Method for removing lead from lead-containing acid solution

Abstract

The invention discloses a lead removal method for a lead-containing acid solution. The lead removal method comprises the following steps: S1, adjusting the temperature of a lead-containing acid solution to 0-15 DEG C; s2, adding lead sulfate seed crystals into the lead-containing acid solution, continuously controlling the temperature to be 0-15 DEG C, and inducing lead ions to be crystallized and separated out through the lead sulfate seed crystals; and carrying out solid-liquid separation until no lead ion crystals are separated out, so as to obtain lead-containing crystal slag and lead-removed acid wastewater. According to the lead removal method for the lead-containing acid solution, through the synergistic effect of inhibiting the solubility of lead sulfate at a low temperature and strengthening crystallization by the seed crystal, high-efficiency recovery of lead is realized under nearly zero addition of chemical agents, meanwhile, the stability of a ferric sulfate solution system is reserved to the maximum extent, and the method has both environmental protection property and economical efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal wastewater treatment, in particular to a method for removing lead from a lead-containing acidic solution. Background Art

[0002] The basic principle of the acid leaching process is to use an acidic solution to react chemically with the metal in the solid material to dissolve the metal ions into the solution. Common acid leaching agents include sulfuric acid, hydrochloric acid, nitric acid, etc. Among them, sulfuric acid is the most commonly used acid leaching agent because of its low price and mild reaction conditions.

[0003] When sulfuric acid is used to treat lead-containing materials, lead ions (Pb 2+ ) is easily mixed into the solution, resulting in lead-containing ferric sulfate waste liquid; in metallurgical waste liquid, lead-acid battery recycling, electronic waste treatment and other scenarios, there is also lead-containing acidic waste liquid that needs to be treated. The existing treatment methods for removing metal ions from acidic wastewater include sulfide precipitation method and adsorption method.

[0004] Sulfide precipitation is a chemical precipitation method used to remove heavy metal ions from wastewater. By adding sulfide precipitants (such as hydrogen sulfide, sodium sulfide, potassium sulfide, sodium hydrogen sulfide, etc.) to the wastewater, heavy metal ions react with sulfur ions to form insoluble sulfide precipitates, thereby achieving the purpose of separation and purification. Sulfide precipitation has the advantages of high efficiency, stability, economy and environmental protection in treating heavy metal wastewater. However, it has the following disadvantages: First, the sulfide precipitation method requires excessive addition of sulfide precipitants to ensure complete precipitation of heavy metal ions. However, excessive addition of sulfide precipitant not only increases the treatment cost, but may also cause secondary pollution; second, the pH needs to be adjusted to alkaline during the sulfide precipitation method, which easily causes co-precipitation of iron ions, resulting in an iron loss rate of between 5% and 10%, which not only reduces the treatment efficiency but also increases the complexity of subsequent treatment; third, the sulfide precipitant is prone to produce toxic hydrogen sulfide gas under acidic conditions, causing secondary pollution. Therefore, the pH value of the solution needs to be strictly controlled to avoid the generation of toxic hydrogen sulfide gas. If hydrogen sulfide gas is produced, further treatment is required to remove hydrogen sulfide, which increases the complexity and cost of the process.

[0005] Adsorption is the use of porous solid adsorbents (such as activated carbon, zeolite, molecular sieve, etc.) to adsorb organic pollutants or heavy metal ions in wastewater. The adsorption process can be achieved through physical adsorption (van der Waals force) or chemical adsorption (chemical bond formation). The adsorption method has the advantages of high efficiency, economy, simple operation, and strong adaptability in wastewater treatment. It is a widely used and promising wastewater treatment technology. However, it has the following disadvantages. First, the operating cost of the adsorption method is high, especially the use cost of high-performance adsorbents such as activated carbon and metal oxides is high, and the regeneration is difficult, resulting in frequent replacement of adsorbents and high operating and processing costs. Second, the selectivity of the adsorbent is poor, and it is difficult to efficiently remove specific pollutants; third, the adsorbent is difficult to regenerate, and it needs to be heated for regeneration, which consumes a lot of energy, and it is easy to collapse during the regeneration process, making it difficult to restore its adsorption capacity; fourth, the iron loss rate is between 30% and 40%, and the subsequent treatment process is complicated, which is not conducive to recycling.

