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PRESENT Minutes of the Annual General Meeting, held on Friday the 20th August, 1971, at 7.45 p.m. in the Boulevard Hotel, Witbank. Mr J. Meintjies in the Chair, 15 Fellows, 7 Members, 2 Associate Members and 10 Visitors. Mr Meintjies extended a welcome to all the members and their wives, and the many visitors and their wives. A special welcome to Mr Robinson the outgoing President of the Institute and Prof. Howat the President Elect and Mrs Howat. The minutes were read and adopted. The Chairman read his Report for the past year and also the Financial Statement. Mr E. Jackson proposed the acceptance of the Financial Statement and Mr Winship seconded it. Mr Meintjies thanked Mr Vic Robinson for all the help he had given throughout the past year. He also thanked the outgoing Committee for their support, and the Secretary for arranging the function. Mr Meintjies congratulated Mr Alex Bain on his election as Chairman and asked him to continue with the meeting. Mr Bain thanked Mr Meintjies for the good work which he had done in the past year and then announced the names of the Committee for the ensuing year. A. Bain Chairman G. Carlyon Vice Chairman J. Meintjies Past Chairman I. Botha E. J. Jackson A. W. L. Brereton B. D. McNiece N. J. P. Coetzee A. N. Turner B. T. Hosking W. D. Winship Mr B. D. McNiece proposed a vote of thanks to the retiring Chairman. The meeting closed at 8.10 p.m. Dinner was served and after coffee Mr Vic Robinson gave a most amusing and informative review of the Institute's activities. Mr Bain thanked Mr Robinson for his address and Prof and Mrs Howat and Mr Robinson for coming down to Wit bank for our Annual General Meeting.

The Institute has set important objectives for 1988 to make the Institute still more purposeful. Precious metals The Second International Symposium on Mining, Extraction, and Processing of Precious Metals will be held in Las Vegas, Nevada, USA, during the 118th TMSAIME Annual Meeting in March 1989. The First International Symposium on Precious Metals.

Jan 1, 1987

By C. Liu, F. Ye

"To extend the variety of lump ores that are used in the COREX shaft furnace and to optimize iron ore blending, the original evaluation method for iron ores that was proposed by Voestalpine AG has been improved. Physicochemical and metallurgical properties of iron ores, including Sishen lump ore and CVRD pellets, which are currently used in the COREX process, and three other lump ores, were assessed and compared. Ore matching principles were proposed and five optimized iron ore blending schemes designed and verified by laboratory experiments to prove the effectiveness of the improved evaluation method. The replacement of Sishen lump ore by the alternative L2 and L3 lump ores without varying the proportion of CVRD pellets could improve the degree of reduction and rate of metallization, and decrease the bonding index. Based on the results of laboratory test work and industrial- trials, an ore blending scheme of 60% CVRD, 20% L2, and 20% L3 is recommended for use in the COREX process. IntroductionIn recent years, problems such as environmental pollution and a shortage of coke and coal resources for blast-furnace ironmaking have become increasingly apparent. Based on sustainable developments in the iron- and steelmaking industries, the environmentally friendly COREX smelting-reduction process with low energy consumption was developed and introduced (Zhou and Du, 2013; Song, Lv, and Yin, 2015; Xu et al., 2016; Kurunov, 2010). The evaluation system for lump ore that was proposed by Voestalpine AG recommends that only Sishen lump ore from South Africa be used in the COREX process, because of the stringent physicochemical and metallurgical property requirements. This situation significantly hampers improvements to the technical and economic aspects of the COREX ironmaking process, especially in China (Eberle, Siuka, and Bohm, 2006). No theoretical or technical basis has been provided for the evaluation system, and the assessment approach for iron ores also presents problems that need to be discussed and resolved.The COREX process consists of two reactors: the prereduction shaft furnace and the melting gasifier as shown in Figure 1 (Wu et al., 2017). Pellets and lump ores which are charged to the prereduction shaft should have a good reducibility and metallization with a low degradation index (Li et al., 2016; Wu et al., 2011; Kumar et al., 2009; Kang, Gupta, and Sahajwalla, 2007). The properties and microstructure of the iron ore pellets which are required to achieve a high productivity and a lower fuel rate in the COREX process have been investigated (Umadevi et al., 2011). Some efforts have also been made to investigate the behaviour of lump ores in the COREX shaft furnace, including the disintegration characteristics and the reduction degradation (Umadevi et al., 2011; Zhou et al., 2015; Xu et al., 2013; Li, Feng, and Zou, 2013; Hou et al., 2014). However, few studies have focused on the optimization of ore blending for partial or total substitution of the expensive Sishen lump ore by other, cheaper lump ores to reduce the production cost. The technology for the utilization of blended lump ores in the COREX process is still in its early development stages (Zhou et al., 2017; You et al., 2017)."

