CN114891273A - Modified overhaul slag based on tannic acid and preparation method and application thereof - Google Patents

Abstract

The invention discloses modified overhaul slag based on tannic acid, a preparation method and application thereof, and belongs to the field of green resource recycling of solid wastes. Forming a tannin polymer coating layer on the surface of the overhaul slag powder through self-polymerization reaction of tannin, and grafting a functional group with a hydrophobic function on the surface of the coating layer through a chemical grafting method to form a hydrophobic protective layer, wherein the obtained product is the composite modified overhaul slag based on the tannin; wherein the substance having a hydrophobic functional group is octadecylamine or hexamethyldisilazane. The process reduces the concentration of pollutants in the sewage through process characteristics, and greatly reduces the wastewater treatment cost. Meanwhile, the problem that the long-term stability of the product obtained after the resource treatment of the existing overhaul slag and other pollutants with poor long-term stability is insufficient is solved. The composite film layer achieves the purposes of protecting pollutants from leakage and modifying the surface, and provides a new method for recycling hazardous wastes.

Description

A kind of modified overhaul slag based on tannic acid and its preparation method and application

technical field

The invention belongs to the technical field of green resource recycling of solid waste, and particularly relates to a modified overhaul slag based on tannic acid and a preparation method and application thereof.

Background technique

The aluminum electrolysis production industry will inevitably generate various wastes in the production process, and Overhaul Waste Residues (OWRs) is the one with the largest output among various wastes. In recent years, overhaul slag has been classified as hazardous waste by the state because of the high toxicity and high content of the pollutants it carries. The harmless treatment of it according to the national hazardous waste standard will greatly increase the cost of the aluminum industry production industry. Therefore, in order to reduce the processing cost of the overhaul slag and relieve the pressure on the industry development caused by the rising industrial cost of aluminum electrolysis production, the research on the recovery and reuse of the overhaul slag has become a hot spot in the research fields of environment and chemical industry. There are few overhaul slag recycling processes, especially in the wet process category. In the early stage, inorganic salts are directly generated to achieve the purpose of making overhaul slag harmless and further reused. The resource-recycling overhaul slag obtained by such a method is an inorganic salt material, and the fluorine element in the fluoride exists in the form of ions, which is easy to dissolve rapidly under the condition of aqueous solution erosion, and has poor stability. Therefore, in order to explore a new fluoride recycling process, the overhaul slag recycling process should be optimized to strengthen the long-term stability of the solidified fluoride, and in the process of use, the good mechanical properties of the inorganic salt of the overhaul slag itself should be exerted, and the overhaul slag product should be guaranteed. It will not directly contact the environment, and finally achieve the purpose of long-term stable and effective utilization of resource-based overhaul slag.

The early methods of the wet recycling process of aluminum industry overhaul slag are mainly to use various inorganic fluoride ion curing agents, such as calcium fluoride, calcium chloride, calcium oxide and other calcium agents, through ion reaction to generate precipitation to solidify free fluoride ions. Although this method can achieve the purpose of recycling the overhaul slag, it has the following problems in the actual use process:

(1) The cured fluoride has poor stability. In the actual use of the inorganic precipitated fluoride in a short time, the solidified fluoride ions will be dissolved into the natural environment due to the erosion of the natural environment such as air and rain.

(2) The cost of fluoride recovery is high. The fluoride ion content in the overhaul slag waste liquid treated by the wet method cannot directly meet the national wastewater discharge standard, and the wastewater after fluoride sedimentation still needs to be defluorinated by other processes.

(3) There are few ways of reuse. The overhaul slag obtained by the current recycling process has low activity and poor performance in actual use.

Therefore, it is necessary to explore an economical and simple modification process to solve the problem of low chemical activity of waste water and products in the process of overhauling the slag, and using the modified overhaul slag as an engineering material modifier to increase the performance of building materials.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the present invention provides a modified overhaul slag based on tannic acid and a preparation method and application thereof. At the same time, the hydrophobic groups are grafted on the surface of the overhaul slag powder by these active groups, and finally the product octadecylamine/tannic acid composite modified overhaul slag (ODA/T-OWRs) or hexamethyl is obtained. Disilazane/tannic acid composite modified overhaul residues (HMDS/T-OWRs). The product is used as a modifier in asphalt pavement, which can improve the viscoelasticity and deformation resistance of modified asphalt.

