Optimisation of efficient auxiliary agents of gold leaching in an alkaline thiourea solution for a finely disseminated gold ore
by Lifeng Li; Zhongsi Zhu; Youcai Liu; Qingquan Lin; Zhihui Li; Jiangang Fu
International Journal of Mining and Mineral Engineering (IJMME), Vol. 5, No. 4, 2014

Abstract: Thiourea as a kind of green and eco-friendly gold lixiviant, was employed to substitute cyanide in the present study of gold leaching. The investigation was carried out on a finely disseminated gold ore from Hongmiao (Hunan province, China) in alkaline thiourea solution with indispensable stable reagents of Na₂SO₃ and (NaPO₃)₆. The main aim was to seek suitable stable reagents and oxidising agents required in leaching gold. Na₂SO₃ and (NaPO₃)₆ were determined as the best stable reagents and Na₂S₂O₈ was a more appropriate oxidant compared with K₃[Fe(CN)₆] in this study. Meantime, the effects of leaching parameters, i.e., the molar ratio of SO₃²⁻, PO₃⁻, TU and S₂O₈²⁻, pH, mixing time and grinding fineness were examined in detail and the optimum condition was obtained. The experimental results show that the molar ratio of SO₃²⁻, PO₃⁻, TU and S₂O₈²⁻ greatly affected gold leaching extent and thiourea decomposition. No more than 72.6% leaching rate could be reached due to deactivation of elemental sulphur created by thiourea and other negative factors, while lower leaching rate (69.4%) of gold leaching rate was obtained in acidic thiourea media compared with alkaline media.

Online publication date: Fri, 26-Dec-2014

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