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By T. Dimillo, R. G. B. Pickeirng

The South African gold and platinum deposits were formed in very different ways and yet both have many similarities. They are flat dipping tabular ore bodies, extremely narrow and located in hard abrasive country rock. The mining methods employed are also similar. Primary access is via shafts or declines; secondary access is via haulages and cross cuts; and tertiary access is from raises. The proposed solution for rapid access described in this paper is focussed on the haulages, cross cuts and raises. The non-explosive rock breaking method has many other applications, however, it is the integration with the Tunnel Digging Machine that results in the first, cost effective, Continuous Tunnelling Machine for hard rock mining.

Sep 1, 2001

By G. M. Wright

We are only as good as we are perceived to be by others and, whilst there is every opportunity to revise and polish our written works, there are no second chances with a spoken presentation. At every level, conferences and seminars have been metaphorical graveyards for many an academic reputation.

Jan 1, 1990

By A. Vogelzang

The paper describes how the level of the water-table was reduced as a result of increased pumping of water from the mine. Because such a condition in an area where there is compactable material above solid dolomite results In surface movement, steps were taken to restore the water-table to its former level. These included the return of water underground via a sinkhole and boreholes, and the piping of water from another mine.

Jan 1, 1978

Proceedings of a General Meeting held at the Witbank Golf Club at 19h30 on 3rd November, 1977 Geomechanics colloquy The 27th Geomechanics Colloquy is to be held on 12th and 13th October, 1978, in the Salzburg Congress Hall. The themes of the four half-day sessions will be as follows: Conference on pneumoconiosis The Vth International Conference on Pneumoconiosis is to be held in Caracas (Venezuela) from 29th October to 3rd November, 1978.

Jan 1, 1978

By W. Bleloch

In the process described, hydrogen is used to generate high-temperature steam and oxygen in the molten bath. Steel is decarburized to low levels to produce a pearlite-free steel suitable for deep drawing. The process makes use of the favourable thermodynamics in the reactions between steam, carbon, and iron, as well as providing high-temperature oxygen for the decarburizing reaction. The process can easily be incorporated in existing BOF (basic oxygen furnace) plant but can also be contemplated as a greenfield process.

Jan 1, 1987

By E. F. E. Müller

In a search for suitable reductants for the electro-metallurgical industry. the Fuel Research Institute is conducting investigations Into the charring of coals and the properties of the chars produced. This paper gives a selection of the results obtained as an illustration of the work being done. The research is proceeding.

Jan 1, 1980

By S. J. Patchet

The use of fill in deep-level gold mining presents the possibility of achieving considerable economic and operational benefits if conventional support can be eliminated. Unfortunately, the combination of the properties of tailings from gold reduction plants and the narrow, flat, tabular reefs being exploited make conventional hydraulic filling very unpractical. Laboratory tests indicate that, with careful control of water content, these tailings can provide an adequate fill material. A variety of bonding agents have been investigated, and the most practical seems to be ordinary Portland cement. Even at very low cement contents some cohesion is achieved. The design and layout for a complete fill support system using hydraulic transport, dewatering, and pneumatic placement are discussed, and a surface field trial indicated that the principles involved are correct and that acceptable results can be achieved. This system and material would completely eliminate conventional timber and brick support, and a preliminary economic analysis indicates that filling is cost competitive on a direct replacement basis. All the operations for a full-scale operation are available or have been developed to a stage sufficient to indicate that the system is practical, although certain operations require further refinement.

Jan 1, 1978

By R. Morris, W. D. Clough

SYNOPSIS The design of an opencast coal mine over areas previously mined by underground mining methods presents several potential methods of mining the coal. The paper describes some basic methods of mining for the No. 2 seam of the Witbank Coalfield, which had previously been mined by the bord-and-pillar method.

Jan 1, 1985

By G. V. R. Landman

Changes in the explosion behaviour of mixtures of coal dust, methane, and air when exposed to different energy sources are discussed. Changes to the lower explosive limits, minimum ignition energies, and rates of pressure rise when the same hybrid mixture of coal dust, methane, and air is exposed to ignition sources which are either spatially extended or spatially concentrated, are examined. A diagram is presented from which coal-dust loadings and methane presence can be determined which are below the lower explosible limits, and stated as a safety factor.

Jan 1, 1995

Book review AUSTRALIAN MINERAL INDUSTRY REVIEW FOR 1970 The Review is prepared by the Bureau of Mineral Resources, Geology and Geophysics, and gives an interesting and up-to-date account of the Australian minerals industry.

By R. P. Plewman

The Chemical, Metallurgical and Mining Society, from which The South African Institute of Mining and Metallurgy is descended, had as its coat-of-arms a green shield with a very flat gold chevron dividing the field into two. A crossed pick and shovel occupied the lower half, and an alembic (distilling vessel) and a flaming crucible occupied the top half.

