An efficient continuous desiliconization process equipped with a mechanical stirrer in a hot metal runner was newly developed. The facility was installed during the revamping of No.3 blast furnace at Kobe Works, and the commercial operation started up successfully in January 2008. Before the installation of the commercial facility, the reaction behaviour was investigated under various experimental conditions for the application of a mechanical stirring method to continuous desiliconization treatment in the hot metal runner. Hot metal experiments at laboratory scale showed that the stirring intensity was an important factor for the process performance, and the mechanical stirring method was available for the improvement of reaction efficiency. As a result of plant tests, it was confirmed that a higher oxygen efficiency of desiliconization was achieved by the combination of runner arrangement and mechanical stirrer compared with the conventional injection of the desiliconizing agent. According to the reaction analysis of continuous desiliconization in the hot metal runner using the semi‐batch reaction model, it was estimated that the average slag‐metal residence time in the reaction region is improved due to an increased entrainment of foamed slag into the stirred metal bath in the mechanical stirring method, and therefore, it leads to a high desiliconization efficiency. Based on the experimental results, the equipment specifications and the runner design for this process were determined.
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 holdup. 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.
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