A metal removal and recovery method for waste and old titanium anode plate

Abstract

The application relates to the technical field of metal recovery, in particular to a metal removal and recovery method for waste titanium anode plates; nanometer particles are subjected to a coating operation, cations are introduced to graft the coated nanometer particles, grafted nanometer particles are obtained, and the grafted nanometer particles are pretreated to obtain initial nanometer particles. In the application, the metal recovery of the waste titanium anode plates is realized through the synergistic effect of magnetic nanometer particle synthesis, functional modification and biological enzyme directional degradation; the surface of the nanometer particles is subjected to double-layer coating of silicon dioxide-polyacrylic acid and synergistic modification of carboxyl and amino groups, the adsorption capacity and selectivity to noble metal ions are enhanced, the noble metal ions are reduced to metal states through catalysis of an active enzyme solution, an integrated process of adsorption to degradation and then magnetic separation is formed between the noble metal ions and the functional nanometer particles, and after the titanium matrix is regenerated through pickling, high-value recovery and utilization of metal materials can be realized through smelting or powder metallurgy.

Description

Technical Field

[0001] This invention relates to the field of metal recycling technology, specifically to a method for removing and recycling metals from waste titanium anode plates. Background Technology

[0002] Waste titanium anode plates refer to anode electrodes made of titanium that no longer meet technical requirements or have reached the end of their service life after long-term use in industrial applications. These anode plates are usually used in electrochemical reactions, corrosion protection, or electrolysis processes, such as in the chlor-alkali industry or electrolytic aluminum production. Due to the excellent corrosion resistance and strength of titanium materials, waste titanium anode plates can be recycled after being scrapped. They have certain recycling value and reuse potential, and titanium metal or other valuable alloy materials can be obtained through smelting and reprocessing.

[0003] Traditional metal removal and recovery methods have several shortcomings. Traditional chemical coprecipitation methods often exhibit problems such as wide particle size distribution and weak magnetic responsiveness during the process, resulting in uneven quality of the recovered metal and low efficiency in subsequent separation and recovery stages. At the same time, functionalization modification technology usually only uses a single functional group, such as amino or carboxyl groups, resulting in limited adsorption capacity and poor selectivity, which cannot effectively improve the removal rate of metal ions. Secondly, the use of traditional dispersants also shows defects such as poor environmental performance and easy agglomeration, which increases the complexity of the process. Moreover, in the recovery process of titanium matrix, the purity of the recovered metal is often not high, which affects its subsequent application value.

[0004] Therefore, the present invention provides a method for metal removal and recycling of waste titanium anode plates to solve the aforementioned related technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide a method for metal removal and recycling of waste titanium anode plates. This method achieves metal recovery from waste titanium anode plates through the synergistic effect of magnetic nanoparticle synthesis, functionalization modification, and targeted degradation by bioenzymes. First, highly magnetically responsive nanoparticles are synthesized using hydrothermal coupling technology. The surface is then coated with a silica-polyacrylic acid double layer and synergistically modified with carboxyl and amino groups to enhance the adsorption capacity and selectivity for noble metal ions. The noble metal ions are then catalyzed by an active enzyme solution to reduce them to a metallic state, forming an integrated process from adsorption to degradation and then to magnetic separation with the functional nanoparticles. After acid washing and regeneration, the titanium matrix is ​​utilized at high value through smelting or powder metallurgy. The entire process relies on a green dispersant, tea polyphenols, to enhance the stability of the system.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for metal removal and recycling of waste titanium anode plates, the method comprising the following steps: Waste titanium anode plates are crushed, and the crushed waste titanium anode plates are acid-washed to obtain titanium-based products and metal solutions. Among them, the waste titanium anode plates are crushed, and the particle size of the crushed particles is ≤2mm.

[0007] Ferrous chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water were mixed in proportion to obtain a composite solution. The composite solution was then pretreated to obtain nanoparticles. The nanoparticles were coated, and cations were introduced to graft the coated nanoparticles to obtain grafted nanoparticles. The grafted nanoparticles were pretreated to obtain initial nanoparticles. Tea polyphenols were added to the initial nanoparticles to obtain functional nanoparticles. An active enzyme solution was prepared, and the active enzyme solution was mixed with functional nanoparticles to form a nanocomposite product. The nanocomposite product was dispersed in a metal solution to obtain metal particles, and the titanium-based product was processed to obtain titanium metal.

