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

传统的提金方法是在氰化物（CN）溶液中浸提金，然后在活性炭上回收金-氰化物络合物。最后，可以从活性炭中回收黄金，并提炼为高纯度的黄金。虽然用氯化萘提取黄金（即氯化萘工艺）是一种非常有效的工艺，而且氯化萘对黄金具有高度选择性浸出作用，但氯化萘的毒性一直是黄金行业面临的挑战。氯化萘是已知毒性最强的物质之一，对人类和动物具有极强的毒性。黄金行业多年来一直成功使用氯化萘，但每年都会报告发生几起氯化萘泄漏事故。使用氯化萘的另一个挑战是在黄金提炼厂的沃茨中进行解毒的成本。通过开发不含氯化萘的黄金提取替代工艺，消除氯化萘的使用一直是黄金行业的一个主要驱动力。到目前为止，巴里克黄金公司，加拿大一家金矿开采公司是唯一一家开发了无氯化萘黄金回收工艺并将其商业化的公司。该工艺称为CaTS工艺，其使用无毒的硫代硫酸钙作为金浸出介质。然而，该方法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浸出过程中硫代硫酸盐氧化背后的根本原因，并为这一挑战制定解决方案。该项目成功完成后，CaTS工艺的试剂成本将最小化，该工艺可以销售给其他加拿大和国际黄金公司，为巴里克黄金公司和加拿大带来可观的收入。

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.