Effect of Al2O3 on Sintering Reaction of Calcium Ferrite

Calcium ferrite containing aluminum (CFA) has been widely used in blast furnace production because it is an important compound that affects the quality of sinter. The influence of Al2O3 on CFA preparation process was studied by the raw material of CaO-Fe2O3-Al2O3. Diffraction of x-rays (XRD), scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS) analysis were used to analyze the phase, micro morphology and the reducibility of the products. The results showed that CaO tended to combine more with Fe2O3 to form calcium ferrite with the increase of Fe2O3, whereas CaO tended to combine more with Al2O3 to form calcium aluminate with the content of Al2O3 above 45%. The micro morphology of sintered samples had a stable sintering skeleton structure due to the existence of calcium ferrite. Calcium ferrite was distributed between different particles in flakes, whereas calcium aluminate was attached to the Al2O3 particle surface. The large amount of calcium aluminate inhibited the emergence of calcium ferrite, and it had an adverse impact on the reducibility of sinter and the preparation of CFA.