Desulphurisation behaviour of blast furnace slag with high Al 2 O 3 content at 1823 K

Abstract

The desulphurisation of blast furnace slag is an important metallurgical function of blast furnace smelting. To elucidate the desulphurisation behaviour of blast furnace slag with high Al₂O₃ content, the slag–metal equilibrium method was employed to determine the sulfide capacity (C _S) of CaO–SiO_2–Al₂O_3–MgO melts for blast furnace smelting at 1823 K. When basicity (R_w =w(Basic oxide)/w(Acid oxide)) and w(MgO)/w(Al₂O₃) were increased, the intensities of the characteristic peaks of [SiO₄] and [AlO₄] in Raman spectrum decreased, indicating that the degree of polymerisation had reduced. The cluster structures of [SiO₄] and [AlO₄] depolymerised and lgC _S (i.e. the desulphurisation ability) increased, owing to which the number of free O²⁻ ions increased. However, when w(Al₂O₃) was increased, the intensities of the characteristic peaks of [SiO₄] and [AlO₄] in Raman spectrum increased gradually, indicating that the degree of polymerisation had increased, and the simple structures of [SiO₄] and [AlO₄] were polymerised. As a result, both the number of free O²⁻ ions and lgC _S decreased.