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By C. Chapman, M. G. Reading, M. P. Amsden

Computer control of flotation at the Ecstall concentrator By M. P. AMSDEN, C. CHAPMAN, and M. G. READING Ecstall Mining Limited, a subsidiary of Texas Gulf Sulphur Company, operates the Kidd Creek Mine, a 10000 tons per day base metal producer, near Timmins, Ontario. Two different types of ore are mined and milled: copper-zinc and silver-lead-zinc. At the highly automated Ecstall concentrator the ores are processed by selective flotation in three individual circuits. One of the most important metallurgical tools for process control is a sample system incorporating continuous on-stream X-ray analysis. Recently this system was automated further by the addition of computer control of reagents for two copper-zinc flotation circuits. The computer programs, utilizing optimum seeking methods and smelter contract terms, have increased copper recovery by 1,1 per cent, zinc recovery by 1,4 per cent, and have reduced reagent costs by 16 per cent. Although not expected, copper and zinc concentrate grades were improved slightly as well.

By P. J. D. Lloyd, Jill Urban, M. R. Urban

The adsorption of gold from cyanide solutions onto constituents of the reef, and its role in reducing the efficiency of the gold-recovery process by M. R. URBAN. M.Sc. (Chem. Eng.) Rand (Visitor). JILL URBAN. B.Sc. (Chem. Eng.) Rand (Visitor) and P. J. D. LLOYD. Ph.D. (Cape Town) (Fellow) Evidence for the adsorption or re-precipitation of gold from cyanide solutions onto gangue minerals of the Witwatersrand reefs has been gathered over a number of years by various investigators. The evidence from tests using radioactive tracers is conclusive and indicates thlt adsorption contributes about 0,1 g/t to the total gold loss from conventional reduction works. The loss is a function of the alkalinity and cyanide concentration of the solution, and it appears to be affected by the extent of time between milling and cyanidation. The heavy minerals appear to be the strongest adsorbers, and the clay minerals somewhat less strong adsorbers. A sensitive qualitative test based on thin-layer chromatography permits the extent of adsorption and desorption to be readily determined.

By H. M. Krieg, M. J. Ungerer, C. G. C. E. van Sittert, D. J. van der Westhuizen

"The transition metals tantalum (Ta) and niobium (Nb) are of significant importance, for example in the nuclear energy sector where they are used as cladding materials, as well as in capacitors and specialized materials. For these applications a high-purity metal is needed. The separation of Ta and Nb is always a challenge since they are found together in nature and have similar chemical and physical properties, resulting in costly and laborious separation processes. A technology that has been used successfully for the separation of these metals entails solvent extraction (SX)1. While separation was achieved in a previous SX study using a sulphuric acid (H2SO4) medium with the extractants diiso-octyl phosphinic acid (PA) and di-(2-ethylhexyl) phosphoric acid (D2EHPA), due to the absence of speciation data for Ta and Nb it is not clear how the separation occurred.One method that might be suitable for determining the speciation of a reaction is molecular modelling. Calculations based on the densityfunctional theory (DFT) are now used not only for light elements and small molecules, but also metal complexes, heavy metals, and especially metal separation in SX2. In this study the aqueous phase used during SX was investigated by studying periodic systems of Ta, as a metal and in salt form, when it is in contact with H2O and H2SO4. The results were used to predict the reaction mechanism occurring during SX. Results showed that (i) in a 1:1 acid-water ratio, the deprotonation of H2SO4 was endothermic, (ii) in a 1:5 ratio deprotonation was exothermic forming HSO4 -, and (iii) in a 1:10 ratio double deprotonation occurred to form SO42- exothermically."

Jan 1, 2017

By D. W. Horsfallt

The above paper gives a fair amount of information and is a useful addition to the literature on a subject of growing importance. I believe that more experimental results could have been given, together with more details of the modifications made to the plant that enabled it to operate with the success mentioned in the paper. One important omission is a definition of the word fines. As pointed out elsewhere!, this word is used very loosely.

