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By D. B. Paterson

In view of decreasing head grades, the relatively high gold price, and recent developments in metal evaluation, an exercise was initiated to determine the extent of gold concentration, the mode of occurrence, and the areas of concentration within the run-of-mine milling circuits of Randfontein Estates Gold Mining Company (Witwatersrand) Limited. The total gold content of three of the thirteen run-of-mine mils in the Group was measured as a typical lock-up of approximately 200 kg per mil. The majority of this gold was concentrated either behind the grid-type body liners or within the pockets of the body liners. This paper is an account of the experimental procedure and the results obtained, and highlights possible means of limiting gold lock-up in future.

Jan 1, 1988

By Z. Zitron

In 1978 the South African Coal Processing Society (SACPS), together with the Institute for Energy Studies of the Rand Afrikaans University, ran a school on coal processing. This was judged by both the organizers and the participants to have been extremely successful. As a result, it was decided to hold a second coal school in 1980. NIM reports Report no. 1958 A mineralogical investigation of sulphide-bearing chromitite from the Loskop Dam ar..a.(10th Feb., 1978; reissued 1st De!)., 1980). Report no. 2067 List of unrestricted NI M publications issued from 1966 to 1980. Report no. 2076 Wet high-intensity magnetic separation. Laboratory tests conducted in 1978 and 1979. Report no. 2083 The determination, by anodic-stripping voltammetry, of zinc and lead in six NIMROC reference samples. Report no. 2086 An automatic sampling probe for use in the carbon-I npulp process.

Jan 1, 1981

By L. Bloch

Most mine safety initiatives in South Africa are doomed to limited success because of one simple fact: they are a-historical and un-cultural and do not deal with the serious ?legacy issues? that still negatively impact on safety, production, and relationships. We in the SA mining industry continually use imported, foreign safety concepts and systems that will not work fully in a South African context. ?The 4th Wave: Culture-Based Behavioural Safety?, as developed by Lance Bloch, an international award-winning clinical psychologist with 12 years? experience in the mining industry - focused mostly on Platinum - is making waves. He has been very successful in creating people-centred, empowered, high-performance safety cultures wherever he has worked. Not only does the 4th Wave transform the corporate culture of a mine, improving safety and production and building an environment of Ubuntu, but it also uses people?s cultures as a means of winning hearts and minds in the battle for safe production. Powerful relationships are built through engagement at all levels, leading to all being focused on the best needs of the company and its constituents as a whole. The programmes are no less than nation-building - something most necessary in the industry, with the pressures from community, unions, the DMR, and politicians. This presentation will describe and discuss the 4th Wave as an advance on previous safety technology and programmes, as particularly relevant to platinum mining in South Africa today.

Jan 1, 2012

By Gerard de Vries

pipeline industry and are still growing in size. Liquid epoxy and polyurethanes are an excellent choice for whatever the aggressiveness of the substance transported and whatever the harmful outside influences, maximum protection is required. They can be used as coatings on all kind of pipelines varying from the mainline coating to the field joint coating. Compared with traditional systems like dual layer FBE and 3-layer polyolefin there are some benefits to be considered like easiness of repairs, amount of coats, application temperature and film thickness. The interior coating renders the pipe surface so much smoother that considerable savings can be realized in pump stations. Apart from the interior of the pipeline, the industry is faced with new challenges like higher operating temperatures of lines and an emphasis on product benefits in order to save money. Key words: liquid epoxy, liquid polyurethane, phenolic epoxy, pipeline, field joint coating, internal coating, corrosion control

Jan 1, 2006

By Sylvie Poirier

Researchers at Natural Resources Canada (NRCan) CANMET Mining and Mineral Sciences Laboratories (CANMET-MMSL) and Mining Technologies International (MTI) have designed and built a hybrid diesel-electric mining loader that is the first of its kind to be developed for underground mines. Diesel equipment is popular because of its mobility and most mining operations are reluctant to replace it with tethered electrical equipment despite the obvious elimination of diesel contaminants and significantly lower heat generation (? 35% of an equivalent diesel). However, a diesel-electric vehicle, being currently evaluated by CANMET-MMSL, could be beneficial. In this unit, a constant load diesel generator feeds batteries which, in turn, powers electrical motors that drive the equipment. In a hybrid diesel-electric unit, the constant load diesel generator can be optimized for minimal emissions and hence lower dilution air requirements. This paper will present the project status and the anticipated benefits for mining operations through the application of this technology.

