The relationship between melt structure and viscosity: the effect of different fluxes on CaO–SiO 2 slags

Abstract Na 2 O, CaF 2 , B 2 O 3 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 Na 2 O, CaF 2 , and B 2 O 3 respectively on the melt structure of the traditional CaO–SiO 2 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 [SiO 4 ] 4− tetrahedrons cannot occur on Na + ions. The overall mobility of the particles in the melt structure is improved with the replacement of Ca 2+ with Na + . Therefore, the fluidity of CaO–SiO 2 –Na 2 O slags is stronger than that of CaO–SiO 2 , and the viscosity is reduced. F − ions mainly bond with Ca 2+ ions to form complexes. The resulting Ca–F structures destroy the electrostatic restraint between Ca 2+ ions and depolymerized depolymerized [SiO 4 ] 4− tetrahedrons in the Ca–O structures, and the fluidity of CaO–SiO 2 –CaF 2 slags are improved. The effect of B 2 O 3 on the melt structure of CaO–SiO 2 is related to the basicity. In this study, when the value of basicity is 1.87, the addition of B 2 O 3 increases the degree of polymerization of the CaO–SiO 2 melt structure, and the viscosity may increases.