A slag fully-closed resource processing and zero-emission water circulation process

Abstract

The application discloses a slag full-closed resource treatment and zero-emission water circulation process, and belongs to the technical field of solid waste treatment and waste water zero-emission. The process comprises the following steps: after the slag is subjected to spray dust suppression and negative pressure air extraction purification treatment in a closed storage area, the slag is subjected to closed conveying and then subjected to screening and crushing, first-stage magnetic separation of iron, jigger gravity separation and auxiliary separation, vibration table separation and second-stage magnetic separation, two-stage eddy current separation for purifying metal aluminum and copper crushing and water sand separation; waste water generated in the separation is subjected to multi-stage treatment of precipitation, coagulation precipitation and filtration, and then is all reused in each production process; fine sand is sent to a sealed water draining area after grading, and is naturally drained until the water content is lower than 20%; after the sludge is subjected to pressure filtration dewatering, the mud cake is transported out for resource utilization; all of initial rainwater, flushing water and drained water in the factory area are collected and merged into a water treatment system for unified reuse. The application realizes efficient recovery of valuable metals in the slag, accurate control of water content of the recycled aggregate and zero-emission of production water.

Description

Technical Field

[0001] This invention relates to the field of solid waste treatment and zero wastewater discharge technology, specifically a fully enclosed resource utilization treatment and zero-discharge water recycling process for slag. Background Technology

[0002] With the widespread application of municipal solid waste incineration power generation technology, the amount of incinerator slag produced is increasing year by year. Slag contains valuable metals such as iron, copper, and aluminum, as well as aggregates that can be used in building materials production, and has high resource utilization value.

[0003] Currently, most slag treatment processes employ wet separation methods, generating large amounts of wastewater containing suspended solids and dissolved pollutants. While existing technologies include methods such as magnetic separation, jigging, and eddy current separation for recovering valuable metals from slag, and devices for graded sedimentation treatment of slag water, none of these systematically address the following technical issues: 1. Traditional processing methods often employ open-air operations, resulting in severe dust and noise pollution, harsh working environments, and difficulties in meeting environmental standards. Significant dust emission problems exist at raw material storage yards, conveyor belt transfer points, and crushing and screening stages.

[0004] 2. High water consumption in production and rudimentary wastewater treatment methods. Although some improved processes have added sedimentation tanks, they only achieve simple settling and cannot achieve deep purification and recycling of water, leading to scaling, pipe blockage, and unstable operation. Large amounts of muddy wastewater are discharged, causing secondary pollution and serious waste of water resources.

[0005] 3. Low sorting accuracy and low metal recovery rate. If aluminum in the slag is not effectively separated, it will directly affect the strength and durability of the finished building materials made from recycled aggregates. Existing single-stage eddy current separation processes are insufficient to achieve efficient aluminum purification.

[0006] 4. The moisture content of the finished aggregate fluctuates greatly, requiring secondary stacking and drying before downstream use, which increases additional energy consumption and site costs.

[0007] 5. The mud generated during the sorting process lacks effective ways to be utilized as a resource and is usually disposed of as waste, causing secondary pollution and waste of resources. Summary of the Invention

[0008] The purpose of this invention is to provide a fully enclosed resource-based treatment and zero-discharge water recycling process for slag. The aim is to achieve clean and resource-based treatment of slag and zero discharge of production water by constructing a fully enclosed operating environment, a multi-stage water treatment system, and optimizing the graded sorting process.

