Recycling method of waste lead-acid storage battery PE partition plate

Abstract

The invention discloses a recycling method of a PE partition plate of a waste lead-acid storage battery, and belongs to the field of recycling of solid waste resources. The method comprises the following steps: sorting and deleading the waste lead-acid storage battery separator impurities, and then drying the waste lead-acid storage battery separator impurities; then adding the waste lead-acid storage battery separator into an open mill for open milling at a temperature close to the melting point of UHMWPE, and then gradually adding linear low-density polyethylene for continuous open milling, so that the waste lead-acid storage battery separator and the linear low-density polyethylene are uniformly mixed to obtain the modified separator with relatively good fluidity. Then adding the modified partition plate into a solid-phase mechanochemical grinding machine for repeated grinding to obtain modified partition plate scraps with small sizes, and finally, blending and extruding the modified partition plate scraps and polypropylene through a double-screw extruder to obtain the modified polypropylene. On one hand, the fluidity of the separator is improved by using linear low-density polyethylene, and on the other hand, the interface bonding force with polypropylene is improved through solid-phase mechanochemical grinding.

Description

Technical Field

[0001] The invention belongs to the field of recycling of solid waste resources, and in particular relates to a method for recycling PE separators of waste lead-acid batteries. Background Art

[0002] In recent years, in order to improve the energy structure, as the country advocates new energy, lead-acid batteries, as an important equipment for electric energy storage, have received more and more attention. The demand for lead-acid batteries in my country has increased year by year, and the amount of scrapped lead-acid batteries has also increased year by year. At present, the relevant research on the recycling system of waste lead-acid batteries at home and abroad has been relatively mature. There are relatively mature recycling systems for materials such as lead paste, grids, waste sulfuric acid, and plastic shells, which can achieve a high recycling rate, but there are few explorations on the recycling of lead-acid battery separators. Separators account for 1-2% of the mass of lead-acid batteries. More than 100,000 tons of scrapped separators are not properly handled every year, so relevant theoretical guidance is urgently needed. The main traditional ways to deal with lead-acid battery separators are incineration, landfill, and use as low-value inorganic fillers, which not only bring serious burdens to the environment, but also cause a large waste of resources. Therefore, it is very necessary to develop high-value and high-quality recycling and utilization of waste lead-acid battery separators, which can not only solve the practical problems of waste lead-acid battery separator disposal, but also meet the needs of the times for high-value utilization of energy resources. Summary of the invention

[0003] The purpose of the present invention is to solve the problems of large amount of waste PE separators of waste lead-acid batteries, waste of resources, and difficulty in recycling due to poor fluidity. The basic principle is to use a near-melting point processing method to avoid the disadvantage of thermal decomposition of PE separators caused by high temperature, and gradually add linear low-density polyethylene to improve the processing fluidity of PE separators. Subsequently, the interface structure of PE separators is improved through the mechanochemical reaction function of solid-phase mechanochemical grinding equipment, and its interface interaction with polypropylene is enhanced, thereby realizing the value-added utilization of PE separator materials of waste lead-acid batteries.

[0004] The purpose of the present invention is achieved through the following technical solutions.

[0005] The present invention provides a method for recycling PE separators of waste lead-acid batteries, and the recycling method comprises the following steps: (1) Use near-infrared spectroscopy technology to identify the six components of waste lead-acid battery separator materials (PE separator, fiber cloth, plastic shell, label paper, plastic film and packaging paper) and sort them in combination with obsolete equipment; (2) placing the PE separator obtained in step (1) into deionized water at 80°C, adding a surfactant and a lead removal agent, and mechanically stirring for 1 hour. After the reaction is completed, taking out the PE separator and drying it; (3) The PE separator obtained in step (2) is added to a double-roll mill at 140° C. and mixed, and then the linear low-density polyethylene is gradually added and mixed evenly. The obtained mixture is coarsely crushed by a crusher and then added to a solid phase force chemical grinding equipment to be ground into fine granular PE separators; (4) The fine granular PE separator obtained in step (3) is used as a modifier for polypropylene.

[0006] The mass ratio of the surfactant sodium dodecyl sulfate to the PE separator in step (2) is 1:8, and the molar ratio of the lead removal agent concentrated nitric acid to sodium chloride is 2:1.

