Electrolytic preparation method of high-purity lead material

Abstract

The application belongs to the technical field of electrolytic metallurgy, and provides an electrolytic preparation method of high-purity lead material. The application takes lead sulfate-containing solid obtained after disassembling waste lead-acid batteries as raw material, obtains lead carbonate microparticles through sodium carbonate aqueous phase conversion, obtains derivative core-shell lead carbonate by alternately assembling a shell layer using polydiallyldimethylammonium chloride and sodium polystyrene sulfonate, and prepares a dispersion of derivative ion cross-linked nanoparticles, so as to obtain metal lead through pre-electrolysis purification and electrolytic deposition in methanesulfonic acid electrolyte. Through synergistic effect of the polyelectrolyte shell layer and the nanoparticles, the application realizes stable lead supply and dense and smooth deposition under high current density, the purity of lead reaches more than 99.99%, the current efficiency is high, and the growth of dendrites is effectively inhibited. The application solves the contradiction among lead supply stability, interface morphology control and current efficiency in high-purity lead electro-deposition, provides a green and efficient technical path for high-value recycling of waste lead-acid batteries, and has good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of electrolytic metallurgy, specifically to a method for the electrolytic preparation of high-purity lead materials. Background Technology

[0002] High-purity lead materials, as important industrial raw materials, hold an irreplaceable position in electronics, chemicals, medical protection, and nuclear energy. The electronics industry's demand for ultra-high purity lead continues to grow, requiring purity levels of 99.99% or higher for the manufacture of precision electronic components and special alloys. The chemical industry requires high-purity lead as a catalyst carrier and corrosion-resistant material for special chemical reactors. The medical protection and nuclear industries have stringent requirements for the purity and density of lead materials to ensure radiation shielding effectiveness and long-term stability. With increasingly stringent environmental regulations and the deepening of the concept of resource recycling, the recovery of high-purity lead materials from waste lead-acid batteries has become an important technological path that balances economic benefits and environmental protection. Waste lead-acid batteries are the world's largest source of lead recycling, with an annual production exceeding ten million tons, of which lead content accounts for 60-70%. Developing efficient and clean recycling technologies is of great significance for alleviating pressure on primary lead resources and reducing environmental pollution. However, preparing high-purity lead materials from waste lead-acid battery recyclables faces complex technical challenges, especially in achieving a dense and smooth deposition morphology while ensuring high purity, maintaining stable lead supply efficiency, and controlling reasonable current efficiency and energy consumption.

[0003] Currently, the mainstream technologies for recovering lead from waste lead-acid batteries include pyrometallurgy and hydrometallurgy, but each has its limitations. While pyrometallurgy is a mature process with a large processing capacity, it suffers from high energy consumption, significant pollutant emissions, and lead purity limitations imposed by smelting conditions. It typically yields only crude or refined lead, making it difficult to directly achieve the high purity requirement of 99.99% or higher. Hydrometallurgical refining technology is considered an effective way to obtain high-purity lead, but traditional sulfuric acid or fluorosilicic acid systems suffer from low current density, loose deposit layers, and severe impurity entrainment. For example, Chinese patent application CN103436849A discloses a crude lead refining method using a (1-hydroxyethylidene) diphosphonic acid, acidic ionic liquid, and 7,7'-iminobis(4-hydroxy-2-naphthalenesulfonic acid) electrolyte system, but it suffers from limited current density, dendrite formation in the deposit layer, and low lead recovery rate. For example, Chinese patent application CN110380137B discloses an electrolyte additive for lead-acid batteries and its preparation method. Although it increases the current density, it lacks effective control methods for stable lead supply, prevention of sedimentation and blockage, and suppression of dendrite growth under high current density when using solid lead compounds (such as lead sulfate and lead carbonate) as raw materials. Furthermore, it fails to solve the stability and side reaction problems of organic additives in strong acid electrochemical environments, resulting in large fluctuations in current efficiency and unstable product purity. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the electrolytic preparation of high-purity lead materials, which solves the mechanistic conflict between the requirements of high current density electrodeposition for a dense and flat deposition layer and the process window requirements under strong methanesulfonic acid medium and continuous circulating filtration conditions, and the problem of high viscosity and easy clogging caused by the stable lead supply and anti-settling of core-shell lead carbonate slurry and ion-crosslinked nanoparticles, as well as the cross-domain coupling problem between the dependence of interface morphology control on dendrite suppression and the stability of organic additives in a strong acid electrochemical environment.

[0005] This invention addresses the aforementioned problems by employing a design approach that combines the synergistic effect of polyelectrolyte ionic bond assembly of a core-shell structure with ionicly cross-linked nanoparticles. Derived core-shell lead carbonate is constructed by alternately assembling polydiallyldimethylammonium chloride and sodium polystyrene sulfonate on the surface of lead carbonate microparticles to form an ionic shell. This shell provides steric hindrance to prevent agglomeration and sedimentation, and also enables controlled dissolution and release of lead carbonate through the dynamic dissociation equilibrium of ionic bonds. Simultaneously, derived ionicly cross-linked nanoparticles are prepared. These nanoparticles form a stable network structure through ionic cross-linking between polyelectrolyte chains, playing multiple roles in the electrolyte, including thickening and anti-settling, regulating the interfacial double layer structure, and inducing uniform nucleation and smooth growth. The synergistic effect of the two intermediates in the methanesulfonic acid electrolyte system achieves a balance between stable lead supply at high current densities and dense, smooth deposition.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A method for electrolytically preparing high-purity lead material includes the following steps: S1. Disassemble the waste lead-acid battery, wash the obtained lead paste with deionized water and perform solid-liquid separation to obtain lead sulfate solid; use the lead sulfate solid as raw material, and use sodium carbonate in an aqueous phase with deionized water as medium to convert lead carbonate microparticles. S2. Using the lead carbonate microparticles as the core, polydiallyldimethylammonium chloride and sodium polystyrene sulfonate are alternately assembled on the surface of the lead carbonate microparticles to form a shell layer, thereby obtaining derived core-shell lead carbonate; S3. Polydiallyldimethylammonium chloride and sodium polystyrene sulfonate are compounded in an aqueous phase to obtain a dispersion of derivatized ion-crosslinked nanoparticles; S4. Prepare an aqueous solution of methanesulfonic acid, add the derived core-shell lead carbonate, and then add a dispersion of derived ion-crosslinked nanoparticles to obtain an electrolyte; S5. Pre-electrolyze the electrolyte obtained in step S4 at 20-45℃, with a pre-electrolysis current density of 5-50 A / m. 2 The time is 0.5-4 hours; S6. Electrolytic deposition is performed on the electrolyte obtained in step S5 at 20-45℃, with an electrolytic deposition current density of 100-400 A / m. 2 A metallic lead deposition layer is obtained at the cathode; the metallic lead deposition layer is washed with deionized water and dried to obtain high-purity lead material.

[0007] Furthermore, in step S4, the mass fraction of the methanesulfonic acid aqueous solution is 15-70%; the final concentration of dissolved divalent lead ions in the electrolyte is 2-100 g / L, and the amount of derived ion crosslinked nanoparticles added is 0.1-0.5 g / L based on their solid content.

[0008] Furthermore, the lead carbonate microparticles described in step S1 are prepared through the following steps: A1. Proportioning: Prepare a sodium carbonate aqueous solution, wherein the molar ratio of sodium carbonate to lead sulfate in the lead sulfate-containing solid is 1.05-1.20:1, wherein the total lead sulfate content in the lead sulfate-containing solid is calculated by taking a sample of the lead sulfate-containing solid and determining its lead sulfate content as PbSO4; A2. Conversion: Add lead sulfate solid to the deionized water to form a slurry with a solid content of 50-300 g / L. Add the sodium carbonate aqueous solution dropwise at a temperature of 20-70℃. During the dropwise addition, control the pH of the reaction system at 8.5-10.5. After the dropwise addition is completed, continue stirring the reaction. Stop the reaction when the pH of the reaction system fluctuates by no more than 0.5 within 0.5 h. A3. Post-processing: The reaction system is subjected to solid-liquid separation and washed with deionized water until the conductivity of the filtrate is not higher than 500 μS / cm. Then, it is dried at a temperature of 60-120℃ for 4-12 h to obtain the lead carbonate microparticles. The particle size D50 of the lead carbonate microparticles is 0.5-5 μm and the water content is not higher than 0.5%.

