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By I. J. A. Brackley

An investigation of the slope stability of a pit and failures of spoil dumps, carried out at Silicon Smelters quartz mine, Pietersburg, South Africa, is described. The major geological feature of the mine is the intensely foliated schist in the footwall, with exceptionally Iow strengths upon extensive discontinuities, and the similarly unusual strength properties of the dumped schist spoil. The selection of slope angles for the pit is described, and a proposal for the stabilization of the failing spoil dump by segregated dumping is explained.

Jan 1, 1985

By B. R. Broekman, J. P. W. Bennie, P. D. K. Robinson, R. P. Viljoen

The theme of the Congress was 'Resources and Technology', the intention being to highlight those basic technical aspects in the disciplines of geology, mining, extractive metallurgy, and metals technology that are required for successful mineral-based operations. The technical programme covered a fairly broad field, as is appropriate for the CMMI Congress, and was generally considered to be of a high professional standard; informative and, with the exception of some minor hitches, well-run. Parallel sessions were held in the four disciplines. All were well attended, and despite tight presentation schedules, certain valuable discussions developed.

Jan 1, 1994

Discussion of the above paper by G. J. van JAARSVELDt Mr Ortlepp's paper is important, and deals with a subject towards which much controversy and insufficient basic scientific logic, in my opinion, have been directed. He attempts to remedy some of our unscientific popular misconceptions, and for this we thank him. However, I regret to say that experience has shown that some of his statements cannot be allowed to pass unchallenged. Author's reply Mr Van Jaarsveld's contribution is welcome because it provides an opportunity for me to clarify certain points that were perhaps not adequately explained in the paper.

Jan 1, 1979

By H. Wagner

The paper points out that bord-and-pillar mining is the most important method of coal extraction in South African underground coal mines, and advocates that pillar design procedures should be refined to make more rational allowance for the differences in strength properties between various coal seams and roof and floor strata. However, any deviations from well-established design procedures must be based on sound engineering principles and reliable data on the strength properties of the seams and strata concerned. Recent information indicates that practices for the protection of surface structures against underground mining should be revised.

Jan 1, 1980

By J. A. Wates

Stope backfilling in South African gold mines uses the coarser cyclone fraction of the gold tailings. The disposal of the overflow from the cyclones, which is finer and of higher moisture content than normal gold tailings, presents some problems. This paper describes an investigation undertaken to define the parameters that are required for a quantitative and qualitative assessment of the operation and stability of slimes dams built of such material. However, seeing the investigation was conducted on the slimes from only one mine, it is recommended that, until a wider range of data becomes available, tests should be conducted for each individual mine.

Jan 1, 1988

By J. H. deur Potgieter

This paper, 'A review of the biological treatment of cyanide-bearing waste water' discusses the necessity for the treatment of cyanide-bearing waste water with a view to the avoidance of environmental pollution, and the limitations of the available chemical and physical processes are referred to briefly. The sources of cyanide-bearing waste waters are mentioned. The mechanisms of production and utilization of cyanide by fungi and bacteria are discussed. The work done in connection with the biological removal and destruction of cyanide is summarized, the successes achieved are described, and the relevant processes are listed. In conclusion, some advantages of biological processes for the removal of cyanide are mentioned.

Jan 1, 1991

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 C. J. Fauconnier

The various methods of detecting fires and heatings in collieries are reviewed. The methods described range from those relying principally on human senses to sophisticated methods employing infrared technology to detect traces of the products of oxidation and combustion. The advantages and disadvantages of various gases employed as indicator gases for the early detection of heatings and fires are discussed, and recommendations are made in this regard. The operation of a modern infrared carbon monoxide detection system is described, and the differences in operation and application of telemetric systems, tube-bundle systems, and up cast-shaft monitors are discussed In conclusion, some indication is given of the capital outlay required for typical early-detection systems.

Jan 1, 1981

By J. T. Davies

Note: Melting techniques in the iron foundry by J. T. DAVIES* INTRODUCTION The selection of melting equipment for use in an iron foundry has for several years been the subject of numerous discussions, papers, and conferences. The controversy that has raged throughout the world has been brought about by the following factors: IF AC Symposium The 2nd IF AC Symposium on Automation in Mining, Mineral and Metal Processing will be held from 13th to 17th September, 1976, at the Carlton Hotel, Johannesburg. Advance registration takes place on 12th September, 1976. World phosphates The Minerals Bureau of the Department of Mines has released the second publication in its series of reports on the economic aspects of minerals that are of particular importance to South Africa.

