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By M. J. U. T. Van Wijngaarden, R. J. Dippenaar, J. M. A. Geldenhuis

The successful application of solid electrolytes in electrochemical cells for high-temperature thermodynamic studies depends to a large extent on an accurate knowledge of the P. value of the electrolyte (the oxygen partial pressure at which the ionic conductivity and n-type electronic conductivity of the electrolyte are equal). Consequently, the P. value of an electrolyte must be determined prior to its use in electrochemical cells. This paper describes the successful application of a coulometric titration technique in the quantitative assessment of the P. values of a commercially available ytria-stabilized zirconia electrolyte that has been used extensively by local investigators. The experimentally determined P. values of the electrolyte are reported and compared with P. values reported in the literature for a similar electrolyte.

Jan 1, 1988

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 22nd August, 1973. Dr J. P. Hugo (President) was in the Chair. There were also present 64 Fellows, 20 Members, 5 Associates, 3 Students, and 34 Visitors, making a total of 126. The President declared the meeting open at 4.05 p.m. OBITUARIES The President: It is my sad duty to announce the death of the following members of the Institute C. Boocock, R. J. G. Moore, M. P. Pearse, and A. I. Sussman, all Fellows, and W. T. Dalling, a Life Member. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I ask you to rise and observe a few moments' silence. MINUTES Die President: Item twee op die agenda is die bekragtiging van die notules van die jongste Algemene Vergadering van die Instituut. Daar die notules in die Augustus uitgawe van die Joernaal gepubliseer is, vra ek u toestemming dat dit as sulks bekragtig word. Toestemming verleen. WELCOME TO VISITORS The President: It is my very great pleasure to welcome all the distinguished guests who have honoured us with their presence this afternoon; in particular, a hearty word of welcome to the Honorary President of the Institute, Mr Plumbridge, the President of the Chamber of Mines. You are doubly welcome here, sir, and we thank you for your presence. Also to that old member and stalwart, the Honorary Vice-President of the Institute, Mr Tommy Gibbs, the Government Mining Engineer-you're very welcome, Mr Gibbs. Then, we are particularly privileged this afternoon to have an Honorary Member with us, the Minister of Mines for Rhodesia, Mr Dillon. You will recall that he honoured us with his company last year. Mr Dillon, we are very appreciative and hope that this is now a standing arrangement. We are also honoured by the presence of some thirteen Presidents, Vice-Presidents, or Chairmen of our sister scientific and technical organizations. I shall rapidly read their names, but they must all feel assured that they are very welcome here today. Firstly, one of our own Past Presidents and members, Mr Geoff Goode in his capacity as President of the Associated Scientific and Technical Societies of South Africa; Mr L. R. Robinson, President of the South African Institution of Mechanical Engineers, and Mrs Robinson; Mr G. Goedhals, President of the South African Institute of Electrical Engineers ; Dr Antrobus, President of the Geological Society of South Africa, and Mrs Antrobus; Mr T. V. Dean, Vice-President of the Institute of Land Surveyors of the Transvaal, and Mrs Dean; Mr R. M. Stroh, President of the Mine Ventilation Society of South Africa; Mr Ken Steele, President of the Association of Mine Managers, and Mrs Steele; Mr Mike Gericke, President of the South African Council for Professional Engineers; Mr R. G. Matthews, President of the Institute of Mine Surveyors of South Africa; Mr P. H. Pettifor, President of the Institute of Production Engineers, London, and Mrs Pettifor ; Dr Nico Stutterheim, Chairman of the South African Institute of Chemical Engineers, and Mrs Stutterheim; Professor F. A. van Duuren, Chairman of the Engineers' Liaison Committee in Pretoria; also, I haven't spotted him but I trust he is here-Mr Alex Bain, who is Chairman of this Institute's Witbank/Middelburg Branch. To one and all, ladies and gentlemen, a hearty word of welcome. Not last on our list, a word of welcome to Mr Eric Boden, the Manager of A.S. and T.S. We also have with us I trust, Dr Deist, and his good lady-Dr Deist will be figuring in our proceedings later this afternoon. Also Mr Barcza and Mrs Barcza. Mr Bareza, a former President of the Institute, also has a task to perform. Then, I hope two of our student prize winners are here-Mr Beetge and Mr Painting. Then we also have Mr Roberts, who is welcome in his capacity as co-author with Dr Deist. Then, last of all, a hearty word of welcome to Dr Helen Glen (I am not sure whether she has arrived yet, but she is certainly due to come)-the new Honorary Editor of the Institute's Journal. MEMBERSHIP The President: I have pleasure in announcing that, their names having been published in accordance with By-law 5.2.2, the following have been elected by Council to membership in the following grades Fellows: W. G. Jayes and F. K. Wright Members: D. W. Penman, A. W. Bryson, and D. L. Gibbs Graduates: R. J. Adey, J. P. Bond, R. C. Dunne, G. M. Entwhistle, J. M. Rendu, J. P. S. Turner, and A. P. van Jaarsveld Associates: A. Ellis, B. R. Hambly, A. J. Johansen, and G. W. Tregoning

