Abstract:The converter has the production capacity of smelting low phosphorus steel now, and the converter dephosphorization process is still the main difficulty and research focus in the production of ultra-low phosphorus 9Ni steel. The effects of molten steel temperature, slag basicity, FeO and slag amount on dephosphorization of converter were briefly analyzed. Combined the three modes of dephosphorization of the converter with the field tooling and equipment conditions, such as double-association method, three-slag method and double-slag method. Double-association method has large temperature drop, long cycle and difficult production organization. The operation process is complex and the end phosphorus is unstable with three-slag method. By optimizing the converter dephosphorization process, the production of ultra-low phosphorus steel by double-slag smelting process was realized, which simplified the converter smelting process of ultra-low phosphorus steel and improved the production efficiency. The main process parameters of converter dephosphorization were studied. By using the decarburization oxygen lance nozzle, the oxygen flow was controlled following by 83.5% of the decarburization blowing flow, which could achieve good dephosphorization effect and reduce the burning loss of hot metal carbon. The carbon content of semi-steel in dephosphorization stage could not be controlled too low, and the dephosphorization effect and heat control in dephosphorization stage were better when the carbon was 3.0%-3.5%. When the dephosphorization temperature was controlled between 1 300 ℃ and 1 350 ℃, the dephosphorization rate was higher. When the basicity of slag was 1.8-2.2, the dephosphorization rate and slagging effect were better. A pouring slag volume of more than 40%, decarburization period end temperature was controlled by 1 590-1 610 ℃, the mass percent of FeO of slag was more than 20%, and the basicity of final slag was more than 6, the end phosphorus of converter could be reduced to less than 0.002%. Under the condition of slag detection and tapping slide plate used to block slag, reducing the amount of slag and alloy with low phosphorus content adopted in tapping, the phosphorus increase of molten steel could be controlled within 0.000 5%. Through industrial tests, the phosphorus content of the finished castings was achieved to less than 0.002%.
王星, 胡显堂, 危尚好, 周冬升, 王东, 刘敏. 转炉冶炼低磷洁净钢的工艺开发和实践[J]. 钢铁, 2022, 57(11): 53-63.
WANG Xing, HU Xian-tang, WEI Shang-hao, ZHOU Dong-sheng, WANG Dong, LIU Min. Process development and practice of converter smelting low phosphorus clean steel[J]. Iron and Steel, 2022, 57(11): 53-63.
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