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By R. J. MacAulay, R. C. More O’Ferrall

Preliminary tests on cement-consolidated gold-plant slime are outlined, together with preliminary underground tests on the behaviour of two paddocks of the material. Further large-scale testing of the same material pumped to the underground workings from a batching plant on surface is described.

Jan 1, 1978

By R. H. O?Connor, B. N. Soutar

The paper reviews the introduction 01mechanical shaft drilling into the sinking 01shafts in the Gold Fields Group. A comparison is made between the operating costs 01the drilling rig and those of conventional hand-held machines, and it is concluded that, despite certain disadvantages, mechanical drilling is preferable.

Jan 1, 1988

By M. R. Henzen, J. W. Funke, G. J. Stander

SYNOPSIS The adverse effect of acidic mine drainage derived from gold and coal mining operations on the quality of receiving waters is described, together with measures to be taken to counteract this pollution. The mineral load and the toxic effects from metallurgical and metal finishing industries are also considered. Attention is drawn to water conservation aspects.

By A. A. Hazell

Mine management by objectives By A. A. HAZELL The author discusses the objective areas of mine management. Setting objectives is seen to be a conscious process which starts at the highest level of management. This enables clear objectives to be set at each lower management level. The methods of setting objectives in the areas of stope production, productivity and manager performance are set out in detail. In the area of manager performance emphasis must be placed on the practice of management. It is concluded from results obtained that "management by objectives" produces better than average perormances.

By D. G. Hulbert, D. Tudors, M. L. Coetzee, I. K. Craig

The paper describes how a multivariable control scheme was developed and implemented for the run-of-mine milling circuit at a gold mine belonging to Vaal Reefs Exploration & Mining Company Limited. The key variables that are controlled are slurry level in the sump, mass of material in the mil, and product size. The control scheme has resulted in reliable control of the dynamics of the plant, and has provided a good basis for the optimization of plant operation by the selection of suitable set Points.

Jan 1, 1990

By C. J. Van Niekerk, C. C. Begley

SYNOPSIS The paper opens with brief descriptions of the history, occurrence, and regional geology of South Afri¬can zinc deposits, and follows with descriptions of the resources, mining methods, and processes for the concentration of the sulphide minerals and the extraction of zinc as practised in South Africa. The end uses in the form of alloys or as salts are given in some detail. Statistics on the production and consumption of zinc in South Africa are given, and the current market situation and future prospects are discussed briefly.

Jan 1, 1991

By B. Rohrmann

The paper deals briefly with the history of vanadium, and its uses, price movement, and world resources. It then describes the titanomagnetite ore of the Bushveld Complex, and the production of vanadium from this ore at Highveld Steel & Vanadium Corporation Limited, giving details of the various processes used, including the roast-leach, rotary-kiln, electric-smelting, shaking-ladle, and basic-oxygen-furnace operations. The paper concludes with a very brief account of the treatment of Highveld slags in Europe for the production of vanadium pentoxlde and ferrovanadium.

Jan 1, 1985

By R. Hutchings

The paper reviews current understanding of the effect of ion implantation on the wear process, and the state-of-the-art of ion implantation as a commercially viable treatment to impart wear resistance. Ion implantation involves the firing of high-energy ions into the surface of a material, which modifies the surface properties and so causes a transition in the dominant wear mode. The process is best suited to specialized engineering applications involving critical dimensional tolerances or surface finishes, but has gained little industrial acceptance because of its poor reproducibility and the lack of a suitable method of inspection.

Jan 1, 1986

By A. Whillier

Recovery of energy from the water going down mine shafts by A. WHILLIER, Pr. Eng., Se. D. (M.I.T.) (Fellow) The influence of energy-recovery systems on the rise in temperature of water going down mines is examined. It is concluded that the, cost benefit of such systems, deriving partially from the reduced temperature rise in situations where cold water IS sent underground from surface, would more than justify the installation cost.

Jan 4, 1977

By B. Strohmeier

The role of large, ultra-high-powered arc furnaces in a fully integrated steelworks for the production of flat products is outlined, and an account is given of the technological improvements that have been implemented over the past few years to enable the arc furnace to remain competitive against the conventional route using blast furnaces and top-blown-oxygen steelmaking (LD). Modern secondary refining facilities have been installed, enabling the arc furnace to operate at high production rates in the manufacture of high-quality flat products.

Jan 1, 1985

By J. A. Ryder, M. U. Ozbay

An ERR-based methodology is presented for use in the re-assessment of the performance of stabilizing pillars, taking into account the effects of fracturing that can occur in pillar foundations under conditions of high stress. It is shown that the damage in the foundations of under-designed pillars can cause up to 30 per cent increases in ERR compared with the ERR for pillars with unfractured foundations. Despite this reduction in assessed performance, stabilizing pillars are still generally found to result in substantially lower ERR levels than alternative methods of reducing ERR, such as the use of stiff backfill or backfill ribs.

Jan 1, 1990

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 S. J. Webber

This paper reports on the use of the MINSIM-D stress-analysis program for the modeling of two large seismic events that occurred on the same fault eleven years apart. It was found that the first event (magnitude 5,2) could not be ascribed to purely mining-induced stresses, indicating that the largest seismic events probably result from the interaction of mining-induced stresses with large scale tectonic stresses. However, the stress changes induced during eleven years of mining were found to be capable of generating sufficient excess shear stress (ESS) to be responsible for the second event (magnitude 4,3), The upper limit for the magnitude of purely mining-induced events was found to be approximately 4,3.