Jan 7, 1976

In order to test the applicability of elastodynamic codes in the modeling of mining related problems, comparisons are made between seismic data and numerical analyses. The dynamic finite difference program WA VE is used for the modeling of a horizontal stope in a deep mine. The slip along a vertical fault situated within the positive excess shear stress lobe of the stope initiates seismic waves. The stope-fault geometry is modeled in both two and three dimensions. The three dimensional non-slip weakening WAVE analyses correlate well with Brune's analytical model. For accurate modeling of the peak particle velocities predicted by McGarr's empirical relationship, it is recommended that a three-dimensional stope -fault model is used, with the amount of slip weakening dependent on the magnitude of the event.

Jan 1, 1995

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 M. I. Brittan, E. J. J. van Vuuren

Computer analysis, modelling and optimization of gold recovery plants of the Anglo American Group by M. I. BRITTAN M.Sc. (Eng.), M.S., Ph. D., (Member). and E. J. J. van VUUREN M.Sc., (Visitor). Multiple correlation and regression techniques are used to analyse gold plant operating records. Key variables m the process which Influence the gold recovery are Identified and assembled into a mathematical model. This constitutes a valuable tool for the optimisation of variables such as the rates of reagent addition and for assessing the economics of extending the plant. Substantial short term economic benefits have been realized. The techniques provide a rapid diagnostic service without interfering with normal plant operation. Quantitative results are presented and their implications examined. The value of the method is discussed.

By G. J. Wright, M. J. Neale

As machines become more complex and vital to our way of life, any disturbance or failure of their proper functioning tends to have serious consequences. To prevent such failures, increasing attention is being paid to techniques for the monitoring of machinery condition or 'health'. Of the many methods available, examination of the lubricant and any particles it contains forms a basis for interpretation of the conditions of operation, and the rate and severity of degradation of the moving parts, in a machine. Many techniques of wear-debris analysis, such as spectrographic oil analysis and ferography, are available indicate the composition, shape, size, and concentration of contaminants in a lubricant. This paper reviews the important aspects of wear-debris analysis as an integral component of machinery condition monitoring, and gives an insight into the selection of appropriate techniques and the information that can be obtained from each.

Jan 1, 1987

By R. Meyjes, P. Davies

Keywords: Pyrometallurgy, furnace, smelter, engineering company Metix is a private smelter engineering company wholly owned by its management. Its main lines of business in the ferro-alloy industry being: - turnkey smelter projects (LSTK) - engineering, project, and construction management projects (EPCM) - specialised furnace equipment comprising: ? complete electrode columns, including forged copper pressure rings and contact shoes, as well as fail-safe slipping devices ? water-cooled roofs ? bus-tube systems ? feed systems ? cooling systems ? linings ? off-gas systems ? tap-hole drills & clay guns - furnace power supply systems - ore agglomeration & sinter plants - feasibility studies & due diligence reports - technical consulting for investment banks - project procurement & cost control Metix management experience includes around 130 combined years of contacts and experience in the South African smelter industries. Over 30 furnaces have been built, for processes including FeCr (high, medium, and low carbon), FeSi, FeMn (high and medium carbon), SiMn (ultra low carbon), Si metal, and FeV.

Jan 1, 2006

By Alan Bauer

SYNOPSIS A discussion is presented of the advances that have been made in rotary drilling in recent years and it is indicated how and why these drills have replaced percussive equipment even in the hardest formations at larger than 7 in. diameter. A method is presented showing how it is possible to estimate drill requirements and how to optimize drilling and blasting costs for a particular situation. To do this it is necessary to have, in addition to drill performance data, a knowledge of comparative explosive performance. Current methods of doing this are therefore critically appraised. As hole diameters have increased for overall drilling and blasting economies the question of fragmentation arises. In North America this has been approached on a try-it-and-see basis giving results that, in general, have been very satisfactory. The current drilling and blasting practices in North America are reviewed and reference made to the factors of importance in slope control.

