蒙脱石与沸石矿物对铀尾矿库有害物的原位阻滞作用与机制

Montmorillonite and zeolite minerals have good performance to adsorb and immobilize radioactive and heavy metal elements. Based on the study of chemical and mineral composition, as well as physical and chemical properties (such as particle size, porosity, pH, etc.) of the deposit of uranium tailings including its leachate, the injecting paste material that is made from montmorillonite which has superior dispersibility is injected into the deposit of uranium tailings, then the NaAlO2 alkaline solution is injected into the pores of the montmorillonite/uranium tailing composite formed previously, and the zeolite minerals are synthesized in situ in the pores with NaAlO2 and montmorillonite in alkaline water system. The research contents include the in situ adsorption of montmorillonite on the harmful metal ions and its characteristics of pore closed, watertight and airtight, the in situ adsorption and solidifying properties of synthesising zeolite minerals on the harmful metal ions and radon，and the cementation and impermeable characteristics, the watertight and airtight of the montmorillonite or zeolite minerals/uranium tailing composites as well as the immobilization effect on the harmful metal ions and radon. Combining with theoretical analysis and experimental characterization, the identified contents include the chemical and mineral composition, the physical and chemical properties of the deposits in the typical uranium tailing impoundments, and the injection properties of Montmorillonite colloidal materials for the deposit of uranium tailings, as well as the selective adsorption of montmorillonite and zeolite minerals for the harmful metal ions in the percolate of the uranium tailing impoundments. The revealed problems include the in-situ closed and solidifying effects, and the blocking mechanism of montmorillonite and zeolite minerals for the harmful metal ions and radon. The technology and theoretical models of the in-situ closed and solidifying process for the uranium tailing impoundments would be found. Above all is to provide theory and technical basis for the treatment of the uranium tailing ponds.

蒙脱石、沸石矿物对放射性和重金属离子具有良好的吸附和固化性能。在铀尾矿堆积物（含渗滤液）化学和矿物组分及理化（如密度、颗粒学、孔隙和化学）属性研究基础上，利用蒙脱石良好防渗性和胶体分散性制成注浆材料注入铀尾矿库堆积物中，形成蒙脱石/铀尾矿堆积物复合体，研究蒙脱石对有害金属离子原位吸附、孔隙封闭及水密气密作用；研究注入的NaAlO2与蒙脱石在碱性水体系中形成沸石矿物及对有害金属离子晶格固定、原位吸附和固化作用；研究蒙脱石、沸石矿物/铀尾矿复合体的密水、密气及对有害金属离子的固化效果；与理论分析和实验表征相结合，查明典型铀尾矿库中堆积物的化学和矿物组分及理化属性、蒙脱石胶体可注入性及蒙脱石和沸石矿物对铀尾矿渗滤液中有害金属离子的吸附规律；揭示蒙脱石、沸石矿物对铀尾矿堆积体孔隙的原位封闭和固化作用及对有害金属离子和氡气的阻滞机制；建立铀尾矿库原位封闭与固化的原理模型，为铀尾矿库治理提供理论依据。

铀尾矿堆积体在大气降水的淋滤和地表潜水的渗滤作用下，其内的有害金属离子较易进入地表水和浅层地下水中，给人类健康和生态环境带来严重危害。因此，防止铀尾矿库退役后有害金属离子特别是放射性元素的迁移一直是环境领域国内外关注与研究的重要课题。.膨润土、沸石矿物对放射性和重金属离子具有良好的吸附和固化性能，是治理铀尾矿库潜在的固化基材。以我国铀矿山尾矿为研究对象，在铀尾矿矿物组分及理化属性研究基础上，研究了尾矿中有害金属离子的含量、赋存状态和可迁移活性。并进一步研究了尾矿粒度、淋滤液pH等因素对铀尾矿堆积体中有害金属离子的迁移影响；并基于膨润土良好的阳离子交换性、防渗性和胶体分散性，将其作为吸附和阻滞材料，研究了膨润土对有害金属离子的吸附行为，将其注入铀尾矿堆积体中形成膨润土/铀尾矿复合体，以及复合体中膨润土凝胶对有害金属离子的吸附、孔隙封闭及密水性；研究了膨润土在碱性水体系中形成沸石矿物及对铀尾矿堆积体的密水和对有害金属离子的阻滞效果；查明了铀尾矿堆积体的化学和矿物组分及理化属性、铀尾矿堆积体中有害金属离子的迁移规律、膨润土对铀尾矿中有害金属离子的吸附规律、膨润土转化为沸石矿物的优化合成条件；揭示了铀尾矿堆积体中有害金属离子的迁移机制、膨润土对铀尾矿中有害金属离子的吸附机制以及膨润土、沸石矿物对铀尾矿堆积体孔隙的原位封闭和固化作用及对有害金属离子的阻滞机制。