海泡石辅助含铀土壤化学清洗及对铀富集研究

Sepiolite Assisted Chemical Cleaning of Uranium Bearing Soil and Its Enrichment of Uranium

运用海泡石辅助对铀矿山的含铀土壤进行化学淋洗。研究了铀在不同粒级含铀污染土壤中的含量,通过搅拌淋洗的方法对土壤进行修复研究,探讨了淋洗时间、淋洗剂种类、温度、超声加热等因素对淋洗效果以及海泡石对土壤中铀的富集的影响。结果表明,随着土壤粒径的增大,土壤中的含铀量逐渐减少,即土壤中含铀量与土壤粒径成负相关关系,且除了砂砾外,其他的铀含量均已超过了铀的目标修复值40mg/kg。淋洗时间为8h,淋洗较为充分,淋洗效果达到最佳,成本合适。通过提高温度、超声辅助等方法,既可以使淋洗效果得到明显的提升,对海泡石的富集效果也有很好的促进作用。在淋洗方面,柠檬酸的效果最好,盐酸的效果最差;在海泡石对土壤中铀的富集方面,硫酸淋洗土壤铀的富集倍数最高,柠檬酸淋洗土壤铀的富集倍数最差。通过构建土壤—淋洗液—海泡石的铀迁移路径实现土壤中铀去除并在海泡石中的富集。

Uranium-bearing contaminated soil of uranium mine was chemical eluted with sepiolite.Content of uranium in different particle sizes of contaminated soil was studied,and contaminated soil was repaired by stirring and elution.Influences of elution time,eluant type,temperature,and ultrasonic heating on elution effect and influences of sepiolite on enrichment of uranium in soil were discussed.The results show that uranium content in soil drops gradually with increase of soil particle size,uranium content in soil is inversely proportional to soil particle size.Except for gravel,other uranium contents exceed the uranium target repair value of 40 mg/kg.When elution time is 8 h,elution is relatively sufficient,elution effect is the best,and cost is appropriate.By improving temperature and applying ultrasonic assist methods,elution effect can be significantly improved,and enrichment effect of sepiolite is also very good.In terms of elution,citric acid has the best effect and hydrochloric acid has the worst effect;in terms of enrichment of uranium in soil by sepiolite,sulfuric acid elution has the highest enrichment ratio of uranium in soil,while citric acid elution has the lowest enrichment ratio of uranium in soil.Removal of uranium from uranium contaminated soil and enrichment of uranium in sepiolite are achieved by constructing soilleacheate-sepiolite uranium migration path.