A Fe-modified modified biomass rare earth tailings particle electrode, preparation method and application thereof

Abstract

The present invention provides an Fe-modified modified biomass rare earth tailings particle electrode, a preparation method and an application thereof, which are used for the micro-electrolysis deep treatment of high-concentration refractory organic industrial wastewater. By using rare earth tailings doped with biomass as a carrier and loading Fe modification, a regular particle electrode is prepared, which improves the mechanical strength of the particle electrode and can adsorb refractory organic matters in the wastewater, realizing the stable passivation of the micro-electrolysis deep treatment of organic matters in industrial wastewater. The preparation method includes respectively preparing rare earth tailings powder, cast iron powder and highly viscous clay powder; preparing biochar powder, mixing the biochar powder, rare earth tailings powder and highly viscous clay powder in a mass ratio of 5:3:2 to generate a carbon matrix; generating a second matrix after Fe modification, mixing the cast iron powder and the carbon matrix in a mass ratio of 5:1, granulating the second matrix after drying, and then placing it in a tubular furnace for anoxic calcination at 400 °C for 2 h, and cooling to generate rare earth tailings particle electrodes.

Description

Technical Field

[0001] The present invention relates to the field of industrial wastewater treatment, and in particular, to an Fe-modified modified biomass rare earth tailing particle electrode, a preparation method thereof, and an application thereof. Background Art

[0002] High-concentration and difficult-to-degrade organic industrial wastewater generally originates from industries such as chemical engineering, pesticides, leather making, coking, and dyes. Due to the characteristics of its production process, organic wastewater with complex components, high concentration, and containing difficult-to-degrade, toxic and harmful substances will be generated. It is difficult to treat such wastewater by traditional biochemical methods.

[0003] Especially in the chemical industry, due to the complex production process, there are a variety of chemical raw materials and chemical products involved. The organic chemical wastewater generated in production usually has the following characteristics: The wastewater mainly has the following characteristics:

[0004] ① The concentration of organic matter is high, the COD is generally above 2000mg / L, and some even reach as high as tens of thousands or hundreds of thousands of mg / L. Relatively speaking, the BOD is low, and the ratio of BOD to COD in many wastewaters is less than 0.3;

[0005] ② The composition is complex, and the wastewater contains toxic substances. Most of the organic matter in the wastewater is aromatic compounds and heterocyclic compounds, and it also contains sulfides, nitrides, heavy metals, and toxic organic substances;

[0006] ③ The chroma is high and there is an odor. Some wastewaters emit a pungent stench, causing adverse effects on the surrounding environment;

[0007] ④ It has strong acidity and alkalinity.

[0008] Therefore, the advanced oxidation technology for degrading high-concentration and difficult-to-degrade organic industrial wastewater will become one of the most important methods.

[0009] Commonly used advanced oxidation technologies include ozone advanced oxidation, photocatalysis, electrolysis and other technologies. Among them, the microelectrolysis technology is widely used as the advanced treatment of high-concentration and difficult-to-degrade organic industrial wastewater due to its low operating cost, simple process and easy operation.

[0010] Microelectrolysis is a good process for treating wastewater based on the principle of electrochemical corrosion of metals, using the formed countless micro-galvanic cell effects, also known as internal electrolysis method, iron-carbon method, iron filings filtration method, zero-valent iron method, etc. Traditionally, the microelectrolysis materials used in the microelectrolysis process are generally iron filings and charcoal, which need to be activated with acid and alkali before use, and are very easy to passivate and agglomerate during use. Also, because iron and carbon are in physical contact, it is very easy to form an isolation layer between them, making the microelectrolysis unable to continue and lose its effect. This leads to frequent replacement of microelectrolysis materials, not only with a large workload and high cost, but also affecting the treatment effect and efficiency of wastewater. Summary of the Invention

