Construction waste treatment and recycling method

Abstract

The invention discloses a method for treating and recycling construction wastes. The method comprises the following steps: step S1, a pretreatment stage; s2, a crushing and grinding stage; s3, a recycled aggregate preparation stage; and S4, a regenerated product production stage: through fine classification, crushing, grinding and reasonable formula design of the building wastes, waste concrete, masonry and the like are converted into high-quality regenerated aggregates and regenerated products, so that high-added-value utilization of the building wastes is realized, exploitation of natural aggregates is reduced, resources are saved, and the production cost is reduced. The random landfill and stacking of the building wastes are avoided, and the occupation of land resources and the pollution to the environment are reduced. Meanwhile, waste water in the production process is recycled, water resource consumption is reduced, the development concept of environmental protection is met, and the treatment and recycling method is relatively simple in process and low in equipment investment cost.

Description

Technical Field

[0001] The present invention relates to the technical field of construction waste treatment, and in particular to a method for treating and recycling construction waste. Background Art

[0002] With the acceleration of urbanization, the construction industry has flourished, and at the same time, a large amount of construction waste has been generated. These construction wastes mainly include waste concrete, bricks, wood, metal, glass, etc. Traditional treatment methods are mostly simple landfill or stacking, which not only occupies a large amount of land resources, but also may cause pollution to soil, groundwater, etc. In addition, many components in construction waste have potential utilization value. If they can be effectively recycled, they can not only reduce the pressure on the environment, but also reduce the construction industry’s dependence on natural raw materials and achieve sustainable utilization of resources. However, the existing construction waste treatment and recycling methods have problems such as low treatment efficiency, unstable quality of recycled products, and high energy consumption, which are difficult to meet actual needs. Therefore, it is of great practical significance to develop a construction waste treatment and recycling method that is efficient, environmentally friendly, and can ensure the quality of recycled products. Summary of the invention

[0003] In response to the problems in the related technology, the present invention proposes a method for treating and recycling construction waste, which solves the problems of resource waste, environmental pollution and unstable quality of recycled products in the existing treatment methods, and realizes efficient treatment and high value-added utilization of construction waste.

[0004] Preprocessing stage:

[0005] Classification and screening: The collected construction waste is initially classified by combining manual and mechanical methods into categories such as concrete blocks, masonry, wood, metal, glass, etc. Concrete blocks, masonry and other lumps are screened using a vibrating screen and classified into different grades according to particle size. Particles larger than 50mm are used as coarse aggregate raw materials, particles between 10-50mm are used as fine aggregate raw materials, and particles less than 10mm enter the subsequent grinding process.

[0006] Cleaning and impurity removal: Use high-pressure water guns to wash the classified concrete blocks and bricks to remove dirt, dust, oil and other impurities on the surface to ensure the purity of the raw materials for subsequent processing. The wastewater after cleaning is recycled after being processed through sedimentation, filtration and other processes.

[0007] Crushing and grinding stage:

[0008] Crushing: Use jaw crusher and cone crusher to crush the coarse aggregate raw materials in two stages, and further crush the concrete blocks and masonry into smaller particles. Control the discharge port width of the jaw crusher to 20-30mm, and adjust the discharge port of the cone crusher to 10-15mm, so that the aggregate particle size after crushing meets the requirements.

[0009] Grinding: The screened particles less than 10mm and the crushed aggregates are sent to the ball mill for grinding. During the grinding process, an appropriate amount of grinding aid is added, and the amount of grinding aid added is 0.1%-0.3% of the raw material mass. Through the grinding action of the ball mill, the raw materials are ground into fine powder, of which the 80μm square hole sieve residue does not exceed 10%, in order to improve its activity and subsequent reaction performance.

[0010] Recycled aggregate preparation stage:

[0011] Mixing and stirring: Mix the ground concrete and masonry fine powder with a certain proportion of cement, fly ash, admixtures, etc. The amount of cement added is 10%-15% of the fine powder mass, the amount of fly ash added is 20%-30% of the fine powder mass, and the admixtures include water reducer, early strength agent, etc. The amount of water reducer added is 0.5%-1% of the fine powder mass, and the amount of early strength agent added is 1%-2% of the fine powder mass. Stir well in a forced mixer for 5-10 minutes to mix all the ingredients evenly to form a recycled aggregate blank with certain properties.

[0012] Molding and curing: The mixed recycled aggregate blank is fed into the molding die, and the recycled aggregate of the desired shape, such as cube, cylinder, etc., is formed by vibration and pressure molding. The molding pressure is controlled at 10-15MPa, the vibration frequency is 30-50Hz, and the vibration time is 3-5 minutes. The molded recycled aggregate is cured in a standard curing room, the curing temperature is controlled at 20±2℃, the relative humidity is greater than 95%, and the curing time is 7-14 days, so that its strength meets the design requirements.

