Search Documents

By M. F. Dawson, S. B. Davis

SYNOPSIS This paper describes the size reduction of limestone smaller than 1 mm by attrition grinding, using quartz (1 to 3 mm) as the grinding medium in a laboratory rig. The ore and grinding medium were closely sized fractions, and the particle size of the grinding medium was at least three sizes larger than that of the ore. Batch tests showed that the size reduction of the feed followed two first-order rate processes: one for an apparently fast-breaking ore fraction, and a slower one for most of the ore (86 per cent). The production of fines (material smaller than 10 µm) followed a zero-order rate equation. Continuous runs showed that the process could be modelled as a perfectly mixed system provided that the discharge screen did not selectively retain coarser particles of ore. The ratio of medium to ore (both by mass and by volume) was found to have a significant effect, the most energy¬efficient grinding occurring at ratios between 1 and 2. The solids content of the slurry also had a significant effect, the greatest efficiency being obtained at 50 to 65 per cent solids (by mass). Within these energy-efficient ranges of medium-to-ore and solids content, the lower values resulted in maximum feed breakage and the higher values in maximum fines production. The most important factor in the breakage of feed was the difference in the particle size of the grinding medium and the ore; the amount of ore broken out of the feed size for a given energy input was found to increase linearly with the difference between the size of the grinding medium and that of the ore up to 2 mm. The production of fines increased similarly, but only up to a difference of about 1,2 mm, when it levelled off at about 5 kg/kW ? h. The mechanism proposed for attritioning is mainly the abrasion of 1 µm planes of limestone along the crystal axes, with some fracturing along existing lines of weakness. The energy consumption of nearly 200 kW ? h per ton of product smaller than 10 µm appears to be higher than that in other types of milling. It is concluded that the value of attrition milling lies in its selectivity; in this work, only the softer limestone and virtually none of the hard quartz grinding medium was comminuted.

Jan 1, 1989

By A. A. Oakes, P. M. C. Wilson

This paper describes some aspects of the planning of a new colliery which commenced production in the Middleburg district in 1966. An account is given of some of the problems encountered in the early years of operation and of what was done to solve them. The conclusion is reached that design of plant and machinery should be flexible to permit multiplication of units.

By M. J. King, W. K. B. Loftus, H. S. Simpson

SYNOPSIS The history of the early diamond fields and primitive methods of diamond recovery are traced, giving a brief description of the improvements made in final diamond recovery processes and techniques up to the present day. In particular the emphasis is on the effect of improved equipment in reducing final hand sorting time and labour, better security and greater recovery of fine diamonds.

By H. Wagner

The discovery of the gold-rich Main Reef Group of reefs on the farm Langlaagte in 1886 marked the opening of the richest and most extensive goldfield in history. Mining of the narrow reefs progressed from the outcrops to more than 3,5 km, and has made South Africa the foremost mining country in the world. Changes in the political and socio-economic climate create a new challenge to the gold-mining industry. The most significant of these is the emergence of Black trade unions, with their demands for higher wages, improved safety, job advancement, and abolition of discriminatory legislation. Industrial conflicts on gold mines have risen significantly in the past ten years, and are likely to continue in the future, although the causes of these conflicts may change. Events largely outside the control of the gold-mining industry, such as the improved dollar price for gold and the depreciation of the value of the rand relative to major currencies, have enabled the industry to meet the demands for higher wages and to narrow the wage gap. However, labour productivities have improved insignificantly and are a cause of major concern for the future development of the industry. Continued pressure in the industrial-relations area, the inflation of working costs, and the extension of mining operations to greater depths and more difficult areas create major challenges to mine managements and mining engineers. Significant improvements in mining technology, environmental control, and safety will have to be made to ensure the long-term survival of the industry. The unavoidable introduction in deep gold mines of mechanization on a larger scale to meet the requirements of higher labour productivities and a better and safer underground environment will have a major impact on the cost and management structure of these mines. Engineering will assume a more important role on deep gold mil1es, and management styles and structures will have to be adapted to accommodate these changes. The supply of suitably qualified engineers, technicians, and artisans will be a crucial factor controlling the rate of technological change. The industry is well-geared through its Group system to meet these challenges, and to benefit from the experience gained in the operation of highly mechanized mines. However, changes take time to implement and there is very little time left.

