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By L. P. Lamprecht

Traditionally, South African shaft sinking operations have used electric detonators for the initiation of blastholes. Globally, the trend in shaft sinking is to use the shock tube and detonating cord (STDC) initiation system, with value adding benefits. In pursuing this global trend, Cementation Mining of South Africa in partnership with SMX have ventured the STDC route. This paper explores the work carried out to date, and identifies a number of benefits to be gained by using the system.

Jan 1, 1999

The Institute has concluded an agreement with the Chamber of Mines whereby the Chamber Librarian maintains a section in the Library for the Institute. Surface effects of underground mining South Africa is blessed with vast mineral resources. It is essential to exploit those reserves if the country is to remain economically viable. Surface-mining equipment The Goldfields Mining Expo '86 is to be held in Kalgoorlie, Western Australia, from 30th October to 1st November, 1986, in conjunction with the Annual Conference of the Western Australian School of Mines. Mintek reports Report M142D Characteristics of gold and pyrite flotation at the Chemwes plant. (1st issued May 1984.) Report M159D Beneficiation tests on andalusite ore from the Marico district. (1st issued Aug. 1984.) Report M164D The recovery of tungsten from South African low-grade schee/ite concentrates. (1st issued Sep. 1984.)

Jan 1, 1986

By J J. Pretorius, G M. Hoffmann

Utilisation of lower-grade (<60 per cent Fe) resources, not utilised in the current products, is crucial to ensure optimal resource utilisation and maintaining/improving future profit margins by reclassifying low-grade material to ore. The purpose of the Sishen Expansion Project (?SEP?) is therefore to investigate the technical and financial viability of producing up to an additional 10 Mtpa of new products at Sishen from material currently classified as low-grade materials. Jigging technology has progressed to a point where Sishen?s 50 to 60 per cent Fe run of mine (?ROM?) material, once considered as waste, can be beneficiated to produce a saleable 64 per cent Fe product. This has been confirmed through appropriate beneficiation testwork. Consequently, Sishen can now produce saleable product from material not currently included in the resource definition, increasing the resource base of the mine significantly and ensuring higher resource utilisation. Mine Planning utilised the geological models to produce detail planning schedules, reflecting the current and SEP plants separately, optimised to comply with product specifications of both the current and SEP plants and to confirm the viability of the low-grade resources identified as SEP feed material. The SEP products specifications have been derived by optimally matching iron ore market requirements with the revised resource base. A 64.0 per cent Fe lump product and a 63.5 per cent Fe fine product are the optimal SEP products. The SEP plant will be able to produce 10Mtpa at an average yield of 60 per cent and a lump to fine ratio of 62 to 38. The plant consists of five major sections namely crushing, material preparation, beneficiation, final product handling and quality control services. Maximum integration with the current Sishen plant was considered. Kumba currently has an agreement with Transnet to rail up to 23.5 Mtpa through the Sishen Saldanha Iron Ore Export Channel (?IOEC?). Transnet and Sishen Iron Ore Company have signed a Definitive Agreement that deals with the expansion of IOEC?s capacity, which increases Kumba?s entitlement from 23.5Mtpa to 35.0Mtpa. The detailed enviro-legal impact assessments for the SEP indicated that the project has low enviro-legal risk as a result of it being a brownfields project incorporated into the current Sishen operations.

