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By R. G. B. Pickering, B. Ebner

The hard rock gold and platinum mines in South Africa have seen little development in the technology of mining. Holes are still drilled in the rock—though the latest water hydraulic rockdrills will complete that task in two minutes compared with the eight hours for hand drilling. Charging up is with far safer explosives and with available initiation systems it is no longer necessary to run up the face lighting each fuse. Movement of rock in the stope is predominantly by means of scraper buckets and scraper winches — these were first introduced in the 1920s.Support is still mainly rock, either in sit pillars or backfill, or alternatively wood. Just as themining process has changed very little it is hardly surprising that the productivity of mining is also relatively unchanged. Major efforts have been made to mechanize the mining process. However, most of the narrow reef mines where ‘trackless mechanized mining’ was introduced in the early 1980s have reverted to conventional mining. In the wider reefs mechanized mining is the option of choice, unfortunately most of the gold and platinum mines have very narrow reefs that are not suitable to’ off the shelf’ equipment. The move to introduce room-and-pillar mining into the narrow UG2reefs is at the expense of mining more waste with the reef, fortunately it appears that appropriate waste and reef separation processes are available. Room-and-pillar mining followed by long holedrilling and blasting of a narrow slot of reef out of the pillars currently appears to offer the best of both worlds—maximum reef recovery with minimum waste dilution. All these mining methods are still dependent on blasting to break the rock. The cyclic nature of mining by blasting places severe constraints on the rate of face advance that can be achieved and consequently the utilization of the invested capital. For narrow reef hard rock mining to break out of these constraints and to really make progress in the 21st century it is necessary to follow the lead of the soft rock mining industry and change the technology of mining. In the underground coal mining industry, coal cutting has been proved to be the most cost-effective solution. In narrow reef hard rock mining the future must be based on the development of non-explosive methods of rock breaking that in turn are integrated into continuous mining systems. Non-explosive so that the mining operation can be conducted on a continuous basis, with nodelays for the removal of blasting fumes. Continuous mining also maximizes the return on the capital invested in developing the mine. Rock cutting will define the stope width and that in turn will be designed to minimize waste dilution; it will also minimize damage to the hanging and create a safer environment. Mechanization makes it possible to automate the mining process and further improve safety by positioning the operators in a safer environment. This paper defines the work to evaluate cutting processes carried out by Sandvik TamrockVoest Alpine. The evaluation was in the UG2 and the pyroxenite and norite typical of the Merensky Platinum Reefs. A novel form of mining machine is proposed that will utilize existing technology. Finally the paper describes the interaction between Sandvik Tamrock Voest Alpineand Lonmin Platinum and the initiation of an agreement to develop and trial a prototype hard rock narrow reef mining machine.

Sep 1, 2001

R. C. J. Goode (President): South Africa is known for its sunshine and mineral deposits-especially its gold and its diamonds-and as this year marks the 75th Anniversary of the establishment of the South African Institute of Mining and Metallurgy, it is appropriate that I say a few words about mining and metallurgy and the part this industry and our Institute has played in the life of this country. Africa, as the Dark Continent, with its fascinating tales of Prester John, Ophir, Queen of Sheba and its myths and legends has throughout the ages fired the public imagination. Pharaoh Necho, 600 years before the birth of Christ, sent an expedition from Egypt around the Cape to probe this strange land. The gold for King Solomon's throne was said to come from Monomotapa-the country now known as Rhodesia. Centuries later the Arabs and Portuguese searched for this mineral wealth. The Arabs found little gold but unfortunately established a lucrative trade in black slaves. Now let us take a brief look into the closing stages of the Stone Age when the indigenous population of the lower portion of this continent consisted of the Bushmen, a nomadic hunting people who knew no metals and kept no stock, and the Hottentots who were a pastoral folk with cattle and sheep. Then somewhere about the 11th century the Bantu started their long migration southwards and brought with them the knowledge of smelting of iron ore. One of their settlements was here in Johannesburg on the Melville Kopje at Emmarentia. These people were the first miners and metallurgists on the Witwatersrand and the beautifully preserved iron smelting furnace constructed nearly 1,000 years ago is a tribute to their technical ability. This ability to use iron to make better spears for hunting or to fashion hoes for cultivating the soil led to their establishment as a superior tribe. The earlier Bushmen were pushed back to the inhospitable swamps and deserts and the Hottentots fled to the south. The Bantu also knew the art of copper smelting. In the days of the Dutch East India Company, at the end of the seventeenth century, Bantu workers brought copper from the north-west Cape to Simon van der Stel, but it was another two hundred years before the white man turned this to advantage. Stories of the Bantu mining gold spurred the early European hunters to travel deeper into the heart of Africa in search of wealth, and we are told that Karel Kruger, in 1834 whilst leading an ivory hunting expedition, discovered gold on the Witwatersrand, and took samples to Cape Town; but when he returned with a larger expedition a few years later his party was attacked by Moselekatze's Matabele near Potchefstroom. Kruger was killed and only the legend survived. The real spur to mining in this country was the discovery of diamonds in Griqualand West in 1867. The field seemed fabulously rich and diggers flocked to the scene from the four corners of the earth. With them came Cecil Rhodes, Barnato, Beit and some of the finest mining and financial brains the country had yet seen. These giant entrepreneurs were not tempted by the small deposits of gold in the Barberton and Pilgrim's Rest areas when these were made a few years later but

