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By D. F. Williams

The modelling, simulation, and design of processes for the recovery of gold from solution by absorption on carbon require the combination of a suitable rate expression with a description of the flow conflguration of the system. By the use of a suitable rate expression from the literature, methods are presented for the design of multi-stage countercurrent absorption systems corresponding to the commonly used carbon-in-pulp and carbon-in-column contacting systems. The sensitivity of the recovery to various design parameters is illustrated. These results have important implications in the choice and design of equipment.

Jan 1, 1985

By J. C. Vreugdenburg, W. A. H. Poppmeier

An overview of methods of manufacture is presented, as well as the results of laboratory experiments on the making of stainless clad steels. , It is concluded that stainless clad steel can be made in South Africa with existing rolling equipment, and that good bonding between the two materials depends on clean mating surfaces, proper edge welding, and a minimum reduction of 25 per cent at a rolling temperature of 120O"C. In practice, a minimum reduction of 70 per cent at 1100cC is recommended. : Suggested applications for clad steel include parts and equipment for the chemical, petrochemical, marine engineering, and mining industries, for the building sector, and for household appliances.

Jan 1, 1991

By D. A. Fenton

The structural design of large grinding mills, with reference to shell-mounted bearings by D. A. FENTON*, P. Eng. (Visitor) The paper outlines the advantages of shell-mounted grinding mills over mills having a conventional trunnionsupported shell. The growing use of larger mills in the past decade has led to a significant number of mechanical and structural failures, the most common being those at the junction of the head and the shell. Larger mill diameters favour the use of shell-mounted bearings. The elimination of castings, which have an inherent weakness to fracture, makes the shell-supported mill lighter and stronger than a conventional mill of the same shell thickness.

Jan 9, 1976

By P. H. Botha

An account is given of the procedures used by the South African Iron and Steel Industrial Corporation (Iscor) for tests on the flotation of coal fines, and some of the beneficiation problems encountered with coal from Durnacol, Grootegeluk, and the Soutpansberg area are discussed. These, and other South African coals differ from overseas coals in that they contain a high percentage of fixed ash, which means that they have to be crushed more finely for liberation and that they then contain more fine material (smaller than 0,84 mm). In addition, the coal from the three areas mentioned occurs in fine layers and seams, and contains many intergrown particles.

Jan 1, 1980

By S. W. Evans, G. Pienaar

Weldable steel plate with a good combination of strength and toughness is currently produced from 0,12 to 0,28 per cent carbon low-alloy steel heat-treated by roller quenching and tempering. Alternatively, steel plate of the same strength can be produced at a lower production cost by the use of very-low-carbon steel (0,03 to 0,08 per cent carbon) processed by in-line quenching without tempering. This paper reports the results of experimental work on these steels, and compares them with the properties of conventional steel. On thinner sections, it was found that the properties of the experimental steels compare favourably with those of conventional grades.

Jan 1, 1989

By T. A. Claasen

Exceptionally low yields in the coking-coal fields of the Soutpansberg area in the northern Transvaal, are taxing the skill and ingenuity of preparation engineers. The coals are highly intergrown, and a series of crushing and washing steps may be required to extract the maximum usable tonnage. In addition, novel preparation techniques may have to be employed. This paper, which is a case study of work recently undertaken, gives a general account of raw coal properties, emphasizing those related to maximum recoveries, and outlines the steps involved in the design of appropriate flow sheets based on laboratory studies.

Jan 1, 1980

By P. Smit

Health hazards of South African . mIne water by P. SMIT, M.B., Ch.B., D.T.M.H., D.P.H. (Visitor) The water supply in South African mines is not as good as most mining engineers would like to believe, nor is sufficient care taken to ensure the safe dispensing, transportation, and consumption of water. As long as cases of dysentery and typhoid continue to occur in large numbers, it can be assumed only that the water supplies are not safe, or that the water-dispensing methods are poor. A dual water supply is a real health hazard. The ideal water supply is a single safe source for human consumption and industrial use.

