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By R. T. Jones

Base metals and platinum group metals can be collected in metallic alloy form, via a wide variety of smelting processes. The recovery, or degree of collection, of the valuable metals is a function of the extent of reduction in the furnace, which, in turn, is indicated by the fraction of iron present in the feed materials that report to the alloy. An equation has been developed that relates the recovery of various metals (such as Ni, Co, Cr, and PGMs) to the recovery of Fe. This recovery equation (for each metal) is characterized by a single parameter (K?) that can either be empirically fitted to the data, or expressed in terms of the equilibrium constant and the ratios of the activity coefficients involved. Data from a number of varied DC arc furnace campaigns are presented to illustrate this behaviour.

Jan 1, 2009

What is a nugget effect? In the early development of geostatistics, the term ?nugget effect? was coined for the apparent discontinuity at the beginning of many semivariogram graphs. This name was chosen to reflect the large differences found between neighbouring samples in ?nuggety? mineralizations such as Wits gold reefs. Geostatistical theory assumes that the difference between a sampled value and a potential repeat sample at the same location is actually zero. Included in this ?nugget effect? would be true variation between contiguous samples due to the nature of the mineralization, micro-fracturing, nugget or crystal size, and so on. Also included in the nugget effect would be any ?random? sampling variation which might occur due to the method in which the sample was taken, the adequacy of the sample size, the assaying process, etc. Arguments were put forward that ?sampling errors? actually exist at zero distance. Some geostatistical schools actually maintain that the ?nugget effect? is all sampling error. This would imply that ?perfect? sampling would eliminate the nugget effect entirely. There is now a dichotomy both in the geostatistical world and in the software packages provided for geostatistical analyses. It may seem academic to argue over whether the semivariogram model should take a value of zero, a value equal to the nugget effect, or a partial value at distance zero. However, the decision can have a profound effect on both the estimated resource and in our confidence on that resource. Whereas most geostatistical texts define the semivariogram model as taking the value of zero at zero distance, others imply that the full nugget effect should be used at zero distance. For example: ?The nugget effect refers to the nonzero intercept of the variogram and is an overall estimate of error caused by measurement inaccuracy and environmental variability occurring at fine enough scales to be unresolved by the sampling interval3 ?Christensen4 has shown that the ?nugget effect?, or non-zero variance at the origin of the sernivariogram, can be reproduced by a measurement error model ?The nugget effect is considered random noise and may represent short-scale variability, measurement error, sample rate, etc.5. In many training texts and Web courses, the definition of the semivariogram is ambiguous as the formulae for semivariogram models is not actually specified at zero distance6,7,8.

Jan 1, 2010

Council and Standing Committees-1984/85 President: J.D. Austin Vice Presidents: H.E. James and Dr H. Wagner Immediate Past President: Prof. R.P. King Honorary Treasurer: Prof. D.G. Krige Members of Council: B.C. Alberts, Prof. S. Budavari, E.B. Crocker, N.J. Devine, C.E. Fivaz, J.S. Freer, Prof. G.G. Garrett, J.J. Geldenhuys, Dr A.K. Haines, R.W.O. Kersten, Dr B.K. Loveday, I.D. Matthews, G. Maude, H.G. Mosenthal, B.E. Protheroe, Dr O.K.H. Steffen, Dr P.T. Wedepohl Chairman, Witbank/Middelburg Branch: W.C. Mather Chairman, Orange Free State/Klerksdorp Branch: Dr M.A. Orridge Past Presidents Serving on Council: Dr M.G. Atmore, Prof. A.N. Brown, Dr P.R. Jochens, G.Y. Nisbet, Prof. R.P. Plewman, Dr R.E. Robinson, Prof. M.D.G. Salamon, P.W.J. van Rensburg, D.A. Viljoen, P.A. von Wielligh Standing Committee Chairmen: Adjudication, Prof. R.P. King; Awards, Prof. R.P. King; Constitution, Rules and Policy, Prof. R.P. King; Excursions and Banquet, B.E. Protheroe; Journal, H.E. James; Membership, Dr H. Wagner; Phoenix National Committee, Dr M.G. Atmore; SAIMM School-Extractive Metallurgy, J.S. Freer; SAIMM School-Mining, Prof. S. Budavari; Special Publications, J.D. Austin; Technical Programme¬Extractive Metallurgy, Dr B.K. Loveday; Technical Programme-Mining, J.J. Geldenhuys; Technical Programme-Physical Metallurgy, Dr P.T. Wedepohl; Training, Career Guidance and Education, Prof. R.P. King; World Mining Congress-National Committee, Prof. R.P. Plewman; Working Group Physical Metallurgy, Prof. G. G. Garrett