[0008] Furthermore, the steps for obtaining the titanium-based product and the metal solution specifically include: The crushed waste titanium anode plate was mixed with a dilute hydrochloric acid solution with a mass fraction of 8%, and stirred in a water bath at 45-55°C for 1-2 hours to obtain the initial pickling product and the first pickling solution. The initial pickling product was washed with deionized water to bring the pH to 6.8–7.2. The washed initial pickling product was then mixed with a 10% (w / w) dilute sulfuric acid solution and soaked at 55–65°C for 2–3 hours to obtain the titanium-based product and the second pickling solution. The metal solution is obtained by mixing a first pickling solution and a second pickling solution.

[0009] Furthermore, the composite solution is obtained by mixing ferric chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water in a mass ratio of 3-5:1-3:1:130-150 and then ultrasonically dispersing for 10-20 minutes.

[0010] Furthermore, the pretreatment of the composite solution includes: The composite solution was placed in a microwave reactor, the power was set to 300-310W and the temperature to 55-65℃, and sodium hydroxide solution was added dropwise while stirring until the pH reached 10.8-11.2, resulting in the formation of a black precipitate. The black precipitate was mixed with ethylene glycol at a mass ratio and hydrothermally treated at 175–185°C for 3.5–4.5 h to obtain nanoparticles.

[0011] Furthermore, the coating operation on the nanoparticles includes: Nanoparticles were mixed with ethanol at a solid-liquid ratio of 0.04–0.06 g / mL. Ammonia was added to adjust the pH to 9.4–9.6. After adjustment, 3%–5% tetraethyl orthosilicate by mass of the nanoparticles was added. The mixture was stirred at 35–45 °C for 5.5–6.5 h to obtain coated nanoparticles with a particle size of 10–30 nm.

[0012] Furthermore, the specific operation of introducing cations to graft the coated nanoparticles is as follows: The coated nanoparticles were mixed with deionized water at a mass ratio of 1:14-16. Then, 45%-55% of the mass of the coated nanoparticles of acrylic acid and 0.8%-1.2% of the mass of potassium persulfate were added. After the addition was completed, nitrogen gas was introduced and the reaction was carried out at 65-75°C for 3.5-4.5 hours to obtain grafted nanoparticles.

[0013] Furthermore, the pretreatment of the grafted nanoparticles includes: Grafted nanoparticles were dispersed in N,N-dimethylformamide at a solid-liquid ratio of 0.08–0.12 g / mL, and then ethylenediamine at a mass of 18%–22% of the grafted nanoparticles was added. The mixture was stirred at 75–85 °C for 8–10 h to form initial nanoparticles.

[0014] Furthermore, the process for obtaining functional nanoparticles is as follows: Tea polyphenols and deionized water are mixed at a mass ratio of 1:90-110 to form a dispersion. Initial nanoparticles with a mass of 10-12 times that of tea polyphenols are added to the dispersion, and the mixture is ultrasonically treated for 10-15 minutes to obtain functional nanoparticles.

[0015] Furthermore, the mixing of the active enzyme solution with the functional nanoparticles includes: The active enzyme solution and functional nanoparticles were mixed at a mass ratio of 1:90-110 to obtain a nanoenzyme solution. Glutaraldehyde, at a mass ratio of 15%-25% of the functional nanoparticles, was added to the nanoenzyme solution. The mixture was stirred at 23-27°C for 2-3 hours. After stirring, the mixture was washed 2-4 times with deionized water to obtain the nanocomposite product. The process of dispersing the nanocomposite product in a metal solution includes: The nanocomposite product is dispersed in a metal solution at a mass ratio of 1:9 to 11 and shaken at a constant temperature of 23 to 27°C for 2 to 3 hours to obtain a shaking solution. The shaking solution is then placed in a magnetic field and allowed to stand for 30 to 40 minutes to obtain a magnetic composite. The magnetic composite is then processed to obtain metal particles.

[0016] The strength of the magnetic field is 0.5T.

[0017] Furthermore, the treatment of the titanium-based product includes the following steps: The titanium-based product was mixed with the mixed solution in an equal mass ratio and stirred at 35–45°C for 1–2 hours. After stirring, the mixture was centrifuged and the centrifuged solid was collected. The centrifuged solid was washed with deionized water to bring the pH to 6.8–7.1 to obtain titanium metal. The mixed solution is obtained by mixing nitric acid, hydrofluoric acid and deionized water in a mass ratio of 2-4:1:15-18.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves metal recovery from waste titanium anode plates through the synergistic effect of magnetic nanoparticle synthesis, functionalization modification, and bio-enzyme-directed degradation. First, highly magnetically responsive iron(III) oxide nanoparticles are synthesized using hydrothermal coupling technology. The surface is coated with a silica-polyacrylic acid double layer and synergistically modified with carboxyl and amino groups to enhance the adsorption capacity and selectivity for noble metal ions. The noble metal ions are then catalyzed by an active enzyme solution to reduce them to a metallic state, forming an integrated process from adsorption to degradation and then to magnetic separation with the functional nanoparticles. After acid washing and regeneration, the titanium matrix is ​​utilized at high value through smelting or powder metallurgy. The entire process relies on tea polyphenol green dispersant to improve the stability of the system.

