Numerical simulation and monitoring experiment of liquid injection diffusion range in ionic rare earth ores

Abstract Currently, in-situ leaching is the predominant method for extracting ionic rare earth ores. However, this technique still faces persistent challenges such as low resource utilization efficiency and environmental issues including water and soil contamination. Clarifying the diffusion characteristics of the leach liquid is crucial for addressing these problems. Geophysical methods, particularly conductive electrical techniques, have been widely employed to monitor the diffusion range of the leach liquid. Nevertheless, these methods suffer from limitations such as operational complexity, high costs, and poor timeliness. To overcome these drawbacks, this study first utilizes numerical simulation to determine the influence range of liquid injection, and subsequently evaluates the effectiveness of the high-density resistivity method in delineating its diffusion extent. Based on the deep structural characteristics of a rare earth mine in Fujian, China, identified through high-density resistivity method, a suitable site was selected for a comparative experiment. The experiment compared time-lapse resistivity tomography monitoring with seepage numerical simulations of liquid injection faced actual geological model, and the results demonstrated good consistency in the diffusion ranges identified by both methods. Through theoretical analysis and comparative monitoring results, this study proposes that the integrated approach of “detailed deep structure investigation & seepage numerical simulation of liquid injection” can effectively characterize the diffusion behavior of the leach liquor. This provides theoretical support for the precise placement of injection wells and the design of anti-seepage systems in ionic rare earth mining. contributing to improved mineral recovery rates and reduced environmental pollution from liquid injection.