Method for regenerating a filter cloth for leaching of rare earth roasted ore

Abstract

The application discloses a method for regenerating rare earth roasting ore water leaching filter cloth, and belongs to the technical field of filter cloth cleaning, regeneration and repair.The method comprises the following steps: screening out failed filter cloth with secondary utilization value, and performing high-temperature steam blowing activation on the filter cloth by using configured activators; then, the treated filter cloth is placed into a strong acid solution for ultrasonic soaking treatment, and then is washed by water until the pH of the filter cloth surface is 6-7; finally, the treated filter cloth is subjected to surface treatment and heat setting treatment, so that the regenerated filter cloth is obtained.The method effectively overcomes the defects of traditional cleaning methods, restores the original performance of the filter cloth, and greatly reduces the production cost of enterprises.

Description

Technical Field

[0001] This invention relates to the field of filter cloth cleaning, regeneration and repair technology, and more specifically to a method for regenerating filter cloth using rare earth roasted ore water leaching solution. Background Technology

[0002] Traditional filter cloth cleaning methods typically include physical cleaning (such as washing or brushing) and chemical cleaning (such as acid and alkali solution treatment). However, while these methods can remove some surface contaminants, they cannot completely restore the original filtration performance of the filter cloth. Especially during chemical cleaning, some metal ions on the filter cloth surface (such as aluminum, calcium, magnesium, and iron) may react with the cleaning solution to form complex precipitates, further exacerbating secondary clogging or damage to the filter cloth and even reducing its service life. Furthermore, existing cleaning and regeneration technologies suffer from a series of problems, such as unsatisfactory cleaning results, long regeneration cycles, high energy consumption, and significant resource waste.

[0003] To address these issues, researchers and engineers in the industry are actively exploring new filter cloth regeneration technologies. These technologies aim to thoroughly remove contaminants from filter cloths using efficient and environmentally friendly methods, avoiding secondary precipitation and complex formation of metal ions during the cleaning process. This, in turn, restores the filter cloth's filtration performance, improves its permeability and strength, and extends its service life. For example, comparative patent CN 111167219 A discloses a filter cloth cleaning method comprising six steps: pre-cleaning, primary cleaning, primary aeration, secondary cleaning, secondary aeration, and filter cloth surface treatment. However, this method is not suitable for cleaning filter cloths used in rare earth roasted ore leaching solutions.

[0004] In the treatment of rare earth roasted ore leaching solutions, filter cloth, as a key filtration medium, is widely used to separate and remove organic matter, inorganic salts, and other complex substances from the leaching solution. These filter cloths are typically made of corrosion-resistant materials and can withstand harsh working conditions. However, over time, a large amount of contaminants, such as organic matter, inorganic salts, and other metal compounds, accumulate on the surface and in the mesh of the filter cloth. These contaminants gradually clog the filter cloth mesh, reducing its permeability and filtration efficiency, thus affecting the overall efficiency and stability of the rare earth roasted ore leaching solution treatment system. At the production site, due to factors such as temperature and ion concentration in the solution, filter cloths sometimes become severely clogged and fail after only 1-2 days of use. The main structure of such failed filter cloths remains largely intact, with minimal wear on the mesh, but all the filter pores are completely blocked. These blockages are difficult to remove with acids, alkalis, or other cleaning agents, ultimately requiring the filter cloth to be treated as solid waste.

[0005] Existing methods do not provide specific cleaning or regeneration methods for filter cloths used in rare earth roasted ore leaching solutions. Due to the significant differences in the composition of the liquid, although filter cloth cleaning methods from other fields can remove some contaminants to a certain extent, they still have drawbacks such as poor cleaning effect and high cost.

[0006] Therefore, how to provide a method for regenerating filter cloth from rare earth roasted ore water leaching solution is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a method for regenerating filter cloth of rare earth roasted ore water leaching solution, which effectively overcomes the shortcomings of traditional cleaning methods, restores the original performance of the filter cloth, and greatly reduces the production cost for enterprises.

