Promoting the Utilization of High-Alumina Iron Ores During Sintering by Pre-preparing a Low-Melting-Point Flux

High-alumina iron ore sintering is characterized by poor sinter indices and high carbon emission due to the limited formation amount of liquid phase. In this study, the conventional Ca-bearing flux (i.e., burnt lime) was substituted by a new Ca-bearing flux with low melting point (i.e., prefabricated calcium ferrite) for the improvement of the formation ability of liquid phase during sintering. The substitution of prefabricated calcium ferrite for burnt lime contributed to the reduction of the formation temperature of liquid phase and the improvement of liquid-phase fluidity. At the optimum substitution ratio of 20%, the strength of sinter compacts was improved by 38.38% in the mini-sintering tests due to the more formation of liquid phase, especially SFCA (i.e., Silico-ferrite of calcium and alumina). In addition, the proportion of high-alumina iron ore can be appropriately increased from 10.20% to 25.20% at the substitution ratio of 20% under the premise of the similar strength of sinter compacts. High-alumina iron ore can be effectively utilized during sintering by pre-preparing the low melting-point flux, which will be further proved by the relevant sinter pot tests in our follow-up study. Graphical Abstract