MgO addition plays an essential role in the blast furnace smelting process, including softening-melting characteristics and metallurgical properties of slag. In the present study, the effect of MgO distribution on the softening-melting characteristics and slag system of vanadium-titanium magnetite burden were explored by simulating BF conditions. The results show that the MgO flux addition significantly affects the crystallization temperature of slag-phase, the precipitated phase components, and slag viscosity. This indicates that appropriate MgO addition can improve the metallurgical properties of blast furnace slag effectively, thereby improving the softening-melting-dripping performance of the mixed burden. The V-Ti pellets with a MgO content higher than 2.40 wt% exhibit optimum metallurgical properties. With a constant MgO content in mixed burden, the softening-melting properties of composite burden could be improved effectively as the MgO partitioning scheme includes 1.90 wt% MgO in sinter and 3.02 wt% MgO in pellet.

To solve situation of high-sulfur copper slag utilization, an innovative technology was proposed for oxidation roasting with composite agglomerates. The oxidation-roasting process was studied by factage7.3 software. The thermodynamics were calculated about sulfur removal, sulfur adsorption and decomposition. The adsorption of sulfur oxides and microstructure evolution were analyzed via an oxidation roasting experiment and SEM-EDS. The results show that the matte and As_xS_y in the matrix could be effectively removed via oxidation roasting in an oxygen atmosphere; the sulfoxide was adsorbed to produce CaSO₄. The Fe₂SiO₄ decomposition could be realized at suitable roasting temperature and in an oxygen atmosphere. This is helpful for the magnetic separation of iron and silicon. The thermodynamic and experimental results were preliminarily confirmed to be available in the innovative process.