[0006] The prior art methods for treating lead-containing acidic waste liquid have at least the following defects: (1) In the prior art, when lead-containing acidic waste liquid is treated by sulfidation precipitation method, it has the disadvantages of high treatment cost, high iron loss rate, and may cause secondary pollution, increase the complexity of the process flow and treatment cost; (2) In the prior art, when lead-containing acidic waste liquid is treated by adsorption, it has the disadvantages of high treatment cost, poor selectivity of adsorbent and high energy consumption. Summary of the invention

[0007] The invention discloses a lead removal method for a lead-containing acidic solution, so as to solve the technical problems in the prior art that the lead-containing acidic solution has high treatment cost, high iron loss rate, may cause secondary pollution, and increase the complexity of the process flow and the treatment cost.

[0008] In order to solve the above problems, the present invention adopts the following technical solutions: In a first aspect, the present application provides a method for removing lead from a lead-containing acidic solution, comprising the following steps: S1. Adjust the temperature of the lead-containing acid solution to 0°C to 15°C; S2. Adding lead sulfate seed crystals to the lead-containing acidic solution, continuing to control the temperature at 0°C to 15°C, inducing the crystallization of lead ions through the lead sulfate seed crystals until no more lead ions are crystallized; then performing solid-liquid separation to obtain lead-containing crystalline slag and lead-free acidic wastewater.

[0009] Furthermore, in step S1, the temperature of the lead-containing acidic solution is controlled at 3°C ​​to 12°C.

[0010] Furthermore, in step S1, the temperature of the lead-containing acidic solution is controlled at 3°C ​​to 7°C.

[0011] Furthermore, in step S2, the lead sulfate seed crystals are micron-sized lead sulfate seed crystals; And / or, the lead sulfate seed crystals are added in an amount of 0.1 g / L to 1 g / L of the lead-containing acidic solution; And / or, the lead ion crystallization is carried out under low-speed stirring; And / or, during the lead ion crystallization process, the temperature is controlled at 3°C ​​to 12°C.

[0012] Furthermore, in step S2, the particle size of the lead sulfate seed crystal is 1 μm to 5 μm; And / or, the lead sulfate seed crystals are added in an amount of 0.3 g / L to 0.8 g / L of the lead-containing acidic solution; And / or, the lead ion crystallization is carried out by stirring at a stirring rate of 50 rpm to 100 rpm for 2 to 4 hours; And / or, during the lead ion crystallization process, the temperature is controlled at 3°C ​​to 7°C.

[0013] Furthermore, in step S2, the solid-liquid separation is performed using a plate and frame filter press.

[0014] Furthermore, the method further comprises pre-treating the lead-containing acidic solution, wherein the pre-treatment is adding EDTA-2Na to the lead-containing acidic solution; The preprocessing is before step S1; or, the preprocessing is after step S1 and before step S2.

[0015] Furthermore, the dosage of the EDTA-2Na is 0.1 g / L to 1 g / L of the lead-containing acidic solution.

[0016] Furthermore, the dosage of the EDTA-2Na is 0.3 g / L to 0.8 g / L of the lead-containing acidic solution.

[0017] Furthermore, during the pretreatment, after the addition of EDTA-2Na, the stirring rate is controlled to be 50 rpm to 100 rpm and the stirring is continued for 2 to 4 hours.

