This work evaluated the immobilization of uranium (U) through incorporation into calcite under reduced and oxidized conditions. We investigated how much U could be entrapped by calcite crystallizing in chloride solutions in autoclaves at temperatures from 162 to 300 °C. The oxidation state of U was set by controlling oxygen fugacity via redox buffers. Uranium was introduced into calcite growth media as a solid oxide compound or U aliquot. We found the uptake of tetravalent U by calcite is higher than that of hexavalent U by up to four orders of magnitude. We estimate that crystallization of a few mg of calcite immobilizes all dissolved U when 1 kg of solution is saturated with UO₂ under reduced hydrothermal conditions.

这项工作评估了在还原和氧化条件下通过掺入方解石中铀的固定化。我们研究了在162至300°C的温度下，通过在高压灭菌器中的氯化物溶液中的方解石结晶可能截留多少U。通过经由氧化还原缓冲液控制氧逸度来设定U的氧化态。将铀作为固体氧化物或U等分试样引入方解石生长介质中。我们发现方解石对四价U的吸收要比六价U高四个数量级。我们估计，当1 kg的溶液在还原的水热条件下被UO ₂饱和时，几毫克方解石的结晶会固定所有溶解的U。