FORFARANDE FOR ELEKTROKEMISK UPPARBETNING AV ANVENDA SVAVELSYRAHALTIGA BETLOSNINGAR FOR BETNING AV JERN

摘要

Iron is extracted by cathodic deposition from final pickling solutions which per litre contain at most 100 g of sulphuric acid and at least 25 g of iron ions. The sulphate ions are removed electrodialytically. Salts are added to the final pickling solution to set an ammonium, magnesium or alkali metal sulphate concentration of 0.5-1.0 mol/litre. The final pickling solution is fed into the cathode compartment of an electrolytical appliance composed of cells - which contain anode and cathode compartments separated by diaphragms - and is allowed to flow through said cathode compartments, while the iron content of the solution is depleted to a value of 7-15 g Fe<++>/litre. Then the solution is passed into the anode compartment of the appliance and is moved therethrough in a direction identical to that of the flow maintained in the cathode compartment. The current density based on the area of the diaphragm is held at a value of 15-22 A/dm<2>, and the operating temperature of the electrolysis is held at a value of 70-90 DEG C.