Abstract: To solve the problems of low service life of oxygen lance and high oxygen consumption, the design of oxygen lance nozzle was optimized for a 100 t top and bottom combined blowing converter. The study includes measuring the pressure loss of oxygen pipeline, water modeling experiment and industrial test. The result of measuring oxygen pipeline pressure loss shows that the resistance loss of oxygen pipeline is 0.08－0.10 MPa during the using pressure 0.8 MPa, leading to an insufficient oxygen pressure for the original lance nozzle. The water modeling experiment shows that, with the new lance nozzle design, the impact depth of metal bath is increased by 7－18 mm, the impact area of metal bath is enlarged by 28－65 mm2 and the mixing time of bath is shortened by 1.9－9.3 s. The industrial test shows that the smelting time is shortened by 0.5 min, the total slagging materials consumption is reduced by about 1 kg/t and the dephosphorization rate is improved by 1.9 %.

Key words: oxygen lance nozzles, water modeling experiment, industrial test, dephosphorization rate