[0013] Recycled product production stage:

[0014] Preparation of recycled concrete: Recycled concrete is prepared by mixing recycled aggregate as the main raw material with cement, water, admixtures, etc. according to a certain mix ratio. The replacement rate of recycled aggregate is 30%-70%, and the cement uses ordinary Portland cement with a strength grade of 42.5, and the water-cement ratio is controlled between 0.4-0.6. Admixtures are added according to actual needs, such as water reducers, air entraining agents, etc., and are fully mixed and evenly mixed through mixing equipment to make recycled concrete, which can be used for pouring general building structures.

[0015] Recycled brick production: Mix the recycled aggregate with an appropriate amount of cement, lime, gypsum, etc., add a certain amount of water and stir evenly, and then press it into shape through a brick-making machine. The amount of cement added is 10%-15% of the mass of the recycled aggregate, the amount of lime added is 5%-10% of the mass of the recycled aggregate, and the amount of gypsum added is 3%-5% of the mass of the recycled aggregate. The formed bricks are steam-cured in a curing kiln at a curing temperature of 80-100℃ and a curing time of 8-12 hours to produce recycled bricks with good strength and durability, which can be used for building wall masonry.

[0016] Beneficial Effects of the Invention

[0017] Efficient utilization of resources: Through the fine classification, crushing, grinding and reasonable formula design of construction waste, waste concrete, bricks and stones are converted into high-quality recycled aggregates and recycled products, achieving high added value utilization of construction waste, reducing the mining of natural aggregates and saving resources.

[0018] Significant environmental benefits: It avoids random landfill and stacking of construction waste, reduces the occupation of land resources and pollution to the environment. At the same time, the recycling of wastewater in the production process reduces water resource consumption, which is in line with the development concept of green environmental protection.

[0019] Stable quality of recycled products: Strict control of process parameters in each processing link, such as crushing particle size, grinding fineness, mixing ratio, molding pressure and curing conditions, ensures the stable performance of recycled aggregates and recycled products, which can meet various quality requirements of construction projects and expand the application scope of recycled products.

[0020] Improved economic benefits: The treatment and recycling method of the present invention has a relatively simple process, low equipment investment cost, and the recycled products have certain market competitiveness, which can bring considerable economic benefits to the enterprise and promote the sustainable development of the construction waste treatment industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 The present invention is a schematic flow chart of a method for treating and recycling construction waste. DETAILED DESCRIPTION

[0023] According to an embodiment of the present invention, a method for treating and recycling construction waste is provided.

[0024] Embodiment 1:

[0025] Raw material collection and pretreatment: Construction waste was collected at a building demolition site, with a total amount of about 100 tons. Through manual sorting, wood, metal, glass and other debris were picked out, and the remaining concrete blocks and masonry were about 80 tons. Vibrating screens were used for screening to obtain 20 tons of coarse aggregate raw materials with a particle size greater than 50mm, 30 tons of fine aggregate raw materials with a particle size of 10-50mm, and 30 tons of particles with a particle size less than 10mm. The coarse and fine aggregate raw materials were washed with high-pressure water guns, and the cleaning wastewater was recycled after sedimentation and filtration, consuming a total of about 5 tons of new water.

[0026] Crushing and grinding: 20 tons of coarse aggregate raw materials are first crushed by a jaw crusher, and the width of the discharge port is controlled to 25mm to obtain preliminary crushed aggregate. Then it is sent to a cone crusher for secondary crushing, and the discharge port is adjusted to 12mm, and finally coarse aggregate particles that meet the requirements are obtained. 30 tons of particles less than 10mm and crushed coarse aggregate particles are sent to a ball mill for grinding, and 0.1 tons of grinding aid (accounting for 0.125% of the raw material mass) are added at the same time, and the residue on the 80μm square hole sieve is 8%.

[0027] Preparation of recycled aggregate: 40 tons of ground fine powder, 4 tons of cement (10% of the mass of fine powder), 8 tons of fly ash (20% of the mass of fine powder), 0.2 tons of water reducer (0.5% of the mass of fine powder), and 0.4 tons of early strength agent (1% of the mass of fine powder) are mixed in a forced mixer for 8 minutes, and then sent into a molding mold after mixing evenly. Recycled aggregate is made under the conditions of molding pressure of 12MPa, vibration frequency of 40Hz, and vibration time of 4 minutes. The molded recycled aggregate is placed in a standard curing room for 10 days, and the curing temperature is controlled at 20℃ and the relative humidity is 98%.

