Regeneration method of retired blade glass fiber and regenerated glass fiber concrete reinforcing material

Abstract

The invention provides a regeneration method of retired blade glass fibers and a regenerated glass fiber concrete reinforcing material, and belongs to the technical field of green building materials and solid waste resource comprehensive utilization. By constructing an integrated intelligent equipment system of crushing and sorting, glass fiber regeneration and concrete production, the production cost of the regenerated glass fiber concrete reinforced material is reduced by 40% or above compared with that of a traditional process, and the economic threshold value of large-scale engineering application is reached; by adopting a three-stage regeneration technical chain of'multistage crushing pretreatment-two-stage catalytic pyrolysis-interface nano reinforcement ', the bottleneck of performance degradation of the thermosetting composite material regenerated glass fiber is broken through, and the mechanical property and pumping construction performance of the regenerated glass fiber concrete reinforced material are improved; the compressive strength of the regenerated glass fiber concrete reinforcing material reaches 65-82MPa in 28d, and meanwhile, the pumping construction performance with the slump of 180-220mm can be kept.

Description

Technical Field

[0001] The present invention relates to the technical field of green building materials and comprehensive utilization of solid waste resources, and particularly relates to a regeneration method for glass fiber of retired blades and a regenerated glass fiber concrete reinforcing material. Background Art

[0002] The current regenerated glass fiber concrete reinforcing material system mainly relies on traditional glass fiber (E-glass), steel glass fiber, and polypropylene (PP) / polyethylene (PE) synthetic glass fiber, etc. According to statistics, the annual output of glass fiber exceeds 10 million tons. Its production process requires high-energy-consuming processes such as high-temperature melting above 1500 °C and wire drawing with a platinum-rhodium alloy leakage plate. The comprehensive energy consumption per unit product reaches 1.2 - 1.8 tons of standard coal / ton, and the carbon emission intensity is 2.5 - 3.5 tons of CO2 / ton, causing serious pollution to the environment.

[0003] At the same time, the disposal problem of glass fiber composites (GFRP) in retired wind turbine blades in the wind power industry is becoming increasingly severe. The cumulative amount of retired blades has exceeded 1 million tons. The thermosetting resin matrix (such as epoxy resin and unsaturated polyester) in the retired blades is difficult to degrade. The current treatment technologies mainly include simple landfill (accounting for about 65%) or incineration for power generation (accounting for about 30%). This not only causes waste of resources of glass fiber (with a content of 60 - 75%), but also releases pollutants such as dioxins and nitrogen oxides during the incineration process, causing serious pollution to the environment. Therefore, how to produce glass fiber from retired wind turbine blades in the wind power industry has received great attention.

[0004] However, due to the irreversible cross-linked structure of the thermosetting resin in GFRP of retired blades, the conventional mechanical crushing method can only obtain inferior fibers with a length < 3 mm and a surface resin residue > 20% (the tensile strength decays to 30 - 40% of the original fiber), which cannot meet the mechanical indexes of the reinforcing material. Although the pyrolysis method (i.e., thermal cracking at a temperature of 500 - 600 °C) can recycle fibers, there are problems such as high energy consumption (> 3000 MJ / ton) and fiber oxidation embrittlement, and the resin decomposition products need to be subjected to additional purification treatment. At the same time, even if the fibers are recycled, after the recycled glass fibers are used in concrete, there are also problems such as poor fiber-cement matrix interfacial compatibility and uneven fiber dispersion, resulting in insufficient anti-cracking and strengthening efficiency of the concrete (crack inhibition rate < 30%), and fiber pull-out failure is likely to occur during long-term service.

[0005] Therefore, with the continuous growth of the demand for green and high-performance building materials in the construction industry, as well as the disposal problem of retired wind turbine blades faced by the wind power industry, providing a regeneration method for glass fiber of retired blades and a regenerated glass fiber concrete reinforcing material has become an urgent technical problem in this field. Summary of the Invention

[0006] The object of the present invention is to provide a regeneration method for glass fibers of retired blades and a regenerated glass fiber concrete reinforcing material. The regeneration method provided by the present invention can not only solve the problem of wind power solid waste, but also provide a regenerated glass fiber concrete reinforcing material with low cost and high performance, and has great application demands in the building material market and the waste treatment market of the wind power industry.

[0007] In order to achieve the above object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a regeneration method for glass fibers of retired blades, comprising the following steps:

[0009] (1) Perform multi-stage crushing pretreatment on the retired blades to obtain glass fiber bundles;

[0010] (2) Mix the glass fiber bundles obtained in the step (1) with a catalyst and perform two-stage catalytic pyrolysis to obtain glass fibers; the two-stage catalytic pyrolysis is: first keep the temperature at 250-320 °C for 20-60 min, and then keep the temperature at 380-420 °C for 1-5 h;

[0011] (3) Perform fiber strengthening regeneration on the glass fibers obtained in the step (2) to obtain regenerated glass fibers; the fiber strengthening regeneration is a combined process of microwave-assisted acid etching and plasma surface activation.

[0012] Preferably, the multi-stage crushing pretreatment in the step (1) includes primary shredding, secondary crushing and sorting performed in sequence.

[0013] Preferably, the sorting is a combination of eddy current sorting and electrostatic sorting.

[0014] Preferably, the catalyst in the step (2) is a Ni / Al2O3 catalyst, and the mass of the catalyst is 8-12% of the total mass of the glass fiber bundles and the catalyst.

[0015] Preferably, the atmosphere of the two-stage catalytic pyrolysis in the step (2) is an inert atmosphere.

[0016] Preferably, the acid used in the microwave-assisted acid etching in the step (3) is a nitric acid solution; the concentration of the nitric acid solution is 0.3-0.7 mol / L.

[0017] Preferably, the temperature of the microwave-assisted acid etching in the step (3) is 70-90 °C, and the power of the microwave-assisted acid etching is 200-400 W.

[0018] Preferably, the method of plasma surface activation in the step (3) is: impregnate the glass fibers after microwave-assisted acid etching in a silane coupling agent solution, and then perform heat treatment.

[0019] The present invention provides recycled glass fibers obtained by the recycling method described in the above technical solution. The length of the recycled glass fibers is 12 - 18 mm, and the diameter of the recycled glass fibers is 13 - 17 μm.

[0020] The present invention provides a recycled glass fiber concrete reinforcing material. The preparation method of the recycled glass fiber concrete reinforcing material includes: dry - mixing recycled glass fibers, aggregates and cement, and then adding water for wet - mixing to obtain the recycled glass fiber concrete reinforcing material; the recycled glass fibers are the recycled glass fibers described in the above technical solution.