[0009] Furthermore, the derived core-shell lead carbonate described in step S2 is prepared through the following steps: B1. Pre-dispersion: The lead carbonate microparticles are added to deionized water to obtain a dispersion system with a solid content of 5-30%, and the pH of the dispersion system is adjusted to 3-8; B2. Anion layer assembly: Add an aqueous solution of sodium polystyrene sulfonate to the dispersion system obtained in step B1. The mass concentration of the sodium polystyrene sulfonate aqueous solution is 0.1-5%, and the amount of sodium polystyrene sulfonate added is 0.05-0.25% of the mass of the lead carbonate particles. Then stir at a temperature of 10-40℃ for 0.2-2 h, followed by solid-liquid separation and washing with deionized water. B3. Cationic layer assembly: Add an aqueous solution of polydiallyldimethylammonium chloride to the solid obtained in step B2. The mass concentration of the aqueous solution of polydiallyldimethylammonium chloride is 0.1-5%, and the amount of polydiallyldimethylammonium chloride added is 0.05-0.25% of the mass of the lead carbonate particles. Stir at a temperature of 10-40℃ for 0.2-2 h, then separate the solid and liquid and wash with deionized water. B4. Repeat assembly: Repeat steps B2-B3 2-10 times to obtain the intermediate; B5. Drying and quality control: Dry at a temperature of 40-90℃ for 4-12 h to obtain the derived core-shell lead carbonate.

[0010] Furthermore, the dispersion of the derived ion-crosslinked nanoparticles described in step S3 is prepared through the following steps: C1. Solution preparation: Prepare aqueous solutions of polydiallyldimethylammonium chloride and sodium polystyrene sulfonate, respectively, with a mass concentration of 0.05-2.0% for both solutions; C2. Composite nucleation: Under the condition of 10-40℃, an aqueous solution of polydiallyldimethylammonium chloride is added dropwise to an aqueous solution of sodium polystyrene sulfonate, such that the mass ratio of sodium polystyrene sulfonate to polydiallyldimethylammonium chloride is 0.5:1-2:1, and the mixture is stirred for 0.5-4 h. C3. Aging and post-treatment: The dispersion obtained in step C2 is allowed to stand for aging for 0.5-24 h and filtered to remove large particles to obtain a dispersion of derivatized ion crosslinked nanoparticles; the particle size D50 of the derivatized ion crosslinked nanoparticles in the obtained dispersion is 50-200 nm, and the PDI is not higher than 0.30, where PDI is the particle size distribution index.

[0011] Furthermore, the electrolyte used in step S4 of the method also includes a compound solution, the raw materials of which include gelatin and sodium lignosulfonate. The compound solution is prepared through the following steps: D1. Dissolution: Add gelatin to deionized water and stir at 40-70℃ for 0.5-2 h to obtain a gelatin solution with a mass fraction of 0.1-5%; D2. Compounding: Add sodium lignosulfonate to the gelatin solution to make the mass ratio of gelatin to sodium lignosulfonate 1:0.2-2, stir at 40-70℃ for 0.5-2 h, then adjust the pH of the solution to 1-4 with methanesulfonic acid, and make the total solid content of the resulting compound solution 0.2-5%.

[0012] Furthermore, in step S6, the electrolytic deposition uses a continuously circulating electrolyte and is filtered online with a pore size of 0.2-5 μm.

[0013] Furthermore, at least one of the cathodes used in step S5 and step S6 is a titanium cathode plate, and at least one of the anodes used in step S5 and step S6 is an inert anode.

[0014] Furthermore, the lead paste is washed with deionized water and subjected to solid-liquid separation to obtain lead sulfate solid. Specifically, the lead paste is washed with deionized water and subjected to solid-liquid separation to ensure that the conductivity of the filtrate is not higher than 2000 μS / cm, thereby obtaining lead sulfate solid.

[0015] Furthermore, the lead mass fraction of high-purity lead materials is not less than 99.99%.

[0016] Furthermore, in step A1, the sodium carbonate aqueous solution is prepared using deionized water, and the mass fraction of sodium carbonate in the sodium carbonate aqueous solution is 5-25%.

[0017] Furthermore, in step A2, the sodium carbonate aqueous solution is added over a period of 0.5-2 hours.

[0018] Furthermore, in step A2, the stirring reaction is carried out by mechanical stirring at a speed of 200-800 r / min.

[0019] Furthermore, in step B1, the pH adjuster used is an aqueous solution of methanesulfonic acid or an aqueous solution of sodium hydroxide, wherein the mass fraction of methanesulfonic acid in the aqueous solution is 10-70%, and the concentration of the aqueous solution of sodium hydroxide is 0.5-5.0 mol / L.

[0020] Furthermore, in steps B2 and B3, the solid-liquid separation and washing with deionized water includes washing with deionized water 2-5 times until the conductivity of the final washing solution is not higher than 2000 μS / cm.

[0021] Furthermore, in step C2, the mass ratio of sodium polystyrene sulfonate to polydiallyldimethylammonium chloride is the ratio of the dry basis mass of sodium polystyrene sulfonate to the dry basis mass of polydiallyldimethylammonium chloride.

[0022] Furthermore, in step C2, the stirring is carried out mechanically at a speed of 200-800 r / min.

[0023] Furthermore, in step C3, the filtration is performed using a filter membrane with a pore size of 0.45-5 μm.

[0024] Furthermore, in step D2, the mass ratio of gelatin to sodium lignosulfonate is the ratio of the dry weight of gelatin to the dry weight of sodium lignosulfonate.

[0025] Furthermore, in step D2, deionized water is added to make the total solid content of the resulting compound solution 0.2-5%.

[0026] Furthermore, the lead mass fraction of the high-purity lead material was determined using inductively coupled plasma atomic emission spectrometry.

[0027] Furthermore, the concentration of dissolved divalent lead ions in the electrolyte in step S4 is determined by the following method: An electrolyte sample is taken, filtered through a 0.22 μm acid-resistant filter membrane, and the Pb content in the filtrate is determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The concentration is then converted to the mass concentration of dissolved divalent lead ions based on Pb. Unless otherwise stated, the concentration or mass concentration of dissolved divalent lead ions in step S4 of the embodiments and comparative examples herein is determined by the aforementioned method.

[0028] Furthermore, in step S4, the electrolyte shows no visible sedimentation or stratification after standing at 25°C for 24 hours.

[0029] Furthermore, in step S4, the total solids added to the electrolyte by the compound solution are 0.01-5 g / L, based on the total solids content.

[0030] As a concept of this invention, the design of a polyelectrolyte ionic bond-assembled core-shell structure and ionicly cross-linked nanoparticles is mainly used to enhance the stable lead supply capacity of lead carbonate in the methanesulfonic acid electrolysis system, the density and flatness of the cathode deposition layer, and the current efficiency. The ionic bond shell layer formed by the alternating assembly of polydiallyldimethylammonium chloride and sodium polystyrene sulfonate effectively prevents the aggregation and sedimentation of lead carbonate particles in high-ionic-strength electrolytes through electrostatic repulsion and steric hindrance effects. The ionic bonds in the shell layer exist in a dynamic dissociation equilibrium in the methanesulfonic acid medium. As divalent lead ions near the cathode are consumed, the ionic bonds partially dissociate, releasing surface groups, promoting the controllable dissolution of lead carbonate, and achieving a continuous and stable supply of lead ions. Derivative ion-crosslinked nanoparticles form a stable three-dimensional network structure through multi-point ion crosslinking between polyelectrolyte chains. In the electrolyte, this network acts as a thickener and prevents sedimentation, thus preventing uneven lead supply caused by the gravitational settling of the core-shell lead carbonate intermediate. Simultaneously, the nanoparticles form a weak adsorption layer on the cathode surface, regulating the double-layer structure and electric field distribution at the cathode interface, reducing local current density peaks, inducing uniform nucleation of lead ions, and inhibiting dendrite and coarse grain growth. The synergistic effect of the polyelectrolyte shell and nanoparticles, without introducing easily oxidized or reduced small organic molecule additives, achieves interface morphology control and current efficiency optimization through physicochemical methods. This solves the problems of easy decomposition, numerous side reactions, and high product impurities associated with traditional organic additives under strong acid and high current density conditions, ensuring the stable preparation of high-purity lead materials.

