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Caving is the lowest cost underground mining method provided that the draw point spacing, draw point size, and ore-handling facilities are designed to suit the caved material, and that the draw point horizon can be maintained for the life of the draw. In the near future, several open-pit mines that produce more than 50 kt per day will have to examine the feasibility of converting to low-cost, large-scale underground operations. Several other large scale, low-grade underground operations will experience major changes in their mining environments as large dropdowns are implemented These changes demand a more realistic approach to mine planning than in the past, where existing operations have been projected to increased depths with little consideration of the change in mining environment that will occur. As economics force the consideration of underground mining of large, competent ore bodies by low-cost methods, the role of cave mining will have to be defined In the past, caving was generally considered for rockmasses that cave and fragment readily. The ability to define cavability and fragmentation, the availability of large, robust load-haul-dump units, a better understanding of draw-control requirements, improved drilling equipment for secondary blasting, and reliable cost data have shown that competent orebodies with coarse fragmentation can be exploited by cave mining at a much lower cost than by drill-and blast methods.

Jan 1, 1994

Recent advances in the design and performance of flotation equipment A General Meeting and Colloquium on the above topic was held on 12th March, 1975, at Kelvin House, Johannesburg. The Colloquium was attended by 250 delegates and was opened by the Immediate Past President, Mr P. W. J. van Rensburg, at 09h30. Obituary Mr Van Rensburg announced with regret the deaths of James Alfred Boyd, Life Fellow, and Jack Joseph Frankel, Fellow. Training of technicians The Institute has received a letter from The Federation of Societies of Professional Engineers pointing out that there is considerable opportunity for the training of Coloured and Bantu technicians and artisans, and that the existing facilities will be extended as the demand for them increases.

Jan 6, 1975

By I. Wayland

Value added blasting is a process methodology that links tasks and processes, with the aim to improve/enhance the technical application of explosives technology and initiating systems, resulting in improved output. The phases and steps of a typical value added blasting intervention are discussed in this paper. Each step having distinct purposes, principles and methodology. The underlying philosophies and process steps of the programme are described for each step. This paper gives an account of projects that have been completed in two Anglo American Gold Mines. This will include a description of the projects that were conducted at Vaal Reefs 8 Shaft and Western Deep Levels South Mine covering: ? The need for blasting improvements ? The approach that was followed ? The result of the programme.

Jan 1, 1999

By R Kersten

The note describes an exercise on the simulation of the frequency and size of seismic events on the basis of the frequency distribution of the events and their inter-arrival times (Le. the frequency distribution of the time elapsed between events). From the suite of available results, those of one simulation for a period of three months are included. The tentative conclusions drawn from the exercise indicate that the overall seismic activity in an area can be predicted for a time period, that structurally complex areas will have a higher incidence of seismic events than other areas, and that the position and time of an event cannot be predicted by the use of a wide-spread system such as that used at present.

Jan 1, 1985

By S. Visage

By 1984 Iscor's first direct-reduction plant will be operating at the Vanderbijlpark Works, and for the fin;t time the Corporation will have an alternative method to the blast furnace for producing iron from ore. The performance of Iscor's four-kiln plant, which will be the largest coal-based plant in the world producing sponge iron, will undoubtedly be watched with great interest by steelmakers throughout the world. Beneficiation of tin The Southeast Asia Tin Research and Development (SEATRAD) Centre is a regional oganization, formed by the Governments of Indonesia, Malaysia, and Thailand with assistance from the United Nations, to conduct, coordinate, and promote research and training in the various fields of tin production, including geology, prospecting, mining, mineral processing, and smelting.

Jan 1, 1982

By R. G. B. Pickering

The Faculty of Engineering at the University of the Witwatersrand and the Mining Technology Division of the CSIR have co-operated to define the problems associated with deep level mining and in this paper they will identify what they consider to be the critical areas requiring technological solutions. This perspective will then be applied to work currently being carried out by both the organizations and gaps for additional developments will be identified. Finally the Co-operative Research Centre methodology operating in Australia is described. The purpose of this CRC is to provide a vehicle for R&D co-operation to develop and implement technologies which will increase the competitiveness of the mining industry. A further objective is to develop an appropriately skilled human resource base.

Jan 1, 1996

By P. C. Seligmann

Primary fracture from an array of shotholes by c. M. LOWNDS. B.Sc. Hons. (Rhodes). Ph.D. (Cape) (Visitor) and P. C. SELIGMANN. B.Sc. (Witwatersrand) (Visitor) The effects of stress on the directions of cracks that are propagating in a brittle medium are described. It is shown that the superimposition of stress fields from the holes of an array always adversely affects fragmentation. Consequently, the best fragmentation will result when holes are fired far enough apart in space or time for each to develop its whole crack pattern without disturbance from the others. This concept leads to a philosophy for the design of more effective blasting patterns, which has been verified on model scale and which explains many published, empirical results.

