Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

Annual production of crude steel for China was 822.7 million tons in 2014.1) The amount of used steelmaking slags accounts for about 10 to 20 wt.% of the crude steel production. Over the past decades, only about 30 wt.% of the steelmaking slag have been reused in applications, such as road base course material, civil engineering work, and a raw material for fertilizer, etc.2) However, the most efficient way is to recycle the slags into ironand steelmaking process, which will inevitably lead to phosphorus enrichment and the burden of further dephosphorization.3–5) On this occasion, the selective crystallization and phase separation (SCPS) method was taken into consideration.6–8) The main factors of this method are to enrich the phosphorus into a certain phase and to make the enriched phase grow large enough through composition modification. Thereafter, the steelmaking slags, separated from the phosphorous enriched phase, can be efficiently and economically reused. It has been known that in the slags, phosphorous, in terms of 3CaO·P2O5, dissolves into 2CaO·SiO2 phase to form the n2CaO·SiO2–3CaO·P2O5 solid solution.4,5,9,10) However, the Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content