Effect of slag-remaining operation on dephosphorization based on single-slag converter steelmaking technology

During converter steelmaking process, large amounts of slags are generated which take away heat and iron resources from molten bath. The slag-remaining operation is a kind of hot slag recycling. It is that all or most of the slags are left in the converter for next heat during continuous production of several successive heats. The basicity of the remaining slag is about 3, and the content of (FeO) is about 20%. When slag-remaining operation is adopted, it increases the slagging speed in the early stage. Influence of slag-remaining process on the dephosphorization during converter steelmaking was studied through industrial practice and theoretical calculation. The results show that the slag-remaining operation can realize low cost and high efficiency for converter steelmaking. It can reduce the consumption of lime and achieve better dephosphorization effect. But phosphorus content in slag increases gradually with the increase of slag remaining times and the dephosphorization capacity of slag is reduced, which result in the poor dephosphorization of steel. Therefore, the times of slag-remaining should be less than 5 to ensure the dephosphorization of steel.