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

Abstract

Nickel slag can be recycled as one of excellent secondary sources due to valuable iron resource and the thermophysical property of CaO–SiO 2 –“FeO”–Al 2 O 3 –MgO system is significant for the iron‐extracting process by aluminum dross. In the present work, the viscosity and structure evolution of CaO–SiO 2 –“FeO”–Al 2 O 3 –MgO slag system are investigated from 1723 to 1873 K, and the influence of Al 2 O 3 /SiO 2 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 Al 2 O 3 /SiO 2 ratio under the both “FeO” contents. Structure measurement shows that the evolution of slag structure is dependent on the coupling effect of in [SiO 4 ]‐tetrahedra and in [AlO 4 ]‐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 Al 2 O 3 /SiO 2 ratio at 33.71 and 8.13 wt% “FeO” content, respectively. Additionally, the influence mechanism of Al 2 O 3 /SiO 2 on viscosity and structure of slag is analyzed from the thermodynamic view and atomic level.