Method for thermally melting and centrifugally separating aluminum-plastic composite material

Abstract

The invention relates to a method for thermally melting and centrifugally separating an aluminum-plastic composite material, and belongs to the technical field of comprehensive recycling of solid waste renewable resources. The method for thermally melting and centrifugally separating the aluminum-plastic composite material comprises the following steps: crushing or shearing the aluminum-plastic composite material; and heating the crushed or sheared aluminum-plastic composite material to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the cracking temperature of the plastic, carrying out centrifugal separation, flowing out plastic liquid, and cooling to obtain the plastic and the aluminum foil. According to the method, the separation aging is fast, when the aluminum-plastic film is heated to be higher than the plastic melting point temperature and controlled to be lower than the plastic decomposition temperature, aluminum-plastic separation can be fast achieved by means of a centrifugal device, the separation degree is high, and the technological process is short. When precise temperature control is achieved and the temperature is controlled to be below the cracking temperature, generation of oxygen-containing and chlorine-containing gas can be effectively inhibited, aluminum metal is prevented from being oxidized, the aluminum metal and equipment are prevented from being corroded by an aluminum-containing compound (HCl), and aluminum metal loss is reduced. According to the method, the waste aluminum-plastic materials with different aluminum contents can be continuously separated on a large scale, waste is turned into wealth, comprehensive utilization of resources is achieved, and the method has excellent economic and ecological benefits.

Description

Technical Field

[0001] The invention relates to a method for thermally melting and centrifugally separating aluminum-plastic composite materials, belonging to the technical field of comprehensive recycling of solid waste renewable resources. Background Art

[0002] Common aluminum-plastic composite materials include aluminum-plastic plates and aluminum-plastic composite packaging films, among which the aluminum-plastic composite packaging film is mainly composed of an aluminum foil high-barrier layer (15% to 50%) and a polymer heat-sealing layer (50% to 85%), etc. It has extremely high barrier, light-blocking and puncture-resistant properties, and is indispensable in high-barrier packaging such as new energy batteries, food, medicines and cutting-edge defense products. The national output of aluminum-plastic composite films has increased year by year, and most of them are disposable. The recycling rate in my country is only 10-15%, mainly through landfill or incineration, which greatly pollutes the environment and seriously wastes resources. Realizing the green and efficient recycling and high-value recycling of discarded aluminum-plastic composite packaging films is a key requirement for my country to control plastic pollution and efficiently recycle scrap aluminum metals and achieve a sustainable development strategy.

[0003] At present, the main processes for separating aluminum and plastic materials include mechanical separation, pyrolysis separation, chemical separation, and ultrasonic-assisted separation. From the actual production situation, the above methods all have different degrees of incomplete separation (for example, in mechanical separation, with high-voltage electrostatic separation, the final product still has 15-20% aluminum metal mixed in the plastic), low recovery rate (for example, due to the thinness of some aluminum foil layers, the presence of oxygen and chlorine elements in the plastic layer and the binder, the intermediate or final product of pyrolysis reacts with aluminum to form aluminum oxide, resulting in a low aluminum metal recovery rate), and high risk factors (for example, through chemical analysis combined with ultrasonic-assisted methods, since some organic solvents are flammable, explosive, and volatile, the risk factor of explosion and volatilization is high when combined with ultrasound), resulting in unclear economic benefits.

[0004] The patent application number is 200510090807X, a method for separating and recycling waste aluminum-plastic composite materials. The waste aluminum-plastic composite materials are crushed into strips and blocks, sealed in a sealed container, vacuumed, heated to form a plastic material in a pyrolysis vaporized state, and the pyrolysis gas is extracted by vacuuming, and the remaining in the container is aluminum metal material. In this patent application, the waste aluminum-plastic composite materials need to be heated to above the pyrolysis temperature to form a vaporized plastic material, which will inevitably produce oxygen and chlorine elements, so that the intermediate or final product of the pyrolysis reacts with aluminum to form aluminum oxide, resulting in a low aluminum metal recovery rate. When the heating temperature exceeds the cracking temperature of the plastic material, the molecular structure of the plastic material changes, and the products are hydrocarbons and non-condensable combustible gases. Summary of the invention

