Method for recovering lead from sulfur-containing lead paste

Abstract

The present invention relates to the field of waste lead paste recycling and utilization, and discloses a method for recovering lead from sulfur-containing lead paste. The method comprises the following steps: (1) contacting the sulfur-containing lead paste, chiral aminocarboxyl molecules, and an organic acid salt at a pH of 7-8.2, so that non-PbSO4 components and PbSO4 components are leached simultaneously to obtain a lead-containing filtrate and a leached residue; wherein the molar ratio of the non-PbSO4 components to the PbSO4 components in the material before contact is 0.5-10:1; and (2) subjecting the lead-containing filtrate to an aging reaction with a precipitant to obtain a lead salt precipitate and a regenerated filtrate. The method provided by the present invention can achieve direct and efficient leaching of all lead components in the sulfur-containing lead paste in a one-step process, with a high lead recovery rate.

Description

Technical Field

[0001] The invention relates to the field of recycling of waste lead paste, and in particular to a method for recovering lead from sulfur-containing lead paste. Background Art

[0002] A typical scrapped lead-acid battery consists primarily of four components: spent electrolyte, grid alloy, scrap lead paste, and polymeric materials. Scrap lead paste is the most complex active material and the most challenging to process. Analysis reveals its primary components to be PbSO₄ (45-60 wt%), PbO₂ (35-40 wt%), PbO (10-15 wt%), and a small amount of metallic lead (3-5 wt%). PbSO₄ is the most challenging component to process, as it decomposes at temperatures exceeding 1000°C and produces toxic sulfur oxides and lead-containing fumes. Furthermore, scrap lead paste contains small amounts of impurities (approximately 1 wt%), such as iron, antimony, calcium, copper, and magnesium. During the recycling process, these impurities can affect the electrochemical properties of the recycled lead compound, reducing its cycling performance. Therefore, developing efficient, simple, and environmentally friendly methods for recycling sulfur-containing lead paste is crucial.

[0003] At present, there are two main methods for recycling waste lead paste: pyrometallurgy and wet recycling. The former prefers to obtain metals through high-temperature operations, while the latter emphasizes the recovery of metals from solutions using special solvents under mild conditions. Wet recycling is further divided into electroplating to recover metallic lead and direct recovery of lead oxide. Among them, in the electroplating process for recovering metallic lead, since most of its leaching agents are reagents such as fluoroboric acid, fluorosilicic acid, and perchloric acid, they not only corrode the reaction equipment but also produce toxic gases. In addition, the raw materials required by battery companies are mainly lead oxide, and the recovered lead product needs to undergo a ball milling process to obtain the lead oxide required for the preparation of lead-acid batteries. Therefore, on the whole, the wet electroplating lead process does not take into account the energy consumption of the electroplating process and the energy consumption of preparing lead oxide from refined lead, resulting in a large amount of energy loss and additional carbon dioxide emissions.

[0004] In terms of the direct lead oxide recovery process, since the lead sulfate component is difficult to dissolve in general acidic solutions, the existing wet leaching process requires the lead sulfate component to be pre-desulfurized (pre-desulfurization process) to convert it into easily leached lead oxide or lead carbonate before leaching. For example, CN104141045B reported that the waste lead paste is first pre-desulfurized and roasted to obtain crude lead oxide, which is then leached through chiral molecule circulation to obtain lead complex, which is then carbonized to obtain lead carbonate precipitation, and the lead carbonate is thermally decomposed to obtain lead oxide, thus realizing the transformation of crude lead oxide into high-purity lead oxide. The basic process is as follows: Figure 1As shown. CN107460339B reports that waste lead paste is first pre-desulfurized, and then subjected to complexation, dissociation, and solid-liquid separation to obtain lead oxide. Another idea is to uniformly convert the mixture of lead oxide and lead sulfate into lead sulfate, and then convert it into lead sulfate. For example, CN107779603A reports that waste lead paste is first converted into PbSO4 through sulfidation, and then a conjugate solution is used to achieve effective leaching of lead sulfate, converting the lead sulfate solid into a complex lead solution, and then obtaining the lead oxide product through processes such as carbonization and roasting. This solves the problem of incomplete desulfurization reaction of lead sulfate solid in the past and achieves a leaching rate of lead sulfate of more than 99.8%. However, this process will generate more lead sulfate than the original lead paste during the sulfation process and promote the production of a large amount of low-value sulfate by-products (such as sodium sulfate or ammonium sulfate), which increases the desulfurization cost of the subsequent desulfurization process. At the same time, the sulfation process consumes a large amount of sulfuric acid, which is costly and highly corrosive. In addition, some lead oxide is coated in the lead sulfate particles, which also leads to a reduction in lead recovery rate. CN106916952A reports the use of a composite leaching agent to effectively leach lead sulfate-containing waste, converting the lead sulfate solid into a complex lead solution, which is then carbonized and roasted to obtain a lead oxide product. Finally, the lead-removed mother liquor is desulfurized for recycling. However, this method is difficult to recover all the lead components in waste lead paste containing complex components such as lead sulfate and lead oxide.

