Abstract: In order to solve the problem of excessive nitrogen content in liquid steel in LF refining process, each process of smelting was analyzed. The results showed that the initial slagging stage of LF refining was the mainly process for nitrogen content increasing. Through the sampling analysis and thermodynamic analysis, it was confirmed that the increasing of nitrogen content in molten steel was mainly caused by the AlN in the aluminum dross. The synthetic slag with high Al2O3 and low nitrogen content was used instead of aluminum dross, and the usage of aluminum dross was reduced from 2.6 kg/t to 0.6 kg/t, the nitrogen mass fraction could be decreased in 42 % at the endpoint of LF refining in a cast of seven furnaces. It is drawn that the synthetic slag reduces the nitrogen content in liquid steel caused by raw materials without affecting the refining effect.

Key words: LF refining, nitrogen content, aluminum dross, FactSage