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By A. D. Pienaar

The aqueous chemistry of niobium and tantalum compounds with hydrofluoric acid is a mature field of investigation. In contrast, very little attention has been paid to reactions of these compounds in non-aqueous environments. Similarly, reactions of elemental fluorine with niobium and tantalum compounds have received little more than cursory attention in literature. This work discusses the isothermal reaction kinetics derived from thermogravimetry, using a less redundant approach than is currently the standard. We also discuss the most likely kinetic models for this reaction.

Jan 1, 2012

By K. Goshtasbi

The mechanical behaviour of schistose sedimentary rocks such as slate show a great amount of anisotropy. Hence, the schistocity plane is essential when investigating the mechanical behaviour of such rocks. The presence of such rocks in civil projects causes non-symmetric deformation and their behaviour is unpredictable. In this research, the anisotropic strength behaviour of slates is studied. Uniaxial and triaxial tests were conducted on specimens having orientation angles (ß) of 0, 30, 45, 60, 75 and 90 degrees. The triaxial tests were done at confining pressures of 3, 5 and 10 MPa. The effect of anisotropy on uniaxial and triaxial strength, cohesion, angle of internal friction and Hoek and Brown's m and s constants were investigated. The results indicate that the strength of slates in uniaxial and triaxial compression exhibit a U-shaped anisotropic behaviour. In-order to evaluate the most suitable criterion for predicting the anisotropic strength of rocks in uniaxial and triaxial compression, an investigation was carried out on various criteria. In uniaxial compression, the Liao and Huong and Ramamurthy criteria had good agreements with the test results. In triaxial compression the Hoek and Brown and Mc Lamore criteria had better agreements with the test results. It should be noted that in-order to utilize these criteria, a large number of tests must be carried out. However, as the Ramamurthy criterion needs fewer test results, it can be the most suitable for investigating the behaviour of anisotropic rocks in triaxial compression. Keywords: Slate, anisotropy, schistose, failure criteria

Jan 1, 2006

By J. J. Swanepoel

Titanium nitride in upgraded nitrided ilmenite (bulk of iron removed) can selectively be chlorinated to produce titanium tetrachloride. Except for iron, most other components present during this low temperature (ca. 200°C) chlorination reaction will not react with chlorine. It is therefore necessary to remove as much iron as possible from the nitrided ilmenite. Hydrochloric acid leaching is a possible process route to remove metallic iron from nitrided ilmenite without excessive dissolution of species like titanium nitride and calcium oxide. Calcium oxide dissolution results in unrecoverable acid consumption. The leachability of nitrided ilmenite in hydrochloric acid was evaluated by determining the dissolution of species like aluminium, calcium, titanium and magnesium in a batch leach reactor for 60 minutes at 90°C under reflux conditions. The hydrochloric acid concentration (11%, 18% and 25%), initial acid-to-iron mole ratio (2:1, 2.5:1 and 3.3:1), and solid-to-liquid mass ratio (1:8.33 to 1:2.13) were varied. The results indicate that a hydrochloric acid concentration of 25 wt% supplied in a 2:1 acid-to-iron mole ratio would produce the most favourable upgraded nitrided ilmenite product. The dissolution of iron in this solution reached 97 per cent after only 60 minutes. The total dissolution of calcium and titanium species was 0.01 and 0.11 wt% respectively. Hydrochloric acid can therefore be used as lixiviant to remove metallic iron from nitrided ilmenite. Keywords Titanium nitride, upgraded nitrided ilmenite, hydrochloric acid leaching, metallic iron dissolution.

Jan 1, 2011

By Godofredo F. Barrios

For years urethane screen surfaces have been used in a wide range of wet screening applications where openings from as fine as 100 microns and coarser have been used. The purpose of this paper is to expose the reader to new developments in both screen surface and screening equipment technologies which allow an end user to consider urethane screen surfaces for fine screening applications. These technologies allow an end user to use the inherent advantages of urethane with regards to wear resistance while also realizing the benefits that a high oper area urethane screen surface can bring. These benefits include non blinding characteristics and feed capacities that which rival that of traditional stainless steel surfaces. The paper will highlight the features of this patented urethane screen surface technology and the screening machines they are used in conjunction with. There will also be a presentation of case studies of commercial installations where these technologies are utilized. These case studies are from the base metals industry therefore relevance to the conference is direct and not inferred. Included in the paper will also be constraints which must be taken into account when considering urethane screen surfaces such as temperature and chemical attacks. This paper will expose potential end users to a possibility of using screens to achieve extremely accurate size separations in applications where screens were previously not considered. The paper will explain and demonstrate that prior concerns of screen surface blinding, high screen surface consumption rates and large screen surface area requirements can be eliminated by proper utilization of high open area urethane screen surfaces.

