Reaction behaviors and amorphization effects of titanate species in pure substance systems relating to Bayer digestion

• Published in: Hydrometallurgy Vol. 171; pp. 86 - 94
• Main Authors: Wang, Yanxiu, Zhang, Ting-an, Lv, Guozhi, Zhang, Weiguang, Zhu, Xiaofeng, Xie, Liqun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2017
• Subjects: Alumina digestion; Amorphization effect; Bayer process; Reaction behavior; TiO2; Bayer process; Alumina digestion; Amorphization effect; Reaction behavior; TiO2
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/j.hydromet.2017.04.009

To understand the adverse effects of TiO2 on alumina leaching, the reaction behavior of TiO2 in a series of pure substance systems relating to Bayer digestion was systematically investigated based on thermodynamics, experiments, and comprehensive analyses. The results show that TiO2 is almost unreactive without alkali in the Bayer system. When free alkali does exist, TiO2 preferentially forms amorphous, metastable sodium titanate as a reactive intermediate and induces more side reactions. The physicochemical characteristics and the transformation of the amorphous metastable phase were described in detail. The findings from this study provide strong evidence explaining titanate species' reduction of the dissolution efficiency of alumina through amorphization and the elimination of adverse titanate effects via promoting the crystallization of amorphous metastable phase. Knowledge of these mechanisms deepens the understanding of the effects of titanate species in the Bayer process and assists in the prevention and control of titanate industrial hazards. We investigate the amorphization and transformation of Ti-containing minerals via their reaction behaviors in a series of pure substance systems relating to Bayer digestion in order to explain how titanate species adversely affects alumina digestion and how to eliminate the adverse amorphization effects by titanate transformation. [Display omitted] •Compared the behaviors in a series of Ti-containing pure substance systems.•Described the physicochemical characteristics of amorphous metastable intermediate.•Explained how TiO2 affect Bayer digestion through amorphization.•Investigated the transformation of amorphous metastable phase in different conditions.