非饱和矿堆溶液渗流迟滞与毛细扩散行为表征

Characterization of liquid seepage hysteresis and capillary diffusion behavior in unsaturated ore heap

  • 摘要: 为深入理解非饱和矿堆内溶浸液毛细渗流扩散以及渗流迟滞行为,本文构建适于非饱和矿堆的毛细渗流模型,利用COMSOL multiphysics有限元数值平台开展毛细渗流可视化模拟研究,并利用时域反射器(Time domain reflector,TDR)实时探测了非饱和堆内持液率变化,探索了基于Design Expert的毛细渗流过程多因素响应规律,讨论了非饱和矿堆持液率、毛细吸力、孔隙率与喷淋强度间的潜在关联机制。研究结果表明:孔隙率对矿堆持液率的影响高于喷淋强度,矿堆持液率随喷淋时间的增长收敛性增加,且孔隙率小的矿堆需要更长的时间才能达到稳态持液;不考虑溶液喷淋强度影响时,矿堆持液率与孔隙比、水力传导系数呈正相关;特别是在喷淋初期(0~20 s),喷淋强度、水力传导系数和孔隙比对矿堆持液率的影响更为显著;初步构建了考虑气液两相运移的非饱和矿堆溶液毛细渗流模型;毛细吸力的变化对孔隙率较小的矿堆更敏感;喷淋强度较大、孔隙比越小时,矿堆底部的毛细吸力越大,更易达到稳态持液状态。

     

    Abstract: To deeply understand the capillary diffusion and seepage hysteresis behavior of the leaching solution in unsaturated ore heaps, this study builds a capillary seepage model suitable for an unsaturated ore heap by employing the COMSOL multiphysics finite element numerical platform to perform the capillary seepage visual simulation. A time-domain reflector is used to detect in-situ liquid holdup changes in the unsaturated heap in real-time, and multifactor response regulations of the capillary seepage process are explored based on a design expert. The potential connection mechanism among the liquid holdup, capillary suction, porosity, and irrigation rate of unsaturated ore heaps is also discussed. Research results show that the heap porosity has an obvious impact on the heap liquid holdup than the irrigation intensity. The increased convergence of the liquid holdup improves with the spraying time, and the ore heap with small porosity takes a longer time to reach a steady status of the liquid holdup. When the effect of the liquid irrigation is not considered, the heap liquid holdup is positively correlated with the porosity ratio and hydraulic conductivity. Especially in the initial stage of the irrigation period (0–20 s), the effects of the irrigation rate, hydraulic conductivity, and porosity ratio on the ore heap liquid holdup are more significant. An unsaturated ore pile solution capillary seepage model considering the gas−liquid two-phase migration is preliminarily constructed. The capillary suction is observed to be more sensitive in the ore heap with lesser porosity. The larger the irrigation rate and the smaller the porosity, the greater is the capillary suction at the bottom of the ore heap, and it is easier for the ore heap to reach a steady state of the liquid holdup.

     

/

返回文章
返回