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By M. Coetzee

The susceptibility of experimental low-nickel Cr-Mn-N stainless steels to hot cracking, sensitization, and pitting corrosion in the as-welded condition was investigated. These steels were developed for deep-drawing applications and are similar in composition to type 201 stainless steel. In order to obtain good formability, the rapid rate of work-hardening (characteristic of the 200-series steels) was decreased by the addition of copper. The behaviour of two sets of alloys during fusion welding was investigated: 17Cr-7Mn-4Ni-o.5Cu steels containing 0.001 to 0.27 per cent nitrogen, and 17Cr-7Mn-2Ni-o.1N steels with copper contents varying between 0.01 and 3.11 per cent. Al the steels in these two sets initially solidify as d-ferrite, which transforms partially to austenite during cooling. As the nitrogen level increases, the microstructure of an autogenous-weld metal ranges from large amounts of d -ferrite, martensite, and Widmanstätten austenite, to austenitic structures with small amounts of vermicular d -ferrite. The formation of d -ferrite during solidification and the presence of ferrite retained in the weld metal indicate that the experimental alloys will not be susceptible to hot cracking during welding. Except for the alloy with 0.27 per cent nitrogen, the resistance to pitting corrosion of the experimental steels in the as-welded condition is inferior to that of type 304 stainless steel. None of the experimental steels is susceptible to intergranular attack in the as welded condition. The alloys with 0.19 and 0.27 per cent nitrogen have properties (corrosion and microstructure) similar to those of type 304 stainless steel in the as-welded condition.

Jan 1, 1996

Interpretation of Leached Outcrops, by Roland Blanchard. Published by Nevada Bureau of Mines, University of Nevada, Reno, Nevada, 89507, 1968, 188 pages. Price $7.50 (R5.40). This book contains a summary of the author's knowledge of leached outcrops, derived from some 30 years' experience as a geologist operating mainly in the United States of America and Australia. Part 1 of the book provides a comprehensive coverage of the various processes and substances involved in the oxidation of many minerals, under different climatic conditions, to form the final leached products. In Part 2, details are given of the appearance and composition of the oxidation products of the following minerals: pyrite, pyrrhotite, arsenopyrite, cha1copyrite, cha1cocite, bornite, tetrahedrite, oxidized copper minerals, galena, cerussite, sphalerite, molybdenite, chromite, hematite, magnetite, manganite, pyrolusite, calcite, siderite, fluorite, salite and supergene silica. The illustrations, the black and white photographs and the colour plates of oxidation products are of a high standard. The material is presented in a logical order and in terms which are not over-technical; hence it is useful to persons other than trained geologists. Despite the advances in geophysical and geochemical prospecting, the location and interpretation of gossans remains an important method of discovering ore bodies, particularly so since the correct interpretation of a leached material can prevent the fruitless and expensive prospecting of an underlying body of uneconomic concentration. Therefore it is considered that this volume will be a valuable addition to the libraries of universities, exploration companies and geologists. It is of interest to note that the author, who died in 1966, presented a paper, under the same title as this book, to the Chemical, Metallurgical and Mining Society of South Africa in 1939. For this work he was awarded the Society's Gold Medal. W.T.S.

NOTICES PROCEEDINGS OF THE SECOND INTERNATIONAL CLEAN AIR CONGRESSThis massive volume of 1,380 pages contains all the papers presented at the congress held in December 1971. INDEX TO SOUTH AFRICAN PERIODICALS This bibliographical work has been produced by the Johannesburg Public Library since 1945, and is of interest to all our readers. THE CONTROL OF GASEOUS SULPHUR COMPOUND EMISSION An international conference on this theme will be held at the Salford University from 10th to 12th April, 1973. COLLOQUIUM ON SLlMES DAMS The South African Institute of Mining and Metallurgy have great pleasure in advising members that two-day colloquium on Slimes Dams is being arranged for the 14th and 15th November, 1973. NATIONAL INSTITUTE FOR METALLURGY / NASIONALE INSTITUUT VIR METALLURGIE REPORT. VERSLAG No. 1424 REVIEW OF THE WORLD'S FLUORSPAR INDUSTRY, WITH PARTICULAR REFERENCE. TO SOUTH AFRICA Ist August, 19n Investigator: H. H. Gossling SYNOPSIS The consumption of fluorspar has increased significantly during the last three years, and a consumption of approximately 5,76 million tonnes per annum is projected for 1975. REPORT. VERSLAG No. 1432 LABORATORY METHOD No. 44/2 THE DETERMINATION OF RUTHENIUM AND OSMIUM IN THE RESIDUES RESULTING FROM THE LEACHING OF MATTES 5th July, 19n Investigators: Magdalena M. KrUger R. V. D. Robert SYNOPSIS The method described involves the sintering of the residue with barium peroxide, and the distillation of ruthenium and osmium from the sinter. REPORT. VERSLAG No. 1439 THE REACTION OF SULPHIDE MINERALS WITH THIOL COMPOUNDS 29th June, 19n Investigator: L. A. Goold SYNOPSIS A selected group of thiol reagents was reacted with a wide range of sulphide minerals, and products that were formed at the surface were extracted and identified by infrared spectrophotometry.

