COMPARISON OF 2 METHODS FOR PREDICTING TRACE-ELEMENTS FROM FLY-ASH ONACID-MINE SPOILS

Laboratory leaching experiments were conducted to simulate fly ash wea thering in acidic environments and to determine the metal and metalloi d release characteristics of several fly ash materials. Fly ash was pl aced in small cylinders and continuously leached with 0.1 N sulfuric a cid (H2SO4) or simulated acid mine drainage (AMD). Leachates were moni tored for metals and metalloids. When a fly ash was leached with H2SO4 up to its neutralizing capacity only 10 to 30% of the total metals or metalloids were released. At equal levels of total acidity, more meta ls were released by H2SO4 than by AMD probably due to the creation of new oxides or hydroxides of iron (Fe) providing sites for adsorption o f metals or metalloids.