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By D. D. Aksenova, V. A. Ignatkina, L. A. Samatova, A. V. Lygach, E. D. Shepeta

Calcium minerals such as scheelite, phosphate, apatite are valuable minerals, which have similar flotation properties to the calcium gangue minerals. An additional problem is the fine dispersion and close mineral association of valuable and other minerals. Low polar compounds (non-ionic surfactant), such as fatty iso alcohols, neonol and phosphol, and their combinations with sodium oleate have been studied using flotation of monominerals and ore flotation; ATR IR spectroscopy and TEM for study surface of minerals; UV spectroscopy for control solubility, aggregation and de-aggregation processes. Increase in solubility of fatty acid collectors was confirmed by low soluble (heteropolar) compounds. Oxyethylated esters of phosphoric acid are adsorbed on phosphorite by -O2PO2R2 and on other rock minerals by donation of OH bond. Same effect shows difference of adsorption of fatty iso alcohols on calcite and scheelite. The different forms of adsorption of ionic and nonionic compound on a sparingly-soluble mineral surface creates distinction of the flotation kinetics and technological balance of ore flotation. The results of the separation of flotation of scheelite from calcite depend on the order of pouring into pulp of fatty iso alcohols and oleate, and their ratio in the mixture. Increasing scheelite recovery into rougher scheelite concentrate by 3.6% for both the flotation and sludge classes was obtained. Calcite recovery varied slightly upwards or downwards by 0.8-2.4%. The use of the non-ionic surfactant phosphol in combination with a fatty acid soap allows for obtaining a phosphate concentrate with more than 28% P2O5 content and almost 80% recovery in flotation operation. It is not obtainable with other reagent regimes. Keywords: Flotation, calcium minerals, oleate, fatty isoalcols, neonol, oxyethylated esters, adsorption

Jan 1, 2020

By N. R. Williams

Black Mountain, a polymetallic base metal mine located in the Northern Cape territory of South Africa has been blessed with high grade economic ore for many years. Now that the Broken Hill orebody is nearing the end of its life, a lower grade orebody (Swartberg) is being exploited to supplement production from Broken Hill. In addition, ore from stopes in the upper levels of the Broken Hill orebody is considerably tarnished (oxidized). As a natural result, the remaining ore contains a higher percentage of magnetite, pyrrhotite and pyrite than in earlier years. Bismuth, cadmium and cobalt also occur in the ore in higher quantities. The life of the mine has been lengthened with the discovery of further deeper-lying ore reserves extending from the Broken Hill orebody suitably called the Deeps section. However, to bridge the gap between development of the new reserve and the exhaustion of the old reserve, these lower grade and tarnished (oxidized) ores have to be treated. The mine has had reasonable success in identifying unfavourable or problematic ore types and stockpiling them separately to blend in small quantities with more favourable ore. Bench and plant scale tests have aided identification of the various ore types and significant improvements in flotation metallurgical results have been seen. Copper, lead and zinc metal occur as sulphides in the ore. The mill consists of a differential and sequential flotation process that extracts copper concentrate, lead concentrate and zinc concentrate respectively with silver metal recovered in the copper and lead concentrates. This paper describes the ore blending strategy employed at the mine to maximize the econo-metallurgical efficiency of the operation.

