Numerical Study of the Kinetics of Dephosphorization with Single-Flow Post-combustion Oxygen Lance in Converter Steelmaking Process

A gas-metal two-phase flow model was established for the 250 t converter blowing process, and a coupled mass transfer model based on the standard k-ε model for converter dephosphorization kinetics was used to study the effects of different oxygen lances and bottom blows on the molten steel velocity, melt pool phosphorus distribution and end-point phosphorus content. The results show that the post-combustion oxygen lance (POL) had greater molten steel velocity, smaller dead zone area, larger impact area and lower phosphorus content in the molten pool than the conventional oxygen lance (COL). Top-bottom blowing conditions of the conventional oxygen lance (COLB) and post-combustion oxygen lance (POLB) in the melt pool speed were significantly increased, the impact area increased, and the efficiency of dephosphorization was improved. When the blowing time was 800 seconds, the phosphorus content of the COL, POL, COLB and POLB were 487, 426, 409, and 373 ppm, respectively. The POLB had the highest phosphorus removal efficiency and phosphorus content was in exponential relationship with blowing time. Finally, the industrial test was conducted in the 250 t converter, and the POL had little change in lance position during the blowing, the dephosphorization rate was increased by 1.41 pct, and the total iron in the final slag was slightly lower by 0.25 pct.