Effect of zinc(II) and caustic content on the decomposition of sodium aluminate solutions and relevance to the Bayer process

• Published in: Hydrometallurgy Vol. 225; p. 106287
• Main Authors: Xu, Lei, Chen, Wen-mi, Zhang, Yan-jun, Fan, Shang, Pi, Jian-qing, Wang, Ming-li
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2024
• Subjects: Aluminum hydroxide; Crystal seed decomposition; Sodium aluminate solution; Zinc; Sodium aluminate solution; Zinc; Crystal seed decomposition; Aluminum hydroxide
• ISSN: 0304-386X; 1879-1158
• DOI: 10.1016/j.hydromet.2024.106287

The impact of zinc (Zn) on the seed decomposition process of sodium aluminate solution at different caustic concentrations was investigated. The results showed that as the concentration of Zn(II) in sodium aluminate solution increased from 0 to 1000 mg/L, the decomposition efficiency of the solution and average grain size of the resulting aluminum tri-hydroxide (ATH) changed little at a caustic concentration of 141 g/L. At caustic concentrations of 160 g/L and 177 g/L, the decomposition efficiency increased from 35.8% and 21.6% to 40.6% and 24.9%, respectively, while average grain size of the ATH crystal seeds increased from 14.2 and 9.25 μm to 17.9 and 15.9 μm, respectively. The XRD, FT-IR, and SEM analyses showed that zinc can enter the ATH seeds and interact with the α-ATH crystal planes. It may also form interactions with the AlO octahedral growth structure, thus promoting solution decomposition and influencing crystal growth. The research results will provide valuable references for improving the quality of alumina products. [Display omitted] •Effect of Zn on decomposition of sodium aluminate solution was studied in detail.•Decomposition mechanism of Zn-containing sodium aluminate solutions was explored.•The possible structures of substances formed from Zn and aluminum tri-hydroxide were explored.