Jan 1, 2001

By R. Katzenbach, M. Vogler, U. Adamietz

Abstract The design of deep excavation pits in rock mass is dependent as well on the mechanical properties of the rock mass as for example the orientation and the type of discontinuities like bedding planes, joints and fissures, the length of the discontinuities (persistence), the grade of weathering, the strength of rock mass, and the shear strength in the discontinuities, etc., and also on the respective boundary conditions specific for the project, and here especially the geometrical boundary conditions. The basic mutual influences and interactions between these boundary conditions are explained and exemplary presented at an excavation pit with a depth of 18,5 m, situated at a slope with a surface near groundwater table. Résumé La planification des excavations profondes dépend aussi bien de la qualité mécanique du roc, par exemple la location de la texture de la surface de moindre résistance, le degré de rupture, le degré de décomposition, la dureté du roc et la résistance limitée au cisaillement de la texture de la surface de moindre résistance que des conditions limitées spécifiques pour le projet, ici en particulier des conditions limitées géométriques. Les influences et interactions essentielles et mutuelles entre les conditions limitées isolées seront expliquées et présentées à l’aide d’une excavation 18,5 m de profondeur, située sur une pente où le niveau des eaux souterraines est près de la surface. Kurzfassung Die Planung tiefer Baugruben im Fels hängt sowohl von den mechanischen Eigenschaften des Fels wie z.B. der räumlichen Lage des Trennflächengefüges, dem Durchtrennungsgrad, dem Verwitterungsgrad, der Gesteinsfestigkeit sowie der Scherfestigkeit des Trennflächengefüges als auch von den projektspezifischen Randbedingungen hier insbesondere von den geometrischen Randbedingungen ab. Die wesentlichen gegenseitigen Einflüsse und Interaktionen zwischen den einzelnen Randbedingungen werden aufgezeigt und an einer 18,5 m tiefen Baugrube in Hanglage mit oberflächennahem Grundwasser vorgestellt.

Jan 1, 2003

By J. S. Harington

Our purpose is to record and to explain the widely changing numbers of the huge total of black workers on the gold mines of South Africa over the century from 1896 to 1996. These men were recruited from up to twenty territories, and their contributions are examined. The major areas providing labour over this long period have been Lesotho, the former Transkei within South Africa and Mozambique. From 1989 to 1996, for instance, these three areas accounted for over sixty per cent of the total labour force (tlf). Our principal Figure 1 shows the tlf fluctuating through time to reach a peak of 480 000 in 1988. Irregular falls are also documented with the most serious in 1995 to 180 000. Based on this graph we consider the political, economic, sociological and historical reasons behind these changing employment opportunities. These have included external world-scale events such as war or depression, as well as internal changes of national economy and policy. We show the importance for numbers employed of the discovery of gold in the Orange Free State in 1946, the influence generally of the ?Winds of Change? and the firm maintenance by the State of law and order. Varying gold production costs and profitability against high tax rates, allied with increasing wages and a lack of development capital, have led in the last decade to employment falling by fifty per cent, despite an actually higher value of gold output. Finally, this analysis considers the role of the migrant labour system as it affects, and is affected by, conditions in the gold mining industry, with special reference to its less than humane consequences in the numerically dominant territories of Lesotho and Transkei.

Jan 1, 2004

By M. Castelli, C. Scavia, S. Marello, A. Allodi

ABSTRACT – This paper investigates the possibility of interpreting the shear band evolution in hard soils and soft rocks as the result of shear propagation from pre-existing natural defects. Thesis done through the application of the principles of Fracture Mechanics, a Slip-Weakening Model(SWM) being used to simulate the non-linear zone at the tips of the discontinuity. Experimental observations have been carried out on prismatic samples of Beaucaire marl through biaxial compression tests in plane strain conditions. A numerical simulation confirms the validity of the proposed approach. RÉSUMÉ – Cet article présente la possibilité d’interpréter l’évolution des bandes de cisaillement dans les roches tendres et les sols raides comme le résultat de la propagation pour cisaillement à partir d’un défaut préexistant. Le Slip-Weakening Model (SWM) a été employé pour modéliser la zone non linéaire a l’extrémité d’une discontinuité. Nous présentons des observations expérimentaux obtenues à travers des essais de compression en déformation plane sur des échantillons prismatiques de marne. La simulation numérique d’un essai confirme la validité de la méthode proposée. KURZFASSUNG – Die vorliegende Arbeit versucht die Ausbreitung von Scherzonen in(bindigen) Böden und im Lockergestein anhand der Entwicklung von Scherrissen ausgehend vonexistierenden Schwachstellen zu erklären. Die Umsetzung erfolgte mit Hilfe der Bruchmechanik,für die Modellierung der nichtlinearen Zone an den Rissenden wurde ein Slip-Weakening-Modell(SWM) eingesetzt. Es wurden zweiaxiale Druckversuche an prismatischen Probekörpern vonBeaucaire Mergel unter der Bedingung eines ebenen Verzerrungszustandes durchgeführt. Dienumerische Untersuchungen bestätigten die Annahmen der untersuchten Theorie.