[0007] The amount of the linear low-density polyethylene added in step (3) is 20-50% of the total mass of the linear low-density polyethylene and the PE separator. The particles are ground 1-3 times in a solid phase mechanochemical grinder to obtain a PE separator with a particle size of 30-100 mesh.

[0008] The amount of the granular PE separator added in step (4) is 5-20% of the total mass of the granular PE separator and polypropylene.

[0009] The scientific principle of the invention: Firstly, the disadvantage of thermal decomposition of materials due to high temperature is avoided by combining near-melting point processing with distributed feeding method.

[0010] Secondly, solid phase chemical grinding further improves the fluidity of PE separator on the one hand, and improves the interface bonding performance of PE separator on the other hand.

[0011] Compared with the prior art, the present invention has the following technical effects: Based on the coupling technology of blending modification and solid-phase force chemical grinding, the processing performance and interface bonding performance of recycled waste lead-acid battery separator materials are improved. This material can enhance the impact resistance and wear resistance of polypropylene while ensuring the original tensile and bending properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a comparison chart of the melt flow rates of the PE separator / linear low-density polyethylene composite material after solid phase mechanochemical grinding prepared in Example 1 of the present invention and the unground PE separator / linear low-density polyethylene composite material of Comparative Example 1.

[0013] Figure 2 The impact performance of the PE separator / polypropylene composite material prepared in Example 1 of the present invention and the pure polypropylene material in Comparative Example 2 was tested. DETAILED DESCRIPTION

[0014] The present invention is described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. Example 1

[0015] A method for recycling PE separators of waste lead-acid batteries, the preparation steps are as follows: (1) The six components of the waste lead-acid battery PE separator miscellaneous materials (waste lead-acid battery PE separator, fiber cloth, plastic shell, label paper, plastic film and packaging paper) are identified by near-infrared spectroscopy technology and separated by jigging equipment, wherein the near-infrared spectroscopy technology adopts the method of Chinese patent application number CN202310212683.6, and the jigging equipment separation adopts the technology of Chinese patent application number CN201911260961.5; the obtained waste lead-acid battery PE separator (200 g) is placed in 80°C deionized water, sodium dodecyl sulfate (25 g), concentrated nitric acid (1.32 ml) and sodium chloride (0.87 g) are added, and then mechanically stirred for 1 hour. After the reaction is completed, the waste lead-acid battery PE separator is taken out and dried; (2) The waste lead-acid battery PE separator obtained in step (1) is added to a double-roll open mill at 140°C for mixing, and then the linear low-density polyethylene is gradually added and mixed evenly. The obtained waste lead-acid battery PE separator / linear low-density polyethylene mixture is coarsely crushed in a crusher and then added to a solid phase force chemical grinding device for grinding 1-3 times into fine particles of the waste lead-acid battery PE separator / linear low-density polyethylene mixture. The melt flow rate test result is shown in Figure 1 , linear low-density polyethylene accounts for 50% of the total mass (after mixing PE separator of waste lead-acid battery with linear low-density polyethylene).

[0016] (3) The fine particles of the waste lead-acid battery PE separator / linear low-density polyethylene ground three times in step (2) are blended with polypropylene in a twin-screw extruder and injection-molded into mechanical splines by an injection molding machine. The waste lead-acid battery PE separator / linear low-density polyethylene mixture ( Figure 2 The amount of PE separator (hereinafter referred to as PE separator) added accounts for 5%, 10%, 20% of the total mass (after mixing fine granular PE separator / linear low-density polyethylene and polypropylene) (i.e. Figure 2 5% PE separator, 10% PE separator, 20% PE separator on the horizontal axis), and then the mechanical properties test was carried out. The test results are shown in Figure 2 .

[0017] The melt flow rate of the ground waste lead-acid battery PE separator / linear low-density polyethylene mixture prepared in Experimental Example 1 was measured. The melt flow rate index of grinding once was 2.04 g / 10 min, the melt flow rate index of grinding twice was 2.845 g / 10 min, and the melt flow rate index of grinding three times was 3.378 g / 10 min. All of them were higher than the melt flow rate of the unground waste lead-acid battery PE separator / linear low-density polyethylene mixture prepared in Comparative Example 1.

