Effect of roasting temperature on the coal-based direct reduction of high-iron vanadium tailings

The effect of roasting temperature on the coal-based direct reduction of vanadium tailings was investigated by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). A metallic iron separation test of the roasting products was done by using a grinding-magnetic separation method. It is shown that the roasting temperature of 1 200℃ is needed for the generation, merger and growing up of metallic iron and for monomer dissociation between metallic iron particles and slag phase in the roasting products. Fe₂O₃ in vanadium tailings is completely reduced into metal iron, and Fe₂TiO₅ is basically transformed into metallic iron and TiO₂ at 1 200℃. The metal iron powder with a total iron mass fraction of 90.90% and a TiO₂ mass fraction of 0.56% is obtained from roasting products of vanadium tailings with a total iron mass fraction of 36.54% and a TiO₂ mass fraction of 9.28% at 1200℃ using the grinding-magnetic separation method.