Jan 4, 1977

By C. E. Feather, G. M. Koen

The significance of the mineralogical and surface characteristics of gold grains in the recovery process by C. E. FEATHER B.Se. Hons. (Cape Town)* and G. M. KOEN D.Se. (Pretoria)* A description is given of the nature and occurrence of gold at various stages in the process of its recovery from Witwatersrand and related ores. Electron microprobe investigations show that the surface of gold grains in the ore is already coated. During metallurgical processing, further coatings, mainly hydrated iron oxides, accumulate on the grains. Theories are advanced for the formation of these coatings, and the adverse effects on metallurgical operations are discussed.

By W. F. Lorch

Growing use of deionised water in surface coating techniques by w. F. LORCH Production engineers in the metal plating, paint, plastics-coating and printed circuit industries are increasingly aware of the cost of sub-standard or blemished items which have been poorly processed. An area where quality control can quickly produce higher efficiencies is in the choice of suitably purified water for making up solutions, for rinse baths and 'drag-out' baths, for cleansing lines and electrophoresis tasks, for maintaining electrolyte density and hence consistency, and for facilitating the recovery of valuable minerals. The author of this article examines the general problems of using nonpurified water, and shows how purified water has become accepted by the principal surface coating industries to improve processes and effect economies.

By K. R. Vost

Calculations are given for the reduction in amplitude and change in phase of the diurnal variation in air temperature as the air flows through a mine. The concrete lining of a typical shaft was found to have a much greater effect than the steelwork. An increase in the conductivity of the concrete, or filling of the steelwork with water, did not have enough effect on the rise in air temperatures underground during the day to justify the costs involved. The steel temperature followed the air temperature much more closely than the concrete temperature did. Calculations are given for the heat stored in steel and concrete during the day.

Jan 1, 1980

By G. E. Blight

It is shown that the profiles of beaches of hydraulic-fill tailings dams can be predicted with good accuracy the use of small-scale laboratory deposition tests on materials from a prototype tailings dam. Although the slope of a tailings beach at any point is related to the shear strength of the settled slurry, are severe practical difficulties in the prediction of beach profiles from shear strengths measured in the laboratory. The hydraulic sorting of particle sizes that occurs on a tailings beach results in a gradient of permeability the beach, and this gradient has the significant effect of lowering the phreatic surface in the tailings dam.

Jan 1, 1985

By M. B. Algeo

Discussion of the above paper M. B. ALGEO The management and staff of Buffelsfontein Gold Mining Company Limited are to be congratulated on the excellent performances described in the paper presented by Mr Christos. In this day and age, with the current economic and labour situation, the mining industry is being constantly pressed to increase the productivity of ever-diminishing quanta of resources. Stress in rock The ISRM Symposium, 1976 is to be held in Sydney from 9th to 13th August, 1976. It is being organized by The Australian Geo. mechanics Society as a regional symposium of the International Society for Rock Mechanics. Thermal analysis The First European Symposium on Thermal Analysis will be held at the University of Salford on 20th to 24th September, 1976.

Jan 12, 1975

By J P. van Dyk

The dramatic strengthening of the rand against the dollar as well as a decline in quantity and quality of locally available concentrates have had a dramatic impact on Zincor?s operations during the previous two years. Zincor has responded with the implementation of a number of technical improvements to the process to decrease cost and increase revenue and plant flexibility. Among the initiatives is the pre-leaching and pelletising of the zinc concentrate, de-bottlenecking and process improvements in the leach and purification circuits, the introduction of cathode washing and automated cathode stacking in the cell house and the installation of a new furnace to produce pre-alloyed jumbos. This paper will describe these initiatives and others that Zincor have recently taken to stay competitive in changing global base metals market.

