不同固定剂对铀尾矿库中铀稳定效果的试验研究

利用壳聚糖、凹凸棒土、还原铁粉和羟基磷灰石4种固定剂对铀尾矿库中的铀进行固定化处理，通过逐级化学提取法和毒性浸出试验（TCLP）研究了铀尾矿库中铀的形态分布特征与浸出特性。结果表明：固定剂对铀的形态分布的影响存在显著差异，壳聚糖、凹凸棒土和还原铁粉掺杂后主要促进可交换态（包括水溶态）铀向其他较稳定结合态铀转化，羟基磷灰石掺杂显著提高了残渣态铀的含量。固定能力强弱依次为：羟基磷灰石>还原铁粉>凹凸棒土>壳聚糖。TCLP结果表明：壳聚糖增强了铀的活性，浸出量增加4%~23%；羟基磷灰石降低铀的浸出量近80%，是铀尾矿库中铀稳定效果较好的一种固定剂。

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.