Jan 10, 1973

By D. vas As, Constance M. Vleggaar, P. D. Toens

A facility at the National Nuclear Research Centre, Pelindaba, for the calibration of gamma survey meters used in uranium-prospecting operations by P. D. TOENS, D.Sc. (Fellow), D. van ASt, M.Sc. (Visitor), and CONSTANCE M. VLEGGAAR, B.Se. (Visitor) Ground radiometric surveys in uranium prospecting have in the past suffered from two serious shortcomings. Owing to varying instrument sensitivity and the often arbitrary height at which readings are taken, it has been impossible to compare results obtained in different surveys and, moreover, to relate such readings to actual U30s concentrations. A set of calibration sources designed to overcome these problems has recently been constructed on the site of the National Nuclear Research Centre, Pelindaba. A discussion of the standards applied and the instrument calibration procedure is presented.

Newmont is one of the few remaining large mining companies that was established in the early nineteen hundreds. The company has a long, colourful and enviable history. This paper provides highlights of Newmont?s business and technical history since its inception in 1916, its transition to a ?gold only? company in the early 1990s and progress since that time up until the present day. Details of Newmonts current gold operations and its gold production profile for 2008 are also provided in the paper Over the last 50 years Newmont has developed a host of innovative gold technologies to meet the challenges of treating the complex refractory gold ores, found at the company owned mines in the Carlin region and around the world. Details of the technologies are provided and they include chlorination, roasting, bacterial and pressure leaching, leaching gold with thiosulphate and thiocyanate, N2Tech flotation, HPGR treatment of hard and abrasive ores and, finally, the use of Hydro-Jex technology for improving gold recovery from heaps.

Jan 1, 2009

By R. A. H. Lycett, P. R. Jochens, D. D. Howat

The crystallization of rutile from titaniferous slags by R. A. H. LYCETT, M.Se. (Eng.),"A.M.I.M.M. (Visitor), P. R. JOCHENS, Pr. Eng., M.Se. (Eng.) (Rand), Ph.D. (Member), and D. D. HOWAT, B.Se., Ph.D., F.R.I.C., F.I.M. (Fellow) Factors affecting the precipitation of rutile from smelter slags were investigated, with particular reference to the effect of additions of phosphorus pentoxide to the slag. The phases were identified and the phase boundaries determined for slags having phosphorus pentoxide additions of 0 to 50 per cent. The liquidus temperatures of these slags were determined, and a pseudo-binary phase diagram was constructed. Rutile crystallized as the primary phase from melts having a phosphorus pentoxide content of more than IS,S per cent. Prismatic rutile crystals whose TiO. content was more than 97 per cent were grown from melts that had a phosphorus pentoxide addition of 30 per cent. However, the morphology of the precipitated rutile was such as to make subsequent separation impracticable.