May 1, 2019

By C. Liu, G. Zhu, Y. Liao

"The effect of particle size on the flotation kinetics of a low-rank coal was compared using air bubbles and oily bubbles. Five kinetic models were applied to the data from the tests to derive the relationships between the flotation rate constant, the ultimate recovery, and the particle size fraction. The results show that oily bubble flotation (OBF) resulted in a lower ash content and higher combustible recovery than air bubble flotation (ABF), especially for the -125 ??m size fraction. It was found that the flotation of a low-rank coal in individual size fractions using air bubbles and oily bubbles can be best described by a first-order model with rectangular distribution of tendency to float and the classical first-order model respectively. OBF yielded higher ultimate combustible and ultimate ash recoveries. The flotation rate constants for OBF were higher in all the models except for the fully mixed reactor model. The ultimate recovery values and modified rate constants first increased and then decreased as the size fraction decreased. The trend of the flotation rate constants as a function of the size fraction was similar in all the models except for the fully mixed reactor model. IntroductionFroth flotation is a physical-chemical separation method that is widely used in coal beneficiation for the separation of fine coal particles from associated minerals in water slurries. Since the cumulative recovery of a component in the concentrate is proportional to flotation time, the flotation process can be considered as a time-rate recovery process (Emad, Mohammad, and Bahram, 2010). Therefore, the general mathematical flotation models that incorporate both a recovery and a rate function can describe flotation time recovery profiles.The kinetics of coal flotation, as a measure of coal recovery as a function of time, have been studied in detail by many researchers. Different kinetic models have been proposed and published in the literature. The order and the rate constant are strongly dependent on the flotation conditions, such as the particle size and size distribution, the bubble concentration, the reagent concentrations, and the operating parameters (Zhang et al., 2013). The particle size has been reported to affect the flotation kinetics to a great extent (Yoon, Luttrell, and Asmatulu, 2002; Ntengwe and Witika, 2011). Numerous researchers have studied the aspects of flotation kinetics while paying special attention to particle size (Meftuni and Ibrahim, 1997; Rubinstein and Samygin, 1998; Graeme, 2012). However, the effect of particle size on the flotation kinetics of a low-rank coal has been relatively little discussed."

Jan 1, 2017

The 96th Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room of the Transvaal Automobile Club in Johannesburg on Wednesday, 11th August, 1993. OBITUARIES The President announced the deaths of the following members of the Institute during the past year. Life Fellow E.F. Laschinger. Other Members R.K. Boright, J.S. Jacobi, R.D. Power, J.H. Cannon, C.J. du Plooy, L.B. Mcrae, C.P. Rossouw, A.L. Sillars, A.W. Heugh, R.K. Briggs, P.J. Stark, and C.S. Stott. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, all rose and observed a moment of silence.

Jan 1, 1993

By M. Steyn

The coordination compound tetrakis(1,3-diphenyl-1,3-propanediona to)zirconium(IV), [Zr(DBM)4], (DBM = dibenzoyl methane/1,3- diphenyl-1,3-propanedionol) was synthesized and characterized by single-crystal X-ray diffraction. [Zr(DBM)4] crystallizes in the monoclinic space group P21/c (a = 24.769(4) Å, b = 10.216(5) Å, c = 19.314(4) Å, and = 101.541(5)°). The coordination geometry around the zirconium atom, formed by the eight O-donating atoms of the four -diketonates, is found to be a near-perfect square antiprism. Crystal packing is stabilized by C?H... interactions throughout the crystal lattice. This structure is a noteworthy example of the application of ambient condition synthesis of zirconium compounds in N,N'-dimethylformamide (DMF) as reaction and crystallization solvent, highlighting the possibilities of aerobic condition metal purification through chelation.

