JPS5732314A - Lance for oxidation treatment of molten slag - Google Patents

Abstract

PURPOSE:To prevent the erosion of the leading end part and side wall parts of a lance for blowing an oxidative gas into molten slag by forming said lance into double construction and flowing refrigerant in the outside pipe. CONSTITUTION:Oxygen is supplied into the inside pipe 5 of a lance 3 immersed into the molten slag 2 in a slag pan 1, and refrigerant of >=140kcal/cm<3>hr cooling capacity into an outside pipe 4, whereby oxidation treatment is accomplished. In the case in which oxygen is blown with a steel pipe or stainless steel pipe, erosion progresses drastically when the surface temp. of the outside pipe of the lance exceeds about 1,200 deg.C. Hence, keeping the surface temp. of the outside pipe at about below 1,200 deg.C necessitates keeping the heat conductivity of the refrigerant at >=2,000kcal/m<3>hr deg.C. The flow rate W (kg/hr) of the gaseous refrigerant necessary for this is determined by the equation [Q: refrigerant cooling capacity (kcal/ cm<3>hr), cp: the average specific heat of refrigerant (kcal/kg deg.C), DELTAT: the temp. rise of refrigerant (1,200 deg.C), D: the inside diameter of the outside pipe (cm), H: the immersion depth of the lance (cm)].