Thermodynamic Consideration on the Kiln Dust Generated from Eco-cement Production

抄録

Eco-cement is expected to provide a solution for both the municipal and industrial problems caused by limited availability of landfill sites. The heavy metals in wastes are vaporized through the sintering process and caught as kiln dust in the bag filter. For the purpose of recycling the metals, the usefulness of thermodynamic calculation in regard to the Eco-cement production process was confirmed, and the behavior of Zn, Cu and Pb components in Eco-cement production was analyzed by means of simulation. Consequently, the results can be summarized as follows: (1) As the volatilization ratio of metals at 1400°C, which is the sintering temperature of Portland cement type Eco-cement, Pb is the highest, followed by Cu and Zn is the lowest. (2) Each component reacts with CaCl₂ and is vaporized mainly as ZnCl₂, CuCl and PbCl₂ in an oxidizing atmosphere of 1400°C. (3) It was found that the volatilization behavior of Cu and Zn are different depending on the employed atmosphere whether oxidizing or reducing. The volatilization ratio of the Cu component is higher than that of the Zn component under an oxidizing condition. On the other hand, that of Zn component is much higher under a reducing condition.