Study On The Stability Of Residual Matter In Southern Ion Rare Earth Mines

The southern ionic Rare earth mine is an important strategic resource in China,which is widely distributed in southern regions such as Jiangxi,Fujian,Guangdong and Guangxi province and so on.Rare earth elements were ion-phase adsorption in clay minerals,with a high content of rare earth,mining process is simple and so on.Based on the data of soil survey in the project area,this paper is used as the research object of an abandoned mine in the rerare-earth mining area of longnan county,Jiangxi province,collecting the original weathered crust profile and the profile of weathered crust of the mined area,10 surface water and 2 groundwater in the mining area,using the geochemical analysis of the regular elements,rare earth elements,ammonia nitrogen and sulfate,the content of heavy metal elements in the weathering crust and the water environment,discussing the characteristics of migration and distribution of rare earth elements in the horizontal and vertical directions,the migration characteristics and sources of ammonia nitrogen,the migration characteristics and pollution degree of heavy metals after the exploitation of rare earth mines,analyzing the stability of rare earth,ammonia nitrogen and heavy metals.The results show that the content of constant elements is basically unchanged after the mining of ionic rare earth mining,except for FeO is oxidized to Fe₂O₃,and Mine environment from closed reduction into an open oxidation environment.The total content of clay minerals decreased from 65%to 50%,which is mainly composed of Illite,kaolinite and halloysite.Before and after mining,The average grain size of the weathered shells before and after mining was in the range of 0-2 m in depth,from103.78?m to 76.08?m,increasing first and then decreasing with depth,the average particle size was 125?m when the depth was 3-10m,while the depth was 10-12m,the average particle size before mining was 123?m,after mining reduced to 55.46?m.There is a big difference in migration and transformation of light and heavy rare earths in the study area,which the distribution characteristics of LREE are similar to?REE.In the mining area a,the content of LREE and?REE is lower than the non-mining area,while the distribution of HREE content is just the opposite.rare earth elements is enrichment in the fully weathered layer on Vertical distribution before and after mining.The rare earths in the water environment are mainly controlled by the pH,while the pH of surface water in the mining area is 4.06,which is at the key with the highest activity of rare earth.The excessive levels of ammonia and sulfate is very serious in the study area.In the surface water,the content of NO₃^-and NH₄⁺exceed the standard limit of Grade V of surface water environmental quality standard?GB3838-2002?by a hundredfold and tenfold,respectively.In groundwater,The content of NH₄⁺exceeds the standard limit of Grade V of groundwater environmental quality standard?GB/T14848-93?by hundreds.According to the analysis results of stable nitrogen isotopes,the nitrogen sources are mainly rainwater and ammonia-bearing leaching agent.The high anomalies of heavy metal Pb in the surface soil of the study area are mainly concentrated in the mining area,mainly from the ore-forming Original rock,while the Cd element may have point source pollution,which corresponds to the range of human activities,Obviously not related to mining activities.The results of morphological analysis showed that the total amount of heavy metal element Pb increased 3-8 times more than the national soil background value?26 ppm?after the exploitation of rare earth mines,and the activity ratio increased from 18.15%to34.77%,while Cd did not appear enrichment phenomenon,the activity ratio increased slightly,from 25.15%to 30.25%.In summary,the exploitation of the southern ionic rare earths enhanced the activity of rare earth elements and heavy metal elements,while leaving a large amount of ammonia and sulfate residues,posing a potential hazard to soil and water.In this paper,studing on the stability of rare earths,ammonia nitrogen and heavy metals after the exploitation of the southern ionic rare earths in order to provide the basic data and theoretical support for the environmental restoration and treatment of the southern ionic rare earths.