[0011] The object of the present invention is to provide a Fe-modified modified biomass rare earth tailings particle electrode, which has the characteristics of strong activity, large specific surface area, fast reaction rate, wide range of action on organic pollutants, long service life, etc. Moreover, during the microelectrolysis process, the change in the form of Fe in the Fe-modified modified biomass rare earth tailings particle electrode can not only realize the catalytic microelectrolysis process but also be compatible with the coagulation treatment process, and there is also a synergistic effect;

[0012] Another object of the present invention is to provide a preparation method of a Fe-modified modified biomass rare earth tailings particle electrode. After the rare earth tailings of the biochar are formed and calcined to create pores, the particle electrode is modified by loading Fe; when the filler is in the wastewater, countless tiny primary batteries can be formed to generate electrode reactions. At the same time, because the iron, carbon, and their impurities in the filler can also form a macroscopic battery according to the electrolytic activity, the efficiency of advanced wastewater treatment is improved.

[0013] Another object of the present invention is to provide the application of the Fe-modified modified biomass rare earth tailings particle electrode, which is used for the treatment of organic industrial wastewater. It can efficiently remove the organic matter in the wastewater, reduce the chromaticity, improve the biodegradability, and avoid phenomena such as filler passivation and caking during the operation while maintaining stable treatment effects.

[0014] The embodiments of the present invention are implemented as follows:

[0015] A preparation method of a Fe-modified modified biomass rare earth tailings particle electrode, the preparation method comprising the following steps:

[0016] S1: Prepare rare earth tailings powder, cast iron powder, and highly viscous clay powder respectively:

[0017] The raw material of the rare earth tailings powder is rare earth tailings. The main rare earth carrier minerals in the rare earth tailings are mainly bastnasite, and the main minerals are fluorite, barite, celestite, aluminosilicate minerals, and quartz, as well as a small amount of iron oxides;

[0018] S2: Prepare biochar powder to generate a carbon matrix:

[0019] Mix the biochar powder, rare earth tailings powder, and highly viscous clay powder in a mass ratio of 5:3:2, add an appropriate amount of water and disperse with an ultrasonic dispersion device to form a first suspension, and place the first suspension in a vacuum drying oven to dry to obtain a carbon matrix;

[0020] S3: Generate a second matrix modified with Fe:

[0021] Mix the cast iron powder in S1 and the carbon matrix in S2 in a mass ratio of 5:1, add an appropriate amount of water and disperse with an ultrasonic dispersion device to form a second suspension, and place the second suspension in a drying oven to dry to obtain a second matrix modified with Fe;

[0022] S4: Generate rare earth tailing particle electrodes:

[0023] Dry the second matrix and granulate it, then place it in a tubular furnace and roast it under anoxic conditions at 400 °C for 2 h, and take it out after cooling.

[0024] In a preferred embodiment of the present invention, the preparation method of the above-mentioned rare earth tailing powder includes: the rare earth tailings are the continental trough rare earth ore, and the rare earth tailings are crushed and screened to obtain rare earth tailing powder with a particle size of 50-100 mesh for standby.

[0025] In a preferred embodiment of the present invention, the preparation method of the above-mentioned cast iron powder includes: selecting waste cast iron chips from a machining factory and using a crusher to crush and screen to obtain cast iron powder with a particle size of 50-100 mesh.

[0026] In a preferred embodiment of the present invention, the preparation method of the above-mentioned highly viscous soil powder includes: using a crusher to crush and screen the highly viscous soil from a brick and tile kiln factory to obtain yellow fine powder with a particle size of 50-100 mesh, thus obtaining the highly viscous soil powder.

[0027] In a preferred embodiment of the present invention, the preparation method of the above-mentioned biochar powder includes: carbonizing natural renewable plant fibers such as rice husks, wheat straws, and straws under anoxic conditions at 400 °C and then crushing them to 100-150 mesh to form biochar powder.

