Corrosion and stress corrosion cracking behavior of alloys in solutions relevant to gold thiosulfate leaching technology

湿法冶金工艺对金属萃取废液的处理和显著的研究致力于在环境问题方面改进工艺。金的湿法冶金萃取目前主要采用氰化浸出法。由于人员安全和环境问题，用硫代硫酸盐代替氰化物浸出剂引起了人们的极大兴趣。巴里克黄金公司有意为其氰化浸金工艺开发新的浸出剂。评估材料在浓硫代硫酸盐溶液中的腐蚀行为是一个障碍，因为以前没有在这种介质中进行过研究。本提案的总体目标是提供建筑材料在硫代硫酸盐溶液中与金浸出有关的腐蚀行为的数据。最终的实际目标将是确定在化学稳定性和应力腐蚀开裂方面具有最佳性能的合金。在基本层面上，由于没有关于浓硫代硫酸盐溶液中腐蚀行为的数据，这将对腐蚀科学做出重大贡献。这是特别重要的，因为1)硫代硫酸盐与表面的相互作用导致硫的产生，从而促进应力腐蚀开裂；(2)溶液化学及硫代硫酸盐缓冲能力引起的并发症。在这项研究中使用的创新电化学技术将有助于缩小腐蚀科学在这种特殊环境中的差距。本研究项目将培养1名博士生、1名博士后和4名暑期生。本研究有助于理解高浓度硫代硫酸盐溶液中的腐蚀现象。这将极大地帮助确定这种介质的最佳建筑材料，最终将加速从目前的氰化物浸出厂向更环保的硫代硫酸盐浸出厂的过渡。

Hydrometallurgical processes for metal extraction deal with waste solution treatment and significant research isdedicated to improving the processes in terms of environmental issues. Gold hydrometallurgical extraction is currentlybeing performed bycyanide leaching. Due to personnel safetyand environmental issues, there is significant interest for replacing the cyanide leaching agent with thiosulfate. Barrick Gold Corporation is interested in developing the new leaching agent for their cyanide gold leaching process. The assessment of corrosion behavior of materials in concentrated thiosulfate solutions is an obstacle since no previous studyhas been performed in this medium. The overall objective of this proposal is to provide data on corrosion behavior of construction materials in thiosulfate solutions relevant to gold leaching. The final practical goal will be to decide on the alloys with the best performance in terms of chemical stabilityand stress corrosion cracking. In fundamental level, this will appreciablycontribute to the corrosion science since there is no data on corrosion behavior in concentrated thiosulfate solutions. This is particularlyimportant because of 1) interactions of thiosulfate with the surface leading to generation of sulfur and consequentlypromoting stress corrosion cracking; and 2) solution chemistryand the complications resulting from buffering capacityof thiosulfate. The innovative electrochemical techniques to be used in this studywill contribute to close the corrosion science gap in this particular environment.A PhD student, a post doctoral fellow and four summer students will be trained in this research project. This studywill help understanding the corrosion phenomenon in highlyconcentrated thiosulfate solutions. It will greatlyhelp deciding the best construction materials for this medium, which will finallyaccelerate the transition from the current cyanide-based leaching plants to more environmentally-friendlythiosulfate plants.