Experimental Study on Optimization of Coal Blending for Blast Furnace

Coal blending experiments were carried out with bituminous coal and anthracite as raw materials to explore the influence of content of bituminous coal on the combustion performance of blended coal, and the influence mechanism of particle size composition on the combustion rate of pulverized coal was analyzed. The results show that when the mass fraction of bituminous coal is in the range of 40%-70%, the hardgrove grindability index of blended coal fluctuates between 77 and 89. When the mass fraction of bituminous coal is up to 65%, the return flame length of blended coal is more than 150 mm, and the blended coal has a slight explosiveness. In the same particle size range, the combustion rate of pulverized coal varies greatly, and the combustion rate of anthracite is more obviously affected by the particle size of pulverized coal. When the proportion of blended coal with particle size less than 74 μm is 80%, the small particle size pulverized coal has the best combustion promotion effect on the large particle size pulverized coal. When the mass fraction of bituminous coal is more than 60%, the combustion rate of blended coal decreases. Considering the characteristics of blended coal and the relative content of CO and CO₂ in flue gas, it is suggested that the mass fraction of bituminous coal should be controlled at about 55%.