Experimental Study on Immobilization of Uranium in Uranium Tailing Pond Using Different Fixatives

Four fixatives including chitosan, attapulgite, zero valent iron and hydroxyapatite were separately added to immobilize uranium in uranium tailing pond. The species distribution characteristic of uranium was determined by stepwise chemical extraction, and the leaching feature of uranium was measured by toxicity characteristic leaching procedure (TCLP). The results indicate that the effects of fixatives on the species distribution of uranium have significant difference. Exchangeable (including water soluble) uranium is changed into other stable states after addition of chitosan, attapulgite and zero valent iron, and the residual uranium content increases with the introduction of hydroxyapatite. The order of anchorage capacity is hydroxyapatite>zero valent iron>attapulgite>chitosan. The results of TCLP indicate that uranium is activated by chitosan treatment, and leaching increases by 4%-23%. The hydroxyapatite reduces uranium leaching by nearly 80%, which is the best fixative for the remediation of uranium in uranium tailing pond.