The treatment of cyanide from gold mine effluent by a novel five-compartment electrodialysis

Abstract

In this paper, a novel approach of five-compartment electrodialysis was proposed for the treatment of cyanide from gold mine effluent. Two different processing modes were introduced. In mode 1, the cyanide was removed with homogeneous ion exchange membranes and heterogeneous ion exchange membranes respectively. In mode 2, the recovery of cyanide was achieved with homogeneous monovalent anion exchange membranes (1-AEMs) and cation exchange membranes (CEMs). The applied voltage was optimized to improve the removal and recovery efficiency. In addition, pH variation (the recovery of alkaline solution) was investigated. The results showed that the CN− extraction percent of 87.14% was achieved at 30V applied voltage with the energy consumption of 8.33kWhm−3 in mode 2. Meanwhile, the removal rate reached up to 97.90% with homogeneous ion exchange membranes at 38V applied voltage in mode 1, which was much higher than the case of heterogeneous ion exchange membranes (74.02%). Finally, the recovery of alkaline solution was achieved as above and the recovered alkaline solution could be reused for pH adjustment in ED process. This research provides a new insight into the resource recycling of cyanide from gold mine effluent in industrial application.