Study On Heap Leaching Structure Of Ion-adsorptionbed Rare Earth Based On Unsaturated Percolation Theory

Ion adsorption rare earth deposits are rich in medium and heavy rare earth elements that play an important role in a variety of high-tech fields and are known as the "industrial vitamin" of modern industry.The misuse of the in situ leaching process over the years has led to a long history of predatory and crude mining of ion-absorption rare earth resources,resulting in a serious waste of resources and environmental damage.The key to solving the problems of rare earth yield and environmental protection lies in the development of leaching technologies that match the structure of the ore body,break through the limitations of in situ leaching methods,innovate and optimize the heap leaching structure,improve the leaching efficiency,and achieve green and efficient mining of ion-adsorbed rare earth.In this paper,we investigate the water-holding and permeability characteristics of ionadsorbed rare earth,carry out physical model tests and numerical simulations of different heap leaching structures,optimize the heap leaching structure and establish a new heap leaching method.The specific work is as follows:(1)The soil-water characteristics of ion-adsorbed rare-earth with different pore ratios were tested,and a bimodal soil-water characteristic curve model considering the influence of pore ratios was established.The water-holding characteristics of ion-adsorbed rare-earth were analyzed using three bimodal soil-water characteristic curve models;the pore size distribution curves of ion-adsorbed rare-earth were calculated using the LI model derivation;a bimodal soil-water characteristic curve model considering the influence of pore ratio was proposed based on the LI model,and a high-precision three-dimensional soil-water characteristic surface of pore ratio-substrate suction-saturation was drawn.(2)The saturated and unsaturated permeation tests of ion-adsorbed rare-earth with different pore ratios were carried out to investigate the permeation characteristics of ion-adsorbed rare-earth with different pore ratios.The saturation permeability coefficients of ion-adsorbed rare-earth were measured using the variable head method;a test device combining the filter paper method and the transient profile method was developed for measuring the unsaturated permeability coefficients of ion-adsorbed rare-earth;the accuracy of the BLN-Mualem unsaturated permeability model was verified for the unsaturated permeability test results.(3)The physical model tests and numerical simulations of four different heap leach structures were carried out to demonstrate the rationality of numerical simulations for heap leach structure studies.A comparative analysis of the seepage parameters of the different heap leach structures was carried out;the advantages and disadvantages of the lateral and pipe feed methods and the role of the drainage body structure were investigated;an optimal heap leach structure was identified.(4)The optimal heap leaching structure is structurally optimized through numerical simulation,and a new heap leaching method is proposed.The shape and variation law of the wetted body during the infiltration process of the pipe-inlet method are explored to reveal the spatial and temporal variation law of the pipeline parameters and soil parameters on the infiltration distance and the transport rate of the wetted peak;the influence of different composition structures on the seepage field of the heap leaching structure is explored;new ideas and references are provided for the green and efficient mining of rare earth resources.