铁屑去除酸法地浸采铀地下水中硝酸盐的试验研究

Study on reduction of nitrate from in-situ acid uranium leaching groundwater with iron particles

在酸法地浸采铀过程中,硝酸及硝酸盐的广泛使用使硝酸盐在地下不断累积并扩散到地下水中,这给矿区地下水造成了一定程度的污染。本试验以铁屑为还原剂,对该地下水中NO3--N的去除进行了批试验和动态试验研究。试验结果表明,铁屑可有效去除地下水中的NO3--N,其去除率随pH值的降低而逐渐升高;溶液中共存的Ca2+、Mg2+对NO3--N的去除影响不大,而SO42-、HCO3-的存在可明显降低NO3--N去除率;铁屑最佳投加量为120 g/L,铁炭最佳体积比为1∶1;二级柱可以明显提高柱子的稳定运行时间,在55 h内NO3--N去除率可保持在93%以上,去除效果较好。

Nitrate acid and nitrate are widely used in in-situ uranium leaching. Nitrate in lixiviant accumulates gradually and diffuses to groundwater, which causes nitrate pollution in groundwater of diggings at some extent. Nitrate remediation from in-situ acid uranium leaching groundwater is investigated with scrap iron through batch and dynamic experiments. The results indicate that nitrate can be removed by iron effectively, and the removal rate increases with decreasing pH value. Coexisted irons of Ca^2＋ ,Mg^2＋ have little effect on removal rate, but the coexisted anions of SO4^2- , HCO3^- blocked nitrate removal obviously. The best amount of scrap ion is 120 g/L and the best volume ratio ion to carbon is 1： 1. Two-stage column improves the steady runtime obviously and gets a better effect. Nitrate removal rate keeps in 93% for about 55 hours.