[0008] To achieve the above objectives, the present invention provides a method for regenerating filter cloth from rare earth roasted ore water leaching solution, specifically including the following steps: S1, the screened-out failed filter cloth with secondary utilization value is activated by high-temperature steam blowing with a prepared activator.

[0009] S2, the filter cloth treated in S1 is immersed in a strong acid solution for ultrasonic soaking, and then rinsed with water until the pH of the filter cloth surface is 6-7.

[0010] S3 involves surface treatment of the filter cloth after S2, followed by heat setting to obtain the final regenerated filter cloth.

[0011] Its beneficial effects are as follows: By combining multiple steps such as high-temperature steam activation, acid solution immersion, and composite surface modification solution treatment, it can efficiently remove organic matter, inorganic salts, and other complex compounds from the filter cloth, while avoiding the formation of composite precipitates by the reaction of metal ions with other substances during the cleaning process, ensuring that the filter cloth pores are not clogged again. Secondly, through strict control of process parameters, such as specific temperature, time, and solution concentration, the performance of the filter cloth is significantly improved. The air permeability of the filter cloth can be restored to more than 98.5% of the original filter cloth, and the tensile strength can be restored to more than 97% of the original filter cloth, greatly improving the reuse rate of the filter cloth.

[0012] The expired filter cloth with secondary utilization value mentioned in step S1 refers to the filter cloth whose filtration performance has decreased due to being blocked by complex compounds during the solid-liquid separation step after rare earth concentrate is leached by concentrated sulfuric acid decomposition water.

[0013] The filter cloth is made of PP, PE, PPS, PET, or PTFE.

[0014] The activator mentioned in step S1 is a mixed solution of a strong base and a surfactant, wherein the molar ratio of the strong base to the surfactant is 1-6:1.

[0015] The mass fraction of all solutes in the mixed solution is 30%-70%.

[0016] The strong base is one or more of NaOH, KOH, NaNH2, and KNH2.

[0017] The surfactant is one or more of alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyoxyethylene polyoxypropylene ether, betaine, and fatty amine polyoxyethylene ether.

[0018] Its beneficial effects are as follows: the activator used in this invention is different from traditional solvents and has never been reported in similar literature. Moreover, the use of this activator improves the effect of subsequent acid dissolution by more than 70%.

[0019] The high-temperature steam blowing activation in step S1 is carried out at a temperature of 120-160℃ for 5-20 minutes.

[0020] Its beneficial effects are as follows: the main function of high-temperature activation is to efficiently activate solid organic pollutants. The surface and pores of the filter cloth are filled with organic matter and metal salts, which are difficult to dissolve in water and are difficult to remove even with acids and alkalis alone. The filter cloth is also easily damaged in ordinary strong alkaline solutions. The high-temperature activation method can effectively improve the hydrophilicity of the filter cloth surface, activate organic complex ions, and promote the subsequent acid dissolution effect. This method has not been seen in the rare earth field, nor in other fields, for treating complex solid substances.

[0021] Excessive activation temperature can damage the filter cloth matrix. After extensive research, it has been determined that the high-temperature activation temperature is 120-160℃ and the activation time is 5-20 minutes. This results in a rapid increase of more than two times in the subsequent acid dissolution effect without damaging the matrix structure of the filter cloth.

[0022] Step S1 not only applied a new formula but also a new process. Under the operation of this formula and process, a very significant effect was achieved in removing contaminants from the surface of the filter cloth.

[0023] The strong acid solution mentioned in step S2 is one or more of HCl, H2SO4, HNO3, HF, CF3SO3H, and C5H5SO3H; the concentration of the acid solution is 0.5-8 mol / L, and the temperature is 25-95℃.

[0024] Its beneficial effects are as follows: After removing solid organic impurities from the filter cloth surface in step S1, the acid can effectively react with the solid substances on the filter cloth surface through dissolution and complexation. Controlling the acid concentration is crucial for a complete reaction, while also ensuring that the filter cloth is not damaged. Therefore, this concentration was determined through extensive experimental verification. This acid concentration and temperature range ensures that the filter cloth is not damaged during the cleaning process while thoroughly removing contaminants.

