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By Y. Belloa, C. Dorfling

The presence of impurities such as Se and Te in copper sulfate leach solutions can have a detrimental effect on electrowinning efficiency. These elements can be removed from the solution by precipitation; sulfurous acid is commonly used as a precipitation reagent, while studies have also reported improved precipitation with the addition of metallic copper. This paper aimed to determine the effect of conditions used during the solution purification step on the characteristics of the precipitates that formed. Precipitation tests were performed in a batch reactor with copper sulfate leach solutions obtained from the base metal refinery of a platinum group metal producer. The effects of agitation rate (250 and 500 rpm), SO2 flow rate (4.4 and 5.8 mL/min.L), temperature (65 and 95°C) and metallic copper powder addition (0, 1 and 2 g/L) on the characteristics of the precipitates formed during the tests were determined using scanning electron microscopy. The major phases detected in the precipitates formed when using SO2 as the only precipitation reagent were elemental Se and Cu2Se. The introduction of copper powder led to the production of different sulfide phases for the experiments conducted at 65°C irrespective of the values of the other reaction parameters. At 95°C, Cu crystals, Cu2O and tiny inclusions of Cu2(Se,Te) were the prominent phases noticed in the precipitates produced from all the tests conducted with copper powder as precipitation enhancing reagent. Keywords: copper, precipitation, selenium, tellurium

Jan 1, 2020

A. H. Mokken: I am pleased to have been given this opportunity to make a contribution to Dr Muller's paper tonight. The reason for this is that, at one stage in our careers, we were associates in the same undertaking. Dr Muller, then fresh from University, with a degree in pure science, had just stepped onto the first rung of the ladder, which, it was then thought, would lead him to a career in gold extractive metallurgy. However, endowed with an enquiring mind and conscious of a lack of fundamental training in general metallurgy and engineering, he felt a need for further academic study. To meet this need and, more importantly, to meet the necessary finances, he found his opportunity in steel. Armed with a bursary, he bade farewell to gold and proceeded overseas, to the University of Sheffield, to train as a steel metallurgist. The outcome of these academic efforts, which were followed by assignments in the steel industry and a further period at Sheffield, is the man we have listened to tonight-a highly qualified metallurgist who has displayed a sound knowledge of his subject. In choosing Sheffield, Dr Muller became associated with a steelmaking centre of world renown, a centre usually credited with the first systematic production of alloy steels, as far back as the 18th century. Since that time, great advances have been made in the production of alloy steels and this is especially so in the last decade or two, when major developments in civil, mechanical, electrical, aeronautical and nuclear engineering have been made possible by the development of steels with improved properties. In spite of spectacular advances in the technology of non-ferrous alloys, plastics and other materials of construction, steel has maintained its role as a pre-eminent material for engineering use. With the gradual accumulation of data on the properties of steels, and the use of thin film electron microscopy, to study the behaviour and characteristics of such phenomena as dislocations in metals and other microstructural features, the physical metallurgist appears to be approaching the stage of an exact understanding of such phenomena as strength, ductility and brittleness-a knowledge which could lead to close control of such properties and, therefore, to the attainment of the highest goals. An interesting example, illustrating the use of fundamental principles, based on physico-metallurgical research, is the development of the maraging steels developed by Bieber at the International Nickel Company. These steels have met the extreme technological requirements of the space age by providing the material for the cases of large rockets in which qualities, such as high tensile strength, toughness, workability and weldability are most important. Attractive as they might appear to be in considerations of savings of weight, cost of erection, transport of materials and foundations, the use of high strength steels has been accompanied by special problems such as brittle fracture, hydrogen embrittlement, notch-toughness and fatigue. It has been found that high strength steels, which performed acceptably in conventional tension tests, were found to undergo failure, in a brittle manner, in service. Hydrogen embrittlement has caused spectacular failures at a fraction of the normal ultimate tensile strength, and a lack of correlation between fatigue and tensile strengths has diminished the advantages to be obtained from the use of high strength steel in some applications. A new approach to the selection of materials for engineering design has resulted from a consideration of these phenomena in which strength, as such, is no longer as significant as it was previously. Parallel with the development of high strength steel has been the need for suitable techniques for joining component parts and here welding has played an

