Magnetic properties of ilmenite, hematite and oilsand minerals after roasting

To recover heavy minerals from the Athabasca oil sands tailings, a roasting step is necessary to burn off the residual bitumen. However, most of the previous researchers, using a roasting step, did not seem to be able to separate the Fe-bearing titanium minerals (ilmenite and leucoxene) from the Fe-free titanium minerals (rutile and anatase). An investigation was therefore carried out to study the changes in magnetic properties after roasting to the types of minerals contained in the oil sands tailings. Ilmenite, hematite, and a rutile concentrate (LR Rutile) produced from the oil sands tailings (containing mainly leucoxene and rutile), were used in the study. It was observed that the magnetic susceptibility of ilmenite increased after either oxidation or reduction roasting at some intermediate temperatures and roasting time. For hematite, reduction roasting increased its magnetic susceptibility and oxidation roasting did not seem to have any effect. Reduction roasting of the LR Rutile resulted in an increase in its magnetic susceptibility, and this increase was mainly due to the contaminating Fe-bearing minerals (leucoxene). Upgrading of the LR Rutile was possible either by using low intensity magnetic separation following reduction roasting, or by using high intensity magnetic separation directly.