Behavior of cobalt-containing phases in hydrochloride decomposition of sulfide Cu–Ni materials

Abstract

Effect of the solution redox potential on the behavior of cobalt-containing phase components of sulfide copper-nickel concentrates in the Cu(II)/Fe(III)–Cl––HCl–Cl₂ system was studied. It was shown that, at solution redox potentials in the range 350–650 mV, phases based on heazlewoodite, pentlandite, cobaltous pentlandite, and cobalt pentlandite are transformed to thiospinels from the linneite group (M₃S₄, where M = Ni, Fe, Co). The resulting thiospinels are dissolved, with the exception of Co₃S₄, at solution redox potentials of 450 mV and less. The Co₃S₄ thiospinel is a stable compound in concentrated chloride solutions up to 650 mV, which, in the system under study, may be a reason for the poor cobalt recovery from sulfide concentrates.