[0018] The impact strength of the mixture of PE separator of waste lead-acid battery / linear low-density polyethylene and polypropylene prepared in this experimental example was measured. The impact strength of the mixture of PE separator of waste lead-acid battery / linear low-density polyethylene with a content of 5% was 7.11 KJ / m 2 The impact strength of the waste lead-acid battery PE separator / linear low-density polyethylene mixture with a content of 10% is 7.25KJ / m 2 The impact strength of the waste lead-acid battery PE separator / linear low-density polyethylene mixture with a content of 20% is 7.02KJ / m 2 , which are higher than the impact strength of the pure polypropylene prepared in Comparative Example 2.

[0019] Comparative Example 1 (1) The six components of the waste lead-acid battery PE separator miscellaneous materials (waste lead-acid battery PE separator, fiber cloth, plastic shell, label paper, plastic film and packaging paper) are identified by near-infrared spectroscopy technology and separated by jigging equipment, wherein the near-infrared spectroscopy technology adopts the method of Chinese patent application number CN202310212683.6, and the jigging equipment separation adopts the technology of Chinese patent application number CN201911260961.5; the obtained waste lead-acid battery PE separator (200 g) is placed in 80°C deionized water, sodium dodecyl sulfate (25 g), concentrated nitric acid (1.32 ml) and sodium chloride (0.87 g) are added, and then mechanically stirred for 1 hour. After the reaction is completed, the waste lead-acid battery PE separator is taken out and dried; (2) The waste lead-acid battery PE separator obtained in step (1) was added to a double-roll open mill at 140°C for mixing, and then the linear low-density polyethylene was gradually added and continued to mix evenly. The obtained waste lead-acid battery PE separator / linear low-density polyethylene mixture was tested for melt flow rate after coarse crushing in a crusher. The linear low-density polyethylene accounted for 50% of the total mass (after the waste lead-acid battery PE separator and the linear low-density polyethylene were mixed). The melt flow rate of the waste lead-acid battery PE separator / linear low-density polyethylene mixture prepared in this comparative example 1 was measured to be 1.831 g / 10 min.

[0020] Comparative Example 2 A certain amount of pure polypropylene was injected into mechanical specimens for impact performance testing, and the temperature of the injection molding machine was 195°C. The impact performance of the pure polypropylene prepared in this comparative example 2 was measured to be 5.62 KJ / m 2 .

Claims

1. A method for recycling PE separators of waste lead-acid batteries, characterized in that: The steps include: (1) Identify six components of waste lead-acid battery separator materials through near-infrared spectroscopy technology, which are PE separator, fiber cloth, plastic shell, label paper, plastic film and packaging paper, and sort them in combination with obsolete equipment; (2) placing the PE separator obtained in step (1) into deionized water at 80°C, adding a surfactant and a lead removal agent, and mechanically stirring for 1 hour. After the reaction is completed, taking out the PE separator and drying it; (3) The PE separator obtained in step (2) is added to a double-roll mill at 140° C. and mixed, and then the linear low-density polyethylene is gradually added and mixed evenly. The obtained mixture is coarsely crushed by a crusher and then added to a solid phase force chemical grinding equipment to be ground into fine granular PE separators; (4) The fine granular PE separator obtained in step (3) is used as a modifier for polypropylene.

2. The method for recycling PE separators of waste lead-acid batteries according to claim 1, characterized in that: The surfactant described in step (2) is sodium dodecyl sulfate, and the mass ratio of the sodium dodecyl sulfate to the PE separator is 1:8; the lead removal agent is concentrated nitric acid and sodium chloride, and the molar ratio of the concentrated nitric acid to sodium chloride is 2:

1.

3. The method for recycling PE separators of waste lead-acid batteries according to claim 1, characterized in that: The amount of the linear low-density polyethylene added in step (3) is 20-50% of the total mass of the mixture of the linear low-density polyethylene and the PE separator. The mixture is ground 1-3 times in a solid phase mechanochemical grinder to obtain a PE separator with a particle size of 30-100 mesh.

4. A method for recycling PE separators of waste lead-acid batteries according to any one of claims 1 to 3, characterized in that: The amount of the fine granular PE separator added in step (4) is 5-20% of the total mass of the granular PE separator and polypropylene.

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