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By D. L. B. Pollnow

Tinplate, and electrolytic tinning at the Iscor works, Vanderbijlpark by D. L. B. POLLNOW, B.Sc. (Chem.), M.Sc. (Met.), D.Se. (France) The paper first describes tinplate as a product, dealing with its structure and its advantages to the packaging industry. It then describes Iscor's electrolytic tinning line, which is one of the largest Halogen units in the world. Details are given of the process and of the equipment used.

Jan 1, 1977

By A. V. Z. Brink, D. M. O’Connor

Recent research into the prediction of mining-induced seismic events by the monitoring of small microseismic events at Western Deep levels Gold Mine is described. Measurement and interpretation techniques and results are presented. It was found that the occurrence of the larger events near longwall faces on the Carbon leader reef is preceded for some hours by an increased rate of microseismic emission and spatial concentration of the microseismic events in the zone of eventual failure. The research is currently being expanded with the aim of producing a practical rockburst early-warning system.

Jan 1, 1983

By F. W. Petersen

For the past thirteen years, the Universities of Cape Town and Stellenbosch have hosted an annual symposium to discuss topics relevant to mineral processing. Since 1987, this Symposium has been held under the auspices of the Western Cape Branch of the South African Institute of Mining and Metallurgy, and has become one of the main events on the national conference calendar. In 1989 and 1993, the symposia took the shape of international conferences. This year the 13th Annual Mineral Processing Symposium was organized by the two universities, the Cape Technikon, and the local branch of the South African Institute of Mining and Metallurgy, and was held at the Van Riebeeck Hotel in Gordon's Bay.

Jan 1, 1994

By G. Sommer, R. P. Chaix, G. T. W. Ormrod

Recent developments in the instrumentation and automation of uranium-processing plants by G. SOMMER, Ing. (Grad.) (Visitor), G. T. W. ORMROD (Visitor), and R. P. CHAIX, B.Sc. (Visitor) The paper discusses work at the National Institute for Metallurgy on the evaluation of measuring techniques for the automatic control of free acid in leaching. of the ratio of ferric to ferrous ion in leaching, of pH in liquid-liquid extraction. and of uranium in loaded solvent. Commercially available instruments. and the modifications that have been made to adapt them to South African uranium plants, are also described.

By W. J. Van Den Berg, J. G. Taylor

The paper discusses the introduction of blindhole boring on the South African gold mines of Anglo American Corporation. It covers the boring trials conducted, and outlines the progress made in the development of blindhole borers. The operating costs, and performances, of the latest 1,52 m diameter borer are given. Future trends and requirements In the application and design of blindhole borers are discussed, as well as factors that are of importance in the design of future machines.

Jan 1, 1978

By D. E. Scheck

A computer-aided blast design consultant system has been developed. The software consists of two modules: one uses theoretical and empirical formulae and procedures to design a blast based on user supplied geological and mechanical data, while the other is an expert system that analyzes blast vibration problems and recommends remedial action using knowledge based rules. The system is currently undergoing field evaluation.

Jan 1, 1987

By Northrop. I. N.

Hardmetals possess extremely high hardness and wear resistance, which render them ideal for applications such as metal-cutting tools, rock-drilling tools, and industrial wear-resistant parts like dies, punches, and seals. However, hardmetals are britle, and show poor resistance to impact and shock. They can therefore rarely be used unsupported, and it is common practice to attach hard metal working parts to a more resilient tool holder or support, which is normally made of steel. . . . Owing to the widely differing physical and mechanical properties of steels and hard metals, the Joining of one to the other is problematic, and the method used must be chosen with care. This paper reviews several methods available for the joining of hardmetal to steel, and discusses the advantages and disadvantages of each.

Jan 1, 1987

By S. Selmer-Olsen

New trends and developments in the production of ferro-silicon, ferro-manganese and ferro-chrome alloys are discussed, with emphasis on the general trend to the adoption of large production units. Problems which arise, both of a metallurgical and an electrical nature, due to the use of large electric furnaces, are outlined with specific reference to the limitations imposed by the power carrying capacity of Soderberg electrodes, the furnace resistance and the furnace reactance. The implications of combining high resistance within the furnace with good metallurgical operating conditions are illustrated by considering the production of ferro-silicon and ferro-manganese. The possibility of replacing electric furnaces used for ferro-manganese production, by large low shaft blast furnaces using oxygen enriched blast, is mentioned. The continued use of small electric arc furnaces for ferro-chrome production is also mentioned, and is ascribed to lack of ore suitable for treatment in large furnaces. Agglomeration of chromite ores appears to be a possible answer to this problem.

