Method for recovering carbon fibers from waste carbon/carbon composite

A technology of carbon-carbon composite materials and recycling methods, applied in the production of bulk chemicals, etc., can solve the problems of poor quality of recycled fibers, loss of mechanical properties, low production efficiency, etc., achieve uniform heating, fast heating speed, and energy saving effects

Inactive Publication Date: 2018-08-31
HUNAN NANFANG BOYUN NOVEL MATERIAL
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Problems solved by technology

[0003] At present, among carbon-carbon composite waste materials, carbon fiber recycling methods include mechanical physical methods, energy recovery methods, heat recovery methods, and chemical recovery methods. These methods all have problems such as low recovery efficiency, poor quality of recycled fibers, There are many problems such as serious surface area carbon, serious loss of mechanical properties, and large energy consumption.
[0004] Chinese invention patent CN103333360A discloses a method for efficiently recovering carbon fibers in carbon / carbon composite waste materials in the form of supercritical fluid, but the method has the following defects: the traditional electric heating mode is used to heat the high-temperature reactor to achieve At the supercritical point, it takes a long time to heat up, and the energy loss is large; the cycle time required for a single operation is long, the production efficiency is low, and the production cost is high

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  • Method for recovering carbon fibers from waste carbon/carbon composite

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Embodiment 1

[0029] In this embodiment, the method for microwave-assisted supercritical recovery of carbon fibers in carbon-carbon composite materials includes the following steps:

[0030] (1) Carbon-carbon composite waste pretreatment: cutting resin-based carbon-carbon composite waste into 10cm 3 The left and right blocks are added to the supercritical convection high-pressure hydrothermal reactor; the inner tank of the supercritical convective high-pressure hydrothermal reactor is made of high-density polytetrafluoroethylene;

[0031] (2) Treatment of nitric acid and sodium hydroxide aqueous solution: prepare a nitric acid solution with a mass concentration of 20% and a sodium hydroxide solution with a mass concentration of 20% with deionized water, and combine resin-based carbon-carbon composites equivalent to those described in step (1). Add the nitric acid solution and sodium hydroxide solution 5 times the weight of the material waste into the supercritical convection high-pressure h...

Embodiment 2

[0037] The difference between this embodiment and embodiment 1 is only:

[0038] Step (2), use deionized water to prepare the mixed acid of hydrochloric acid and acetic acid with mass concentration of 10%, and the mixed alkali solution of potassium hydroxide, sodium carbonate and sodium bicarbonate with mass concentration of 50%, and the weight is the step ( 1) The mixed acid solution of hydrochloric acid and acetic acid and the mixed alkali solution of potassium hydroxide, sodium carbonate and sodium bicarbonate, which are twice the weight of the resin-based carbon-carbon composite material waste, are added to the supercritical convective high-pressure In the hydrothermal reaction kettle, microwave is used to heat the reaction kettle, and the microwave power is adjusted to 10KW to raise the temperature inside the kettle to 120°C, and keep at this temperature for 1min;

[0039] In step (3), a mixture solution of ethanol, propanol, butanol, and benzyl alcohol with a mass concen...

Embodiment 3

[0045] The difference between this embodiment and embodiment 1 is only:

[0046] Step (2), using deionized water to prepare a mixed acid solution of formic acid, sulfurous acid and acetic acid with a mass concentration of 50%, and a mixed alkali solution of ammonium carbonate, ammonium bicarbonate, and sodium bicarbonate with a mass concentration of 10%, Mix the mixed acid solution of the formic acid, sulfurous acid and acetic acid with a weight equivalent to 3.5 times the weight of the resin-based carbon-carbon composite material waste in step (1) and ammonium carbonate, ammonium bicarbonate, and sodium bicarbonate Alkali solution is added into the supercritical convection high-pressure hydrothermal reaction kettle, the reaction kettle is heated by microwave, the power is adjusted to 2KW, the temperature in the kettle is raised to 50°C, and the temperature is kept at this temperature for 15min;

[0047] In step (3), a mixed alcohol solution of ethylene glycol, butanetriol, n-...

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Abstract

A method for recovering carbon fibers from a waste carbon/carbon composite comprises the following steps: (1) cutting resin-based carbon/carbon composite waste into blocks of 10 cm<3> plus/minus 3 cm<3>, and adding the blocks to a reaction kettle; (2) preparing medium-strong acid and alkali solutions with low boiling point, adding the solutions to the reaction kettle, performing microwave heatingto enable temperature in the kettle to be at 50-120 DEG C, and preserving heat for 1-15 min; (3) adding an alcohol organic solvent with concentration being 10%-50% of to the reaction kettle, and performing full stirring for uniformly mixing solid-liquid substances; (4) performing microwave heating to enable temperature of the kettle to reach 150-280 DEG C and a fluid in the kettle to be in a supercritical state, preserving heat for 1-15 min, and performing cooling; (5) extracting a solid material, washing the solid material to be neutral and drying the solid material at constant temperature toobtain recovered carbon fibers. The recovery method is low in time consumption and energy consumption, quality retention rate of the recovered carbon fibers is higher, cost of recovery of the carbonfibers from the carbon/carbon composite can be reduced remarkably, and efficient recovery and resourceful recycling of the carbon/carbon composite waste are realized.

Description

technical field [0001] The invention relates to a method for recycling carbon fibers in waste carbon-carbon composite materials, in particular to a microwave-assisted supercritical method for recycling carbon fibers in waste carbon-carbon composite materials. Background technique [0002] Carbon / carbon composite materials are considered to be the most promising due to their advantages of low density, high strength, high specific modulus, high thermal conductivity, low expansion coefficient, good friction performance, good thermal shock resistance and high dimensional stability. One of the promising high-temperature materials, it has been widely used in aerospace, automobile industry, military industry, medicine and other fields. However, after a certain number of years, the mechanical properties such as tensile and compressive properties can no longer meet the actual needs, and they cannot be used any longer, which leads to the generation of a large amount of waste carbon-ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J11/00C08K7/06
CPCC08J11/00C08K7/06Y02P20/54
Inventor 周南戴开瑛康志卫
Owner HUNAN NANFANG BOYUN NOVEL MATERIAL
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