Jan 1, 1980

By Gernot Beer, Christian Dünser, Marcos Noronha

The main findings of the joint research initiative “Numerical Simulation in Tunnelling” and a follow-on project on efficient numerical simulation models for tunnelling are presented. Die wichtigsten Resultate des Forschungsschwerpunkts „Numerische Simulation im Tunnelbau“ und einem Folgeprojekt über effiziente numerische Simulationsmethoden werden präsentiert Les résultats les plus importants du point principal de la recherche "simulation numérique dans la construction de tunnels" et un projet consécutif sur des méthodes de simulation numériques efficaces sont présentés

Jan 1, 2003

The Third International Conference on Coal Research was held in Sydney, Australia, in October 1976. The papers and proceedings of the Conference will be published in Australia on behalf of the International Committee for Coal Research in April 1977. The papers deal with the economics and practicability of coal conversion, coal winning, resources assessment, safety and dust, and coal and power generation, together with an appreciation of coal potential by the deputy chairman of the U.K. National Coal Board. Copies of the report are available to organizations within member countries of ICCR at a cost of 35 dollars (Australian), including postage, by application to the Executive Officer, Third ICCR, Box 3842 GPO Sydney, Australia 2001. Drafts should be in Australian currency payable to Third International Conference on Coal Research.

Jan 6, 1977

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 26th August, 1970, at 4.15 p.m. Mr. J. K. E. Douglas (President) was in the Chair. There were also present sixty-three Fellows, thirty-five Members, one Graduate, eight Associates, five Students and nineteen Visitors, making a total of one hundred and thirty-two. The President declared the meeting open at 4.20 p.m. OBITUARIES The President: 'It is my sad duty to announce the deaths of the following members of the Institute. Dr J. A. Papenfus, Fellow, who joined the Institute in 1942 and passed away on the 28th of May, 1970. Mr D. G. Beadle, Fellow, who joined the Institute in 1946 and passed away on the 17th of June, 1970. Gentlemen, Derek Beadle was very well known in this Institute. His papers on dust will be remembered and, at the time of his untimely death, he was one of our assistant editors. 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 15th April, 1970, as published in the July, 1970, issue of the Journal'. Agreed. WELCOME TO VISITORS The President: 'Ladies and Gentlemen, we are honoured this afternoon by the presence of many distinguished guests and I extend to you all a most cordial welcome. We are happy to have with us Dr A. A. von Maltitz, President of the Chamber of Mines of South Africa, who is also Honorary President of this Institute. We also have one of our Honorary Vice- Presidents, Mr T. L. Gibbs, the Government Mining Engineer; Mr D. E. Hamm, President, Institution of Certificated Mechanical and Electrical Engineers, S.A.; Mr S. C. M. Naude, Director, Witwatersrand Technical College; Mr I. R. G. Stephen, Senior Vice-President, The S.A. Institute of Electrical Engineers; Mr G. M. Tompkins, President, The S.A. Institution of Mechanical Engineers; Professor P. B. Ackermann, President of the Geological Society of S.A.; Mr A. S. Robinson, Vice-President of the S.A. Institute of Civil Engineers; Professor W. Mare, President of the Institute of Land Surveyors of the Transvaal; Mr B. D. Charlton, President of the S.A. Institute of Assayers and Analysts; Mr R. Hemp, The President, The Mine Ventilation Society of S.A.; Mr L. J. Prince, The President, The S.A. Association of Mine Managers; Mr J. Botha, The President, The S.A. Institute of Foundrymen; Mr G. Niterl, The President, The Institute of Welding; Mr M. R. Gericke, President, S.A. Council of Professional Engineers; Mr N. A. Honnet, Chairman, Orange Free State Branch; Mr P. R. C. Cooke, Chairman. The South African Chemical Institute (S. Tvl' Section). Gentlemen, we are very honoured indeed, to have these distinguished gentlemen with us this afternoon, as our honoured guests. We are also pleased to have with us, one of our Honorary Fellows, Mr F. G. Hill, and several Past-Presidents. I also extend a very warm welcome to all our lady guests and to all our other visitors.' 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: NEW APPLICATIONS Fellows: Herbert Dalton-Brown, Stephen William Morel. Members: Clive Lester Workman-Davies, Basil James Russell Botha. Students: Timothy Nigel Watson, John William Hairbottle. I wish to welcome the new members to the Institute and to congratulate those members who have been transferred to a higher grade.' ANNUAL REPORTOFTHE COUNCILAND ACCOUNTS FOR THE YEAR ENDED 30th JUNE, 1970 The President: 'I now have pleasure in presenting to you, the Annual Report and Statement of Accounts for the year ended June, 1970. These have been handed to you this afternoon and, as is customary, I propose they be taken as read. Before moving their adoption, however, I would like to refer to some of the salient features, leaving as is usual, the task of dealing with the finances, to our Honorary Treasurer. It is encouraging that membership has continued to grow, and now stands at 1,613, an increase of 61 over last year's total. Your Council, however, is aware that there are still people in our mining and metallurgical industries, who could qualify for membership, but who have not yet joined the Institute. A drive to increase membership was accordingly organised, and members of Council were given the responsibility for campaigning in sections of industry, and for publicising the objectives and advantages of belonging to the Institute. Up to now there has not been much reaction to this campaign, but I hope we will see results in the coming year. At the same time, Council has recognised the need for change in the conduct of the Institute's affairs in order to meet the changing needs of our membership. Our members, both mining and metallurgical, are in the first place, geographically more widely dispersed than they used to be, and secondly, with the growth of the metallurgical industry, their technical interests are now more diversified. The Institute must cope with these changing needs if we are to continue to perform a useful function. The