Jan 1, 1986

By M. B. Cortie

An account is given of the development of ferritic stainless steels since their discovery in the early years of this century. The alloys became very widely used in the 1950s, the market during that decade being driven strongly by a demand for automobile trim made of ferritic stainless steel. The production of ferritic stainless steel declined as a proportion of the total at the end of the 1950s as consumer preferences changed. However, the market is now growing strongly again, this time driven by a demand for oxidation-resistant alloys for motor-vehicle exhaust systems. The tonnages produced, applications, and market shares of the various alloys are discussed and compared. Trends in world stainless-steel production, product forms, technological development, and usage are examined.

Jan 1, 1993

The Copperbelt areas of Zambia and the Democratic Republic of Congo (DRC) have recently been seeing the development of a significant number of new projects. Due to the current economic climate, some of these projects have been delayed but the region remains an important resource for copper and cobalt for future years. Many of these projects will utilize an agitation leach followed by solvent extraction and electrowinning to recover both copper and cobalt. The flowsheet route for copper is fairly well established while the processing options for cobalt vary considerably depending on the final product (metal or salt) the operator wishes to make. The mineralogy of ores in the area is typically associated with high gangue acid consumption during the leaching process. This has resulted in acid availability to the area being constrained and acid prices have risen accordingly. Agitation leach circuits, typically, have a tight water balance which needs to be maintained and a bleed of process liquor needs to be continuously removed from the circuit in order to maintain this balance. This bleed, typically, contains fairly high levels of acid and requires neutralization prior to tailings disposal or secondary metal recovery. It is, therefore, desirable to minimize the acid concentration in this bleed stream in order to decrease total acid requirements and neutralization costs for the process plant. An in depth case study by Cognis and Bateman Engineering evaluated three different flowsheets with the aim of determining relative operating costs between the three alternatives, together with differences in plant capital cost requirements.

Jan 1, 2009

By K. Sinding

This paper discusses reasons for mining company mergers that have become the fashion, the role of the ?Juniors? and asks what the motives might really be. It examines changes in company concentration over the last 20 years in key mineral segments. Data at different stages of a project are examined to attempt to elucidate the role of the ?Juniors?. Areas for further research are suggested.

Jan 1, 2009

By Adams. M. D.

Most of the cyanide lost in carbon-In-pulp plants is due to the reaction of cyanide with base metals and sulphides during leaching. Some cyanide is also lost in the adsorption tanks as a result of oxidative and adsorption reactions with the activated carbon. The high rates of cyanide loss in the elution and electrowinning stages are atributable to hydrolytic decomposition and anodic oxidation, respectively. However, the relative amount of cyanide lost during these two stages is small for a given amount of ore treated.

Jan 1, 1990

By B. Rainier

This paper discusses the preparation of material for backfilling operations using hydrocyclones. Aspects dealt with include the advantages and disadvantages, material requirements, process constraints, operating systems and equipment of the backfill plant.

Jan 1, 1988

By R. J. Mostert

The role of hardenability in the development of high-strength low-alloy (HSLA) steels is discussed. The applicability of the superhardenability treatment. a steel making technique for increased hardenability, to HSLA steels is indicated, and the literature on this treatment is reviewed. Several low-carbon superhardenability HSLA steels were designed by use of published superhardenability multiplying factors. It was found that the hardenability of these low-carbon steels can be increased to the same extent as that of medium-carbon steels. The mechanical properties as determined in normalized bars indicate that the superhardenability treatment can be used successfully in the production of low-carbon hot-rolled HSLA steels.

