Chinese Journal of Chemical Engineering, Vol.27, No.5, 1037-1043, 2019
Removal of chloride from simulated acidic wastewater in the zinc production
The removal of chloride from the zinc electrolyte produced during hydrometallurgical zinc production is challenging. The ion-exchange method is a promising way to remove chloride if the resin washing wastewater can be recycled. This paper focuses on chloride removal from resin washing wastewater to enable its reuse. Various processing factors including the oxygen gas velocity, temperature, and reaction time were investigated systematically. The results show that the optimal conditions for dechlorination are an oxygen gas velocity of 0.5 L.min(-1), a reaction temperature of 80 degrees C, and a reaction time of 30 min. A dechlorination efficiency of 80% with a residual chloride ion concentration less than 200 mg.L-1 was achieved, which meets the requirements for the recycling of wastewater. The presence of manganese accelerates the dechlorination by forming a Mn2+-MnO2-MnO4--Mn2+ redox cycle. In this process, about 15 kg of the MnO2 and all of the zinc can be recovered from 100 m(3) wastewater, and the wastewater can be reused, which makes the ion-exchange method a promising technique for chloride removal. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights reserved.