Depressive effect of oxalic acid on titanaugite during ilmenite flotation

• Oxalic acid selectively depressed titanaugite during ilmenite flotation.
• C2O42− is the dominant form in oxalic acid solution when pH > 4.19.
• Oxalic acid chemisorbed onto titanaugite by reaction with metal ions.
• Ca2+ is preferable to react with C2O42− thermodynamically, followed by Fe2+, Mg2+.

Ilmenite and titanaugite have very similar physiochemical properties. Iron, titanium, calcium, magnesium, and other metal ions exist on the surface of both minerals, making it difficult to separate the two minerals. In this study, oxalic acid was used as a depressant in the microflotation of ilmenite and titanaugite and the depressive effect of oxalic acid toward titanaugite was demonstrated. Through a series of microflotation, oxalic acid composition analysis, reaction thermodynamic calculations, and XPS analysis, oxalic acid was found to significantly and selectively inhibit titanaugite. Oxalic acid was adsorbed onto mineral surfaces via a chemical chelating reaction with metal ions, predominately Ca2+. Therefore, oxalic acid selectively depressed titanaugite during ilmenite flotation.