By Rick Watro
Vice President, Covington Operations, WestRock Company
WestRock invested in a new boiler ash handling system to improve management of fly ash at our Covington, Virginia, paper mill to significantly reduce water usage at the mill, and increase opportunities for beneficial reuse of the fly ash created by our operations.
Fly ash is a byproduct of burning coal in boilers for energy in the paper mill's manufacturing process. Our mill previously operated a wet fly ash system, where fly ash is managed in water and sent to a wastewater treatment system. Afterwards, we would manage the wet fly ash in two ponds on our mill’s grounds.
Our new dry fly ash system conveys ash from both our mill’s boilers using the existing transfer system with a new routing. The ash is removed from the conveyor by a drag chain, allowing it to shed most of the water collected in the process. The ash comes into a collector at the top of a silo designated for boiler fly ash. From there, the dry ash can be loaded into truck trailers or rail cars, or wetted and loaded into open-top rail cars and trailers.
The new system enhances the sustainability of our mill operations in three important ways:
- It reduces our mill’s water usage by approximately eight percent per day;
- It improves water effluent quality by reducing the amount of dissolved solids entering the wastewater treatment system and increasing residence time in the treatment system; and
- The dry ash produced by the system allows for easier management of the material and creates better opportunities to use the ash in beneficial ways – for example, as cement aggregate.
As a result, our mill was also able to close the two ponds previously used to manage wet fly ash, eliminating their yearly operating cost for dredging.
We are proud to benefit our community by using less water, improving water quality, and creating economic activity by reducing the cost of our manufacturing process.
WestRock Company received a 2017 AF&PA Leadership in Sustainability Award for Water for its Covington Mill Power Boiler Ash Handling Systems project.