1. New Publications Tin and its uses no. 140. Greenford (England), International Tin Research Institute, 1984. Catalogue. English translations of German standards 1984. Berlin, Beuth Verlag GmbH, 1984. Mining and mineral processing operations in Canada 1983. Ottawa, Canadian Government Publishing Centre, 1984. $6.00. Canadian mineral deposits not being mined in 1983. Ottawa, Canadian Government Publishing Centre, 1984. $6.00. 2. Mintek Publications Report M42D The recovery of tantalite and cassiterite from a bulk sample of pegmatite supplied by Falconbridge Explorations Limited. (First issued 1982.) Report M46D Tests on the nature and reduction of the chlorine in fluorspar concentrate from the western Transvaal. (First issued 1982.) Report M58D An electrochemical process for the recycling of tungsten carbide scrap. (First issued 1982.) Report M59D Testwork on samples of oxidized ore from the Potgietersrus Prospect. (First issued 1982.) Report M60D The production of electrolytic manganese dioxide from furnace sludge. (First issued 1983.) Report M64D Isotope-source neutron-activation analysis for the determination of manganese in bulk samples. (First issued 1982.) Report M128 The determination of cyanide in hydrometallurgical process solutions and effluents by ion chromatography. Report M132 Mineralogical parameters influencing the acid-bacterial leachability of low-grade nickel ores. Report Ml34 The NIMROC reference materials: revised values for thorium, yttrium, lanthanum, and the rare-earth elements. ReportM140 The effect of physical and chemical factors on the corrosivity of a synthetic mine water. Report Ml44 The development of standard procedures for the evaluation of magnetite for use in heavy-medium separation. Report M145 A preliminary study of the mineralogy of the nickel occurrence at Mabilikwe Hill, northern Transvaal.

Jan 1, 1984

By P. G. Henderson, G. C. Thompson

The organization and mechanized colliery management of a large by G. C. THOMPSON, B.Sc. (Min. Eng.) (Witwatersrand), M.B.L. (Member), and P. G. HENDERSON, B.Sc. (Min. Eng.) (Pretoria), M.B.A. (Member). Usutu Collieries Limited, at present the largest single producer of coal in South Africa, supplies Cam den power station. and produces 435 000 tonnes per month by conventional mechanized methods from bord-and-pillar workings in three mines. The thickness of the seams averages 2 metres, and the depth below surface varies from 15 to 150 metres. Each mine depends to a different extent on certain common facilities and services. Two of the mines are located on the same coalfield, and their rationalization would possibly be advantageous. Production policy is one of productivity with flexibility. The double-loader system is widely used, and one section at each mine is worked on single shift. Pillar extraction is practised where possible. In addition to lubrication and inspections, planned maintenance of mining equipment consists of sub-assembly replacements and overhauls. Conveyor and tractor/trailer transport is used underground. but trolley-wire locomotive haulage is being considered. The organization is such that co-ordination is relatively difficult, and certain changes could possibly improve the functioning of the engineering and mining departments. Technical and management training is carried out. Long-term planning will make use of a computer programme and will involve the investigation of other mining methods. Five-year and twelve-month plans are prepared, the planning of coal quality being based on the view that the mine and the power station together constitute a system. Control information systems make use of a remote computer terminal located at the mine. An improved integrated system is being investigated.

