PROCESS INVESTIGATIONS CONCERNING THE ELE CTROCHEMICAL IMMOBILIZATIONOF URANIUM SPECIES ON MICROCONDUCTOR STRUCTURES

The current state of the art concerning the elimination of uranium fro m acid mining drainage is characterized by the fact that the uranium ( VI) can be removed by hydrolysis and flocculation of iron (Ill)-salt a nd coadsorption at the hydroxide flakes. This mine water cleaning proc edure, which is applied relatively often to uranium fixing has the dec isive disadvantage that the resulting uranium containing felling sludg e is spent on dumps and is leached by fall out events or groundwater. In order to overcome this disadvantage and electrochemically based con version concept on the basis of an electrochemical solid bed reactor h as been developed. In this concept the mobile U(VI)-species are reduce d on the surface of microconductors to immobile U(IV)-species. In this way, the post-worry and protection of such dump bodies should be form ed essentially more economically concerning a remobilisation. This con cept was proofed in laboratory experiments. A mechanism of U(VI) adsor ption and the subsequent electrochemical reduction on the surface of t he microconductor to U(IV) is suggested and discussed. During applicat ion in closed columns a ''backwash'' has to occur in order to minimize surface blocking of the acitve sites inside the solid bed reactor.