By A. F. Lee

Dr E. C. Hanekom (Visitor): Two years ago we used the bubble pick-up technique as developed at Anglo American Corporation for screening candidate flotation agents prepared in our laboratories. It was obviously necessary to know to what extent the technique gave reproducible results and a statistical evaluation of the test method was made using a mineral sample provided by Anglo American Corporation. A bubble of 2.0 mm diameter was used and the measuring graticule was divided into squares (units) with sides of 5.0 mm at 25 X magnification. The mineral granules had diameters from 53 to 74 mm. The bubble was loaded by depressing it against a layer of mineral grains to give an arbitrary but constant compression of 0.4-0.5 mm. It was rolled five times through 2 mm horizontal displacement. The bubble was then lifted, its load compacted by gently stirring and the projected area measured in squares (units) on the grid. Each substance was tested at 5 ppm concentration in distilled water at five points in the pH range 3-6. With these standardized conditions of operation the reproducibility of the test was studied. Four materials were tested and at each pH value the procedure of forming a bubble, picking up granules and counting the units was repeated ten times. From these results the standard deviation for a single count at any pH value was calculated for each material (Table 1. The coefficient of variation of approximately 3 per cent was relatively low and it was decided that further refinements in the counting procedure would be of doubtful benefit with the present apparatus. Similar experiments were carried out with 12 sample materials. In this case the bubble formation and pick-up were repeated four times at each pH value, the mean value was calculated for each set of four observations and final pick-up values for the materials were obtained by selecting the highest mean count. Each test was completely repeated a number of times as indicated in Table 2 and the standard deviation calculated. The results allowed the selection of the more promising materials and the rejection of poor performers at the 95 per cent confidence level. All tests were carried out by one operator. Some evidence was obtained that the method is sensitive to operator bias. In conclusion it can be said that from all the results analyzed it would appear that once operation conditions are fixed (viz operator, pH control) the precision of the method is adequate. The author wishes to thank Messrs African Explosives and Chemical Industries Limited for permission to publish these data. G. S. Stander and C. J. Kooij (Visitors): We must congratulate Mr Lee for this most interesting and useful development of the pick-up experimental method. It certainly provides research workers with an instrument which makes flotation more of a science and less of an art. We visited Mr Lee at his laboratory where he gave us a demonstration of the bubble pick-up instrument and technique as developed and improved by him.

