According to a 70 t ladle prototype at steel works

the water model with model-prototype linear scale ratio 1：2.75 has been established. The obtained critical blowing gas rate was 450 L/min by water modeling test to measure the rate of ladle bottom blowing argon in critical slag entrapment condition. The horizontal flow velocity of liquid surface in ladle with different gas blowing rate was measured in test to analyze the relation between horizontal flow velocity and liquid entrapped slag in ladle and get the liquid surface flow rate in critical slag entrapment condition being 0.652 m/s and its Weber index in that condition being 6.967. Using critical Weber index to calculate liquid surface flow velocity in critical slag entrapment condition and method to define the argon blowing rate for critical liquid entrapped slag by measuring the argon blowing rate up to liquid surface flow rate in critical slag entrapment condition are discussed in this paper.