[0018] The technical solution adopted by the present invention can achieve the following beneficial effects: The lead removal method of the lead-containing acidic solution in the present application selectively removes or selectively recovers lead by suppressing the solubility of lead sulfate at low temperature and strengthening crystallization with seed crystals, and realizes efficient recovery or removal of lead with almost zero chemical agent addition, while retaining the stability of the ferric sulfate solution system to the maximum extent, being both environmentally friendly and economical, and can be used for the selective recovery or removal of lead in lead-containing acidic wastewater, and can also be used for the selective recovery or removal of lead in lead-containing acidic solutions. Specifically, it has the following advantages: (1) It has high selectivity for lead, and the lead removal rate in lead-containing acidic solution can reach ≥99.8%, and the iron loss rate is ≤0.5% during the lead removal process; (2) The resource recycling rate is high. When the lead removal method in this application is used to treat the lead-acid battery leachate, the lead is selected for recovery due to its high lead content. The lead removal method in this application achieves efficient lead recovery. The lead content of the obtained lead-containing crystalline slag is greater than 60%, which can be directly used as a raw material for lead smelting; the obtained lead-removed acidic wastewater can also be used as a leaching agent for hydrometallurgical zinc smelting after the residual impurities are adsorbed by activated carbon. When the lead removal method in this application is used to treat the lead-containing iron sulfate leachate obtained by the acid leaching process, since the waste liquid itself has a low lead content and a high iron content, the lead is selected for removal and the iron is recovered. The lead removal method in the present application achieves efficient removal of lead, and the obtained lead-containing crystalline slag is treated as solid waste and can be disposed of as hazardous waste (HW31 category). Due to the small iron loss, the subsequent separation of iron and other metals through additional steps (such as acid leaching and magnetic separation) is avoided, simplifying the treatment process; the obtained lead-removed acidic wastewater can be used to produce iron-containing compounds (such as iron sulfate, iron phosphate, etc.) after activated carbon adsorbs residual impurities, and due to the small iron loss, the output of iron-containing compounds can also be increased, improving resource utilization and avoiding waste of resources. In addition to being used for lead removal from lead-acid battery leachates and iron sulfate leachates, the lead removal method in the present application can also be used for lead removal from other lead-containing acidic wastewaters and other lead-containing acidic solutions.

[0019] (3) The cost of wastewater treatment is low. Compared with the adsorption method which requires heating to regenerate the solid adsorbent, it has the advantage of low energy consumption, which is reduced by about 40%, significantly reducing the cost of wastewater treatment. Moreover, compared with the existing sulfide precipitation method, there is no need to add a large amount of chemical precipitant, which significantly reduces the cost of wastewater treatment. Therefore, compared with the adsorption method and sulfide precipitation method in the prior art, the lead removal method in this application has a lower treatment cost.

[0020] (4) Environmentally friendly, it can achieve efficient recovery or removal of lead with almost zero addition of chemical agents, which is beneficial to the environment and avoids secondary pollution. DETAILED DESCRIPTION

[0021] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0022] 1. Sample The following examples and comparative examples were all carried out using the following samples.

[0023] Sample 1: Lead-containing iron sulfate leaching solution obtained by acid leaching process, containing Pb 2+ 500mg / L, Fe 3+ 80g / L, pH=2; Sample 2: Lead-acid battery leachate, containing Pb 2+ 3000mg / L, pH=0.5.

[0024] 2. Embodiment Embodiment 1: The lead-containing acidic solution in this embodiment is a lead-containing iron sulfate leaching solution (sample 1) obtained by an acid leaching process, and the lead removal includes the following steps: S1, take Pb 2+ 500mg / L, Fe 3+ 1m³ of 80g / L, pH=2 iron sulfate leaching solution, precooled to 5℃; S2, stirring at a stirring rate of 75 rpm, adding lead sulfate seeds with a particle size of 3 μm into the ferric sulfate leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 0.5 kg (added according to the volume of 0.5 g / L of the ferric sulfate leachate); during the lead ion crystallization and precipitation, the temperature is controlled to be 5° C., the stirring rate is 75 rpm, and the stirring time is 3 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0025] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ concentration.

[0026] Embodiment 2: The lead-containing acidic solution in this embodiment is a lead-containing iron sulfate leaching solution (sample 1) obtained by an acid leaching process, and the lead removal includes the following steps: S1, take Pb 2+ 500mg / L, Fe 3+ 1m³ of 80g / L, pH=2 iron sulfate leaching solution, precooled to 0℃; S2, stirring at a stirring rate of 90 rpm, adding lead sulfate seeds with a particle size of 1 μm into the ferric sulfate leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 0.1 kg (added according to the volume of 0.1 g / L of the ferric sulfate leachate); during the lead ion crystallization and precipitation, the temperature is controlled to be 0° C., the stirring rate is 90 rpm, and the stirring time is 2.5 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0027] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ concentration.