Jan 1, 1976

By J. J. Geldenhuys

Premier of the North-West Province, Mr Molefe, foreign dignitaries and guests, ladies and gentlemen. It is a pleasure and also a special honour for me to have been invited here this morning to make this address. The xv Congress of the Council of Mining and Metallurgical Institutions is, by its very nature, an extremely important event for the international minerals industry. But I believe that this specific Congress assumes an even greater significance because of the profound and far-reaching changes that have taken place in South Africa this year. These are exhilarating times, a period when so much in our country has altered and when so much has to be done so quickly to build positively on our bold political decisions.

Jan 1, 1994

By M. T. Scholtz, I. J. Corrans

Akinetic study of the leaching of pentlandite in acidic ferric sulphate solutions by I. J. CORRANS, (Pr. Eng.). B.Sc. (Chem. Eng.) (Wits.). M.Se. (N.S.W.). Ph.D. (Natal) (Member) and M. T. Scholtz. B.Sc. (Chem. Eng.) (C. T.). Ph.D. (Toronto) (Visitor) A study was made of the kinetics in the leaching of nickel from pentlandite in dilute-acidic ferric sulphate solutions as a basis for subsequent studies on bacterial leaching. The chemical leaching rate was found to be highly dependent on the temperature and the concentration of ferric ions. The proposed mechanism for the leaching process is one involving rate control by chemical processes and mass transport. Good agreement was found between the experimental data and the proposed mechanism.

Jan 5, 1976

By M. J. U. T. Van Wijngaarden, R. J. Dippenaar, J. M. A. Geldenhuis

The successful application of solid electrolytes in electrochemical cells for high-temperature thermodynamic studies depends to a large extent on an accurate knowledge of the P. value of the electrolyte (the oxygen partial pressure at which the ionic conductivity and n-type electronic conductivity of the electrolyte are equal). Consequently, the P. value of an electrolyte must be determined prior to its use in electrochemical cells. This paper describes the successful application of a coulometric titration technique in the quantitative assessment of the P. values of a commercially available ytria-stabilized zirconia electrolyte that has been used extensively by local investigators. The experimentally determined P. values of the electrolyte are reported and compared with P. values reported in the literature for a similar electrolyte.

Jan 1, 1988

By P. G. Henderson

Coalbrook Collieries has produced approximately 2 million tons of coal by retreat longwalling since April 1976. Strata control. support. stone intrusions. coal conveyance, and the inflow of goaf and water between the face supports have been the major operational problems experienced to date. The progressive percentage availability of the total system (moves between panels excluded) for the first three panels mined was 40 per cent. Satisfactory solutions have been evolved for these problems. and the availability in the present panel (fourth panel) has increased to approximately 60 per cent. It is envisaged that longwalling will become the most economical method of ensuring optimum heat values, greater recovery. and reduced geographic expansion. as well as safer roof conditions. at Coal brook.

Jan 1, 1980

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 Jean-Claude Paye

In February 1996 the OECD's Environment Policy Committee will commemorate its 25th anniversary with a fifth meeting at Ministerial level. Environment ministers will be taking stock of the progress made by OECD countries in protecting and managing the environment in that quarter-century, and sharing views on likely challenges and co-operative responses. Ministers can point to many important accomplishments. Scientific understanding and technological tools for establishing and monitoring risks to human health and the environment have improved dramatically since the early 1970s. All OECD countries now have in place comprehensive environmental legislation, supported by specialized institutions for policy design, implementation and enforcement. The results of these efforts are increasingly evident in the form of cleaner air and water, and improved protection of natural areas, notwithstanding the many complex problems that remain.

Jan 1, 1996

By P. J. D. Lloyd

The Witwatersrand reefs contain gold, uranium, and pyrite in the following average concentrations: 0,001 per cent, 0,02 per cent, and 1,7 per cent respectively. The paper discusses the flotation of pyrite to produce a s,ulphide concentrate, reviews work done on the production of gold concentrates, discusses attempts to produce maximum concentrates, and closes with a review of processes for the simultaneous flotation of these three species. It is concluded that high recoveries of all three species can be achieved only if a rougher concentrate of perhaps 20 per cent of the feed (by mass) IS produced, and it is suggested that reverse leaching (leaching before cyanidation) of this concentrate, followed by a cleaning flotation step for the recovery of the pyrite, would be more efficient than the routes employed at present.

Jan 1, 1981

By D. A. Viljoen

The ore mined at Black Mountain is of a complex nature, being composed of both magnetic and massive sulphides, which have greatly varying metal values. Because of this, there is need for a rapid method of assaying for the continuous monitoring and control of the process streams, and the Outokompu Courier onstream analysis system and the Proscon process-control computer systems have therefore been installed. Geostatistics In view of the continuing demand, the Department of Mining and Mineral Sciences in association with Special Courses Division, Department of Adult Education and Extramural Studies, both of the University of Leeds, will offer two further courses on A Practical Introduction to Geostatistics in 1981, each covering ten working days. The courses will run from 30th March to 10th April and 14th to 25th September.

