The remediation of groundwater environment in the post-mining area at in-situ leaching uranium mines has aroused widespread public concern. The long-term change of groundwater U concentration in the post-mining area is still unclear. Field investigation and numerical simulation methods were comprehensively used in this study, and a typical post-mining area of a “CO₂+O₂” in-situ leaching uranium mine in northern China was taken as the research object. On the basis of identifying the distribution characteristics of groundwater U in the post-mining area, the natural attenuation trend of U in groundwater at different times was quantitatively predicted, and the long-term change of U concentration was quantified. The results show that the concentration of U in the groundwater in the post-mining area is 0.273~5.24 mg/L, and the sampling points with U concentration lower than 2.5 mg/L accounted for 64%. The simulation results show that in the post-mining stage, the groundwater flow direction tend to the regional groundwater flow direction. When the natural attenuation process of U is not considered, U in groundwater migrate to 167 m downstream after 100 years of final mining, and the predicted migration distance is conservative. When the natural attenuation of U is considered, the migration distance of U is only 42 m after 100 years of final mining. The concentration of U in the groundwater in the mining area is reduced from the initial 2.5 mg/L to below 1.0 mg/L. Natural attenuation can reduce the migration distance and the concentration of groundwater U in the post-mining area, and the monitored natural attenuation (MNA) technology can be used as an alternative scheme for groundwater remediation at in-situ leaching uranium mines in the future.

According to the emission of pollutants during the operation of a reduction ilmenite (associated radioactive ore) project, the individual effective doses of different exposure routes on the surrounding public were predicted, and the contribution of different exposure routes were analyzed, to provide a reference for estimating the radiation dose of the project to the public. The results show that the maximum individual effective dose of the public members was 0.09 mSv/a, and the key exposure route was radon inhalation irradiation, which contributed 80.6%.The contribution share of ingestion exposure was 17.8%, the contribution of internal exposure due to radionuclides inhalation was 1.6%. The radiation impact of the project on the surrounding public meets the relevant standard requirements. Compared with radon inhalation exposure, the contribution of ingestion and inhalation exposure is smaller, but it cannot be ignored.

The uranium purification and conversion line will produce sodium diuranate precipitation and impurity residue. In order to recover the metallic uranium and reduce the waste mass, the uranium metal was recovered from these uranium-containing precipitates by nitric acid direct leaching and calcination-nitric acid leaching method. The content of impurity ions in the leaching solution were analyzed, and the main factors affecting the leaching rate of uranium were determined. Under the optimum conditions, the leaching rates of uranium by calcination-nitric acid leaching and direct nitric acid leaching are 98.14% and 96.11% respectively, and the mass of uranium-containing precipitates can be reduced by about 85%~90%.

Uranium conversion production mainly includes fluorination, hydrofluorination, and electrolytic fluorine production processes. Among which the electrolytic fluorine production process and fluorination process are the main factors affecting production capacity and continuous and stable operation. Based on the analysis of the principle and current situation of electrolytic fluorine production, the influences of hydrogen fluoride feeding, carbon plate operation and maintenance, electrolyte operation parameters, etc. on the operation of electrolytic fluorine production process were studied. The key points of control of a small amount of continuous hydrogen fluoride feeding and carbon plate current stability were analyzed. Measures such as optimization of hydrogen fluoride feeding mode, depolarization treatment process, carbon plate current monitoring, and regular electrolyte replacement were adopted. The operation of electrolytic fluorine production process is more stable and efficient.

A pretreatment process for uranium containing waste liquid was proposed to address the issues of nanofiltration membrane blockage and ion exchange resin poisoning in the treatment of uranium containing waste liquid. On the basis of determining the optimal process parameters for chemical precipitation and organic matter decomposition in the laboratory, engineering design and verification were carried out. The results show that after pretreatment, the turbidity of the waste liquid can be reduced to 16.25 NTU (removal rate of 98.74%), and COD can be reduced to 110.25 mg/L (removal rate of 87.13%). The waste liquid after pretreatment meets the water quality requirements of nanofiltration and ion exchange resin, and the pretreatment process effectively solves the problems in the treatment of uranium containing wastewater during uranium conversion.