Jan 1, 1984

Colloquium and General Meeting were held at Kelvin House on 19th May, 1971, the theme being 'Modern trends in coal mining practice.' Mr V. C. Robinson (President) was in the Chair. The Colloquium was attended by 205 delegates and was opened by the President at 9 a.m. OBITUARY The President: 'It is my sad duty to announce the death of C. C. Cullen, Fellow, who joined the Institute in 1946 and passed away on 15th March, 1971. As a mark of respect to the memory of the deceased and in sympathy with the bereaved I would ask you all to rise and observe a few moments silence'. ELECTION OF SCRUTINEERS The President: 'In terms of Clause 9.4 of the By-Laws I now call for the nomination of seven Corporate Members to act as scrutineers of the ballot for Council'. Messrs V. C. Robinson, Prof D. D. Howat, Dr J P Hugo, D. G. Maxwell, J. K. E. Douglas, R. J. Adamson and P. Lambooy were nominated by P. W. J. van Rensburg and seconded by P. A. von Wietligh. The President: 'Are there any further nominations? If not I declare these gentlemen elected.' MEMBERSHIP The President: 'I have much pleasure in announcing that the names of 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: Douglas Edward King, Bryan Rudolph Scott, James Gregor Phimister, Anthony David Walters. Graduates: Cornelius Johann Muller, Marthinus Stephanus Mulder. Associates: John George Everson, Colin Robert Llewellyn Davies. Students: Francois George Enslin Beetge, Ewald Boshoff, Christiaan J. Cloete, Christopher John Davies, Cameron George Elvin, Kenneth Eric Field, Johannes Louis Fourie, Hans Gert Gastrow, Peter John Ledger, James Robert William Lindsay, Kynaston Lloyd McDonald, Richard Peter Mohring, Arthur Leslie Painting, Matthias Arthur Pascall, Ian Neil Sinclair, Donald Allan James Ross-Watt. MEMBERS TRANSFERRED TO A HIGHER GRADE From Member to Fellow: Peter Norman Roberts. From Associate to Graduate: Alfred Eric WaIter Fletcher. From Student to Graduate: Wilfried Pierre de Villiers, Edward Emile Eichenberger, William Alan Nairn, Lodewyk Johannes de Jager, Colin Henry Obray, John Grenig Rees. COLLOQUIUM The President opened the proceedings and introduced Mr N. W. S. Schumann as the overall chairman for the day. The following papers and contributions were presented: FIRST SESSION: Chairman R. C. J. GOODE. Paper: 'Problems encountered in the operation of a new colliery' by P. M. C. Wilson and A. A. Oakes. Contributors: D. J. Moloney, G. R. Canny, I. G. Evans, R. B. MacGillivray, Dr F. G. J. de Jager, M. J. Deats, and N. Zolezzi. R. B. MacGillivray Mr President and gentlemen, I would like to congratulate the authors on presenting a most interesting paper on a very important subject. After several attempts at finding suitable reserves to extend the life of Welgedacht Exploration Company's Utrecht Colliery a block of coal rights was acquired south west of the town of Utrecht. A study of these reserves showed that they would enable a satisfactory return on capital invested to be achieved. It was decided therefore to open up what is now called the Zimbutu section of Welgedacht Exploration Company, to produce 41 000 metric tons of coal per month. The decision to open this section was taken in August, 1968 and due to certain allocation requirements it was necessary to bring it into production by the 1st of January, 1970. Fortunately a fair amount of statistical data had been collected prior to August, 1968 from the old Utrecht Colliery in anticipation of opening a mine and a fairly detailed rechnical report had been prepared. As a result the dead line was only missed by four days. Main features of the Design A feasibility study was carried out on three possible shaft positions and the final position was selected from these three on economic grounds. As the coal seam at the selected shaft position was only 21 metres below the surface it was decided to sink two twin incline shafts to enable rapid establishment of through ventilation and alternative hauling arrangements for quick development. This also allowed the final vertical ventilation shaft to be placed at some distance away to avoid the nuisance of fan noise. Second outlet requirements are also very well met by these twin inclines. Again on the basis of economics and also due to the uncertainty of roof conditions it was decided to use hand loading methods underground. However, to allow for future possible conversion to mechanised loading, should this become economical through rising wages, a conveyor belt was installed in the hauling shaft. This conveyor belt is fed from an endless rope haulage in the east companion by means of tipplers, a bin and a feeder. The main development heading was left clear for the future installation of a conveyor belt which would afford easy conversion to mechanisation.

By H. E. James

GOLD 100, the most comprehensive international conference on gold ever held anywhere in the world, took place in Johannesburg from 14th to 18th September, 1986. The Conference was followed by a series of one day visits and an extended technical tour. The Conference was organized jointly by the Council for Mineral Technology (Mintek), the Chamber of Mines of South Africa, the School of Business Leadership of the University of South Africa, and The South African Institute of Mining and Metallurgy.