Jan 12, 1969

Dr T. F. Muller (Honorary President): "Mr President, gentlemen. May I congratulate the Institute on its 75th birthday, and your President on his comprehensive review of the Institute's 75 years. It is an interesting commentary on the affairs of the Institute that your President should refer to a speech made by a founder member 25 years ago on the occasion of your 50th Anniversary and then say there is no need to repeat what was given there, but that he would confine his remarks to bringing the Institute's history up to date. To me this suggests a remarkable continuity of thought and ideals-a welcome island of stability in an ever-changing world. One can somehow picture another future President, perhaps one of the younger and tougher members here today, doing the same thing in 25 years when you celebrate your centenary-and again someone doing the same in the year 2094 when your Institute is 200 years old! I hope they will recognise their debt to the early pioneers of the Institute gathered here today. In any event, this review of the fine achievements of the past 75 years is certain of an honoured place in the annals of the society. Here is a record of the onward march of technology in South Africa and a tribute to a long line of mining engineers, of chemists, metallurgists and geologists who made a greater contribution to the well-being and the prosperity of South Africans than South Africans generally are aware. Your Institute started off as a 'gold and cyanide club', peopled largely by chemists and metallurgists who made a signal contribution to the industry from the earliest times. Despite the addition to their ranks of ever-growing numbers of mining engineers, the metallurgist members have continued to make notable contributions. One recalls, for example, the manner in which they rose to the occasion to resolve the problems associated with the establishment of the uranium industry in this country. The creation of a major industry based on the existence of low grade uranium ores in the conglomerate reefs of our low grade goldfields is a classic example of the manner in which a new large industry can be rapidly created through the combined endeavours of all concerned. I noted with pleasure your remark, Mr President, that members of the Institute would like to keep up to date with recent progress in nuclear fuel matters and that members should be given the opportunity to study developments in their journal. I am sure that the National Institute of Metallurgy which conducts fuel research on behalf of the Atomic Energy Board and of the Uranium industry, and NUFCOR, which co-ordinates the uranium research programme, would be glad to co-operate if invited by the Institute to make periodical contributions to its journal. You have referred to the building up of our research organization and its dynamic approach to mining problems. I understand that the expenditure of the mineral industries on research exceeds one-third of the entire research expenditure of the private sector. South Africa is in the forefront of mining development and the focus of world attention is on the achievements of our scientists and mining engineers. We can look forward to continued advances in mining technology based on their vision and expertise. I share your disappointment, Mr President, that the Base Metals Division has ceased to exist; and that there is a resultant dearth of papers offered to the Institute on these important sections of mining and metallurgy. We are seeing some remarkable developments in the mining and beneficiation of base minerals, and it is in this area that I see the greatest potential for future expansion. If we can grasp the opportunities