[0005] In summary, the pre-desulfurization process suffers from low lead recovery, low product purity, and complex process flow. Therefore, there is an urgent need to develop a simple process for recovering lead from sulfur-containing lead paste to improve lead recovery and product purity. Summary of the Invention

[0006] The present invention aims to overcome the problems of complex process flow, low lead recovery rate, and low product purity in the prior art by providing a method for recovering lead from sulfur-containing lead paste. The method provided by the present invention can achieve direct and efficient leaching of all lead components in sulfur-containing lead paste in a single step, achieving a high lead recovery rate.

[0007] In order to achieve the above object, the present invention provides a method for recovering lead from sulfur-containing lead paste, which comprises the following steps:

[0008] (1) contacting a sulfur-containing lead paste, a chiral aminocarboxylic acid molecule, and an organic acid salt at a pH of 7-8.2, so that a non-PbSO4 component and a PbSO4 component are leached simultaneously to obtain a lead-containing filtrate and a leaching residue; wherein the molar ratio of the non-PbSO4 component to the PbSO4 component in the material before contact is 0.5-10:1;

[0009] (2) subjecting the lead-containing filtrate to an aging reaction with a precipitant to obtain a lead salt precipitate and a regenerated filtrate.

[0010] Preferably, the pH of the contact in step (1) is 7.3-7.8.

[0011] Preferably, the molar ratio of the non-PbSO4 component to the PbSO4 component in the material before contact is 3-10:1.

[0012] Preferably, the contact temperature in step (1) is 50-180°C, preferably 80-160°C.

[0013] Through the above technical solution, the beneficial effects of the present invention include:

[0014] The method provided by the present invention involves contacting a sulfur-containing lead paste containing lead sulfate with chiral aminocarboxyl molecules and an organic acid salt at a specific pH, while simultaneously regulating the molar ratio of non-PbSO4 components to PbSO4 in the material before contact. This significantly improves the leaching rate of lead sulfate and enables direct leaching of both PbSO4 and non-PbSO4 components, resolving the issues of difficult lead sulfate treatment, high desulfurization costs, and low lead recovery rates in traditional recovery processes. Furthermore, the process of the present invention is simple, easily scalable, and has promising development prospects.

[0015] The method provided by the present invention omits the pre-desulfurization step, can effectively reduce lead loss, and fully realize the effective utilization of resources; the method provided by the present invention can realize the recycling and reuse of the chiral aminocarboxylic acid molecules in the recovery process, minimize the consumption of chemical raw materials and the generation of waste liquid, and realize a closed-loop direct leaching and lead recovery process of sulfur-containing lead paste.

[0016] The method provided by the present invention preferably uses a rotating liquid film reactor as an equipment, which greatly shortens the reaction time and improves the reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a process flow chart for recovering lead oxide from sulfur-containing lead paste in the prior art;

[0018] Figure 2 This is a process flow chart for recovering lead oxide from sulfur-containing lead paste according to the present invention;

[0019] Figure 3 It is a schematic diagram of the structure of a rotating liquid film reactor;

[0020] Figure 4 This is a diagram of the working principle of the rotating liquid film reactor;

[0021] Figure 5 The SEM image (Figure a) and XRD pattern (Figure b) of the original sulfur-containing lead paste of Example 1;

[0022] Figure 6The following are the SEM image (Figure a) and XRD (Figure c) images of the lead carbonate recovered from the sulfur-containing lead paste in Example 1, as well as the SEM image (Figure b) and XRD image (Figure d) of the lead oxide product.

[0023] Description of Reference Numerals

[0024] exist Figure 3 middle,

[0025] 1. Hopper; 2. Stator; 3. Rotor; 4. Pneumatic motor;

[0026] 5. Circulation pipe; 6. Discharge pipe; 7. Machine body; A. Operating equipment;

[0027] B. Power equipment. DETAILED DESCRIPTION

[0028] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0029] One aspect of the present invention provides a method for recovering lead from sulfur-containing lead paste, the method comprising the following steps:

[0030] (1) contacting a sulfur-containing lead paste, a chiral aminocarboxylic acid molecule, and an organic acid salt at a pH of 7-8.2, so that a non-PbSO4 component and a PbSO4 component are leached simultaneously to obtain a lead-containing filtrate and a leaching residue; wherein the molar ratio of the non-PbSO4 component to the PbSO4 component in the material before contact is 0.5-10:1;

[0031] (2) subjecting the lead-containing filtrate to an aging reaction with a precipitant to obtain a lead salt precipitate and a regenerated filtrate.