Jan 1, 2003

By K. Moxham, R. G. B. Pickering

Over the last few years Lonmin Platinum and Sandvik have embarked on a unique partnership of collaboration through a systematic approach to developing equipment to mechanize and automate narrow reef platinum mining. After the initial design and manufacture of the equipment the key aspect is the integrating equipment, people and method into a mining system. Another key a spec of mechanization is the optimization of equipment utilization and this philosophy has ensured continual evolvement of mining methods. This paper describes the trials and development that have resulted in the mining method described as Lonmin mechanized breast.

Jan 1, 2006

By H. Lagendijk, I. J. Reinecke

Mintek was contracted by Oriel Resources plc in 2004 to conduct a preliminary assessment study on smelting ferronickel from the large but relatively low grade Shevchenko nickel ore deposit in Kazakhstan. A detailed feasibility study (?DFS?) was awarded to Bateman BV following promising results from the preliminary assessment study (?PAS?) and small-scale pilot plant test work. As part of the DFS, a total of 450metric tons of ore was collected from three different locations in the deposit and shipped to Mintek. After sampling, the bulk sample was prepared for smelting. This comprised crushing, screening and calcining with each step done separately for the three different lots. The chemical composition of the ore from the deposit is relatively high in silica and therefore falls out of the MgO to SiO2 range that is normally processed by pyrometallurgical means to produce ferronickel. The main objective of the testwork was to demonstrate that a method could be found and successfully applied to smelt these siliceous ores and produce an acceptable nickel-containing alloy. A 2-m ID DC arc furnace was installed with a twin-cathode (electrode) configuration to replicate the proposed commercial-scale furnace and also incorporated an advanced design of water-cooled copper panels in the lower furnace sidewalls to withstand the aggressive nature of the high SiO2-containing slags. The reductant used was a high-volatile coal from Karaganda in Kazakhstan. The reductant addition was adjusted to achieve a 90% recovery of nickel. In the assessment of the process metallurgy, some deviation from equilibrium conditions was observed. This deviation is ascribed to the intermittent existence of a smelting bath partially covered with feed during the testwork. Optimization of smelting conditions should result in the metallurgy (slag metal equilibrium) being closer to the theoretical predictions and make the production of a 20% nickel alloy possible at 90% nickel recovery. The solution for the successful processing of these siliceous ores was found in the attainment of the necessary operational stability through the control of arc length, operating temperature, open-bath smelting conditions and flux additions of up to 10% dolime for the most siliceous of the three ore types. The test work carried out by Mintek provided the basis for the process flow sheet and engineering design of the DC arc smelting furnaces for the Shevchenko Nickel project.

Jan 1, 2007

By S. A. Scott

Mintek developed the MinataurTM leach-solvent extraction-precipitation technology as a cost effective, easily operated alternative to conventional gold refining processes. The technology was first commercialized at the Harmony Gold Refinery in 1997 to produce 99.99 per cent gold product and has subsequently led to development of various value-addition steps including the casting of various investment bars, gold wire drawing and gold potassium cyanide powder production. In addition to refining gold to high purity, if an appreciable amount of silver is present in the feed material it is also refined to 99.99 per cent purity. The major advantage that the Minataur? technology has over other gold refining processes is the relatively low gold lock-up and reduced operating costs. The operating cost1as at April 2001 for the expanded Harmony refinery (24-ton per annum gold production) was approximately half that of conventional smelting and toll refining. The extractant employed for solvent extraction is relatively cheap and highly selective for gold, making the technology attractive in situations where significant quantities of platinum group metals or base metals are present.