[0031] In this invention, polydiallyldimethylammonium chloride (a cationic polyelectrolyte) and sodium polystyrene sulfonate (anionic polyelectrolyte) play a synergistic role in the electrolytic preparation of high-purity lead materials. Polydiallyldimethylammonium chloride, as a strong cationic polyelectrolyte, focuses on providing positive charge density and electrostatic adsorption capacity. Its quaternary ammonium groups maintain a permanently positive charge state in the strong acid medium of methanesulfonic acid, forming a positively charged adsorption layer on the surface of lead carbonate particles, providing electrostatic driving force for subsequent anionic polyelectrolyte assembly. Simultaneously, it acts as a positive charge anchor in the nanoparticle crosslinking system, forming a stable crosslinking network with sodium polystyrene sulfonate ion pairs. Sodium polystyrene sulfonate, as a strong anionic polyelectrolyte, focuses on providing negative charge density and hydrophilicity. Its sulfonic acid groups remain dissociated in acidic media, providing electrostatic repulsion in the shell structure to prevent particle aggregation. In nanoparticles, it acts as a negative charge anchor, forming multi-point ionic crosslinks with polydiallyldimethylammonium chloride. In improving the stability and dispersibility of lead carbonate and the stability of lead supply, polydiallyldimethylammonium chloride forms a first positively charged layer on the surface of lead carbonate through electrostatic adsorption. Sodium polystyrene sulfonate then assembles into a second negatively charged layer through ionic bonding. The alternating assembly of multiple ionic shells provides steric hindrance while maintaining the dynamic reversibility of the shells. As divalent lead ions near the cathode are consumed, partial dissociation of the ionic bonds promotes the dissolution of lead carbonate and releases lead ions. In improving the density and smoothness of the cathode deposition layer and inhibiting dendrite formation, nanoparticles formed by the cross-linking of the two polyelectrolytes through ionic bonding increase the viscosity of the system in the electrolyte, slowing down the sedimentation rate of the core-shell lead carbonate intermediate and ensuring the spatial uniformity of lead ion supply. At the same time, the nanoparticles form a weak adsorption layer on the cathode surface, regulating the interfacial double layer structure, reducing local current density fluctuations, and inducing uniform nucleation and layered growth of lead atoms. The synergistic effect of polydiallyldimethylammonium chloride and sodium polystyrene sulfonate lies in the precise matching of positive and negative charges and the dynamic balance of ionic bonds. This achieves both stable assembly and controllable dissociation of the core-shell structure, as well as cross-linking stability and interface regulation of nanoparticles. Thus, in the harsh electrochemical environment of strong methanesulfonic acid and high current density, it synergistically improves lead supply stability, deposition density and current efficiency, ensuring the stable preparation of high-purity lead materials.

[0032] Beneficial technical effects 1. Achieving high-value green recycling of waste lead-acid batteries: This invention uses lead sulfate-containing solids obtained from the dismantling of waste lead-acid batteries as raw materials. Through sodium carbonate aqueous phase conversion, it avoids the high energy consumption and pollutant emission problems of traditional pyrometallurgical processes. The wet electrolysis process operates at normal temperature and pressure, with low energy consumption and less pollution. It realizes the resource utilization of waste and environmentally friendly preparation, which is in line with the development direction of circular economy and green manufacturing. It provides a sustainable technical path for solving lead resource shortage and environmental pollution.

[0033] 2. Obtaining high-purity, dense, and smooth lead material: This invention achieves high current density (100-400 A / m²) in a methanesulfonic acid electrolysis system through the synergistic effect of a core-shell structure assembled by polyelectrolyte ionic bonds and ion-crosslinked nanoparticles. 2 The stable electrodeposition under the conditions of ) yields high-purity lead materials with a lead mass fraction of over 99.99%. The deposited layer is dense and flat, dendrite growth is effectively suppressed, and the content of organic and non-metallic inclusions is low, meeting the stringent requirements for lead purity and morphology in high-end application fields such as electronics, chemicals, and medical protection.

[0034] 3. Solving the problem of lead supply stability and interface morphology control in high current density electrodeposition: The derived core-shell lead carbonate designed in this invention achieves controllable dissolution and release of lead carbonate through the dynamic dissociation equilibrium of the ionic bond shell, ensuring the stable maintenance of the divalent lead ion concentration in the electrolyte and avoiding current efficiency fluctuations caused by rapid sedimentation of the solid lead source or insufficient lead supply; the derived ion-crosslinked nanoparticles achieve uniform nucleation and layered growth at the cathode interface through the effects of thickening and anti-settling and interface double-layer regulation, without introducing easily decomposable organic additives, effectively suppressing the generation of dendrites and coarse grains.

[0035] 4. High process stability, suitable for industrial scale-up: The polyelectrolyte material used in this invention has good stability in strong acid electrochemical environment, is not prone to redox side reactions, and the current efficiency is stable at a high level. The electrolyte can be continuously recycled and its cleanliness is maintained by online filtration. The process parameter window is wide, the operating conditions are mild (20-45℃, normal pressure), the equipment requirements are simple, and it is easy to realize continuous and automated production. It has good industrial application prospects and economic benefits. Attached Figure Description

[0036] Figure 1 The XRD crystal phase structure diagrams of the high-purity lead materials of Example 1 and Comparative Example 6 are shown.

[0037] Figure 2 The Zeta potential distribution diagrams are shown for the derived core-shell lead carbonate aqueous dispersion system obtained in step S2 of Example 1 and the lead carbonate microparticle aqueous dispersion system without assembled shell in Comparative Example 6.

[0038] Figure 3 The turbidity-time curves of the electrolytes obtained in step S4 of Example 1 and Comparative Example 7 under standing conditions at 25°C are shown.

[0039] Figure 4 The XPS Pb 4f high-resolution spectra of the surface of the metallic lead deposits obtained in Example 1, Comparative Example 1, and Comparative Example 6 are shown.

[0040] Figure 5 This is a comparison chart of the impurity element content in the high-purity lead materials obtained in Example 1, Comparative Example 2, and Comparative Example 8 using ICP-OES.

[0041] Figure 6 This is a macroscopic photograph of the high-purity lead material obtained in Example 1.

[0042] Figure 7 This is a scanning electron microscope image of the high-purity lead material obtained in Example 1. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Example 1

[0044] A method for electrolytically preparing high-purity lead material, the specific steps of which are as follows: Step S1: Preparation of lead carbonate microparticles First, the lead paste obtained from the dismantling of waste lead-acid batteries is pretreated by washing with deionized water and separating solids and liquids. During the washing process, the conductivity of the filtrate is kept below 2000 μS / cm to obtain solid lead sulfate.

[0045] Pretreated lead sulfate-containing solids were used as raw materials, with lead sulfate as the main component in this embodiment. A sodium carbonate aqueous solution was prepared, with a molar ratio of sodium carbonate to lead sulfate in the lead sulfate-containing solids of 1.12:1. The total lead sulfate content in the lead sulfate-containing solids was calculated based on the lead sulfate content (calculated as PbSO4) determined from samples of the lead sulfate-containing solids. In this embodiment, the sodium carbonate aqueous solution was prepared using deionized water, with a sodium carbonate mass fraction of 15%. The lead sulfate-containing solids were added to the deionized water to form a slurry with a solid content of 175 g / L. The sodium carbonate aqueous solution was added dropwise at 45°C using mechanical stirring. In this embodiment, the addition time was 1.2 h, the stirring speed was 500 r / min, and the pH of the reaction system was controlled between 8.5 and 10.5 during the addition process. After the addition was complete, the reaction was continued with stirring at 500 r / min until the pH of the reaction system fluctuated by no more than 0.5 within 0.5 h. The reaction system was subjected to solid-liquid separation and washed with deionized water until the conductivity of the filtrate was no higher than 500 μS / cm. It was then dried at 90°C for 8 h to obtain the lead carbonate microparticles of this embodiment. The lead carbonate microparticles of this embodiment have a particle size D50 of 2.8 μm and a water content of no more than 0.5%.

[0046] Step S2: Preparation of Derivative Core-Shell Lead Carbonate The lead carbonate microparticles prepared in step S1 were added to deionized water for pre-dispersion to obtain a dispersion system with a solid content of 17.5%. The pH of the dispersion system was then adjusted to 5.5. In this embodiment, the pH adjusters were aqueous methanesulfonic acid solution and aqueous sodium hydroxide solution. The mass fraction of methanesulfonic acid in the aqueous methanesulfonic acid solution was 40%, and the concentration of the aqueous sodium hydroxide solution was 2.5 mol / L.

[0047] Anion exchange layer assembly: Sodium polystyrene sulfonate aqueous solution was added to the dispersion system. In this embodiment, the concentration of sodium polystyrene sulfonate aqueous solution was 2.5%, and the amount of sodium polystyrene sulfonate added was 0.15% of the mass of lead carbonate particles. The mixture was stirred at 25°C for 1.1 h. Subsequently, solid-liquid separation was performed and the mixture was washed with deionized water. In this embodiment, solid-liquid separation and washing with deionized water included washing with deionized water 3 times until the conductivity of the final washing solution was not higher than 2000 μS / cm.

[0048] Cationic layer assembly: Add polydiallyldimethylammonium chloride aqueous solution to the solid obtained in the above steps. In this embodiment, the concentration of polydiallyldimethylammonium chloride aqueous solution is 2.5%, and the amount of polydiallyldimethylammonium chloride added is 0.15% of the mass of lead carbonate particles. Stir at 25°C for 1.1 h, then separate the solid and liquid and wash with deionized water. The washing method is the same as that for anionic layer assembly.

[0049] The anion layer assembly and cation layer assembly processes described above were repeated 6 times, and the resulting core-shell lead carbonate was obtained by drying at 65°C for 8 hours.

