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By P. J. D. Lloyd

An account is given of the development of a process to concentrate gold and other valuable minerals and to produce a discardable waste. In this process, the ore is coarsely milled, a bulk flotation concentrate is prepared, and the flotation tailing is scavenged in a hydrocyclone, which returns coarse gangue, moderately coarse valuable minerals, and locked valuable minerals back to the mill. The engineering developments required by this circuit in order that it will fit underground, and the progress made towards the achievement of those requirements, are reviewed. If the waste is to be suitable for use as a backfill in a deep-level, flat tabular excavation, it should be capable of being placed hydraulically, and should have both low voidage and high rates of drainage. Such a material could be prepared by the fine screening of the overflow from the cyclone in the proposed circuit. Possible methods for the handling of the concentrate and the recovery of its valuable constituents are described. The paper concludes with a discussion of the possible benefits from the use, in deep-level Witwatersrand mines, of a system involving concentration underground, extensive backfilling using the tailings from the concentration process, and hydraulic hoisting of the concentrate.

Jan 1, 1979

Gold Fields is the world?s fourth largest gold producer with operations in South Africa, Australia, Ghana and South America. All of Gold Fields? South African Operations are located in the Witwatersrand Basin and are intermediate to deep level underground mines exploiting gold bearing, shallow dipping tabular orebodies, which have collectively produced over 50 kt (1,608 Moz) of gold over a period of more than 100 years. Although the use of Monte Carlo as a business tool was introduced in 1964, it has only been in the last 30 years that it has gained increasing acceptance within the mining industry. However, the application thereof has been mostly limited to determination of risk in project areas. This paper however, considers the possibility of using Monte Carlo simulations to asses the underlying ?Root Cause? criteria critical to the operations management of existing mining operations. Currently, working operations have a distinct advantage over project areas as they have a wealth of historical information at hand. This, in turn, can be utilized to model distributions and relationships that can be used in Monte Carlo simulations, the results of which can be analysed to determine areas of concern. Projects can then be set up to ameliorate the effects of these and in turn reduce the risk of not achieving the operational targets. It is here that it must be stated emphatically that it should be the ?root causes? and the associated relationships that need to be emplaced within the model in order to achieve results that reflect the true causal relationship. The paper outlines possible sources of ?root cause? relationships and considers the outcomes of these in a case study on a large South African Gold Mine.

Jan 1, 2009

By J. A. C. Diering

All underground openings are three-dimensional, and in many cases it is not valid to analyse two-dimensional sections. This has been a problem in the past owing to the magnitude and complexity of three-dimensional stress analysis. In this paper a three-dimensional boundary element approach, using non-conforming quadratic elements, which is specifically applicable to underground excavations, is described. In addition, the philosophy of application of stress analyses is discussed. Three case histories are presented to demonstrate the practical nature of the approach as a tool in solving mining problems.

Jan 1, 1987

By M. M. Oosterveld

Diamonds are mined from ancient raised beach deposits in southern Namibia where complex geological controls have resulted in patchy diamond distribution, largely related to irregularities (trapsites) in the bedrock. The distribution of the number of diamonds per sample is a discrete, reverse- J shape distribution which can be characterized by two parameters. These parameters have been transformed into a Beta and Theta Contribution which can be interpreted as reflecting the 'quantity' and 'quality' of the trapsites. The relationship of statistical parameters, obtained during the sampling of an ore deposit, to the geology of the deposit is an important element of ore reserve estimation. The large-scale regional trends in the contributions have been explained in terms of the geology.

Jan 1, 1987

By K. I. Afewu, L. C. Woollacott

The design of in-pulp adsorption vessels in the gold industry has, for the most part, been seen as a problem involving the suspension of fine particles o ore in a slurry. The need for the vessel to be designed as a mass-transfer contactor has received insufficient attention. The current series of papers addresses this need The previous paper considered the question of the scale dependence of the film transfer coefficient. This paper examines the mixing considerations that are relevant. A review of the literature and an examination of a limited set of data provide some insight into the mixing conditions needed for the dispersion of the particles of adsorbent. The mixing requirements for the suspension of the ore particles are also considered, and conclusions are drawn in regard to the design of mechanically agitated vessels for gold in-pulp adsorption circuits.

Jan 1, 1995

By J. J. van Vuuren

Pipe-stick support in deep-level gold mines is first described and illustrated, a pipe-stick being a mine pole trimmed to the required size and sleeved by a pipe. An account is then given of an investigation into this form of support that involved load-compression tests in a 1000-ton press, tests in a rapid loading machine simulating rock-burst conditions, a study of the load-compression behaviour of pipesticks installed underground, and a cost evaluation. Pipe-stick support was found to be very effective on the face and to cost less than conventional matpacks.