Jan 1, 1980

By M. A. von Below, I. C. Robinson

A mineral economic analysis of South Africa's mineral-beneficiation industry, comprising both economic theory and case studies, suggests that the domestic market has proved to be a more effective vehicle for promoting the establishment of advanced beneficiation projects than the availability of domestic raw materials. Although the domestic market plays an important role in the promotion of beneficiation by providing a secure outlet for sales, its most vital role is in the development of technological and marketing know-how that may give South African beneficiated products the competitive advantage required to penetrate export markets. The real wealth of a country lies primarily in the skills of its people rather than in its natural resources, and the domestic market plays a pivotal role in the development of these skills.

Jan 1, 1990

By P. Stevenson

Correlations for the critical velocity needed to hydraulically convey particles in horizontal, or near-horizontal, pipes are either explicitly dependent upon the shear stress imparted by the fluid upon the surface of the particle bed, or require a velocity and hydraulic diameter. Often such approaches are modified to account for pipe inclination by the introduction of simple factors. However, we assert that the physics that underpins the hydraulic conveying of particles in steep pipes (such as a directionally drilled oil well) is dissimilar to that which governs particle behaviour in horizontal pipes. In steeply inclined systems, a sliding sediment induces an upward counter flow and hence an autogenous contribution to the shear rate. The physics underpinning particle hydraulic conveying in steep systems is explored using the separation results of Laskovski et al.10

Jan 1, 2007

By J. A. Ryder

A high proportion of damaging rockbursts are thought to be underlain by seismic events that represent shear or rupture along planes of weakness (faults, joints, dyke contacts). Such events are controlled by shear stresses and friction properties along the plane. Excess shear stress (ESS) is a measure that can be evaluated numerically and that, in principle, can be used in an assessment of the possible magnitude and relative likelihood of seismic activity. Methods for the calculation of ESS in practical mining contexts, and for the estimation of the magnitudes of possible seismic event progressions, are briefly reviewed. The effects of variables such as depth, stoping width and, in particular, virgin horizontal stresses on general shear-type seismic hazards are investigated. Attempted back-analyses of two large rockbursts are described.

Jan 1, 1988

By P. D. K. Robinson

In the second of a series of five colloquia with the theme Rescue 91 ..Survival Initiatives for the Mining Industry, the emphasis was placed on the harnessing of improved technology for the benefit of all the industry. The Colloquium was held at Mintek, Randburg, and attracted some 150 delegates and speakers from a cross-section of the industry. Eight papers were presented, and panel discussions were held to round off the morning and afternoon sessions. The purpose of the Colloquium was to allow mines and other groups to put forward innovative schemes in the management of technology that could be shared by everyone in their determination to ensure the survival of the gold-mining industry in the current difficult times. PAPERS The papers presented were as follows: The introduction of detachable bits at Cooke No. 1 Shaft, by C.A.F. Sweet of Randfontein Estates Survival through cost-saving measures in the engineering field, by E.J. Jurgensen of Freddies Survival through innovation, action, and a positive vision for the future, by G.C.V. Wade of Vaal Reefs Measuring misaligned guides, by H. Sperling of CSIR Rock-crushing innovations, by E. Trueman of Nordberg Improved explosives technology-has it been worth the effort? by RA. Lindsay of Sasol Cost savings through corrosion monitoring, by M. Tullmin of CSIR Enhanced efficiencies through technical developments in the survey departments, by D. Maree of Beatrix.

Jan 1, 1992

To the members of The South African Institute of Mining and Metallurgy I have audited the annual financial statements of The South African Institute of Mining and Metallurgy set out on pages 641 to 644 for the year ended 30 June 2006. These annual financial statements are the responsibility of the Institute?s Council members. My responsibility is to express an opinion on these annual financial statements based on my audit. Scope I conducted my audit in accordance with International Standards on Auditing. Those standards require that I plan and perform the audit to obtain reasonable assurance about whether the annual financial statements are free of material misstatement. An audit includes: ?examining, on a test basis, evidence supporting the amounts and disclosures in the annual financial statements, ?assessing the accounting policies used and significant estimates made by management, and ?evaluating the overall financial statement presentation. I believe that my audit provides a reasonable basis for my opinion. Audit opinion In my opinion, the annual financial statements present fairly, in all material respects, the financial position of the Institute at 30 June 2006 and the results of its operations and cash flows for the year then ended in accordance with generally accepted accounting practice appropriate to the Institute. Supplementary information The supplementary schedule does not form part of the annual financial statements and is presented as additional information. I have not audited this schedule and accordingly do not express an opinion on it.

Jan 1, 2006