Jan 1, 1985

South Africa?s now a member of this body, tailored on the World Bank, and headquartered in Abidjan-Cote d'Ivoire. As a funding agency for capital projects within 59 member countries of the ADB it is to be expected that there are guidelines to the requirements for funding application and for project management and control.

Jan 1, 1996

Actual observations of rockburst damage, together with some theoretical considerations, strongly suggest that conventional approaches to the design of tunnel support are inappropriate where there is a significant seismic risk. The present widely used support systems, which are based on stiff, fully grouted re-bars, are inadequate where rock displacement velocities exceed 1 m/s. It is shown by means of a simple conceptual model that yielding of the support elements is essential to ensure their survival when they are subject to the high strain rates typical of severe rockbursts. The model proposes that the total load in the element is an impulsive tensile force imposed and sustained by a single 'tributary' block ejected from the tunnel wall. The stability of the system is determined from a comparison of the kinetic energy developed by the block with the energy of deformation absorbed by a grouted steel tendon. A novel test procedure was developed for the validation of this approach, and for an examination of the energy-absorbing capacity of stiff and yielding tendons. The results of an initial series of tests showed that the recently developed cone-bolt is an effective yielding device. It absorbs twenty times more impulsive-load energy than is consumed by the complete fracture of grouted re-bar of equivalent strength, and it remains totally unscathed. Importantly, the results demonstrate that the ejection model is not merely an explanatory concept, but can be used as a representative and valid design method.

Jan 1, 1994

By S. Poirier, J. -M. Facteau

The gold mine sector is presently facing low gold prices as well as technological challenges. Its competitiveness and survival will depend on new mining methods and equipment to improve ore extraction. In 1999, Natural Resources Canada has invested new funds over a period of three years at CANMET’s Experimental Mine to establish the Narrow-Vein Mining Project. A team of engineers and researchers specialized in mining, mechanics and electronics engineering are working to meet the critical need of ore-extraction technology. CANMET’s programme in mechanization and automation for narrow-vein mining had, prior to 1999, realised several important achievements, many in co-operation with a consortium of mining companies(Soredem). The investment of new funds in this area will contribute to develop technologies to improve the productivity, as well as health and safety conditions of the narrow-vein mining industry. Several important impacts of this project will be monitored. In particular, a database of methods and equipment used in narrow-vein mining is being developed. A key thrust is to identify operators’ needs with respect to the development and automation of mining methods and equipment. Based on those needs, research and development projects will be created. The paper will present the objectives of the narrow-vein mining project and some of the results, including the web site developed to present the results of the project.

Sep 1, 2001

By T. F. Muller

In recent years, a great deal has been written and spoken, both in our country and overseas, about the dangers posed to the environment and the ecology by mining operations. The object of this address is to put this problem, and it is a real problem, into reasonable perspective. I shall try to present the various facets that merit consideration as objectively as possible. In doing so, I shall examine the following factors: Book review National Coal Board. Gate belt conveyors. London, H.M.S.O. (Price 95p.) Although the preface of this handy little book states that it has been written for the guidance of miningoperation trainees, it will prove valuable to the practising engineer as well. NIM reports Report no. 1733 A mineralogical investigation of weathered carbonatite from Salpeterkop. (14th Apr., 1975; re-issued 28th Feb., 1978). Report no. 1823 The recovery of gold and pyrite from a residue dump at Crown Mines. (10th Jul., 1976; re-issued 28th Feb., 1976). Report no. 1829 An investigation of weathered carbonatite from Salpeterkop. (20th Jul., 1976; reissued 28th Feb., 1978). Report no. 1932 A BASIC computer programme for the evaluation of intensity data from the Telsec Lab-X-250 Analyser. (12th Jan., 1978). Report no. 1940 The extraction of the noble metals with n-octylaniline, and its application to the analysis of platinum-bearing materials. (30th Jan., 1978). Report no. 1945 Analyses of the NIMROC reference samples for minor and trace elements. (28th Feb., 1978). Report no. 1945 Analyses of the NIMROC reference samples for minor and trace elements. (28th Feb., 1978). International futures conference A conference entitled 'The Road Ahead' is being organized by the 1820 Settlers National Monument Foundation to be held in Grahamstown from 3rd to 7th July, 1978. Conference of metallurgists The technical programme has been established for the 17th Annual Conference of Metallurgists sponsored by the Metallurgical Society of the Canadian Institute of Mining and Metallurgy. This year the Conference will be held in Montreal, Quebec, on 27th to 31st August, 1978, together with the 8th Hydrometallurgy Meeting.

