Technological research on converting iron ore tailings into a marketable product
by I. Mitov, A. Stoilova, B. Yordanov, and D. Krastev
This paper presents three technological scenarios for the recovery of a marketable product (iron-containing pellets) from gangue stored in the tailings dam at Kremikovtzi metallurgical plant in Bulgaria, using various combinations of flotation, magnetic separation, magnetic flocculation, and roasting. The iron concentrate from each process was subjected to pelletizing in a laboratory-scale pelletizer. Each technology was assessed with respect to the mass yield of concentrate, iron recovery, and the iron, lead, and zinc contents of the concentrate in order to establish the most effective route.
Evaluation of the mechanical properties of wood-derived charcoal briquettes for use as a reductant
by N.W. Makgobelele, R.K.K. Mbaya, J.R. Bunt, N.T. Leokaoke, and H.W.J.P. Neomagus
Silicon Smelters (Pty) Ltd (South Africa) consumes more than 80 000 t/a of wood derived charcoal as carbon reductant in the production of silicon metal. More than 10% of this material is discarded as fines (<6 mm) due to abrasion during processing. Charcoal fines residue (<650 μm) and polyvinyl alcohol (PVA) binder were used in this study to produce mechanically strong charcoal briquettes for metallurgical application. Key properties were investigated, and the results compared with metallurgical grade coarse charcoal. The produced briquettes were found to have a lower resistance to abrasion and drop-shattering than the coarse charcoal, but better compressive strength and water resistance.
A new grade-capping approach based on coarse duplicate data correlation
by R.V. Dutaut and D. Marcotte
In most exploration or mining grade data-sets, the presence of outliers or extreme values represents a significant challenge to mineral resource estimators. The most common practice is to cap the extreme values at a predefined level. This paper presents a new capping approach that uses QA/QC coarse duplicate data correlation to predict the real data coefficient of variation (i.e., error-free CV). The robustness of the approach is assessed using simulated data-sets. Real case studies of gold and nickel deposits are used to compare the proposed approach to the methods most widely used in the industry. The new approach is simple and objective, and. it provides a cap grade that is determined automatically.
A review of the role of underground measurements in the historical development of rock engineering in South Africa
by D.F. Malan and J.A.L. Napier
This paper describes some important aspects associated with historical underground measurements in South African gold and coal mines. The time-dependent response of the rock has been neglected for many decades, resulting in important aspects not being explored. Recent work is only now starting to address this gap in knowledge. A key lesson learnt in this investigation is that major advances in rock mechanics will not be possible without careful monitoring of the rock mass behaviour in experimental sites. Areas requiring further research can only be developed using extensive underground monitoring programmes.
Projectification in the South African mining industry
by W.A. Smith, M.C. Bekker, and C. Marnewick
Projects or project-orientated approaches in various sectors of the national economy have led to concepts such as ' projectified' and 'project orientated' organizations. By quantifying the share of project work in total work for a company, industry, or economy, one can reasonably determine the impact project management, and by default projectification, has in terms of staff optimization and allocation. This paper presents the results of a projectification study on the South African mining industry. The levels of projectification have increased over time, with the overall projectification of work being approximately one third of all work conducted.
Density – A contentious issue in the evaluation and determination of Resources and Reserves in coal deposits
by L. Roux
The initial evaluation of a coal deposit often raises uncertainty about the accuracy of the reported Resources and Reserves. Reconciliation of results from mining and beneficiation with the original raw field data highlights deficiencies in original estimations. Density, and its accurate determination, are the keys to credible values being obtained for Resources and Reserves. Losses of between 15% and 20% of the Resource/Reserve can be the result if incorrect densities are applied to the tonnage derivation. This paper summarizes the factors which contribute to the correct calculations of Resources and Reserves. A combination of theoretical, empirical, and reconciliatory evaluations of the available data has shown that an integrated approach provides credible results with a considerably higher degree of accuracy than is currently possible.
A critical investigation into spontaneous combustion in coal storage bunkers
by S. Govender, J.J.L. du Plessis, and R.C.W. Webber-Youngman
Spontaneous combustion (SC) is a cold oxidation reaction that generates heat, causes the temperature to rise of the reactant, leading to self-ignition. This occurs without an external heat source. This study investigated the occurrence of SC in coal storage bunkers. The results led to the compilation of a decision analyser for the use of engineers designing or working with coal storage bunkers. These findings, together with the systematic decision analyser, give good guidance on how to minimize and prevent SC in a coal bunker.
The geometric axial surface profiles of granular flows in rotating drums
by Elbasher M.E. Ahmed, I. Govender, and A. Mainza
A mechanistic description of axial segregation in rotating drum flows remains an open question. Consequently, optimal mixing of grinding balls and rocks for efficient breakage, maximum production of fines, and slurry transport is seldom achieved. This paper presents a practical model of the axial free surface profile by linking it to readily derived geometric features of the cross-sectional S-shaped free surface profile. A parametric study shows good agreement with experimental measurements reported in the literature, and heuristically valid trends.
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