Furnace Bottom Ash (FBA)
FBA is typically grey to black in colour, is quite angular and has a porous surface structure. The characteristics of the FBA are influenced by the type of furnace in which the coal is burned, the rank of the coal, actual operating conditions in the furnace and how the FBA is removed from the boiler station (wet or dry transport). FBA may be ground prior to transport and storage.
FBA is composed of the agglomerated particles formed in pulverised coal furnaces that are too large to be carried in the flue gases. These particles then impinge on the furnace walls or fall through open grates to an ash hopper at the bottom of the furnace.
As by-products of a highly efficient and regulated industrial process, FBA from various types of power stations will typically exhibit similar and consistent properties. Coarse FBA, for example, is often used as a sand replacement, aggregate for lightweight blocks, a road base component, for agricultural drainage mediums and as engineered bulk fill.