Process for the treatment and recycling of concrete production waste

Abstract

This invention discloses a process for treating and recycling concrete production waste, comprising the following steps: S1, adding coarse aggregate to a concrete production and transportation equipment and mixing it; after mixing, pouring the coarse aggregate coated with concrete production waste out of the outlet of the concrete production and transportation equipment; S2, adding fine aggregate to a concrete production and transportation equipment and mixing it; after mixing, pouring the fine aggregate coated with concrete production waste out of the outlet of the concrete production and transportation equipment; S3, drying the coarse aggregate obtained in S1 and the fine aggregate obtained in S2, and mixing them to obtain a dried clean material; S4, removing the shell from the dried clean material; S5, further screening the removed clean material. This invention uses a dry treatment method, resulting in stable aggregate moisture content, which is beneficial for reproducing concrete. Furthermore, it eliminates the need for wastewater treatment, leading to lower overall treatment costs and less environmental pollution.

Description

Technical Field

[0001] This invention relates to the field of concrete production waste treatment and recycling processes. More specifically, this invention relates to a concrete production waste treatment and recycling process. Background Technology

[0002] Concrete engineering is a major component of construction projects. During the production and application of concrete, waste concrete is inevitably generated. Research and statistical analysis have found that concrete batching plants generate approximately 2-3% of their daily concrete production as waste concrete. Of this, 1.6% is contaminated with concrete adhering to production and transportation equipment such as mixers and trucks, while 0.4-1.4% is waste concrete generated by accidental errors such as spillage during receiving, over-ordering, transportation delays, equipment malfunctions, and mix proportion errors. For waste concrete generated by accidental errors, digital production scheduling and process monitoring management can minimize errors and reduce losses; however, it is difficult to avoid waste concrete adhering to production and transportation equipment.

[0003] Concrete waste adhering to production and transportation equipment such as mixers and mixer trucks mainly consists of a slurry formed by mixing cement, fly ash, and other cementing materials with water, as well as some sand and gravel aggregates. Concrete mixing plants typically handle this waste using a sand and gravel separator. After being washed clean with water, the concrete adhering to the equipment enters the sand and gravel separator. Through the mechanical movement of a vibrating screen or drum screen, and the screening action of screens of different sizes, the sand and gravel in the mixture are separated. However, because this method relies primarily on water washing to separate sand and gravel from the slurry, it consumes a large amount of water. The wastewater needs further treatment through processes such as sedimentation, filtration, and neutralization to meet standards. This water treatment process is complex, difficult, and costly. Furthermore, the treated sand and gravel aggregates have a high mud content and high moisture content, and some small particles are carried away by the water, resulting in poor gradation of the separated sand and gravel aggregates, affecting their reuse. Summary of the Invention

[0004] To achieve these objectives and other advantages according to the present invention, a preferred embodiment of the present invention provides a process for treating and recycling concrete production waste, comprising the following steps:

[0005] S1. Add coarse aggregate to the concrete production and transportation equipment and mix it to coat the surface of the coarse aggregate with the concrete production waste on the inner wall of the equipment to achieve preliminary cleaning. After mixing, pour the coarse aggregate coated with concrete production waste out of the outlet of the concrete production and transportation equipment.

[0006] S2. Add fine aggregate to the concrete production and transportation equipment and mix it. After mixing, pour the fine aggregate covering the concrete production waste out of the concrete production and transportation equipment outlet.

[0007] S3. The coarse aggregate coated with concrete production waste in S1 and the fine aggregate coated with concrete production waste in S2 are dried and mixed to obtain the dried clean material.

[0008] S4. Remove the shell from the dried cleaning material;

[0009] S5. Further sieve the cleaned material after shelling.

[0010] According to a preferred embodiment of the present invention, in step S1, the volume of the added coarse aggregate is 2%-5% of the volume of the concrete production and transportation equipment.

[0011] According to a preferred embodiment of the present invention, in step S2, the volume of fine aggregate added is 2%-5% of the volume of the concrete production and transportation equipment.