[0050] Step S3: Preparation of dispersions of derivatized ion-crosslinked nanoparticles Aqueous solutions of polydiallyldimethylammonium chloride and sodium polystyrene sulfonate were prepared separately, with a concentration of 1.0% for both solutions in this embodiment. At 25°C, the polydiallyldimethylammonium chloride solution was added dropwise to the sodium polystyrene sulfonate solution, resulting in a mass ratio of sodium polystyrene sulfonate to polydiallyldimethylammonium chloride of 1.25:1. In this embodiment, the mass ratio is the ratio of the dry weight of sodium polystyrene sulfonate to the dry weight of polydiallyldimethylammonium chloride. The mixture was mechanically stirred for 2.2 h at a stirring speed of 500 r / min. The resulting dispersion was allowed to stand for 12 h for aging, and then filtered through a 2.7 μm pore size membrane to remove large particles, yielding a dispersion of derivatized ion-crosslinked nanoparticles. The nanoparticle dispersion had a particle size distribution index (PDI) of 125 nm and a particle size distribution index (D50) of 0.20.

[0051] Step S4: Electrolyte preparation Methanesulfonic acid was added to deionized water to obtain an aqueous methanesulfonic acid solution with a methanesulfonic acid mass fraction of 42.5%. Under stirring, the derived core-shell lead carbonate prepared in step S2 was added, followed by a dispersion of derived ion-crosslinked nanoparticles. Finally, a compound solution was added to prepare the electrolyte. In the resulting electrolyte, the concentration of dissolved divalent lead ions was 51 g / L, and the amount of derived ion-crosslinked nanoparticles added was 0.25 g / L based on their solids content. The total solids content of the compound solution added was 2.5 g / L based on its total solids content. In this embodiment, the electrolyte showed no visible sedimentation or stratification after standing at 25°C for 24 h.

[0052] The preparation method of the compound solution in this embodiment is as follows: Gelatin is added to deionized water and stirred at 55°C for 1.2 h to dissolve, resulting in a gelatin solution with a gelatin mass fraction of 2.5%. Sodium lignosulfonate is added to the gelatin solution to make the mass ratio of gelatin to sodium lignosulfonate 1:1.1. In this embodiment, the mass ratio of gelatin to sodium lignosulfonate is the ratio of the dry basis mass of gelatin to the dry basis mass of sodium lignosulfonate. The mixture is stirred at 55°C for 1.2 h. The pH of the resulting compound solution is adjusted to 2.5 with methanesulfonic acid, and deionized water is added to make the total solid content of the resulting compound solution 2.6%, thus obtaining the compound solution of this embodiment.

[0053] Step S5: Pre-electrolysis purification A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. The electrolyte was pre-electrolyzed at 32.5℃ with a pre-electrolysis current density of 27.5 A / m. 2 The pre-electrolysis time is 2.2 h.

[0054] Step S6: Electrolytic deposition A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. Electrolytic deposition was performed on the electrolyte obtained in step S5 at a temperature of 32.5℃, with a current density of 250 A / m. 2 A metallic lead deposition layer was obtained at the cathode. Electrolytic deposition employed a continuous circulating electrolyte and online filtration with a pore size of 2.6 μm. The metallic lead deposition layer in this embodiment was washed with deionized water to obtain high-purity lead material. The lead mass fraction of the high-purity lead material in this embodiment was 99.995%, and the lead mass fraction in this embodiment was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). Example 2

[0055] A method for electrolytically preparing high-purity lead material, the specific steps of which are as follows: Step S1: Preparation of lead carbonate microparticles First, the lead paste obtained from the dismantling of waste lead-acid batteries is pretreated by washing with deionized water and separating solids and liquids. During the washing process, the conductivity of the filtrate is kept below 2000 μS / cm to obtain solid lead sulfate.

[0056] The pretreated lead sulfate-containing solid was used as a raw material, with lead sulfate as the main component in this embodiment. A sodium carbonate aqueous solution was prepared, with a molar ratio of sodium carbonate to lead sulfate in the lead sulfate-containing solid of 1.08:1. The total lead sulfate content in the lead sulfate-containing solid was calculated based on the lead sulfate content (calculated as PbSO4) determined by sampling the solid. In this embodiment, the sodium carbonate aqueous solution was prepared using deionized water, with a sodium carbonate mass fraction of 20%. The lead sulfate-containing solid was added to the deionized water to form a slurry with a solid content of 240 g / L. The sodium carbonate aqueous solution was added dropwise under mechanical stirring at a temperature of 60°C. In this embodiment, the addition time was 0.8 h, the stirring speed was 650 r / min, and the pH of the reaction system was controlled between 8.5 and 10.5 during the addition. After the addition was complete, the reaction was continued at 650 r / min. The reaction was stopped when the pH of the reaction system fluctuated by no more than 0.5 within 0.5 h. The reaction system was subjected to solid-liquid separation and washed with deionized water until the conductivity of the filtrate was no higher than 500 μS / cm. It was then dried at 105°C for 6 h to obtain the lead carbonate microparticles of this embodiment. The lead carbonate microparticles of this embodiment have a particle size D50 of 3.5 μm and a water content of no more than 0.5%.

[0057] Step S2: Preparation of Derivative Core-Shell Lead Carbonate The lead carbonate microparticles prepared in step S1 were added to deionized water for pre-dispersion to obtain a dispersion system with a solid content of 24%. The pH of the dispersion system was then adjusted to 4. In this embodiment, the pH adjusters were aqueous methanesulfonic acid solution and aqueous sodium hydroxide solution. The mass fraction of methanesulfonic acid in the aqueous methanesulfonic acid solution was 55%, and the concentration of the aqueous sodium hydroxide solution was 3.5 mol / L.

[0058] Anion exchange layer assembly: Sodium polystyrene sulfonate aqueous solution was added to the dispersion system. In this embodiment, the concentration of sodium polystyrene sulfonate aqueous solution was 4%, and the amount of sodium polystyrene sulfonate added was 0.20% of the mass of lead carbonate particles. The mixture was stirred at 32°C for 0.8 h, followed by solid-liquid separation and washing with deionized water. In this embodiment, solid-liquid separation and washing with deionized water included washing with deionized water 3 times until the conductivity of the last washing solution was not higher than 2000 μS / cm.

[0059] Cationic layer assembly: Add polydiallyldimethylammonium chloride aqueous solution to the solid obtained in the above steps. In this embodiment, the concentration of polydiallyldimethylammonium chloride aqueous solution is 4%, and the amount of polydiallyldimethylammonium chloride added is 0.20%. Stir at 32°C for 0.8 h, then separate the solid and liquid and wash with deionized water. The washing method is the same as that for anionic layer assembly.

[0060] The anion layer assembly and cation layer assembly processes described above were repeated 8 times, and the resulting core-shell lead carbonate was obtained by drying at 75°C for 6 hours.

[0061] Step S3: Preparation of dispersions of derivatized ion-crosslinked nanoparticles Aqueous solutions of polydiallyldimethylammonium chloride and sodium polystyrene sulfonate were prepared separately, with a concentration of 1.5% for both solutions in this embodiment. At 32°C, the aqueous solution of polydiallyldimethylammonium chloride was added dropwise to the aqueous solution of sodium polystyrene sulfonate, resulting in a mass ratio of sodium polystyrene sulfonate to polydiallyldimethylammonium chloride of 1.6:1. In this embodiment, the mass ratio is the ratio of the dry weight of sodium polystyrene sulfonate to the dry weight of polydiallyldimethylammonium chloride. The mixture was mechanically stirred for 3 hours at a speed of 650 r / min. The resulting dispersion was allowed to stand for 18 hours for aging, and then filtered through a 3.5 μm pore size membrane to remove large particles, yielding a dispersion of derivatized ion-crosslinked nanoparticles. The nanoparticle dispersion had a particle size distribution index (PDI) of 160 nm and a particle size distribution index (D50) of 0.25.

[0062] Step S4: Electrolyte preparation Methanesulfonic acid was added to deionized water to obtain an aqueous methanesulfonic acid solution with a methanesulfonic acid mass fraction of 58%. Under stirring, the derived core-shell lead carbonate prepared in step S2 was added, followed by the dispersion of derived ion-crosslinked nanoparticles prepared in step S3. Finally, a compound solution was added to prepare the electrolyte. In the electrolyte, the concentration of dissolved divalent lead ions was 75 g / L, and the amount of derived ion-crosslinked nanoparticles added was 0.38 g / L based on their solids content. The total solids content of the compound solution was 2.5 g / L based on its total solids content. In this embodiment, the electrolyte showed no visible sedimentation or stratification after standing at 25°C for 24 h.

[0063] The preparation method of the compound solution in this embodiment is as follows: Gelatin is added to deionized water and stirred at 62°C for 1 h to dissolve it, resulting in a gelatin solution with a gelatin mass fraction of 3.8%. Sodium lignosulfonate is added to the gelatin solution to make the mass ratio of gelatin to sodium lignosulfonate 1:1.6. In this embodiment, the mass ratio of gelatin to sodium lignosulfonate is the ratio of the dry basis mass of gelatin to the dry basis mass of sodium lignosulfonate, and the mixture is stirred at 62°C for 1 h. The pH of the resulting compound solution is adjusted to 2 with methanesulfonic acid, and deionized water is added to make the total solid content of the resulting compound solution 3.8%, thus obtaining the compound solution of this embodiment.

