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Redox Controlled Chalcopyrite Leaching as a New Method for Copper Production

氧化还原控制黄铜矿浸出作为铜生产的新方法

基本信息

批准号：
13450412
负责人：
TSUNEKAWA Masami
金额：
$ 9.41万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Heap leaching of low-grade copper ore, combined with solvent-extraction/electro-winning, has become important in copper production, because of its low capital and operation costs, operational simplicity However, the process has not been fully successful, due to the extremely slow leaching kinetics of a common copper source, chalcopyrite (CuFeS_2). Chalcopyrite leaching is a redox process and the control of the redox potential determined by the concentration ration of oxidant ferric ion to reductant ferrous ion has been proposed to improve the leaching rate. In this study, the redox potential dependence of chalcopyrite leaching in sulfuric acid solutions and the factors affecting the potential dependence of the leaching were investigated to establish the redox controlled chalcopyrite leaching. Leaching and anodic-polarization experiments showed that coexistence of cupric and ferrous ions activate anodic dissolution of chalcopyrite, causing faster copper extraction at the potentials below a certain value (critical potential). The analysis of the AC impedance spectra for chalcopyrite electrode indicated that a high-resistance passive layer grows on the chalcopyrite surface without cupric and/or ferrous ions, and that coexistence of these ions causes a formation of another product layer and inhibits the passive layer growth at low potentials. These results are explained by a reaction model assuming the formation of intermediate Cu_2S due to chalcopyrite reduction and the subsequent oxidation of the Cu_2S. The critical potential corresponds to the redox potential of the Cu_2S formation and the predicted values matched with the experimental results, and the optimum redox potential for chalcopyrite dissolution is a function of cupric and ferrous ion concentrations. Effects of catalysts like silver ions and activated carbon on chalcopyrite leaching were also explained based on the above model.

低品位铜矿堆浸与溶剂浸出/电积相结合，具有投资少、操作成本低、操作简单等优点，在铜生产中具有重要意义。然而，由于黄铜矿(CuFeS_2)这一常见铜源的浸出动力学非常缓慢，该工艺并未完全成功。黄铜矿浸出属于氧化还原过程，提出了通过控制氧化剂铁离子与还原铁离子的浓度比来控制氧化还原电位的方法来提高浸出率。本文研究了黄铜矿在硫酸溶液中浸出的氧化还原电位依赖性及其影响因素，以建立氧化还原控制的黄铜矿浸出过程。浸出和阳极极化实验表明，铜和亚铁离子的共存激活了黄铜矿的阳极溶解，使铜在某一值(临界电位)以下的浸出速度加快。对黄铜矿电极交流阻抗谱的分析表明，黄铜矿表面没有铜和/或亚铁离子，而是形成了高阻的钝化层，在低电位时，这些离子的共存导致另一个产物层的形成，抑制了钝化层的生长。用黄铜矿还原生成中间产物Cu2S和随后的Cu2S氧化的反应模型解释了这些结果。临界电位对应于Cu2S生成的氧化还原电位，预测值与实验结果相吻合，黄铜矿溶解的最佳氧化还原电位是铜和亚铁离子浓度的函数。在此基础上，对银离子、活性碳等催化剂对黄铜矿浸出的影响进行了解释。