[0021] The present invention provides a recycling method for glass fibers of retired blades, which includes the following steps: (1) performing multi - stage crushing pretreatment on the retired blades to obtain glass fiber bundles; (2) mixing the glass fiber bundles obtained in step (1) with a catalyst and performing two - stage catalytic pyrolysis to obtain glass fibers; the two - stage catalytic pyrolysis is: first, keeping the temperature at 250 - 320 °C for 20 - 60 min, and then keeping the temperature at 380 - 420 °C for 1 - 5 h; (3) performing fiber strengthening and recycling on the glass fibers obtained in step (2) to obtain recycled glass fibers; the fiber strengthening and recycling is a combined process of microwave - assisted acid etching and plasma surface activation. By means of multi - stage crushing pretreatment, the present invention can avoid causing excessive damage to the integrity of the glass fiber bundles, obtain glass fiber bundles with a high integrity rate, improve the recycling effect, and lay a foundation for subsequent catalytic pyrolysis and fiber strengthening and recycling; through two - stage catalytic pyrolysis, epoxy resin chain scission and depolymerization are achieved at a temperature of 250 - 320 °C, and deep decomposition of benzoxazine resin is completed at a temperature of 380 - 420 °C, thereby reducing the emission of toxic gases and avoiding environmental pollution caused by waste gas; by adopting a combined process of microwave - assisted acid etching and plasma surface activation for fiber strengthening and recycling, the surface performance of the glass fibers can be significantly improved, which is beneficial to improving the fiber - cement matrix interfacial compatibility and further improving the performance of the recycled glass fiber concrete reinforcing material.

[0022] The present invention constructs an integrated intelligent equipment system of "crushing and sorting - glass fiber regeneration - concrete production", reducing the production cost of recycled glass fiber concrete reinforcing materials by more than 40% compared with traditional processes, reaching the economic threshold for large-scale engineering applications; by adopting a three-stage regeneration technology chain of "multi-stage crushing pretreatment - two-stage catalytic pyrolysis - interfacial nano-enhancement", it breaks through the bottleneck of deteriorated performance of recycled glass fiber in thermosetting composites and improves the mechanical properties and pumping construction performance of recycled glass fiber concrete reinforcing materials. The results of the examples show that the recycled glass fiber concrete reinforcing materials prepared from the recycled glass fiber provided by the present invention have a 28-day compressive strength of 65 - 82 MPa (GB / T50081 standard), and at the same time can maintain a pumping construction performance with a slump of 180 - 220 mm.

[0023] The present invention realizes for the first time the closed-loop conversion from wind power solid waste to high-performance recycled glass fiber concrete reinforcing materials. While solving the problem of storage pollution of ten thousand tons of GFRP, it provides an innovative solution for the synergistic improvement of the crack resistance (crack width control ≤ 0.1 mm), toughness (flexural toughness index η 30 ≥ 4.5) and durability (carbonation depth < 3 mm / year) of concrete materials, and has the dual advantages of environmental attributes and mechanical properties in the "Technical Requirements for Green Building Materials Product Certification", which is of strategic significance for promoting the green collaborative development of the construction and wind power industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the physical flow chart for preparing glass fiber bundles in Example 1 of the present invention;

[0025] Figure 2 It is the physical flow chart for preparing recycled glass fiber in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention provides a method for recycling glass fiber from retired blades, comprising the following steps:

[0027] (1) Conduct multi-stage crushing pretreatment on the retired blades to obtain glass fiber bundles;

[0028] (2) Mix the glass fiber bundles obtained in step (1) with a catalyst and perform two-stage catalytic pyrolysis to obtain glass fiber; the two-stage catalytic pyrolysis is: first keep the temperature at 250 - 320 °C for 20 - 60 min, and then keep the temperature at 380 - 420 °C for 1 - 5 h;

[0029] (3) Perform fiber strengthening regeneration on the glass fiber obtained in step (2) to obtain recycled glass fiber; the fiber strengthening regeneration is a combined process of microwave-assisted acid etching and plasma surface activation.

[0030] The present invention performs multi-stage crushing pretreatment on retired blades to obtain glass fiber bundles.

[0031] The present invention has no special limitation on the specific source of the retired blades, and the retired blades well-known to those skilled in the art can be used. As an implementation mode of the present invention, the retired blades can be retired wind turbine blades; the retired wind turbine blades can be 1.5MW wind turbine blades; the glass fiber content of the 1.5MW wind turbine blades is 68wt%.

[0032] In the present invention, the multi-stage crushing pretreatment includes primary shredding, secondary crushing, and sorting performed in sequence.

[0033] In the present invention, the primary shredding is preferably performed using a jaw crusher; the size of the product of the primary shredding is preferably 50-100mm.

[0034] In the present invention, the secondary crushing is preferably performed using an impact crusher; the size of the product of the secondary crushing is preferably 10-20mm.

[0035] Through the two-stage crushing treatment of the present invention, the size of the retired blades can be gradually refined, and the integrity rate of the glass fiber bundles is guaranteed to be ≥90% in this process, thereby improving the recovery rate of the glass fiber bundles.

[0036] In the present invention, the sorting is preferably a combination of eddy current sorting and electrostatic sorting. The present invention has no special limitation on the specific operations of the eddy current sorting and electrostatic sorting, and the processes of eddy current sorting and electrostatic sorting well-known to those skilled in the art can be used. In the present invention, the sorting can be eddy current sorting first, and then electrostatic sorting. Through the above sorting process of the present invention, the removal rate of metal inserts (bolts, wires, etc.) can be >99.5%, thereby obtaining the required glass fiber bundles.

[0037] In the present invention, the integrity rate of the glass fiber bundles is preferably ≥90%.

[0038] After obtaining the glass fiber bundles, the present invention mixes the glass fiber bundles and a catalyst and then performs two-stage catalytic pyrolysis to obtain glass fibers.

[0039] In the present invention, the catalyst is preferably a Ni / Al2O3 catalyst. In the present invention, the mass of the catalyst is preferably 8-12% of the total mass of the glass fiber bundles and the catalyst, more preferably 9-11%, and further preferably 10%. By controlling the type and dosage of the catalyst, the present invention can fully decompose the epoxy resin and benzoxazine resin in the glass fiber bundles.

[0040] In the present invention, the two-stage catalytic pyrolysis is as follows: first, keep the temperature at 250 - 320 °C for 20 - 60 min, and then keep the temperature at 380 - 420 °C for 1 - 5 h. Preferably, first keep the temperature at 250 - 300 °C for 30 - 40 min, and then keep the temperature at 400 °C for 2 - 3 h. Through the two-stage catalytic pyrolysis, the present invention realizes the chain scission and depolymerization of epoxy resin at a temperature of 250 - 320 °C, and completes the deep decomposition of benzoxazine resin at a temperature of 380 - 420 °C, thereby reducing the emission of toxic gases and avoiding environmental pollution caused by waste gas.

[0041] In the present invention, the atmosphere of the two-stage catalytic pyrolysis is preferably an inert atmosphere, more preferably nitrogen with a purity ≥ 99.99%. By carrying out the two-stage catalytic pyrolysis in an inert atmosphere, the present invention can avoid the occurrence of redox reactions.

