Mathematic model for catch carbon practice of steelmaking medium and high carbon steel in a 70 t arc furnace has been established. According to the requirement of carbon content in liquid steel at tapping

based on the chemical compositions of charged scrap and hot metal

the blowing parameters of ultrasonic coherent jet oxygen lance are controlled suitably to use consumable oxygen-carbon lance at door and the available slag basicity is used to carry out aim catch carbon practice. The steelmaking practice of 0. 55% C steel showed that with charged 30% hot metal

the proportion of heats with arc furnace end point [C] 0. 40% ~ 0. 65% was N85% to obviously decrease steel melting cost.