The Optimum Study On Top And Bottom Combined Blown Converter Process In CISC

The top and bottom combined blown smelting technology combines the advantages of top blown's fast reaction and that of bottom blown's steady smelting. And it overcomes the disadvantages of top blown's spray easily and bottom blown's melting slag uneasily. Through the effect of top and bottom gas stirring, the reaction of metal-slag-gas is speed up, spray is decreased, metal yield is increased, and temperature of molten steel and equality between components are improved. To improve productivity of converter and quality of molten steel, the technology of combined blown converter was put into production at Nov. 2003 in CISC. To ensure the proper design of parameters in process and opitimization, the parameters in process of combined blown converter in CISC were studied systematically through physical simulation experiment in laboratory and trial in plant. The theoretical and practical foundation were provided in this paper for combined blown converter device and type of steel in CISC. The bottom critical parameters'calculation of bottom blown nozzle showed that, the minute pressure of bottom blown nozzle was 0.32Mpa under the rated condition. Through water model simulation experiment in laboratory, the process parameters(top lance levels,top blown flux and bottom blown flux) of top blown and combined blown were estimated. And the further optimizative patterns were provided. The industrial experiment showed that end-point [O],[C]×[O],the content (FeO) of final slag and (TFe) of final slag were decreased under the same of end-point control after the technology of combined blown was put into production in CISC. End-point [Mn] and desulfurization were increased. End-point [P] of combined blown was the same with that of top blown. With the decrease of bottom blown flux, the content of end-point [P] was decreased and the content of end-point [Mn] was increased. The former metal-slag splashing at 3~4 min disappeared under optimum combined blown patterns. Through controlling the bath stirring, the content end-point [Mn] of new combined blown patterns was higher than that of former patterns, dephophorization changed hardly, and efficiency of desulfurization was increased due to strengthening slag melting.