Two column flotation cells have been installed as single-stage rougher cleaners at Batu Hijau. The objective was to provide additional residence time in the cleaner circuit to maintain maximum recovery during high mill throughput and high feed grade periods. Installation of the columns has allowed the relatively coarse, well-liberated rougher concentrate and the relatively fine, low-grade scavenger concentrate to be treated separately, improving metallurgical performance in the cleaner circuit. Plant results show that the columns produce a high-grade concentrate at an average stage copper recovery of approximately 80 per cent. There is also indication of increases in both overall plant copper recovery and final concentrate copper grade. In addition, the operability and stability of the cleaner circuit has greatly improved.

Jan 1, 2007

By X. M. Prevost

A computer system to store, retrieve and process coal borehole and analytical data together with other geological, geographical or topographical information is described. As a result of the large volume and variety of data stored since its inception in 1979, as well as the basic versatility of the system, the National Coal Data Base has been performing a number of new tasks for which it was not originally designed. As considerable sets of data are used on almost every project, the use of statistical application programs has become an important processing tool.

Jan 1, 1987

Underground mining and particularly dipping narrow tabular orebodies are difficult to mechanize appropriately, given the low gold price and other external factors. Particularly in the deep level mines in South Africa, there is little choice left but to mechanize if the industry is to remain competitive and a significant global player. This paper presents a design philosophy for appropriate mechanization intended to generate solutions that can be implemented using the people currently employed in South Africa mines. The design philosophy is based on the ability of high-pressure water (hydropower technology) to deliver enhanced performance to users and on simplicity in the eyes of the user. Four examples of systems and equipment are described to illustrate the approach to Appropriate Mechanization. These include: • The Development End System, • The Monorail Raise Climber, • Automatic Pump Control Valves, and • The Energy Recovery Pump. The equipment is presented with the following critical issues foremost in mind: Safety, Working Environment, Performance, Cost effectiveness and Implementation. Although the appropriate mechanization approach is described in the context of the South African underground mining industry, much of the Appropriate Mechanization equipment has worldwide applications. Key Words: Hydropower, Mechanization, Tunnel Development, Raise Development, Monorail, Raise Climber, Pump Control Valve, and Energy Recovery

Sep 1, 2001

By J. M. Stewart, C. H. Wyndham

Suggested thermal stress limits for safe physiological strain in underground environments by J. M. STEW ART M.Sc. (Eng) (Witwatersrand) (Visitor) and C. H. WYNDHAM M.B., D.Sc. (Witwatersrand), F.R.C.P. (Land) (Fellow) A comparison of safe temperature limits, based on Mitchell and Whillier's equations for specific cooling power (SCP), with similar limits determined experimentally shows the SCP-based limits to be unnecessarily conservative. It is argued that, while a small part of this conservatism may be attributed to an erroneous extrapolation of the heat transfer dependence on wind speed, the major part is probably due to the use of too Iowa limiting mean skin temperature in the calculation of SCP. A combination of Mitche/l's basic data with results available in the literature permits the derivation of modified heat transfer equations based on data that fully cover the range of wind speeds of interest. These equations, using a mean skin temperature of 36°C as the basis for the calculation of safe temperature limits, are then shown to agree favourably with those determined empirically. Furthermore, values of SCP based on these equations are shown to correlate reasonably well with wet kata readings, giving positive support to the wet kata thermometer as a heat stress meter.

Jan 8, 1975

Ausmelt is supplying commercial quantities of an alkyl hydroxamate flotation collector AM28 for flotation of oxide and supergene base metal ores and tailings. AM28 is a non-hazardous product used as a ten per cent to 50 per cent solution in dilute potassium hydroxide. It is a selective flotation collector for oxide or oxidised base metal minerals and replaces conventional sulfidisation for oxide mineral flotation. At Radio Hill, the AM28 is used in conjunction with traditional sulfide collectors, which allows simultaneous flotation of oxide and sulfide copper minerals. The Fox Resources Radio Hill copper concentrator near Karratha, Western Australia, is currently configured to treat supergene copper ore sourced from the West Whundo open pit. This Archean VMS type copper deposit has been deformed and remobilised with uplift, erosion and weathering to form a significant supergene zone. The sulfide copper minerals present in the upper zone are digenite and chalcocite with lesser chalcopyrite and covellite. Oxide copper minerals present include cuprite, with lesser malachite and azurite. Gangue minerals include quartz, talc and chlorite. Plant trials at Radio Hill are reported for supergene West Whundo ore, where the AM28 was stage added into the circuit at nominally 80 g/t. Plant data over three months shows the copper recovery increased consistently from around 50 - 60 per cent to above 70 per cent when AM28 was added. This has been proven statistically. The grade of the concentrate was consistent with and without AM28, at nominally 22 - 24 per cent copper.