[0028] In a preferred embodiment of the present invention, the specific generation method of the above-mentioned carbon matrix is as follows:

[0029] Mix biochar powder, rare earth tailing powder and highly viscous soil powder according to a mass ratio of 5:3:2, add an appropriate amount of water, and maintain a solid-liquid ratio of 1:40-50;

[0030] Disperse the biochar powder and rare earth tailing powder with ultrasound at 30-50 kHz and 50 W / L to form a first suspension;

[0031] Place the first suspension in a vacuum drying oven at 40 °C and dry it for 2 h to obtain the carbon matrix for standby.

[0032] In a preferred embodiment of the present invention, the specific generation method of the above-mentioned second matrix modified with Fe includes:

[0033] Mix cast iron powder and carbon matrix according to a mass ratio of 5:1, add an appropriate amount of water, and maintain a solid-liquid ratio of 1:30-40;

[0034] Disperse it with ultrasound at 30-50 kHz and 50 W / L to form a second suspension;

[0035] Place the second suspension in a drying oven at 40 °C and dry it for 1 h to obtain the second matrix modified with Fe.

[0036] In a preferred embodiment of the present invention, the above-mentioned second matrix granulation method includes: extruding into cylindrical particles by an extrusion granulator, with the particle diameter being 5 mm and the length being 10 mm.

[0037] An Fe-modified modified biomass rare earth tailings particle electrode, which is a rare earth tailings particle electrode obtained by the preparation method of any one of the above.

[0038] An application of an Fe-modified modified biomass rare earth tailings particle electrode, which is the application of a rare earth tailings particle electrode in the microelectrolysis deep treatment of organic industrial wastewater.

[0039] The embodiments of the present invention have the following advantages compared with the prior art:

[0040] 1. The electrode material obtained in the present invention for high-concentration and difficult-to-degrade organic industrial wastewater uses rare earth tailings, biochar, and highly viscous soil as carriers, doped with Fe modification. During the vacuum roasting process, the complete oxidation of Fe is prevented. By different roasting temperatures, the pore sizes and surface areas formed during the thermal decomposition of biochar are different. Among them, the main rare earth carrier minerals in the continental trough rare earth tailings are mainly bastnasite, and the main minerals are fluorite, barite, celestite, aluminosilicate minerals, and quartz, with a small amount of iron oxides. During the roasting process, carbon dioxide will be released, causing the crystal form of the tailings minerals to change, increasing the porosity, having a large specific surface area, and having a strong adsorption capacity;

[0041] 2. The continental trough rare earth tailings do not contain radioactive elements. After being doped and formed with biochar and highly viscous soil and roasted, a regular carrier is formed, increasing the rigid strength of the particle electrode material skeleton;

[0042] 3. The iron-carbon microelectrolysis in the particle electrode is the main microscopic primary battery in wastewater treatment. The rare earth tailings contain cerium, aluminosilicate, etc., which increase the surface activity of the particle electrode, introduce different metal elements to form a macroscopic primary battery with biochar particles, utilize the activity of various metal elements to form different electric potentials, constitute a microelectrolysis material, and increase and strengthen the microelectrolysis reaction, with a relatively high deep oxidation efficiency for wastewater under acidic and weakly alkaline conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0044] Figure 1 It is the SEM diagram of biomass carbonization in the embodiments of the present invention;

[0045] Figure 2 This is the SEM image of the particle electrode material in the present invention. Detailed implementation manners

[0046] The various exemplary detailed implementation manners of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation manners of the present invention.

[0047] It should be understood that the terms used in the present invention are only for describing specific implementation manners and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0048] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0049] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the present invention specification, which are obvious to those skilled in the art. Other specific implementation manners obtained from the present invention specification are also obvious to those skilled in the art. The present invention specification and examples are only exemplary.

[0050] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0051] First embodiment

[0052] This embodiment provides a Fe-modified modified biomass rare earth tailings particle electrode material, which is used for the advanced treatment of high-difficulty refractory organic industrial wastewater, and the advanced treatment includes but is not limited to catalytic micro-electrolysis process and coagulation treatment process.

