Poster (EARTH)

[PE1-045] Research of Removing Fluoride from ZnSO₄ Solution by CaSO₄

Xuejiao Cao¹, ○Yan Liu¹, Ting'an Zhang¹, Yuhao Zhang¹, Weiguang Zhang¹, Kun Wang¹ (1. Northeastern University, China)

Keywords:Aluminum electrolysis, Desulfurization, Defluorination, Zinc sulfate, Calcium sulfate

The low concentration SO₂, fluorine and Al₂O₃ dust containing gas generated from aluminum electrolysis process is harmful to environment and human health. However, the existing fluorine removal technology of dry purification process cannot efficiently remove the low concentration SO₂ simultaneously. A method of ZnO combined with O₃ to produce ZnSO₄ is put forward to recover and remove the low concentration SO₂ in this paper. But during the process, HF is inevitable adsorbed into the ZnSO₄ solution, which is bad to recover ZnSO₄ by evaporative crystallization. So conditions of precipitation agent dosage, reaction time, pH, temperature, stirring speed are investigated to remove F^- from ZnSO₄ solution by CaSO₄ slag. Results show that the highest rate of fluoride removal is up to 87.93% under the best conditions of 2 times of the theoretical amount precipitant, reaction time 90min, pH4.5, 50℃, stirring speed of 900 rpm. The concentration of F^- in the ZnSO₄ solution is less than 130mg/L and the zinc loss rate is less than 5%.