Neutralization device for waste acid water produced in lead-acid battery recovery process

Abstract

A neutralization device for waste acid water produced in the lead-acid battery recovery process comprises a reaction tank used for neutralization reaction, the upper end of the reaction tank is provided with an acid adding port, a chemical adding port used for adding chemicals and a feeding port used for feeding lead paste, and the lower end of the reaction tank is provided with a discharging port; the acid adding port is communicated with a waste acid storage tank through a waste acid conveying pipeline, and the feeding port is communicated with a lead paste feeding device; the feed opening is communicated with a slurry filter press through a slurry conveying pump and a slurry conveying pipeline, and is used for inputting slurry after neutralization reaction into the slurry filter press for filter pressing, and solid filter residues after filter pressing are discharged through a solid discharge hopper at the bottom of the slurry filter press; and filter liquor after filter pressing is discharged into a filter liquor storage tank through a liquid discharging opening in one side of the slurry filter press and a filter liquor conveying pipeline. The lead plaster and waste acid water can be comprehensively treated, the production rhythm is improved, the quality of by-products is guaranteed, and the service life of the filter press can be prolonged.

Description

Technical Field

[0001] This utility model discloses a neutralization device for waste acid water produced in the lead-acid battery recycling process, belonging to the field of lead-acid battery recycling technology. Background Technology

[0002] Lead-acid battery recycling processes are categorized into pre-desulfurization processes and tail gas desulfurization processes based on lead paste treatment methods. These processes primarily target lead paste desulfurization and waste acid water neutralization during the lead-acid battery recycling process. Pre-desulfurization processes mainly employ sodium-based and ammonia-based desulfurization methods.

[0003] During battery recycling and processing, iron impurities in waste acid water can reach approximately 1000 ppm due to the dissolution of iron parts and corrosion of equipment. Initially, this iron exists in a divalent form, but upon contact with air or oxidizing media, it gradually changes to a coexisting divalent and trivalent form. Conventional waste acid water neutralization processes primarily involve adding a neutralizing agent separately to a reaction tank to precipitate impurities in the waste acid water, followed by filtration using a filter press to remove the precipitate. During this separate neutralization process, the iron neutralization reaction forms Fe(OH)₂ and Fe(OH)₃. Because Fe(OH)₂ precipitation requires a high pH value, the filter press cannot completely precipitate and filter it, leading to the precipitation of Fe… 2+ If the iron impurities in the neutralization filtrate pass through the filter cloth, it will ultimately result in high iron levels in the desulfurization byproducts, causing quality problems such as yellowing appearance or failure to meet the main content standards. At the same time, due to the small particle size of Fe(OH)3 colloids, filter cloth pores may become clogged during the waste acid neutralization filtrate filtration stage, thereby affecting filtration efficiency and filter cloth lifespan. Summary of the Invention

[0004] The purpose of this invention is to provide a neutralization device for waste acid water produced in the lead-acid battery recycling process, so as to solve the problem of Fe mentioned in the background art. 2+ The filter cloth cannot intercept impurities, leading to the introduction of impurities into the neutralized filtrate, resulting in substandard by-product quality and Fe. 3+ The problem of difficulty in filtration of sediment alone.

[0005] To achieve the above objectives, this utility model provides the following technical solution:

[0006] A neutralization device for waste acid water generated during lead-acid battery recycling includes a reaction tank for neutralization reaction. The upper end of the reaction tank is provided with an acid inlet, a reagent inlet, and a lead paste feeding inlet, and the lower end of the reaction tank is provided with a discharge port. The acid inlet is connected to a waste acid storage tank via a waste acid conveying pipeline, and the discharge port is connected to a lead paste feeding device. The discharge port is connected to a slurry filter press via a slurry conveying pump and a slurry conveying pipeline, for feeding the slurry after the neutralization reaction into the slurry filter press for filtration. The solid filter residue after filtration is discharged through a solid discharge hopper at the bottom of the slurry filter press, and the filtrate after filtration is discharged into a filtrate storage tank through a liquid discharge port on one side of the slurry filter press and a filtrate conveying pipeline.

[0007] The lead paste feeding device includes a lead paste filter press and a screw conveyor. The solid discharge port at the lower end of the lead paste filter press is sealed and connected to the upper part of the feed port of the screw conveyor. The screw discharge port at the other end of the screw conveyor is sealed and connected to the feeding port on the reaction tank. The liquid discharge port on one side of the lead paste filter press is discharged through the liquid discharge pipe.

[0008] The waste acid transport pipe is inserted from the acid filling port at the top of the reaction tank to a depth of about 10 cm.

[0009] The reaction vessel is equipped with a stirring device.

[0010] The reaction vessel is equipped with a weighing device at the bottom.

[0011] The lower end of the solid feed hopper is sealed and connected to the upper left feed port of the second screw conveyor. The lower right end of the second screw conveyor has a discharge port, which is connected to the top feed port of the smelting silo. This is used to transport the solid filter residue after pressure filtration to the smelting silo via the second screw conveyor.