Jan 1, 2006

By F. Terblanche, M. Holton, A. Kruger

The paper presents an optimal mine planning system designed to simultaneously optimize all the underground mines of large South African gold and platinum mining corporations. The system, code named PlanIT-OPTIM, is a multi-stage solution involving the use of adetailed 3D CAD-based mine planning system (CADSmine™V4). The mine design and scheduling rules defined in CADSmine™ are responsible for simulating mining sequencing, rock mechanics, and ventilation, etcetera. Feasible production ranges generated by CADSmine™ and various high-level mathematical models are used as inputs to a mathematical optimization engine. The optimization engine produces optimal production profiles (i.e. key business indicators such as tonnages, mineral and areas extracted per time period) by maximizing net present value. Other objectives such as profit continuity, production continuity and maintaining available reserves can also be specified as optimization criteria. The final step in the PlanIT-OPTIM process is to convert the optimal production profiles into practical and attainable business plans. This is achieved through the CADSmine™ Detail Optimization Engine that modifies the original CADSmine™ schedule to match the optimal production profiles. With current methods it is an impossible task to find the best business plan for a mining corporation in any reasonable period of time should conditions change (e.g. gold prices, exchangerates, grade estimates, etcetera). The fast turn around time achieved through PlanIT-OPTIM makes it possible to do several ‘what-if’ scenarios in a reasonably short time. PlanIT-OPTIM has already been used in the gold mining industry to find optimal business plans for a mine.

Jan 1, 2003

By J. Ekengård, H. Srinath, M. Andersson, P. Jönsson, D. S. Sarma

The present paper deals with mixing between the metal and slag phase during the ladle refining process, including vacuum degassing. Dispersion of metal drops in ladle slags has been studied. The results show a larger quantity of metal droplets in ladle slag during the alloying and stirring phase than during the subsequent vacuum degassing phase. The thermodynamic and kinetic aspects of the interaction between metal drops and the slag matrix have been considered and probable reasons for the observed distribution discussed.

Jan 1, 2004

By A. Mboma

Keywords: Furnace, decommissioning, care and maintenance, re-start, funding, nickel Bindura Nickel Corporation (BNC) operates two nickel mines, and treats concentrates from these mines as well as toll concentrates from the region around its Bindura Smelter and Refinery (BSR) complex. At the smelter, concentrates of at least 5% nickel content are blended and dried to 4% moisture in a coal-fired rotary kiln. Matte smelting of concentrate is carried out in a six-in-line electric arc furnace, where the furnace slag is granulated and discarded. Furnace matte is transferred via ladles into Peirce-Smith converters, where, after granulation, a leach alloy containing 68%Ni, 20%Cu, and 6%S is produced. Converter slag is recycled via the matte-smelting furnace. The onset of the global economic recession towards the end of 2008 resulted in a collapse of metal prices, worsening the local situation that was already marred by unfavourable macro-economic conditions in Zimbabwe. As a result, BNC mines were put on care and maintenance in November 2008, followed by Bindura Smelter and Refinery in February and March 2009 respectively. The business environment has since changed, and BNC is getting ready to re-start the plant. This paper describes the decommissioning of the Bindura furnace, asset preservation during the care and maintenance programme in the past two years, and preparation for starting up of the Bindura smelter in the near future.

Jan 1, 2011

By V. Yahorava

Resin-in-pulp (RIP) technology has recently often been considered for the direct recovery of base metals and uranium from dense pulps. Implementation of RIP will eliminate the requirement for any solid-liquid separation downstream of leaching and has the potential to combine the recovery and purification steps, hence reducing both capital and operating costs. The recovery of the valuable metal is expected to be higher when RIP is used, especially where the leached solids are difficult to settle or filter, and to wash. The main concerns about the use of RIP for uranium recovery from dense pulps are the impact of silica on the resin?s metallurgical performance and the operating costs that would be associated with resin loss. Although a number of resin manufacturers have been developing much improved RIP-grade resins, it is critical that the most cost-effective resin be selected. Mintek currently is doing a significant amount of work on silica fouling of RIP-grade strong-base resins in acidic leach liquors and the effect it has on the performance of the resin, including its durability. This paper describes the results of the test work done on silica fouling and its impact on plant design input data. Resin durability test work was done using various laboratory techniques, but durability was also evaluated on a relatively large scale using actual pumps, screens, and mechanical agitation. Based on the results generated, a preliminary economical evaluation was done to estimate the impact of resin loss on the overall economic viability of a specific application. Keywords: resin-in-pulp, silica fouling, resin loss, equilibrium, kinetics, elution, durability, mechanical strength, resistance to attrition.

