A recycling method of waste conveyor belt, modified powder, modified asphalt and asphalt composite material

Abstract

The application relates to a recycling method of waste conveying belt, modified powder, modified asphalt and asphalt composite material, and comprises the following steps: pretreating and crushing the waste conveying belt to obtain powder with a particle size of less than or equal to 0.5 mm; adding the powder into a high-speed mixer, adding a dispersing agent, a coupling agent and a compatilizer after temperature rising, and stirring and mixing to obtain modified powder, wherein the dispersing agent is a combination of nano calcium carbonate and superfine talc powder. It is unexpectedly found that the powder obtained by pretreating and crushing the waste PVC / PVG fabric whole-core flame-retardant conveying belt can completely solve the industry problems of poor compatibility of the powder with asphalt, weak interface combination and unstable heat storage by modifying the powder with a coupling agent, a compatilizer and a specific dispersing agent.

Description

Technical Field

[0001] This invention relates to the field of industrial solid waste resource utilization technology, specifically to a method for recycling waste conveyor belts, modified powder, modified asphalt, and asphalt composite materials. Background Technology

[0002] PVC / PVG woven solid-core flame-retardant conveyor belts are characterized by flame retardancy, antistatic properties, wear resistance, and high overall strength. They are widely used in industries such as coal mines, metal mines, ports, and metallurgy, serving as key transmission components in industrial production. As their service life ends, my country generates hundreds of thousands of tons of waste conveyor belts annually. Their main components are polyvinyl chloride (PVC), rubber, polyester / nylon fabric skeleton, flame retardants, etc., making them a difficult-to-degrade polymer composite material.

[0003] Currently, the conventional disposal methods for waste PVC / PVG fabric solid woven flame-retardant conveyor belts are mainly landfill, open-air stockpiling, and simple incineration. This not only occupies a large amount of land resources but also causes soil, groundwater, and air pollution, while resulting in a serious waste of polymer materials and fiber resources. Existing recycling technologies are mostly limited to coarse crushing and simple regeneration, suffering from poor dispersibility, poor compatibility with asphalt interfaces, unstable thermal storage, and substandard road performance, making them unsuitable for direct use in high-quality asphalt pavement materials.

[0004] Therefore, developing a green, efficient, and high-value recycling and remanufacturing technology for waste PVC / PVG fabric solid core flame-retardant conveyor belts, and converting them into asphalt composite materials that meet the acceptance standards, is of great significance for realizing the resource utilization of solid waste, reducing the cost of road materials, and improving the performance of road engineering. Summary of the Invention

[0005] In view of this, the present invention provides a method for recycling waste conveyor belts, modified powder, modified asphalt, and asphalt composite materials, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0006] To achieve the aforementioned objective, a first aspect of the present invention provides a method for recycling waste conveyor belts, comprising the following steps:

[0007] Step S1: Pre-treat and crush the waste conveyor belt to obtain powder with a particle size of less than or equal to 0.5 mm;

[0008] Step S2: Add the powder to a high-speed mixer, heat it up, add a dispersant, coupling agent and compatibilizer, stir and mix to obtain modified powder, wherein the dispersant is a combination of nano calcium carbonate and ultrafine talc powder.

[0009] In the recycling method described above, optionally, the modified powder contains, by mass percentage, 2.0-5.0% of the dispersant, 1.0-2.0% of the coupling agent, and 1.0-3.0% of the compatibilizer.

[0010] In the recycling method described above, optionally, the dispersant accounts for, for example, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0% by mass percentage in the modified powder.

[0011] In the recovery method described above, the coupling agent may optionally account for, for example, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, etc.

[0012] In the recycling method described above, the compatibilizer may optionally account for, for example, 1.0%, 1.2%, 1.4%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, etc.

[0013] In the recycling method described above, optionally, the mass ratio of the nano-calcium carbonate to the ultrafine talc powder is 1:1 to 3:1, and the particle size of the ultrafine talc powder is 1000 to 2000 mesh.

[0014] In the recycling method described above, optionally, the coupling agent is a silane coupling agent; the compatibilizer is a maleic anhydride grafted compatibilizer with a grafting rate of 1.5-2.0%.

[0015] In the recycling method described above, optionally, the coupling agent is at least one of KH-550 and KH-570, and the compatibilizer is at least one of maleic anhydride-grafted polyethylene and maleic anhydride-grafted polyolefin elastomer.

