Super-high bed sintering for iron ores: variation and optimization of bed resistance

As the bed depth increases, sintering yield increases, but the productivity decreases. To reveal the reasons for the decrease in productivity and explore targeted solutions, the bed resistance of mixtures, wet zone, and combustion zone was analyzed in the laboratory. The results showed that the decreased porosity of mixture resulted in the increased bed resistance by 160.56% when the bed depth increased from 600 to 1000 mm. After improving porosity of 1% by adding loosening bars with optimized size and distribution, the bed resistance decreased, and the productivity increased by 5%. The increase in bed depth increased the thickness of the wet zone from 120 to 680 mm and the resistance from 1.56 to 8.83 kPa. By using a three-stage intensive mixer and pre-adding water for granulation, the moisture of mixture was reduced by 0.6%, and the sintering productivity increased by 4%. Besides, the high bed resistance is mainly caused by the increase in the thickness of the combustion zone from 31.9 to 132.7 mm, and the bed resistance increased from 0.70 to 5.62 kPa. The bed resistance of the combustion zone at 900 mm was increased by 90.51% compared to 700 mm. After optimization of the distribution of coke breeze, the thickness of combustion zone at the lower layer decreased from 132.7 to 106.84 mm and permeability improved significantly.