The use of collectors mixture in the reverse cationic flotation of magnetite ore: The role of Fe-bearing silicates

The paper describes effective reagent combinations for removal of silicates by reverse cationic flotation from magnetic concentrate in magnetite ores processing. This work is based on a hypothesis that a further development in reverse cationic flotation of iron ores implies, a more detailed consideration of the nature of the Fe-bearing gangue minerals. Thus, the choice of reagent regime has been determined by the similar physicochemical properties of iron oxides and silicates such as amphiboles due to inclusion of iron into their crystal lattice. Zeta-potential studies of Fe-oxides, quartz and Fe-bearing amphibole samples have shown that amines of different molecular structure are equally well adsorbed both on the surface of Fe-oxides and on the surface of silicates within рН range of 4–10. Flotation studies of quartz and Fe-bearing amphibole samples have revealed that the use of starch as a depressant of Fe-oxides has a hydrophilic effect on the surface of Fe-bearing silicates and significantly decreases their flotation by ether amines. Flotation of these minerals is not possible by primary monoamines in the presence of starch due to the adsorption layer formation.The experimentally selected mixtures of ether amines with primary monoamines or with alcohols provide formation of a hydrophobic adsorption layer on the surface of amphiboles and magnetite–silicate aggregates, even in the presence of starch in the system. A total hydrophobic effect is sufficient for an effective flotation of the entire silicate complex and producing of magnetite concentrates with SiO2 content <1.0% and Fe content up to 70.3% from magnetic concentrate with SiO2 content ∼3%.