Extraction agent and recovery method for tin element recovery from spent lead paste

Abstract

The present application relates to the technical field of waste lead paste recycling, and particularly relates to an extractant for recovering tin element in waste lead paste and a recovery method. The present application provides an extractant for recovering tin element in waste lead paste, which comprises a tin solubilizer containing carboxyl, ketone and disulfide bond, and an alkali solubilizer; in the extractant, the molar ratio between carboxyl, ketone, disulfide bond and hydroxyl in the alkali solubilizer is (1.0-4.0):(0.5-3.0):(0.3-2.0):(1.0-5.0); and the pH of the extractant is 9-10. The extractant provided by the present application utilizes the carboxyl, ketone and disulfide bond in the tin solubilizer to act on Sn 4+ , in combination with the OH ‑ and alkaline action of the alkali solubilizer, to convert the insoluble tin oxide in the waste lead paste into soluble tin complex, thereby laying a foundation for efficient recovery.

Description

Technical Field

[0001] This invention relates to the field of waste lead paste recycling technology, specifically to an extractant and recycling method for recovering tin from waste lead paste. Background Technology

[0002] Lead-acid batteries are widely used in automobiles, communications, and energy storage due to their low cost, high reliability, and mature technology. With the increasing number of discarded lead-acid batteries each year, their recycling has become an important issue for environmental protection and resource recycling. Waste lead paste from lead-acid batteries is one of the main byproducts of the recycling process. Besides containing a large amount of lead, it also contains tin, which is often a lead-tin alloy, during the crushing process. This tin enters the lead paste and, under the oxidation of lead dioxide in the paste, forms tetravalent tin oxide, resulting in a typical tetravalent tin content of 0.01~0.1 wt% in the waste lead paste.

[0003] Tin, as an important non-ferrous metal, has high economic value. Currently, the recycling and processing of waste lead paste from lead-acid batteries largely focuses on recovering lead, while insufficient attention is paid to tin, leading to the waste of tin resources. Furthermore, the tin in waste lead paste increases the burden on subsequent lead smelting processes, affecting the purity and quality of lead products. Therefore, developing an efficient and convenient reagent for recovering tin from waste lead paste is of great significance for improving the overall economic efficiency of lead recycling, reducing smelting costs, and achieving comprehensive resource utilization.

[0004] Currently, there are few methods for recovering tin from waste lead paste. Existing methods often suffer from low recovery efficiency, complex processes, high reagent consumption, and high costs. For example, using strong acids as extractants can extract tin to some extent, but it also leaches out large amounts of lead, making subsequent separation difficult. Furthermore, strong acids are highly corrosive to equipment and pose a high risk of environmental pollution. On the other hand, processes using high-temperature roasting combined with leaching do not use any chemical reagents and are relatively environmentally friendly, but they suffer from high energy consumption and demanding operating conditions, hindering industrial-scale application.

[0005] Therefore, there is an urgent need for a reagent for recovering tin from waste lead paste that can improve recycling efficiency, reduce costs, and be environmentally friendly. Summary of the Invention The present invention aims to overcome the shortcomings of low recovery efficiency and high cost of the extractant used for tin recovery from waste lead paste in the prior art, and provides an extractant and recovery method for tin recovery from waste lead paste to overcome the above-mentioned shortcomings.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides an extractant for recovering tin from waste lead paste, comprising a tin solubilizer containing carboxyl groups, ketone groups, and disulfide bonds, and an alkaline co-solvent; wherein the molar ratio between the carboxyl groups, ketone groups, disulfide bonds, and hydroxide ions in the alkaline co-solvent is (1.0~4.0): (0.5~3.0): (0.3~2.0): (1.0~5.0); and the pH of the extractant is 9~10.

[0007] Preferably, in the extractant, the molar ratio between carboxyl groups, ketone groups, disulfide bonds and hydroxide ions in the alkaline co-solvent is (1.0~3.0): (0.5~2.0): (0.5~2.0): (2.0~4.0).

[0008] Preferably, in the extractant, the molar ratio between carboxyl groups, ketone groups, disulfide bonds and hydroxide ions in the alkaline co-solvent is (1.0~2.5): (0.5~1.5): (0.5~1.5): (2.0~3.0).

[0009] Preferably, the extractant further includes a tin stabilizer containing hydroxyl groups.

[0010] Preferably, the tin stabilizer is a polyhydroxy compound.

[0011] Preferably, the tin stabilizer is a polyhydroxy compound with a chain structure.

[0012] Preferably, the polyhydroxy compound is at least one selected from ethylene glycol, 1,3-propanediol, glycerol, and 1,4-butanediol.

[0013] Preferably, in the extractant, the molar ratio between carboxyl groups, ketone groups, disulfide bonds, hydroxyl groups and hydroxide ions in the alkaline co-solvent is (1.0~4.0): (0.5~3.0): (0.3~2.0): (1.0~5.0): (1.0~5.0).

[0014] Preferably, in the extractant, the molar ratio between carboxyl groups, ketone groups, disulfide bonds, hydroxyl groups and hydroxide ions in the alkaline co-solvent is (1.0~3.0): (0.5~2.0): (0.5~2.0): (1.0~3.0): (2.0~4.0).

