CaO改质对铁酸锌中锌选择性浸出的影响

Effect of CaO modification on selective leaching of zinc from ZnFe_2O_4

炼钢粉尘中锌的主要存在形式为铁酸锌(ZnFe_(2)O_(4)).为了分离回收铁酸锌中的锌,利用CaO改质铁酸锌,再利用盐酸对改质铁酸锌进行选择性浸出,研究了Ca和Fe的摩尔比、pH值及温度对改质铁酸锌中各金属元素浸出的影响.研究结果表明:CaO焙烧改质能将铁酸锌充分转化为铁酸二钙(Ca_(2)Fe_(2)O_(5))和氧化锌(ZnO);提高Ca和Fe的摩尔比对改质铁酸锌中锌、铁的浸出无明显影响,但能增加钙的浸出率;随着pH值的增加,改质铁酸锌中铁、锌、钙的浸出率均降低;升高温度能促进改质铁酸锌中铁酸二钙的溶解,铁和钙的浸出率均显著升高.当Ca和Fe的摩尔比为1.3、pH值为2、温度为25℃时,改质铁酸锌中锌的浸出率达到94.11%,而铁的浸出率仅为9.8%,实现了锌和铁的有效分离,可为后续锌的电解回收创造良好条件.

Zinc in steelmaking dust mainly exists in the form of zinc ferrite.In order to separate and recover zinc from zinc ferrite,calcium oxide was used to modify zinc ferrite,and then hydrochloric acid was used for selective leaching the modified zinc ferrite.The effects of the stoichiometric ratio of Ca and Fe,pH value and temperature on the dissolution of metal elements in modified zinc ferrite were studied.The results showed that zinc ferrite could be fully converted into calcium ferrite and zinc oxide by roasting modification of calcium oxide.Increasing the stoichiometric ratio of Ca and Fe had no significant effect on the leaching rate of Zn and Fe in modified zinc ferrite,but increased the leaching rate of Ca.With the increase of pH,the leaching rate of Fe,Zn and Ca in modified zinc ferrite decreased.Increasing temperature could promote the dissolution of modified zinc ferrite,resulting in a significant increase in iron and calcium leaching rates.When Ca and Fe molar ratio was 1.3,pH value was 2 and the temperature was 25℃,the leaching rate of zinc in modified zinc ferrite was 94.11%,while the leaching rate of iron was only 9.8%.The effective separation of zinc and iron in zinc ferrite has been realized,which could create good conditions for the subsequent electrolytic recovery of zinc.