铁矾渣酸浸液磷酸除铁过程研究

Study on Iron Removal with Phosphoric Acid from Acid Leaching Solution of Jarosite Slag

针对"锌渣焙烧—酸浸提铟和锌—氯盐浸银和铅"处理湿法炼锌铁矾渣焙烧温度范围窄、难以工业应用的难题,提出"铁矾渣焙烧—酸浸—酸浸液磷酸除铁并副产磷酸铁—除铁后液提铟和锌"新工艺,重点研究铁矾渣酸浸液磷酸除铁过程,包括磷酸除铁工艺条件、动力学变化规律、副产磷酸铁物相。研究结果表明,较优的铁矾渣酸浸液磷酸除铁工艺条件为:P/Fe=0.9、温度85℃、时间8h、诱导剂加入量0.7g,除铁率为58.08%、铟损失率26%,铁矾渣中铁浸出率由23%降为9.66%(≤10%),除铁后铟浸出率为70.3%(≥70%),酸浸液中Zn^(2+)在磷酸除铁过程中损失很小,不受影响,三种元素浸出率均符合指标要求。磷酸除铁反应过程和铟损失过程均基本符合零级反应,反应活化能分别为51.25和46.12kJ/mol。磷酸除铁过程副产高纯度结晶型FePO_4·2H_2O。铁矾渣焙烧温度调节宽度达到70℃。

To address narrow roasting temperature range and difficulty of industrial application of original combined process of"zinc slag roasting,acid leaching of indium and zinc,chloride leaching of silver and lead"in treating jarosite slag from zinc hydrometallurgy,a new process of"jarosite slag roasting,acid leaching,iron removal from acid leaching solution with phosphoric acid and produce byproduct of ironic phosphate,extracting indium and zinc after iron removal"was put forward.The process to remove iron from acid leaching solution of jarosite slag by phosphoric acid was studied,in terms of technological conditions,law of kinetic and phase of by-product of ferric phosphate.The results show that the optimum conditions for iron removal include P/Fe=0.9,temperature of 85℃,time of 8 h,and inducer dosage of 0.7 g,under which,iron removal rate is 58.08%and indium loss rate is 26%,Fe leaching rate in jarosite slag is reduced from 23%to 9.66%(≤10%),indium leaching rate after iron removal is 70.3%(≥70%),and loss rate of Zn2+in acid leaching solution is very small.The leaching rates of three elements all meet the requirements of the index.Iron removal and indium loss during iron removal with phosphoric acid basically accord with zero order reaction with activation energy of 51.25 kJ/mol and 46.12 kJ/mol,respectively.High purity crystalline FePO4o2H2O is by-product.The roasting temperature range of jarosite slag is 70℃.