离子型稀土矿浸出过程的渗流-反应-应力耦合模拟研究

Simulation Research on Multi-field Coupling in Leaching Process of Ionic Rare Earth Ore Based on COMSOL

基于孔隙流体质量守恒和溶质质量守恒,综合考虑岩土力学固结对土体结构影响,结合浸矿过程的化学反应,建立浸出液对离子型稀土矿浸出行为的渗流-反应-应力耦合数值模型。通过COMSOL软件模拟浸出液通过三轴渗透对稀土矿进行渗透时的渗流运动以及溶质运移过程,并分别研究注液压、轴压、围压3种不同载荷对柱浸过程中渗流场、应力场和浓度场分布的时空演化规律。通过液相和固相中的RE^(3+)和NH_(4)^(+)浓度分布结果表明,注液压由10 kPa增至50 kPa时,液相RE^(3+)浓度峰值有所减小,最大峰值差为0.19 g·L^(-1),而浸出液末端位置大幅度加深,最大位置差为0.051 m,说明增大注液压能显著加快渗流过程的进行,进而缩短浸出周期。增大轴压和围压可使矿体的孔隙结构更为紧密,液相RE^(3+)浓度峰值有所增大,其RE^(3+)浓度峰值差分别为0.37,0.58 g·L^(-1),浸出液末端深度有所减小,最大位置差分别为0.020,0.029m,表明阻碍了浸出液的渗流,延长浸出周期,但在一定程度上能提高浸出率,且围压的提升效果较轴压更大。

Based on the conservation of pore fluid mass and solute mass,taking into account the influence of rock-soil mechanical consolidation on the soil structure,combined with the chemical reaction process in the leaching ore process,the seepage-reaction-stress coupled mathematic model of the leaching behavior of ion-type rare earth ore is established.Using the COMSOL software,the seepage movement and solute transport process are simulated when the leaching agent penetrates the rare earth ore through triaxial penetration.Three different loading patterns of injection hydraulic pressure,axial pressure and confining pressure are studied respectively.The temporal and spatial evolution rules of the distribution of seepage field,stress field and concentration field in the process of column leaching are discovered.The results of the concentration distribution of RE^(3+)and NH^(4+) in the liquid and solid phases show that the concentration peak value of RE^(3+)in the liquid phase decreases slightly,and the maximum peak difference is 0.19 g·L^(-1),but the leaching end position deepens greatly,when the injection pressure increases from 10 to 50 kPa.The maximum position difference is 0.051 m,indicating that increasing the injection hydraulic pressure can greatly accelerate the seepage process and reduce the leaching time.Because increasing the axial pressure and confining pressure make the pore structure of the ore body more compact,the concentration peak of RE^(3+)increases,and the peak difference of the RE^(3+)concentration in the liquid phase is 0.37 and 0.58 g·L^(-1),respectively.The ending depth of the leaching solution reduces.The seepage process and leaching period prolong,but it can increase the leaching rate to a certain extent,and the effect of confining pressure is superior to axial pressure.