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By H. E. James

During the past ten years there has been an upsurge of interest in the development of selective ion exchange resins and solvents, and of ion-exchange and solvent extraction equipment tailored to the special requirements of mineral-processing circuits. It is therefore not surprising that the recent Symposium on Ion Exchange and Solvent Extraction in Mineral Processing, held at the National Institute for Metallurgy (NIM) on 7th and 8th February, 1980, was a resounding success. This Symposium, organized jointly by NIM. Ion exchange and solvent extraction The Symposium on Ion Exchange and Solvent Extraction in Mineral Processing, which was organized jointly by the National Institute for Metallurgy, the South African Institution of Chemical Engineers, and the South African Institute of Mining and Metallurgy, was held in Randburg on 7th and 8th February, 1980. Analytical chemistry The Fifth International Conference on Analytical Chemistry, organized by the Chemical Society, is to be held at Lancaster University, England, from 20th to 26th July, 1980. Coal mining The First International Symposium on Thick and Steep Seam Coal Mining will be held in London from 18th to 21st May, 1980. Mineral processing The XIV International Mineral Processing Congress will be held in Toronto from 10th to 16th October, 1982. The theme of the congress will be 'Worldwide industrial application of mineral processing technology'. Sessions will be held on the following:

Jan 1, 1980

By M. D. G. Salamon

If a transition from one equilibrium state to another occurs during the course of mining, energy transfer takes place in the rock mass, which is assumed to be an elastic continuum. The energy components are defined as follows: the work done by external and body forces, W; the increase in stored energy in the mass, Uc; the strain energy in the rock mined during the transition, Urn; the work done on mine support or backfill, Ws; and the released energy, Wr. The energy balance is defined as (W + Urn) - (Uc + Ws) = Wr> 0, where the first set of components in parentheses represents the sources of energy, while that of the second corresponds to the known modes of energy expenditure and the component on the right is the unaccounted-for energy surplus, which must be released and dissipated in some form. The inequality Wr ~ Urn> 0 applies. Expressions for the energy components are derived first for the general case and then for the 'slit' modal used to simulate tabular excavations. Through specific examples, the importance of the progressive nature of mining is emphasized. The size of the steps used to enlarge the excavations appears to play a significant role in the mode of energy transfer. This observation forms the basis of the second paper in this series of two papers.

Jan 1, 1984

By Paul Fouche

The past decade has seen a tremendous revival of the base metal industry in Africa, coupled with an unprecedented increase in the prices of base metal commodities in the last couple of years. The theme of the 4th Southern African Base Metal Conference, is therefore, ?Africa?s base metals resurgence?. This conference will explore the contributions made by the mining and metallurgical disciplines to the base metals industry in Africa. It will also investigate how the base metals industry in Africa can capture the maximum potential from the increase in base metal prices through research, innovative thinking, new ways of operating and project implementation. The conference will also consider the influence of Europe?s REACH programme on the base metal industry in Southern Africa. The conference will include a technical visit to Rössing Mine (Uranium) and will be followed by technical visits to Ongopolo (copper), Skorpion Mine (zinc) and Rosh Pinah Zinc Corporation(zinc and lead). The conference, to be held in Swakopmund, Namibia, also confirms the commitment of the Southern African Institute of Mining and Metallurgy (SAIMM), to hosting a regular forum on base metals in the Southern African region. Swakopmund is an ideal conference venue for local and international mining and metallurgical professionals to be exposed to the latest advances in exploration, resource evaluation, projects and technological advances in Southern Africa?s base metal industry. The organising committee is looking forward to your participation at the conference in July 2007.

Jan 1, 2007

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 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 S. Budavari

The effects of shaft pillars left in deep-level hard-rock mines during the extraction of tabular deposits were studied some time ago, resulting in the formulation of design principles and procedures, which have been used with success in the design of shaft pillars in the deep-level gold mines of South Africa. The method has not yet been utilized in the design of shaft pillars in shallow and moderately deep hard-rock mines. The purpose of the present study was to remedy the situation since a great number of deposits are worked at those depths. The object of this paper is to present governing equations for the components of stress and differential movement as derived by use of an elastic model. The pillar is taken to be circular in the plane of a horizontal deposit. On the basis of the numerical results obtained, a study was made of the distribution of the vertical strain and tilt along the axis of the shaft, and of the vertical stress along the shaft and across the pillar. In every case investigated, the most adverse geometry was taken into consideration. By use of an empirical criterion and the results of some in situ observations, the determination of pillar dimensions and differential displacement components for South African gold-mining conditions is demonstrated. Pillar dimensions for shallow and moderate depths are compared with those accepted for deep-level conditions.