[0016] In the recycling method described above, optionally, in step S2, at least one of a heat stabilizer and an antioxidant is added during the stirring and mixing process, wherein the heat stabilizer is a calcium-zinc composite heat stabilizer.

[0017] By mass percentage, the heat stabilizer accounts for 0.4-0.8% and the antioxidant accounts for 0.2-0.5% in the modified powder.

[0018] In the recycling method described above, optionally, the antioxidant is at least one of antioxidant 1010 and antioxidant 168.

[0019] In the recycling method described above, optionally, in step S1, the waste conveyor belt is a waste woven fabric flame-retardant conveyor belt.

[0020] The waste fabric solid-core flame-retardant conveyor belt, such as at least one of waste PVC fabric solid-core flame-retardant conveyor belt or waste PVG fabric solid-core flame-retardant conveyor belt, contains PVC resin, rubber elastomer, fabric fibers, flame-retardant inorganic fillers, etc. These materials have poor compatibility with asphalt, weak interfacial bonding, and unstable thermal storage. Traditional waste rubber powder recycling methods still cannot effectively solve the problems of poor interfacial compatibility with asphalt and substandard road performance for powders containing these substances, making them unsuitable for direct use in high-quality asphalt pavement materials. However, the inventors of this application unexpectedly discovered that by adding coupling agents, compatibilizers, and specific dispersants to the powder obtained after pretreatment and crushing of waste fabric solid-core flame-retardant conveyor belts, the industry problems of poor compatibility with asphalt, weak interfacial bonding, and unstable thermal storage can be completely solved.

[0021] In the recycling method described above, optionally, in step S1, the pretreatment includes manual removal of impurities, followed by water washing, and drying with hot air at 100-120℃ until the moisture content is ≤1%. The water washing adopts a combination of spray washing and ultrasonic cleaning.

[0022] In the recycling method described above, optionally, in step S1, the crushing is performed using multi-stage crushing combined with screening.

[0023] In the recycling method described above, optionally, in step S2, the temperature is raised to 80-110°C and the stirring time is 5-25 min.

[0024] In the recycling method described above, step S2 may optionally include the following steps: adding the powder to a high-speed mixer, heating to 80-100°C, adding a dispersant, stirring at high speed for 5-10 minutes, then adding a coupling agent and a compatibilizer, heating to 90-110°C, and stirring at high speed for 10-15 minutes.

[0025] In the recycling method described above, optionally, in step S2, the stirring speed of the high-speed mixer is 1500-2500 r / min.

[0026] To achieve the aforementioned objective, a second aspect of the present invention provides a modified powder obtained by the recycling method as described in any one of the preceding first aspects.

[0027] To achieve the aforementioned objective, a third aspect of the present invention provides a modified asphalt, wherein, by weight, the modified asphalt comprises 100 parts of base asphalt and 8-18 parts of modified powder, wherein the modified powder is the modified powder as described in the second aspect above.

[0028] Optionally, the modified bitumen described above may further include 0-3 parts of aromatic oil.

[0029] To achieve the aforementioned objective, a fourth aspect of the present invention provides a method for preparing modified asphalt as described in the third aspect above, comprising heating and melting base asphalt, adding modified powder for premixing, then high-speed shearing, followed by isothermal development, and cooling to obtain modified asphalt.

[0030] In the preparation method described above, optionally, the base asphalt is petroleum asphalt. The petroleum asphalt may be road petroleum asphalt, specifically, No. 70 asphalt.

[0031] In the preparation method described above, optionally, the stirring speed of the high-speed shearing is 3500-5000 r / min, and the shearing time is 20-35 min.

[0032] In the preparation method described above, optionally, the isothermal development is carried out in a development tank, the isothermal development temperature is 165-180℃, and the development time is 40-90min.

[0033] To achieve the aforementioned objectives, a fifth aspect of the present invention provides an asphalt composite material comprising aggregate, mineral powder, and modified asphalt, wherein the modified asphalt is the modified asphalt described in the third aspect above or the modified asphalt prepared by any of the preparation methods described in the fourth aspect above.