O.F.S. Branch Proceedings of the Annual General Meeting on Wednesday, 30th July, 1975 The Aromal General Meeting of the Branch was held at the St. Helena Club on Wednesday, 30th July, 1975 at 7.45 p.m. Mr D. A. Smith (Chairman) was in the Chair. There was also present: Professor R. P. Plewman, President of the S.A. Institute of Mining and Metallurgy. Conference on Vacuum Metallurgy The Fifth International Conference on Vacuum Metallurgy is to be held in Munich from 11th to 15th October, 1976. Excavation and tunnelling A conference on 'Rapid Excavation and Tunneling' is to be held in Las Vegas from 14th to 17th June, 1976. Book reviews Mine filling. Queensland (Australia), Mt. Isa Mines, Limited, ] 973. 293 pp. $A20,00 incl. postage. Young, R. S. Cheml:cal phase analysis. London, Charles Griffin, 1974. 126 pp. £4.50. NIM reports Report no. 1714 The efficiency of the fire-assay procedure with nickel sulphide as the collector in the determination of platinum,silver, gold, and iridium. Report no. 1721 A preliminary investigation into the mechanism of depression in the flotation of sulphide minerals at the Prieska Copper Mine. Report no. 1725 The determination of silica in fluorspar by 14 Me V neutron-activation analysis. Report no. 1736 The determination, by atomic- absorption spectrophotometry and liquid extraction, of antimony (parts per million) in ores and concentrates. Report no. 1741 South African costs of equipment for the metall'urgical industry(1975}. Report no. 1744 The refining of the platinum-group metals . Report no. 1746 The determination, by atomic-absorption spectrophotometry, of minor elements in zinc, lead, and copper sulphide concentrates. Report no. 1747 Magnetohydrostatic separation of gold from gravity concentrates. Report no. 1750 A review of the present and future development of sulphur production in South Africa. Report no. 1754 A new three-dimensional anodic electrode for reduced power consumption du,ring the electrowinning of metals. Report no. 139 A preliminary survey of goldrecovery problems arising in the production of pyrite. (9th Feb., 1967, re-issued Jun. 1975.) 16 pp. Report no. 140 A preliminary mineralogical investigation of pyrite from the K imberley and the Main Reefs, VogelstruisbuU Gold Mine. (13th Feb., 1967, re-issued Jut 1975.) 11 pp. Report no. 165 Gold recovery from pyrite flotation mill products by cyanidation. Progress made up to 1st May, 1967. (5th May, 1967, re-issued Jun. 1975.) 8 pp. Report no. 133 Gold recovery by cyanidation from mill products obtained after pyrite flotation. Progress made up to ht July, 1967. (18th Jul., 1967, reissued Jun. 1975.) 14 pp. Report no. 219 A review of some of the mineralogical factors influencing the flotation of pyrite. (29th Nov., 1967 reissued Jun. 1975.) 20 pp. Report no. 278 Gold recovery by cyanidation from mill products obtained after pyrite flotation. (24th Jan., 1968, re-issued Sep. 1975.) 51 pp. Report no. 306 The effect of preaeration on two samples of thickener under flow from the Venterspost Gold Mine. (30th Mar., 1968, re-issued Jul. 1975.) 14 pp. Report no. 317 Results of tests carried out at the Loraine Gold Mine during the period 5th to 7th February, 1968. (21st Mar., 1968, re-issued Jul. 1975.) 11 pp. Report no. 321 Aeration of ore from the Loraine Gold Mine before theaddition of cyanide.(17th Apr., 1968, reissued Jul. 1975.) 30 pp. Report no. 380 The effect of aeration, before cyanidation, of pulps of gold ores containing xanthate. (14th Aug., 1968, re-issued Jul. 1975.) 44 pp.