Jan 1, 2014

By J. Petersen, K. Shaik1, H. Kolev, Z. Cherkezova-Zheleva

Sperrylite is one of the most abundant platinum minerals globally, valued for its economic importance but also known for its highly refractory nature, making it difficult to process via the conventional route. This study explores the oxidative leaching of sperrylite using a cyanide–ferricyanide system, with a key focus on characterisation of the mineral and surface speciation under varied leaching conditions using x-ray photoelectron spectroscopy. The parameters investigated include the effect of sodium cyanide concentration, the use of potassium ferricyanide as an oxidant, copper sulphate pentahydrate as a catalyst, as well as the effects of temperature and particle size. A limited set of leaching tests was carried out to study the surface chemistry rather than optimising dissolution conditions. This approach identified mineral oxidation states and shifts in binding energies, prior to and post leaching. XPS analysis of sperrylite’s surface chemistry identified key species, comprising the bulk Pt(II)–As (≈73 eV) and As(–I)–Pt (≈41.8 eV) states, together with surface oxidation products Pt(II)–O (≈72 eV), Pt(IV)–O (≈74.5 eV), As(III)–O (≈43 eV) and As(V)–O (44.5 eV). Leaching led to the removal of pre-existing oxides on the ultra-finely ground sample, exposing the underlying bulk species. In contrast, the crystalline sample with an initial low concentration of oxides, generated higher amounts of fully oxidised species after leaching, reflecting greater surface reactivity.

Mar 6, 2026

A Seminar to discuss 'Reactivity of Line in Steel Making' was held in the auditorium of Iscor's Headquarters Building in Pretoria on the 5th August, 1971. The Institute organised this Seminar on the occasion of the visit of Dr Obst of the Rheinische Kalkstein Werke GMBH, Wuelfrath, West Germany. The latter is one of the largest lime companies in the world and Dr Obst is in charge of their research laboratory. He and his co-workers have earned a reputation for their research into reactivity of lime in steel making. This work is also of great importance to the steel industry in this country, particularly with the changes which are occurring with the introduction of basic oxygen furnaces. Some 80 persons representing most of the major steel companies attended this Seminar. Dr Obst presented his most interesting paper which he illustrated with projector slides. This paper is printed in full in this journal. This was followed by several contributions and active discussions. The first contribution was made by Dr T. B. Beeton of the Research and Development Department, Iscor. He gave a brief summary of the studies on reactive lime carried out at Iscor since 1968. Their work was particularly related to the selection and definition of the various reactivity tests and the correlation of these with plant results. He demonstrated that the DIN methods, particularly the Din (40°) test, gave the best results and reported that good agreement had been reached between Iscor, Highveld and Northern Lime on future test procedures. Mr B. Lowther of The Northern Lime Company then dealt with problems associated with the production of high reactive lime. The rotary kilns at The Northern Lime plant at Lime Acres are particularly suitable for the production of high-reactive lime, because this type of kiln lends itself to accurate control of temperatures and retention times. Several problems, however, exist. Because of the long haul distances and the deterioration of reactive lime by absorption of CO2 and water, high reactive lime is not suitable for most customers. To constantly be changing kiln conditions to produce relatively small quantities of high-reactive lime, therefore, causes problems. Highveld Steel at present is the only company requiring high-reactive lime and a satisfactory product is now being produced at a cost because kiln capacity is reduced and fuel costs are higher. Dr P. R. Jochens, of the National Institute for Metallurgy then submitted data to show how the reactivity of soft burnt reactive lime deteriorated due to long railage hauls. Detailed sampling of trucks had been carried out leaving the lime works and on receipt at Highveld and it was demonstrated that there was deterioration in the top layers of the truck. This top layer protected the balance of the lime which is still in good condition on arrival at Highveld. Exposure to atmosphere by further handling and storage into the bunkers at Highveld, however, resulted in further severe deterioration in the lime reactivity and the lime when finally fed to the Basic Oxygen Furnace is reduced to one third to one quarter of the original reactivity value. The same deterioration does not occur with normal run of kiln lime, which is burnt harder, but still has a satisfactory reactivity for most purposes. Mr A. A. Hejja of the Department of Metallurgy, Witwatersrand University then made a contribution on the metallurgical aspects of the use of lime of different reactivities in the Basic Oxygen Furnace and the effect on desulphurization efficiencies. He gave a wealth of data on actual tests which had been carried out and came up with the surprising conclusion that the deterioration of high-reactive lime due to transport did not have as serious an effect on the efficiency of desulphurization as one would have expected. The efficiency was good provided high-reactive lime in the first instance had been produced, irrespective of whether it had deteriorated thereafter. Poor efficiency was obtained only when the lime in the first instance was produced in an unreactive form. The temperature rise in the Basic Oxygen Furnace also has a definite effect. If lime is introduced when the temperature is too high, soft burnt reactive lime becomes hard burnt and unreactive before it can dissolve in the slag. Use of ferromanganese slag assists dissolution of lime. There was a great deal of discussion following these contributions. Particular interest was expres8ed in the special lime described by Dr Obst. This consists of a mixture of fine lime which is premixed with fluxes and either briquetted or pelletised. The question of injecting finely ground lime as an alternative was also discussed. Both these systems eliminate the necessity for highly reactive lime. With smaller lime particles, larger surfaces are exposed thereby ensuring more rapid dissolution in the molten slag. The discussions generally were lively and informative and all present derived benefit from learning of the experiences of others. The valuable contribution made by our German visitor, Dr Obst, was particularly appreciated. The instantaneous English-German translation service which was provided, greatly facilitated discussions.

