Research On The Behavior Of Tin Removal From Tin-bearing Iron Ores By Reduction Roasting

Abstract:Tin-bearing iron ores is recognized as one of typical complex iron ore resources. It is difficult to separate tin and iron from the iron ores using the traditional physical separation processes, because gangue minerals and cassiterite have complex properties and mineral dissemination particle sizes. The novel process of reduction roasting obtains excellent performance of tin separation. However the behaviors of iron calcium and silicon minerals during reduction roasting and phase transformation of cassiterite are not clear.In this study, tin-bearing iron concentrates from Huanggang of Inner Mongolia and pure minerals of cassiterite, calcite, magnetite and quartz were used as raw materials. The effect of the minerals on the volatilization of tin and phase transformation of cassiterite during the reduction raosting process were studied respectivel. The existences of the calcite, magnetite and quartz have effects on the phase transformation during the reduction roasting process. The formation of tin-doped spinel ferrite (Fe2.6Sn0.4O4) in the weak reduction atmosphere inhibits the volatility of tin, moreover roasting temperature has a significant impact on the reaction between cassiterite and iron oxides to reduce the volatilization. Calcite is easily to decompose into lime at high temperature and then reacts with cassiterite to form calcium tin oxide, which is difficult to reduce and volatilize of cassiterite. In the presence of quartz, silicate stannous (SnO·SiO2) is formed easily through the reduction roasting process. The forming of the reaction intermediates limits the volatilization of SnO in weak reducing atmospheres (lower than20%CO). But quartz acts as a stabilizer to prevent the over-reduction of SnO2to metallic tin, thus the SnO in silicate stannous is volatility. So that it has advantages on the volatilization of tin in strong reducing atmosphere.