Uranium serves as the "grain" for the nuclear industry and constitutes a strategic resource essential for both national and energy security. Currently, the global uranium supply relies primarily on conventional extraction technologies, such as open-pit and underground mining combined with heap leaching, as well as in-situ leaching. These well-established technologies, characterized by high maturity and relatively low costs, represent the primary methods for uranium extraction at present. However, conventional uranium mining is facing mounting challenges, including the gradual depletion of high-grade resources and increasing difficulty in developing low-grade deposits. Therefore, it has become imperative to expand uranium extraction technologies toward unconventional resources. Unconventional uranium resource extraction technologies aim to recover uranium from low-grade polymetallic associated ores, seawater, and salt lake brines. Although various technical pathways are still in the research and development stage, they have demonstrated significant potential for broadening resource boundaries and achieving comprehensive resource utilization. This paper systematically reviews the fundamental principles, research progress, and future development trends of uranium extraction technologies, aiming to provide a reference for technological innovation and strategic direction in the field of uranium extraction.

Niobium and tantalum are strategic rare metals, and their efficient separation and purification are crucial for the sustainable utilization of resources. The resource characteristics and industrial demand of niobium and tantalum are summarized, and the research progress of solvent extraction method in niobium and tantalum separation is focused on. The formation mechanism of niobium-tantalum fluoride complexes and their coordination behavior with extractants are discussed. The extraction performance of ketones, esters, amines, crown ethers, organic phosphonates, and novel functionalized ionic liquid extractants is summarized, and current challenges and development trends are outlined.

In order to improve the leaching efficiency of chalcopyrite, on the basis of the conventional heating leaching system, the pulse microbubble method is introduced to reduce the influence of the sulfide layer by improving the mass transfer efficiency in the leaching process. The kinetics is discussed, the morphology of the leaching residue is analyzed, and the mechanism of pulse microbubble-enhanced leaching is revealed. The results show that the pulsed microbubbles can significantly improve the leaching rate of chalcopyrite, and the increase rate rises with the decrease in microbubble size. Under the optimum conditions of conventional leaching, the copper leaching rate is only 53.6%, while under the same conditions, the copper leaching rate can increase to 62.48% and 80.40% when the pore size of the orifice plate is 94 and 75 μm, respectively. The SEM test results show that the pulsed microbubbles can effectively improve the aggregation degree and coverage area of the sulfide layer on the surface of chalcopyrite. The mechanism may be that the pulsed microbubbles have higher mass transfer efficiency and can accelerate the reaction rate. At the same time, the local high temperature and high pressure released during the burst can weaken the passivation of the sulfide layer during the leaching process, thereby improving the leaching effect of chalcopyrite.

In order to expand the development boundary of overseas low-grade copper-cobalt oxide ore, the leaching of copper and cobalt with sulfuric acid was studied for the Colluvium of MSESA orebody in Congo (DRC). The effects of various key factors on the leaching were investigated, and the economy of the process was evaluated and analyzed. The results show that the contents of copper and cobalt in the colluvium are 1.1% and 0.15%, respectively. The oxidation rate of the ore is high and the argillization is serious. The main gangue phases are talc, biotite, quartz, chlorite and dolomite. Copper mainly exists in the form of oxide, and cobalt exists in the form of cobaltite, cobalt carbonate and cobalt in gangue. Under the conditions of grinding fineness of 70% (－200 mesh), sulfuric acid addition of 7%, leaching temperature of 25 ℃, leaching time of 2 h, liquid volume to solid mass ratio of 2.5∶1, and stirring rate of 300 r/min, the leaching rates of copper and cobalt are 88.72% and 71.75%, respectively, and the acid consumption is 5.43 t/tCu. Cathode copper is produced by leaching－extraction－electrowinning process. The production cost is $3 450.618/tCu, accounting for only 36.322% of the sales price of cathode copper, which has good economic benefits.

The selective recovery of lithium from retired ternary lithium batteries by carbothermal reduction－two-step leaching (water leaching-acid leaching) process was studied. The effects of carbothermal reduction and leaching test conditions on lithium leaching were investigated. The results show that the cathode powder and activated carbon are compounded according to the ratio of carbon mass fraction of 27%. After roasting at 600 ℃ for 90 min, the roasting product is mixed with ultrapure water according to the solid-liquid mass volume ratio of 1/18, and then 83% of the theoretical amount of sulfuric acid is added dropwise. After leaching at 65 ℃ for 20 min, the lithium leaching rate is more than 98%, while the leaching rates of nickel, cobalt and manganese are less than 5%, and the lithium recovery effect is better.