Jan 10, 1975

By H. Von Michaelis

The world is rapidly becoming more ?green? i.e. energy conscious. Since mining and mineral processing are massive energy users, the mining industry is seeking ways to reduce its energy footprint. In mining and mineral processing operations, energy is often the most expensive cost item. Comminution, i.e. grinding, is frequently the most energy-intensive step between mine and metal. High pressure grinding rolls (HPGR) are being installed in a rapidly growing number of ?hard rock? mineral processing operations. In the energy conscious cement industry, HPGR grinding has been standard practice for decades. HPGR is known to be energy-efficient; the question is how energy efficient? How can the energy efficiency of HPGR be enhanced? This paper reviews recent HPGR applications for the processing particularly of copper, gold, platinum, PGM-Ni-Cu and iron ores. HPGR technology is discussed with respect to energy efficiency. The harder the ore the greater the energy savings are likely to be. Typical energy savings of 10?20% can be expected when installing HPGR vs. a SAG mill. Wipf(2005) showed why conventional Bond Work index tests on HPGR product is likely to under-estimate the energy savings that can be achieved by installing HPGR. Energy efficiency of HPGR is, however, ore-specific. The biggest energy savings of HPGR tested thus far is 9.5 kWh/tonne claimed for Vista Gold?s Mt. Todd gold ore from Western Australia, a savings of over one-third of conventional SABC comminution energy. Several commercial scale iron-ore pellet feed plants install HPGR for fine-grinding of concentrate to increase the surface area of pellet feed in a manner that reduces overall energy consumption. Energy-consumption in comminution is, however, only part of the energy savings benefit story. HPGR typically also reduces the amount of steel lost through wear of mill liners and media. Marsden(2008) showed that when the energy that would have been consumed to produce the steel that is saved by applying HPGR is factored in, then the overall energy savings of HPGR is considerably greater. Johnson et al.(1988, 2005) tested HPGR in a flowsheet in which energy savings of around 50% can be expected if HPGR product screen oversize is recirculated to the HPGR. Innovative flowsheets have been proposed by Rule et al.(2008) and by Morley (2008) which are expected to result in significantly increased energy savings. HPGR applied in flowsheets in conjunction with coarse ore separation devices, e.g. ore sorting or DMS to remove barren waste from HPGR feed promises significantly greater energy efficiencies. Fine-grinding and ultra-fine grinding of ore or concentrates in conventional ball mills results in energy consumptions that increase exponentially with product fineness. Wipf (2009) presented a flowsheet in which he proposed the installation of HPGR ahead of the Aerosion ?Disintegrator? for ultra-fine grinding of ores and/or concentrates. This dry grinding arrangement is expected to achieve ap80 = 7 µm using up to 100 kWh/t less energy than could be achieved by wet ball milling. Using conventional comminution, an ore might require grinding to p80 = 45µm (? 325 mesh), for example, to liberate the valuable components, e.g. magnetite, from gangue, e.g. silica. Inter-particle comminution in HPGR may break some ores along grain boundaries thereby liberating valuable minerals from gangue at a much coarser particle sizes. Early magnetic separation rejection of silica gangue liberated from magnetite by HPGR at coarser grain sizes could further reduce downstream comminution energy consumption.

Jan 1, 2009

Corosion technology: An information source book, by Judith Ann Douvile. Taylor & Francis, 1989. 188 pp. £32. Stainless steel buyers guide 1990. Southern Africa Stainless Steel Development Association (P.O. Box 4479, Rivonia, 2128), 1990. Free. Fatigue and stress of engineering materials and structures, edited by H.P. Lieurade. ITT International (40 Promenade Marx-Dormoy, 93460 Gournay-sur- Marne, France), 368 pp. US$ 109. Titanium and aluminium, edited by P.A. Coulon. ITT International (40 Promenade Marx-Dormoy, 93460 Gournay-sur-Marne, France), 200 pp. US$ 80. Engineering applications of stochastic processes. Theory, problems and solutions, by A. Zayezdny, D. Wulich, and D. Tabak. Chichester, John Wiley, 1989. 525 pp. £54.50. Metal behaviour and surface engineering, edited by S. Curioni, B. Waterhouse, and D. Kirk. ITT International (40 Promenade Marx-Dormoy, 93460 Gournaysur- Marne, France), 413 pp. US$ 109. Fuzzy control and fuzzy systems, by W. Pedrycz. Chichester, John Wiley, 1989. 272 pp. £37.50. CILO (carbon-in-leach with oxygen) cost study, by Minproc Engineers (USA). Free.

Jan 1, 1990

Scientific and technical research is becoming an expensive business, and needs to be managed as well as directed. Regardless of whether it operates under public or private auspices, a research-and development organization should not tolerate inefficiency or irrelevance. Its true worth is ultimately decided by the impact it makes on its environment. Doing the right things is preferable to merely doing things in the right way. Clear definition and the setting of goals form the crux of the Management by Objectives (MBO) system. This system provides the research establishment with a profound sense of purpose and direction, which is essential for effective planning and control. Performance standards, in association with costs and manpower, value assessment, feedback, and improvement, tend to follow naturally once the principle of a results-oriented management system is adopted. MBO is a participative management system, leading to decentralization and self-control of the individual rather than imposed control. If wisely implemented with the necessary respect for creative work, it can enhance the job satisfaction of the research worker as well as the overall productivity ofthe research establishment.

