Method for resource utilization of waste and used textiles by microwave-assisted pyrolysis of red mud catalyst

Abstract

The application discloses a kind of bauxite catalytic microwave-assisted pyrolysis of waste and old textile resourceization method, belong to microwave-assisted catalytic pyrolysis of waste and old textile processing field.The specific steps are as follows: after washing and dewatering treatment, waste and old textile is dried, granulation;After drying bauxite, grinding and sieving;Waste and old textile and bauxite particles after granulation are treated by microwave pyrolysis;Residual solid after pyrolysis is pyrolysis carbon;After collecting gas generated in the process of pyrolysis, condensation is obtained, and incondensable pyrolysis gas and liquid pyrolysis oil are obtained;The present application utilizes bauxite as catalyst and converts waste and old textile into valuable oil, gas and carbon, realizes the maximum absorption of bauxite and waste and old textile and resource utilization.The present application has low cost, simple operation, and pyrolysis product can meet some energy utilization, so that bauxite and waste and old textile are resourceized, harmless and reduced, achieve the goal of synergistic effect of pollution reduction and carbon reduction, produce good economic benefit, social benefit and environmental benefit.

Description

A method for resource recovery of waste textiles by microwave-assisted pyrolysis catalyzed by red mud. Technical Field

[0001] This invention relates to a method for the resource recovery of waste textiles by microwave-assisted pyrolysis of red mud, belonging to the field of microwave-assisted catalytic pyrolysis of waste textiles. Background Technology

[0002] Waste textiles refer to textiles that have been used for a long time or scraps from the textile production process. They are often made of cotton, linen, polyamide, and polyester materials, and are characterized by high carbon content, adjustable structure, and low impurity content.

[0003] Currently, the main processing technologies for waste textiles are: (1) incineration for power generation; (2) degradation to prepare chemicals; and (3) recycling waste textiles into regenerated fibers for reuse in the textile industry. The products obtained from these three recycling processes have low added value and weak market-driven momentum, necessitating the development of new processes and technologies to transform waste textiles into high-value-added products. Recycling waste textiles and obtaining high-performance raw materials through sorting, recycling, and reprocessing is an effective approach, but existing technologies are not suitable for waste textiles.

[0004] To improve resource utilization efficiency, certain technologies can be used to recover energy and valuable resources from waste textiles. This can not only reduce fossil fuel consumption but also promote the recycling of waste textiles. Since waste textiles are mostly blended fabrics containing dyes, pigments, and fine impurities that are difficult to separate, recycling waste textiles into recycled textile raw materials requires pretreatment such as component separation and purification, making recycling difficult and costly. Among various technologies, microwave-assisted catalytic pyrolysis is considered one of the emerging technologies for recovering energy and chemical components from organic waste. It can convert organic solid waste into three-phase high-value-added products: pyrolysis oil, pyrolysis char, and combustible gas, showing great promise. However, the catalysts currently used face problems such as easy deactivation and high cost. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for the resource recovery of waste textiles through microwave-assisted pyrolysis of red mud catalysis. This method solves the problems of incomplete treatment, pollutant generation, and high treatment costs associated with current waste textile processing. The technical solution of this invention is as follows:

[0006] (1) After washing and dehydrating the waste textiles, dry them.

[0007] (2) The dried waste textiles are crushed and granulated.

[0008] (3) Dry the red mud, grind it and sieve it.

[0009] (4) The granulated waste textiles obtained in step (2) and the sieved red mud particles obtained in step (3) are subjected to microwave pyrolysis treatment to obtain the residual solid, which is pyrolytic carbon.

[0010] (5) Collect and condense the gas generated in step (4) to obtain non-condensable pyrolysis gas and liquid pyrolysis oil.

[0011] Preferably, the equipment for washing and dehydrating the waste textiles in step (1) is a common household washing machine, and the drying is done using an electric constant temperature blower drying box, with drying conditions of 60-80℃ for 12-24 hours.

[0012] Preferably, the crushing device used in step (2) is a twin-shaft shear crusher or a combination of a twin-shaft shear crusher and a single-shaft fine crusher, and the granulation device is a disc granulator with a particle diameter of 4 to 10 mm.

[0013] Preferably, the equipment used for drying in step (3) is an electric thermostatic drying oven, and the drying conditions are drying at 100-120℃ for 24-48 hours, and the sieve is 60-100 mesh.

[0014] Preferably, the reaction temperature of the microwave pyrolysis treatment in step (4) is controlled at 400-700℃, the pyrolysis environment is oxygen-free or oxygen-deficient, the microwave power used in the microwave pyrolysis treatment process is 500-3000W, the microwave frequency is 915MHz or 2450MHz, and the microwave pyrolysis treatment time is 10-60 minutes.