Recycling spent LiFePO₄ batteries is crucial for mitigating resource shortages and lowering environmental pollution. Leaching lithium from the spent LiFePO₄ batteries using succinic acid-hydrogen peroxide system was investigated. The effects of succinic acid concentration, hydrogen peroxide volume fraction, solid mass to liquid volume ratio, leaching temperature and time on lithium leaching rate were examined. The leaching mechanism was further clarified through kinetic analysis and SEM. The results indicate that under the optimal leaching conditions of succinic acid of 0.8 mol/L, hydrogen peroxide of 2%, solid mass to liquid volume ratio of 4 mg/1 mL, leaching temperature of 80 ℃, and time of 40 min, the conditions, lithium leaching rate is more than 98%, while iron leaching rate is less than 2%. Kinetic analysis reveals that the leaching process is primarily diffusion-controlled. Overall, these findings demonstrate that the synergistic succinic acid-hydrogen peroxide system offers high efficiency and sustainability in LiFePO₄ leaching, providing a feasible route for the green recycling of spent LiFePO₄ batteries.

Germanium in lignite ash mainly exists in Ge—O—Si bonded state, vitreous encapsulated state and iron oxide adsorbed state. The traditional acid leaching method is difficult to destroy the structure of highly stable Ge—O—Si bond and dense encapsulated vitreous body, resulting in less than 50% germanium leaching rate and low resource recovery rate. Based on the comparison of three process routes of lignite ash direct acid leaching, roasting－acid leaching, alkali fusion activation－acid leaching and two leaching systems of sulfuric acid or hydrochloric acid, the process route of extracting germanium from lignite ash by high temperature alkali fusion pretreatment－acid leaching process was proposed and studied. The effects of alkali fusion temperature, mass ratio of material to alkali and alkali fusion holding time on the leaching rate of germanium in lignite ash were investigated, and the leaching effects of sulfuric acid and hydrochloric acid on alkali fusion activation products were compared. The results show that the leaching performance of germanium can be significantly improved by breaking the Ge—O—Si bond by alkali fusion and converting insoluble silicate into soluble sodium salt, and then the efficient leaching of germanium can be realized by conventional acid leaching. Under the conditions of alkali fusion temperature of 600 ℃, mass ratio of material to alkali of 1/1.8 and alkali fusion time of 1 h, the main spherical structure of lignite ash is destroyed, and the encapsulated substances in alkali fusion products are released. When hydrochloric acid or sulfuric acid leaching systems are used, the leaching rates of germanium are 86.37% and 93.98%, respectively. This technology can realize the efficient leaching of germanium in lignite ash, which can provide a new technical approach for the resource utilization of high-silicon germanium-containing secondary materials and the efficient recovery of strategic metal germanium.

In-situ uranium leaching was investigated using native acidophilic ferrous sulfate oxidizing bacillus (Acidithiobacillus ferrooxidans, L24f) and acidophilic sulfur oxidizing bacillus (Acidithiobacillus thiooxidans, L24s) from sandstone-type uranium ore. In combination with physicochemical parameter monitoring and characterization techniques such as SEM-EDS and XRD, the synergistic leaching mechanism was elucidated to determine the effectiveness of synergistic leaching and the optimal inoculation ratio. The results show that L24f and L24s strains have a significant synergistic uranium leaching effect, and the inoculation volume ratio of 1∶1 is the optimal ratio. Under this condition, the final uranium leaching rate of sandstone-type uranium ore is 86.5%, which is 7.5 percentage points higher than that of a single L24f pure bacteria system. The mixed bacterial consortium system can maintain the low pH environment of the system through complementary metabolic functions, effectively inhibit the formation of jarosite passivation layer, and significantly improve the leaching rate of uranium.

Uneven and discontinuous calcareous sandstone and mudstone interlayers are distributed in the mining area of Bayin Qinggeli uranium mine. In order to explore the influence of low-permeability interlayers on uranium leaching effect, a three-dimensional unstructured grid lithology model of ore-bearing aquifer was constructed based on borehole data in the test mining area, and the flow field and solute transport process of in-situ leaching uranium under different extraction-injection methods were simulated. By introducing a matrix calculation method based on the actual extraction-injection flow of group wells, the solute mass ratio and natural groundwater content were quantitatively compared and analyzed. The results show that compared with the original extraction-injection method, after the extraction-injection methods of SYC-1 and SYZ-1 wells are interchanged, the range of groundwater drawdown funnel is reduced, the capture ability of pumping wells to leaching solution is significantly improved, the mass ratio of extracted and injected solute is increased by 1.7 times, the natural groundwater content in pumping volume is reduced by 29.4%, the hydraulic connection between extraction-injection wells is stronger, and the leaching effect is better than that of the original extraction-injection method. Calcareous sandstone and mudstone interlayers significantly hinder the hydraulic connection between extraction-injection wells, resulting in significantly different leaching effects of different extraction-injection methods.