[0064] Step S5: Pre-electrolysis purification A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. The electrolyte was pre-electrolyzed at 38°C with a pre-electrolysis current density of 38 A / m. 2 The pre-electrolysis time is 3 hours.

[0065] Step S6: Electrolytic deposition A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. Electrolytic deposition was performed on the electrolyte obtained in step S5 at a temperature of 38°C, with a current density of 330 A / m. 2 A metallic lead deposition layer was obtained at the cathode. Electrolytic deposition employed a continuous circulating electrolyte and online filtration with a pore size of 3.8 μm. The metallic lead deposition layer in this embodiment was washed with deionized water to obtain high-purity lead material. The lead mass fraction of the high-purity lead material in this embodiment was 99.998%, and the lead mass fraction in this embodiment was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). Example 3

[0066] A method for electrolytically preparing high-purity lead material, the specific steps of which are as follows: Step S1: Preparation of lead carbonate microparticles First, the lead paste obtained from the dismantling of waste lead-acid batteries is pretreated by washing with deionized water and separating solids and liquids. During the washing process, the conductivity of the filtrate is kept below 2000 μS / cm, thus obtaining solid lead sulfate.

[0067] Pretreated lead sulfate-containing solids were used as raw materials, with lead sulfate as the main component in this embodiment. A sodium carbonate aqueous solution was prepared, with a molar ratio of sodium carbonate to lead sulfate in the lead sulfate-containing solids of 1.16:1. The total lead sulfate content in the lead sulfate-containing solids was calculated based on the lead sulfate content (calculated as PbSO4) determined from samples of the lead sulfate-containing solids. In this embodiment, the sodium carbonate aqueous solution was prepared using deionized water, with a sodium carbonate mass fraction of 10%. The lead sulfate-containing solids were added to the deionized water to form a slurry with a solid content of 100 g / L. The sodium carbonate aqueous solution was added dropwise under mechanical stirring at a temperature of 32°C. In this embodiment, the addition time was 1.6 h, the stirring speed was 350 r / min, and the pH of the reaction system was controlled between 8.5 and 10.5 during the addition process. After the addition was complete, the reaction was continued with stirring at 500 r / min. The reaction was stopped when the pH of the reaction system fluctuated by no more than 0.5 within 0.5 h. The reaction system was subjected to solid-liquid separation and washed with deionized water until the conductivity of the filtrate was no higher than 500 μS / cm. It was then dried at 75°C for 10 h to obtain the lead carbonate microparticles of this embodiment. The lead carbonate microparticles of this embodiment have a particle size D50 of 1.8 μm and a water content of no more than 0.5%.

[0068] Step S2: Preparation of Derivative Core-Shell Lead Carbonate The lead carbonate microparticles prepared in step S1 were added to deionized water for pre-dispersion to obtain a dispersion system with a solid content of 12%. The pH of the dispersion system was then adjusted to 6.5. In this embodiment, the pH adjusters were aqueous methanesulfonic acid solution and aqueous sodium hydroxide solution. The mass fraction of methanesulfonic acid in the aqueous methanesulfonic acid solution was 25%, and the concentration of the aqueous sodium hydroxide solution was 1.5 mol / L.

[0069] Anion exchange layer assembly: Add sodium polystyrene sulfonate aqueous solution to the dispersion system. In this embodiment, the concentration of sodium polystyrene sulfonate aqueous solution is 1.2%, and the amount of sodium polystyrene sulfonate added is 0.10% of the mass of lead carbonate particles. Stir at 18°C ​​for 1.5 h, then separate the solid and liquid and wash with deionized water. In this embodiment, the solid-liquid separation and washing with deionized water includes washing with deionized water 4 times until the conductivity of the last washing solution is not higher than 2000 μS / cm.

[0070] Cationic layer assembly: Add polydiallyldimethylammonium chloride aqueous solution to the solid obtained in the above steps. In this embodiment, the concentration of polydiallyldimethylammonium chloride aqueous solution is 1.2%, and the amount of polydiallyldimethylammonium chloride added is 0.10% of the mass of lead carbonate particles. Stir at 18°C ​​for 1.5 h, then separate the solid and liquid and wash with deionized water. The washing method is the same as that for anionic layer assembly.

[0071] The anion layer assembly and cation layer assembly processes described above were repeated four times, and the resulting derivative core-shell lead carbonate was obtained by drying at 55°C for 10 h.

[0072] Step S3: Preparation of dispersions of derivatized ion-crosslinked nanoparticles Aqueous solutions of poly(diallyldimethylammonium chloride) and sodium polystyrene sulfonate were prepared separately, with a concentration of 0.5% for both solutions in this embodiment. At 18°C, the aqueous solution of poly(diallyldimethylammonium chloride) was added dropwise to the aqueous solution of sodium polystyrene sulfonate, resulting in a mass ratio of sodium polystyrene sulfonate to poly(diallyldimethylammonium chloride) of 0.8:1. In this embodiment, the mass ratio is the ratio of the dry weight of sodium polystyrene sulfonate to the dry weight of poly(diallyldimethylammonium chloride). The mixture was mechanically stirred for 3.2 h at a stirring speed of 350 r / min. The resulting dispersion was allowed to stand for 20 h for aging, and then filtered through a 1.8 μm pore size membrane to remove large particles, yielding a dispersion of derivatized ion-crosslinked nanoparticles. The nanoparticle dispersion had a particle size distribution index (PDI) of 85 nm and a particle size distribution index (D50) of 0.15.

[0073] Step S4: Electrolyte preparation Methanesulfonic acid was added to deionized water to obtain an aqueous methanesulfonic acid solution with a methanesulfonic acid mass fraction of 28%. Under stirring, the derived core-shell lead carbonate prepared in step S2 was added, followed by a dispersion of derived ion-crosslinked nanoparticles, then the dispersion of derived ion-crosslinked nanoparticles prepared in step S3. Finally, a compound solution was added to prepare the electrolyte. In the electrolyte, the concentration of dissolved divalent lead ions was 25 g / L, and the amount of derived ion-crosslinked nanoparticles added was 0.12 g / L based on their solids content. The total solids content of the compound solution was 1.2 g / L based on its total solids content. In this embodiment, the electrolyte showed no visible sedimentation or stratification after standing at 25°C for 24 h.

[0074] The preparation method of the compound solution in this embodiment is as follows: Gelatin is added to deionized water and stirred at 48°C for 1.5 h to dissolve it, resulting in a gelatin solution with a gelatin mass fraction of 1.2%. Sodium lignosulfonate is added to the gelatin solution to make the mass ratio of gelatin to sodium lignosulfonate 1:0.6. In this embodiment, the mass ratio of gelatin to sodium lignosulfonate is the ratio of the dry weight of gelatin to the dry weight of sodium lignosulfonate. The mixture is stirred at 48°C for 1.5 h. The pH of the resulting compound solution is adjusted to 3 with methanesulfonic acid, and deionized water is added to make the total solid content of the resulting compound solution 1.2%, thus obtaining the compound solution of this embodiment.

[0075] Step S5: Pre-electrolysis purification A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. The electrolyte was pre-electrolyzed at 26°C with a current density of 16 A / m³. 2 The pre-electrolysis time is 3.2 h.

[0076] Step S6: Electrolytic deposition A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. Electrolytic deposition was performed on the electrolyte obtained in step S5 at a temperature of 26°C, with a current density of 170 A / m. 2 A metallic lead deposition layer was obtained at the cathode. Electrolytic deposition employed a continuous circulating electrolyte and online filtration with a pore size of 1.2 μm. The metallic lead deposition layer in this embodiment was washed with deionized water to obtain high-purity lead material. The lead mass fraction of the high-purity lead material in this embodiment was 99.992%, and the lead mass fraction in this embodiment was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). Example 4

[0077] A method for electrolytically preparing high-purity lead material, the specific steps of which are as follows: Step S1: Preparation of lead carbonate microparticles First, the lead paste obtained from the dismantling of waste lead-acid batteries is pretreated by washing with deionized water and separating solids and liquids. During the washing process, the conductivity of the filtrate is kept below 2000 μS / cm to obtain solid lead sulfate.

[0078] Pretreated lead sulfate-containing solids were used as raw materials, with lead sulfate as the main component in this embodiment. A sodium carbonate aqueous solution was prepared, with a molar ratio of sodium carbonate to lead sulfate in the lead sulfate-containing solids of 1.06. The total lead sulfate content in the lead sulfate-containing solids was calculated based on the lead sulfate content (calculated as PbSO4) determined by sampling the solids. In this embodiment, the sodium carbonate aqueous solution was prepared using deionized water, with a sodium carbonate mass fraction of 22%. Lead sulfate was added to the deionized water to form a slurry with a solid content of 270 g / L. The sodium carbonate aqueous solution was added dropwise with mechanical stirring at 25°C. In this embodiment, the addition time was 0.6 h, the stirring speed was 720 r / min, and the pH of the reaction system was controlled between 8.5 and 10.5 during the addition. After the addition was complete, the reaction was continued with stirring at 500 r / min. The reaction was stopped when the pH of the reaction system fluctuated by no more than 0.5 within 0.5 h. The reaction system was subjected to solid-liquid separation and washed with deionized water until the conductivity of the filtrate was no higher than 500 μS / cm. It was then dried at 110℃ for 5 h to obtain the lead carbonate microparticles of this embodiment. The lead carbonate microparticles of this embodiment have a particle size D50 of 4.5 μm and a water content of no more than 0.5%.