[0032] Prior art CN104141045B( Figure 1) discloses a method for converting crude lead oxide into high-purity lead oxide by subjecting scrap lead paste to pre-desulfurization and calcination to obtain crude lead oxide, followed by cyclic leaching of chiral molecules to obtain a lead complex, followed by carbonization to obtain a lead carbonate precipitate, and thermal decomposition of the lead carbonate to obtain lead oxide. The inventors discovered during their research that the desulfurization mother liquor during the pre-desulfurization process carries away some lead, resulting in lead pollution and loss, reducing lead recovery rates, and complicating the process flow and increasing costs. The inventors further discovered during their research that by contacting a sulfur-containing lead paste containing lead sulfate with chiral aminocarboxyl molecules and organic acid salts, adjusting the solution pH to within the range of 7-8.2 and controlling the molar ratio of non-PbSO4 components to PbSO4 in the pre-contact material to within the range of 0.5-10, the leaching rate of lead sulfate can be greatly improved. Simultaneously, the non-PbSO4 components and PbSO4 components can be co-leached in a one-step process, solving the problems of low lead sulfate leaching rates and high pre-desulfurization costs associated with conventional scrap lead paste. The lead-containing filtrate is then subjected to an aging reaction with a precipitant, ultimately yielding a lead carbonate product with a purity of up to 99.99%. The method of the present invention eliminates the need for a pre-desulfurization step, shortening the wet lead recovery process, effectively reducing lead loss, increasing lead recovery rates, and fully realizing efficient resource utilization.

[0033] According to the present invention, preferably, the pH of the contacting step (1) is 7.3-7.8, for example, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, and any value within a range consisting of any two of these values. This preferred embodiment is more conducive to the simultaneous leaching of non-PbSO4 components and PbSO4 components, and is more conducive to improving the leaching rate of lead sulfate.

[0034] The present invention leaches at a higher temperature, breaking through the previous reaction temperature limitation, and can achieve rapid leaching of non-PbSO4 components and PbSO4 components, while improving the leaching rate. Preferably, the contact temperature in step (1) is 50-180°C, preferably 80-160°C, for example, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, and any value within the range formed by any two of these values.

[0035] According to the present invention, preferably, the molar ratio of the non-PbSO4 components to the PbSO4 components in the pre-contact material is 3-10:1, for example, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1, and any value within a range consisting of any two of these values. This preferred embodiment further facilitates the simultaneous leaching of the non-PbSO4 components and the PbSO4 components.

[0036] When the molar ratio of non-PbSO4 components to PbSO4 components in the sulfur-containing lead paste already meets the above conditions, there is no need to add additional non-PbSO4 components (preferably PbO components) or PbSO4 components; when the molar ratio of non-PbSO4 components to PbSO4 components in the sulfur-containing lead paste does not meet the above conditions, additional non-PbSO4 components (preferably PbO components) or PbSO4 components may be added to meet the above conditions.

[0037] According to the present invention, preferably, in step (1), the non-PbSO4 component includes PbO.

[0038] The PbO component in the pre-contact material of the present invention comes from the original PbO in the sulfur-containing lead paste and the optionally additionally added PbO.

[0039] Preferably, the non-PbSO4 components further include Pb and PbO2.

[0040] During the contact process of step (1) of the present invention, Pb and PbO2 react to form PbO.

[0041] The PbSO4 component in the pre-contact material of the present invention comes from the original PbSO4 in the sulfur-containing lead paste and the optionally additionally added PbSO4.

[0042] In order to further achieve simultaneous leaching of non-PbSO4 components and PbSO4 components and improve the leaching rate, preferably, the molar ratio of the chiral aminocarboxyl molecules to the organic acid salt is 1-10:1, preferably 1-6:1, for example 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, and any value in the range formed by any two of these values.

[0043] According to the present invention, preferably, the molar ratio of the amount of the chiral aminocarboxylic acid molecule in step (1) to the theoretical amount required for complexation of lead in the waste lead paste is 1-8:1, preferably 2.5-5:1, for example, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, and any value in the range formed by any two of these values.

[0044] According to the present invention, preferably, the chiral aminocarboxylic acid molecule is provided in the form of a solution, and the concentration of the chiral aminocarboxylic acid molecule solution is 20-180 g / L, preferably 80-160 g / L.

[0045] Preferably, the solvent in the chiral aminocarboxylate molecule solution is an organic solvent and / or water, preferably water.

[0046] The present invention has a wide range of selection for the type of chiral aminocarboxyl molecules, which can be various common chiral aminocarboxyl molecules. In order to optimize the complexing effect, preferably, the chiral aminocarboxyl molecule is histidine.