[0053] It uses rare earth tailings doped with biomass-based as a carrier, and after being loaded with Fe modification, it is prepared into a regular particle electrode, which improves the mechanical strength of the particle electrode, and at the same time can adsorb refractory organic substances in the wastewater, realizing the stable passivation of the advanced micro-electrolysis treatment of organic substances in industrial wastewater.

[0054] Specifically, the preparation method of the rare earth tailings particle electrode material is as follows:

[0055] S1. Preparation of raw materials of rare earth tailings powder, cast iron powder and highly viscous clay powder:

[0056] Crush the rare earth tailings and screen out the ore powder with a mesh size of 50-100 meshes for standby; in this embodiment, the Continental Trough rare earth ore is selected, and the main rare earth carrier minerals in the tailings are mainly bastnasite, and the main minerals are fluorite, barite and celestite, aluminosilicate minerals and quartz, and a small amount of iron oxides;

[0057] Crush the waste cast iron chips from the machining factory and screen out the cast iron powder with a mesh size of 50-100 meshes for standby;

[0058] Crush the highly viscous clay from the brick and tile kiln factory and screen out the yellow fine powder with a mesh size of 50-100 meshes for standby.

[0059] S2. Preparation of biochar powder to generate carbon matrix:

[0060] Preparation method of biochar powder: Carbonize natural renewable plant fiber raw materials such as rice husks and wheat straw at 400 °C under anaerobic conditions and then crush them to 100-150 meshes. Please refer to Figure 1 the SEM image of biomass carbonization to form biochar powder for standby;

[0061] Method for generating carbon matrix: Mix the 50-100 mesh rare earth tailings powder prepared in step S1 with the highly viscous clay powder according to the mass ratio of biochar, rare earth tailings, and highly viscous clay of 5:3:2, add an appropriate amount of water, and the solid-liquid ratio is 1:40-50; Disperse the biomass carbon powder and rare earth tailings powder with ultrasound at 30-50 kHz and 50 W / L to form a first suspension; Place the first suspension in a vacuum drying oven at 40 °C and dry for 2 h to obtain a gray powder recorded as the carbon matrix for standby.

[0062] S3. Generate the second matrix modified with Fe:

[0063] Mix the 50-100 mesh cast iron powder prepared in S1 with the carbon matrix prepared in step S2 according to the mass ratio of 5:1, add an appropriate amount of water, and the solid-liquid ratio is 1:30-40; Disperse with ultrasound at 30-50 kHz and 50 W / L to form a second suspension, and place the second suspension in a drying oven at 40 °C and dry for 1 h to obtain the second matrix.

[0064] S4. Generate rare earth tailings particle electrodes:

[0065] Granulate the dried second matrix, extrude it into cylindrical particles with a diameter of 5 mm and a length of 10 mm using an extrusion machine, and then place it in a tubular furnace and roast it at 400 °C under anaerobic conditions for 2 h, and take it out after cooling. Please refer to Figure 2SEM image of the particle electrode material to obtain rare earth tailings particle electrodes.

[0066] The following combines different process data with experiments to further describe in detail the influence of rare earth tailings particle electrode materials on performance.

[0067] I. Influence of the mass ratio of iron to carbon on the removal efficiency of COD in wastewater

[0068] The prepared rare earth tailings particle electrodes are used for industrial wastewater treatment, such as the oxidation treatment of refinery wastewater. In the raw water of a company's refinery wastewater, the TOC content is about 1400 - 2000 mg / L, and the COD content is about 2100 - 3200 mg / L. The experimental wastewater used in this example is the refinery wastewater of this company after integrated coagulation and adsorption pretreatment as the experimental wastewater, and the COD content in the experimental wastewater is about 300 - 500 mg / L.

