氰化提金废水中金属氰络合离子的溶剂萃取

Solvent extraction of metal cyanide complex ions in cyanide gold extraction wastewater

采用溴代十六烷基吡啶(CPB)−仲辛醇−磺化煤油体系对氰化提金废水进行处理,主要研究CPB浓度、改性剂占比、pH值、混相时间、相比(O/A)对各金属离子萃取效果的影响及反应机制。研究表明:在85 g/L CPB−仲辛醇(25%,体积分数)−磺化煤油体系,O/A为1:1、pH值为11、混相时间为5 min的条件下,经三级萃取后,氰化废水中总氰(CN_(T))去除率可达到80%以上,铜、锌、铁离子萃取率分别为78.5%、79.4%、58.1%;各金属离子存在竞争萃取现象,萃取优先顺序依次为Zn>Cu>Fe。萃取饱和负载有机相经2.5 mol/L的NH4SCN溶液反萃,O/A为2.5时,铜、锌、铁离子反萃率分别为87.7%、90.3%、85.8%,反萃液中总金属离子浓度可达到7822.8 mg/L,实现了金属氰络合离子的有效富集。萃取过程中金属以金属氰络合离子的形态进入有机相,符合离子缔合原理。

In this paper,cetylpyridinium bromide(CPB)-secondary octanol-sulfonated kerosene system was used to treat cyanide gold extraction wastewater.The effects of CPB concentration,modifier ratio,pH value,mixing time and phase ratio(O/A)on the extraction efficiency of each metal ion and the reaction mechanism were mainly studied.The results show that under the conditions of 85 g/L CPB-secondary octanol(25%,volume fraction)-sulphonated kerosene system,O/A ratio of 1:1,pH value of 11,and mixing time of 5 min,the removal rate of total cyanide(CNT)in cyanide wastewater after tertiary extraction can reach more than 80%,and the extraction rates of Cu,Zn and Fe ions are 78.5%,79.4%and 58.1%,respectively.There is a competitive extraction phenomenon for each metal ion,and the extraction preferential order is Zn>Cu>Fe.The saturated organic phase is back-extracted by 2.5 mol/L NH4SCN solution when O/A is 2.5,and the stripping rates of Cu,Zn and Fe ions are 87.7%,90.3%and 85.8%,respectively.The total metal ion concentration in the back-extraction solution is 7822.8 mg/L,which realizes the effective enrichment of metal cyanide complex ions.In the extraction process,metal enters the organic phase in the form of metal cyanide complex ions,which conforms to the ion association principle.