[0015] Preferably, the mass ratio of the granulated waste textiles to the sieved red mud in step (4) is 2:1 to 1:2.

[0016] The principle of this invention is as follows: Red mud is used as a catalyst to degrade waste textiles with high carbon content into three pyrolysis products: solid, liquid, and gas. The presence of numerous weak and strong acid sites in the red mud structure promotes the breaking of C / C single bonds and the formation of aromatic hydrocarbons in the waste textiles, increasing the yield of pyrolysis oil and gas. Simultaneously, the presence of red mud lowers the reaction activation energy, further improving product yield. Furthermore, the unique rapid heating effect of microwaves allows organic matter to rapidly heat up and undergo pyrolysis, preventing secondary cracking reactions and further increasing the yield of pyrolysis oil and gas.

[0017] Beneficial effects of the present invention

[0018] (1) This invention utilizes microwave-assisted pyrolysis technology to pyrolyze waste textiles, which can save energy consumption in the pyrolysis process (compared to traditional pyrolysis), and can improve the yield and quality of pyrolysis oil and pyrolysis gas. Microwave-assisted pyrolysis can also efficiently solidify heavy metals in dyes of waste textiles.

[0019] (2) This invention enables red mud and waste textiles to be disposed of to varying degrees, providing a new approach to the resource utilization of solid waste and the reduction of environmental pollution caused by the accumulation of pollutants.

[0020] (3) Using large quantities of solid waste red mud as a catalyst is low-cost, reduces pollution, and increases the yield of pyrolysis products.

[0021] (4) Pyrolysis oil and gas can be used in the energy and chemical industries. By using them to generate electricity and then using the electricity for microwave-assisted pyrolysis, the energy consumption of waste textile pyrolysis can be further reduced.

[0022] (5) The method described in this invention can convert waste textiles into 100% pyrolytic carbon, pyrolytic gas and pyrolytic oil, and at the same time broaden new ideas for the resource utilization of low-cost red mud. Attached Figure Description

[0023] Figure 1 is a schematic diagram of the process flow of the present invention.

[0024] Figure 2 shows the XRD pattern of red mud particles.

[0025] Figure 3 is a comparison chart of the content of each product in Examples 1-3 and Comparative Examples 1-3. Detailed Implementation

[0026] Example 1

[0027] A method for the resource recovery of waste textiles by microwave-assisted pyrolysis of red mud, as shown in Figure 1, includes the following steps:

[0028] (1) Textiles produced by a textile factory in Yunnan Province were washed and dehydrated in a household washing machine and then dried at 60°C for 12 hours in an electric constant temperature drying oven.

[0029] (2) After the dried waste textiles are crushed by a twin-shaft shear crusher, they are granulated by a disc granulator. The granulated particles have a diameter of 4 mm.

[0030] (3) Bayer red mud produced by an aluminum company in Wenshan Prefecture, Yunnan Province was dried at 100°C for 24 hours in an electric constant temperature drying oven, and then ground through a 60-mesh sieve in an agate mortar to obtain red mud particles for later use.

[0031] (4) The textile obtained in step (2) and the red mud particles obtained in step (3) are fed into a microwave pyrolysis device at a mass ratio of 2:1 for pyrolysis treatment. The pyrolysis temperature is 400℃, the microwave power is 500W, the microwave frequency is 915MHz, the pyrolysis time is 10 minutes, and the pyrolysis process is kept in an oxygen-free environment. The solid residue obtained is pyrolysis carbon.

[0032] (5) Collect and condense the gas generated in step (4) to obtain non-condensable pyrolysis gas and condensed pyrolysis oil.

[0033] Example 2

[0034] A method for the resource recovery of waste textiles by microwave-assisted pyrolysis of red mud, as shown in Figure 1, includes the following steps:

[0035] (1) Textiles produced by a textile factory in Yunnan Province were washed and dehydrated in a household washing machine and then dried at 70°C for 18 hours in an electric constant temperature drying oven.

[0036] (2) After the dried waste textiles are crushed by a twin-shaft shear crusher, they are granulated by a disc granulator. The granulated particles have a diameter of 7 mm.

[0037] (3) Bayer process red mud produced by an aluminum company in Wenshan Prefecture, Yunnan Province was dried at 110°C for 36 hours in an electric constant temperature drying oven, and then ground through an 80-mesh sieve in an agate mortar to obtain red mud particles for later use.

[0038] (4) The textile obtained in step (2) and the red mud particles obtained in step (3) are fed into a microwave pyrolysis device at a mass ratio of 1:1 for pyrolysis treatment. The pyrolysis temperature is 500℃, the microwave power is 1500W, the microwave frequency is 915MHz, the pyrolysis time is 30 minutes, and the pyrolysis process is kept in an oxygen-free environment. The resulting solid residue is pyrolysis carbon.