Jan 9, 1975

By M. R. MacIver, M. Pawlik, H. Alizadeh

Treatment of tailings is an integral component of mineral processing. Tailings with a high clay content are a challenge for the mineral processing industry; e.g. the clay slimes produced from production of phosphate in the mid-western United States and the fine tailings produced from oil sands production in western Canada. Dispersants are a commonly used process aid, but their impact on the structure and settling properties of high clay content tailings is not well understood. The paper describes the changes in composition and bitumen release that occur when mature fine tailings (MFT) are treated with a polymeric dispersant (lignosulfonate.) Synchrotron-source computed tomography (CT) was used to obtain high-resolution 3D images of samples prepared at varying dosages of dispersant. The CT method permits a powerful visualisation of the internal structure and composition of the samples. These insights will enhance our understanding of the structural characteristics of mineral tailings relevant to solid-liquid separation by flocculation and thickening. Keywords: Dewatering, dispersion, dispersants, chemical treatment, computed tomography

Jan 1, 2020

I am a partner in a minerals' development company called A.B.F. Limited, that does minerals development in Africa and Asia. I have read your very fine magazine often at the Colorado School of Mines Library in Golden, Colorado. I would like to ask your assistance in trying to locate a South African smelter; preferably on the coast, but not totally necessary for the project, that can separate the first four metals (Au, Ag, Cu, and Pb).

Jan 1, 1980

By G. R. Lane

A large opencast gold mining company in Africa had just completed a feasibility study for the expansion of the operations. A traditional net present value project valuation methodology had been used that showed a very positive net present value (NPV). The project team had conducted a qualitative risk assessment that identified and logged all potential project risks and had subjectively incorporated ?risk? via the discount rate and other assumption contingencies around gold price expectations, operating parameters etc. Management requested that an independent quantitative risk modelling approach be adopted to obtain a better understanding of the impact of risk on the overall project valuation and confidence level in the final valuation. A detailed project valuation model was configured in the Carbon Modelling Technology and the stochastic modelling module used to perform the Monte Carlo simulations. Analysis of historical operational performance data relating to actual achievements versus planned and budget determined the historical variability of the underlying parameters as well as variance to budget. This was done at a detailed level for mining rates and costs, processing rate, costs and recovery, and other operational efficiency measures. External market assumptions relating to gold price, exchange rate, and inflation were modelled and the dependency between them modelled using a copula. This case study will demonstrate the approach taken to building and populating the quantitative risk model and the overall results of the Monte Carlo simulation. The final valuation demonstrated that the project had a 44 percent probability of an NPV less than zero i.e. 44 percent chance of project finance loss.

Jan 1, 2012

By G. W. Holl, E. G. Fairon

A review of some aspects of shaft design by G. W. HOLL, Pr. Eng., Associate of the Mine Managers Association of South Africa (Fellow)- and E. G. FAIRON, Pr. Eng., F.S.A.I.E.E., M.I. Cert. M.E.E., M.I.Mech. E., (Visitor) The reasons for the choice of vertical shafts in preference to inclined shafts of comparable capacity are set out, and the conclusion that the former are superior in virtually all circumstances is substantiated. The shapes of vertical shafts sunk during the past sixty years are recorded, and the shapes of those sunk during the past decade are analysed. From this analysis it is clear that circular and elliptical (and quasi-elliptical) shafts are the shafts of the future and that the rectangular shape will conceivably become obsolete. The determination of the size of shaft is discussed and it is forecast that shafts of a diameter of 13 metres and over will probably be sunk without difficulty in the years to come. The depth of the shaft is determined intrinsically by the Mines and Works Regulations applicable to factors pf safety of winding ropes and the design of the winding system. The Blair winder is the most suitable winder for hoisting rock, men, and material from a depth of, say, 3000 metres on an economic basis. Tertiary shafts will, therefore, be unnecessary in future deep-level mining projects at the limit of depth now envisaged. A few other factors relating to shaft design are described.

