Stability of gold-thiosulphate complexes during gold-thiosulphate leaching process

传统的提金方法是在氰化物溶液中浸出金，然后在活性炭上回收金-氰化物络合物。最后，从活性炭中回收金，精制成高纯度的金。**虽然用CN提金（即CN工艺）是一种非常有效的工艺，而且众所周知CN对金的浸出具有高度选择性，但CN的毒性一直是黄金行业面临的挑战。CN是已知毒性最强的物质之一，对人类和动物都有极大的毒性。多年来，黄金行业一直在成功地使用CN，然而，每年都有几起CN泄漏事故的报道。使用CN的另一个挑战是在金萃取厂的废水中对其进行解毒的费用。**通过开发不含CN的黄金提取工艺，消除CN的使用一直是黄金行业的主要推动力。迄今为止，加拿大金矿公司巴里克黄金公司（Barrick Gold Corp.）是唯一一家开发出无碳回收方法并将其商业化的公司。该工艺以无毒的硫代硫酸钙作为金浸出介质，称为CaTS工艺。然而，该工艺的一个重大挑战是硫代硫酸盐在金浸出过程中的不稳定性。本研究的目的是了解在浸出过程中硫代硫酸盐氧化背后的根本原因，并针对这一挑战制定解决方案。项目成功完成后，CaTS工艺的试剂成本将降至最低，该工艺可推广给其他加拿大和国际黄金公司，为巴里克黄金公司和整个加拿大创造可观的收入。

The conventional method for gold extraction is to leach gold in a cyanide (CN) solution and the recover the gold-cyanide complex on activated carbon. Finally the gold can be recovered from the activated carbon and refined as highly pure gold.**Although the gold extraction with CN (i.e. CN process) is a very efficient process and CN is known to be a highly selective leaching for gold, the toxicity of CN has always been a challenge for the gold industry. CN is one of the most toxic materials known and is extremely toxic for human and animals. The gold industry has been successfully using CN for many years, nonetheless, several accidents of CN spills are reported every year. Another challenge with the use of CN is the cost of its detoxification in the waste waters of the gold extraction plants.**To eliminate the use of CN has been a major drive in the gold industry, via development of alternative CN-free processes for gold extraction. Thus far, Barrick Gold Corp., a Canadian gold mining company, is the only company which has developed and commercialized a CN-free process for gold recovery. The process is called CaTS process which uses non-toxic calcium thiosulphate as the gold leaching media. However one significant challenge with this process is the instability of thiosulphate during the gold leaching process. The objective of this study is to understand the fundamental reason behind the thiosulphate oxidation during the leaching process, and develop a solution for this challenge. After successful completion of the project, the reagent cost of the CaTS process will be minimized and the process can be marketed to other Canadian and international gold companies, generating significant revenues for Barrick Gold Corp, and Canada in general.