Jan 1, 2004

The validity of a steady state assumption made by Adams and Nicol (1986) in the modelling of the elution of gold from activated carbon was investigated. It is shown that the accuracy of the steady state approximation is dependent, not only on the magnitudes of the solution flow rate and reactor volume, but also on the lumped elution rate constant. Under the experimental conditions used by Adams and Nicol (1986) the steady state assumption was inaccurate. This could be circumvented in this instance by applying a rigorous general model which accounts for unsteady state behaviour in the solution and in the activated carbon to the experimental data.

Jan 1, 1997

By A. Muwila

Hercules? is a low nickel austenitic stainless steel developed at Mintek that has a typical composition of 9 wt% Mn, 0.05 wt% C, 2wt% Ni, 0.25 wt% N and 16.5 wt% Cr. A more corrosion resistant version of Hercules? (Hercules? B) with 0.5 wt% Mo has also been developed. Potentiodynamic tests performed on Hercules? B in a 5wt% sulphuric acid solution showed it to have improved corrosion resistance comparable to that of AISI 304. The effect of a varying Mn content on the corrosion resistance of Hercules? B has also been investigated and the results discussed in this paper. From the corrosion test results, it is clear that decreasing the Mn content of Hercules? B increased the corrosion rate, while increasing it decreased the corrosion rate. Keywords: austenitic stainless steel, % ferrite, molybdenum, manganese, nitrogen, electrochemical corrosion tests, potentio-dynamic scans, microstructure, chemical analysis.

Jan 1, 2007

By L. C. Stilwell

Input-output analysis is a major branch of quantitative economics, and is used to analyse the flow of goods and services between production sectors in a national economy. Its purpose is to determine the relative value-adding capacity of each sector. The model has also, in recent years, found increasing use in assessing the environmental and ecological impact of development projects. It has, however, never been applied to individual production facilities, such as large mines, which themselves have complex economic structures, through which there is a flow of goods and services. Conventional cost and accounting systems, as used on mines, treat production sectors as separate cost centres, and do not determine the inter-relationships between them. This can lead to incorrect conclusions on the relative value of sectors and their impact on the total economic performance of the facility. This paper explains the basic principles of input-output analysis, and presents an example of its application to a simplistic model of a mine, which is used in the absence of any real data. The paper concludes that, by forcing definition of the value adding function of each sector, input output analysis will facilitate control of inputs, or costs. This will result in optimal application of resources and exploitation of ore reserves. The authors realise the model needs to be tested on an operating mine, and hope this paper will result in an opportunity to do so. The authors wish to thank the anonymous referees for their valuable comments.

Jan 1, 2000

By N. Lock

"Despite the pre-eminence of the Jwaneng Diamond Mine as the world’s richest diamond mine, the discovery story has long been clouded in mystery. This is the 45-year old untold story of the Jwaneng discovery and contemporaneous Bechuanaland/Botswana political and socioeconomic history. Diamond exploration by De Beers in Bechuanaland began in 1955, with the first true kimberlite discovery near Letlhakane in 1967, before Clifford’s Rule was applied and before the use of indicator mineral chemistry. Surface deflation soil sampling and bioturbation by termites was the foundation for exploration into the Kalahari. The 1962 reconnaissance programme south of Jwaneng had failed to make any discoveries. Improved sampling methods were applied to the Kalaharicovered areas in 1969 and positive results were received by year-end. The Whateley’s Wish percussion drill-hole in December 1972 was confirmed as Jwaneng 2424D/K2 with drill core in early 1973. Jumper drills were required to penetrate the Kalahari sand cover. Diamond resources were demonstrated despite multiple technical problems. IntroductionThe Jwaneng Diamond Mine is, by value, the world’s richest diamond mine. Harry Oppenheimer is quoted as saying that Jwaneng is ‘the most important primary deposit found anywhere in the world since the discovery at Kimberley more than a century ago.’ (Taylor III, 1982) The mine opened in 1982 after some nine years of evaluation and construction since discovery in February 1973. Debswana (2017) states that 2015 production was 7.87 Mt of ore from which 10.408 million carats were recovered at a grade of 132 carats per 100 t (cpht). Although the value is not reported, it was noted that Jwaneng contributes 60–70% of Debswana’s total revenue from all mines, including Orapa, Damtshaa, and Letlhakane (Debswana, 2017)."