[0047] The organic acid salt of the present invention acts synergistically with the chiral aminocarboxylic acid molecules, which is more conducive to the simultaneous leaching of non-PbSO4 components and PbSO4 components. Preferably, the organic acid salt is a C1-C5 carboxylate, preferably sodium acetate and / or sodium propionate.

[0048] In the present invention, the main component of the leaching residue is the insoluble impurities in the sulfur-containing lead paste. Preferably, the leaching residue contains at least one of Cu, Ca, Mg, Bi, Sb, Sn and Fe.

[0049] Preferably, the leaching residue further contains unreacted residual Pb or PbO2.

[0050] Preferably, the material obtained by the contact in step (1) is subjected to solid-liquid separation to obtain a lead-containing filtrate and a leaching residue.

[0051] The present invention has no particular limitation on the solid-liquid separation, which can be carried out according to conventional technical means in the art, and the present invention will not elaborate on it here.

[0052] The present invention is not particularly limited to the sulfur-containing lead paste, and can be any of the various sulfur-containing lead pastes commonly used in the art. Preferably, the sulfur-containing lead paste is derived from waste lead-acid batteries, lead sludge generated during the production of lead-acid batteries, or lead paste sludge generated during the production of lead-acid batteries.

[0053] Preferably, the waste lead-acid batteries are crushed, screened, and dried to obtain sulfur-containing lead paste.

[0054] Further preferably, the process of treating the self-disassembly waste lead-acid batteries includes:

[0055] S1, washing the self-disassembled waste lead-acid battery until the washing liquid is neutral;

[0056] S2, crushing, screening, and then drying the washed self-disassembled waste lead-acid batteries to obtain sulfur-containing lead paste.

[0057] The present invention has no particular limitation on the crushing and screening, and can be carried out according to conventional technical means in the art to obtain sulfur-containing lead paste with a particle size of 50-200 mesh.

[0058] The present invention has no particular limitation on the specific conditions of the drying, and the drying can be carried out according to conventional methods in the art. Preferably, the drying conditions include: a temperature of 80-180° C. and a drying time of 5-12 hours.

[0059] Preferably, the acidified lead mud or the paste lead mud produced in the process of preparing lead-acid batteries is dried to obtain the sulfur-containing lead paste.

[0060] The present invention has no particular limitation on the specific conditions of the drying, and the drying can be carried out according to conventional methods in the art.

[0061] According to the present invention, preferably, the reaction conditions of step (2) include: temperature of 10-90°C, preferably 40-65°C; time of 1-120 min, preferably 1-10 min.

[0062] The present invention allows for a wide range of precipitants, which can be selected from conventional options in the art. Preferably, the precipitant is selected from at least one of carbon dioxide, ammonium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, copper carbonate, calcium carbonate, barium carbonate, ammonium bicarbonate, sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, barium bicarbonate, and urea.

[0063] Preferably, the amount of the precipitant is 0.5-2 mol relative to 1 mol of soluble lead ions in the lead-containing filtrate.

[0064] Preferably, the material obtained from the reaction in step (2) is subjected to solid-liquid separation to obtain a lead salt precipitate and a regenerated filtrate.

[0065] The present invention has no particular limitation on the solid-liquid separation, which can be carried out according to conventional technical means in the art, and the present invention will not elaborate on it here.

[0066] The complexing agent and the chiral aminocarboxyl molecule can achieve a conjugation effect, and the synergistic effect is conducive to the rapid leaching of the lead sulfate component. The method of the present invention can also add a complexing agent as needed.

[0067] In the method of the present invention, the lead salt precipitate can be recovered as a product, or the lead salt precipitate can be treated to obtain lead oxide for recovery.

[0068] The present invention does not particularly limit the method for obtaining lead oxide by the lead salt precipitation treatment, and can refer to conventional methods in the art. Preferably, the method further comprises: roasting the lead salt precipitate to obtain lead oxide.

[0069] Preferably, the calcination conditions include: a temperature of 350-700° C., preferably 400-550° C., and a time of 5-180 min, preferably 10-40 min. The calcination is generally performed in an air atmosphere, which may include a flowing atmosphere or a static atmosphere.

[0070] According to the present invention, preferably, the method further comprises: subjecting the regenerated filtrate to a desulfation treatment to obtain a sulfate precipitate and a residual filtrate. With this preferred embodiment, sulfate ions can be removed and the residual filtrate can be recycled.

[0071] The present invention has no particular limitation on the conditions for the desulfation treatment, and the treatment can be carried out according to conventional methods in the art.

[0072] The present invention allows for a wide range of desulfurizing agents to be used in the desulfation treatment, and can be conventionally selected in the art. Preferably, the desulfurizing agent used in the desulfation treatment is selected from at least one of barium hydroxide, calcium hydroxide, strontium hydroxide, barium oxide, calcium oxide, strontium oxide, barium peroxide, calcium peroxide, and strontium peroxide.