[0019] Through full-process optimization, the magnetic responsiveness and adsorption capacity of functional nanoparticles were significantly improved, while dispersion stability and antioxidant properties were enhanced, extending service life. The synergistic effect of active enzyme solution and nano-adsorption enabled efficient capture and directional degradation of precious metal ions. Magnetic separation technology ensured rapid solid-liquid separation and improved recovery efficiency. The titanium matrix recycling process achieved high-value utilization through smelting regeneration and powder metallurgy. Green synthesis and environmentally friendly treatment technologies reduced the use of toxic reagents and lowered the environmental burden. Attached Figure Description

[0020] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart illustrating the overall preparation of functional nanoparticles using the metal removal and recycling method for waste titanium anode plates according to the present invention; Figure 2 This is a general flowchart of the metal removal and recycling method for waste titanium anode plates according to the present invention. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0023] In this embodiment, unless otherwise specified, all raw materials are conventional commercial products. Among them, tea polyphenols were purchased from Anhui Anrui Biotechnology Co., Ltd., in powder form, with a solubility of approximately 3g / 100mL at 20°C. Furthermore, the preparation of the active enzyme solution is adjusted according to requirements. As a specific example, the preparation of the ruthenium-degrading enzyme solution includes mixing horseradish peroxidase with phosphate buffer at a mass ratio of 1:1000 to obtain a ruthenium-degrading enzyme solution with a concentration of 1 mg / mL.

[0024] The specific steps to obtain ruthenium metal particles are as follows: the magnetic complex, phosphate buffer and ruthenium degrading enzyme solution are mixed at a mass ratio of 1:10:1 and shaken at 37°C for 4 hours to obtain metal particles.

[0025] like Figure 1 and Figure 2 As shown, a method for metal removal and recycling of waste titanium anode plates includes the following steps: Waste titanium anode plates are crushed, and the crushed waste titanium anode plates are acid-washed to obtain titanium-based products and metal solutions. Among them, the waste titanium anode plates are crushed, and the particle size of the crushed particles is ≤2mm.

[0026] Ferrous chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water were mixed in proportion to obtain a composite solution. The composite solution was then pretreated to obtain nanoparticles. The nanoparticles were coated, and cations were introduced to graft the coated nanoparticles to obtain grafted nanoparticles. The grafted nanoparticles were pretreated to obtain initial nanoparticles. Tea polyphenols were added to the initial nanoparticles to obtain functional nanoparticles. An active enzyme solution was prepared, and the active enzyme solution was mixed with functional nanoparticles to form a nanocomposite product. The nanocomposite product was dispersed in a metal solution to obtain metal particles, and the titanium-based product was processed to obtain titanium metal.

[0027] Furthermore, the steps for obtaining the titanium-based product and the metal solution specifically include: The crushed waste titanium anode plate was mixed with a dilute hydrochloric acid solution with a mass fraction of 8% and stirred in a water bath at 45°C for 1 hour to obtain the initial pickling product and the first pickling solution. The initial pickling product was washed with deionized water to pH 6.8. The washed initial pickling product was then mixed with a 10% (w / w) dilute sulfuric acid solution and soaked at 55°C for 2 hours to obtain a titanium-based product and a second pickling solution. The metal solution is obtained by mixing a first pickling solution and a second pickling solution.

[0028] Furthermore, the composite solution is obtained by mixing ferric chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water in a mass ratio of 3:1:1:130 and then ultrasonically dispersing for 10 minutes.

[0029] Furthermore, the pretreatment of the composite solution includes: The composite solution was placed in a microwave reactor, the power was set to 300W and the temperature to 55℃, and sodium hydroxide solution was added dropwise while stirring until the pH reached 10.8, resulting in the formation of a black precipitate. The black precipitate was mixed with ethylene glycol at a certain mass ratio and then hydrothermally treated at 175°C for 3.5 hours to obtain nanoparticles.

[0030] Furthermore, the coating operation on the nanoparticles includes: Nanoparticles were mixed with ethanol at a solid-liquid ratio of 0.04 g / mL, and ammonia was added to adjust the pH to 9.4. After adjustment, tetraethyl orthosilicate (3% by mass of nanoparticles) was added, and the mixture was stirred at 35°C for 5.5 h to obtain coated nanoparticles with a particle size of 10 nm.