[0079] Step S2: Preparation of Derivative Core-Shell Lead Carbonate The lead carbonate microparticles prepared in step S1 were added to deionized water for pre-dispersion to obtain a dispersion system with a solid content of 8%. The pH of the dispersion system was then adjusted to 7.5. In this embodiment, the pH adjusters were aqueous methanesulfonic acid solution and aqueous sodium hydroxide solution. The mass fraction of methanesulfonic acid in the aqueous methanesulfonic acid solution was 65%, and the concentration of the aqueous sodium hydroxide solution was 4.5 mol / L.

[0080] Anion exchange layer assembly: Sodium polystyrene sulfonate aqueous solution was added to the dispersion system. In this embodiment, the concentration of sodium polystyrene sulfonate aqueous solution was 0.5%, and the amount of sodium polystyrene sulfonate added was 0.22% of the mass of lead carbonate particles. The mixture was stirred at 35°C for 0.4 h, followed by solid-liquid separation and washing with deionized water. In this embodiment, solid-liquid separation and washing with deionized water included washing with deionized water twice until the conductivity of the final washing solution was not higher than 2000 μS / cm.

[0081] Cationic layer assembly: Add polydiallyldimethylammonium chloride aqueous solution to the solid obtained in the above steps. In this embodiment, the concentration of polydiallyldimethylammonium chloride aqueous solution is 0.5%, and the amount of polydiallyldimethylammonium chloride added is 0.22% of the mass of lead carbonate particles. Stir at 35°C for 0.4 h, then separate the solid and liquid and wash with deionized water. The washing method is the same as that for anionic layer assembly.

[0082] The anion layer assembly and cation layer assembly processes described above were repeated 6 times, and the resulting derivative core-shell lead carbonate was obtained by drying at 82°C for 5 h.

[0083] Step S3: Preparation of dispersions of derivatized ion-crosslinked nanoparticles Aqueous solutions of poly(diallyldimethylammonium chloride) and sodium polystyrene sulfonate were prepared separately, with a concentration of 0.15% for both solutions in this embodiment. At 35°C, the aqueous solution of poly(diallyldimethylammonium chloride) was added dropwise to the aqueous solution of sodium polystyrene sulfonate, resulting in a mass ratio of sodium polystyrene sulfonate to poly(diallyldimethylammonium chloride) of 1.85:1. In this embodiment, the mass ratio is the ratio of the dry weight of sodium polystyrene sulfonate to the dry weight of poly(diallyldimethylammonium chloride). The mixture was mechanically stirred for 0.8 h at a stirring speed of 720 r / min. The resulting dispersion was allowed to stand for 22 h for aging, and then filtered through a 4.5 μm pore size membrane to remove large particles, yielding a dispersion of derivatized ion-crosslinked nanoparticles. The nanoparticle dispersion had a particle size distribution index (PDI) of 180 nm and a particle size distribution index (D50) of 0.28.

[0084] Step S4: Electrolyte preparation Methanesulfonic acid was added to deionized water to obtain an aqueous methanesulfonic acid solution with a methanesulfonic acid mass fraction of 62%. Under stirring, the derived core-shell lead carbonate prepared in step S2 was added, followed by a dispersion of derived ion-crosslinked nanoparticles to prepare the electrolyte. The electrolyte contained 88 g / L of dissolved divalent lead ions, and the amount of derived ion-crosslinked nanoparticles added was 0.45 g / L (based on solids). In this embodiment, the electrolyte showed no visible sedimentation or stratification after standing at 25°C for 24 h. This embodiment does not use a compound solution; high-purity lead material is prepared solely through the synergistic effect of derived core-shell lead carbonate and derived ion-crosslinked nanoparticles.

[0085] Step S5: Pre-electrolysis purification A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. The electrolyte was pre-electrolyzed at 42°C with a pre-electrolysis current density of 45 A / m. 2 The pre-electrolysis time is 0.8 h.

[0086] Step S6: Electrolytic deposition A titanium cathode plate was used as the cathode, and a ruthenium-iridium coated titanium anode plate was used as the anode. Electrolytic deposition was performed on the electrolyte obtained in step S5 at a temperature of 42°C, with a current density of 365 A / m. 2 A metallic lead deposition layer was obtained at the cathode. Electrolytic deposition employed a continuous circulating electrolyte and online filtration with a pore size of 0.5 μm. The metallic lead deposition layer in this embodiment was washed with deionized water to obtain high-purity lead material. The lead mass fraction of the high-purity lead material in this embodiment was 99.995%, and the lead mass fraction in this embodiment was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES).

[0087] Comparative Example 1: It is basically the same as Example 1, except that the mass fraction of the methanesulfonic acid aqueous solution in step S4 is 12%, while the amounts of other components and preparation conditions remain unchanged.

[0088] Comparative Example 2: It is basically the same as Example 1, except that the mass fraction of the methanesulfonic acid aqueous solution in step S4 is 75%, while the amounts of other components and preparation conditions remain unchanged.

[0089] Comparative Example 3: It is basically the same as Example 1, except that in step S4, the mass concentration of dissolved divalent lead ions in the electrolyte is 1.5 g / L, while the amounts of other components and preparation conditions remain unchanged.

[0090] Comparative Example 4: It is basically the same as Example 1, except that in step S4, the mass concentration of dissolved divalent lead ions in the electrolyte is 110 g / L, while the amounts of other components and preparation conditions remain unchanged.

[0091] Comparative Example 5: It is basically the same as Example 1, except that the amount of derivatized ion crosslinked nanoparticles added in step S4 is 0.05 g / L based on their solid content, while the amount of other components and preparation conditions remain unchanged.

[0092] Comparative Example 6: It is basically the same as Example 1, except that in step S2, the core-shell structure is not assembled. Instead, the lead carbonate microparticles prepared in step S1 are used directly to replace the derived core-shell lead carbonate as the lead source added to the electrolyte. The amounts of other components and preparation conditions remain unchanged.

[0093] Comparative Example 7: It is basically the same as Example 1, except that the dispersion of derivatized ion crosslinked nanoparticles is not added in step S4, while the amount of other components and preparation conditions remain unchanged.

[0094] Comparative Example 8: Basically the same as Example 1, except that the current density for electrolytic deposition in step S6 is 85 A / m. 2 The amounts of other components and preparation conditions remain unchanged.

[0095] Performance testing: Experiment 1: Determination of lead purity and impurity elements This experiment used inductively coupled plasma optical emission spectrometry (ICP-OES) to evaluate the purity and main impurity element content of the prepared high-purity lead material, verifying whether the target of 99.99% purity was achieved. The testing principle is based on high-temperature plasma excitation of characteristic spectral lines of each element in the sample, and quantitative analysis of element content based on spectral line intensity. During the experiment, the lead material sample was dissolved in a nitric acid-hydrogen peroxide mixed acid system to prepare the test solution. The contents of Pb and impurity elements such as Cu, Fe, Ag, Bi, and Sb were determined using an ICP-OES instrument (RF power 1.3 kW, plasma flow rate 15 L / min) at 25±2℃. Quantification was performed using the standard curve method to calculate the lead mass fraction and the content of each impurity element (ppm). Each sample was measured in triplicate, and the average value was taken.

[0096] Experiment 2: Current efficiency measurement This experiment evaluates the efficiency of electrical energy conversion into lead deposition during electrolysis based on Faraday's law of electrolysis. The current density was 250 A / m³. 2 Constant current electrolysis was performed at 32.5℃ for 2 hours. The cathode weight gain, i.e., the lead deposition mass, was accurately measured using a precision electronic balance (accuracy ±0.1 mg). The theoretical deposition mass was calculated based on the amount of electricity passed. The current efficiency was calculated as (actual deposition mass / theoretical deposition mass) × 100%. Each experiment was performed in triplicate, and the average ± standard deviation of the current efficiency percentage was calculated to evaluate the energy conversion efficiency of the electrolysis process.

[0097] Experiment 3: Surface roughness of the deposited layer Five measurement areas were randomly selected on the surface of a 30 mm × 30 mm × 2-5 mm thick deposited layer sample using a surface profilometer. The surface roughness Ra value was determined with a 5 mm scan length and a 0.1 μm resolution.

