Beneficiation of landfilled and ponded fly ash
With interest in the recovery and beneficiation of landfilled ash growing, ST Equipment and Technologies (STET) explains how its unique tribo-electrostatic belt separation system, long used for beneficiation of freshly-generated fly ash, is also effective on recovered ash after suitable drying and deagglomeration. By Lewis Baker, Abhishek Gupta, Stephen Gasiorowski, ST Equipment and Technologies , USA.
Figure 1: STET Separator processing dried, landfilled fly ash
The American Coal Ash Association (ACAA) annual survey of production and use of coal fly ash reports that between 2000 and 2015, over 1Bnst of fly ash was produced by coal-fired utility boilers in the United States.1 Of this amount, approximately 400Mst was beneficially used, mostly for cement and concrete production.
However, the remaining 600Mst are primarily found in landfills or filled ponded impoundments. While utilisation rates for freshly generated fly ash have increased considerably over recent years, with current rates near 55 per cent, approximately 20Msta of fly ash continues to be disposed of. While utilisation rates in Europe have been much higher than in the US, considerable volumes of fly ash have also been stored in landfills and impoundments in some European countries.