Jan 1, 1986

A Colloquium and General Meeting was held jointly with the Mine Ventilation Society of S.A. in Kelvin House, Johannesburg, on 17th November, 1971, the theme being "The Economics of Mine Ventilation". Professor D. Howat (President) was in the chair. The Colloquium was attended by 150 delegates and was opened by the President at 9.00 a.m. MEMBERSHIP The President: "I have much pleasure in announcing that the names of the 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: Fellows: Frederich-Wilhelm Volk, Peter Bennet Columbine. Members: Allan Colin Lawrence, Karel Anton van Gessel, Christopher Robert Harrison, Christopher Michael George Wartley, Frank Heinrich Deist, Ralph Morris, Benjamin Johannes Nolte. Associates: Wolf gang Freidrich Gottsman. TRANSFERS From Member to Fellow: Hugh Edward Keith Alien. From Graduate to Member: Errol Vincent Bosman, Christopher Roderick Stewart Needes, Bernard Wessels Holthousen. From Student to Graduate: David Robert Fleming. I welcome the new members to the Institute and congratulate them on their election. CO-OPTION TO COUNCIL The President announced that at the Council meeting held on 5th October, 1971, it was agreed, in terms of Rule 3.9 to co-opt Dr T. B. Beeton to Council. COLLOQUIUM The President welcomed visitors and members. He stressed that the discussion would be informal and that any contributor requiring publication should submit his contribution in writing. He then thanked the authors for providing pre-prints of the papers. After the President had concluded his opening remarks, he asked Professor J. de V. Lambrechts to act as Colloquium Chairman for the day and he, in turn, introduced the three Session Chairmen namely, Dr A. Whillier (Chamber of Mines and President of the Mine Ventilation Society); Mr M. Barcza (Managing Director, Corner House Laboratories); and Mr L. W. P. v.d. Bosch (Chief Consulting Engineer, Union Corporation). The following papers were presented: "Fan efficiency investigation on mines of the Union Corporation, Ltd." by J. A. Drummond. Published in the Journal Feb. 1972. "The design of underground cooling towers" by A. Whilliel'. Published in the Journal, Oct. 1971. "Some aspects of the design of cooling plant installations" by R. Hemp. Published in the Journal, Nov. 1971. "The planning of ventilation and refrigeration requirements in deep mines" by D. F. H. Grave and R. M. Stroh. Published in the Journal, Dec. 1971. "Cooling power of underground environments" by D. Mitchell and A. Whillier. Published in the Journal, Oct. 1971. At the conclusion of the three technical sessions the Symposium Chairman commented as follows, indicating that he would prepare a written summing up at a later stage: "The tone of the colloquium has had a sincerely practical note about it. It would have been a pity if the ventilation experts talked only theory and little practice. This practical theme has, I am sure, made the colloquium interesting to both ventilation men and others whose daily tasks do not touch so closely on this fascinating subject. This practical theme was in evidence through all the papers and contributions. Some of you may have felt that there was not enough emphasis on the word 'economics' as advertised in the broad title of the colloquium. I do not think this was really a valid criticism because as someone said 'it all boils down to Rands in the end!' So whether it was a case of low fan efficiency, poor design of cooling towers, wrong planning or low human efficiency due to high heat stress. . . it all boils down to money saving and therefore economics, whenever improvements are forthcoming. The title of the colloquium was thus not misplaced. The views of senior mining men on the production side are appreciated. Let us say that this exchange of views between ventilation engineers and those who have to take the final decisions and spend the money, should prove to be most rewarding." Professor Lambrechts finally thanked the Session Chairmen and everybody who had helped to make the colloquium a success and the meeting closed at 4.0 p.m. In a subsequent written summing up, the Colloquium Chairman gave the following as his impressions of some of the highlights which emerged from the papers and discussion thereof: (The names indicate the authors only). Drummond: It was hinted that the time had arrived to consider the introduction of a South African fan test code which would be better suited to local conditions than the currently acknowledged B.S.S. code which, however, is seldom enforceable in practice. In this connection also, there was prominent reference to the thermodynamic approach of McPherson. Wide variations in the quality of maintenance of, and repair work on, fans were stressed. It was mooted that ventilation engineers responsible for estimating the basic duty specifications for large fans, frequently played safe by overestimating the pressure required, thus ensuring that there would not be a shortfall in air volume delivered. This usually meant reduced fan efficiency and it was suggested that decision makers seemed to lay more emphasis on volume of air delivered than on real eco-

By G. Nino de Guzman, L. C. Woollacott

The isotherms that are usually taken to represent the force 'driving' the adsorption in carbon-in-pulp processes may change from contactor to contactor. This paper reports on an investigation into the extent to which this Isotherm shift is Influenced by the changes in oxygen and cyanide concentration that occur in operating plants. The impact of the isotherm shift on the reliability of simulation results is examined.