To achieve the above object, the present invention proposes the following technical solutions:

Technical scheme 1: A modified overhaul slag based on tannic acid, through the self-polymerization reaction of tannic acid, a tannic acid polymer coating layer is formed on the surface of the overhaul slag powder, and then the hydrophobic function is formed by chemical grafting. The functional group is grafted on the surface of the coating layer to form a hydrophobic protective layer, and the obtained product is the modified overhaul slag based on tannic acid; wherein, the substance with the functional group with hydrophobic function is octadecylamine or hexamethyldicarbonate Silylamine.

Technical scheme 2: a method for preparing a modified overhaul slag based on tannic acid, comprising the following steps:

1) carry out precipitation fluorine treatment to the overhaul slag powder, filter, dry, and grind to obtain overhaul slag powder with precipitation;

2) Mixing the fluorine overhaul slag powder with a buffer solution to obtain an overhaul slag solution;

3) After adding tannic acid to the overhaul slag solution, ultrasonic treatment, heating and stirring, filtration, washing, drying, and regrinding, the obtained product is directly immersed in octadecylamine or hexamethyldisilazane and hot-mixed Treatment, standing, and the obtained product is washed, dried and ground to obtain a modified overhaul slag based on tannic acid.

During the operation, the particle size of each grinding is the same as that of the overhauled slag powder.

Further, in step 1), the particle size of the precipitation fluorine overhaul slag powder is 100-200 mesh.

Further, in step 2), the pH of the buffer solution is 8-9, and the solid-to-liquid ratio of the precipitation fluoride overhaul slag powder to the buffer solution is 1 g: (3-10) mL.

Further, in step 3), the mass ratio of the tannic acid to the precipitating fluorine overhaul slag powder is (0.5-1.0):5.

The fluorine precipitation treatment is a fluorine precipitation method in which the soluble fluoride in the overhaul slag is precipitated into insoluble fluoride, mainly using inorganic and organic substances that can precipitate and react with fluoride ions as the sedimentation agent. Relatively stable and hard properties; the precipitation agent can be selected from anhydrous calcium chloride, which can provide Ca ²⁺ to change the direction of the precipitation reaction during the reaction, and at the same time accelerate the polymerization of tannic acid by means of the chelation reaction with tannic acid. rate.

Further, in step 3), the ultrasonic treatment time is 15-30min, the heating temperature is 25-60°C, the stirring time is 12-24h, and the rotational speed is 350-450rpm.

Further, in step 3), the dosage ratio of the octadecylamine or hexamethyldisilazane to the heavy fluorine overhaul slag powder is (5-7) mL:5g.

Further, in step 3), the hot-mixing treatment temperature is 60°C, the hot-mixing treatment time is 1-2h, the standing temperature is 25-60°C, and the standing time is 12-18h.

Technical solution 3: a composite modified asphalt, which uses a tannic acid-based modified overhaul slag modifier and SBS (styrene-butadiene-styrene block copolymer) to jointly modify the asphalt to obtain a composite modified asphalt. Modified bitumen (OWRs/SBS). When the modified overhaul slag is mixed into the asphalt, keep a constant temperature of 150-200 ℃, and disperse the modified overhaul slag at a speed of 350-450rpm, so that the overhaul slag powder is evenly dispersed in the asphalt.

The mixing amount of the modified overhaul slag is 1.0-2.0% of the total mass of the asphalt, and the mixing amount of the SBS is 5% of the total mass of the asphalt.

The reaction principle of the present invention:

Based on the nature of the fluoride ion itself, calcium or other metal ions are used to react with it to form a hard precipitate, and then the tannic acid coating layer is adhered to the surface of the fluoride overhaul slag powder through the self-polymerization reaction of tannic acid. The fluoride precipitation powder is also encapsulated, resulting in less sediment in the solution directly contacting the solution, and promoting the continued sedimentation of fluoride ions in the solution. Finally, a large number of hydroxyl groups on the surface of the overhaul slag wrapped by tannic acid undergo Michael addition and Schiff base reaction with the amino group of the modifier, and the lipophilic and hydrophobic groups are grafted on the surface of the overhaul slag powder.