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 26th August, 1970, at 4.15 p.m. Mr. J. K. E. Douglas (President) was in the Chair. There were also present sixty-three Fellows, thirty-five Members, one Graduate, eight Associates, five Students and nineteen Visitors, making a total of one hundred and thirty-two. The President declared the meeting open at 4.20 p.m. OBITUARIES The President: 'It is my sad duty to announce the deaths of the following members of the Institute. Dr J. A. Papenfus, Fellow, who joined the Institute in 1942 and passed away on the 28th of May, 1970. Mr D. G. Beadle, Fellow, who joined the Institute in 1946 and passed away on the 17th of June, 1970. Gentlemen, Derek Beadle was very well known in this Institute. His papers on dust will be remembered and, at the time of his untimely death, he was one of our assistant editors. 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 15th April, 1970, as published in the July, 1970, issue of the Journal'. Agreed. WELCOME TO VISITORS The President: 'Ladies and Gentlemen, we are honoured this afternoon by the presence of many distinguished guests and I extend to you all a most cordial welcome. We are happy to have with us Dr A. A. von Maltitz, President of the Chamber of Mines of South Africa, who is also Honorary President of this Institute. We also have one of our Honorary Vice-Presidents, Mr T. L. Gibbs, the Government Mining Engineer; Mr D. E. Hamm, President, Institution of Certificated Mechanical and Electrical Engineers, S.A.; Mr S. C. M. Naude, Director, Witwatersrand Technical College; Mr I. R. G. Stephen, Senior Vice-President, The S.A. Institute of Electrical Engineers; Mr G. M. Tompkins, President, The S.A. Institution of Mechanical Engineers; Professor P. B. Ackermann, President of the Geological Society of S.A.; Mr A. S. Robinson, Vice-President of the S.A. Institute of Civil Engineers; Professor W. Mare, President of the Institute of Land Surveyors of the Transvaal; Mr B. D. Charlton, President of the S.A. Institute of Assayers and Analysts; Mr R. Hemp, The President, The Mine Ventilation Society of S.A.; Mr L. J. Prince, The President, The S.A. Association of Mine Managers; Mr J. Botha, The President, The S.A. Institute of Foundrymen; Mr G. Niterl, The President, The Institute of Welding; Mr M. R. Gericke, President, S.A. Council of Professional Engineers; Mr N. A. Honnet, Chairman, Orange Free State Branch; Mr P. R. C. Cooke, Chairman. The South African Chemical Institute (S. Tvl. Section). Gentlemen, we are very honoured indeed, to have these distinguished gentlemen with us this afternoon, as our honoured guests. We are also pleased to have with us, one of our Honorary Fellows, Mr F. G. Hill, and several Past-Presidents. I also extend a very warm welcome to all our lady guests and to all our other visitors.' 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: NEW APPLICATIONS Fellows: Herbert Dalton-Brown, Stephen William Morel. Members: Clive Lester Workman-Davies, Basil James Russell Botha. Students: Timothy Nigel Watson, John William Hair-bottle. I wish to welcome the new members to the Institute and to congratulate those members who have been transferred to a higher grade.' ANNUAL REPORTOFTHE COUNCILAND ACCOUNTS FOR THE YEAR ENDED 30th JUNE, 1970 The President: 'I now have pleasure in presenting to you, the Annual Report and Statement of Accounts for the year ended June, 1970. These have been handed to you this afternoon and, as is customary, I propose they be taken as read. Before moving their adoption, however, I would like to refer to some of the salient features, leaving as is usual, the task of dealing with the finances, to our Honorary Treasurer. It is encouraging that membership has continued to grow, and now stands at 1,613, an increase of 61 over last year's total. Your Council, however, is aware that there are still people in our mining and metallurgical industries, who could qualify for membership, but who have not yet joined the Institute. A drive to increase membership was accordingly organised, and members of Council were given the responsibility for campaigning in sections of industry, and for publicising the objectives and advantages of belonging to the Institute. Up to now there has not been much reaction to this campaign, but I hope we will see results in the coming year. At the same time, Council has recognised the need for change in the conduct of the Institute's affairs in order to meet the changing needs of our membership. Our members, both mining and metallurgical, are in the first place, geographically more widely dispersed than they used to be, and secondly, with the growth of the metallurgical industry, their technical interests are now more diversified. The Institute must cope with these changing needs if we are to continue to perform a useful function. The

