| Backfill mining has greatly solved the problems caused by solid waste of mine tailing,so it has been widely used in mines at home and abroad.But there are still scientific problems in the technology that can be further explored and solved.Tailing is the main raw material for fillings,and a large amount of heavy metal elements contained in it have not been completely removed.After filling to the stopes,due to the influence of the surrounding complex environment,there is a risk of re-leaching and migration,which poses a hidden danger to the safety of groundwater.Moreover,due to the complexity and particularity of the filling site,it is extremely difficult to govern.Therefore,the implementation of source cleaning control of fillers and the study of the migration and curing of heavy metal elements after tailing filling are of great significance for improving the harmless treatment of mine solid waste and the safety protection of groundwater environment.From the point of view of multi-disciplinary cross,based on a variety of different testing equipment,comprehensive theoretical analysis,indoor experiments and numerical simulations,this paper explores the re-leaching migration mechanism and predictive monitoring of heavy metal elements after filling and mining,develops a new environmental protection curing agent and improves the air blow-in method for filling,thus effectively realizing source control and bringing certain improvements to the safety of groundwater environment.The main conclusions and outcomes are as follows:(1)By carrying out a series of basic conditions experiments,such as the analysis of tailings mineral phase characteristics of different particle sizes,the analysis of heavy metal content in tailings,the analysis of acid production capacity,the analysis of influencing factors of heavy metal leaching after filling body soaking,the p H analysis of leaching solution,the conductivity analysis of leaching solution and the analysis of soaking leaching solution,the changes of different heavy metal concentrations and leaching amounts and the morphological distribution are obtained.It is proposed that heavy metal elements do have different degrees of leaching and are gypsum-type pore leaching theory.The key factors affecting the migration of heavy metals under this theory are analyzed,which provides a theoretical basis for the solidification and control of heavy metals in mine filling.(2)The leaching experiment of lead-zinc tailings filling body was carried out,and the leaching peaks and conditions of different heavy metal elements were obtained.The numerical simulation model of heavy metal element migration was constructed,and the migration rules of different heavy metal elements with p H value,time and temperature were revealed.(3)By carrying out a series of experiments on different combinations of carbon adsorbents,inorganic adsorbents,dissolved organic matter,p H adjusters and chitosan,which have the function of curing heavy metal elements,a set of optimal formulations was obtained.The new environment-friendly curing agent was compared with the combination;in the curing experiment of tailing filling material,the content of heavy metal elements decreased by 91.5%～96.5%,and a good curing experiment effect was achieved.(4)Through the analysis of the method of pre-mixing the curing agent of the filler slurry in the actual project,it is found that the dissociation phenomenon will occur in the pipeline transportation and affect the curing effect,and a method of air blowing into the mixing is proposed to make it mixed in the tube;Numerical simulation simulation with the feed inlet,air inlet,curing agent inlet and mixture outlet as the impact factors was carried out,and the air inlet angle of 30 °C and the curing agent inlet angle of 45 °C were the most suitable,and the curing effect and strength were also better,which provided a greater guarantee for the safety protection of groundwater environment.This thesis contains 81 figures,40 tables and 223 references. |
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