Pyrolysis of Waste Tire Rubber in the Presence of Sn-bearing Iron Concentrates and its Effect on the Tin Removal from this Iron Concentrate

摘要

The Sn-bearing iron concentrate had a great influence on the pyrolysis of waste tire rubbers, and simultaneously the Sn in this concentrate could be removed efficiently during the pyrolysis process. With the additive of Sn-bearing iron concentrates, the gas yield from the pyrolysis of waste tire rubbers increased while the solid yield decreased. This was mainly due to the reduction of Fe_3O_4 by the pyrolysis char. A CaO-MgO containing complex was formed during the pyrolysis of waste tire rubbers with Sn-bearing iron concentrates, which could prevent the formation of stable chemical structures in hydrocarbons and decrease the activation energy of degradation reactions. The derived-oil yield was increased with it. The 'S' in the waste tire rubber could be transformed into Sn-bearing iron concentrates through the formation of FeS and ZnS, and then be oxidized to SO_2 (g) by Fe_3O_4 or reduced to COS (g) by CO (g), causing the sulfur content in the derived-oil to be decreased. Simultaneously, in the presence of these generated SO_2 (g) and COS (g), the Sn in the Sn-bearing iron concentrate could be sulfurized and removed. The Sn residual content in this Sn-bearing iron concentrate was decreased to 0.062 wt.% at pyrolysis temperature of 1 000°C for 60 min in a high purity N_2 flow rate of 100 ml/min.