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Johannesburg, South Africa

Youlton B.J.,SGS South Africa | Youlton B.J.,University of Witwatersrand | Kinnaird J.A.,University of Witwatersrand
Minerals Engineering | Year: 2013

During the acid leaching of uranium, gangue-reagent interactions have both negative and positive consequences. Gangue dissolution increases reagent costs, and in some cases can prevent the economic acid leaching of an ore, but can also increase uranium mineral exposure and improve recoveries. Due to rapid dissolution kinetics, the acid consumption characteristics of the various carbonate species are readily predicted, however the same is not true of silicate gangue. Due to factors including slower leach rates, incongruent dissolution, parabolic kinetics, and surface area, pH and temperature dependence, the gangue acid consumption characteristics of silicate minerals are significantly more complex. A detailed mineralogical investigation and acid leach tests were conducted on sandstone-hosted uranium ore samples. The dissolution characteristics of the more common gangue phases were determined. The study demonstrated that gangue-reagent interactions can be predicted from mineralogical data, thus reducing technical risk during processing. © 2013 Elsevier Ltd. All rights reserved. Source

Coetzee L.L.,SGS South Africa | Theron S.J.,SGS South Africa | Martin G.J.,SGS South Africa | Merwe J.-D.V.D.,SGS South Africa | Stanek T.A.,SGS South Africa
Minerals Engineering | Year: 2011

Modern gold deportment studies include physical, chemical and mineralogical assessments, combined to obtain a full understanding of the nature and variability of gold in a resource. The objective is to provide information which will allow cost effective and practical processing by informing decisions regarding resource evaluation, mining method and extraction process optimization. The distribution of gold, based on speciation, grain size and mode of occurrence (liberation, exposure, and mineral association) is quantitatively determined by means of automated Scanning Electron Microscopic Techniques (QEMSCAN/MLA). Furthermore, general mineralogical characterization is undertaken in order to characterize the gangue components; with special emphasis on deleterious characteristics of the ore (e.g. cyanide consumers such as secondary Cu-species, preg-robbers/borrowers, passivation due to Sb-minerals or As-minerals and oxygen consumers such as pyrrhotite/marcasite). Predictions based on the mineralogical observations are confirmed by physical and chemical testwork. These include grading analyses, gravity separation, direct cyanidation, and diagnostic (sequential) leach tests. © 2010 Elsevier Ltd. All rights reserved. Source

Smythe D.M.,SGS South Africa | Lombard A.,SGS South Africa | Coetzee L.L.,SGS South Africa
Minerals Engineering | Year: 2013

Due to the variability and complex nature of REE-containing ores, it is vital to understand the mineralogical characteristics, before embarking on any metallurgical testwork campaign. REE's are present in a variety of phases/minerals, all of which may react differently during processing. It is therefore important to identify and quantify all the REE-phases present in the ore, their mineral associations, grain size distributions as well as their liberation characteristics. In order to quantify the elemental deportment of the different REE's into the different REE-bearing phases, it is necessary to determine the mineral chemical compositions by Electron Microprobe. By assigning the average measured REE-elemental compositions to the different REE-phases, it becomes possible to determine the amount of each REE per REE-phase. Predictions about the best theoretically achievable grades and recoveries can be made. The data obtained are used to design a metallurgical testwork program suitable for the specific ore-type. © 2013 Elsevier Ltd. All rights reserved. Source

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