The Research Of Hydrogeological Characteristics And Zinc Ion' Migration Features In Groundwater Of A Lead-Zinc Mining Area

In this study,The scale of the lead-zinc mine is large.Pumping and drainage have caused groundwater to form a large range of cone.The concentration of Zn²⁺in the groundwater of some sections had exceeded the class III standard for groundwater quality.Therefore,This study use the methods of geological surveys,injecting test,water pressure test,pumping test and sonar flow velocity test,to find out the hydrogeological characteristics and the transport of Zn²⁺in groundwater.It is of great significance to prevent groundwater polluting and ensure the safety of water for production and living in the area.The results obtained in this articel are as follows:?1?The rainfall is plenty in the study area,the geomorphologies belong to transitional zone of structural erosion hilly hills,erosion corrosion peak cong valleis and plains.Low-lying south north high.The interbedding of the soluble rock and the non-dissolvabla rock is mainly developed.The fault structure is dominated by NE and near SN,followed by NW and near EW.?2?Divide groundwater into three types:loose soil pore water,bedrock fissure water and carbonate karst water.Qianjiang is the minimum erosion plane in the area,and the groundwater is drained from west to east overall.However,the drainage of the mines had changed the natural flow field of groundwater,formed a pattern of taking mine as the center,supplementing the eastern river,and recharging the western groundwater.The groundwater dynamics are mainly affected by rainfall,mining and the water level of the Qianjiang river.?3?Water conductivitise of major faults in the mining area:The F₂ fault generally acts as a water barrier,but locally has a water conducting effect;the F₃ fault acts as a water barrier;F₄ is a diversion fault.?4?Total chemical analysis of 22 water samples in the study area showed that:The groundwater in the study area is low salinity,and the total hardness is medium to hard water.The chemical types of groundwater are mainly HCO₃^--Ca²⁺and HCO₃^--Ca²⁺·Mg²⁺.Zn²⁺exceeded where tailings is not stack in the reasonably place.The groundwater quality of the mining area basically reached class III groundwater standards.?5?Used the methods of injecting test,water pressure test,pumping test and sonar flow velocity test,to find out the hydrogeological parameters and groundwater flow rates:?1?The results of water injecting tests in soil show that:The test obtains the hydraulic conductivity is 1.39E-08³.68E-07m/s,the average value is 1.00E-07m/s,and the recommended value is 9.26E-08m/s??2?The results of water injecting tests in rock show that:D₁sl² dolomite has a good overall water content,but its homogeneity is poor.As the depth increases,the water permeability and the water richness of the fractured aquifer weaken.?3?The results of water pressure tests show that:The dolomite permeability is moderately permeable to microscopic,with the karst fissures weakening with depth.The Dale Formation?D₁d?Dolomite,Guanqiao Formation?D₁g?dolomite,argillaceous dolomite,Ertang Formation?D₁e?marlstones,water permeability are all less than 1Lu,and are slightly permeable.?4?The results of pumping tests show that:There is a large difference in water inflow at different locations,Karst development is uneven and poor connectivity;The groundwater recharge area in the southwest is relatively small and is mainly supplemented by the shallow fracture water in the south.?5?The results of sonar methods to measure flow velocity show that:The western part of the country is bounded by fault F₂.Shallow groundwater flows along faults to the northeast,and deep groundwater fills the pits through the fracture network.The observation experiments along the Qianjiang river in the east show that the groundwater fills the pit,confirming the recharge of groundwater in the Qianjiang river.?6?The southern part is a confining boundary;The northwest forms a relatively confining boundary.The northeast and east are the supply boundary of Qianjiang river.Established a concept model for hydrogeology in the area.The simulated values are in good agreement with the observations,which can reflect the characteristics of groundwater seepage and Zn²⁺migration.?7?The high concentration of Zn²⁺is mainly distributed in the Bengshan tailings and the east side of the Daling coal mine.the Solute's diffusion pattern is closely related to the direction of groundwater flow.In the case of pumping water,solute moves towards the pit,when stopping pumping,solute gradually moves to the Qianjiang river,may pollute the water in Qianjiang river.The solute transfer is slow in the western Bengshan mineral,mainly due to the water-repelling effect of the F₂ fault.The simulation results show that,the concentration of Zn²⁺in the tailings won't spread to the residential area on the west side of the mine in the next 20 years,which will have little impact on the residents'drinking water,but will affect the water quality of the Qianjiang river within a certain range.