[0069] The experimental device is self-built. The influent uses experimental wastewater, and the effluent is connected to a sedimentation tank after adjusting the pH through a pipeline. After sedimentation, the effluent is taken out to measure its COD. Specifically, the particle electrodes prepared by mixing 50 - 100 mesh cast iron powder and matrix carbon in different mass ratios at a roasting temperature of 400 °C are used to investigate their removal rate of COD in the experimental wastewater. During the microelectrolysis treatment process, the liquid-solid ratio of the experimental wastewater to the particle electrode is 2:1, the pH is 4, and the reaction time is 2 h. Please refer to Table 1 for the influence of different mass ratios of iron to carbon on the COD removal rate.

[0070] Iron-carbon mass ratio 4﹕1 5﹕1 6﹕1 7﹕1 COD removal rate / % 68.40 80.05 71.23 60.20

[0071] Table 1

[0072] As can be seen from Table 1, with the increase of the mass ratio of iron to carbon, the removal rate of wastewater COD first rises and then falls. When the mass ratio of cast iron powder to matrix carbon is 5:1, the removal rate of COD in the wastewater reaches the maximum of 80.05%. This is because when iron and matrix carbon form a macroscopic primary battery, an appropriate ratio is required. The ratio of cast iron powder to matrix carbon determines the dosage of iron and matrix carbon, and also determines the number of primary batteries formed in the particle electrode. At the same time, the addition of various metal elements in rare earth tailings strengthens the reaction of the microelectrolysis primary battery. When the mass ratio of cast iron powder to matrix carbon is too small, the number of primary batteries in the reaction system fails to reach the maximum, resulting in incomplete microelectrolysis reaction. When the mass ratio of cast iron powder to matrix carbon is too large, excessive metal elements will accelerate dissolution under acidic conditions, directly react with hydrogen ions to produce hydrogen and metal ions. While a large number of metal ions enter the solution, the newly generated [H] is also less, thus reducing the ability of the wastewater organic matter at the filler. Moreover, especially when Fe2+ enters the solution, it will cause the wastewater to show a "color return" phenomenon. Therefore, the optimal mass ratio of iron to carbon in this example is 5:1.

[0073] II. Influence of the roasting temperature of particle electrodes on the COD removal rate of wastewater

[0074] Particle electrodes prepared by mixing 50-100 mesh cast iron powder and matrix carbon in a mass ratio of 5:1 under different roasting temperatures were used to investigate their COD removal rates from the experimental wastewater.

[0075] Similarly, during the micro-electrolysis treatment process, the liquid-solid ratio of the experimental wastewater to the particle electrodes was 2:1, the pH was 4, and the reaction time was 2 h. Please refer to Table 2 for the influence of different roasting temperatures on the COD removal rate.

[0076] Roasting temperature / °C 300 350 400 450 500 COD removal rate / % 72.03 76.12 80.10 71.36 69.24

[0077] Table 2

[0078] From Figure 2 it can be seen that when the roasting temperature was 400 °C, the COD removal rate of the particle electrodes prepared with a mass ratio of 5:1 of cast iron powder and matrix carbon powder for the experimental wastewater reached 80.10%. The roasting temperature is an essential and important factor during the roasting process of micro-electrolysis particle electrodes, which can affect issues such as the hardness of the particle electrodes, treatment efficiency, and economy in engineering practical applications. If the roasting temperature is too low, the clay cannot bond the cast iron powder and matrix carbon powder together, resulting in low hardness, loose structure, and easy swelling of the particle electrodes in the wastewater; if the roasting temperature is too high, the metal elements in the cast iron powder and rare earth tailings are prone to transform into oxides and become inactivated, and the energy consumption will also increase accordingly, which is not applicable considering technical economy. The optimal roasting temperature in this example is 400 °C.

