Hamelehle, J, Schmitt, C & Keat, J 2023, 'Design and commissioning of coal fly ash filter plant', in GW Wilson, NA Beier, DC Sego, AB Fourie & D Reid (eds), Paste 2023: Proceedings of the 25th International Conference on Paste, Thickened and Filtered Tailings
, University of Alberta, Edmonton, and Australian Centre for Geomechanics, Perth, pp. 403-413, https://doi.org/10.36487/ACG_repo/2355_30
Coal-fired power plants have come under stricter environmental regulations for their waste disposal with some requiring the stored fly ash slurry to not have any bleed water as measured by the paint filter test. Slurry at a solids concentration that passes this test is considered a paste by most definitions. Transporting this paste presents significant technical problems. Instead, some coal-fired power plants have opted to filter the fly ash and transport the filter cake using conventional dry material handling methods such as trucking and conveying.
This case study looks at a coal-fired power plant located in the continental northwest USA that decided to filter its fly ash to meet these new environmental regulations. The new filter plant would receive approximately 2,800 metric t/d of fly ash from a pair of existing paste thickeners. The new pressure filter system would filter the fly ash to a cake moisture low enough to be trucked to the storage facility without liquefying in the bed of a truck.
This paper outlines the design process of the fly ash filtration, conveying, and truck loadout performed by Paterson & Cooke. Some vital issues discussed will be deciding on what filter technology to use and designing to ensure continuous operation. Also included in this paper are major lessons learned during commissioning and ramp up to full throughput operation.
Keywords: coal fly ash, pressure filtration, plant commissioning