By C. Klutke

This paper outlines a simple methodology for mineral characterization, developed as part of the Australian Mineral Industry Research Association (AMIRA) managed research project P777 ?The Development of Heavy Suspension Techniques for High Density Separations (Replacement of Clerici?s Solution)?. The project was sponsored by De Beers, Rio Tinto and Iluka Resources. Heavy mineral characterization of samples arising from exploration, mining or metallurgical processes is frequently conducted using laboratory heavy liquid analysis. Unfortunately, there are only a limited number of high density (?heavy?) liquids and these tend to be more toxic as their density increases. Low-toxicity inorganic solutions, based on tungsten compounds, have been developed that can be utilized at relative densities (RD) up to 3.0. Beyond this value organic liquids can be used; however, this presents significant health and safety hazards. Diiodomethane (methylene iodide) having a relative density of 3.31 is commonly used. Mixtures of thallium formate and thallium malonate were found in the early 1900s by Clerici to provide liquids having specific gravities between 4.0 and 5.0. For the characterization of the heavy components of mineral sand deposits (e.g. anatase RD 3.9, rutile RD 4.2, ilmenite RD 4.4?4.7 and zircon RD4.6?4.8) there is currently no heavy liquid alternative to Clerici?s solution. Clerici?s solution is highly toxic and testing is now conducted by few laboratories worldwide, with costs reflecting the chemical costs, infrastructure costs and health and safety regimes (e.g. blood testing of exposed staff). A simple laboratory technique of density fractionation has been developed, employing suspensions of fine tungsten carbide particles in lithium heteropolytungstates solutions, that can replace Clerici?s solution in the evaluation of fine mineral sands samples (e.g. -250 +150microns). The developing methodology that can achieve low-cost, low-toxic separations at relative densities above 4.0 is outlined and the comparison of results with Clerici?s solution presented. In addition, preliminary work on density fractionation of zircon samples is presented. Zircon fractionation relates to their inclusion, radionuclide content and metamictization.

Jan 1, 2007

Papers of Interest The following papers may be of interest to members. APCOM The Thirteenth International Symposium on the Application of Operation Research and Computer Techniques for Decision Making in the Mineral Industries will be held at the Technical University CIausthaI, Federal Republic of Germany, from 6th to 11th October, 1975.

Jan 1, 1975

By M. Grave

Rock Engineers are required to design safe cost effective support systems and stoping layouts for their respective mines. As each stope has its own unique environment, continual re evaluation is required in all stopes to maximize extraction and achieve value from the support standard. This paper presents numerical modelling used to plan early mining within the shaft pillar and a reevaluation of an existing stope support standard.

