NaOH分解含铟铁矾渣新工艺

Novel technique of decomposition of ammonium jarosite bearing indium in NaOH medium

提出NaOH分解含铟铁矾渣新工艺,考察NaOH用量、液固比、温度和时间对铁矾渣分解率的影响,并讨论铁矾渣中杂质金属,如Zn、In、Cu、Cd、Pb、As、Sb、Sn和Ag等在NaOH分解过程中的行为。结果表明:在m(NaOH):m(铁矾渣)=0.3814:1、温度60℃、液固比2:1、反应时间2h的最优条件下,铁矾渣的分解率达到98.03%,而原料中的杂质金属,如Sn、Sb、Zn、In、Cu、Cd、Pb和Ag等绝大部分留在分解渣中,As则以AsO43-的形态大部分进入溶液,浸出率达到83.36%。DSC-TGA热分析和X射线衍射分析结果表明:在NaOH分解过程中,铁矾渣中的铁主要以Fe3O4形式沉淀入渣;分解渣中Fe、In和Zn的含量分别为38.81%、0.23%和12.89%;经稀盐酸选择性浸出铟和锌后,进一步磁选富集可作为炼铁原料。

The decomposition of ammonium jarosite bearing indium in NaOH medium were studied. The effects of NaOH addition, liquid-solid ratio, decomposition temperature and time on the decomposition ratio of ammonium jarosite were investigated, respectively, and the behavior of impurity elements, such as Zn, In, Cu, Cd, Pb, As, Sb, Sn andAg in jarosite residues was also discussed. The results show that the decomposition rate of ammonium jarosite can reach 98.03% under the following optimum conditions, which are m（NaOH）：m（jarosite）=0.381 4：1, temperature 60℃, liquid-solid ratio 2：1, reaction time 2 h. During the alkaline decomposition, the impurity elements, such as Zn, In, Cu, Cd, Pb, Sb, Sn and Ag are left in the residue, while As is leached into the pregnant solution as AsO43- with leaching rate of 83.36%. DSC-TGA thermal analysis and XRD characterization results demonstrate that Fe is precipitated as Fe304 during alkaline decomposition of jarosite. The contents of Fe, In and Zn in decomposition residue are 38.81%, 0.23% and 12.89%, respectively. After selective leaching of In and Zn with dilute HCI solution, the iron concentrates obtained from magnetic separation can be used as raw material for iron smelting.