The flotation characteristics of a nickel sulphide transition ore are investigated by laboratory tests with regard to two aspects, the recovery of magnesia bearing gangue, and the depression of the nickel sulphides by gangue slime coatings. The ore, from the Perseverance deposit of Western Mining Corporation at Leinster in Western Australia, is shown to have only a small proportion of naturally floating magnesia minerals, and the dominant recovery mechanism of magnesia is shown to be recovery of magnesia ulphide composites by sulphide flotation. Depression of nickel sulphides by slimes of magnesia minerals is demonstrated by comparison with cyclone deslimed flotation feed. Carboxy methyl cellulose (CMC) acts as a slime dispersant, not as a magnesia depressant, but the dosage required to achieve satisfactory nickel recovery is uneconomically high. 10 % sodium chloride solution is shown to give superior results, compared to CMC, particularly in the flotation of fine material. Deslimed feed exhibits partial natural flotation of nickel sulphides.