Jan 1, 2009

COUNCIL The following served on Council during the year under review Office Bearers Dr J. P. Hugo (President), P. W. J. van Rensburg and Professor R. P. Plewman (Vice-Presidents), Professor D. D. Howat (Immediate Past-President), and D. G. Maxwell (Honorary Treasurer). Ordinary Members of Council H. P. Carlisle (until February), R. C. Espley-Jones, G. H. Grange, Dr D. I. Legge, W. W. Malan, J. B. Mudd, Dr R. E. Robinson, Dr M. D. G. Salamon, L. W. P. van den Bosch, D. A. Viljoen (co-opted May 1973), and P. A. von Wielligh. Branch Chairmen A. Bain (Witbank-Middelburg Branch), C. J. Isaac (O.F.S. Branch). Past Presidents Serving on Council R. J. Adamson, M. Barcza, H. Britten, J. K. E. Douglas, R. C. J. Goode, P. Lambooy, Professor J. de V. Lambrechts, Dr J. T. McIntyre, J. F. Reid, and V. C. Robinson. Ten Council meetings were held during the year, with an average attendance of 18, and the standing committees held 29 meetings. MEMBERSHIP Twelve Fellows, ten Members, twenty-one Graduates, eleven Associates, thirty-one Students, and forty-two Company Affiliates were elected during the year. One Member was reinstated. Eight Fellows, two Members, and two Associates were admitted to retired membership. Four Graduates were transferred to Members, one Associate to Member, three Students to Members, one Graduate to Associate, two Students to Graduates, and one Student to Associate. Your Council records with deep regret the death during the year of the following : D. R. Campbell, J. Daniel, M. J. Dennehy, and F. S. C. Rogers (Life Fellows) ; W. T. balling and T. Pryor (Life Members); C. Boocock, W. Drake R. J. Moore, M. P. Pearse, J. M Pike, W. A. Schwezoff, A. I. Suss man, and L. G. S. Wright (Fellows) ; A. F. Chalmers (Member) ; and W. R. Gerry and G. T. Rimmer(Associates). A comparative statement of membership as at 30th June, 1973, and the end of the previous year it shown in the following tabulation: 30th - 30th June, - June, 1972 - 1973 Honorary Life Fellows 5 - 4 Honorary Fellows 13 - 9 Life Fellows 181 - 177 Fellows 541 - 536 Members 479 - 487 Graduates 115 - 128 Associates 182 - 186 Students 162 - 183 Company Affiliates 24 - 64 1 702 - 1 774 JOURNAL The papers that were published in the Journal during the year are listed below: August, 1972 The effects of chromium oxide, iron oxide, and calcium oxide on the liquidus temperatures, viscosities, and electrical conductivities of slags in the system MgO-Al2O3-SiO2, by M. S. Rennie, D. D. Howat, and P. R. Jochens A study of the dust exposure of South African white gold miners, by R. J. Page-Shipp and Elizabeth Harris A forecast of the coal and uranium requirements for electric power generation in South Africa, by E. J. Maunders September, 1972 Mine management by objectives, by A. A. Hazell Some aspects of the deformation behaviour and temperature rise during instantaneous compression loading of high purity aluminium, by H. J. E. Hamel Computer control of flotation at the Ecstall concentrator, by M. P. Amsden, C. Chapman, and M. G. Reading Optimizing the public gains from the exploitation of mineral resources, by A. Azis and J. Zwartendyk October, 1972 Presidential Address: Nuclear energy: its interactions with mining and metallurgy, by J. P. Hugo Presidentsrede: Kernenergie: sy wissel-werkinge met mynbou en metallurgic, deur J. P. Hugo Raise-boring experiences in the gold mines of the Anglo American Corporation Group, by J. W. Wilson and P. C. Graham November, 1972 Materials for winding plant components, by G. T. van Rooyen An analytical solution to the batch-comminution equation, by R. P. King A new approach to the study of human factors in stope productivity, by A. C. Lawrence Fundamental studies of the flotation process: the work of the National Institute for Metallurgy, by N. P. Finkelstein and V. M. Lovell Growing use of deionised water in surface coating techniques, by W. F. Lorch December, 1972 The development and application of a computer system to aid in the planning of production in mines, by F. H. Deist, L. F. Duvel, J. D. Austin, and H. D. Small PERT, and how PERT techniques can be used in modern mine management, by E. J. Boome and A. C. Schmidt A critical comparison of specific cooling power and the wet kata thermometer in hot mining environments, by J. de V. Lambrechts January, 1973 Liquidus temperatures in the Cr-Fe-Si system in the composition range representative of ferrochromium-silicide produced in South Africa, by J. C. M. Wethmar, D. D. Howat, P. R. Jochens, and O. A. W. Strydom Platinoids in the Witwatersrand System, by C. A. Cousins The development of a continuous recording scintillation counter mounted on a cyclometer, by P. D. Teens and D. Visser February, 1973 Computer analysis, modelling, and optimisation of gold recovery plants of the Anglo American Group, by M. I. Brittan and E. J. J. van Vuuren The significance of the mineralogical and surface characteristics of gold grains in the recovery process, by C. E. Feather and G. M. Keen Statistical valuation of diamondiferous deposits, by H. S. Sichel March, 1973 The effect of the reactivity of lime on desulphurisation efficiency in the basic oxygen furnace, by A. A. Hejja, D. D. Howat, and P. R. Jochens A review of real-time particle size analysers, by A. L. Hinde In situ measurements of the surface heat transfer coefficient in underground airways, by K. R. Vest April, 1973 An investigation into the kinetics and mechanisms of the oxidation of iron (II) by oxygen in aqueous chloride solutions, by R. P. Colborn and M. J. Nicol Electric smelting at Rustenburg Platinum Mines Limited of nickel-copper concentrates containing platinum-group metals, by J. C. Mostert and P. N. Roberts Metallurgical considerations in the

