Sintering Behavior of Return Fines and their Effective Utilization Method

Return fines is unavoidably formed in sintering process, it recycles back into sintering and makes up 30 to 40% of the iron bearing materials. When deteriorated raw materials are applied, sintering process is balanced with higher ratio of return fines, which greatly affected sintering efficiency and fuel consumption. In order to reduce the return fines by effectively using, basic researches were conducted using modeled quasi-particles, consisting of return fines and sintering blend. Proper using ratio of two kinds of return fines were confirmed by measuring both granulating and bonding ability, then reasonable quasi-particle structure of return fines was proposed from the perspective of segregated basicity optimization. The results obtained were summarized as follows: Return fines generated from unassimilated iron ores, insufficient uniformity of melt, highly developed porous structure and lower internal force of eutectic structures. Assimilation ability and liquid fluidity of return fines were higher than sintering blend, resulting in promotion of low-temperature melt generation. The optimal addition of return fines from BE sieving was suggested not to surpass 30 mass% by melt generation balance, and the ratio for return fines from sintering sieving should be controlled at about 20 mass% with contradictory effect on bonding and granulation. Quasi-particles of returns fines were characterized by high compactness and uniformity at lower segregated basicity, weaken melt formation surrounding returns fines to strengthen that of iron ores was the effectively using way.