TREATMENT OF ACID-MINE WATER WITH CALCITE AND QUARTZ SAND

This study investigates interactions between a typical acid-mine water and a solid mixture of calcite and quartz, In this solid mixture, cal cite provides a source of alkalinity whereas quartz surfaces become pr eferable place for precipitation of produced oxides. The results indic ate that neutralization by calcite dissolution is critical for extensi ve immobilization of metals from these waters, As pH increases, ferrih ydrite, amorphous Al(OH)(3), Cu(OH)(2), and possibly Zn(OH)(2) precipi tate that decreases the aqueous concentrations of Fe, Al, Cu, and Zn. These precipitates also provide more adsorption sites for metal ions. Under the experimental conditions used in this study, Pb sorption was stronger than either Cd or Zn. The presence of ferrihydrite increased Pb and Cd adsorption significantly, Cd was most mobile with respect to the other metal ions studied. Besides metal ions, SO42- is also adsor bed onto oxide surfaces to some extent. An unknown sulfate mineral was present when the mine water lacked dissolved Fe or was not neutralize d by calcite. The mineral is likely a Cu and/or Zn sulfate with struct ural H2O.