Jan 10, 1973

By A. Tosun

Muckpile fragmentation formed by blasting depends on the specific charge factor, the discontinuities in the rock mass, and the rock strength. Determination of the discontinuity characteristics and rock strength is a long and difficult process. These two parameters are directly associated with the rock drilling speed. Therefore, it is the drilling speed of the machine used for the blast-hole, rather than the blasthole discontinuity characteristics and rock strength parameters, that is used in the prediction of muckpile fragmentation before blasting. Primarily, it has been suggested that the muckpile fragmentation values can be correctly determined by establishing correlations between the efficiency of the loader and muck pile fragmentation, since fragmentation is directly correlated with the former parameter. Subsequently, a correlation predicting the drilling speed of the drill machine was developed according to the discontinuity characteristics of the blasting surface and the rock strength. Finally, a correlation was developed predicting muckpile fragmentation according to the specific charge factor and the drilling speed of the drill machine The data was obtained by conducting blasting tests in two different limestone quarries.

Nov 30, 2022

By W. S. Nel

Training in the mining industry by W. S. Nel, B. A. (Wits) (Visitor) After defining training and discussing the present level oftraining in the South African Mining Industry, the paper proposes the adoption of a centralized training system for the Industry and suggests several ways in which this should function. The finance required for the implementation and running of such a system should be obtained from State aid and from the institution of a levy and grant system for the whole Industry.

Jan 7, 1974

By Christopher J. Oates

Overview ? Mining Codes ? Best Practice ? Mining Standards Guidelines ? Get it right from the start ? External Auditors ? The 5% rule ? MMCRM's - The Key Components ? The MMCRM Report / Certificate ? MMCRM's & Round Robins ? Summary

Jan 1, 2005

By N. Moemise, M. B. Shongwe, P. A. Olubambi, M. M. Ramakokovhu

"Near-infrared (NIR) spectroscopy sorting technology is incorporated in an automated optical mineral sorter that can discriminate between materials using the differences in characteristics when exposed to near-infrared radiation. During September 2014 to April 2015, a pilot plant that utilized NIR technology to discriminate between kimberlite and waste materials was commissioned to determine the viability of including this technology in the diamond winning process flow sheet at Cullinan Diamond Mine. The plant was used to minimize the waste content in the size fraction -70+35 mm that reports to the crushing section and then to the dense media separation process. This paper describes the initial test work, conducted at Mintek, that led to the decision to conduct a pilot-scale study. The mineralogical characterization of the feed and product streams to establish the sorting criteria and the operational data obtained during the pilot plant campaign are described. The results indicated a good possibility of discriminating between the kimberlite and waste material using NIR technology. However, the consistency of discrimination was not good enough to avoid the risk of potential diamond loss. Furthermore, a lower than expected availability of the machine reduced the throughput capabilities. IntroductionUsing near-infrared spectroscopy (NIRS) technology for ore sorting is a new concept for the mineral processing and mining industry. NIRS has been used for decades in the laboratory for the identification of pure minerals, and has its roots in the recycling, food, and pharmaceutical industries (Salter and Wyatt, 1991; Robben et al., 2009). Ore sorting in itself is not a new concept; it was introduced during the Stone Age with handsorting being the first method to separate valuable materials from gangue (Wills and Napier-Munn, 2006; Sassos, 1985). However, over the years the scale of mining has increased and hand-sorting has become challenging to implement (Joensson, 2014).Sensor-based sorting is an advanced technology that can help overcome problems such as ore dilution experienced in mineral processing operations. The benefits are lower energy and water costs, reduced ore dilution, lower environmental impact, and improved profit margin (Mathew, 1974; Jonsson, 2014; Salter and Wyatt, 2009; Death et al., 2009). In sensor-based sorting, materials are mechanically sorted based on certain physical properties that are detected by a sensor (Dalm, 2013). Research has found that with NIR scanners it is possible to obtain a ‘fingerprint’ of a sample that is directly related to its mineralogical composition. According to Woutruba et al. (2009), molecules absorb NIR radiation by means of electronic and vibrational transitions. Nowadays, there are many sensors available in the market that utilize different material properties; the choice of a sensor is dependent on the mineralogy of the ore."