[0028] Recycled product production:

[0029] Preparation of recycled concrete: Recycled concrete is prepared by mixing recycled aggregate with cement, water, admixtures, etc. at a recycled aggregate replacement rate of 50%. Cement uses ordinary Portland cement with a strength grade of 42.5, a water-cement ratio of 0.5, and an appropriate amount of water reducer. A total of 100 cubic meters of recycled concrete was prepared. After testing, its compressive strength reached the C30 grade requirement and was used for pouring the foundation cushion of a certain building.

[0030] Recycled brick production: 30 tons of recycled aggregates are mixed with 3 tons of cement (accounting for 10% of the mass of recycled aggregates), 1.5 tons of lime (accounting for 5% of the mass of recycled aggregates), and 0.9 tons of gypsum (accounting for 3% of the mass of recycled aggregates). After adding appropriate amount of water and stirring evenly, they are pressed into shape by a brick making machine. The bricks are placed in a curing kiln for steam curing at a temperature of 90°C for 10 hours to make 50,000 recycled bricks. After testing, the strength grade of the recycled bricks reaches MU15 and is used for the wall masonry of a certain building.

[0031] Embodiment 2:

[0032] Raw material collection and pretreatment: 80 tons of construction waste were collected at another construction site. After sorting and screening, and removing impurities such as wood and metal, 65 tons of concrete blocks and masonry remained. The vibrating screen screened out 15 tons of coarse aggregate raw materials with a particle size greater than 50mm, 25 tons of fine aggregate raw materials with a particle size of 10-50mm, and 25 tons of particles with a particle size less than 10mm. The raw materials were cleaned with a high-pressure water gun, and the cleaning wastewater was recycled after treatment, consuming about 4 tons of new water.

[0033] Crushing and grinding: After the coarse aggregate raw materials are crushed by a jaw crusher (discharge port width 28mm) and a cone crusher (discharge port 13mm), they are sent to a ball mill for grinding together with particles smaller than 10mm. 0.15 tons of grinding aid (accounting for 0.23% of the raw material mass) are added and ground to a 9% residue on an 80μm square hole sieve.

[0034] Preparation of recycled aggregate: 40 tons of ground fine powder were mixed with 6 tons of cement (accounting for 15% of the mass of fine powder), 12 tons of fly ash (accounting for 30% of the mass of fine powder), 0.4 tons of water reducing agent (accounting for 1% of the mass of fine powder), and 0.8 tons of early strength agent (accounting for 2% of the mass of fine powder) for 10 minutes, and then molded under the conditions of molding pressure 14MPa, vibration frequency 45Hz, and vibration time 5 minutes. Cured in a standard curing room for 14 days, the curing temperature was 21℃, and the relative humidity was 96%.

[0035] Recycled product production:

[0036] Preparation of recycled concrete: The replacement rate of recycled aggregate is set at 60%, 42.5 ordinary Portland cement is used, the water-cement ratio is 0.45, and an appropriate amount of air entraining agent is added to prepare 80 cubic meters of recycled concrete. After testing, the compressive strength of the concrete reaches the C35 grade and is used for the pouring of beams and slabs of a certain building.

[0037] Recycled brick production: Based on 30 tons of recycled aggregate, add 4.5 tons of cement (accounting for 15% of the recycled aggregate mass), 3 tons of lime (accounting for 10% of the recycled aggregate mass), 1.5 tons of gypsum (accounting for 5% of the recycled aggregate mass), add water and stir to form. Steam curing in a curing kiln at a temperature of 100°C for 12 hours to make 40,000 recycled bricks. After inspection, the strength grade of recycled bricks reaches MU20, which is used for non-load-bearing wall masonry of high-rise buildings.

[0038] Efficient utilization of resources: Through the fine classification, crushing, grinding and reasonable formula design of construction waste, waste concrete, bricks and stones are converted into high-quality recycled aggregates and recycled products, achieving high added value utilization of construction waste, reducing the mining of natural aggregates and saving resources.

[0039] Significant environmental benefits: It avoids random landfill and stacking of construction waste, reduces the occupation of land resources and pollution to the environment. At the same time, the recycling of wastewater in the production process reduces water resource consumption, which is in line with the development concept of green environmental protection.

[0040] Stable quality of recycled products: Strict control of process parameters in each processing link, such as crushing particle size, grinding fineness, mixing ratio, molding pressure and curing conditions, ensures the stable performance of recycled aggregates and recycled products, which can meet various quality requirements of construction projects and expand the application scope of recycled products.

