2020 Volume 60 Issue 10 Pages 2291-2300
Gypsum waste, with CaSO4·2H2O as the main ingredient, decomposed into SO2(g) at a proper temperature, according to previous research. It could sulfurize SnO2 to SnS(g) in the presence of C or CO(g), based on which a method of roasting with gypsum waste (CaSO4·2H2O) for removing Sn from Sn-bearing iron concentrates was put forward in this paper. In addition, a traditional curing agent, FeS2, was introduced and comparatively studied. With FeS2 used as the curing agent for tin sulfurization and removal, the FeS generated from the FeS2 decomposition played a major role through its transformation to SO2(g) and COS(g) in mixed gases of 35 vol.%CO and 65 vol.%CO2. Besides, the COS(g) had a better sulfurization effect on tin than SO2(g). The ‘S’ from gypsum waste (CaSO4·2H2O) was mainly transformed into FeS and Ca3Fe4S3O6 upon roasting with tin-bearing iron concentrate in mixed gases of 35 vol.%CO and 65 vol.%CO2, both of which could sulfurize Sn(l) to SnS(g) also through their transformation to SO2(g) and COS(g). The amount of sulfur added by CaSO4·2H2O could be decreased compared with that added by FeS2 due to the higher utilization efficiency of ‘S’ in CaSO4·2H2O. This process realized the cyclic utilization of gypsum waste, Sn effective removal and the iron pre-reduction from tin-bearing iron concentrate.
