Method for producing cement by screening and gradient utilization of construction wastes

Abstract

The invention relates to a method for screening and gradient utilization of construction waste for cement production, and belongs to the technical field of resource utilization of construction waste. The construction waste is subjected to spraying treatment through composite spraying liquid and then sequentially subjected to crushing through efficient crushing equipment, screening through multi-stage screening equipment and sorting through intelligent sorting equipment, so that metal components, light substance components, waste soil components and concrete masonry crushed aggregate components are obtained; the metal components are recycled and reused; the light substance components are conveyed into a decomposing furnace of a cement production system to be used as alternative fuel; the waste soil component and the medium-particle-size concrete masonry crushed material component are stirred and mixed to form a mixed material, and the mixed material is added into the cement raw material to serve as a siliceous and calcareous raw material; the fine-particle-size concrete masonry crushed aggregate components are deeply processed and used for cement preparation. According to the invention, effective separation of metals and impurities in the construction wastes is realized, and the recycling rate and the metal recovery rate are improved.

Description

Technical Field

[0001] This invention relates to the field of construction waste resource utilization technology, and in particular to a method for screening and cascading construction waste for use in cement production. Background Technology

[0002] With the acceleration of urbanization, the amount of construction waste generated has increased dramatically. Traditional methods of disposal of construction waste mainly involve dumping and landfilling, which not only occupy a large amount of land resources, but also cause harmful substances contained in the waste to seep into and pollute the soil and groundwater. Furthermore, the methane and other gases produced by the decomposition of organic matter during landfilling exacerbate the greenhouse effect, posing a serious and lasting threat to the ecological environment.

[0003] As a vital foundational industry of the national economy, the cement industry is also a major consumer of raw materials and energy, requiring large quantities of natural mineral resources such as limestone and clay annually. Its production process also faces the dual challenges of resource depletion and environmental pressure. Using construction waste as an alternative raw material or fuel for cement production can provide a large-scale solution for construction waste disposal and reduce the cement industry's dependence on natural resources.

[0004] Chinese Patent CN114988783A: Provides a clinker-free cement concrete based on construction waste proportioning and its preparation method. The chemical composition of the clinker-free cement concrete based on construction waste proportioning is: waste concrete, clinker-free cement, sand, crushed stone, concrete enhancer, antifreeze agent, waterproofing agent, rust inhibitor, water-reducing agent and water. The method involves crushing the waste concrete generated from the demolition of old buildings, screening the crushed concrete to separate concrete crushed materials of different specifications, calcining and reprocessing the concrete crushed materials with smaller particle sizes, and grinding the calcined and reprocessed concrete crushed materials to replace cement.

[0005] Chinese Patent CN117265964A: This patent relates to the field of road construction technology, and in particular to a road construction process based on recycled cement from construction waste. The technical solution includes: S1, collection and sorting of construction waste; S2, preparation of cold recycled mixture; S3, carbonation and harm reduction treatment; S4, preparation of recycled cement; S5, road base construction; and S6, concrete surface modification.

[0006] Existing technologies that use crushed construction waste as concrete aggregate or cement production substitutes have several drawbacks: incomplete separation of metals and impurities from construction waste, low resource utilization and metal recovery rates, and poor economic viability. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a method for the tiered screening and utilization of construction waste in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is first treated by spraying with a composite spray liquid, and then successively crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragments; the composite spray liquid is made by pretreatment and mixing reaction of alcohol amine wastewater and pulp and paper white mud. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0008] As one of the preferred methods, the high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 80-120mm.

[0009] As one of the preferred methods, the spraying of the composite spray liquid is divided into two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.3%-0.5% of the mass of the construction waste raw material, and the spraying is left to stand for 5-8 minutes after spraying. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 50-100μm.

[0010] As one of the preferred methods, the multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are fine particle size 1-5mm, medium particle size 5-20mm, and coarse particle size 20-50mm, wherein the coarse particle size crushed material is returned to the high-efficiency crushing equipment for further crushing.

[0011] As one of the preferred methods, the vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 15-20Hz and an amplitude of 5-10mm.

[0012] As a preferred embodiment, the intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic field strength of the magnetic separator is 10,000-15,000 kgs, used to separate metals from construction waste. The air velocity of the air separator is controlled at 15-25 m / s, used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0013] As one of the preferred methods, the mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:3-1:5.