[0098] Experiment 4: Determination of Electrolyte Viscosity and Rheological Properties This experiment used a rotational viscometer to evaluate the viscosity of an electrolyte containing derivative core-shell lead carbonate and derivative ion-crosslinked nanoparticles. The electrolyte sample was placed in the rotational viscometer's measuring cell, and the shear rate was measured at 32.5 ± 0.5 °C for 10–500 s⁻¹. -1 Viscosity values ​​were measured within a specified range, with readings taken 30 seconds after each shear rate stabilized. The rheological type was analyzed by plotting viscosity-shear rate curves to determine whether the electrolyte exhibited Newtonian or pseudoplastic fluid characteristics. Each sample was measured three times, and the average value was taken to calculate the apparent viscosity (mPa·s), specifically at 32.5 ± 0.5 °C and a shear rate of 100 s⁻¹. -1 The viscosity values ​​measured under the conditions were used for single-value comparison in Table 1 and to evaluate the flow properties and processing suitability of the electrolyte.

[0099] Experiment 5: Electrolyte Dispersion Stability Test This experiment evaluated the anti-settling ability and dispersion stability of derivatized ion-crosslinked nanoparticles in electrolyte using static sedimentation experiments and turbidimetry, verifying the synergistic effect of anti-settling performance and stable lead supply. Electrolyte samples containing derivatized ion-crosslinked nanoparticles were placed in 100 mL colorimetric tubes and allowed to stand for 24 hours at 25±1℃ and <60% RH, observing for obvious sedimentation or stratification. Turbidity values ​​at 1 cm, 5 cm, and 9 cm below the liquid surface were measured using a turbidimeter, and the sedimentation rate was calculated as (top turbidity - bottom turbidity) / initial turbidity × 100%. Each sample was measured in triplicate, and the sedimentation rate percentage and dispersion uniformity index were calculated to evaluate the long-term dispersion stability of the nanoparticles.

[0100] Experiment 6: XRD Crystal Phase Structure Characterization This experiment utilizes X-ray diffraction (XRD) to characterize the crystal phase composition, lattice parameters, and crystallinity of high-purity lead materials, verifying the crystal quality of electrodeposited lead. Lead material samples were prepared as powder or plate samples and tested using an XRD instrument (Cu Kα radiation, λ=0.15406 nm, tube voltage 40 kV, tube current 40 mA). The scanning range was 20-80° (2θ), the step size was 0.02°, the scanning speed was 5° / min, and the slit system was configured as 1°-0.15 mm-1°. The positions of the main diffraction peaks and their corresponding crystal plane indices were determined according to the JCPDS 04-0686 lead standard card. The lattice constant was calculated, and the grain size was calculated using the Scherrer formula. The test data were exported as CSV format (2θ, intensity) for Origin plotting and analysis, comprehensively characterizing the crystal structure features of the lead material.

[0101] Experiment 7: Zeta potential measurement Take the derived core-shell lead carbonate sample or unassembled shell lead carbonate microparticle sample obtained in step S2, prepare an aqueous dispersion system with a mass fraction of 0.05%, and determine the Zeta potential distribution by electrophoretic light scattering at 25±0.5℃. Each sample is measured in parallel 3 times and the average value is taken.

[0102] Experiment 8: Characterization of the chemical state of XPS surface The lead deposition layer sample obtained in step S6 was washed with deionized water and dried. The high-resolution spectrum of Pb 4f was measured using X-ray photoelectron spectroscopy, and the binding energy was corrected using C 1s = 284.8 eV to compare the relative proportions of metallic lead and oxide lead.

[0103] Figure 1 The XRD crystal structure diagrams of the lead materials prepared in Example 1 and Comparative Example 6 are shown. X-ray diffraction was used to characterize the 2θ range of 20 to 80 degrees, and the basic parameters such as the diffraction peak shape and peak width of the two were compared by normalizing the relative intensity. The variable parameter was whether a core-shell assembly structure was formed in the sample preparation route. The results showed that the characteristic diffraction peaks of Example 1 were sharper and had fewer impurity peaks, while the peak shape of Comparative Example 6 was wider and accompanied by additional weak peaks. The conclusion is that core-shell assembly can improve the crystal order and reduce the introduction of impurity phases, thereby providing a structural basis for subsequent performance stability, proving that the scheme is reasonable in terms of structural construction.

[0104] Figure 2 The Zeta potential distribution diagrams for the derived core-shell lead carbonate aqueous dispersion system obtained in step S2 of Example 1 and the unassembled shell lead carbonate microparticle aqueous dispersion system in Comparative Example 6 are shown. The Zeta potential distribution of the samples was determined by electrophoretic light scattering. The results show that the absolute value of the Zeta potential in Example 1 is larger and the distribution is more concentrated, indicating that the surface charge state of the particles is more stable and the dispersion stability is better after core-shell assembly, indicating that this scheme is reasonable in terms of interface control.

[0105] Figure 3 The graphs show the normalized turbidity versus time curves of the electrolytes obtained in step S4 of Example 1 (dispersion with added derivatized ion cross-linked nanoparticles) and Comparative Example 7 (without added dispersion) under standing conditions at 25°C. The stability characterization parameters for turbidity retention over time are the mean normalized turbidity curves from 0 to 24 hours of standing at 25°C and the standard deviation error band with n equal to 3. The variable parameters are the differences in sample system structure and interface stabilization mechanism. The results show that the turbidity retention of Example 1 decreases more slowly and has a narrower error band over time, while that of Comparative Example 7 decreases more rapidly and fluctuates more. The conclusion is that Example 1 has better anti-sedimentation and anti-flocculation ability and batch-to-batch consistency, proving that the scheme is reasonable and reproducible in terms of stability during actual storage and use.

[0106] Figure 4 The XPS Pb 4f high-resolution spectra of the lead deposited layers obtained in Example 1, Comparative Examples 1 and 6 are shown. X-ray photoelectron spectroscopy was used to characterize the normalized intensity spectrum shape and peak position distribution in the range of binding energy from 132 to 146 eV, with the variable parameter being the difference in the proportion of chemical states on the lead surface under different preparation conditions. The results show that the spectrum shape of Example 1 is closer to the metallic state dominance and the contribution of the high binding energy shoulder peak is lower, while the comparative sample shows more obvious oxidation state related characteristics. The conclusion is that Example 1 can effectively reduce surface oxidation and maintain a more controllable surface chemical environment during preparation and post-treatment, which is consistent with its better stability and consistency, proving that the scheme is reasonable in terms of surface state control.

[0107] Figure 5 The ICP-OES comparison charts show the content of Cu, Fe, Ag, Bi, Sb, As, Sn, and Zn impurity elements in the high-purity lead materials obtained in Example 1, Comparative Examples 2, and 8. Inductively coupled plasma atomic emission spectrometry was used for quantitative analysis of each impurity element. The results show that the overall content of each impurity element in Example 1 is lower and the dispersion is smaller, indicating better impurity control and thus beneficial for obtaining high-purity and stable lead materials.

[0108] Figure 6 The image shows a macroscopic photograph of the high-purity lead material obtained in Example 1. The sample exhibits a uniform lead-gray metallic appearance and a consistent overall morphology, indicating that the deposition process was stable and macroscopic defects were controlled under conditions of moderate current density, synergy with multi-component intermediates, and online filtration. This supports the rationale for obtaining a high-purity lead material with a lead mass fraction of 99.995%.

[0109] Figure 7The image shows a scanning electron microscope (SEM) image of the high-purity lead material obtained in Example 1. The SEM was used to observe the surface and morphological hierarchy of the metallic lead deposition layer obtained from the cathode. At low magnification, the deposition layer is continuous and uniform over a large area. At medium magnification, it consists of tightly packed electrodeposited grains and nodules with suppressed agglomeration protrusions. At high magnification, the grain boundaries are clear and dominated by a small number of micropores or surface steps. This indicates that the superposition of derived core-shell lead carbonate and derived ion-crosslinked nanoparticles can reduce the tendency of coarse nodules and dendrites, and improve the density and uniformity of the deposition. Structurally, this proves the correctness and rationality of the process parameter configuration.

[0110] The performance comparison between the embodiments and the comparative examples is shown in Table 1.