[0009] The process includes the following steps: (1) Layout of the work area and closed storage pretreatment: High-noise equipment is placed in the sunken work area and vibration reduction measures are taken. The material is transported from top to bottom by utilizing the elevation difference between the processing units. The slag raw material is unloaded into a closed storage area with sound-absorbing enclosure for atomized spraying to suppress dust. The spray water comes from the subsequent water treatment and reuse system. The storage area is maintained in a slightly negative pressure state. The extracted gas is discharged after being treated by dust removal, adsorption and photocatalysis. The drain water at the bottom of the storage area is collected into the circulating water collection system. (2) Closed-loop feeding and grading crushing: The slag in the storage area is screened through a closed conveyor. The material on the screen is picked out to remove impurities, and the material under the screen is sent to the crushing process. After crushing, the material reaches the set particle size. The entire feeding, screening and crushing process is carried out in a closed working space with sound absorption measures. The generated dust is collected and enters the dust removal system. (3) Pre-magnetic separation and iron separation After crushing, the material undergoes a primary magnetic separation process, where magnetic materials are separated and collected separately, while non-magnetic materials enter the next process. (4) Jigging and auxiliary sorting: Non-magnetic materials enter the jigging separation process, and the jigging water is recycled clean water. The jigging frequency and amplitude are controlled. The upper layer of light materials after jigging is separated by auxiliary separation to remove incompletely burned raw materials, and the lower layer of heavy materials is separated by auxiliary separation to remove solid iron blocks and other iron blocks. The wastewater generated by jigging is collected in the wastewater equalization tank. (5) Vibrating bed separation and secondary magnetic separation: The intermediate products after jigging are fed into a vibrating bed for separation, with the frequency of the vibrating bed controlled. The material after vibrating bed separation is then subjected to a secondary magnetic separation to recover residual magnetic particles. The wastewater generated by the vibrating bed separation and the secondary magnetic separation is collected in a wastewater equalization tank. (6) Two-stage eddy current separation for aluminum extraction: After the secondary magnetic separation, the material enters the eddy current separator, which adopts a two-stage series mode, with the working frequency and magnetic field strength set separately. After separation, aluminum products are obtained, while ensuring that the aluminum content in the tailings is lower than the set threshold. The wastewater generated in this process is collected into the wastewater equalization tank. (7) Copper crushing and water-sand separation: After eddy current separation, the coarse sand enters the copper crushing process. After being crushed to the set particle size, it enters the water-sand separation process to separate the copper particles from the fine sand and collect the copper products separately. The wastewater generated by the water-sand separation is collected in the sewage equalization tank. (8) Multi-stage water treatment and recycling: The mixed wastewater in the sewage equalization tank is subjected to sedimentation treatment, coagulation sedimentation treatment and filtration treatment in sequence. After the treated water meets the reuse standard, it is all reused for the spray water in process (1), the jigging water in process (4), the vibrating bed water in process (5), the eddy current separation water in process (6) and the copper crushing and cooling water in process (7). (9) Fine sand classification and finished product moisture content control: After water and sand separation, the fine sand is sent to the grading process and divided into different grades according to particle size; the graded recycled aggregate is sent to the sealed dewatering area for natural dewatering, and the moisture content of the recycled aggregate after dewatering is lower than the set value; the dewatered water is returned to the sewage equalization tank. (10) Slurry filtration and resource utilization: The sediment discharged in process (8) and the fine sludge collected in process (9) are concentrated for filter press dewatering. The moisture content of the filter cake after filter press is controlled within the set value. The filtrate generated by filter press is returned to the sewage equalization tank for reprocessing. The dewatered filter cake is transported off-site for resource utilization. (11) Integration of water resources across the entire region: All initial rainwater, washing water from various areas, aggregate drain water, and equipment cooling water in the factory area are collected and fed into the sewage regulating tank. They are then treated together with the production wastewater in process (8) and reused in a unified manner to ensure that no wastewater is discharged from the factory area. (12) Closed-loop transfer of finished metal products: The sorted iron, copper, aluminum and their alloy products are all transferred to the finished product area in a closed environment.

[0010] Preferably, in step (1), the spray water volume of the atomizing spray is 0.5 to 1.5 m³ per ton of slag. 3 Spray pressure 0.2~0.4MPa; in process (2), the screening adopts a screen with a screen hole of 60~80mm, the particle size of the crushed material is ≤40mm, and the crushing level does not exceed three levels; in process (3), the magnetic field strength of the first-level magnetic separation is ≥3000Gs, and the magnetic field strength of the second-level magnetic separation in process (5) is ≥2500Gs; in process (4), the jigging frequency is 300~400 times / min, the amplitude is 10~15mm, the feed concentration is 20%~30%, and the water-to-material ratio is (3~5):1; in process (6), the first stage of the two-stage eddy current separation has a working frequency of 40~60Hz and a magnetic field strength of 4000~5000Gs, and the second stage has a working frequency of 70~90Hz and a magnetic field strength of 6000~7000Gs; in process (7), the particle size of the crushed copper is ≤10mm.

[0011] Preferably, in the two-stage eddy current separation process (6), the aluminum concentrate obtained after the first stage separation enters the second stage separation, and the tailings from the second stage separation are returned to the first stage feed inlet for recycling separation.