Jan 3, 1975

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

The March General Meeting of the Institute was held in Kelvin House, Johannesburg on 18th March, 1970, at 4.30 p.m. Mr J. K. E. Douglas (President) was in the Chair. There were also present fifteen Fellows, Messrs H. Britten, R. C. J. Goode, Prof D. D. Howat, Mr T. C. A. Meyer, Dr R. E. Robinson, Messrs V. C. Robinson and P. W. J. van Rensburg (Council Members), S. K. de Kok, Dr N. P. Finkelstein, Messrs K. W. Findlay, H. N. Hepker, J. Levin, Dr K. A. Murray and Mr A. H. Mokken. Four Members including Mr D. Ayres, Dr M. I. Britten and Dr A. Granville. One Associate: Mr G. S. Stander. One Student, Mr R. N. Guest. Four Visitors, Messrs S. A. Allison, C. N. Leibb, C. J. Kooij and A. Mavrogordato. Secretary: Mr D. C. Visser. Total present: Twenty-seven. OBITUARY The President: "It is my sad duty to announce the death of Henrik Johannes Van Eck, Honorary Life Member, who joined the Institute in 1929 and passed away on 18th February, 1970. Dr van Eck started life as a chemist and chemical engineer and, as we all know, he rose to become one of our most distinguished leaders of industry in the country. On many important occasions we, in this Institute, have been privileged to have him address us on subjects which were always of great importance and relevance to the developments in this country. He was a man of great vision and imagination and could put across his ideas in a most eloquent and convincing manner. In his important position as chairman of the Industrial Development Corporation and of Iscor, whatever he said carried great weight. Busy as he was he always found time to participate not only in the affairs of this Institute but in many other technical and public bodies. His passing is a great loss to South Africa and we in this Institute wish to associate ourselves with the many other tributes which have been paid to this great man. We extend our sympathy to his wife and family and as a mark of respect I would ask you to rise and observe a few moments silence." MEMBERSHIP The President: "I have much pleasure in announcing that the names of the undermentioned candidates, having been published in accordance with By-Law 5.2.2, Council has elected them to membership of the Institute in the following grades: Fellow: Ian Douglas Bruce Corner, Joachim Bernhard Rolfes. Member: Michael Vernon Nolan. Associate: Karl Franz Wilhelm Eick. MEMBERS TRANSFERRED TO A HIGHER GRADE From Member to Fellow: Nilo Zolezzi. From Graduate to Member: Roger Billingham. I welcome the newly elected members to the Institute and congratulate the members who have been transferred to a higher grade." PAPERS FOR PRESENTATION The President: (i) "Mr Lee, may I call on you to deliver your paper entitled 'A new bubble pick-up technique as a rapid flotation test method'." After the presentation of the paper the President said: "The paper which Mr Lee introduced this afternoon was a short one but was nonetheless important in that it described a new tool for use in flotation test work. Those of us who have experienced the frustration of trying to solve flotation problems by trial and error methods know what this means. I well remember 25 years ago at T.G.M.E. trying to improve the recovery from the flotation plant there by trying various combinations of reagents and then having to wait a couple of days for the assay office to give results. Even then, on the small scale laboratory tests which had to precede full scale tests one could never be sure that the results obtained were reproducible on the full scale. Here it seems we have a relatively simple apparatus which can measure instantly the effectiveness of various reagents under different concentrations and pH values, etc. It is most important, I believe, that developments of this kind be reported in our journal for the benefit of all involved in such work, not only so that we know about it but also in order to provoke constructive discussion which might lead to further developments. I would like to invite members, therefore, to submit papers or notes on important

