The leachability of some metals (Al, As, Ba, Ca, Cr, Cu, Fe, K, Mg, Mn, Ti, Zn) from fly ashes was studied in the presence of ethylenedaimine tetraacetic acid (EDTA) and naturally occurring complexing agents-humic acid (HAs). Secondary complex- forming equilibria taking place in the leachates increase significantly the leached amounts of most metals. Kinetic experiment showed that almost the whole "available" amounts of metals are leached form fly ash within a time period of several hours (mostly within 20 h), with exceptions of matrix constituents (typically aluminium), which are released more slowly.
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