Effect of CaF2 On the Reduction Volatilization of Tin Oxide Under CO-CO2 Atmosphere

A selective reduction volatilization (SRV) process developed by the authors was effective to remove tin from the complex tin-bearing iron concentrates. It is reported that many gangue minerals of quartz, calcite, and fluorite are existent in the concentrates. Our previous studies investigated the effect of quartz and calcite on the removal of tin. In this study, the effect of fluorite (calcium fluoride) was conducted, and pure CaF2 was added into the tin-bearing iron concentrates to investigate how CaF2 affected the tin volatilization behavior under different roasting conditions. The effect of CaF2 on the phase transformation of SnO2 was also determined using SEM-EDS and XRD. The results indicated that SnF2 was much easier to volatilize than SnO under CO-CO2 atmosphere in the presence of CaF2, so the calcium fluoride in the concentrates was beneficial to promote the tin removal during the SRV process.