Most ReadPart of the waste residue generated during the development and utilization of rare earth resources belongs to the associated radioactive solid waste. The safe and effective disposal of this type of waste residue is an urgent problem that needs to be solved in the current development of the rare earth industry. By the method of investigation and analysis, based on the types and sources of rare earths, statistics were conducted on the types, yields and radioactive nuclide activity levels of waste generated during the mining and selection process. Combined with the development plan of the rare earth industry, the stock and increment of rare earth waste in typical provinces(autonomous regions) were preliminarily estimated. And the current status and existing problems of the treatment and disposal of rare earth associated radioactive waste residue were sorted out. On this basis, a strategy for regional landfill disposal is proposed: it is recommended to implement a 7+x model nationwide, and to build rare earth waste residue warehouses in major rare earth provinces(autonomous regions), with reference to the model of Baotou in Inner Mongolia, to collect and dispose of rare earth associated radioactive waste residues in the provinces(autonomous regions). Based on the estimated amount and increment of waste residues, suggestions for the scale of rare earth waste residue disposal in each province(autonomous region) are provided.
Acidic wastewater generated by in-situ leaching uranium poses a serious threat to the groundwater environment. Aiming at the problems of long microbial remediation cycle, low survival rate and insufficient stability of electrokinetic remediation, a remediation method of microelectric field-coupled sulfate-reducing bacteria (SRB) was proposed. Through simulated wastewater remediation experiments, a three-chamber electrochemical device was constructed to explore the remediation mechanism and optimize the key parameters by combining the electromigration effect with the reduction function of SRB. The results show that the coupled remediation system significantly enhanced the uranium (VI) removal rate (more than 98%), and effectively reduced the concentrations of Ca, Mg, Al, Fe and other metal ions (removal rate>80%) and sulfate content (removal rate > 90%). Under the influence of an electric field, uranyl ions migrate to the cathode region, where they are predominantly reduced by S2- generated through the metabolic activity of sulfate-reducing bacteria (SRB) and subsequently co-precipitated. A minor fraction is reduced to U(IV) via electrode reactions. Experiments show that the different potential gradients can lead to different pH in the cathode chamber, which affects the remediation effect, with H+ leading to the escape of S2- under acidic conditions (pH<4) and the formation of soluble uranium complexes easily under alkaline conditions (pH>9); with a potential gradient of 0.2~0.4 V/cm, the balancing remediation efficiency, microbial activity and energy economy. This study provides a theoretical basis and technical support for the green and efficient remediation of acidic wastewater from uranium extraction by in-situ leaching technology.
The domestic and international situation of digital mine was introduced. Aiming at the problem of information island, taking an in-situ leaching uranium mine in Inner Mongolia as the research object, following the digital uranium mine architecture of CNUC, the digital integrated management and control platform was designed. By analyzing the technical architecture of systems of the mine, the data interface program was researched and developed independently, which is compatible with WebService, OPC and IEC104 standards. Using the data interface program, the values in the database of OA, DCS and electric power system were got and centralized managed. By the digital integrated management and control platform, the digitalization level of in-situ leaching uranium mine was greatly improved.
In order to improve the efficiency of uranium extraction by the moving bed adsorption tower, Fluent and Edem software were used to simulate the process of uranium extraction by the moving bed adsorption tower. By adjusting the inlet flow rate, and observing the movement of resin particles, the distribution state and the settling of saturated resin in the moving bed adsorption tower, the optimal inlet flow rate was analyzed and obtained. The accuracy of the simulation results was verified by building an experimental platform, and the comparative analysis of the experimental data with the numerical simulation results confirmed the consistency of the two conclusions, thus verifying the accuracy and applicability of the model. The results show that the optimal inlet flow rate is 4 m3/h. At this flow rate, the extraction efficiency of uranium ions is maximized, which provides an important design parameter for the future design of moving bed adsorption tower.