[0025] The ultrasonic immersion treatment in step S2 has a frequency of 20kHz-40kHz and a duration of 10-60min.

[0026] Its beneficial effects are that the soaking time determines whether the solid substances are fully decomposed, while ensuring that the filter cloth material itself is not damaged. Soaking for 10-60 minutes is the result of extensive experimental verification. This time range significantly improves the cleaning effect of the filter cloth.

[0027] The surface treatment in step S3 involves immersing the filter cloth in a surface treatment solution for 1-10 minutes.

[0028] The surface treatment solution consists of 1-30 wt% 3-aminopropyltrimethoxysilane or 3-chloropropyltrimethoxysilane, 0.1-15 wt% alkylbenzene sulfonate or alcohol ether sulfate, 0.1-15 wt% polyvinyl alcohol or polyacrylic acid, 0.1-5 wt% polyurethane, 0.1-5 wt% tetrafluoroethylene or polyvinyl fluoride, with the remainder being water and ethanol, in a water:ethanol volume ratio of 5-10:1.

[0029] The beneficial effects are as follows: 3-aminopropyltrimethoxysilane (APTMS) or 3-chloropropyltrimethoxysilane can effectively increase the hydrophobicity of the filter cloth surface; alkylbenzene sulfonates or alcohol ether sulfates can effectively improve the permeability of the filter cloth; polyurethane, tetrafluoroethylene (PTFE), or polyvinyl fluoride (PVDF) can improve the flexibility of the filter cloth; and water and ethanol mainly serve as solvent media. After preparing the surface treatment agent according to the given ratio, it can significantly improve the performance of the regenerated filter cloth, further ensuring the air permeability and strength of the filter cloth. The ratio and component selection of the surface treatment solution ensure a comprehensive improvement in the performance of the filter cloth during the regeneration process.

[0030] The heat setting treatment in step S3 is a high-pressure steam treatment at 120-200℃ for 5-15 minutes.

[0031] Its beneficial effects are as follows: the main function of high-pressure steam setting treatment is to make the modified liquid adsorbed on the surface of the filter cloth more stable and durable, while also ensuring the uniformity, smoothness, and aesthetics of the filter cloth pores. The setting of this treatment time and temperature range significantly improves the stability and durability of the filter cloth.

[0032] The present invention also claims protection for the regenerated filter cloth prepared by the above method, wherein the air permeability of the regenerated filter cloth is restored to more than 98.5% of that of the original new filter cloth, and the tensile strength is restored to more than 97% of that of the original new filter cloth.

[0033] As can be seen from the above technical solutions, compared with the prior art, the present invention discloses a method for regenerating filter cloth of rare earth roasted ore water leaching solution, which achieves the following beneficial effects: (1) In the current filter cloth cleaning technology field, traditional methods are difficult to avoid the thorny problem of metal ions reacting with cleaning agents to produce precipitates, leading to secondary blockage. However, the present invention innovatively adopts a step-by-step treatment method of high temperature activation and acid solution, which effectively removes complex pollutants such as organic matter, inorganic salts and metal ions accumulated on the surface and inside the mesh of the filter cloth, completely solving the long-standing pain point of the industry and bringing unexpected technical breakthroughs.

[0034] (2) In the prior art, the setting of filter cloth performance recovery parameters is usually limited, and the performance of the filter cloth after cleaning and regeneration is difficult to reach a high level. However, after treatment by the method of the present invention, the air permeability of the filter cloth is restored to more than 98.5% of the original filter cloth, and the tensile strength is restored to more than 97% of the original filter cloth. The filtration efficiency of the regenerated filter cloth is almost at the original level, far exceeding the performance recovery level of similar technologies, which greatly meets the high requirements for filter cloth performance in the treatment of rare earth roasted ore water leaching solution, and breaks the conventional selection of filter cloth performance recovery parameters in the prior art.