Jan 1, 1982

By M. Tang, X. Tong

"SynopsisSlime coating is one of the most common ways for serpentines to contaminate metallic mineral concentrates during traditional flotation of coarse sulphide particles. This could pose quite a complicated and challenging problem in the case of some types of low-grade and finely disseminated Cu-Ni ores bearing high serpentine contents. This is the case for the copper and nickel sulphides from the Yunnan Mine, China. Previous batch flotation tests of this ore resulted in satisfactory recoveries of 86.92% Cu, 54.92% Ni, and 74.73% Pt+Pd, and concentrate grades of 4.02% Cu, 3.24% Ni, and 76.61 g/t Pt+Pd. However, the MgO content in these concentrates was more than 19%. In the current study, microflotation tests and settling rate tests were introduced to investigate the effects of a combination of strong collectors (a 2:1 weight ratio of butyl xanthate and butyl ammonium dithophosphate) on entrainment of serpentines in metallic mineral concentrate, as well as visual observations of the concentrates in suspension using still photography. All test results indicated the presence of serpentines entrapped in the hydrophobic flocs that resulted from these collectors, even with the use of effective gangue depressants. These strong collectors are used to flocculate the ultra-fine sulphides by forming loose and ‘fluffy’ hydrophobic flocs. However, these hydrophobic flocs may also be able to load or entrap some serpentine slimes into the concentrate, and this entrained serpentine could be harder to remove by using depressants or intensified conditioning than serpentine slime coating on the particle surfaces.IntroductionSerpentine minerals, which have the generalized composition (Mg,Fe)3Si2O5(OH)4, can be easy to crush and grind due to their convoluted and bent layered structures. These serpentines can hinder the enrichment of some metallic minerals and dilute their concentrates by entrainment during flotation. The resulting high pulp viscosities, slime coatings, and high content of dissolved ions adversely affect the flotation recoveries of copper and nickel sulphides, and high levels of MgO entrained in the concentrates lead to heavy penalties from smelters. Since the quality of nickel flotation concentrate depends heavily on its MgO content (generally less than 6–7% for No.1 or 2 grade nickel concentrate according to the standard requirement from National Nonferrous Industry), reducing the entrainment of serpentine during flotation is becoming more and more pressing. Previous research has focused on the collectors and depressants that are commonly used in copper-nickel flotation, as well as their interaction mechanisms."

Jan 1, 2015

By J van Rooyen, S. Archer, M. Fox

The use of dilute sulphur dioxide (SO2) gas mixtures for the oxidation/precipitation of manganese has been explored widely in recent years. The technical merit of the concept is well proven and implementation of the technology on commercial scale is imminent. This paper reviews the technology of manganese removal by means of dilute SO2 gas mixtures and highlights some of the challenges associated with its implementation on industrial scale. A brief review of the technology is presented; the review considers both the mechanism and chemistry of manganese oxidation/precipitation with dilute SO2 gas mixtures. The impact of variables such as temperature, pH and SO2 concentrations on the manganese removal process is assessed. Challenges associated with implementation of the technology on industrial scale are discussed. Gas dispersion is highlighted as a critical design consideration.

Jan 1, 2007

By F. Botha

South Africa is amongst the 40 driest counties in the world, with extreme weather conditions and beset by both droughts and floods. Coupled with economic growth is an increased demand on water resources and, as with all other industrial developments, mining requires large volumes of water, which is likely to have an impact on the environment. Further to this, the mining industry also realizes that minerals are a non-renewable resource and the contribution to wealth creation from mineral extraction is not everlasting. It serves as an economic boost and careful planning is required to ensure that the legacy of mining is sustainable, and that some of the returns from mining provide continual economic and social prosperity.