Radioactive decontamination is an important technical means to ensure the sustainable development of nuclear industry. Radioactive decontamination is not only related to the comprehensive cost of operating and managing facilities such as nuclear power plants, and the development of radioactive mineral resources, but also related to personnel safety and social environmental safety, and should be given sufficient attention. On the basis of summarizing various radioactive decontamination technologies commonly used in the process of decommissioning and maintenance of domestic nuclear facilities, the application conditions, advantages and disadvantages of physical decontamination, chemical decontamination, electro oxidation decontamination, microbial decontamination and smelting decontamination technologies are analyzed, and the technical pain points and development direction of decontamination technology is proposed.
Low-permeability sandstone uranium mine, with its poor permeability and high injection difficulty, has brought great challenges to the traditional in-situ leaching mining technology. In view of the current low permeability uranium mining problems, this paper discussed the innovative application of high-pressure liquid injection technology in the field of in-situ leaching mining and its effectiveness. Comparative tests were conducted to verify the effectiveness of high-pressure liquid injection technology, pumping liquid volume test and tracer test were carried out under atmospheric pressure and high-pressure conditions respectively. The test results show that compared with the atmospheric pressure condition, the high-pressure liquid injection technology increases the injection flow by 6.4 times, the pumping flow by 1.05 times and the seepage velocity by 33 times. High-pressure liquid injection technology can effectively solve the leachants injection problem in low-permeability sandstone uranium mine, and the technology is convenient to implement in the mine site.
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.
With the development of uranium mining, uranium mining technology has rapidly advanced, but various challenges have emerged. In the process of in-situ leaching of uranium, there is often a phenomenon of decreased pumping and injection volume, which seriously affects the efficiency of uranium leaching. In response to the problem of decreased pumping and injection volume, physical, chemical, and combined well cleaning techniques have been carried out. The washing technology can solve the blockage around the wells, but its washing effect lasts for a short time and has a small impact radius, which cannot fundamentally solve the problem of decreased flow rate. The liquid flow cavitation technology is widely used in petroleum extraction, which can effectively increase the production of pumping wells and reduce the pressure of injection wells. However, it has not been involved in the in-situ of uranium process. In this paper, by comparing the difference between uranium leaching technology and petroleum technology, the cavitation device is optimized, and the drilling wellhead device is improved in the ground test, and then the liquid flow cavitation test is carried out. During the test, the operation displacement reached 2 m3/min and the pressure was about 21 MPa, which verified the feasibility of liquid flow cavitation technology in in-situ of uranium, and provided a new idea for improving the permeability of uranium mine.
In order to cope with the rising cost of truck haulage due to the rising price of diesel fuel, this thesis focuses on the existing trolley line in the Husab uranium mine in Namibia, the “Field two-time refueling method” was designed to measure the oil consumption and power consumption on the slope under the condition of pure oil and the auxiliary condition of trolley line. By disassembling the cost and benefit factors related to the operation of trolley line, this thesis put forward the reasonable value method of each factor, constructed the economic analysis frame and completed the economic feasibility calculation of the operation of trolley line. The results show that the truck with 330 t rated load in Husab is driven up the slope by trolley line at a speed of 550 m, consumes 62.65 kW·h of electricity, saves 11.25 liters of fuel consumption than the truck with pure oil, and the climbing speed is 24 km/h, which is twice as fast as that of the truck with pure oil. According to the calculation, the total dynamic income of the test section in Husab is 70.47 million N$\$$ during its whole life, and the static payback period of the technical renovation investment is less than 2 years. The static payback period of the investment is less than 5 years considering the construction cost. The investment sensitivity analysis shows that the project is most sensitive to the oil price, followed by electricity price and operating cost, and the project is least sensitive to the capital input, but even when the oil price is reduced by 50%, the dynamic income of the whole life of the project can still reach 22.09 million N$\$$, indicating that the project has strong risk resistance.
With the global growth in demand for clean energy, the development of uranium ore resources and its environmental impact increasingly have raised concerns. Uranium tailings (slag), as the main by-product of uranium mining and processing, are an urgent environmental concern requiring safe disposal. This study systematically summarized the research progress of uranium tailings backfilling and safe disposal technology, and focuses on the paste filling process optimization and nano material solidification mechanism, in order to provide theoretical support for the green development of uranium resources and the safe disposal of radioactive waste.