Research On Migration Simulation Of Trace Elements Based On Gamma Spectrum Measurement

Radon is a radioactive gas in underground exhaust,which can be used as an indicator of deep underground geological structure information.A large number of numerical simulation methods and migration mechanism of radon have been carried out at home and abroad to explore the migration law and distribution characteristics of underground radon.Metallic trace elements will migrate to the surface with radon and other geogas,resulting in ore-to-geogas anomalies on the surface.However,the migration mechanism of metal trace elements is still one of the main problems difficult to be solved.This paper attempts to simulate the migration process of metal trace elements by using the numerical simulation method to simulate the migration behavior of radon in unsteady state.On the basis of summarizing and analyzing the internal and external factors of radon migration mechanism and radon migration model,the unsteady variation characteristics of radon under stress are simulated.Based on diffusion and convection theory,a two-dimensional diffusion-convection dynamic model was established.The finite difference method was used to obtain the numerical solution,and the unsteady variation characteristics of radon under stress changes were analyzed.Simulation of diffusion coefficient on radon migration time and influence law.The simulation shows that the additional 5% convective velocity generated under stress accelerates the time for radon to reach equilibrium,has a significant impact on the concentration of radon,and makes the concentration of radon increase by 16%,and the vertical ground projection point of radon source increases by 13.8%.When the diffusion coefficient increases,radon migration takes longer to reach equilibrium,and its upward migration ability is suppressed.Radon gas migrates slowly in the vertical direction,thus making the migration time of radon longer.Taking baoshan Copper-lead-zinc deposit as an example,the migration simulation of metal trace elements is carried out.The main gamma ray of 64 Cu is 1345.77 ke V,and that of lead is 279.197 ke V and238.632 ke V.The drilling indicates that the depth of Cu mineralization is1690 m.Based on the theory of metal nanomigration,gamma energy spectrum of copper,ore age and burial depth,the gas and migration velocity of copper trace elements in the mineralization environment are simulated to be 3.71×10-9cm/s.Then,the migration velocity is used to simulate the mineralization depth of pb(203Pb,212Pb)in the same mineralization period.The simulation results show that the mineralization depth is 300 m and 1100 m,and the drilling indicated depth is 245 m and1350 m.The simulation results are in good agreement with the actual situation.Based on the effective migration rate of copper,the buried depth of underground rock mass is estimated to be about 3100 m by simulating the energy spectrum of bismuth(214Bi).