湿法炼锌赤铁矿法沉铁过程机理分析

Mechanism analysis of iron precipitation process in zinc hydrometallurgy by hematite method

赤铁矿法具有伴生有价金属回收率高、铁渣可资源化利用等优势受到湿法炼锌行业的关注和青睐。赤铁矿法沉铁涉及高温复杂溶液中多个非均相反应,包括FeSO4结晶与返溶、Fe2+氧化、Fe3+水解、亚稳态铁物相形成与转化等过程。赤铁矿沉铁条件下,受同离子效应影响,FeSO4的溶解度随硫酸浓度增大而线性增长,随ZnSO4和MgSO4浓度的增大而减小。在180~200℃下,Fe2+氧化速率随反应温度的升高而加快,反应10~20 min后Fe2+氧化过程基本完成。适当升高反应温度或延长反应时间可抑制亚稳态铁物相——碱式硫酸铁(FeOHSO4)和铁矾(MFe3(SO4)2(OH)6)的形成并使其转化,从而获得较为纯净的赤铁矿沉铁渣。

Hematite process has received more and more attention because of its advantages of high valuable metals recovery and utilization of iron slag as second resource.Hematite precipitation involves multiple heterogeneous reactions at high temperature,including the crystallization and redissolving of FeSO4,oxidation of Fe2+,hydrolysis of Fe3+,and formation and transformation of metastable iron containing phase.The solubility of FeSO4 increases linearly with the increase of sulfuric acid concentration and decreases with the increase of the concentration of ZnSO4 and MgSO4 under hematite precipitation conditions.The oxidation rate of Fe2+accelerated with an increase in reaction temperature,and the Fe2+oxidation process was almost completed after 10~20 min at 180~200℃.The metastable basic ferric sulfate(FeOHSO4)and jarosite(MFe3(SO4)2(OH)6)can be inhibited and transformed to obtain relatively pure hematite slag by increasing the reaction temperature or prolonging the reaction time.