Uranium Tailings Research Articles

Application of advanced spectral-ratio radon background correction in the UAV-borne gamma-ray spectrometry

The influence of the atmospheric radon background on the airborne gamma spectrum can seriously affect researchers’ judgement of ground radiation information. However, due to load and endurance, unmanned aerial vehicle (UAV)-borne gamma-ray spectrometry is difficulty installing upward-looking detectors to monitor atmospheric radon background. In this paper, an advanced spectral-ratio method was used to correct the atmospheric radon background for a UAV-borne gamma-ray spectrometry in Inner Mongolia, China. By correcting atmospheric radon background, the ratio of the average count rate of U window in the anomalous radon zone (S5) to that in other survey zone decreased from 1.91 to 1.03, and the average uranium content in S5 decreased from 4.65 mg/kg to 3.37 mg/kg. The results show that the advanced spectral-ratio method efficiently eliminated the influence of the atmospheric radon background on the UAV-borne gamma-ray spectrometry to accurately obtain ground radiation information in uranium exploration. It can also be used for uranium tailings monitoring, and environmental radiation background surveys.

State of Red Blood Indicators in Animals With Uranium Load

Research relevance: the study of uranium load on the state of red blood is relevant in connection with the effect on the bone marrow and changes in it. Research objectives: to study conditions of red blood indicators in animals with a uranium load. Research materials and methods: experiments were carried out on rabbits of the chinchilla breed, weighing 1.7-2 kg. The animals were divided into 4 groups depending on the altitude above sea level and on the receipt of uranium from food. To obtain posthemorrhagic anemia, a single bloodletting was performed in the amount of 3% of the animal’s weight. Research results: in animals that were in mid-mountain conditions, stimulation of the red and white sprouts of the bone marrow and a pronounced regenerative reaction to the preliminary administration of uranium radionuclide and blood loss were observed. Conclusions: in animals kept in mid-mountain conditions near the uranium tailing dump, the regenerative potential of red and white bone marrow sprouts was reduced, which was confirmed by the absence of regenerative, regenerative processes after blood loss.

Fuzzy Optimal Control of Radon Exhalation in Uranium Tailings under Double-Layer Coverage

The use of covering material is an important measure to control the radon migration of uranium tailings. Radon diffusion and migration are affected by cover layer parameters, such as diffusion coefficient, overburden thickness, particle size, and ore body width. The radon reduction effect of single-layer mulching is often less than that of double-layer, and the material parameters of the cover layer are uncertain; however, they can be explained by a fuzzy dynamic equation. Firstly, the radon exhalation model is constructed with the radon percolation diffusion and migration method in a double-layer covering. Secondly, a fuzzy target of radon exhalation and a fuzzy constraint model are constructed subject to the total cost and thickness of covering material by a triangular membership function. Lastly, the models are aimed at solving the corresponding extreme value interval of the fuzzy target of radon exhalation by immune genetic algorithm, to reconstruct the fuzzy target, fuzzy constraint, and fuzzy aggregation function, where, ultimately, the optimal radon control decision can be obtained by swarm intelligence algorithm subject to different levels between possibility and importance. An example demonstrates a database of optimal decision-making schemes for double-layer coverage, and flexible management of radioactive pollutants is realized.

Fuzzy optimal control of multilayer coverage based on radon exhalation dynamics in uranium tailings

Radon exhalation from uranium tailings has seriously affected environmental safety and human health. Many uncertain parameters, such as diffusion coefficient, porosity, percolation rate, material particle size, etc., are related to the diffusion and migration of radon. Moreover, cover materials, cover layers, and cover thickness are the main instruments to control radon exhalation, and the radon reduction effect of single-layer mulching is often inferior to that of the multilayer. Hence, achieving radon control with multilayer coverage under uncertain environment is an urgent problem that must be solved in the area of nuclear safety and radiation environment. In an attempt to address the issue, a dynamic model of radon exhalation with multilayer coverage is constructed using radon percolation-diffusion migration equation, and triangular membership functions inscribe the model parameters; the objective functions of the left and right equations of the model are constructed, and their extreme value intervals are obtained using immunogenetic algorithm. Then, subject to the total cost and thickness of multilayer covering materials, the fuzzy objective and constraint models of radon exhalation are constructed, and the fuzzy aggregation function is reconstructed according to the importance of the fuzzy objective and constraint models, where ultimately, the optimal radon control decision by swarm intelligence algorithm under different possibility levels and importance conditions can be obtained. An example is then used to validate the effectiveness of the radon exhalation model, and to demonstrate that fuzzy optimization provides a database of decision-making schemes regarding multilayer coverage, and guidance for optimal control and flexible construction management.

