EXAFS研究硫酸硫脲反萃季铵氰化金的机理  

EXAFS Study on the Stripping Mechanism in N_(263)/Alkaline Cyanide Gold Solution/Sulfuric Thiourea System

作　　者：唐红萍[1] 杨明德[1] 何培炯[1] 胡天斗[2] 张静[2] 谢亚宁[2] 

机构地区：[1]清华大学核能技术设计研究院,北京102201 [2]中国科学院高能物理研究所同步辐射实验室,北京100039

出　　处：《光谱学与光谱分析》2004年第6期752-755,共4页Spectroscopy and Spectral Analysis

摘　　要：季铵盐可以直接从氰化浸出液中萃取金 ,但反萃困难。酸性硫脲通空气反萃体系是目前从季铵盐中反萃氰化金最有效的体系 ,但对其机理的研究很少。文章采用扩展X射线吸收精细结构 (EXAFS)等方法研究了硫酸硫脲从负载氰化金季铵盐中反萃金的机理。研究结果表明 ,在反萃过程中 ,硫酸、硫脲和硫脲金都能以中性分子进入有机相 ,中性缔合在季铵盐反萃过程中不可忽视。反萃机理如下 :(1)硫酸和硫脲首先进入有机相被萃取 ;(2 )在有机相中 ,硫脲争夺金的氰根配位 ,使氰化金变成硫脲金 ,同时游离出来的氰根与硫酸中的氢离子作用变成氢氰酸 ,在鼓空气搅拌条件下氢氰酸被空气迅速带走排除 ;(3)硫脲金配合物在有机相和水相中分配 ,大部分硫脲金进入水相 ,从而达到反萃的目的。Quaternary ammonium salt has strong affinity with gold in cyanide solutions, but it is not readily stripped. Stripping with acidic thiourea solutions and air sparging shows promise. There are some reports on the process of thiourea stripping, but little about its mechanism. In this paper, the stripping mechanism of N-263/sulphuric thiourea/alkaline cyanide gold solution is studied by EXAFS. According to the experiments, sulphuric acid, thiourea and gold-thiourea complex can be extracted by N-263 as a neutral molecule, and the stripping process can be described as following: (1) Sulphuric acid and thiourea are extracted by N-263; (2) In organic phase, gold-cyanide complex is converted to gold-thiourea complex, which exists as Au[SC(NH2)(2)](2)HSO4, and CN- forms HCN with acid at the same time; (3) HCN is removed by air sparging, and Au [ SC(NH2)(2)](2)HSO4 is distributed between organic phase and liquor phase, most of which transfers to liquor phase and is stripped.

关 键 词：季铵盐 金 溶剂萃取 酸性硫脲通空气反萃体系 扩展X射线吸收精细结构 EXAFS 

分 类 号：O614.123[理学—无机化学] O658.2[理学—化学]