[0014] As one of the preferred methods, the deep processing of the fine-particle-size concrete masonry aggregate component includes grinding, impurity removal, and homogenization treatment, and the specific surface area of ​​the powder after treatment is 350-450m² / kg.

[0015] As one of the preferred methods, the preparation steps of the composite spray liquid are as follows: A1 Alkylamine Wastewater Pretreatment: 100-mesh filter screen is used to remove suspended impurities from the alkylamine wastewater; A2 Pulping and Papermaking White Mud Pretreatment: The pulping and papermaking white mud is dried using the residual heat of the cement kiln tail, and then crushed to a particle size of 0.06-0.075mm. A3 Mixing reaction: Mix 80-100 parts of pretreated amine wastewater and 10-15 parts of pulping and papermaking sludge, and stir and react at room temperature to obtain a composite spray solution.

[0016] As one of the preferred methods, the A3 reaction time is 25-30 minutes.

[0017] Reaction mechanism: Chemical synergistic reaction mechanism: The hydroxyl and amino components in amine wastewater can undergo neutralization and complexation reactions with calcium carbonate and magnesium hydroxide in pulp and paper sludge to generate surface-active soluble organic salts. These organic salts can reduce the interfacial tension between the components of construction waste, weaken the material's binding force, prevent material agglomeration during crushing, and create favorable conditions for the effective separation of subsequent components.

[0018] Technical effect The lubricating and penetrating effects of the composite spray liquid can reduce the ineffective energy consumption of the crushing equipment during operation, make the particle size of the crushed material more uniform, reduce the need for coarse particles to be returned for secondary crushing, thereby reducing the workload of the subsequent screening process and improving the overall processing efficiency.

[0019] The organic salts generated by the reaction can form a protective film on the inner wall of the crushing equipment. This protective film can reduce the impact and wear of the material on the vulnerable parts of the equipment and extend the service life of the equipment. At the same time, the unreacted silicon and calcium components in the pulp and paper white mud will enter the cement raw material system with the material, directly supplementing the silicon and calcium raw materials required for the raw material, realizing the resource-based synergistic utilization of industrial waste. The whole process will not generate secondary waste and meets environmental protection requirements.

[0020] This invention enables different components of construction waste to play their respective roles through targeted treatment and tiered utilization, effectively separating metals and impurities from construction waste, significantly improving the resource utilization rate of construction waste and the metal recovery rate, and enhancing the overall economic and environmental benefits of the process. Attached Figure Description

[0021] Figure 1 The raw materials are those used in Example 1.

[0022] Figure 2 This is the sample after sieve cascade utilization in Example 1. Detailed Implementation

[0023] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description is provided in conjunction with embodiments and comparative examples: The raw material construction waste components are: 1. Resource utilization rate: Calculated according to the formula: Resource utilization rate = (M total - M residual) / M total × 100%; where M total is the total mass of construction waste and M residual is the mass of unusable residue a.

[0024] 2. Metal recovery rate: Calculated according to the formula: Metal recovery rate = Mgold_recovered / Mtotal × 100%; where Mtotal is the total amount of metal originally in the construction waste, and Mgold_recovered is the mass of recovered metal.

[0025] The white mud came from a paper mill in Lanxi; the amine wastewater came from the Lanxi Economic Development Zone. Example 1

[0026] A method for screening and cascading construction waste for use in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is first treated by spraying with a composite spray liquid, and then successively crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragments; the composite spray liquid is made by pretreatment and mixing reaction of alcohol amine wastewater and pulp and paper white mud. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0027] The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 120mm.

[0028] The composite spray liquid is sprayed in two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.3% of the mass of the construction waste raw material. After spraying, the mixture is left to stand for 5 minutes. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 100μm.

[0029] The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are 5mm fine particle size, 20mm medium particle size, and 50mm coarse particle size, respectively. The coarse particle size crushed material is returned to the high-efficiency crushing equipment for further crushing.

[0030] The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 15Hz and an amplitude of 5mm.

[0031] The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic separator has a magnetic field strength of 10,000 kgs and is used to separate metals from construction waste. The air separator has a wind speed controlled at 15 m / s and is used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0032] The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:3.

[0033] The deep processing of the fine-particle-size concrete masonry aggregate component includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 350 m² / kg.

[0034] The preparation steps of the composite spray liquid are as follows: A1 Alkylamine Wastewater Pretreatment: 100-mesh filter screen is used to remove suspended impurities from the alkylamine wastewater; A2 Pulping and Papermaking White Mud Pretreatment: The pulping and papermaking white mud is dried using the residual heat of the cement kiln tail and then crushed to a particle size of 0.075mm. A3 Mixing reaction: 80 kg of pretreated amine wastewater and 10 kg of pulp and paper white mud are mixed and stirred at room temperature to obtain a composite spray solution.