Jan 1, 2012

By T. Puhakka

Simulation is a way to obtain quickly today future information on how planned systems will most likely behave in various selected situations. This information may then be used to optimize the system and its components and maximize the performance and output. Simulation is a way to fine-tune the layout, match the mobile fleet and optimize the schedule and the way of working to meet the desired production requirements. Simulation provides a glimpse of the upcoming operation, ‘future today’ and helps to predict its restrictions and sensitivity to various aspects. OptiMine™, the Sandvik Tamrock Corp. and CyberCube Oy developed simulation tool is designed to simulate underground rock flow and match suitable technology with various layout options. This tool can be used to view what-if situations and determine what kind of impact mastered changes have to production. The findings of critical points in the layout and working procedures at an early stage of a new mine can help to optimize the layout and material flow. OptiMine™is modular based simulation tool that combines the supplier machine knowledge and traffic guidance with mine operational know-how and mine environment. It is developed to work in a way that an effect of an individual incident, such as the effect of one additional turn in a continuous loading cycle to the daily capacity can be identified. The reported output can be used for economical impact evaluation of selected options. This paper discusses the use of simulation in general and the way the OptiMine™ simulation tool operates and how it may be used for operation, technology and material flow optimization.

Sep 1, 2001

By Dick Stacey

Many open pit mines are now being mined at very significant depths, often at depths far greater than was originally planned. Even deeper open pits are also being planned, to depths that would be considered deep by underground standards. The heights of the resulting rock slopes are usually beyond the current experience and knowledge base. The exceptions are, perhaps, some very high and steep natural rock slopes. These natural rock slopes are also assuming greater significance owing to pressures of infrastructure development and consequent exposure of such infrastructure to the hazards of slope failure and landslides. Developments in road and rail infrastructure are also resulting in higher rock cuttings. Present understanding of the mechanisms of slope behaviour and failure for high slopes, and for slopes subjected to high in situ stress conditions, appears to be lacking. If the mechanisms of slope behaviour are not well understood, the validity of commonly applied methods of analysis of the stability of such slopes may be questionable. The papers in this specialist International Symposium, including papers on mechanisms and monitoring techniques, and case studies will contribute to the understanding of these issues. The Symposium has attracted good international participation, from both the attendance and authorship points of view. We are very grateful to all presenters and delegates for taking timeout of their very busy schedules to come and share their knowledge and we hope that all will benefit from this event. Thanks are due to the Organising Committee and to the members of our International Advisory Panel for the ideas, the contacts and the badgering, and to the Secretariat of the South African Institute of Mining and Metallurgy for the organisation.

Jan 1, 2006

By L. M. Tavares, T. M. Campos, P. M. Faria, R. M. Carvalho

Recent advances in mechanistic ball mill modelling are expected to allow for more accurate predictions that overcome the well-known limitations of phenomenological approaches, including their inability to predict the effect of liner geometry and their wear, in grinding. Although able to describe continuous operation, the UFRJ model of ball mills has only been validated in the past in mills that operate in batch mode, either in laboratory or pilot scale. The present work demonstrates the application of the mechanistic UFRJ ball mill model to predict fine grinding of iron ore in a pelletising plant in Brazil, the first application of such a mechanistic modelling in continuous mode. It shows that the model provides accurate descriptions of flows after iterations in a closed-circuit with hydrocyclones. Keywords: Ball mill, iron ore, grinding, modelling, particle breakage

Jan 1, 2020

By D. D. Howat, J. van der Colf

Slags of the system CaO-MgO-AI2O3-TiO2-SiO2at had been reduced in graphite crucibles for selected time Intervals were fully re-oxidized so that an assessment could be made of the rate and extent to which the titanium oxide had been reduced. The derived kinetic parameters were studied as functions of slag composition and temperature. The extent of reduction after selected Intervals of treatment could be correlated with the physical behaviour of the melt (in terms of viscosity and electrical resistivity).

Jan 1, 1979

By C. R. Thomas

Although stainless steels have been used to a limited extent in the South African mining industry, the metallurgical development of 3CRI2 has presented materials engineers with a viable alternative for certain materials-handling applications. The various types of wear involved in these operations are described, and an explanation is given of how 3CRI2 is able to offer advantages, particularly in wet sliding applications. Certain applications result in various types of abrasive wear, and the performance of 3CRI2 in these areas is described.