Jan 1, 2009

By M. P. Brandt, T. P. Knoetze, I. I. M. Kessler

It has generally been accepted that the volatile mater in a coal is the factor that determines whether or not a specific coal dust is an explosion risk. This paper presents the results of an attempt to relate the explosibility index (Kex) of South African coals, as determined in a AD-litre explosion vessel, to the volatile mater content of the coal and the calorific value of the volatiles. A good relationship between the calorific value of the volatiles and the explosibility index was established, which makes it possible to calculate the violence of an explosion, as expressed by Kex, for South African coals. The Kex value is but one of a number of parameters that influence the explosion hazard in a specific colliery and cannot be used as the sole predictor of the propagation of an explosion underground. Other parameters include the ignitability of the coal, temperature, humidity, dispersibility of the dust, methane concentration, amount of incombustibles present, and ventilation.

Jan 1, 1993

By R. J. Hundermark

Keywords: Anglo American, Anglo Platinum Ltd, Waterval, Mortimer, Polokwane, ACP, pyrometallurgy, platinum, PGMs Anglo Platinum Ltd is the largest primary platinum producer in the world and operates three smelters in South Africa: Waterval, Mortimer and Polokwane. The operational details of the smelters are covered in previous reviews, thus only unit operations that have been upgraded are discussed. The most significant of the upgrades include the installation of a second ACP converter at Waterval Smelter in 2006 and the anticipated upgrade of Mortimer Smelter to 38MW in 2011. Several advances have been made in the smelting operations to improve the furnace stability and longevity. Control of the chromium input to each of the smelters has substantially allowed continued operations at levels below the spinel saturation point in slag, which results in lowered matte and slag temperatures. Mogalakwena concentrate, arising from the Platreef ore, is used to dilute high chromium-containing concentrates. In addition, furnace controls have improved in terms of crucible temperature and condition monitoring, improved feeding control, management of alarms and trips and having the quality of instrumentation and operational rigour required to support this. Advances have been made on the ACP converter in terms of good converter matte quality, and increased intensity and efficiency of operation. Combined with improvements to both the conventional and tower sulfuric acid plants, the emissions from Waterval Smelter have been reduced substantially since the introduction of the ACP. This is in spite of increasing metal throughput. The Anglo Platinum Ltd smelting operations have made significant progress since 2006 and further advances are envisaged to further improve on safety, reduce costs, increase efficiencies and throughput, while reducing emissions.

Jan 1, 2011

By Bjørn Nilsen, Werner Stefanussen

The construction of the Guaigui Multipurpose Project includes a 74 metre high concrete face rock fill dam, a 350 metre long diversion tunnel and a 350 metre long spillway tunnel. The topography in the project area is very steep, and the rock masses are characterized as soft rocks. The stability of the 80 to 100 metre high dam abutments and the excavation of the tunnels in soft rock conditions have caused various challenges and problems to be solved. Limited pre-investigations have called to a great extent for estimation of parameters for the stability calculations based on experience. The preliminary calculation of the stability of the planned rock slope above the spillway intake platform has been carried out by conventional partial factor methods and by use of a computed based Slide Program. The two methods of calculation give different results , and that rock support is necessary to obtain an acceptable factor of safety for a slope inclination of 52o. The input parameters for the rock mass characteristics need to be verified for the permanent calculations.