A Seminar to discuss 'Reactivity of Line in Steel Making' was held in the auditorium of Iscor's Headquarters Building in Pretoria on the 5th August, 1971. The Institute organised this Seminar on the occasion of the visit of Dr Obst of the Rheinische Kalkstein Werke GMBH, Wuelfrath, West Germany. The latter is one of the largest lime companies in the world and Dr Obst is in charge of their research laboratory. He and his co-workers have earned a reputation for their research into reactivity of lime in steel making. This work is also of great importance to the steel industry in this country, particularly with the changes which are occurring with the introduction of basic oxygen furnaces. Some 80 persons representing most of the major steel companies attended this Seminar. Dr Obst presented his most interesting paper which he illustrated with projector slides. This paper is printed in full in this journal. This was followed by several contributions and active discussions. The first contribution was made by Dr T. B. Beeton of the Research and Development Department, Iscor. He gave a brief summary of the studies on reactive lime carried out at Iscor since 1968. Their work was particularly related to the selection and definition of the various reactivity tests and the correlation of these with plant results. He demonstrated that the DIN methods, particularly the Din (40°) test, gave the best results and reported that good agreement had been reached between Iscor, Highveld and Northern Lime on future test procedures. Mr B. Lowther of The Northern Lime Company then dealt with problems associated with the production of high reactive lime. The rotary kilns at The Northern Lime plant at Lime Acres are particularly suitable for the production of high-reactive lime, because this type of kiln lends itself to accurate control of temperatures and retention times. Several problems, however, exist. Because of the long haul distances and the deterioration of reactive lime by absorption of CO2 and water, high reactive lime is not suitable for most customers. To constantly be changing kiln conditions to produce relatively small quantities of high-reactive lime, therefore, causes problems. Highveld Steel at present is the only company requiring high-reactive lime and a satisfactory product is now being produced at a cost because kiln capacity is reduced and fuel costs are higher. Dr P. R. Jochens, of the National Institute for Metallurgy then submitted data to show how the reactivity of soft burnt reactive lime deteriorated due to long railage hauls. Detailed sampling of trucks had been carried out leaving the lime works and on receipt at Highveld and it was demonstrated that there was deterioration in the top layers of the truck. This top layer protected the balance of the lime which is still in good condition on arrival at Highveld. Exposure to atmosphere by further handling and storage into the bunkers at Highveld, however, resulted in further severe deterioration in the lime reactivity and the lime when finally fed to the Basic Oxygen Furnace is reduced to one third to one quarter of the original reactivity value. The same deterioration does not occur with normal run of kiln lime, which is burnt harder, but still has a satisfactory reactivity for most purposes. Mr A. A. Hejja of the Department of Metallurgy, Witwatersrand University then made a contribution on the metallurgical aspects of the use of lime of different reactivities in the Basic Oxygen Furnace and the effect on desulphurization efficiencies. He gave a wealth of data on actual tests which had been carried out and came up with the surprising conclusion that the deterioration of high-reactive lime due to transport did not have as serious an effect on the efficiency of desulphurization as one would have expected. The efficiency was good provided high-reactive lime in the first instance had been produced, irrespective of whether it had deteriorated thereafter. Poor efficiency was obtained only when the lime in the first instance was produced in an unreactive form. The temperature rise in the Basic Oxygen Furnace also has a definite effect. If lime is introduced when the temperature is too high, soft burnt reactive lime becomes hard burnt and unreactive before it can dissolve in the slag. Use of ferromanganese slag assists dissolution of lime. There was a great deal of discussion following these contributions. Particular interest was expres8ed in the special lime described by Dr Obst. This consists of a mixture of fine lime which is premixed with fluxes and either briquetted or pelletised. The question of injecting finely ground lime as an alternative was also discussed. Both these systems eliminate the necessity for highly reactive lime. With smaller lime particles, larger surfaces are exposed thereby ensuring more rapid dissolution in the molten slag. The discussions generally were lively and informative and all present derived benefit from learning of the experiences of others. The valuable contribution made by our German visitor, Dr Obst, was particularly appreciated. The instantaneous English-German translation service which was provided, greatly facilitated discussions.