Zinc zeolite imidazole framework material (ZIF-8) is suitable for uranium adsorption due to its high specific surface area and abundant active sites. Aiming at the problems of long time and large consumption of organic solvents in the synthesis of ZIF-8 by traditional solvent method, ZIF-8 was rapidly synthesized by green and efficient mechanochemical method using zinc hydroxide and 2-methylimidazole as raw materials and used for uranium adsorption. The results show that the ZIF-8 prepared by mechanochemical method has good crystallinity, rhombic dodecahedron morphology, specific surface area of 1 642 m²/g, and rich surface defects and active sites on the surface. Under suitable conditions, the removal rate of uranium by ZIF-8 is more than 99.99%, the maximum adsorption capacity is 476 mg/g, and the adsorption can reach equilibrium within 20 min. The process is a single-layer chemical adsorption mechanism. The cost analysis results show that the synthesis efficiency of mechanochemical method is 16 times higher than that of traditional solvent method, and former's theoretical material cost per gram of uranium is only 3.5% of that of the latter. The mechanism analysis results show that the high specific surface area of the material and the synergistic effect of hydroxyl groups and imidazole nitrogen atoms are the key to the efficient adsorption of U(Ⅵ). ZIF-8 prepared by rapid mechanochemical method has good performance and has certain application potential in the field of uranium adsorption.

Aiming at the issues of prolonged leaching cycles and low efficiency in the existing heap leaching process at a uranium mine, an on-site industrial optimization heap leaching test was conducted on fine-grained ore. The optimal process conditions and key parameters of key stages, including ore crushing, wet granulation, and spray heap leaching, on uranium extraction were systematically investigated. The results demonstrate that the closed-circuit crushing and screening process effectively regulates the feed particle size to below 4 mm. Excellent pelletisation is achieved under the conditions of drum granulator speed of 30 r/min and ore feed rate of 40 t/h. Heap leaching tests confirm that this optimised process successfully reduces the uranium from 0.158% to 0.011 5%, achieving the uranium leaching rate of 92.72%, under the conditions of liquid volume to solid mass ratio of 4.86∶1, sulfuric acid consumption of 8.56%, and spray cycle of 78 d.

For treatment of uranium-containing wastewater, a co-culture system comprising Pseudomonas cepacia and anaerobic granular sludge (PC-AnGS) was constructed, and its performance and underlying mechanisms for removing of U(Ⅵ) was systematically investigated. The results show that the removal rate of U(Ⅵ) is as high as 94.2% under the optimal conditions of initial pH=7.0, PC-AnGS dosage of 2 g/L, contact time of 10 h and temperature of 35 ℃. The results of adsorption kinetics and isotherm analysis indicate that the adsorption process conforms to the pseudo-second-order kinetics and Langmuir isothermal adsorption model, and is dominated by monolayer chemical adsorption. The control test and SEM, FT-IR, XPS and other characterization results confirm that the PC-AnGS system uses the synergistic effect of the two components to adsorb and fix U(Ⅵ) mainly through the rich functional groups on the surface, and then partial mineralization and reduction. The research results can provide certain technical reference for the bioremediation of uranium-containing wastewater.

In response to the problems of limited adsorption capacity and susceptibility to interference from ions in the existing seawater uranium extraction hydrogel materials, a novel composite hydrogel adsorbent, chitosan/imidazole crosslinked polyamidoxime hydrogel (CS/PAO@IA) was developed. This material is based on chitosan as the three-dimensional network framework and imidazole-2-formaldehyde as the chemical crosslinking agent. Through hydrogen bond effects and Schiff base reactions, a flexible and strong three-dimensional network was constructed. The correctness of the synthesized material structure was verified by systematic characterization methods, and the microscopic morphology of the material surface and the composition and valence state changes of the elements on the surface after uranium adsorption were analyzed. The uranium adsorption performance and ion selectivity of the material were tested separately. The results show that the material has good adsorption selectivity for uranyl ions in the spiked seawater with uranium mass concentration of 3.3 mg/L, and the uranium adsorption capacity is up to 18.13 mg/g. This study can provide a new idea for the development of efficient, stable and multifunctional hydrogel materials for uranium extraction from seawater.

