A method for efficient extraction of rare earth elements from mining sediment based on flash Joule heating technology

Abstract

This invention discloses a method for efficiently extracting rare earth elements from mine sediment based on flash Joule heating technology, thus establishing a rare earth element extraction technology field. The method comprises the following steps: (1) drying and grinding the mine sediment to be extracted to obtain rare earth precursor powder; (2) heat-treating the rare earth precursor powder using flash Joule heating under a protective atmosphere, followed by cooling and grinding to obtain flash Joule-heat-treated rare earth powder; (3) activating the flash Joule-heat-treated rare earth powder in an acid treatment solution, filtering after activation, and collecting the filtrate to obtain a rare earth element extract. Using this invention, efficient extraction of rare earth resources from mine sediment can be achieved.

Description

Technical Field

[0001] This invention relates to the field of rare earth element extraction, specifically to a method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology. Background Technology

[0002] Rare earth elements are an indispensable strategic resource in modern high-tech industries, and the supply-demand imbalance is becoming increasingly acute. Currently, more than 90% of the world's rare earth resources still rely on traditional mining. However, with the gradual depletion of high-grade rare earth reserves, traditional mining methods can no longer meet the growing market demand. Seeking new sources of rare earth resources and efficient recycling technologies has become an urgent need for industrial development.

[0003] It is worth noting that the rare earth element (REE) grades in the sediment accumulated in tailings ponds, dewatering wells, and beneficiation plant drainage ditches in the mining area are generally between 300 and 2000 ppm. This grade is higher than or close to the industrial mining threshold for rare earths, indicating significant recycling value. However, this type of sediment has long been undeveloped and considered a "dead reserve," resulting not only in a serious waste of rare earth resources but also in ecological and environmental hazards caused by sediment accumulation, exacerbating the pressure on ecological governance in the mining area.

[0004] Currently, although there has been some research on the recycling technology for rare earth-containing sediments, there are still insurmountable technical bottlenecks that prevent the realization of large-scale, green, and efficient recycling. The specific problems are as follows: Firstly, while wet acid leaching is widely used, it causes significant pollution. This process requires the use of acids with a concentration greater than 4 mol·L⁻¹. -1 The process involves using concentrated hydrochloric acid or sulfuric acid, with a liquid-to-solid ratio of 5:1 or higher, and leaching times ranging from 2 to 24 hours. This not only results in low reaction efficiency but also generates a large amount of high-salt wastewater, making subsequent wastewater treatment difficult and costly. Furthermore, the amount of neutralization residue generated after acid leaching is as high as 1.5 times the mass of the bottom mud, leading to significant secondary waste residue accumulation and causing secondary pollution.

[0005] Secondly, while bioleaching is environmentally friendly, its practicality is limited. This process relies on the metabolic activity of specific microbial communities to leach rare earth elements, with a reaction cycle of 5-15 days, resulting in low efficiency. Furthermore, the activity of these microbial communities is easily affected by fluctuations in environmental factors such as temperature and pH, leading to poor stability and a rare earth leaching rate that is generally below 60%, making it difficult to meet the recovery rate requirements of industrial production.

[0006] Third, the high-temperature roasting-chlorination process has excessively high energy consumption and emissions. The process heats the sediment to 1000-1200℃, with energy consumption exceeding 900 kWh / t. -1 This process consumes a huge amount of energy; it also requires the addition of 8-12% carbonaceous reducing agent, resulting in CO emissions exceeding 1.2 t·t during the reaction. -1Bottom sediment does not meet the dual carbon targets and green production concepts, and the investment cost of high-temperature equipment is high, resulting in poor economic efficiency.

[0007] Fourth, supercritical CO2 extraction faces technical and cost obstacles. The process requires equipment to withstand pressures exceeding 25 MPa, placing stringent demands on equipment materials and sealing performance. Furthermore, the large circulation volume of solvents and complexing agents, poor selectivity for rare earth elements, and high difficulty in impurity separation result in high overall process costs, hindering large-scale application.

