Zincor's average zinc recovery was 90.29 % (for the period of 1 January 2009 to 30 September 2011), which was well below the industry standard of 96 %. Due to limitations in Zincor's iron removal technology, the maximum achievable recovery was 94 %. The zinc loss through the iron residue was the second biggest contributor to the overall zinc losses, so that there was much room for improvement. The calcine used for neutralisation in the Iron Removal Stage contained a portion of insoluble zinc ferrite. The insoluble zinc loss through the iron residue was associated with the presence of the insoluble zinc ferrite, as well as the phenomenon of coating of unleached neutralising agent by iron precipitate. The soluble zinc loss was a function of the dewatering characteristics of the precipitate. The work included the evaluation of alternative neutralising agents to supplement or replace calcine, as well as the implementation of a seed recycle. A review of literature found that the use of an alternative neutralising agent that contained little or no zinc could potentially reduce the insoluble portion of the zinc loss. Secondly, the presence of seed could potentially reduce both the soluble and insoluble zinc losses by promoting agglomeration growth and providing additional surface area for precipitation to occur (thereby reducing coating of zinc-rich neutralising agents). The laboratory work evaluated a number of alternative neutralising agents, but focused on the use of DRC oxide and limestone for neutralisation. These were evaluated separately and in combination, with and without a seed recycle.

South Africa has large low-grade coal reserves. With the prospect of expanding its coal demands for exports and power generation, it is important that the beneficiation and transport of coal in the country are economical. The current mode of transporting coal has some drawbacks, which include inefficient rail infrastructure, long distances, and several environmental concerns related to air pollution, water pollution, and traffic risks. It is, therefore, important to investigate efficient means of coal transportation, which will also reduce environmental impacts. The transport of highly concentrated coal-water slurries through pipelines has attracted the attention of many researchers as an efficient and economical means of fine coal utilization. The primary objectives of this study are to investigate the importance of surface charge, solids concentration and particle size on the stability and rheological behaviour of Witbank coal. This work was carried out to arrive at a sounder discernment of the function of dispersion addition on coal-water mixtures rheology and stability.

The objective of this review is to summarise the characteristics, significance and evolution of heavy minerals and their accumulations, and to identify the key controls on the development and distribution of heavy mineral concentrations in alluvial systems. These controls can be broadly classified as tectonic setting, geomorphic setting and grain-scale concentrating processes, each of which is discussed. Based on this review, exploration models are developed which are designed to indicate favourable localities for the accumulation of heavy minerals, and trends likely to be exhibited within these accumulations. The models are structured from the broadest scale of target selection, down to the local scale of sample site selection. The major conclusion of this work is that an understanding of process geomorphology is required to develop genetic models of placer development, including a detailed evaluation of climatic fluctuations throughout the Caenozoic. Palaeoplacers such as the Witwatersrand goldfield, are inferred to have formed under similar circumstances of tectonic setting as genetically comparable Caenozoic placers such as those of Otago, New Zealand. The means of preservation of such major basins is however poorly understood.