Flotation separation of ilmenite and titanaugite modified by Fe2+-assisted peroxymonosulfate oxidation: Performance and activation mechanism

Abstract

Efficient separation of ilmenite and titanaugite has always been recognized challenge in modern mineral processing. The use of a heterogeneous Fenton-like oxidation process composed of peroxymonosulfate (PMS) and Fe²⁺ is promising to address this issue. Flotation findings indicated that effective recovery of ilmenite could be achieved under weak acidic conditions, and a TiO₂ recovery of 81.56 % and a grade of 32.16 % concentrate was collected. A series of characterization analyses confirmed that the PMS-Fe²⁺-mediated Fenton-like reaction in the ilmenite system generated more •OH and SO₄^•- radicals, which oxidized Fe²⁺ to Fe³⁺ on its surface, thus improving the active sites on ilmenite surface. Moreover, PMS-Fe²⁺ promoted the positive shift of surface charge on ilmenite, facilitating NaOL adsorption and making the surface more hydrophobic. NaOL primarily interacted with Fe active sites on the ilmenite surface and Mg²⁺ and Ca²⁺ active sites on the titanaugite surface in the formation as chemisorption. Thus, PMS-Fe²⁺ activated ilmenite mainly via augmenting the quantity and reactivity of Fe active sites on the surface. In summary, these findings provide the innovative pathways to implement the advanced oxidation processes in mineral flotation.