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By G. R. Drennan, N. J. Wagner, M. J. T. Sebola

The Soutpansberg Coalfield hosts South Africa's hard coking coal reserves. However, coals in this region are understudied compared to other coalfields in the country. This study characterizes the properties of fine-float fraction samples extracted from a wide diameter borehole core in the Makhado Project, Tshipise sub-basin, Soutpansberg coalfield. Conventional analyses were used to determine the coal quality, petrographic composition, mineralogy, geochemistry (including trace element and rare earth element composition), and free swelling index of samples from six coal horizons and three partings from the economic No.6 Seam. The coal samples are classified as medium rank bituminous C coals (0.88 %RoVmr, 0.92 %Rmax) and are highly vitrinitic in composition (97 vol% mineral matter free (mmf)). The samples show strong caking potential (FSI of 9). The total rare earth concentrations range between 570 and 3193 ppm in the ash samples. Preliminary analysis show all but two samples are promising sources of rare earth elements as the total concentrations exceeded the 1000 ppm cut-off grade. Further research is required to confirm these preliminary findings.

Aug 2, 2022

By D. Krebs, Tero Korhonen, X. Yang, A. Kirpala, N. Heino

At present, over 85% of the world’s rare earth oxides are produced from the bastnäsite ores, found mainly in China. Meanwhile, the ion adsorption ores are the most important sources for heavy rare earth production. As the demand for rare earth materials in the world increases, other forms of rare earth deposits will become new potential resources of rare earth production in the future. In this paper, flotation performance of a steenstrupine ore from the Kvanefjeld deposit for rare earth recovery was studied through laboratory bench testwork. The effects of various factors including grinding size and collector dosage on recovery and selectivity of the selected rare earth elements, La, Ce and Y, were investigated. A rare earth concentrate with the grades of La 2.8 wt%, Ce 5.1 wt% and Y 1.0 wt% at recoveries of 80.5% La, 79.8% Ce and 55.3% Y was obtained in optimum conditions. Further potential to improve the efficiency of REE flotation was discussed. Keywords: Rare earth elements, flotation, steenstrupine, Kvanefjeld deposit

Jan 1, 2020

By Y. G. Zhu, G. B. Zheng, X. X. Hu

Reverse flotation by cationic collectors is the classical method to reduce the silicon content in magnesite. But because of the low selectivity, there is a large loss of magnesite in the reverse flotation froth. To improve the efficiency of the collector, a novel collector named BK433 was developed in this paper. In order to determine the performance of the BK433 collector, a systematic experimental study was carried out with a high silicon magnesite in China. The suitable pH environment of slurry was confirmed, the depression effect of different depressants was investigated, and the flotation effect was compared with commonly used traditional collectors. The results show that the BK433 shows remarkable good selectivity and collection ability. After the 4 stages reverse flotation, the SiO2 content decreased from 3.76% to 0.25%, SiO2 impurity removal rate reached 94.69%. Meanwhile, the MgO content increased from 45.06% to 46.73%，the recovery of obtained concentrate (calculated by MgO) was 82.79%. Keywords: Magnesite, Desilicication, Reverse flotation, Collector

Jan 1, 2020

By Pekka Taskinen

Advanced optimizing control of the fluidised bed zinc roaster has been in use for an extended period at Boliden Kokkola and the implications are seen as extended bed stability, increased throughput and far better on-line availability. The roaster furnace control system developed is based on a dynamic and predictive furnace model, with parameters determined experimentally at the site. The controller maximises the concentrate feed and keeps the furnace operational parameters inside limits given by raw material mix and equipment constraints. The products of a zinc roaster, calcine, sulphur dioxide and the side products, such as mercury, meet gradually more stringent requirements, in particular as to their assays and total recoveries in the process chain. The end users of sulphuric acid in northern Europe, among others in the pulp and paper industry, require mercury levels much less than the conventional 0.2-0.4 ppm Hg. Therefore, secondary de-mercurising circuits have been used over the last five years for further cleaning the SO2 stream allowing production acid grades with less than 0.08 ppm Hg.