Jan 1, 2006

By L. Chen, G. A. Brooks, S. A. Nightingale

The dissolution of alumina and magnesia has been investigated using laser scanning confocal microscopy (alumina) and a rotating finger apparatus (magnesia) to assess the effects of temperature, composition and forced convection on the rate of dissolution in CaO-SiO2-Al2O3based slags. The two techniques have differing strengths and limitations, and provide complementary methods for studying dissolution. Alumina dissolution was studied for temperatures from 1477 to 1577°C. Based upon the data, the rate controlling mechanism was thought to be mass transfer control in the slag. The diffusion coefficients for the alumina particles are estimated to be in the range 10-11to 10-10m2.s. MgO degradation for sample rotation speeds of 50 to 800 rpm at 1500 and 1530°C was studied for both congruent and incongruent dissolution. The results show that the rate of dissolution for this is primarily controlled by a diffusion mass transfer mechanism for congruent dissolution except at the highest rotation speed. For incongruent dissolution, the mechanism is much more complex, with the morphology and distribution of the spinel reaction product having a significant effect. At high speeds and prolonged times, mechanical forces played a major role in the degradation process. Keywords; kinetics, corrosion, refractories, dissolution rate, inclusions, mass transfer, slags, steelmaking

Jan 1, 2004

Mr D. Wilson was born in Vereeniging, where he also completed his schooling, matriculating from General Smuts High School in 1977. Mr K.A. van Gessel was born in 1937. His final studies were conducted at Delft University, where he graduated with an M.Sc. degree in mining engineering. Mr J.G. McCaUum was born in 1938 and matriculated at Jeppe Boys&apos; High School, Johannesburg. Mr H. Scot RusseU started his mining career at Randfontein Estates Gold Mining Co. Witwatersrand, Limited, where he served as temporary Geological Assistant, Sampler, Surveyor, Shift Boss, and Mine Overseer. Mr A.M.P. Henderson was born in 1950, in Kiel, West Germany. Mr J.L. Nel matriculated in 1957. This was folowed by his atainment ofthe folowing degrees: B.Sc. (Chemistry, Physics) in 1961, B.Sc. Hons. (Metalurgy) in 1965, M.Sc. (Metalurgy) in 1967, and MDD (student of the year) in 1981