[0005] In view of the problems and shortcomings of the above-mentioned prior art, the present invention provides a method for thermal melting and centrifugal separation of aluminum-plastic composite materials. The method has a fast separation time. When the aluminum-plastic film is heated to a temperature above the melting point of the plastic and controlled below the decomposition temperature of the plastic, the aluminum-plastic separation can be quickly achieved with the help of a centrifugal device, and the separation degree is high and the process flow is short. When precise temperature control is achieved and the temperature is controlled below the cracking temperature, the generation of oxygen-containing and chlorine-containing gases can be effectively suppressed, the oxidation of aluminum metal can be avoided, and the aluminum metal and equipment can be corroded by aluminum-containing compounds (HCl), thereby reducing the loss of aluminum metal. The method can continuously and on a large scale separate waste aluminum-plastic materials with different aluminum contents, turn waste into treasure, realize the comprehensive utilization of resources, and have excellent economic and ecological benefits.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for thermally melting and centrifugally separating aluminum-plastic composite materials comprises the following steps:

[0008] (1) crushing or shearing the aluminum-plastic composite material;

[0009] (2) The crushed or sheared aluminum-plastic composite material is heated to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the cracking temperature of the plastic, centrifuged, and the plastic liquid is discharged, and the plastic and aluminum foil are obtained after cooling.

[0010] In the step (1), the plastic composite material is crushed or cut into long strips, blocks or squares with an area of ​​0.1 square centimeters to 5 square centimeters.

[0011] The centrifugal separation in step (2) is to change the direction of centrifugal rotation.

[0012] The changing of the centrifugal rotation direction is changing the rotation direction every 0.5-30 minutes.

[0013] In the step (2), the centrifugal separation uses rapid mechanical vibration to separate the liquid plastic from the aluminum foil.

[0014] The heat melting and centrifugal separation process in step (2) can be performed using a heat melting centrifugal separation device. One structure of the heat melting centrifugal separation device is as follows: Figure 1As shown, the hot melt centrifugal separation device includes a centrifuge base 1, a centrifuge housing 2, a heat insulating material 3, an exhaust device 4, a transmission device 5, a heating device 6, an aluminum-plastic composite material inlet and a plastic liquid collecting port. The centrifuge base 1 is provided with a centrifuge housing 2 on the top, the top of the centrifuge housing 2 can be opened and sealed, the centrifuge housing 2 is provided with an exhaust device 4 on the top, a centrifuge heating tank is provided inside the centrifuge housing 2, a heating device 6 is provided outside the centrifuge heating tank, an aluminum-plastic composite material inlet is provided on the top of the centrifuge heating tank, a transmission device 5 is provided at the bottom of the centrifuge heating tank through the heat insulating material 3 for transmission centrifugation, uniform small holes are provided on the outer surface of the centrifuge heating tank to allow the plastic liquid to flow out centrifugally, a plastic liquid collecting port is provided under the centrifuge heating tank and located inside the centrifuge housing 2, and the outflowing plastic liquid is collected at the plastic liquid collecting port.

[0015] The melting point and cracking temperature of common plastics in the above-mentioned aluminum-plastic composite materials are: polypropylene (PP) melting point 160-170℃, cracking 350-400℃; polyethylene (PE) melting point 105-135℃, cracking 400-500℃; nylon 6 (PA6) melting point 215-225℃, cracking 350-400℃; nylon 66 (PA66) melting point 255-265℃, cracking 350-400℃.

[0016] The beneficial effects of the present invention are:

[0017] (1) This method is simple to operate and has a fast separation speed. When heated to the melting point, aluminum and plastic can be effectively separated within half an hour;

[0018] (2) This method does not use hazardous chemicals such as ethyl acetate, and the operating environment is simple, safe, and environmentally friendly;

[0019] (3) This method can achieve the goal of not changing the molecular structure of the plastic and not cracking the plastic, thus providing a practical method for the resource utilization of aluminum plastic. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a structure of a hot melt centrifugal separation device that can realize the present invention.

