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By D. S. Loubser

The technique of backfilling in the gold mining industry is dependent on the dewatering of slurry to form a solid support system. In many cases flocculants are added to the slurry to increase the rate of dewatering. To ensure that a stable support is obtained it is important that the chemistry, application and limitations of these flocculant additives are understood. Flocculant additives have to be added at a point where minimum shear will occur. (Shear occurs when a flocculant is exposed to excess energy resulting in breakdown, of the floc.) To ensure that optimum results are obtained it is important that personnel involved are trained to use the flocculant additives and dosing equipment correctly.

Jan 1, 1988

In a gold CIP/CIL circuit, adding new circuit water to a final tails thickener and then directing the thickener overflow to the head of the circuit significantly reduces the cyanide concentration at the TSF discharge spigot. The new water is used to dilute the final tails. The dilution and recycle of the tails in this manner may have the added benefit of reducing reagent consumption, in some cases to the point where the reagent savings justify the expenditure and Cyanide Code compliance is achieved at no extra cost. Potential circuit configurations and water recycles can be modelled by splicing a flowsheeting and thermodynamics package, such that changes to the composition of the water can be reduced to chemical speciation with a Gibbs free energy minimisation enabling a complete understanding of the circuit water chemistry.

Jan 1, 2007

By Y. G. Che, M. Brown, R. L. Gandhi, M. D. Watson

Slurry pipelines have proven to be an economical method of mineral concentrate transport over long distances. Some of these pipelines are internally lined with high-density polyethylene (HDPE) to avoid internal corrosion. HDPE is an inert and extremely smooth material, and it was believed hat scale deposits would not form on it. However, there have been instances of scaling on HDPE lined pipes. Scale problems have also occurred on bare steel pipes. In this paper experience with scale problems in some of these pipelines will be summarized. Alternatives available for control of scale problems will be discussed, and a success story for the control of scale problems in the 300 km long Century zinc and lead slurry pipeline will be presented.

Jan 1, 2007

By J. Trcková

This paper describes the method of modelling rock mechanical problems on experimental models. Based on an actual experiment used as an example, assessment of the surface deformation due to undermining, the extensive possibilities of using a 3-D physical model and application results in practice are demonstrated. A special method of modelling the underground mine progress by using paraffin melting is presented. Keywords: undermining, subsidence of surface, 3-D experimental model

Jan 1, 2009

By L. Wade

The advent of relatively cheap computing power has precipitated a rapid growth of computer usage in the mining industry. In order to obtain most benefit from this development a need is recognised for the future mining graduate to be trained in computer literacy. This paper outlines the type of training required and describes progress to date with such a programme at the University of the Witwatersrand. Certain challenges concerning the teaching effort are discussed.

Jan 1, 1987

By C. J. Van Niekerk

When gold plant residues are cycloned for producing a coarse product for backfilling the gold and uranium values are upgraded in the backfill product. Gravity concentration, wet high intensity magnetic separation and froth flotation were investigated as first-stage recovery processes to recover these economic values from backfill prior to placement underground. This paper addresses the recovery of values from flotation concentrates and also details the economic feasibility of a treatment route including flotation, followed by roasting of flotation concentrate to liberate gold entrapped in pyrite and reverse gold leaching of the calcine so produced.

Jan 1, 1988

Stochastic methods are normally invoked / used to assist with the understanding of risks, when there is uncertainty around a particular outcome. Uncertainty implies that there is a risk that the desired outcome will not be realized. Stochastics and probability theory has long held out the promise to answering this need, but has often been maligned because of its misuse. This paper takes a critical look need for Monte Carlo simulation to project risk evaluation and highlights what is considered to be the fundamental issues that should be thoughtfully considered to avoid the abuse of this technique. The upside of avoiding the abuse of this technique will be the wider acceptance by practitioners that it is a credible technique to quantify this important aspect of valuation.

