Study On Pore Structure Evolution And Seepage Characteristics Of Ionic Rare Earth Ore During Leaching

At present,the mining process of most ionic rare earth mines mainly follows the in-situ leaching method using ammonium sulfate solution as the leaching agent.Although this method has the advantages of low cost,protection of vegetation and high leaching efficiency,in actual production,Because a large amount of ammonia nitrogen wastewater generated in the leaching process cannot be effectively treated and causes soil pollution,in order to better realize the green mining of ionic rare earth ore,this paper selects magnesium sulfate as the leaching agent and simulates in-situ leaching through indoor column leaching Process,to study the relationship between the pore structure of the ore body and the law of seepage in the process of in-situ leaching,to avoid the leakage of the leaching solution and the low collection rate of the mother liquor,etc.,to provide help for the actual production of the mine.In order to clearly characterize the evolution of the pore structure during the entire leaching process from a meso level,the whole leaching process is divided into the leaching liquid according to the rare earth content in the leaching liquid per unit time?1h?when the rare earth elements inside the ore sample react with the leaching liquid 5 stages: saturated stage of ore body,initial stage of ion exchange,effective ore leaching stage,remaining reaction stage,and reaction end stage.Studies have shown that during the saturated phase of the ore body,the internal tiny pores penetrate into pore channels under the action of seepage,and no rare earth precipitates at this time;during the ion exchange stage,the porosity of the ore body gradually increases;during the effective leaching stage,the porosity First increase and then decrease;during the remaining reaction stage and reaction stage,the porosity of the ore body fluctuates around a constant value.In order to analyze the evolution of pore structure from a microscopic level,this experiment used a NMR instrument to simultaneously detect the ore samples of magnesium sulfate solution and water at all times during the leaching process to obtain the pore throat and pore size distribution at each time of leaching,and combined with NMR T₂ The atlas and the inversion image of the ore body section,through the comparison between the two,it is believed that the exchange process of the leached ions of the rare earth ore body causes the deposition and release of fine particles in the ore body,thereby generating dynamic pore structure changes and revealing the pore structure during the leaching Evolutionary mechanism.In order to explore the relationship between pore structure changes and seepage laws during the leaching process,based on fractal theory,the pore fractal dimension was used to quantitatively describe the pore structure at various times during the leaching process.The permeability coefficient at each moment under the action of magnesium sulfate solution and clear water leaching can be analyzed from the curve of the permeability coefficient and the fractal dimension of the pore.After counting to a certain range,the seepage effect cannot induce the development of the pore structure at this time,and the permeability coefficient of the ion exchange reaction experiment continues to increase.