Gas Permeability Improvement Mechanism at the Lower Part of Blast Furnace by Converter Slag Injection from Tuyere and Quantification of its Effect

In order to improve gas permeability around the blast furnace bird’s nest region during high pulverized coal injection rate operation, flux injection technology from the tuyere is surveyed with the purpose of decreasing slag hold-up. In this study, converter slag is focused on as the flux material. The advantages of converter slag as an inductant are its low melting point and its smaller endothermic quantity because it is a high FeO pre-melt slag. Results obtained by experiments and actual blast furnace tests are as follows:(1) Converter slag melted quickly during flight within the raceway and showed excellent assimilation properties with bird’s nest slag.(2) Based on the results of slag dripping experiments, a scheme is established which estimates the improvement of gas permeability using the operational conditions for the blast furnace and the converter slag injection conditions.(3) A decrease in pressure drop at the lower part of the blast furnace was demonstrated by converter slag injection tests at Kobe No.3 blast furnace. The operational results showed fairly good agreement with those estimated by the scheme of the present study.