A novel technology for the refinement of low-grade ilmenite concentrate

In this paper, the refinement of low-grade ilmenite concentrate was studied. It was found that by transforming in NaOH/NaNO3 molten salt, and then leaching in water and in dilute hydrochloric acid, the low-grade ilmenite concentrate containing 3.09 wt% Mg, 1.03 wt% Ca, 3.38 wt% Si and 1.54 wt% Al can be refined well, meanwhile the contents of Ti and Fe are not affected. The lattice of ilmenite concentrate can be completely destroyed in the molten salt with NaOH/NaNO3 weight ratio 7:3 at 400 °Cfor 6 h. The removal rates of Mg, Al, Ca and Si are 86.62%, 90.55%, 92.62%, 92.90% respectively by leaching the transformed concentrate in water with L/S ratio 2:1 mL/g at 60 °C for 0.5 h, and leaching the water leached residue in dilute HCl solution with L/S ratio 4:1 mL/g under pH 1.2 at 40 °C for 2 h. The contents of Mg, Al, Ca and Si are 0.41 wt%, 0.13 wt%, 0.08 wt% and 0.21 wt% respectively in the refined concentrate, which is suitable for arc reduction smelting to produce high-quality titanium slag.