[0035] (3) Through scientific cleaning and surface modification treatment, this invention not only effectively restores the filtration performance of the filter cloth, but also enhances its anti-fouling ability and mechanical strength, which is an extremely rare comprehensive effect in the prior art. This invention greatly extends the service life of the filter cloth, significantly reduces the replacement frequency and related costs, and brings significant economic and environmental benefits to the industry, demonstrating unexpected technical value. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 The process flow diagram of this invention.

[0038] Figure 2 XRD comparison chart of regenerated filter cloth. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention discloses a method for regenerating filter cloth from rare earth roasted ore leaching solution.

[0041] Example 1

[0042] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. An activator with a molar ratio of NaOH to fatty alcohol polyoxyethylene ether of 1:1 and a total mass fraction of 30% of solute is prepared. The screened filter cloth is activated by high-temperature steam blowing through the activator at a temperature of 120℃ for 20min.

[0043] (2) The filter cloth activated by high temperature steam is placed in a 0.5 mol / L HCl solution and soaked under ultrasonic frequency of 40 kHz. The soaking temperature is 60℃ and the soaking time is 60 min. Then it is taken out and rinsed with water until the pH of the filter cloth surface is 6.7.

[0044] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution and soaked for 10 minutes. The surface treatment solution contains 30 wt% of 3-aminopropyltrimethoxysilane (APTMS), 0.1 wt% of alkylbenzene sulfonate, 10 wt% of polyvinyl alcohol (PVA), 3 wt% of polyurethane (PU), 5 wt% of tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 10:1.

[0045] Then it is taken out and subjected to high-pressure steam setting at 120℃ for 5 minutes to obtain the final regenerated filter cloth.

[0046] After testing, the air permeability of the regenerated filter cloth was restored to 98.6% of that of the original filter cloth, and the tensile strength was restored to 97.2% of that of the original new filter cloth.

[0047] Example 2

[0048] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. An activator with KOH and polyoxyethylene polyoxypropylene ether molar ratio of 2:1 and a total solute mass fraction of 50% is prepared. The screened filter cloth is activated by high-temperature steam blowing through the activator at a temperature of 130℃ for 15 minutes.

[0049] (2) The filter cloth activated by high temperature steam is placed in a mixed solution of H2SO4 and HNO3, wherein the concentration of H2SO4 is 3 mol / L and the concentration of HNO3 is 3 mol / L; it is soaked under ultrasonic frequency of 30 kHz, the soaking temperature is 25℃ and the time is 30 min; then it is taken out and rinsed with water until the pH of the filter cloth surface is 7.

[0050] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution for 5 minutes. The surface treatment solution contains 1 wt% of 3-aminopropyltrimethoxysilane (APTMS), 15 wt% of alkylbenzene sulfonate, 8 wt% of polyvinyl alcohol (PVA), 2 wt% of polyurethane (PU), 1 wt% of tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 9:1.

[0051] Then it is taken out and subjected to high-pressure steam shaping treatment at 150℃ for 10 minutes to obtain the final regenerated filter cloth.

[0052] After testing, the air permeability of the regenerated filter cloth was restored to 98.7% of that of the original filter cloth, and the tensile strength was restored to 97.5% of that of the original new filter cloth.

[0053] Example 3

[0054] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. Prepare an activator with NaNH2 and betaine molar ratio of 3:1 and total solute mass fraction of 60%. Activate the screened filter cloth with high temperature steam blowing through the activator at a temperature of 140℃ for 10min.

[0055] (2) The filter cloth activated by high temperature steam is placed in a mixed solution of HF and C5H5SO3H, the concentration of HF in the mixed solution is 0.5mol / L and the concentration of C5H5SO3H is 2mol / L; it is soaked under ultrasonic frequency of 35kHz, the soaking temperature is 35℃ and the time is 20 min; then it is taken out and rinsed with water until the pH of the filter cloth surface is 6.1.