[0035] The reaction time for A3 is 25 minutes. Example 2

[0036] A method for screening and cascading construction waste for use in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is first treated by spraying with a composite spray liquid, and then successively crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragments; the composite spray liquid is made by pretreatment and mixing reaction of alcohol amine wastewater and pulp and paper white mud. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0037] The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 110mm.

[0038] The composite spray liquid is sprayed in two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.4% of the mass of the construction waste raw material, and the spraying is left to stand for 6 minutes after spraying. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 90μm.

[0039] The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are 4mm for fine particles, 15mm for medium particles, and 40mm for coarse particles. The coarse particles are returned to the high-efficiency crushing equipment for further crushing.

[0040] The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 15Hz and an amplitude of 5mm.

[0041] The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic field strength of the magnetic separator is 11,000 kgs, used to separate metals from construction waste. The air speed of the air separator is controlled at 20 m / s, used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0042] The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:4.

[0043] The deep processing of the fine-particle-size concrete masonry aggregate component includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 400 m² / kg.

[0044] The preparation steps of the composite spray liquid are as follows: A1 Alkylamine Wastewater Pretreatment: 100-mesh filter screen is used to remove suspended impurities from the alkylamine wastewater; A2 Pulping and Papermaking White Mud Pretreatment: The pulping and papermaking white mud is dried using the residual heat of the cement kiln tail and then crushed to a particle size of 0.07mm. A3 Mixing Reaction: 85 kg of pretreated amine wastewater and 11 kg of pulping and papermaking sludge are mixed and stirred at room temperature to obtain a composite spray solution.

[0045] The reaction time for A3 is 25 minutes. Example 3

[0046] A method for screening and cascading construction waste for use in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is first treated by spraying with a composite spray liquid, and then successively crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragments; the composite spray liquid is made by pretreatment and mixing reaction of alcohol amine wastewater and pulp and paper white mud. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0047] The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 90mm.

[0048] The composite spray liquid is sprayed in two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.4% of the mass of the construction waste raw material, and the spraying is left to stand for 7 minutes after spraying. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 60μm.

[0049] The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are 2mm for fine particles, 10mm for medium particles, and 30mm for coarse particles. The coarse particles are returned to the high-efficiency crushing equipment for further crushing.

[0050] The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 20Hz and an amplitude of 10mm.

[0051] The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic field strength of the magnetic separator is 14,000 kgs, used to separate metals from construction waste. The air speed of the air separator is controlled at 20 m / s, used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0052] The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:4.

[0053] The deep processing of the fine-particle-size concrete masonry aggregate component includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 400 m² / kg.

[0054] The preparation steps of the composite spray liquid are as follows: A1 Alkylamine Wastewater Pretreatment: 100-mesh filter screen is used to remove suspended impurities from the alkylamine wastewater; A2 Pulping and Papermaking White Sludge Pretreatment: The pulping and papermaking white sludge is dried using the residual heat of the cement kiln tail and then crushed to a particle size of 0.065mm. A3 Mixing reaction: 95 kg of pretreated amine wastewater and 14 kg of pulp and paper white mud are mixed and stirred at room temperature to obtain a composite spray solution.

[0055] The reaction time for A3 is 30 minutes. Example 4

[0056] A method for screening and cascading construction waste for use in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is first treated by spraying with a composite spray liquid, and then successively crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragments; the composite spray liquid is made by pretreatment and mixing reaction of alcohol amine wastewater and pulp and paper white mud. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0057] The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 80mm.

[0058] The composite spray liquid is sprayed in two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.5% of the mass of the construction waste raw material, and the mixture is left to stand for 8 minutes after spraying. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 50μm.

[0059] The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are 1mm fine particle size, 5mm medium particle size, and 20mm coarse particle size, respectively. The coarse particle size crushed material is returned to the high-efficiency crushing equipment for further crushing.

[0060] The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 20Hz and an amplitude of 10mm.

[0061] The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic field strength of the magnetic separator is 15,000 kgs, used to separate metals from construction waste. The air speed of the air separator is controlled at 25 m / s, used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0062] The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:5.

[0063] The deep processing of the fine-particle-size concrete masonry aggregate includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 450 m² / kg.