[0012] According to a preferred embodiment of the present invention, the drying process includes the following operations:

[0013] The coarse aggregate coated with concrete production waste in S1 and the fine aggregate coated with concrete production waste in S2 are fed into a dryer for drying treatment. The dryer is a steel cylinder with an installation angle of 5 to 10°. The dryer can rotate continuously, and at the same time, hot dry air at a temperature of 60-100° is blown in from the outlet to the inlet.

[0014] According to a preferred embodiment of the present invention, in step S4, the shell removal process includes the following operations:

[0015] The dried cleaning material is fed into a primary drum screen containing steel balls. The cleaning material is mixed and screened with the steel balls. The primary small particles separated by the primary drum screen are further fed to a secondary drum screen. The screen aperture size of the secondary drum screen is smaller than that of the primary drum screen. The secondary small particles separated by the secondary drum screen are collected in the collection hopper as active micro powder.

[0016] According to a preferred embodiment of the present invention, the steel balls in the remaining material in the primary drum screen and the remaining material in the secondary drum screen are magnetically separated and removed by a magnetic separator.

[0017] According to a preferred embodiment of the present invention, the screening process in S5 includes the following operations:

[0018] After the steel balls are magnetically removed, the remaining material in the primary drum screen is screened through screens of different sizes to obtain coarse aggregates of different particle sizes; after the steel balls are magnetically removed, the remaining material in the secondary drum screen is screened through screens of different sizes to obtain fine aggregates of different particle sizes.

[0019] According to a preferred embodiment of the present invention, in the screening process of S5, a dust collector is installed above the primary drum screen and the secondary drum screen, and a blower is installed below to blow air from bottom to top.

[0020] The present invention has at least the following beneficial effects:

[0021] (1) This invention does not require wastewater treatment, resulting in lower overall treatment costs and less environmental pollution;

[0022] (2) The present invention uses a dry process, which can retain some of the cement and fly ash cementitious activity in the cement paste, and the resulting active micro powder is easier to reuse.

[0023] (3) In the dry processing of the present invention, the friction of iron balls can simultaneously play the role of aggregate shaping and reduce the content of needle-shaped and flaky particles.

[0024] (4) The present invention adopts dry processing, and the aggregate moisture content is stable, which is conducive to the re-production of concrete (the aggregate moisture content is very high and uneven after wet processing, which is not conducive to reuse).

[0025] (5) In conventional wet processing, water will carry away some small particles, resulting in poor aggregate gradation. The dry processing method used in this invention can avoid this problem.

[0026] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the process for treating and recycling concrete production waste in this invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0029] The following description is intended to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious modifications will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0030] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0031] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0032] like Figure 1 As shown, a preferred embodiment of the present invention provides a process for treating and recycling concrete production waste, including the following steps:

[0033] S1. Add coarse aggregate to the concrete production and transportation equipment and mix it to coat the surface of the coarse aggregate with the concrete production waste on the inner wall of the equipment to achieve preliminary cleaning. After mixing, pour the coarse aggregate coated with concrete production waste out of the outlet of the concrete production and transportation equipment.

[0034] For concrete production and transportation equipment such as mixers and mixer trucks, after production and transportation are completed, concrete waste adheres to their inner walls, and coarse aggregate and fine aggregate are used as cleaning materials.

[0035] S2. Add fine aggregate to the concrete production and transportation equipment and mix it. After mixing, pour the fine aggregate covering the concrete production waste out of the concrete production and transportation equipment outlet.

[0036] Adding fine aggregate and further mixing further coats the waste in the corners and crevices of concrete production and transportation equipment, achieving deep cleaning.

[0037] S3. To prevent the slurry from adhering firmly to the surface of the cleaning material after complete hydration, the material poured out from the equipment outlet needs to be dried. Specifically, the coarse aggregate coated with concrete production waste in S1 and the fine aggregate coated with concrete production waste in S2 are dried and mixed to obtain the dried cleaning material.

[0038] S4. Remove the shell from the dried cleaning material;

[0039] S5. Further sieve the cleaned material after shelling.

[0040] According to a preferred embodiment of the present invention, in step S1, the volume of coarse aggregate added is 2%-5% of the volume of the concrete production and transportation equipment. The specific volume ratio is determined according to the equipment adhesion rate and is generally controlled within 1-3 minutes of mixing.

