Abstract

Of late, given the difficulties in gold extraction and severe environmental pollution emanating from cyanide extraction of Carlin-type gold concentrate (CTGC), a novel pressure oxidation pretreatment followed by sodium jarosite decomposition and fine grinding was first proposed to extract gold from the CTGC in a non-cyanide system. Thermodynamic computations of the Gibbs free energy and the Eh–pH diagram of different reaction systems were calculated to reveal the reaction mechanism during the treatment process. The optimal pressure oxidation pretreatment conditions were determined as follows: stirring speed 600 r/min, liquid-to-solid ratio of 4, pH 1.2–1.3, partial pressure of oxygen 1200 kPa, temperature 225 °C, and time 1.5 h. The extraction of gold increased from 9.7 to 82.1%. The sulfur conversion mechanism and the distribution of the gold phase as a function of leaching temperature during the pressure oxidation leaching process were investigated. The precise regulation and control mechanism of sodium jarosite decomposition and fine grinding were clarified. Furthermore, the polysulfide leaching results show that pressure oxidation leaching of the CTGC followed by sodium jarosite decomposition and fine grinding can efficiently liberate gold from the mineral envelope and provide favorable conditions for gold extraction in a non-cyanide leaching system. The leaching efficiency of gold in the polysulfide system reached 96.8%. This process has proved to be a promising alternative for efficient and environmentally friendly extraction of gold from the refractory gold ore.

Graphical Abstract

中文翻译：

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加压氧化预处理-黄钾铁矾分解-细磨从卡林型金精矿中无氰提金：一种环保工艺及其机理

摘要

近来，鉴于卡林型金精矿（CTGC）氰化法提取金的困难和严重的环境污染，首先提出了一种新的加压氧化预处理，然后是黄钾铁矾钠分解和细磨，以从CTGC中提取金。无氰系统。计算了不同反应体系的吉布斯自由能和Eh-pH图的热力学计算，以揭示处理过程中的反应机理。最佳压力氧化预处理条件为搅拌速度600 r/min、液固比4、pH 1.2~1.3、氧分压1200 kPa、温度225 ℃、时间1.5 h。黄金的提取率从 9.7% 增加到 82.1%。研究了加压氧化浸出过程中硫转化机理和金相分布随浸出温度的变化。阐明了黄钾铁矾钠分解和细磨的精确调控机理。此外，多硫化物浸出结果表明，CTGC加压氧化浸出、黄钾铁矾钠分解和细磨可以有效地将金从矿物包膜中释放出来，为无氰浸出系统中的金提取提供有利条件。金在多硫化物体系中的浸出率达到96.8%。该工艺已被证明是一种从难处理的金矿石中高效、环保地提取金的有前景的替代方案。

图形概要