浸矿条件下溶液细观渗流机制及演变规律

Solution mining is an important technology for the treatment of low-grade and complexity metal ores in our country. Leaching efficiency and leaching rate is restricted seriously by the poor solution permeability during the leaching process. Compared with traditional research method which focuses on static ore pile in a macroscopic level, this project pays exhaustive attention to the meso-scale flow inside the pile and its coupled mechanism with leaching reaction: Firstly, the nuclear imaging technology with high resolution is used for obtaining the numerical model of heap microstructure before and after leaching. Secondly, particle image velocimetry and nuclear imaging velocimetry are combined to measure mesoscopic seepage field between the ore particles. Reveals the effections of particle size distribution, sprinkling rate, pore size and connectivity on solution mesoscopic seepage. Thirdly, solution flow experiment under the condition of leaching reaction is carried out. The heap permeability and solution flow velocity under condition of mineral dissolution and solute precipitation are measured to reveal the effection of pore evolution on the solution mesoscopic flow. Finally, relation model between leaching rate, porosity and flow velocity is established. The key influence factor influencing the solution mesoscopic seepage is investigated by using the multiphysics analysis software. Optimization and control mechanism of mesocopic seepage environment within the dump is put forward. Overall, theoretical basis will be provided to optimize the flow process inside the heap by this research.

溶浸采矿是处理我国低品位复杂金属矿产资源的重要技术手段，但是，浸矿过程溶液渗透性差已严重制约矿石浸出率和浸出速率的提高。本项目突破传统的宏观静态矿堆研究方法，深入开展堆内溶液细观渗流特性及其与浸矿反应的耦合机制研究：首先，采用高精度核磁成像技术获取浸出前后矿堆细观结构的数值模型，分析细观孔裂隙结构参数及其在矿物浸出条件下的演变特征；其次，结合粒子图像测速法和核磁成像测速技术，测定矿石颗粒间溶液细观渗流场，揭示颗粒级配、喷淋强度、孔隙尺寸及连通性等因素对溶液细观渗流的影响规律；再次，开展矿物浸出条件下溶液细观渗流实验，测定矿物溶解和溶质沉淀条件下矿堆渗透率、溶液流速等参数，揭示孔隙结构演变对矿堆细观渗流的影响机制；最后，建立浸矿速率、孔隙率、渗流速率之间的关系模型，借助多场耦合分析软件探讨溶液细观渗流的关键影响因素，揭示矿堆细观渗流环境的优化调控机制，为改善矿堆内溶液渗透效果提供理论基础。

溶浸采矿是处理我国低品位复杂金属矿产资源的重要技术手段，但是，浸矿过程溶液渗透性差严重制约矿石浸出率和浸出速率的提高。为揭示堆内溶液细观渗流特性及其与浸矿反应耦合机制，本项目主要开展了以下工作：.（1）基于CT扫描和三维重构技术，建立了级配矿岩散体和单个矿石颗粒的三维数值模型，分析了矿岩散体颗粒间细观孔隙形状、尺寸等结构特征，探讨了矿石粒径对矿堆细观孔隙结构的影响，揭示了单矿石颗粒内部微孔裂隙发育特征，对矿石内部微孔裂隙进行了分类。.（2）利用核磁共振成像技术，获取了柱浸体系矿岩散体颗粒间溶液分布图像，揭示了矿堆细观孔隙内溶液分布特征，得到了不同喷淋强度下柱浸体系溶液渗流场分布特征，揭示了喷淋强度对流速值分布和速度场均匀性的影响，阐明了细观孔隙内溶液流场随喷淋强度的演化规律。 .（3）建立了不同浸矿阶段矿岩散体三维重构模型，探明了浸矿过程矿岩散体线孔隙率、面孔隙率、体孔隙率和孔隙尺寸等参数随时间的演化规律，揭示了粗细颗粒分层条件下矿堆孔隙结构浸矿前后的演变特征，得到了矿物浸出下矿石表面孔裂隙形貌特征，分析了细粒层位置对矿石表面孔裂隙结构的影响。.（4）研究了不同颗粒级配矿岩散体渗透系数随浸矿时间的演化规律，开展了粒子图像测速试验，揭示了孔隙形状、连通性等对矿堆细观孔隙内溶液渗流的影响，分析了矿石内部微裂隙和矿石颗粒间孔隙的分形演化特征，构建了矿岩介质分形渗流的运动方程、窜流方程、状态方程和连续方程，实现了矿岩介质分形渗流演化规律的数学表征。.（5）建立了浸矿反应-孔隙演化-溶液渗流综合模型，通过数值模拟分析了孔隙结构突变条件下溶液渗流轨迹及渗流速度的变化规律，揭示了浸矿前后溶液渗流差异，提出了充气、电场强化等堆浸体系溶液渗流调控措施。.本项目研究成果可为优化矿堆细观渗流环境、改善矿堆溶液渗透效果、提高有用矿物浸出速率和浸出率提供理论支撑，对促进我国浸矿技术的推广应用具有重要意义。