Research on safety early warning of uranium tailings dam based on abnormal radioactive indexes of water leachate

The radioactive index value of the leachate of the uranium tailings dam is affected by the internal damage of the dam. Therefore, a way of using the deviation of the radioactive index concentration in the leachate to warn the instability of the dam is innovatively proposed in this paper. Firstly, the SSA-BP algorithm is used to predict and analyze the five groups of parameters U, Ra, ∑ α, ∑ β and Rn. Then, the deviation between the actual value and the predicted value is computed. Finally, an early warning is given based on the entropy weight extension decision-making model. The model is verified by the leachate environment monitoring data of a uranium tailings dam in southern China from 2016 to 2020, which shows that the model can effectively caution of the instability of the uranium tailings dam and provides a reference for the subsequent decommissioning management.

Experimental study on dam damage and radon precipitation in uranium tailing ponds based on impact loading effects

Experimental study on dam damage and radon precipitation in uranium tailing ponds based on impact loading effects

“Two-in-one” dual-function luminescent MOF hydrogel for onsite ultra-sensitive detection and efficient enrichment of radioactive uranium in water

In consideration of the severe hazards of radioactive uranium pollution and the growing demand of uranium resources, the novel sensor/adsorbent composite was creatively developed to integrate the dual functions for on-site detection of uranium contamination and efficient recovery of uranium resources. By hybridizing the luminescent 3D terbium (III) metal–organic framework (Tb–MOF) with sodium alginate (SA) gel using terbium (III) as cross-linker, the Tb-MOF/Tb-AG was fabricated with multi-luminescence centers and sufficient binding sites for uranium. Notably, the ultra-high sensitivity with detection limit as low as 1.2 ppt was achieved, which was 4 orders of magnitude lower than the uranium contamination standard in drinking water (USEPA) and even comparable to the sensitivity of the ICP-MS. Furthermore, the very wide quantification range (1.0 ×10−9-5.0 ×10−4 mol/L), remarkable adsorption capacity (549.0 mg/g) and outstanding anti-interference ability have been achieved without sophisticated sample preparation procedures. Applied in complex natural water samples from Uranium Tailings and the Pearl River, this method has shown good detection accuracy. The ultra high sensitivity and great adsorption capacity for uranium could be ascribed to the synergistic coordination, hydrogen bonding and ion exchange between uranium and Tb-MOF/Tb-AG. The mechanisms were explored by infrared spectroscopy, batch experiments, X-ray photoelectron studies and energy dispersive spectroscopic studies. In addition, the Tb-MOF/Tb-AG can be reused for uranium adsorption.

Influence of fiber type and amount of reinforcing fibers on radon exhalation in uranium tailings’ overburden under high temperature environment

Influence of fiber type and amount of reinforcing fibers on radon exhalation in uranium tailings’ overburden under high temperature environment

Classification and prediction of radon stable zone in uranium tailings pond: a case study from uranium tailings pond in sothern China

Classification and prediction of radon stable zone in uranium tailings pond: a case study from uranium tailings pond in sothern China

Effect of Natural Zeolite on Pore Structure of Cemented Uranium Tailings Backfill

The use of some environmental functional minerals as backfill-modified materials may improve the leaching resistance of cemented uranium tailings backfill created from alkali-activated slag (CUTB), but these materials may participate in the hydration reaction of the cementitious materials, which could have a certain impact on the pore structure of the CUTB, thus affecting its mechanical properties and leaching resistance. In this paper, natural zeolite is selected as the backfill-modified material, and it is added to alkali-activated slag paste (AASP) and CUTB in cementitious material proportions of 4%, 8%, 12%, and 16% to prepare AASP mixtures and CUTB mixtures containing environmental functional minerals. After the addition of natural zeolite, the porosity of the CUTB generally increases, but when the content is 4%, the porosity decreases to 22.30%. The uniaxial compressive strength (UCS) of the CUTB generally decreases, but the decrease is the smallest when the content is 4%, and the UCS is 12.37 MPa. The addition of natural zeolite mainly reduces the number of fine pores in the CUTB, but the pores with relaxation times T2 of greater than 10 ms account for about 10% of the total pores, and there are a certain number of large pores in the CUTB. The main product of alkali-activated slag is calcium (alumino)silicate hydrate (C-(A)-S-H gel). When natural zeolite is added, the hydration products develop towards denser products with a high degree of polymerization and the formation of low polymerization products is reduced. This affects the internal fracture pores of the hydration products and the interface pores of the CUTB, has an irregular effect on the pore characteristics of the CUTB, and influences the UCS.