By J. Jacobs

The three-product cyclone was originally developed in Russia and is now extensively used in China. The cyclone has recently entered the South African coal industry, and with the obvious advantages that this item of process equipment offers our ever-evolving industry it is safe to assume that it will add value to dense medium circuits in South Africa. Some of the possible applications include: ? Producing multiple products using a single dense medium circuit. These can typically be a primary product with calorific value of 27.50 MJ/kg and a secondary (middling) product with a calorific value of 22 MJ/kg ? High-density separation with a low circulating medium density. Anglo Thermal Coal and Exxaro have pioneered the use of these units at Umlalazi and New Clydesdale respectively. Extensive test work has been performed at Umlalazi to determine the efficiency of the unit and to determine how it compares with the conventional DSM (Dutch School of Mines) cyclone. Some people in the coal industry were initially sceptical and expected the performance of the three-product cyclone to be inferior to that of the conventional dense medium cyclone. The results of the test work have, however, shown that the efficiency of the unit is comparable to that of the cyclones currently employed. A valid concern expressed is the control over the cut-point density of the second stage separation, and work is on-going to find the optimal way to control the secondary separation density. Theoretically, the secondary separation density can be manipulated by changing the orifices of the unit, especially the spigot of the secondary stage. This remains to be proven, and a series of tests is currently being planned. Whatever the result of these tests may be, the three-product cyclone definitely has a place in the South African coal processing industry as it offers a low OPEX and CAPEX solution for producing multiple products from a single circuit, as well as the ability to operate at very high separation densities, while making use of low-density circulating medium. Keywords dense medium separation, DSM, three-product cyclone, coal processing.

Nov 1, 2013

By J. T. M. Amphlett, C. A. Sharrad, M. D. Ogden, R. I. Foster

"A renewed interest in nuclear power around the world in order to reduce greenhouse gas emissions is going to increase demand for uranium as fuel. This will result in more uranium being mined, which will in turn increase associated environmental pressures, such as fresh water use. A move to lower quality waters containing impurities such as chloride would help alleviate these pressures. In this work, we determined the uptake characteristics of weakly basic anion exchange resin Ps-EDA towards uranium from saline solutions in a dynamic flow column. Breakthrough curves were produced, with suppression of uptake being observed for chloride concentrations above 5 g L-1. Calculated resin saturation capacities at zero and 5 g L-1 chloride are comparable with literature values for strong-base anion exchange resins, and exceed those published for weak-base resins up to 20 g L-1 chloride. Data has been fitted to multiple breakthrough models, with the modified dose-response model most effectively predicting uranium recovery. The results show that the ethylenediamine functionality could be suitable for use in future uranium processing flow sheets where a high-saline lixiviant is used. IntroductionIon exchange (IX) is a key technology in the uranium mining industry and is well established for the extraction of uranium from both acidic and alkaline leach liquors (Edwards and Oliver, 2000). It was first employed in 1952 at the West Rand mine in South Africa (Ford, 1993; Taylor, 2016). H2SO4 and Na2CO3 are the most commonly employed lixiviants used to solubilize uranium in acidic and alkaline leach conditions respectively. The chemistry of these systems causes uranium to form anionic sulphate or carbonate complexes, which can be taken advantage of by anion exchange resins.Another major technology for the extraction and purification of uranium from leach liquors is solvent extraction (SX). This technique involves the extraction of uranium from the aqueous phase into an immiscible organic layer. Although this is a commonly used method, there are major drawbacks to it, including the use of large volumes of flammable solvents, solvent loss, phase disengagement, third phase formation, and the production of problematic degradation products (Veliscek-Carolan, 2016). These problems can be circumvented through the use of IX resins."