Jan 1, 1981

By V. N. Medvedev, A. M. Bryukhanov

Stationary mine air control equipment enables monitoring of CH4 concentration only in sensor locations. CMC-4 individual indicator built into a caplight has been developed in Ukraine, extending CH4 monitoring to manned job sites. Major technical characteristics of the indicator are demonstrated. It features two operation thresholds: 1st threshold 1.0 to 2.0% vol. 2nd threshold 1.5 to 2.5% vol. Basic absolute accuracy ± 0.2% Caplight battery is a common power supply for the lamp and CH4 indicator, providing at least 10 hours of the system non-stop operation. Average pre-failure life is at least 10,000 hrs. It features: an explosion proof design and intrinsically safe test circuit; a small-sized sensor as an integral part of the caplight; a hybrid microcircuit to facilitate functioning of methane monitoring unit. The CMC-4 indicator weight is the weight of the caplight itself and equals 2.4 kg. A two-threshold design makes possible to distinguish between methane sources: slow accumulation due to diffusion or sudden rushes due to a gas-dynamic event. CMC-4 indicators in addition to stationary equipment minimize the risk of CH4 explosion underground determined as a product of accident intensity by calculated time interval.

Jan 1, 2003

Slope stability is a fundamental part of a successful mining operation. It impacts directly on the safety of personnel and the economics of the mine. The Jwaneng Mine in Botswana is planning a push back of 644m depth in the south east wall. Mining will commence in 2010 and be completed in 2024. This will put the mine in the deep pit category. The mine has invested in extensive geotechnical data gathering and design programs that started as far back as 2003 for the south east wall. The south east wail of Jwaneng Mine is characterized by foliation that dips adversely into the mining faces. The orienta1ion of the foliation is variable due to intense tectonic movements that have also caused the occurrence of faults that are sub-vertical. A considerable amount of information on the characteristics of structural patterns and the rock mass has been collected. This paper presents an overview of the feasibility level geotechnical design that is about to be concluded.

Jan 1, 2010

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 25th August, 1971, at 4.15 p.m. Mr V. C. Robinson (President) was in the Chair. There were also present fifty one Fellows, twenty one Members, two Associates, two Students and fourteen Visitors, making a total of ninety one. The President declared the meeting open at 4.15 p.m. OBITUARIES The President: 'It is my sad duty to announce the death of the following members of the institute: H. J. G. C. Arndt, Life Member, joined 1933, passed away 11th May, 1971. J. H. A. Diering, Fellow, joined 1921, passed away 24th June, 1971. L. O. W. Leimer, Fellow, joined 1960, passed away 25th June, 1971. E. A. Meltzer, Fellow, joined 1941, passed away April, 1971. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I would ask you to rise and observe a few moments silence.' MINUTES The President: 'May we confirm the minutes of the General Meeting held on 17th March, 1971, as published in the July, 1971 issue of the Journal?' Agreed. WELCOME TO VISITORS The President: In welcoming you here, ladies and gentlemen, it gives me great pleasure to see so many of our office bearers-our important honorary office bearers-and particularly I would like to welcome our Honorary President, who is, as you know, the President of the Chamber of Mines, Mr John Shilling, and we are 'privileged also to have with us two of our Honorary Vice-Presidents. One in particular I am very pleased to welcome here, and that is Mr G. F. van L. Froneman, who is the Administrator of the Orange Free State, and we extend a very hearty welcome to him, because he is a long way from home. Then we have another Honorary Vice-President, Mr Tommy Gibbs, the Government Mining Engineer, and there are many distinguished guests, whose names I want to give you, so that you will know who they are. We are happy to have present: Mr R. C. J. Goode, Member of Council, I.M.M. London; Mr E. Boden, Manager, A.S. & T.S. of S.A.; Mr G. A. P. Louw, The President, The Associated Scientific and Technical Societies of S.A.; Mr I. R. G. Stephen, The President, The South African Institution of Electrical Engineers; Mr A. S. Robinson, The President, The South African Institution of Civil Engineers; Mr C. F. J. Schneider, The President, The Institute of Land Surveyors of the Transvaal; Mr R. J. Vermaak, The President, The South African Institute of Assayers & Analysts; Prof J. P. F. Sellschop, The President, Joint Council of S.A. Scientific Societies; Mr T. C. Watermeyer, The President, The Federation of Societies of Professional Engineers; Mr G. A. MacWhirther, The President, S.E.I.F.S.A.; Mr C. G. Hinds, The President, The Mine Managers Association; Mr J. F. Aldersley, The President, The South African Institute of Foundrymen; Dr H. O. Reisener, The President, The Institute of Welding; Dr F. P. A. Robinson, The President, S.A. Corrosion Council; Mr A. Bain, The Chairman, Witbank-Middelburg Branch; Prof D. J. Schoeman, The Chairman, The S.A. Institution of Chemical Engineers; Dr N. P. Finkelstein, The Chairman, The South African Chemical Institute (S.Tvl Section); Mr J. M. Meyer, Chairman, O.F.S. Branch. To all these guests and their ladies, I extend a most cordial welcome, and hope that you are going to enjoy the afternoon. MEMBERSHIP The President: 'I have pleasure in announcing that the names of the following candidates having been published in accordance with By-Law 5.2.2., Council has elected them to membership in the following grades: Fellows: Richard Lloyd Blandy, Byron J. Haley. Members: Brian Roger Borton, Frederick Brian Peacock, Peter John Stacey, Kenneth Niles Thanstrom. Students: Peter Boesley James, Kenneth Brian Perel. TRANSFERS From Member to Fellow: Cecil Eugene Fivaz, Peter Edwards. I wish to welcome the new members to the Institute and to congratulate those members who have been transferred to a higher grade. ANNUAL REPORT OF THE COUNCIL AND ACCOUNTS FOR THE YEAR ENDED 30TH JUNE 1971 THE PRESIDENT: We now come, ladies and gentlemen, to the annual report of the Council of the Institute-and our accounts for the year ended 30th June, 1971, and these documents are on your chairs; I know you probably haven't had time to study them yet, but I would like to highlight some of the things which I think are worth mentioning. I would ask you to take, first of all, ladies and gentlemen, the report of the Council as being read, and before moving adoption, however, there are certain salient points I wish to touch on, and I will leave the financial side of this entirely to our very competent and worthy, Honorary Treasurer, Mr Denis Maxwell.