[0031] Furthermore, the specific operation of introducing cations to graft the coated nanoparticles is as follows: The coated nanoparticles were mixed with deionized water at a mass ratio of 1:14. Then, acrylic acid (45% by mass of the coated nanoparticles) and potassium persulfate (0.8% by mass) were added. After the addition was completed, nitrogen gas was introduced and the mixture was reacted at 65°C for 3.5 hours to obtain grafted nanoparticles.

[0032] Furthermore, the pretreatment of the grafted nanoparticles includes: Grafted nanoparticles were dispersed in N,N-dimethylformamide at a solid-liquid ratio of 0.08 g / mL, and then ethylenediamine (18% by mass of the grafted nanoparticles) was added. The mixture was stirred at 75°C for 8 hours to form the initial nanoparticles.

[0033] Furthermore, the process for obtaining functional nanoparticles is as follows: Tea polyphenols and deionized water were mixed at a mass ratio of 1:90 to form a dispersion. Initial nanoparticles with a mass of 10 times that of tea polyphenols were added to the dispersion, and the mixture was ultrasonically treated for 10 minutes to obtain functional nanoparticles.

[0034] Furthermore, the mixing of the active enzyme solution with the functional nanoparticles includes: The active enzyme solution and functional nanoparticles were mixed at a mass ratio of 1:90 to obtain a nanoenzyme solution. Glutaraldehyde, which accounts for 15% of the mass of the functional nanoparticles, was added to the nanoenzyme solution. The mixture was stirred at 23°C for 2 hours. After stirring, the mixture was washed twice with deionized water to obtain the nanocomposite product. The process of dispersing the nanocomposite product in a metal solution includes: The nanocomposite product was dispersed in a metal solution at a mass ratio of 1:9 and shaken at 23°C for 2 hours to obtain a shaking solution. The shaking solution was then placed in a magnetic field and allowed to stand for 30 minutes to obtain a magnetic composite. The magnetic composite was then processed to obtain metal particles.

[0035] The strength of the magnetic field is 0.5T.

[0036] Furthermore, the treatment of the titanium-based product includes the following steps: The titanium-based product was mixed with the mixed solution in an equal mass ratio and stirred at 35°C for 1 hour. After stirring, the mixture was centrifuged and the centrifuged solid was collected. The centrifuged solid was washed with deionized water until the pH reached 6.8 to obtain titanium metal. The mixed solution is obtained by mixing nitric acid, hydrofluoric acid and deionized water in a mass ratio of 2:1:15.

[0037] Example 2 The preparation method of the metal removal and recycling method for waste titanium anode plates provided in this embodiment is basically the same as that in Embodiment 1. The main difference between the two lies in the specific composition and ratio of the raw materials used. The specific composition of the raw materials used in this embodiment is as follows: The metal removal and recycling method includes the following steps: Waste titanium anode plates are crushed, and the crushed waste titanium anode plates are acid-washed to obtain titanium-based products and metal solutions. Among them, the waste titanium anode plates are crushed, and the particle size of the crushed particles is ≤2mm.

[0038] Ferrous chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water were mixed in proportion to obtain a composite solution. The composite solution was then pretreated to obtain nanoparticles. The nanoparticles were coated, and cations were introduced to graft the coated nanoparticles to obtain grafted nanoparticles. The grafted nanoparticles were pretreated to obtain initial nanoparticles. Tea polyphenols were added to the initial nanoparticles to obtain functional nanoparticles. An active enzyme solution was prepared, and the active enzyme solution was mixed with functional nanoparticles to form a nanocomposite product. The nanocomposite product was dispersed in a metal solution to obtain metal particles, and the titanium-based product was processed to obtain titanium metal.

[0039] Furthermore, the steps for obtaining the titanium-based product and the metal solution specifically include: The crushed waste titanium anode plate was mixed with a dilute hydrochloric acid solution with a mass fraction of 8% and stirred in a water bath at 55°C for 2 hours to obtain the initial pickling product and the first pickling solution. The initial pickling product was washed with deionized water to pH 7.2. The washed initial pickling product was then mixed with a 10% (w / w) dilute sulfuric acid solution and soaked at 65°C for 3 hours to obtain a titanium-based product and a second pickling solution. The metal solution is obtained by mixing a first pickling solution and a second pickling solution.

[0040] Furthermore, the composite solution is obtained by mixing ferric chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water in a mass ratio of 5:3:1:150 and then ultrasonically dispersing for 20 minutes.

[0041] Furthermore, the pretreatment of the composite solution includes: The composite solution was placed in a microwave reactor, the power was set to 310W and the temperature to 65℃, and sodium hydroxide solution was added dropwise while stirring until the pH reached 11.2, resulting in the formation of a black precipitate. The black precipitate was mixed with ethylene glycol at a certain mass ratio and then hydrothermally treated at 185°C for 4.5 hours to obtain nanoparticles.