[0073] The desulfurizing agent of the present invention can be used directly or in the form of a solution.

[0074] When the desulfurizing agent is used in the form of a solution, the present invention has no particular limitation on the concentration and dosage of the desulfurizing agent, which can be appropriately selected according to specific circumstances, as long as the sulfate ions in the regeneration filtrate can be completely removed.

[0075] Preferably, the material obtained by the desulfation treatment is subjected to solid-liquid separation to obtain sulfate precipitate and residual filtrate.

[0076] The present invention has no particular limitation on the solid-liquid separation, which can be carried out according to conventional technical means in the art, and the present invention will not elaborate on it here.

[0077] According to the present invention, preferably, the remaining filtrate obtained is returned to step (1) for recycling to provide at least part of the chiral aminocarboxyl molecules. Adopting this preferred embodiment, the chiral aminocarboxyl molecules can be recycled in the recovery process, the consumption of chemical raw materials and the generation of waste liquid can be minimized, and a closed-loop sulfur-containing lead paste direct leaching and lead recovery process is achieved.

[0078] The lead recovery of the present invention can be carried out in any reaction device commonly used in the art. In order to further improve the lead recovery effect, preferably, the lead recovery is carried out in a rotating liquid film reactor.

[0079] The rotating liquid film reactor described in the present invention is a reactor that has an intensifying effect on solid-liquid reactions. It has both a narrow reaction space and a high shear rate. The rotor and stator rotate relative to each other at high speed, so that the material can be effectively dispersed, homogenized and crushed, achieving the effect of ultrafine crushing and emulsification of the material, while ensuring a high leaching rate and greatly reducing the reaction energy consumption.

[0080] According to the present invention, preferably, the contacting in step (1), the reaction in step (2) and the desulfurization treatment of the regenerated filtrate are carried out in a rotating liquid film reactor, such as Figure 3 As shown, the rotating liquid film reactor includes: operating equipment A and power equipment B;

[0081] The operating device A includes a stator 2 and a rotor 3, which are used for the contact in step (1), the reaction in step (2), and the desulfurization treatment of the regenerated filtrate;

[0082] The power device B is used to provide power for the reactor.

[0083] According to the present invention, preferably, the operating device A further comprises a discharge pipe 6 for discharging the lead salt precipitate.

[0084] According to the present invention, preferably, a circulation pipe 5 is provided on the discharge pipe 6 for recycling the remaining filtrate. In this preferred embodiment, the remaining filtrate provides at least a portion of the chiral aminocarboxyl molecules, enabling the recycling of the chiral aminocarboxyl molecules in the recovery process, minimizing the consumption of chemical raw materials and the generation of waste liquid, and realizing a closed-loop process for direct leaching and recovery of lead from sulfur-containing lead paste.

[0085] According to the present invention, preferably, the operating device A is fixedly installed above the fuselage 7 .

[0086] According to the present invention, preferably, the power device B comprises a pneumatic motor 4 for providing power to the reactor.

[0087] According to the present invention, preferably, the rotating liquid film reactor further comprises a hopper 1 , which is fixedly installed above the operating device A along the logistics direction for feeding.

[0088] According to the present invention, preferably, the pipe opening of the circulation pipe 5 is arranged above the hopper 1 .

[0089] The contacting in step (1), the reaction in step (2) and the desulfurization treatment of the regenerated filtrate are carried out in a rotating liquid film reactor, which can also greatly shorten the time of each step.

[0090] Preferably, the contact time in step (1) is 10s-5min.

[0091] Preferably, the rotating liquid film reactor is preheated before use.

[0092] The present invention has no particular limitation on the method of preheating treatment, and it can be carried out using commonly used technical means in the art.

[0093] It should be noted that the rotating liquid film reactor of the present invention generates heat during operation, so there is no need to continue heating the rotating liquid film reactor during the lead recovery process to maintain the required temperature of the system.

[0094] According to a preferred embodiment of the present invention, Figure 3 and Figure 4 As shown, the rotary liquid film reactor is preheated, and then the sulfur-containing lead paste, chiral aminocarboxylic acid molecules, and organic acid salts are respectively introduced from the hopper 1 of the rotary liquid film reactor into the operating device A fixedly mounted above the body 7. The rotor 3 and stator 2 in the operating device A rotate at high speed relative to each other, ensuring full contact between the materials and accelerating the contact process, thereby obtaining a lead-containing filtrate and a leaching residue, which is discharged through a discharge pipe 6. A precipitant is introduced from the hopper 1 of the rotary liquid film reactor into the operating device A to react with the lead-containing filtrate, thereby obtaining a lead salt precipitate and a regeneration filtrate, which is discharged through a discharge pipe 6. A precipitant is introduced from the hopper 1 of the rotary liquid film reactor into the operating device A to react with the regeneration filtrate, thereby obtaining a sulfate precipitate and a residual filtrate, which is then recycled through a circulation pipe 5 from the hopper 1 of the rotary liquid film reactor into the operating device A, and the sulfate precipitate is discharged through a discharge pipe 6. Throughout the entire process, the pneumatic motor 4 of the power device B provides power for the rotary liquid film reactor.

