PURPOSE: To enable smooth spraying of metal chloride solution without causing clogging of spray nozzle, by neutralizing a concentrated solution of chloride of metal such as iron, etc. containing a small amount of Al3+ and Cr3+ with a metal such as iron, etc., filtering the solution, decomposing it under heating by a roaster.
CONSTITUTION: In a method wherein a solution of chloride of one or more metals (e.g., pickling solution of aluminum killed steel, etc.) of Fe, Mn, Zn, Mg, Ni, Co, etc. containing ≤1wt% Al3+ and/or Cr3+ is concentrated under heating by a hot gas discharged from a roaster, the solution is filtered by a strainer, decomposed under heating by the roaster, and HCl and a metal oxide are recovered, before the concentrated solution is filtered, a process, wherein one or more metals of F, Mn, Zn, Gg, Ni, Co, etc. are added to it and free acids are neutralized, is set. The amounts of Al3+ and Cr3+ after the filtration are reduced to half or less by grain growth of Al colloid, etc., and clogging of spray nozzle is lightened.
KOUNO KATSUMI
IDA TAKESHI
