Cationic Effect of Ferrous Ions on Sulfide Capacity of CaO-FetO-Al2O3-SiO2 Slag System

Abstract

The cationic effect of ferrous ions on the sulfide capacity of CaO-FetO-Al2O3-SiO2 slags was studied from the viewpoint of the ionic structure in the slag using micro-Raman spectroscopy. In the cation-excess region (M2+/2(Fe3+ + Al3+) > 1.0), the sulfide capacity was directly proportional to the basicity of the slags, owing to the S2− stabilizing effect of excess cations. However, in the cation-deficient region (M2+/2(Fe3+ + Al3+) 0.5), the sulfide capacity decreased with the increase of the Fe2+ content owing to the Qn unit affinity of the Fe2+ ion. The sulfide capacity was determined by the competition between the Qn unit affinity and stability of the S2− ion, depending on the type of cation. Therefore, the partial covalent bonding between the M2+ cations (M: Ca, Fe) and aluminosilicate affected the ionic interactions with the S2− ions.