[0079] III. Influence of different diameters of particle electrodes on the COD removal rate of wastewater

[0080] Particle electrodes with different diameters of 10 mm prepared by mixing 50-100 mesh cast iron powder and matrix carbon in a mass ratio of 5:1 under a roasting temperature of 400 °C were used to investigate their COD removal rates from the experimental wastewater. During the micro-electrolysis treatment process, the liquid-solid ratio of the experimental wastewater to the particle electrodes was 2:1, the pH was 4, and the reaction time was 2 h. Please refer to Table 3 for the influence of different diameters of particle electrodes on the COD removal rate of wastewater.

[0081] Diameter / mm 3 5 7 9 11 15 COD removal rate / % 79.02 80.03 79.65 75.00 67.80 45.20

[0082] Table 3

[0083] As can be seen from Table 3, within a relatively small particle size range, the COD removal rate of the particle electrodes for the wastewater can always be maintained at about 79%. However, as the diameter of the particle electrodes increases, the COD removal rate of the wastewater decreases. When the filler particle size increases to about 15 mm, the removal rate of the wastewater rapidly decreases to 45.20%.

[0084] The smaller the diameter of the particle electrode, the more the number of particles of the particle electrode contained per unit mass. Theoretically, the total specific surface area of the particles is larger, and the number of micro-galvanic cells is also more. In the same time, the removal rate of organic pollutants in the wastewater by the filler is higher. However, the filler particle size is not the smaller the better. If the particle size is too small, the formed particle electrode is easily crushed under pressure, easily lost, and has adverse effects such as caking and blockage, and instead fails to achieve the use effect and the purpose of preventing the filler from caking. Therefore, in this embodiment, it is recommended that the optimal choice for the particle electrode diameter is about 10 mm.

[0085] In summary, the electrode material prepared by the method provided in this embodiment is smelted and produced by fusing a metal alloy catalyst with a high potential difference and adopting a high-temperature microporous activation technology. It has the characteristics of iron-carbon integration, fused catalyst, microporous framework alloy structure, large specific surface area, light specific gravity, strong activity, large current density, and high water utilization efficiency.

[0086] The micro-electrolysis technology acts on the wastewater, can efficiently remove the organic matter in the wastewater, reduce the chroma, improve the biodegradability, and avoid phenomena such as filler passivation and caking during the operation while the treatment effect is stable.

[0087] The Fe-modified modified biomass rare earth tailings particle electrode in this embodiment has the characteristics of strong activity, large specific surface area, fast reaction rate, wide range of organic pollutants acting on, and long service life.

[0088] During the micro-electrolysis process, the change of the Fe form in the Fe-modified modified biomass rare earth tailings particle electrode can not only realize the catalytic micro-electrolysis process but also be compatible with the coagulation treatment process, and there is also a synergistic effect.

[0089] The rare earth tailings of the biochar used in this embodiment are formed and roasted to form pores and then loaded with Fe-modified particle electrodes. When the filler is in the wastewater, countless micro-galvanic cells can be formed to generate electrode reactions. At the same time, because the iron, carbon and impurities in the filler can also form a macroscopic battery according to the electrolytic activity, the efficiency of the advanced treatment of the wastewater is improved.

[0090] This specification describes examples of embodiments of the present invention and is not meant to illustrate and describe all possible forms of the present invention. It should be understood that the embodiments in the specification may be implemented in various alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or reduced to show details of particular components. The specific structural and functional details disclosed should not be construed as limiting but merely as a representative basis for teaching one skilled in the art to implement the present invention in multiple forms. Those skilled in the art should understand that the multiple features described and illustrated with reference to any one drawing may be combined with features illustrated in one or more other drawings to form embodiments not explicitly illustrated or described. The combinations of features described provide representative embodiments for typical applications. However, various combinations and variations of features consistent with the teachings of the present invention may be used for specific applications or implementations as needed.

