Abstract: Influence of different bottom tuyere number and configuration in top and bottom combination blown converters on bath mixing time was investigated in laboratory for improvement of BOF’s bath stirring effect. It is found from the investigation that the suitable arrange where the bottom tuyeres should be set is (0.40—0.65)D (D is bath diameter). Too many bottom tuyere number and symmetrical, dispersive and uniform configuration along the same circumference is detrimental for the whole bath mixing, while unsymmetrical and relatively concentrative bottom tuyere configuration can form the trend of horizontal mixing in the bath, which is benefit to the whole bath mixing and can decrease the mixing time by about 30%. It is proved from the application of the unsymmetrical and relatively concentrative bottom tuyere configuration in industrial converters of Sansteel, Fujian that the metallurgical results at converter blowing end can be improved. Mean product of [C] and [O] concentrations, [%C]•[%O], at end-point of blowing in No.1 and No.2 100 t BOFs were reduced from 0.003 1、0.003 3 to 0.002 6、0.002 7, respectively. In No.1 BOF, average [Mn] mass fraction at end point was increased from 0.183% to 0.212%, mean [P] mass fraction at blowing end was decreased from 0.016 7% to 0.014 8%, and average w(T.Fe) in slag at end-point of blowing was reduced from 15.23% to 13.36%. Mean [%C]•[%O] at end-point of blowing in 120 t BOF was 0.002 5.

Key words: top and bottom combination blown converter, bottom tuyere configuration, symmetrical and dispersive configuration, unsymmetrical and relatively concentrative configuration, bath mixing time, metallurgical result