Method for recovering lead tetraoxide from waste lead plaster

Abstract

The invention discloses a method for recovering lead tetraoxide from waste lead plaster, which comprises the following steps: (1) obtaining a waste lead plaster material, and drying to obtain a lead plaster sample; (2) carrying out acid leaching pretreatment on the waste lead plaster: carrying out acid leaching on the lead plaster sample obtained in the step (1) by using dilute sulphuric acid, wherein the lead plaster sample subjected to acid leaching comprises the main components of PbSO4 and PbO2; (3) desulfurization reaction: leaching the lead plaster sample in the step (2) by using an ammonium oxalate solution to obtain a solid mixture of lead oxalate and lead dioxide; and (4) roasting: roasting the solid mixture in the step (3) to obtain lead tetraoxide. According to the method, the ammonium oxalate solution serves as a desulfurizing agent to directly desulfurize the lead plaster, the obtained solid mixture is directly roasted to obtain a lead tetroxide product, lead dioxide in the waste lead plaster is fully utilized, and the defects that in the process of recovering lead from the waste lead-acid storage battery, the usage amount of chemical reagents is too large, the technological process is long, and secondary pollution is caused are overcome; the method is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of recycling waste lead-acid batteries, and in particular to a method for recycling lead tetroxide from waste lead paste. Background Art

[0002] Lead-acid batteries are widely used in communication base stations, backup power equipment, transportation and other fields due to their stable voltage, safe operation, high cost performance and long service life. Due to the widespread use of lead-acid batteries, the generation of a large number of waste lead-acid batteries will be inevitable. If waste lead-acid batteries are not properly handled after disposal, it will seriously threaten the environment and human health. At the same time, waste lead-acid batteries are an important raw material for secondary lead production. Therefore, how to recycle lead resources with environmentally friendly processes has become an important research direction.

[0003] The main component of waste lead-acid batteries is waste lead paste, which has a complex composition and is the part that needs to be focused on in the recycling process of waste lead-acid batteries. PbSO4 has the highest content in waste lead paste. It is stable and has a high melting point. It is difficult to dissolve in water and acid. It can only be completely decomposed above 1300°C. The second is PbO2, which has strong oxidizing properties, relatively stable properties, and is insoluble in oxidizing acids and alkalis. Therefore, if PbSO4 and PbO2 are not converted into easily handled lead compounds, it will be detrimental to the recovery and utilization of lead in waste lead paste.

[0004] At present, the existing treatment technology for PbSO4 and PbO2 in waste lead paste generally adopts pyrometallurgy or hydrometallurgy. The traditional pyrometallurgy can directly reduce PbSO4 and PbO2 to metallic lead under high temperature conditions. However, the recovery process requires high temperature conditions above 1300°C, which inevitably leads to problems such as excessive smelting energy consumption, lead dust and SO2 generation, which is difficult to meet the current environmental protection requirements. The hydrometallurgical process often requires the use of acid reagents and reducing agents to convert PbO2 into low-valent lead compounds such as PbSO4, and then use leaching agents, desulfurization agents or carbonizing agents to convert PbSO4 into more easily handled lead compounds, and finally obtain lead oxide or metallic lead products by calcination, smelting or crystallization. This type of recovery process has a long process flow, consumes a large amount of acid reagents and reducing agents, easily produces acidic wastewater, and lacks economic benefits. Therefore, it is of great significance to find a method for recycling waste lead paste that can fully utilize PbO2 in waste lead paste, avoid the use of acid reagents and reducing reagents, reduce the discharge of three wastes, save energy and protect the environment, and meet the basic requirements of current sustainable development.

[0005] Lead tetroxide, a red mixture of lead oxide and lead dioxide, is widely used in lead-acid batteries, crystal glass, glazes and other fields due to its own characteristics.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The purpose of the present invention is to provide a method for recovering lead tetroxide from waste lead paste, which makes full use of lead dioxide in the waste lead paste and overcomes the shortcomings of excessive use of chemical reagents, long process flow and secondary pollution in the process of recovering lead from waste lead-acid batteries.

[0008] To achieve the above object, the present invention provides a method for recovering lead tetroxide from waste lead paste, comprising the following steps:

[0009] (1) obtaining waste lead paste material, drying it, and obtaining a lead paste sample;

[0010] (2) Acid leaching pretreatment of waste lead paste: The lead paste sample of step (1) is acid-leached with dilute sulfuric acid, and the main components of the lead paste sample after acid leaching are PbSO4 and PbO2;

[0011] (3) desulfurization reaction: leaching the lead paste sample of step (2) with an ammonium oxalate solution to obtain a solid mixture of lead oxalate and lead dioxide;

[0012] (4) Calcination: Calcinate the solid mixture of step (3) to obtain lead tetroxide.

[0013] Preferably, in the above technical solution, in step (1), the lead paste is dried at a temperature of 50-95° C. for 1-5 h, and then sieved after cooling.

[0014] Preferably, in the above technical solution, the concentration of the dilute sulfuric acid in step (2) is 0.1-1 mol / L.

