For the purpose of decreasing Si content in hot metal by means of flux (CaO, MgO) injection through the blast furnace tuyeres, fundamental experiments and operational tests at Keihin No. 2 blast furnace were carried out. Results obtained are as follows.
(1) The generation rate of SiO gas (K'SiO) based on fundamental experiments were formularized as follows.
K'SiO= 4.07 × 107 × exp (-120 × 103/RT) × αSiO2
(2) For decreasing Si content in hot metal, MgO flux injection from the tuyeres was proved to be more effective than CaO flux injection. As to the charging method of flux, tuyere injection is most effective followed by top charging with coke and top charging with ore.
(3) The decrease in Si content in hot metal by MgO injection was estimated to be mainly due to the decreased generation rate of SiO gas with decreased activity of SiO2 in raceway slag, which is formed by the reaction of coke ash and injected MgO flux.
(4) According to magnesite injection of additional 10 kg/t from the tuyeres, Si decreases due to MgO increase in hearth slag and raceway slag were estimated to be 0.009% and 0.045% respectively.