Jan 1, 1979

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 J. W. Drelich, H. Zeng, L. Xie, X. Cui, Z. Gao, M. Tian, Y. Hu, W. Hu, W. Sun

Flotation is a mineral separation technology that uses the surface hydrophobic difference of valuable minerals and their associated gangue minerals to separate them. The flotation collector adsorbs on the valuable mineral surface to improve its hydrophobicity, and metal ions are usually used as activators to enhance the collector adsorption. Different mineral surfaces show different charging properties and adsorption behaviours with the collector or metal ions. Moreover, the order of adding metal ions and the collector also show significant and different flotation performance for the same mineral. The adsorption or flotation behaviour or both are governed by mineral surface chemistry, such as surface charging and reactivity. In our recent studies, force measurement using atomic force microscopy (AFM) was employed to study the surface charging and adsorption mechanism of metal ions and collectors. By preparing collector-functionalised AFM tips, AFM can directly measure the adsorption strength of the collector on the mineral surface to determine the anisotropy of mineral surface reactivity. The preparation of collector-functionalised AFM tips provides the foundation for further study of the activation role of metal ion in the collector adsorption. The application of AFM for force measurement in the surface chemistry of mineral flotation can provide important information on developing flotation reagents and lays the foundation for the specific regulation of mineral surface characteristics. Keywords: Scheelite; flotation; surface chemistry; AFM force measurement

Jan 1, 2020

By L. Hermansson

Trackless mining at LKAB, Sweden by L HERMANSSON (Visitor) Because the usual means of transporting men and material to the working sites was time-wasting and uneconomical, inclined subways were installed in the Kiirunavaara Mine that permitted the access of rubber-wheeled vehicles to all underground working sites. Men and material could now be transported direct to the working site with no reloading. An increase of 8 to 12 per cent in underground productivity has been obtained by the use of this new transportation system. Rubber-wheeled vehicles are also used in development, production drilling, and loading. In December 1958, the management of the Luossavaara Mine decided to cut the costs of waste-rock haulage. The system of waste transport was the conventional one of shuttle car, rail haulage, and skip hoisting. After consideration of other methods, it was decided to re-equip the mine completely for a system of trackless transport. Results show that mining costs per ton of ore were reduced by 27 per cent, and mining costs per ton of waste were reduced by a spectacular 80 per cent. The new system has proved to be more flexible, and ore grading has been simplified since there is no longer any mixing in ore passes and chutes.

By M. B. Algeo, R. H. A. Plaistowe

A method of forecasting the haulage trucks required for a large open-pit operation is described. Emphasis is placed on the effects of changes in planning and on the complexities of a mining operation that involves many benches and dumping areas.

Jan 1, 1979

By J. P. M. Hojem, C. Dimitriou, N. C. Joughin

This paper describes the design and construction of the first experimental underground rockcutting machine from measurements of cutting forces determined in tests on small rock specimens in the workshop. The deficiencies of this design, revealed by stoping with almost identical rockcutting machines, are described. An account is given of the design and construction of further experimental machines incorporating substantial improvements which made them technically feasible for use in production.

By J. J. Van Rensburg

The commissioning of a test facility for the calibration of anemometers by J. J. VAN RENSBURG (Student Member). After the erection of a commercially produced open-jet wind tunnel for the calibration of the anemometers used in mine ventilation, the wind tunnel was calibrated for routine use. There is a choice of five orifice plates. which, together with a variable-speed fan, can give a measurable range of air velocities in the test section from about 0,05 to 35 m/so The orifice plates were calibrated against a standard pitot tube, and it is now necessary only to measure the pressure drop across an orifice plate and to read off, from a set of graphs, the true outlet velocity in the test section. The paper describes the underlying theory and the test results.

Jan 4, 1975

By X. M. Prevost

A computer system to store, retrieve and process coal borehole and analytical data together with other geological, geographical or topographical information is described. As a result of the large volume and variety of data stored since its inception in 1979, as well as the basic versatility of the system, the National Coal Data Base has been performing a number of new tasks for which it was not originally designed. As considerable sets of data are used on almost every project, the use of statistical application programs has become an important processing tool.

Jan 1, 1987

By N. C. Joughin, A. C. Buckmaster

The use of face conveyors in gold mines by N. C. JOUGHIN. B.Sc. (Eng.). Ph.D. (Wits) (Member) and A. C. BUCKMASTER; M.A. (Cantab.) A mechanized stope-cleaning system has been developed around an armoured face conveyor, which was tested on the surface and in two underground trials. In the second underground trial, an average face advance of 8,5 m per month was obtained with a labour productivity of 27 ca/worker/month on a two-shift blast cycle. Two new face cleaning systems have been built, each incorporating an armoured face conveyor, a loading plough, a collapsible self-advancing barricade, and an integral roof-support system. These are about to be tested. A new type of reciprocating flight conveyor is being developed for stope use. This is cheaper, lighter, and more compact, and exhibits better wear characteristics, than an armoured face conveyor. In the early stages of the trials, this conveyor frequently achieved a singleshift blast cycle. It should be possible to achieve face advances of up to 40 ca/worker/month with a consistent one-shift blast cycle. The use of drill rigs and a self-advancing roof-support system would improve the productivity to over 50 ca/worker/month.