[0015] Preferably, in the extractant, the molar ratio between carboxyl groups, ketone groups, disulfide bonds, hydroxyl groups and hydroxide ions in the alkaline co-solvent is (1.0~2.5): (0.5~1.5): (0.5~1.5): (1.0~2.0): (2.0~3.0).

[0016] Preferably, the carboxyl group in the tin solubilizer is derived from at least one of 2-oxoglutaric acid, oxaloacetic acid, α-ketoglutaric acid, malonic acid, thiosalicylic acid, mercaptosuccinic acid, α-lipoic acid, and succinic acid.

[0017] Preferably, the ketone group in the tin solubilizer is derived from at least one of pyruvate, 2-oxoglutaric acid, oxaloacetic acid, and α-ketoglutaric acid.

[0018] Preferably, the disulfide bond in the tin solubilizer is derived from at least one of thiosalicylic acid, mercaptosuccinic acid, α-lipoic acid, and cysteine.

[0019] Preferably, the alkaline co-solvent is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and calcium hydroxide.

[0020] Preferably, the tin solubilizer includes solubilizer A, which provides both carboxyl and ketone groups, and solubilizer B, which provides both carboxyl and disulfide bonds.

[0021] Preferably, the solubilizer A is at least one of 2-oxoglutaric acid, oxaloacetic acid, and α-ketoglutaric acid.

[0022] Preferably, the solubilizer B is at least one of thiosalicylic acid, mercaptosuccinic acid, and α-lipoic acid.

[0023] Preferably, the alkaline co-solvent is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and calcium hydroxide.

[0024] The present invention also provides a method for recovering tin from waste lead paste, comprising: mixing waste lead paste with the extractant provided by the present invention, ball milling and then extracting with water to obtain a leachate; adding acid to the leachate to adjust the pH to 1-2, and recovering tin oxide.

[0025] Preferably, the amount of the extractant is 2-5 wt% of the waste lead paste.

[0026] Preferably, the ball milling conditions include: a ball-to-material ratio of (5~20):1, a rotation speed of 200~600 rpm, and a time of 10~30 min.

[0027] Preferably, the grinding media is cemented carbide balls or zirconia balls.

[0028] Preferably, the diameter of the ball milling media is 3 to 8 mm.

[0029] Preferably, the waste lead paste has undergone impurity removal treatment.

[0030] Preferably, the waste lead paste is subjected to a crushing process, and the particle size of the crushed waste lead paste is 50-100 mesh.

[0031] Preferably, the liquid-to-solid ratio during water extraction is 3-5 mL / g.

[0032] Preferably, the extraction method is as follows: extraction at 25~40℃ and a rotation speed of 100~200 rpm for 20~30 minutes.

[0033] Preferably, the acid is at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0034] Preferably, the concentration of the acid is 1~2 mol / L.

[0035] Preferably, the reaction is stirred at 25-40°C for 15-20 min, then allowed to stand for 30-60 min, and then dried at 100-110°C for 2-3 h to obtain tin oxide.

[0036] Therefore, the present invention has the following beneficial effects: (1) The extractant provided by the present invention utilizes the carboxyl groups, ketone groups and disulfide bonds in the tin solubilizer to react with Sn. 4+ Its function is to combine with the OH- of the alkaline co-solvent. - Through alkaline action, the sparingly soluble tin oxides in waste lead paste are converted into soluble tin complexes, laying the foundation for efficient recycling.

[0037] (2) The extractant provided by the present invention does not involve toxic or environmentally unfriendly reagents, and the reagents that can meet the requirements of the present invention are widely available and inexpensive.

[0038] (3) The molar ratio between carboxyl groups, ketone groups, disulfide bonds and hydroxide ions in the alkaline co-solvent provided by the present invention is a specific molar ratio, which is related to the amount of each reagent added, and is for the purpose of ensuring the performance balance of the entire extractant.

[0039] (4) The extractant of the present invention adds a tin stabilizer, utilizing the hydroxyl group and Sn 4+ It forms coordination bonds and simultaneously encapsulates soluble tin complexes through intermolecular hydrogen bonds, inhibiting their aggregation or precipitation, improving the complexation conversion rate, and thus improving the recovery efficiency of the extractant.

[0040] (5) The tin stabilizer with a chain structure used in this invention can further reduce steric hindrance and avoid complex aggregation. Furthermore, when the extractant is ball-milled and mixed with waste lead paste, the chain structure can increase the fluidity of the system and conversely promote mass transfer during the ball milling process.

[0041] (6) The recycling method provided by the present invention involves ball milling the extractant and waste lead paste, successfully converting the insoluble tin oxide in the waste lead paste into soluble tin complex / soluble stannate, and then using a strong acid to decomplex the soluble tin complex / soluble stannate, ultimately resulting in tin oxide in the form of tin oxide, and thus recovering the tin oxide.

[0042] (7) The recovery method provided by the present invention utilizes high concentrations of H + Disrupting the original alkaline or neutral conditions, while simultaneously increasing the concentration of H+. + Competitive binding to the coordination sites of complexing agents disrupts the complexation balance, causing the tin in the originally stable soluble tin complex / soluble stannate to undergo decomplexation.