The invention adopts tannic acid as the coating layer to protect the inner core of the overhaul slag, and ensures that the overhaul slag will not directly contact the environment during use: the tannic acid coating layer, as an organic polymer, has good stability and coating sex. In the modification process, the core-shell structure can be formed with the overhaul slag powder as the core, and the hydrophobic group can be grafted outside the tannic acid coating layer by chemical grafting method to further form a hydrophobic protective layer, which not only retains the overhaul slag as an inorganic The excellent mechanical properties of salt have greatly improved the long-term stability of the resource-based overhaul slag.

The invention utilizes the self-polymerization reaction of tannic acid, wraps the settled fluoride in the sedimentation process, changes the amount of sedimentation in the solution in the sedimentation reaction process, and promotes further sedimentation of free fluoride ions in the waste water. At the same time, the whole process has few steps, so Low cost: In the process of overhauling the slag with resources, tannic acid self-polymerizes to form a coating layer to wrap the solid powder in the solution and isolate it from contact with the solution. The ion precipitation reaction is a reversible reaction, and the fluoride ion concentration in the final solution is controlled by the solubility product under the reaction environment. The coating of tannic acid can reduce the number of precipitates in the solution, so that the fluoride ions in the solution are further precipitated with calcium ions, which breaks through the limit ability of inorganic calcium agents to directly precipitate fluoride ions in the conventional process, and makes the wastewater produced by this process. The content of fluoride ions in the medium can reach the concentration of direct discharge, which greatly reduces the cost of resource utilization.

Chemical grafting will be carried out on the surface of the overhaul slag, making it suitable for use as a modifier in asphalt: asphalt has poor compatibility with inorganic salt powder, and metal cations in inorganic salt powder will reduce the service life of asphalt. Therefore, the grafting of hydrophobic groups on the tannic acid coating layer is chosen to improve the compatibility of the recyclable overhaul slag and asphalt, and at the same time further prevent the water from directly contacting the recyclable overhaul slag powder, resulting in the ionization of metal cations and damage to the use of asphalt. life. At the same time, bitumen, as an oily organic matter, can well protect the recyclable overhaul slag and further strengthen its stability.

Compared with the prior art, the beneficial effects of the present invention are:

1. Tannic acid is added in the reaction process of the present invention, which adheres to the surface of the overhauled slag powder, and is rapidly deposited and aggregated on its surface to form a polytannic acid coating layer. The coating layer has long-lasting stability and can be used as a link to increase inorganic and the deposited polytannic acid layer also has functional groups such as hydroxyl and imine groups, which provide a large number of active groups for further functionalization, which are easy to be combined with octadecylamine, hexamethyl group and other functional groups. The amine groups in the disilazine and other substances undergo reactions such as Schiff bases, which further promotes the efficient grafting of hydrophobic functional groups on the surface of the overhaul slag powder.

2. The present invention improves the low compatibility of the overhaul slag powder as an inorganic material with asphalt, and helps the overhaul slag powder to be better and more uniformly dispersed in the asphalt, thereby providing three-dimensional mechanical support and enhancing the elasticity of the asphalt. At the same time, the hydrophobic functional groups obtained by the secondary modification of the overhaul slag powder can improve the hydrophobic performance of the asphalt, so as to improve the water damage resistance of the asphalt, and for the overhaul slag itself, it can also ensure that the fluoride precipitation cannot be directly contacted with water. Causes the ionization of fluoride to generate fluoride ions that flow into the environment.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is a graph showing the variation of the overhaul slag/SBS composite modified asphalt complex shear modulus G ^* (10Hz) with temperature of Application Example 4 and Comparative Example 1 of the present invention;

Fig. 2 is a graph showing the variation of the overhaul slag/SBS composite modified asphalt complex shear modulus G ^* (10Hz) with temperature of Application Example 5 and Comparative Example 2 of the present invention;

Fig. 3 is a graph showing the variation of the overhaul slag/SBS composite modified asphalt complex shear modulus G ^* (10Hz) with temperature of Application Example 6 and Comparative Example 3 of the present invention;

Figure 4 shows the effect of tannic acid addition on fluoride ion concentration in overhaul slag;

Figure 5 shows the toxicity immersion experiment before and after modification of the overhaul slag.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail, which detailed description should not be construed as a limitation of the invention, but rather as a more detailed description of certain aspects, features, and embodiments of the invention.

