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A series of improvements in prolonging the AOD refractory lining life in Baosteel are introduced and analyzed in this paper,including modification of the AOD shell shape,adjustment of the top slag components and selection of the side-blowing tuyeres.Firstly,the layout of side-blow tuyeres was altered with the angle between each two tuyeres being 22.5° instead of the original 18°,and the connection of the outside steel shell in the side-blow area was modified from the former platform shape with great stress concentration into a new smooth circle shape.Secondly,the slag components were changed from the former CaO-FeO-SiO2 system to the CaO-MgO-SiO2 system.Besides,the basicity of the top slag was kept higher than 1.8,and the MgO content in the slag was kept within the range of 8％ - 12％.Finally,tuyeres with an inner diameter 13％ smaller than that of the original tuyeres were used.Based on these research and optimization work,the thermodynamics and kinetics in the AOD refining bath has been improved markedly,and the campaign of the AOD has been prolonged from 45 heats at the beginning of its start-up to the current 185 heats.Meanwhile,the yield of chromium alloy and the decarburization efficiency have also been improved.