Physical And Chemical Seepage Experminent And Solute Transport Simulation Of In-situ Leaching Uranium

With the rapid development of social economy,the demand for energy is also increasing,especially for the consumption of non-renewable energy.As a resource that is scarce and difficult to mine,uranium resources are closely related to our lives.With the development of science and technology and the enhancement of environmental protection awareness,it is proposed to leaching in situ for low-permeability sandstone uranium deposits with large reserves in China The method of mining.In order to improve the efficiency of in-situ leaching and mining,this paper conducts research through a combination of indoor seepage experiments and numerical simulations.First,based on theoretical knowledge such as seepage mechanics and chemical reaction principles,the infiltration fluid in uranium ore sandstone is studied physical chemical reaction to explore the influencing laws and influencing factors of the leaching solution;then based on the conclusions of the seepage experiment and combining with the mining data of a uranium mine to conduct a numerical simulation study to explore the law of solute migration and diffusion during the in-situ leaching The scope ofits leaching provides certain theoretical and technical guidance for the in-situ leaching of uranium.The main research contents and conclusions are as follows:(1)Through indoor seepage experiments,it is concluded that the non-Darcy seepage in porous media changes continuously with the seepage process.It is not only affected by the dissolution of the leaching solution on the sandstone,but also the pressure is an important factor affecting the change of seepage law.Under the injection of 0.8ml/min,the permeability coefficient of the sandstone mine changes dynamically with the change of the inlet pressure,and the change law of the permeability coefficient changes symmetrically about the inlet pressure of0.15 MPa.(2)The pH value of the leaching solution measured through experiments basically showed an upward trend in the first 46 hours,but the permeability coefficient declined in 30-46 hours,indicating that there are differences in the consumption reaction of sulfuric acid leaching solution at different stages,and the change in pH value also reflects The degree of dissolution of the leaching fluid on the sandstone ore and the change of the pore structure are discussed.At the same time,the viscosity of the leaching solution is also constantly changing.The change of the viscosity affects the law of seepage flow of the leaching solution,especially when the penetration rate is small.Therefore,when in-situleaching of uranium is carried out,it is necessary to consider the influence of the viscosity of the leaching solution on the penetration rate.(3)By comparing the simulation results with the field data,the simulation results can well reflect the actual situation of the mining area.During the in-situ leaching of uranium,the leaching solution and uranium in the ore-bearing layer both diffuse and migrate to other aquifers.The grade of uranium in the ore-bearing layer gradually decreases with the increase of leaching time,especially in the first 6months.The uranium and the leaching fluid in the ore-bearing layer will migrate and diffuse to the aquifer under the effect of gravity faster In the upper aquifer.(4)The solute transport and migration are not only affected by the concentration gradient,but also by the head value.The smaller the head gradient,the smaller the effect of solute migration and diffusion,and the greater the difference at the same time and the same distance.The greater the effect,the smaller the difference in the same distance at the same time.(5)Through the combination of particle tracing and solute transport simulation results,in the previous month,the migration and capture areas of the pumping wells were basically circular to the surroundings,but by four months,the pumping wells had affected the vicinity of the wells.The precipitation funnel formed in the area began toaffect the migration and diffusion trajectory of the injection well;and there is a very slow migration zone during the migration of solute to the edge of the mining area.Combining the results of the two,it can be concluded that the solute is moving to the edge of the mining area.There is an intersecting zone between the seepage of the injection well and the trapping well in the diffusion,and this intersecting zone has a great influence on the solute transport.Therefore,it is possible to control the unnecessary leakage of leaching solution and uranium through the rational design of well pattern parameters for mining wells,thereby improving the efficiency of uranium mining and the protection of groundwater environment.