Dec 1, 2018

By NONEn NA

1. Book reviews . Rudiments of mining practice, oy C.E. Gregory.Clausthal-Zellerfeld (West Germany), Trans Tech Publications.OS$24.Reviewer: A.N. BrownProfessor Gregory has had a wide experience of hardrockmetalliferous mining throughout the world, beinga well-known academic who has taught at many universitiesin the Western World. His basic training was obtainedin his native land of Australia. In this publication he identified the need for a basic, simple book on miningpractice to provide new students of mining with a backgroundto their studies. He also designed the book to providea background to persons operating on the fringesof the industry such as students of economics and journalists.The text extends to only some 120 pages, and containsa sufficient number of monochrome sketches, diagrams,and photographs. It is written in a straight-forward, easyto-read style. The book contains an index and elementarytable of conversion from imperial to SI (metric) units,and there is also a glossary of mining terms that mostreaders would find useful.The author has succeeded in keeping the contentssimple, as indicated by the title. However, after each chapter, there are references to further recommendedreading. The book could be useful in the South African context, although the coverage of coal and opencast mining operations is slender.

Jan 1, 1987

The 90th Annual General Meeting of The South African Institute of Mining and Metallurgy was held at Kelvin House, Johannesburg, on 19th August, 1987. Dr H. Wagner (President) was in the Chair and declared the meeting open at 16h00. Obituaries The President read out the names of the departed Members as follows: N.M. Airey, F.J. Kisbey-Green, Dr R.A. Pelletier, C.B. Anderson, A.R. Cator, J. van Heerden, P.J. Burman, C.C. Crosson, M. Livingstone¬Blevins, S.T. Firman, V.E. Kisbey-Green, and A.L. Corna. All stood and observed a moment of silence as a mark of respect. Minutes The minutes of the 89th Meeting of the SAIMM, which was held on 20th of August, 1986, were confirmed.

Jan 1, 1987

By S. Moodley

In the chloride process for Ti02 pigment production, various titania feedstocks (i.e. rutile, synthetic rutile, slag, and upgraded titania slag (UGS)) are chlorinated in a fluidized bed reactor with petroleum coke at temperatures between 1000°C and 1100°C to yield gaseous metal chlorides. Although feedstock preference is largely based on Ti02 content, feedstock physical properties (i.e. density, sphericity, size distribution, and porosity) differ; these differences will affect fluidization behaviour and can inadvertently affect conversion efficiency. For example, a high carryover from the reactor reduces particle residence time and decreases conversion rates. Owing to dwindling rutile reserves in the world, most chloride producers are forced to feed blends of feedstocks to their chlori¬nators; and so it becomes important to understand whether blends have an effect on the hydrodynamic properties of the bed. This paper describes the physical characterization of different feeds and the determination of the elutriation constants for slag, rutile, synthetic rutile, and a blend (i.e. 50 wt% rutile, 50 wt% slag). A common feature of the tests was that particles finer than 75 Km tended more than any other size to be elutriated. The tested rutile, classified as a Geldart Group B material, had the lowest carryover, whereas the slags had the highest. Interestingly, the elutriation constant (ki) of the blend is lower than those of either of its individual components.

Jan 1, 2012

By S. Moodley

In the chloride process for TiO2 pigment production, various titania feedstocks (i.e. rutile, synthetic rutile, slag, and upgraded titania slag (UGS)) are chlorinated in a fluidized bed reactor with petroleum coke at temperatures between 1000°C and 1100ºC to yield gaseous metal chlorides. Although feedstock preference is largely based on TiO2 content, feedstock physical properties (i.e. density, sphericity, size distribution, and porosity) differ; these differences will affect fluidization behaviour and can inadvertently affect conversion efficiency. For example, a high carryover from the reactor reduces particle residence time and decreases conversion rates. Owing to dwindling rutile reserves in the world, most chloride producers are forced to feed blends of feedstocks to their chlorinators; and so it becomes important to understand whether blends have an effect on the hydrodynamic properties of the bed. This paper describes the physical characterization of different feeds and the determination of the elutriation constants for slag, rutile, synthetic rutile, and a blend (i.e. 50 wt% rutile, 50 wt% slag).A common feature of the tests was that particles finer than 75 µm tended more than any other size to be elutriated. The tested rutile, classified as a Geldart Group B material, had the lowest carryover, whereas the slags had the highest. Interestingly, the elutriation constant ([ki]) of the blend is lower than those of either of its individual components.