The first neutrinos in nature ever detected by man were "caught" in a unique laboratory some 3 km (over 2 miles) underground in one of the world's deepest mine shafts at East Rand Proprietary Mines (ERPM), Boksburg. Only 100 m from where gold is being mined from the rock face a small team of South African and American physicists work on one of the most fascinating and important fundamental research projects that is currently exciting the imagination of the scientific world. Neutrinos are sub-atomic particles just as are protons, neutrons and electrons, but they are unique in that they have neither electric charge nor mass. Cosmic neutrinos travel at the speed of light and penetrate stars and planets. Even a million kilometres of solid lead would not provide a satisfactory shield against them. Stars are believed to "burn" by means of nuclear reactions which produce enormous fluxes of neutrinos. The sun, for example, illuminates the earth with visible light, but also bathes it with neutrinos. After World War II, two American physicists, Profs Frederick Reines and Clyde Cowan, experimenting at a large nuclear reactor, succeeded in obtaining direct evidence of the existence of the laboratory-produced neutrino. It then became very important to establish whether neutrinos also existed in nature. This knowledge would lead to a greater understanding of the forces of nuclear physics, of the behaviour of nuclear particles and, indeed, is also relevant to astrophysics. From the start it was clear that the search for "natural" neutrinos would be difficult. Questions which arose were- * how could they be traced if they were without mass or electric charge? * how could other nuclear particles be screened off? * could these not be wrongly detected, or even prevent accurate detection of neutrinos? Neutrinos were known to be produced along with charged particles, by the reaction of primary cosmic rays with the constituents of the atmosphere. It was also known that when the neutrinos collided with matter, they themselves produced the same type of charged particle which could be detected if the unwanted charged particles from the atmosphere could be screened off. What was needed, therefore, was a laboratory where the particles produced in the atmosphere could be screened out, yet which would receive and detect the particles produced by the neutrons' collision with the matter (solid rock) in the vicinity of the laboratory. This meant that scientists either had to build a laboratory with an enormously thick lead shield for their detection work. . . or they could go as near as possible to the centre of the earth where only charged nuclear particles of the very highest energies could penetrate. ERPM was clearly the most suitable place in the world where so effective a "neutrino trap" could be set. Under more than 3 000 m of solid rock the apparatus for detecting neutrinos is well shielded against unwanted nuclear particles produced in the cosmic radiation which can reach the laboratory only in a steeply vertical trajectory. Other particles are easily stopped by the great thickness of rock. The air-conditioned laboratory is at one end of a 150 m long tunnel, 2,5 m high and wide, blasted from the rock. The electronic recording equipment is housed here, while the rest of the tunnel is filled with the detection system. When a charged particle passes through a detector element, it produces a minute flash of light which is recorded and which triggers a flash-tube array. This then defines the trajectory of the charged particle, which is also recorded on film for analysis. So far 82 neutrinos have been detected, 50 at the present level and 32 at a higher level, and the findings have borne out the physicists' theoretical expectations. In this joint project Profs Reines, J. P. F. Sellschop, Director of the Witwatersrand University's Nuclear Research Unit and M. F. Crouch of the Case-Western Reserve University of Ohio are the Chief Investigators. This unique endeavour has been made possible by financial support from the US Atomic Energy Commission, the University of the Witwatersrand and the Chamber of Mines of South Africa, as well as by the cooperation of the management and men of ERPM.

By C. P. Naudé

Mechel, a large, integrated steel, stainless steel, and ferroalloy producer in Russia is committed to upgrading its facilities to world class pyrometallurgical process and environmental practice. Yuzhural Nickel currently uses shaft furnaces to produce a matte containing iron, nickel and traces of cobalt. This rather old technology is thermally inefficient and is characterized by high operating costs. Mechel has investigated suitable equipment and processes to upgrade the plant, and awarded a contract for the construction of a 12 MW DC smelter, located near the town of Orsk, to Bateman Engineering Projects in June 2008. The selection of DC furnace technology for laterite smelting can be considered as a strategic highlight for the pyrometallurgical treatment of low-grade lateritic ores, and could be the first industrial-scale implementation of this technology. This project has been designed to achieve multiple goals including the demonstration of the process and associated equipment technology at commercial scale, to confirm the scale-up design parameters of the forthcoming 2 x90 MW, twin electrode DC furnaces, and to prove the environmental emission superiority of closed furnaces. It also provides a valuable operator training platform. This paper deals with the process design, key technology building blocks and design features which have been incorporated to produce a pyrometallurgical vessel capable of (i) resisting slag superheat and chemical aggressiveness, (ii) process fine material without pre-agglomeration, (iii) achieve high nickel recoveries and(iv) being tolerant to the variations in chemical composition of laterite ore. The approach to increasing campaign lives between partial and complete rebuilds, through the use of composite furnace module (CFM) technology originally developed and patented by the University of Melbourne, is also followed in more detail. Unfortunately, results from hot commissioning and lessons learned from initial operation are not available because the project completion has been delayed due to the worldwide downturn in demand for commodities. Keywords DC furnace, ferronickel laterite smelting, corrosive slag, coppercooler technology.

