Method for high-yield carbon recovery from waste glass fiber reinforced plastics and electrode material

Abstract

The invention discloses a method for recovering carbon from waste glass fiber reinforced plastics at high yield and an electrode material. The method for recovering carbon from waste glass fiber reinforced plastics at high yield comprises the following steps: S1, crushing waste glass fiber reinforced plastics into glass fiber reinforced plastics particles; s2, reacting the glass fiber reinforced plastic particles with acid for pre-carbonization; s3, performing low-temperature pyrolysis on the pre-carbonized powder; s4, performing physical separation of carbon powder and glass fiber on the powder subjected to low-temperature pyrolysis; wherein the weight ratio of the glass fiber reinforced plastic particles to the acid is (1-5): 1, and the mass concentration of the acid is 10-100%. The crushed glass fiber reinforced plastic particles react with acid and then are subjected to low-temperature pyrolysis, so that not only is the carbon recovery rate improved, but also the electrical property of hard carbon can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of waste glass steel resource utilization, and particularly relates to a method for recycling carbon from waste glass steel at a high yield and an electrode material. BACKGROUND

[0002] Sodium-ion batteries (SIBs) are called the most beneficial supplement of lithium-ion batteries due to their low cost, abundant sodium reserves, high safety performance and other characteristics, and are expected to be widely used in electric vehicles, energy storage power stations and large-scale energy storage fields. Sodium-ion batteries mainly consist of positive and negative electrode materials, separators and electrolytes. Among the many sodium-ion battery negative electrode materials, hard carbon is the first choice for commercialization of sodium-ion batteries due to its abundant source, low cost, simple preparation process, low sodium intercalation platform, high sodium storage capacity and other characteristics.

[0003] The mainstream hard carbon is derived from three raw materials: biomass such as straw, bamboo, coconut shell, etc., the prepared hard carbon has a good specific capacity but a large ash content and poor consistency; coal-based such as pitch, needle coke, etc., the prepared hard carbon has a low specific capacity and a layer spacing closer to soft carbon, and can only be used as low-end hard carbon; and the industry-recognized high-end hard carbon is derived from resin raw materials such as phenolic resin, epoxy resin and unsaturated polyester resin, etc. However, the cost of resin raw materials is high, such as the market price of phenolic resin is about 8000 yuan / ton, and the market price of epoxy resin is about 14000 yuan / ton. The price of hard carbon prepared from resin as a raw material is too high, which is unacceptable in the market.

[0004] Meanwhile, China is the largest producer of glass steel in the world, and produced about 7.5 million tons of glass steel in 2024, accounting for about 66% of the global share. Glass steel has a long service life, is resistant to acid and alkali, cannot be naturally degraded, and is not allowed to be landfilled, and can only be treated at a waste incineration plant at a waste treatment fee of 1000-4000 yuan per ton.

[0005] Preparation of hard carbon from waste glass steel has obvious cost advantages, but the difficulty lies in how to obtain resin from glass steel. The conventional method is to grind the glass steel to a diameter of 3-10 mm, and then use the specific gravity difference for physical separation. However, due to the effect of the sizing agent, the glass fiber is tightly combined with the resin, and at this time only about 30-40% of the glass fiber can be separated. To further separate the glass fiber, the glass steel needs to be further ground to about 20-50 um. However, deep grinding consumes a large amount of energy, and even if the particles are ground to a very small size, they cannot be completely separated, and the residual glass fiber particles will have a negative impact on the electrical performance of the hard carbon.

[0006] Chinese patent application No. CN201910327680.0 discloses a hard carbon negative material preparation method, which comprises crushing glass steel, low-temperature pre-carbonization to generate pre-carbonized resin, immersing the pre-carbonized resin in a strong alkali solution to dissolve the glass fibers, obtaining insoluble particles C, uniformly mixing the insoluble particles C with starch, and then high-temperature carbonization to obtain solid D. The solid D is crushed and graded to obtain a hard carbon negative material. However, the patent needs to use a large amount of alkali liquor to dissolve the residual glass fibers, which produces a large amount of water glass solution. A large amount of water is needed to dissolve the water glass to separate the carbon powder, thereby causing huge environmental and cost pressures. The patent does not have a impurity removal step. Metal impurities are inevitably left in the glass steel, which will negatively affect the electrical properties of the hard carbon.