Jan 2, 1976

By P. J. Petit

The strategic mission of the South African mining industry is to extract the mineral assets in an energy efficient, economical and safe manner. Drilling has received particular attention in the last few years. As the operations move away from the power source, conventional and old drilling technology result in poor penetration rates, increased drilling shift lengths, slow face advances and limited stope efficiencies. The need for an alternate mining method, performed by a skilled workforce, to increase productivity, has led to the development of the electric rock drilling system for in-stope mining operations. The focus of this paper is a systematic evaluation of the electric rock drilling system as a function of production and technical parameters, in the platinum orebody. The particular electrical reticulation system is illustrated. Power usage, problems experienced, and solutions are described. The safe use of the recently developed drill is elaborated upon by describing protection devices. The testing and certification process, for approval by the recognized authorities, are documented. The testing and certification process, for approval by the recognized authorities, are documented. The human factor is also considered. Known detrimental factors of high noise exposure, vibrations levels and oil emissions are reviewed. In conclusion, recommendations on future strategies for the implementation of electric drilling technology within the mining and construction industries, is included.

Jan 1, 2006

By K. I. Afewu, L. C. Woollacott

Little is reported in the literature that is directly useful for the interpolation film coefficients for the in-pulp adsorption circuits used in gold metallurgy. This can create a problem if the design or operation of these circuits is to be optimized by the use of simulation techniques. To address this problem, a study was undertaken on the influence of mixing intensity, scale, and geometry on the film coefficient in adsorption systems typical of the carbon-in pulp plants used for gold extraction. This, the first paper deals with the influence of these factors on the film coefficient and shows that the specific power to just disperse the carbon in the slurry is an important variable. This variable is also strongly dependent on mixing intensity, scale, and geometry-a dependence that is dealt with in the second paper in the series. From the informatlon obtained, practical scale-up procedures were developed. These procedures are considered to be applicable to resin-in-pulp as well as to carbon-In-pulp plants.

Jan 1, 1995

By C. S. Northcote, I. F. Buchan, L. F. Baars

In 1969 the Coal Division of the Anglo American Corporation was awarded the tender to supply coal to the new 3000 MW power station to be erected at Kriel, which is situated midway between the towns of Ogies and Bethal in the eastern Transvaal. The coal was to be supplied from the No. 4 Seam in the Kriel Area of the Witbank Coalfield. The No. 4 Seam in this area varies in depth of overburden from 75 m to 6 m, with an average of 55 m. Initially, the mine was planned as an underground mine incorporating a three-shaft system for transporting some 8 million tons of coal per annum to the power station. As the result of negotiations between Anglo and Escom to improve the volumetric extraction of coal from the new mine, the Kriel Division of Anglo Power Collieries was finally planned to produce 4,1 million tons of coal from an underground mine and 4,5 million tons from an opencast mine, with a resultant increase in volumetric extraction. This paper describes the opencast operation at Kriel, with particular reference to the water problems encountered and to the operation of the draglines on sloping ground to a depth of 40 m to the top of the coal seam.

Jan 1, 1980

By L. C. Woollacott

Some of the factors that may influence the reliability of a consistent material balance derived from plant data were investigated, data taken from a sampling of the Iow-grade tin-flotation circuit at Rooiberg A Mine being used as the basis for the investigation. The importance of subjecting a calculated balance to a thorough analysis of its sensitivity to erors in assay and flow rate measurements is highlighted. Several simple guidelines are derived from the analysis of the Rooiberg data, and these appear to be generaly applicable to process-evaluation exercises and to the technique used for the smoothing of material balances.

Jan 1, 1987

By J. -M. Chautru

A geostatistical simulation of a typical mining site for polymetallic nodules in the North Pacific Ocean is presented. This is the first stage in the design of an industrial mining system. Two variables which have a major effect on the orebody's economic potential are considered, namely: the maximum slope of the ground inside a mining block of 50 x 100 m; and the average quantity of nodules on the same support. Two geostatistical problems have emerged in this study. The first is due to the lack of a change of support model for the maximum of a variable. A provisional solution, considering an experimentally accessible 'equivalent' support, is proposed. The second is due to a non-linear link between the two variables. To be able to take this into account in the simulation, we propose a new method based on the decomposition: X = E(X/Y) + Residue (X). Satisfactory results were obtained with this approach.

Jan 1, 1987

By P. Geldenhuys, D. J. C. Taylor, D. C. Page

This paper gives a technical review of the history, occurrence, mining, and metallurgy of iron in South Africa. The reserves of iron ore worldwide and in South Africa are reviewed, and potential new developments In the iron-and-steel industry in South Africa are examined. The paper concludes that the exploitation of lower-grade iron deposits will probably supplement the reserves of high-grade hematite ore in the distant future, and that, accepting this scenario. South Africa will be well placed to provide iron ore for its expected internal steel requirements, as well as supplying quality Iron ore for the export market.

Jan 1, 1988