Potential utilization of FGD gypsum and fly ash from a Chinese power plant for manufacturing fire-resistant panels

• Large amounts of FGD gypsum and fly ash generated from power plants in Xinjiang.
• Low leaching potential of FGD gypsum and fly ashes.
• Manufacturing fire-resistant panels from pure FGD Gp and FGD Gp/fly ash mixture.
• Benign mechanical and insulating property of fire-resistant panels.
• High application potential of fire-resistant panels with low environmental burden.

The present study investigates the geochemical characteristics of the flue gas desulfurization gypsum (FGD Gp) generated from a pulverized-coal combustion (PCC) power plant in Xinjiang, Northwest China, with special emphasis on manufacturing fire-resistant panels using this FGD Gp as well as the fly ash collected from the same power plant. The physical, mechanical and insulating properties of the manufactured panels are also determined. The FGD Gp is characterized by low trace element concentration and low leachable potential for environment-concerned trace elements, indicating it can be reused with low environmental implication. Fire-resistant panels were successfully made from pure FGD Gp, pure commercial gypsum (CGp) and different FGD Gp/fly ash and CGp/fly ash mixtures. With the same gypsum/fly ash proportion, the FGD Gp/fly ash panels present relatively lower density, lower water absorption and lower mechanical strength, but higher moisture contents and better insulating capacities than the CGp/fly ash panels. The pure FGD Gp panel presents the best insulating capacity (52 min), much higher than that of the pure CGp panel (42.8 min). The mechanical and insulating properties of the panels are reduced with the increasing of fly ash proportion in the mixtures, but even prepared with 80% fly ash, the manufactured panels can still be used as benign fire-resistant panels with no significantly physico-chemical, and mechanical limitations. Therefore, manufacture of fire-resistant panels from FGD-Gp and fly ash is a very promising application for these coal combustion by-products which are substantially being generated in large amounts from Xinjiang power plants. The manufactured fire-resistant panels can be used in large amount as insulating construction and building materials with low environmental implication and high economic value.