[0064] The preparation steps of the composite spray liquid are as follows: A1 Alkylamine Wastewater Pretreatment: 100-mesh filter screen is used to remove suspended impurities from the alkylamine wastewater; A2 Pulping and Papermaking White Mud Pretreatment: The pulping and papermaking white mud is dried using the residual heat of the cement kiln tail and then crushed to a particle size of 0.06mm. A3 Mixing reaction: 100 kg of pretreated amine wastewater and 15 kg of pulp and paper white mud are mixed and stirred at room temperature to obtain a composite spray solution.

[0065] The reaction time for A3 is 30 minutes.

[0066] Comparative Example 1 A method for screening and cascading construction waste for use in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is sequentially crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragment components. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0067] The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 120mm.

[0068] The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are 5mm fine particle size, 20mm medium particle size, and 50mm coarse particle size, respectively. The coarse particle size crushed material is returned to the high-efficiency crushing equipment for further crushing.

[0069] The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 15Hz and an amplitude of 5mm.

[0070] The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic separator has a magnetic field strength of 10,000 kgs and is used to separate metals from construction waste. The air separator has a wind speed controlled at 15 m / s and is used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0071] The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:3.

[0072] The deep processing of the fine-particle-size concrete masonry aggregate component includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 350 m² / kg.

[0073] Comparative Example 2 A method for screening and cascading construction waste for use in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is first treated by spraying with a spraying liquid, and then successively crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragment components. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0074] The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 120mm.

[0075] The spraying of the spray liquid is divided into two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.3% of the mass of the construction waste raw material, and the spraying is left to stand for 5 minutes after spraying. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 100μm.

[0076] The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are 5mm fine particle size, 20mm medium particle size, and 50mm coarse particle size, respectively. The coarse particle size crushed material is returned to the high-efficiency crushing equipment for further crushing.

[0077] The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 15Hz and an amplitude of 5mm.

[0078] The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic separator has a magnetic field strength of 10,000 kgs and is used to separate metals from construction waste. The air separator has a wind speed controlled at 15 m / s and is used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0079] The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:3.

[0080] The deep processing of the fine-particle-size concrete masonry aggregate component includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 350 m² / kg.

[0081] The spray solution is an alcohol amine wastewater.

[0082] Comparative Example 3 A method for screening and cascading construction waste for use in cement production, the operation steps of which are as follows: S1 Construction Waste Screening: Construction waste is first treated by spraying with a spraying liquid, and then successively crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragment components. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system for use as alternative fuel; the waste soil components and medium-sized concrete brick and stone crushed materials are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; and the fine-sized concrete brick and stone crushed materials are further processed for use in cement preparation.

[0083] The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 120mm.

[0084] The spraying of the spray liquid is divided into two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.3% of the mass of the construction waste raw material, and the spraying is left to stand for 5 minutes after spraying. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 100μm.

[0085] The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are 5mm fine particle size, 20mm medium particle size, and 50mm coarse particle size, respectively. The coarse particle size crushed material is returned to the high-efficiency crushing equipment for further crushing.

[0086] The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 15Hz and an amplitude of 5mm.

[0087] The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic separator has a magnetic field strength of 10,000 kgs and is used to separate metals from construction waste. The air separator has a wind speed controlled at 15 m / s and is used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

[0088] The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:3.

[0089] The deep processing of the fine-particle-size concrete masonry aggregate component includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 350 m² / kg.

[0090] The spraying liquid is obtained by mixing 10 kg of pulp and paper white mud and 80 kg of water.

[0091] Table 1. Test results of resource recovery rate and metal recovery rate of construction waste in the examples and comparative examples. Resource utilization rate / % Metal recovery rate / % Example 1 98.39 99.87 Example 2 98.43 99.91 Example 3 98.51 99.98 Example 4 98.55 100 Comparative Example 1 75.37 84.52 Comparative Example 2 92.63 94.46 Comparative Example 3 93.36 95.11 Comparing the resource recovery rate and metal recovery rate of the embodiments and comparative examples in the data table, the resource recovery rate and metal recovery rate of the embodiments of the present invention are significantly higher than those of the comparative examples. Specifically, Comparative Example 1, which did not use the composite spray solution, had both indicators far lower than those of the embodiments. Comparative Examples 2 and 3, which used a mixture of single-aluminol amine wastewater or pulp and paper sludge with water as the spray solution, had both indicators higher than those of Comparative Example 1, but still lower than those of the embodiments. This result fully demonstrates that the composite spray solution prepared by pretreatment and mixing of alkanol amine wastewater and pulp and paper sludge, combined with subsequent high-efficiency crushing, multi-stage screening, and intelligent sorting processes, can effectively solve the problem of incomplete metal and impurity sorting in construction waste in existing technologies, effectively improving the resource recovery rate and metal recovery rate of construction waste, and verifying the superiority and effectiveness of the technical solution of the present invention.

