The relationship between melt structure and viscosity: the effect of different fluxes on CaO–SiO2 slags

Abstract

Abstract Na2O, CaF2, B2O3 are commonly used fluxes in metallurgical slags. These fluxes reduce the viscosity of slags are related to changing the melt structures. In this study, molecular dynamics simulation was used to analyze the main effects of Na2O, CaF2, and B2O3 respectively on the melt structure of the traditional CaO–SiO2 metallurgical slags. The results showed that since Na+ ions have only one charge, and the electrostatic restraint between the multi-charged ions and the depolymerized [SiO4]4− tetrahedrons cannot occur on Na+ ions. The overall mobility of the particles in the melt structure is improved with the replacement of Ca2+ with Na+. Therefore, the fluidity of CaO–SiO2–Na2O slags is stronger than that of CaO–SiO2, and the viscosity is reduced. F− ions mainly bond with Ca2+ ions to form complexes. The resulting Ca–F structures destroy the electrostatic restraint between Ca2+ ions and depolymerized depolymerized [SiO4]4− tetrahedrons in the Ca–O structures, and the fluidity of CaO–SiO2–CaF2 slags are improved. The effect of B2O3 on the melt structure of CaO–SiO2 is related to the basicity. In this study, when the value of basicity is 1.87, the addition of B2O3 increases the degree of polymerization of the CaO–SiO2 melt structure, and the viscosity may increases.