FBA (25 kg) was directly collected from the drag conveyor
following combustion and previous to the recovery of metals. WBA
(25 kg) was taken from various stockpiles stored for at least
3 months in an open disposal environment. After homogenization,
both samples of FBA and WBA were screened to a particle size
below 25 mm and quartered by a riffle-type sample splitter. Afterwards,
the samples were stored in a closed vessel at 4 C in an
inert atmosphere in order to minimize natural aging and moisture
uptake.