[0043] (8) The recovery method provided by the present invention utilizes a strong acid environment to inhibit Sn. 4+ Hydrolysis ensures that tin exists in a soluble form or is converted into tin oxide after decomplexation; simultaneously, according to Le Chatelier's principle, high concentrations of H₂... + This shifts the reaction equilibrium toward decomplexation, ensuring the complete release of tin from the complex.

[0044] (9) The recycling method provided by the present invention utilizes strong acid to promote the protonation of the extractant, so that it is dissociated from the soluble tin complex / soluble stannate, and the extractant can be recycled and reused.

[0045] (10) The recycling method provided by the present invention fully integrates the extractant and waste lead paste by ball milling and mixing mechanical activation and enhanced mass transfer characteristics, so that the extractant can quickly replace the insoluble tin oxide in the waste lead paste.

[0046] (11) The recycling method provided by the present invention is simple and does not involve reagents with very low toxicity or environmental friendliness, but has high recycling efficiency and is suitable for actual production use. Detailed Implementation

[0047] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0048] The preferred embodiments of the present invention will now be described in detail.

[0049] This invention provides an extractant for recovering tin from waste lead paste, comprising a tin solubilizer containing carboxyl groups, ketone groups, and disulfide bonds, and an alkaline co-solvent; wherein the molar ratio between the carboxyl groups, ketone groups, disulfide bonds, and hydroxide ions in the alkaline co-solvent is (2.0~4.0): (1.0~3.0): (0.5~2.0): (1.0~5.0): (2.5~5.0); and the pH of the extractant is 9~10.

[0050] In the extraction agent provided by this invention, the carboxyl group in the tin solubilizer reacts with Sn. 4+ Coordination is performed to form stable Sn-O coordination bonds, thereby removing Sn from the waste lead paste. 4+ It transforms into a soluble tin complex. The ketone group in the tin solubilizer enhances the coordination bond strength or chelation effect in the soluble tin complex through the proximity effect, and can cooperate with the carboxyl group to form a polydentate coordination structure, thereby improving the stability of the soluble tin complex. The disulfide bond in the tin solubilizer introduces sulfur coordinating atoms, which can further improve the stability of the soluble tin complex.

[0051] Based on the above, this invention utilizes carboxyl groups, ketone groups, disulfide bonds, and Sn. 4+ The bonding process transforms the insoluble tin oxides in waste lead paste into stable soluble tin complexes. Furthermore, the alkaline co-solvent provides a strongly alkaline environment to facilitate the release of carboxyl groups, enhancing the conversion efficiency of the soluble tin complexes; and utilizes the OH groups within them... - It reacts with tin oxide to form SnO3. 2- To promote Sn 4+ The release of OH groups accelerates the reaction process of insoluble tin oxides converting into soluble tin complexes, thereby increasing the conversion efficiency of the soluble tin complexes. However, it should be noted that the alkaline co-solvent provides a large amount of OH groups. - This helps maintain basicity and promotes the release of carboxyl groups, preventing premature protonation of carboxyl groups. However, the released carboxyl groups will, in turn, consume OH groups. - When OH - Excessive consumption can lead to insufficient local alkalinity, affecting Sn. 4+ The release efficiency of the alkali co-solvent affects the equilibrium of the system. Therefore, the amount of alkali co-solvent added must not only be considered in maintaining the pH of the system at 9-10, but also in terms of OH-. - The amount provided.

[0052] Furthermore, the molar ratio between the carboxyl group, ketone group, disulfide bond and hydroxyl group in the alkaline co-solvent provided by this invention is a specific molar ratio, which is related to the amount of each reagent added, and is for the purpose of ensuring the performance balance of the entire extractant.

[0053] In summary, the extractant provided by this invention does not involve toxic or environmentally unfriendly reagents, and the reagents that meet the requirements of this invention are widely available and inexpensive. The extractant provided by this invention utilizes the carboxyl, ketone, and disulfide bonds in the tin solubilizer to react with Sn. 4+ Its function is to combine with the OH- of the alkaline co-solvent. - Through alkaline action, the sparingly soluble tin oxides in waste lead paste are converted into soluble tin complexes, laying the foundation for efficient recycling.

[0054] Preferably, the extractant further includes a tin stabilizer containing hydroxyl groups.

[0055] The hydroxyl groups of tin stabilizers with Sn 4+It forms coordination bonds and simultaneously encapsulates soluble tin complexes through intermolecular hydrogen bonds, inhibiting their aggregation or precipitation and improving the complexation conversion rate.

[0056] Preferably, the tin stabilizer is a polyhydroxy compound.

[0057] Preferably, the tin stabilizer is a polyhydroxy compound with a chain structure.

[0058] The chain-like structure can further reduce steric hindrance and prevent complex aggregation. Furthermore, when the extractant is ball-milled and mixed with waste lead paste, the chain-like structure can increase the fluidity of the system and conversely promote mass transfer during the ball milling process.

[0059] Preferably, the polyhydroxy compound is at least one selected from ethylene glycol, 1,3-propanediol, glycerol, and 1,4-butanediol.

