Method for simply recycling carbon from waste glass fiber reinforced plastics and electrode material

Abstract

The invention provides a method for simply recovering carbon from waste glass fiber reinforced plastic and an electrode material. The method comprises the following steps: S1, crushing and grinding the waste glass fiber reinforced plastic into glass fiber reinforced plastic powder; s2, physically separating the ground glass fiber reinforced plastic powder according to the specific gravity of resin and glass fiber to obtain resin powder; s3, the resin powder and acid are mixed for a reaction, and pre-carbonized powder is obtained; s4, pyrolyzing the pre-carbonized powder to obtain carbon powder; wherein the weight ratio of the acid to the resin in the step S3 is (0.1-1): 1, and the mass concentration of the acid is 10-100%. According to the method, the crushed glass fiber reinforced plastic particles are further ground into the powder with the micron particle size, then the obtained glass fiber reinforced plastic powder is directly subjected to physical separation to obtain the resin powder, the acid and the resin powder react, and then low-temperature pyrolysis is conducted, so that the carbon recovery rate is increased, and the electrical performance of subsequent hard carbon can be improved.

Description

Technical Field

[0001] This invention belongs to the field of waste fiberglass recycling technology, and particularly relates to a simple method for recycling carbon from waste fiberglass and an electrode material. Background Technology

[0002] Sodium-ion batteries (SIBs) are considered the most beneficial complement to lithium-ion batteries due to their low cost, abundant sodium reserves, and high safety performance, and are expected to be widely used in electric vehicles, energy storage power stations, and large-scale energy storage. Sodium-ion batteries mainly consist of positive and negative electrode materials, a separator, and an electrolyte. Among the many negative electrode materials for sodium-ion batteries, hard carbon has become the preferred negative electrode material for the commercialization of sodium-ion batteries due to its abundant sources, low cost, simple preparation process, low sodium intercalation platform, and high sodium storage capacity.

[0003] Mainstream hard carbon comes from three types of raw materials: biomass such as straw, bamboo, and coconut shells, which produce hard carbon with acceptable specific capacity but high ash content and poor consistency; coal-based materials such as pitch and needle coke, which produce hard carbon with low specific capacity and interlayer spacing closer to soft carbon, and can only be used as low-end hard carbon; the industry-recognized high-end hard carbon comes from resin raw materials such as phenolic resin, epoxy resin, and unsaturated polyester resin. However, resin raw materials are expensive, with phenolic resin priced at approximately 8,000 yuan / ton and epoxy resin at approximately 14,000 yuan / ton. Hard carbon produced using resin as raw material is too expensive for the market to accept.

[0004] At the same time, fiberglass has a long lifespan, is resistant to acids and alkalis, and cannot be naturally degraded.

[0005] Using waste fiberglass as raw material to prepare hard carbon has a significant cost advantage, but the difficulty lies in how to obtain the resin from the fiberglass.

[0006] Chinese patent application CN201910327680.0 discloses a method for preparing hard carbon anode material, including crushing fiberglass, low-temperature pre-carbonizing to generate pre-carbonized resin, immersing the pre-carbonized resin in a strong alkaline solution to dissolve the glass fibers, obtaining insoluble particles C, mixing the insoluble particles C with starch, and then carbonizing at high temperature to obtain solid D, and pulverizing and classifying solid D to obtain hard carbon anode material. However, this patent requires the use of a large amount of alkaline solution to dissolve the residual glass fibers, generating a large amount of water glass solution. A large amount of water is needed to dissolve the water glass to separate it from the carbon powder, leading to significant environmental and cost pressures. Furthermore, this patent lacks a purification process, inevitably leaving metallic impurities in the fiberglass, which negatively impacts the electrical performance of the hard carbon anode material.