[0042] In the present invention, the pyrolysis gas generated by the two-stage catalytic pyrolysis is preferably converted into aromatic oil through catalytic reforming; the catalyst used for the catalytic reforming is preferably HZSM-5 molecular sieve; the mass of the catalyst is preferably 10 - 20% of the mass of the glass fiber bundle, more preferably 15%; the yield of the aromatic oil ≥ 75%. By catalytically reforming the pyrolysis gas, the present invention not only reduces the emission of waste gas, but also realizes the high-value utilization of the pyrolysis gas, which is beneficial to the sustainable utilization of resources.

[0043] In the present invention, the surface residual carbon of the glass fiber is preferably < 3%. The glass fiber obtained in the present invention has a low surface residual carbon content and good quality.

[0044] After obtaining the glass fiber, the present invention performs fiber strengthening and regeneration on the glass fiber to obtain regenerated glass fiber.

[0045] In the present invention, the fiber strengthening and regeneration is a combined process of microwave-assisted acid etching and plasma surface activation, preferably microwave-assisted acid etching and plasma surface activation carried out in sequence.

[0046] In the present invention, the acid used for the microwave-assisted acid etching is preferably nitric acid solution; the concentration of the nitric acid solution is preferably 0.3 - 0.7 mol / L, more preferably 0.4 - 0.6 mol / L, and further preferably 0.5 mol / L; the temperature of the microwave-assisted acid etching is preferably 70 - 90 °C, more preferably 75 - 85 °C, and further preferably 80 °C; the power of the microwave-assisted acid etching is preferably 200 - 400 W, more preferably 250 - 350 W, and further preferably 300 W.

[0047] In the present invention, the method of plasma surface activation is: impregnate the glass fiber after microwave-assisted acid etching in a silane coupling agent solution, and then perform heat treatment.

[0048] In the present invention, the silane coupling agent in the silane coupling agent solution is preferably silane coupling agent KH-550; the concentration of the silane coupling agent solution is preferably 2-4 wt%, more preferably 3 wt%; the solvent in the silane coupling agent solution is preferably a mixed solvent of ethanol and water; the volume ratio of ethanol to water is preferably 9:1-5:5, more preferably 8:2-6:4, and further preferably 7:3; the pH of the silane coupling agent solution is preferably 4-5, more preferably 4.5. In the present invention, the temperature of the impregnation is preferably 50-80 °C, more preferably 60 °C; the time of the impregnation is preferably 1-3 h, more preferably 2 h. By using the above silane coupling agent solution for impregnation, the present invention can improve the surface modification effect on glass fibers.

[0049] In the present invention, the temperature of the heat treatment is preferably 100-150 °C, more preferably 120-130 °C; the time of the heat treatment is preferably 0.5-2 h, more preferably 1 h. In the present invention, the atmosphere of the heat treatment is preferably a mixed gas of argon and oxygen; the volume ratio of argon to oxygen is preferably 8:2-9:1, more preferably 9:1. By heat treatment, the present invention can form a chemical bonding interface on the surface of glass fibers.

[0050] By adopting the combined process of microwave-assisted acid etching and plasma surface activation for fiber strengthening and regeneration, the present invention can remove microcracks on glass fibers and generate nano-scale groove structures, enabling the tensile strength of the regenerated glass fibers to reach 1.8-2.4 GPa (ASTM D2343 standard), achieving 85-92% of the performance of aviation-grade E-glass fibers.

[0051] The present invention provides the regenerated glass fibers obtained by the regeneration method of the above technical solution.

[0052] In the present invention, the length of the regenerated glass fibers is 12-18 mm; the diameter of the regenerated glass fibers is 13-17 μm. By controlling the size of the regenerated glass fibers, the present invention can further improve the mechanical properties and pumping construction performance of the regenerated glass fiber-reinforced concrete materials.

[0053] In the present invention, when the length of the regenerated glass fibers does not meet the above requirements, the present invention preferably cuts the regenerated glass fibers. The present invention has no special limitation on the specific operation of the cutting, and it can be cut using a cutting machine.

[0054] The present invention provides a regenerated glass fiber concrete reinforcing material. The preparation method of the regenerated glass fiber concrete reinforcing material includes: dry-mixing regenerated glass fibers, aggregates, and cement, and then adding water for wet-mixing to obtain the regenerated glass fiber concrete reinforcing material; the regenerated glass fibers are the regenerated glass fibers described in the above technical solution.

[0055] In the present invention, the dosage of the regenerated glass fibers in the regenerated glass fiber concrete reinforcing material is preferably 0.6-1.5 wt%, more preferably 1.2-1.5 wt%. By controlling the dosage of the regenerated glass fibers, the mechanical properties and pumping construction performance of the regenerated glass fiber concrete reinforcing material can be further improved.

[0056] In the present invention, the cement is preferably P·O42.5 cement; the aggregates preferably include sand and gravel and Class I fly ash; the dosage of sand and gravel in the regenerated glass fiber concrete reinforcing material is preferably 30-45 wt.%, more preferably 35-40 wt.%, and further preferably 38 wt.%; the dosage of Class I fly ash in the regenerated glass fiber concrete reinforcing material is preferably 15-25 wt%, more preferably 20 wt%.

[0057] In the present invention, the regenerated glass fiber concrete reinforcing material preferably further includes nanoparticles and a superplasticizer. In the present invention, the nanoparticles are preferably nano-calcium carbonate; the dosage of the nanoparticles in the regenerated glass fiber concrete reinforcing material is preferably 1-2 wt%, more preferably 1.5 wt%; the superplasticizer is preferably a polycarboxylate-based water reducer; the water reduction rate of the polycarboxylate-based water reducer is preferably ≥30%; the dosage of the superplasticizer is preferably 5-15 kg / m 3 ,more preferably 10 kg / m 3 。In the present invention, the nanoparticles and the superplasticizer are preferably dry-mixed with the raw glass fibers, aggregates, and cement. By adding the nanoparticles and the superplasticizer, the mechanical properties of the regenerated glass fiber concrete reinforcing material can be further improved.

[0058] The present invention has no special limitation on the amount of water used, as long as the water-binder ratio meets the requirements. In the present invention, the water-binder ratio is preferably 0.45-0.5, more preferably 0.48%. By controlling the water-binder ratio, the concentration of the slurry can be controlled, so that it has good pumping construction performance.

[0059] In the present invention, the time for dry-mixing is preferably 30-120 s, more preferably 60-90 s; the time for wet-mixing is preferably 90-180 s, more preferably 120-150 s. By the above mixing method, the uniformity index (CV value) of the dispersion of the regenerated glass fibers can be ≤8%, thereby further improving its mechanical properties.

[0060] The present invention preferably vibrates and compacts and cures the product of wet mixing in sequence after the wet mixing is completed.

[0061] In the present invention, the frequency of the vibration compaction is preferably 40 - 70 Hz, more preferably 50 - 60 Hz; the time of the vibration compaction is preferably 30 - 120 s, more preferably 60 - 90 s; the equipment for the vibration compaction is preferably a vibrating table. The present invention has no special requirements on the specific model and source of the vibrating table, and a vibrating table well-known to those skilled in the art can be used. By performing vibration compaction after wet mixing, the present invention can remove impurities such as air bubbles introduced during the wet mixing process, thereby improving the density and further improving the mechanical properties of the recycled glass fiber concrete reinforcing material.