Jan 1, 1989

By R. S. J. Toit

Discussion: T. L. Gibbs,* (Honorary Vice-President and Fellow): In terms of the Pneumoconiosis Compensation Act of 1962, a Pneumoconiosis Risk Committee was established whose function it is to estimate (by whatever means the committee deems fit) in respect of every controlled mine the pneumoconiosis risk to which persons employed in a dusty atmosphere at that mine are exposed. In estimating such risk the committee may estimate different risks in respect of individual mines or parts of mines or classes or groups of mines or occupations or localities at mines. The pneumoconiosis risk may be reviewed and re-estimated at any time. The Act provides further that the General Council for Pneumoconiosis Compensation shall apportion the levy imposed on owners of controlled mines on the basis of the pneumoconiosis risk determined by the risk committee and the numbers of persons employed in a dusty atmosphere. The task of the risk committee is a most responsible one and also a very difficult and complex one in view of the many different types of mines, rock formations, dust conditions, etc. Quite obviously, comparisons between mines cannot be made on dust concentrations alone as different mineral dusts have different toxicity or pneumoconiosis response factors. However, with its present knowledge, the risk committee is satisfied that the risk at mines, other than coal mines, is related to the mean quartz-equivalent dust concentration to which persons are exposed and the estimation of risks is based on this relationship. From the above, it will be clear that the work done by Dr du Toit on the problem of basing the current rate of levies to provide for pneumoconiosis compensation on the current dust hazard at mines has been of immense value to the risk committee. Up to now the risk committee has not been able to obtain complete and accurate information on the dust exposure of persons at all mines - and, in fact, it is doubtful whether it will be economic or practicable to obtain this in the foreseeable future - but reasonable assessments have been possible from routine dust sampling in some cases and from periodic comprehensive dust surveys in others. As a temporary measure the risks of some mines were estimated initially on a group basis relating to average dust conditions and the type of rock and mineral mined, but as more information became available, differentiation between individual mines became possible. It is the aim of the risk committee to eventually apply such a differentiation in all cases and to ensure that within the bounds of practicability each mine pays for its risk and for its risk only. In this connection, the relationship between the levies and the amounts actually paid out in compensation are examined regularly. In conclusion, I wish to add my congratulations to the author on his excellent paper. His findings will assist materially in the just administration of that very important piece of beneficial legislation, the Pneumoconiosis Compensation Act. G. K. Sluis Cremer MD (Visitor): Dr du Toit has made a valiant attempt to relate dust hazard and the rate of collecting funds for the purpose of paying compensation for Pneumoconiosis. In doing so he has had to make a number of assumptious, some of which touch on the medical aspects of pneumoconiosis. It is worth discussing whether these assumptions are justifiable. Pneumoconiosis is defined in our Pneumoconiosis Act as permanent disease of the cardio-respiratory organs which is caused by the inhalation of mineral dust. To a non-medical person this definition has probably a clear cut meaning. The doctors however have to deal with such conditions as silicosis and asbestosis where there is a well defined dose response relationship to the inhalation of quartz and asbestos respectively and on the other hand chronic bronchitis where the relationship to dust inhalation is poorly defined and where certainly no clear dose response relationship has emerged after many investigations in this country and overseas. Nevertheless since 1953 about half of our certifications for Pneumoconiosis are on the grounds of chronic bronchitis i.e. the X-rays show no evidence of silicosis, asbestosis or other relevant disease. This fact must affect Dr du Toit&apos;s computations. The next assumption we should examine is the manner in which toxicity factors have been allocated to the various mineral species. These allocations have in part been based on a restricted number of animal experiments carried out overseas but mostly in South Africa by Webster at the Pneumoconiosis Research Unit. To extrapolate the findings in a relatively small number of animal experiments to the expected reactious in man is a notoriously dangerous exercise. Furthermore the bracketing together of all silicates (except asbestos) and the insoluble metal oxides is entirely unacceptable. Talc (a hydrated silicate of magnesium) and muscovite mica (a silicate of aluminium and potassium) cause pneumoconiosis in their own right. On the other hand

Jan 3, 1970

By By the staff of Gold Fields of South Africa

A diamond-drilling programme conducted from 1971 to 1973 by the Phelps Dodge Corporation revealed three complex sulphide ore-bodies in the highly folded Namaqualand mobile belt on the farm Aggeneys, some 65 km west of the small town of Pofadder on the road to Springbok in the northwestern Cape. Of these, the Broken Hill occurrence is the most promising.

Jan 1, 1980

By A. J. S. Benade, N. B. Strydom, W. H. Van Der Walt

The influence of two weeks of microclimate cooling on the state of heat acclimatization by N. B. STRYDOM, M.Sc., Ph.D. (Illinois) (Fellow), A. J. S. BENADE, M.Sc. (Potch.) (Visitor), and W. H. VAN DER WALT, B.Sc. (Potch.) (Visitor) Five volunteer Black subjects were acclimatized according to the climatic-room acclimatization procedure, and their states of heat acclimatization were determined by the usual heat-stress test. The subjects thereafter wore pre-frozen jackets in a somewhat higher environmental temperature (33,9/35,6 °C). stepping at the same rate as before for four hours a day for fourteen days. The heat-stress test was repeated and followed by a similar test at the higher environmental temperature. It was found that fourteen days of microclimate cooling in a very hot environment had no adverse effect on the degree of heat acclimatization. The sweat rates during microclimate cooling remained high, even though no sweating is possible beneath the pre-frozen ice-jacket. which indicates that there is an increase in sweat rate from the areas of exposed skin.

Jan 7, 1975

By M. R. Anderton

"A hierarchical four-character code designed for geological and allied data may be used to log exploration drill-holes and store the information on magnetic media. The code is intended for use in semi-free format and permits the collection of as much, or as little, data as the geologist may require for the purpose in hand. A method of data storage by variable length records is discussed.Information may be retrieved by means of a simple enquiry language. Optional output facilities could allow the retrieval of data in a form suitable for direct input to a contouring package. The enquiry parameters and interrogation program can thus provide the interface between the data bank and associated application systems."