Jan 1, 2008

By D. Fourie

A brief history of channel sampling in South African gold mines is followed by a chronicle of different sampling events and sampling methods that used the traditional ?hammer and chisel? approach as well as diamond core extraction of the sample. The problems associated with each method of sample collection are documented and the use of a laser scanner to measure the exact volumes of sample material extracted from a correctly delimited sample site are considered. Areas where increment delimitation errors (IDEs), increment extraction errors (IEEs), increment weighting errors (IWEs), and increment preparation errors (IPEs) occur were investigated. A ?simulated chip sample model? is introduced and provides the basis for comparing the percentages of error introduced as a result of improper sampling. The heterogeneity experiment showed that reefs that are more homogenous tend have lower extraction errors than the more complex carbon-rich reefs, which may contribute to understanding the poor mine call factor on mines exploiting the latter types of reef. Keywords channel sampling, chip sampling, error, bias, modelling.

Jan 1, 2014

By J. A. Caldwell, G. E. Blight

The metropolitan area of the Witwatersrand has grown up around the Witwatersrand gold mines. Most of the mines have now been abandoned, but deposits of waste material remain and have been surrounded, and in some instances covered, by urban and industrial sprawl. This paper describes the development of geotechnical measures for the abatement of air and water pollution from abandoned gold-residue dams in the Witwatersrand area. The measures include the stabilization of the surfaces of the dams to prevent wind and water erosion, the terracing of slopes to minimize erosion, and the construction of catchment walls and dams. The measures were developed in terms of the set of guidelines for environmental protection adopted by the Chamber of Mines of South Africa in 1979.

Jan 1, 1983

Material transfer in underground mines often relies on ore and waste pass systems. Over the years the authors have investigated the design and performance of orepass systems in several Canadian and South African mines. It has been recognized that while most mining operations have either implicitly or explicitly clearly defined objectives, in the design and successfully operate orepass systems there seems to be an absence of a strategy on how to best attain these goals. Consequently, it is not surprising that the majority of operations reviewed by the authors experience a number of problems of varying degrees of severity and economic consequences. This is illustrated by reference to both South African and Canadian operations. The second part of this paper focuses on a review of tactical interventions to rectify orepass problems or mitigate their impact. The paper closes with a framework for a flexible strategy for the design and operation of orepass systems. Keywords orepass; orepass design; orepass stability; orepass rehabilitation; orepass operation; orepass strategy.

Oct 1, 2013

By M. J. Nicol, G. Cromberge

An account is given of the development of a relatively simple model that describes the kinetics of the absorption of gold cyanide on activated carbon. The model is based on the treatment of the carbon solution interface as a homogeneous boundary across which gold is transported at a rate determined by the rate of mass transport to and from the interface. Rate equations derived from this model describe the results of various kinetic experiments under continuous or batch conditions in the laboratory and on operating pilot and full-scale plants.

Jan 1, 1983

By M. J. Nicol, G. Cromberge, C. A. Flemming

A relatively simple rate equation for the kinetics of the absorption of gold from cyanide solutions onto activated carbon was lI5ed as the basis in the development of a model for multistage carbon-in-pulp and carbon-in-Ieach absorption circuits. The model was used in the prediction of both the steady-state and the transient behaviour of the absorption process, and the results were found to be in reasonable agreement with those observed in an extended pilot-plant campaign. A number of practical implications of the model are discussed, and an assessment is made of the economic consequences of the various process options available for the design of a carbon-in-pulp plant.

