Demobilization of heavy metals from mine waters

The present study elucidates the remediation of mine waters by means of geochemical barriers ("active barriers"). Active barrier systems (ABS) are developed which can prevent heavy metal dispersion by introducing the barrier into the mine. Therefore, low-cost materials are investigated which can remove contaminants by chemical, and/or physical mechanisms from water. The materials investigated are industrial byproducts (e.g. fly ash, red mud scale arrears), natural wastes (e.g. tree bark), and relatively cheap natural products (bentonite, zeolites). Red mud and fly ash show the best results for the removal of Zn, Cd, Ni, and Mn from model water. Cd seems to have the strongest binding of the investigated metals on the sorption sites. The main mechanisms of metal removal from solution in this case are sorption and precipitation. Both materials have very good sorption and acid neutralization capacities (ANC), but ANC seems to be the determining factor.