Mechanism of direct reduction and melting-separation for carbon-bearing pellets

To explore the mechanism of reduction and melting-separation in carbon-bearing pellets, cold-bound pellets were made of analytically pure Fe₂O₃, oxides, and different reductants, and their isothermal reduction experiment was carried out. The influences of reduction parameters, such as temperature, reduction time, carbon/oxygen mole ratio, and type of reductants, on the metallization degree and melting behavior were discussed on the basis of experimental data. The microstructure and phase transformation of the pellets were characterized by X-ray diffraction and scanning electron microscopy. It is found that the pellets cannot be molten well at too low or too high temperature. An increase in carbon/oxygen mole ratio can improve the reduction and melting rate of the pellets. The appropriate temperature, carbon/oxygen mole ratio, and reducing agent are 1400℃, 1.2, and pulverized coal, respectively. The reduction and melting-separation reactions of the pellets contain direct reduction reaction, indirect reduction reaction, carbon gasification re-action, carburization reaction and iron melting reaction, and finally realize the separation of iron and slag.