[0012] Preferably, in step (8), the hydraulic retention time of the sedimentation treatment is ≥3h; in the coagulation sedimentation treatment, 10-30mg / L of polyaluminum chloride and 0.5-2mg / L of polyacrylamide are added, and after the reaction, the mixture enters the secondary sedimentation tank with a hydraulic retention time of 2-4h; the filtration treatment adopts multi-media filtration with a filtration accuracy of ≤10μm; after treatment, the water is reused after the SS index reaches ≤10mg / L, COD ≤30mg / L, and turbidity ≤5NTU.

[0013] Preferably, during the coagulation and sedimentation treatment, acid or alkali adjusters are added according to the pH value of the wastewater to maintain the reaction pH at 6.5~8.0; when the heavy metal ions in the wastewater exceed the standard, heavy metal scavenging agents are added simultaneously.

[0014] Preferably, the sealing and draining area in process (9) is divided into multiple zones, which are stored according to the aggregate particle size. The draining time of different zones is adjusted independently. The draining time of the coarse sand zone is ≥36h, and the draining time of the fine sand zone is ≥60h. During the draining period, the temperature inside the silo is kept ≤30℃ and the relative humidity is kept ≤60%. The set value of the moisture content at the factory is 20%.

[0015] Preferably, in the process (10), the filter press is a plate and frame filter press with a feed pressure ≥ 0.6 MPa, a filter press cycle ≤ 60 min, and a filter cake moisture content ≤ 60%. Before filter press, lime or polyacrylamide is added to the slurry as a filter aid, and the amount added is 0.5% to 2% of the slurry dry solids.

[0016] As a preferred option, all waste gas generated during the entire process is introduced into a central dust removal system through a gas collection pipeline, and is treated by a combination of bag filtration, activated carbon adsorption and ultraviolet photocatalysis to meet emission standards.

[0017] As a preferred option, when the process is first run, clean water is injected as the initial circulating water. Subsequently, only the water lost due to mud cake and evaporation is replenished, and the amount of water replenished does not exceed 5% of the total circulating water. The dust collected by the dust removal system in step (2) is returned to the jigging feed inlet of step (4), mixed with the jigging feed, and then re-enters the sorting process.

[0018] As a preferred option, the fine sand separated in step (7) is graded and collected into three grades: coarse sand, medium sand, and fine sand, and used to prepare recycled building materials of different specifications. The mud cake after dehydration in step (10) is sent to a cement plant as a raw material admixture or used to produce lightweight wall panels. The magnetic material separated in step (3) is crushed and then magnetically separated again to separate refined iron, large iron blocks and stainless steel, which are collected as finished metal products.

[0019] In summary, due to the adoption of the above-mentioned technologies, the beneficial effects of this invention are: 1. This invention achieves synergistic control of dust, noise, and odor by fully sealing the production area and adding sound-absorbing enclosures, atomized spray dust suppression, bag dust collection, activated carbon adsorption, and ultraviolet photocatalysis.

[0020] 2. This invention constructs a multi-stage water treatment system of sedimentation, coagulation sedimentation and filtration, combined with a whole-area water resource integration system, to uniformly recycle, treat and reuse production wastewater, initial rainwater, storage drainage and aggregate drain water, etc., truly achieving zero discharge of production water; 3. This invention achieves efficient graded recycling of valuable metals such as iron, stainless steel, copper, and aluminum through a process combining pre-magnetic separation, secondary magnetic separation, and two-stage eddy current separation, thereby increasing the added value of resources and avoiding the impact of aluminum on the quality of finished building materials. 4. This invention completes the particle size classification and gradation optimization of aggregates through a water-sand separation system; through natural drainage in the sealed drainage zone and independent zone control, it ensures that the moisture content at the factory is less than 20%, so that downstream customers can use it directly without secondary stacking and drying. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention, making other features, objects, and advantages of the invention more apparent. The illustrative embodiments of the invention illustrated in the drawings and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] In the description of this invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing the invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0024] Example 1

[0025] This embodiment uses slag from a municipal solid waste incineration power plant as raw material, with a daily slag processing capacity of 500 tons, and is implemented according to the following steps: (1) Layout of the work area and closed storage pretreatment: High-noise equipment such as jigs and crushers are arranged in the sunken work area and equipped with shock-absorbing pads. Each processing unit is arranged in descending order according to the natural elevation difference of the site to achieve gravity-flow conveying of materials from top to bottom. The slag raw material is unloaded into a closed storage area equipped with sound-absorbing panels. The storage area is equipped with an atomizing spray system with a spray pressure of 0.3MPa and a spray water volume of 1.0m³. 3 / t of slag. The storage area is maintained at a slight negative pressure (-50Pa). The extracted gas is discharged after being treated by a combination of bag filter dust collection, activated carbon adsorption, and ultraviolet photocatalysis (wavelength 254nm). Drainage from the bottom of the storage area is collected into the circulating water collection system through drainage ditches.