Jan 1, 2010

By B. Steyn

AngloGold Ashanti?s Obuasi Mine, in Ashanti Province, Ghana, operates a plant utilizing bacterial oxidation technology. The mineralization consists predominately of arsenopyrite with gold associated in the sulphides. The plant was commissioned in 1994, at that time was the largest BIOX® plant in the world, and has been operated by AngloGold Ashanti since 2004. The constraints identified in the plantwere the flotation capacity, BIOX® feed size and disruptions to the BIOX® process. This paper focuses on the practical steps that were followed in order to increase the recovery of the plant. The original plant design was based on a head grade of 10 g/t and an overall recovery of 86.5%. In 2007 the plant was operating at an overall recovery of 79.2% at a head grade of 5.6 g/t and this has improved to 80.6% at a head grade of 5.8 g/t during the last quarter of 2008. Additional improvement to 81.5% are expected by the end of April 2009. Improvements that have been implemented include: ?Replacement of the regrind mill ?Installation of additional float capacity ?Installation of a scavenging circuit ?Installation of a complete water treatment plant. In addition we have focused on the effect of the water circuit on the BIOX® process and the steps involved in correcting this problem. The water circuit was originally designed as an open circuit and through environmental considerations the circuit was closed towards the end of 2007. The bacteria in the BIOX® are particularly sensitive to cyanide and cannot tolerate levels above 0.05ppm (free cyanide), this required extensive modifications to the water circuit. The plant improvement project is ongoing and the current scope of work should be complete by the end of April 2009. Further research and development work is being planned, which includes a ?white rot bacteria? that can consume the preg-robbing carbon and oxidize the sulphide in a single pass.

Jan 1, 2009

By J. Portal

One of the key products produced by the mineral sands industry is the titanium dioxide slag, a process that requires grinding of a coarse product down to a valuable saleable product. Traditional methods have included the vertical roller mill in tandem with dynamic air classifiers and, alternatively, two-stage grinding and crushing through an AG mill in closed circuit with a dynamic classifier and secondary gyradisc crushers. The products produced, commonly known as chloride and sulphate slag, are differentiated by the particle size distribution of the final product. The more valuable chloride slag must, by specification, be a product sized in the range between 850 and 100 microns?the more fines generated in the grinding process, the less higher valuable final chloride slag is produced. This paper will explore a technology that is new to both the mineral sands and to other mineral processing industries. Inter particle communition, or IPC as it is known, has been applied in the cement industry to improve the performance of clinker grinding mills. The principle is to create a process of material on material comminution under high pressure that fractures the material along the grain boundaries rather than breaking it smaller than a gap setting in the crusher. The process is now looked at for the TiO2slag producers because of the potential benefits of energy savings and with a minimal generation of minus 100-micron fines. Discussions will revolve around the design and functionality of the Rhodax® both from a process and maintenance perspective, a typical test regime and results on slag grinding. The development of the flowsheet necessary for the process will be examined, the ancillary equipment required and finally the scale-up from the test to an industrial plant will be investigated. Full-scale results of an operating plant will also be given showing the benefits that can be realized. A promising new flowsheet with fines reintroduction to the Rhodax® crusher will be presented.