[0028] Embodiment 3: The lead-containing acidic solution in this embodiment is a lead-containing iron sulfate leaching solution (sample 1) obtained by an acid leaching process, and the lead removal includes the following steps: S1, take Pb 2+ 500mg / L, Fe 3+ 1m³ of 80g / L, pH=2 iron sulfate leaching solution, precooled to 10℃; S2, stirring at a stirring rate of 60 rpm, adding lead sulfate seeds with a particle size of 5 μm into the ferric sulfate leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 1 kg (added according to the volume of 1 g / L of the ferric sulfate leachate); during the lead ion crystallization and precipitation, the temperature is controlled at 10° C., the stirring rate is 60 rpm, and the stirring time is 4 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0029] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ concentration.

[0030] Embodiment 4: The lead-containing acidic solution in this embodiment is a lead-containing iron sulfate leaching solution (sample 1) obtained by an acid leaching process, and the lead removal includes the following steps: S1, take Pb 2+ 500mg / L, Fe 3+ 1m³ of 80g / L, pH=2 iron sulfate leaching solution, precooled to 15℃; S2, stirring at a stirring rate of 50 rpm, adding lead sulfate seeds with a particle size of 4 μm into the ferric sulfate leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 0.3 kg (added according to the volume of 0.3 g / L of the ferric sulfate leachate); during the lead ion crystallization and precipitation, the temperature is controlled to be 15° C., the stirring rate is 50 rpm, and the stirring time is 3.5 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0031] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ concentration.

[0032] Embodiment 5: The lead-containing acidic solution in this embodiment is a lead-acid battery leachate (sample 2), and lead removal includes the following steps: S1, take Pb 2+ 1m³ of lead-acid battery leachate with a concentration of 3000mg / L and pH=0.5, precooled to 2°C; S2, stirring at a stirring rate of 50 rpm, adding EDTA-2Na to the lead-containing acidic solution for pretreatment, the dosage of EDTA-2Na is 0.15 kg (added according to the volume of the lead-acid battery leachate 0.15 g / L), maintaining the stirring rate at 50 rpm for continuous stirring for 3 hours; S3, stirring at a stirring rate of 50 rpm, adding lead sulfate seeds with a particle size of 3 μm into the lead-acid battery leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 0.5 kg (added according to the volume of 0.5 g / L of the lead-acid battery leachate); during the lead ion crystallization and precipitation, the temperature is controlled to be 2° C., the stirring rate is 50 rpm, and the stirring time is 4 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0033] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ Concentration; After the lead-containing crystalline slag is dried at 60°C for 2h, the lead grade of the dried lead-containing crystalline slag is tested.

[0034] Embodiment 6: The lead-containing acidic solution in this embodiment is a lead-acid battery leachate (sample 2), and lead removal includes the following steps: S1, take Pb 2+ 1m³ of lead-acid battery leachate with a concentration of 3000mg / L and pH=0.5, precooled to 10℃; S2, stirring at a stirring rate of 100 rpm, adding EDTA-2Na to the lead-acid battery leachate for pretreatment, the addition amount of EDTA-2Na is 0.3 kg (added according to the volume of the lead-acid battery leachate 0.3 g / L), maintaining the stirring rate at 100 rpm for continuous stirring for 2 hours; S3, stirring at a stirring rate of 100 rpm, adding lead sulfate seeds with a particle size of 1 μm into the lead-acid battery leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 0.1 kg (added according to the volume of the lead-acid battery leachate 0.1 g / L); during the lead ion crystallization and precipitation, the temperature is controlled to be 0° C. to 15° C., the stirring rate is 50 rpm, and the stirring time is 2 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0035] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ Concentration; After the lead-containing crystalline slag is dried at 60°C for 2h, the lead grade of the dried lead-containing crystalline slag is tested.

