Abstract
This paper presents a research overview, reconciling key and useful case study findings, towards uncovering major causes of gold refractoriness and maximising extraction performance of specific gold flotation and bio-oxidation products. Through systematic investigation of the ore mineralogical and gold deportment properties, leaching mechanisms, and kinetic behaviour and pulp rheology, it was observed that the predominant cause of the poor extraction efficacy of one bio-oxidised product is the presence of recalcitrant sulphate minerals (e.g., jarosite and gypsum) produced during the oxidation process. This was followed by carbonaceous matter and other gangue minerals such as muscovite, quartz, and rutile. The underpining leaching mechanism and kinetics coupled with the pulp rheology were influenced by the feed mineralogy/chemistry, time, agitation/shear rate, interfacial chemistry, pH modifier type, and mechano-chemical activation. For instance, surface exposure of otherwise unavailable gold particles by mechano-chemical activation enhanced the gold leaching rate and yield. This work reflect the remarkable impact of subtle deposit feature changes on extraction performance.
Highlights
The economic significance of gold to the development of several nations (e.g., Australia, South Africa, USA, China, Canada, and Ghana), owing to its coveted qualities and unique applications, can be traced back to the dawn of civilization [1,2,3,4,5,6]
Reconciling and discussing all the key findings emerging from the comprehensive, investigations presented; Determining the overall impact of process variables on the leaching behaviour and rheological behaviour; and Summarise the different mechanisms and kinetics which underpin the leaching behaviour with links to extant literature. This provides overarching discussions, highlighting how the new knowledge and greater understanding gleaned may be useful in designing ore mineralogy-specific, customised approach and strategies for improved, cost-effective gold extraction from complex, refractory, sulphidic ores
The major cause of gold refractoriness in the obstinate ore was the presence of refractory secondary sulphate minerals
Summary
The economic significance of gold to the development of several nations (e.g., Australia, South Africa, USA, China, Canada, and Ghana), owing to its coveted qualities and unique applications, can be traced back to the dawn of civilization [1,2,3,4,5,6]. Despite numerous reported studies on improved gold extraction (by cyanide leaching) from complex low grade ores [9,10,11,12,13,14,15,16], there is still a lack of fundamental knowledge and understanding on the interplay between refractory ore-specific primary and secondary mineral phases, solution chemistry, and the particle-solution interfacial species, particle interactions, and chemical/electrochemical reactions which underpin the mechanisms and kinetics of the leaching process. This provides overarching discussions, highlighting how the new knowledge and greater understanding gleaned may be useful in designing ore mineralogy-specific, customised approach and strategies for improved, cost-effective gold extraction from complex, refractory, sulphidic ores
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