A P204-TOPO-sulfonated kerosene synergistic extraction-Fe(Ⅱ) reduction stripping system was constructed. The effects of extraction reaction time, phosphoric acid concentration, extraction temperature, amount of iron powder and stripping temperature were investigated, and the optimal process conditions were determined. The results show that the extraction-stripping of uranium conforms to the law of diffusion control-in-phase reaction. The apparent activation energy of the extraction reaction is 34.76 kJ/mol, and that of the stripping reaction is 40.289 kJ/mol. The system is controlled by both mass transfer and chemical reaction. The optimal extraction conditions are room temperature, extraction time of 6 min, phosphoric acid concentration of 3.5 mol/L, and V_O/V_A=1/5. The optimal stripping conditions are temperature of 323.15 K, stripping time of 10 min, phosphoric acid concentration of 5 mol/L, reduced iron powder amount of 10 times the theoretical amount, and V_O/V_A=5/1. Under the optimal conditions, the uranium extraction rate is 96% and the stripping rate is 81.3%.

The leaching of manganese from low-grade manganese carbonate ore by sulfuric acid without reducing agent was studied. The effects of key parameters such as mineral particle size, sulfuric acid concentration and liquid volume to solid mass ratio on the leaching rate of manganese were investigated by single factor test, and the cyclic leaching process was optimized. The results show that under the conditions of ore particle size －300 μm－+150 μm proportion ≥ 95%, sulfuric acid concentration of 5.5 mol/L, reaction temperature of 60 ℃, each cycle leaching time of 30 min, liquid volume to solid mass ratio of 4∶1, and 4 extraction cycles of leaching, the average leaching rate of manganese is 98.35%, and the mass concentration of manganese in the leaching solution is 101.62 g/L. The proportion of manganese and impurities in the leaching solution is coordinated, and the solution composition is equivalent to the solution composition obtained by the leaching of imported manganese carbonate ore, which can provide qualified feed solution for the next step of manganese deep processing.

The efficient removal and stabilization of arsenic in copper smelting waste acid is a difficult problem for the green development of the industry. Although the existing lime-iron salt method can remove arsenic, it produces a large amount of arsenic-containing waste residue, which has the risk of secondary pollution. In order to achieve treating waste with waste, the treatment of arsenic in waste acid by copper tailings was studied. Through the synergistic oxidation-precipitation mechanism of hydrogen peroxide, the effects of initial pH, solid mass to liquid volume ratio, reaction temperature, reaction time and hydrogen peroxide dosage on arsenic removal and arsenic stability were systematically investigated. The results show that under the optimal conditions of initial pH= 0.65, solid mass to liquid volume ratio of 1 g/8 mL, reaction temperature of 60 ℃, reaction time of 10 h, and 30% hydrogen peroxide dosage of 2.0 mL/100 mL, the removal rate of arsenic in waste acid reaches more than 97%, and the arsenic leaching concentration of arsenic-containing tailings after treatment reaches the standard. The method can realize the efficient removal and solidification of arsenic in waste acid, which provides a new technical support for the resource utilization of copper tailings and the treatment process of waste acid.

The iron content in flotation tailings of copper smelting slag is high, which has further comprehensive recycling value. Based on the difference of decomposition performance of fayalite and magnetite minerals in copper tailings in acidic solution, the recovery of iron from copper smelting tailings by sulfuric acid leaching－magnetic separation process was studied. The effects of various factors on iron recovery were investigated, and the optimal leaching and magnetic separation conditions were determined. The results show that under the optimized acid leaching conditions of sulfuric acid concentration of 0.2 mol/L, liquid volume to solid mass ratio of 4∶1, leaching temperature of 40 ℃ and leaching time of 60 min, the total iron mass fraction in the leaching residue is 52.57%, and the iron recovery rate is 95.17%. The optimum magnetic separation conditions are as follows: grinding particle size 28 μm accounts for 90%, magnetic separation field strength 140 kA/m. Under the conditions, the total iron grade of iron concentrate is 59.25%, and the iron recovery rate is 85.70%. The process has good economic feasibility and can provide reference for the resource utilization of iron in flotation tailings of copper smelting slag.

