Advances in transparent characterization and targeted intervention for fracture-seepage in deep sandstone uranium leaching systems

WANG Leiming; LI Shuo; YIN Shenghua; CHENG Liang; ZHANG Chao; CHEN Wei; XUE Senmiao

Abstract：Uranium,as a pivotal strategic resource,holds significant importance in the fields of national defense and en-ergy.With the depletion of shallow resources,the deep earth strategy emerges as a crucial means to ensure resource secur-ity.Sandstone uranium ore leaching mining,a method that harnesses natural conditions by injecting leaching solutions to chemically react with ores,transforming uranium from solid phase to liquid phase,has garnered global attention due to its advantages of low cost,short cycle time,pipelining,and unmanned operation.Nevertheless,deep sandstone uranium leaching confronts the"three highs and one disturbance"complex environment of high well depth,high geothermal tem-perature,high geostress,and intense disturbance,where the multi-scale nature of ore layer pore-fracture structures leads to multi-stage solution seepage,intricate seepage paths,and difficulties in uniform permeation.To tackle these challenges,re-searchers have extensively delved into pore-fracture structure characterization,seepage behavior visualization,as well as targeted intervention and macro-control in deep sandstone uranium mines.This paper delves into the current research status of pore fracture-seepage transparency characterization and directional intervention in the in-situ leaching system for deep uranium mining.Specifically,the transparency characterization of pore fracture structures is primarily categorized in-to physical characterization methods and 3D reconstruction technologies.The visualization of seepage processes encom-passes studies on seepage experimental behaviors,the preparation of transparent rocks,and the application of numerical simulation techniques in enhancing seepage visualization.Furthermore,the paper explores the mechanisms of directional intervention and regulation within the in-situ leaching system for deep uranium mining,encompassing strategies such as physical control,biochemical regulation,and sandstone uranium reservoir modification.These research efforts have signi-ficantly improved uranium leaching efficiency,mitigated environmental impacts associated with mining,and propelled the development of green and sustainable uranium resources.Lastly,the paper identifies the bottlenecks and challenges faced in the research on pore-fracture-seepage transparency characterization and directional intervention for the in-situ leaching of deep sandstone uranium deposits.Looking ahead,it is imperative to deepen our understanding of the leaching mechan-isms in such systems,optimize and refine the technologies for transparent characterization of pore-fracture structures and visualization of seepage behaviors,and innovate more efficient and environmentally friendly strategies for directional in-tervention and regulation.