Selective Removal Of Chloride Ions From Wet Zinc Smelting Electrolyte: Research On Methods And Processes Based On Diffusion Dialysis

Metal zinc is mainly produced by hydrometallurgical process,and the acidic electrolyte produced in the electrolytic deposition stage needs to be recycled in the leaching stage,which leads to the accumulation of impurities,especially impurities such as chloride ion,and the accumulation of chloride ions will not only influence the process of production but also lower the quality of the metal zinc.Up to date,many methods have been tried to remove the impurities of chloride ion from the electrolyte,but there is not a satisfactory method till now.As a traditional membrane separated process,diffusion dialysis is widely used in the recovery of acid and alkali due to its energy saving and environmental protection.Our job is to selectively remove halide impurities from the electrolyte by diffusion dialysis?DD?.This paper mainly describes a series of studies on the selectived removal of chloride ions by the diffusion dialysis method in the electrolyte,which mainly focusing on the following two aspects.?1?In this work,we propose a new method that extends the application of diffusion dialysis from traditional acid/base recovery to selectived separation of ions.The mobility of water,anion permeability,cation permeability and selectivity of anion at different flow intensities were discussed and analyzed.The results show that Cl^-and F^-have relatively obvious selectivity to HSO₄^-,the highest ion transmitting of Cl^-and F^-are up to 69.36%and 40.14%respectively,while the loss rate of Zn²⁺is about 1%.The mass transfer mechanism of selectivity was elaborated,and a set of impurity removal craftworks was designed according to the practical situation of the factory.?2?In this study,the impurity removal process was optimized on the basis of the previous work.Under the optimal flow intensity(4L·h^-1·m^-2),By adjusting the acidity of the zinc sulfate electrolyte,the mobility of water,anion and cation permeability,and selectived separation of anions and cations were discussed and analyzed.The results show that the selectivity of chlorine removal is greatly improved in the neutral electrolyte,and the selectived permeability is increased from the 2.56 to the 42.8.At the same time,the removal rate of Cl^-remained stable from55.1%to 46.6%,but the removal rate of SO₄^2-declined from 21.5%to1.09%.The increase of selectivity was studied in depth,with the practical situation of the plant in different acidity,we estimate the cost.