[0039] (5) Collect and condense the gas generated in step (4) to obtain non-condensable pyrolysis gas and condensed pyrolysis oil.

[0040] Example 3

[0041] A method for the resource recovery of waste textiles by microwave-assisted pyrolysis of red mud, as shown in Figure 1, includes the following steps:

[0042] (1) Textiles produced by a textile factory in Yunnan Province were washed and dehydrated in a household washing machine and then dried at 80°C for 24 hours in an electric constant temperature drying oven.

[0043] (2) After the dried waste textiles are crushed by a twin-shaft shear crusher, they are granulated by a disc granulator with a particle diameter of 10 mm.

[0044] (3) Bayer process red mud produced by an aluminum company in Wenshan Prefecture, Yunnan Province was dried at 120°C for 48 hours in an electric constant temperature drying oven, and then ground through a 100-mesh sieve in an agate mortar to obtain red mud particles for later use.

[0045] (4) The textile obtained in step (2) and the red mud particles obtained in step (3) are fed into a microwave pyrolysis device at a mass ratio of 1:2 for pyrolysis treatment. The pyrolysis temperature is 700℃, the microwave power is 3000W, the microwave frequency is 2450MHz, and the pyrolysis time is 60 minutes. The pyrolysis process is kept in an oxygen-free environment. The solid residue obtained is pyrolysis carbon.

[0046] (5) Collect and condense the gas generated in step (4) to obtain non-condensable pyrolysis gas and condensed pyrolysis oil.

[0047] Comparative Example 1

[0048] The raw materials and conditions in this embodiment are the same as in Example 1, except that red mud is not added. Specifically:

[0049] (1) Textiles produced by a textile factory in Yunnan Province were washed and dehydrated in a household washing machine and then dried at 60°C for 12 hours in an electric constant temperature drying oven.

[0050] (2) After the dried waste textiles are crushed by a twin-shaft shear crusher, they are granulated by a disc granulator. The granulated particles have a diameter of 4 mm.

[0051] (3) The granulated textiles are sent to a microwave pyrolysis device for pyrolysis treatment. The pyrolysis temperature is 400℃, the microwave power is 500W, the microwave frequency is 915MHz, the pyrolysis time is 10 minutes, and the pyrolysis process is kept in an oxygen-free environment. The solid residue obtained is pyrolysis carbon.

[0052] (4) Collect and condense the gas generated in step (3) to obtain non-condensable pyrolysis gas and condensed pyrolysis oil.

[0053] Comparative Example 2

[0054] The raw materials and conditions in this embodiment are the same as in Example 1, except that red mud is replaced with calcium oxide, specifically:

[0055] (1) Textiles produced by a textile factory in Yunnan Province were washed and dehydrated in a household washing machine and then dried at 60°C for 12 hours in an electric constant temperature drying oven.

[0056] (2) After the dried waste textiles are crushed by a twin-shaft shear crusher, they are granulated by a disc granulator. The granulated particles have a diameter of 4 mm.

[0057] (3) Calcium oxide produced by a mineral products company in Yunnan Province was ground through an agate mortar and passed through an 80-mesh sieve to obtain calcium oxide particles for later use.

[0058] (4) The textile obtained in step (2) and the calcium oxide particles obtained in step (3) are fed into a microwave pyrolysis device at a mass ratio of 2:1 for pyrolysis treatment. The pyrolysis temperature is 400℃, the microwave power is 500W, the microwave frequency is 915MHz, the pyrolysis time is 10 minutes, and the pyrolysis process is kept in an oxygen-free environment. The solid residue obtained is pyrolysis carbon.

[0059] (5) Collect and condense the gas generated in step (4) to obtain non-condensable pyrolysis gas and condensed pyrolysis oil.

[0060] Comparative Example 3

[0061] The raw materials and conditions in this embodiment are the same as in Embodiment 1, except that the microwave pyrolysis equipment is replaced with a tubular furnace pyrolysis equipment. Specifically:

[0062] (1) Textiles produced by a textile factory in Yunnan Province were washed and dehydrated in a household washing machine and then dried at 60°C for 12 hours in an electric constant temperature drying oven.

[0063] (2) After the dried waste textiles are crushed by a twin-shaft shear crusher, they are granulated by a disc granulator. The granulated particles have a diameter of 4 mm.

[0064] (3) Bayer red mud produced by an aluminum company in Wenshan Prefecture, Yunnan Province was dried at 100°C for 24 hours in an electric constant temperature drying oven, and then ground through a 60-mesh sieve in an agate mortar to obtain red mud particles for later use.