[0008] Further analysis reveals that many of the defects in the aforementioned process are closely related to the limitations of traditional heating methods. Existing processes mostly employ heating methods such as resistance furnaces, muffle furnaces, or microwave sintering, all of which follow an outside-to-inward conduction pattern for heat transfer. However, the thermal conductivity of the bottom mud in mining areas is extremely low, only 0.3-0.8 W·m⁻¹. -1 ·K -1 This results in a slow heating rate, typically below 50°C / min. -1 This leads to a series of problems: First, slow heating cannot instantly break the crystal structure of stable minerals such as rare earth phosphates and silicates, making it difficult for rare earth elements to be effectively released from the mineral phase, thus restricting leaching efficiency; Second, during the heating process, organic matter and sulfides in the bottom mud will carbonize in advance, forming a dense coating layer that hinders the contact between rare earth elements and the leaching medium, further reducing recovery efficiency; Third, prolonged heating (processing cycle exceeding 2 hours) results in high energy consumption, which cannot match the needs of continuous dredging and batch processing in mining areas, making it difficult to achieve continuous industrial production.

[0009] Even more serious is that mining sediments often contain heavy metals such as lead (Pb), cadmium (Cd), and arsenic (As), as well as organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). During conventional high-temperature treatment, heavy metals are prone to volatilization and diffusion and cannot be captured simultaneously, causing secondary pollution of the atmosphere and soil. At the same time, prolonged high temperatures can promote deep carbonization of organic matter, generating persistent free radicals, increasing the difficulty and cost of subsequent harmless treatment of sediments, thus highlighting the superimposed environmental risks.

[0010] In summary, existing rare earth recovery processes in mine sediments generally suffer from low efficiency, high energy consumption, heavy pollution, and poor stability. The inherent defects of traditional heating methods further exacerbate these bottlenecks, making it impossible to achieve green and efficient recovery of dead rare earth reserves in the sediments. Therefore, developing a rare earth recovery technology for mine sediments that can overcome the limitations of traditional processes and possess high efficiency, low energy consumption, and environmental friendliness is of great significance for alleviating the supply and demand imbalance of rare earths, realizing resource recycling, and promoting ecological governance in mining areas. This has become a pressing technical problem for those skilled in the art to solve. Summary of the Invention

[0011] To address the aforementioned shortcomings, this invention proposes a method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology. This method aims to solve the core problem of low recovery efficiency when extracting rare earth elements from mining sediment using existing technologies, thereby achieving efficient extraction of rare earth resources from mining sediment.

[0012] To achieve this objective, the present invention adopts the following technical solution: A method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology includes the following steps: (1) Dry and grind the bottom mud of the mining area to be extracted to obtain rare earth precursor powder; (2) Under a protective atmosphere, the rare earth precursor powder was heat-treated by flash Joule heating. After cooling and grinding, the rare earth powder after flash Joule heating was obtained. (3) The rare earth powder after flash joule heat treatment is placed in an acid treatment solution for activation. The concentration of the acid treatment solution is ≤1.5M. After activation, the solution is filtered and the filtrate is collected to obtain rare earth element extract.

[0013] As an improvement to the above technical solution, in step (1), the bottom mud of the mining area to be extracted is dried at 90℃~110℃ to remove moisture, and then thoroughly ground and passed through a 150-250 mesh sieve to obtain rare earth precursor powder.

[0014] As an improvement to the above technical solution, step (2) specifically includes the following steps: (2.1) Place the rare earth precursor powder in a Joule furnace; (2.2) Under a protective atmosphere, with a pulse voltage of 50V~70V and a pulse current of 50A~70A, the rare earth precursor powder is heated to 1800K~2200K within 8~12s. (2.3) After natural cooling, the reaction product is ground and passed through a 150-250 mesh sieve to obtain rare earth powder after flash joule heat treatment.

[0015] As an improvement to the above technical solution, in step (2.2), argon gas is introduced into the Joule furnace to form a protective atmosphere.

[0016] As an improvement to the above technical solution, in step (2.2), under a protective atmosphere, with a pulse voltage of 60V and a pulse current of 60A, the rare earth precursor powder is heated to 2200K within 10s.

[0017] As an improvement to the above technical solution, in step (3), the rare earth powder after flash joule heat treatment is placed in an acid treatment solution and activated at 80℃~100℃ for 2~6 hours. After activation, it is filtered and the rare earth element extract is collected.

[0018] As an improvement to the above technical solution, the acid treatment solution is an HCl solution with a concentration of 0.5M to 1.5M.

[0019] As an improvement to the above technical solution, the sediment to be extracted is sediment from a rare earth mining area, and the mass percentage of rare earth elements in the sediment is ≤5%.

