In the extraction aspect, the paper discloses two different extraction schemes on treating refractory ores, namely pretreatment followed by gold leaching and direct leaching. Pretreatment process involving roasting chemical oxidation and bio-oxidation have been discussed. Direct leaching of gold ore processing such as heap leaching, carbon in pulp (CIP), carbon in leach (CIL) and resin in pulp (RIP) are summarized. This paper also dicloses in a detailed manner the research approach on the development of alternative leach reagents which could improve environmental concerns as compared to the use of cyanide.
In order to generate the most value from refractory gold ore cip extraction plant and prevent longer-term distress due to grade erosion, we see three main areas for action that miners should consider:
Diligent mine planning and plant design are crucial to keep capital expenditures (capex) on budget and ensure that operating expenditures (opex) stay in the expected range during the production stage. In order to decrease capex overspending, miners should pay extra attention to the plant design prior to construction. Identification of bottlenecks and overcapacities is crucial due to the many recirculation systems needed at the processing plant. A suboptimal plant design for a specific ore can quickly erode the benefits of higher-grade refractory ores through reduced recovery or the inability to approach nominal capacity. Miners should also be mindful of proper material selection during plant construction in order to decrease downtimes caused by, for example, extensive material wear in the highly corrosive environment associated with autoclaves.
The role of biotechnology in different facets of gold extraction metallurgy is illustrated with respect to biogenesis of gold ore processing plant, biobenefication, bioliberation and bioenvironmental control. The use and commerical potential of this technology are discussed with reference to the mining and processing of Hutti gold ores. A microbial survey of the Hutti gold mines revealed the ubiquitous presence of various autotrophic and heterotrophic bacteria, fungi and yeast of relevance in gold processing. The possible roles played by different indigenous microorganisms in the formation, conversion and transport of gold along with various associated minerals have been brought out. Similarly, the role of Thiobacillus ferrooxidans in the flotation beneficiation of gold-bearing sulphides and in enhancing gold recovery from refractory sulphide ores and concentrates has been demonstrated. Direct gold solubilization could be achieved by Bacillus spp. Various fungi and yeast were found to be useful in the biosorption of gold and other base metals from cyanide effluents. It could thus show that biotechnology could be beneficially utilized in different stages of precious metal processing spanning from mining to waste disposal.
A Review of the Cyanidation Treatment of Copper ore Separation and Concentrates
by Diego Medina * andCorby G. Anderson and reagents proposed for the effective treatment of these ores. The primary purpose of this review paper is to present the hydrometallurgical processes that currently exist in the mining industry for the treatment of silver, copper, and tantalum ore separation, as well as concentrate treatments. In addition, this paper aims to present the most important challenges that the industry currently faces, so that future processes that are both more efficient and feasible may be established.