Jan 1, 1978

By R. M. Spang

Abstract Between the German city of Dresden and the Czech capital Prague a 4-lane highway is under con-struction. At the outskirts of Dresden it will cross the narrow and deeply eroded Weißeritz Valley by a bridge. Two twin tube tunnels under oblique angles join the bridge out of the rocky valley flanks. The different geotechnical conditions of these 4 tunnel portals, their design and construction are described within this publication. The two southern portals of the tunnel Dölzschen are situated within a vertical 65 m high former quarry slope, 25 m above the valley floor. The slope proved instable due to toppling failure and exposed serious rockfall risks. Systematic anchoring, scaling, rock bolting, netting and filling under extreme access conditions eliminated these risks. Tunnel excavation started from the slope surface without any pre-cut or conventional portal construction. The opposite northern portals of the tunnel Coschütz are situated in more gentle rock slopes. After removal of debris, excavation of the eastern tunnel started in a 30° slope striking oblique to the driving direction, without any precut, too. Because of the gentle slope inclination the cross section was not earlier completely covered by rock than 30 m behind. The western tunnel started from an optimized short, narrow and steep precut. Its flanks were stabilized by reinforced shotcrete and rock bolts. Because of the small distance between the tubes rock bolts were drilled into the cross section of the neighboring tunnel. Tunnel excavation was made by drill and blast operation, preliminary support consisted of steel arches, reinforced shotcrete and radial rock bolts. Thorough survey of the bolt’s coordinates and direction prevented them from meeting each other. Rock bolts were of the permanent type to prevent the final lining from being obliquely loaded. Systematically arrayed measuring devices checked deformations of slopes and tunnels. Zusammenfassung Der Neubau der Bundesautobahn A 17 wird Dresden und Prag miteinander verbinden. Die vierspurige Autobahn quert westlich von Dresden das enge und tief eingeschnittene Tal der Wilden Weißeritz mit einer Brücke. An beide Brückenwiderlager schließen mit schiefwinkligem Anschnitt doppelröhrige Tunnel an, deren Portale in den felsigen Talflanken liegen. Die unterschiedlichen geotechnischen Verhältnisse, die Überlegungen für einen jeweils optimalen Entwurf und der Bau der portalnahen bergmännischen Tunnelabschnitte sind Gegenstand dieser Veröffentlichung. Die Südportale des Tunnels Dölzschen liegen in einer vertikalen, 65 m hohen Felswand, 25 m über dem Talgrund. Die Felswand erwies sich als global kippgefährdet, außerdem lagen flächig verteilte erhebliche Steinschlag- und Felssturzrisiken für Bau und Betrieb vor. Die Kippgefahr wurde durch ein Systemraster aus vorgespannten Felsankern, die Steinschlag- und Felssturzrisiken durch bergsteigerisches Beräumen mit dem Brecheisen, Felsnägel und Steinschlagschutznetze eliminiert. Der Tunnelausbruch begann von einer Vorschüttung direkt in der Felswand ohne Voreinschnitt im Schutz einer kurzen Luftbogenstrecke. Die gegenüberliegenden Nordportale des Tunnels Coschütz befinden sich in wesentlich flacheren Hängen. Nach dem Aushub einer mehrere Meter dicken Abraumhalde begann der Tunnelausbruch der östlichen Röhre asymmetrisch mit einer Luftbogenstrecke in einer spitzwinklig zur Vortriebsrichtung streichenden, 30° mit dem Vortrieb steigenden Felsfläche, ebenfalls ohne Voreinschnitt. Wegen der flachen Neigung der Böschung war der Tunnelquerschnitt erst nach 30 m vollständig überdeckt. Für den Vortrieb der westlichen Tunnelröhre mussten erst eine zwischen den Röhren vorhandene Felsnase teilweise abgetragen, die westlich anschließende zurückspringende Felswand vertikal gestellt und gesichert und Felsaushub in der rechten Flanke getätigt werden. Der damit entstehende Voreinschnitt wurde so kurz wie möglich und ohne seitliche Arbeitsräume ausgeführt. Die Sicherung der Böschungen erfolgte mit bewehrtem Spritzbeton und Felsnägeln. Wegen des geringen Abstands der beiden Röhren wurden die unteren Lagen der radialen Ausbruchsicherung durchgeankert. Der Tunnelvortrieb begann im Schutz eines geankerten Portalkranzes und ebenfalls von einer Luftbogenstrecke aus.