[0021] Figure 2 It is a physical picture of the aluminum-plastic composite material of Example 1.

[0022] In the figure: 1-centrifuge base, 2-centrifuge housing, 3-insulating material, 4-exhaust device, 5-transmission device, 6-heating device. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0024] Example 1

[0025] The method for thermally melting and centrifugally separating the aluminum-plastic composite material comprises the following steps:

[0026] (1) 500 kg of aluminum-plastic composite material (the plastic in the aluminum-plastic composite material is nylon 6, and the aluminum content is 15%) Figure 2 As shown) broken or cut to 1cm*1cm size;

[0027] (2) The crushed or sheared aluminum-plastic composite material is heated to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the plastic cracking temperature (230°C), kept warm for 10 minutes, and centrifuged. During this period, the rotation direction is continuously changed at 300 revolutions per minute, and the rotation direction is changed every 3 minutes to allow the plastic liquid to flow out. After cooling, plastic and aluminum foil are obtained.

[0028] Place the crushed or sheared aluminum-plastic composite material into Figure 1 In the hot melt centrifugal separation device, the specific operation method is:

[0029] (1) Open the top of the centrifugal device housing 2, place the crushed or sheared aluminum-plastic composite material into the centrifugal heating tank through the plastic composite material inlet, close the top of the centrifugal device housing 2, turn on the heating device 6, and raise the temperature of the aluminum-plastic composite material to 230° C. and keep it warm for 10 minutes;

[0030] (2) Turn on the transmission device 5, rotate at 300 revolutions per minute, and change the rotation direction every 3 minutes. The plastic liquid flows out from the small hole of the centrifugal heating tank, and the plastic liquid is collected through the plastic liquid collection port, and the aluminum foil remains in the centrifugal heating tank.

[0031] After cooling, the aluminum foil and plastic were collected separately, and the solid recyclables were 491 kg (98.2%), with a loss of 9 kg (1.8%), including 89 kg (18.1%) of aluminum foil and 402 kg (81.8%) of plastic. There was basically no plastic on the surface of the aluminum foil. There were water droplets on the separation cover, and it was speculated that the loss component was water.

[0032] Comparative Example 1

[0033] The method for thermally melting and centrifugally separating aluminum-plastic composite materials comprises the following steps:

[0034] (1) 500 kg of aluminum-plastic composite material (the plastic in the aluminum-plastic composite material is nylon 6 and the aluminum content is 15%) is crushed or sheared into a size of 1 cm*1 cm;

[0035] (2) The crushed or sheared aluminum-plastic composite material is heated to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the plastic cracking temperature (230° C.), kept warm for 10 minutes, and centrifuged while keeping the rotation direction unchanged at 300 revolutions per minute. The plastic liquid flows out and is cooled to obtain plastic and aluminum foil.

[0036] After cooling, the aluminum foil and plastic were collected separately, and 493 kg (98.6%) of solid recyclables were obtained, with a loss of 7 kg (1.4%), including 98 kg (19.87%) of aluminum foil and 395 kg (80.13%) of plastic. There was still a small amount of plastic on the surface of the aluminum foil. There were water droplets on the separation cover, and it was speculated that the lost component was water.

[0037] Comparative Example 2

[0038] The method for thermally melting and centrifugally separating the aluminum-plastic composite material comprises the following steps:

[0039] (1) 500 kg of aluminum-plastic composite material (the plastic in the aluminum-plastic composite material is nylon 6 and the aluminum content is 15%) is crushed or sheared into a size of 10 cm*10 cm;

[0040] (2) The crushed or sheared aluminum-plastic composite material is heated to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the plastic cracking temperature (230°C), kept warm for 10 minutes, and centrifuged. During this period, the rotation direction is continuously changed at 300 revolutions per minute, and the rotation direction is changed every 3 minutes to allow the plastic liquid to flow out. After cooling, plastic and aluminum foil are obtained.

