Abstract: A process for separating minerals of different mineralogical character. A milled slurry or flotation concentrate is subjected to a first conditioning step (20) followed by a first flotation step (30) followed by a second conditioning step (50) followed by a second flotation step (60). One of the conditioning steps is with an oxidising gas, the other of the conditioning steps being with a non-oxidising gas and an oxidisable surface modifying reagent. The process allows separation of mixtures of valuable minerals by tailoring both the first and second conditioning steps and first and second flotation steps to particular mixed mineral ores.