This invention relates to a method where sulfidic iron-bearing copper concentrate
is leached on the countercurrent principle, in a chloride environment. The leaching
takes place with the aid of bivalent copper and an oxygen-bearing gas as a multi-stage
continuous process, under normal pressure, at a temperature, which as highest corresponds
to the boiling point of the solution. Part of the insoluble solid matter is returned,
counter to the main flow of solid matter, to one of the previous leaching stages
or reactors where, as a result of the extended leaching time, the leach waste iron
is recovered mostly as hematite.