Fly Ash Processing of Thermal Power Plants and Orientation of Rational Utilization By-products in the Context of Circular Economy

Thermal power fly ash is a source of waste that is harmful to the environment and human health. There have been many studies on the treatment of fly ash and the recovery of fly ash for unburnt bricks, porous concrete, etc. However, the amount of coal in these products significantly leads to wasting coal resources in ash (30%). In order to make products cleaner, and meet civil requirements, thermal power fly ash needs to be processed more thoroughly. In this study, fly ash was processed by flotation and acid-leaching methods. Clean coal after flotation in optimal conditions has an ash content of 8.78% and a recovery of 74%; tailing has an ash content of 96.56%. Clean coal after HNO3 and HF leaching with an ash content of 0.36% is recommended to be used as a fuel coal slurry (COM/CWM) or coal electrodes, etc. By-products of the leaching process are recommended to be recovered solvents while the tailings products of the flotation are used to make green concrete, and middling products are used to make unburnt bricks. This research is the first demonstration of UCC production from fly ash. It opens up a direction for efficient production, processing, and use of fly ash in the context of the circular economy trend in Vietnam.