Research Of The Smelting With Low Silicon Hot Metal In Blast Furnace At Longmen Steel CO.Ltd.

If the silicon content of hot metal in blast furnace (BF) could be reduced, we will reach the aim of higher yield and higher quality with lower consumption, and it will satisfy the requirement of less slag in the process of converter steel-making. So the technique of BF low-silicon smelting has been attached more and more importance and become an important theme in the BF smelting. The silicon content higher than 0.65% of the hot metal in BF smelting has become a stumbling block in the production of Shaanxi Longmen Steel CO. Ltd. So included in the study were the employment of the method of theoretical analysis and experimental research with practical production to seek for the measure of reducing the silicon content.The theoretical analysis of main factors in the formation and transformation of silicon in BF smelting were studied in this paper. Then, some experiments on the basis of the practice of Longmen Steel are designed for ascertaining those factors: the determination of the sinter performance, the determination of the slag viscosity and the influential factors, mutual reaction experiment, the experiment on the effect of pulverized coal injection on the silicon content.The results show that the following measures should be taken to achieve low-silicon smelting in Longmen Steel blast furnace:Firstly, the management of raw materials should be strengthened, the quality should be stabilized, and the ash content of coke should be decreased. The sinter quality should be improved to ensure better metallurgical properties: suitable basicity, higher content of MgO,FeO, and lower SiO₂,Al₂O₃.Secondly, the binary basicity of BF slag should be adequately advanced with a proper content of MgO and Al₂O₃.Thirdly, the content of FeO and MnO of BF slag should be appropriately increased to provide a favorable condition for the reoxidization of silicon at the bottom of BF. If permitted, adding a little manganese ore is suggested.Last but not least, oxygen enrichment and high blast temperature should be adopted to increase the pulverized coal injection. And the coal with low ash content and low SiO₂ should be selected.The measures mentioned above have been carried out in NO.1 BF of Longmen Steel. There has been a satisfactory result of 0.58% silicon content of hot metal and a lowering tendency.