Find in Library

In this study, molecular dynamics simulation was used to study the effect of SiO₂/Al₂O₃ mass ratio on the structural properties and viscosity of molten fused red mud. The stability of various T–O bonds in the melt was elucidated by analyzing the bond angle and coordination number; the degree of polymerization, and the stability of the melt were explored by analyzing the number of T–O–T bridging oxygen (BO) and the distribution of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi>Q</mi><mrow><mi>S</mi><mi>i</mi></mrow><mi>n</mi></msubsup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi>Q</mi><mrow><mi>A</mi><mi>l</mi></mrow><mi>n</mi></msubsup></mrow></semantics></math></inline-formula> of [SiO₄]⁴⁻ as well as that of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi>Q</mi><mrow><mi>S</mi><mi>i</mi></mrow><mi>n</mi></msubsup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msubsup><mi>Q</mi><mrow><mi>A</mi><mi>l</mi></mrow><mi>n</mi></msubsup><mo> </mo></mrow></semantics></math></inline-formula> of [AlO₄]⁵⁻; the self-diffusion coefficient of each atom was determined by mean square displacement (MSD) analysis; and the trend of the melt viscosity was analyzed according to the relationship between diffusion and viscosity. The results show that as the ratio of SiO₂/Al₂O₃ increases, the viscosity of molten fused red mud first increases, then decreases, and finally increases. This is because Ti⁴ and Fe³⁺ combine with O²⁻ to form [TiO₆]⁸⁻ octahedron and [FeO₄]⁵⁻ tetrahedra, which increase the degree of depolymerization of the melt.