Selective flotation separation of ilmenite from fine-grained titanaugite utilizing environmentally friendly depressant sodium alginate: Experimental and mechanistic study

The flotation separation of fine-grained ilmenite and titanaugite is a challenging issue. This study employed an environmentally friendly inhibitor, sodium alginate (SA), to overcome this challenge. Single mineral flotation results demonstrated that SA exhibited significant depression on fine-grained titanaugite over a wide pH range, while inhibitory effects on ilmenite was small. Furthermore, binary mixed mineral flotation experiments revealed that a concentrate with a grade of 37.52 % and a recovery of 65.15 % could obtain using 6.0 mg/L of SA. AFM images confirmed that SA had stable and dense adsorption on the surface of titanaugite compared to ilmenite, which hindered further adsorption of NaOL. Zeta potential and FTIR analyses indicated that SA underwent strong chemisorption on the titanaugite surface, while its interaction with ilmenite was comparatively weak, resulting in a considerable increase in the floatability difference between the two minerals. XPS analysis and DFT calculations confirmed that the carboxyl group within SA formed a stable bridge adsorption configuration with the Ca and Mg sites of titanaugite. However, SA had feeble influence the chemical interactions between NaOL and the Fe site on ilmenite. Consequently, SA shows a greater affinity for titanaugite than ilmenite, which facilitates the selective separation of fine-grained ilmenite from titanaugite.