Effect of Al2O3 content on the viscosity and structure of CaO-SiO2-Cr2O3-Al2O3 slags

The effect of Al2O3 content on the viscosity and structure of CaO-SiO2-Cr2O3-Al2O3 slags was investigated to facilitate recycling of Cr in steelmaking slags. The slags exhibit good Newtonian behavior at high temperature. The viscosity of acidic slag first increases from 0.825 to 1.141 Pa center dot s as the Al2O3 content increases from 0 to 10wt% and then decreases to 1.071 Pa center dot s as the Al2O3 content increases further to 15wt%. The viscosity of basic slag first increases from 0.084 to 0.158 Pa center dot s as the Al2O3 content increases from 0 to 15wt% and then decreases to 0.135 Pa center dot s as the Al2O3 content increases further to 20wt%. Furthermore, Cr2O3-containing slag requires less Al2O3 to reach the maximum viscosity than Cr2O3-free slag; the Al2O3 contents at which the behavior changes are 10wt% and 15wt% for acidic and basic slags, respectively. The activation energy of the slags is consistent with the viscosity results. Raman spectra demonstrate that [AlO4] tetrahedra appear initially and were replaced by [AlO6] octahedra with further addition of Al2O3. The dissolved organic phosphorus content of the slag first increases and then decreases with increasing Al2O3 content, which is consistent with the viscosity and Raman results.