Jan 1, 2007

By F. T. Cawood

This paper reviews the Mineral and Petroleum Resources Royalty Bill of 2006, identifies potential areas that require further consideration by the National Treasury and, where appropriate, offers alternatives. At its basic level a royalty regime consists of two elements: the base and the rate that must be applied to the base. Deciding on an acceptable royalty rate is a complex matter and can be done only after extensive analysis of all variables affecting the competitiveness of the regime. The proposed royalty rates are in the range of zero to five per cent and are based on sales revenue. It is argued that future investment patterns are more likely to be influenced by market cycles and commodity prices than policy events. Inevitably the current boom in the minerals sector will come to an end and the success of the proposed regime will be known only when profit margins are under pressure. Policy makers must therefore have the long run in mind when developing policies that affect the ability of industry to do business, without the need to renegotiate each time there is a change in the market. A long-run policy must be sufficiently flexible to allow for consistently fair sharing ratios and splitting of revenues between government and industry. Although broadly in line with international practice, the current version cannot be regarded as internationally competitive and efficient. In order for the royalty bill to become internationally competitive, promote beneficiation of mineral production and adequately compensate the State for the loss of a national resource, the National Treasury should heed the following main recommendations in this review: 1. Abandon the notion that each mineral product must have its own royalty rate; 2. Introduce an NSR type royalty that allows for value-addition costs to be deducted from the base; and 3. Provide for automatic relief through the use of a sliding-scale mechanism based on ability to pay, e.g. the X-Factor used in the gold mining tax formula.

Jan 1, 2007

By G. L. Gomes-Sebastiao, W. W. de Graaf

"Gomes Sand is a quarry operation that produces sand and aggregate for the construction industry. The quarry is experiencing inconsistencies in the fragmentation and poor pit conditions as a result of poor drilling and blasting practices. This results in excessive downtime in the load and haul and crushing processes.A benchmarking exercise of the blasting practices was conducted to evaluate the effect of the inconsistency on the mining cycle. After changes in the blasting practices the downtime was reduced, which improved the crushing plant utilization by 4.9%. The improved blasting practices and more consistent fragmentation decreased the average number of loads lost each month due to jaw crusher blockages from 9.2% to 3.9% of plant throughput. The change in blasting practices also improved pit conditions. IntroductionGomes Sand is a quarry operation that has been in operation since 2009, producing sand and stone for the construction industry. The quarry was experiencing unacceptable blasting results. The repercussions included uneven pit floors, large amounts of oversize rock (>500 mm), and inconsistent fragmentation.The blast results affected the load and haul operations as well as the efficiency of the crusher. This resulted in downtime in the daily operations, and consequent production and revenue losses.The crusher product should have a top size of 50 mm. A blast fragmentation of <50 mm would improve the downstream operations and the crusher throughput.An investigation into the blasting practices was carried out to assess whether the downstream delays can be eliminated by improving the blast results. The exercise included:* Assessing if the designed blast layout is adhered to on the bench* Observing the quality and control of drilling* Observing the charging procedure of the blast-holes* Benchmarking the fragmentation consistency of the blasted rock using current blast design and practices* Analysing the throughput of the crushing plant* Investigating the power consumption of the crushing plant and determine if a change in blasting practices will affect this* Evaluating the hours spent by the hydraulic hammer on secondary breaking."

Jan 1, 2017

By S. Gqebe, A. Lewis, M. Rodriguez-Pascual

"Gravitational sedimentation of suspensions in various precipitation processes is hindered by colloidal stability. This is due to the high surface charge of the suspension and results in strong attraction/interaction between the ions on the particle surface and counter-ions in solution. Moreover, this strong interaction results in a charge build-up that renders the suspension stable. In order to induce gravitational sedimentation of these particles, a redistribution of ions close to the particle surface is required. We therefore sought to redistribute ions close to the particle surface by applying a magnetic field. This results in the reduction of interparticle electrostatic repulsive forces and a subsequent increase in the zeta potential of a suspension. For the purpose of this study, a copper sulphide suspension was used. Copper sulphide particles were exposed to a range of field strengths for set exposure times and their zeta potential was measured before and after exposure. All particles had an initial zeta potential value equal to or less than –40 mV prior to magnetic field exposure. A significant increase in zeta potential was observed, with values reaching a maximum of –16.5 mV when exposed to a 2 T field strength for 40 minutes. This is due to Lorentz ion shifts resulting from the Lorentz force exerted by the magnetic field on the particle surface. IntroductionMetal sulphide precipitation is a process for treating industrial waste streams with high residual concentration of mixed metal ions and acid mine drainage. This process has been reported to achieve higher metal removal compared with the industrially prevalent lime precipitation, due to the sparingly soluble nature of the metal sulphide precipitates formed. However, precipitation is governed by high levels of supersaturation which favour the formation of fine particles (Lewis, 2010). Consequently, some of the metal sulphide fines formed exhibit slow settling dynamics and thus tend to remain suspended in solution."