[0036] Embodiment 7: The lead-containing acidic solution in this embodiment is a lead-acid battery leachate (sample 2), and lead removal includes the following steps: S1, take Pb 2+ 1m³ of lead-acid battery leachate with a concentration of 3000mg / L and pH=0.5, precooled to 6°C; S2, stirring at a stirring rate of 75 rpm, adding EDTA-2Na to the lead-acid battery leachate for pretreatment, the addition amount of EDTA-2Na is 0.5 kg (added according to the volume of the lead-acid battery leachate 0.5 g / L), maintaining the stirring rate at 75 rpm for continuous stirring for 3 hours; S3, stirring at a stirring rate of 75 rpm, adding lead sulfate seeds with a particle size of 5 μm into the lead-acid battery leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 0.8 kg (added according to the volume of 0.8 g / L of the lead-acid battery leachate); during the lead ion crystallization and precipitation, the temperature is controlled to be 6° C., the stirring rate is 75 rpm, and the stirring time is 3 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0037] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ Concentration; After the lead-containing crystalline slag is dried at 60°C for 2h, the lead grade of the dried lead-containing crystalline slag is tested.

[0038] Embodiment 8: The lead-containing acidic solution in this embodiment is a lead-acid battery leachate (sample 2), and lead removal includes the following steps: S1, take Pb 2+ 1m³ of lead-acid battery leachate with a concentration of 3000mg / L and pH=0.5, precooled to 15°C; S2, stirring at a stirring rate of 100 rpm, adding EDTA-2Na to the lead-acid battery leachate for pretreatment, the addition amount of EDTA-2Na is 0.8 kg (added according to the volume of the lead-acid battery leachate 0.8 g / L), maintaining the stirring rate at 100 rpm for continuous stirring for 2.5 hours; S3, stirring at a stirring rate of 100 rpm, adding lead sulfate seeds with a particle size of 1 μm to the lead-acid battery leachate to induce lead ion crystallization; the amount of lead sulfate seeds added is 1 kg (added according to the volume of 1 g / L of the lead-acid battery leachate); during the lead ion crystallization, the temperature is controlled to be 15° C., the stirring rate is 100 rpm, and the stirring time is 2 hours, until no more lead ion crystals are precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0039] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ Concentration; After the lead-containing crystalline slag is dried at 60°C for 2h, the lead grade of the dried lead-containing crystalline slag is tested.

[0040] Embodiment 9: The lead-containing acidic solution in this embodiment is a lead-acid battery leachate (sample 2), and lead removal includes the following steps: S1, take Pb 2+ 3000mg / L, 1m³ of lead-acid battery leachate with pH=0.5 was stirred at a stirring rate of 50rpm, and EDTA-2Na was added to the lead-acid battery leachate for pretreatment. The dosage of EDTA-2Na was 0.15kg (based on the volume of the lead-acid battery leachate of 0.15g / L), and the stirring rate was maintained at 50rpm for 4 hours; S2, precooling the lead-acid battery leachate after EDTA-2Na pretreatment to 2°C; S3, stirring at a stirring rate of 50 rpm, adding lead sulfate seeds with a particle size of 3 μm into the lead-acid battery leachate to induce lead ion crystallization and precipitation; the amount of lead sulfate seeds added is 0.5 kg (added according to the volume of 0.5 g / L of the lead-acid battery leachate); during the lead ion crystallization and precipitation, the temperature is controlled to be 2° C., the stirring rate is 50 rpm, and the stirring time is 4 hours, and no lead ion crystallization is precipitated; then a plate and frame filter press is used for solid-liquid separation to obtain lead-containing crystal slag and lead-free acidic wastewater.

[0041] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ Concentration; After the lead-containing crystalline slag is dried at 60°C for 2h, the lead grade in the dried lead-containing crystalline slag is detected.

[0042] 3. Comparison Comparative Example 1: The difference between this comparative example and Example 1 is that: first, the temperature of the iron sulfate leaching solution is controlled to 25°C, and then lead sulfate seeds are added to induce the crystallization of lead ions; during the crystallization of lead ions, the temperature is controlled to 25°C.

[0043] The other steps are the same as those in Example 1, and lead-containing crystalline slag and lead-free acidic wastewater are obtained.

[0044] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ concentration.

[0045] Comparative Example 2: The difference between this comparative example and Example 1 is that no lead sulfate seed crystals are added.

[0046] The other steps are the same as those in Example 1, and lead-containing crystalline slag and lead-free acidic wastewater are obtained.

[0047] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ concentration.