Jan 1, 2007

The Steering Committee for Minerals and Mining Policy convened two workshops during March 1996 to address the following topics: Business Environment- National and Provincial Powers, Administration and Regulation, Mineral Marketing, Beneficiation, Research and Development, Environmental Issues, Mining Impact on Surface Usage, Southern Africa Regional Issues. Human Resources: Elementary Residual Racism, Housing, Downscaling, Migrant Labour and Human Resource Development. Mineral Tenure: Mineral Rights, System of Access to Mineral Rights, Access to Exploration information, optimal Exploration, Trust Lands. Small-scale Mining. Development of Small-scale Mining, Artisanal Mining.

Jan 1, 1996

By P. Share

As part of JAGUARS (JApanese-German Underground Acoustic emission Research in South Africa), high-resolution tiltmeters were installed during 2007 at Mponeng gold mine, South Africa, in an attempt to study and understand the risks posed by in-mine seismic events and to subsequently use the knowledge gained to mitigate these risks. In December 2007, an M2.2 event occurred at Mponeng and was detected by the tiltmeters installed. The tilt expected for the M2.2 event is modelled through the use of numerical and analytical tools and utilizing, as input parameters, characteristics of the event such as the rupture area, the amount of slip, elastic properties of the rock, the state of stress before the event occurred, and frictional parameters of the rupture. The calculated tilt values are correlated and compared with the recorded data, and are found to be of the same order. Certain input parameters, such as the initial rupture point, are further constrained by varying them, during modelling, until the calculated and observed tilt values are approximately equal. From modelling, it can be concluded that the rupture point had to be closer to the location of the tiltmeters. In addition, possible locations acting as source areas for the observed aftertilt are determined. Further modelling still needs to be done to quantify the effects of the tunnel close to the tiltmeters and plastic deformation of the rock mass. Keywords high-resolution tilt data, Mponeng gold mine, M 2.2 seismic event, analytical modeling, numerical modeling, rupture plane.

Oct 1, 2013

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

For the past 12 years, the Universities of Stellenbosch and Cape Town have hosted an annual symposium to discuss research topics in Minerals Processing. Since 1987, this meeting has been held under the auspices of the Western Cape Branch of the South African Institute of Mining and Metallurgy, and has enjoyed much national and international support. In 1993, in place of the usual Symposium, the Branch and Universities collaborated with CSM Associates Ltd and Minerals Engineering Journal is organizing the international Minerals Engineering '93 Conference in Cape Town.

Jan 1, 1993

By G. Wu, S. Liu

In view of the singleness of traditional methods about international petroleum (Brant) price forecast, ten main factors that affect international petroleum price are fully analysed. Based on time series method and multivariate linear regression method, the simulation model with the theory and idea of system simulation is firstly established. And this forecasting system realizes visual operation under the environment of MATLAB/SIMULINK. So this article tries a new way for further exploring petroleum price’s running law and guiding its forecasting practice. Keywords: Petroleum price forecast, system simulation, residual error, physical flows information flows

Jan 1, 2003

Mineral sand beneficiation plants comprise a complex combination of electrostatic, magnetic and gravity based separation techniques. These are combined and replicated in ways that provide the most efficient and cost effective separation of the valuable components. On line instrumentation has been developed at the JKMRC (eg. conductor/non-conductor(CNC) ) to measure the properties of the dry plant process streams. This paper provides results from the recent development of a novel low cost mass flow meter and discusses their combined use with the CNC instrumentation for the control of dry separation circuits.

Jan 1, 2003

By R. G. Cawthorn

The earliest authenticated scientific report of the occurrence of platinum in rocks from the Bushveld Complex appears to be by William Bettel on 10th November 1906. Thereafter, prospecting of the chromite-rich rocks for platinum proved frustrating. I suggest that the resurgence of interest shown by Dr Hans Merensky in 1924 resulted from his realization that newly-panned platinum had a different grain size from that in the chromite layers and indicated a different source rock, which he located and it became known as the Merensky Reef.

Jan 1, 2006

By J. Gummer, M. Williams, S. J. Hawksworth

A common problem encountered in British coal mines is bearing failure on conveyor system idler rollers, which on occasions has led to fires. The UK Mines Inspectorate initiated a study of such failures to assess the potential for ignition of explosive atmospheres. As part of this study HSL have developed a system to measure the temperatures generated within the bearings during controlled failure. Temperatures are measured using both infrared thermal imaging and contact thermometry. The work to date has shown that temperatures well in excess of the auto-ignition temperature of methane can occur.

