Method for recycling tin from lead-tin-containing waste residues

Abstract

The invention discloses a method for recycling tin from lead-tin-containing waste residues, and belongs to the technical field of solid waste recycling. The method comprises the following steps that sodium chloride, imidazole chloride ionic liquid and fatty acid are added into water to be mixed, and a pH regulator is used for regulating the system to be acidic to obtain leachate; and adding the lead-tin-containing waste residues into the leaching solution, leaching, and carrying out solid-liquid separation to obtain filtrate and tin residues. Aiming at the two defects that although lead can be effectively dissolved in a traditional high-chlorine environment, high-chlorine residues and tin dissolution risks exist, chlorine entrainment in slag is reduced from the source, the environmental protection pressure is reduced, meanwhile, treatment after separation is optimized, and the tin recovery rate is increased. According to the scheme, efficient dissolution of lead and stabilization of tin are realized while the consumption of chlorine salt is reduced, the environment-friendly bottleneck of a traditional high-chlorine process is solved, and the separation efficiency is guaranteed.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste resource utilization, and particularly relates to a method for recovering tin from lead-tin-containing waste residue. BACKGROUND

[0002] In the lead-tin-containing waste residue, tin mainly exists in the form of various compounds. The treatment of tin-containing lead residue is mostly carried out by using a fractionalization method to preliminarily remove tin. The crude lead is heated to a certain temperature, and tin is first fractionalized and separated at a lower temperature by using the difference in melting points of tin and lead. However, the tin removal effect of this method is limited, and a large amount of tin still remains in the lead, making it difficult to achieve efficient separation and recovery of tin. Alternatively, a pyrometallurgical smelting method is used, that is, the lead residue is mixed with a reducing agent and smelted in a high-temperature furnace to reduce tin from the compound. However, this pyrometallurgical smelting process has extremely high energy consumption and produces a large amount of harmful gases such as sulfur dioxide and lead vapor, which causes serious environmental pollution and also increases the treatment cost and process complexity. The crude tin obtained through smelting still contains a large amount of impurities such as lead, iron, and arsenic, which need to be further refined.

[0003] To address these problems, hydrometallurgical technology has gradually attracted attention. Tin is leached from the waste residue by acid leaching or alkali leaching, and then separated and purified by electro-deposition or chemical precipitation. However, the wet process also has some defects, such as a long process, a large amount of chemical reagent consumption, and complex impurities in the leaching solution, which increases the difficulty of subsequent separation and purification. In addition, a large amount of heavy metal-containing wastewater generated during the leaching process needs to be properly treated, otherwise it will cause secondary pollution to the environment.

[0004] Current improvements in hydrometallurgy still have some problems. For example, the existing technology still does not effectively control the environmental impact when treating lead-tin-containing waste residue, especially in the treatment of harmful gases and wastewater, and the process still needs to be further optimized. The comprehensive recovery and utilization of other valuable metals in lead-tin-containing waste residue is still not sufficient, and a large amount of valuable metals are wasted or not effectively separated during the recovery process. Therefore, how to optimize the leaching conditions, develop efficient separation and purification technology, and improve the recovery rate and purity of tin is still a problem that needs to be solved. SUMMARY

[0005] The purpose of the present application is to provide a method for recovering tin from lead-tin-containing waste residue to solve the problem of low recovery rate of tin separation in the process of recovering tin from lead-tin-containing waste residue by wet process.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] The application provides a method for recovering tin from lead-tin waste residue, comprising the following steps: adding sodium chloride, imidazole chloride salt ionic liquid and fatty acid into water to mix, adjusting the system to be acidic by using a pH regulator to obtain a leaching solution; adding the lead-tin waste residue into the leaching solution to leach, and obtaining a filtrate and tin residue after solid-liquid separation.

[0008] The tin residue is washed to recover tin, and the washing liquid is recovered as raw material of the leaching solution.

[0009] The filtrate is adjusted to be alkaline to precipitate lead, the obtained precipitated lead is washed to obtain lead residue, and the washing liquid is recovered to be used as raw material of the leaching solution.

