Uranium Fixation by Mineralization at the Redox Front

DOI Web Site Web Site 1 Citations 6 References
  • Isobe Hiroshi
    Environmental Geochemistry Laboratory, Department of Environmental Safety Research, Japan Atomic Energy Research Institute

Bibliographic Information

Other Title
  • 酸化還元境界における鉱物化によるウランの固定
  • サンカ カンゲン キョウカイ ニ オケル コウブツカ ニ ヨル ウラン ノ コ

Search this article

Description

The behavior of actinide elements including uranium in geomedia is controlled by redox conditions. Under the oxidized conditions, uranium forms uranyl ion (UO22+) and its complexes, and dissolves in ground water. Under the reduced conditions, U(IV) has much lower solubility than uranyl ion. In the Koongarra uranium deposit, Australia, lead-bearing uraninite, uranyllead oxide and uranyl silicate minerals occur in the unweathered, primary ore zone, and uranyl phosphate minerals occur in the weathered, secondary ore zone. Between unweathered and weathered zones, the transition zone exists as a redox front. In the transition zone, graphite and sulfide minerals react as reducing agents for species dissolved in ground water. By SEM, spherical grains of uraninite were observed in veins with graphite. Pyrite had coffinite rim with crystals of uraninite. Calculation based on the ground water chemistry and hydrology at Koongarra shows that the uranium in the transition zone may be fixed from the ground water. In the Koongarra transition zone, recent mineralization of uranium by reduction takes place. Mineralization is much stronger fixation mechanism than adsorption on clay minerals. Pyrite in the buffer materials of possible radioactive waste repositories can fix radionuclides in oxidized ground water by mineralization with reducing reactions.

Journal

Citations (1)*help

See more

References(6)*help

See more

Keywords

Details 詳細情報について

Report a problem

Back to top