METHOD OF REWORKING IRON CAKE CONTAINING NON-FERROUS METALS Russian patent published in 2005 - IPC

FIELD: hydro-metallurgy; reworking iron cakes containing non-ferrous metals, nickel and cobalt in particular; utilization of by-products of hydro-metallurgy for return of valuable components to technological process.

SUBSTANCE: moist cake is subjected to treatment with sulfuric acid in presence of ferric chloride (III) introduced in the amount of 4.5-7.5 mass-% of FeCl₃ relative to Fe₂O₃ contained in pulp. Then, iron is reduced to bivalent state by sodium sulfite solution at concentration of 150-260 g/l at mass ratio of Fe₂O₃:Na₂SO₃=(0.18-0.23):1 at simultaneous deposition of iron in form of ferric sulfite (II) which is subjected to thermolysis in boiling mode continued for 0.5-1.5 h for forming hydrated ferrous oxide (II) which is separated from solution by filtration containing ions of non-ferrous metals; then, it is washed and subjected to heat treatment at 400-440°C for 0.5-1.5 h for forming ferric oxide (III). Thermolysis of ferrous oxide (II) may be performed under rarefaction; sulfur dioxide separated at this is neutralized with soda for obtaining sodium sulfite solution which is directed to iron reduction stage. Ferric chloride (III) solution may be obtained through treatment of part of iron cake in the amount of 3.5-5.5 mass-% of concentrated hydrochloric acid taken in stoichiometric amount relative to iron contained in cake. Proposed method makes it possible to increase extraction of non-ferrous metals iron cake to 96.5-98.5% at simultaneous obtaining ferric oxide (III) powder possessing pigment properties at reduced content of admixtures of non-ferrous metals.

EFFECT: facilitated procedure.

6 cl, 6 ex