研究采用一种环保、高效的硫代硫酸盐—铁氰化钾体系替代广泛使用的氰化法提取物料中的金银。在这种新的硫代硫酸盐体系中,利用更加稳定的K3Fe(CN)6替代传统的四氨合铜作为氧化剂。考察了硫代硫酸盐浓度、K3Fe(CN)6浓度以及溶液的初始p H值对浸出效果的影响。实验证明,这种新的体系能够快速有效地溶解金银,反应初始阶段铁氰化钾作氧化剂时,银的溶解速度非常快,铁氰化钾消耗完之后,银的溶解机理转变为氧气驱动的过程,此时银的溶解速率下降较多。该体系在浸出剂略微过量的情况下即可实现对金银的有效浸出。将该体系用于硫酸渣中金银的提取,在浸出条件为:0.05 M五水合硫代硫酸钠、1 m M铁氰化钾、p H=8时,浸出48 h后,金银的提取率分别为88%和92%。
The leaching of silver with the environmental effective sodium thiosulfate-potassium ferricyanide-sodium ferrocyanide alternative system has been studied.The thiosulfate leaching system was used to replace the widely-used cyanide.In this new thiosulfate leaching system,the more stable potassium ferricyanide was used to replace the traditional tetra-amine copper as oxidant.The effect of thiosulfate concentration,ratio of ferricyanide to ferrocyanide,p H,and temperature on silver leaching has been investigated.The results showed that this leaching system was quietly efficient to the dissolution of silver,the silver leaching rate was extremely fast when the ferricyanide acted as oxidation in the initial stage.After the complete consumption of potassium ferricyanide,silver dissolution was driven by oxygen and leaching rate decreased.A high silver leaching rate could be achieved in the case of a slight excess of lixiviant.In the leaching of sulfuric acid residue,leaching conditions were 0.05 M Na2S2O3·5H2O,1 m M K3Fe(CN)6,at p H=7,the extraction rate of gold and silver were 88% and 92% respectively after a leaching time of 48 hours.