The invention relates to a method for recovering non-ferrous metals,
particularly nickel, cobalt, copper, zinc, manganese and magnesium, from
materials containing said metals by converting said non-ferrous metals
into sulphates by means of melt and melt coating sulphation, i.e. by a
thermal treatment under oxidizing conditions within a temperature range of
400 to 800.degree. C., during which a reaction mixture is formed
containing at least one said non-ferrous metal, iron(III)sulphate and
alkali metal sulphate, and appropriate reaction conditions are selected to
substantially prevent iron(III)sulphate from thermally decomposing to
hematite, and finally, said non-ferrous metals are recovered as metallic
compounds. In the method of the invention, a process is formed around the
melt and melt coating sulphation, which comprises nine steps. The
invention is particularly characterized by the manner of pelletizing the
material to be fed into step 2 with an alkali metal (Na, K)
sulphate--sulphuric acid--water solution, during which the hematite
(Fe.sub.2 O.sub.3) contained in the feed material will at a suitable
temperature react with sulphuric acid and form hydrous iron(III)sulphate
which together with sodium sulphate also acts as the bonding agent
required in the pelletizing.