Jan 1, 2008

By R. Romano, E. Montalar, J. B. Serón

The SMR geomechanics classification system (adaptation of RMR for slopes) is reviewed with data from 87 actual slopes in Valencia. In a research project, SMR has been applied by a GIS system, as a method to forecast stability problems in future road construction. As a result of this work a methodology for GIS application has been developed. On revient sur la classification geomechanique SMR ( une adaptation du RMR pour talus et pentes) avec les dates de 87 talus existant autour de Valencia. Dans le cadre d’un projet de recherche SMR a été appliquée, avec un système GIS, comme méthode de prévision de stabilité problèmes dans la construction de futures routes. Une méthodologie pour l’application du GIS a été développe. Das Geomechanische Einteilungssystem SMR (eine Anpassung des RMR an Böschungen) wird an Hand der Daten von 87 Böschungen im Gebiet von Valencia überdacht. In einem Forschungsprojekt wurde das SMR in einem Geographischen Informationssystem (GIS) als Methode zur Vorhersage von Stabilitätsproblemen bei zukünftigen Straßenbauprojekten eingesetzt. Das Ergebnis dieser Arbeit ist die Entwicklung einer Methodologie für die GIS-Anwendung

Jan 1, 2003

By O. I. Ostrovski, D. K. Belashchenko

The aim of this paper is the construction of models of systems with ionic and ionic-covalent bonds (molten salts) using experimental diffraction data and the calculation of their structure and thermodynamic and transport properties. Modelling was performed using algorithm BELION, in which the non-coulomb part of interaction potential between ions in the model was determined by the method of iterative simulation which targeted agreement between calculated and experimental partial pair correlation functions (PPCFs). The ionic charges in salts, which can be fractional, were determined by minimization of internal energy. In this paper, the algorithm BELION is applied for chlorides of alkaline-earth metals. Pair potentials, PPCFs, atomization energies, self-diffusion coefficients and electric conductivity are calculated. The charge of alkaline-earth metals was in the range of 2.0-2.1, slightly increasing from Mg to Ba. Partial pair correlation functions and atomization energies of models agree well with experimental data for MgCl2, SrCl2and BaCl2. Keywords: molten salt, molecular dynamics, partial pair correlation function, ionic charge, atomization energy, diffusion.

Jan 1, 2004

By P. J. Kinver

This paper deals with the development of backfilling methods and systems at the Broken Hill orebody of Black Mountain Mineral Development Company (Pty) Limited, at Aggeneys in the north-western Cape Province. Production started in 1979, being confined to large diameter blasthole stoping methods in the upper, steeply dipping areas of the orebody. This blasthole reserve is now depleted and the production tonnage, 100000 tons per month, is produced from eight cut and fill stopes in the flatter dipping areas of the orebody. The fill methods of the blasthole stoping area evolved prior to the pillar extraction are briefly discussed together with the resulting experiences gained that enabled virtually 100% extraction to be achieved. The original cut and fill mining used costly hydraulic cemented fill; this was replaced partly by unconsolidated river sand and later by dune sand which occurs in abundance. The paper describes the planning, research work and commissioning of a cycloning plant that now enables dune sand to be used successfully as an unconsolidated hydraulic fill. The development of drainage, placement and control methods are also reviewed.

Jan 1, 1988

By R. R. Mankowski

The work described in this paper is an attempt to increase present-day knowledge of fatigue in mine hoisting cables, particularly the internal energy loss arising from interwire/strand friction in a cable undergoing periodic non-planar transverse vibration. Such frictional energy loss is known to be one of the major influences limiting useful working life of hoisting cables in use today, and is responsible for the large capital outlay required to maintain the high safety factors prescribed by the mining industry. The experimental method employed identifies two mechanical characteristics of cables that are independent of amplitude and frequency, and are primarily attributed to the type of cable construction. Interest is focused the time rate of change of curvature as the major parameter influencing the internal damping mechanism. Empirical results confirm that amplitude and mode number play an important role in quantifying the internal losses, and also reveal that a critical radius of curvature exists below which damage due to vibration fatigue rises exponentialy to potentially high levels.