Jan 1, 1983

By M. J. Nicol

The results are reported of experiments on the influence of a number of variables on the rate of loading of gold cyanide onto activated carbon and the equilibrium capacity of the carbon. These variables include the concentrations of gold and free cyanide in solution, the pH value and ionic strength of the solution, the concentration of organic compounds in the solution, the temperature, the particle size of the carbon, and the mixing efficiency. The experiments were carried out under approximately steady-state conditions to simulate the conditions in a countercurrent carbon-in-pulp absorption plant. In addition, the results are reported of experiments to establish whether the absorption of gold cyanide onto activated carbon is a reversible process.

Jan 1, 1983

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 J. H. Venter

The accuracy of estimation from samples of ore in bulk By J. H. Venter Published in the Journal April 1972. ERRATA: Equation (1) should read... Equation (3) should read .... line following "Duscussion" Delete" .... Insert... above "References" "Discussion". Replace .... tenth DISCUSSION M. DA VID Professor Venter has proposed a formula to compute the variance of the estimated grade of a lot of broken ore, and interesting comments on the relevance of the formula and suggestions for developments are made by P. R. Janisch.

Jan 4, 1972

By M. J. Southwood

SYNOPSIS Experiments carried out under atmospheric pressure and temperature (25°C) and sterile conditions show that the dissolution rate of nickel and copper from a pyrrhotite-pentlandite-chalcopyrite ore in a lixiviant of sulphuric acid is greatly enhanced in the presence of pyrite. At a pH value of 1,8 and in the presence of pyrite of equal mass to that of the ore, the recoveries of nickel and copper improved dramatically (21 and 80 per cent respectively). At a pH value of 4,0 the recovery of nickel was enhanced, but the chalcopyrite was refractory. A galvanic mechanism is probable, but cannot be proved from these experiments. The economic implications of the results are discussed.

Jan 1, 1985

By C. A. Snyders

This paper investigates the recovery of platinum group metals (PGMs) from a dilute cyanide leach solution containing base metals, in a manner similar to that used for gold extraction in a typical CIP process, and focuses on both the adsorption and elution stages. The carrier-phase extraction of precious metals using activated carbon offers significant advantages over other processes in terms of simplicity, the high pre-concentration factor, rapid phase separation, and relatively low capital and operating costs. As a sorbent, activated carbon is still by far the most important material because of its large surface area, high adsorption capacity, porous structure, negligible environmental toxicity, low cost, and high purity standards. Adsorption tests were performed on a pregnant alkaline leach solution (0.15 ppm Pt, 0.38 ppm Pd, 0.1 ppm Au) resulting from cyanide extraction performed in column leach tests. The initial adsorption rates of platinum, palladium, and gold were very fast and recoveries of these three metals were approximately 90 per cent after 2 hours and 100 per cent, 97.4 per cent, and 99.9 per cent respectively after 72 hours. The parameters that influence the extraction of PGMs and Au were examined to assess their relative importance during the adsorption process in order to provide the basis for process optimization. The concentration of thiocyanate was not identified as significant factor for PGMs adsorption, while nickel concentration was the most significant extraction process parameter. Base metal cyanide complexes adsorb and compete with the PGM complexes for sites on activated carbon, and while copper adsorption can be minimized by adjusting the residence time, nickel adsorbs at approximately the same rate as that of the PGMs, influencing the loading capacity and adsorption kinetics of the PGMs. The feasibility of eluting platinum and palladium cyanide complexes from activated carbon using an analogue of the AARL process was investigated. Platinum and palladium elute from activated carbon almost to completion in 4 to 5 bed volumes at 80°C, while the elution of gold at this temperature is slow, with a significant amount of gold still to be eluted after 16 bed volumes. Cyanide pre-treatment was found to have a significant influence on PGM elution. Higher cyanide concentration in the pre-treatment step results in more efficient elution up to a point, and experiments suggest the possibility of an optimum cyanide concentration, beyond which elution efficiency starts decreasing.

