TREATMENT OF RESIDUE

摘要

PROBLEM TO BE SOLVED: To efficiently remove impurities in a calcium fluoride residue by using a calcium fluoride residue treatment process that comprises subjecting steelmaking dust to dechlorination treatment with lime water to obtain dechlorination water containing calcium and treated dust, adding a carbon material and water to the treated dust and pelletizing the mixture into pellects, roasting the pellets in a reduction/volatilization furnace to recover a crude zinc oxide powder, treating the crude zinc oxide powder in an alkali solution at a specified pH value. SOLUTION: Prescribed amount of chlorine in steelmaking dust in a raw material bin is removed by being sprayed dechlorinated lime water. Dechlorination water containing calcium is fed into defluorination treatment vessel. Dechlorinated steelmaking dust is baked in reduction/volatilization furnace after pelletizd. Crude zinc oxide powder volatized by baking is recovered by bag filter. Zinc oxide powder containing lead halide and zinc halide is agitated in a dehalogenation vessel with an alkali aqueos solution (>pH10). After solid liquid separation. The mixture is separated into calucium fluoride residue and waste water in the defluorination residue vessel with alkali aqueous solution of above pH11.