Abstract
This study focuses on leaching of gold from fine-grained waste materials from flotation. The input raw material is the waste product after flotation containing about 1–2.5 g/t of Au. This paper makes part of wider research to identify all available methods and select the most appropriate technology to obtain residual gold from fine-grained waste materials. An alternative method to conventional cyanide methods, which have negative environmental impacts [1], has been tested under laboratory conditions, namely thiourea leaching. We observed the effect of the grain size of input raw materials with concentration of thiourea and Fe3+ ions in dependence on temperature and pH during research. The pH values were maintained low during all experiments to avoid dissociation of the leaching solution. In optimal condition of leaching we achieved 85% success rate of gold recovery. The data may be useful to improve the processes of recovery of useful constituents from unused wastes with the content of gold. Keywords: Flotation; Gold; Leaching; Thiourea. DOI 10.35180/gse-2020-0036
Highlights
Hodruša-Hámre is a Slovak mining village which has long been connected with mining of gold-silver ores
When an iron (III) ion is used as the oxidizing agent, the overall reaction showing the extraction of gold in the acidic thiourea solutions can be described as follows: Au + 2CS(NH2)2 + Fe3 → Au[CS(NH2)2] + Fe2+
The experiments were carried out under laboratory conditions, during which time and temperature were monitored during leaching, which was kept in a laboratory shaker and approached the air temperature so that the results could be applied in industry
Summary
Hodruša-Hámre is a Slovak mining village which has long been connected with mining of gold-silver ores. The basis of the ore is quartz along with other silicates such as illite, mica or feldspar. The proportion of silicate is relatively high up to 80–85 %. The use of thiourea CH4N2S as an extraction agent for leaching has proven to be a quality method to obtain precious metals in the metallurgical industry. The use of thiourea CH4N2S as an extractant for leaching is used as a suitable method to recover precious metals in the metallurgical industry [2]. Thiourea leaching has been applied in gold hydrometallurgy. As opposed to cyanide methodology, thiourea leaching is more economical due to a lower cost because in cyanidation the high acid solutions need to be neutralized [3]
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