[0111] As can be seen from the performance of the examples and comparative examples in Table 1, Examples 1-4 employ a synergistic technique involving derived core-shell lead carbonate and derived ion-crosslinked nanoparticles, achieving optimal performance at a methanesulfonic acid mass fraction of 15-70%, a dissolved lead ion concentration of 2-100 g / L, and an electrolytic deposition current density of 100-400 A / m². 2Within the scope of the claims, all samples exhibited excellent overall performance, with lead purity reaching 99.992-99.998%, current efficiency reaching 89.8-94.2%, surface roughness controlled at 1.62-2.15 μm, and total impurities controlled at 15-62 ppm. It should be noted that Examples 1 and 4 are not single-factor control experiments specifically designed for the addition of a compound solution. They differ in conditions such as the mass fraction of methanesulfonic acid, the concentration of dissolved divalent lead ions, the amount of derivatized ion-crosslinked nanoparticles added (based on their solid content), and the electrolytic deposition current density. Therefore, their performance differences cannot be simply attributed to the addition of a compound solution. The higher electrolyte viscosity in Example 4 is mainly related to the combined effects of a higher mass fraction of methanesulfonic acid, a higher concentration of dissolved divalent lead ions, and a higher amount of derivatized ion-crosslinked nanoparticles added (based on their solid content). The compound solution is an optional adjustable component that can further optimize the deposition morphology and operating window under certain operating conditions, but it is not a necessary condition for achieving the technical effects of this invention. In Comparative Examples 1 and 2, the methanesulfonic acid mass fraction exceeded 15-70%, resulting in lead purity decreasing to 99.962% and 99.975%, current efficiency decreasing to 78.5% and 81.2%, surface roughness increasing to 3.85 and 3.12 μm, and impurity content significantly increasing to 285 and 188 ppm, respectively. This indicates that neither excessively low nor excessively high methanesulfonic acid mass fractions can achieve a synergistic optimization of high purity and high efficiency. In Comparative Examples 3 and 4, the dissolved divalent lead ion concentration exceeded the range, leading to insufficient lead supply and excessively high electrolyte viscosity, respectively. Lead purity decreased to 99.958% and 99.968%, current efficiency decreased to 72.8% and 76.5%, and impurity content increased to 335 and 248 ppm. In Comparative Example 5, the amount of derived ion-crosslinked nanoparticles added was too low (based on solids), failing to effectively control the interface morphology, resulting in increased surface roughness to 3.42 μm and impurity content to 215 ppm. Comparative Examples 6 and 7, lacking core-shell structures or dispersions of derived ion-crosslinked nanoparticles, lost the synergistic effect of their core technical features. Lead purity decreased to 99.945% and 99.952%, respectively; current efficiency decreased to 68.5% and 71.2%; surface roughness significantly increased to 5.85 and 5.12 μm; and impurity content surged to 428 and 382 ppm, respectively, fully demonstrating the necessity and superiority of the technical solution of this invention. Comparative Example 8, with its excessively low electrolytic deposition current density, although achieving a high lead purity of 99.982% and a low surface roughness of 2.58 μm, had a deposition rate of only 16.5 g / h, far lower than the 31.2-66.8 g / h of the examples, resulting in a significant decrease in production efficiency and rendering it unsuitable for industrial application.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any equivalent structural transformations made under the concept of the present invention and using the contents of the specification and drawings of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for electrolytically preparing high-purity lead material, characterized in that, Includes the following steps: S1. Disassemble the waste lead-acid battery, wash the obtained lead paste with deionized water and perform solid-liquid separation to obtain lead sulfate solid; use the lead sulfate solid as raw material, and use sodium carbonate in an aqueous phase with deionized water as medium to convert lead carbonate microparticles. S2. Using the lead carbonate microparticles as the core, polydiallyldimethylammonium chloride and sodium polystyrene sulfonate are alternately assembled on the surface of the lead carbonate microparticles to form a shell layer, thereby obtaining derived core-shell lead carbonate; S3. Polydiallyldimethylammonium chloride and sodium polystyrene sulfonate are compounded in an aqueous phase to obtain a dispersion of derivatized ion-crosslinked nanoparticles; S4. Prepare an aqueous solution of methanesulfonic acid, add the derived core-shell lead carbonate, and then add a dispersion of derived ion-crosslinked nanoparticles to obtain an electrolyte; S5. Pre-electrolyze the electrolyte obtained in step S4 at 20-45℃, with a pre-electrolysis current density of 5-50 A / m. 2 The time is 0.5-4 hours; S6. Electrolytic deposition is performed on the electrolyte obtained in step S5 at 20-45℃, with an electrolytic deposition current density of 100-400 A / m. 2 A metallic lead deposition layer is obtained at the cathode; the metallic lead deposition layer is washed with deionized water and dried to obtain high-purity lead material.

2. The method according to claim 1, characterized in that, In step S4, the mass fraction of the methanesulfonic acid aqueous solution is 15-70%; the concentration of dissolved divalent lead ions in the electrolyte is 2-100 g / L, and the amount of derived ion crosslinked nanoparticles added is 0.1-0.5 g / L based on their solid content.

3. The method according to claim 1, characterized in that, In step S1, the lead carbonate microparticles are prepared through the following steps: A1. Proportion: Prepare a sodium carbonate aqueous solution with a molar ratio of sodium carbonate to lead sulfate in the lead sulfate solid solution of 1.05-1.20:1; A2. Conversion: Add lead sulfate solid to deionized water to form a slurry with a solid content of 50-300 g / L. Add the sodium carbonate aqueous solution dropwise at a temperature of 20-70℃. During the dropwise addition, control the pH of the reaction system at 8.5-10.

5. After the dropwise addition is complete, continue stirring the reaction. Stop the reaction when the pH of the reaction system fluctuates by no more than 0.5 within 0.5 h. A3. Post-processing: The reaction system is subjected to solid-liquid separation and washed with deionized water until the conductivity of the filtrate is not higher than 500 μS / cm. Then, it is dried at a temperature of 60-120℃ for 4-12 h to obtain the lead carbonate microparticles. The particle size D50 of the lead carbonate microparticles is 0.5-5 μm and the water content is not higher than 0.5%.

4. The method according to claim 1, characterized in that, In step S2, the derived core-shell lead carbonate is prepared through the following steps: B1. Pre-dispersion: The lead carbonate microparticles are added to deionized water to obtain a dispersion system with a solid content of 5-30%, and the pH of the dispersion system is adjusted to 3-8; B2. Anion layer assembly: Add an aqueous solution of sodium polystyrene sulfonate to the dispersion system obtained in step B1. The mass concentration of the sodium polystyrene sulfonate aqueous solution is 0.1-5%, and the amount of sodium polystyrene sulfonate added is 0.05-0.25% of the mass of the lead carbonate particles. Then stir at a temperature of 10-40℃ for 0.2-2 h, followed by solid-liquid separation and washing with deionized water. B3. Cationic layer assembly: Add an aqueous solution of polydiallyldimethylammonium chloride to the solid obtained in step B2. The mass concentration of the aqueous solution of polydiallyldimethylammonium chloride is 0.1-5%, and the amount of polydiallyldimethylammonium chloride added is 0.05-0.25% of the mass of the lead carbonate particles. Stir at a temperature of 10-40℃ for 0.2-2 h, then separate the solid and liquid and wash with deionized water. B4. Repeat assembly: Repeat steps B2-B3 2-10 times to obtain the intermediate; B5. Drying and quality control: Dry at a temperature of 40-90℃ for 4-12 h to obtain the derived core-shell lead carbonate.

5. The method according to claim 1, characterized in that, The dispersion of the derived ion-crosslinked nanoparticles described in step S3 is prepared through the following steps: C1. Solution preparation: Prepare aqueous solutions of polydiallyldimethylammonium chloride and sodium polystyrene sulfonate, respectively, with a mass concentration of 0.05-2.0% for both solutions; C2. Composite nucleation: Under the condition of 10-40℃, an aqueous solution of polydiallyldimethylammonium chloride is added dropwise to an aqueous solution of sodium polystyrene sulfonate, such that the mass ratio of sodium polystyrene sulfonate to polydiallyldimethylammonium chloride is 0.5:1-2:1, and the mixture is stirred for 0.5-4 h. C3. Aging and post-treatment: The dispersion obtained in step C2 is allowed to stand for aging for 0.5-24 h and filtered to remove large particles to obtain a dispersion of derivatized ion crosslinked nanoparticles; the particle size D50 of the derivatized ion crosslinked nanoparticles in the obtained dispersion is 50-200 nm, and the PDI is not higher than 0.30, where PDI is the particle size distribution index.

6. The method according to claim 1, characterized in that, The electrolyte used in step S4 of the method also includes a compound solution, which is prepared through the following steps: D1. Dissolution: Add gelatin to deionized water and stir at 40-70℃ for 0.5-2 h to obtain a gelatin solution with a mass fraction of 0.1-5%; D2. Compounding: Add sodium lignosulfonate to the gelatin solution to make the mass ratio of gelatin to sodium lignosulfonate 1:0.2-2, stir at 40-70℃ for 0.5-2 h, then adjust the pH of the solution to 1-4 with methanesulfonic acid, and make the total solid content of the resulting compound solution 0.2-5%.

7. The method according to claim 1, characterized in that, In step S6, electrolytic deposition uses a continuously circulating electrolyte and is filtered online with a pore size of 0.2-5 μm.

8. The method according to claim 1, characterized in that, At least one of the cathodes used in step S5 and step S6 is a titanium cathode plate, and at least one of the anodes used in step S5 and step S6 is an inert anode.

9. The method according to claim 1, characterized in that, The lead paste is washed with deionized water and subjected to solid-liquid separation to obtain lead sulfate solid. Specifically, the lead paste is washed with deionized water and subjected to solid-liquid separation to ensure that the conductivity of the filtrate is not higher than 2000 μS / cm, thereby obtaining lead sulfate solid.

10. The method according to claim 1, characterized in that, The lead mass fraction of the high-purity lead material is not less than 99.99%.

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