Feb 1, 2019

By I. V. Filippova, Y. Foucaud, M. Badawi, O. Barrès, L. O. Filippov, S. Lebègue

Sodium silicate (Na2SiO3) is one of the most common reagents used in the froth flotation process, in which it is an efficient dispersant as well as a powerful gangue minerals depressant. Due to its high affinity with a lot of minerals, mostly silicates, it adsorbs on their surfaces and prevents the adsorption of the collectors, maintaining them hydrophilic. Hence, Na2SiO3 is widely used in the flotation separation of rare earth minerals, zinc minerals, iron minerals, scheelite, fluorite, apatite, and many other minerals. For decades, authors have demonstrated higher efficiency of Na2SiO3 when it is used in combination with sodium carbonate (Na2CO3), a common pH regulator. Among many well-known depressants, this system presented the best efficiency for many ores, including the Tabuaço scheelitebearing skarn studied herein. However, the mechanisms resulting in these strong positive synergistic effects are not well understood at the moment. Hence, the response surface methodology (RSM) was applied to this ore, considered as a case study, to optimize the depressing conditions and to study deeply the flotation behavior of this system. Strong synergistic effects between the two reagents were exhibited by the RSM, mostly affecting the scheelite, fluorite, and calcium-bearing silicates recoveries. This was attributed to surface carbonation of the minerals by Na2CO3, subsequently leading to a better depression by Na2SiO3. Overall, a 1:1 ratio between the two reagents displayed the best results in terms of WO3 grade and recovery. To gain understanding in the molecular mechanisms responsible for the aforementioned synergistic effects, FTIR studies were combined with state-of-the-art molecular modelling (Ab Initio Molecular Dynamics at 300 K) on fluorite, an archetype of calcium minerals. Keywords: Synergistic effects, scheelite, depressants, FTIR, DFT calculations

Jan 1, 2020

By G. Akdogan, J. H. Zietsman, C. Dorfling, D. Attah-Kyei

The development of newer and improved electrical products has led to an increase in the rate at which older products are discarded as waste. The main focus of electronic waste is the printed circuit board (PCB) because of the inherently high value of contained metals such as gold and copper. Several options for treatment of the non-metallic fraction including material recycling, where the residue may be used as inclusions in concrete or asphalt materials with minimal processing or chemical recycling, where chemicals and fuels are produced from the residue using pyrolysis exist. In this paper, the utilisation of the non-metallic leached PCB waste fraction as reductant in secondary copper smelting was investigated. Analysis of the leached residue revealed that PCB is highly amorphous and has a carbon content of 28.5%, an oxygen content of 23.1%, with the ash and volatile matter contents 40.1% and 44.8% respectively. Thermodynamic simulations of secondary smelting of copper were conducted in terms of metal recovery, and the energy required when PCB was used as a reductant. The results were also compared with that of coal and PCB-coal blends. The simulations revealed that as PCB in the blend used as reductants increases, the amount of energy required for the smelting operation decreases. Metal recovery slightly decreased as the mass percent of PCB in the blend increased due to lower carbon content present in PCB relative to coal. The results also highlighted the energy saving with PCB-coal blends which was around 160 kWh per ton of feed relative to coal. The decrease in the amount of energy required for the operation is attributed to the higher volatile content of the PCB, which is also a part of the reduction process. Keywords: PCB leach residue, alternative reducing agent, secondary copper smelting