In order to solve the problem of fluorine-containing water pollution, lanthanum chloride precipitation method was used to remove fluorine from it. Through in-depth analysis of the chemical characteristics and thermodynamic reaction mechanism of the solution, the interaction between La³⁺ and F^- in aqueous solution was revealed. The effects of initial pH of the solution, the amount of lanthanum chloride, reaction temperature and time on the removal of fluoride were investigated by single factor test, and the optimized process parameters were determined. The results show that for the fluorine-containing simulated solution with fluorine ion mass concentration of 0.1－1.0 g/L, under the conditions of initial solution pH of 3.0, lanthanum chloride dosage of 1.3 times of the theoretical amount, reaction temperature of 50 ℃ and reaction time of 10 min, the fluorine removal rate is more than 95%, and the residual fluorine ion mass concentration in the liquid after fluorine removal is less than 30 mg/L, which meets the fluoride emission limit specified in the national standard. The method has good process applicability in a wide range of fluorine concentration and has certain application value.

Aiming at the problems of high chemical inertness of high-rank anthracite, high energy consumption and high pollution of traditional activation process, a two-step process of potassium ferrate activation－thiourea gas phase doping was used to prepare high-performance nitrogen and sulfur co-doped porous carbon. The effects of activation temperature, mass ratio of potassium ferrate to coal and activation time on the preparation of porous carbon CDC were investigated by Box-Behnken method. Then, nitrogen and sulfur were doped into thiourea gas phase to obtain NS-3-850. The microstructure and surface chemical properties were characterized by SEM-EDS, XRD, Raman and XPS. The electrochemical properties were tested by CV and GCD methods. The results show that the method effectively constructs a hierarchical pore structure dominated by micropores and coordinated by mesopores, and successfully introduces nitrogen-and sulfur-containing functional groups into the carbon skeleton. The obtained nitrogen and sulfur co-doped porous carbon has a high specific surface area (1 393 m²/g) and an optimized mesoporous ratio (33.69%). The pore structure is suitable for ion diffusion and the surface functional groups are improved. NS-3-850 exhibits good energy storage performance in 6 mol/L KOH electrolyte, and the specific capacitance is 220 F/g at current density of 0.5 A/g. The preparation process provides a feasible technical path for the directional conversion and functionalization of inert coal by wet chemical means.

A self-synthesized novel composite alkaline slow-release material was studied for the treatment of uranium mine acid mine drainage (AMD) containing high concentrations of . Static tests were first conducted to screen for an optimal composite alkali-releasing material. Subsequently, static condition tests and dynamic column experiments were carried out to evaluate the alkali-release performance, physical stability, and the removal efficiency of U(Ⅵ) and Mn from simulated AMD. The results show that for an acidic solution with pH 2.6 and mass concentration of 2.7 g/L, the optimal composite alkali-releasing material exhibits good resistance to pulverization and sustained alkali-release performance. In the dynamic column experiment, when the material contacted the solution for 40 minutes, the effluent pH can be stably raised to 8－9. With initial mass concentrations of U and Mn at 1 mg/L and 2.9 mg/L, respectively, the removal rates of U and Mn are 69.8% and 67.2%, respectively. The material demonstrates long-term resistance to pulverization under the erosion of high-concentration acid, making it suitable for use as a slow-release alkali source in Permeable reactive barrier (PRB) technology.

To enhance comprehensively recovery efficiency of zirconium resources from polymetallic deposits, and support the development of clean energy, a systematic analysis was conducted on the raw ore, zircon concentrate, tailings, and hydrometallurgical products at different stages from an alkaline granite porphyry-type polymetallic deposit in Inner Mongolia. Multi-techniques, including optical microscopy, SEM-EDS, XRD, and AMICS was used to systematically reveal the occurrence forms and liberation characteristics of zirconium throughout the entire beneficiation and metallurgical process. The research results show that zirconium mainly occurs as independent zircon in the raw ore and processing products, with minor amounts occurring in the form of isomorphic, substituting for Th⁴⁺ and U⁴⁺ ions and dispersing in carrier minerals such as thorite, pyrochlore, and monazite. Zircon is progressively enriched and liberated during beneficiation, although fine-grained zircon particles are still lost in gravity tailings due to encapsulation or intergrowth. During hydrometallurgical treatment, zircon is converted into Zr compounds via alkali fusion, but some particles remain incompletely reacted or are encapsulated by newly formed siliceous materials, leading to residual zirconium in the acid-leaching residue, either as zircon or zirconium-bearing siliceous compounds. Based on these findings, an improved process of "stage grinding-stage seperation optimization dissolution-enhanced alkali fusion pretreatment" is proposed, providing mineralogical support for optimizing the ore beneficiation and metallurgical process.