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By A. M. Copeland, A. J. Barrett

The use of hydraulically placed backfill in the deep gold mines of South Africa has increased rapidly over the past decade. The backfill that is delivered to the placement areas has a relatively high moisture content, and it is therefore pumped into geotextile containment bags that allow excess water to drain out but retain solid particles. The specific problems associated with this process that are addressed in this paper include the loss of solid particles entrained in the excess water, the rate of strength gain of the backfill, and the post-placement shrinkage of the backfill. The results of laboratory, surface stope, and underground tests are described. The parameters that were varied included the slurry density, the particle-size distribution, and the feed rate of the slurry the concentration of added flocculant; and the type of geotextile used as containment. Suggestions are given for the optimization of the placement properties of backfill.

Jan 1, 1994

By G. B. Lundstrom

SYNOPSIS For some time, Vaal Reefs South has operated blindhole borers successfully as an integral part of the mining cycle of operations. To date, over 13 000 m of mechanized boxholing has been completed, and from time to time impressive performances have been achieved. The paper describes the machines, the modus operandi, and the structure of the boring organization at the Mine, with some of the results recorded. The Mine recently took delivery of two new machines with interesting design features. The introduction and early experiences with these two machines are also described.

Jan 1, 1985

By J. S. Preston

The properties of some recently developed solvent-extraction reagents for the separation of cobalt and nickel sulphate solutions are reported. New commercial extractants based on alkyl phosphonic and alkyl phosphinic acids are described. These reagents show much improved selectivity for cobalt compared with established extractants. Some novel extractants developed at Mintek for the selective recovery of nickel in the presence of cobalt are also described. These reagents, which are based on mixtures of carboxylic acids and non-chelating oximes, are of interest in that no commercial nickel-selective reagents are currently available. Graphs showing metal loading and stripping, and pH-functionality, are presented. together with details of the metal separations achieved in batch countercurrent- extraction experiments with the various reagents.

Jan 1, 1983

Publications of the 13th CMMI Congress, by J.T. Woodcock (editor-in-chief). Melbourne, Australasian Institute of Mining and Metallurgy, 1986. Set $A90,00. Reviewer: J.D. Austin

Jan 1, 1988

By J. H. Venter

This paper contributes towards the solution of the problem of characterizing the accuracy of estimation of ore quality based on a random sample from the ore bulk.

By A. G. R. Coreejes, G. Ferreira

The paper sets out briefly the methods used for the planning and control of the construction work at Grootegeluk Coal Mine near EIIisras, Transvaal. It includes a discussion of the programming, the updating of programmes, and the progress reporting.

Jan 1, 1982

A General Meeting and Colloquium on 'Motivation and productivity in the mining industry' was held on May 22nd, 1974, at Kelvin House, Johannesburg. Mr P. W. J. van Rensburg (President) was in the chair. The Colloquium was attended by 170 delegates and was opened by the President at 09h25.

Jan 8, 1974

Previous investigations of stress conditions under which core discing occurs have concentrated on shear stress as the cause of this phenomenon. In this paper it is suggested that discing initiates as a result of extension strain, which develops in the field of triaxially compressive stress ahead of the borehole end.

Jan 1, 1982

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 G. Coetzer, J. C. Davidtz

The substitution of functional groups in covalent trithiocarbonate collector molecules influences the selective and non-selective bonding of collector molecules to mineral surfaces, as well as flotation efficiency in a mixed sulphide ore. These effects were concluded to be related to the metal-sulphide solubility products and electron densities on the sulphur atoms in the collector

Jan 1, 1989

By H. Knorre, A. Griffiths, R. Higgins, S. Gos

Hydrogen peroxide is gaining acceptance as a reagent for the treatment of mining effluents containing cyanide. In this paper some of the chemical and environmental aspects of treatment with hydrogen peroxide are discussed, and one way of improving the economics of the process is described. This is known as selective detoxification, which involves the oxidation of the less stable (cyanide) complexes while not affecting the more stable complexes, which contribute very little to the concentration of free cyanide or to the toxicity of the treated water.

Jan 1, 1987

By H. P. Coetzee, V. J. Solomon

As the price of gold increased, so did the viability of mining previously abandoned unpay areas of Stilfontein Mine. After an assessment to confirm the profitability of mining these areas, it was necessary to re-establish access-ways such as haulages, cross-cuts, and travelling ways. Openingup is a labour-intensive, relatively slow operation, and attempts were made to mechanizeand speed it up. Some of the techniques applied and the results achieved, whether successful or not, are discussed.

Jan 1, 1982

By G. H. Grange

Details are given of three legal controls for the pollution of the air, the water, and the land, together with brief histories of the developments leading up to these controls. Attention is drawn to the fact that legal action may be instituted against a mine under common or other laws where pollution causes proveable damage or loss. It is suggested that an international conference should be held to define the philosophies and principles on which to base not only the necessary legislation for environmental control but also the machinery by which the controls can be administered.

