Scavenging and immobilization of trace contaminants by colloids in the waters of abandoned ore mines


Scavenging and immobilization of trace contaminants by colloids in the waters of abandoned ore mines

Zänker, H.; Richter, W.; Hüttig, G.

Inorganic colloids in mine waters are able to influence trace heavy metal transport. In oxic waters they mainly result from the formation of oxyhydroxides and oxyhydroxy sulfates of Fe(III) and Al due to the oxidation of Fe2+ and the hydrolysis of Fe3+ and Al3+. However, the colloid inventories and the colloid properties depend on the mine wa-ter type. Acidic pore waters (pH < 3) contain large amounts (g/l range) of relatively stable ultrafine (< 5 nm) iron(III) oxyhydroxy sulfate particles which most probably consist of a mixture of hydronium jaro-site (HFe3(SO4)2(OH)6) and schwertmannite (Fe8O8(OH)6SO4). Arse-nic and lead tend to be adsorbed onto these colloids. Waters of higher pH (pH > 4) contain smaller amounts (mg/l range) of Fe- and Al-rich colloids of 100 to 300 nm that are unstable. They carry elements such as As, Pb, Zn, Cu, Po, Th, Ac. These trace heavy metals can be scavenged by the colloids and can be immobilized due to colloid coagulation and sedimentation ("natural attenuation"). In the pH range from 4 to 6 (flooding waters) also U(VI) is adsorbed onto the colloidal particles since their adsorption is neither prevented by high acidity nor by the formation of uranyl carbonato complexes. Also U(VI) can be scavenged and immobilized in this pH range. However, in "bulk wa-ters" of pH > 6 such as tunnel waters the adsorption of U(VI) to the colloids is normally prevented by carbonate complexation

Keywords: Colloids; mine waters; iron; aluminum; uranium

  • European Materials Research Society (E-MRS) 2002 Spring Meeting, Symposium C: Colloid 2002. Strasbourg (France), June 18 - 21, 2002.
  • Colloids and Surfaces A: Physicochemical and Engineering Aspects 217 (2003) 21-31

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