By A. Ball

This paper addresses the need for a unifying model that will permit the selection and design of optimum materials for a given wear situation. With this objective in view, the characteristics of the various forms of abrasive, adhesive, and erosive wear are described in terms of localized stress, strain, strain rate, and frictional heating. The measured performance of a variety of metallic, ceramic, and polymeric materials and coated or surface treated materials are described briefly. These results were obtained under conditions of dry-particle abrasion, abrasion in conjunction with corrosion, cavitation erosion in liquids, erosion by particles in low- and high-velocity gas streams, and erosion by particles in a liquid stream. Electron microscopy was used extensively, together with microhardness profiles, in the determination of the modes of material detachment and the underlying deformations and structural changes. As a result of the experimental work, a model based upon a critical strain to microfracture is presented. The microstructural features and materials properties that determine wear resistance are discussed.

Jan 1, 1986

By N. Kernahan, T. Zaniewski

Threshold blasting involves the use of small amounts of high explosive to break and fragment hard rock without having to evacuate mining personnel. The method is easily assimilated and effective in rockbreaking, but requires rigid control on drilling, charging and timing. Current underground trials are aimed at fine-tuning the amount of explosive energy and blast hole geometry to allow the firing of multiple sets of shot holes in a continuous manner. Through correct procedures, the after-blast fumes, dust and fly rock can be contained so as to provide a safe working environment. Threshold blasting hugely reduces the volumes of explosives used in mining and brings to maturity the potential of the process begun by Alfred Nobel when he introduced nitroglycerine, and later dynamite, to mining. Its key contribution is its enabling of continuous mining operations with well understood and relatively low cost technologies. The use of batch blasting, employing large burdens holds the greatest potential for delivering high flow rates of ore at minimal cost. There is good potential for rapid evolution of the concept.

Sep 1, 2001

By P. R. Labrum, H. A. D. Kirsten

The literature on shotcrete is reviewed with the object of identifying aspects that have not been addressed specifically in terms of its structural performance and manufacture as applied to underground mines. The programme and results of a series of full-scale tests on mesh- and fibre-reinforced shotcrete panels are presented, from which it is concluded that fibre-reinforced shotcrete is competent, especialy at large deformations, and is equivalent in structural performance to mesh-reinforced shotcrete for a fibre content of 3 per cent by mass: furthermore, that the support design systems developed for mesh-reinforced shotcrete are directly applicable to fibre-reinforced shotcrete. The Q-NATM system for the design of temporary tunnel support is presented briefly as one such system. It provides for the integrity of the excavation to be considered in terms of its competence and displacement determinateness, and represents the first systematic procedure for the design of temporary tunnel support. Finally, the support designed on the basis of the Q-NATM system for the main and cross-cut tunnels on the production level in the proposed BA5 block cave at Premier Mine is presented as a practical example of the design of fibre-reinforced shotcrete as part of an overall support system.

Jan 1, 1990

By D. Limpitlaw

As coal mining often results in the generation of acid mine drainage (AMD), careful planning and management of the water on such mines is required. A colliery in Mpumalanga recently sponsored independent research into the pollution-ameliorating potential of a natural wetland that has been receiving AMD for at least two decades. Samples of the sediment collected in the wetland were subjected to nine stages of sequential extraction in a determination of the distribution of the metal species present. The samples were then analysed for aluminium, iron, and manganese. The concentrations of sulphate-reducing bacteria (SRB) were also determined. The SRB concentration was found to increase with distance downstream (away from the source of pollution). An analysis of the sediment speciation data indicated that metal immobilization may be optimal in areas where the organic adsorption of metals is at its greatest. The analysis also provided evidence of the biogeochemical improvement of the water quality as the AMD passed through the wetland environment. The metal species present did not correlate strongly with the SRB populations; nor did the soluble species correlate with the species formed over long periods of time.

Jan 1, 1996

By Austin Whillier, Duncan Mitchell

The problem of heat stress underground in the gold mines is approached on the basis of the heat transfer between the human body and the underground environment. Experimental measurements of radiant and convective heat transfer and a theoretical calculation of maximum evaporative heat transfer enable the maximum cooling power of an environment to be calculated in terms of the dry-bulb and wet-bulb temperature, the mean radiant temperature, the wind speed and the barometric pressure. For most underground applications the cooling power can be expressed as a function of wet-bulb temperature and wind speed only. The relative importance of wind speed and wet-bulb temperature can be assessed: in working places where wind speed is low additional cooling of workmen can be achieved better by increased wind speed than by decreased wet-bulb temperature. The wet kata reading proves to be of limited value as an index of heat stress because environments with equal wet kata do not necessarily have the same cooling power. Finally, thermal equilibrium with the environment is possible when cooling power equals or exceeds the rate of metabolic heat generation. The rates of metabolic heat generation for various underground tasks are indicated.