Feasibility of uranium tailings for cemented backfill and its environmental effects

Surface storage of uranium tailings presents a potential threat to the environment and human health. Cemented backfill can be used to dispose of tailings and control the ground pressure of stopes, providing a new approach for the in-situ seal of heap leaching uranium tailings (HLUTs). The backfilling characteristics of HLUTs were investigated by analyzing the release mechanism of sulfuric acid in HLUTs, the rheological properties of backfill slurry, as well as the strength development and microscopic characteristics of cemented HLUTs backfill (CUTB). The environmental effects of the CUTB were also assessed, and a novel filling process was presented. The results showed that the release rate of sulfuric acid in HLUTs decreased logarithmically, and the content of free sulfuric acid in coarse particles surfaces and ultrafine particles is high, which can be pretreated with 0.1 % quicklime. Slurry with a mass concentration of 74 % ~ 76 % can satisfy the requirements for pipeline transport. The CUTB's strength raised quickly in the former 90d, then decreased to a different extent after 150d, adding 50 wt% FA can enhance its later stability. The leaching level of uranium in CUTB cured for 28d is below the stipulated limit (GB 23727–2009) under different test conditions, having little impact on the underground environment. The hydration products of CUTB are mainly gypsum and C-S-H gel. Gypsum causes later degradation in strength; numerous C-S-H gels generated by the secondary hydration of FA enhance the resistance to sulfate corrosion. These findings have demonstrated that cemented backfill has a high inclusion ratio and low cost for HLUTs, which is of great significance to the HLUTs minimization and the safety of mining while promoting the environmentally friendly development of uranium mines and mills.

Facile synthesis of calcium peroxide modified mesoporous silica for enhanced uranium extraction from uranium tailings leachate

Herein, calcium peroxide modified mesoporous silica (CPMS) was successfully synthesized by a facile strategy and used for simultaneous adsorption and immobilization of U(VI) from uranium-containing wastewater. The batch uranium adsorption experiments reveal excellent adsorption performance of CPMS over a wide pH value. In comparison to calcium peroxide and mesoporous silica, the CPMS showed a great improvement in the removal capacity of uranium. As well, the pseudo-second-order model and Langmuir isotherm model provided a well description of adsorption kinetics and isotherm, respectively, which suggested the monolayer chemisorption governed the adsorption of CPMS for U(VI). In addition, the Langmuir isotherm model calculated the maximum adsorption capacity of CPMS for U(VI) up to 613.50 mg/g. Based on mechanistic studies of XPS, FT-IR, TEM and XRD, U(VI) is predominantly removed through synergistic adsorption of U(VI) by mesoporous silicon and immobilization of U(VI) by calcium peroxide as (UO2)O2•2 H2O (metastudtite). Furthermore, the efficient removal ability of CPMS for U(VI) in uranium tailings leachate was confirmed by column test, the U(VI) concentration of uranium tailings leachate can be reduced from 180.4 μg/L to 2.3 μg/L in 1895.2-bed volumes, which was well lower than the standard limit of WHO for U(VI) concentration in drinking water. This research provides a feasible approach and new idea for the efficient treatment of radioactive wastewater.

Solidification of uranium tailings using alkali-activated slag mixed with natural zeolite

Cemented uranium tailings backfill created from alkali-activated slag (CUTB) is an effective method of disposing of uranium tailings. Using some environmental functional minerals with ion exchange, adsorption, and solidification abilities as backfill modified materials may improve the leaching resistance of the CUTB. Natural zeolite, which has good ion exchange and adsorption characteristics, is selected as the backfill modified material, and it is added to the backfill materials with cementitious material proportions of 4%, 8%, 12%, and 16% to prepare CUTB mixtures with environmental functional minerals. After the addition of natural zeolite, the uniaxial compressive strength (UCS) of the CUTB decreases, but the leaching resistance of the CUTB increases. When the natural zeolite content is 12%, the UCS reaches the minimum value of 8.95 MPa, and the concentration of uranium in the leaching solution is 0.28–8.07 μg/L, the leaching rate R42 is 9.61 × 10−7 cm/d, and cumulative leaching fraction P42 is 8.53 × 10−4 cm, which shows that the alkali-activated slag cementitious material has a good curing effect on the CUTB, and the addition of environmental functional minerals helps to further improve the leaching resistance of the CUTB, but it reduces the UCS to an extent.

Release behavior of uranium from a uranium tailing in Jiangxi Province

In this study, nine soils at different depths in a decommissioned uranium tailing pond in Jiangxi Province are selected as the research objects to study their mineralogical properties and reveal the leaching law of radioactive element uranium under natural rainfall conditions. The research results are as follows: 1) The distribution characteristics of uranium are affected by the mineral composition, microscopic morphology and physical and chemical properties of uranium tailings. 2) In static leaching experiments, acidic solutions, small particles, and high solid-to-liquid ratios all promote the release of uranium. 3) In the dynamic leaching experiment, the lower the pH of simulated rainfall, the more uranium is released. According to Fick theory, the migration mechanism of uranium is mainly surface dissolution, and the release of uranium is related to the content of migratory uranium.