[0062] In the present invention, the temperature of the curing is preferably 20 ± 2 °C; the humidity of the curing is preferably RH ≥ 95%; the time of the curing is preferably 28 d. By curing, the present invention can promote the progress of the hydration reaction and improve the mechanical properties of the recycled glass fiber concrete reinforcing material.

[0063] By adopting a three-stage regeneration technology chain of "multistage crushing pretreatment - two-stage catalytic pyrolysis - interfacial nano-reinforcement", the present invention breaks through the bottleneck of deteriorated properties of recycled glass fiber in thermosetting composites, and improves the mechanical properties and pumping construction performance of the recycled glass fiber concrete reinforcing material; by constructing an integrated intelligent equipment system of "crushing and separation - glass fiber regeneration - concrete production", the production cost of the recycled glass fiber concrete reinforcing material is reduced by more than 40% compared with the traditional process, reaching the economic threshold for large-scale engineering applications. Through the ternary synergistic effect of "recycled glass fiber - nano-particle - hydration product", the 28-day compressive strength of the recycled glass fiber concrete reinforcing material reaches 65 - 82 MPa (GB / T50081 standard), and at the same time, the pumping construction performance with a slump of 180 - 220 mm can be maintained.

[0064] The present invention realizes for the first time the closed-loop conversion from wind power solid waste to high-performance recycled glass fiber concrete reinforcing material. While solving the problem of storage pollution of ten thousand tons of GFRP, it provides an innovative solution for the synergistic improvement of the crack resistance (crack width control ≤ 0.1 mm), toughness (flexural toughness index η 30 ≥ 4.5) and durability (carbonation depth < 3 mm / year) of concrete materials, and has dual advantages of environmental attributes and mechanical properties in the "Technical Requirements for Green Building Materials Product Certification", which has strategic significance for promoting the green and coordinated development of the building and wind power industries.

[0065] The present invention realizes the cross-field coordination between the solid waste at the end of the wind power industrial chain and the raw materials at the front end of the building materials industry, and provides a solution with both environmental and economic benefits for the green and high-performance of concrete materials.

[0066] The method for regenerating retired blade glass fiber in concrete provided by the present invention has the following advantages:

[0067] (I) Breakthrough in environmental benefits, building a new model for full resource utilization of wind power solid waste:

[0068] Solid waste reduction effect: The present invention uses a closed-loop recycling process to make the comprehensive utilization rate of GFRP in retired fan blades ≥ 95wt%, reducing the amount of solid waste generated by 2.3 to 3.8 tons per ton of blades compared with traditional landfill / incineration methods;

[0069] Pollution prevention and control efficiency: The present invention adopts two-stage catalytic pyrolysis to inhibit the generation of persistent organic pollutants such as dioxins (emission concentration <0.1ngTEQ / m 3 , better than the standard limit of GB18484-2020), and through the catalytic reforming process of resin decomposition products, the resource utilization rate of organic components is greater than 85%;

[0070] Contribution to carbon emission reduction: The carbon footprint analysis of the entire life cycle shows that the recycled glass fiber production process obtained by the method provided by the present invention can reduce CO2 emissions by 4.2 to 5.6 tons / ton (ISO14067 standard) compared with virgin glass fiber, and can reduce carbon emission intensity by 62 to 68% (ISO14044 standard) compared with traditional glass fiber reinforced concrete, and the unit product energy consumption is reduced by 55 to 70%. If calculated based on the annual processing of 100,000 tons of retired blades, the annual carbon emission reduction potential is 420,000 to 560,000 tons, which is equivalent to an additional 35,000 to 47,000 hectares of forest carbon sink capacity, which completely reverses the industry's perception that "high performance must have high cost" of recycled materials and promotes the concrete industry to upgrade towards "zero waste and negative carbonization".

[0071] (II) Material performance has leapt forward, improving the technical indicators of recycled glass fiber concrete reinforcement materials:

[0072] Strengthening of mechanical properties: The recycled glass fiber provided by the present invention has a multi-level interface optimization design, so that the tensile strength of the recycled glass fiber concrete reinforced material at 28d reaches 65-82MPa (18-32% higher than the benchmark group), the ultimate bending load is increased by 25-40%, and the mass loss rate of the recycled glass fiber concrete reinforced material after 300 freeze-thaw cycles is less than 1.5% (GB / T50082-2009 standard);

[0073] Durability innovation: This invention can reduce the chloride ion diffusion coefficient of recycled glass fiber concrete reinforcement material to 1.8×10 -12 m 2 / s (55 - 65% lower than ordinary concrete), with the carbonation depth controlled at 0.8 - 1.2 mm / year, thus extending the structural service life of the recycled glass fiber concrete reinforcement material to over 80 years in a marine environment.

[0074] (III) Economic restructuring, opening up a new path for low-cost and high-performance materials:

[0075] Raw material cost advantage: The method provided by the present invention enables the comprehensive production cost of recycled glass fiber to be controlled within 3200 - 4500 yuan / ton, which is only 40 - 55% of that of virgin glass fiber (8000 - 12000 yuan / ton). The depolymerization catalyst has a high recycling rate (loss rate < 3%), and 30% of the value-added tax on comprehensive utilization of resources can be deducted;

[0076] Engineering cost reduction benefit: Taking C40 concrete as an example, adding 0.5% recycled glass fiber can reduce the unit material cost by 12 - 18 yuan, while reducing the crack repair cost by 30 - 50%, and the comprehensive cost over the entire life cycle decreases by 20 - 28%;

[0077] Industrial chain value addition: Relying on the integration of the value chain of "retired blade recycling - glass fiber recycling - building material production", new industrial profit points are created. It is estimated that by 2030, a market for recycled glass fiber concrete reinforcement materials worth 80 - 120 billion yuan / year can be formed (data from Global Market Insights).

[0078] (IV) Process universality innovation, realizing large-scale industrial application:

[0079] Process compatibility: The method provided by the present invention can be adapted to existing building material production lines within 72 hours through modular recycling equipment (processing capacity 5 - 20 tons / h) and in-situ addition technology for concrete mixing plants, and the equipment payback period < 2 years;

[0080] Process stability: The method provided by the present invention can achieve controllable performance of the recycled glass fiber content within the range of 0.3 - 1.5% through an on-line monitoring system for glass fiber surface activation (based on near-infrared spectroscopy) and an intelligent concrete mixing control system (error rate < ±1.5%);

[0081] Standard system support: The technical parameters of the recycled glass fiber concrete reinforcement material provided by the present invention are fully compatible with industry standards such as JG / T 472 - 2015 "Steel Fiber Reinforced Concrete" and CCPA "Technical Specification for the Application of Glass Fiber Reinforced Concrete". It has completed demonstration applications in 6 types of projects such as coastal flood protection dikes and prefabricated buildings (cumulative usage > 50000 m 3 ), and has obtained the green building material certification (three-star level) from the Ministry of Housing and Urban-Rural Development.