[0041] According to a preferred embodiment of the present invention, in step S2, the volume of fine aggregate added is 2%-5% of the volume of the concrete production and transportation equipment.

[0042] According to a preferred embodiment of the present invention, the drying process includes the following operations:

[0043] The coarse aggregate coated with concrete production waste in step S1 and the fine aggregate coated with concrete production waste in step S2 are fed into a dryer for drying treatment. The dryer is a steel cylinder with an installation angle of 5-10°. The dryer rotates continuously, and hot dry air at a temperature of 60-100°C is blown in from the outlet to the inlet. When the clean material coated with waste enters from the inlet, it slowly moves towards the outlet under the action of the rotating steel cylinder and gravity, and is dried by the hot air. After losing moisture, the hydration reaction of the slurry in the waste on the surface of the clean material also stops simultaneously, and a thin shell forms on the surface of the aggregate.

[0044] In another technical solution, the shell removal process in step S4 includes the following operations:

[0045] The dried cleaning material is fed into a primary drum screen containing steel balls. The cleaning material is mixed and screened with the steel balls. The primary small particles separated by the primary drum screen are further fed to a secondary drum screen. The screen aperture size of the secondary drum screen is smaller than that of the primary drum screen. The secondary small particles separated by the secondary drum screen are collected in the collection hopper as active micro powder.

[0046] Generally, the screen aperture of a primary drum screen can be set to 5mm. When the drum screen rotates, it drives the steel balls and cleaning materials inside to tumble together. Under the action of mutual friction and collision between particles, the thin-shell-like waste on the surface of the cleaning material is peeled off, while the coarse aggregate is shaped, reducing the content of needle-like and flaky particles.

[0047] Particles smaller than 1mm screened out by the secondary drum screen are collected in the hopper and conveyed by belt to the active micro powder silo for storage. The main components of the active micro powder are incompletely hydrated cement, fly ash and other binder particles, as well as some stone powder particles. It can be directly reused as raw material for building materials such as dry-mixed mortar, water-stabilized material, and non-fired bricks.

[0048] In another technical solution, the steel balls in the remaining material in the primary drum screen and the remaining material in the secondary drum screen are magnetically separated and removed. The screening process in S5 includes the following operations:

[0049] After the steel balls are magnetically removed, the remaining material in the primary drum screen is sieved through screens of different sizes to obtain coarse aggregates of different particle sizes. Similarly, the remaining material in the secondary drum screen, after the steel balls are magnetically removed, is sieved through screens of different sizes to obtain fine aggregates of different particle sizes. The secondary drum screen has a 1mm aperture. As the drum screen rotates, it causes the steel balls and cleaning material to tumble together. Through friction and collision between the particles, the thin-shell-like waste material on the surface of the cleaning material is peeled off. Simultaneously, particles smaller than 1mm are screened out. The remaining material in the secondary drum screen consists of fine aggregates and steel balls. The fine aggregates include those added to the cleaning material and those adhering to the concrete waste on the inner wall of the equipment.

[0050] In another technical solution, during the screening process in S5, a dust collector is installed above the primary and secondary drum screens, and a blower is installed below them to blow air upwards. To improve aggregate quality and reduce mud content, a blower is installed at the bottom of the vibrating screen to blow air upwards. During vibration and descent, the aggregate comes into full contact with the upward airflow, further removing fine particles from the aggregate surface. Simultaneously, a dust collector is installed above the vibrating screen to capture fine particles in the dust-laden gas, desorb them, and then transport them to an activated micro-powder silo for utilization.

[0051] This invention uses coarse aggregate and fine aggregate sequentially to coat the residual concrete adhering to the equipment, resulting in good cleaning effect, no need for additional water rinsing, and no wastewater generated during the entire process, thus avoiding water treatment problems.

[0052] After the aggregate coated with waste slurry is dried and crusted, it is mixed with iron balls and fed into a drum screen for mixing, friction, and collision. This process removes the slurry crust from the surface of the aggregate, achieving aggregate recycling. At the same time, the friction and collision between the iron balls and the aggregate, as well as between the aggregates themselves, optimizes the aggregate morphology, reduces the content of needle-like and flaky particles, and improves aggregate quality.

