Abstract: Influence of different arrangement of 4–12 bottom tuyeres of a 200 t top and bottom combination blown converter on its bath mixing was investigated in an 1:12 model with physical modeling experiment. Under the condition of combined blowing and the gas flowrates used in this work, the variation range of bath mixing time with different arrangements of 4 bottom tuyeres is large, being 20–49 s, the bath mixing time with different arrangements of 6 bottom tuyeres is 18–42 s, while that with different arrangements of 8–12 bottom tuyeres is 14–38 s. The ratios of bottom tuyere cases with mixing time smaller than 27 s to the corresponding total cases studied were 14 %, 13 %, 33 %, 39 % and 67 %, respectively. This means that 8–12 bottom tuyeres have more bottom tuyere arrangement cases with mixing time smaller than 27 s and these cases can be chosen for combined blowing during a converter campaign. The average values of bath mixing time of different cases at a certain number of bottom tuyeres decrease apparently when the bottom tuyeres increase from 4 to 8. As the bottom tuyeres increase from 8 to 12, the average values decrease a little for the bottom gas flowrtae of 0.57 m3/h, while the average values hardly vary for the bottom gas flowrtae of 2.29 m3/h.

Key words: combination blown converter, number of bottom tuyeres, arrangement of bottom tuyeres, bath mixing time, physical modeling