Jan 1, 1986

Traditionally, the term `total system' design applied to comminution conjures images of a design that addresses the usual business and operational drivers, including health, safety and environment (HSE), capital cost, operating cost, throughput and product size. In terms of the physical process, the mine to customer type studies also exemplifies an approach that satisfies a normal `total systems' approach. As an industry there are drivers that are forcing a re-consideration of what we regard as our total system. This modification of drivers will require changes in approach and implementation to provide the best solutions. Some of the major changes that impact the drivers are shortage of skilled personnel, changing social attitudes to remote mine site work, greenhouse gas emissions (GHGE), quality of available orebodies and geographical location of new mine sites. One approach to the challenges presented by the changing business environment is to expand the system envelope around comminution to ensure that comminution, in its widest sense, helps to meet the new realities. Background to the new drivers and constraints is provided and some of the appropriate responses are examined in relation to the impact on the total system.

Jan 1, 2007

It is shown that, when a flat-bottomed indentor is pressed into the surface of a strong rock, the normal force necessary to cause failure of the rock is reduced substantially if a shear force is applied to the indentor. A mathematical analysis is described, which shows that higher stresses are induced in an elastic material close to the free surface of the material ahead of a punch when a shear force together with a normal force is applied to the punch. Therefore, failure of the material would occur with lower forces applied to the punch. Stress trajectories show that fractures develop in the rock along lines of maximum principal stresses.

Jan 1, 1978

By A. J. Jager, J. A. Ryder, M. U. Ozbay

This paper deals with procedures used for designing pillar systems in hard-rock tabular mines operating at shallow depths, typically less than 1000 m. A comprehensive review if current practice identifies four types if pillars, namely non-yield, yield, crush and barrier pillars, and the main principles for designing these pillars are outlined. It is shown that the current design methods for pillar systems in South Africa are mainly empirical, each mine developing its pillar-design methods based largely on practical experience. This results in varying pillar layouts, even between neighbouring mines, despite similarities in geology, and depth if mining. It is suggested that some current layouts may fall short if being the best as regards safety, the maximum safe extraction percentages, or flexibility in accommodating future mining scenarios in deeper or otherwise different geological conditions.

Jan 1, 1995

By F. H. Deist, H. D. Small, J. D. Austin, L. F. Duvel

The development and application of a Computer System to aid in the planning of production in mines By F. H. Deist, L. F. Duvel, J. D. Austin, H. D. Small A computer system to aid in the planning of production in mines and its application to a complex colliery are descrIbed, The system consists of three phases, the data base maintenance program the 'production simulator' and the report generation facility, In the first part of the paper the categories of information kept on the data base and the functions of the simulator are described in general terms. The application of the system to a multi-product colliery operating a variety of mining methods in a number of superimposed seams is described m the second part. In conclusion some comments are made on further applications and intended future developments.

Project evaluation is completed through individual studies covering technical and financial aspects of the mine to market. These studies are completed at various levels of detail depending on where the project evaluation is in the project's life cycle. The competency of the studies varies in relation to the quality of data, level of the skills employed, control, management and reporting structure. The focus of this paper is managing elements of the study, looking at the cost of opportunity to influence the project, against the value added. Selection of the study manager and study teams is central to getting an integrated project evaluation addressing the correct issues completed on time. Retention of key personnel can reduce rework which, in turn, can reduce time and cost impacts. It is important to have a work breakdown structure at the outset so that the study teams have a common numbering and naming system that will integrate areas, equipment, budgets estimates and accounts. Having set up the evaluation groups and provided training in the study procedures, understanding the scope and schedule are vital elements in producing a project evaluation that addresses the opportunities and the risks of the final project. Arriving at an accurate capital budget requires integration of the research controlled through common systems. Project evaluation process must also address how the project is to be delivered.