[0042] Furthermore, the coating operation on the nanoparticles includes: Nanoparticles were mixed with ethanol at a solid-liquid ratio of 0.06 g / mL, and ammonia was added to adjust the pH to 9.6. After adjustment, 5% tetraethyl orthosilicate by mass of the nanoparticles was added, and the mixture was stirred at 45°C for 6.5 h to obtain coated nanoparticles with a particle size of 30 nm.

[0043] Furthermore, the specific operation of introducing cations to graft the coated nanoparticles is as follows: The coated nanoparticles were mixed with deionized water at a mass ratio of 1:16. Then, acrylic acid (55% by mass of the coated nanoparticles) and potassium persulfate (1.2% by mass) were added. After the addition was completed, nitrogen gas was introduced and the mixture was reacted at 75°C for 4.5 hours to obtain grafted nanoparticles.

[0044] Furthermore, the pretreatment of the grafted nanoparticles includes: Grafted nanoparticles were dispersed in N,N-dimethylformamide at a solid-liquid ratio of 0.12 g / mL, and then ethylenediamine (22% by mass of the grafted nanoparticles) was added. The mixture was stirred at 85°C for 10 h to form the initial nanoparticles.

[0045] Furthermore, the process for obtaining functional nanoparticles is as follows: Tea polyphenols and deionized water were mixed at a mass ratio of 1:110 to form a dispersion. Initial nanoparticles with a mass of 12 times that of tea polyphenols were added to the dispersion, and the mixture was ultrasonically treated for 15 minutes to obtain functional nanoparticles.

[0046] Furthermore, the mixing of the active enzyme solution with the functional nanoparticles includes: The active enzyme solution and functional nanoparticles were mixed at a mass ratio of 1:110 to obtain a nanoenzyme solution. Glutaraldehyde, which accounts for 25% of the mass of the functional nanoparticles, was added to the nanoenzyme solution. The mixture was stirred at 27°C for 3 hours. After stirring, the mixture was washed four times with deionized water to obtain the nanocomposite product. The process of dispersing the nanocomposite product in a metal solution includes: The nanocomposite product was dispersed in a metal solution at a mass ratio of 1:11 and shaken at 27°C for 3 hours to obtain a shaking solution. The shaking solution was then placed in a magnetic field and allowed to stand for 40 minutes to obtain a magnetic composite. The magnetic composite was then processed to obtain metal particles.

[0047] The strength of the magnetic field is 0.5T.

[0048] Furthermore, the treatment of the titanium-based product includes the following steps: The titanium-based product was mixed with the mixed solution in an equal mass ratio and stirred at 45°C for 2 hours. After stirring, the mixture was centrifuged and the centrifuged solid was collected. The centrifuged solid was washed with deionized water until the pH reached 7.1 to obtain titanium metal. The mixed solution is obtained by mixing nitric acid, hydrofluoric acid and deionized water in a mass ratio of 4:1:18.

[0049] Example 3 The preparation method of the metal removal and recycling method for waste titanium anode plates provided in this embodiment is basically the same as that in Embodiment 1. The main difference between the two lies in the specific composition and ratio of the raw materials used. The specific composition of the raw materials used in this embodiment is as follows: The metal removal and recycling method includes the following steps: Waste titanium anode plates are crushed, and the crushed waste titanium anode plates are acid-washed to obtain titanium-based products and metal solutions. Among them, the waste titanium anode plates are crushed, and the particle size of the crushed particles is ≤2mm.

[0050] Ferrous chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water were mixed in proportion to obtain a composite solution. The composite solution was then pretreated to obtain nanoparticles. The nanoparticles were coated, and cations were introduced to graft the coated nanoparticles to obtain grafted nanoparticles. The grafted nanoparticles were pretreated to obtain initial nanoparticles. Tea polyphenols were added to the initial nanoparticles to obtain functional nanoparticles. An active enzyme solution was prepared, and the active enzyme solution was mixed with functional nanoparticles to form a nanocomposite product. The nanocomposite product was dispersed in a metal solution to obtain metal particles, and the titanium-based product was processed to obtain titanium metal.

[0051] Furthermore, the steps for obtaining the titanium-based product and the metal solution specifically include: The crushed waste titanium anode plate was mixed with a dilute hydrochloric acid solution with a mass fraction of 8% and stirred in a water bath at 50°C for 1.5 hours to obtain the initial pickling product and the first pickling solution. The initial pickling product was washed with deionized water to bring the pH to 7.0. The washed initial pickling product was then mixed with a 10% (w / w) dilute sulfuric acid solution and soaked at 60°C for 2.5 hours to obtain the titanium-based product and the second pickling solution. The metal solution is obtained by mixing a first pickling solution and a second pickling solution.

