化学センサーを用いたソーダ基フラックスによる溶銑の脱りん反応の研究

Abstract

New chemical sensors to measure the oxygen pressure and the Na2O activity have been developed by using Na2O·11Al2O3 and ZrO2-MgO electrolytes. The chemical activity of sodium oxide in slag was measured at 1573 K during dephosphorization of carbon-saturated iron by soda-based fluxes. Simultaneously, the oxygen pressure at slag-metal interface and the sodium vapor pressure in gas phase were also measured.In the case of Na2O·SiO2-Fe2O3 flux, the oxygen pressure rose rapidly to about 1×10−7 Pa and slowly fell down to about 3×10−10 Pa. The activity of sodium oxide was constant at about 1×10−5 during dephosphorization and then gradually increased.In the case of Na2CO3 flux, the oxygen pressure fell down to much lower oxygen pressure of 1×10−13 Pa than that in carbon-saturated iron during dephosphorization. The activity of sodium oxide was nearly constant at 3×10−4, when the carbon-saturated iron with 0.35%P was used. However, it fell down to 2×10−6, when the carbon-saturated iron with a large P content of 2.52% was used. The sodium vapor pressure was constant at 6×104 Pa during dephosphorization and graclually lowered during rephosphorization.In the case of Na2CO3 added Fe2O3 flux, both the activity of sodium oxide and the sodium vapor pressure were lower than those in the case of pure Na2CO3 flux.