MOLTEN IRON DEPHOSPHORIZATION METHOD

• Main Authors: FUJII Yusuke, NEGISHI Hidemitsu, ODA Nobuhiko, KAWABATA Ryo, MURAKAMI Yumi, KIKUCHI Naoki
• Format: Patent
• Language: English; French; German
• Published: 31.08.2022
• Subjects: CHEMISTRY; METALLURGY; METALLURGY OF IRON; PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OFWROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS

Proposed is an efficient dephosphorization method using a top and bottom blown converter. This molten iron dephosphorization method uses a top and bottom blown converter charged with molten iron and slag, and to blow an oxygen-containing gas from a top-blowing lance, supplies the oxygen-containing gas as a main gas from an inlet of a blowing main hole, and supplies a control gas from an opening toward an axial center of the blowing main hole through a control gas supply passage. This method has: a slag top-surface position measurement step of, with the position of a top surface of the molten iron having been measured in advance, continuously or intermittently measuring an arbitrary position in a top surface of the slag; a slag top-surface difference calculation step of calculating a slag thickness that is a difference between the measured top-surface positions of the molten iron and the slag; and a jetting condition adjustment step of, using the obtained slag thickness, adjusting a jetting condition of the oxygen-containing gas jetted from the top-blowing lance into an appropriate range. The top-blown jetting condition is adjusted by comparing the slag thickness and the depth of a surface depression.