Jan 1, 2003

1. Reviews Extraction metallurgy, by J.D. Gilchrist. 3rd ed. Oxford, Pergamon, 1989. 431 pp. £50.00 (hard cover), £14.95 (soft cover). Reviewer. Prof. M.D. Brayshaw. Reviewer. Prof. M.D. Brayshaw This third edition bears testimony to a work that contains much of value for lecturers, students, and practising metallurgists. Mineral processing in the United Kingdom, edited by P.A. Dowd. London, Institution of Mining and Metallurgy, 1988. 223 pp. £25.00. Reviewer: Prof. M.D. Brayshaw It came as both a pleasure and a challenge for a resident of South Africa (with its volume and diversity of minerals) to review a book focusing on the beneficiation of ores from the sparsely endowed mineral chests of the United Kingdom. 2. Recent issues Rock mechanics. Theory and applications with case histories, by W. Wittke. Translated from German by R. Sykes. Berlin, Springer-Verlag, 1990. 1076pp. DM248. McGregor's quick reference to the JSE. Pretoria, Juta & Co., 1990. R39,95. McGregor's economic alternatives. Pretoria, Juta & Co., 1990. 400 pp. R34,95. 3. New journals Journal of Materials Chemistry, edited by A.R. West and J. Leader, and published two-monthly by The Royal Society of Chemistry (Blackhorse Road, Letchworth, Herts SG6 IHN, OK). £195 per year, starting in 1991. New Materials World, published monthly by Lawrence Cooklin (15 Selvage Lane, Mill Hill, London NW? 3SS, OK). £180 per year. Mendeleev Communications 4. Books from The Institute of Metals The following were published recently, or are to be published soon, by The Institute of Metals, 1 Carlton House Terrace, London SWl Y SOB, OK. Illustrated case histories of marine corrosion. 1990. Modern steelmaking methods, by C. Moore and R.I. Marshall. 2nd ed. 1990. Grain boundary fractures, by S.F. Pugh. 1991. 160 pp.

Jan 1, 1991

By G. Y. Nisbet

The contribution made to the economy of South Africa by the-minerals industry is discussed according to four of its aspects. Firstly, the industry supports both students and lecturers in technical and academic institutions. This support covers virtually the whole range of courses available at the universities and technikons, although most is obviously devoted to the engineering and science faculties. Secondly, the industry makes a direct financial contribution to the State in that it contributes about40 per cent of the State's receipts from direct tax paid on incomes and 30 per cent of the contributions to the total State revenue. It provides employment for 28 per cent of the total active labour force, and contributes 24 per cent directly to the gross domestic product. Thirdly, the industry is responsible for over 65 per cent of the country's foreign earnings in spite of the significant rise in exports from the manufacturing sector. South African minerals are of crucial importance to the word, since the country has the world's largest reserves of seven minerals and features very prominently in many others. Finally, the industry makes an indirect contribution, referred to as the multiplier effect. This is the ripple effect on the economy made by a large injection of momey by which that money acquires an added effective value. A study made of the total production of the mining industry in 1978, for instance, showed this multiplier to havea value of 1,5. Thus, if this effect is included, the industry's contribution to the gross domestic product is 44,S per cent. Similarly, the industry is responsible for the creation of jobs both within itself and in other industries, which could amount to 100000 for the period 1981 to 1935.

