氰化废水回收技术综述

Review on Recovery Technologies of Cyanide-containing Wastewater

氰化浸出工艺至今仍是占绝对统治地位的提金方法,金矿石中常常伴生含量不等的各类杂质金属矿物,导致氰化物消耗和氰化尾液中氰化物含量显著增加。目前普遍应用的氰化废水净化工艺对处理简单的含游离氰化物的废水是非常有效的。如果矿石中存在其他有价金属如铜等,则氰化物将流失于尾矿、尾渣中难以有效回收,杂质元素的存在增加了氰化物的消耗,严重时甚至使整个金氰化回收工艺失效。针对黄金矿山含氰废水的性质和特点,已研究开发了多种回收技术和方法。由于各种杂质金属的累积效应,含氰废水直接返回工艺通常很难实现。AVR法及由此技术衍生的方法如硫化物沉淀技术生产成本较高、且不能有效回收含氰废液中的有价金属。受制于对氰化物的吸附能力,活性炭只能处理低氰废水。树脂吸附和溶剂萃取工艺可以针对含氰废水性质进行合理的选择性设计,但通常生产成本较高,操作工序繁琐复杂。采用液膜和其他如渗析法等技术仍然处于实验室研究阶段,能够有效应用于工业实践的氰化废液回收技术仍有待开发。

Cyanide leaching is the dominant method in gold extraction nowadays.Cyanide consumption and cyanide content in cyanide-containing wastewater rise significantly due to various impurities with different contents in gold ore.At present,cyanide-containing wastewater purification process widely used is very effective for treating simple free-cyanide bearing wastewater.However,if there are other metals such as copper in ore,cyanide will be lost in tailings,making it difficult to effectively recover.High cyanide consumption and loss caused by various impurities will even make cyanide leaching process failure.In view of characteristics of cyanide-containing wastewater in gold mining industry,variety of recovery technologies and methods have been developed.It is infeasible to return cyanide-containing wastewater directly to leaching process due to accumulation effect of various impurity metals.AVR method and its derivatives,such as sulfide precipitation,are expensive and fail to effectively recover metals from cyanide-containing wastewater.Activated carbon can only treat simple and low concentration cyanide-containing wastewater due to its low adsorption capacity.Resin adsorption and solvent extraction process can be designed in a reasonable and selective way according to properties of cyanide-containing wastewater.However,the cost is relatively high,and operation procedures are complicated.Liquid membranes or other techniques,such as dialysis,are still in laboratory research stage.Technologies can be effectively applied to industrial practice to recover cyanide-containing wastewater still need to be developed.