抄録
Waste gypsum from construction materials have to be recycled legally in Japan. The waste gypsum contains CaSO4 and other materials such as papers. And thus it is impossible to reuse them directly as a CaSO4 resource. A treatment at higher reaction temperature seems to be suitable for recycling a large quantity of the gypsum. However, CaSO4 is rather stable even at high temperature, therefore cost-intensive reactants are necessary.
Re-generation of CaO or CaS from CaSO4 was investigated using waste plastics, which were considered as reduction agent. Thermodynamic simulation was employed to find optimal conditions for reduction of CaSO4. Reduction experiments were conducted using reagents of CaSO4 and polyethylene. CaO was formed from CaSO4 and polyethylene mixture over 1273K in air. Crystal water of CaSO4 accelerates the reaction forming CaO. Plastics can be successfully used to produce CaO and CaS from CaSO4 in controlled atmosphere.