[0007] Another Chinese patent application No. CN202210717470.4 discloses a resource utilization method of waste fiber reinforced composite material. However, the patent uses an excessive amount of sulfuric acid to dissolve the resin. The acid usage is 20-100 times the weight of the resin, which will cause huge subsequent environmental treatment pressures and directly increase the cost of the hard carbon product. SUMMARY

[0008] Therefore, the present application provides a method for recycling carbon from waste glass steel with high yield and an electrode material. The present application reacts the crushed glass steel particles with acid and then performs low-temperature pyrolysis. The carbon recovery rate is improved, and the electrical properties of the hard carbon are also improved.

[0009] To achieve the above-mentioned purposes, the technical solutions of the present application are as follows: The first aspect of the present application provides a method for recycling carbon from waste glass steel with high yield, which comprises the following steps: S1: crushing waste glass steel into glass steel particles; S2: reacting the glass steel particles with acid for pre-carbonization; S3: low-temperature pyrolysis of the pre-carbonized powder; S4: physical separation of the carbon powder and glass fibers after low-temperature pyrolysis to obtain carbon powder; The weight ratio of the glass steel particles to the acid is 1-5:1, and the mass concentration of the acid is 10-100%.

[0010] In a preferred embodiment, the acid in step S2 is selected from any one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid, and nitric acid.

[0011] In a preferred embodiment, the low-temperature pyrolysis in step S3 is specifically: treating the pre-carbonized powder at a temperature of 400-600℃ for 2-5h under the protection of an inert atmosphere to decompose the product after the reaction of the glass steel with the acid.

[0012] In a preferred embodiment, the separation in step S4 is performed by using the specific gravity or electrical conductivity of the carbon powder and the glass fiber powder.

[0013] In a preferred embodiment, the method further comprises step S5: high-temperature carbonization of the obtained carbon powder to obtain hard carbon, or activation to obtain porous carbon.

[0014] In a preferred embodiment, the high-temperature carbonization is performed by treating the separated carbon powder at a high temperature of 800-1600℃ for 2-6h under a protective atmosphere. Preferably, the method further comprises a grinding step: grinding the high-temperature carbonized carbon powder by using a pair of grinding wheels or an air jet mill to obtain hard carbon powder with a D50 of 5-7um.

[0015] In a preferred embodiment, the activation is performed by mixing the pre-carbonized carbon powder with KOH, NaOH, Na2CO3 or ZnCl2 powder at a weight ratio of 1:1-5, uniformly mixing, and treating at a high temperature of 800-1000℃ for 1-3h under the protection of inert gas to obtain porous carbon powder.

[0016] In a preferred embodiment, the waste glass steel is a composite material obtained by compounding glass fibers and resin, wherein the resin is any one of phenolic resin, epoxy resin or unsaturated polyester resin.

[0017] In a preferred embodiment, the crushing step in step S1 is performed by cutting, coarse breaking and crushing the waste glass steel to break the glass steel into particles with a particle size of 1-3mm.

[0018] In a preferred embodiment, the glass steel fibers in step S1 are broken into fibers with a diameter of 1-2mm and a length of 5-30mm.

[0019] The second aspect of the present application also provides an electrode material prepared by the method for high-yield recovery of carbon from waste glass steel according to any one of the above embodiments.

[0020] The present application has the following advantages and positive effects compared with the prior art due to the use of the above technical solutions: The method for recycling carbon from waste glass steel with high yield provided by the application first crushes the waste glass steel into glass steel particles, and then mixes the glass steel particles with acid, which can remove the metal residues in the glass steel particles, and the resin in the glass steel particles can be dehydrated and pre-carbonized by reacting with the acid, and then the pre-carbonized resin can be decomposed into carbon by subsequent low-temperature pyrolysis, and most of the impurities in the carbon powder can be automatically removed, and the carbon powder can be obtained by subsequently physically separating the carbon powder from the glass fiber. The resin powder can be dehydrated by reacting with the acid, which can increase the carbon recovery rate, and can greatly reduce the production of tar, which is conducive to the separation of the glass fiber powder and the carbon powder in the subsequent process, and the amount of acid used is small and can be recycled after concentration, which has little impact on the environment, has little environmental pressure, and has low production cost. The electrode material obtained by the method provided by the application has the advantages of good consistency, good controllability, low ash content, high specific capacity and the like.

