Nickel and Cobalt Ores: Flotation

Most of the world’s nickel is extracted from the mineral pentlandite, (Ni, Fe)9S8, which frequently occurs in ores containing predominantly pyrrhotite and various non-sulRdes, some of which contain magnesium (Table 1). The nickel content in such sulRde ores is generally low (0.2}3%) and varies from place to place in the same deposit. The low nickel content of the present-day nickel sulRde ores renders them unsuitable for either direct smelting or hydrometallurgical extraction, thus requiring beneRciation. The usual method of nickel extraction from sulRde ores is through the production of nickel matte after enriching the nickel content of the ore. This is commonly carried out by magnetic separation, Sotation, or a combination of both after the ore is comminuted to below 200 m in size. The enrichment depends upon the degree of rejection of the other sulRde and non-sulRde gangue. The maximum grade of nickel achieved by Sotation is around 28% Ni.