Jan 1, 1981

By Mike McWha

Drivers to increasing RM use ?Compliance issues ?Section 12 JSE Listing Rules ?Canadian NI 43-101 ?Sarbanes Oxley ?Shortage of African ore reference materials ?Poor perceptions about quality of some local RM?s

Jan 1, 2005

By Mark Coleman

Pnuematic Conveying and Process Injection Technologies have been implimented in the metals markets for the last 40 years and have consideribly improved the productivity and the performance of many processes. There have been many steps forward in handling technology and this paper seeks to consider those now offered by Clyde Materials Handling who as an established customer-driven solutions provider, which has turned its attention to supporting the Metals Market. Clyde seek to utilises its knowledge, expertise and technologies to transform the production processes of its customers, who operate in the ferrous and non-ferrous metals industries. With over 30 years experience in the process improvement industry, Clyde Materials Handling has helped their global customer base transform the way in which they operate their processes, which has enabled them to generate sustainable economic benefit and maintain their positions as leaders in their respective markets. Operators within the metals market have developed and deployed pneumatic conveying and pneumatic injection technologies. These environmentally supportive and sustain-able solutions have been used to transport raw materials within operating facilities, from storage to silo, as well as injecting these materials directly into the heart of production processes. Operators, such as Codelco in Chile, Corus Steel in the UK, and many others across the World have seen pneumatic injection solutions transform their process and costs. To inject a consistent, pulseless and accurate flow of material to a copper concentrate bath smelter, or injecting granular or pulverized coal as a coke substitute in to a blast furnace via the Tuyeres helps to increase the operational capacity, availability and productivity and reduce the cost of the operation. This paper will discuss and highlight the ways in which pneumatic conveying and injection technologies, created by Clyde Materials Handling, and applied in partnership with the customer, have helped to improve the operational performance of the production processes of operators across the non-ferrous metals markets with specific reference to applications in the Lead and Zinc Industries. With examples from Zinc Fuming in Australia, Zinc Calcine and Powder Handling in Korea, Precision coal injection to QSL and TSL Furnaces, and metered distribution of Zinc Calcine to Reactors.

Jan 1, 2008

By J. Little

It is common practice for underground mine plans to be created sequentially, where results from one planning process form the input data for another. While this is practical for manual methods, computerized optimization techniques should consider an integrated approach to creating the global mine plan. This is because optimizing an individual mine planning process, such as stope layouts, introduces a likelihood of increasing costs or decreasing revenues associated with other areas, such as production scheduling, as harmful decisions must be balanced. Considering the interaction and influence that individual underground mine planning processes have on each other during optimization will provide more profitable results than if these are ignored. Optimization techniques for stope layouts and production scheduling are reviewed. An integer programming model is proposed that allows for either integrated or isolated optimization. Both approaches are separately applied to a block model. The results demonstrate the model?s ability to produce optimal long-term sublevel stoping mine plans and the benefits of using an integrated approach. Keywords underground mine optimization, stope layouts, underground production scheduling, integer programming, mathematical programming application.

Oct 1, 2013

The Western Cape Branch of the SAIMM recently held a one-day colloquium on the use of artificial intelligence (AI) in process engineering in the I.S. Gericke conference room at the University of Stellenbosch