[0082] (V) Technical transformation value:

[0083] The present invention breaks through the limitations of the traditional solid waste utilization technology of "low value and fragmentation". With recycled glass fiber as the core medium, it realizes the industrial closed-loop of "retired blades - material regeneration - engineering application", achieving triple leaps in environmental benefits (more than 90% reduction in solid waste), engineering performance (more than 30% increase in strength), and economic value (more than 40% reduction in cost), providing a replicable technical template for the construction of new building industrialization and "waste-free cities".

[0084] The following will clearly and completely describe the technical solutions in the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0085] Example 1

[0086] A method for recycling glass fiber from retired blades comprises the following steps:

[0087] (1) Perform multi-stage crushing pretreatment on retired 1.5MW wind turbine blades (GFRP, with a glass fiber content of 68wt%). First, use a jaw crusher for primary shredding to make the size 50 - 100mm, then use an impact crusher for secondary crushing to make the size 10 - 20mm, and finally use a combination of eddy current separation and electrostatic separation for sorting to obtain glass fiber bundles with a integrity rate of ≥90% and an Fe content of <0.3%;

[0088] (2) Mix the glass fiber bundles obtained in step (1) with a catalyst and perform two-stage catalytic pyrolysis to obtain glass fibers with a surface residual carbon content of <3%. The catalyst is a Ni / Al2O3 catalyst, and the mass of the catalyst is 10% of the total mass of the glass fiber bundles and the catalyst. The two-stage catalytic pyrolysis is as follows: First, keep it at 250°C for 30 minutes in nitrogen with a purity of ≥99.99%, and then keep it at 400°C for 2 hours. The pyrolysis gas generated by the two-stage catalytic pyrolysis is catalytically reformed into aromatic oil, and the catalyst used for catalytic reforming is HZSM-5 molecular sieve, and the mass of the HZSM-5 molecular sieve is 15% of the mass of the glass fiber bundles;

[0089] (3) Fiber-reinforced regeneration is carried out on the glass fiber obtained in the step (2) to obtain regenerated glass fiber; the fiber-reinforced regeneration is a combined process of microwave-assisted acid etching and plasma surface activation; the microwave-assisted acid etching uses a nitric acid solution with a concentration of 0.5 mol / L, the temperature of the microwave-assisted acid etching is 80 °C, and the power of the microwave-assisted acid etching is 300 W; the atmosphere of the plasma surface activation is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 9:1. The specific method is: immerse the glass fiber after microwave-assisted acid etching in a 3 wt% silane coupling agent KH-550 solution (pH = 4.5, and the solvent is ethanol / water with a volume ratio of 7:3), take it out after reacting at 60 °C for 2 h, and perform heat treatment at 120 °C for 1 h to form a chemical bonding interface.

[0090] The regenerated glass fiber concrete reinforcement material prepared by using the above regenerated glass fiber, the preparation method is: mix the regenerated glass fiber, cement (P·O42.5, 340 kg / m 3 ) and aggregate, and then perform dry mixing for 60 s, then add water (control the water-binder ratio to be 0.48) for wet mixing for 120 s, control the slump to be 160 ± 20 mm, then use a vibrating table for compaction (frequency 50 Hz, time 60 s), and finally cure for 28 d under the conditions of 20 ± 2 °C and humidity RH ≥ 95% to obtain the regenerated glass fiber concrete reinforcement material; the aggregate is sand and gravel and Class I fly ash, the content of sand and gravel in the regenerated glass fiber concrete reinforcement material is 38 wt.%, and the content of Class I fly ash is 20 wt.%; the length of the regenerated glass fiber is 12 - 18 mm, the diameter of the regenerated glass fiber is 13 - 17 μm, and the content of the regenerated glass fiber in the regenerated glass fiber concrete reinforcement material is 1.5 wt%.

[0091] The physical flow chart of preparing the glass fiber bundle in Example 1 of the present invention is as Figure 1 shown. From Figure 1 it can be seen that after the retired wind turbine blade is broken multiple times, a fiber bundle with a high integrity rate is obtained, and at the same time, metal inserts (bolts, wires, etc.) have been basically removed.

[0092] The physical flow chart of preparing the regenerated glass fiber in Example 1 of the present invention is as Figure 2 shown. From Figure 2 it can be seen that after the retired wind turbine blade is processed by the three-stage regeneration technology chain of "multi-stage crushing pretreatment - two-stage catalytic pyrolysis - interfacial nano-enhancement", the regenerated glass fiber can have good surface structure and performance. After testing, the tensile strength of the regenerated glass fiber reaches 1.8 - 2.4 GPa (ASTM D2343 standard), reaching 85 - 92% of the performance of aviation-grade E-glass fiber.

[0093] The performance of the recycled glass fiber concrete reinforcing material obtained in Example 1 was tested according to the GB / T50081-2019 standard. The compressive strength of the recycled glass fiber concrete reinforcing material was 66.7 MPa, and the data dispersion coefficient CV = 3.2%; the splitting tensile strength of the recycled glass fiber concrete reinforcing material was 4.1 MPa; Flexural toughness: Through a three-point bending test, the residual strengths were fR1 = 5.8 MPa and fR3 = 4.2 MPa, and the toughness index η 30 = 5.6 (meeting the requirements of FRC III grade).

[0094] Comparative Example 1

[0095] C30 concrete was designed according to the GB / T50081-2019 standard. Cement (P·O42.5, 340 kg / m 3 ) and aggregates were mixed dry for 60 s, then water was added (controlling the water-binder ratio to 0.48) and wet mixed for 120 s. The slump was controlled to be 160 ± 20 mm, and then it was compacted using a vibrating table (frequency 50 Hz, time 60 s). Finally, it was cured for 28 d under the conditions of 20 ± 2 °C and humidity RH≥95%, obtaining concrete; the aggregates were sand, gravel and class I fly ash, and the dosage of sand and gravel in the concrete was 38 wt.%, and the dosage of class I fly ash was 20 wt.%;

[0096] The performance of the concrete obtained in Comparative Example 1 was tested according to the GB / T50081-2019 standard. The compressive strength of the concrete was 34.5 MPa, and the splitting tensile strength was 3.3 MPa.

[0097] It can be seen from the comparison between Example 1 and Comparative Example 1 that after adding the recycled glass fiber provided by the present invention, the compressive strength and splitting tensile strength of the concrete have been significantly improved compared with the reference group, indicating that the solution provided by the present invention can effectively improve the mechanical properties of the concrete.

