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Sn separation from Sn-bearing iron concentrates by roasting with waste tire rubber in N2 + CO + CO2 mixed gases

Yu, Yong, Li, Lei, Wang, Jiayun, Wang, Jingcheng, Li, Kongzhai
Journal of hazardous materials 2019 v.371 pp. 440-448
alloys, carbon dioxide, carbon monoxide, carbonyl sulfide, dust, ferrous oxide, gases, hydrogen sulfide, iron, iron oxides, nitrogen, pyrolysis, roasting, rubber, sulfur dioxide, temperature, thermodynamics, tin, tin dioxide, tires, volatilization, wastes, zinc
The waste tire rubber releases CO, H2S, SO2 and COS during pyrolysis process in N2+CO+CO2 mixed gases, which can reduce and sulfurize SnO2 to SnS thermodynamically. Correspondingly, a new process to separate Sn from Sn-bearing iron concentrates through roasting with waste tire rubbers at a relative low temperature (1273 K) is put forward in the present paper. The formation of Fe-Sn alloy restricts Sn volatilization obviously during the roasting process, and its formation mechanism differs related to roasting temperature and CO content in the mixed gases. The Fe-Sn alloy formation could be weakened and the Sn residual content is decreased to 0.020 wt % at a roasting temperature of 1273 K and waste tire rubber amount of 10 wt %. Meanwhile, the Fe content in the roasted residue increases to 72.25 wt % through a reduction of Fe3O4 to FeO under a mixed gas of 58%N2+21%CO+21%CO2, realizing the tin removal and iron resource utilization from Sn-bearing concentrates. Besides, the zinc which originated from waste tire rubber in the roasted residue is low to 0.015 wt %, implying that it is concentrated in the dust and could be recovered using a dust collection process.