Abstract: About 80% of particles in sludge were smaller than 149 μm in diameter at 1^# BF in Baosteel of China and the particle distribution was composed of two normal distribution curves. While approximately 65% of particles in dust were about 74-297 μm in diameter and the particle distribution was composed of three normal distribution curves. Different microstructures of unused pulverized coal and coke in dust were found through petrographic microscopic analysis. According to the utilized carbon degree of unused pulverized coal and coke, an equation of the ratio of unused pulverized coal to coke in Changcun industrial experiment dust was proposed by means of the microscopic analysis results.