[0056] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution and soaked for 10 minutes. The surface treatment solution contains 15 wt% 3-aminopropyltrimethoxysilane (APTMS), 10 wt% alkylbenzene sulfonate, 0.1 wt% polyvinyl alcohol (PVA), 0.1 wt% polyurethane (PU), 5 wt% tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 8:1.

[0057] Then it is taken out and subjected to high-pressure steam shaping treatment at 150℃ for 15 minutes to obtain the final regenerated filter cloth.

[0058] After testing, the air permeability of the regenerated filter cloth was restored to 98.9% of that of the original filter cloth, and the tensile strength was restored to 97.7% of that of the original new filter cloth.

[0059] Example 4

[0060] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. An activator is prepared with KNH2 and fatty amine polyoxyethylene ether in a molar ratio of 2:1 and a total solute mass fraction of 70%. The screened filter cloth is activated by high-temperature steam blowing with the activator at a temperature of 150°C for 5 minutes.

[0061] (2) The filter cloth activated by high temperature steam was placed in a 4 mol / L H2SO4 solution and soaked under ultrasonic frequency of 25 kHz. The soaking temperature was 45℃ and the time was 10 min. Then it was taken out and rinsed with water until the pH of the filter cloth surface was 7.

[0062] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution for 8 minutes. The surface treatment solution contains 30 wt% 3-aminopropyltrimethoxysilane (APTMS), 15 wt% alkylbenzene sulfonate, 15 wt% polyvinyl alcohol (PVA), 5 wt% polyurethane (PU), 0.1 wt% tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 7:1.

[0063] Then it is taken out and subjected to high-pressure steam shaping treatment at 200℃ for 7 minutes to obtain the final regenerated filter cloth.

[0064] After testing, the air permeability of the regenerated filter cloth was restored to 99.4% of that of the original filter cloth, and the tensile strength was restored to 97.7% of that of the original new filter cloth.

[0065] Example 5

[0066] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. An activator with KNH2 and betaine in a molar ratio of 3:1 and a total mass fraction of 40% of solute is prepared. The screened filter cloth is activated by high-temperature steam blowing with the activator at a temperature of 160℃ for 18 minutes.

[0067] (2) The filter cloth activated by high temperature steam is placed in a solution of HNO3 and CF3SO3H. The concentration of HNO3 in the mixed solution is 1 mol / L and the concentration of CF3SO3H is 2 mol / L. The filter cloth is soaked under ultrasonic frequency of 35 kHz, the soaking temperature is 50℃ and the soaking time is 40 min. Then it is taken out and rinsed with water until the pH of the filter cloth surface is 6.3.

[0068] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution and soaked for 10 minutes. The surface treatment solution contains 10 wt% 3-aminopropyltrimethoxysilane (APTMS), 10 wt% alkylbenzene sulfonate, 5 wt% polyvinyl alcohol (PVA), 3 wt% polyurethane (PU), 3 wt% tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 6:1.

[0069] Then it is taken out and subjected to high-pressure steam setting at 200℃ for 9 minutes to obtain the final regenerated filter cloth.

[0070] After testing, the air permeability of the regenerated filter cloth was restored to 99.3% of that of the original filter cloth, and the tensile strength was restored to 98.5% of that of the original new filter cloth.

[0071] Example 6

[0072] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. Prepare an activator with NaOH and alkylphenol polyoxyethylene ether in a molar ratio of 1:1 and a total mass fraction of 55% of solute. Activate the screened filter cloth with high temperature steam blowing at 135℃ for 12 min.

[0073] (2) The filter cloth activated by high temperature steam is placed in a mixed solution of HCl and CF3SO3H, where the concentration of HCl is 6 mol / L and the concentration of CF3SO3H is 2 mol / L; it is soaked under ultrasonic frequency of 40 kHz, the soaking temperature is 25℃ and the time is 10 min; then it is taken out and rinsed with water until the pH of the filter cloth surface is 7.

