No description available.

The waste products acid mine drainage formed during coal mining and fly ash from coal burning power generation, pose substantial environmental and economic problems for South Africa. Eskom has developed a remediation system employing alkaline fly ash to neutralize and precipitate heavy metals from toxic acidic acid mine drainage streams. The aim of this study was to assess the microbial diversity in and microbial impact on this remediation system.

No abstract available. / Thesis (M.Sc.Eng.)-University of Durban-Westville, 2000.

No description available.

Prof Peter Alexander Mr Chris Bolsmann

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science, 2017 / Six different plant species that grow in a natural wetland impacted by old gold mining and other industrial activities were randomly selected with surface sediments. These included: Cyperus eragrostis (Nutgrass), Datura stramonium (Jimson weed), Melilotus alba (White sweetclover), Panicum coloratum (Blue panicgrass), Persicaria lapathifolia (Pale smartweed) and Phragmites australis (Common reed). These were used to investigate the levels of mercury in the wet and dry seasons, as well as to evaluate which of the species could be utilized for the remediation of mercury contaminated areas. The results obtained indicated that metal contamination could be determined from sediments and plant tissues. The pH values of the sediment samples were mostly neutral to slightly acidic and the redox potential was high in the wet season. On the other hand the dry season was characterised by very acidic and moderately oxidizing conditions. In summer all six plant species had higher concentration of HgT in sediments, whereas in winter the levels of HgT were elevated in the aerial tissues of the plants. The mercury accumulation patterns differed according to individual plant species and seasonality. Seasonal differences were significant but generally the MeHg concentrations in the wet season were higher in both surface sediments and plant tissues. Mercury methylation differed between species but concentration of MeHg was in general higher in plants with high concentration of mercury in sediments. The conversion of bioavailable HgT seemed more pronounced in tissues of the plants sampled in the wet season unlike those sampled in the dry season. Generally bioaccumulation factors were less than 1 in both the wet and dry seasons for all the plant species indicating that Hg was mainly retained in sediments. The translocation factor values were greater than 1 meaning metals were accumulated fundamentally in aboveground tissues for the plants D. stramonium, P. lapathifolia, P. coloratum and C. eragrostis in both the wet and dry seasons. The small bioaccumulation factors combined with translocation factor values greater than 1 were an indication that mercury present in the sediments was not the only source of mercury for the plant species growing in a contaminated environment. For P. australis the translocation of mercury was heavily influenced by seasonality, however this was not the case with M. alba. All the selected plant species demonstrated the capacity to grow in a heavily contaminated area, where P. australis and M. alba seemed to have developed an exclusion strategy to deal with toxic heavy metals therefore suitable for phytostabilisation. D. stramonium, P. lapathifolia, P. coloratum and C. eragrostis on the other hand exhibited characteristics of plants that can be successfully used for phytoextraction and phytovolatilization. / XL2018

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Masters of Science in Mining Engineering 2016/10/5 / Management does not have an efficient mechanism to test strategic and operational alternatives and to assess the impact of these on the value and underlying trade-off variables of the business. Techno-economic models can be applied for this purpose as they provide a framework for undertaking advanced process simulation and business valuation. The purpose of the research report is to identify key components, principles and best practice as applied in techno-economic models, to improve techno-economic modelling for the purpose of decision-making and business optimization. The integrated techno-economic model requires a mining model with production planning and scheduling abilities. The half-level system method can be applied to create production profiles for different mining options and only after optimisation the best option is taken forward for graphical design and detailed scheduling. A metallurgical model incorporates the logic and efficiencies of the treatment process into the techno-economic model from which the refined products are determined for revenue and costing purposes. The financial model integrates with the mining and metallurgical elements and uses detailed costing models and sound financial principles for operating and capital cost estimates. An accurate techno-economic model includes key cash flow components and applies rigorous valuation practice for investment analysis. Techno-economic models are extensively applied in business planning, major project valuations and stay–in-business project valuations. Learnings from the review of these case studies suggest best practice, which allows the models to be applied to different types of business entities and contributes to the accuracy, consistency and efficiency of techno-economic modelling. Integrated techno-economic modelling is also applicable in strategic planning and mine design optimization as it provides a powerful instrument for decision-making and business optimization. The future of the mining business depends on it as an invaluable direction steering tool. / MT2017

