Stepwise recovery of Zn, In, Ga, and Fe from jarosite residue through oxidizing roasting-direct reduction-smelting-electrorefining process
(1. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China;
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China)
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China)
Abstract: An efficient process based on oxidizing roasting-direct reduction-smelting-electrorefining was developed to separate and recover Zn, In, Ga and Fe from a typical hazardous jarosite residue. Phase transformation and element migration during each separating process were evaluated by X-ray diffraction analysis (XRD), thermo-gravimetric- differential scanning calorimetry (TG-DSC), and scanning electron microscopy-energy dispersive spectrometry (SEM-EDS). The results show that the jarosite residue decomposed into hematite and zinc ferrite when oxidizing roasted at 1250 °C for 20 min. Then, Zn and In were volatilized and enriched into flue dust through the reductive roasting of oxidized pellets at 1200 °C for 60 min. Finally, Fe and Ga were separated by smelting-electrorefining of the reduced pellets to obtain high purity iron powder with 99.5% Fe and anode slime with 456 g/t Ga. Through the process, a total recovery of 97.42% Zn, 87.86% In, 90.70% Fe and 84.78% Ga can be achieved.
Key words: jarosite residue; gallium; indium; recovery; electrorefining