By R. R. M. Cousens, W. S. Garrett

Discussion: L. T. Campbell Pitt: When Mr Garrett and I discussed the design and construction of plugs and bulk head doors to resist great water pressures in mines about ten years ago, we visualized an emeregeny when there would be no time for site preparation. We could not however, anticipate a problem of such magnitude and urgency as the one described in the paper under discussion. The paper very clearly describes the flooding and the measures taken to save the mine. The complete flooding would have been a national disaster. The account of the combat between man and water reads like the account of a military operation. It was an endeavour which achieved success because there was a master plan, tenacity and, in fact, heroism. The paper is of necessity a long one. In my contribution I will mention some historical facts and factors that I believe have relevance to the flooding and the saving of the mine. It is of great satisfaction to me to have been one of the two initiators of a new approach to underground plug design and construction. The investigation was taken over by a Chamber of Mines Committee which combined our early work with further research and the resulting data had a significant bearing on the West Drie emergency plug designs. The final plug length was correctly based on the requirements to obviate leakage. A plug to have structural strength only would have been very much shorter but so ineffective as to have become a waste of labour, material, and in consequence, wasted the limited time available to prevent flooding of the whole mine. The figure of 75 lb per sq in. sheer stress provided a very ample margin, in my opinion, but under the very difficult site conditions and the limitations of plug material suitable for the very unusual construction, justified such a figure. There must have been considerable temptation to reduce the safety margin due to the urgency to complete and commission the plugs, but it is much to the credit of the directors of this operation that nothing less than a safe design was permitted. In about 1945 Blyvooruitzicht Gold Mining Company, which was then mining in to the West Driefontein area to assist in early development, decided to protect themselves from a possible inrush of water from the latter mine. A bulk head door was accordingly designed and installed on 2 level between 1945 and 1948 at 4,218 ft below surface. Since West Driefontein paid for it, Gold Fields consulting mechanical engineers collaborated with their colleagues of Rand Mines who completed their design after a few modifications were agreed. This door was never used to prevent an inrush into Blyvooruitzicht but the exercise was very useful to Gold Fields when the high pressure doors initially installed on 10 and 12 levels between Nos. 2 and 3 shafts to enable isolation of one section of the mine from another were designed. At that time the capacity of West Driefontein to cope with an inrush of water was comparatively small because the storage in stoped areas and the installed pump capacity were much less than in later years. These doors together with others of the same design were later moved to the lower levels served by sub vertical shafts. In addition, doors to prevent flood water entering the pump chambers on 18 level were installed at each end of that level, and designed for a head of 360 feet so that water would have to reach 16 level before the pumps were flooded. All these doors were called upon to hold water and it is reported that only a small plug in one of the doors and a 4 in. dia flanged pipe joint failed. The lesson is that in these cases the smallest details warrant as much attention as the major ones. That these were the only equipment failures when so much depended on equipment, is very much to the credit of design engineers, both of the Gold Fields head office and companies who supplied both mechanical and electrical equipment. Until I had read the paper I wondered why the policy of isolation by bulk head doors was not continued as the development moved eastward towards the Bank Compartment and particularly when it pierced the Bank dyke. The reasons have been given in the paper. It was unreasonable to expect provisions to be made to counter the remote contingency that the large installed pumping capacity and mine capacity to store water would be exceeded during a peak inrush. When pumps were being considered for West Driefontein, it was decided that the Gold Fields standard underground main pumps at that time of 1 million gallons per 24 hours would be too small. Three alternatives were considered. 1. Very large units that would require underground sub assembly and dismantling of both pump and motor. 2. The largest pump and motor that could be conveyed as a complete pump or motor from surface to the pump chamber. 3. Pumps of higher speed to reduce dimensions and weight. It was decided to adopt alternate 2 because of avoidance of transporting pumps in parts and assembling underground. Alternative 3 was not favoured because high speeds would have introduced problems of more exact rotor balancing. I believe the decision was correct and in the crisis enabled comparative easy transport of pumps and motors to surface for overhaul and, if required, transfer to other pump stations. The standard pump thus became a 10 stage 1,500 rpm pump with a capacity of approximately 2 million gallons per 24 hours against a static head that varied

