Abstract: Based on SGRS technology， the effect of low basicity dephosphorization (De-P) slag in BOF slagless steelmaking was studied. According to the mass balance of slagless steelmaking， the lower the basicity of De-P slag is， the more CaO will be recycled and the more desilicication of liquid steel will be attained. At the same time， the experimental results show that， with the decrease of De-P slag basicity， the slag melting performance is gradually improved， leading to the beneficial outcomes of increasing the deslagging quantity and reducing the metallic iron content in De-P slag. When the basicity of De-P slag is 1.2-1.8， the hemisphere temperature of De-P slag could be controlled below 1380℃， the free CaO content of De-P slag could be controlled at around 0.7%， and the amount of BOF deslagging in the end of De-P stage could be controlled more than 8t (210t BOF) or 5t (100t BOF).

Key words: converter furnace, slagless steelmaking, low basicity salg, dephosphorization(De-P), mineral phase