[0020] As an improvement to the above technical solution, the rare earth element includes one or more of Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Yb, Lu, and Ho.

[0021] As an improvement to the above technical solution, the rare earth element includes one or more of Sm and Ho.

[0022] One of the above technical solutions includes the following beneficial effects: 1. This embodiment employs a combination of flash Joule heat treatment and acid leaching to extract rare earth elements from industrial mining sediment. First, the high-temperature, rapid heat treatment characteristics of flash Joule heat can quickly alter the crystal structure and morphology of the rare earth phase in the rare earth precursor powder, breaking the bonds between the rare earth elements and the sediment matrix. This reduces the leaching resistance of rare earth elements during subsequent acid leaching, improving their extractability. Then, acid leaching is used to efficiently extract rare earth elements from the flash Joule heat-treated powder. By comparing the acid leaching extraction rates of samples before and after heat treatment, the synergistic effect of the flash Joule heat-acid leaching combined process is clearly demonstrated. Compared to direct acid leaching of the sediment, this method significantly improves the extraction efficiency of various rare earth elements, including Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Yb, Lu, and Ho. Furthermore, after flash joule heat treatment, the present invention only requires low-concentration acid for extraction to achieve efficient extraction of rare earth elements, eliminating the need for high-concentration acid leaching. This effectively reduces the harm to the ecological environment and lowers subsequent processing costs.

[0023] 2. This embodiment describes a method for efficiently extracting rare earth elements from mining sediment using flash evaporation Joule heating technology. This method enables efficient, green, and low-cost extraction of rare earth resources from mining sediment, providing a new path for diversified supply of rare earth resources and possessing both significant economic and environmental value. Attached Figure Description

[0024] Figure 1 This is a schematic diagram comparing the rare earth element extraction rates of Example 1 and Comparative Example 1. Figure 2 This is an SEM image of the sample before extraction in Example 1, wherein, Figure 2 Figures a1 and a2 are SEM images of the sample before extraction at different magnifications, respectively. Figure 3 These are SEM images of the samples extracted in Example 1, where... Figure 3 Figures b1 and b2 are SEM images of the extracted sample at different magnifications, respectively. Figure 4 This is a schematic diagram comparing the rare earth element extraction rates of Example 2 and Comparative Example 2; Figure 5 This is a schematic diagram comparing the rare earth element extraction rates of Example 3 and Comparative Example 3; Figure 6 This is a schematic diagram comparing the rare earth element extraction rates of Example 4 and Comparative Example 4. Figure 7 This is a schematic diagram comparing the rare earth element extraction rates of Example 4 and Comparative Example 4. Detailed Implementation

[0025] To facilitate understanding of the present invention, a more complete description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0026] Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Raw materials whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0028] This embodiment discloses a method for efficiently extracting rare earth elements from mine sediment based on flash Joule heating technology, including the following steps: (1) Dry and grind the bottom mud of the mining area to be extracted to obtain rare earth precursor powder; (2) Under a protective atmosphere, the rare earth precursor powder was heat-treated by flash Joule heating. After cooling and grinding, the rare earth powder after flash Joule heating was obtained. (3) The rare earth powder after flash joule heat treatment is placed in an acid treatment solution for activation. The concentration of the acid treatment solution is ≤1.5M. After activation, the solution is filtered, and the filtrate is collected to obtain a rare earth element extract. Specifically, the concentration of the acid treatment solution is exemplarily 0.5M, 0.6M, 0.7M, 0.8M, 0.9M, 1.0M, 1.1M, 1.2M, 1.3M, 1.4M, or 1.5M, but is not limited thereto.

[0029] It is worth noting that the extraction target in this embodiment is the bottom sediment of the mining area. The rare earth elements in the bottom sediment are of low grade and have poor physical properties (easy to clump, uneven particle size), which makes the extraction of rare earth elements from the bottom sediment of the mining area very difficult. Some existing technologies have studied the use of high-concentration acid leaching to extract rare earth elements from the bottom sediment of the mining area. However, in practical applications, it has been found that this method not only has an extremely low rare earth element extraction rate, but also causes great harm to the ecological environment and has high subsequent processing costs.

