Study on Content of Nitrogen Pick-up in Thin Slab Produced by CSP in JISCO
Author of the article:XIE Jian;QIAO Degao
Author's Workplace：Jiuquan Iron and Steel(Group)Co.,Ltd.,Jiayuguan 735100,China
Key Words：CSP refining process protection cast process molten steel nitrogen content
Abstract：The causes of nitrogen increasing in the thin slab of BOF+LF+CC+HR line used in CSP process in JISCO were investigated. The results show that the average nitrogen content of the raw slab is 56 ×10^-4%, which is out of the control range. The process from the end of the BOF to the refining station is a major step of nitrogen increasing of molten steel,which is caused by the high nitrogen content of scrap steel and alloy used. During the continuous casting process, there is no contact between the molten steel and the air, and the nitrogen increase in the pouring process is mainly caused by the air inhalation caused by the loose seal at the junction of the lower nozzle and the long nozzle. By controlling the amount of scrap steel, using alloys with low nitrogen content, controlling the refining process, and improving the sealing at the junction of the lower nozzle and the long nozzle, the average nitrogen content of the slab can be reduced to 46×10^-4%.
