Abstract:

Flotation gold tailings contain a certain amount of gold and other valuable elements, thus having recycling value. However, problems such as low leaching efficiency and difficulties in extracting gold from low concentration leaching solutions exist. Therefore, a new process of electro-chlorination leaching combined with electrocoagulation extraction of gold was proposed. The use of electro-generated chlorine to assist hydrochloric acid leaching could significantly improve the gold leaching rate of flotation gold tailings, and the positively charged colloids generated by electrocoagulation could efficiently capture trace aquo-gold ions in the solution. The experimental results showed that the electro-chlorination leaching of flotation gold tailings with a particle size range of 50—75μm could achieve ideal leaching results. The influence of the stirring speed on the electro-chlorination leaching rate was not significant, while the hydrochloric acid concentration, liquid-solid ratio and temperature were the key factors dominating the electro-chlorination leaching effect. Electrocoagulation exhibited significant adsorption selectivity for gold ions in the leachate. At a pH of 6, a plate voltage of 2V and a plate spacing of 2cm, the electrocoagulation gold extraction efficiency was approximately 100%. Scanning electron microscopy (SEM), X-ray energy dispersive spectrometer (EDS), X-ray diffractometer (XRD) and X-ray photoelectron spectrometer (XPS) were used to characterize the microscopic morphology and material composition of flotation gold tailings, tailings leaching residues and gold-containing flocs. Theoretical studies showed that the oxidizing chlorine generated by electro-chlorination and the polarization effect of the anode enhanced the dissolution of gold and improved the leaching rate. The iron ions generated by the anode electrolysis of electrocoagulation hydrolyzed to form positively charged iron hydroxide colloids, which underwent electrostatic adsorption and redox reactions with negatively charged AuCl₄^- ions in the solution, thus realizing the efficient extraction of gold. The research results can provide theoretical and technical bases for the efficient and low-cost extraction and recovery of low-grade flotation gold tailings, and provide methodological references for the development of electrochemical leaching and rare and precious metal extraction technologies.

Key words: leaching, electrocoagulation, adsorption, reduction, gold recovery

摘要：

浮选金尾矿含一定量的金及有价元素，具有回收价值，但存在浸出效率低、低浓度浸出液金提取困难等问题。本文因此提出电氯化浸出协同电絮凝提取金的新工艺，利用电生氯辅助盐酸浸出大幅提高浮选金尾矿金的浸出率，利用电絮凝产生的正电性胶体高效捕获溶液中的微量水合金离子。实验结果表明：粒径范围在50~75μm的浮选金尾矿电氯化浸出均能取得理想的浸出效果，搅拌速度对电氯化浸出率的影响并不显著，而盐酸浓度、液固比、温度则是主导电氯化浸出效果的关键因素；电絮凝对浸出液中的金离子表现出显著的吸附选择性，在pH=6、极板电压2V、极板间距2cm时，金提取效率约100%。采用扫描电子显微镜（SEM）、X射线能谱仪（EDS）、X射线衍射仪（XRD）、X射线光电子能谱仪（XPS）等表征了浮选金尾矿、尾矿浸出渣、含金絮体的微观形貌和物质组成，理论研究表明，电氯化产生的氧化性氯、阳极的极化作用加强了金的溶解，提高了浸出率；电絮凝阳极电解产生的铁离子水解形成带正电的铁氢氧化物胶体，与溶液中带负电的AuCl₄^-发生了静电吸附和氧化还原作用，实现了金的高效提取。研究结果可为低品位浮选金尾矿高效、低成本的提取回收提供理论和技术依据，为电化学浸取和稀贵金属提取技术的发展提供方法借鉴。

关键词: 浸取, 电絮凝, 吸附, 还原, 黄金回收