C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
C21C7/04—Removing impurities by adding a treating agent
C21C7/072—Treatment with gases
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
C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
C22B9/055—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ while the metal is circulating, e.g. combined with filtration
