| 摘要 |
<p>PROBLEM TO BE SOLVED: To easily micronize the bubbles of a reflux gas in a riser tube, a thereby to increase the decarburizing rate and the deoxidizing rate and moreover, to reduce the attain concns. of nitrogen and oxygen in molten steel at the time of deoxidizing treatment by providing the inner wall of a riser tube with a gas blowing tuyere for a reflux composed of double tubes and blowing hydrocarbon gas from the inner tube of this double tubes and an adiabatic gas from the outer tube. SOLUTION: The gas blowing tuyere 6 for a reflux provided on the inner wall 5 of an immersed tube for a riser tube is provided with double tubes, and hydrocarbon or a gaseous mixture of hydrocarbon and an adiabatic gas are blown in from the inner tube 8 of the double tubes and, moreover, an adiabatic gas from the outer tube 9. Furthermore, as hydrocarbon, CH4, C2H6, C3H8, C4H10 or the like can be used singly or mixdly, and, as the adiabatic gas, Ar, N2, CO, CO2 or the like can be used singly or mixedly. Moreover, in the case extra-low carbon steel is melted, since there is anxiety that carbon produced by the decomposition of hydrocarbon in a low carbon region increases the [C] concn. in the molten steel, in the process, hydrocarbon is exchanged for gaseous Ar.</p> |