[0074] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution for 6 minutes. The surface treatment solution contains 20 wt% 3-aminopropyltrimethoxysilane (APTMS), 7 wt% alkylbenzene sulfonate, 9 wt% polyvinyl alcohol (PVA), 1 wt% polyurethane (PU), 2 wt% tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 5:1.

[0075] Then it is taken out and subjected to high-pressure steam shaping treatment at 180℃ for 12 minutes to obtain the final regenerated filter cloth.

[0076] After testing, the air permeability of the regenerated filter cloth was restored to 98.8% of that of the original filter cloth, and the tensile strength was restored to 98.2% of that of the original new filter cloth.

[0077] Comparative Example 1

[0078] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. Prepare an activator with NaOH and fatty alcohol polyoxyethylene ether in a molar ratio of 8:1 and a total mass fraction of 30% of solute. Activate the screened filter cloth with high temperature steam blowing at 90℃ for 20min.

[0079] (2) The filter cloth activated by high temperature steam was placed in 0.4 mol / L HCl solution and soaked under ultrasonic frequency of 40 kHz. The soaking temperature was 60℃ and the soaking time was 60 min. Then it was taken out and rinsed with water until the pH of the filter cloth surface was 6.7.

[0080] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution for 10 minutes. The surface treatment solution contains 30 wt% of 3-aminopropyltrimethoxysilane (APTMS), 0.1 wt% of alkylbenzene sulfonate, 10 wt% of polyvinyl alcohol (PVA), 3 wt% of polyurethane (PU), 5 wt% of tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a volume ratio of water to ethanol of 4:1.

[0081] Then it is taken out and subjected to high-pressure steam setting at 120℃ for 4 minutes to obtain the final regenerated filter cloth.

[0082] After testing, the air permeability of the regenerated filter cloth was restored to 85% of that of the original filter cloth, and the tensile strength was restored to 80% of that of the original new filter cloth.

[0083] Comparative Example 2

[0084] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. An activator is prepared with KOH and polyoxyethylene polyoxypropylene ether in a molar ratio of 12:1 and a total mass fraction of 50% of solute. The screened filter cloth is activated by high-temperature steam at 130°C for 15 minutes.

[0085] (2) The filter cloth activated by high temperature steam is placed in a mixed solution of H2SO4 and HNO3, wherein the concentration of H2SO4 is 0.3mol / L and the concentration of HNO3 is 0.3mol / L; it is soaked under ultrasonic frequency of 30kHz, the soaking temperature is 85℃ and the time is 30 min; then it is taken out and rinsed with water until the pH of the filter cloth surface is 7.

[0086] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution for 5 minutes. The surface treatment solution contains 1 wt% of 3-aminopropyltrimethoxysilane (APTMS), 15 wt% of alkylbenzene sulfonate, 8 wt% of polyvinyl alcohol (PVA), 2 wt% of polyurethane (PU), 1 wt% of tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 20:1.

[0087] Then it is taken out and subjected to high-pressure steam shaping treatment at 150℃ for 20 minutes to obtain the final regenerated filter cloth.

[0088] After testing, the air permeability of the regenerated filter cloth was restored to 75% of that of the original filter cloth, and the tensile strength was restored to 70% of that of the original new filter cloth.

[0089] Comparative Example 3

[0090] (1) The screened filter cloth with secondary utilization value is specifically the filter cloth used for solid-liquid separation after rare earth concentrate is leached by concentrated sulfuric acid decomposition water. The filter cloth is blocked by complex compounds, resulting in a decrease in filtration performance. Prepare an activator with NaNH2 and betaine in a molar ratio of 15:1 and a total mass fraction of 60% of solute. Activate the screened filter cloth with high temperature steam at 140℃ for 10 min.

[0091] (2) The filter cloth activated by high temperature steam was placed in a 5 mol / L HNO3 solution and soaked under ultrasonic frequency of 60 kHz. The soaking temperature was 90 ℃ and the time was 20 min. Then it was taken out and rinsed with water until the pH of the filter cloth surface was 6.1.