[0060] Any polyhydroxy compound containing hydroxyl groups and having a chain structure that can be used as a tin stabilizer in this invention includes, but is not limited to, ethylene glycol, 1,3-propanediol, glycerol and 1,4-butanediol.

[0061] Preferably, in the extractant, the molar ratio between carboxyl groups, ketone groups, disulfide bonds, hydroxyl groups and hydroxide ions in the alkaline co-solvent is (2.0~4.0): (1.0~3.0): (0.5~2.0): (1.0~5.0): (2.5~5.0).

[0062] Preferably, the carboxyl group in the tin solubilizer is derived from at least one of 2-oxoglutaric acid, oxaloacetic acid, α-ketoglutaric acid, malonic acid, thiosalicylic acid, mercaptosuccinic acid, α-lipoic acid, and succinic acid.

[0063] Preferably, the ketone group in the tin solubilizer is derived from at least one of pyruvate, 2-oxoglutaric acid, oxaloacetic acid, and α-ketoglutaric acid.

[0064] Preferably, the disulfide bond in the tin solubilizer is derived from at least one of thiosalicylic acid, mercaptosuccinic acid, α-lipoic acid, and cysteine.

[0065] Preferably, the alkaline co-solvent is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and calcium hydroxide.

[0066] Preferably, the tin solubilizer includes solubilizer A, which provides both carboxyl and ketone groups, and solubilizer B, which provides both carboxyl and disulfide bonds.

[0067] This invention relates to a tin solubilizer containing carboxyl, ketone, and disulfide groups, which can be obtained by combining various single reagents containing carboxyl, ketone, and disulfide groups. The carboxyl, ketone, and disulfide groups can originate from the same substance or from two different substances.

[0068] For example, 2-oxoglutaric acid possesses both carboxyl and ketone groups, with a fixed distance between the carboxyl and ketone groups, potentially forming a more stable chelate ring and yielding a stable soluble complex. Alternatively, pyruvic acid and malonic acid can be used to provide the ketone and carboxyl groups, respectively. Compared to providing both carboxyl and ketone groups simultaneously in the same substance, providing two groups in two different substances allows for greater flexibility in the spatial positions of the groups.

[0069] Preferably, the solubilizer A is at least one of 2-oxoglutaric acid, oxaloacetic acid, and α-ketoglutaric acid.

[0070] Solubilizer A only needs to meet the requirement of providing both carboxyl and ketone groups. Except for 2-oxoglutaric acid, oxaloacetic acid, and α-ketoglutaric acid, other reagents that meet the requirements can be adopted.

[0071] Preferably, the solubilizer B is at least one of thiosalicylic acid, mercaptosuccinic acid, and α-lipoic acid.

[0072] Solubilizer B only needs to meet the requirement of providing both carboxyl groups and disulfide bonds. Except for thiosalicylic acid, mercaptosuccinic acid, and α-lipoic acid, other reagents that meet the requirements can be adopted.

[0073] Preferably, the alkaline co-solvent is at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and calcium hydroxide.

[0074] The alkaline co-solvent in this invention only needs to provide sufficient OH. - The solution is sufficient to dissolve the sparingly soluble tin oxide and maintain the pH of the system at 9-10. For example, sodium carbonate and calcium hydroxide can be used to maintain the pH of the system at 9-10 through hydrolysis.

[0075] The alkaline co-solvents used in this invention can be any solvent that meets the above conditions and does not react with other groups in the tin solubilizer and tin stabilizer. For example, those containing Ba... 2+ The alkaline co-solvent will react with the carboxyl group to form a salt precipitate, disrupting the balance of the extractant system.

[0076] The present invention also provides a method for recovering tin from waste lead paste, comprising: mixing waste lead paste with the extractant provided by the present invention, ball milling and then extracting with water to obtain a leachate; adding acid to the leachate to adjust the pH to 1-2, and recovering tin oxide.

[0077] When waste lead paste and extractant are mixed under ball milling: carboxyl groups and Sn 4+ The formation of Sn-O coordination bonds transforms the insoluble tin oxides in waste lead paste into soluble tin complexes. The ketone group enhances the stability of the coordination structure through the proximity effect by forming a chelate ring, ensuring the stability of the formed soluble tin complex. The hydroxyl group reacts with the insoluble tin oxides to form soluble stannates, promoting the formation of Sn-O complexes. 4+Released from sparingly soluble tin oxides; disulfide bonds may break into thiol groups under the mechanical force of ball milling, reacting with Sn. 4+ The formation of Sn-S coordination bonds converts insoluble tin oxides into soluble stannates. Simultaneously, sulfur's coordination ability is stronger than oxygen's, compensating for the insufficient coordination of oxygen and ensuring a greater conversion of insoluble tin into soluble tin. An alkaline co-solvent maintains an alkaline environment, accelerating the release of carboxyl groups, thereby ensuring the conversion rate of soluble tin complexes / soluble stannates.

