Decomposition kinetics of zircon sand in NaOH sub-molten salt solution
(1. School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China;
2. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China)
2. National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China)
Abstract: Sub-molten salt was applied to the decomposition of zircon sand (ZrSiO4). The kinetics of the decomposition of zircon sand and the effects of reaction temperature, reaction time, NaOH content, agitation speed, and the NaOH/ore mass ratio on the decomposition rate of zircon sand in NaOH sub-molten salt were investigated. The results indicate that the decomposition rate of zircon sand increases with the increase in the reaction temperature, reaction time, and NaOH content. The shrinking-core model with surface chemical reaction-controlled process is the most applicable for the decomposition of zircon sand, with the apparent activation energy of 77.98 kJ/mol. The decomposition product is sodium zirconium silicate (Na2ZrSiO5), and the decomposition rate is higher than 99% under the optimal conditions.
Key words: zircon sand; decomposition; kinetics; sub-molten salt; sodium zirconium silicate