(中南大学 资源加工与生物工程学院，长沙 410083)
摘 要: 结合扫描电子显微镜(SEM)和原子力显微镜(AFM)测定金氰化溶解过程表面产物的形貌。结果表明，金片表面溶蚀程度轻，少量溶解主要发生在棱和角等边界断点上。利用X射线光电子能谱(XPS)研究了金氰化溶解过程表面产物的组成元素及键合特性，得出表面产物的主要成分为AuCN、Au(OH)x和Au2(OHCN)。金在NaCN溶液中的溶解是分步进行的：第一步，Au与配位剂CN-作用形成长链结构的AuCN，AuCN进一步与CN-反应才形成 实现溶解；第二步反应只能在AuCN长链的断点处发生，因而成为总反应的控制步骤，从而使表面产物AuCN大量累积形成表面覆盖层，即表面钝化层；而棱角部位的表面产物因断点多而较易发生溶解，从而呈疏松颗粒状，未能形成紧密相连的面覆盖，即表面活性区。
关键字: 金；氰化物；氰化浸金；表面产物；钝化
（School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China）
Abstract:The micro-morphology of gold surface products in cyanide solutions was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). It is found that, little corrosion occurs on the gold surface except on the surface edges and horns. The element composition and binding feature of gold surface products in cyanide solutions were studied by X-ray photoelectron spectroscopy (XPS). It is indicated that the composition of surface product include AuCN, Au(OH)x and Au2(OHCN). Gold dissolution process takes place by two steps, in which, AuCN first forms into a long-chain structure AuCN that further reacts with CN- to form the soluble complex in the second step. The second step that can only take place on the end of AuCN chain essentially acts as the rate-controlling step. This mechanism inevitably causes surface covering of accumulated AuCN, i.e., the surface passivated layer. On the other side surface products on the edges and horns dissolve faster because of more breakpoints in the AuCN chain and remain in separate particles which doesn’t form compact spread covering, i.e., surface activated area.
Key words: gold; cyanide; gold cyanidation; surface product; passivation
