Leaching Behavior and Kinetics of Ilmenite Ore with NaOH Hydrothermal Method

Abstract:

The leaching behavior and kinetics of ilmenite ore with NaOH hydrothermal method was researched in this work, and the innovative metallurgical process for leaching titanium from ilmenite ore is proposed with NaOH hydrothermal method in order to overcome the severe dilute H₂SO₄ waste water pollution of current titanium extraction process in industry. It is determined that the optimal reaction conditions is as follows: the reaction temperature 240℃, NaOH concentration 400 g.L^_-1, the mass ratio of alkali to ore 3.5:1, partial oxygen pressure 0.5 MPa, reaction time 2 h, agitation speed 600 rpm, and ore particle size <75μm, and the leaching degree of titanium can reach 95%. Based on XRD analyses and SEM microstructure examination, the decomposition behavior of ilmenite ore was investigated and the generating of sodium titanium particles were observed. The producing phenomenon of the product layer was not found during leaching. The leaching kinetics study shows that the leaching rate of ilmenite ore with NaOH hydrothermal method is controlled by the solid product layer diffusion with the apparent activation energy of 47.39 kJ/mol and an empirical rate equation is “1-2X/3-(1-X)^_2/3=[735.09exp(-47389.8/RT)]t”.

Key words:Ilmenite ore; NaOH hydrothermal method; titanium leaching degree; leaching behavior; kinetics