[0030] This embodiment employs a combined method of flash Joule heat treatment and acid leaching to extract rare earth elements (REEs) from industrial mining sediment. First, the high-temperature, rapid heat treatment characteristics of flash Joule heat treatment quickly alter the crystal structure and morphology of the rare earth phase in the rare earth precursor powder, breaking the bonds between the rare earth elements and the soil matrix. This reduces the leaching resistance of REEs during subsequent acid leaching, improving their extractability. Then, acid leaching is used to extract REEs from the flash Joule heat-treated powder. By comparing the acid leaching extraction rates of samples before and after heat treatment, the synergistic effect of the combined flash Joule heat treatment and acid leaching method is clearly demonstrated. Compared to direct acid leaching of the mining sediment, this method significantly improves the extraction efficiency of various REEs such as Ho, La, and Sm. Furthermore, after flash Joule heat treatment, only a low-concentration (≤1.5M) acid solution is needed for efficient REE extraction, eliminating the need for high-concentration acid leaching. This effectively reduces environmental impact and lowers subsequent processing costs.

[0031] In one embodiment, in step (1), the bottom mud of the mining area to be extracted is dried at 90°C to 110°C to remove moisture, and then thoroughly ground and passed through a 150-250 mesh sieve to obtain rare earth precursor powder.

[0032] This embodiment, using drying at 90℃~110℃, effectively removes free moisture from the sediment of the mining area to be extracted. This prevents rapid vaporization of moisture during subsequent flash Joule heat treatment, which could lead to powder splashing and agglomeration, ensuring the stability of the heat treatment process. Furthermore, it avoids side reactions between moisture and rare earth components or equipment at high temperatures, reducing interference with the rare earth's morphology. Thorough grinding and sieving through a 150-250 mesh sieve breaks the soil sample into a uniform fine powder state, reducing particle size differences and ensuring a uniform particle size distribution of the rare earth precursor powder. This results in more uniform pulse current conduction during subsequent flash Joule heat treatment, avoiding problems such as localized overheating or insufficient heat treatment.

[0033] Specifically, in step S100, the sediment from the mining area to be extracted can be dried at 90℃, 95℃, 100℃, 105℃, or 110℃ to remove moisture, but is not limited to these conditions. After thorough grinding, it can be passed through a 150-mesh, 200-mesh, or 250-mesh sieve, but is not limited to these conditions.

[0034] In one implementation, step (2) specifically includes the following steps: (2.1) Spread the rare earth precursor powder evenly on the surface of carbon paper and place it in a Joule furnace; specifically, spread the rare earth precursor powder evenly on the surface of carbon paper inside a quartz tube with a size of 2cm×6cm and place it in a Joule furnace. (2.2) Under a protective atmosphere, with a pulse voltage of 50V~70V and a pulse current of 50A~70A, the rare earth precursor powder is heated to 1800K~2200K within 8~12s; specifically, the pulse voltage is 50V, 55V, 60V, 65V or 70V, the pulse current is 50A, 55A, 60A, 65A or 70A, and the temperature after heating is 1800K, 1900K, 2000K, 2100K or 2200K, but not limited thereto; (2.3) After natural cooling, the reaction product is ground and passed through a 150-250 mesh sieve to obtain rare earth powder after flash joule heat treatment.

[0035] Carbon paper, as an excellent conductive and thermal carrier, ensures full contact between the powder and the heat source; quartz tubes fix the sample shape and prevent sample displacement and scattering during heating. Combined with an inert protective atmosphere, side reactions such as oxidation and nitridation of rare earth components at high temperatures of 1800K~2200K can be effectively avoided, ensuring the purity of the rare earth phase. The short-duration, high-temperature flash Joule heating mode can rapidly break the bonds between rare earth elements and the sediment matrix in the rare earth precursor (such as the lattice structure of silicate and oxide matrices), promoting phase transformation or grain refinement of the rare earth phase, significantly improving the activity of the rare earth components, and greatly reducing resistance to subsequent acid leaching extraction. Natural cooling avoids sample lattice distortion or stress cracking caused by rapid cooling, ensuring the stability of the rare earth phase. Subsequent grinding and sieving through a 150-250 mesh sieve can eliminate local agglomeration that may occur during high-temperature treatment, resulting in a uniform particle size distribution of the rare earth powder and improving the uniformity of solid-liquid contact in subsequent acid leaching experiments.

[0036] In one embodiment, in step (2.2), a protective atmosphere is formed by introducing argon gas into the Joule furnace.