Jan 3, 1969

By More-O&apos, R. C. Ferrall, J. W. Wilson

Discussion: M. D. G. Salamon* (Fellow): The theoretical principles behind the techniques of calculation used by the authors was formulated and published during the period 1962- 65. These principles, together with their practical implications, were summarized in a review paper in 1966.1 Now, in February, 1970, we have this long and comprehensive paper discussing the practical application of the theory. I think this is good progress. The large number of practical examples treated in the paper clearly demonstrates not only the skill and knowledge of the authors, but also the versatility of the techniques of analysis. I feel that the techniques described by the authors, and their improved versions, will revolutionize mine planning. I suggest that no shaft system or stoping layout should be planned in future without an adequate rock mechanics analysis. It seems that it will be progressively more difficult to white wash mistakes in rock mechanics and attribute their costly outcome to normal mining risk. We should not, however, become complacent. There is still a lot to learn and do in the future. I do not want to discuss tonight the question of further research but instead, I will raise two other problems which may hinder the future progress of practical rock mechanics. To carry out work similar to that described in the paper, mine managements require men who are capable of doing the work and who have the most efficient techniques of analysis at their disposal. As a research engineer I have been associated with the development of techniques of analysis. I can assure you that these have undergone an amazingly rapid development during the last six years. We have seen the change from the use of the electrolytic tank analogue and manual integration to the method described by the authors, that is, to the employment of the automatic network analogue and computer integration. But this is not the end. In a recent paper Prof R. P. Plewman2 and his co-authors described a completely digital technique. Here the process of calculating on- and off-reef quantities is integrated into one computer run. But these sophisticated methods of computation are useless without men to make intelligent use of them. During the last few years a new breed of mining engineers has appeared on the scene - the Rock Mechanics Engineer. I feel it is timely to call the attention of the senior members of this Institute to the fact that this new breed will succeed in carrying out its duties in a valuable manner only if we manage to attract to its ranks young engineers of the right quality. The requirements are high. The top rock mechanics engineers have to be good mine planners and they have to understand the essence of sophisticated theories. Without these attributes they will not succeed in the long term and the industry will not gain the benefit of available knowledge. To attract this quality of engineers the industry will have to ensure that rock mechanics is accepted by all concerned as a career which could lead to the top echelons of our profession. Finally, I would like to make one or two remarks concerning Part I of the paper. In Sections 3.1 and 3.2 the authors describe methods of determining the normal stress on the reef plane and the convergence distribution in the excavations. The description as given applies only to a horizontal reef. When the reef is inclined the situation is more complex since a shear component of stress on the intact reef and a ride component in the excavations must then also be determined. These can be calculated by methods similar to that described in the paper.3 The practical application of the method of calculating the released energy (Section 3.4) is in the comparison of various stoping layouts to establish an order of preference in terms of decreasing rates of energy release. To carry out these comparisons effectively, the calculations must be carried out in a manner by which the values of energy per unit area obtained are comparable. I would like to note in this respect that the method of calculation given in the paper is valid without reservation only if there is no elastic contact between the hanging and foot walls in the mined-out area. If there is contact then the calculated energy values are correct only if the mined out area is increased in small steps during the analysis. My second point in this regard is concerned with the practical method of calculation as described in Sections 3.4 (ii)-(iii). Firstly, I would like to suggest that the energy calculation should be carried out, as far as possible, by using always the same scale on the analogue. Secondly, the reading of current on a pin should be followed by the removal of that pin to obtain the corresponding reading of potential. The product of these two values will be proportional to the energy released during the mining of the small area corresponding to that pin. The method suggested by the authors tends to mask possible danger points in the layouts, since they obtain an average value for a time period, say, for six months.

I appreciate the honour that has been bestowed upon me by my election as President of this Institute. We are starting what I believe will be a challenging year. The first challenge facing the Institute is financial. From the accounts for you will note that the Institute operated at a loss for the first time since 1987. average membership subscription was increased by only 10 per cent, reflecting desire to keep costs down in the minerals industry. The Institute will therefore to rely on other income to meet its budget requirements and break even financially. source of these funds will be the activities of the Technical Programme Committees. disciplines-Mining, Extraction Metallurgy, and Metals Technology are planning programmes for the coming year. I urge al members to increase their support of colloquia schools. Increased membership would also bring in more funds. Please, therefore, encourage colleagues who are not yet members of the Institute to join it.

Jan 1, 1991

By S. M. Graham, G. Mellis

"The determination of the oxidation state(s) of an element present in a solid sample may be required for a number of reasons, including the assessment of the degree of reduction which has taken place during a multi-step production of a metal. In addition, possible flaws in a metal may result from small amounts of oxides included in the solid. The analyte of interest may be present as a major component of a sample of interest, or as a minor impurity - beneficial or requiring removal - in another matrix.Numerous methods have been established for the analysis of species in solution samples - for example, Fe2+ and Fe3+ by titration, Cr6+ by colourimetric means, etc. With appropriate knowledge of the solution being analysed, many of these methods are fairly straightforward, extremely reproducible and accurate. In those instances where the analyte in a solution is known to be in only one form, the analysis is even more straightforward, since it can be achieved instrumentally (by AAS, rCP-OES or rCP-MS, for example).However, the situation with respect to the analysis of solids is not as simple. Various techniques - such as X-ray diffraction - are routinely used by our mineralogists to obtain information about the various minerals present in solid samples, and thus about the oxidation states of the analyte elements present. However, these techniques usually give results that are qualitative, or semi-quantitative at best. They are also usually time-consuming and expensive. One of our colleagues at Mintek, Deshenthree Chetty, has done extensive work in developing a method for the quantification of manganese species in solids using mineralogical methods, and this is no small achievement."