[0095] The present invention will be described in detail below through examples.

[0096] In the following examples, the PbO leaching rate and PbSO4 leaching rate parameters were measured by chemical titration analysis (EDTA-2Na titration).

[0097] Test Example 1

[0098] Used to illustrate the effect of the ratio of lead oxide and lead sulfate on lead leaching

[0099] (1) Weigh a certain amount of lead oxide and lead sulfate in a 250 mL three-necked flask at a molar ratio of 1:1. Control the reaction temperature to 100°C, then add 100 g / L histidine solution and stir for 30 min at a speed of 600 rpm.

[0100] (2) After the reaction is completed, filter and collect the filtrate for titration analysis. The reaction results are shown in Table 1.

[0101] Test Example 2-6

[0102] The method of Test Example 1 was followed, except that the PbO / PbSO4 molar ratio was changed. The reaction results are shown in Table 1.

[0103] Table 1

[0104]

[0105] Note: Total lead leaching rate

[0106] Where m (g) is the weight of lead oxide and lead sulfate; ω1 (%) is the total lead content; C (molL -1 ) is the concentration of disodium ethylenediaminetetraacetic acid used for titration in the leachate; V(L) is the volume of disodium ethylenediaminetetraacetic acid used for titration in the leachate.

[0107] It can be seen from the results in Table 1 that, compared with Test Example 6, Test Examples 1-5 achieve the combined leaching of lead sulfate and lead oxide components by adjusting the ratio of lead oxide to lead sulfate, thereby achieving a synergistic promotion effect in the leaching process.

[0108] Example 1

[0109] Process flow such as Figure 2 shown.

[0110] Take 100g of scrap lead paste from automotive lead-acid batteries as an experimental sample, which contains 28.7wt% (mass fraction) PbO (0.129mol), 14.45wt% PbSO4 (0.048mol), 26.8wt% Pb (0.129mol), 14.45wt% PbO2 (0.105mol), and the remainder is water.

[0111] (1) The waste sulfur-containing lead paste, 2.5 L of histidine aqueous solution, and 0.32 mol of sodium acetate were placed in a preheated rotating liquid film reactor. The reactor was started and reacted at 100°C for 5 min. The PbO leaching rate and PbSO4 leaching rate, as well as the specific reaction conditions of step (1), are shown in Table 3.

[0112] (2) After the reaction is completed, solid-liquid separation is performed to obtain a lead-containing filtrate and a leaching residue. An appropriate amount of CO2 (1 mol of carbon dioxide relative to 1 mol of soluble lead ions in the lead-containing filtrate) is introduced into the lead-containing filtrate at 60°C. After aging for 2 minutes, solid-liquid separation is performed to obtain a lead salt precipitate (PbCO3) and a regenerated filtrate. The purity of the obtained lead carbonate product is 99.99% as determined by ICP method.

[0113] (3) The regenerated filtrate is reacted with calcium hydroxide at 80° C. for 3 min, and then allowed to stand at 80° C. for 5 min, followed by solid-liquid separation to obtain a residual filtrate and sulfate precipitate (calcium sulfate). The residual filtrate is returned to step (1) for recycling.

[0114] (4) The lead salt precipitate (PbCO3) obtained in step (2) was calcined at 400°C for 40 min to obtain the PbO product, with a Pb recovery rate of 99.08%.

[0115] The SEM image of the original sulfur-containing lead paste is given as an example ( Figure 5 a) and XRD patterns ( Figure 5 b), as can be seen from Figure (5a), the morphology of the sulfur-containing lead paste is irregular, without obvious features, and the particle size distribution is uneven; as can be seen from Figure (5b), the sulfur-containing lead paste is mainly composed of PbO2, Pb, PbO and PbSO4.

[0116] The SEM image of the lead carbonate recovered is exemplified ( Figure 6 a) and XRD( Figure 6 c) and SEM images of lead oxide products ( Figure 6 b) and XRD patterns ( Figure 6 d), from Figure 6 From a, we can see that the morphology of lead carbonate presents a regular long cone; Figure 6 From c, we can see that the diffraction peak intensity of lead carbonate is high, indicating that its crystallinity is good. Figure 6 In b, we can see that the lead oxide morphology retains some of the lead carbonate structure, which is stacked. Figure 6 d proves that the product obtained after lead carbonate is calcined is lead oxide.

[0117] The content of impurities in the obtained lead salt precipitate is exemplified as shown in Table 2. This further proves that the lead carbonate of the present invention has high purity.