[0007] Another Chinese patent application, CN202210717470.4, discloses a method for the resource utilization of waste fiber-reinforced composite materials. However, this patent uses an excessive amount of sulfuric acid to dissolve the resin, with the amount of acid being 20-100 times the weight of the resin. This will bring huge pressure on subsequent environmental treatment and directly increase the cost of hard carbon products. Summary of the Invention

[0008] In view of this, the present invention provides a simple method for recycling carbon from waste fiberglass and an electrode material. The present invention further grinds the crushed fiberglass powder into powder with a micron particle size, and then directly performs physical separation on the obtained fiberglass powder to obtain resin powder. The resin powder is then reacted with acid and then subjected to low-temperature pyrolysis, which not only improves the carbon recovery rate, but also enhances the electrical properties of the subsequent hard carbon.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows: The first aspect of this invention provides a simple method for recycling carbon from waste fiberglass, comprising the following steps: S1: Crushing and grinding waste fiberglass into fiberglass powder; S2: The ground fiberglass powder is physically separated according to the specific gravity of carbon powder and glass fiber to obtain resin powder; S3: Mix resin powder with acid and react to obtain pre-carbonized powder; S4: Pyrolyze the pre-carbonized powder to obtain carbon powder; In step S3, the weight ratio of acid to resin is 0.1-1:1, and the mass concentration of acid is 10-100%.

[0010] The waste fiberglass is a composite material obtained by combining glass fiber and resin. The resin includes any one or more of phenolic resin, epoxy resin, or unsaturated polyester resin.

[0011] In one preferred embodiment, the acid in step S3 is selected from any one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid.

[0012] In one preferred embodiment, during step S3, the resin powder and acid are mixed and heated simultaneously to 50-150°C.

[0013] In one preferred embodiment, the crushing in step S1 involves cutting, coarsely crushing, and then crushing the waste fiberglass into fiberglass particles with a particle size of 1-3 mm.

[0014] In one preferred embodiment, the grinding in step S1 specifically involves subjecting the crushed fiberglass particles to a roller mill, a high-speed mill, or an air jet mill to obtain fiberglass powder with a D50 of 5-7 μm.

[0015] In one preferred embodiment, the low-temperature pyrolysis in step S4 specifically involves treating the pre-carbonized powder at 400-600°C for 2-5 hours under an inert atmosphere to decompose the product of the reaction between the fiberglass and the acid.

[0016] One preferred embodiment further includes step S5: carbonizing the obtained carbon powder at high temperature to obtain hard carbon, or activating it to obtain porous carbon.

[0017] The high-temperature carbonization involves treating the obtained toner powder at a high temperature of 800-1600℃ for 2-6 hours under a protective atmosphere.

[0018] The carbon powder obtained by high-temperature carbonization is subjected to grinding or air jet milling to obtain hard carbon powder with a D50 of 5-7μm.

[0019] The activation specifically involves mixing the pre-carbonized carbon powder with KOH, NaOH, Na2CO3, or ZnCl2 powder at a weight ratio of 1:1-5, and then treating it at a high temperature of 800-1000℃ for 1-3 hours under the protection of an inert gas to obtain porous carbon powder.

[0020] Based on the same inventive concept, a second aspect of the present invention also provides an electrode material, which is prepared by the method for recycling carbon from waste fiberglass in any of the above embodiments.

[0021] Because the present invention adopts the above technical solution, it has the following advantages and positive effects compared with the prior art: This invention provides a simple method for recovering carbon from waste fiberglass. First, the waste fiberglass is crushed into particles, then further ground into micron-sized powder. The entangled resin and glass fibers are separated, and then physically separated using the difference in specific gravity between the fibers and glass fibers to obtain resin powder. The resin powder is then mixed with a small amount of acid. This removes residual metals from the resin powder and allows the resin to react with the acid. Subsequent low-temperature pyrolysis decomposes the reacted resin into carbon. This invention avoids the direct pyrolysis of resin, which would cause some carbon to volatilize as gas, thus increasing the carbon recovery rate. Furthermore, it uses a small amount of acid, and approximately 70% can be recovered after concentration, resulting in minimal subsequent environmental impact, less environmental pressure, and low production costs.

[0022] This invention involves mixing resin powder with a small amount of acid before pyrolysis, using a strongly oxidizing acid solution to pre-carbonize the resin. For example, the carbon yield after pre-carbonization of epoxy resin can reach 30-40%, while experiments have shown that the carbon yield of epoxy resin powder directly subjected to pyrolysis at 500°C is no higher than 16%.

[0023] This invention utilizes crushing and grinding methods to separate resin and glass fiber, which is simple and allows for the direct extraction of resin.

[0024] The electrode material obtained by the method provided in this invention has advantages such as good consistency, good controllability, low ash content, and high specific capacity.

[0025] We can collaborate with existing waste fiberglass crushing plants in the market to directly collect the crushed fiberglass particles from these plants, significantly reducing pre-processing investment. This achieves the recycling of waste fiberglass, reduces processing costs for fiberglass companies, and simultaneously addresses the social issue of environmentally friendly fiberglass disposal.

