The raceway formed in front of a tuyere is one of decisive factors to operate a blast furnace stably and efficiently, because the gas distributions from the raceway and the descent of the burden are greatly affected by the characteristics of the raceway.
There are, however, many unknown facts about the formation of the raceway and incidental phenomena. This study has been carried out for the purpose of solving some of them using a cold model and an experimental blast furnace.
In this paper, some results obtained through cold model experiments are presented.
The summary of the results is as follows:
1) Particles in the raceway rotate around at high speed, colliding with rotating particles or the raceway wall and some of them are reduced in size.
2) A lot of fine particles formed in the raceway accumulates on the surface of the raceway in front of the tuyere.
3) Under a condition of reduced particle size in front of tuyere, the raceway is enlarged, especially upwards along the furnace wall.
4) The depth of the raceway can be expressed by the relationship between the raceway factor (P·V²·ρ_go/g·d_s·ρ_s·S²) and the penetration factor (D_R/D_T).