A phase‐field model for the study of isothermal dissolution behavior of alumina particles into molten silicates

Abstract

Particle dissolution process refers to the dissolving of one liquid or solid phase into another solvent phase. This process is of vital importance in the engineering material science, and chemical engineering, etc. Here, we develop a phase‐field model with diffusion‐controlled processes at interfaces for isothermal dissolution of alumina inclusion particles in molten silicates, referred as “slag,” with comprehensive compositions applied in process metallurgy. The interfacial energy between solid inclusion particle and molten silicate can vary with different temperatures and chemical compositions. This model is validated using experimental data of high‐temperature confocal laser scanning microscopy (HT‐CLSM) technique. Moreover, the developed model is applicable to predict the dissolution behavior of solid particle in a realistic size scale. The possibility of the model application is illustrated with studies of different physical parameters that affect particle dissolution behavior. The phase‐field simulations show that inclusion morphology influences both the dissolution profile and time, and the influence decreases with the increased temperature. Increasing same amount of Al2O3 component in slag, the increased degrees of the alumina dissolution time in silicates with different V‐ratio values, a ratio between the mass percent of CaO and that of SiO2, are almost the same. If the V‐ratio of slag is relatively small, an increased MgO component in the silicate will significantly decrease the particle dissolution time. On the contrary, the change in MgO component in the silicate will have a minor effect if the value of V‐ratio is quite large. In order to rapidly dissolve the inclusion, basicity index (BI) of molten silicate should be larger than 1.4. A balance between BI and MgO component in slag is suggested to be considered to design or optimize molten silicate (slag) for its application in the refining process of steel manufacturing.

A mechanism theory of dissolution profile of oxide particles in oxide melt

“…In this case, Al XS atoms may substitute for Si atoms at the tetrahedron center, and almost keep the constant angles between tetrahedral 31 . But the bond strength of Al atoms is lower, compared with that of Si atoms in tetrahedral coordination 32‐33 . If the substitution between Al and Si atoms is the main way of the Al incorporation, the average bond strength of networks will become weaker, and then the melt viscosity will decrease.…”

“…9, this slag composition is important in the ladle metallurgy field for inclusion removal. The melt liquidus temperature is 1728 K, 9 and the melt viscosity is calculated using a theoretical model 32 . The simulated results are listed in Figure 13.…”

“…Incorporating Equations (33) and (34) to (31) and 32 The melt liquidus temperature is 1728 K, 9 and the melt viscosity is calculated using a theoretical model. 32 The simulated results are listed in Figure 13. Figure 13A to D show the dissolution profiles with increased temperature from 1773 to 1873 K. The profiles are in parabolic shape in the cases of SiO 2 and CaAl 4 O 7 , and in sigmoidal shape in the cases of Al 2 O 3 and MgAl 2 O 4 .…”

“…31 But the bond strength of Al atoms is lower, compared with that of Si atoms in tetrahedral coordination. [32][33] If the substitution between Al and Si atoms is the (35) Al [4] main way of the Al incorporation, the average bond strength of networks will become weaker, and then the melt viscosity will decrease. Solvang et al 34 also reported that a decreasing viscosity will be obtained through the substitution of Al and Ca atoms for Si atoms in tetrahedral coordination.…”

Phase-field model for crystallization in alkali disilicate glasses: Li₂O–2SiO₂, Na₂O–2SiO₂ and K₂O–2SiO₂

“…Also, Xuan et al calculated the dissolution behavior of alumina particles into molten silicates using a simple and classical PFM. 15) However, the enough small mesh size for the diffuse interface width and the simulation time scale are restricted less than 0.2¯m © 0.2¯m and less than 0.005 s, respectively. To date, it required a development of the PFM technique for the reasonable prediction in the oxide melt system.…”