Jan 1, 2016

By G. A. Bezuidenhout, J. P. T. Kapusta, D. K. Chibwe

"Peirce-Smith converters (PSCs) are extensively used in the copper, nickel, and platinum group metals industries to remove iron and sulphur from the molten matte phase. This technology has not changed significantly since its inception in the early 20th century. The typical converting operation involves lateral purging of air/oxygen-enriched air into molten matte through a bank of tuyeres. This blowing operation occurs at low air pressure from the blowers, and the induced bubbling regime is considered inefficient from both a process and an energy utilization perspective. Inherent drawbacks include recurrent tuyere blockage, inevitable tuyere punching operation to clear airways, and low oxygen efficiency as a result of substantial air losses due to leakages.Investigations in the 1980s demonstrated1 that jetting into Cu and Ni converters could reduce or eliminate some of the process difficulties. In spite of these findings, very little progress has been made in the application of these concepts for converting of non-ferrous melts on a commercial scale.As part of its operational improvement and energy reduction initiative, Western Platinum embarked on a full-scale industrial evaluation of generating a jetting regime by using sonic injection. Prior to full-scale industrial evaluation, a numerical assessment was conducted to ascertain the feasibility of implementing sonic injection on Lonmin converters. The work included flow characterization at high injection pressures achieving sonic velocity at the tuyere exit. The 2D and 3D simulations of the three-phase system were carried out using the volume of fluid (VOF) and realizable k- e turbulence models to account for the multiphase and turbulence nature of the flow, respectively. These models were applied using the commercial CFD numerical code FLUENT.This paper discusses the key findings regard ing understanding of gas plume extension, velocity distribution, shear wall stress analysis, and phase distribution characteristics in the system. Plant trials are also discussed with reference to the commercial aspects of a fullscale implementation of sonic injection in the smelter."

Jan 1, 2014

1. Recent publication Iron and steel works of the world. Worcester Park (England), Metal Bulletin PLC, 1987. 9th edition, 728 pp. £94.75 by air mail.2. Canadian publications Mining and mineral processing operations in Canada, 1987. Mineral Bulletin MR 216. $15. (Obtainable from Printing and Publishing, Supply and Services Canada, Hull, Quebec, KIA 059 Canada.) Peat producers in Canada, 1986 directory, by M. Prud&apos;homme. MRI 87/7 Canadian mines: Perspective from 1986. Reserves, production capability, exploration, development. Mineral Buletin MR 215. $9.95. 3. Mintek publications Report M313 The testing of abrasion resistance in pipeline materials, by D.P. Enright. Nov. 1987. 36 pp. Report M328 The installation and commissioning of a Hilger Monospek D500 scanning monochromator, by A.E. Watson. Sep. 1987. 11 pp. Report M331 The design and operation of hot-air dryers for the drying of granular activated carbon. Nov. 1987. 30 pp. Report M338 Ore microscopy, image analysis, and the extractive metallurgy of sulphide minerals-an overview. Nov. 1987. 14 pp. Report M339 The determination, by flow-injection analysis, of sulphate in solutions containing chromium(I/I) and iron(I/I). Nov. 1987. 11 pp. Report M222D The simultaneous determination of common anions by ion chromatography, by A. Cameron and C. Pohlandt. Oct. 1985, reissued May 1987. 10 pp. Report M227D The spectrophotometric determination of silica in metallurgical-grade fluorspar, by M. Solomons. Nov. 1985, reissued Jun. 1987. 9 pp. Report M229D The determination of metalic iron in prereduced iron ores, by R. Lownsbrough. Dec. 1985, reissued Jun. 1987. 7 pp. Report M252D The spectrophotometric determination of bismuth in sulphide materials, by M. Solomons. Mar. 1986, reissued Jun. 1987. 13 pp. Special Publication no. 12 Platinum in South Africa, by A.M. Edwards and Silk. 1987. 64 pp. Illustrated in colour. R30 ( Africa), US$30 (other countries). 4. Journals of interest Industrial Minerals. London, Metal Bulletin Journals Ltd. Tin and its uses no. 154, Nov. 1987.

