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 Q n Si in [SiO 4 ]-tetrahedra and Q n Al 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.

Viscosity of BOF Slag

“…Thereby, no change or no contamination or minor contamination was previously reported. It was found that the molybdenum from the crucible was dissolved in the slags during viscosity measurements of FeO-containing nickel slag (MoO3 concentrations of 0.25-0.52 wt% and 0.25-0.46 wt% for higher and lower FeO content, respectively) [21,22]. The viscosity curves in our experiments were repeated several times.…”

“…The influence of temperature, slag basicity, and Cr 2 O 3 content on the viscosity of stainless steelmaking slags has been experimentally determined by Liu et al [20]. The viscosity of FeO-containing nickel slag was investigated as a function of FeO/Al 2 O 3 ratio and of Al 2 O 3 /SiO 2 ratio by Zhang and co-workers [21,22]. The influence of TiO 2 content between 5 and 15 wt% on the viscosity of the BF slags was investigated by Jiao and co-workers, using the rotating viscometer.…”

“…Liu et al used scanning electron microscope with energy-dispersive X-ray spectroscopy SEM/EDS in order to evaluate the quantity of secondary phases, e.g., spinel particles, during the viscosity measurement of the stainless steelmaking slags [20]. The structure of FeO-containing nickel slag was analyzed by Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy in [21,22]. The effect of TiO 2 and FeO [24], TiO 2 and Al 2 O 3 [25], and MgO and Al 2 O 3 [26,27] on the structure of BF slag was investigated using FTIR and Raman analysis.…”

“…Chemical analysis of the slag samples after the viscosity measurements was performed only in [17,28], and only Fe was analyzed in [21,22,24]. The non-linear relationship of the natural logarithm of viscosity with respect to inverse of the temperature from the data was reported in [23,33].…”