Molecular Dynamics Simulation of the Structure and Properties of CaO-SiO2-CaF2 Slag Systems

Abstract

As a fundamental slag system in metallurgical processes, the CaO-SiO2-CaF2 system, its properties, and related microstructures are of critical importance. The effect of the binary basicity and addition of CaF2 on the structure and viscosity of CaO-SiO2-CaF2 slag were investigated using molecular dynamics simulations and Fourier transform infrared spectrometry. The average bond lengths of Si-O, Ca-O, and O-O were 1.61, 2.31, and 2.61 A, respectively, and the coordinate number of Si remained constant. O-Si-O maintained an angle of 109.2, which was considered to be unaffected by the basicity changes. With increasing basicity, the network connectivity degrees Q3 and Q4 decreased, and the microstructure of the melt was significantly simpler. The effect of CaF2 on the depolymerization of the network structure was not obvious, and CaF2 acted mainly as a diluent. The calculations showed that the viscosity decreased upon setting up a ratio of nonbridging oxygen over tetrahedrally coordinated atoms (NBO/T). A good linear relationship was confirmed between the viscosity of the molten slag and the NBO/T.