Jan 1, 2007

By M. B. Cortie

The historical development of materials engineering in the mining industry Is briefly reviewed, and some of the factors currently influencing the industry in South Africa are discussed. Material usages in various parts of the mining operation are surveyed. The predominant mechanisms in the degradation of materials in mines are wear, corrosion, and fatigue. The issue of corrosion-abrasion Is considered, but it Is concluded that abrasive wear predominates in most rock-handling and comminution applications and that, in general, little economic benefit Is to be gained in those applications by the use of existing corrosion-resistant alloys. However, alloys with a measure of corrosion resistance find profitable application elsewhere in the mining environment. The use of other engineering materials such as polymers, ceramics, al1l1inium, and various ferrous alloys may be economically viable in a variety of niche situations. Identification of the most cost-effective material in each case calls for a systematic approach and some patience.

Jan 1, 1996

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 M. Thurston

This case study shows that for a set of lognormal data with a low coefficient of variation the semi-variogram of the logs has almost the same shape as the semi-variogram of the raw data. This means that the variogram of the logs, which is numerically more stable, can be used to krige the raw data. This technique is tested on samples from a sedimentary gold deposit and the results compared to those obtained from ordinary and simple lognormal kriging.

Jan 1, 1987

By E. A. Brinkmann

A kinetic model framework for single particle kinetics in combined diffusion and adsorption processes is presented. The framework applies to the general case in which both diffusion and the adsorption reaction play important roles in determining the overall rate in processes where the migrating species can both adsorb and accumulate. The technique, which should be applicable to a wide range of reaction mechanisms, consists of an iterative integration procedure for the coupled diffusion and reaction equations. The case of a reversible linear adsorption reaction rate is developed. In order to verify the technique as a legitimate method of model development, an analytical solution for the identical case is derived and compared to the numerical solution. Excellent agreement exists between the two solutions.

Jan 1, 1987

By k. Lebecki, S. Trzcionka

The prototype and test results of the instrument for quick determination of incombustible content in deposited dust as a protection against coal dust explosion propagation are presented. Presently existing methods do not permit to obtain quick information about incombustible content, needed for the proper protection of workings. As the operating principle for the e instrument the dependence of reflection of infrared radiation intensity on incombustible content in the sample is chosen. The construction is based on the modern electronics. The measurement will be done at the sampling site. The range of the instrument is 0-100% of incombustible, direct reading, autonomous supply, weight no more than 0.5 kg, and is intrinsically safe according to EN Standards. During the Conference the instrument will be commercialized.

Jan 1, 2003

By G. Whittle

An important aspect of the project evaluation process is the achievement of a clear and quantitative understanding of the primary drivers influencing project value and risk. A business scenario-based approach is required to ensure that the project meets value and risk hurdles over the short, medium and longer term. Adopting an optimising approach can aid significantly in the development of a project concept into a business that is optimal and sustainable in the longer term. Through the application of case studies, based on work performed with various mining organisations during the last five years, this paper will demonstrate how project value and robustness can be optimised. Experience has demonstrated that applying this approach results in significant value improvements and risk reduction - primarily by application of a rigorous, fact-based analysis and optimisation process that rapidly increases management team understanding and insight of key driver of value and risk.

Jan 1, 2007

By P. G. Van Der Walt

This paper deals with the reticulation of deslimed tailings from surface to the stope face underground. Reference is made to the experience gained at the pilot plants operating on four of the gold mines administered by Gold Fields of South Africa, as well as at the full-scale system at East Driefontein which was commissioned recently. Mine-wide backfill systems are currently being installed on five other mines administered by Gold Fields. These six full-scale systems are capable of handling more than 270 000 tons of backfill solids per month. The type of reticulation system chosen, the selection of flowrates and the composition of the slurry, as well as the selection of the appropriate pipes and ancillary equipment are discussed. Both theoretical and practical aspects are taken into consideration. Other aspects covered include the design of underground storage dams and communication systems.

Jan 1, 1988

Project evaluation is completed through individual studies covering technical and financial aspects of the mine to market. These studies are completed at various levels of detail depending on where the project evaluation is in the project's life cycle. The competency of the studies varies in relation to the quality of data, level of the skills employed, control, management and reporting structure. The focus of this paper is managing elements of the study, looking at the cost of opportunity to influence the project, against the value added. Selection of the study manager and study teams is central to getting an integrated project evaluation addressing the correct issues completed on time. Retention of key personnel can reduce rework which, in turn, can reduce time and cost impacts. It is important to have a work breakdown structure at the outset so that the study teams have a common numbering and naming system that will integrate areas, equipment, budgets estimates and accounts. Having set up the evaluation groups and provided training in the study procedures, understanding the scope and schedule are vital elements in producing a project evaluation that addresses the opportunities and the risks of the final project. Arriving at an accurate capital budget requires integration of the research controlled through common systems. Project evaluation process must also address how the project is to be delivered.