[0118] Table 2

[0119]

[0120] Example 2

[0121] Process flow such as Figure 2 shown.

[0122] (1) One kilogram of the same waste sulfur-containing lead paste as in Example 1 (containing 1.286 mol of PbO, 0.487 mol of PbSO₄, 1.293 mol of Pb, and 1.049 mol of PbO₂) was placed in a preheated rotating liquid film reactor along with 25 L of a histidine aqueous solution and 4.84 mol of sodium acetate. The reaction was started and allowed to react at 120°C for 5 minutes. The PbO leaching rate and PbSO₄ leaching rate, as well as the specific reaction conditions for step (1), are shown in Table 3.

[0123] (2) After the reaction is completed, solid-liquid separation is performed to obtain a lead-containing filtrate and a leaching residue. CO2 (1 mol of carbon dioxide is used relative to 1 mol of soluble lead ions in the lead-containing filtrate) is introduced into the lead-containing filtrate at 60°C. After aging for 2 minutes, solid-liquid separation is performed to obtain a lead salt precipitate (PbCO3) and a regenerated filtrate. The purity of the obtained lead carbonate product is 99.99% as determined by ICP method.

[0124] (3) The regenerated filtrate is reacted with a 0.05 mol / L barium hydroxide solution at 80° C. for 3 min, and then allowed to stand at 80° C. for 5 min, followed by solid-liquid separation to obtain a residual filtrate and a sulfate precipitate (barium sulfate). The residual filtrate is returned to step (1) for recycling.

[0125] (4) The lead salt precipitate (PbCO3) obtained in step (2) was calcined at 400°C for 40 minutes to obtain the PbO product. The recovery rate of Pb was 99.21%.

[0126] Example 3

[0127] Process flow such as Figure 2 shown.

[0128] One kilogram of waste sulfur-containing lead paste obtained from used Chaowei batteries was taken as an experimental sample. After EDTA titration analysis, it contained 14.34wt% PbO (0.6425mol), 15.61wt% Pb (0.7534mol), 31.1wt% PbSO4 (1.0255mol), 33.67wt% PbO2 (1.4076mol), and the remainder was water.

[0129] (1) The waste sulfur-containing lead paste, 25 L of histidine aqueous solution, and 7.53 mol of sodium propionate were placed in a preheated rotating liquid film reactor, and 90 g of PbO (0.4032 mol) was added. The reaction was started and allowed to react at 80°C for 5 min. The PbO leaching rate and PbSO4 leaching rate, as well as the specific reaction conditions for step (1), are shown in Table 3.

[0130] (2) After the reaction is completed, solid-liquid separation is performed to obtain a lead-containing filtrate and a leached residue. CO2 (1 mol of carbon dioxide relative to 1 mol of soluble lead ions in the lead-containing filtrate) is introduced into the lead-containing filtrate at 60°C. After aging for 2 minutes, solid-liquid separation is performed to obtain a lead salt precipitate (PbCO3) and a regenerated filtrate. The purity of the obtained lead carbonate product is 99.99% as determined by ICP method. The specific impurity types and contents in the lead carbonate product are shown in Table 2.

[0131] (3) reacting the regenerated filtrate with a 0.05 mol / L strontium hydroxide solution at 80° C. for 3 min, then allowing the mixture to stand at 80° C. for 5 min and subjecting it to solid-liquid separation to obtain a residual filtrate and a sulfate precipitate (strontium sulfate). The residual filtrate is returned to step (1) for recycling.

[0132] (4) The lead salt precipitate (PbCO3) obtained in step (2) was calcined at 400°C for 40 minutes to obtain the PbO product. The recovery rate of Pb was 98.28%.

[0133] Example 4

[0134] The method of Example 1 was followed, except that the contact temperature in step (1) was 60° C. The leaching rate of PbO was 91.14%, and the leaching rate of lead sulfate was 68.78%.

[0135] The purity of the obtained lead carbonate was 99.97%, and the recovery rate of Pb was 62.06%.

[0136] Comparative Example 1

[0137] The method of Example 1 was followed, except that the pH in step (1) was set to 6.2. The leaching rates of PbO and lead sulfate were 98.5% and 40.1%, respectively.

[0138] The purity of the obtained lead carbonate was 99.97%, and the recovery rate of Pb was 39.97%.

[0139] Comparative Example 2

[0140] The method of Example 1 was followed, except that sodium acetate was not added. The leaching rate of PbO was 95.4%, and the leaching rate of lead sulfate was 48.5%.

[0141] The purity of the obtained lead carbonate was 99.95%, and the recovery rate of Pb was 45.8%.