Jan 1, 2012

By R. J. Cocks

Water auditing and water efficient practices are evolving as the quantitative tools for water balance reporting in the mining and minerals processing sector. This paper was written to describe the process of water auditing in a gold mining environment. It will contribute towards building an appropriate water management framework for The Cooperative Research Centre (CRC) for sustainable resource processing (CSRP). The research assists with the assessment of water balances in mining and hydrometallurgical processes and provides, on the ground, steady-state data for ongoing probabilistic modeling underway at most of Newmont?s gold mine operations. Five Newmont case study mine sites including the Tanami Granites Goldmine are central to this PhD water project study. The function of the Tanami-Granites water audit exercise was to measure a controlled flow of various water quality types and set a framework to establish further research for water efficiencies and water conservation in mining.

Jan 1, 2009

By H. S. Sichel

Statistical valuation of diamondiferous deposits By H. S. SICHEL, D.Sc The valuation of diamondiferous deposits depends on (i) the density distribution, (ii) the size distribution of stones and (iii) the selling price structure prevailing at a particular time. In the density distribution the stochastic variable is defined as the number of individual stones found per sample unit irrespective of the stone size. The density distribution is discrete and allows for barren sample units. As diamonds often occur in clusters, a Poisson mixture distribution is derived which is entirely new, as existing discrete distributions cannot represent the stone number frequencies found in nature. For the sizes of diamonds, which are measured by weight, a new compound logarithmic normal distribution is developed. Combination of (i), (il) and (iii) leads to a meaningful appraisal of diamondiferous ground expressed in monetary value per production unit of mining. Finally, confidence limits are calculated which allow for inferences from sampling to recovery.

By R. Gebrekristos

It is commonly accepted that three types of aquifers exist in the Bushveld Complex: (a) alluvial aquifers in areas of river courses, (b) weathered bedrock aquifer formed by the in-situ weathering of the bedrocks, (c) fractured aquifers underlying the weathered aquifers controlled by the regional and local fracturing of the crystalline rocks. Hydrogeological studies conducted in the Critical Zone of the Bushveld Complex in the western limb show that the UG2 pyroxenite layer is of a particular interest and has a unique aquifer property. It yields much of the groundwater inflow into some mines and can be classified as the most important aquifer in the vicinity of the mining zone. The UG2 pyroxenite aquifer is restricted to the dipping UG2 pyroxenite unit. The unit weathers more intensely than the surrounding norites and anorthosites and is characterized by deeper weathering horizons (two to three times deeper than the surrounding rocks). For much of the UG2 mining area between depths of 35 ? 80 m, stoping of the UG2 takes place approximately 5 ? 7 m below the UG2 pyroxenite aquifer, and usually there is no groundwater inflow into the mine workings. However, unsealed deep exploration boreholes intersecting the UG2 pyroxenite and reaching underground mine workings, or mine roofbolts penetrating the weathered pyroxenite aquifer from underneath, can result in significant groundwater inflows into the underground workings. The reason as to why the UG2 pyroxenite weathers more than the norites and anorthosites has not been fully studied but is suspected to be due to the bedding planes of the unit and mineralogical composition of the particular pyroxenes forming the unit, which result in preferential physical and chemical weathering under atmospheric conditions. The weathered pyroxenes form sand-sized, rounded grains with improved effective porosity and permeability suitable for the storage and passage of groundwater. The orientation of the pyroxenite aquifer can easily be determined as it dips with the Bushveld layered strata. No-flow boundaries can be assumed on the hanging- and footwall of the pyroxenite aquifer and the flow rates can be estimated using 2-dimentional analytical equations. However, this must be confirmed with strong conceptual models since the existence of a fracture network connecting the pyroxenite aquifer with the overlying weathered and/or underling fractured aquifers can complicate the system, lowering the accuracy of analytical models and necessitating the utilization of numerical models.