Jan 1, 2007

By J. M. Musadaidzwa

Skorpion Zinc is located 25 km north-west of the small settlement of Rosh Pinah in southern Namibia. Commissioned in early 2003, Skorpion Zinc became the first mine-to-metal operation to commercially apply a purely hydrometallurgical process route to exploit a zinc oxide orebody. The novel technology, known as The Modified ZincexTM Process patented by Tecnicas Reunidas, comprises sulphuric acid atmospheric leaching, zinc solvent extraction (SX) and electrowinning (EW) to produce London metal exchange (LME) Special high grade (SHG) zinc. Forming the core of the process, the SX step has thrived in its role as a barrier to impurities and also in the upgrading of the pregnant liquor solution (PLS), converting it into a loaded electrolyte (LE) sufficiently rich and pure for EW. Against this successful run, a number of challenges have, however, been encountered in SX due the emergence of upset conditions largely emanating from upstream processes. This paper outlines some of the major deviations that have beset the SX process in its first five years of continuous operation. Impurity excursions, temperature depressions, changes in phase continuity, excess aqueous entrainment, the effect of colloidal silica and the accumulation of rare earth elements on the organic phase will be discussed in detail. Keywords: skorpion zinc, solvent extraction, the Modified ZincexTM Process (MZP) DE2HPA, aqueous entrainment (AE), loaded electrolyte (LE), standard liquid validation (SLV) test, organic continuity, aqueous continuity (AC), electrowinning, colloidal silica, phase disengagement time (PDT), rare earth elements (REE).

Jan 1, 2009

By N. Brown

Australian mining companies are actively exploring for and developing mineral deposits throughout the world with interests in emerging markets such as Africa, Asia and South America. It is important to understand emerging market risk as this will affect the willingness of mining companies and financial institutions to invest in a country, especially with reference to their key asset, the mining licence or operating/concession agreement. Mining companies looking to develop new projects in emerging markets have different risk profiles than projects in countries such as Australia and Canada. Examples of key risks faced in emerging markets include: 1. political - expropriation, nationalisation, contract frustration, currency inconvertibility, war, terrorism, strikes, riots and civil commotion; and 2. legal - mining legislation, arbitration and dispute resolution, trade agreements. There is a problem in the difference in risk perceptions between mining companies, financial institutions and insurers. This can cause different stakeholders to carry out different evaluations of the risks faced by a project, resulting in confusion about the risk margin attached to any project. In a time where resource nationalisation and energy security are prompting governments to become more involved in the mining sector we run through some recent examples of mining companies that have had problems due to the key risks highlighted earlier. Importance of carrying out the right due diligence to replace perceptions with reality: ? early identification of risks - detailed due diligence on emerging market risks that may arise will help with their identification and mitigation, ? make use of companies that can help identify risks and suggest solutions, ? control the cost of financing - risk margin applied to a project ? finance loan will be influenced by the risks faced, and ? risk management and using political risk insurance. There are plenty of opportunities in emerging markets but it is important to recognise the associated risks. Detailed due diligence at an early stage will provide long-term benefits.