[0142] Table 3

[0143]

[0144] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for recovering lead from sulfur-containing lead paste, the method comprising the following steps: (1) contacting a sulfur-containing lead paste, a chiral aminocarboxylic acid molecule, and an organic acid salt at a pH of 7.3-7.8, so that a non-PbSO4 component and a PbSO4 component are leached simultaneously to obtain a lead-containing filtrate and a leaching residue; wherein the molar ratio of the non-PbSO4 component to the PbSO4 component in the material before contact is 3-10:1; (2) subjecting the lead-containing filtrate to an aging reaction with a precipitant to obtain a lead salt precipitate and a regenerated filtrate; Wherein, the organic acid salt is a C1-C5 carboxylate.

2. The method according to claim 1, wherein The contact temperature in step (1) is 50-180°C.

3. The method according to claim 2, wherein: The contact temperature in step (1) is 80-160°C.

4. The method according to claim 1, wherein The molar ratio of the chiral aminocarboxylic acid molecule to the organic acid salt is 1-10:

1.

5. The method according to claim 4, wherein The molar ratio of the chiral aminocarboxylic acid molecule to the organic acid salt is 1-6:

1.

6. The method according to claim 1, wherein The molar ratio of the amount of chiral aminocarboxylic acid molecules used in step (1) to the theoretical amount required for complexing lead in the waste lead paste is 1-8:

1.

7. The method according to claim 6, wherein: The molar ratio of the amount of chiral aminocarboxylic acid molecules used in step (1) to the theoretical amount required for complexing lead in the waste lead paste is 2.5-5:

1.

8. The method according to claim 1, wherein The chiral aminocarboxylic acid molecule is provided in the form of a solution, and the concentration of the chiral aminocarboxylic acid molecule solution is 20-180 g / L.

9. The method according to claim 8, wherein The chiral aminocarboxyl molecule is provided in the form of a solution, and the concentration of the chiral aminocarboxyl molecule solution is 80-160 g / L.

10. The method according to claim 1, wherein The chiral aminocarboxyl molecule is histidine.

11. The method according to claim 1, wherein The organic acid salt is sodium acetate and / or sodium propionate.

12. The method according to claim 1, wherein In step (1), the non-PbSO4 component includes PbO.

13. The method according to any one of claims 1 to 12, wherein: The reaction conditions of step (2) include: temperature of 10-90°C and time of 1-120 min.

14. The method according to claim 13, wherein: The reaction conditions of step (2) include: temperature of 40-65° C. and time of 1-10 min.

15. The method according to any one of claims 1 to 12, wherein: The precipitant is selected from at least one of carbon dioxide, ammonium carbonate, sodium carbonate, potassium carbonate, magnesium carbonate, copper carbonate, calcium carbonate, barium carbonate, ammonium bicarbonate, sodium bicarbonate, potassium bicarbonate, magnesium bicarbonate, calcium bicarbonate, barium bicarbonate and urea.

16. The method according to any one of claims 1 to 12, wherein: The method further comprises: roasting the lead salt precipitate to obtain lead oxide.

17. The method according to claim 16, wherein The calcination conditions include: temperature of 350-700° C. and time of 5-180 min.

18. The method according to claim 17, wherein The calcination conditions include: a temperature of 400-550° C. and a time of 10-40 minutes.

19. The method according to any one of claims 1 to 12, wherein: The method further comprises: performing a desulfate treatment on the regenerated filtrate to obtain a sulfate precipitate and a residual filtrate.

20. The method according to claim 19, wherein The desulfurizing agent used in the desulfurization treatment is selected from at least one of barium hydroxide, calcium hydroxide, strontium hydroxide, barium oxide, calcium oxide, strontium oxide, barium peroxide, calcium peroxide and strontium peroxide.

21. The method according to claim 19, wherein The remaining filtrate is returned to step (1) for recycling to provide at least part of the chiral aminocarboxyl molecules.

22. The method according to claim 19, wherein The contacting in step (1), the reaction in step (2), and the desulfurization treatment of the regenerated filtrate are carried out in a rotating liquid film reactor, and the rotating liquid film reactor comprises: an operating device (A) and a power device (B); The operating device (A) comprises a stator (2) and a rotor (3), which are used for carrying out the contacting in step (1), the reaction in step (2), and the desulfurization treatment of the regenerated filtrate; The power device (B) is used to provide power for the reactor.

23. The method according to claim 22, wherein The operating device (A) further comprises a discharge pipe (6) for discharging the lead salt precipitate; The discharge pipe (6) is provided with a circulation pipe (5) for recycling the remaining filtrate.

24. The method according to claim 22, wherein The operating device (A) is fixedly installed above the fuselage (7).

25. The method according to claim 22, wherein The power device (B) includes a pneumatic motor (4) for providing power to the reactor.

26. The method according to claim 23, wherein The rotating liquid film reactor further comprises a hopper (1), which is fixedly installed above the operating device (A) along the logistics direction and is used for feeding; The pipe opening of the circulation pipe (5) is arranged above the hopper (1).

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