REFINING METHOD WITH REDUCED PRESSURE GAS BLOWING

PURPOSE:To improve the contact probability of unrefined molten steel with gas and to shorten the refining time by arranging gas blowing holes facing the bottom part of a ladle and mutually executing the gas blowing. CONSTITUTION:The two gas blowing holes 4-1, 4-2 are arranged so as to face the bottom part of the ladle 1. An immersed tube 3 is arranged into the molten steel 2 in the ladle 1. Pressure in the immersed tube 3 is reduced, and by increasing the gas blowing quantity from the gas blowing hole 4-1, the refining is started. By gas blowing, temporarily, the molten steel stream is stabilized and stagnating parts alpha, beta of the molten steel 2 which does not run into gas bubbles, are formed. After passing the prescribed time, the gas quantity from the gas blowing hole 4-1 is reduced, and the gas blowing quantity from the faced gas blowing hole 4-2 is increased. Then the whole molten steel stream is reversed and the stagnating parts alpha, beta of the molten steel 2 at the time of using the gas blowing hole 4-1 are cancelled. Further, the stream as large block of the molten steel 2 is eliminated, and by developing the fine disturbance, the stirring of the molten steel 2 can be promoted.