The Stabilization of Inorganic Residues Discharging from the Municipal Wastes Treatment System Voaltilization Behavior of Heavy Metals in Inorganic Residues from the Resource Recovery System

Abstract

The volatilization behavior of toxic heavy metals in the residues discharging through the Resoruce Recovery System (RRS) of the municipal wastes was experimentally studied in order to examine the possible secondary pollution induced by the light-weight aggregates production process by utilizing the RRS residues. The RRS residues consist of selected inorganics and pyrolytic dust, and contain toxic metals as shown in Table 1. The pellet was made of the residues and was used for the volatilization experiment.
The volatilizing behavior was examined by using an apparatus shown in Fig.1 under various experimental conditions. It was found that the volatilization of Cd and Pb existing in the residues increased with the rising temperature, and was strongly influenced by carbon content of the pellet, oxygen concentration and velocity of the flowing gas, and increased under a reduced atmosphere as shown in Fig.4 and 5. The Cd and Pb oxides existing in the RRS residues may be reduced by reductive substances generated by thermal decomposition and partial oxidation of carbonaceous materials in the pellet. It is considered that the increase of Cd and Pb volatilization under the reduced atmosphere is ascribed to the increase of metal fraction since the vapour pressures of the Cd and Pb metals are higher than those of the oxides in the temperature range of this experiment.