C CHEMISTRY; METALLURGY
C22 METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
C22B PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
7/00 Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof;; Methods of a general interest or applied to the winning of more than two metals
C22B7/02 Working-up flue dust