[0041] After cooling, the aluminum foil and plastic were collected separately, and 492 kg (98.4%) of solid recyclables were obtained, with a loss of 8 kg (1.6%), including 103 kg (20.94%) of aluminum foil and 489 kg (79.06%) of plastic. There was still a small amount of plastic on the surface of the aluminum foil. There were water droplets on the separation cover, and it was speculated that the lost component was water.

[0042] Example 2

[0043] The method for thermally melting and centrifugally separating the aluminum-plastic composite material comprises the following steps:

[0044] (1) 500 kg of aluminum-plastic composite material (the plastic in the aluminum-plastic composite material is nylon 6 and the aluminum content is 45%) is crushed or sheared into a size of 1 cm*1 cm;

[0045] (2) The crushed or sheared aluminum-plastic composite material is heated to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the plastic cracking temperature (230°C), kept warm for 10 minutes, and centrifuged. During this period, the rotation direction is continuously changed at 300 revolutions per minute, and the rotation direction is changed every 3 minutes to allow the plastic liquid to flow out. After cooling, plastic and aluminum foil are obtained.

[0046] After cooling, the aluminum foil and plastic were collected separately, and 495 kg (99%) of solid recyclables were obtained, with a loss of 5 kg (1%), including 230 kg (46.5%) of aluminum foil and 265 kg (53.5%) of plastic. There was basically no plastic on the surface of the aluminum foil. There were water droplets on the separation cover, and it was speculated that the lost component was water.

[0047] Example 3

[0048] The method for thermally melting and centrifugally separating the aluminum-plastic composite material comprises the following steps:

[0049] (1) 500 kg of aluminum-plastic composite material (polypropylene in the aluminum-plastic composite material, aluminum content is 45%) was crushed or sheared into 1 cm*1 cm size;

[0050] (2) The crushed or sheared aluminum-plastic composite material is heated to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the plastic cracking temperature (200°C), kept warm for 10 minutes, and centrifuged. During this period, the rotation direction is continuously changed at 300 revolutions per minute, and the rotation direction is changed every 3 minutes. The plastic liquid flows out and is cooled to obtain plastic and aluminum foil.

[0051] After cooling, the aluminum foil and plastic were collected separately, and 496 kg (99.2%) of solid recyclables were obtained, with a loss of 4 kg (0.8%), including 232 kg (46.78%) of aluminum foil and 264 kg (53.22%) of plastic. There was basically no plastic on the surface of the aluminum foil. There were water droplets on the separation cover, and it was speculated that the lost component was water.

[0052] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for thermally melting and centrifugally separating aluminum-plastic composite materials, characterized in that The following steps are involved: (1) crushing or shearing the aluminum-plastic composite material; (2) The crushed or sheared aluminum-plastic composite material is heated to a temperature above the melting point of the plastic in the aluminum-plastic composite material and below the cracking temperature of the plastic, centrifuged, and the plastic liquid flows out, and the plastic liquid and aluminum foil are obtained after cooling.

2. The method for thermally melting and centrifugally separating aluminum-plastic composite materials according to claim 1, characterized in that: In the step (1), the plastic composite material is crushed or cut into long strips, blocks or squares with an area of ​​0.1 square centimeters to 5 square centimeters.

3. The method for thermally melting and centrifugally separating aluminum-plastic composite materials according to claim 1, characterized in that: The centrifugal separation in step (2) is to change the direction of centrifugal rotation.

4. The method for thermally melting and centrifugally separating aluminum-plastic composite materials according to claim 3, characterized in that: The changing of the centrifugal rotation direction is changing the rotation direction every 0.5-30 minutes.

5. The method for thermally melting and centrifugally separating aluminum-plastic composite materials according to claim 1, characterized in that: In the step (2), the centrifugal separation uses rapid mechanical vibration to separate the liquid plastic from the aluminum foil.

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