Separation of phosphorus from metallurgical-grade silicon via micro negative pressure during oxidative ladle refining
(1. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650093, China;
2. National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China;
3. Key Laboratory (MOST) of Clean Utilization in Complex Non-ferrous Metal Resources, Kunming University of Science and Technology, Kunming 650093, China)
2. National Engineering Laboratory for Vacuum Metallurgy, Kunming University of Science and Technology, Kunming 650093, China;
3. Key Laboratory (MOST) of Clean Utilization in Complex Non-ferrous Metal Resources, Kunming University of Science and Technology, Kunming 650093, China)
Abstract: The stable separation of P from metallurgical-grade silicon (MG-Si) was achieved by introducing a micro negative-pressure (MNP) environment with oxidative ladle refining. The average relative removal efficiency of P was increased from -1.9428% to 21.7638% with the introduction of MNP environment. During MNP oxidative ladle refining (MNPOLR), P was not enriched in slag and instead was separated via gas phase transfer. Despite the low boiling point of P and its highly saturated vapor pressure, the volatilization of P was controlled by gas diffusion during conventional oxidative ladle refining. The continuous separation of fume via MNPOLR weakened the diffusion resistance of P in the gas phase, efficiently separating P from MG-Si. Therefore, MNPOLR is an effective P separation technique that can be widely applied.
Key words: oxidative ladle refining; micro negative pressure; separation; phosphorus; metallurgical-grade silicon