Jan 1, 2007

By Stephen Hughes

Ausmelt Top Submerged Lancing (TSL) Technology has gained widespread commercial acceptance in the lead and zinc industries, as an efficient and highly flexible pyrometallurgical reactor with accompanying excellent environmental performance. For the processing of lead and zinc bearing feed materials twenty one (21) Ausmelt furnaces are now in operation, under design or under construction. With recent increases in the value of both lead and zinc and an ever increasing focus on the sustainable use of resources, interest in the processing of secondary feed material sources as well as metal containing residues has substantially increased. Ausmelt Technology has proven to be well suited to the economic recovery of values from such sources. This has for example culminated in Ausmelt?s commitment to the Whyalla Zinc project as the owner/operator of a facility for the treatment of zinc bearing secondary feeds. This paper describes Ausmelt?s recent developments in the fields of lead and zinc processing, as well as further investigations into new processing areas, including the direct smelting of zinc concentrates. Ausmelt?s TSL Technology can now be regarded as Best Available Technology (BAT) for metal production.

Jan 1, 2008

By W. D. Grimsley, R. P. King, J. B. See

Samples (15 to 20 g) of pre-calcined Mamatwan manganese ore or pure Mn 304 smaller than 48 mesh were reacted at temperatures in the range 1000 to 1300°C with samples of spectrographically pure graphite smaller than 325 mesh. Samples (1 g) of ore or pure Mn02 smaller than 48 mesh were reacted at temperatures of 1000 and 1200°C with pure graphite fines in argon, with graphite in carbon, .'1onoxide, and with carbon monoxide alone. In each case, the loss of mass as a function of time was recorded with a hermobalance. The rate and degree of reduction were found to increase with additions of carbon and with increasing temperature up to 1300oC, when they reached their maximum. The shape of the reduction curves, together with the results obtained from examination of the products of reaction by microscopy and X-ray diffraction, were used as the basis for a postulated reduction mechanism. Some details are given of an initial kinetic model that was used to verify the proposed mechanism. It was found that the reduction of Mamatwan ore by graphite at temperatures in the range 1000 to 1300°C occurs in two stages: (i) an initial stage during which the higher oxides of manganese are rapidly reduced to MnO with concurrent formation of CaMn2O4 and (ii) a longer stage during which CaMn2O4 and MnO are reduced to carbides by carbon dissolved in the ferromanganese phase.

Jan 1, 1978

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

Orebody modelling and reserve estimation are now subject to sophisticated procedures, but folded stratiform and stratabound deposits present particular problems in transforming coordinates of samples and blocks into their correct relative positions prior to deformation. In this paper an approach is taken whereby a geologically interpreted reference plane is used as a control. The study area is the Rio Tinto Minera copper mine near Santiago de Compostela, Spain. The transformation procedure on the 'unfolded' state is described, its limitations assessed and advantages considered.

Jan 1, 1987

By S. Shamaila

The design and efficient operation of density-based mineral processing units requires regular densimetric analysis to be carried out on the various associated process streams. The results obtained from such analyses can have wide application, including the generation of washability and partition curves, which are critical for process design, control, and simulation. This paper describes some of the collaborative efforts that Kumba Iron Ore, in partnership with Springer New Technology and Anglo Technical Solutions Research, is pursuing in developing a novel density determination technique exploiting X-ray transmission (XRT) and optical imaging. This technique is being developed with the aim to determine sample density distributions that apply to washability characterisation of ores. This technique is aimed to be an alternative to the traditional sink and float method. For certain applications sink and float has required the use of tetrabromoethane (TBE) solution?a chemical that has been classified as harmful and environmentally unfriendly. This paper therefore presents some achievements in developing this novel technique which seems to be very promising.

Jan 1, 2012