[0052] Furthermore, the composite solution is obtained by mixing ferric chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water in a mass ratio of 4:2:1:140 and then ultrasonically dispersing for 15 minutes.

[0053] Furthermore, the pretreatment of the composite solution includes: The composite solution was placed in a microwave reactor, the power was set to 305W and the temperature to 60℃, and sodium hydroxide solution was added dropwise while stirring until the pH reached 11, resulting in the formation of a black precipitate. The black precipitate was mixed with ethylene glycol at a certain mass ratio and hydrothermally treated at 180°C for 4 hours to obtain nanoparticles.

[0054] Furthermore, the coating operation on the nanoparticles includes: Nanoparticles were mixed with ethanol at a solid-liquid ratio of 0.05 g / mL, and ammonia was added to adjust the pH to 9.5. After adjustment, tetraethyl orthosilicate (4% by mass of nanoparticles) was added, and the mixture was stirred at 40°C for 6 h to obtain coated nanoparticles with a particle size of 20 nm.

[0055] Furthermore, the specific operation of introducing cations to graft the coated nanoparticles is as follows: The coated nanoparticles were mixed with deionized water at a mass ratio of 1:15. Then, acrylic acid (50% by mass of the coated nanoparticles) and potassium persulfate (1% by mass) were added. After the addition was completed, nitrogen gas was introduced and the mixture was reacted at 70°C for 4 hours to obtain grafted nanoparticles.

[0056] Furthermore, the pretreatment of the grafted nanoparticles includes: Grafted nanoparticles were dispersed in N,N-dimethylformamide at a solid-liquid ratio of 0.1 g / mL, and then ethylenediamine, accounting for 20% of the mass of the grafted nanoparticles, was added. The mixture was stirred at 80°C for 9 h to form the initial nanoparticles.

[0057] Furthermore, the process for obtaining functional nanoparticles is as follows: Tea polyphenols and deionized water were mixed at a mass ratio of 1:100 to form a dispersion. Initial nanoparticles with a mass of 11 times that of tea polyphenols were added to the dispersion, and the mixture was ultrasonically treated for 13 minutes to obtain functional nanoparticles.

[0058] Furthermore, the mixing of the active enzyme solution with the functional nanoparticles includes: The active enzyme solution and functional nanoparticles were mixed at a mass ratio of 1:100 to obtain a nanoenzyme solution. Glutaraldehyde, which accounts for 20% of the mass of the functional nanoparticles, was added to the nanoenzyme solution. The mixture was stirred at 25°C for 2.5 hours. After stirring, the mixture was washed three times with deionized water to obtain the nanocomposite product. The process of dispersing the nanocomposite product in a metal solution includes: The nanocomposite product was dispersed in a metal solution at a mass ratio of 1:10 and shaken at 25°C for 2.5 hours to obtain a shaking solution. The shaking solution was then placed in a magnetic field and allowed to stand for 35 minutes to obtain a magnetic composite. The magnetic composite was then processed to obtain metal particles.

[0059] The strength of the magnetic field is 0.5T.

[0060] Furthermore, the treatment of the titanium-based product includes the following steps: The titanium-based product was mixed with the mixed solution in an equal mass ratio and stirred at 40°C for 1.5 h. After stirring, the mixture was centrifuged and the centrifuged solid was collected. The centrifuged solid was washed with deionized water until the pH reached 7.0 to obtain titanium metal. The mixed solution is obtained by mixing nitric acid, hydrofluoric acid and deionized water in a mass ratio of 3:1:17.

[0061] Comparative Example 1: The preparation method and specific ratio of raw materials for a metal removal and recycling method for waste titanium anode plates provided in this embodiment are roughly the same as those in Example 1. The main difference is that an equal amount of initial nanoparticles are used to replace functional nanoparticles in this embodiment.

[0062] Comparative Example 2: The preparation method and specific ratio of raw materials for a metal removal and recycling method for waste titanium anode plates provided in this embodiment are roughly the same as those in Example 1. The main difference is that in this embodiment, an equal amount of grafted nanoparticles are used instead of functional nanoparticles.