[0021] The glass fiber can be separated from the resin in a relatively easy way after low-temperature pyrolysis, because the sizing agent can be damaged by high-temperature treatment.

[0022] The glass powder is mixed with the acid in the preparation process, and then directly subjected to low-temperature pyrolysis and high-temperature carbonization, so that the amount of water treatment in the whole process is small.

[0023] The regenerated glass fiber obtained by the application has a large length, which is conducive to the reuse of the regenerated glass fiber.

[0024] The method for recycling and preparing hard carbon negative electrode material provided by the application uses waste glass steel as raw material, which has a wide source, a negative composition (can collect garbage disposal fees), is suitable for large-scale production, and has great application potential. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a photo of the glass steel fiber powder after crushing in the embodiment of the application; Figure 2 It is a photo obtained after low-temperature pyrolysis in embodiment 1 of the application; Figure 3 It is a TEM photo of the carbon powder obtained after high-temperature carbonization in embodiment 1 of the application; Figure 4 It is an electrical performance test curve of the hard carbon obtained in embodiment 1 of the application. DETAILED DESCRIPTION

[0026] The application provides a method for recycling and preparing carbon from waste glass steel and an electrode material from the perspective of carbon recovery rate and environmental protection in the process of recycling resources from waste glass steel. The electrode material prepared by the process of the application has the advantages of excellent consistency, controllability, low ash content and high specific capacity, and the recycling process is environmentally friendly and has a high carbon recovery rate.

[0027] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a method for high-yield carbon recovery from waste fiberglass and the electrode materials proposed in this invention. The advantages and features of this invention will become clearer from the following description.

[0028] This invention provides a method for high-yield carbon recovery from waste fiberglass, wherein the waste fiberglass comprises a composite material obtained by combining glass fiber and resin, and the resin is a resin such as phenolic resin, epoxy resin or unsaturated polyester resin. Common fiberglass materials can be used for fan blades, reaction vessels, corrosion-resistant pipes or PCB boards, etc.

[0029] The method for recycling and preparing carbon includes the following steps: S1: The waste fiberglass is cut, coarsely crushed, and then crushed into particles with a diameter of 1-3mm. Considering the lower shear strength of fiberglass, it is preferable to crush it into fiberglass fibers with a diameter of 1-2mm and a length of 5-30mm (e.g., Figure 1 The crushed fiberglass powder reduces processing costs and improves 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 / 5-1 / 3 of its original volume, increasing the loading capacity of transport vehicles by 3-5 times and directly reducing logistics costs. The crushed particles 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 resin and fiber, promoting separation. Fiberglass is formed by the tight bonding of glass fibers and resin matrix through chemical bonds and mechanical interlocking, creating a three-dimensional network structure. 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.

[0030] S2: Pre-carbonize fiberglass powder by reacting it with acid: control the mass ratio of fiberglass powder to acid to be 1-5:1, the mass concentration of acid to be 10-100%, the specific reaction time to be 20-40 min, heat to 50-150℃, and stir at the same time.

[0031] According to conventional technology, pyrolysis of glass steel powder will produce gaseous overflow such as CO2, H2, CO, CH4, elemental carbon and tar, and the output of gas-liquid-solid three phases is about 1:1:1. The tar has high viscosity, and the production of a large amount of tar will paste the carbon powder and glass fiber, causing the carbon powder to be difficult to be stripped out.

[0032] The present application strictly controls the amount of acid. On the one hand, the acid has a dehydration function and can perform pre-carbonization to improve carbon recovery rate and greatly reduce the production of tar, which is beneficial to the subsequent separation of glass fiber powder and carbon powder; on the other hand, the acid dissolves the metal impurities in the glass steel.