Jan 1, 1993

The Institute was founded in 1894 as the Chemical and Metallurgical Society of South Africa. In 1904 it was reconstituted as the Chemical Metallurgical and Mining Society of South Africa and in 1956 it became the South African Institute of Mining and Metallurgy. The objects of the Institute are to advance the science and practice of mining and metallurgy, to afford opportunities for the interchange and recording of knowledge of mining and metallurgy and to ensure high standards of professional conduct and competence. Membership benefits include monthly issues of the Journal of the Institute, monthly General Meetings at which papers are read, symposia, excursions to mining and industrial concerns and the use of club facilities at Kelvin House. Technical journals received on an exchange basis are available to members at the Johannesburg Public Library. The current membership of the Institute is over 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be not be less than 30 years of age, shall be university graduates in pure or applied science or shall produce evidence to the satisfaction of the Council that they have successfully completed a co-ordinated course of study in pure or applied science of at least three years' duration at an approved university or institution deemed by the Council to be of equivalent status. Members shall have been employed in senior technical positions in important mining or metallurgical undertakings for at least five years or they shall have practised as mining or metallurgical consultants for at least five years. They shall be practising their profession at the time of application. Entrance fee R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.INST.M.M. Associate Members shall be not less than 25 years of age and shall be university graduates in pure or applied science, or shall have successfully completed co-ordinated courses of study in pure or applied science of at least three years' duration. They shall have been engaged in work of an approved technical character in the mining or metallurgical industries, of which not less than two years shall have been in positions of responsibility. A candidate shall be practising his profession at the time of his application. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00 (country). Letters of designation: A.M.S.INST.M.M. Affiliates shall be not less than twenty-five years of age, and shall have been engaged in positions of responsibility in, or associated with, the mining or metallurgical industries for periods of not less than three years. If, however, the candidate for admission to the higher grade of Affiliate, is at the time of his application, already a Student member, he need satisfy the Council only that he is, at the time of his application, engaged in a position of responsibility in or associated with the mining or metallurgical industries. In all cases the applicants shall satisfy the Council that they are fit and proper persons to become Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members shall be not less than 21 years of age and shall be university graduates in pure or applied science, or have completed co-ordinated courses of study in pure or applied science of at least three years' duration at an approved university or institution. They shall not remain Graduate members after attaining the age of 30 years without the persmission of Council. Entrance fee R1.00; Annual subscription R7.00 (town), R6.00 (country). Students shall be persons not less than 18 years of age who are being educated or trained in a manner approved by the Council, to occupy a technical position in or associated with the mining or metallurgical industries and who, furthermore, shall not have attained the qualification required for a higher grade of membership. They may remain Students until they have obtained the necessary qualifications for transfer to a higher grade of membership, but not after the end of the Institute's financial year in which the attain the age of 28 (twenty-eight) years. They shall then transfer to a higher grade to retain membership of the Institute. The Council may relax the provisions of this clause in such cases as it considers appropriate. Entrance fee nil; Annual subscription R3.00 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate Member candidates who may not fulfil all the requirements for entrance to these grades but whose status, professional achievements and practical experience in mining or metallurgy justify such election. Applications. Requests for membership application forms should be addressed to the Secretary: South African Institute of Mining and Metallurgy, p.a. Box 1183, Johannesburg.

The Institute was founded in 1894 as the Chemical and Metallurgical Society of South Africa. In 1904 it was reconstituted as the Chemical Metallurgical and Mining Society of South Africa and in 1956 it became the South African Institute of Mining and Metallurgy. The objects of the Institute are to advance the science and practice of mining and metallurgy, to afford opportunities for the interchange and recording of knowledge of mining and metallurgy and to ensure high standards of professional conduct and competence. Membership benefits include monthly issues of the Journal of the Institute, monthly General Meetings at which papers are read, symposia, excursions to mining and industrial concerns and the use of club facilities at Kelvin House. Technical journals received on an exchange basis are available to members at the Johannesburg Public Library. The current membership of the Institute is over 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be not be less than 30 years of age, shall be university graduates in pure or applied science or shall produce evidence to the satisfaction of the Council that they have successfully completed a co-ordinated course of study in pure or applied science of at least three years' duration at an approved university or institution deemed by the Council to be of equivalent status. Members shall have been employed in senior technical positions in important mining or metallurgical undertakings for at least five years or they shall have practised as mining or metallurgical consultants for at least five years. They shall be practising their profession at the time of application. Entrance fee R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.lNST.M.M. Associate Members shall be not less than 25 years of age and shall be university graduates in pure or applied science, or shall have successfully completed co-ordinated courses of study in pure or applied science of at least three years' duration. They shall have been engaged in work of an approved technical character in the mining or metallurgical industries, of which not less than two years shall have been in positions of responsibility. A candidate shall be practising his profession at the time of his application. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Letters of designation: A.M.S.INST.M.M. Affiliates shall be not less than twenty-five years of age, and shall have been engaged in positions of responsibility in, or associated with, the mining or metallurgical industries for periods of not less than three years. If, however, the candidate for admission to the higher grade of Affiliate, is at the time of his application, already a Student member, he need satisfy the Council only that he is, at the time of his application, engaged in a position of responsibility in or associated with the mining or metallurgical industries. In all cases the applicants shall satisfy the Council that they are fit and proper persons to become Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members shall be not less than 21 years of age and shall be university graduates in pure or applied science, or have completed co-ordinated courses of study in pure or applied science of at least three years' duration at an approved university or institution. They shall not remain Graduate members after attaining the age of 30 years without the persmission of Council. Entrance fee R1.00; Annual subscription R7.00 (town), R6.00 (country). Students shall be persons not less than 18 years of age who are being educated or trained in a manner approved by the Council, to occupy a technical position in or associated with the mining or metallurgical industries and who, furthermore, shall not have attained the qualification required for a higher grade of membership. They may remain Students until they have obtained the necessary qualifications for transfer to a higher grade of membership, but not after the end of the Institute's financial year in which the attain the age of 28 (twenty-eight) years. They shall then transfer to a higher grade to retain membership of the Institute. The Council may relax the provisions of this clause in such cases as it considers appropriate. Entrance fee nil; Annual subscription R3.00 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate Member candidates who may not fulfil all the requirements for entrance to these grades but whose status, professional achievements and practical experience in mining or metallurgy justify such election. Applications. Requests for membership application forms should be addressed to the Secretary: South African Institute of Mining and Metallurgy, P.O. Box 1183, Johannesburg.