Jan 1, 1988

The Institute of Lighting Engineers of South Africa The Institute of Lighting Engineers of South Africa (ILESA) was constituted in May 1972 and now has over 70 members. The first Annual General Meeting was held on 15th August, 1973, at the Philips Auditorium, when the first presentation of membership certificates was made. Book Reviews Der Hochofenprozess. Das kinetischdynamische Simulationsmodell des Vereins Deutscher Eisenhiittenleute.Diisseldorf, Verlag Stahleisen M.B.H., 1973. Jones, M. H. and Woodcock, J. T. Ultraviolet spectrophotometry of flotation agents with special reference to the determination of xanthate in flotation liquors. London, Institution of Mining and Metallurgy. 1973. 25 pp. £2,50. Notice VI INTERNATIONAL CONGRESS OF ENGINEERS The above congress is to be held in Barcelona from 6th to 10th October, 1974. NIM reports Report No. 1568 A computer programme for the estimation of parameters in flotation. Report No. 1571 The commissioning of a direct-reading spectrometer for the analysis of silicate rocks by use of the graphite-pellet technique. Report No. 1579 The determination of tin tn geochemical- survey samples. Report No. 1587 A preliminary investigation of the flotation of copper-activated sphalerite without the use of collectors. Report No. 1589 Preliminary investigations into the flotation of tin dioxide, cassiterite, and some related gangue minerals. Professional . engineers Reference (18/19/1) 22nd November, 1973 Dear Sir/Madam, From time to time questions are being asked publicly concerning registration of professional engineers. These questions mainly concern the time it takes to finalise applications, especially those of applicants who do not hold a recognised engineering qualification. Professionele . . Ingenleors Verwysing (18/19/1) 22 November 1973 Geagte heer/dame, Van tyd tot tyd word daar vrae in die openbaar gestel oor die registrasie van Professionele Ingenieurs. Vrae gaan veral oor waarom dit so lank neem om aansoeke af te handel, veral van aansoekers wat nie &apos;n erkende ingenieurskwalifikasie besit nie.

Jan 3, 1974

By L. Thomson

"The smelter at Sudbury Integrated Nickel Operations, located in Sudbury, Ontario, operates a single electric AC furnace. This furnace treats nickel sulphide concentrates produced by Glencore and third-party feeds and as such its performance is key to the company’s nickel supply chain. Currently the plant has two shutdowns per year in order to carry out significant repairs on matte tap-holes.Improved monitoring systems that enable better prediction of tap-hole wear have been a continued focus. The electric furnace is an essential piece of the smelter flow sheet requiring the need for planned tap-hole maintenance along with robust systems for management according to to this plan.The ability to meet our goal of zero harm is ensuring that safe practices are in place. Detailed procedures and cool-down practices have been implemented to ensure that required matte chemistry and temperature criteria can be met during the period leading into a shutdown for tapblock maintenance.A significant repair of the electric furnace will take place in 2015. During this rebuild, the sidewalls and matte endwall will be replaced. There is work underway to improve wall and matte end performance in an attempt to extend the time between rebuilds. This paper will review the approach taken towards this end."

Jan 1, 2014

Geological mapping makes an important contribution to orebody knowledge during the evaluation of structurally controlled gold veins. Orebody knowledge comprises an understanding of mineralization characteristics relevant to evaluation, mining, processing and environmental issues and allows project expectations to be realistically set. Structural interpretation to define continuity and mineralization controls is a key part of geological risk reduction and the reporting mineral resources using the JORC and other codes. The Dolgellau gold belt is a small British field that produced an estimated 150 000 oz from narrow quartz veins. Historical records, recent exploration and production data, published material, and accessible surface and underground exposure provide a valuable case study. Previous mapping has shown the general geometry of vein systems, but tends to accentuate gross geological continuity. Recent work has attempted to determine internal vein architecture and examine the significance of the historical views of ore shoot controls. The work resulted in the definition of vein continuity scenarios for the gold belt and evaluation expectations associated with each. This has, in turn, led to a realistic view of what can be achieved from an evaluation and project development perspective.

Jan 1, 2009

By Kevin Peacocke

The future of Gravity ? Primary mineral recovery ? Enhancement of existing process efficiency ? Pre-Concentration ? Alternative? or ?New? production

Jan 1, 2006