采用冷冻结晶工艺对钛白副产硫酸亚铁进行了提纯研究，重点考察了结晶母液循环时镁、锰杂质的累积情况以及它们的去除规律，同时对可能引入体系的钠杂质影响也进行了研究。通过多次结晶可以逐渐降低七水硫酸亚铁晶体中镁、锰杂质含量，但结晶母液的循环会导致体系内镁、锰杂质逐渐累积。利用结晶液与结晶体中镁、锰含量的关系曲线推断得到：当结晶液中镁含量低于298 mg/L时，七水硫酸亚铁晶体中镁质量分数将低于0.025%；当结晶液中锰含量高于761 mg/L时，七水硫酸亚铁晶体中锰质量分数将高于0.05%。另外，结晶法提纯硫酸亚铁时应避免向体系中引入钠离子，否则会导致七水硫酸亚铁晶体中钠杂质含量超标问题。该论文研究结果可以为利用结晶法提纯钛白副产硫酸亚铁提供一定的理论和技术指导。

The freezing crystallization process was used to study on purification of by-product ferrous sulfate of titanium dioxide.The accumulation of Mg and Mn impurities and their removal rules during the circulation of the crystallization mother liquor were mainly investigated.Meanwhile，the influence of Na impurities that may be introduced into the system was also studied.Through multiple crystallizations，the Mg and Mn impurities in FeSO₄·7H₂O could be gradually reduced，but the circulation of the crystallization mother liquor would cause the gradual accumulation of Mg and Mn impurities in the system.By using the relationship curve between the content of Mg and Mn in the crystal liquid and the crystal，it could be inferred that the Mg content in the FeSO₄·7H₂O would be lower than 0.025% when the Mg content in the crystal liquid was less than 298 mg/L，and the Mn content in FeSO₄·7H₂O would be higher than 0.05% when the Mn content in the crystal liquid was higher than 761mg/L.In addition，Na should be avoided to introduce into the system，otherwise it would cause the Na impurity content in FeSO₄·7H₂O to exceed the standard.The research results of this paper could provide certain theoretical and technical guidance for purifying by-product ferrous sulfate of titanium dioxide by crystallization approach.