The Institute was founded in 1894 as the Chemical and Metallurgical Society of South Africa. In 1904 it was reconstituted as the Chemical Metallurgical and Mining Society of South Africa and in 1956 it became the South African Institute of Mining and Metallurgy. The objects of the Institute are to advance the science and practice of mining and metallurgy, to afford opportunities for the interchange and recording of knowledge of mining and metallurgy and to ensure high standards of professional conduct and competence. Membership benefits include monthly issues of the Journal of the Institute, monthly General Meetings at which papers are read, symposia, excursions to mining and industrial concerns and the use of club facilities at Kelvin House. Technical journals received on an exchange basis are available to members at the Johannesburg Public Library. The current membership of the Institute is over 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be not be less than 30 years of age, shall be university graduates in pure or applied science or shall produce evidence to the satisfaction of the Council that they have successfully completed a co-ordinated course of study in pure or applied science of at least three years' duration at an approved university or institution deemed by the Council to be of equivalent status. Members shall have been employed in senior technical positions in important mining or metallurgical undertakings for at least five years or they shall have practised as mining or metallurgical consultants for at least five years. They shall be practising their profession at the time of application. Entrance fee R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.INST.M.M. Associate Members shall be not less than 25 years of age and shall be university graduates in pure or applied science, or shall have successfully completed co-ordinated courses of study in pure or applied science of at least three years' duration. They shall have been engaged in work of an approved technical character in the mining or metallurgical industries, of which not less than two years shall have been in positions of responsibility. A candidate shall be practising his profession at the time of his application. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Letters of designation: A.M.S.INST.M.M. Affiliates shall be not less than twenty-five years of age, and shall have been engaged in positions of responsibility in, or associated with, the mining or metallurgical industries for periods of not less than three years. If, however, the candidate for admission to the higher grade of Affiliate, is at the time of his application, already a Student member, he need satisfy the Council only that he is, at the time of his application, engaged in a position of responsibility in or associated with the mining or metallurgical industries. In all cases the applicants shall satisfy the Council that they are fit and proper persons to become Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members shall be not less than 21 years of age and shall be university graduates in pure or applied science, or have completed co-ordinated courses of study in pure or applied science of at least three years' duration at an approved university or institution. They shall not remain Graduate members after attaining the age of 30 years without the permission of Council. Entrance fee R1.00; Annual subscription R7.00 (town), R6.00 (country). Students shall be persons not less than 18 years of age who are being educated or trained in a manner approved by the Council, to occupy a technical position in or associated with the mining or metallurgical industries and who, furthermore, shall not have attained the qualification required for a higher grade of membership. They may remain Students until they have obtained the necessary qualifications for transfer to a higher grade of membership, but not after the end of the Institute's financial year in which they attain the age of 28 (twenty-eight) years. They shall then transfer to a higher grade to retain membership of the Institute. The Council may relax the provisions of this clause in such cases as it considers appropriate. Entrance fee nil; Annual subscription R3.00 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate Member candidates who may not fulfil all the requirements for entrance to these grades but whose status, professional achievements and practical experience in mining or metallurgy justify such election. Applications. Requests for membership application forms should be addressed to the Secretary: South African Institute of Mining and Metallurgy, P.D. Box 1183, Johannesburg.