[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for screening and cascading construction waste for use in cement production, comprising the following steps: S1 Construction Waste Screening: After being treated by spraying with a composite spray liquid, the construction waste is then crushed by high-efficiency crushing equipment, screened by multi-stage screening equipment, and sorted by intelligent sorting equipment to obtain metal components, light material components, waste soil components, and concrete brick and stone fragments; the composite spray liquid is made by pretreatment and mixing of alcohol amine wastewater and pulp and paper white mud. S2 cascade utilization: The metal components are recycled and reused; the light material components are transported to the decomposition furnace of the cement production system and used as alternative fuels; the waste soil components and medium-sized concrete brick and stone crushed components are mixed to form a mixture, which is then added to the cement raw materials as siliceous and calcareous raw materials; the fine-sized concrete brick and stone crushed components are further processed for use in cement preparation. The composite spray solution is prepared from amine wastewater and pulp and paper white mud.

2. The method for screening and cascading construction waste for cement production according to claim 1, characterized in that: The high-efficiency crushing equipment is a combination of a jaw crusher and an impact crusher, and the particle size of the crushed construction waste is 80-120mm.

3. The method for screening and cascading construction waste for cement production according to claim 1, characterized in that: The composite spray liquid is sprayed in two stages. The first stage is spraying before the jaw crusher feeds, with a spray volume of 0.3%-0.5% of the mass of the construction waste raw material. After spraying, the material is left to stand for 5-8 minutes. The second stage is mist spraying at the feed chute of the impact crusher, with a droplet diameter of 50-100μm.

4. A method for the tiered utilization of construction waste in cement production according to claim 1, characterized in that: The multi-stage screening equipment includes three layers of screening screens. The particle size specifications of the concrete masonry crushed material components obtained after screening are fine particles of 1-5mm, medium particles of 5-20mm, and coarse particles of 20-50mm. The coarse particles are returned to the high-efficiency crushing equipment for further crushing.

5. A method for the tiered utilization of construction waste in cement production according to claim 1, characterized in that: The vibrating screen of the multi-stage screening equipment is an eccentric shaft vibrating screen with a vibration frequency of 15-20Hz and an amplitude of 5-10mm.

6. A method for screening and cascading construction waste for cement production according to claim 1, characterized in that: The intelligent sorting equipment includes a magnetic separator, an air separator, and a photoelectric separator, with magnetic separation, air separation, and photoelectric separation performed sequentially. The magnetic field strength of the magnetic separator is 10,000-15,000 kgs, used to separate metals from construction waste. The air velocity of the air separator is controlled at 15-25 m / s, used to separate lightweight materials such as plastics and wood. The photoelectric separator further separates residual impurities by identifying differences in material color and density.

7. A method for the tiered utilization of construction waste in cement production according to claim 1, characterized in that: The mixing mass ratio of the waste soil component and the medium-sized concrete masonry component is 1:3-1:

5.

8. A method for screening and cascading construction waste for cement production according to claim 1, characterized in that: The deep processing of the fine-particle-size concrete masonry aggregate includes grinding, impurity removal, and homogenization. The specific surface area of ​​the powder after processing is 350-450 m² / kg.

9. A method for the tiered utilization of construction waste in cement production according to claim 1, characterized in that: The preparation steps of the composite spray liquid are as follows: A1 Alkylamine Wastewater Pretreatment: 100-mesh filter screen is used to remove suspended impurities from the alkylamine wastewater; A2 Pulping and Papermaking White Mud Pretreatment: The pulping and papermaking white mud is dried using the residual heat of the cement kiln tail, and then crushed to a particle size of 0.06-0.075mm. A3 Mixing reaction: Mix 80-100 parts of pretreated amine wastewater and 10-15 parts of pulping and papermaking sludge, and stir and react at room temperature to obtain a composite spray solution.

10. A method for screening and cascading construction waste for cement production according to claim 9, characterized in that: The reaction time of A3 is 25-30 minutes.

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