[0012] The neutralization device of this invention can effectively solve the problems of slow equipment filtration efficiency and short service life of filter cloth caused by the difficulty of filtering iron precipitate residue when neutralizing waste acid water alone. It can also avoid the problem of ferrous iron failing to precipitate and being introduced into by-products when waste acid water is neutralized alone, thus preventing abnormal quality of by-products.

[0013] This utility model provides a neutralization device for waste acid water produced in the lead-acid battery recycling process. It solves the problems of substandard by-product quality caused by the introduction of divalent iron impurities into the neutralization filtrate in the waste acid water and the difficulty of separate filtration of trivalent iron precipitation. It can comprehensively treat lead paste and waste acid water, which not only improves the production speed, but also ensures the quality of by-products and extends the service life of the filter press. Attached Figure Description

[0014] The technical solutions in the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0015] Figure 1This is a schematic diagram of the structure of this utility model;

[0016] In the diagram: 1. Lead paste filter press; 1-1. Solid discharge port; 1-2. Liquid discharge pipe; 2. Screw conveyor one; 2-1. Screw discharge port; 3. Reaction tank; 3-1. Reaction tank stirring device; 3-2. Reaction tank weighing device; 3-3. Chemical dosing port; 4. Waste acid water conveying pipe; 5. Slurry conveying pipe; 6. Slurry conveying pump; 7. Slurry filter press; 7-1. Solid discharge hopper; 8. Screw conveyor two; 8-1. Screw discharge port for conveying filter residue after reaction; 9. Filtrate conveying pipe; 10. Filtrate storage tank. Detailed Implementation

[0017] like Figure 1 The neutralization device of this utility model mainly comprises a lead paste filter press 1, a screw conveyor 2, a reaction tank 3, a waste acid conveying pipeline 4, a slurry conveying pipeline 5, a slurry conveying pump 6, a slurry filter press 7, a second screw conveyor 8, a filtrate conveying pipeline 9, and a filtrate tank 10. The lead paste filter press 1 and the screw conveyor 2 constitute a lead paste feeding device. The lead paste filter press 1 has a solid discharge port 1-1 at its lower end, which is sealed and welded to the feed port at the upper left end of the screw conveyor 2. The screw conveyor 2 has a screw discharge port 2-1 at the lower right end, and the liquid discharge port on one side of the lead paste filter press 1 discharges through the liquid discharge pipeline 1-2. The upper end of the reaction vessel 3 has an acid inlet, a chemical inlet 3-3 for adding reagents, and a feed inlet for adding lead paste. The reaction vessel 3 has a stirring device 3-1. One end of the stirring rod of the stirring device 3-1 extends into the reaction vessel 3, and its end has stirring blades. The other end of the stirring rod is connected to a stirring motor fixed at the upper end of the reaction vessel 3. The lower end of the reaction vessel 3 has a feed outlet. The acid inlet is connected to the waste acid storage tank through the waste acid conveying pipe 4. The waste acid conveying pipe 4 is inserted from the acid inlet at the top of the reaction vessel 3 to a depth of about 10cm. The waste acid storage tank stores waste acid water generated during battery recycling. The waste acid conveying pipeline 4 has a waste acid water conveying pump. The feeding port and the screw discharge port 2-1 are sealed and welded together. The discharge port is connected to the slurry filter press 7 via the slurry conveying pump 6 and the slurry conveying pipeline 5. It is used to input the slurry after the neutralization reaction into the slurry filter press 7 for filtration. The lower end of the slurry filter press 7 has a solid feeding hopper 7-1 for discharging solid materials. The lower end of the solid feeding hopper 7-1 is sealed and connected to the upper left feed port of the screw conveyor 8. The lower right end of the screw conveyor 8 has a discharge port, which is connected to the top feed port of the smelting silo. It is used to transport the solid filter residue after filtration to the smelting silo via the screw conveyor 8. On the other side of the slurry filter press 7, there is a liquid discharge port for discharging liquid materials. The liquid discharge port is connected to the filtrate storage tank 10 via the filtrate conveying pipe 9, and is used to discharge the filtered filtrate into the filtrate storage tank 10 through the liquid discharge port and the filtrate conveying pipe 9. The bottom of the reaction tank 3 is equipped with a weighing device 3-2, which is a conventional weighing device.

