Abstract: To solve the problems of low oxygen supply intensity and long smelting cycle in the 210 t large converter, 10 oxygen lance nozzles were designed and water model test were performed. The results showed that the impact cavity formed by the 5-hole oxygen lance jet had better independence, and under the same oxygen flow rate, its impact depth was greater than that of the 6-hole oxygen lance. Among the ten oxygen lance nozzles, the nozzle 3 and nozzle 4 have the best impact depth. The impact area (radius) significantly increases with the increase of inclination angle, and the nozzle 3, 4, 9 and 10 have better impact areas compared with other nozzles. Therefore, the nozzle 3 was used as the new 5-hole oxygen lance for industrial testing, and the nozzle 9 was used as the new 6-hole oxygen lance for industrial testing. The experimental results were compared with the original 6-hole oxygen lance. The industrial test results show that in terms of phosphorus removal ability, the new 6-hole lance is the best, while the original 6-hole lance is the worst. Compared to the original 6-hole lance, the new 5-hole lance does not have the ability to shorten the oxygen supply time, while the average oxygen supply time of the new 6-hole lance is shortened by 22 s. In terms of lifespan, the new 5-hole lance is not as good as the original 6-hole lance, while the lifespan of the new 6-hole lance is equivalent to that of the original 6-hole lance.Compared to the original 6-hole lance, the new 6hole lance has a significant effect on reducing the total iron content in slag and steel material consumption.

Key words: 210 t converter, water model test, industrial testing, oxygen lance nozzle, oxygen supply intensity, dephosphorization rate