[0037] At high temperatures of 1800K~2200K, rare earth elements and compounds exhibit strong chemical reactivity. Contact with oxygen easily generates stable rare earth oxides, while contact with nitrogen may produce rare earth nitrides. These byproducts significantly reduce the leachingability of rare earth elements and may even alter their phase structure. Argon protection can prevent such side reactions. The sample is spread on the surface of carbon paper, which serves as a conductive and thermally conductive carrier, crucial for achieving rapid heating. Furthermore, without an inert gas protective atmosphere, contact with oxygen at high temperatures can cause a combustion reaction in the carbon paper, leading to structural damage, decreased conductivity, and uneven current conduction, resulting in localized insufficient or overheating of the sample.

[0038] In one embodiment, in step (2.2), the rare earth precursor powder is heated to 2200K within 10s under a protective atmosphere and with a pulse voltage of 60V and a pulse current of 60A.

[0039] In one embodiment, in step (3), the rare earth powder after flash joule heat treatment is placed in an acid treatment solution and activated at 80℃~100℃ for 2~6 hours. After activation, it is filtered and the rare earth element extract is collected. The rare earth powder before and after flash joule heat treatment is acid-leached and activated. Under the above conditions, the rare earth components activated at high temperature can be fully dissolved, further improving the extraction rate of rare earth elements.

[0040] In one embodiment, the acid treatment solution is an HCl solution with a concentration of 0.5M to 1.5M. The HCl solution concentration used in this embodiment, within the range of 0.5M to 1.5M, effectively extracts rare earth elements from rare earth powder after flash Joule heat treatment. Furthermore, the relatively low concentration of the HCl solution used in this embodiment eliminates the need for high-concentration HCl solutions to effectively extract rare earth elements. Compared to traditional acid leaching using high-concentration acids, this method is more environmentally friendly and safer.

[0041] In some alternative embodiments, the concentration of the HCl solution is 1.0 M.

[0042] In one embodiment, the sediment to be extracted is rare earth mine sediment, which is waste solid material generated during the mining and beneficiation of rare earth ore. The mass percentage of rare earth elements in the rare earth mine sediment is ≤5%, meaning the sum of the masses of all rare earth elements in the rare earth mine sediment accounts for ≤5% of the total mass of the rare earth mine sediment. Since the extraction target in this embodiment is rare earth mine sediment, which has a low rare earth grade and contains a large amount of minerals (such as quartz and feldspar) and impurity elements (such as iron, calcium, and silicon), the extraction of rare earth elements from the rare earth mine sediment is very difficult. This embodiment uses a flash evaporation Joule heating method combined with low-concentration acid leaching, which can effectively improve the extraction rate of rare earth elements from rare earth mine sediment.

[0043] In one embodiment, the rare earth element includes one or more of Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Yb, Lu, and Ho.

[0044] More preferably, the method of the present invention for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology is used to extract one or more rare earth elements from Sm and Ho.

[0045] The technical solution of the present invention will be further explained below with reference to embodiments and comparative examples. Example

[0046] This embodiment provides a method for efficiently extracting rare earth elements from mine sediment based on flash Joule heating technology, including the following steps: (1) The bottom mud of the mining area to be extracted is dried at 100°C to remove moisture, and then thoroughly ground and passed through a 200-mesh sieve to obtain rare earth precursor powder; wherein, in this embodiment, the bottom mud of the mining area to be extracted is rare earth mining area mud, and the mass percentage of rare earth elements in the rare earth mining area mud of this embodiment is 3.2%; (2) Take 50 mg of the rare earth precursor powder obtained in step (1), spread it evenly on the surface of carbon paper inside a quartz tube with dimensions of 2 cm × 6 cm, and place it in a Joule heating furnace. Argon gas is introduced as a protective atmosphere, and the rare earth precursor powder is heated to 2000 K within 10 s under the conditions of pulse voltage of 60 V and pulse current of 60 A. After it cools naturally, the reaction product is ground and passed through a 200-mesh sieve to obtain rare earth powder after flash Joule heat treatment.

[0047] (3) Place the rare earth powder after flash joule heat treatment in 1M HCl solution and activate it at 85℃ for 4 hours. After activation, filter it using an F-grade sand core funnel and collect the rare earth element extract.

[0048] Comparative Example 1 This comparative example provides a method for extracting rare earth elements, including the following steps: (1) The bottom mud of the mining area to be extracted was dried at 100°C to remove moisture, and then ground thoroughly and passed through a 200-mesh sieve to obtain rare earth precursor powder; wherein, the bottom mud of the mining area to be extracted used in this comparative example is the same rare earth mining area bottom mud from the same source and batch as in Example 1, and the mass percentage of rare earth elements in the rare earth mining area bottom mud of Comparative Example 1 is 3.2%.