The June General Meeting of the Institute was held in Kelvin House, Johannesburg, on 18th June, 1969, at 4.30 p.m. Mr J. K. E. Douglas (Vice-President) was in the Chair. There were also present fourteen Members, Messrs R. J. Adamson, F. P. Bath, D. M. Jamieson, D. G. Maxwell, Dr J. T. McIntyre, and Mr P. W. J. van Rensburg (Council Members), Messrs B. F. Berry, A. F. Lee, J. E. van Leeuwen, G. G. Nicolson, N. F. Peverett, Dr A. G. Raper, Messrs E. R. Rudolph and H. R. Reid. Five Associate Members, Messrs T. D. Brown, M. R. Fuller-Good, J. S. Freer, Dr P. R. Jochens and Mr D. A. Viljoen. One Graduate, Mr P. G. Mrkusic. Five Students, Messrs N. A. Barcza, J. A. Cruise, R. P. W. Henrard, D. I. Ossin and J. C. M. Wethmar. Nine Visitors, Messrs M. Badenhorst, N. J. Bovey, H. H. Herold, Dr H. J. S. Kriek, Messrs M. S. Rennie, B. B. Segal, S. Selmer-Olsen, O. A. W. Strydom and B. Yates. Secretary, Mr D. C. Visser. Total present: Thirty-six. MINUTES The Vice-President: "May we confirm the minutes of the Monthly General Meetings held on 24th March, 16th April and 21st May, 1969 as published in the Journal?" Agreed. MEMBERSHIP The Vice-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: Members: Wilfred Desmond Morgan, Abraham Kriek. Associate Members: Rodger Neville Hampson, Robert Richard Booth Lodge. Graduates: Beverley Hugh Waiters, Gwynne Hugh Johnston. Students: Colin Edward Alvery, Peter Marthinus Haikes, Charles Aubrey Husband, John Nowell Randell, Frederick Johannes Jacobus Blaauw, Johannes Andries Breytenbach, Peter Vos, Frederik Hendrik Coetzee, Petrus Nicolaas Jacobus Smit, Patrick Alien Boardman, Robert Nelson Guest. "May I welcome the newly elected members to the Institute." (Applause.) ELECTION OF SCRUTINEERS FOR THE 1969-70 BALLOT FOR COUNCIL The Vice-President: "In terms of By-Law 9.4, I now call for nominations for scrutineers for the 1969-70 ballot for CounciL" P. W. J. van Rensborg: "I wish to nominate Messrs R. C. J. Goode, V. C. Robinson, J. K. E. Douglas, P. Lambooy, D. G. Maxwell, H. Britten and H. Simon as scrutineers."