[0092] (3) The filter cloth that has been activated at high temperature and soaked in strong acid is placed in the surface treatment solution and soaked for 10 minutes. The surface treatment solution contains 0.5 wt% 3-aminopropyltrimethoxysilane (APTMS), 10 wt% alkylbenzene sulfonate, 0.1 wt% polyvinyl alcohol (PVA), 0.1 wt% polyurethane (PU), 5 wt% tetrafluoroethylene (PTFE), and the remainder is water and ethanol, with a water to ethanol volume ratio of 25:1.

[0093] Then it is taken out and subjected to high-pressure steam shaping treatment at 150℃ for 30 minutes to obtain the final regenerated filter cloth.

[0094] After testing, the air permeability of the regenerated filter cloth was restored to 80% of that of the original filter cloth, and the tensile strength was restored to 75% of that of the original new filter cloth.

[0095] XRD characterization

[0096] XRD characterization was performed on the failed filter cloth, the alkaline-washed filter cloth, and some of the regenerated filter cloths in the examples. The results are shown in [Figure number missing]. Figure 2 As can be seen from the figure, the original diffraction peaks of the failed filter cloth have disappeared. This is because a layer of filter residue covers the surface of the filter cloth. After the filter cloth is treated by this technology, the original diffraction peaks of the filter cloth reappear, indicating that the filter residue on the surface has been removed more thoroughly.

[0097] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for regenerating a filter cloth for leaching of a rare earth roast ore aqueous solution, characterized in that, Specifically comprising the following steps: S1, the screened failure filter cloth with secondary utilization value is activated by high-temperature steam blowing with configured activator; The failure filter cloth with secondary utilization value refers to the filter cloth blocked by complex compounds and leading to the decline of filtering performance in the solid-liquid separation step using filter cloth after the rare earth concentrate is decomposed and leached by concentrated sulfuric acid; the material of the filter cloth is PP, PE, PPS, PET, PTFE; The activator is a mixed solution of strong base and surfactant, wherein the molar ratio of strong base to surfactant is 1-6:1; The mass fraction of all solutes in the mixed solution is 30%-70%; The strong base is one or more of NaOH, KOH, NaNH2, and KNH2; The surfactant is one or more of alkyl phenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, polyoxyethylene polyoxypropylene ether, betaine, and fatty amine polyoxyethylene ether; The temperature of the high-temperature steam blowing activation is 120-160℃, and the time is 5-20 min; S2, the filter cloth after S1 treatment is placed in a strong acid solution for ultrasonic immersion treatment, and then rinsed with water until the pH of the filter cloth surface is 6-7; The strong acid solution is one or more of HCl, H2SO4, HNO3, HF, CF3SO3H, and C5H5SO3H; the substance concentration of the acid solution is 0.5-8 mol / L, and the temperature is 25-95℃; The frequency of the ultrasonic immersion treatment is 20 kHz-40 kHz, and the time is 10-60 min; S3, the filter cloth after S2 treatment is subjected to surface treatment and then heat setting treatment to obtain the final regenerated filter cloth; The surface treatment is to immerse the filter cloth in a surface treatment liquid for 1-10 min; The surface treatment liquid is composed of 3-aminopropyltrimethoxysilane or 3-chloropropyltrimethoxysilane 1-30 wt%, alkyl benzene sulfonate or alcohol ether sulfate 0.1-15 wt%, polyvinyl alcohol or polyacrylic acid 0.1-15 wt%, polyurethane 0.1-5 wt%, tetrafluoroethylene or polyfluoroethylene 0.1-5 wt%, and the rest is water and ethanol, wherein the volume ratio of water to ethanol is 5-10:1; The heat setting treatment is 120-200℃ high-pressure steam treatment, and the treatment time is 5-15 min.

2. A regenerated filter cloth prepared by the method of claim 1, characterized in that, The air permeability of the regenerated filter cloth is restored to more than 98.5% of the original new filter cloth, and the breaking strength is restored to more than 97% of the original new filter cloth.

Images