Comparison of two methods for predicting trace elements from fly ash on acid mine spoils

Abstract

Laboratory leaching experiments were conducted to simulate fly ash weathering in acidic environments and to determine the metal and metalloid release characteristics of several fly ash materials. Fly ash was placed in small cylinders and continuously leached with 0.1N sulfuric acid (H₂SO₄) or simulated acid mine drainage (AMD). Leachates were monitored 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 metals were released by H₂SO₄ than by AMD probably due to the creation of new oxides or hydroxides of iron (Fe) providing sites for adsorption of metals or metalloids.