[0041] Improved economic benefits: The treatment and recycling method of the present invention has a relatively simple process, low equipment investment cost, and the recycled products have certain market competitiveness, which can bring considerable economic benefits to the enterprise and promote the sustainable development of the construction waste treatment industry.

[0042] It can be seen from the above embodiments that the construction waste treatment and recycling method of the present invention can effectively convert construction waste into high-quality recycled products, meet the needs of different construction projects, and has good economic, environmental and social benefits.

[0043] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating and recycling construction waste, characterized in that: The following steps are involved: Step S1: pre-processing stage; Step S2: Crushing and grinding stage; Step S3: recycled aggregate preparation stage; Step S4: Regeneration product production stage.

2. The method for treating and recycling construction waste according to claim 1, characterized in that: The preprocessing stage in step S1 includes the following steps: 1) Classification and screening: The collected construction waste is preliminarily classified into concrete blocks, masonry, wood, metal, glass and other categories by combining manual and mechanical methods. The concrete blocks and masonry are screened by particle size using a vibrating screen. Those larger than 50mm are used as coarse aggregate raw materials, those between 10-50mm are used as fine aggregate raw materials, and those smaller than 10mm enter the subsequent grinding process; 2) Cleaning and impurity removal: The sorted concrete blocks and bricks are washed with a high-pressure water gun to remove surface impurities. The waste water after cleaning is recycled after sedimentation and filtration.

3. The method for treating and recycling construction waste according to claim 1, characterized in that: The crushing and grinding stage in step S2 includes the following steps: 1) Crushing: Use jaw crusher and cone crusher to crush the coarse aggregate raw materials in two stages, and control the discharge opening width of jaw crusher to 20-30mm and the discharge opening width of cone crusher to 10-15mm; 2) Grinding: The screened particles smaller than 10 mm and the crushed aggregates are sent to a ball mill for grinding, and a grinding aid accounting for 0.1%-0.3% of the raw material mass is added, and the powder is ground until the residue on the 80μm square hole sieve does not exceed 10%.

4. The method for treating and recycling construction waste according to claim 1, characterized in that: The recycled aggregate preparation stage in step S3 comprises the following steps: 1) Mixing and stirring: Mix the ground concrete and masonry fine powder with cement, fly ash and admixtures, with the cement added in an amount of 10%-15% of the fine powder mass, the fly ash added in an amount of 20%-30% of the fine powder mass, the water reducer added in an amount of 0.5%-1% of the fine powder mass, and the early strength agent added in an amount of 1%-2% of the fine powder mass, and stir in a forced mixer for 5-10 minutes; 2) Molding and curing: The mixed recycled aggregate blank is fed into the molding mold and molded by vibration pressure. The molding pressure is controlled at 10-15MPa, the vibration frequency is 30-50Hz, and the vibration time is 3-5 minutes. After molding, it is cured in a standard curing room with a curing temperature of 20±2℃ and a relative humidity greater than 95%. The curing time is 7-14 days.

5. The method for treating and recycling construction waste according to claim 1, characterized in that: The regeneration product production stage in step S4 includes the following steps: 1) Preparation of recycled concrete: Recycled aggregate is used as the main raw material, with a replacement rate of 30%-70% of recycled aggregate, mixed with cement, water and admixtures. The cement is ordinary Portland cement with a strength grade of 42.5, and the water-cement ratio is controlled at 0.4-0.

6. Mix well to make recycled concrete; 2) Recycled brick production: Mix the recycled aggregate with cement, lime and gypsum, with the cement addition amount being 10%-15% of the recycled aggregate mass, the lime addition amount being 5%-10% of the recycled aggregate mass, and the gypsum addition amount being 3%-5% of the recycled aggregate mass. Add water and stir evenly, then press into shape through a brick-making machine. The bricks are steam-cured in a curing kiln at a curing temperature of 80-100°C for 8-12 hours.

6. The method for treating and recycling construction waste according to claim 2, characterized in that: In the cleaning and impurity removal step, the water pressure of the high-pressure water gun is 2-5 MPa.

7. The method for treating and recycling construction waste according to claim 4, characterized in that: In the mixing and stirring step of the recycled aggregate preparation stage, other functional admixtures may be added according to actual needs.

8. The method for treating and recycling construction waste according to claim 5, characterized in that: In the recycled concrete preparation step, admixtures include water reducing agent, air entraining agent, etc., and the type and amount of admixtures are determined according to the performance requirements of the concrete.

9. The method for treating and recycling construction waste according to claim 5, characterized in that: In the regenerated brick production step, the formed bricks are naturally dried before being sent to the curing kiln, and the drying time is 1-2 days.

Images