[0026] The resulting carbon powder can be either carbonized at high temperatures into hard carbon for use as a negative electrode material in sodium-ion batteries, or activated into porous carbon for use as a negative electrode material in lithium-ion batteries. The product can be adapted to different market changes, resulting in more robust economic performance.

[0027] The method for recycling and preparing carbon provided by this invention uses waste fiberglass as raw material. Fiberglass is widely available and has a negative cost (waste disposal fees can be charged), making it suitable for large-scale production and showing great application potential. Attached Figure Description

[0028] Figure 1 Photographs of broken fiberglass particles according to an embodiment of the present invention; Figure 2 These are photographs of the resin pre-carbonized with sulfuric acid in Examples 1-3 of this invention; Figure 3 The electrical performance test curve of the hard carbon powder obtained in Example 2 of this invention as the negative electrode of a sodium-ion battery is shown. Figure 4 This is a BET image of the toner obtained after thermal decomposition in Example 1 of the present invention. Detailed Implementation

[0029] This invention addresses the current process of recycling waste fiberglass and proposes a simplified method for preparing carbon from waste fiberglass, along with an electrode material, from the perspectives of carbon recovery rate and environmental protection. The electrode material prepared using the process of this invention has the advantages of excellent consistency, controllability, low ash content, and high specific capacity. Moreover, the recycling process is environmentally friendly and has a high carbon recovery rate.

[0030] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a simplified method for recycling carbon from waste fiberglass and the electrode material proposed in this invention. The advantages and features of this invention will become clearer from the following description.

[0031] This invention provides a simple method for recycling carbon from waste fiberglass, wherein the waste fiberglass is a composite material containing glass fiber and resin, wherein the resin is phenolic resin, epoxy resin or unsaturated polyester resin, etc. Common fiberglass can be used for fan blades, reaction vessels, corrosion-resistant pipes or PCB boards, etc.

[0032] The method specifically includes the following steps: S1: The waste fiberglass is cut, coarsely crushed, and then crushed into particles with a diameter of 1-3mm (e.g., ...). Figure 1 The crushed fiberglass granules reduce processing costs and improve transportation efficiency. For example, wind turbine blades and automotive parts are large and irregularly shaped, making direct transportation and processing expensive. The crushing process, using equipment such as shredders and fine crushers, gradually reduces large pieces of waste to millimeter-sized particles, significantly reducing their volume percentage. For instance, after crushing, the volume of a 1-ton large fiberglass blade can be reduced to 1 / 5 to 1 / 3 of its original volume, increasing the loading capacity of transport vehicles by 3 to 5 times and directly reducing logistics costs. The crushed granules are also easier to pass through conveyor belts, screw feeders, and other equipment into subsequent processing stages, avoiding jamming or damage to equipment caused by large pieces of material. On the other hand, it exposes the interface between the resin and glass fiber, promoting separation. Fiberglass is a three-dimensional network structure formed by the tight bonding of glass fiber and resin matrix through chemical bonds and mechanical interlocking. Crushing, through external forces such as shearing and extrusion, disrupts the interfacial bonding between fibers and resin, achieving initial separation of fibers and resin: In the crushed particles, some fibers break off from the resin due to stress, forming a mixture of "fiber bundles + resin fragments," providing a basis for separation in subsequent process steps; and increasing surface area: Crushing increases the specific surface area of ​​the particles, accelerating the penetration and dissolution of the resin by acid in subsequent chemical recycling, and improving reaction efficiency.

[0033] S2: The crushed fiberglass particles are further processed by roller milling, high-speed milling or air jet milling to obtain fiberglass powder with D50=5-7μm, which further promotes the separation of resin and glass fiber.

[0034] S3: Physically separate fiberglass powder according to the specific gravity of resin and glass fiber, such as using air classifiers and shaking tables.