By B. Yu, M-H. Cao, C. Zhou, X-Z. Zhang

The transient infiltration and lubrication behaviour of slag during continuous casting of steel is important for billet quality. A two-dimensional coupled mathematical mould model was developed to investigate these phenomena. The accuracy of the model was verified by comparing the calculated slag consumption with measurements by the plant. The results show that the liquid slag is consumed from the middle and late period of positive strip time to the next early period of positive strip time, including the entire negative strip time. The maximum downward infiltration velocity and positive pressure in the slag channel is at the middle of the negative strip time. Increasing the positive pressure of the slag channel is conducive to lubrication. The shear stresses acting on the shell surface and at the mould side were determined by the lubrication slag consumption and total slag consumption, respectively, and gradually decreased with increasing slag consumption. The negative strip time was lengthened to increase the slag consumption and prolong the time near the maximum downward shear stress, so as to be conducive to the demould.

Apr 16, 2024

By J. L. Havenga

South Africa produces about 400 Kt zircon (ZrSiO4) per annum. This represents about 30 percent of the global demand. However, very little is beneficiated locally and more than 95 percent is exported with little or no value addition. Zircon is a very inert material and needs to undergo high-temperature alkaline melting processes to produce valuable zirconium products. The conversion of zircon to plasma-dissociated zircon (PDZ) produces a chemically reactive species (ZrO2.SiO2) which consist of finely divided submicron monoclinic ZrO2 crystals dispersed in a SiO2 matrix. In this paper, an in-flight, non-transferred arc pilot plasma plant with a capacity of 100 kg/h and which consists of three 150 kW DC plasma torches, is described. The optimization of the plant, which includes the use of different zircon concentrates, the influence of particle size, feed rates, plasma gas, and energy utilization, is discussed.

Jan 1, 2012

By J. L. Havenga

South Africa produces about 400 Kt zircon (ZrSiO4) per annum. This represents about 30 percent of the global demand. However, very little is beneficiated locally and more than 95 percent is exported with little or no value addition. Zircon is a very inert material and needs to undergo high-temperature alkaline melting processes to produce valuable zirconium products. The conversion of zircon to plasma-dissociated zircon (PDZ) produces a chemically reactive species (ZrO2.SiO2) which consist of finely divided submicron monoclinic ZrO2 crystals dispersed in a SiO2 matrix. In this paper, an in-flight, non-transferred arc pilot plasma plant with a capacity of 100 kg/h and which consists of three 150 kW DC plasma torches, is described. The optimization of the plant, which includes the use of different zircon concentrates, the influence of particle size, feed rates, plasma gas, and energy utilization, is discussed.

Jan 1, 2012