Study Of Extraction Of Chloride Ion From Zinc-bearing Waste Lixivium

In industrial production, there are large amounts of zinc in waste produced after extracting indium. It is wasteful and pollutes the environment if waste produced directly emissions.In this paper, zinc-bearing waste lixivium after dipped in sulfuric acid from one company in Qinghai after extracting indium was studied, which contains large amounts of Zn2+ and SO42-. It was used as the raw material of Zn SO4·n H2 O fodder, but now they are inactive. So the waste lixivium can be used as the raw material to eletrodeposit zinc. But there are a large amount of Cl- in the waste lixivium due to a closed-circuit. And the concentration of Cl- must be below 0.3 g·L-1. The chloride produced during electrolyzing zinc with the pickle liquors is harmful to anode plate and the environment of workshops.This paper presents research on extracting and stripping Cl- from zinc-bearing waste lixivium by using trioctylamine as an extractant, A additive as a solvent for better separationphase,sulfonated kerosene as a diluentand Na OH solution as a stripping agent. The extraction process, extraction technology and extraction mechanism were studied. The main work is as follow:(1) A single-stage extraction experiments were measured by using organic phase containing different volume ratio trioctylamine, A additive and sulfonated kerosene. It was found that two phases were completely separated in the extraction process by adjusting the p H of zinc-bearing waste lixivium and washing organic phase with acid. Univariate experiment such as composition of organic phase, phase ratio, and p H of zinc-bearing waste lixivium were determined. The optimal conditions were achieved. The composition of organic phase was VTOA:VA additive:Vkerosene=3:2:5, organic phase was washed by equivalent 1 mol·L-1 H2SO4, O/A ratio was 3:2, the p H of zinc-bearing waste lixivium was adjusted to below than 0.3. The percentage extraction of Cl- was 92.77%, and the partition ratio was 12.80. The concentration of Cl- in aqueous decreased from 24.43 g·L-1 to 1.77 g·L-1. The result of single-stage extraction was well.(2) The extraction mechanism was studied. Therewere two extraction mechanismsincluding ionic association and ionic interchange. According to the concentration of the changes of negions and cations, the extraction mechanismwas ionic association mainly.(3) The results of extraction and stripping technology of Cl- using 30%TOA-20%A additive-50%sulfonated kerosene extraction system indicated that the percentage extraction of Cl- in three-stage concurrent extraction was 99.47%. The concentration of Cl- in aqueous decreased to 0.13 g·L-1. When the stripping agent was 5% Na OH solution and the stripping O/A was 5:2, the stripping process was exhaustive at single-stage stripping. After five-stage extraction technology experiment, the percentage extraction of Cl- was more than 98.83%, which satisfied the Cl-concentration in zinc electrolyzing solution. The capability of the extraction was retained after serial cycles without solution loss and emulsifying phenomenon.