[0098] Example 2

[0099] A method for recycling waste blade glass fiber, comprising the following steps:

[0100] (1) Perform multi-stage crushing pretreatment on waste 1.5 MW wind turbine blades (GFRP, glass fiber content is 68 wt%). First, use a jaw crusher for primary shredding to make the size 50-100 mm, then use an impact crusher for secondary crushing to make the size 10-20 mm, and finally use a combination of eddy current separation and electrostatic separation for separation to obtain glass fiber bundles, with the integrity rate of the glass fiber bundles ≥90% and the Fe content <0.3%;

[0101] (2) Mix the glass fiber bundle obtained in step (1) with a catalyst and perform two-stage catalytic pyrolysis to obtain glass fibers, with the residual carbon on the surface of the glass fibers < 3%; the catalyst is a Ni / Al₂O₃ catalyst, and the mass of the catalyst is 10% of the total mass of the glass fiber bundle and the catalyst; the two-stage catalytic pyrolysis is as follows: keep it at 280 °C for 30 min in nitrogen with a purity ≥ 99.99%, and then keep it at 400 °C for 2 h; the pyrolysis gas generated by the two-stage catalytic pyrolysis is catalytically reformed into aromatic oil, and the catalyst used for catalytic reforming is HZSM-5 molecular sieve, and the mass of the HZSM-5 molecular sieve is 15% of the mass of the glass fiber bundle;

[0102] (3) Perform fiber-reinforced regeneration on the glass fibers obtained in step (2) to obtain regenerated glass fibers; the fiber-reinforced regeneration is a combined process of microwave-assisted acid etching and plasma surface activation; the microwave-assisted acid etching uses a nitric acid solution with a concentration of 0.5 mol / L, the temperature of the microwave-assisted acid etching is 80 °C, and the power of the microwave-assisted acid etching is 300 W; the atmosphere of the plasma surface activation is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 9:1. The specific method is: immerse the glass fibers after microwave-assisted acid etching in a 3 wt% silane coupling agent KH-550 solution (pH = 4.5, and the solvent is ethanol / water = 7:3 by volume ratio), take them out after reacting at 60 °C for 2 h, and perform heat treatment at 120 °C for 1 h to form a chemical bonding interface.

[0103] The regenerated glass fiber concrete reinforcing material prepared by using the above regenerated glass fibers, the preparation method is: mix the regenerated glass fibers, cement (P·O 42.5, 340 kg / m 3 ) and aggregates, and perform dry mixing for 60 s, then add water (control the water-binder ratio to be 0.48) and perform wet mixing for 120 s, control the slump to be 160 ± 20 mm, then use a vibrating table to compact (frequency 50 Hz, time 60 s), and finally cure for 28 d under the conditions of 20 ± 2 °C and humidity RH ≥ 95% to obtain the regenerated glass fiber concrete reinforcing material; the aggregates are sand, gravel and class I fly ash, the dosage of sand and gravel in the regenerated glass fiber concrete reinforcing material is 38 wt.%, and the dosage of class I fly ash is 20 wt.%; the length of the regenerated glass fibers is 12 - 18 mm, the diameter of the regenerated glass fibers is 13 - 17 μm, and the dosage of the regenerated glass fibers in the regenerated glass fiber concrete reinforcing material is 1.2 wt%.

[0104] Example 3

[0105] A method for regenerating waste blade glass fibers, which is the following steps:

[0106] (1) The retired 1.5 MW wind turbine blades (GFRP, with a glass fiber content of 68 wt%) are subjected to multi-stage crushing pretreatment. First, a jaw crusher is used for primary shredding to make the size 50 - 100 mm. Then, an impact crusher is used for secondary crushing to make the size 10 - 20 mm. Finally, a combination of eddy current separation and electrostatic separation is used for separation to obtain glass fiber bundles with a integrity rate of ≥90% and an Fe content of <0.3%;

[0107] (2) The glass fiber bundles obtained in the step (1) and a catalyst are mixed and then subjected to two-stage catalytic pyrolysis to obtain glass fibers with a surface residual carbon content of <3%. The catalyst is a Ni / Al2O3 catalyst, and the mass of the catalyst is 10% of the total mass of the glass fiber bundles and the catalyst. The two-stage catalytic pyrolysis is as follows: First, it is kept at 280 °C for 30 min in nitrogen with a purity of ≥99.99%, and then it is kept at 420 °C for 2 h. The pyrolysis gas generated by the two-stage catalytic pyrolysis is catalytically reformed into aromatic oil. The catalyst used for catalytic reforming is HZSM-5 molecular sieve, and the mass of the HZSM-5 molecular sieve is 15% of the mass of the glass fiber bundles;

[0108] (3) The glass fibers obtained in the step (2) are subjected to fiber strengthening regeneration to obtain regenerated glass fibers. The fiber strengthening regeneration is a combined process of microwave-assisted acid etching and plasma surface activation. The microwave-assisted acid etching uses a nitric acid solution with a concentration of 0.5 mol / L, the temperature of the microwave-assisted acid etching is 80 °C, and the power of the microwave-assisted acid etching is 300 W. The atmosphere of the plasma surface activation is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 9:1. The specific method is as follows: The glass fibers after microwave-assisted acid etching are immersed in a 3 wt% silane coupling agent KH-550 solution (pH = 4.5, and the solvent is ethanol / water with a volume ratio of 7:3), taken out after reacting at 60 °C for 2 h, and heat-treated at 120 °C for 1 h to form a chemical bonding interface.

[0109] The regenerated glass fiber concrete reinforcement material prepared using the above regenerated glass fibers has a preparation method as follows: The regenerated glass fibers, cement (P·O42.5, 340 kg / m 3After mixing with aggregates, dry mix for 60 s, then add water (control the water-binder ratio to be 0.48) and wet mix for 120 s. Control the slump to be 160 ± 20 mm. Then use a vibrating table to compact (frequency 50 Hz, time 60 s). Finally, cure for 28 d under the conditions of 20 ± 2 °C and humidity RH ≥ 95% to obtain a recycled glass fiber concrete reinforcement material; the aggregates are sand and gravel and class I fly ash. The dosage of sand and gravel in the recycled glass fiber concrete reinforcement material is 38 wt.%, and the dosage of class I fly ash is 20 wt.%; the length of the recycled glass fiber is 12 - 18 mm, the diameter of the recycled glass fiber is 13 - 17 μm, and the dosage of the recycled glass fiber in the recycled glass fiber concrete reinforcement material is 0.9 wt%.