[0010] In the application, no three wastes are discharged in the whole recovery process, which is environmentally friendly and belongs to a green circular process. The recovery rate is high, the lead residue and the tin residue are sent to lead and tin smelting respectively, and can be sold separately. After the separation of lead and tin, the grade of the tin residue is greatly improved, and the economic benefits of recovery are improved.

[0011] Under the condition of strong acidity and high concentration of sodium chloride solution, lead ions can form various complexes with chloride ions, and the higher the concentration of chloride ions, the more stable it is. In a high chlorine environment, lead ions are difficult to precipitate, while tin ions have low solubility in this environment, thereby realizing the separation of lead and tin. However, this method will result in a large amount of chloride ions in the separated substance, and the process of recovering chloride ions will increase and consume a large amount of solvent, increase the cost, and have poor environmental performance. In the leaching solution of the application, sodium chloride, imidazole chloride salt ionic liquid, fatty acid and pH regulator are included. The introduction of imidazole chloride salt ionic liquid can improve the solubility and stability of lead ions in a low-concentration sodium chloride and weak acidic environment. The introduced imidazole chloride salt ionic liquid provides more cationic centers, which are stable in nature, and can form an ionic liquid-Pb-Cl ternary complex with Pb 2+ , thereby significantly improving the solubility of lead. In a low-chlorine environment, the Cl- and cationic centers in the imidazole chloride salt ionic liquid can form stable complexes or compounds with tin, especially under weak acidic conditions (pH 2-3), which can accelerate the dissolution of tin residue. The fatty acid is chemically stable in hydrochloric acid at room temperature and is physically dispersed in the solution in a weak acidic environment. It selectively adsorbs lead complexes and promotes the migration of lead to the liquid phase. Not only can the use amount of ionic liquid be reduced to improve the solubility of lead, but also the fatty acid can wrap the tin residue particles to form a hydrophobic layer to inhibit the dissolution of the tin residue.

[0012] Further, the concentration of sodium chloride in the leaching solution is 100-120 g / L;

[0013] The pH regulator is hydrochloric acid, and the pH value of the leaching solution is adjusted to 2-3;

[0014] The concentration of imidazole chloride salt ionic liquid is 5-10 g / L;

[0015] The concentration of the fatty acid is 0.5-0.6 mol / L.

[0016] Low-chlorine operation: small amount of NaCl is used, and the chlorine entrainment in the residue is reduced from the source;

[0017] Ionic liquid recovery: the imidazole chloride salt has high thermal stability and can be recovered from the washing water by distillation for reuse;

[0018] Fatty acid circulation: no reaction in hydrochloric acid at room temperature, and reuse through simple phase separation.

[0019] Further, the fatty acid is one of oleic acid or stearic acid.

[0020] Further, the mass fraction of lead in the lead-tin-containing waste residue is 15%-20%, and the mass fraction of tin is 2%-12%; the solid-liquid ratio of the lead-tin-containing waste residue and the leaching solution is 1:8-20.

[0021] Further, the leaching temperature is 25-30℃, and the leaching time is 30-40 min.

[0022] Further, the pH value of the filtrate is adjusted to 9.5-10, and the reagent used for adjusting the pH value is sodium carbonate or sodium hydroxide.

[0023] Further, the imidazole chloride ionic liquid is prepared by the following steps:

[0024] Under a nitrogen atmosphere, alkyl imidazole and chlorinated hydrocarbon are added to ethanol, the temperature is set to 78℃, and reflux reaction is carried out for 6-24 h; after the reaction is completed, ethanol is removed by reduced pressure distillation, and recrystallization is carried out with anhydrous diethyl ether to obtain the imidazole chloride ionic liquid.

[0025] Further, the molar ratio of the amount of alkyl imidazole to chlorinated hydrocarbon is 1:1.1-1.2.

[0026] Further, the chlorinated hydrocarbon is one of 1-chloropentane, chlorohexane and chlorononane.