Jan 1, 2016

By J. Nell

Heavy mineral deposits often contain relatively high levels of radioactive elements (thorium and uranium in particular).It is difficult to obtain clean separation of ilmenite and monazite (the main impurity mineral containing radioactive elements), and physical intergrowths of the two minerals are, in fact, not uncommon. As a result, ilmenite concentrates obtained from such deposits often contain high levels of thorium and uranium. Because of the large negative free energies of formation of ThO2and U3O8boththorium and uranium report to the slag during smelting and if an ilmenite concentrate contaminated with monazite is used to make high titania slag, the concentrations of these elements in the slag end up about 40% higher than in the ilmenite feed. Previous work, patented by RGC Mineral Sands Limited, and subsequently confirmed by Mintek, showed that radioactivity may be reduced by roasting an ilmenite concentrate with borax at 1000°C to 1100°C and leaching it with hydrochloric acid1. It is evident that the cost of an ilmenite roast/leach process will be high and there may be economic benefits in removing the radioactive elements from the slag instead (the volume of slag to be treated is smaller than the volume of ilmenite feed). To remove radioactive elements from the slag it is necessary to know how these elements occur in the slag. Inother words, the distribution of uranium and thorium between the various oxide, silicate and metallic phases in high titania slag must be determined. Once the deportment of thorium and uranium between the various phases ha sbeen determined, an appropriate process for slag purification can be developed. Test samples High-titania slag was prepared in a pilot-scale DC furnace from ilmenite concentrates with different levels of uranium and thorium. Subsequently, ten slag samples representing a range of compositions were selected for bulk chemical analysis, scanning electron microscopy and micro-analysis. The samples were crushed to a maximum particle size of 1 mm and from each sample a 20-kg batch was riffled out for analysis. Bulk chemical composition Chemical compositions of the samples selected for test work are given in Table I. TiO2, Al2O3, SiO2, MgO, MnO, FeO and V2O5were analysed by ICP-OES, Na2O, CaO andCr2O3by atomic absorption spectroscopy and U and Th by XRF (the XRF detection limit for U and Th was around 4 ppm). The ?B? series has a higher silica content than the others as a result of small silica additions that were made during smelting. All samples have elevated alumina levels as a result of furnace refractory contamination during smelting. As expected, there is an inverse relationship between the concentrations of TiO2and FeO in the samples (Figure 1).The TiO2and FeO levels are similar to the levels found in industrial slags2. Extreme conditions of reduction under which reduction of more ?refractory? oxides (e.g., chromia, magnesia, silica, alumina and even urania and thoria) might take place were not explored in the study. Note that BB1and BBB1 contain more than 7% combined silica and alumina (SiO2as a flux addition during smelting, and Al2O3from refractory contamination) and they do not fall on the general trend defined by the other samples. The U and Th concentrations of sample E2 is noteworthy. In the preparation of slag E2, monazite concentrate was added to the ilmenite to increase the concentrations of radioactive elements in the slag. This was done primarily to facilitate the detection of Th and U during the phase chemical characterization of the slag. Radioactivity measurements Gamma ray emissions from the samples were measured [ ]

Jan 1, 2007

By J. A. Kinnaird, B. J. Youlton, K. L. Youlton

Methods for treating and processing refractory gold ores are well established. However, what is less well understood is how the formation of the gold-bearing deposits affects gold processing and extraction. In order to evaluate the effect of ore genesis on gold extraction a number of South African gold deposits were studied. These included complex Pilgrim’s Rest samples as well as refractory Fairview, Barbrook, and Consolidated Murchison samples. We found the refractory nature of gold ores is controlled by a limited number of well-understood mineralogical factors. Solid solution gold is linked to low temperature and pressure conditions in fine-grained sedimentary lithologies, while reactive pyrrhotite can form from hydrothermal fluids associated with mafic magmatic rocks. These formational controls can be used to identify and avoid complex deposits at a desktop study phase, or address and reduce complications further along the pipeline using early mineralogical studies.