[0110] Example 4

[0111] A method for recycling glass fiber from retired blades comprises the following steps:

[0112] (1) Conduct multi-stage crushing pretreatment on retired 1.5 MW wind turbine blades (GFRP, glass fiber content is 68 wt%). That is, first use a jaw crusher for primary shredding to make the size 50 - 100 mm, then use an impact crusher for secondary crushing to make the size 10 - 20 mm, and finally use a combination of eddy current separation and electrostatic separation for separation to obtain glass fiber bundles with a integrity rate of ≥ 90% and Fe content < 0.3%;

[0113] (2) After mixing the glass fiber bundles obtained in step (1) with a catalyst, conduct two-stage catalytic pyrolysis to obtain glass fibers with surface residual carbon < 3%; the catalyst is Ni / Al2O3 catalyst, and the mass of the catalyst is 10% of the total mass of the glass fiber bundles and the catalyst; the two-stage catalytic pyrolysis is as follows: keep warm at 300 °C for 30 min in nitrogen with purity ≥ 99.99%, and then keep warm at 380 °C for 2 h; the pyrolysis gas generated by the two-stage catalytic pyrolysis is catalytically reformed into aromatic oil, and the catalyst used for catalytic reforming is HZSM-5 molecular sieve, and the mass of the HZSM-5 molecular sieve is 15% of the mass of the glass fiber bundles;

[0114] (3) Fiber-reinforced regeneration is carried out on the glass fiber obtained in the step (2) to obtain regenerated glass fiber; the fiber-reinforced regeneration is a combined process of microwave-assisted acid etching and plasma surface activation; the microwave-assisted acid etching uses a nitric acid solution with a concentration of 0.5 mol / L, the temperature of the microwave-assisted acid etching is 80 °C, and the power of the microwave-assisted acid etching is 300 W; the atmosphere of the plasma surface activation is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 9:1. The specific method is: immerse the glass fiber after microwave-assisted acid etching in a 3 wt% silane coupling agent KH-550 solution (pH = 4.5, the solvent is ethanol / water = 7:3 by volume ratio), take it out after reacting at 60 °C for 2 h, and perform heat treatment at 120 °C for 1 h to form a chemical bonding interface.

[0115] The regenerated glass fiber concrete reinforcing material prepared by using the above regenerated glass fiber, the preparation method is: mix the regenerated glass fiber, cement (P·O 42.5, 340 kg / m 3 ) and aggregate, and perform dry mixing for 60 s, then add water (control the water-binder ratio to be 0.48) and perform wet mixing for 120 s, control the slump to be 160 ± 20 mm, then use a vibrating table to compact (frequency 50 Hz, time 60 s), and finally cure for 28 d under the conditions of 20 ± 2 °C and humidity RH ≥ 95% to obtain the regenerated glass fiber concrete reinforcing material; the aggregate is sand and gravel and class I fly ash, the dosage of sand and gravel in the regenerated glass fiber concrete reinforcing material is 38 wt.%, and the dosage of class I fly ash is 20 wt.%; the length of the regenerated glass fiber is 12 - 18 mm, the diameter of the regenerated glass fiber is 13 - 17 μm, and the dosage of the regenerated glass fiber in the regenerated glass fiber concrete reinforcing material is 0.6 wt%.

[0116] Example 5

[0117] A regeneration method for retired blade glass fiber, which is the following steps:

[0118] (1) Perform multi-stage crushing pretreatment on the retired 1.5 MW fan blade (GFRP, the glass fiber content is 68 wt%), that is, first use a jaw crusher for primary shredding to make its size 50 - 100 mm, then use an impact crusher for secondary crushing to make its size 10 - 20 mm, and finally use a combination of eddy current separation and electrostatic separation for separation to obtain a glass fiber bundle, the integrity rate of the glass fiber bundle ≥ 90%, and the Fe content < 0.3%;

[0119] (2) Mix the glass fiber bundles obtained in step (1) with a catalyst and perform two-stage catalytic pyrolysis to obtain glass fibers with less than 3% residual carbon on the surface; the catalyst is a Ni / Al₂O₃ catalyst, and the mass of the catalyst is 10% of the total mass of the glass fiber bundles and the catalyst; the two-stage catalytic pyrolysis is as follows: keep it at 250 °C for 30 min in nitrogen with a purity ≥ 99.99%, and then keep it at 400 °C for 2 h; the pyrolysis gas generated by the two-stage catalytic pyrolysis is catalytically reformed into aromatic oil, and the catalyst used for catalytic reforming is HZSM-5 molecular sieve, and the mass of the HZSM-5 molecular sieve is 15% of the mass of the glass fiber bundles;

[0120] (3) Carry out fiber-reinforced regeneration on the glass fibers obtained in step (2) to obtain regenerated glass fibers; the fiber-reinforced regeneration is a combined process of microwave-assisted acid etching and plasma surface activation; the microwave-assisted acid etching uses a nitric acid solution with a concentration of 0.5 mol / L, the temperature of the microwave-assisted acid etching is 80 °C, and the power of the microwave-assisted acid etching is 350 W; the atmosphere of the plasma surface activation is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 9:1. The specific method is: immerse the glass fibers after microwave-assisted acid etching in a 3 wt% silane coupling agent KH-550 solution (pH = 4.5, the solvent is ethanol / water = 7:3 by volume ratio), take them out after reacting at 60 °C for 2 h, and perform heat treatment at 120 °C for 1 h to form a chemical bonding interface.

[0121] The regenerated glass fiber concrete reinforcement material prepared using the above regenerated glass fibers. The preparation method is: mix the regenerated glass fibers, cement (P·O42.5, 340 kg / m 3 ) and aggregates, and perform dry mixing for 60 s, then add water (control the water-binder ratio to be 0.48) and perform wet mixing for 120 s, control the slump to be 160 ± 20 mm, then use a vibrating table to compact (frequency 50 Hz, time 60 s), and finally cure for 28 d under the conditions of 20 ± 2 °C and humidity RH ≥ 95% to obtain the regenerated glass fiber concrete reinforcement material; the aggregates are sand, gravel and Class I fly ash, the dosage of sand and gravel in the regenerated glass fiber concrete reinforcement material is 38 wt.%, and the dosage of Class I fly ash is 20 wt.%; the length of the regenerated glass fibers is 12 - 18 mm, the diameter of the regenerated glass fibers is 13 - 17 μm, and the dosage of the regenerated glass fibers in the regenerated glass fiber concrete reinforcement material is 0.9 wt%.

[0122] The regenerated glass fiber concrete reinforcement materials obtained in Examples 2 - 5 of the present invention have a 28-day compressive strength of 65 - 82 MPa (GB / T50081 standard), and at the same time can maintain a pumping construction performance with a slump of 180 - 220 mm.

[0123] Comparative Example 2

[0124] A method for recycling the glass fiber of retired blades, comprising the following steps:

[0125] (1) Perform multi-stage crushing pretreatment on retired 1.5MW wind turbine blades (GFRP, glass fiber content is 68wt%), that is, first use a jaw crusher for primary shredding to make its size 50-100mm, then use an impact crusher for secondary crushing to make its size 10-20mm, and finally use a combination of eddy current separation and electrostatic separation for separation to obtain glass fiber bundles, with the integrity rate of the glass fiber bundles ≥90% and the Fe content <0.3%;

[0126] (2) Mix the glass fiber bundles obtained in the step (1) with a catalyst and keep it at 500°C for 2h in nitrogen with a purity ≥99.99% to obtain glass fibers. The catalyst is a Ni / Al2O3 catalyst, and the mass of the catalyst is 10% of the total mass of the glass fiber bundles and the catalyst;

[0127] (3) Perform fiber strengthening regeneration on the glass fibers obtained in the step (2) to obtain regenerated glass fibers; the fiber strengthening regeneration is a combined process of microwave-assisted acid etching and plasma surface activation; the microwave-assisted acid etching uses a nitric acid solution with a concentration of 0.5mol / L, the temperature of the microwave-assisted acid etching is 80°C, and the power of the microwave-assisted acid etching is 300W; the atmosphere of the plasma surface activation is a mixed gas of argon and oxygen, and the volume ratio of argon to oxygen is 9:1. The specific method is: soak the glass fibers after microwave-assisted acid etching in a 3wt% silane coupling agent KH-550 solution (pH = 4.5, the solvent is ethanol / water = 7:3 by volume ratio), take it out after reacting at 60°C for 2h, and perform heat treatment at 120°C for 1h.