By W. L. Van Heerden

In situ complete stress-strain characteristics of large coal specimens by W. L. VAN HEERDEN, B.Sc. Hons. (Pret.) (Visitor) The significance of ;n situ tests on large coal specimens is briefly reviewed. Tests aimed at obtaining complete stress-strain characteristics of large coal specimens with high width-to-height ratios are described. A formula for the relationship between strength and width-to-height ratios of coal pillars is proposed, and the influence of width to- height ratios on the deformation characteristics of pillars is discussed.

The Annual General Meeting of the Branch was held in the Witbank Golf Club on Thursday, 28th August, 1969 at 5.00 p.m. Mr C. G. Sowry (Chairman) was in the Chair. There were also present: Ten Members: Messrs J. Meintjes (Vice-Chairman), J. E. van Aswegen, A. C. Hofmeyr, I. Botha, B. F. v. d. Merwe, C. H. Coxon, R. Canny, R. C. J. Goode, A. Bain, G. E. Carlyon. Six Associate Members: Messrs B. T. Hosking, R. E. Powell, W. Weber, T. Bulloch, E. J. Jackson, P. J. Muller. Fourteen Visitors. Total Present: 31. The Chairman declared the meeting open and extended a welcome to all visitors including Mr R. C. J. Goode, President of the Institute. MINUTES OF PREVIOUS GENERAL MEETING The Minutes of the General Meeting held on the 26th June, 1969, were read and adopted. CHAIRMAN'S REPORT The Chairman presented a report outlining the activities of the Branch during the past year. Membership of the local Branch had increased from 80 to 99 during the year. DECLARATIONOF OFFICEBEARERS The Chairman announced that owing to his transfer out of the Witbank area, he was unable to accept the nomination as Chairman for a further year of office. The outgoing committee had elected Mr J. Meintjes Chairman and Mr A. Bain Vice-Chairman for the ensuing year. Mr J. Meintjes then took the chair. Mr J. Meintjes thanked Mr C. G. Sowry for his successful steering of the Branch during its period of inauguration. ELECTION OF COMMITTEE MEMBERS The Chairman then read the Scrutineers' Report and declared the following eight members elected as Committee Members for the 1969-1970 year: Messrs I. Botha, A. W. Brereton, G. E. Carlyon, B. T. Hosking, E. J. Jackson, B. D. McNeice, P. J. Muller, B. F. van der Merwe. TALK The Chairman then called upon Mr A. Bain to present his talk and film show on 'Impressions of the mining and metallurgy congress tour to Australasia'. CLOSURE After thanking the speaker for an interesting talk, the Chairman declared the Meeting closed at 8.40 p.m.

Orange Free State Branch Minutes of a General Meeting held at the Welkom Mine Canteen on Wednesday, 21st November, 1973, at 4-.00 p.m. Present Mr E. T. Wilson (Chairman) in the Chair, 15 Fellows and Members, 12 Associates, Graduates, and Students, and 11 Visitors (Total 38). Book review Symposium on Environmental Engineering in Coal Mining The 20 papers presented at the symposium cover some 14 subjects related to environmental engineering in coal mines, such as dust, heat, gas emissions, ventilation, noise, and lighting. Competition for students Each year the Institute offers a prize (or prizes should the entries warrant it) of up to Rl00 for the best paper or dissertation on a topic appropriate to the interests of the Institute. A.8. & T.8. Trust The A.S. & T.S. Trust has been formed with the specific object of establishing a worthwhile source of funds which can be used to further the progress of science and technology in South Africa. Nim reports Report No. 1573 A pilot-plant investigation of a flotation model. Report No. 1597 The role of sulphur in the flotation of sulphide minerals. Report No. 1599 The analysis of silicate rocks and metallurgical slags by X -ray-fluorescence spectrometry. Report No. 1607 The analysis of ion-exchange resins by X-ray- fluorescence spectrometry. Report No. 1617 An electronic differential precision thermometer.

