FREMGANGMSAADE TIL IMMOBILISERING AF BLY OG CADMIUMI FASTE RESTER FRA FORBRAENDING AF AFFALD VED ANVENDELSE AF KALK OG PHOSPHAT

摘要

Free-flowing dry residues (I) contg. fly ash (II) and mixts. of (II) with bottom ash are contacted with at least one H2O soluble phosphate in an amt. equiv. to 1-8wt.% H3PO4 (w.r.t. total residue) in the presence of lime, hydrated lime and/or flue gas scrubber prod. as a free lime source which furnishes 1-25 pts. wt. Ca(OH)2 per 5 pts. fly ash. Cd and Pb in (I) are then immobilised and the leaching thereof from (I) is lowered to no more than 1 ppm Cd and 5 ppm Pb thus complying with toxicity tests. Pref. (I) contains 5-20wt.% fly ash and soluble phosphate is poly, hypo or metaphosphoric acid or their alkali metal salts.