Effect of Temperature on Desulphurization of Liquid Iron Using Basic Oxygen Furnace Slag

Abstract

High amount of basic oxygen furnace (BOF) slag in steelmaking process is a big challenge, therefore, recycling of the slag have been extensively concerned by not only steelmakers but also researchers. One of the promising methods is to use the slag as a flux in the pretreatment process because the basicity of slag is high and it contains high amount of MgO and CaO. This study examines recycling ability of the BOF slag as a part of the flux adding to the pretreatment process. In the experiment procedure, the flux was combination of the slag (59 mass%), CaO (32 mass%) and SiO2 (9 mass%). The flux and the iron sample were put into the crucible, and then set up in the resistance furnace. The experiments were carried out at different temperatures of 1450, 1500 and 1550 °C with holding time of 15 minutes. The results shown that the S content in the iron significantly decreased in all cases of temperatures. S content in the iron in the pretreatment process reduced from the initial value to 0.007 mass% at the temperature of 1450 °C. However, at temperature of 1550 °C, the S content in the iron was 0.012 mass%. Besides, Si content in the iron reduced with increasing temperature; Si content in the iron significantly decreased from initial value of 2.67 mass% to 0.05 and 0.06 mass% once the temperatures were 1500 and 1550 °C, respectively. Additionally, it was indicated that Fe content in the slag after reaction dropped from the initial value of 6.20 mass% to 0.62 mass% at the temperature of 1550 °C.