It should be understood that the terms described in the present invention are only used to describe particular embodiments, and are not used to limit the present invention. Additionally, for numerical ranges in the present disclosure, it should be understood that each intervening value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated value or intervening value in that stated range is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention relates. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials in connection with which the documents are referred. In the event of conflict with any incorporated document, the content of this specification controls.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the present invention. The description and examples of the present application are only exemplary.

As used herein, "comprising," "including," "having," "containing," and the like, are open-ended terms, meaning including but not limited to.

During the test, the concentration of fluoride ions in each batch of overhaul slag was different, and it was necessary to test the treated samples to obtain the theoretical amount of precipitation fluoride. The overhaul slag used in the present invention is tested by a standard soaking process under the condition that the solid-liquid ratio is 10g:100mL, and the fluoride ion concentration in the leaching solution is 2523.75mg/L. The theoretical addition amount of anhydrous calcium chloride is 7.38g/L calculated by the number of moles, and the actual addition amount of anhydrous calcium chloride in the technological process is 5 times the theoretical value, namely 36.9g/L.

Preparation of Tris-HCl buffer: Dissolve 0.6057 g of Tris (tris (trishydroxymethylaminomethane) in 100 mL of water, and titrate to pH with 1 mol of HCl solution.

Example 1

(1) Weigh 5g of overhaul slag sieved to 100 mesh in 50mL of aqueous solution, dissolve in a magnetic stirrer with constant temperature heating at 50°C for 30min, and add anhydrous calcium chloride with a total amount of 36.9g/L in two times, each time After adding anhydrous calcium chloride, fluorine was precipitated for 10 minutes, and the product obtained by vacuum filtration was placed in an oven at 60 °C for 8 hours, for use;

(2) regrinding the precipitation fluorine overhaul slag obtained in step (1) to 100 mesh, and then dewatering in a 60° C. oven for 2 hours to obtain overhaul slag powder;

(3) 5g of overhaul slag powder obtained in step (2) was placed in 50mL of Tris-HCl buffer with pH 8.5, 0.5g of tannic acid was added, and sonicated for 15min in an ultrasonic cell disruptor. The heat dissipation method is controlled below 60 °C, and after completion, it is stirred at 350 rpm for 12 hours at 35 °C;

(4) Filtration of the product after the completion of the reaction, repeated washing with absolute ethanol and water for 3 times, drying in an oven at 60°C for 12 hours, the obtained product was re-ground to 100 mesh, and directly immersed in 5 mL of ODA or HMDS solution for hot mixing 1h, the hot mixing temperature was 60°C, and then placed at a constant temperature of 45°C for 12h. The final product was repeatedly washed 3 times with absolute ethanol and water, dried and ground to 100 mesh to obtain modified overhaul slag, denoted as 18 Alkylamine/tannic acid composite modified overhaul residues (ODA/T-OWRs) or hexamethyldisilazane/tannic acid composite modified overhaul residues (HMDS/T-OWRs).

Example 2

(1) Weigh 5g sieve to 150 mesh overhaul slag in 50mL aqueous solution, dissolve in 55°C constant temperature heating magnetic stirrer for 30min, add anhydrous calcium chloride with a total amount of 36.9g/L in two times, each time After adding anhydrous calcium chloride, fluorine was precipitated for 10 minutes, and the product obtained by vacuum filtration was placed in an oven at 60 °C for 8 hours, for use;

(2) regrinding the precipitation fluorine overhaul slag obtained in step (1) to 150 mesh, and then dewatering in a 60° C. oven for 2 hours to obtain overhaul slag powder;

(3) 5g of overhaul slag powder obtained in step (2) was placed in 50mL of Tris-HCl buffer with a pH of 8.0, 0.75g of tannic acid was added, and sonicated for 20min in an ultrasonic cell disruptor, and the ultrasonic temperature was adjusted by suspending ultrasonic or physical The heat dissipation method is controlled below 60 °C, and after completion, it is stirred at 400 rpm for 18 hours at 40 °C;

