Abstract: In this paper, the 180 t BOF industrial tests of double slag and remaining slag technology were carried outto study the effects of the temperature, TFe of dephosphorization slag and especially the basicities varied over a wide range on the phosphorus distribution ratio of LP, dephosphorization ratioand deslagging time under the condition of high phosphorus containing hot metal, and the phase compositions of dephosphorization slag were alsoanalyzed.The results show that when the basicity of slag varies from 0.9 to 2.6, the phosphorus distribution ratio of LP and dephosphorization ratio are increased with increasing basicity, and the calculated values of LPwith Ogawa empirical formula are slightly higher than the actual values with reasonable extents, when the temperature is relatively low in the range of 1345–1420℃. When the temperature of the dephosphorization end point is increased, the phosphorus distribution ratio LP and dephosphorization ratioare decreased. When the TFe in the dephosphorization slag is changed in the range of 11.30 %–19.42%, the effect of TFe change on the dephosphorization reaction is not obvious.The dephosphorization slag phase consists mainly of a dark gray phaseofCa3Mg(SiO4)2, a light gray phaseof CaFeSiO4, and awhitephaseof Ca2Fe2O5. Among them, P content is the highest in the dark gray phase, which is the mainphosphorus-rich phase.

Key words: double slag and remaining slag process, dephosphorization, basicity, temperature, phosphorus-rich phase