Jan 1, 2012

The February General Meeting of the Institute was held in Kelvin House, Johannesburg, on 19th February, 1969 at 4.30 p.m. Mr R. C. J. Goode (President) was in the Chair. There were also present forty-six Members, including Messrs H. E. Cross, A. R. C. Fowler, P. Lambooy, D. G. Maxwell, Dr J. T. McIntyre, Messrs J. A. Nixon, V. C. Robinson and P. W. J. van Rensburg (Council Members), Messrs G. Abdinor, H. F. Allan, R. E. Barnes, M. M. Bayley, J. K. Boyd, R. R. M. Cousens, R. E. F. Cowley, D. Savile Davis, H. J. Davisson, C. T. Fenton, J. Fergusson, J. Fritz, M. L. Fitzgerald, J. M. Gosnell, J. C. Hall, S. A. Hancox, D. M. Jamieson, Dr D. G. Krige, Messrs J. E. V. Leeuwen, A. Louw, C. F. Louw, B. H. L. Leach, R. B. MacGillivray, C. S. McPhail, E. Margo, G. G. Nicolson, E. Pavitt, M. P. Pearse, F. O. Read, Dr M. D. G. Salamon, Dr H. S. Sichel, Messrs D. Storrar, S. G. Taussig, A. H. Taute, E. B. Viljoen and P. A. von Wielligh. Sixteen Associate Members, including Messrs S. T. Baron, W. M. Fitzpatrick, M. R. Fuller-Good, P. R. Garcia, H. G. Gericke, P. D. Hatfield, R. Hemp, G. S. Lee, Miss V. E. Marting, Messrs A. H. Munro, R. C. Power, O. F. Rheeder, G. C. Thompson and N. Zolezzi. Two Graduates, Messrs D. Bosley and J. C. Sutherland. Three Affiliates, Messrs R. K. Briggs, A. B. Cook and G. M. Thain. One Student, Mr P. W. Henrard. Twenty-three Visitors, including Messrs N. J. W. Bell, R. G. Bushell, A. Bryan, J. F. Cillie, C. M. de Beer, Dr F. H. Deist, Messrs D. S. Drake, P. G. du Plessis, R. W. Hodgson, D. M. Hawkins, S. C. H. Kearns, M. D. Labuschagne, L. Munro,R. Murchison and L. Robinson. Secretary, Mr D. C. Visser. Total present: Ninety-two. OBITUARIES The President: "It is my sad duty to announce the death of the following members of the Institute. Edward Frank Jud Bulman, Life Member, who joined the Institute in 1931 and passed away on 7th November, 1968. Elmar Fenton Chapin, Member, who joined the Institute in 1941 and passed away on 17th November, 1968. Solly Rabinowitz Rabson, Member, who joined the Institute in 1944 and passed away on 13th February, 1969. Mr. Rabson was the holder of two certificates of merit for papers presented to the Institute.

By T. Groenewald

Potential applications of thiourea In the processing of gold by T. GROENEWALD, Ph.D. (Rand), D.I.C. (Imperial College) (Visitor) The aqueous chemistry of gold(l) that has found practical application is mainly the chemistry of the anionic complexes involving ligands such as cyanide. sulphite, and the halides. The one potential exception is the cationic gold(I)-thiourea ion. While many laboratory studies have been made during the past decade. the application of thiourea in the processing of gold is only now reaching the development stage. While thiourea is relatively inexpensive. recent interest has probably been spurred mainly by the novel technology that could arise out of the cationic properties of the gold-thiourea ion. This review outlines the chemistry of gold and thiourea. and discusses the possible use of thiourea in the processing of gold with respect to dissolution. solvent extraction. ion exchange, electrowinning. electroplating. electroless deposition. electro-etching, and electropolishing.

Jan 6, 1977