[0034] In this invention, the modified asphalt meets the following requirements: penetration 55-65 (0.1 mm), softening point ≥ 50℃, and ductility ≥ 30 cm at 10℃. The asphalt composite material meets the following requirements: dynamic stability ≥ 6000 cycles / mm at 60℃, residual stability after water immersion ≥ 90%, and low-temperature bending strain ≥ 2800 με.

[0035] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0036] This application unexpectedly discovers that the powder obtained from the pretreatment and crushing of waste PVC / PVG fabric solid-core flame-retardant conveyor belts, when modified with coupling agents, compatibilizers, and specific dispersants, can completely solve the industry problems of poor compatibility with asphalt, weak interfacial bonding, and unstable thermal storage of such powders. Based on this discovery, further research led to and resulted in this invention.

[0037] Furthermore, the modified powder obtained by the recycling method of the present invention has high compatibility and high dispersibility. The modified asphalt obtained after being mixed with the base asphalt has penetration, softening point, ductility, high temperature rutting resistance, water stability and low temperature crack resistance, all of which meet the requirements of road asphalt specifications, and even meet the standards for first-class highways. It can be directly used as paving material for expressways, heavy-duty pavements and urban roads, realizing the high-value, large-scale and engineering utilization of industrial solid waste.

[0038] The recycling method of this invention is green and environmentally friendly with no secondary pollution, achieving nearly 100% resource utilization of waste conveyor belts. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] The modified asphalt provided in this embodiment is prepared by the following method:

[0042] Step 1: Preparation of modified powder

[0043] (1) Remove metal buckles, steel bars, stones, mud and other impurities from the waste PVG fabric whole core flame retardant conveyor belt manually. Then, remove surface oil and dust by a combination of high pressure spray water washing and ultrasonic cleaning. Finally, dry it with hot air at 110℃ until the moisture content is ≤1% to obtain clean blank.

[0044] (2) The clean billet is subjected to coarse crushing, medium and fine crushing and ultra-fine pulverization in sequence, and combined with wind classification and sieving to obtain rubber-plastic fiber composite powder with a particle size of 0.3-0.5mm. The powder contains PVC resin, rubber elastomer, fabric fiber, flame retardant inorganic filler, etc.

[0045] (3) Put the powder into a high-speed mixer, heat it to 90°C, then add the dispersant and stir at 2000 r / min for 8 min. Then add the coupling agent, compatibilizer, heat stabilizer and antioxidant, heat it to 100°C, stir at 2000 r / min for 12 min, then cool it to below 40°C and discharge the modified powder.

[0046] In step (3), by mass percentage, the modified powder contains 3.0% dispersant, 1.2% coupling agent, 2.0% compatibilizer, 0.5% heat stabilizer, and 0.3% antioxidant, with the remainder being powder. The dispersant is a combination of nano-calcium carbonate and ultrafine talc powder in a mass ratio of 2:1, with the ultrafine talc powder being 1500 mesh. The coupling agent is KH-550, and the compatibilizer is maleic anhydride-grafted polyethylene (PE-g-MAH, grafting rate 1.5-2.0%). The heat stabilizer is a calcium-zinc composite heat stabilizer, and the antioxidant is a combination of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0047] Step 2: Preparation of modified asphalt

[0048] 100 parts of base asphalt were added to a high-speed shear mill and heated to 170°C until completely melted. Then, 12 parts of modified powder were slowly added and premixed at low speed for 10 minutes. The mixture was then sheared at 4000 r / min for 25 minutes and transferred to a development tank. The mixture was then developed at a constant temperature of 175°C for 60 minutes to obtain modified asphalt.

[0049] The base asphalt used is No. 70 petroleum asphalt.

[0050] Example 2

[0051] The modified asphalt provided in this embodiment is prepared using a method basically the same as in Example 1, except that:

[0052] In step (2), the particle size of the powder is 0.1-0.3 mm.

[0053] In step (3), by mass percentage, the modified powder contains 4.0% dispersant, 1.5% coupling agent, 2.5% compatibilizer, 0.6% heat stabilizer, and 0.3% antioxidant, with the remainder being powder. The dispersant is a combination of nano-calcium carbonate and ultrafine talc powder in a mass ratio of 3:1, with the ultrafine talc powder being 2000 mesh. The coupling agent is KH-570, and the compatibilizer is maleic anhydride-grafted polyethylene (PE-g-MAH, grafting rate 1.5-2.0%).