[0128] The regenerated glass fiber concrete reinforcing material prepared by using the above regenerated glass fibers, the preparation method is: mix the regenerated glass fibers, cement (P·O42.5, 340kg / m 3 ) and aggregates, and perform dry mixing for 60s, then add water (control the water-binder ratio to be 0.48) for wet mixing for 120s, control the slump to be 160±20mm, then use a vibrating table for compaction (frequency 50Hz, time 60s), and finally cure for 28d under the conditions of 20±2°C and humidity RH≥95% to obtain the regenerated glass fiber concrete reinforcing material; the aggregates are sand and gravel and class I fly ash, the dosage of sand and gravel in the regenerated glass fiber concrete reinforcing material is 38wt.%, and the dosage of class I fly ash is 20wt.%; the length of the regenerated glass fibers is 12-18mm, the diameter of the regenerated glass fibers is 13-17μm, and the dosage of the regenerated glass fibers in the regenerated glass fiber concrete reinforcing material is 1.5wt%.

[0129] Comparative Example 3

[0130] A method for recycling glass fiber of retired blades, comprising the following steps:

[0131] (1) Perform multi-stage crushing pretreatment on retired 1.5 MW wind turbine blades (GFRP, glass fiber content is 68 wt%), that is, first use a jaw crusher for primary shredding to make the size 50 - 100 mm, then use an impact crusher for secondary crushing to make the size 10 - 20 mm, and finally use a combination of eddy current separation and electrostatic separation for separation to obtain glass fiber bundles, with the integrity rate of the glass fiber bundles ≥ 90% and the Fe content < 0.3%;

[0132] (2) Mix the glass fiber bundles obtained in step (1) with a catalyst and keep them at 300 °C for 2 h in nitrogen with a purity ≥ 99.99% to obtain glass fibers; the catalyst is a Ni / Al2O3 catalyst, and the mass of the catalyst is 10% of the total mass of the glass fiber bundles and the catalyst;

[0133] (3) Perform fiber strengthening regeneration on the glass fibers obtained in step (2) to obtain regenerated glass fibers; the fiber strengthening regeneration is a combined process of acid etching and plasma surface activation; the acid etching uses a nitric acid solution with a concentration of 0.5 mol / L, and the temperature of the acid etching is 80 °C; the atmosphere of the plasma surface activation is a mixed gas of argon and oxygen. The specific method is: soak the acid-etched glass fibers in a 3 wt% silane coupling agent KH-550 solution (pH = 4.5, the solvent is ethanol / water = 7:3 by volume ratio), take them out after reacting at 60 °C for 2 h, and perform heat treatment at 120 °C for 1 h to form a chemical bonding interface.

[0134] The regenerated glass fiber concrete reinforcing material prepared by using the above regenerated glass fibers, the preparation method is: mix the regenerated glass fibers, cement (P·O42.5, 340 kg / m 3 )), aggregates and water (control the water-binder ratio to 0.48), then wet mix for 120 s, then use a vibrating table for compaction (frequency 50 Hz, time 60 s), and finally cure for 28 d under the conditions of 20 ± 2 °C and humidity RH ≥ 95% to obtain the regenerated glass fiber concrete reinforcing material; the aggregates are sand, gravel and class I fly ash, the dosage of sand and gravel in the regenerated glass fiber concrete reinforcing material is 38 wt.%, the dosage of class I fly ash is 20 wt.%; the length of the regenerated glass fibers is 12 - 18 mm, the diameter of the regenerated glass fibers is 13 - 17 μm, and the dosage of the regenerated glass fibers in the regenerated glass fiber concrete reinforcing material is 1.5 wt%.

[0135] The regenerated glass fiber concrete reinforcement materials obtained in Comparative Examples 2 to 3 all had a 28-day compressive strength < 55 MPa (GB / T 50081 standard), and at the same time, pollutants such as dioxins and nitrogen oxides were released during the preparation process, causing environmental pollution.

[0136] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for recycling fiberglass of retired blades, characterized in that, It includes the following steps: (1) Conduct multi-stage crushing pretreatment on the retired blades to obtain glass fiber bundles; (2) Mix the glass fiber bundles obtained in the step (1) with a catalyst and conduct two-stage catalytic pyrolysis to obtain glass fibers; the two-stage catalytic pyrolysis is as follows: first keep the temperature at 250-320°C for 20-60 minutes, and then keep the temperature at 380-420°C for 1-5 hours; (3) Conduct fiber strengthening and regeneration on the glass fibers obtained in the step (2) to obtain regenerated glass fibers; the fiber strengthening and regeneration is a combined process of microwave-assisted acid etching and plasma surface activation.

2. The regeneration method according to claim 1, wherein The multi-stage crushing pretreatment in the step (1) includes primary shredding, secondary crushing, and sorting in sequence.

3. The regeneration method according to claim 2, characterized in that, The sorting is a combination of eddy current sorting and electrostatic sorting.

4. The regeneration method according to claim 1, wherein, The catalyst in the step (2) is a Ni / Al2O3 catalyst, and the mass of the catalyst is 8-12% of the total mass of the glass fiber bundles and the catalyst.

5. The regeneration method according to claim 1, wherein The atmosphere for the two-stage catalytic pyrolysis in the step (2) is an inert atmosphere.

6. The regeneration method according to claim 1, characterized in that, The acid used for microwave-assisted acid etching in the step (3) is a nitric acid solution; the concentration of the nitric acid solution is 0.3-0.7 mol / L.

7. The regeneration method according to claim 1, characterized in that The temperature for microwave-assisted acid etching in the step (3) is 70-90°C, and the power of microwave-assisted acid etching is 200-400 W.

8. The regeneration method according to claim 1, characterized in that, The method for plasma surface activation in the step (3) is: immerse the glass fibers after microwave-assisted acid etching in a silane coupling agent solution, and then conduct heat treatment.

9. The regenerated glass fiber obtained by the regeneration method according to any one of claims 1 to 8, characterized in that, The length of the regenerated glass fibers is 12-18 mm, and the diameter of the regenerated glass fibers is 13-17 μm.

10. A regenerated fiberglass concrete reinforcing material, characterized in that, The preparation method of the regenerated glass fiber concrete reinforcing material includes: dry-mix the regenerated glass fibers, aggregates, and cement, and then add water for wet mixing to obtain the regenerated glass fiber concrete reinforcing material; the regenerated glass fibers are the regenerated glass fibers described in claim 9.

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