[0078] After successfully converting the insoluble tin oxides in waste lead paste into soluble tin complexes / soluble stannates, the high concentration of H+ provided by a strong acid was utilized. + Disrupting the original alkaline or neutral conditions, while simultaneously increasing the concentration of H+. + Competitive binding to the coordination sites of complexing agents disrupts the complexation equilibrium, causing the tin in the originally stable soluble tin complex / soluble stannate to undergo decomplexation. Furthermore, a strongly acidic environment can inhibit Sn... 4+ Hydrolysis ensures that tin exists in a soluble form or is converted into tin oxides (such as tin dioxide) after decomplexation; simultaneously, according to Le Chatelier's principle, high concentrations of H₂... + This shifts the reaction equilibrium towards decomplexation, ensuring the complete release of tin from the complex. Furthermore, the strong acid promotes the protonation of the extractant, causing it to dissociate from the soluble tin complex / soluble stannate, enabling the recovery and reuse of the extractant.

[0079] Preferably, ball milling can be replaced by ultrasonic, microwave reaction, or high-pressure high-temperature reaction.

[0080] In this invention, ball milling is used as the primary mixing method. Theoretically, ultrasound can generate localized high temperature and pressure through the cavitation effect of ultrasonic waves, promoting interfacial reactions, but its effect on high-hardness oxides (such as the insoluble tin oxides in this invention) may be weaker than ball milling. Microwave reactions can enhance the reaction through molecular vibration heating, but require stirring to achieve a mechanical activation effect similar to ball milling. High-pressure, high-temperature reactions utilize a high-pressure reactor to create a high-pressure environment to increase the reaction rate, but lack mechanical crushing effect, resulting in lower processing efficiency for insoluble tin oxides. Based on the above considerations, this invention preferentially selects ball milling as the mixing method, but the recovery process achieved using the extractant of this invention can be implemented using other methods such as ultrasound, microwave reactions, or high-pressure, high-temperature reactions.

[0081] Preferably, the amount of the extractant is 2-5 wt% of the waste lead paste.

[0082] Preferably, the ball milling conditions include: a ball-to-material ratio of (5~20):1, a rotation speed of 200~600 rpm, and a time of 10~30 min.

[0083] Ball milling utilizes mechanical activation to reduce particle size, increase specific surface area, and disrupt crystal structure, while also enhancing mass transfer to accelerate the contact reaction. Therefore, this invention employs the cost-effective ball milling method to break down sparingly soluble and highly crystalline tin oxides, and integrates an extractant with the sparingly soluble tin oxides to accelerate their contact reaction.

[0084] In this invention, specific ball-to-material ratios, rotation speeds, and time are selected to achieve the optimal ball milling effect. The ball-to-material ratio affects the collision energy and frequency; too high a ratio leads to excessive equipment load, while too low a ratio results in insufficient activation. In this invention, the ball-to-material ratio is (5~20):1. The rotation speed determines the collision intensity; insufficient rotation speed leads to incomplete reaction, while excessive rotation speed may cause accelerated ball mill wear and introduce impurities. In this invention, the rotation speed is 200~600 rpm. The ball milling time needs to be sufficient to fully refine the insoluble tin oxide particles, but excessive time will lead to secondary particle agglomeration. In this invention, the time is 10~30 min.

[0085] Preferably, the grinding media is cemented carbide balls or zirconia balls.

[0086] The limitation on the ball milling media is to avoid introducing iron and silicon impurities. Other media that can meet this requirement can be used as the ball milling media for this invention, including but not limited to cemented carbide balls or zirconia balls.

[0087] Preferably, the diameter of the ball milling media is 3 to 8 mm.

[0088] Preferably, the waste lead paste has undergone impurity removal treatment.

[0089] Preferably, the waste lead paste is subjected to a crushing process, and the particle size of the crushed waste lead paste is 50-100 mesh.

[0090] Preferably, the liquid-to-solid ratio during water extraction is 3-5 mL / g.

[0091] Preferably, the extraction method is as follows: extraction at 25~40℃ and a rotation speed of 100~200 rpm for 20~30 minutes.

[0092] Preferably, the acid is at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0093] Preferably, the concentration of the acid is 1~2 mol / L.

[0094] Preferably, the reaction is stirred at 25-40°C for 15-20 min, then allowed to stand for 30-60 min, and then dried at 100-110°C for 2-3 h to obtain tin oxide.

[0095] The preferred embodiments of the present invention have been described above, but the present invention is not limited thereto.

[0096]

Example

[0097] In this section, the raw material information is as follows: waste lead paste, from mechanically crushed AGM lead-acid batteries.

[0098] This section describes the mechanisms in the specific embodiments provided, but does not limit the specific embodiments.

[0099] Tin solubilizers: 2-oxoglutaric acid (HOOC-(CH2)2-CO-COOH) and α-lipoic acid (reduced state, HS-(CH2)4-CO-COOH); alkaline co-solvent: sodium hydroxide; tin stabilizer: 1,3-propanediol (HO-CH2CH2CH2-OH).