[0049] (2) Take 50 mg of the rare earth precursor powder obtained in step (1) and place it in 5 M HCl solution. Activate it at 85 °C for 4 hours. After activation, filter it using an F-grade sand core funnel and collect the filtrate to obtain rare earth element extract.

[0050] Specifically, the total content of each rare earth element in the sediment of the mining area to be extracted used in Example 1 and Comparative Example 1 was determined using the following methods: The sediment from the mining area to be extracted (from the same source and batch as in Example 1) was dried at 100°C to remove moisture, then thoroughly ground and passed through a 200-mesh sieve to obtain rare earth precursor powder. 30 mg of the rare earth precursor powder was activated overnight at 95°C in a mixture of concentrated HF (48 wt%, 2 mL) and concentrated HNO3 (15 M, 2 mL). The sample was then dried in an oven at 100°C and re-digested overnight at 95°C in a mixture of concentrated HNO3 (15 M, 1 mL), H2O2 (32%, 1 mL), and ultrapure water (5 mL, HPLC grade). After digestion, all solids were dissolved, and the sample was diluted to 50 mL with ultrapure water. ICP-MS was performed to determine the total content of each rare earth element in the original mining area sediment.

[0051] The rare earth element extracts obtained in Example 1 and Comparative Example 1 were diluted with ultrapure water, and the contents of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb, Lu, and Ho in the rare earth element extracts obtained in Example 1 and Comparative Example 1 were determined by ICP-MS.

[0052] Based on the measured contents of each rare earth element in Example 1 and Comparative Example 1, and the total contents of each rare earth element in the original mine sediment determined by the above method, the extraction rate of each rare earth element can be calculated. The extraction rates of each rare earth element in Example 1 and Comparative Example 1 are detailed below. Figure 1 As shown. Figure 1 In the diagram, the blue bars indicate the test data for Comparative Example 1, and the orange bars indicate the test data for Example 1.

[0053] from Figure 1 It can be seen that first treating the sediment samples using flash Joule heating technology, followed by extraction in a 1 mol / L hydrochloric acid solution, significantly increased the extraction rates of elements Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Yb, Lu, and Ho, with improvements several times or even tens of times. Furthermore, from... Figure 1 It can be seen that Example 1 has a relatively high extraction rate for elements Ho and Sm, with Ho having the highest extraction rate. Therefore, the extraction method of Example 1 can be used when extracting Ho and Sm.

[0054] Furthermore, scanning electron microscopy (SEM) was performed on the samples before and after extraction in Example 1. The SEM image of the sample before extraction in Example 1 is shown below. Figure 2 As shown, the SEM image of the extracted sample is shown in the image. Figure 3 As shown. From Figure 2 The sample before the use of flash Joule heating technology shows that the sample particles had a rough surface before the reaction, and rare earth elements were attached to the surface of the sediment particles in the mining area in the form of micro-nano particles. Figure 3 It can be seen that the particle size of the sample decreased after the reaction, the surface was relatively smooth, and there were pores on the sample surface, which is presumably caused by the extraction of rare earth particles, indicating that the rare earth element extraction effect was good.

[0055] Examples 2 to 5 The methods for efficiently extracting rare earth elements from mining sediment using flash Joule heating technology in Examples 2-5 are the same as those in Example 1, except that the mining sediment samples used in Examples 2-5 are from rare earth mining areas with different origins or batches than those in Example 1. Specifically, the mass percentage of rare earth elements in the rare earth mining sediment used in Example 2 is 2.9%, the mass percentage of rare earth elements in the rare earth mining sediment used in Example 3 is 2.5%, the mass percentage of rare earth elements in the rare earth mining sediment used in Example 4 is 2.4%, and the mass percentage of rare earth elements in the rare earth mining sediment used in Example 5 is 3.1%.

[0056] Comparative Examples 2 to 5 The methods for extracting rare earth elements in Comparative Examples 2 to 5 are the same as those in Comparative Example 1, except that the sediment samples used in Comparative Example 2 are the same as those used in Example 2, the sediment samples used in Comparative Example 3 are the same as those used in Example 3, the sediment samples used in Comparative Example 4 are the same as those used in Example 4, and the sediment samples used in Comparative Example 5 are the same as those used in Example 5.

