Desulphurisation behaviour of blast furnace slag with high Al₂O₃ 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.

KEYWORDS:

• Blast furnace slag with high Al₂O₃ content
• Sulfide capacity
• Slag structure
• Raman spectroscopy

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by National Natural Science Foundation of China [grant number NSFC52074072, NSFC51774071, NSFC52074074, NSFC52074086, NSFC51974073].