Jan 1, 2007

By D. Savile Davis

D. Savile Davis* (Member): The members of the Chamber of Mines Research Laboratories, headed by Dr Cook, indeed deserve all the plaudits that have been given for the original conception of the rock-cutter, and for the research work that has gone into designing the equipment now being tested. Underground trials with the rock-cutting machines at the Doornfontein Gold Mining Company Limited have been encouraging to the extent that 29 square fathoms of rock have been cut in the past three months with two modified prototype machines. Both the hangingwalI condition of the stope and the control of stoping width have been excellent. So far, however, the rate of production has been too slow and does not compare with conventional stoping methods, due firstly to the time-consuming operation of moving the machine forward and resetting it in its next cutting section and secondly to mechanical defects. Although great strides have been made in improving the tungsten carbide cutting tool, further progress is dependent upon engineering development in the design of a more reliable and versatile machine within economic limits. Commenting briefly on the experiments that have been carried out on the Gold Fields mines, the rock-cutter, when used at the Luipaards Vlei mine, some 600 ft below surface, cut very nearly perfect slots above and below the reef on a stope face but was unable to cut slots in the reef itself. At the Doornfontein mine, however, where the tests are currently being carried out at a depth of 8,000 ft below surface and where there is a much greater pressure acting on the rock face, vertical fracture planes can be clearly seen in the hangingwall running parallel to the face. Owing to the presence of these fracture planes it has been found impossible to cut slots of any depth and the action of the machine is more one of spalling than of cutting, resulting in slabs of combined reef and waste falling from the face as the cutting tool advances. This is accentuated by the existence of a well-defined hangingwall parting plane. Most of the slabbing takes place from the slot cut below the reef to the hangingwalI of the stope. Since waste sorting in narrow conditions and poor lighting is not an efficient operation, the reef together with a proportion of waste rock, has to be removed from the stope. The ripping action of the machine as opposed to slot cutting under these particular conditions may not be a great disadvantage, as the volume of waste which can be packed depends on the ratio of reef width to stope width and with a narrow reef body some waste has to be removed to the surface. In these circumstances mining at depth with this type of machine should not be viewed as selective mining but more correctly mining without explosives. Another type of rock-cutter is being tested by the Gold Fields Group, consisting of a diamond studded rotating disc, which has, to date, cut slots 10 ft in length and averaging 7 1/2 in. in depth. It is, however, too early to comment on the practicability and economics of such a cutter. The great interest that is at present being shown in breaking rock without the use of explosives warrants comment on the Robins raise-borer, recently introduced into South Africa, and used for the first time with great success at the Doornfontein mine.

By C. van Loggerenberg, P. E. Venter

The paper covers a wide range of modifications that are of potential interest to the practical coal-preparation engineer. Unfortunately, the paucity of performance data does not permit one to draw conclusions. The authors do not appear to have a clear understanding of the Tramp (or partition) curve concept.

Jan 1, 1992

By M. B. Algeo, R. H. A. Plaistowe

A method of forecasting the haulage trucks required for a large open-pit operation is described. Emphasis is placed on the effects of changes in planning and on the complexities of a mining operation that involves many benches and dumping areas.

Jan 1, 1979

COLLOQUIUM AND GENERAL MEETING Developments in gold recovery processes A General Meeting and Metallurgical Colloquium on the above topic were held on Wednesday, 14th March, 1973, at Kelvin House, Johannesburg. Dr J. P. Hugo (President) was in the Chair. The colloquium was attended by 170 delegates, and was opened by the President at 9.15 a.m.

By G. P. L. van der Linde

EVERY OREBODY IS UNIQUE [ ] GEOLOGY AND MINERALIZATION DIFFERENT [ ]

Jan 1, 2005

By C. J. Van Niekerk, D. R. Allen

The electrolytic extraction of zinc at the Zinc Corporation of South Africa Limited by C. J. VAN NIEKERK, B.Se. (Hons.)(Poteh.), M.Se. (Unisa)(Fellow) and D. R. ALLEN, A. Met. (Sheffield) (Member) This paper gives a brief account of some modifications that were made to the process of zinc electrowinning practised by the Zinc Corporation of South Africa Limited. Some changes in the materials of construction are also described.

Jan 2, 1977

Minutes of the Annual General Meeting held at the St. Helena Club on Wednesday, 27th July, 1977, at 7.30 p.m. Book review Advances in extractive metallurgy, 1977. Proceedings of the third symposium organised by the Institution of Mining and Metallurgy held from 18-20th April 1977. London, the Institution of Mining and Metallurgy, 1977. 244 pp. £18,50. Coal preparation A meeting of the Organising Committee of the Eighth International Coal Preparation Congress took place in Moscow on 24th and 25th May, 1977.

Jan 1, 1978