[0057] The extraction rates of rare earth elements in Example 2 and Comparative Example 2 are shown in [reference needed]. Figure 4 As shown, the extraction rates of rare earth elements in Example 3 and Comparative Example 3 are as follows: Figure 5 As shown, the extraction rates of rare earth elements in Example 4 and Comparative Example 4 are as follows: Figure 6 As shown, the extraction rates of rare earth elements in Example 5 and Comparative Example 5 are as follows: Figure 7 As shown.

[0058] from Figure 4 It can be seen that the extraction rates of most rare earth elements in Example 2 are significantly higher than those in Comparative Example 2. In Example 2, the extraction rates of most elements are around 40%, with La reaching 48%, Sm reaching 47%, and Ho reaching 79%.

[0059] from Figure 5 It can be seen that the extraction rates of most rare earth elements in Example 3 are significantly higher than those in Comparative Example 3. Specifically, the extraction rate of Sm in Example 3 reaches 32%, and the extraction rate of Ho reaches 58%.

[0060] from Figure 6 It can be seen that the extraction rates of most rare earth elements in Example 4 are significantly higher than those in Comparative Example 4. Specifically, the extraction rate of Sm in Example 4 reaches 32%, and the extraction rate of Ho reaches 62%.

[0061] from Figure 7 It can be seen that the extraction rates of most rare earth elements in Example 5 are significantly higher than those in Comparative Example 5. Specifically, the extraction rate of Sm in Example 5 reaches 52%, and the extraction rate of Ho reaches 85%.

[0062] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology, characterized in that, Includes the following steps: (1) Dry and grind the bottom mud of the mining area to be extracted to obtain rare earth precursor powder; (2) Under a protective atmosphere, the rare earth precursor powder was heat-treated by flash Joule heating. After cooling and grinding, the rare earth powder after flash Joule heating was obtained. (3) The rare earth powder after flash joule heat treatment is placed in an acid treatment solution for activation. The concentration of the acid treatment solution is ≤1.5M. After activation, the solution is filtered and the filtrate is collected to obtain rare earth element extract.

2. The method for efficiently extracting rare earth elements from mine sediment based on flash Joule heating technology according to claim 1, characterized in that, In step (1), the bottom mud of the mining area to be extracted is dried at 90℃~110℃ to remove moisture, and then thoroughly ground and passed through a 150-250 mesh sieve to obtain rare earth precursor powder.

3. The method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology according to claim 2, characterized in that, Step (2) specifically includes the following steps: (2.1) Place the rare earth precursor powder in a Joule furnace; (2.2) Under a protective atmosphere, with a pulse voltage of 50V~70V and a pulse current of 50A~70A, the rare earth precursor powder is heated to 1800K~2200K within 8~12s. (2.3) After natural cooling, the reaction product is ground and passed through a 150-250 mesh sieve to obtain rare earth powder after flash joule heat treatment.

4. The method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology according to claim 3, characterized in that, In step (2.2), a protective atmosphere is formed by introducing argon gas into the Joule furnace.

5. The method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology according to claim 3, characterized in that, In step (2.2), the rare earth precursor powder is heated to 2200K within 10s under a protective atmosphere and with a pulse voltage of 60V and a pulse current of 60A.

6. The method for efficiently extracting rare earth elements from mine sediment based on flash Joule heating technology according to claim 3, characterized in that, In step (3), the rare earth powder after flash joule heat treatment is placed in an acid treatment solution and activated at 80℃~100℃ for 2~6 hours. After activation, it is filtered and the rare earth element extract is collected.

7. The method for efficiently extracting rare earth elements from mine sediment based on flash Joule heating technology according to claim 6, characterized in that, The acid treatment solution is an HCl solution with a concentration of 1.0M.

8. The method for efficiently extracting rare earth elements from mine sediment based on flash Joule heating technology according to claim 6, characterized in that, The sediment to be extracted is sediment from a rare earth mining area, and the mass percentage of rare earth elements in the sediment is ≤5%.

9. The method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology according to claim 8, characterized in that, The rare earth elements include one or more of Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Yb, Lu, and Ho.

10. The method for efficiently extracting rare earth elements from mining sediment based on flash Joule heating technology according to claim 8, characterized in that, The rare earth elements include one or more of Sm and Ho.

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