New understanding on the separation of tin from magnetite-type, tin-bearing tailings via mineral phase reconstruction processes

Magnetite-type tin-bearing tailing is a typically complex secondary resource in China, of which iron and tin are with greater value. The utilization of this resource has long been a challenge due to the complex mineralogy of tin and iron minerals. In this study, the mineralogical characteristics of the tailings were studied. It was found that tin mainly existed as fine-grained cassiterite and lattice Sn4+ (Fe3-xSnxO4) in magnetite particles, which was almost impossible to recover by physical mineral processing. Fe2.6Sn0.4O4 samples were synthesized to study the mineral phase reconstructions of Fe3-xSnxO4 under CO−CO2 atmosphere, as well as in the presence of Na2CO3 or CaO. Then, three proposed processes of selective reduction roasting, sodium roasting and calcium roasting processes were demonstrated and applied in the separation of tin and iron. Finally, some suggestions were recommended for the separation of tin from magnetite-type tin-bearing tailings.