[0027] Further, the alkyl imidazole is one of N-n-hexadecyl imidazole, 1-octyl imidazole, 2-butyl imidazole, 1-propyl imidazole and N-methyl imidazole.

[0028] The beneficial effects of the present application are:

[0029] The present application provides a method for recovering tin from lead-containing tin waste residue, which aims at the two defects of high-chlorine residue and tin dissolution risk in the traditional high-chlorine environment which can effectively dissolve lead. The present application realizes efficient lead-tin separation in a low-concentration NaCl and weakly acidic environment by designing a composite leaching system and utilizing the synergistic effect of imidazole chloride ionic liquid and fatty acid. The imidazole chloride ionic liquid provides a stable coordination center, and the fatty acid provides a weak acid environment, which can effectively separate lead and tin. 2+The formation of ternary complex significantly improves the solubility of lead; the fatty acid selectively adsorbs the lead complex to promote the migration of lead, and at the same time, it wraps the tin residue particles to form a hydrophobic layer to inhibit the dissolution of tin residue. Through low-chlorine operation, recycling of ionic liquid and fatty acid, this scheme reduces the environmental pressure from the source by reducing the chlorine entrainment in the residue, optimizes the separation post-treatment, and improves the recovery rate of tin. This scheme reduces the amount of chloride salt while achieving efficient dissolution of lead and stabilization of tin, solving the environmental bottleneck of the traditional high-chlorine process and ensuring the separation efficiency. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0031] The following is a detailed description of a method for recovering tin from lead-containing tin waste residue according to an embodiment of the present application.

[0032] Tin soot is a kind of tin-containing waste, and its main raw material source is various waste electronic products such as televisions and computers. A large amount of lead-containing tin waste residue is generated during the recycling process. First, acid leaching is used to remove part of other metal ions in the tin soot and reduce interference. Specifically, the tin soot is added to sulfuric acid with a concentration of 60 g / L, soaked and filtered, and the obtained lead-containing tin waste residue contains 31.32% lead and 12.36% tin. The following examples and comparative examples use this lead-containing tin waste residue for recovery treatment.

[0033] The following will be specifically described with reference to the examples.

[0034] Example 1

[0035] The present embodiment provides a method for recovering tin from lead-containing tin waste residue, comprising the following steps: adding sodium chloride, imidazole chloride salt ionic liquid and fatty acid into water to mix, and using a pH adjuster to adjust the system to be acidic to obtain a leaching solution; adding the lead-containing tin waste residue into the leaching solution to leach, and obtaining a filtrate and tin residue after solid-liquid separation. The concentration of sodium chloride in the leaching solution is 100 g / L; the pH adjuster is hydrochloric acid, and the pH value of the leaching solution is adjusted to 2; the concentration of the imidazole chloride salt ionic liquid is 10 g / L; and the concentration of the fatty acid is 0.6 mol / L. The solid-liquid ratio of the lead-containing tin waste residue and the leaching solution is 1:15. The leaching temperature is 30°C, the leaching time is 30 min, and the fatty acid is oleic acid.

[0036] The imidazole chloride salt ionic liquid is prepared by the following steps:

[0037] Under nitrogen atmosphere, alkyl imidazole and chlorohydrocarbon were added into ethanol, the temperature was set at 78℃, and the reaction was refluxed for 10 hours. After the reaction was completed, ethanol was removed by vacuum distillation, and recrystallization was performed with anhydrous ether to obtain imidazole chloride ionic liquid. The molar ratio of alkyl imidazole and chlorohydrocarbon was 1:1.1. The chlorohydrocarbon was 1-chloropentane, and the alkyl imidazole was N-methyl imidazole.

[0038] The tin residue was washed with water to recover tin, and the washing liquid was recovered as raw material of the leaching liquid. The filtrate was adjusted to be alkaline to precipitate lead, the obtained precipitated lead was washed to obtain lead residue, and the washing liquid was recovered to be used as raw material of the leaching liquid. The pH value of the filtrate was adjusted to 10, and the reagent used for adjusting the pH value was sodium carbonate.

