A review of hematite flotation using 12-carbon chain collectors

A sample of naturally occurring, relatively pure hematite (98.5% Fe2O3) was used as a model for the study of the flotation of insoluble metal oxides. The isoelectric point of this sample was 2.7 and the point of zero charge was 6.7. A number of surfactants containing saturated 12-carbon chain groups were used as collectors over a wide range in pH. otation of this hematite with dodecanoic acid (lauric acid) showed a maximum recovery in the pH range 6–8.5, a sudden drop at pH 9, and a steady increase in recovery as the pH was raised from 9–12. The flotation of the hematite using potassium dodecyl hydroxamate showed a maximum recovery at pH 5.5, with little flotation at pH <3. AtpH >10, the recovery fell except at high additions of collector. The flotation of hematite using sodium dodecyl sulphate showed a high recovery for pH <6, a trough in recovery between pH 7 and 9, and a secondary maximum in recovery at pH 10. Different flotation behaviour was observed when sodium dodecyl benzyl sulphonate was used. Using ARMAC C, (a commercially available dodecyl ammonium acetate), a flotation maximum was observed at pH 8, with steadily decreasing recovery as the pH was raised or lowered from this value. These results are discussed in terms of the surface chemistry of the hematite and the solution chemistry of the various collectors used.