Abstract: At present, the gasification dephosphorization in the process of slag splash protection is an effective slag dephosphorization technology. In order to ensure the effect of smelting and recycling after converter slag gasification dephosphorization, an experimental study on the use of gasification dephosphorization slag as a return material for slagging and dephosphorization was carried out in the laboratory. The research results show that the gasification dephosphorization slag is used for the dephosphorization of molten iron with strong dephosphorization ability in the early stage and low dephosphorization rate at the end point. The dephosphorization ratio and dephosphorization rate of hot metal at the end point are 53.3 % and 0.16 %/min respectively. Comparing the preparation of dephosphorization agent, it can be seen that the dephosphorization effect of the dephosphorization agent is poor in the early stage, and the dephosphorization rate at the end point is high, the final hot metal dephosphorization ratio and dephosphorization rate are 91.6 % and 0.32 %/min, respectively. According to the dephosphorization advantages of the two dephosphorization agents, the mixed ratio of molten iron is used for dephosphorization. When a large proportion of gasification dephosphorization slag is used for dephosphorization of molten iron, the phenomenon of phosphorus reversion occurs; when the mixing ratio is 1∶4, the dephosphorization effect is the best, and the end point dephosphorization ratio is 64.4 %. The CO₂ emission reduction assessment was carried out for molten iron dephosphorization with a ratio of 1∶4 mixed slag  using the life cycle assessment method, and the CO₂ emission reduction per ton of steel was estimated from the beginning to the end of the system boundary by 6.034-10.34 kg, and the ton of steel could save 1.8-3.0 yuan of lime.

Key words: gasification dephosphorization slag, recycling, dephosphorization rate, life cycle assessment, emission reduction