基于水资源安全的离子型稀土原地浸矿渗漏控制机理研究

The in-situ leaching technology is the most advanced mining technology in the mining process of ionic rare-earth mine. However, for the ore body developed on a floor with cracks, the leakage from the floor cracks during the mining process will severely pollute water resources, and it becomes the principal technical difficulty of in-situ leaching technology. With the floor-crack-developed ionic rare-earth mine as samples, this project conducts a study on the leakage control mechanism during pre-leaching stage, leaching stage respectively by doing the following: studying the geologic structures of mining lot; summing up the methods of finding out huge floor cracks under ionic rare-earth ore body with geophysical exploration technology, building up man-made seepage-proof floor; as for small floor cracks which can not be found out by traditional methods and unidentified big cracks, through conducting study on leakage characteristics of in-situ leaching process, summarizing the rule of influence exerted by seepage cracks on in-situ leaching leakage field; establishing a scientific approach to find out floor-seepage cracks under ionic rare-earth ore body. Based on the above researches, according to the related hydrogeological parameters, this project establishes an underground water pollution prediction model and plans to build a prior-prevention, process-prediction system of seepage control. Lastly, the findings of this project aim to provide a theoretical guidance to help control and repair the water resources pollution during the in-situ leaching of ionic rare-earth mining.

原地浸矿工艺是目前离子型稀土矿开采中最先进的采矿工艺，但对底板裂隙发育的矿体，在原地浸矿过程中底板裂隙的大量渗漏严重污染了水资源，如何有效控制渗漏已成为离子型稀土原地浸矿面临的核心技术难题。本项目以底板裂隙发育的离子型稀土矿山为样本，开展原地浸矿前、原地浸矿期的渗漏控制机理研究：通过矿区地质构造研究，结合多种地球物理勘查技术，总结出有效查明离子型稀土矿体底板大裂隙的方法，构建人工防渗底板，减少渗漏；对传统方法难以查明的小裂隙和未查明的大裂隙，通过开展原地浸矿渗流特征研究，总结出渗漏裂隙对原地浸矿渗流场的影响规律，科学建立一种查明离子型稀土矿体底板渗漏裂隙的方法；在此基础上，依据在矿山实地采取的相关地质和水文参数，建立离子型稀土原地浸矿地下水污染预测模型。拟构建事前预防、事中预测的渗漏防控体系，为地下水污染控制与修复提供理论指导。

原地浸矿工艺是目前离子型稀土矿开采中最先进的采矿工艺，但对底板裂隙发育的矿体，在原地浸矿过程中底板裂隙的大量渗漏严重污染了水资源，如何有效控制渗漏已成为离子型稀土原地浸矿面临的核心技术难题。.本项目以广东省平远县仁居稀土矿区白石岌矿段为研究对象，运用岩体优势结构面理论，对含矿花岗岩体节理构造进行研究，确定了岩体中对气液和岩体稳定性起控制作用的2组优势结构面的方位，开展了优势结构面研究；计算了岩体的RQD值，对岩体的稳定性进行了评价。.开展了矿体底板隐伏构造研究。划分出第四系洪冲积物、坡残积层粘性土、花岗岩、凝灰岩和断裂破碎带5种地层类型，分别进行了电阻率测定。选择高密度电法对开采矿段进行勘察，发现了1条走向约为SE105°、倾向近北、倾角变化范围从71°到近似垂直的规模裂隙，并得到了工程验证确认，采用人工注浆的方法对规模裂隙进行了封堵。.开展了矿区地下水及地表水环境影响分析与预测研究。在钻孔中进行水文地质参数试验，确定了冲积层、残坡积层、强风化花岗岩、弱风化花岗岩的渗透系数和给水度；通过对开采矿段边界性质、内部结构、渗透性质、水力特征和补径排条件的分析，采用有限元法构建了研究区溶质运移数值模型，对研究区污染趋势进行模拟分析和预测，重点分析了铵根离子在不同时间节点在地下水中富存和运移的规律及其对地下水的影响程度。.开展了矿区地下水污染风险评价研究。通过对原地浸矿区地下水污染源、污染途径和地下水污染风险影响因素分析，从地形因素、地质因素、水文因素、开采因素中确定了14个单项指标作为评价指标，构建了基于灰色理论的地下水污染风险综合评价方法。同时，提出了原地浸矿对水资源环境影响的调控建议。.以上研究有效减少了原地浸矿过程中因母液渗漏对水资源的污染，为矿区地下水污染预测和治理提供了理论指导，对构建资源节约型、环境友好型稀土矿山开发具有一定的理论价值和应用价值。