Jan 1, 2020

By D. Bessinger, J. Rabe, J. Zietsman, C. Coetzee, P. H. Lamont, J. Muller

The UCAR® CHILL-KOTE? freeze lining concept combines wall cooling with carbon and graphite refractories of higher thermal conductivities to ?chill? the refractory lining by transferring heat from the refractory lining. Effective sidewall water cooling, together with the efficiency of the heat dissipating conductive refractories, lowers the temperature of the lining to below that of the molten process materials. This causes a layer of slag and process metal to solidify or ?freeze? and form a protective ?skull? which completely coats the refractory hot face. Once formed, the slag skull insulates the refractories, reducing heat loss and protect the lining from erosion, chemical attack, thermal shock, and other stresses. The result: extended life and greatly improved refractory performance. The Ilmenite smelting process depends on the presence of a solidified slag skull to protect sidewall refractory material from chemical attach by molten slag. No known refractory material is able to withstand this corrosive material. To date, UCAR has not applied their Chill Kote ? technology in the ilmenite smelting industry. This paper revolves around the results obtained from conducting an ilmenite smelting campaign on a 500kW DC open-arc furnace with a UCAR designed refractory system. The purpose of this test was to establish the effects such a lining has on refractory wear and the reduction-smelting process. Proper thermo-couple management enabled the authors to monitor lining wear for the duration of the campaign. Prior to the pilot-scale campaign, modeling work was completed to evaluate the feasibility of applying UCAR® CHILL-KOTE? technology to ilmenite smelting furnaces. The successful operation of a pilot-scale furnace equipped with the UCAR® CHILL-KOTE? lining as well as concise modeling suggest that it should be a viable option to consider for an industrial-scale furnace.

Jan 1, 2007

By C. Musingwini

An often overlooked factor in the analysis of mine layouts and schedules is technical operating flexibility (or tactical flexibility), mainly due to its nebulous nature. By glossing over technical operating flexibility the resultant mine layouts and schedules maybe suboptimal. The need to incorporate technical operating flexibility into the analysis and comparison of mine layouts and schedules is increasing in importance. The nature of technical operating flexibility is illustrated, previous work on valuing of operating flexibility reviewed, and a proposal made on how technical operating flexibility can be quantified for tabular reef mines by using a platinum reef deposit as a case study. Once technical operating flexibility has been quantified it becomes possible to explore its incorporation into the analysis of mine layouts and schedules and subsequent optimization processes. This paper is a revised version of a paper presented in the Proceedings of the Second International Platinum Conference, ?Platinum Surges Ahead? in 2006. The work described in this paper is part of a current PhD study at the University of the Witwatersrand. Keywords: mine plans, layouts, schedules, technical operating flexibility/tactical flexibility, ore availability.

Jan 1, 2007

By R. M. Whyte

The complexities that exist in the nature of the basic feedstock to the metallurgical process call for a high degree of ingenuity from the extractive metallurgist in seeking the best possible treatment method for a particular ore. Drawing from personal experience the author presents four case studies that demonstrate the value of creative thinking in addressing the challenges typically encountered by the extraction metallurgist. It is concluded that creative expression most often occurs in response to a perceived strong need within an organization. By deliberately laying down meaningful challenges management can stimulate innovative thinking and achieve extraordinary results.

Jan 1, 2009

By E. L. Thyse, P. Bepswa

The Western Cape Mineral Processing Facility (WCMPF) is a collaborative educational initiative between the Department of Process Engineering at the University of Stellenbosch and the Chemical Engineering Departments at the University of Cape Town and the Cape Peninsula University of Technology. The primary objective of the WCMPF is to facilitate the education, development and graduation of suitably qualified engineering graduates and diplomats for the mining and mineral processing industries. In recent years the WCMPF has embarked on a number of initiatives aimed at improving the quality of mineral processing education which include, more importantly the introduction of novel ?end to end? or ?integrated? practicals. The practicals are developed around a specific mineral theme or route, which more than often includes the development of several new pilot plant practicals demonstrating key unit operations or processes in the selected mineral theme or route. The most recent mineral processing pilot plant practical programme is developed around the beneficiation of heavy mineral sands. The programme consist of the following developed pilotplant practicals: the online electrostatic separation of free flowing mineral sands using a Roche Mining Carrara high tension roll separator incorporating a Blue Cube Systems MQi in-line mineral quantifier; the production of titania-rich slag and pig iron from the smelting of ilmenite and anthracite in a 60 kW direct current (DC) plasma arc furnace as well as the mineralogical characterization of the feed and products; the continuous closed-circuit ball milling and screen classification of titania-rich slag. This paper illustrates the important role of a well-designed heavy mineral sands beneficiation pilot plant practical programme in facilitating the education and development of suitably qualified personnel for the mining and mineral process industries.