[0048] Comparative Example 3: The difference between this comparative example and Example 5 is that: first, the temperature of the iron sulfate leaching solution is controlled to 25°C, and then lead sulfate seeds are added to induce lead ion crystallization and precipitation; during the lead ion crystallization and precipitation process, the temperature is controlled to 25°C.

[0049] The rest is the same as in Example 5, obtaining lead-containing crystalline slag and lead-free acidic wastewater.

[0050] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+ Concentration; After the lead-containing crystalline slag is dried at 60°C for 2h, the lead grade of the dried lead-containing crystalline slag is tested.

[0051] Comparative Example 4: This comparative example is different from Example 5 in that no lead sulfate seed crystals are added.

[0052] The rest is the same as in Example 5, obtaining lead-containing crystalline slag and lead-depleted acidic wastewater.

[0053] Detection of Pb in lead removal acidic wastewater 2+ Concentration and Fe 3+Concentration; After the lead-containing crystalline slag is dried at 60°C for 2h, the lead grade of the dried lead-containing crystalline slag is tested.

[0054] Comparative Example 5: In this comparative example, the lead-containing iron sulfate leaching solution (sample 1) was treated by sulfidation precipitation method, which includes the following steps: S1, take Pb 2+ 500mg / L, Fe 3+ 80g / L iron sulfate leaching solution 1m³, add dilute sulfuric acid or sodium hydroxide to the iron sulfate leaching solution, adjust the pH to 3.5, so that Fe 3+ Preferentially hydrolyzed to Fe(OH) 3 The precipitation was stirred at room temperature at a stirring rate of 100 rpm for 60 min to promote the Fe(OH) 3 The particles aggregate and after standing, solid-liquid separation is carried out through a plate and frame filter press, and the filtrate enters the next step of treatment; S2, to remove Fe 3+ Add NaOH to the filtrate to adjust the pH to 9; 2 S) and Pb 2+ The molar ratio of 5:1 is added; sodium sulfide (Na 2 After adding S), the mixture was stirred at 35°C and 100 rpm for 30 min to promote the precipitation of PbS (reaction formula: Pb 2+ +S 2- →PbS↓); S3, according to the volume of the filtrate obtained in step S1, adding 0.3 mg / L polyacrylamide (PAM) as a flocculant to accelerate the aggregation of PbS microparticles; S4, using a plate and frame filter press to separate solid and liquid, to obtain 3 sludge and lead removal acidic wastewater.

[0055] After solidification, the sludge is treated as hazardous waste (HW31 category) and Pb in the lead removal acid wastewater is detected. 2+ Concentration and Fe 3+ concentration.

[0056] Comparative Example 6: In this comparative example, the adsorption method is used to treat the lead-containing iron sulfate leaching solution (sample 1), comprising the following steps: S1, take Pb 2+ 500mg / L, Fe 3+ 80g / L ferric sulfate leaching solution 1m³, add sodium hydroxide to the ferric sulfate leaching solution, adjust the pH to 3.5, and make Fe 3+ Preferentially hydrolyzed to Fe(OH) 3 The precipitation was stirred at room temperature at a stirring rate of 100 rpm for 60 min to promote the Fe(OH)3 The particles aggregate and after standing, solid-liquid separation is carried out through a plate and frame filter press, and the filtrate enters the next step of treatment; S2, use dilute sulfuric acid or NaOH to adjust the pH of the filtrate to 4, add adsorption resin, the adsorption resin is phosphate-based resin, according to the adsorption resin and Pb 2+ The mass ratio of 1:15 was added, and the mixture was stirred at 25°C and 150 rpm for 60 min; S3. The filtrate after adsorption was separated by centrifuge at 5000rpm to obtain lead-free acidic wastewater. Pb in the lead-free acidic wastewater was detected. 2+ Concentration and Fe 3+ concentration.

[0057] The effects of wastewater treatment in the above-mentioned Examples 1 to 9 and Comparative Examples 1 to 6 are shown in Table 1 below: Table 1 Wastewater treatment effect

[0058] From Table 1, we can see that: (1) Compared with Comparative Examples 1-2, Examples 1-4 have lower lead removal rates when the temperature is higher (Comparative Example 1) or when no seed crystal is added (Comparative Example 2). In Examples 1-4, good lead removal effects are achieved by suppressing the solubility of lead sulfate at low temperature and strengthening crystallization with seed crystals.