The variation of uranium tailings impoundment cover fissures and radon exhalation under the continuous heat and insolation conditions

The variation of uranium tailings impoundment cover fissures and radon exhalation under the continuous heat and insolation conditions

Experimental study on radon exhalation and dynamic response of uranium tailings dam under earthquake

Experimental study on radon exhalation and dynamic response of uranium tailings dam under earthquake

Immobilization of uranium tailings by phosphoric acid-based geopolymer with optimization of machine learning

Immobilization of uranium tailings by phosphoric acid-based geopolymer with optimization of machine learning

Enhancement effects of weak electric field on uranium and manganese removal from leachate of uranium tailings impoundment by artificial wetland

Artificial wetlands (AWs) planted with Acorus Calamus L. and coupled with weak electric field (WEF) were constructed to investigate the effects of flow direction, hydraulic retention time (HRT), and WEF intensities on the removal of uranium and manganese from leachate of uranium tailings impoundment (LUTI), the distribution characteristics of the uranium and manganese in the AWs, and the growth and physiological responses of the plants in them. The results showed that the optimized removal rates of uranium and manganese from LUTI were observed to be 97.03% and 99.72%, respectively, in the upwelling AW planted with Acorus Calamus L. and coupled with WEF intensity of 0.3 V/cm when the HRT was 72 h. Compared with the group without WEF, the bioaccumulations of uranium and manganese by Acorus Calamus L were increased by 169.23% and 522.91%, respectively, the adsorption capacities of biofilms toward uranium and manganese were increased by 7.38% and 48.90%, respectively, the content of uranium in the substrates was decreased by 10.76%, while the manganese concentration had no significant difference, and the contents of uranium and manganese in the salt scale deposited on the cathode surface reached 51.20 and 653.11 mg/kg, respectively, when the WEF intensity was 0.3 V/cm in the AW. The applied WEF increased the activity of superoxide dismutase (SOD) and the content of glutathione (GSH), and reduced the content of malondialdehyde (MDA) in the leaves of Acorus Calamus L, so as to alleviate the stress of uranium and manganese on wetland plants in the AW. Therefore, the AW has potential application in the removal of uranium and manganese from LUTI.

Evaluation of cadaveric bone marrow cells of children from different regions of Kyrgyzstan

Introduction and Aim: The bone marrow is responsible for the supply of oxygen and restores the cells that form the blood of a tissue. The objective is to study the cadaveric bone marrow cells from dead children of different regions of Kyrgyzstan. Materials and Methods: Bone marrow examination was performed on 38 cadavers (Bishkek–11, Kara-Balta–9, Cholpon-Ata–10, and Naryn–8) of children dead due to causes unrelated to immunodeficiency. The cadaveric bone marrow cells from dead children were collected within a day after death. Results: Studies of cadaveric bone marrow cells from dead children in Kara-Balta showed an increase in basophils, eosinophils, lymphocytes, leukoerythroblastosis, and a decrease in myelocytes. Erythroid growth according to the normoblast hematopoiesis was slightly decreased. Megakaryocytes were single or absent (no function) and contained small number of platelets. Conclusion: Cadaveric bone marrow cells taken from dead children who lived near the uranium tailings dump of Kara-Balta, demonstrated an anomaly with the hematopoietic function of the bone marrow, the state of the stroma, the ratio of hematopoietic and adipose tissue, cellular composition, different pathological processes as indicated by myelocytes in comparison to dead children from other regions (Bishkek, Cholpon-Ata, and Naryn).

Risk assessment management and emergency plan for uranium tailings pond

The safety of uranium tailings pond is closely related to social stability and economic development, so it is necessary to improve the emergency management of uranium tailings pond to ensure its safety by adjusting the emergency plan. The Interpretive Structural Model (ISM) is used to analyze the structural relationship between the main risk factors leading to the occurrence of emergencies. The results show that attention should be paid to the risk factors originating from humans and infrastructures, and effective management measures should be adopted in the process of emergency management, for example, people build tighter employee access system, clarify the responsibilities of employees at all levels, and improve monitoring and organizational means. According to the results of ISM analysis, a structural risk control system can be constructed, and a defensive barrier that can effectively block the risk coupling transmission can be designed to prevent the risk from being transformed into an event. For other risks, system resilience management should be strengthened to respond to risks. The process is set as emergency response and accident response. Different management objects use different management methods to make emergency management work efficiently.