Structural and transport properties of TiO2-SiO2-mgO-CaO system through molecular dynamics simulations

The structural and transport properties of molten titanium slag have intuitive and important effects on the reaction efficiency of the smelting process, separation efficiency of slag and metal, and quality of titanium slag. Molecular dynamics simulations were carried out to characterize the structural and transport properties of titanium slag with various contents of alkaline earth oxide. The average CNTi-O (Coordination Number) increased from 5.99 to 6.04 while the average CNSi-O increased from 4.57 to 4.93 when the content of alkaline earth oxide increased from 3.5% to 31.5%. The Ti-O-Ti bond angle in the edge-sharing [TiO6] octahedron remained at 100.00 degrees, while the Ti-O-Ti bond angle in the vertex-sharing [TiO6] octahedron increased from 125.25 degrees to 127.04 degrees with an increase in the content of alkaline earth oxide from 35% to 31.5%. A part of the Ti-O bond in the oxygen connection was replaced with the Mg-O bond as the content of alkaline earth oxide increased from 3.5% to 31.5%. The transformation in the oxygen connection reduced the structural strength of the system. The self-diffusion coefficients followed the order: Mg2+>Ca2+>Ti4+>O-2(-)>Si-4(+). The viscosity of the system decreased from 0.098 Pa.s to 0.064 Pa.s as the content of alkaline earth oxide increased from 3.5% to 31.5%, which is in good accordance with the measured results. The results will contribute to predicting and controlling the transport properties of molten titanium slag and will lay the foundation for the efficient production of high-quality titanium slag. (C) 2020 Elsevier B.V. All rights reserved.