Jun 1, 2021

By W. K. Brinsden

In August 1965, the late Mr Alan Smith, then Mill Superintendent at Gold Mines of Kalgoorlie (GMK), Australia, asked me to investigate the planting of vegetation on the GMK slimes dams in order to ease the dust problem in urban and industrial areas-a problem that is caused largely by dust from these barren slimes dams. My early sources of information were the comprehensive papers in various issues of the Journal of The South African Institute of Mining and Metallurgy. However, the climate of Johannesburg differs from that of Kalgoorlie. The average Johannesburg rainfall, which falls mostly in summer, is 730 mm, and the average maximum summer temperature is 26°C (top 34°C). The winters are cool, the average maximum being 18°C (low -7°C). Kalgoorlie, on the other hand, receives, on average, 257 mm of sporadic rainfall, has hot dry summers with an average maximum of 35°C (top 45°C), and cool winters with an average maximum of 18°C (low -2°C). My obvious choice was to look at established trees growing on the GMK lease. A number of Athel pines were growing vigorously adjacent to the Oroya mining and geology offices and also on a nearby sand dump. The Athel pine (Tamarix aphylla), which is native to North Africa, Asia, and India, was originally introduced into Australia in 1936 by Mr Essington Lewis, then manager of BHP. His cuttings were planted in Whyalla, where some difficulty had been experienced in finding trees and shrubs that would flourish despite the district's low rainfall. In August 1965, cuttings of approximately 20 cm length and 1 cm diameter were taken from the GMK trees, stripped of leaves, and placed in jars of water in the sun. When the cuttings had sprouted both leaves and roots, they were planted in local soil in tins (about 20 cm high and 10 cm in diameter), and watered daily. In October 1965, when the new shoots were about 8 cm long, the trees were transplanted onto a lower flat section¬approximately 30 m wide, 30 m long, and 2 m high-of the Trafalgar slimes dam. No additional soil or fertilizer was used, and the trees were planted in their tins, the bases of which had been removed (the tin would eventually rust away). A few common varieties of non-prickly cactus and two native salt bush (spp Atriplex) were also planted, but did not survive, probably because of the acidity of the slime. During the summer of 1965/1966, Kalgoorlie's rainfall was 88 per cent above the average, and this probably helped the trees to survive. The moisture content was usually about 2,5 per cent from about 10 cm below the surface, and the pH value of the slime (d80 approximately 75 µm) was about 6. The trees were watered twice a week for the first four months and then left untended. By 1974 they had grown to only about 0,7 m, which indicated that their growth in slime was very slow. Other Athel pines were planted on the wall of the dam, but did not survive beyond 1974, probably because of the steep (about 500) slope and the hardness of the walls, which were initially formed by hand-shovelling of the slime as the height of the dam was raised. Five of the six Athel pines planted in 1965, which probably reached maturity (approximately 5 m in height) in 1981-16 years after being planted-have survived. In the early 1980s, waste rock had to be dumped on the dam, but the management of KMA (now KCGM) took care to ensure that the trees were not buried. Trials are being conducted on other tailings dams so that the performance of cuttings taken from the trees on Trafalgar dam can be compared with that of cuttings taken at various sites in Western Australia. It might also be worth while for an attempt to be made to strike cuttings from Trafalgar dam in pots containing different mixtures of soil and slime.

Jan 1, 1991

By D. J. de Clerk

Global trends stipulate the need to optimize existing assets while reducing environmental impacts. This paper illustrates the procedure that was followed to achieve such goals at one of the coal burning flash dryer units at an Anglo American smelter. An in-depth study of the process and related literature led to the development and installation of a revised control philosophy. This system includes modifications to the existing regulatory control structure as well as a hybrid rule-based and model-predictive advanced process control (APC) layer. Since commissioning of the APC, this flash dryer?s average throughput has increased by more than 6%, despite higher feed moistures. Furthermore, even though coal consumption has increased slightly, operating efficiency has improved by close to 5%. This was made possible by improving stability of the drying column outlet temperature by approximately 40%, which in turn enabled selection of a more optimal setpoint. Recent data has shown that APC utilization now exceeds 95%. This is indicative of a successful controller installation with good site acceptance. The same philosophy has therefore since been rolled out to most of the other flash dryers in the group.

Jan 1, 2012