Jan 1, 2007

By N. Mulaudzi

The use of SO2/air gas mixtures as an oxidant to precipitate Mn from Co(II) leach liquors was investigated. The effects of SO2/air ratio, pH and temperature on Mn precipitation were evaluated. It was found that the use of SO2/air gas mixtures resulted in significantly higher Mn precipitation kinetics compared to using air or pure O2 alone. The SO2/air ratio was varied from 0% to 6% SO2(v/v) in air and similar Mn removals were achieved at 0.75% to 3% SO2 at pH 3. The solution pH was varied from pH 2 to pH 4; Mn precipitation did not increase considerably from pH 2 to pH 3, but increased significantly at pH values higher than pH 3. Cobalt co-precipitation also increased as pH increased, with 1% Co co-precipitation at pH 3. An increase in temperature from 30°C to 60°C also increased Mn precipitation and 100% Mn precipitated at 50°C. Cobalt co-precipitation also increased significantly with an increase in temperature. An activation energy of 25 kJ/mol was calculated from the Arrhenius plot, which is an indication that the precipitation reactions were both chemically and diffusion controlled. XRD analysis showed that Mn precipitated in the form of Mn2O3 instead of MnO2 that was predicted from thermodynamic data. SEM and XRD analysis also revealed that the precipitate consisted mainly of gypsum or bassanite (99%), with the Mn containing phase (< 1%) distributed within the gypsum phase. The co-precipitated Co reported to the Mn phase. Keywords: manganese precipitation; SO2/O2 gas mixtures; cobalt solutions.

Jan 1, 2009

The January General Meeting was held at The Moth Hall, Witbank, on Thursday, 30th January, 1969. Mr C. G. Sowry (Chairman of the Witbank/Middelburg Branch) was in the chair. There were also present: Fourteen Members: Messrs A. Bain, A. W. L. Brereton, J. Meintjes, G. Langton, A. C. Hofmyer, J. H. Moore, T. S. Wilmot, B. F. van der Merwe, H. A. Williams, O. T. Wright, J. E. van Aswegen, P. J. Beukes, I. Botha. Six Associate Members: Messrs B. T. Hosking, R. E. Powell, J. B. Cornish, R. Ladner, W. Weber, P. J. Muller. Two Affiliates: Messrs P. B. Cass, W. K. C. Bremer. Nine Visitors. Apologies were received from Messrs G. R. Canny, E. J. Jackson. MINUTES OF THE PREVIOUS GENERAL MEETING It was proposed and accepted that these be taken as read. Proposer, J. Meintjies; seconded, A. W. L. Brereton. 75TH ANNIVERSARY CELEBRATIONS OF THE S.A.I.M.M. The Chairman reminded members of the functions arranged to mark this occasion. It was also mentioned that members desirous of forming parties to travel to Johannesburg should either make arrangements amongst themselves or inform the Secretary who would assist in arrangements. PAPER FOR PRESENTATION The Chairman then called upon Mr S. Selmer-Olsen to present his paper, &apos;Lectures on electro-smelting of ferro-alloys&apos;. After Mr S. Selmer-Olsen had presented his paper, he answered questions arising from contributions from the floor. The Chairman then thanked Mr S. Selmer-Olsen for presenting his paper. CONTRIBUTIONS TO PREVIOUS PAPERS Contributions to the paper &apos;Photo-electric readings. Their significance for dust control on collieries,&apos; presented by Messrs G. H. J. Kitson (Member) and Y. J. F. Haven (Visitor), were read by Messrs A. Bain and A. W. L. Brereton.