Complete gold extraction and recovery from double refractory gold ores by thiourea after bio-oxidation

IF 4.8 2区材料科学 Q1 METALLURGY & METALLURGICAL ENGINEERING Hydrometallurgy Pub Date : 2024-05-17 DOI:10.1016/j.hydromet.2024.106330

Keiko Sasaki , Ikumi Suyama , Ryusei Takimoto , Kojo Twum Konadu , Hirofumi Ichinose , Jacques Eksteen

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Abstract

Cyanidation, a conventional process to extract gold from gold ores, has been used for over 130 years in industrial mining because of the high efficiency and rate of formation of Au(CN)₂⁻ and the high recovery efficiency by adsorption of Au(CN)₂⁻ on activated carbon. However, carbonaceous refractory gold ores are not targeted because Au(CN)₂⁻ is easily adsorbed on carbonaceous matter in the ores, resulting in high recovery loss. In this study, the flotation concentrates of a carbonaceous refractory gold ores was subjected to biooxidation at 45 °C using a mixed culture containing iron-oxidizing and sulfur-oxidizing bacteria, followed by gold extraction using thiourea under strongly acidic conditions. The gold extraction efficiency reached ∼100% in 12 h without re-adsorption. Finally, the quantitative recovery of the Au(CS(NH₂)₂)₂⁺ complex was confirmed by adsorption on strongly cationic exchange resin. Biooxidation reduced the amount of Fe-containing metal sulfides, which minimized the decomposition of thiourea, and the Au(CS(NH₂)₂)₂⁺ complex had a low affinity toward carbonaceous matter, different to Au(CN)₂⁻. Since the process described in this study does not require roasting to remove carbonaceous materials in pretreatment and does not use cyanide for gold extraction, it is environmentally friendly and should be considered for practical applications in carbonaceous gold ore-producing mines.

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生物氧化后用硫脲从双重难提金矿石中完全提取和回收金

氰化法是从金矿石中提取黄金的传统工艺，由于 Au(CN)2- 的形成效率高、速度快，而且 Au(CN)2- 在活性炭上的吸附回收效率高，因此已在工业采矿中使用了 130 多年。然而，由于 Au(CN)2- 容易吸附在矿石中的碳质上，导致回收损失大，因此碳质难选金矿不是目标。本研究使用含铁氧化细菌和硫氧化细菌的混合培养物，在 45 °C 下对碳质难选金矿的浮选精矿进行生物氧化，然后在强酸性条件下使用硫脲提取金。金的提取效率在 12 小时内达到了 100%，且无再吸附现象。最后，通过在强阳离子交换树脂上的吸附，确认了 Au(CS(NH2)2)2+ 复合物的定量回收。生物氧化减少了含铁金属硫化物的数量，从而将硫脲的分解降到最低，而且 Au（CS（NH2）2）2+ 复合物与 Au（CN）2- 不同，对碳物质的亲和力较低。由于本研究所述工艺在预处理时无需焙烧去除碳质物质，也不使用氰化物提金，因此对环境友好，应考虑在碳质金矿生产中实际应用。

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来源期刊

Hydrometallurgy 工程技术-冶金工程

CiteScore

9.50

自引率

6.40%

发文量

144

审稿时长

3.4 months

期刊介绍： Hydrometallurgy aims to compile studies on novel processes, process design, chemistry, modelling, control, economics and interfaces between unit operations, and to provide a forum for discussions on case histories and operational difficulties. Topics covered include: leaching of metal values by chemical reagents or bacterial action at ambient or elevated pressures and temperatures; separation of solids from leach liquors; removal of impurities and recovery of metal values by precipitation, ion exchange, solvent extraction, gaseous reduction, cementation, electro-winning and electro-refining; pre-treatment of ores by roasting or chemical treatments such as halogenation or reduction; recycling of reagents and treatment of effluents.