[0018] In operation, waste acid water generated from 10 tons of battery recycling (mainly composed of dilute sulfuric acid, a small amount of ferrous sulfate / ferric sulfate and other impurities, sulfuric acid concentration 5-25%, iron content 1000ppm) is transported into reaction tank 3 through waste acid water conveying pipe 4. The amount of waste acid water added is controlled by the weighing device 3-2 at the bottom of reaction tank 3, and the stirring device 3-1 is turned on. Next, lead paste generated from 5 tons of battery recycling (mainly composed of lead sulfate 40-60%, lead dioxide 10-30%, lead oxide 5-20% and other impurities) is filtered through lead paste filter press 1. The filter residue is transported into reaction tank 3 through screw conveyor 2. Then, 500g of defoamer (organosilicon type defoamer) is added into reaction tank 3 through the dosing port 3-3 at the top of reaction tank 3. Then, 3.86 tons of neutralizing agent (ammonium bicarbonate in this example, the amount of neutralizing agent added is twice the total sulfur molar amount of waste acid water and lead paste) is added through the dosing port 3-3 at the top of reaction tank 3. Add the reagent 3-3 slowly into the reaction tank; after the neutralizing agent is added, continue stirring and react for 1 hour to confirm that there are no obvious bubbles on the surface of the reaction liquid and that the pH of the reaction slurry is ≥7. If the reaction endpoint is reached, the reaction tank 3 is ready to discharge the material. If the reaction endpoint is not reached, continue the reaction or add neutralizing agent to continue the reaction until the pH of the reaction slurry is ≥7. After the reaction endpoint is reached, the slurry in the reaction tank 3 is transported to the slurry filter press 7 for filtration through the slurry conveying pump 6 and the slurry conveying pipeline 5. The filter residue after the reaction is desulfurized lead paste (mainly lead carbonate, containing a small amount of lead sulfate and a small amount of iron hydroxide). The desulfurized filter residue is discharged from the solid discharge hopper 7-1 to the screw conveyor 8, and transported into the smelting raw material warehouse through the screw conveyor 8. The filtrate after the reaction is a clean sulfate solution, which can be processed as an evaporation crystallization raw material to produce qualified by-products. The filtrate after filtration is discharged into the filtrate storage tank 10 through the liquid discharge port on one side of the slurry filter press 7 and the filtrate conveying pipeline 9. This device treats undesulfurized lead paste and waste acid water together. It utilizes the strong oxidizing properties of lead dioxide in the undesulfurized lead paste under acidic conditions to oxidize all ferrous ions to ferric ions. This oxidizes ferrous ions to ferric ions, which then form ferric hydroxide, a more easily precipitated substance, during neutralization. This avoids the ferrous ions from failing to precipitate during neutralization and being directly filtered through the pores. At the same time, the ferric hydroxide produced during neutralization agglomerates with the lead paste, forming large precipitate particles. Since the lead paste particles themselves are relatively large, they leave suitable pores when combined with the filter pores during the pressure filtration process, ensuring filtration effect and efficiency, and guaranteeing the service life of the filter cloth.

[0019] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A neutralization apparatus for spent acid water produced from a lead acid battery recycling process, characterized by: The application relates to a lead paste neutralization reaction device, which comprises a reaction tank (3) for carrying out a neutralization reaction, an acid adding port, a reagent adding port (3-3) for adding reagents and a lead paste feeding port arranged at the upper end of the reaction tank (3), and a discharge port arranged at the lower end of the reaction tank (3); the acid adding port is communicated with a waste acid storage tank through a waste acid conveying pipeline (4), and the lead paste feeding port is communicated with a lead paste feeding device; the discharge port is communicated with a slurry pressure filter (7) through a slurry conveying pump (6) and a slurry conveying pipeline (5), and is used for inputting slurry after the neutralization reaction into the slurry pressure filter (7) to carry out pressure filtration; and the solid filter residue after the pressure filtration is discharged through a solid discharge hopper (7-1) at the bottom of the slurry pressure filter (7), and the filtrate after the pressure filtration is discharged into a filtrate storage tank (10) through a liquid discharge port at one side of the slurry pressure filter (7) and a filtrate conveying pipeline (9).

2. A neutralization device for spent acid water produced in a lead acid battery recycling process according to claim 1, characterized in that: The lead paste feeding device comprises a lead paste pressure filter (1) and a screw conveyor (2); a solid discharge port (1-1) at the lower end of the lead paste pressure filter (1) is connected with the upper part of an inlet of the screw conveyor (2) in a sealing mode, a screw discharge port (2-1) below the other end of the screw conveyor (2) is connected with the lead paste feeding port of the reaction tank (3) in a sealing mode, and a liquid discharge port at one side of the lead paste pressure filter (1) is connected with an outlet pipeline (1-2) in a sealing mode.

3. A neutralization device for spent acid water produced in a lead acid battery recycling process according to claim 1, characterized in that: The waste acid conveying pipeline (4) is inserted into the acid adding port at the top of the reaction tank (3) by 10 cm.

4. A device for neutralizing spent acid water produced in a lead acid battery recycling process according to claim 1, characterized in that: The reaction tank (3) is provided with a stirring device (3-1).

5. A neutralization apparatus for spent acid water produced in a lead acid battery recycling process according to claim 1, 3 or 4, characterized in that: The reaction tank (3) is provided with a weighing device (3-2) at the bottom.

6. A neutralization device for spent acid water produced in a lead acid battery recycling process according to claim 1, characterized in that: The left end of a screw conveyor (8) is connected with the upper part of the inlet of the solid discharge hopper (7-1) in a sealing mode, the right end of the screw conveyor (8) is provided with a discharge port at the lower part, the discharge port is communicated with the top inlet of a smelting material bin, and the solid filter residue after the pressure filtration is conveyed into the smelting material bin through the screw conveyor (8).

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