离子型稀土矿原地浸矿“渗流-溶出-传质”过程强化基础研究

The in-situ leaching process of weathered crust elution-deposited rare earth ore exists the problems of bad leaching effect, lixivium and adaptability. Based on these problems, focus on the processes coupling, process control and process intensification, to ascertain the ion exchange and desorption rules of in-situ leaching system and find out its effective strengthening way. Find out the change rule of the pore structure characteristics of weathered crust elution-deposited rare earth ore in the infiltration process. Ascertain the influence mechanism of ore body expand and “Remove-deposit” of fine particle. Find out the effective method to eliminate the formation mechanism of the "Blind area/dead zone" to realize the intensification of the in-situ leaching process. Establish the mass transfer model of in-situ leaching, determine its mass transfer equation and state equation; Find out the optimum mass transfer process optimization approach, establish the full coupling model of "seepage-rare earth dissolution-mass transfer" of in-situ leaching system, reveal the inner link between multiple processes and synergy strengthening mechanism. To formation the fundamental theoretical system of weathered crust elution-deposited rare earth ore in-situ leaching system.

针对离子积型稀土矿原地浸出过程中存在的浸取效率低、浸出液质量差、适应性差等一系列问题，以多过程耦合、过程调控与过程强化为研究主线，揭示原地浸出体系中稀土离子的溶出规律，并探明其有效的强化途径；找出离子型稀土矿矿体在渗流体系中的孔隙结构变化规律，探明矿体膨胀与微细颗粒“迁移-沉积”对渗流过程的作用机制，找出消除“盲区/死区”的有效途径，实现渗流过程的强化；构建原地浸出体系的传质模型，确定其传质表达式，状态方程与传质系数；探索出最佳的传质过程优化途径，构建原地浸出体系“渗流-稀土溶出-传质”全耦合模型，揭示多个过程之间的内在联系与协同作用机制，最终形成离子型稀土矿原地浸出体系“渗流-稀土溶出-传质”过程强化基础理论体系与技术原型。

浸取效率低、浸出液质量差、适应性差等系列问题是制约离子型稀土资源绿色高效开发的关键问题。本项目以典型赣南离子型稀土矿为研究对象，开展了 “渗流-溶出-传质”过程强化基础研究，结果表明，矿体pH值、黏土矿物种类及含量对RE离子吸附特性影响显著，不同REE存在显著解吸特性差异，镧、铈解吸效果更差；RE离子浸出过程受内扩散控制，获取了关键因素药剂浓度与粒径的浸出动力学参数，与RE浸出规律不同，Al浸出曲线呈直线延伸，主要受溶液酸度影响；复合铵盐可促进RE离子正向交换反应，研究了系列助浸剂助浸效果，经纯化制备的LPF效果最佳，多相介质通过降低RE活度及黏土矿物对其的静电引力等协同助浸机制有效强化了RE溶出过程；CT扫描与三维可视化结果显示，矿体孔隙以狭长柱状为主，孔直径集中在0.5-1mm，喉道平均直径300μm左右，胶状微细颗粒易迁移并在小孔隙处沉降堵塞渗流通道，喉道直径是影响渗流的关键，沟流区域周边孔隙堵塞、注液孔密度低是形成“盲区/死区”主要原因，复合铵盐可有效抑制黏土膨胀，表面活性剂及高密度-小速度注液方式可有效促进渗流效果；基于塔板色层理论的Van Deemter方程可准确描述传质过程，矿体均匀程度、纵向扩散系数、传质阻力系数及浸出剂流速是影响传质效果主要因素，采用田菁胶等提高黏土矿物表面亲水性可有效调控扩散系数与传质阻力系数，优化传质效果，亲水性更强的羧甲基化改性田菁胶效果更佳；合适的助浸剂是实现“溶出-渗流-传质”全过程优化调控的关键，耦合各浸出过程发现，浸出剂浓度、浸出剂pH、助浸剂浓度具有显著的交互影响，上述关键因素对浸出效果影响符合三元二次回归方程，pH影响最大；项目实施中发表论文9篇、出版专著1部、授权发明专利3项，形成了原地浸出体系“渗流-离子溶出-传质”强化调控理论基础与技术原型，探索的理论与开发的技术可为离子型稀土矿高效浸出提供理论支持与技术思路。