[0091] The foregoing is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an Fe-modified modified biomass rare earth tailing particle electrode, characterized in that, The preparation method includes the following steps: Prepare rare earth tailings powder, cast iron powder and highly viscous clay powder respectively. The raw material of the rare earth tailings powder is rare earth tailings. The main rare earth carrier minerals of the rare earth tailings are mainly bastnasite. The main minerals are fluorite, barite and celestite, aluminosilicate minerals and quartz, as well as a small amount of iron oxides; the rare earth tailings are crushed and screened to obtain rare earth tailings powder with a particle size of 50-100 mesh. Prepare biochar powder to generate a carbon matrix. Mix the biochar powder, the rare earth tailings powder and the highly viscous clay powder in a mass ratio of 5-5.5:3:1.5-2, add an appropriate amount of water and disperse with an ultrasonic dispersion device to form a first suspension, and place the first suspension in a vacuum drying oven to dry to obtain a carbon matrix. Generate a second matrix modified with Fe. Mix the cast iron powder and the carbon matrix in a mass ratio of 5-7:1, add an appropriate amount of water and disperse with an ultrasonic dispersion device to form a second suspension, and place the second suspension in a drying oven to dry to obtain a second matrix modified with Fe. Generate rare earth tailings particle electrodes. Granulate the dried second matrix, and then roast it under anoxic conditions at 300-500 °C, and cool to obtain rare earth tailings particle electrodes. The preparation method of the biochar powder includes: carbonize natural renewable plant fibers at 400 °C under anoxic conditions and then crush them to 100-150 mesh to form biochar powder.

2. The preparation method of the Fe-modified modified biomass rare earth tailings particle electrode according to claim 1, characterized in that, The rare earth tailings are continental trough rare earth ores.

3. The preparation method of the Fe-modified modified biomass rare earth tailings particle electrode according to claim 1, characterized in that, The preparation method of the cast iron powder includes: select waste cast iron chips from a mechanical processing factory, and use a crusher to crush and screen to obtain cast iron powder with a particle size of 50-100 mesh.

4. The preparation method of the Fe-modified modified biomass rare earth tailings particle electrode according to claim 1, characterized in that, The preparation method of the highly viscous clay powder includes: use a crusher to crush and screen the highly viscous clay from a brick and tile kiln to obtain yellow fine powder with a particle size of 50-100 mesh to obtain highly viscous clay powder.

5. The preparation method of the Fe-modified modified biomass rare earth tailings particle electrode according to claim 1, wherein, The specific generation method of the carbon matrix is as follows: Mix the biochar powder, the rare earth tailings powder and the highly viscous clay powder in a mass ratio of 5:3:2, add an appropriate amount of water, and keep the solid-liquid ratio at 1:40-50; Disperse the biomass carbon powder and the rare earth tailings powder with ultrasonic waves at 30-50 kHz and 50 W / L to form a first suspension; Place the first suspension in a 40 °C vacuum drying oven and dry for 2 h to obtain a carbon matrix for standby.

6. The preparation method of the Fe-modified modified biomass rare earth tailings particle electrode according to claim 1, characterized in that, The specific generation method of the second matrix modified with Fe: Mix the cast iron powder and the carbon matrix in a mass ratio of 5:1, add an appropriate amount of water, and keep the solid-liquid ratio at 1:30-40; Disperse with ultrasonic waves at 30-50 kHz and 50 W / L to form a second suspension; Place the second suspension in a 40 °C drying oven and dry for 1 h to obtain a second matrix modified with Fe.

7. The preparation method of the Fe-modified modified biomass rare earth tailings particle electrode according to claim 1, characterized in that, The granulation diameter of the second matrix is 5-10 mm.

8. A Fe-modified modified biomass rare earth tailings particle electrode, characterized in that, Rare earth tailings particle electrodes obtained by the preparation method according to any one of claims 1-7.

9. Application of Fe-modified modified biomass rare earth tailing particle electrode, characterized in that, Application of the rare earth tailings particle electrode according to claim 8 in the deep treatment of organic industrial wastewater.

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