Selective flotation of ilmenite from diopside using 8 hydrox 2027 Minerals E

Selective flotation separation of ilmenite from calcium–magnesium silicate gangue remains challenging due to the weak natural hydrophobicity of ilmenite and the insufficient selectivity of conventional collectors. This study evaluates 8-hydroxyquinoline (8-HQ) as a selective collector for ilmenite–diopside separation. Using conditions of pH 7.0 ± 0.2 and an 8-HQ concentration of 1.0 × 10 −4 mol L−1, single-mineral recoveries of ilmenite and diopside were determined to be 90.1% and 25.0%, respectively. Flotation of artificially mixed minerals under these conditions yielded a concentrate containing 43.8% TiO2 with a recovery of 86.7%, thus demonstrating effective separation of ilmenite from diopside. The contact angle of ilmenite increased from 42.1° to 78.2° after 8-HQ treatment, while diopside's increased from 27.2° to 35.8°. UV–vis analysis revealed an adsorption amount of 0.138 mg g−1 of 8-HQ on ilmenite, approximately 3.6 times that on diopside. Additional spin-polarized calculations suggested an adsorption energy of approximately −1.66 eV with optimized Fe–N and Fe–O distances of 2.14 and 2.48 Å. These results indicate that selective adsorption of 8-HQ on exposed Fe sites enhances ilmenite's hydrophobicity, facilitating its effective flotation separation from diopside.