Jan 1, 1990

By R. J. Dippenaar, W. H. Van Niekerk, D. A. Kotze

It is generally accepted that alkalis attack and degrade the carbon fraction of coke in a blast furnace. Because South African cokes contain relatively high amounts of ash, the influence of alkalis on the ash fraction was investigated, the carbon and ash fractions being separated and studied separately. Potassium engenders the formation of liquid, with a resultant expansion of volume and a decrease in the strength of the coke ash. However, the ash did not play a significant part in the degradation of the coke, and it was found that the catalytic effect of potassium on the Boudouard reaction was the overriding factor in the coke-degradation process.

Jan 1, 1986

By R. M. Morris, G. A. Matthesius, M. J. Desai

Slow pyrolysis experiments were caried out on samples of coal from north em Natal having a volatile mater content ranging between 10 and 25 per cent by mass and a constant particle-size distribution. The tests were conducted at atmospheric pressure in a helium atmosphere, and ata heating rate of 10 KImin and a final temperature of 1220 K. The pyrolysis products were taken as coke and volatile mater (tar and eight other species), and tMir respective yields were measured. The experimental results were used in the modification of an existing mathematical model and in the derivation of new corelations for some of the parameters of the model, so that the volatile products of a coal can be predicted from ultimate and proximate analyses of the coal. The pyrolysis tests showed good agreement between the model predictions and the experimental results.

Jan 1, 1987

By J. P. Hoffman

This paper describes the metallurgical aspects and properties of a duplex austenitic-ferritic steel SAF 2205. As well as having high yield strength and hardness, SAF 2205 combines the high resistance of ferritic stainless steels to chloride-induced stress-corrosion cracking and the excellent resistance of austenitic stainless steels to hydrogen-induced stress-corrosion cracking. Its alloying elements contribute to its mechanical and corrosion properties as follows: nitrogen increases its pitting potential and improves its strength, nickel increases its resistance to pitting and its toughness, chromium and molybdenum give improved resistance to pitting and crevice corrosion. SAF 2205 has better resistance than steel types 316 Land 317 L both to pitting corrosion and to stress-corrosion. This makes it a very good material for pipes, tanks, and pumps in harsh environments such as those in petrochemical and desalination plants.

Jan 1, 1986

The aspect ratio (mill diameter/mill length) of autogenous and semi autogenous mills varies widely and can be as high as three or as low as 0.5. The literature on the subject of what effect aspect ratio has on grinding mill performance or energy efficiency is almost non-existent. However, at the design stage of many grinding circuits the subject is often vigorously debated amongst metallurgists. In this paper the performance characteristics of mills with different aspect ratios are examined to determine whether process performance characteristics are a function of aspect ratio and whether high aspect ratio mills are any more or less energy efficient than low aspect ratio units. Data from both pilot and full-scale mills are used for this purpose in open and closed circuit configurations.

Jan 1, 2007

By R. D. Beck

The minerals industry needs the support of al sections of the population if it is going to be able to supply the new materials required for future development. It will achieve this support only if its image is good. Perceived images of the minerals industry are examined in respect of history, technology, environment, safety, education, and economics. Concern is expressed about the low technological image of the industry and the declining number of students enrolling in minerals-related disciplines. It is concluded that it is the professionals, through institutes like The South African Institute of Mining and Metallurgy, who must take the lead in improving the image of the minerals industry. The Presidential Address gives data to support this thesis; data that, is hoped, can be used in efforts to educate people about the minerals industry.

Jan 1, 1991

By G. Gafner

The paper gives the reasons for the development of a gold alloy of 990 fineness with good colour, durability, and mechanical properties, and explains why titanium was chosen as the alloying metal. Methods are described for the alloy?s production, solutionizing, and age-hardening. Mechanical properties are given as a function of deformation, age-hardening time, and temperature for three different starting states, and these properties are compared with those of some standard 14 and 18 ct jewelery alloys and pure gold. The effects of various salts and fluxes on the composition of the alloy after heat treatment at 1150, 800, and 500°C are discussed. These indicate how alloy scrap can be refined to pure gold, and how solutionizing and agehardening can be conducted without the use of vacuum equipment. The results of wear tests indicate that the alloy is more durable than normal coinage and jewelery alloys. Tips are given on the grain refining, soldering, and casting of the alloy.

Jan 1, 1989

By P. J. Kinver

This paper deals with the development of the cut-and-fill mining method at the Broken Hill orebody of Black Mountain Mineral Development Company (Pty) Limited, at Aggeneys in the north-western Cape Province of South Africa. Lead, copper, zinc, and silver are produced. Production started in January 1976, being confined to blasthole production methods in the upper, steeply dipping areas of the orebody. This blasthole reserve is 70 per cent depleted, and pillar extraction is in progress. The balance of the production tonnage, 60 kt per month, is produced from three cut-and-fill stopes situated in the flatter-dipping areas of the orebody. The cut-and-fill mining method at Black Mountain is a result of research and planning activities that included the use of modelling, laboratory tests, mathematical analyses, in situ tests, and experience gained from other mining operations. These investigations and the resulting developed methods and designs are summarized in the paper.

Jan 1, 1985