Development of a New Combined Process for Nickel and Cobalt Recovery from Ferriferous Laterite Ores

The studies on the development of a new process for nickel and cobalt recovery from ferriferous laterite ores via a reducing roasting–sulfuric acid leaching are carried out. The conditions for the reducing roasting of the ores in the temperature range from 400 to 950°C and for the sulfuric acid leaching of the cinder (after cooling without air and passivation in water) at pH 1.4–3.0 and the weight ratio of the solid to liquid phases 1 : (3–4) in the temperature range from 25 to 95°C for 0.5–4 h are studied. General regularities of the reducing roasting of the ores with the selective metallization of nickel and cobalt (where the formation of wustite (FeO) is excluded; i.e, Fe 2 O 3 is reduced to Fe 3 O 4 ) are revealed. The conditions for the leaching of the cinder by sulfuric acid with nickel and cobalt recovery into a solution are established. The optimum parameters of these processes that make it possible to achieve high parameters for the recovery of nickel (87–99%) and cobalt (80–91%) into a solution at the sulfuric acid consumption within 90–140 kg/t ore are determined.