Due to the influence of special mining technology in open-pit mines, shoveling equipment is prone to safety accidents during operation. Aiming at the problems of large inspection blind area and untimely response in the management of shoveling equipment in open-pit mine enterprises, a high slope and cross operation control scheme of shoveling equipment is proposed based on high precision positioning technology. The high slope operation control scheme combines terrain data, uses positioning technology, through on-site measurement and operation scheduling, real-time monitoring and alarm, on-site processing and record verification, real-time monitoring of the operation height of the shoveling equipment and judging whether it exceeds the safety range. The cross operation control scheme of shoveling equipment monitors the operation spacing in real time through the confirmation of operation spacing before operation, the audit of scheduling plan and the inspection of operation spacing. The proposed control scheme realizes the safe and fine management of the operation spacing and excavation height of the shoveling equipment, effectively reduces the risk of accidents in the process of open-pit mining, and improves the operation efficiency.

Some uranium mining and metallurgy soil ²²⁶Ra background value can not be determined, because of historical background and decommissioning knowledge in the early year. Based on analyzing the influencing factors of soil ²²⁶Ra value, natural factors determine soil ²²⁶Ra background value and human factors cause the soil ²²⁶Ra value to rise. It is difficult to investigate soil ²²⁶Ra background value at the contaminated site. In order to reduce the influence of human factors, monitoring plan, minimum sample size, and investigation statistical method are researched from surrounding soil of the site. Based on an example of the uranium mining and metallurgy decommissioning site, the feasibility of the supplemental investigation method is verified. The investigation statistical method can provide support for the engineering design and practice of uranium mining and metallurgy decommissioning.

Uranium tailings pond is a major safety and environmental hazard, and it is very important to ensure the safety and reliability under all conditions (including extreme disaster condition). Seismic condition is an important extraordinary working condition affecting the safety of uranium tailings ponds. Focused on the renovation project of a uranium tailings pond, the three-dimensional dynamic finite element method is applied to simulate and analyze seismic condition of uranium tailings pond for the first time. HS small model and UBC3D-PLM model constitutive model are selected to simulate and analyze a uranium tailings pond by dynamic finite element method. Seismic wave characteristic parameters and tailings dynamic characteristic parameters are taken into the finite element seismic dynamic simulation calculation, and the extreme conditions of rare earthquake are considered in the calculation, the displacement nephogram, acceleration nephogram, acceleration time history curve, potential liquefaction range and incremental displacement nephogram are obtained. The results show that the displacement of the dam body increases continuously under earthquake action, and the displacements of dam body decrease obviously after the implementation of the renovation project; there is no obvious change in the acceleration response caused by the renovation project; the liquefaction area is mainly distributed in the slope of the filled dam below the rock-filled platform, mainly in shallow layers (depth of about 3~6 m), and the improvement of liquefaction is limited. The stability safety factor of the dam body under rare earthquake increases from 0.975 to 1.061, the security of rare earthquake condition gets fundamental improvement.

The radioactivity of investigation, analysis and evaluation of liquid effluent such as mine water, tailings pond effluent and process wastewater produced by a uranium mine were conducted, the radioactivity level of liquid effluent and the pollution of accepted water were mastered, and the radiation impact of liquid effluent on local residents through various pollution channels was evaluated. The results show that the discharge concentrations of U, ²²⁶Ra, ²¹⁰Pb and ²¹⁰Po in the mine water, process wastewater and tailings pond effluent meet the limit requirements. The concentration of U in the middle and lower reaches of the accepted water body is slightly higher than the background level, and the concentrations of ²²⁶Ra, ²¹⁰Pb and ²¹⁰Po are among the normal background levels. The maximum personal dose caused by liquid effluent from uranium mine was 1.45×10^-3 mSv/a of 20 km, and the maximum collective effective dose was 2.35×10^-4 man·Sv/a of 20 km. The key resident group was the population group of WNW orientation in the >2~5 km area. The liquid effluent of uranium mining is discharged into the receiving water after reaching the standard, which has little impact on local radiation.

Against the background of growing global energy demand, the rate of extraction of various types of mineral resources is accelerating. However, with the increase of mining depth, the problem of high temperature and heat damage is gradually highlighted. The high temperature and heat damage not only affect the normal operation of various types of machinery and equipment, but also pose a serious threat to the safe production of the mine. The causes and effects of heat damage in mines were analyzed. At the same time, taking a hard rock uranium mine in the south of China as an example, through numerical simulation and other methods, the thermal and physical parameters of the surrounding rock of the mine, the geothermal field of the mine and the deep thermal environment were studied in depth, and on this basis, the existing problems of the mine were analysed, and the cooling technology was proposed.