[0026] (2) Enclosed feeding and grading crushing: The slag in the storage area is sent to the primary vibrating screen (80mm screen hole) via an enclosed belt conveyor. The material over the screen (80mm) enters the manual sorting platform to pick out large debris; the material under the screen (≤80mm) is sent to the jaw crusher for secondary crushing to ≤40mm. The entire feeding, screening and crushing process is carried out in a closed workshop. The workshop walls are equipped with sound-absorbing panels. The generated dust is sent to the bag filter through the dust collection pipe and the collected dust is returned to the jigging sorting feed inlet.

[0027] (3) Pre-magnetic separation and iron separation: After crushing, the material is conveyed by a belt conveyor through a first-stage permanent magnet drum magnetic separator (magnetic field strength 3500Gs). Magnetic materials (refined iron, large iron blocks, stainless steel) are separated and collected separately, while non-magnetic materials enter the jigging separation process.

[0028] (4) Jigging and auxiliary separation: Non-magnetic materials enter the jigging separator. The jigging water is recycled clean water with a feed concentration of 25%, a jigging frequency of 350 times / min, an amplitude of 12mm, and a water-to-material ratio of 4:1. The upper layer of light materials after jigging is manually sorted to separate incompletely burned raw materials (returned to the incinerator), and the lower layer of heavy materials is manually sorted to separate solid iron blocks and other iron blocks (entering the iron crushing process). The wastewater generated by jigging is collected in the wastewater equalization tank.

[0029] (5) Vibrating bed separation and secondary magnetic separation: The intermediate product after jigging is fed into a vibrating bed separator with a vibration frequency of 450 times / min. The material after vibrating bed separation is then subjected to a secondary magnetic separator (magnetic field strength 2600Gs) to recover residual magnetic particles. Wastewater generated from vibrating bed separation and secondary magnetic separation is collected in a wastewater equalization tank.

[0030] (6) Two-stage eddy current separation for aluminum extraction: The material after two-stage magnetic separation enters a two-stage eddy current separation system. The first-stage eddy current separator operates at a frequency of 50Hz and a magnetic field strength of 4500Gs, used for roughing; the second-stage eddy current separator operates at a frequency of 80Hz and a magnetic field strength of 6500Gs, used for cleaning. The aluminum concentrate obtained after the first-stage separation enters the second-stage separation, and the tailings from the second-stage separation are returned to the first-stage feed inlet for recycling. After two-stage separation, aluminum products are obtained (purity 97.5%, recovery rate 70%), and the aluminum content in the tailings is reduced to 0.4%. The wastewater generated in this process is collected in a wastewater equalization tank.

[0031] (7) Copper crushing and water-sand separation: The coarse sand after eddy current separation enters the copper crusher and is crushed to ≤10mm. Then it enters the water-sand separator, where water is used to separate the copper particles from the fine sand. The copper product is collected separately (recovery rate 46%). The wastewater generated by water-sand separation is collected in the sewage equalization tank.

[0032] (8) Multi-stage water treatment and recycling: Mixed wastewater in the sewage equalization tank (volume 500m³) 3 Perform the following processes sequentially: (8a) Sedimentation treatment: Wastewater enters the primary sedimentation tank, with a hydraulic retention time of 4 hours to remove large suspended solids, and bottom sludge is discharged periodically; (8b) Coagulation and sedimentation treatment: The supernatant from the primary sedimentation tank enters the coagulation reaction tank, and 20 mg / L of polyaluminum chloride and 1.2 mg / L of polyacrylamide are added. The alkaline solution is automatically added according to the pH value of the wastewater to maintain the reaction pH at 7.0~7.5. After the reaction, it enters the secondary sedimentation tank with a hydraulic retention time of 3 hours. (8c) Filtration treatment: The supernatant from the secondary sedimentation tank enters a multi-media filter (filled with quartz sand and anthracite, with a filtration accuracy of 5μm). (8d) After treatment, the clear water enters the clear water tank. The water quality indicators are SS=8mg / L, COD=25mg / L, and turbidity=4NTU. All of it is recycled for the spray water in process (1), the jigging water in process (4), the vibrating bed water in process (5), the eddy current separation water in process (6), and the copper crushing and cooling water in process (7).