[0063] Comparative Example 3: The preparation method and specific raw material ratio of the metal removal and recycling method for waste titanium anode plates provided in this embodiment are largely the same as those in Example 1. The main difference is that: in this embodiment, nanoparticles are prepared by chemical coprecipitation. The specific chemical coprecipitation method is as follows: Ferrous sulfate heptahydrate, ferric chloride hexahydrate, and deionized water were mixed in a mass ratio of 1:2:10 and sonicated for 10 min to obtain a homogeneous solution. The solution was heated to 80°C in a water bath, and sodium hydroxide solution was added dropwise while stirring until the pH reached 11. The reaction was carried out for 1 hour with nitrogen gas continuously introduced during the reaction to obtain the reaction product. The reaction product was washed three times with deionized water and dried in a vacuum drying oven at 60°C for 4 hours to obtain nanoparticles.

[0064] Effect test The metal removal and recycling methods for waste titanium anode plates described in Examples 1-3 of this invention are referred to as Experimental Examples 1-3; the metal removal and recycling methods for waste titanium anode plates described in Comparative Examples 1-3 are referred to as Comparative Examples 1-3; and then the performance of each group of metal removal and recycling methods for waste titanium anode plates in equal quantities is tested.

[0065] Experimental setup: Based on national standards, the recovery efficiency, precious metal purity, and titanium purity were tested. Each group was tested in triplicate, and the average value was taken to verify the feasibility of the process.

[0066] Recycling efficiency test: Test basis: Referring to the "Technical Specification for Recycling and Utilization of Solid Waste Containing Non-ferrous Metals" (GB / T41012-2021), the ratio of the total mass of recycled metal to the total mass of raw metal was calculated. The experimental results are detailed in Table 1. Table 1: Recovery Efficiency Table All examples were satisfactory. The modification with tea polyphenols enhanced the adsorption capacity of the nanoparticles for metal ions. Example 2 showed the best efficiency after optimizing acid washing and reaction parameters. Comparative Examples 1 and 2, which used initial / grafted nanoparticles to replace the functional type, exhibited weak adsorption. Comparative Example 3, which used a chemical co-precipitation method to prepare nanoparticles, showed poor dispersion and low efficiency.

[0067] Purity testing for recycled precious metals: Test basis: Following the "Regulations and Naming Methods for the Purity of Precious Metals in Jewelry" (GB11887-2012), the purity was calculated by detecting the total impurity content, focusing on the ruthenium metal purity index. The data results are shown in Table 2. Table 1: Purity of Recovered Ruthenium Metal The purity of the examples met the standards. Tea polyphenol modification improved the selective adsorption of precious metals by the nanoparticles and reduced impurity entrainment. Example 2 showed the best selectivity after parameter optimization. Comparative Examples 1 and 2, without tea polyphenol modification, had poor selectivity; Comparative Example 3 had uneven nanoparticle size, resulting in more adsorbed impurities and purity failing to meet the acceptable level.

[0068] Purity testing of recycled titanium: Test method: Referencing the "Chemical Analysis Methods for Titanium and Titanium Alloys" (GB / T4698-2017), impurity content was determined using spectroscopic methods. The example used a stepwise acid pickling and nanocomposite product synergistic impurity removal process. Table 3: Purity of Recycled Titanium In the examples, the titanium purity met the standards. Stepwise acid washing and nanocomposite products were used to remove impurities in synergy. In Example 2, the acid washing temperature and time were optimized, and the impurities were removed more thoroughly. In Comparative Examples 1 and 2, the nanoparticles were not modified and could not fully adsorb the impurities in the solution, leaving residues in the titanium base. In Comparative Example 3, the adsorption capacity of the nanoparticles was insufficient, and the titanium base impurities were too high.

[0069] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0070] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for metal removal and recycling of waste titanium anode plates, characterized in that: The metal removal and recycling method includes the following steps: Waste titanium anode plates are crushed, and the crushed waste titanium anode plates are acid-washed to obtain titanium-based products and metal solutions. Ferrous chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water were mixed in proportion to obtain a composite solution. The composite solution was then pretreated to obtain nanoparticles. The nanoparticles were coated, and cations were introduced to graft the coated nanoparticles to obtain grafted nanoparticles. The grafted nanoparticles were pretreated to obtain initial nanoparticles. Tea polyphenols were added to the initial nanoparticles to obtain functional nanoparticles. An active enzyme solution was prepared, and the active enzyme solution was mixed with functional nanoparticles to form a nanocomposite product. The nanocomposite product was dispersed in a metal solution to obtain metal particles, and the titanium-based product was processed to obtain titanium metal.

2. The method for metal removal and recycling of waste titanium anode plates according to claim 1, characterized in that: The specific steps for obtaining the titanium-based product and the metal solution are as follows: The crushed waste titanium anode plate was mixed with a dilute hydrochloric acid solution with a mass fraction of 8%, and stirred in a water bath at 45-55°C for 1-2 hours to obtain the initial pickling product and the first pickling solution. The initial pickling product was washed with deionized water to bring the pH to 6.8–7.