Jan 1, 2007

By P. R. Jochens

South Africa depends to a considerable measure on the exploitation of mineral reserves and the processing of these minerals. One of the prime requirements for the mining and metallurgical industry to continue in this vital role is access to sufficient energy in a suitable form. Hence, four important questions are discussed: Does South Africa have sufficient energy for the processing of its minerals and metals! Will the cost of energy allow South Africa's minerals and metals to compete on world markets? Can mining and metallurgical processes become more energy-efficiency Can mining and metallurgical processes be adapted to the various forms of energy that may have to be utilized in the future? It is concluded that about 26 per cent of the extractable reserves of coal would be required in the mining and processing of 50 per cent of South Africa's reserves of gold, platinum-group metals, copper, iron, ferrochromium, and ferromanganese. However, the reducing agents required exceed the extractable reserves but not the total estimates of mineable in situ resources of metallurgical coal and anthracitic coal. Even under the severe constraint that coal could become virtually the sole source of energy, only about three-quarters of the extractable reserves of coal would have been consumed by the year 2025. The reasonably assured resources of uranium metal that can be recovered at less than $80 per kilogram are considerable and, at current conversion efficiencies to electricity, are equivalent to one-fifth of the extractable reserves of coal. The rate of exportation of energy in the form of U30. was about five times that of coal in 1978. It is pointed out that the price of energy has a direct effect on the competitiveness of metals, and, although constituting only a small proportion of the selling price of precious metals, it represents a significant proportion of the selling price of copper and metals recovered from oxide ores. The scope for the conservation of energy appears to be greater in the extraction and conversion of primary energy-carriers to electrical energy than in other mining or metallurgical fields. Provided that alternative sources of energy can be converted to electrical energy, they can be applied to the mining and metallurgical industries. The decision as to which type of energy should be used in specific mining and metallurgical situations is complicated, and is likely to be subjected to closer scrutiny than in the past. The hope is expressed that the tentative conclusions reached will give rise to more-quantitative analyses from those qualified to undertake such an exercise. Inevitably, the questions asked at the outset give rise to more questions, and the more interesting ones are posed in the context of each conclusion.

Jan 1, 1980

The first annual student prizegiving function of the South African Institute of Mining and Metallurgy was held in the Dorothy Susskind Auditorium, University of the Witwatersrand, on Thursday, 26th May, 1977. The address (see opposite page) was given by Dr M. G. Atmore, a director of Anglo American Corporation and Vice-President of the Institute.

Jan 1, 1977

By I. R. M. Chaston

A full and detailed description is given of the dense-medium cyclone plants used in Africa for the recovery of diamonds.

John Keith Elers Douglas recently retired from active participation in the activities of the South African Institute of Mining and Metallurgy after over forty years of diligent and valuable service to the Institute. This account of his contributions to the mineral industry and associated organizations is presented as a tribute to all his hard work and dedication. Mineral processing The Fourteenth International Mineral Processing Congress, sponsored by the Canadian Institute of Mining and Metallurgy, is to be held in Toronto from 22nd to 27th October, 1982. The theme of the meeting is 'Worldwide industrial application of mineral technology'.

Jan 1, 1981

By H. E. Cross

The conversion of a uranium plant to the recovery of zinc by H. E. CROSS. B.Sc. (Eng.)(Hons.) Rand (Fellow) The conversion of the Vogelstruisbult Uranium Plant into a plant for the production of electrolytic zinc is described. The reasons for the conversion, the preliminary investigations. and the basic design principles are all outlined, and a brief account is given of operating experience.. during the commissioning of the plant, with equipment that had been put to a use for which it was not originally Intended.

Jan 11, 1973

By P. C. van Aswegen

The Schools A school on 'Measurement, Process Control and Optimization in the Minerals Industry', organized by The South African Institute of Mining and Metallurgy, was presented twice by course leader Dr Ken Garner, ably assisted by the staff of the Measurement and Control Division of Mintek. The first school was held from 16th to 20th July, 1984, at the University of the Witwatersrand, and the second from 11th to 15th February, 1985, at Mintek. Project development The Sydney Branch of the Australasian Institute of Mining and Metallurgy will hold a second Project Development Symposium in Sydney between 7th and 10th October, 1986. This second symposium will extend the range of topics covered by its predecessor in 1983 to emphasize planning (including strategic planning), construction, and project commissioning.

Jan 1, 1985

By A. G. W. Knock

Logistic curves are used in the prediction of the primary production of tin metal from estimated worldwide resources. Such curves are asymptotic to the total cumulative reserves, which are a function of prevailing metal prices and total resources. The figures for tin resources are based on the findings of Robertson and of Brobst and Pratt, the latter authors including estimates of undiscovered deposits. It is suggested that tin production will slump from the present level to 100000 long tons per annum by the end of the century, but will reach a new peak of 200 000 long tons some thirty years later. It appears that production will never exceed 300000 long tons per annum unless substantial new resources, excluding those predicted, are discovered.

Jan 1, 1979