Jan 1, 2014

By L. Marais

The development of a post-mining economy is generally framed as accessible and desirable and something that mining companies, consultants, and the government can, and should, plan for. It is indeed possible. Yet, most mining regions, other than the big metropolitan municipalities, find economic diversification after mining challenging, despite their grand plans, consultant reports, and company intentions. Their efforts blind them to other ideas that are often prerequisites to diversification. This paper highlights some economic and social misconceptions about economic diversification and explains where planning goes wrong. Mistakes typically stem from ignorance and misunderstandings. Planners and policy makers fail to grasp the essential requirements for economic diversification. They underestimate the structural constraints created by mining. They do not see how mine rehabilitation is linked to economic diversification. They generally do not understand the South African space economy or the nature of new economies. The paper also proposes a more careful consideration of those economic aspects that mining cities have control over, such as land use management and infrastructure. The paper further explains how understanding long-term dependencies can help prevent governance failures. The social disruption that accompanies mine decline and closure must be recognised and dealt with. The mines must plan for decline as a way to resuscitate the economy. It concludes with a framework for assessing and developing a post-mining economy.

Apr 25, 2025

By M. Krasowska, W. Skinner, R. K. Asamoah

Understanding chemical interactions at solid-liquid interfaces have played a pivotal role in improving mineral flotation performance, increasing the rate of mineral crystallisation and profitable leaching of valued minerals and metals. This paper highlights gold leaching with links to surface and interfacial chemical processes occurring, and opportunities to maximise extraction while reducing usage of more recent scarce resources. From the review, there is a significant link between surface and interfacial processes and gold leaching performance. Evidently, gold leaching kinetics could be increased by changing leaching conditions, including manipulating the surface and interfacial interactions. Control of surface and interfaces during gold extraction could enhance rapid, smarter gold extraction and mitigate formation of passivation layers. Keywords: Surface and interfaces, refractory ores and concentrates, gold leaching, reaction mechanism and kinetics

Jan 1, 2020

"Chairman: Dr N. G. W. Cook Rapporteur: Mr M. P. RobertsPapers:Planning open pit mining operations using simulation by A. Bauer and P. N. Calder Simulation for control of underground liquid flow by G. N. Pitts and P. B. CrawfordEvaluation of production strategies in a group of copper mines by linear programming by P. H. Williams, J. N. Brooke and D. M. PoulterAn equipment maintenance system by D. W. Dean and J. A. RyderTaken as a whole, the difference between the four papers in this session were perhaps more illuminating than their similarities. The titles of the first and second papers contained the word 'simulation', and in both papers random number generation was relied upon in the selection of inputs from empirical distributions, but the nature of the models to which these values were inputs were quite different. The third paper displayed another method of uniting the empirical and the theoretical in a linear programming formulation whose matrix coefficients were measured empirically, and here some apt remarks on computer implementation were included. This paved the way for the last paper which abandoned all theoretical pretensions in favour of a detailed description of computer implementation and perhaps as a result gave rise to the most feeling audience participation.The systems mentioned were developed for the iron, petrol, copper and gold producing industries in the US, Canada, Zambia and South Africa..As with all the parallel sessions, contributions from the floor may have been limited by the shorter time available to delegates to acquaint themselves with the papers before the session. In spite of this, and due largely to the active chairman¬ship of Dr Cook, the discussion during the session which is summarized here contributed much to the information contained in the papers themselves.In his presentation, Dr Calder summarized his paper. He expected that simulation would be used in future on an almost universal basis in open pit mining. It could contribute new knowledge more cheaply than experimentation in the flea For example, this study had shown what was previously thought to be a matter of more shovels and trucks was really a blasting problem, and improving blasting had increased production to the desired level. The simulation had shown that uniformity of truck performance was a desirable factor. It had also been used to study the advisability of a dispatching system.Dr Ramani contended that where equipment characteristics were available, deterministic standard simulation could adequately simulate systems in which interference occurred. Operator performance could be measured against perfor¬mance curves predicted by standard simulation and poor operators spotted and retrained. The present system did not take into account variability in truck loading, for instance. Dr Calder replied that if the number of variables was large, the standard approach became too complicated for operating personnel to follow. He admitted he had not tried it. The variability of truck loading could be coped with easily using the Monte Carlo approach. Operator variability was already incorporated because the time studies are actual."