(4) Filtration of the product after the completion of the reaction, repeated washing with absolute ethanol and water for 3 times, drying in an oven at 60°C for 12h, the obtained product was re-ground to 150 mesh, and directly soaked in 6.5mL ODA or HMDS solution to heat Mixed for 1.5 hours, the hot mixing temperature was 60 °C, and then placed at a constant temperature of 50 °C for 13 hours. The final product was washed 3 times with absolute ethanol and water, dried and ground to 150 mesh, that is, the modified overhaul slag was obtained, recorded as Octadecylamine/tannic acid composite modified overhaul residues (ODA/T-OWRs) or hexamethyldisilazane/tannic acid composite modified overhaul residues (HMDS/T-OWRs).

Example 3

(1) Weigh 5g sieve to 200 mesh overhaul slag in 50mL aqueous solution, dissolve in 55 ℃ constant temperature heating magnetic stirrer for 30min, add anhydrous calcium chloride with a total amount of 36.9g/L in two times, each time After adding anhydrous calcium chloride, fluorine was precipitated for 10 minutes, and the product obtained by vacuum filtration was placed in an oven at 60 °C for 8 hours, for use;

(2) regrinding the precipitation fluorine overhaul slag obtained in step (1) to 200 mesh, and then dewatering in a 60° C. oven for 2 hours to obtain overhaul slag powder;

(3) 5g of overhaul slag powder obtained in step (2) was placed in 50mL of Tris-HCl buffer with a pH of 8.5, 1.0g of tannic acid was added, and sonicated for 30min in an ultrasonic cell disruptor. The heat dissipation method is controlled below 60 °C, and after completion, it is stirred at 450 rpm for 12 hours at 45 °C;

(4) Filtration of the product after the completion of the reaction, repeated washing with absolute ethanol and water for 3 times, drying in an oven at 60°C for 12 hours, the obtained product was re-ground to 200 mesh, and directly immersed in 5 mL of ODA or HMDS solution for hot mixing 1h, the hot mixing temperature was 60°C, and then placed at a constant temperature of 45°C for 14h. The final product was repeatedly washed 3 times with absolute ethanol and water, dried and ground to 200 mesh, that is, the modified overhaul slag was obtained, denoted as 18 Alkylamine/tannic acid composite modified overhaul residues (ODA/T-OWRs) or hexamethyldisilazane/tannic acid composite modified overhaul residues (HMDS/T-OWRs).

Application Example 4

Weigh 150 g of SK-70A asphalt and dry it in an oven at 135 °C for 2 hours to remove excess water. Add the HMDS/T-OWRs or ODA/T-OWRs and SBS obtained in Example 1 into the asphalt, and keep a constant temperature of 150 °C. After shearing for 2h under 5000rpm high-speed shearing machine, and dispersing under 400rpm high-speed shearing machine for 2h, the composite modified asphalt of HMDS/T-OWRs/SBS or ODA/T-OWRs/SBS was obtained; HMDS/T-OWRs Or the dosage of ODA/T-OWRs is 1% of the total mass of asphalt, and the dosage of SBS is 5% of the total mass of asphalt.

Application Example 5

Weigh 150 g of SK-70A asphalt and dry it in an oven at 135 °C for 2 hours to remove excess water. Add the HMDS/T-OWRs or ODA/T-OWRs and SBS obtained in Example 2 into the asphalt, and keep a constant temperature of 165 °C. After shearing for 2h under 5000rpm high-speed shearing machine, and dispersing under 450rpm high-speed shearing machine for 2h, the composite modified asphalt of HMDS/T-OWRs/SBS or ODA/T-OWRs/SBS was obtained; HMDS/T-OWRs Or the dosage of ODA/T-OWRs is 1.5% of the total mass of asphalt, and the dosage of SBS is 5% of the total mass of asphalt.