[0053] After drying, the incompletely hydrated cement, fly ash, and other binder particles in the slurry remain active. When mixed with some stone powder particles from the aggregate, they can be directly reused as raw materials for building materials such as dry-mixed mortar, water-stabilized materials, and non-fired bricks. The recycled coarse and fine aggregates have low mud and moisture content, and good gradation with no particle loss, making them suitable for direct use in concrete production or reuse for cleaning production and transportation equipment.

[0054] Compared to conventional wet processing, which carries away some small particles and results in poor aggregate gradation, dry processing avoids this. This invention uses dry processing, eliminating the need for wastewater treatment, leading to lower overall treatment costs and less environmental pollution. Furthermore, dry processing retains some of the cementitious activity of cement and fly ash in the cement paste, resulting in more easily reusable active micropowder. During dry processing, the friction from the iron balls simultaneously shapes the aggregate, reducing the content of needle-like and flaky particles. After dry processing, the aggregate moisture content is stable, which is beneficial for re-producing concrete (wet processing results in high and uneven aggregate moisture content, hindering reuse).

[0055] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A process for the treatment and recycling of concrete production waste, characterized in that, The method comprises the following steps: S1, adding coarse aggregate into the concrete production and transportation equipment for mixing, so that the concrete production waste on the inner wall of the equipment is wrapped on the surface of the coarse aggregate to achieve preliminary cleaning, and after the mixing is completed, the coarse aggregate wrapped with the concrete production waste is poured out from the outlet of the concrete production and transportation equipment; S2, adding fine aggregate into the concrete production and transportation equipment for mixing, and after the mixing is completed, the fine aggregate wrapped with the concrete production waste is poured out from the outlet of the concrete production and transportation equipment; S3, drying the coarse aggregate wrapped with the concrete production waste in S1 and the fine aggregate wrapped with the concrete production waste in S2, and after mixing, clean materials after drying are obtained; S4, performing shell removing treatment on the clean materials after drying; S5, further performing screening treatment on the clean materials after shell removing.

2. The concrete production waste treatment and recycling process of claim 1, wherein, In S1, the volume of the added coarse aggregate is 2%-5% of the volume of the concrete production and transportation equipment.

3. The concrete production waste processing and recycling process of claim 1, wherein, In S2, the volume of the added fine aggregate is 2%-5% of the volume of the concrete production and transportation equipment.

4. The concrete production waste processing and recycling process of claim 1, wherein, In S3, the drying treatment comprises the following operations: The coarse aggregate wrapped with the concrete production waste in S1 and the fine aggregate wrapped with the concrete production waste in S2 are sent into a dryer for drying treatment, the dryer is a steel cylinder, the installation angle is 5-10°, the dryer can continuously rotate, and dry hot air with a temperature of 60-100°C is continuously blown into the dryer from the outlet to the inlet.

5. The concrete production waste processing and recycling process of claim 1, wherein, In S4, the shell removing treatment comprises the following operations: The clean materials after drying are conveyed into a first roller screen with steel balls, the clean materials are mixed and screened with the steel balls, the primary small particles screened out of the first roller screen are continuously conveyed into a second roller screen with steel balls, the screen hole size of the second roller screen is smaller than that of the first roller screen, the secondary small particles screened out of the second roller screen enter a collecting hopper for collection as active micropowder.

6. The concrete production waste processing and recycling process of claim 5, wherein, The steel balls in the remaining materials in the first roller screen and the second roller screen are respectively magnetically selected and sucked away by a magnetic separator.

7. The concrete production waste processing and recycling process of claim 6, wherein, In S5, the screening treatment comprises the following operations: The remaining materials in the first roller screen after the steel balls are magnetically selected and sucked away are screened through screens with different sizes to obtain coarse aggregates with different particle sizes; and the remaining materials in the second roller screen after the steel balls are magnetically selected and sucked away are screened through screens with different sizes to obtain fine aggregates with different particle sizes.

8. The concrete production waste processing and recycling process of claim 7, wherein, In the screening treatment in S5, a dust remover is installed above the first roller screen and the second roller screen, and a blower is installed below, and air blowing is performed from bottom to top.

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