Jan 1, 1982

By J. M. Paull, J. B. See

The rate of reaction between different carbonaceous reducing agents and silicon monoxide gas was studied by the use of a technique developed in Norway by Tuset and Raaness. Argon carrier gas was used to pass a known fixed concentration of silicon monoxide gas through an I1 cm3 sample of precalcined reducing agent at 1650°c. Silicon monoxide gas was generated by the heating of a mixture of silica and silicon carbide, and the progress of the reaction was followed by monitoring the carbon monoxide in the off-gas with an infrared spectrometer. The reactivity of silicon monoxide gas towards a number of carbonaceous reducing agents (charcoal, Iscor coke, Lurgi char, and petroleum coke) was shown to be similar to results obtained with the carbon dioxide reactivity test. The silicon monoxide reactivity test was able to indicate the extent to which fines were generated when the reducing agent was converted to silicon carbide. Of the reducing agents studied, Lurgi char appeared to be the most suitable for the production of ferrosilicon because it has a high reactivity towards silicon monoxide gas and high strength when converted to silicon carbide. So that industry could be given some indication of the suitability of certain reducing agents for the production of ferrosilicon and silicon metal, a reactivity scale similar to that of Tuset and Raaness was constructed that compares the volume of silicon monoxide gas required by a reducing agent to reach a carbon monoxide content of 10 per cent in the off-gas during the conversion of the reducing agent to silicon carbide. This scale assists in the selection of those reducing agents that require less silicon monoxide gas for conversion to silicon carbide, and that give savings in material and power costs because less silicon monoxide gas need be generated in the furnace.

Jan 1, 1979

By D. G. Krige

By use of models based on the South African gold-mining industry, analyses are made of the effects of changes in the mining tax structure on the .State's tax income from potential new mines; also on the percentage of such mines likely. to be proceeded with. The percentage is affected by the correlation between changes in taxation and in the flotation pay limits !or new mines. It is shown that the State stands to gain both directly and indirectly from raising the level of the capital allowance and from its extension to all mines; and that the reduced taxation resulting from a lowering of the discriminatory high tax formula for the gold mines, would, in respect of potential new mines, be compensated for by a significant increase in the percentage of such mines that would be proceeded with.

Jan 1, 1979

By D. J. Adams, R. G. Gürtunca

This paper describes the results obtained from a rock-engineering monitoring programme carried out at West Driefontein gold mine, where dewatered and classified tailings have been used as backfils for local and regional support. The in situ behaviour of these backfils and the surounding rockmass were determined, and it was found that the backfil used on this mine has provided significant regional support. The underground observations also showed less rockburst damage in backfiled panels than in unfiled panels, provided the backfil had been placed properly in the stopes.

Jan 1, 1991

By R. J. Dippenaar

In his inaugural lecture (delivered in Afrikaans at the University of Pretoria on 16th February, 1995), Professor Dippenaar defends his doctrine, philosophy, objectives, and methodology, as was required of a newly appointed professor in the days of old. Briefly, he recounts the growth and achievements of the Department of Material Science and Metallurgical Engineering at the University of Pretoria; he sketches its strategic guidelines and the obstacles encountered; he outlines the opportunities for the metallurgical industry in South Africa and the need for environmental control; and he describes how modeling techniques, together with expert systems, can aid both the industry and the community. He ends on an optimistic note, saying that his Department will continue to strive to transform adversities into opportunities, and to give its students a view of new horizons beyond the foundations laid by their teachers.

Jan 1, 1996

By D. J. Adams, R. G. Gürtunca

CONTRIBUTION BYJ.F. CURTlS The paper, which in an exemplary manner records the monitoring of backfill behaviour, falls short in the 'rock engineering' stated in the title. Just what the objective of the rock engineering was is obscure.

Jan 1, 1992

By A. A. Bradley, K. H. Stanton, P. J. D. Lloyd

A theory for the dynamic balancing of centrifugal mills is presented that takes account of the mass and shape of the charge in a gyrated grinding tube and the way in which the charge lags behind the centrifugal force vector. predicts that a corresponding lag in the angular position of the counterweight centres of mass is necessary, and that the fractional filling should be increased if the ratio of gyration diameter to tube diameter is decreased. A worked example is given for a I MW centrifugal mill that was balanced adequately by the methods described.

Jan 1, 1983

By D. W. Boydell, E. B. Viljoen

A flowsheet incorporating rotary-drum filtration for the solid-liquid separation step, followed by solvent extraction for uranium purification, is used as a standard against which four flowsheets are compared. These flowsheets employ either counter current decantation or belt filtration for solid-liquid separation, and either solvent extraction or continuous ion exchange plus solvent extraction for the purification step. Sales revenue, taxation, capital expenditure, and operating costs are estimated. These factors are taken into account in the calculation of an incremental net present value for each circuit by the discounting of cash flows at 25 per cent per year over a projected life of 15 years. For the material used in these examples, the highest net present value results from the circuit that employs belt filtration followed by continuous ion exchange and solvent extraction.

Jan 1, 1978

By T. C. Marshall

A comparison between hydraulic and pneumatic rockdrills by T. C. Marshall, Pr.Eng. (Member) The greatly increased output of rockdrills has placed new demands on booms, carriers, and drill steels and bits. Limited scope for further improvement in pneumatic rockdrills has led to the development of hydraulic rockdrills, which compare favourably with their pneumatic counterparts: they are more efficient, more flexible in coping with variations in the working conditions, more economical in the consumption of drill steel, and less productive of noise and mist. Their disadvantages include a greater need for a reliable power supply, a greater vulnerability to dirt, greater complexity (requiring more skilful maintenance), and the liberation of heat into the working environment. They should be regarded as a complement to, and not as a substitute for, pneumatic rockdrills.

Jan 2, 1974

Papers of Interest The following papers may be of interest to members. APCOM The Thirteenth International Symposium on the Application of Operation Research and Computer Techniques for Decision Making in the Mineral Industries will be held at the Technical University CIausthaI, Federal Republic of Germany, from 6th to 11th October, 1975.

Jan 1, 1975