PURPOSE: To economically recover nickel in the form of an aqueous solution, by successively blowing air and then chlorine into a slurry containing nickel sulfide and proper concentrations of sulfuric acid and chlorine ions so that proper redox potential is obtained.
CONSTITUTION: At the time of carrying out electrolytic refining of metal nickel by using nickel matte as an anode, slimes formed at the anode or the residue obtained by removing a part of simple-substance sulfur content from the above is formed into a slurry of about 200W300g/l. Further, ≥70g/l, preferably about 80W250g/l, of sulfuric acid and ≥10g/l, preferably about 35W50g/l, of chlorine ion from NaCl, etc., are incorporated to the above aqueous solution. The above aqueous solution is maintained in a heated state of about 80W100°C, into which air or oxygen-enriched air is blown until redox potential comes to ≥550mV. Then, chlorine is blown into the above slurry in the same heated state as mentioned above so that redox potential comes to 650W750mV. In this way, nickel can be economically recovered in the form of an aqueous solution from nickel sulfide in the slimes or the residue.
TSUCHIDA NAOYUKI
SUGIURA TAKU
FUKUI IWAO
INAMI TOMOYUKI