[0100] 2-Oxopramic acid contains two carboxyl groups and one ketone group, while α-lipoic acid contains one carboxyl group and one disulfide bond. 2-Oxopramic acid and α-lipoic acid must be used together, the key being that their combination simultaneously provides the necessary carboxyl, ketone, and disulfide groups for the reaction. When used alone, 2-Oxopramic acid's oxygen coordination (O-Sn) has limited stability, while α-lipoic acid's sulfur coordination (S-Sn) compensates for this deficiency, forming a coordinated coordination of O and S heteroatoms, significantly improving the stability of the complex. Using α-lipoic acid alone leads to a reduction in the number of carboxyl groups, and the disulfide bond in α-lipoic acid requires ball milling activation, resulting in insufficient complexation sites. If 2-Oxopramic acid or α-lipoic acid is used alone, the corresponding reagent with the missing group must be added. Essentially, the synergy between 2-Oxopramic acid and α-lipoic acid lies in their ability to provide the necessary groups and the required amount of groups for the reaction.

[0101] Sodium hydroxide serves as a source of OH- - The key is to maintain the pH at 9-10 to remove Sn from the insoluble tin oxides in the waste lead paste. 4+ Released; and the carboxyl group is not easily dissociated under neutral / acidic conditions, and cannot effectively react with Sn. 4+ Coordination leads to extremely low complexation efficiency. A lack of sodium hydroxide makes it difficult to dissolve insoluble tin oxides in waste lead paste, resulting in insufficient free Sn. 4+ Continuing the reaction, it is impossible to obtain a sufficient amount of soluble tin complex / soluble stannate.

[0102] 1,3-Propanediol, as an auxiliary enhancer, is not absolutely necessary, but it can stabilize the formed tin complex through hydroxyl coordination and steric hindrance effects, reducing its decomposition or precipitation during ball milling and improving the complexation yield. The absence of 1,3-propanediol has a relatively small impact on the extraction efficiency, but adding 1,3-propanediol can help alleviate the problem of easy aggregation and precipitation of soluble tin complexes, further improving the extraction efficiency of tin.

[0103] The possible reaction formulas involved are as follows: SnO2 + 4HOOC-(CH2)2-CO-COOH + 8OH - →[Sn(C5H7O2)2] 2- +4CO2+6HCOO - +6H2O (1) SnO2 + 2OH - →SnO3 2- +H2O (2); SnO2 + 2HO-CH2CH2CH2-OH + 2OH - →[Sn(O-CH2CH2CH2-O)2] 2- +4H2O (3); Example 1 S1. Pretreatment: The tetravalent tin content in the waste lead paste was found to be 0.05 wt%. After removing impurities, the waste lead paste was pulverized to 80 mesh.

[0104] S2. Wet ball milling: Add 14.6 g of 2-oxoglutaric acid, 10.3 g of α-lipoic acid, 8 g of sodium hydroxide, and 5.7 g of 1,3-propanediol to 1000 g of waste lead paste treated in S1, and stir to mix evenly to obtain a mixture. Then transfer the mixture to a ball mill. The ball milling parameters are: 5 mm diameter zirconia balls as the grinding media, ball-to-material ratio of 8:1, ball milling speed of 300 r / min, and ball milling for 12 min.

[0105] S3. Water extraction: After ball milling, add 3000 mL of deionized water to the mixture obtained from ball milling, maintaining a liquid-solid ratio of 3 mL:1 g. Then, under constant temperature water bath conditions of 30℃, stir and extract for 25 min at 150 r / min.

[0106] S4. Recovery: The material obtained from the S3 water leaching was filtered to separate the leachate and leaching residue. 1.5 mol / L hydrochloric acid was added dropwise to the leachate to adjust the pH to 1.5. The mixture was then stirred at 30°C for 18 min, allowed to stand for 45 min to precipitate, and then vacuum filtered through a 0.45 μm filter membrane to obtain the precipitate. The precipitate was dried at 105°C for 2.5 h to recover tin dioxide.

[0107] The tin recovery rate was 93.5% as tested.

[0108] Example 2 S1. Pretreatment: The tetravalent tin content in the waste lead paste was found to be 0.01 wt%. After removing impurities, the waste lead paste was pulverized to 50 mesh.

[0109] S2. Wet ball milling: Add 8.8 g of 2-oxoglutaric acid, 10.3 g of α-lipoic acid, 8 g of sodium hydroxide, and 5.7 g of 1,3-propanediol to 1000 g of waste lead paste treated in S1, and stir to mix evenly to obtain a mixture. Then transfer the mixture to a ball mill. The ball milling parameters are: 3 mm diameter zirconia balls as the grinding media, ball-to-material ratio of 5:1, ball milling speed of 200 r / min, and ball milling for 10 min.

[0110] S3. Water extraction: After ball milling, add 4000 mL of deionized water to the mixture obtained from ball milling, maintaining a liquid-to-solid ratio of 4 mL:1 g. Then, under constant temperature water bath conditions of 25℃, stir and extract for 20 min at 100 r / min.

[0111] S4. Recovery: The material obtained from the S3 water leaching was filtered to separate the leachate and leaching residue. 1 mol / L sulfuric acid was added dropwise to the leachate to adjust the pH to 1.0. The mixture was then stirred at 25°C for 15 min, allowed to stand for 30 min to precipitate, and then vacuum filtered through a 0.45 μm filter membrane to obtain the precipitate. The precipitate was dried at 105°C for 2.5 h to recover tin dioxide.

[0112] The tin recovery rate was 90.2% as tested.

