Silicon volatilisation in the form of SiO during slagging by limestone in BOF

In this paper, the silicon volatilisation phenomenon during slagging by limestone in basic oxygen furnace (BOF) and its influencing factors were studied by industrial experiment and thermodynamic calculation. In our estimation, the volatilisation ratio of silicon in this industrial experiment is about 13.01–47.82%. Thermodynamic analysis showed that the silicon volatilisation phenomenon happens after charging limestone directly into BOF because CO2 from limestone decomposition could massively oxidise the silicon in the hot metal into gaseous SiO in the hot spot zone. The mass of produced SiO increases, then decreases with the increase of the limestone addition and the carbon content of hot metal, and SiO mass is proportional to silicon content of hot metal. Compared with lime slagging, the strong stirring effect of CO2 from limestone decomposition, massive foaming slag formation, great increment of furnace gas are all favourable to silicon volatilisation.