Jan 1, 1988

By N. Birtek, R. P. King

The washability characteristics of fine South African coals were measured and were found to be well characterized by an M-curve having the equation Z = aQb exp(cQ) x dQ, where Z is the ash content per 100 units of total feed and 0 is the mass yield. Parameters a, b, c, and d were determined for 23 different samples of coal from important coal seams in the main South African coalfields in the size range 0,0025 to 1 mm. The relationship between ash content and relative density was determined and correlated by means of two linear relationships. This characteristic behaviour was explained in terms of the liberation of macerals and the different association between the mineral mater and the two major macerals vitrinite and inertinite. The results obtained in this study can be used to calculate the expected performance of an ideal separation process, and can also be used as input for the simulation of real beneficiation plants. An example is worked through in detail to illustrate the method of calculation.

Jan 1, 1990

By Ralph H. Nafziger

This paper reviews the major deposits of lower-grade chromite in the world, and a wide variety of methods used for the recovery of chromium from them. Gangue materials in more coarsely sized ores can be separated by gravity means, whereas flotation techniques are required for finer-grained materials. However, unless there is considerable Iron In the ores, physical means cannot increase the Cr/Fe ratios. Chemical techniques such as hydrometallurgical methods, chlorination, roasting and leaching, and smelting are required for this purpose. A greater understanding of the physical properties of chromites and the chemical reactions that take place in the recovery operations is required before. the recoveries from lower-grade chromites can be maximized. More efficient recovery operations can be realized If It can be shown definitively that the reduction of chromites occurs via either a gas-solld or solid-solid mechanism, for example. The effects of specific impurities on the chromite reduction reactions need to be better understood, as do reagent and pH control in the flotation of chromite.

Jan 1, 1982

By R. Falcon, A. J. Ham

This paper summarizes the characteristics of Southern African coals, presents a fundamental approach to the combustion performance of coal, and reviews some of the recent developments in the fields of technological evaluation and boiler design for coals typical of this region. This includes a summary of the petrographic constituents of coa~ highlighting the differences between the Palaeozoic coals of the northern and southern hemispheres (Laurasia and Gondwana respectively), and the effects of these properties on the combustion performance of coal as seen in terms of laboratory, pilot-scale, and full-scale operating conditions. Recent developments in boiler design linked to advanced characterization studies and commercial experience have led to unprecedented use, with maximum effect, of the low-grade, high-ash, high-inertinite coals typical of some parts of this region. In the light of this success, more adequate understanding and better methods of assessment of the coals typical of the Gondwana region are called for, particularly in the light of the price premium for high-grade coal and the more cost-effective lower grade coals on the international steam markets.

Jan 1, 1988

By N. Saldía, C. Riveros, R. Hills, S. Barrera

The transport of tailings composites provided by different sources is a field of study where a limited amount of research has been conducted. Nevertheless, such systems are important sources of operational difficulties, especially in the case of high clay content tailings. The case presented in the present paper consists of a free surface flow pipeline transporting a composite of two different tailings with high clay content. It has presented operational difficulties such as partial blockages and upstream box and air intake overtopping events. In the present paper, the causes of these difficulties are identified. These include lack of complete mixing of the different tailings, multi-layered flow with low velocity and high yield values with high frictional losses. The pipeline characteristics and performance are analysed in three stages: design, initial operation and enhanced operation, the latter accomplished by means of increasing turbulence in the box located upstream from the pipeline. The last section of the pipeline and another distribution pipeline system located downstream from the pipeline have performed well. The cause of different behaviour of both systems is also assessed.

Jan 1, 2007

Newmont is one of the few remaining large mining companies that was established in the early nineteen hundreds. The company has a long, colourful and enviable history. This paper provides highlights of Newmont?s business and technical history since its inception in 1916, its transition to a ?gold only? company in the early 1990s and progress since that time up until the present day. Details of Newmonts current gold operations and its gold production profile for 2008 are also provided in the paper Over the last 50 years Newmont has developed a host of innovative gold technologies to meet the challenges of treating the complex refractory gold ores, found at the company owned mines in the Carlin region and around the world. Details of the technologies are provided and they include chlorination, roasting, bacterial and pressure leaching, leaching gold with thiosulphate and thiocyanate, N2Tech flotation, HPGR treatment of hard and abrasive ores and, finally, the use of Hydro-Jex technology for improving gold recovery from heaps.

