Influence of P2O5 and Al2O3 on Mineral Formation in Converter Slag

Converter Slag is a by-product during steelmaking. Reusing the slag as Portland cement material can be regarded as a way to reduce environmental pollution. However, the poor grindability caused by complex chemical composition of the slag makes it very difficult to be used in cement industry. To better understand its grindability, the mineral characteristic of converter slag was investigated in this paper. Experimetal slags of CaO-MgO-SiO2-Fe2O3, CaO-MgO-SiO2-Fe2O3-P2O5 and CaO-MgO-SiO2- Fe2O3-P2O5-Al2O3 were synthetized according to physical and chemical properties of actual converter slag. The mineral structures of these slags were analyzed by SEM and EDS. The results show that actual and synthetic slags have mainly three mineral, where dicalcium silicate with little phosphorus presented dark gray, periclase presented black and the matrix phase of dicalcium ferrite. Moreover, phosphorus largely dissolves in the 2CaO center dot SiO2 in the form of 3CaO center dot PO4, and the other minerals don't contain phosphorus. A Little aluminum has a little influence on the mineral formation of the slag.