Jan 6, 1974

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.

By F. G. Hill

The paper reviews the restrictions imposed by the Department of Mines (now the Department of Mineral and Energy Affairs) on the surface use of ground that has been undermined at shallow depths (down to a depth of244m). The reasons for the restrictions are discussed, with special reference to the early records kept by the Department of Mines on subsidence and fracture of the surface. A discussion of the nature of the strata overlying the ore-body, and the effect of undermining, is followed by a detailed account of investigational work, particularly since 1970, on the stability of shallowly undermined ground. The significance of the data collected during the investigations is considered next, with special reference to the social and economic implications. These are so farreaching, that it is proposed that the already flexible approach of the Department of Mineral and Energy Affairs in considering what structures may be built on undermined ground should become even more flexible. To this end, the appointment of a Commission is proposed to collect as much information as possible on the stability of ground undermined at shallow depth, and to revise the current overrestrictive conditions or guide lines that are in use.

Jan 1, 1981

METRICATION In order to bring South Africa into line with metric countries the world over and in view of the indisputable advantages of using the comma as a decimal sign, the Metrication Advisory Board has decided to recommend that the comma be used consistently as decimal sign as from April 1, 1971. Numbers consisting of more than three figures are separated by spaces into groups of three to the left and right of the comma, and not by commas, e.g... 2 734 671,512 73 A quantity such as 12,41 kg is read as "twelve comma four one kilograms" and 31,34 km as "thirty-one comma three four kilometres." A motor-car previously described as a 3.8 litre model now becomes a 3,8 litre model. THE BRITISH COUNCIL AWARDS 1972-1973 The British Council invites applications from permanent residents of all races in the Republic of South Africa and South West Africa, for the following awards:- SCHOLARSHIPS Scholarships are available to such residents who hold University degrees or comparable professional qualifications. The scholarships are tenable for post-graduate study at Universities and other educational establishments in Britain for the academic year of approximately ten months beginning 1st October 1972. All arrangements will be made by the British Council and the scholarships will include tuition fees, a maintenance allowance, approved travel in Britain, return fares to Britain, a books grant and a clothing grant. The closing date for applications is 31st July, 1971. BURSARIES Bursaries are available to such permanent residents who hold University degrees or who, being already established in their professions or trades, hold other qualifications. The bursaries are tenable at British educational in-institutions or other suitable establishments in Britain for a course of training, study or research lasting not less than two months or more than six. The British Council will arrange full programmes and professional contacts, and the bursaries will include a maintenance grant, a books grant, authorised course fees and certain other expenses. The British Council may, at its discretion, bear the cost of single or return fares to Britain. The closing date for application is 31st July, 1971. TRAVEL GRANTS Travel grants each of £300 are available in respect of journeys to Britain undertaken between 1st April, 1972, and 31st March, 1973, and are provided to facilitate visits to British Universities by persons holding staff appointments or graduate research posts at South African Universities. Visits must normally be of at least six months duration though grants are occasionally made for visits lasting for one complete term. Grant holders will make their own arrangements with the universities which they wish to visit and will be responsible for finding their own accommodation. The British Council's assistance is limited to the contribution towards cost of fares. The closing date for applications is 31st October, 1971. For further particulars and the relevant application forms please write stating the type of award you wish to apply to: THE CULTURAL ATTACHE BRITISH EMBASSY PRETORIA

DISCUSSION: The value of incentive payments in the mining industry by K; SMITH Published in the Journal, May 1974 H. P. CARLISLE* The author has drawn attention to one of the most important of mining problems, viz productivity, and in so doing has highlighted, perhaps inadvertently, the difficulty of assessing productivity. Competition for Students Each year the Institute offers a prize (or prizes should the entries warrant it) of up to R100 for the best paper or dissertation on a topic appropriate to the interests of the Institute. Corrigendum The Journal, May 1974, p. 377 We regret that the last portion of A. A. Hazell's contribution to the paper 'The value of incentive payments in the mining industry' by K. Smith was printed in the wrong sequence.

