Effects of frother type and froth height on the flotation behaviour of chromite in UG2 ore

About 70% of the UG2 reef consists of the gangue mineral chromite (FeO · Cr₂O₃). In the processing of UG2 ore by flotation for the recovery of platinum group elements (PGEs) the presence of chromite in the concentrates can cause serious downstream processing problems and a grade of less than 3% Cr₂O₃ is sought. This constrains operating procedures and compromises optimum recovery of the PGEs.In this study, the influence of the froth phase on the recovery of chromite was investigated by changing both frother type and dosage and froth height in batch scale flotation tests. The results obtained showed that it was possible to obtain concentrates with less than 3% Cr₂O₃ content by increasing the froth height, allowing for better drainage of both entrained gangue particles and coarse particles with low hydrophobicity. At a 3 cm froth height, very low water and mass recovery were obtained and thus low entrainment. Nevertheless a small amount of chromite particles coarser than 45 μm was persistently recovered which may be attributed to the true flotation of these particles.The mechanism of chromite recovery was discussed on the basis of the difference in the appearance of the froth structure and water recovery.