[0054] In the second step, the amount of modified powder used is 10 parts.

[0055] Example 3

[0056] The modified asphalt provided in this embodiment is prepared using a method basically the same as in Embodiment 2, except that:

[0057] In step (1), a waste PVC fabric solid core flame-retardant conveyor belt is used.

[0058] In step (2), the particle size of the powder is less than 0.3 mm.

[0059] In the second step, the amount of modified powder used is 15 parts.

[0060] Example 4

[0061] The modified asphalt provided in this embodiment is prepared in the same way as in embodiment 1, except that in step (3), the powder is put into a high-speed mixer, heated to 90°C, and then a dispersant, coupling agent, compatibilizer, heat stabilizer and antioxidant are added. The mixture is stirred at high speed for 12 minutes and then cooled to below 40°C to obtain the modified powder.

[0062] Comparative Example 1

[0063] The modified asphalt provided in this comparative example is prepared by the following method:

[0064] Step 1: Preparing the powder

[0065] The waste PVG fabric whole core flame retardant conveyor belt is manually cleaned to remove impurities such as metal buckles, steel bars, stones, and dirt. Then, it is cleaned by a combination of high-pressure spray washing and ultrasonic cleaning to remove surface oil and dust. Finally, it is dried with hot air at 110℃ until the moisture content is ≤1% to obtain clean raw material.

[0066] The clean raw material is subjected to coarse crushing, medium and fine crushing and ultra-fine pulverization in sequence, combined with wind classification and sieving, to obtain rubber-plastic fiber composite powder with a particle size of 0.3-0.5mm.

[0067] Step 2: Preparation of modified asphalt

[0068] The second step is basically the same as in Example 1, except that the modified powder is replaced by the rubber-plastic fiber composite powder prepared in the first step of this example.

[0069] Comparative Example 2

[0070] The modified asphalt provided in this comparative example is basically the same as that in comparative example 2, except that the particle size of the rubber-plastic fiber composite powder is 1.0-2.0 mm.

[0071] Comparative Example 3

[0072] The modified asphalt provided in this comparative example is basically the same as that in Example 1, except that in step (3), only ultrafine talc powder is used as the dispersant.

[0073] Comparative Example 4

[0074] The modified asphalt provided in this comparative example is basically the same as that in Example 1, except that in step (3), only nano sodium carbonate is used as the dispersant.

[0075] Comparative Example 5

[0076] The modified asphalt provided in this comparative example is basically the same as that in Example 1, except that the amount of dispersant used in step (3) is 10%.

[0077] The modified asphalts of Examples 1-4 and Comparative Examples 1-5 were subjected to performance tests according to the methods specified in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011), and the results are shown in Tables 1 and 2.

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082] Asphalt composite materials were prepared by mixing the modified asphalt of Examples 1-4 and Comparative Examples 1-5 with aggregates and mineral powder, respectively. The modified asphalt consisted of 5.0 parts by weight, aggregates consisted of 92.5 parts by weight, and mineral powder consisted of 2.5 parts by weight. The aggregates were basalt aggregates (AC-13 type, particle size 0.075-13.2 mm), and the mineral powders were limestone mineral powders (particle size ≤0.75 mm).

[0083] The asphalt composite materials prepared using the modified asphalt of Example 1 and Comparative Examples 1-5 were tested according to the methods specified in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011). The test results are shown in Table 3.

[0084] Table 3

[0085]

[0086] As can be seen from the above test results, all indicators of the asphalt composite material in this application embodiment meet the standards for highways and first-class roads. Its high-temperature rutting resistance, water stability, and low-temperature crack resistance are significantly better than those of the comparative example. In contrast, the unmodified powder or large-particle powder has defects such as segregation, poor ductility, insufficient strength, and unqualified water stability, and cannot be used in road engineering.

[0087] The above test results show that the embodiments of this application, by recycling waste PVC / PVG fabric solid-core flame-retardant conveyor belts to obtain modified powder, and using it to prepare modified asphalt, have the following significant advantages compared with existing methods for recycling waste PVC / PVG fabric solid-core flame-retardant conveyor belts: They completely solve the industry problems of poor compatibility, weak interfacial bonding, and unstable thermal storage between PVC / rubber / fiber and asphalt, achieving high-value, large-scale, and engineering-based utilization of industrial solid waste, for example:

[0088] 1) Green and environmentally friendly with no secondary pollution: The entire process of treating waste conveyor belts adopts physical cleaning, mechanical crushing and low-temperature modification, without incineration and release of toxic and harmful substances, achieving nearly 100% resource utilization of waste conveyor belts.

