Magnetite and inorganic sludge were mainly composed of Fe2O4 and Fe2O3, respectively. Initial specific surface areas of magnetite and inorganic sludge were 130 m2/g and 31.7 m2/g. CO2 decomposition rate for inorganic sludge was increased with temperature. Maximum CO2 decomposition rates were shown 89% for magnetite at 350℃ and 84% for inorganic sludge at 500℃. Specific surface area for magnetite was not varied significantly after CO2 decomposition. However, specific surface area for inorganic sludge was greatly decreased from initial 130 m2/g to approximately 50~60 m2/g after reaction. Therefore, it was estimated that magnetite could be used for CO2decomposition for a long time and inorganic sludge should be wasted after CO2 decomposition reaction.

This research was conducted to estimate the characteristics of carbon dioxide decomposition using an inorganic sludge. The inorganic sludge was composed of high amount (66.8%) of Fe2O3. Hydrogen could be reduced with 0.247, 0.433, 0.644, and 0.749 at 350, 400, 450, and 500℃, respectively. The carbon dioxide decomposition rates at 250, 300, 350, 400, 450, and 500℃ were 32, 52, 35, 62, 75, and 84%, respectively. High temperature led to high reduction of hydrogen and better decomposition of carbon dioxide. The specific surface area of the sludge after hydrogen reduction was higher than that after carbon dioxide decomposition. The specific surface area of the sludge was more decreased with increasing of temperature.

This research was performed to evaluate heavy metal leaching characteristics of the sludge from paper mill process with sintering temperature. Heavy metal leaching of the sludge was characterized with Korean Leaching Test and Toxicity Characteristic Leaching Procedure. The test sludge was composed of 70.72% of moisture, 9.5% of volatile solids and 9.76% of fixed solids. As a result of XRF analysis, Fe was the highest inorganic element in approximately 83%, which implies the recycling possibility of the sludge in reuse of Fenton chemicals and artificial lightweight aggregate. Leaching of heavy metals from sintered sludge was lower than the dry ones. However, there was no significant difference in leaching characteristics between the sludges sintered at 350℃ and 650℃. Zn and Fe were leached more greatly in TCLP and KLT methods respectively.