Investigation of the reverse flotation of iron ore in three different flotation cells: Mechanical, oscillating grid and pneumatic

[Display omitted] •Evaluation of the reverse flotation of hematite in a mechanical, oscillating grid and pneumatic flotation cell.•Coarse quartz recovery increases with increasing impeller speed to an optimum.•Coarse quartz recovery and fine hematite loss decrease with increasing froth height.•Fine hematite loss decreases significantly with decreasing solids concentration.•Theoverall flotation performance ofthepneumatic cell was better than the mechanical cell. This paper investigates the reverse flotation of iron ore in a laboratory mechanical, oscillating grid (OGC) and pneumatic flotation cell. The main objectives are to investigate the recovery of coarse quartz (+150 µm) by flotation and fine hematite (−25 µm) by entrainment. Agitation/energy input results show that coarse quartz recovery increases with increasing impeller speed to a maximum of ±70%. The recovery of coarse quartz in the OGC is ±10% higher than in the mechanical cell with an optimum at a low energy input of 0.1 W/kg. Froth height results show that coarse quartz recovery and fine hematite loss decrease by over 50% with increasing froth height. Solids concentration results show that coarse quartz recovery remains relatively constant with decreasing solids concentration, but fine hematite loss decreases from 15 to 5% at the maximum froth height due to lower water recoveries. The OGC generally results in the best overall flotation performance at lower energy input. The pneumatic flotation cell achieves better flotation performance than the mechanical flotation cell for most operating conditions.