[0039] Example 2

[0040] The embodiment provides a method for recovering tin from lead-containing tin waste residue, which is different from example 1 in that the raw material ratio in the leaching liquid is changed, and the method comprises the following steps:

[0041] Sodium chloride, imidazole chloride ionic liquid and fatty acid were added into water to mix, and a pH adjuster was used to adjust the system to be acidic to obtain a leaching liquid. The lead-containing tin waste residue was added into the leaching liquid to perform leaching, and the leaching liquid and tin residue were obtained after solid-liquid separation. The concentration of sodium chloride in the leaching liquid was 110 g / L. The pH adjuster was hydrochloric acid, and the pH value of the leaching liquid was adjusted to 2. The concentration of the imidazole chloride ionic liquid was 8 g / L. The concentration of the fatty acid was 0.5 mol / L. The solid-liquid ratio of the lead-containing tin waste residue and the leaching liquid was 1:15. The leaching temperature was 30℃, the leaching time was 30 min, and the fatty acid was oleic acid. The imidazole chloride ionic liquid was the same as that in example 1, and the other raw materials and preparation process were the same as those in example 1.

[0042] Example 3

[0043] The embodiment provides a method for recovering tin from lead-containing tin waste residue, which is different from example 1 in that the raw material ratio in the leaching liquid is changed, and the method comprises the following steps:

[0044] Sodium chloride, imidazole chloride ionic liquid and fatty acid were added into water to mix, and a pH adjuster was used to adjust the system to be acidic to obtain a leaching liquid. The lead-containing tin waste residue was added into the leaching liquid to perform leaching, and the leaching liquid and tin residue were obtained after solid-liquid separation. The concentration of sodium chloride in the leaching liquid was 110 g / L. The pH adjuster was hydrochloric acid, and the pH value of the leaching liquid was adjusted to 2. The concentration of the imidazole chloride ionic liquid was 8 g / L. The concentration of the fatty acid was 0.5 mol / L. The solid-liquid ratio of the lead-containing tin waste residue and the leaching liquid was 1:15. The leaching temperature was 30℃, the leaching time was 30 min, and the fatty acid was oleic acid. The imidazole chloride ionic liquid was the same as that in example 1, and the other raw materials and preparation process were the same as those in example 1.

[0045] Example 4

[0046] The embodiment provides a method for recovering tin from lead-containing tin waste residue, and the difference from the example 1 is that the fatty acid is stearic acid, and the rest of the raw materials and the preparation process are the same as those of the example 1.

[0047] Example 5

[0048] The embodiment provides a method for recovering tin from lead-containing tin waste residue, and the difference from the example 1 is that the solid-liquid ratio of the lead-containing tin waste residue and the leaching solution is changed to 1:8, and the rest of the raw materials and the preparation process are the same as those of the example 1.

[0049] Example 6

[0050] The embodiment provides a method for recovering tin from lead-containing tin waste residue, and the difference from the example 1 is that the imidazole chloride ionic liquid is different, and the specific is that:

[0051] The imidazole chloride ionic liquid is prepared through the following steps:

[0052] Under the nitrogen atmosphere, alkyl imidazole and chlorinated hydrocarbon are added into ethanol, the temperature is set to 78 DEG C, the reflux reaction is carried out for 10 h, after the reaction is completed, the ethanol is removed through the reduced pressure distillation, the anhydrous diethyl ether is used for recrystallization, and the imidazole chloride ionic liquid is obtained; the molar ratio of the alkyl imidazole and the chlorinated hydrocarbon is 1:1.1. The chlorinated hydrocarbon is 1-chloropentane, and the alkyl imidazole is 1-octyl imidazole.

[0053] The rest of the raw materials and the preparation process are the same as those of the example 1.

