Abstract:Based on the mass balances of blast furnace, typical slag basicity was calculated and analyzed in different zones of the blast furnace. Analysis results show that, under large pulverized coal injection, the conventional burden induces the fluctuation of basicity of slag along the blast furnace height, the decrease of threephase zone and the permeability of lower part of blast furnace. To solve the problem, injection of limes into the blast furnace instead of charging from the top could be a good solution. Once the charging of limes from the top is replaced by injection via the tuyeres, the smooth operation and increasing productivity of the blast furnace can be obtained, besides the decreasing bosh slag volume, the proper basicity of slag, the higher location of cohesive zone, the extending of threephase zone, the increasing of permeability and pulverized coal combustibility.