[0059] (2) Compared with Example 5, Example 5 uses the sulfide precipitation method to remove lead. Although a good lead removal effect is achieved, the iron loss rate is high. Additional steps (such as acid leaching and magnetic separation) are required to separate iron from other metals, which increases the processing flow and processing cost. (3) Compared with Example 6, Example 6 uses adsorption to remove lead. Although it achieves good lead removal effect, the iron loss rate is as high as 33.7%. It is also necessary to separate iron from other metals through additional steps (such as acid leaching and magnetic separation), which increases the processing flow and processing cost.

[0060] (4) Compared with Comparative Examples 3-4, Example 5-9 has a lower lead removal rate when the temperature is higher (Comparative Example 3) and when no seed crystal is added (Comparative Example 4). In Example 5-9, a good lead removal effect is achieved by suppressing the solubility of lead sulfate at low temperature and strengthening crystallization with seed crystals. In terms of lead recovery, the quality of the crystal slag obtained in Example 5-9 is also higher than that of the crystal slag in Comparative Examples 5 and 6.

[0061] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0062] In addition, it should be noted that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in a reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0063] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for removing lead from a lead-containing acidic solution, characterized in that: The steps include: S1. Adjust the temperature of the lead-containing acid solution to 0°C to 15°C; S2. Adding lead sulfate seed crystals to the lead-containing acidic solution, continuing to control the temperature at 0°C to 15°C, inducing the crystallization of lead ions through the lead sulfate seed crystals until no more lead ions are crystallized; then performing solid-liquid separation to obtain lead-containing crystalline slag and lead-free acidic wastewater.

2. The method for removing lead from a lead-containing acidic solution according to claim 1, characterized in that: In the step S1, the temperature of the lead-containing acidic solution is controlled at 3°C ​​to 12°C.

3. The lead removal method of the lead-containing acidic solution according to claim 2, characterized in that: In the step S1, the temperature of the lead-containing acidic solution is controlled at 3°C ​​to 7°C.

4. The method for removing lead from a lead-containing acidic solution according to claim 1, characterized in that: In the step S2, the lead sulfate seed crystals are micron-sized lead sulfate seed crystals; And / or, the lead sulfate seed crystals are added in an amount of 0.1 g / L to 1 g / L of the lead-containing acidic solution; And / or, the lead ion crystallization is carried out under low-speed stirring; And / or, during the lead ion crystallization process, the temperature is controlled at 3°C ​​to 12°C.

5. The method for removing lead from a lead-containing acidic solution according to claim 4, characterized in that: In step S2, the particle size of the lead sulfate seed crystal is 1 μm to 5 μm; And / or, the lead sulfate seed crystals are added in an amount of 0.3 g / L to 0.8 g / L of the lead-containing acidic solution; And / or, the lead ion crystallization is carried out by stirring at a stirring rate of 50 rpm to 100 rpm for 2 to 4 hours; And / or, during the lead ion crystallization process, the temperature is controlled at 3°C ​​to 7°C.

6. The method for removing lead from a lead-containing acidic solution according to claim 1, characterized in that: In the step S2, the solid-liquid separation is performed using a plate and frame filter press.

7. The method for removing lead from a lead-containing acidic solution according to claim 1, characterized in that: The method also includes pre-treating the lead-containing acidic solution, wherein the pre-treatment is adding EDTA-2Na to the lead-containing acidic solution; The preprocessing is before step S1; or, the preprocessing is after step S1 and before step S2.

8. The method for removing lead from a lead-containing acidic solution according to claim 7, characterized in that: The dosage of the EDTA-2Na is 0.1 g / L to 1 g / L based on the volume of the lead-containing acidic solution.

9. The method for removing lead from a lead-containing acidic solution according to claim 8, characterized in that: The dosage of the EDTA-2Na is 0.3 g / L to 0.8 g / L based on the volume of the lead-containing acidic solution.

10. The method for removing lead from a lead-containing acidic solution according to claim 7, characterized in that: During pretreatment, after EDTA-2Na is added, the stirring rate is controlled to be 50 rpm to 100 rpm and stirring is continued for 2 to 4 hours.

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