Application Example 6

Weigh 150 g of SK-70A asphalt and dry it in an oven at 135 °C for 2 hours to remove excess moisture. Add the HMDS/T-OWRs or ODA/T-OWRs and SBS obtained in Example 3 into the asphalt, and keep a constant temperature of 175 °C. After shearing under 5000rpm high-speed shearing machine for 2h, and dispersing under 450rpm high-speed shearing machine for 2h, the composite modified asphalt of HMDS/T-OWRs/SBS or ODA/T-OWRs/SBS was obtained; HMDS/T- The content of OWRs or ODA/T-OWRs was 2.0% of the total mass of asphalt, and the content of SBS was 5% of the total mass of asphalt.

Comparative Example 1

The same as application example 4, the difference is that the HMDS/T-OWRs or ODA/T-OWRs in example 1 are replaced with OWRs treated with precipitation only to obtain OWRs/SBS composite modified asphalt.

Comparative Example 2

Same as Application Example 5, the difference is that the HMDS/T-OWRs or ODA/T-OWRs in Example 1 are replaced with OWRs treated with fluorine only to obtain OWRs/SBS composite modified asphalt.

Comparative Example 3

The same as in Application Example 6, the difference is that the HMDS/T-OWRs or ODA/T-OWRs in Example 1 are replaced with only fluorine-treated OWRs to obtain OWRs/SBS composite modified asphalt.

Test Example 1

The DSR test was carried out for application examples 4-6, comparative examples 1-3 and the control group (modified asphalt with only SBS added, and the SBS content was 5% of the total mass of the asphalt). Specifically, 1.0 g of asphalt was poured on a diameter of For the center of the 25mm test board, moving the test board will squeeze the asphalt between the two test boards, heat the test piece conditioner, correct the excess asphalt around the perimeter, and then adjust the gap to a test gap of 1mm. When the temperature is equilibrated, the equipment will automatically conduct the test at the frequency of 10rad/s and the selected stress target value, and the recording and calculation are completed by the data acquisition system (it needs to be explained, HMDS-TA-OWRs and ODA- TA-OWRs/SBS are HMDS/T-OWRs and ODA/T-OWRs/SBS in the embodiment).

FIG. 1 is a comparison diagram of the storage modulus of the products obtained by applying Example 4 and Comparative Example 1. It can be seen from Figure 1 that when the complex shear modulus G* of the two modified asphalts is at the same temperature, the complex shear modulus of the HMDS/T-OWRs or ODA/T-OWRs/SBS composite modified asphalt in Example 4 is applied. The amount G* is greater than the complex shear modulus G* of the OWRs/SBS modified asphalt treated with only fluorine in Comparative Example 1, which proves that the modified asphalt after modification with tannic acid, hexamethyldisilazane and octadecylamine Overhaul slag, when added to asphalt, hardens the asphalt, thereby increasing its resistance to deformation.

2 is a comparison diagram of the storage modulus of the products obtained by applying Example 5 and Comparative Example 2. It can be seen from Figure 2 that the storage modulus G' of the HMDS/T-OWRs or ODA/T-OWRs/SBS composite modified asphalt is greater than that of the fluorine precipitation only at the same temperature. The storage modulus G' of OWRs/SBS modified asphalt indicates the enhanced elastic properties of HMDS/T-OWRs or ODA/T-OWRs modified asphalt.

3 is a comparison diagram of the storage modulus of the products obtained by applying Example 6 and Comparative Example 3. It can be seen from Fig. 3 that the loss modulus G” of the HMDS/T-OWRs or ODA/T-OWRs/SBS composite modified asphalt of the two modified asphalts at the same temperature is greater than that of the OWRs/SBS modified asphalt only treated with fluorine precipitation. Loss modulus G”, indicating the enhanced viscous properties of HMDS/T-OWRs or ODA/T-OWRs modified asphalt.

It can be seen from Figure 1-3 that the complex shear modulus G*, storage modulus G' and loss modulus G" of HMDS/T-OWRs or ODA/T-OWRs/SBS composite modified asphalt are all larger than those of only precipitation fluorine. Treating OWRs/SBS modified asphalt. This shows that while the viscosity is improved, the elasticity is also improved to a certain extent. It proves that the modified overhaul slag powder can effectively improve the viscoelastic performance and deformation resistance of asphalt after adding asphalt.

