Abstract The effect of temperature in the range of 20–65 °C on gold extraction from refractory gold tailings containing pyrite in 20% (v/v) of 1-butyl-3-methylimidazolium hydrogen sulphate [Bmim+HSO4−]-water solution with thiourea as complexing agent and iron(III) sulphate oxidant, at pH of 1 was examined for 12 h leaching time intervals. The experimental results revealed that the extraction of gold improved by increasing the temperature. The effect of time showed that a substantial amount of gold extraction took place during the first day of extraction and thereafter very little gold extraction occurred. The ionic liquid [Bmim+HSO4−] is water soluble and in aquatic solution can act like a Bronsted acid by releasing H+ ions. The apparent activation energy (Ea) was calculated based on the Arrhenius theory and it suggests that the kinetic process of gold leaching with this acidic ionic liquid follows shrinking core model with mixed and diffusion controlled reaction regions having Ea of 17.97 kJ/mol and 27.17 kJ/mol, respectively. In the SEM image of the solid residue of the leached sample some pores appeared on the reactive pyrite particles, whereas the pyrite particles in the unleached sample looked smooth. Additionally, Raman spectra detected sulphur shifts in the recorded spectra of the solid residue after leaching which can be an indication of the formation of a product surface layer of elemental sulphur, which supports the diffusion through a product layer in the kinetic model.

中文翻译：

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离子液体氧化浸出难溶硫化金尾矿

摘要 20-65 °C 温度范围对含黄铁矿的难熔金尾矿在 20% (v/v) 1-丁基-3-甲基咪唑鎓硫酸氢盐 [Bmim+HSO4−]-水溶液中提取金的影响使用硫脲作为络合剂和硫酸铁 (III) 氧化剂，在 pH 值为 1 时检查 12 小时的浸出时间间隔。实验结果表明，随着温度的升高，金的提取得到改善。时间的影响表明，在提取的第一天发生了大量的金提取，此后几乎没有发生金提取。离子液体 [Bmim+HSO4−] 是水溶性的，在水溶液中可以通过释放 H+ 离子而起到像布朗斯台德酸一样的作用。根据阿伦尼乌斯理论计算表观活化能 (Ea)，表明该酸性离子液体浸金的动力学过程遵循收缩核心模型，混合和扩散控制反应区域的 Ea 为 17.97 kJ/mol 和 27.17 kJ /mol，分别。在浸出样品固体残留物的 SEM 图像中，反应性黄铁矿颗粒上出现了一些孔隙，而未浸出样品中的黄铁矿颗粒看起来很光滑。此外，拉曼光谱在浸出后固体残留物的记录光谱中检测到硫位移，这可能表明元素硫的产品表面层的形成，这支持在动力学模型中通过产品层的扩散。