[0015] Preferably, in the above technical solution, the solid-to-liquid ratio of the lead paste sample to dilute sulfuric acid in step (2) is 1-10:50 g / mL.

[0016] Preferably, in the above technical solution, the acid leaching pretreatment in step (2) is to react at 25-35°C for 0.5-3h, then filter, wash the solid matter to neutrality, and dry at 90-110°C.

[0017] Preferably, in the above technical solution, the concentration of the ammonium oxalate solution in step (3) is 0.5-1 mol / L.

[0018] Preferably, in the above technical solution, the molar ratio of the lead paste to the ammonium oxalate solution in step (3) is 0.5-1:1.

[0019] Preferably, in the above technical solution, the temperature condition for the mixed reaction of the lead paste and the ammonium oxalate solution in step (3) is 25-60° C., and the reaction time is 0.5-2.5 h.

[0020] Preferably, in the above technical solution, the solid mixture is calcined in step (4) at 400-450° C. for 1-2 h.

[0021] Compared with the prior art, the present invention has the following beneficial effects: the method for recovering lead tetroxide from waste lead paste of the present invention uses dilute sulfuric acid as a leaching agent, while converting PbO and Pb in the waste lead paste into PbSO4, the impurity metals in the waste lead paste can be removed. Ammonium oxalate is used as a desulfurizing agent to convert PbSO4 into lead oxalate to obtain a solid mixture of lead oxalate and lead dioxide. The solid mixture is directly converted into the lead tetroxide product by low-temperature roasting, which can avoid the use of acid reagents and reducing reagents when converting lead dioxide, fully utilize the lead dioxide in the waste lead paste, and reduce the generation of acid waste liquid. The desulfurization filtrate obtained at the end can obtain ammonium sulfate byproduct by evaporation and crystallization, which reduces production costs and secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a process flow chart of a method for recovering lead tetroxide from waste lead paste according to the present invention;

[0023] Figure 2 This is the XRD diagram of the waste lead paste leached with dilute sulfuric acid in Example 1 and the final product, lead tetroxide. DETAILED DESCRIPTION

[0024] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0025] Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or variations such as “include” or “comprising”, etc., will be understood to include the stated elements or components but not to exclude other elements or components.

[0026] Example 1

[0027] A method for recovering lead tetroxide from waste lead paste, the process flow chart of which is as follows: Figure 1 As shown, the method comprises four parts: pretreatment of waste lead-acid batteries, acid leaching pretreatment of waste lead paste, desulfurization leaching of acid leached lead paste and roasting of solid mixture, and specifically comprises the following steps:

[0028] (1) Pretreatment of waste lead-acid batteries: Chaowei brand waste lead-acid batteries of model 6-DZM-20 were purchased from the market. The battery shell was removed by manual disassembly, the lead paste plates were taken out, the diaphragms were removed, the lead paste plates were ground, and then placed in an oven to dry at 80°C for 3 h. After the lead paste material was cooled to room temperature, it was sieved through a 120-mesh sieve to obtain the lead paste experimental samples.

[0029] In the waste lead paste, the content of PbSO4 is 48.74wt%, the content of PbO2 is 29.82wt%, the content of PbO is 18.38wt%, the content of Pb is 2.04wt%, and the others are 1.02wt%.

[0030] (2) Acid leaching pretreatment of waste lead paste: 4 g of waste lead paste and 50 mL of 1 mol / L dilute sulfuric acid solution were placed in a 200 mL glass beaker, the waste lead paste and the dilute sulfuric acid solution were mixed, reacted at 30°C for 1.5 h, and then filtered. The solid matter was washed with deionized water until neutral, and dried at 100°C to obtain the lead paste after acid leaching pretreatment.

[0031] (3) Desulfurization reaction: The lead paste after acid leaching is mixed with ammonium oxalate solution in a molar ratio of (SO4 2- :C2O4 2- ) are uniformly mixed in a ratio of 0.5:1.0, and reacted at 25°C for 0.5h to obtain a solid-liquid mixture.

[0032] (4) Calcination: The obtained solid-liquid mixture is placed in a tube furnace and calcined at 400° C. in an air atmosphere for 1.0 h to obtain a lead tetroxide product.

[0033] The desulfurization rate of PbSO4 in this embodiment is 98.57%. Figure 2 As shown, it is the XRD diagram of the waste lead paste leached with dilute sulfuric acid and the final product lead tetraoxide in this embodiment.

[0034] Example 2

[0035] A method for recovering lead tetroxide from waste lead paste, the process flow chart of which is as follows: Figure 1 As shown, the method comprises four parts: pretreatment of waste lead-acid batteries, acid leaching pretreatment of waste lead paste, desulfurization leaching of acid leached lead paste and roasting of solid mixture, and specifically comprises the following steps:

[0036] (1) Pretreatment of waste lead-acid batteries: Tianneng brand waste lead-acid batteries of model 6-DZM-20 were purchased from the market. The battery shell was removed by manual disassembly, the lead paste plates were taken out, the diaphragms were removed, the lead paste plates were ground, and then placed in an oven to dry at 80°C for 3 h. After the lead paste material was cooled to room temperature, it was sieved through a 120-mesh sieve to obtain a lead paste experimental sample.