Jan 1, 2003

By R. P. H. Willis

For technology transfer to be successful a process, from research to full scale application, has to be followed. This paper describes such a process and how it is applied in practice. Some of the ?do?s? and ?don?ts? are highlighted. Recommendations are made on how to communicate existing knowledge and to ensure that a framework exists to effectively plan future projects with final technology transfer objectives firmly in place. The Impact Ripper System is used as a case study to illustrate lessons learned. Key words: Technology transfer, implementation

Jan 1, 2002

By T. Proietti, L. Mongiovì, L. Simeoni

Reliable estimates of the kinematic characteristics of movements are obtained by using a statistical model SSM. This model represents a useful tool for the management of alert and alarm systems. L'élaboration des données du déplacement médian d'un modèle statistique SSM opportun fournit des estimations fiables des caractéristiques cinématiques du mouvement. Le modèle peut être ainsi utilisé pour la gestion des systèmes d'alarme. Die Bearbeitung von Bewegungsdaten anhand eines geeigneten statistischen Modell SSM ergibt vertrauliche Abschätzungen der kinematischen Eigenschaften der Bewegung. Das Modell kann also für das Management von Alarmsystemen verwendet werden.

Jan 1, 2003

The practice of pumping gases which inhibit combustion for purposes of controlling or extinguishing mine fires is now universally accepted. The practice has been used many times in coal mines in India and the experiences are reviewed. The procedures relating to a membrane based nitrogen generator and to a combustion gases generator are described. The physical properties, practical requirements and economic implications of using different gases is briefly reviewed. Some aspects of the practice as related to mine fires in certain collieries in other countries are dealt with.

Jan 1, 2000

The following are available from Metal Bulletin Books Ltd, Park House, Park Terrace, Worcester Park, Surrey KT4 7HY, England. . World aluminium-a Metal Bulletin databook. 2nd ed. 1990. £71.50 surface, £76.50 airmail. This is a compendium of information listing salient details of companies mining bauxite and producing alumina, primary aluminium, secondary ingot, master alloys, and semi-fabricated products; aluminium trading companies; and a memoranda section listing associations, brand names, and other useful information. It is a userfriendly international reference book for aluminium buyers, traders, and producers.

Jan 1, 1991

By A. N. Brown

Professor D. G. Krige, of the Department of Mining Engineering of the University of the Witwatersrand, received the degree of Doctor of Engineering (honoris causa) from the University of Pretoria at the Autumn Graduation Ceremony in April 1981. He was honoured an outstanding engineer for his world-renowned pioneering work in the field of statistical methods of ore valuation, or geostatistics as it has become known. Metalliferous Ore Deposits A short course on the 'Evolution of Metalliferous Ore Deposits' will be held at Rhodes University, Grahamstown, from 8th to 13th February, 1982.

Jan 1, 1981

By P. W. J. van Rensburg

The Institute was privileged to receive an invitation from the Armaments Corporation of South Africa (Armscor) for members to visit one of their plants. As these are factories, the number of visitors who could be accommodated was limited. As the opportunity seldom arises to learn something of this very large industry, there was great interest among members and many were disappointed in not being able to go. Underwater mining The 16th Annual Underwater Mining Institute will be held at Halifax, Nova Scotia, Canada, from 20th to 23rd October, 1985.

Jan 1, 1985

By A. A. Bradley, P. J. D. Lloyd, A. J. Freemantle

Developments in centrifugal milling by A. A. BRADLEY,B.Sc. (Rhodes) (Visitor), A. J. FREEMANTLE, B.Sc. Hons. (Wits) (Visitor), and P. J. D. LLOYD, B.Sc. (Chem. Eng.), Ph.D. (Cape) (Fellow) The theoretical and experimental results of a study of centrifugalmills are reviewed. Means for the scaling up of such mills are suggested, and tests on a prototype mill are described. Despite the high lining wear in the centrifugal machine, which reduces its productive availability, its other advantages suggest that there is merit in pursuing its further development.

Jan 6, 1974

By H. C. Voges

The use of heavy-medium separation in the processing of iron ores by H. C. VOGES. B.Sc. (Visitor) The paper discusses various aspects of the application of heavy-medium separation to the processing of hematite ore at Sishen and Thabazimbi. The two main factors to be borne in mind in the design of a plant for such beneficiation are the Iow unit value of the iron ore produced and the high separation densities required. The four factors of importance in the avoidance of high viscosity in the ferrosilicon medium are discussed in turn.

Jan 6, 1975