Jan 1, 2014

By S R Grano

A fundamental model, which considers the subprocesses of particle collection by bubbles in flotation, is applied to two comprehensive flotation surveys in the rougher stages of C3 concentrator, PT Freeport Indonesia. The flotation surveys focused on the collection of: ? cell-by-cell and size-by-size metallurgical, ? cell hydrodynamic, and ? pulp and surface chemistry information. The two surveys were conducted at significantly different feed tonnages, giving rise to significantly different feed particle size distributions, pulp densities and mean pulp residence times. A series of model simulations are performed with the aim of quantifying changes in copper recovery, on both a size-by-size and unsized basis, with changes in values of the hydrodynamic parameters and hydrophobicity of the copper sulfide mineral. This was carried out in an effort to identify the most promising route to increase overall copper recovery in roughing. It was found that by increasing the hydrophobicity of the copper sulfide mineral surfaces it became possible to optimise cell hydrodynamics, which targeted increased fine (-12 µm) copper sulfide mineral recovery but without adversely affecting coarse (+150 µm) copper sulfide mineral recovery.

Jan 1, 2007

By G. D. Schena

The issue of evaluating the economic impact of large mineral projects in developing countries was studied by the use of econometric models. The evaluating system is demonstrated by its application to an example from Namibia. Three-dimensional graphics are used to illustrate the procedures leading to an assessment of the economic effects of the mineral development. The analysis allows the assessment of the overall economic consequences of mineral developments where there is a need to incorporate in the evaluation issues that are broader in scope than the pure financial objectives. Sets of technical coefficients are exploited for the development of input-output models of the productive structure of an economy. The models are refined to incorporate country-specific behaviours. The increased flexibility of the enhanced semi-input-output model permits a more confident investigation of the economy wide effects associated with a new project in the mineral sector of a developing country. Synthetic measures of profitability at market and shadow prices are introduced, and the cost/benefit ratio is used to rank mineral projects according to their economic profitability. The cost is the capital mobilized for the development of the project and for increasing the productive capacity of the related satellite industries. The benefits are identified with the economy-wide increase in value added induced by the project. 80th costs and benefits are initially valued at market prices. Their ratio is likely to be an index of economic profitability superior to measures that concentrate exclusively on the benefit side of projects. To allow for market distortions, the concept of shadow prices is introduced, and accordingly project-related costs and benefits are re-evaluated. A new cost/benefit ratio at shadow prices is recalculated, which is more meaningful to the policy-maker than decision-making based on socio-economic issues.

Jan 1, 1993

The 101 st Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 12th August, 1998.

Jan 1, 1985

Arthur Robert Owen Wiliams died on 18th May, 1989, at the age of 84. ARO, as he was known, was educated at Malvern in England, and graduated from the Royal School of Mines in 1926. He went to South Africa as a Learner Miner with Consolidated Gold Fields at Robinson Deep.

Jan 1, 1989

The authors and Iscor's management are to be congratulated on an interesting and detailed paper that discloses Iscor's philosophy, strategy, and action concerning what can also be termed productivity improvement. Aside from the pioneering work of Beeforth and Dicks regarding Dynamic Profitability Analysis at Vaal Reefs, there appears to be a shortage of papers on this topic from the mining groups.

Jan 1, 1990

The 93rd Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Highveld Room of the Carlton Hotel in Johannesburg on Wednesday, 15th August, 1990. Obituaries The President announced the deaths of the following Members of the Institute:

Jan 1, 1990

By J. A. Drummond

The duties and efficiencies of a number of main and auxiliary fans were determined by standard and thermal methods. Some observations on the effect of water and dirt accumulation on fan performance were made.

By D. I. Hoyer, M. F. Dawson

The results obtained from the operation of a batch centrifugal ball mill are reported, together with the development of a model for the behaviour of a particle in free flight within the mill, and the introduction of a cumulative breakage rate function. Schumann and Rosin-Rammler plots show the change in particle-size distribution with time at various configurations of the mill. Graphs showing the rate of production of fines and the rate of breakage of coarse particles are included.

Jan 1, 1982