[0054] Example 7

[0055] The embodiment provides a method for recovering tin from lead-containing tin waste residue, and the difference from the example 1 is that the imidazole chloride ionic liquid is different, and the specific is that:

[0056] The imidazole chloride ionic liquid is prepared through the following steps:

[0057] Under the nitrogen atmosphere, alkyl imidazole and chlorinated hydrocarbon are added into ethanol, the temperature is set to 78 DEG C, the reflux reaction is carried out for 10 h, after the reaction is completed, the ethanol is removed through the reduced pressure distillation, the anhydrous diethyl ether is used for recrystallization, and the imidazole chloride ionic liquid is obtained; the molar ratio of the alkyl imidazole and the chlorinated hydrocarbon is 1:1.1, the chlorinated hydrocarbon is chlorohexane, and the alkyl imidazole is 1-octyl imidazole.

[0058] The rest of the raw materials and the preparation process are the same as those of the example 1.

[0059] Example 8

[0060] The embodiment provides a method for recovering tin from lead-containing tin waste residue, and the difference from the embodiment 1 is that the imidazole chloride salt ionic liquid is different, and the specific difference is as follows:

[0061] The imidazole chloride salt ionic liquid is prepared through the following steps:

[0062] Under a nitrogen atmosphere, alkyl imidazole and chlorinated hydrocarbon are added into ethanol, the temperature is set to 78 DEG C, and reflux reaction is carried out for 10 hours; after the reaction is completed, ethanol is removed through reduced pressure distillation, and anhydrous diethyl ether is used for recrystallization, so that the imidazole chloride salt ionic liquid is obtained; the molar ratio of the alkyl imidazole and the chlorinated hydrocarbon is 1:1.1. The chlorinated hydrocarbon is chlorohexane, and the alkyl imidazole is N-n-hexadecyl imidazole.

[0063] The remaining raw materials and preparation processes are the same as those in the embodiment 1.

[0064] Comparative example 1

[0065] The comparative example is compared with the embodiment 1, and the difference is that no fatty acid is added, and the remaining raw materials and preparation processes are the same as those in the embodiment 1.

[0066] Comparative example 2

[0067] The comparative example is compared with the embodiment 1, and the difference is that no imidazole chloride salt ionic liquid is added, and the remaining raw materials and preparation processes are the same as those in the embodiment 1.

[0068] Comparative example 3

[0069] The comparative example is compared with the embodiment 1, and the difference is that no fatty acid and no imidazole chloride salt ionic liquid are added, and the remaining raw materials and preparation processes are the same as those in the embodiment 1.

[0070] Comparative example 4

[0071] The comparative example is compared with the comparative example 3, and the difference is that the concentration of sodium chloride in the leaching solution is increased from 110 g / L to 250 g / L, and the remaining raw materials and preparation processes are the same as those in the comparative example 3.

[0072] The lead leaching rate, the tin leaching rate and the tin recovery rate in the embodiment 1 to the embodiment 8 and the comparative example 1 to the comparative example 3 are recorded and compared, and the results are shown in Table 1.

[0073] Table 1

[0074] Item Lead leach rate / % Tin leach rate / % Tin recovery / % Example 1 ＞99 ＜1 96.62 Example 2 ＞99 ＜1 95.67 Example 3 ＞99 ＜1 96.36 Example 4 ＞99 ＜1 97.02 Example 5 ＞99 ＜1 96.11 Example 6 ＞99 ＜1 97.11 Example 7 ＞99 ＜1 98.36 Example 8 ＞99 ＜1 98.76 Comparative Example 1 97.85 8.36 - Comparative Example 2 64.32 2.24 - Comparative Example 3 42.36 12.31 - Comparative Example 4 84.6 32.63 -

[0075] Note: In Table 1, the lead leaching rate and the tin leaching rate refer to the leaching rates of lead and tin in the filtrate, the tin recovery rate refers to the recovery rate of tin in the tin residue after solid-liquid separation, and “-” in Table 1 indicates that no test is performed.