[0035] S4: Pre-carbonization of resin powder by reacting it with acid: The weight ratio of acid to resin is controlled at 0.1-1:1, and the mass concentration of acid is 10-100%. The resin powder and acid are mixed and simultaneously stirred and heated at 50-150℃ for 20-40 minutes. This invention strictly controls the amount of acid. On the one hand, a small amount of acid reacts with the hydrogen in the resin powder to synthesize water, thereby reducing the leakage of hydrocarbon gases during pyrolysis and increasing the carbon yield. Excessive acid will react with carbon to produce carbon dioxide and carbon monoxide, which will also reduce the carbon recovery rate; therefore, the amount of acid used must be controlled. On the other hand, the acid is used to dissolve and physically separate metallic impurities in the resin. The results of pre-carbonizing the resin with different amounts and concentrations of acid are shown below. Figure 2 As shown.

[0036] The acid can be any one of inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid, or a mixture of any two or three of them.

[0037] S5: The pre-carbonized powder is subjected to low-temperature pyrolysis. Specifically, the pre-carbonized powder is treated at 400-600℃ for 2-5 hours under an inert atmosphere, so that the pre-carbonized resin is cracked into gases such as CO2, H2, CO, and CH4, elemental carbon, and a very small amount of tar under high temperature, and finally carbon powder is obtained.

[0038] S6: The obtained carbon powder is carbonized at high temperature to obtain hard carbon, or activated to obtain porous carbon.

[0039] Specifically, the high-temperature carbonization involves treating the obtained carbon powder at a high temperature of 800-1600℃ for 2-6 hours under a protective atmosphere such as nitrogen or argon. The carbon powder obtained by high-temperature carbonization is then subjected to grinding or air jet milling to obtain hard carbon powder with a D50 of 5-7μm. Hard carbon powder can be used as an electrode material for sodium-ion batteries.

[0040] The activation process involves mixing the pre-carbonized carbon powder with KOH, NaOH, Na2CO3, or ZnCl2 powder at a weight ratio of 1:1-5, and then treating it at a high temperature of 800-1000℃ for 1-3 hours under the protection of an inert gas to obtain porous carbon powder. Porous carbon can be used to prepare silicon-carbon anode materials for lithium-ion batteries.

[0041] Example 1 Take 100 grams of waste fiberglass, crush it to obtain fibrous fiberglass particles; The obtained fiberglass particles were pulverized by air jet milling to obtain a mixed powder with a D50 of 6 μm. The resin powder and glass fiber powder were separated by gravity separation on a shaker. Mix the resin powder with 100g of 50% phosphoric acid solution, heat to 80℃, and mechanically stir at 200rpm for 30 minutes. The pre-carbonized powder was placed in an argon-protected tube furnace for pyrolysis and kept at 500°C for 3 hours to obtain carbon powder. The BET specific surface area of ​​the carbon powder was measured to be 32.628 m². 2 / g, such as Figure 4 As shown.

[0042] Carbon powder and KOH powder were mixed in a weight ratio of 1:4 and placed in an argon-protected furnace. The mixture was heated to 900°C at a heating rate of 5°C / min and held at 900°C for 2 hours to obtain activated carbon powder. The activated carbon powder was then removed after natural cooling. The activated carbon powder was washed and dried to obtain 26g of carbon powder; The BET specific surface area of ​​the obtained porous carbon powder was measured to be 1352.4 m². 2 / g, the results show that porous carbon powder has a high specific surface area.

[0043] Example 2: Take 100 grams of waste fiberglass, crush it to obtain fibrous fiberglass particles; The obtained fiberglass particles were pulverized by air jet milling to obtain a mixed powder with a D50 of 6 μm. The resin powder and glass fiber powder were separated by gravity separation on a shaker. Mix the resin powder with 10 grams of 20% sulfuric acid solution, heat to 120°C, and mechanically stir at 200 rpm for 30 minutes. The pre-carbonized powder was placed in an argon-protected tube furnace for pyrolysis and kept at 500°C for 3 hours to obtain 14g of carbon powder. Carbon powder was placed in an argon-protected tube furnace and heated to 1400°C at a heating rate of 5°C / min. The powder was then treated at 1400°C for 4 hours to obtain hard carbon powder.

[0044] The obtained hard carbon was pulverized by air jet milling, and after washing and drying, hard carbon powder with a D50 of 6 μm was obtained. This carbon powder was used as the negative electrode material for sodium-ion batteries, and the electrochemical performance of this hard carbon material was studied. The results are as follows: Figure 3 As shown, the hard carbon anode has a high reversible capacity and first-cycle coulombic efficiency.

