Effects of cryolite on properties of low flouride content mould flux for thin slab continuous casting

Cryolite could be as candidate of NaF and CaF₂ to reduce environment pollution in mould flux for thin slab continuous casting. Using industrial and waste materials and synthetic test instrument for the physical properties of slag, the effects of cryolite on melting temperature, viscosity, fluidity, surface tension, Al₂O₃ inclusion and adsorption of mould flux were studied, as well as the effect of basicity on crystallization property. The results showed that when basicity was 0.81, with the increase of cryolite content, melting temperature and viscosity decreased obviously, and fluidity and surface tension of mould flux increased. When basicity was 1.03, with the increase of cryolite content, melting temperature and fluidity increased obviously, and viscosity and surface tension of mould flux decreased. When basicity was 1.22, with the increase of cryolite content, melting temperature increased obviously, and viscosity, fluidity and surface tension of mould flux decreased. Inclusion adsorption had no change in any basicity. The basicity had great influence on crystallization property. The higher basicity was, the more obvious crystallization of slag became. The cryolite content should be less than 9 percent so that it could play an effective role. The results would play a guiding role in designing of mould flux for thin slab continuous casting.