Viscosity Estimation of Multicomponent Slags of the CaO–SiO₂–Al₂O₃–Fe_xO System Based on Microstructure Analysis

Abstract

Slag viscosity is key factor of liquid steel refining and the smooth slag tapping of entrained flow coal gasifiers, and the accurate estimation of slag viscosity can provide a guidance for the selection of industrial raw material and the control of industrial process. In this study, a structure-related viscosity model about the multicomponent slags of the CaO−SiO 2 −Al 2 O 3 −Fe x O system is developed based on the flow mechanism of silicate melt to improve slag viscosity behavior. The present estimation model improved the expression of activation energy equation on the basis of the model proposed by Nakamoto and expanded the application from the ternary CaO−SiO 2 −Al 2 O 3 system to the quaternary CaO−SiO 2 −Al 2 O 3 −Fe x O system. Then, the structural roles of all the components were clarified, and the types of oxygen bonds were defined by Raman spectroscopy. The fractions of various oxygen bonds were obtained, and the database of oxygen bonds in any composition within the range of experimental slags was generated by utilizing the Lagrange interpolation method. The result showed that the present model had an advantage in estimating slag viscosity within the compositional range of this experiment slag, and the mean deviations between the viscosities calculated by the present model and measured or published viscosities were within 20%. The model will offer a reference for the estimation and adjustment of slag behavior in the metallurgical slag or coal slag, especially for the iron-rich system.

Influence of Fe2O3‐FeS on the structure of iron‐containing clusters in aluminosilicate melts

“…NBO (non‐bridge oxygen)/G(G = Si, Al, or Fe) can explain the effect of the replaced FeS on the polyhedral structure of silicon and aluminum oxides by responding to some extent to the depolymerization of the network, leading to a loosening of the glassy structure and a reduction in the degree of polymerization 51 . The calculation for NBO/Fe refers the assumption of Zhang et al that the proportion of BO (bridge oxygen) in the FeO 4 unit is twice the proportion of [FeO 4 ]‐tetrahedra 52 . Calculated as in Equations () and (): …”

“…51 The calculation for NBO/Fe refers the assumption of Zhang et al that the proportion of BO (bridge oxygen) in the FeO 4 unit is twice the proportion of [FeO 4 ]-tetrahedra. 52 Calculated as in Equations ( 2) and ( 3…”

Evolution of Viscosity and Structure Property during Aluminothermic Reduction of Vanadium‐Enriched Slag

“…The continuous viscosity was measured with a decreased temperature dropping rate of 3 K min −1 , which proved to be a suitable cooling rate close to the equilibrium viscosity measurement. [ 41,42 ] The successful viscosity–temperature curve was recorded at intervals of 0.1 K in the temperature range of 1523–1873 K. The maximum measured viscosity was limited to 5 Pa s. Above this maximum threshold value, the Mo spindle was raised from the molten slag, indicating that the viscosity measurement was terminated. Moreover, the oxygen partial pressure was controlled at 10 −8 atm by a protective CO 2 /CO gas mixture (volume proportion, 1:4.124; flow rate, 0.8 L min −1 ) during the viscosity measurements.…”

Effect of MgO Content on the Viscosity, Foaming Life, and Bonding in Liquid and Liquid/Solid CaO-SiO2-MgO-5Al2O3-30FeO Slags

“…The analysis of the Raman spectral profiles of each sample is conducted according to the Q n Raman shift values presented in Table 3 [14][15][16][17][18]. The results are plotted, as shown in Figure 7.…”