Jan 1, 2012

By H. Zhong, S. Wang, Q. Sun

The flotation performance of 2-(benzylthio)-acetohydroxamic acid (BTHA) to diaspore was first evaluated by micro-flotation tests. The adsorption mechanism was further investigated through adsorption experiments, molecular dynamics simulation, zeta potential and X-ray photoelectron spectroscopy (XPS). The results demonstrated that BTHA had a stronger ability to collect diaspore in comparison with another diaspore collector, benzohydroxamic acid (BHA), especially under the condition of weak alkalinity, the flotation recovery can reach 90%. The more negative interaction energy (ΔE) between BTHA and diaspore from molecular dynamics simulation results revealed that BTHA had an easier adsorption ablity onto diaspore than BHA, which matched with adsorption results. The zeta potential and XPS revealed that Al atoms might bond with -C(=O)NHOH by formation of Al-O bonds. Keywords: Diaspore, flotation; adsorption; 2-(benzylthio)-acetohydroxamic acid

Jan 1, 2020

By D. I. Nicol

An assessment is made of the possible scope for the use of activated charcoal as the solid adsorbent in an upflow fluidized-bed contactor, and a pilot-plant programme for the recovery of low concentrations of dissolved gold in this contactor is described. It was found possible to produce an effluent that contains less than 0,01 p.p.m. of dissolved gold.

Jan 1, 1997

By P. J. D. Lloyd, Jill Urban, M. R. Urban

The adsorption of gold from cyanide solutions onto constituents of the reef, and its role in reducing the efficiency of the gold-recovery process by M. R. URBAN. M.Sc. (Chem. Eng.) Rand (Visitor). JILL URBAN. B.Sc. (Chem. Eng.) Rand (Visitor) and P. J. D. LLOYD. Ph.D. (Cape Town) (Fellow) Evidence for the adsorption or re-precipitation of gold from cyanide solutions onto gangue minerals of the Witwatersrand reefs has been gathered over a number of years by various investigators. The evidence from tests using radioactive tracers is conclusive and indicates thlt adsorption contributes about 0,1 g/t to the total gold loss from conventional reduction works. The loss is a function of the alkalinity and cyanide concentration of the solution, and it appears to be affected by the extent of time between milling and cyanidation. The heavy minerals appear to be the strongest adsorbers, and the clay minerals somewhat less strong adsorbers. A sensitive qualitative test based on thin-layer chromatography permits the extent of adsorption and desorption to be readily determined.

By A. Marek

Reduced downtime and maximized availability of mining machines are the key factors in optimizing production rates. As technology moves industry towards an age of ?intelligent machines? it sets the foundation for change in mining equipment design, functionality, and maintenance. Recent mining machine designs are integrating more and more electronic components into the core functionality of individual piece of equipment due to regulatory and legislative requirements, such as TIER rating, as well as from a safety aspect such as personal detection systems. This paper describes the use of existing on-board electronic equipment to increase machine availability through automated maintenance planning and diagnostic fault-finding capability. The automated maintenance planning takes place on the machine itself in order to be independent of the mine?s infrastructure, while the diagnostic capabilities allow for reduced downtime. The paper also presents a concept to transfer operational data to surface to be able to optimize planning of maintenance and to reduce downtime. Case studies are presented where such systems have been commissioned and are currently in operation, the possibilities of this technology application for the future are examined.

Jan 1, 2012

By C. G. Anderson

Throughout the world, there are many orebodies or materials which have significant value but also contain arsenic, antimony, and mercury. As regulations on the transport, exposure, disposition and emission of these elements have become more stringent; it has become increasingly more difficult to derive the values from the resources. This paper outlines the fundamentals of alkaline sulfide hydrometallurgy and its successful application to arsenic, antimony and mercury bearing ores, concentrates, by-products, and other materials.

Jan 1, 2008