The Institute was founded in 1894 as the Chemical and Metallurgical Society of South Africa. In 1904 it was reconstituted as the Chemical Metallurgical and Mining Society of South Africa and in 1956 it became the South African Institute of Mining and Metallurgy. The objects of the Institute are to advance the science and practice of mining and metallurgy, to afford opportunities for the interchange and recording of knowledge of mining and metallurgy and to ensure high standards of professional conduct and competence. Membership benefits include monthly issues of the Journal of the Institute, monthly General Meetings at which papers are read, symposia, excursions to mining and industrial concerns and the use of club facilities at Kelvin House. Technical journals received on an exchange basis are available to members at the Johannesburg Public Library. The current membership of the Institute is over 1,400. Membership applications are accepted from suitably qualified persons and the requirements for entrance to the various grades of membership are summarised below. Members shall be not be less than 30 years of age, shall be university graduates in pure or applied science or shall produce evidence to the satisfaction of the Council that they have successfully completed a co-ordinated course of study in pure or applied science of at least three years' duration at an approved university or institution deemed by the Council to be of equivalent status. Members shall have been employed in senior technical positions in important mining or metallurgical undertakings for at least five years or they shall have practised as mining or metallurgical consultants for at least five years. They shall be practising their profession at the time of application. Entrance fee R4.00; Annual subscription R14.00 (town), R12.00 (country). Letters of designation: M.S.A.INST.M.M. Associate Members shall be not less than 25 years of age and shall be university graduates in pure or applied science, or shall have successfully completed co-ordinated courses of study in pure or applied science of at least three years' duration. They shall have been engaged in work of an approved technical character in the mining or metallurgical industries, of which not less than two years shall have been in positions of responsibility. A candidate shall be practising his profession at the time of his application. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00 (country). Letters of designation: A.M.S.INST.M.M. Affiliates shall be not less than twenty-five years of age, and shall have been engaged in positions of responsibility in, or associated with, the mining or metallurgical industries for periods of not less than three years. If, however, the candidate for admission to the higher grade of Affiliate, is at the time of his application, already a Student member, he need satisfy the Council only that he is, at the time of his application, engaged in a position of responsibility in or associated with the mining or metallurgical industries. In all cases the applicants shall satisfy the Council that they are fit and proper persons to become Affiliates. Entrance fee R2.00; Annual subscription R12.00 (town), R10.00(country). Graduate Members shall be not less than 21 years of age and shall be university graduates in pure or applied science, or have completed co-ordinated courses of study in pure or applied science of at least three years' duration at an approved university or institution. They shall not remain Graduate members after attaining the age of 30 years without the persmission of Council. Entrance fee Rl.00; Annual subscription R7.00 (town), R6.00 (country). Students shall be persons not less than 18 years of age who are being educated or trained in a manner approved by the Council, to occupy a technical position in or associated with the mining or metallurgical industries and who, furthermore, shall not have attained the qualification required for a higher grade of membership. They may remain Students until they have obtained the necessary qualifications for transfer to a higher grade of membership, but not after the end of the Institute's financial year in which the attain the age of 28 (twenty-eight) years. They shall then transfer to a higher grade to retain membership of the Institute. The Council may relax the provisions of this clause in such cases as it considers appropriate. Entrance fee nil; Annual subscription R3.00 (town), R3.00 (country). Other. The Council has the power to elect to the grade of Member or Associate Member candidates who may not fulfil all the requirements for entrance to these grades but whose status, professional achievements and practical experience in mining or metallurgy justify such election. Applications. Requests for membership application forms should be addressed to the Secretary: South African Institute of Mining and Metallurgy, P.D. Box 1183, Johannesburg.

By M. Mrost

Slimes disposal at South African gold mines by M. MROST*. M.Sc. (Rand) (Fellow) The soil mechanics, civil engineering, and environmental considerations applicable to the construction of slimes dams on the Witwatersrand gold mines are discussed. It is concluded that, though the procedures used in the construction of dam embankments do not accord with the best possible practice, they are entirely adequate in current local circumstances, provided that proper precautions are taken to ensure that the wall foundations are sufficiently permeable and strong, and that the dams are protected against erosion. If current trends towards larger mining and metallurgical complexes continue, it may become necessary to build larger, higher dams, and to adopt slimes embankmentbuilding practices that are inherently more reliable.