[0045] Example 3 Take 100 grams of waste fiberglass, crush it to obtain fibrous fiberglass particles; The obtained fiberglass particles were pulverized by air jet milling to obtain a mixed powder with a D50 of 6 μm. The resin powder and glass fiber powder were separated by gravity separation on a shaker. Mix the resin powder with 50g of 40% sulfuric acid solution, heat to 50°C, and mechanically stir at 200rpm for 30 minutes. The pre-carbonized powder was placed in an argon-protected tube furnace for pyrolysis and kept at 500°C for 3 hours to obtain 20g of carbon powder. Carbon powder was placed in an argon-protected tube furnace and heated to 1600°C at a heating rate of 5°C / min. It was then treated at 1600°C for 4 hours to obtain hard carbon powder.

[0046] Comparative Example 1 Unlike Example 1, the step of mixing the resin powder with sulfuric acid was omitted, while the other steps remained the same. The pyrolysis step yielded 8g of carbon powder.

[0047] Comparative Example 2 Unlike Example 1, the resin powder was mixed with 200 g of 98% sulfuric acid solution, heated to 50°C, and mechanically stirred at 200 rpm for 30 minutes. Other steps were the same as in Example 1, and the pyrolysis step yielded 10 g of carbon powder.

[0048] Calculate the carbon recovery rate A = m after separation in Examples 1-3 and Comparative Examples 1-2 above. 碳 / m 玻璃状纤维 *100%, the results are as follows: The carbon recovery rates in Examples 1-3 and Comparative Examples 1-2 show that the carbon recovery rate in Examples 1-3 is greater than that in Comparative Example 1, indicating that using acid pre-carbonization of the resin before pyrolysis can increase the carbon recovery rate. Compared with Comparative Example 2, Examples 1-3 show that controlling the acid pre-carbonization of the resin is necessary to improve the carbon recovery rate.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. A simple method for recycling carbon from waste fiberglass, characterized in that, Includes the following steps: S1: Crushing and grinding waste fiberglass into fiberglass powder; S2: The ground fiberglass powder is physically separated according to the specific gravity of resin and glass fiber to obtain resin powder; S3: Mix resin powder with acid and react to obtain pre-carbonized powder; S4: Pyrolyze the pre-carbonized powder to obtain carbon powder; In step S3, the weight ratio of acid to resin is 0.1-1:1, and the mass concentration of acid is 10-100%.

2. The method for simple carbon recovery from waste fiberglass according to claim 1, characterized in that, The acid used in step S3 is selected from any one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid.

3. The method for simple carbon recovery from waste fiberglass according to claim 1, characterized in that, The crushing in step S1 involves cutting, coarsely crushing, and then crushing the waste fiberglass into fiberglass particles with a particle size of 1-3mm.

4. The method for simple carbon recovery from waste fiberglass according to claim 3, characterized in that, The grinding process in step S1 specifically involves subjecting the crushed particles to a roller mill, high-speed mill, or air jet mill to obtain fiberglass powder with a D50 of 5-7 μm.

5. The method for simple carbon recovery from waste fiberglass according to claim 1, characterized in that, The low-temperature pyrolysis in step S4 specifically involves treating the pre-carbonized powder at 400-600℃ for 2-5 hours under an inert atmosphere to decompose the product of the reaction between the fiberglass and the acid.

6. The method for simple carbon recovery from waste fiberglass according to claim 1, characterized in that, It also includes step S5, which involves high-temperature carbonization or activation of the obtained toner.

7. The method for simple carbon recovery from waste fiberglass according to claim 6, characterized in that, The high-temperature carbonization involves treating the obtained toner powder at a high temperature of 800-1600℃ for 2-6 hours under a protective atmosphere.

8. The method for simple carbon recovery from waste fiberglass according to claim 6, characterized in that, The activation specifically involves mixing the pre-carbonized carbon powder with KOH, NaOH, Na2CO3, or ZnCl2 powder at a weight ratio of 1:1-5, and then treating it at a high temperature of 800-1000℃ for 1-3 hours under the protection of an inert gas to obtain porous carbon powder.

9. The method for simple carbon recovery from waste fiberglass according to claim 1, characterized in that, Also includes: The carbon powder obtained by high-temperature carbonization is subjected to grinding or air jet milling to obtain hard carbon powder with a D50 of 5-7μm.

10. An electrode material, characterized in that, The electrode material is obtained by the simple carbon recycling method for waste fiberglass as described in any one of claims 1-9.

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