Jan 1, 1992

By I. Satola, J. Aromaa

In this work we have reviewed methods to classify corrosivity of ground waters. Weight loss and stress corrosion cracking (SCC) corrosion tests have been done for rebar and steel strand. No clear indication of SCC was found. The application of tensile stress to 85 % of yield strength increased general corrosion rate significantly in very corrosive waters. The effect of corrosion protection on the axial behavior of steel strands was determined by double pipe axial tests with different embedment lengths. The results showed a significant difference on behavior between epoxy-coated steel strands, galvanized steel strands and plain steel strand. Dans la présente étude, nous avons passé en revue des méthodes permettant de classifier la corrosivité des eaux souterraines. Des tests portant sur les pertes de poids et sur la corrosion FCC (la fissuration par corrosion sous contrainte) ont été effectués pour les barres d’armature et les torons. Aucune indication nette de FCC n’a été constatée. L’application d’une contrainte de traction allant jusqu’à 85 % de la limite d’élasticité a accru de manière significative la vitesse générale de corrosion dans les eaux très corrosives. L’effet de la protection contre la corrosion sur le comportement axial des torons en acier a été déterminé au moyen de tests axiaux à double tube avec des longueurs d’enrobage différentes. Les résultats ont mis en évidence une différence significative quant au comportement entre les torons en acier à revêtement époxy, les torons en acier galvanisés et les torons en acier standard. In dieser Arbeit haben wir Methoden geprüft, die korrosive Wirkung des Grundwassers einstufen. Gewichtsverlust- und SCC-Korrosionstests wurden für Stahlstäbe und Drahtlitzen durchgeführt. Es wurden keine sicheren Hinweise auf Spannungsrisskorrosionsbrüche gefunden. Bei Anwendung einer Dehnbelastung von 85 % der Streckspannung bzw.Ergebnisstärke stieg die allgemeine Korrosionsrate in stark korrosivem Wasser deutlich an. Die Wirkung des Korrosionschutzes bei axialem Verhalten von Stahldrahtlitzen wurde durch axiale Tests an Doppelleitungen unterschiedlicher Versenkungslänge determiniert. Die Ergebnisse zeigten im direkten Vergleich von epoxidbeschichteten, galvanisierten und normalen Stahldrahtlitzen beachtliche Unterschiede im Verhalten auf.