Jan 10, 1974

By F. E. Steffens

The application of kriging in assessing the area rainfall in a weather modification experiment is complicated by the presence of many zero rainfall recordings on a given day, and the fact that the variograms seem to be quite different for the rainfall on different days. Indicator variograms are shown to be directly related to two sets of conditional probabilities. Probability kriging is used in estimating the probability of rainfall amounts above any cutoff at any point

Jan 1, 1987

By E. Keskinkilic

In this study, sulfide-type inclusion morphologies of a Ca-treated hot-rolled wheel steel, Grade-X, were investigated. The specimens taken from the hot-rolled products of Grade-X heats were studied. The size and distribution of elongated sulfide inclusions were examined for the heats of different S levels. Elongated sulfide inclusions were either not observed or rarely encountered when ladle analysis S content was below 50 ppm. The size and relative abundance of sulfide inclusions were reported to increase markedly when the S composition was greater than or equal to 70 ppm and the Ca/S ratio was less than 0.50. The effect of Ti addition (0.010?0.020% Ti) on sulfide-type inclusion morphologies was then investigated for heats having a sulfur content higher than 50 ppm. Addition of Ti was found to have a partial effect on decreasing the size of sulfide-type inclusions under real steelmaking conditions. Keywords Sulfide inclusions, Ca-treatment, titanium.

Jan 1, 2011

By A. O. Filmer

An account is given of a study on the non-oxidative dissolution in aqueous acidic solutions of nickel sulphides of different stoichiometric composition, in which a rotating ring-disc electrode was used. The rate of dissolution was found to depend on the potential of the sulphide and the nickel-to-sulphur stoichiometric ratio. A maximum rate for the dissolution of nickel from nickel sulphides containing an excess of nickel was recorded at potentials around -0,2 to -O,3V. The rate decreased markedly at more anodic potentials. For nickel-deficient nickel sulphides, the nonoxidative dissolution rate increased with a cathodic shift in potential. Under open-circuit conditions, a nickel sulphide of a composition approximating Ni ,S. reacted most rapidly. The dissolution rate was controlled by either a chemical or an electrochemical reaction at the electrode surface, had an activation energy of between 50 and 65 kJ.mol-1, and was independent of stirring speed.

Jan 1, 1980

By L. J. Park, A. D. Thomas

Gladstone Pacific Nickel Limited (GPNL) is proposing to develop the Marlborough nickel deposit in central Queensland and the Yarwun Refinery in Gladstone, Australia. The project proposes to connect the two sites with a DN 500, single pump station slurry pipeline, transporting up to 4 Mtpa of nickel laterite ore as slurry 180 km from Marlborough to Gladstone. Slurry viscosity is a key parameter influencing pipeline design. Not only is the slurry viscosity relatively high, requiring pumping at low concentrations, around 30% by weight, but the viscosity (yield stress and plastic viscosity) increases with shearing or agitation. It is argued that the viscosity changes can be analysed in terms of total energy input, including energy input during grinding. The slurry viscosity is therefore expected to increase along the pipeline and the pumping concentration must be low enough such that the increase in yield stress does not cause transition to laminar flow towards the end of the pipeline. The base viscosity of two ore types is determined using a rotational viscometer for minus 212 micron slurries. Viscosity variations with ore particle sizes of d99 212, 425 and 600microns are investigated. For each of these particle sizes the expected increase in viscosity during pipeline transport is simulated on a laboratory scale by agitation with a turbine mixer in a baffled container to give the same equivalent unit energy input as will occur in the pipeline. Tests were also conducted on the d99425 micron slurry in a 2.7 metre diameter DN 200Wheelstand, rotated for the 23 hour transit time and at a similar relative velocity as in the pipeline. Based on the Wheel stand test results the yield stress is expected to increase by a factor of 3.1during pipeline transit. The preliminary design allows for a reduced pumping concentration to accommodate this increase in yield stress towards the end of the pipeline.

Jan 1, 2007