Hydrothermal Hot-pressing Solidification of Coal Fly Ashand Its Ability of Fixing Heavy Metal

In this paper, hydrothermal hot-pressing solidification of coal fly ash has been done by mixing with different contents of calcium hydroxide and distilled water for 45 min at the condition of 7 MPa and 200°C. The strength of solidified specimens can reach the highest value of more than 63 MPa with 20% calcium hydroxide and 20% distilled water. During strength development, tobermorite may have a larger effect than CSH, and the immobilization of the solidified specimens for heavy metals can be also attributed to the new phases formed in the solidified bodies with different heavy metals. The results showed that Zn and Cd were to be fixed more readily than Cu and Pb.