Viscosity and Structure of CaO–SiO2–“FeO”–Al2O3–MgO System during Iron‐Extracting Process from Nickel Slag by Aluminum Dross. Part 2: Influence of Al2O3/SiO2 Ratio

Nickel slag can be recycled as one of excellent secondary sources due to valuable iron resource and the thermophysical property of CaO–SiO2–“FeO”–Al2O3–MgO system is significant for the iron‐extracting process by aluminum dross. In the present work, the viscosity and structure evolution of CaO–SiO2–“FeO”–Al2O3–MgO slag system are investigated from 1723 to 1873 K, and the influence of Al2O3/SiO2 ratio is studied under the two “FeO” content conditions of 33.17 and 8.13 wt%, respectively. Experimental results show that the slag system changes from silicates‐based to aluminates‐based with the reduction process. Slag viscosity increases with the increasing Al2O3/SiO2 ratio under the both “FeO” contents. Structure measurement shows that the evolution of slag structure is dependent on the coupling effect of in [SiO4]‐tetrahedra and in [AlO4]‐tetrahedra. The average number of equivalent bridging oxygen (n(BO/T)e) in the slag increases from 1.07 to 1.41, 2.46 to 2.60 with Al2O3/SiO2 ratio at 33.71 and 8.13 wt% “FeO” content, respectively. Additionally, the influence mechanism of Al2O3/SiO2 on viscosity and structure of slag is analyzed from the thermodynamic view and atomic level.