2. The washed initial pickling product was then mixed with a 10% (w / w) dilute sulfuric acid solution and soaked at 55–65°C for 2–3 hours to obtain the titanium-based product and the second pickling solution. The metal solution is obtained by mixing a first pickling solution and a second pickling solution.

3. The method for metal removal and recycling of waste titanium anode plates according to claim 2, characterized in that: The composite solution is obtained by mixing ferric chloride hexahydrate, ferrous sulfate heptahydrate, sodium citrate and deionized water in a mass ratio of 3-5:1-3:1:130-150 and then ultrasonically dispersing for 10-20 minutes.

4. The method for metal removal and recycling of waste titanium anode plates according to claim 2, characterized in that: The pretreatment of the composite solution includes: The composite solution was placed in a microwave reactor, the power was set to 300-310W and the temperature to 55-65℃, and sodium hydroxide solution was added dropwise while stirring until the pH reached 10.8-11.2, resulting in the formation of a black precipitate. The black precipitate was mixed with ethylene glycol at a mass ratio and hydrothermally treated at 175–185°C for 3.5–4.5 h to obtain nanoparticles.

5. The method for metal removal and recycling of waste titanium anode plates according to claim 2, characterized in that: The coating operation on the nanoparticles includes: Nanoparticles were mixed with ethanol at a solid-liquid ratio of 0.04–0.06 g / mL. Ammonia was added to adjust the pH to 9.4–9.

6. After adjustment, 3%–5% tetraethyl orthosilicate (by mass of nanoparticles) was added. The mixture was stirred at 35–45 °C for 5.5–6.5 h to obtain coated nanoparticles.

6. The method for metal removal and recycling of waste titanium anode plates according to claim 1, characterized in that: The specific operation of introducing cations to graft the coated nanoparticles is as follows: The coated nanoparticles were mixed with deionized water at a mass ratio of 1:14-16. Then, 45%-55% of the mass of the coated nanoparticles of acrylic acid and 0.8%-1.2% of the mass of potassium persulfate were added. After the addition was completed, nitrogen gas was introduced and the reaction was carried out at 65-75°C for 3.5-4.5 hours to obtain grafted nanoparticles.

7. A method for metal removal and recycling of waste titanium anode plates according to claim 6, characterized in that: The pretreatment of the grafted nanoparticles includes: Grafted nanoparticles were dispersed in N,N-dimethylformamide at a solid-liquid ratio of 0.08–0.12 g / mL, and then ethylenediamine at a mass of 18%–22% of the grafted nanoparticles was added. The mixture was stirred at 75–85 °C for 8–10 h to form initial nanoparticles.

8. The method for metal removal and recycling of waste titanium anode plates according to claim 6, characterized in that: The process for obtaining functional nanoparticles is as follows: Tea polyphenols and deionized water are mixed at a mass ratio of 1:90-110 to form a dispersion. Initial nanoparticles with a mass of 10-12 times that of tea polyphenols are added to the dispersion, and the mixture is ultrasonically treated for 10-15 minutes to obtain functional nanoparticles.

9. The method for metal removal and recycling of waste titanium anode plates according to claim 1, characterized in that: The process of mixing the active enzyme solution with functional nanoparticles includes: The active enzyme solution and functional nanoparticles were mixed at a mass ratio of 1:90-110 to obtain a nanoenzyme solution. Glutaraldehyde, at a mass ratio of 15%-25% of the functional nanoparticles, was added to the nanoenzyme solution. The mixture was stirred at 23-27°C for 2-3 hours. After stirring, the mixture was washed 2-4 times with deionized water to obtain the nanocomposite product. The process of dispersing the nanocomposite product in a metal solution includes: The nanocomposite product is dispersed in a metal solution at a mass ratio of 1:9 to 11 and shaken at a constant temperature of 23 to 27°C for 2 to 3 hours to obtain a shaking solution. The shaking solution is then placed in a magnetic field and allowed to stand for 30 to 40 minutes to obtain a magnetic composite. The magnetic composite is then processed to obtain metal particles.

10. The method for metal removal and recycling of waste titanium anode plates according to claim 1, characterized in that: The treatment of the titanium-based product includes the following steps: The titanium-based product was mixed with the mixed solution in an equal mass ratio and stirred at 35–45°C for 1–2 hours. After stirring, the mixture was centrifuged and the centrifuged solid was collected. The centrifuged solid was washed with deionized water to bring the pH to 6.8–7.1 to obtain titanium metal. The mixed solution is obtained by mixing nitric acid, hydrofluoric acid and deionized water in a mass ratio of 2-4:1:15-18.

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