Jan 1, 2014

By T. Ito, N. Tokashiki, H. A. Bilgin, Ö. Aydan, T. Akagi

This study is concerned with the electric potential induced by deformation, fracturing and sliding of non-piezoelectric geomaterials. In experiments, the acoustic emissions together with electric potential measurements were also measured in order to see how the so-called seismic electric signals are associated with new fracture occurrence and propagation and sliding in case of existing discontinuities. The outcomes of this experimental study may explain why such electric potential variations may occur during the fracturing and sliding of non-piezoelectric geomaterials. On the basis of these outcomes, their possible implications in geo-engineering and geo-science are discussed. Ce travail concerne 1e potentiel électrique produit par la déformation, 1a fracture ou le glissement du matériel géologique non-piézoélectrique. Aux expérimentations, on a mesuré 1es émissions acoustiques avec le potentiel électrique afin de constater la relation entre les phénomènes de glissement ou de formation et de propagation de nouvelles fractures le long des discontinuités existantes. Les résultats de ce travail expérimental expliquent pourquoi de telles variations de potentiel electrique se produisent durant le glissement ou la fracture du matériel non-piézoélectrique. Sur la base de ces résultats, on a discuté de leurs éventuelles implications dans les domaines de 1a géologie et de 1a géo-ingénierie. Diese Studie befasst sich mit dem elektrischen Potential das durch die Deformation, Bruchbildung und Gleiten von nicht-piezoelektrischen Geomaterialien induziert wird. In Experimenten wurden die akustischen Emissionen zusammen mit elektrischen Potentialmessungen gemessen, um zu sehen, wie die so genannten seismischen elektrischen Signale mit neuer Bruchbildung und Ausbreitung sowie Gleiten im Falle von vorhandenen Diskontinuitäten verbunden sind. Die Ergebnisse dieser experimentellen Untersuchungen könnten erklären warum elektrische Potential Schwankungen während der Bruchbildung und dem Gleiten von nicht-piezoelektrischen Geomaterialien entstehen. Auf der Basis dieser Ergebnisse, wurden ihre möglichen Implikationen in Geoingenieurwissenschaften behandelt.

Jan 1, 2003

Papers and Contributions Since the Institute&apos;s inception, it had been our practice until some years ago to meet regularly for discussion of new developments, using as a basis a paper read by one of the members. Usually, the Journal issue containing the paper would have been circulated well before the meeting, giving members plenty of time to absorb it and perhaps to prepare contributions. Discussion was generally lively, often controversial. The author always had an opportunity to reply.

Jan 1, 1991

By R. C. Urquhart, W. P. Channon, D. D. Howat

Discussion: The mode of current transfer between electrode and slag in the submBerged-arc furnace by w. P. CHANNON, R. C. URQUHART, and D. D. HOWAT J. MEINTJES I have read the paper with much interest, and I should like to make a few observations. (I) The experimental work deals with resistance heating by an electrode immersed in a slag... AUTHORS&apos; REPLY We thank Mr Meintjes for his critical analysis and helpful comments arising out of his study of our paper. Possibly we should emphasize at the outset that our experiments all related to the conditions in which the lower portion of the electrode was immersed in molten slag. We believe, however,

Jan 12, 1974

This paper provides a review of the chemical reactions occurring in the submerged arc processing of chromite ores. The excavations of industrial furnaces have shown that the charge, as it descends through the furnace, passes through a number of distinct reaction zones. Each zone is characterised by differing process conditions and reaction products. The phase equilibria, reaction steps and mechanisms occurring as the charge progresses through the furnace are examined, and the potential influences of these factors on the process outcomes are discussed.

Jan 1, 2004