[0037] In the waste lead paste, the PbSO4 content is 46.18wt%, the PbO2 content is 32.46wt%, the PbO content is 16.20wt%, the Pb content is 3.11wt%, and the others are 2.05wt%.

[0038] (2) Acid leaching pretreatment of waste lead paste: 4 g of waste lead paste and 50 mL of 1 mol / L dilute sulfuric acid solution were placed in a 200 mL glass beaker, the waste lead paste and the dilute sulfuric acid solution were mixed, reacted at 30°C for 1.5 h, and then filtered. The solid matter was washed with deionized water until neutral, and dried at 100°C to obtain the lead paste after acid leaching pretreatment.

[0039] (3) Desulfurization reaction: The lead paste after acid leaching is mixed with ammonium oxalate solution in a molar ratio of (SO4 2- :C2O4 2- ) were uniformly mixed in a ratio of 0.75:1.0, and reacted at 40°C for 1.5h to obtain a solid-liquid mixture.

[0040] (4) Calcination: The obtained solid-liquid mixture is placed in a tube furnace and calcined at 450° C. for 1.0 h in an air atmosphere to obtain a lead tetroxide product.

[0041] The desulfurization rate of PbSO4 in this embodiment is 98.25%.

[0042] Example 3

[0043] A method for recovering lead tetroxide from waste lead paste, the process flow chart of which is as follows: Figure 1 As shown, the method comprises four parts: pretreatment of waste lead-acid batteries, acid leaching pretreatment of waste lead paste, desulfurization leaching of acid leached lead paste and roasting of solid mixture, and specifically comprises the following steps:

[0044] (1) Pretreatment of waste lead-acid batteries: Shanshui brand waste lead-acid batteries of model 6-DW-20 were purchased from the market. The battery shell was removed by manual disassembly, the lead paste plates were taken out, the diaphragms were removed, the lead paste plates were ground, and then placed in an oven to dry at 80°C for 3 h. After the lead paste material was cooled to room temperature, it was sieved through a 120-mesh sieve to obtain a lead paste experimental sample.

[0045] In the waste lead paste, the content of PbSO4 is 45.76wt%, the content of PbO2 is 32.49wt%, the content of PbO is 17.62wt%, the content of Pb is 1.90wt%, and the others are 2.23wt%.

[0046] (2) Acid leaching pretreatment of waste lead paste: 4 g of waste lead paste and 50 mL of 1 mol / L dilute sulfuric acid solution were placed in a 200 mL glass beaker, the waste lead paste and the dilute sulfuric acid solution were mixed, reacted at 30°C for 1.5 h, and then filtered. The solid matter was washed with deionized water until neutral, and dried at 100°C to obtain the lead paste after acid leaching pretreatment.

[0047] (3) Desulfurization reaction: The lead paste after acid leaching is mixed with ammonium oxalate solution in a molar ratio of (SO4 2- :C2O4 2- ) were uniformly mixed in a ratio of 1.0:1.0, and reacted at 60°C for 2.5h to obtain a solid-liquid mixture.

[0048] (4) Calcination: The obtained solid-liquid mixture is placed in a tube furnace and calcined at 450° C. for 2.0 h in an air atmosphere to obtain a lead tetroxide product.

[0049] The desulfurization rate of PbSO4 in this embodiment is 97.32%.

[0050] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for recovering lead tetroxide from waste lead paste, characterized in that: The following steps are involved: (1) obtaining waste lead paste material, drying it, and obtaining a lead paste sample; (2) Acid leaching pretreatment of waste lead paste: The lead paste sample of step (1) is acid-leached with dilute sulfuric acid, and the main components of the lead paste sample after acid leaching are PbSO4 and PbO2; (3) desulfurization reaction: leaching the lead paste sample of step (2) with an ammonium oxalate solution to obtain a solid mixture of lead oxalate and lead dioxide; (4) Calcination: Calcinate the solid mixture of step (3) to obtain lead tetroxide.

2. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: In step (1), the lead paste is dried at a temperature of 50-95° C. for 1-5 hours, and then sieved after cooling.

3. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: The concentration of the dilute sulfuric acid in step (2) is 0.1-1 mol / L.

4. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: In step (2), the solid-to-liquid ratio of the lead paste sample to dilute sulfuric acid is 1-10:50 g / mL.

5. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: The acid leaching pretreatment in step (2) is to react at 25-35°C for 0.5-3h, then filter, wash the solid matter to neutrality, and dry at 90-110°C.

6. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: The concentration of the ammonium oxalate solution in step (3) is 0.5-1 mol / L.

7. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: In step (3), the molar ratio of the lead paste to the ammonium oxalate solution is 0.5-1:

1.

8. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: In step (3), the temperature condition for the mixed reaction of the lead paste and the ammonium oxalate solution is 25-60° C., and the reaction time is 0.5-2.5 h.

9. The method for recovering lead tetroxide from waste lead paste according to claim 1, characterized in that: The solid mixture is calcined at 400-450° C. for 1-2 hours in step (4).

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