Jan 1, 2003

The Annual General Meeting of the South African Institute of Mining and Metallurgy was held in Kelvin House on Wednesday, 25th August, 1976. Dr R. E. Robinson, (President) was in the chair, and declared the meeting open at 16h00. Obituaries The president: It is my sad duty to announce the death of the following members of the Institute : P. A. Creewell, Life Fellow; A. S. Davis, J. S. Hay, P. O. Large, N. McCaskell, and H. G. M. McKerrow, Life Members; C. L. Bererge, Fellow; T. Bulloch, G. Douglas, R. W. Forrester, and C. G. P. Sack, Members; P. R. Garcia, W. A. Naude, and J. P. Slager, Associates. 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 The President: May we confirm the minutes of the General Meeting held on March 17th, 1976, as published in the June issue of the Journal? Agreed. Welcome The President: It is my pleasant duty to welcome a number of guests and distinguished visitors this evening. First, I would like to welcome Mr R. Plumbridge, the President of the Chamber of Mines, and Mrs Plumbridge. We have had very close co-operation with the Chamber of Mines, and it is particularly gratifying that Mr Plumbridge has had time to be with us this evening in spite of very heavy engagements. Ook 'n spesiale woord van verwelkomirg aar mrr. N. Orsmord, die Staatsmyringerieur, en mev. Orsmord. Ors wil hierdie geleertheid gebruik om mrr. Orsmord geluk to wens met sy aarstellirg as die Staatsmyrirgerieur en die hoop uitspreek dat dit baie jare van samewerkirg met hierdie Irstituut sal beteker. We also welcome guests who, in one way or another, have been able to attend most of our Annual General Meetings, the Honourable I. B. Dillon, the Minister of Mines of Rhodesia, and Mrs Dillon. Once again we welcome them most heartily to our Annual Meeting. I would also like to welcome the representatives of many of our sister institutions : the Honorary Treasurer of the AS & TS, Mr D. G. Maxwell; the President of the South African Institution of Mechanical Engineers, Mr A. R. Adams; the Vice-President of the South African Institute of Electrical Engineers, Mr K. A. H. Adams, and Mrs Adams; the President of the Institute of Certificated Mechanical and Electrical Engineer s, Mr Martin and Mrs Martin; a member of the Executive of the South African Institute of Civil Engineers, Professor G. Bright ; the President of the South African Chemical Institute, Mr Vic Shuller, and Mrs Shuller; the President of the Institute of Welding, Professor F. P. A. Robinson, and Mrs Robinson; the President of SACPE, Mr M. R. Gericke ; the President of the Institution of Metallurgists, South African Branch, Mr D. R. Allen; the President of FSPE, Dr P. J. D. Lloyd, and Mrs Lloyd ; Mr A. J. H. Pole of the Association of Mine Managers, and Mrs Pole; and Mr M. D. Hoskin of the South African Institute of Foundrymen. A special word of welcome to Mr G. C. Young of our Orange Free State Branch, and Mrs Young ; and to Mr E. J. Jackson of our Witbank/Middelburg Branch. We have great pleasure in welcoming Dr F. M. Naude, the Scientific Adviser to the Prime Minister, and Dr W. C. J. van Rensburg, Technical Director of the Minerals Bureau. The latter is a new organization, and we hope their attendance here this afternoon forecasts a long period of co-operation between the Minerals Bureau and this Institute. Ook wil ek hartlik hier verwelkom die Rektor van Die Randse Afrikaanse Universiteit, professor G. van N. Viljoen. Ors het baie noue samewerking met die Universiteit gekry, en ek wil ook bier verwelkom die twee verteenwoordigers van die Geologiese-afdeling en die Chemie-afdeling, naamlik, dr C. Roering en professor G. W. Holzapfel. Last, but by no means least, a word of welcome to a very old friend, Mr Eric Boden, the Manager of AS & TS. To all our guests, a very hearty welcome to this our Annual General Meeting. Membership The President: It is required by our Constitution that I announce the names of a number of candidates who have been elected to various grades of membership. The list is a very long one, and I suggest that we simply record that these names will be published in the Journal. Any one who wishes to comment on these members should do so in writing to our Secretary. Agreed. Fellows: G. Paterson, P. H. Adler, F. W. G. Schoning, J. P. de Villiers, F. I. de Waal, J. R. H. Shaw. Members: C. J. Slavin, P. J. Perkins, R. J. I. Butler, A. M. Hattingh, C. E. Alvey, J. A. Engelbrecht, P. L. Gouws, J. P. Martin, J. F. Taylor, K. A. G. Blendulf, A. R. Gibb, W. E. Smith. Associate Members: D. R. Broderick, D. F. Cilliers, D. N. Stuart, P. Kraus, B. G. Pinder. Associates: D. E. Gibbon, D. F. Jacobs, R. F. W. Swanepoel, R. D. H. Bebb, H. H. Vernall, R. D. Gibson, J. P. van Wyk. Graduates : A. N. Morris, D. J. Payne, G. S. Worthington, A. S. Dennison, A. R. Godfrey, N. Holloway, W. J. Rankin, G. S. Lyndon, R. J. van Proctor, J. J. Versluis, G. M. Miller. Students: B. J. Rabie, G. D. Webber, W. L. Blair, I. D. Mathews, K. McVey, S. W. Beer, R. W. J. Bentley,

Jan 10, 1976

By L. Chen, G. A. Brooks, S. A. Nightingale

The dissolution of alumina and magnesia has been investigated using laser scanning confocal microscopy (alumina) and a rotating finger apparatus (magnesia) to assess the effects of temperature, composition and forced convection on the rate of dissolution in CaO-SiO2-Al2O3based slags. The two techniques have differing strengths and limitations, and provide complementary methods for studying dissolution. Alumina dissolution was studied for temperatures from 1477 to 1577°C. Based upon the data, the rate controlling mechanism was thought to be mass transfer control in the slag. The diffusion coefficients for the alumina particles are estimated to be in the range 10-11to 10-10m2.s. MgO degradation for sample rotation speeds of 50 to 800 rpm at 1500 and 1530°C was studied for both congruent and incongruent dissolution. The results show that the rate of dissolution for this is primarily controlled by a diffusion mass transfer mechanism for congruent dissolution except at the highest rotation speed. For incongruent dissolution, the mechanism is much more complex, with the morphology and distribution of the spinel reaction product having a significant effect. At high speeds and prolonged times, mechanical forces played a major role in the degradation process. Keywords; kinetics, corrosion, refractories, dissolution rate, inclusions, mass transfer, slags, steelmaking

