A new method of removing inclusions in molten steel by injecting gas from the shroud

Abstract

A technology of removing inclusions in molten steel by injecting gas from the shroud has been analyzed and studied by method of mathematical model and water model. Study of position of injecting gas, flow rate of gas and gas nozzle size on the generated bubble size and distribution at the shroud has been investigated; the relationship between blowing parameters and inclusion removal efficiency has been analyzed in order to optimize the blowing parameters. The results show that the stronger turbulent vortex at the enlarged part in the shroud favors fine bubbles generation and uniform distribution; fine bubbles in diameter of 0.3 to 0.5 mm can be generated in the shroud and tundish by controlling flow rate of gas. The superfluous gas makes bubble size largen sharply. The nozzle size has some effect on bubbles size and distribution; the larger nozzle size goes against fine bubbles generation. So the optimum gas injected position is located at the enlarged part in the shroud. The resonable flow rate of gas and nozzle size would greatly improve inclusion removal efficiency. © 2006 ISIJ.