[0076] As can be seen from Table 1, the lead leaching rate in the method for recovering tin from lead-containing tin waste residue provided by the application is > 99%, and the tin leaching rate is < 1.5%. The combination of sodium chloride, a pH adjuster, a fatty acid and an imidazole chloride ionic liquid in Examples 1-8 synergistically improves the lead leaching rate and tin recovery rate. According to the comparison between Example 1 and Comparative Examples 1-4, the introduction of the fatty acid and the imidazole chloride ionic liquid is conducive to improving the lead leaching rate and reducing the tin leaching rate. According to the data in Table 1 in combination with Examples 1 and 6-8, different imidazole chloride ionic liquids have an effect on the recovery result. Among them, the long alkyl chain in the imidazole chloride ionic liquid provides strong hydrophobicity, promotes the migration of lead complexes to the ionic liquid rich phase, and cooperates with the fatty acid to form a dense coating layer covering the surface of the tin residue, thereby inhibiting the loss of tin leaching.

[0077] It should be noted that the relational terms herein such as first and second and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0078] Although embodiments of the application have been shown and described, it is to be understood that various modifications, substitutions, replacements and variations can be made to these embodiments without departing from the principles and spirit of the application, and the scope of the application is defined by the appended claims and their equivalents.

Claims

1. A method for recovering tin from lead-containing tin waste residue, characterized by, The method comprises the following steps: adding sodium chloride, imidazole chloride ionic liquid and fatty acid into water to mix, adjusting the system to be acidic by using a pH regulator to obtain a leaching solution; adding lead and tin containing waste residue into the leaching solution to leach, and obtaining a filtrate and tin residue after solid-liquid separation.

2. The method for recovering tin from lead-tin slag according to claim 1, wherein The concentration of sodium chloride in the leaching solution is 100-120 g / L; the pH regulator is hydrochloric acid, and the pH value of the leaching solution is adjusted to 2-3; the concentration of the imidazole chloride ionic liquid is 5-10 g / L; and the concentration of the fatty acid is 0.5-0.6 mol / L.

3. The method for recovering tin from lead-tin slag according to claim 1, characterized in that, The fatty acid is oleic acid or stearic acid.

4. The method for recovering tin from lead-tin slag according to claim 1, wherein The mass fraction of lead in the lead and tin containing waste residue is 15%-20%, and the mass fraction of tin is 2%-12%; the solid-liquid ratio of the lead and tin containing waste residue and the leaching solution is 1:8-20.

5. The method for recovering tin from lead-tin slag according to claim 1, wherein The leaching temperature is 25-30 DEG C, and the leaching time is 30-40 min.

6. The method for recovering tin from lead-tin slag according to claim 1, wherein The tin residue is washed to recover tin, and the washing liquid is recovered as raw material of the leaching solution; The filtrate is adjusted to be alkaline to precipitate lead, the obtained lead precipitate is washed to obtain lead residue, and the washing liquid is recovered to be used as raw material of the leaching solution; the pH value of the filtrate is adjusted to 9.5-10, and the reagent used for adjusting the pH value is sodium carbonate or sodium hydroxide.

7. The method according to claim 1, wherein the lead-tin slag is a waste slag from a lead-tin alloy production process. The imidazole chloride ionic liquid is prepared by the following steps: Under a nitrogen atmosphere, alkyl imidazole and chlorinated hydrocarbon are added into ethanol, the temperature is set to 78 DEG C, and reflux reaction is carried out for 6-24 h; after the reaction is completed, ethanol is removed by reduced pressure distillation, and anhydrous diethyl ether is used for recrystallization to obtain the imidazole chloride ionic liquid.

8. The method according to claim 7, wherein the lead-tin slag is a lead-tin solder waste slag. The molar ratio of the alkyl imidazole and the chlorinated hydrocarbon is 1:1.1-1.

2.

9. The method for recovering tin from lead-tin slag according to claim 7, wherein The chlorinated hydrocarbon is one of 1-chloropentane, chlorohexane and chlorononane.

10. The method for recovering tin from lead-tin slag according to claim 7, wherein The alkyl imidazole is one of N-n-hexadecyl imidazole, 1-octyl imidazole, 2-butyl imidazole, 1-propyl imidazole and N-methyl imidazole.