[0089] 2) Powder particle size control: The powder particle size is controlled below 0.5mm to ensure that it is uniformly dispersed in asphalt without agglomeration or stratification.

[0090] 3) Significant physical-chemical composite modification effect: First, surface activation is carried out through dispersant, and then coupling grafting and compatibility enhancement are carried out to completely solve the industry problems of poor compatibility, weak interfacial bonding and unstable thermal storage of PVC / rubber / fiber with asphalt.

[0091] 4) Road performance fully meets standards: The material has a high softening point, good low-temperature ductility, high dynamic stability, and strong water stability, and can be directly used in the surface layer of heavy-duty roads and highways.

[0092] 5) Low cost and easy to industrialize: The raw materials are industrial solid waste, which are widely available and low cost. The process and equipment are mature and suitable for large-scale industrialization.

[0093] The above embodiments are only used to illustrate the embodiments of the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of the present invention, and the patent protection scope of the embodiments of the present invention should be defined by the claims.

Claims

1. A method for recycling waste conveyor belts, characterized in that, The recycling method includes the following steps: Step S1: Pre-treat and crush the waste conveyor belt to obtain powder with a particle size of less than or equal to 0.5 mm; Step S2: Add the powder to a high-speed mixer, heat it up, add a dispersant, coupling agent and compatibilizer, stir and mix to obtain modified powder, wherein the dispersant is a combination of nano calcium carbonate and ultrafine talc powder.

2. The recycling method according to claim 1, characterized in that, In the modified powder, the dispersant accounts for 2.0-5.0% by mass, the coupling agent accounts for 1.0-2.0%, and the compatibilizer accounts for 1.0-3.0%.

3. The recycling method according to claim 1, characterized in that, The mass ratio of the nano-calcium carbonate to the ultrafine talc is 1:1 to 3:1; and / or, The coupling agent is a silane coupling agent; and / or, The compatibilizer is a maleic anhydride grafted compatibilizer.

4. The recycling method according to claim 1, characterized in that, In step S2, at least one of a heat stabilizer and an antioxidant is added during the stirring and mixing process, wherein the heat stabilizer is a calcium-zinc composite heat stabilizer. By mass percentage, the heat stabilizer accounts for 0.4-0.8% and the antioxidant accounts for 0.2-0.5% in the modified powder.

5. The recycling method according to claim 1, characterized in that, In step S1, the waste conveyor belt is a waste fabric solid-core flame-retardant conveyor belt; and / or, In step S1, the pretreatment includes manual removal of impurities, followed by water washing, and hot air drying at 100-120℃ until the moisture content is ≤1%. The water washing employs a combination of spray washing and ultrasonic cleaning; and / or, In step S1, the crushing process employs multi-stage crushing combined with screening; and / or, In step S2, the temperature is raised to 80-110℃, and the stirring time is 5-25 minutes.

6. A modified powder, characterized in that, The modified powder is obtained by the recycling method according to any one of claims 1 to 5.

7. A modified asphalt, characterized in that, By weight, the modified asphalt comprises 100 parts of base asphalt and 8-18 parts of modified powder, wherein the modified powder is the modified powder as described in claim 6.

8. The method for preparing modified asphalt according to claim 7, characterized in that, The preparation method includes heating and melting the base asphalt, adding modified powder for premixing, then high-speed shearing, followed by isothermal development and cooling to obtain modified asphalt.

9. The preparation method according to claim 8, characterized in that, The base asphalt is petroleum asphalt; and / or, The high-speed shearing stirring speed is 3500-5000 r / min, and the shearing time is 20-35 min; and / or, The constant temperature development is carried out in a development tank, with a development temperature of 165-180℃ and a development time of 40-90 minutes.

10. An asphalt composite material comprising aggregates, mineral powder, and modified asphalt, characterized in that, The modified asphalt is the modified asphalt according to claim 7 or the modified asphalt prepared by any one of the preparation methods in claims 8-9.

Images