[0033] The acid is selected from any one or any two or three or more of inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid.

[0034] S3: The pre-carbonized powder is subjected to low-temperature pyrolysis. Specifically, the pre-carbonized powder is treated at a temperature of 400-600°C for 2-5h under the protection of inert atmosphere, so that the pre-carbonized resin is fissioned into gaseous overflow such as CO2, H2, CO, CH4, elemental carbon and a small amount of tar under the action of high temperature, so as to achieve chemical separation of resin and glass fiber and prepare for subsequent physical separation.

[0035] S4: The powder after low-temperature pyrolysis is subjected to physical separation of carbon powder and glass fiber, for example, separation by specific gravity or electrical conductivity, such as common air separator, shaking table, electric separator, etc.

[0036] S5: The separated carbon powder is subjected to high-temperature carbonization: the separated carbon powder is treated at a high temperature of 800-1600°C for 2-6h under the protection of protective atmosphere.

[0037] S6: The carbon powder obtained by high-temperature carbonization is subjected to pair grinding or jet milling to obtain hard carbon powder with D50 of 5-7um.

[0038] The fibrous powder used in the following examples is: 2kg of fan blade is broken into fibrous powder with a diameter of 1-2mm and a length of 5-30mm by three steps of cutting, rough breaking and breaking, as shown in Figure 1 .

[0039] Example 1 Take 100 grams of broken fibrous powder; Mix the above fibrous powder with 100 grams of 20% sulfuric acid solution, and heat to 120°C while stirring mechanically at 200rpm; Take out the powder and put it into a tube furnace protected by argon for low-temperature pyrolysis at a temperature of 500°C for 3h; after natural cooling, take out the powder and grind it into a powder with D50 of 100um using a pair of roller mills, and the results are as follows Figure 2As shown in the figure, the carbon powder and glass fiber can be physically separated to obtain separate carbon powder and glass fiber; The reselection method was performed on a shaker to obtain carbon powder and glass fiber powder, and 28 g of carbon powder was obtained; The carbon powder was placed in an argon-protected atmosphere furnace and heated to 900°C at a heating rate of 5°C / min, and kept at 900°C for 2 hours to obtain hard carbon, which was taken out after natural cooling; The obtained hard carbon was pulverized by air jet mill, washed and dried to obtain hard carbon powder with D50 of 6um, and the results are shown in Figure 3 As shown in the figure, the carbon powder particle size distribution is uniform.

[0040] The carbon powder was used as the negative electrode material of sodium ion battery, and the electrochemical performance of the hard carbon material was studied, and the results are shown in Figure 4 As shown in the figure, the hard carbon negative electrode has high reversible capacity (the first cycle discharge specific capacity reaches 236mAh / g) and first cycle coulombic efficiency (84%).

[0041] Example 2 Take 100 grams of broken fibrous powder; Mix the above fibrous powder with 100 grams of 40% concentration phosphoric acid solution for 30 minutes, and heat to 120°C while mechanically stirring at 200 rpm; Take out the powder and put it into an argon-protected tube furnace for pre-carbonization at 600°C for 3 hours; after the powder is naturally cooled, it is ground into a powder with D50 of 100um, and the results are shown in Figure 2 As shown in the figure, the carbon powder and glass fiber can be physically separated to obtain separate carbon powder and glass fiber; The reselection method was performed on a shaker to obtain carbon powder and glass fiber powder, and 30 g of carbon powder was obtained; The carbon powder was placed in an argon-protected atmosphere furnace and heated to 1000°C at a heating rate of 5°C / min, and kept at 1000°C for 2 hours to obtain hard carbon, which was taken out after natural cooling; The obtained hard carbon was pulverized by air jet mill, washed and dried to obtain hard carbon powder with D50 of 6um.