[0065] (4) The textiles obtained in step (2) and the red mud particles obtained in step (3) are fed into a tube furnace at a mass ratio of 2:1 for pyrolysis treatment. The pyrolysis temperature is 400℃ and the pyrolysis time is 10 minutes. The pyrolysis process is kept in an oxygen-free environment. The solid residue obtained is pyrolysis char.

[0066] (5) Collect and condense the gas generated in step (4) to obtain non-condensable pyrolysis gas and condensed pyrolysis oil.

[0067] The product yields of pyrolysis of waste textiles in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1 and Figure 3.

[0068] Table 1. Product yields from the pyrolysis of waste textiles in Examples 1-3 and Comparative Examples 1-3.

[0069] Carbon Yield, Gas Yield, Oil Yield: Example 1: 20.44%, 12.98%, 66.58%; Example 2: 17.06%, 14.20%, 68.74%; Example 3: 18.59%, 16.47%, 64.94%; Comparative Example 1: 34.92%, 11.82%, 53.26%; Comparative Example 2: 27.35%, 12.65%, 60.00%; Comparative Example 3: 26.60%, 11.05%, 62.35%. surface

[0070] As can be seen from Table 1 and Figure 3, comparing Example 1 with Comparative Example 1, it can be seen that adding red mud to catalyze microwave pyrolysis can significantly improve the yield of pyrolysis oil. This is because red mud has weak acid and strong acid sites in its structure, and red mud can be considered a solid acid catalyst.

[0071] A comparison of Example 1 and Comparative Example 2 shows that, compared with calcium oxide catalysis, the use of red mud catalysis improves the yield of pyrolysis oil. This is because the red mud component contains Fe2O3 and TiO2, which can undergo other reaction pathways, such as hydrogenation or hydrocracking, thereby increasing the yield of pyrolysis oil.

[0072] A comparison of Example 1 and Comparative Example 3 shows that using a microwave pyrolysis device produces more pyrolysis oil and pyrolysis gas than using a conventional tubular furnace. This is because microwave-assisted pyrolysis utilizes the thermal effect of microwaves to heat the material. During microwave heating, the material absorbs microwave energy and converts it into its own heat energy. This conversion is very rapid, and the temperature rise of the material is significantly faster than in traditional heat transfer heating processes. Furthermore, during microwave pyrolysis, microwaves selectively heat waste textiles without heating the entire space inside the pyrolysis furnace. The temperature of the waste textiles is higher than the surrounding space. This heating method results in rapid heating and pyrolysis of organic matter. The pyrolysis products escape into the cooler surrounding space, preventing secondary cracking reactions. This rapid pyrolysis of organic matter increases the yield of pyrolysis oil and pyrolysis gas.

[0073] In summary, the methods for resource recovery of waste textiles by red mud catalytic microwave-assisted pyrolysis obtained in Examples 1 to 3 can be used to treat waste textiles and bulk solid waste red mud, and produce three-phase high value-added products: pyrolysis oil, pyrolysis char, and combustible gas.

Claims

1. A method for the resource utilization of waste textiles by microwave-assisted pyrolysis catalyzed by red mud, characterized in that: The specific steps are as follows: (1) Wash and dehydrate the waste textiles, then dry them; (2) Crush the dried waste textiles and granulate them; (3) Dry the red mud, grind it, and sieve it; (4) Perform microwave pyrolysis on the granulated waste textiles obtained in step (2) and the sieved red mud particles obtained in step (3) to obtain the residual solid, which is pyrolysis carbon; (5) Collect and condense the gas generated in step (4) to obtain non-condensable pyrolysis gas and liquid pyrolysis oil; The crushing device used in step (2) is a double-shaft shear crusher or a two-stage combination of a double-shaft shear crusher and a single-shaft fine crusher, and the granulation is done with a disc granulator. The particle diameter is 4-10 mm; the equipment used for drying in step (3) is an electric heating constant temperature blower drying box, and the drying conditions are drying at 100-120℃ for 24-48 hours, and the sieve is 60-100 mesh; the reaction temperature of the microwave pyrolysis treatment in step (4) is controlled at 400-700℃, the pyrolysis environment is oxygen-free or oxygen-deficient, the microwave power used in the microwave pyrolysis treatment process is 500-3000W, the microwave frequency is 915MHz or 2450MHz, and the microwave pyrolysis treatment time is 10-60 minutes; the mass ratio of the granulated waste textiles to the sieved red mud in step (4) is 2:1-1:

2.

2. The method for resource recovery of waste textiles by red mud catalytic microwave-assisted pyrolysis according to claim 1, characterized in that: In step (1), the equipment for cleaning and dehydrating waste textiles is a regular household washing machine, and the drying is done using an electric constant temperature blower drying oven. The drying conditions are 60-80℃ for 12-24 hours.

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