Test Example 2

The effect of the amount of tannic acid added on the fluoride ion concentration in the overhaul slag was discussed. The method was the same as that in Example 3. As shown in Figure 4.

It can be seen from Figure 4 that with the increase of the amount of tannic acid added, the concentration of fluoride ions gradually decreased, and the concentration of fluoride ions reached the lowest when the amount of tannic acid was 1.0 g. There is an increase, which proves that the tannins have completely wrapped the overhaul residue at 0.75g, and 0.75g is the lowest addition point to meet the performance standards.

Test Example 3

The hexamethyldisilazane/tannic acid composite modified overhaul slag obtained in Example 3 and the overhaul slag before modification were subjected to a toxicity soaking test, and the results are shown in FIG. 5 .

As can be seen from Figure 5, the modified overhaul slag showed obvious fluoride sequestration ability in the long-term toxicity immersion test. Although there will be a certain leaching situation in the early stage, it can be seen that the fluoride ion concentration after stabilization has a very high fluoride ion concentration. Good stability, the fluoride ion concentration is almost unchanged during the soaking process of more than 50 days.

After the modified overhaul slag obtained in Example 3 is added to the asphalt as a modifier, the asphalt itself will form a protective layer on the surface of the modifier, the modified modifier is evenly distributed in the asphalt, the surface interface is strong, and the asphalt will The surface of the modifier is uniformly and tightly coated, so it will show better protection during actual use.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. within.

Claims (10)

1. The modified overhaul slag based on the tannic acid is characterized in that a tannic acid polymer coating layer is formed on the surface of overhaul slag powder through self-polymerization of the tannic acid, and then a functional group with a hydrophobic function is grafted to the surface of the coating layer through a chemical grafting method to form a hydrophobic protective layer, so that the obtained product is the modified overhaul slag based on the tannic acid; wherein the substance having a hydrophobic functional group is octadecylamine or hexamethyldisilazane.

2. The method for preparing the modified tannin based overhaul slag as claimed in claim 1, which is characterized by comprising the following steps of:

1) performing fluorine precipitation treatment on the overhaul slag powder, filtering, drying and grinding to obtain fluorine precipitation overhaul slag powder;

2) mixing the fluorine-deposited overhaul residue powder with a buffer solution to obtain an overhaul residue solution;

3) adding tannic acid into the overhaul residue solution, performing ultrasonic treatment, heating and stirring, filtering, washing, drying, re-grinding, directly soaking the obtained product in octadecylamine or hexamethyldisilane amine, performing hot-mixing treatment, standing, cleaning, drying and grinding the obtained product to obtain the modified overhaul residue based on the tannic acid.

3. The method as claimed in claim 2, wherein in step 1), the particle size of the fluorine precipitating overhaul residue powder is 100-200 mesh.

4. The preparation method according to claim 2, wherein in the step 2), the pH of the buffer solution is 8-9, and the solid-to-liquid ratio of the fluorine precipitation overhaul residue powder to the buffer solution is 1 g: (3-10) mL.

5. The preparation method according to claim 2, wherein in the step 3), the mass ratio of the tannic acid to the fluorine precipitation overhaul slag powder is (0.5-1.0): 5.

6. the preparation method as claimed in claim 2, wherein in the step 3), the ultrasonic treatment time is 15-30min, the heating temperature is 25-60 ℃, the stirring time is 12-24h, and the rotation speed is 350-450 rpm.

7. The preparation method according to claim 2, wherein in the step 3), the ratio of the octadecyl amine or hexamethyldisilane amine to the fluorine precipitating overhaul residue powder is (5-7) mL:5 g.

8. The preparation method of claim 2, wherein in the step 3), the hot-mixing treatment temperature is 60 ℃, the hot-mixing treatment time is 1-2h, the standing temperature is 25-60 ℃, and the standing time is 12-18 h.

9. A modified asphalt, which is characterized in that the tannin-based modified slag modifier disclosed by claim 1 is used together with SBS to modify asphalt to obtain composite modified asphalt.

10. The composite modified asphalt of claim 9, wherein the modified overhaul slag is incorporated in an amount of 1.0 to 2.0% of the total mass of the asphalt.

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