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Molecular dynamics simulations are used to theoretically calculate the structure and properties of the CaO-SiO2-Al2O3-FeO quaternary slag system with the aim of understanding the influence of the FeO content on the slag structure and properties. The radial distribution function, coordination number, diffusion coefficient, etc. are used to characterize the structural characteristics of the slag. Viscosity is one of the important physical properties in blast furnace ironmaking, having an important influence on the blast furnace oxidation metallurgy process. The results of this study indicate that, as the FeO content is increased, the network structure is destroyed, the diffusion coefficient of each atom increases, and the system viscosity decreases, indicating that the polymerization structure of the CaO-SiO2-Al2O3-FeO slag system tends to be depolymerized. Based on these results, FeO in blast furnace slag has a great influence on the structural characteristics of CaO-SiO2-Al2O3-FeO slag. [ABSTRACT FROM AUTHOR]

• The B 2 O 3 -bearing slag structure was investigated with molecular dynamics. • Boron was found to form planar triangular structure with oxygen. • B 2 O 3 increase polymerization degree by increasing bridge oxygen content. • B 2 O 3 decrease slag viscosity by decreasing the stability of network structure. B 2 O 3 has the advantages of reducing the liquidus temperature and enhancing the fluidity of slag, while its influence mechanism in atomic scale has not yet been fully understood. Molecular dynamics simulation was conducted to investigate the influence of B 2 O 3 on the structure and properties of SiO 2 CaO-Al 2 O 3 -B 2 O 3 blast furnace slag system at 1773 K. Results showed that a large number of [SiO 4 ]4−-[BO 3 ]3− structures are generated in the system after B 2 O 3 added, Si4+ ions mainly exist in the form of [SiO 4 ]4- tetrahedrons and B3+ ions mainly exist in the form of [BO 3 ]3− planar triangular structures and [BO 4 ]5− tetrahedrons. With the increase of B 2 O 3 content, the proportion of [BO 3 ]3− planar triangular structures increase. In addition, the content of bridge oxygen in the microstructure of slag increases obviously, the content of non-bridge oxygen decreases, and the polymerization degree of the system increases somewhat. Through the analysis of microscopic mechanism and the modified NPL viscosity model, combined with experimental data, the truth that the slag viscosity decreases with the increase of B 2 O 3 contents were known in the simulated concentration range. [ABSTRACT FROM AUTHOR]

• The influence of MnO content more than or less than 4 wt% on the structure and properties of slag is different. • High bacisity and the MnO content exceeds 4 wt% enhanced depolymerization of aluminosilicate structure by MnO. • The micro complexity of slag system is positively correlated with the macro viscosity. • Low basicity and high MnO promote lower liquidus temperature of slag. In this paper, molecular dynamics (MD) is used to simulate the local structural order, oxygen bond network and transportation characteristics of the slag system under different basicity, and the influence of MnO on the properties such as viscosity, liquidus temperature and enthalpy was studied. MnO or basicity will not affect the bond length and the coordination number of Si-O, but the coordination number of Al-O is slightly reduced. The conversion rate of BO and TOs to NBO or FO is accelerated when CaO/SiO 2 ratio is 1.2 and MnO exceeds 4 wt%. It indicates that an increase in MnO content at high basicity will make the depolymerization of the slag structure more obvious. The total self-diffusion coefficient of each atoms increases with the increase of basicity and MnO, while the viscosity of slag showed an opposite trend. The enthalpy of the slag increases linearly and the conditions of low basicity and high MnO are beneficial for keeping a low liquidus temperature and realizing the stable and smooth of the blast furnace. [ABSTRACT FROM AUTHOR]