| 摘要 |
<p>PROBLEM TO BE SOLVED: To enhance a secondary combustion rate and to improve scrap melting efficiency by providing an oxygen blowing lance with cooling gas ejection holes above the ejection holes of the lance and blowing gases, such as N2 and CO2 , from these holes at the time of melting the ferrous scrap by using a top blown converter type melting furnace. SOLUTION: The top blowing lance 1 is provided with the cooling gas ejection holes 3 separately from the oxygen-contg. gas ejection holes. The cooling gas ejection holes 3 are disposed in at least one piece, more preferably 4 to 20 pieces on the peripheral surface of the range where the distance H2 from the bottom end face of the lance 1 to the center of the ejection holes attains 0.2H1 <=0.8H1 with respect to the distance H1 from the bottom end face of the top blowing lance 1 under operation to the throat of the converter. As a result, the cooling gases consisting of one kind or >=2 kinds of N2 , Ar, Co and CO2 are blown at a rate corresponding to 5 to 30% of the supplying rate (Nm<3> /h) of the oxygen-contg. gas. One or >=2 kinds of Mg, CO3 , CaCO3 or coal powder contg. >=20wt.% volatile content or >=5wt.% moisture are blown together with the cooling gases.</p> |