[0113] Example 3 S1. Pretreatment: The tetravalent tin content in the waste lead paste was found to be 0.1 wt%. After removing impurities, the waste lead paste was pulverized to 100 mesh.

[0114] S2. Wet ball milling: Add 8.8 g of 2-oxoglutaric acid, 15 g of α-lipoic acid, 8 g of sodium hydroxide, and 4.1 g of 1,3-propanediol to 1000 g of waste lead paste treated in S1, and stir to mix evenly to obtain a mixture. Then transfer the mixture to a ball mill. The ball milling parameters are: 8 mm diameter zirconia balls as the grinding media, ball-to-material ratio of 10:1, ball milling speed of 200 r / min, and ball milling for 30 min.

[0115] S3. Water extraction: After ball milling, add 5000 mL of deionized water to the mixture obtained from ball milling, maintaining a liquid-to-solid ratio of 5 mL:1 g. Then, under constant temperature water bath conditions of 40℃, stir and extract for 30 min at 200 r / min.

[0116] S4. Recovery: The material obtained from the S3 water leaching was filtered to separate the leachate and leaching residue. 2 mol / L nitric acid was added dropwise to the leachate to adjust the pH to 2.0. The mixture was then stirred at 40°C for 20 min, allowed to stand for 30 min to precipitate, and then vacuum filtered through a 0.45 μm filter membrane to obtain the precipitate. The precipitate was dried at 110°C for 3 h to recover tin dioxide.

[0117] The tin recovery rate was 94.8% as tested.

[0118] Example 4 (without 1,3-propanediol) S1. Pretreatment: The tetravalent tin content in the waste lead paste was found to be 0.1 wt%. After removing impurities, the waste lead paste was pulverized to 80 mesh.

[0119] S2. Wet ball milling: Add 8.8 g of 2-oxoglutaric acid, 10.3 g of α-lipoic acid, and 8 g of sodium hydroxide to 1000 g of waste lead paste treated in S1, and stir to mix evenly to obtain a mixture. Then transfer the mixture to a ball mill. The ball milling parameters are: 5 mm diameter zirconia balls as the grinding media, ball-to-material ratio of 8:1, ball milling speed of 300 r / min, and ball milling for 12 min.

[0120] S3. Water extraction: After ball milling, add 3000 mL of deionized water to the mixture obtained from ball milling, maintaining a liquid-solid ratio of 3 mL:1 g. Then, under constant temperature water bath conditions of 30℃, stir and extract for 25 min at 150 r / min.

[0121] S4. Recovery: The material obtained from the S3 water leaching was filtered to separate the leachate and leaching residue. 1.5 mol / L hydrochloric acid was added dropwise to the leachate to adjust the pH to 1.5. The mixture was then stirred at 30°C for 18 min, allowed to stand for 45 min to precipitate, and then vacuum filtered through a 0.45 μm filter membrane to obtain the precipitate. The precipitate was dried at 105°C for 2.5 h to recover tin dioxide.

[0122] The tin recovery rate was 81.2% as tested.

[0123] Comparative Example 1 (α-Lipoic acid removed) S1. Pretreatment: The tetravalent tin content in the waste lead paste was found to be 0.1 wt%. After removing impurities, the waste lead paste was pulverized to 80 mesh.

[0124] S2. Wet ball milling: Add 14.6 g of 2-oxoglutaric acid, 8 g of sodium hydroxide, and 5.7 g of 1,3-propanediol to 1000 g of waste lead paste treated in S1, and stir to mix evenly to obtain a mixture. Then transfer the mixture to a ball mill. The ball milling parameters are: 5 mm diameter zirconia balls as the grinding media, ball-to-material ratio of 8:1, ball milling speed of 300 r / min, and ball milling for 12 min.

[0125] S3. Water extraction: After ball milling, add 3000 mL of deionized water to the mixture obtained from ball milling, maintaining a liquid-solid ratio of 3 mL:1 g. Then, under constant temperature water bath conditions of 30℃, stir and extract for 25 min at 150 r / min.

[0126] S4. Recovery: The material obtained from the S3 water leaching was filtered to separate the leachate and leaching residue. 1.5 mol / L hydrochloric acid was added dropwise to the leachate to adjust the pH to 1.5. The mixture was then stirred at 30°C for 18 min, allowed to stand for 45 min to precipitate, and then vacuum filtered through a 0.45 μm filter membrane to obtain the precipitate. The precipitate was dried at 105°C for 2.5 h to recover tin dioxide.

[0127] The tin recovery rate was 71.3% as tested.

[0128] Comparative Example 2 (2-Oxopramic acid removed) S1. Pretreatment: The tetravalent tin content in the waste lead paste was found to be 0.1 wt%. After removing impurities, the waste lead paste was pulverized to 80 mesh.

[0129] S2. Wet ball milling: Add 10.3 g α-lipoic acid, 8 g sodium hydroxide, and 5.7 g 1,3-propanediol to 1000 g of waste lead paste treated in S1, and stir to mix evenly to obtain a mixture. Then transfer the mixture to a ball mill. The ball milling parameters are: 5 mm diameter zirconia balls as the grinding media, ball-to-material ratio of 8:1, ball milling speed of 300 r / min, and ball milling for 12 min.