Jan 1, 1978

By H. A. D. Kirsten

The paper reports on loading tests conducted on shotcrete reinforced with mesh and various types of steel fibre, and compares the results with the energy absorbing capabilities of 16 mm rebar shepherd's crooks. It is concluded that mesh-reit1forced shotcrete has sufficient energy-absorbing capabilities to contain rockbursts of significant magnitude, having greater energy absorbing capabilities, even at a thickness of 50 mm, than 16 mm rebar shepherd's crooks. Fibre-reinforced shotcrete has energy absorbing capabilities of the same order as, or better than, those of 16 mm rebar shepherd's crooks, but its performance is erratic.

Jan 1, 1995

By M. U. Ozbay

This paper presents an overview of the research that has been carried out to improve the understanding of the fracture processes occurring in rock under high levels of stress. The onset and growth of fractures are studied by means of laboratory model testing, and the results obtained are used in the calibration and validation of the numerical model DIGS, which is based on displacement discontinuity. The results obtained so far have shown that, while there are overall similarities between the experimental results and the numerical simulations, improvements to the experimental procedures and the DIGS are required for a detailed mechanistic understanding of shear-band orientations and extension fractures.

Jan 1, 1996

By M. Sciarone, B. Collins

The production, properties, and selection of ferrosilicon powders for heavy-medium separation by B. COLLlNS. B.Sc Eng. (Rand) (Fellow). T. J. NAPIER-MUNN. B.Sc. (Eng.). A.R.S.M. (Visitor). And M. SCIARONE. M.Se. Eng. (Delft) (Visitor). There are basically two types of ferrosilicon powder available to operators of heavy-medium plants in South Africa spherical and milled grades. The production processes are described, and the properties of the two types are examined and compared. Guidelines are given for the selection of the correct grade of ferrosilicon for any particular application.

Jan 12, 1974

By H. M. Friede, R. H. Steel

Tin mining and smelting in the Transvaal during the Iron Age by H. M. FRIEDE*. Ph.D. and R. H. STEEL* (Visitors) This paper reviews the historical, archaeological, and metallurgical evidence on Iron Age tin mining and tin smelting in Southern Africa. The results of the analysis of twenty samples of tin ore, tin slag, and tin ingots found associated with Iron Age materials in the Transvaal (mostly in the Rooiberg area) are reported and discussed. The types of ingots preserved in local collections are described. A small experimental tin-smelting furnace was constructed and worked according to traditional African Iron Age technology. Qualitative and quantitative results of this experiment are reported.

Jan 7, 1976

By B. E. Protheroe, C. Allen, A. Ball

The results of laboratory abrasive and abrasive-corrosive tests carried out on a range of carbon, Iowalloy, and stainless steels are compared with underground tests conducted on similar materials on prototype shaker conveyors carrying gold-bearing quartzitic rock. The dry-abrasion resistance of all the steels was found to be better than that of mild steel. When the added effect of corrosion was tested, the stainless steels proved to be much superior to proprietary abrasion-resistant alloys both in the laboratory and underground. The ferritic stainless grades were shown to be superior on the basis of cost per unit of volume lost. This investigation has shown that laboratory tests on materials can provide valuable information on their possible performance in situ, and can thus be used to replace lengthy experiments on site.

Jan 1, 1981

By D. D. Howat, J. van der Colf

Selected members of the slag system were reduced in graphite crucibles in an argon atmosphere, and the physicochemical properties of the reduced derivatives of the slags were determined in inert crucibles. It was found that slags having magnesium aluminium titanate as the primary phase before reduction underwent an increase in liquidus temperature, accompanied by a change in the primary phase. No analogous behaviour could be detected for the slags having perovskite as the initial primary crystallization product. In most instances, the viscosity of the melt passed through an initial minimum, followed by an increase as the reduction time was extended. Increased MgO/CaO ratio. basicity, titania content, and reduction temperature all served to accelerate thickening. During reduction, the electrical conductivity of the slags tended to rise relative to the value for the unreduced melt.

Jan 1, 1979

By S. Nana, M. B. Cortie

Duplex stainless steels containing high levels of manganese and copper and lower-than-normal levels of nickel were produced and evaluated. The experimental alloys containing 3 per cent copper by mass could not be successfully hot-rolled. Alloys containing less than 2 per cent copper could be hot- and cold-rolled without difficulty. The wrought experimental alloys that contained copper were found to offer some advantages over the 2205- type duplex stainless steel in sulphuric acid at 52°C. Resistance to pitting attack was governed primarily by the chromium, molybdenum, and nitrogen contents, and one of the experimental alloys was superior to the 2205-type alloy in the ferric chloride test. It is concluded that manganese is a useful substitute for nickel in duplex alloys, but that further work is required before the present alloys, or variations of them, could be commercially viable.

Jan 1, 1993