Study On Diffusion And Migration Law Of Leaching Solution In Coordinated Mining Of Coal And Uranium In Tarangaole Mining Area

Coal and sandstone-type uranium ore resources coexist in Tarangaole mining area,and in situ leaching mining of sandstone-type uranium ore involves complex physical and chemical processes.The structure of ore-bearing matrix and the composition of leaching solution are modified by the reaction of leaching solution and minerals,and the uran-containing leaching solution affects the safe mining of coal resources.In view of the above problem,this article is based on NMR technology monitoring seepage column leaching experiment data and theoretical analysis,core pore characteristics are studied from the microscopic view and leaching liquid corrosion reservoir mineral reaction mechanism,established the uraniferous sandstone coupling of seepage field-field nuclear magnetic resonance（NMR）above conditions on leaching process model of the different aperture porosity and permeability.TOUGHREACT numerical simulation of different temporal and spatial mining sequences of coal and uranium resources is carried out,and the formation evolution law of coordinated development of coal and uranium resources is obtained.The main research results are as follows:（1）Ground leaching mining has a time effect,the leaching process can be divided into three stages:the fluctuation period of dissolution and precipitation（0-97h）,the dominant period of dissolution（97-158h）and the dominant period of precipitation（158-167h）.In the fluctuation period of dissolution and precipitation,the ion concentration of the leaching solution fluctuates,and the dissolution rate of uranium is stable at a low level.The concentration of uranyl carbonate ion increased greatly and the uranium dissolution rate reached the highest level in the dominant stage of dissolution.A large number of chemical precipitates were generated in the dominant precipitation stage to block the migration channel,resulting in a significant decrease in uranium dissolution rate.（2）The amount of leaching solution injection has an important impact on uranium recovery rate,the leaching reaction process is divided into two stages:0-156PV and156-363PV.The first stage is the peak period of uranium leaching,and the leaching solution can fully contact with the uranium minerals contained in the reservoir matrix,and most uranium is leached at this stage.The second stage is the dominant stage of precipitation blockage,and the micropore blockage is serious,and the uranium leaching efficiency is greatly reduced.The function fitting of the scatter plots of micropore,mesopore,macropore and total porosity with reservoir permeability was carried out respectively,and the porosity-effective permeability model of micropore in the aquiline during uranium leaching process was established:lg K=lgΦ_NMR-Mic^11.124+lg3-6.（3）Uranium coal mining sequence affect the spatial distribution of uranium leaching solution,coal and uranium after a prior model simulation to the fifth year,in the horizontal and vertical direction uranium leaching solution of uranium migration diffusion range to reach first coal model 20 years after the spread of the scale,the simulation of 20 years,spread to model in a horizontal leaching solution border,layer,cover the whole uranium deposits in vertical direction,The maximum depth of leaching solution diffusion reaches 73m below the uranium seam,which is only 17m away from the coal seam,which is 33m higher than the maximum migration depth of the uranium first and coal later model,forming a"two-foot tripod"shaped migration field.（4）The uranium recovery rate changes gradually with time.0-8 years is the main period of uranium ore leaching,and the uranium concentration in the leaching solution is the highest in the first year,during which most of the uranium in the ore layer is leached.Between 8-20 years of leaching,the uranium content in the leaching solution decreases slowly and tends to be stable.