Jan 2, 1974

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, August 14th, 1974. Mr P. W. J. van Rensburg (President) was in the Chair. There were present 56 Fellows, 21 Members, 2 Graduates, 5 Associates, 16 Students, and 58 Visitors, making a total of 158. The President declared the Meeting open at 4.08 p.m. OBITUARIES The President: Ladies and gentlemen, before we start the business of the meeting, it is my sad duty to announce the deaths of the following members of the Institute since our last meeting: Dr O. A. E. Jackson, Honorary Life Fellow and Past President; C. Airth, T. L. Blunt, A. E. Frazer, C. L. Lamb, and K. Richardson, Life Fellows; and J. T. Beaumont, Fellow. As you know, there were a number of other deaths during the year, which were reported at previous General Meetings of the Institute. 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: Ladies and gentlemen, the next item on your agenda is confirmation of the minutes of the General Meeting and Special General Meeting held on May 22nd, 1974. These will be published in the August issue of the Journal, and, since you have not yet received this, I must ask that they be held over to the next General Meeting. WELCOME The President: It is a very pleasant duty for me to welcome many members of our Institute and our guests, among whom we are particularly pleased to see the President of the Chamber of Mines, Mr Dolf Schumann, who is also Honorary President of this Institute. Mr Schumann, we are extremely pleased to have you with us today. And, we welcome an old friend of ours, Mr Dillon, Minister of Mines in Rhodesia, who has come down for our Annual General Meeting. Mr Dillon, we are very, very pleased to see you here this evening, and we look forward to seeing Mrs Dillon a little later. And we have with us, too, the presidents or representatives of many of our sister and brother associations, institutes, and societies. In particular, we welcome Mr Mike Gericke, President of the South African Council of Professional Engineers, and Professor Midgley, President of A. S. and T. S. We are also pleased to welcome the Presidents of the Mechanical Engineers, Electrical Engineers, Certificated Mechanical and Electrical Engineers, the Civil Engineers, the Joint Council of Scientific Societies, the Mine Ventilation Society, the South African Association of Consulting Engineers, the Association of Mine Managers, the Institute of Foundrymen, the Institute of Welding, the Federation of Societies of Professional Engineers, Mine Surveyors, Production Engineers (London), and the Institute of Production Engineering. We are very glad, too, to have with us a visitor from England, Professor Raynor and Mrs Raynor. Professor Raynor is Professor of Metallurgy at Birmingham University, and a very well-known metallurgist in Britain. We also have with us the Chairman of the Ferro-Alloys Association. We are expecting the Chairman of our Witbank/Middelburg Branch, the Chairman of the Engineers' Liaison Committee, Pretoria, the Director of the Witwatersrand College of Technical Education, and, of course, our old friend, Mr Eric Boden, the Manager of A.S. and T.S. It is a very great pleasure to have with us a number of persons who will receive honorary Life Fellowship at this meeting, and there are some Gold Medal winners and winners of our Student Prizes. We have apologies from a number of people who are away on business, and unfortunately some are ill. But we are extremely pleased to see those of you who are here, and we are also very pleased to see so many ladies. We expect to see many more of them later this evening, at our Cocktail Party. MEMBERSHIP The President: I have pleasure in announcing that, their names having been published in accordance with By-Law 5.2.2., the following have been elected by Council to membership in the following grades Fellows: B. Collins, D. W. Dixon, J. P. Dreyer, A. T. Hudson, and W. W. Pearce. Members: A. T. Fisher and I. F. Nagy. Associate Members : P. D. de Bruyn and H. C. Iverson. Graduates: D. P. O'Shaugnessy and M. F. Sadler. Associates: R. J. Bushell and A. MacDonald. Students : I. J. Barker, P. J. Charter, J. P. de Witt, G. S. Esterhuizen, N. Green, P. M. Jenner, M. J. R. Meyer, A. P. Nicol, W. J. C. Pothas, B. J. Robbetze, N. T. Sutherland, B. A. Statham, C. R. Thomas, N. C. Webb, M. Salamon, R. G. Jurd, and M. McChesney. Transfers to other grades of membership include the following: Member to Fellow: B. W. Holtzhousen. Graduate to Member: T. S. Schultz. Associate to Associate Member: C. L. Jordaan, H. J. L. Tomlinson, J. E. Forbes, G. H. S. Bamford, T. F. Carswell, J. W. Breidenhann, J. R. Garbutt, and L. S. Gibbs. Student to Graduate: C. J. Faueonnier and B. Lund. Student to Associate : G. P. Gooding. We welcome these new members

Jan 10, 1974