. Chalcopyrite is a sulphide mineral; however, it hydrolyses quickly in the presence of water. Ethylenediaminetetraacetic acid (EDTA) was used to remove the oxide layer formed at the surface of the mineral particles after wet grinding, leaving behind a freshly generated metal sulphide surface. After the EDTA treatment, the ore particles were quickly conditioned at an optimised pH as well as collector concentration and agglomerated. The agglomeration achieved a copper recovery of 75% within 7 seconds, consistent with the recovery achieved by flotation over much longer time scales. Keywords: Chalcopyrite, agglomeration, froth flotation, interfacial chemistry, X-ray fluorescence, selective hydrophobisation

Jan 1, 2020

By D. F. Malan, J. C. Esterhuyse

In this study we explore the use of a novel numerical modelling approach to study the effect of pillar reinforcement on pillar stability. Case studies in the literature indicate that tendons, strapping of the pillars, and shotcrete or thin spray-on liners are commonly used to reinforce pillars. No clear methodology exists to select the type of support or to design the capacity of the support required, however. This has led to ongoing collapses in some mines in spite of heavy support being used to reinforce unstable pillars. A limit equilibrium model with confinement on the edge of the pillar was used to simulate the interaction of the support with the failing pillar. The model correctly predicts that an increase in confinement will lead to a decrease in the extent of pillar failure. As the displacement discontinuity boundary element method allows for the efficient solution of largescale bord-and-pillar layouts, the effect of pillar confinement can now be studied on a mine-wide scale. Accurate calibration of the limit equilibrium model is, however, required before this method can be used for the design of effective pillar support.

May 3, 2023

By O. S. Tinkler, K. C. Sole

Approximately 20% of current world copper cathode output is produced using a hydrometallurgical process route, generally referred to as the leach–solvent extraction–electrowinning flowsheet. Since its commercialization in the late 1960s, steady improvements in the performance and efficiency of the solvent-extraction reagents and equipment, combined with significant developments in leaching and electrowinning, have made an ever-widening range of ore types amenable to this technology. Following successful implementation on all major continents, a large proportion of growth in recent years derives from the re-emergence of copper solvent extraction in the Central African Copperbelt. This review provides a brief history of the development and evolution of copper solvent extractants and mixer-settler contactors, and the significance of the Copperbelt region in achieving commercialization and acceptance of the technology. The opportunities and challenges presented by the abundant high-grade oxide ores of the Copperbelt are contrasted with the processing of solutions derived from the low-grade mixed oxide–sulfide ore bodies that are prevalent in other geological regions. The current status of hydrometallurgical copper production in the African Copperbelt, within a global context, and a medium-term outlook for the technology are discussed.

Jul 5, 2023

By G. Akdogan, I. J. Geldenhuys, Q. G. Reynolds

Efficient recovery of titanium from titaniferous magnetite ores continues to be a promising, yet unrealised opportunity, despite significant occurrences of titaniferous magnetite deposits worldwide and the existence of established industrial-scale practices. Current smelting processes only recover iron and vanadium, while the titanium is discarded in the waste slag. These slags are stockpiled and present massive environmental challenges, while still containing value as residual iron, vanadium and titanium. The complex mineralisation of these deposits does not allow for a significant opportunity to separate the titanium and magnetite minerals through normal physical upgrading processes. An upgrading process is therefore required to derive economic value. An efficient process technology could create an opportunity to unlock all three valuable commodities. South Africa’s Bushveld Complex, the largest known deposit of its kind in the world, is known for the high vanadium content but is also associated with relatively high concentrations of titaniferous magnetite. The quality of the Bushveld Complex was one of the drivers for the establishment of the Highveld Steel and Vanadium Company in the mid-1960s. The unfortunate demise of Highveld Steel and Vanadium created an opportunity to review current practices and evaluate the best available process for this complex ore in the context of the three elements of interest. Past and current processes, the nature of these deposits and the potential to recover titanium are assessed to highlight the potential of fluxless smelting of titaniferous magnetite to produce a titania-rich slag as feedstock to the pigment, titanium metal industry in conjunction with recovery of iron and vanadium. Ilmenite smelting practices are proposed as a suitable alternative to achieve the goal, namely sustainable processing. Keywords: Titaniferous magnetite, titanomagnetite, smelting, titania slags, comprehensive processing

Jan 1, 2020

By P. Mühlen, C. Nelson

Process control optimisation depends a lot on the availability of timely data from production to give operators a chance to make adjustments before potential process upsets or disruptions happen. A lot of data is already available with newer and updated machine technologies, but what about the process upsets coming from the raw materials that we use? They are natural products and therefore they are not of a stable composition or mineralogy. The production process depends on a certain chemical or mineralogical stability of the raw materials when they come to a roaster, kiln or sintering stage. Only then can the proposed reactions take place and the equipment be operated at stable temperatures. Laboratory analytical technologies have the limitation that they depend on representative samples and have a long time delay. Therefore online (real time) analysers are used nowadays in mining applications to obtain an early indication of the actual mined or to-be-processed ore. Most available technologies can only analyse inorganic content on an oxide or elemental level. Near infrared (NIR)- based online analysers can overcome that limitation and give a real time analysis of organic as well as inorganic composition, if required on a mineral level. The paper will present two case studies where the NIR online technology was successfully adapted.: a) Optimising refractory gold ore processing at the Goldstrike roaster operation b) Optimising the sinter process at a Japanese manufacturer. Keywords: Analyser, NIR, online, realtime, gold, roaster, iron ore, sinter, mineral phase analysis

Jan 1, 2020