Removing Tin from Tin-bearing Iron Concentrates with Sulfidation Roasting Using High Sulfur Coal

摘要

With the sulfidation roasting process using high sulfur coal, the tin could be removed efficiently from tin-bearing iron concentrates, and the iron phase was reduced to metal iron. The research showed that the tin removal rate increased with roasting temperature and residence time. Different with the phenomena using pyrite as curing agent, deep reduction of tin-bearing concentrates did not cause tin remove rate decrease. The reason may be that curing rate of tin phases by the SO_2 generated from high sulfur coal pyrolysis was higher, and the formation amounts of iron-tin alloy were decreased. The iron phase was mainly reduced into Fe from Fe_2O_3 and Fe_3O_4 in the roasting process. Tin content of the concentrates was decreased to 0.056% under the conditions of N_2 flow rate of 60 ml/min, roasting temperature of 1 473 K, residence time of 60 min, high sulfur coal addition amounts of 70% and particle size of 200 meshes. The roasting product can meet the standard of BF ironmaking, which requires tin content in iron ores less than 0.08%. The work supplies a new approach for the clean use of high sulfur coal.