[0130] S3. Water extraction: After ball milling, add 3000 mL of deionized water to the mixture obtained from ball milling, maintaining a liquid-solid ratio of 3 mL:1 g. Then, under constant temperature water bath conditions of 30℃, stir and extract for 25 min at 150 r / min.

[0131] S4. Recovery: The material obtained from the S3 water leaching was filtered to separate the leachate and leaching residue. 1.5 mol / L hydrochloric acid was added dropwise to the leachate to adjust the pH to 1.5. The mixture was then stirred at 30°C for 18 min, allowed to stand for 45 min to precipitate, and then vacuum filtered through a 0.45 μm filter membrane to obtain the precipitate. The precipitate was dried at 105°C for 2.5 h to recover tin dioxide.

[0132] The tin recovery rate was found to be 70.5%.

Claims

1. An extractant for recovering tin from waste lead paste, characterized in that, The extractant includes a tin solubilizer containing carboxyl, ketone, and disulfide groups, and an alkaline co-solvent; the molar ratio between the carboxyl, ketone, disulfide groups, and hydroxide ions in the alkaline co-solvent is (1.0~4.0):(0.5~3.0):(0.3~2.0):(1.0~5.0); the pH of the extractant is 9~10. The extractant also includes a tin stabilizer containing hydroxyl groups; The carboxyl group in the tin solubilizer is derived from at least one of 2-oxoglutaric acid, oxaloacetic acid, malonic acid, thiosalicylic acid, mercaptosuccinic acid, α-lipoic acid, and succinic acid. The ketone group in the tin solubilizer is derived from at least one of pyruvate, 2-oxoglutarate, and oxaloacetic acid; The disulfide bond in the tin solubilizer is derived from at least one of thiosalicylic acid, mercaptosuccinic acid, α-lipoic acid, and cysteine.

2. The extractant as described in claim 1, characterized in that, The tin stabilizer is a polyhydroxy compound.

3. The extractant as described in claim 1, characterized in that, The tin stabilizer is a polyhydroxy compound with a chain-like structure.

4. The extractant as described in claim 2 or 3, characterized in that, The polyhydroxy compound is at least one of ethylene glycol, 1,3-propanediol, glycerol, and 1,4-butanediol.

5. The extractant as described in claim 2 or 3, characterized in that, In the extractant, the molar ratio between carboxyl groups, ketone groups, disulfide bonds, hydroxyl groups and hydroxide ions in the alkaline co-solvent is (1.0~4.0): (0.5~3.0): (0.3~2.0): (1.0~5.0): (1.0~5.0).

6. The extractant according to any one of claims 1 to 3, characterized in that, The alkaline co-solvent is at least one of sodium hydroxide, potassium hydroxide, and calcium hydroxide.

7. The extractant according to any one of claims 1 to 3, characterized in that, The tin solubilizer includes solubilizer A, which provides both carboxyl and ketone groups, and solubilizer B, which provides both carboxyl and disulfide bonds.

8. The extractant as described in claim 7, characterized in that, The solubilizer A is at least one of 2-oxoglutaric acid and oxaloacetic acid.

9. The extractant as described in claim 7, characterized in that, The solubilizer B is at least one of thiosalicylic acid, mercaptosuccinic acid, and α-lipoic acid.

10. A method for recovering tin from waste lead paste, characterized in that, include: Waste lead paste is mixed with the extractant as described in any one of claims 1 to 9, ball-milled, and then extracted with water to obtain a leachate; Acid is added to the leachate to adjust the pH to 1-2, and tin oxide is recovered; the amount of the extractant used is 1-7 wt% of the waste lead paste.

11. The recycling method as described in claim 10, characterized in that, The ball milling conditions include: a ball-to-material ratio of (5~20):1, a rotation speed of 200~600 rpm, and a time of 10~30 min.

12. The recycling method as described in claim 10, characterized in that, The grinding media are cemented carbide balls or zirconia balls.

13. The recycling method as described in claim 10, characterized in that, The diameter of the ball milling media is 3~8 mm.

14. The recycling method as described in claim 10, characterized in that, The waste lead paste has undergone impurity removal treatment.

15. The recycling method as described in claim 10, characterized in that, The waste lead paste is pulverized, and the particle size of the pulverized waste lead paste is 50~100 mesh.

16. The recycling method as described in claim 10, characterized in that, The liquid-to-solid ratio during water extraction is 3-5 mL / g.

17. The recycling method as described in claim 10 or 16, characterized in that, The extraction method is as follows: extraction is performed at 25~40℃ and 100~200 rpm for 20~30 minutes.

18. The recycling method as described in claim 10, characterized in that, The acid is at least one of hydrochloric acid, sulfuric acid, and nitric acid.

19. The recycling method as described in claim 10 or 18, characterized in that, The concentration of the acid is 1~2 mol / L.

20. The recycling method as described in claim 11, 16, or 18, characterized in that, The mixture is stirred at 25-40℃ for 15-20 min, then allowed to stand for 30-60 min, and finally dried at 100-110℃ for 2-3 h to obtain tin oxide.