Jan 1, 2004

By L. Ozdemir, B. Asbury, T. G. Rozgonyi

A new type of bit, that has been developed and is being evaluated, shows great potential in expanding the range of rock strength that can be cut by continuous miners and roadheaders. This new style of bit is called the frustum. The tools tested in this program were developed, manufactured and patented by Briese Industrial Technologies, Inc. The frustum derives its name from the unique geometric shape of the cutter, or cutting insert. The frustum shape cutting tool has previously been proven as an effective cutting tool for machining metals, metal matrix composites and polymers. The frustum rock bit has a very dense carbide frustum shape tip mounted on the end of a steel body similar to the conical bits typically used on continuous miners and roadheaders. In between the carbide frustum cutting tip and the steel body there can be a bearing that allows the frustum to rotate around the bit axis. When the bit is forced into the rock at a skewed angle, the frustum tip rotates as it travels. This rotation greatly reduces the cutting forces acting on the bit when compared to the current state of the art conical drag bits. This cutting force reduction, derived from the frustum’s cutting action, allows for much harder and more abrasive rock to be cut without quickly wearing out the bit. Full scale laboratory cutting tests have been performed with the frustum bit in direct comparison to the current state of the art conical bits. Field trials of the frustum bit are currently being planned. Test procedures, results and findings are presented.

Sep 1, 2001

By W. M. Jansen

In many mineral processing operations, the reported production figures for an accounting period may not make the best use of available data. While most of the mathematical approaches, such as check-in/check-out, mass balancing, used in effective metallurgical accounting strategies are well understood, the sources and magnitude of measurement errors generally are not. As part of the 'AMIRA P754-Metal Accounting and Reconciliation' project, a study was undertaken at the Northparkes copper/gold concentrator near Parkes, New South Wales to examine the data used in their concentrator metallurgical accounting system. This paper summarises the results of a detailed examination of the mass measurement systems around the concentrator as well as the primary sampling system used for grade estimation. The goal of this work was to develop practical techniques to quantify the error (ie both accuracy and precision) of the measured metal accounting information. With this information, statistical confidence levels for this data can then be calculated. If the errors are small, the effect of error in each piece of measured data can then be propagated to other calculated production figures such as recovery and feed grade using a statistical technique called `the propagation of error'.

Jan 1, 2007

Council and Standing Committees - 1983/84 President: Prof. R.P. King Vice Presidents: J.D. Austin and H.E. James Honorary Treasurer: Prof. D.G. Krige Immediate Past President: Prof A.N. Brown Members of Council: B.C. Alberts, Prof. S. Budavari, N.J. Devine, Dr C.J. Fauconnier, P.T. Fewell, C. E. Fivaz, J. S. Freer, Prof. G.G. Garrett, J.J. Geldenhuys, Dr A.K. Haines, Dr B.K. Loveday, G. Pienaar, B.E. Protheroe, Dr O.K.H. Steffen, G.C. Thompson, Dr H. Wagner, Dr P.T. Wedepohl Chairman, Witbank/Middelburg Branch: H.C. van Zyl Chairman, Orange Free State/Klerksdorp Branch: D.A. Parfitt Past Presidents Serving on Council: Dr M.G. Atmore, Dr J.P. Hugo, Dr P.R. Jochens, Prof. R.P. Plewman, G.Y. Nisbet, Dr R.E. Robinson, Prof. M.D.G. Salamon, P.W.J. van Rensburg, D.A. Viljoen, P.A. von Wielligh Standing Committee Chairmen: Adjudication, Prof. A.N. Brown; Awards, Prof. A.N. Brown; Banquets, J.S. Freer; Constitution, Rules and Policy, Prof. A.N. Brown; Excur¬sions, J.S. Freer; Journal, H.E. James; Membership, H.E. James; Phoenix National Committee, Dr M.G. Atmore; SAIMM School - Extractive Metallurgy, Dr A. K. Haines; SAIMM School - Mining, Dr H. Wagner; Special Publica¬tions, J.D. Austin; Technical Programme - Extractive Metallurgy, Dr B.K. Loveday; Technical Programme - Mining, G. C. Thompson; Technical Programme -Physical Metallurgy, G. Pienaar; Training, Career Guidance and Education, Dr M.G. Atmore; World Mining Congress - National Committee, Prof. R.P. Plewman; Working Group Physical Metallurgy, Prof. G.G. Garrett

Jan 1, 1984