[0042] Example 3 Take 100 grams of broken fibrous powder; Mix the above fibrous powder with 100 grams of 60% concentration sulfuric acid solution for 30 minutes, and mechanically stir at 200 rpm; The powder was removed and placed in an argon-protected tube furnace for pre-carbonization at 600°C for 3 hours. After natural cooling, the powder was removed and ground into powder with a D50 of 100 μm using a roller mill. The results are as follows. Figure 2 As shown in the figure, the toner and glass fiber can be separated into individual toner and glass fiber simply by physical separation. The carbon powder and glass fiber powder were separated by gravity separation on a shaker, yielding 36g of carbon powder. The carbon powder is placed in an argon-protected furnace and heated to 1600°C at a heating rate of 5°C / min. It is then held at 1600°C for 2 hours to obtain hard carbon, which is then removed after natural cooling. 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.

[0043] Comparative Example 1 Unlike Example 1, the step of mixing the fibrous powder with the sulfuric acid solution was omitted, while the other steps were the same, and 12g of carbon powder was obtained after separation.

[0044] Comparative Example 2 Unlike Example 1, 100g of fibrous powder was mixed with 200g of 98wt% sulfuric acid solution, and the other steps were the same. After separation, 16g of carbon powder was obtained.

[0045] 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 pre-carbonization with acid before pyrolysis can increase the carbon recovery rate. Compared with Comparative Example 2, Examples 1-3 show that controlling the amount of acid used for pre-carbonization is necessary to improve the carbon recovery rate.

[0046] 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 method for high yield recovery of carbon from scrap fiberglass composites, comprising: It comprises the following steps: S1: crushing waste glass steel into glass steel particles; S2: mixing and reacting the glass steel particles with acid to perform pre-carbonization; S3: performing low-temperature pyrolysis on the pre-carbonized powder; S4: separating the carbon powder and glass fiber after low-temperature pyrolysis to obtain carbon powder; The weight ratio of the glass steel powder to the acid is 1-5:1, and the mass concentration of the acid is 10-100%.

2. The method of claim 1, wherein the waste glass steel high recovery of carbon is characterized by, The acid in the step S2 is selected from any one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid.

3. The method of claim 1, wherein the waste glass steel has a carbon content of 0.1 wt% to 0.5 wt%. The low-temperature pyrolysis in the step S3 is specifically: treating the pre-carbonized powder under the protection of inert atmosphere at a temperature of 400-600℃ for 2-5h to decompose the product after the reaction of glass steel and acid.

4. The method of claim 1 or 3, wherein the waste glass steel is a fiber reinforced plastic. The separation in the step S4 utilizes the specific gravity or electrical conductivity of the carbon powder and glass fiber powder to separate them.

5. The method of claim 1, wherein the waste glass steel is a waste glass fiber reinforced plastic (GFRP) and the hard carbon is a hard carbon derived from waste GFRP. It further comprises a step S5 of performing high-temperature carbonization or activation on the obtained carbon powder.

6. The method of claim 5, wherein the waste glass steel high yield recovery carbon is characterized by, The high-temperature carbonization is: treating the separated carbon powder under the protection of inert atmosphere at a high temperature of 800-1600℃ for 2-6h.

7. The method of claim 5, wherein the waste glass steel has a carbon content of 0.1 wt% to 0.5 wt%. The activation is specifically: uniformly mixing the carbon powder obtained by pre-carbonization with KOH, NaOH, Na2CO3 or ZnCl2 powder according to a weight ratio of 1:1-5, treating under the protection of inert gas at a high temperature of 800-1000℃ for 1-3h to obtain porous carbon powder.

8. The method of claim 1, wherein the waste glass steel high yield recovery carbon is characterized by, The crushing step of the step S1 is: cutting, roughly breaking and crushing the waste glass steel to break the glass steel into fibrous powder with a diameter of 1-2mm and a length of 5-30mm.

9. The method of claim 1, wherein the waste glass steel high yield recovery carbon is characterized by, It further comprises: Performing pair grinding or air flow grinding on the carbon powder obtained by high-temperature carbonization to obtain hard carbon powder with a D50 of 5-7μm.

10. An electrode material, characterized by, The electrode material is obtained by the method for recycling carbon from waste glass steel with high yield according to any one of claims 1-9.

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