基于核磁共振成像技术的堆浸细观渗流速度场特性

Mesoscopic seepage velocity characteristics during heap leaching based on magnetic resonance imaging

采用核磁共振成像技术对柱浸渗流过程进行非接触、无损探测,得到溶液静止和流动时的核磁共振图像.通过对速度值分布的分析,评价了速度场均匀性,得到了均匀性指数与喷淋强度的关系,进而研究了细观渗流速度场分布特性和孔隙内速度场演化规律.研究表明:流速分布具有明显的不均匀性,流速值与孔隙大小并不严格一致;不同喷淋强度下速度值分布趋势相似,最大流速与喷淋强度正相关;通过分析速度场均匀性与喷淋强度间关系可得到喷淋强度阈值,实验中0.7 L·cm-2·h-1为此粒级级配的喷淋强度阈值.现场应用动态喷淋强度可明显改善堆场的渗透性,提高铜的浸出率.

Column leaching seepage processes were detected in a non-contact and non-destructive way by magnetic resonance ima- ging. Column leaching images were obtained when the flow was stationary and running. Mesoscopic seepage velocity field distribution characteristics and velocity field evolution rules inside pores were studied by analyzing the velocity value distribution, flow velocity dis- tribution uniformity, and relationship between evenness index and spray intensity. The research shows that the velocity distribution has obvious inhomogeneity, and the flow velocity value is not in accordance with the pore size strictly. The flow velocity distribution is sim- ilar for different spray intensities. There is a positive correlation between the maximum velocity and spray intensity. A spray intensity threshold can he obtained by analyzing the relationship between velocity field uniformity and spray intensity. The value of 0.7 L· cm^-2 h^- 1 is the intensity threshold of the designated graded distribution. Field applications of dynamic spray intensity can obvious- ly improve the permeability of dumps and the leaching rate of copper.