Selective Recovery of Scandium From Sulfating Roasting Red Mud By Water Leaching

摘要

A completely new process of selectively recovering Sc~(3+) without impurity of Fe~(3+) from Bayer red mud was developed. Prior to water leaching process, red mud needs to be digested and sulfated at a low temperature and subsequently roasted at a higher temperature for a period of time. During the roasting process, the products such as SO_2, SO_3 and H_2SO_4 molecules of thermal decomposition of sulfites including NaFe(SO_4)_2 and NaAl(SO_4)_2 could be recycled and reused as the raw materials of sulphuric acid. The leaching results indicate that roasting temperature and roasting time are the main constraint on selective leaching performance of scandium. As the sulfated red mud sample is roasted at 750 ℃ for 40 min and subjected to water leaching at 50 ℃ for 30 min, 53.0 wt% Sc~(3+), <1.0 wt% Fe~(3+), <0.3 wt% Si~(4+) and ~8.9 wt% Al~(3+) could be leaching out. Of note, the solid-liquid separation process is quite easy to be carried out.