Jan 1, 2009

By J. E. Chilton

No regular monitoring of methane is required in areas of gassy coal mines outby the mining face. Methane ignitions that have occurred in mine outby areas indicate the need to provide better protection to workers. Handheld methane monitors are now used by some miners to make periodic measurements of methane at the working face. The IYONI II gas detector which is incorporated into a miner’s cap lamp and worn on a miner’s helmet can continuously provide an alarm signal whenever methane levels exceed a set level. Tests were conducted to evaluate the performance characteristics of this methane detector by measuring response times with methane gas supplied through a calibration fixture or adaptor. Other response time tests were performed with the detector in an environmental test box. Performance was also evaluated in a full scale test gallery where face methane emission and underground ventilation were simulated. Procedures for calibration by response time measurement of the IYONI II detector have been developed. In limited testing, the IYONI II detector was found to reliably detect the presence of 1 percent by volume methane.

Jan 1, 2003

Mill relining is a major contributor to overall plant downtime. Reducing the number of mill liner pieces removed from and replaced in the mill has a direct impact on the overall reline time and in turn, mill availability. To improve the mill availability of Ridgeway Operations' 32 foot SAG mill, a number of initiatives were implemented in terms of liner design. These included the conversion of the shell from 40 to 30 rows, reducing the number of pieces from 80 to 60 each shell reline and reducing the number of pieces from 48 to 32 per feed end reline. In addition, modifications were made to the discharge end of the mill to extend the life of the outer pulp lifter and discharge cone, thereby reducing the frequency of change out. The standard radial outer pulp lifter was converted to an angled design. The discharge cone was converted to the BullnoseTM design supplied by Bradken. This paper discusses the design changes made and the expected benefits to the Ridgeway Operations in terms of mill availability improvements.

Jan 1, 2007

By D. J. Stanton

The objective of this study was to develop, install, and test a small underground mobile refrigeration plant (MRP) to deal with some of the real problems associated with mine cooling in an operating mine. The requirement for cooling the underground environment is discussed with particular emphasis on the need for this method of cooling, with the concomitant benefits. The research investigated current methods of cooling and reasons for previous failures in MRP. Both static and dynamic simulations were conducted to increase the confidence level under operating conditions. Implementation and testing, resulted in ?lessons learnt? requiring modifications, which are documented. Actual results have been recorded. These results have proved that significant cooling via MRP is feasible. Main benefits include positional efficiency, cost per kilowatt of cooling and cooling opportunities for remote hot areas of a mine. Finally, a proven technology is now available for large-scale implementation in the mining industry. Now the ventilation engineer has another system of cooling, which can be utilized in the quest to create an occupational environment, which meets the physical and mental health requirements of the worker.

Jan 1, 2004

By D. Burrows

Traditionally, characterisation of the mineralogy and textures of ore and rock samples were based on observations of hand specimens and thin sections using an optical microscope. The extent of the data collection was limited by the available tools and thus variations in mineralogy and texture were generally not described by quantitative data. These qualitative to semi-quantitative approaches, even though well established over the years, resulted in variable observations and data sets. The data were unlikely to be representative of a sample and limited statistical validity meant the results could not be reliably used in modern digital mining design and planning. With recently developed SEM based quantitative mineralogy tools and the corresponding methodologies, ore textures can be quantified and compared numerically. The numerical data can not only enhance the understanding of an orebody in geological terms, but can also be used in the creation of metallurgical models for mine and mineral processing design and simulation. These capabilities provide valuable inputs to risk assessment studies and the evaluation of mineral projects.