Jan 1, 2005

By H. L. Monro

The price received for a commodity decreases as the quantity sold increases. all other factors remaining the same. This has been the position with gold since it was demonetized in August 1971. The result is that the marginal revenue per kilogram of gold decreases steadily with increased production. If operating losses are to be avoided, the marginal cost of production must not exceed the marginal revenue. This requirement, although not seriously violated by most invididual mines, is not met by the industry as a whole, resulting in large losses of income to the State and the shareholders. These losses are increasing, and a way of curbing or reversing this trend is described.

Jan 1, 1984

By R. D. C. Shone

Consideration is given to the technical and economic feasibility of freeze desalination as a technique for the simultaneous provision of ice to cool deep mines and for the desalination of mine water. Freeze desalination has not been developed fully or commercially. For sea-water applications, it may not offer significant advantages over other methods of desalination but, for the unique mining application, a single dual purpose plant that produces desalinated ice could offer significant cost savings over combinations of separate desalinators and ice-makers. The current status 01 freeze desalination is reviewed, and the important aspects relating to mines are discussed. Some freezing processes that could be suitably modified are described. The possible use of conventional ice-making machines for desalinating mine water is also discussed.

Jan 1, 1987

By R. Hemp

The first part of this paper describes the collection of barometric pressure measurements in a mine and their statistical analysis, which shows the effect of variations in barometric pressure, both on the primary emissions of methane gas into the workings (whether from fissures or from the surrounding strata), and on the flow of air to and from large unventilated, or poorly ventilated, areas. The second part of the paper deals with a study, based on computer simulations, of leakage flows of air into and out of sealed areas, and the reduction of such flows by the use of adequate seals.

Jan 1, 1994

By A. Moerman, M. Verreault, V. Falmagne

Noranda has been involved in the development of technologies for automated mining vehicles since 1988, and has contributed in transferring the technological foundation for the suite of SIAM products now being commercialized by STAS. Some of these technologies are now mature and available for commercial implementation in operations where a strong business case can be made for the use of automation. Noranda has successfully implemented or is commissioning the Tele-remote, Auto-loading and truck Guidance technologies at two of its operations, based on operating needs and economic justifications. Operator acceptance, training and maintenance issues have been addressed in order to ensure the reliability and availability of the automation components. These represent the most significant challenges encountered and addressed during the implementation period.

Sep 1, 2001

By A. K. Haines

The status of the South African research and development programme on continuous ion exchange, which was aimed at the technical and economic assessment of that process for the recovery of uranium, is reviewed. The first phase of this programme, which has now been completed, involved development investigations on various pilot plants and culminated in the successful operation of a large-scale demonstration plant and the incorporation of the system in a number of new South African uranium plants. This account highlights the engineering aspects and the design fo the system, its adaptation to process flowsheets, and plans for future development.

Jan 1, 1978

By M. Mrost

Slimes disposal at South African gold mines by M. MROST*. M.Sc. (Rand) (Fellow) The soil mechanics, civil engineering, and environmental considerations applicable to the construction of slimes dams on the Witwatersrand gold mines are discussed. It is concluded that, though the procedures used in the construction of dam embankments do not accord with the best possible practice, they are entirely adequate in current local circumstances, provided that proper precautions are taken to ensure that the wall foundations are sufficiently permeable and strong, and that the dams are protected against erosion. If current trends towards larger mining and metallurgical complexes continue, it may become necessary to build larger, higher dams, and to adopt slimes embankmentbuilding practices that are inherently more reliable.

Jan 2, 1974

By R. R. Mankowski

The work described here attempts to underscore the importance of the time lag between the end of a loading phase and the instant a winding drum begins its acceleration phase. Traces generated from a computer-simulation model show that the amplitude of the stress oscillations occurring in mine hoisting cable during the constant velocity-of-ascent phase is a direct result of the temporal sequence employed between the loading and the raising phases. While current and early literature indicates that extensive work has been undertaken on the isolated effects of these two independent sequences, the literature does not appear to contain any documented evidence to suggest an optimal control or interfacing between these two dynamic regimes.

Jan 1, 1995