Submitted to: School of Mining Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, South Africa September 2015 / Most coal seams in the Waterberg Coalfield contain medium to high levels of phosphorus in coal. Thermal coal, which has a lower value than metallurgical coal, is produced from these coal seams. Metallurgical coal used as feed for char production has especially stringent phosphorous content specifications. Phosphorous levels vary both laterally and vertically through the coal succession of the Vryheid Formation. If the coal horizons with elevated phosphorus could be identified and selectively removed, significant amounts coal could be saved and utilized as metallurgical coal through the life of the mine. Different mining horizons with regards to their phosphorus content have to be determined to increase the amount of char plant feed coal. Bench definitions and their techno-economic applications are therefore the main purpose of the current investigation. Bench 11 is currently the only source utilized for char plant feed coal. The char plant is therefore entirely dependent on coal supply from Bench 11. This poses a risk on the continual production of char at Grootegeluk Mine. It was determined that this bench is not suitable for char plant feed coal in certain areas of the resource. A high phosphorus coal horizon was identified in the upper portion of the bench. If this coal is removed separately, the phosphorus content of the coal in the remaining portion of the bench would be suitable for char plant feed coal. This alternative step is dependent on the phosphorus distribution in the resource and may therefore not always be effective. No changes to the other bench definitions could be established that would increase the amount of potential char plant feed coal. Three further aspects were investigated: The potential to reduce phosphorus in coal by means of coal beneficiation was determined. Results showed that phosphorus levels in coal cannot be lowered sufficiently by means of coal beneficiation. Secondly, the suitability of using different coal analyses to improve the estimation of phosphorus in coal was investigated. Results showed that phosphorus prediction and analyses cannot be enhanced nor replaced by other coal analyses. Lastly, the importance of Zone 1 as a source of low phosphorous coal was investigated. Zone 1 is currently not part of the mine plan, but if mined, it could be used as a source for blending; thereby increasing the amount of char plant feed coal from the reserves. In certain portions of the resource, utilizing Zone 1 may be the only feasible way of securing the continual supply of low phosphorus content coal. Analytical exploration borehole data of phosphorus in coal is limited in certain areas of the resource. Due to the variability of phosphorus in the coal horizons, more borehole data is required to increase the estimation accuracy of phosphorus in the coal. Based on such data, mining horizons might be changed in future to secure more char plant feed coal.

The platinum market is best understood through a comprehensive analysis of supply and demand. Supply is most significantly affected by production constraints and the erratic draw-down in Russian stockpiles. Total world supply of platinum for 1998 amounted to 5.915 Moz, 64% of which was produced from the Bushveld Complex in South Africa. The remainder emanated from Russia, Zimbabwe, the United States, Canada and the recycling of autocatalysts. Supply is forecast to drop by 320 000 oz in 1999 due to a lower Russian export quota and reduced Zimbabwean production. Demand for platinum is unusual, in that it is sought after both as a store of wealth, and has properties that make it irreplaceable in a host of industrial applications. Current world demand for the metal is driven by a growing Eastern jewelry market and increased use in autocatalysts due to vehicle emissions legislation. Total world demand for 1998 amounted to 5.755 Moz. A predicted steady growth in the consumption of platinum for jewelry and existing applications, together with development of new uses, is expected to result in an annual 250 000 oz increase in demand for 1999 and 2000. The derived supply and demand balance for 1998 shows a small excess in supply relative to demand. This will be absorbed by inventories and is likely to have little affect on price, A significant shortfall of 410 000 oz, however, is predicted for 1999. This is likely to be followed by a further shortfall in 2000 and will drive up prices, impel consumers towards substitution and thriving and encourage producers to expand.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg in partial fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 1993 / Superfines of less than 200 micron are generated when mining coal. They have not been successfully beneficiated in the past and are not acceptable to the consumer. A processh as been developed whereby the superfines are beneficiated, briquetted without the use of binders and devolatilised to produce a premium smokeless briquette which will attract a premium price in the export market. [Abbreviated abstract. Open document to view full version] / MT2017