Jan 1, 2007

MEMBERSHIP In terms of By-laws7.7.1 members are hereby notified that the membership of the following has been cancelled and their names removed from the Membership Register: H. Digby Roberts, R. J. P. van Tonder, S. D. Williams (Members), A. I. de Klerk, M. F. Ford, A. W. Hine, H. A. Johnston, R. T. Joyner, H. D. Small, P. White (Associate Members), J. de F. Agrella, A. Leibowitz (Affiliates), J. P. M. Maidment, C. P. J. M. Steyn (Graduates), H. C. M. Fourie, B. C. P. Job, J. P. Kruger, E. C. Nicolas, A. P. Prinsloo, B. Schuitema (Students). INSTITUTE PUBLICATION Transactions of the Seventh Commonwealth Mining and Metallurgical Congress Requests are still being received by the Institute for sets of the above transactions. Members who wish to dispose of sets in good condition are requested to contact the Secretary, P.O. Box 1183, Johannesburg or 304 Kelvin House, Johannesburg. As these are for resale a price of not more than R10.00 can be offered per set of three volumes. INTERNATIONAL SOLVENT EXTRACTION CONFERENCE, 1971 The Society of Chemical Industry has agreed to sponsor an International Conference devoted to the science and technology of solvent extraction. This will be held in The Hague in the Netherlands during the week commencing 19th April, 1971. The organisation of the Conference will be in the hands of a Conference Committee under the chairmanship of Mr B. F. Warner. The emphasis of the Conference will be on technical solvent extraction of both inorganic and organic substances, including basic principles and practical applications. Sessions are envisaged covering the chemistry of solvent extraction, industrial processes and economics, the performance of contacting equipment and the underlying phenomena involved, and the response characteristics and control of such units. The Conference Committee will welcome offers of papers for presentation at the Conference. In the firts instance, intending authors should submit a preliminary title and an indication of the scope of their contribution to the Conference Secretary: Dr. C. Hanson, University of Bradford 7, U.K. It is hoped to have available in September a first circular giving further details of the Conference. Copies may be obtained from: International Solvent Extraction Conference, 1971, 14, Belgrave Square, London, S.W.1. SOUTH AFRICAN TUNNELLING CONFERENCE TO BE HELD IN 1970 A South African Tunnelling Conference, to be known as TUNCON 70, is to be held in Johannesburg during the latter half of July, 1970. South Africa, in common with other countries, has a vital and growing interest in tunnelling. Apart from the 800 kilometres of tunnel excavated annually in the gold mines, the 82 kilometre-long Orange-Fish Tunnel is being driven to carry water from the Orange River to the drier areas of the Eastern Cape Province. This and the realization that services such as water and transport are increasingly being carried underground in various parts of the world have emphasized the need for a forum at which the technology and potential of tunnelling can be discussed. TUNCON 70 is being supported by three professional engineering societies representing some 6,000 engineers, namely, the South African Institute of Mining and Metallurgy, the South African Institute of Civil Engineers and the South African Institution of Mechanical Engineers, as well as by the Geological Society of South Africa. The conference has three main purposes. Firstly, to pool and exchange expertise by authorities on tunnelling; secondly, to discuss future developments in tunnelling technology with the aim of making those concerned with long-term planning aware of the potentialities of tunnelling; thirdly, to propose standards for tunnel shapes and sizes. Adoption of standards for tunnelling equipment and accessories would be a major step forward in improving tunnelling efficiency. The five themes of the conference will be: tunnel utilisation, exploration, design, construction and standards. The conference will be held at the University of the Witwatersrand, Johannesburg, from 21st to 24th July, 1970. Arrangements will be made for visits to be paid to mines and tunnelling projects before the start of the conference. Further information is obtainable from the Organising Committee, TUNCON 70, P.O. Box 1183, Johannesburg, South Africa.

By K. M. Seiler

Automation in mining requires accurate maps of road networks on site. Because roads on open-cut mines are dynamic in nature and continuously changing, manually updating road maps is tedious and error-prone. This paper investigates the possibility of automatically deriving an accurate representation of the road network using GPS data available from haul trucks operating on site. We present an overview of approaches proposed in literature and test the performance of publicly available methods on GPS data collected from trucks operating on site. Based on shortcomings seen in all tested algorithms, a post-processing step is developed which geometrically analyses the created road map for artefacts typical of free-drive areas on mine sites and significantly improves the quality of the final road network graph.

Sep 1, 2021

By Peter Townsend, Sergei Diachenko, Allan Moss

The Palabora Mining Company has successfully extended the life of its operation by developing a 30,000tpd block cave underground mine below the now closed open pit. The process of transitioning from surface to underground mining has been technically, operationally and managerially challenging. This has been due to a number of factors; in particular, the development of a block cave in a very competent rock mass. The competence of the rock mass is clearly demonstrated in the open pit that preceded the block cave, one of the steepest deep open pit excavations in the world. With cave breakthrough, however, the pit was ?instantaneously? deepened by 400m causing a major failure of the northwest wall involving close to 100Mt of waste material.

Jan 1, 2006