[0033] (9) Fine sand grading and finished product moisture content control: The fine sand after water-sand separation is sent to a grading screen and divided into three grades: coarse sand, medium sand, and fine sand according to particle size. The graded recycled aggregates are stored in different sections of the sealed drainage area. The coarse sand area is drained for 40 hours, the medium sand area for 55 hours, and the fine sand area for 72 hours. During the drainage period, the temperature inside the storage area is maintained at 28℃ and the relative humidity at 55%. The moisture content of the finished product after drainage is tested: coarse sand 17%, medium sand 18%, and fine sand 19%, all below 20%. The drained water is returned to the wastewater equalization tank through the bottom diversion channel.

[0034] (10) Sludge filtration and resource utilization: The sludge discharged from the primary and secondary sedimentation tanks and the fine-particle sludge collected from the drainage ditch are concentrated and fed into a plate and frame filter press. Lime is added to the sludge before feeding (the amount added is 1.0% of the dry solids of the sludge). The feeding pressure is 0.7 MPa, the filtration cycle is 50 min, and the moisture content of the sludge cake after filtration is 56%. The filtrate produced by filtration is returned to the wastewater equalization tank for reprocessing. The dewatered sludge cake is transported to the cement plant as a raw material admixture.

[0035] (11) Integration of water resources across the entire area: The initial rainwater collection pond, fire water pond, surface washing water of each storage area, aggregate drainage ditch and equipment cooling water in the plant area are all collected through the diversion ditch and flowed into the sewage regulating pond. They are then treated together with the production wastewater in process (8) and reused in a unified manner. After 30 days of continuous operation, except for the loss due to mud cake and evaporation, there was no wastewater discharge. The amount of water replenished accounted for only 4.8% of the circulating water volume.

[0036] (12) Closed transfer of finished metal products: All sorted iron blocks, copper, aluminum ingots and other finished metal products are transferred to the finished product warehouse in a closed belt conveyor channel.

[0037] In this embodiment, recycled aggregate is used to prepare non-fired bricks, and the strength of the finished product meets the MU15 standard; mud cake is used as a cement admixture, and the strength of cement mortar does not decrease when the admixture ratio is 8%; the dust concentration in the entire work area is ≤4mg / m³. 3 Noise level ≤75dB(A), and all environmental protection indicators meet the standards.

[0038] Example 2

[0039] The difference between this embodiment and embodiment 1 is that the daily slag processing capacity is 300 tons. In process (2), the primary sieve aperture is adjusted to 60mm, the particle size of the crushed material is ≤30mm, and the crushing stage is two stages. In process (4), the jigging frequency is 300 times / min, the amplitude is 10mm, the feed concentration is 22%, and the water-to-material ratio is 3.5:1. In process (5), the vibrating bed frequency is 400 times / min. In process (6), the first stage of the two-stage eddy current separation has a working frequency of 45Hz and a magnetic field strength of 4000Gs, and the second stage has a working frequency of 75Hz and a magnetic field strength of 6000Gs. In process (8), polyaluminum chloride 15mg / L and polyacrylamide 0.8mg / L are added for coagulation sedimentation, and the reaction pH is maintained at 6.8~7.2. In process (9), the temperature of the draining bin is 30℃ and the humidity is 58%. The coarse sand zone drains for 36h, the medium sand zone for 50h, and the fine sand zone for 65h, and the moisture content at the factory outlet is 16%, 17%, and 18%, respectively. In process (10), the feed pressure was 0.6 MPa, the filter press cycle was 55 min, and the moisture content of the sludge cake was 58%. The remaining operations were the same as in Example 1. Results: Aluminum recovery rate was 65%, purity was 96.8%, copper recovery rate was 43%, the recycled aggregate met the requirements for building materials, production water was discharged zero, and environmental indicators met the standards.

[0040] Comparative Example 1 The traditional open-type slag treatment process was adopted, without a fully enclosed working environment or a multi-stage water treatment system, relying solely on simple sedimentation followed by reuse. Results showed that dust concentration in the work area exceeded national standards by three times, and noise levels exceeded standards by 5 dB(A). The suspended solids (SS) in the reused water reached 120 mg / L, leading to jig nozzle blockage, a 30% decrease in eddy current separation efficiency, and severe pipe scaling. The system was forced to shut down for cleaning after only 10 days of operation. Furthermore, production water could not be effectively recycled, resulting in approximately 200 tons of wastewater being discharged daily.

[0041] Comparative Example 2 Instead of using two-stage eddy current separation, only single-stage eddy current separation was used (operating frequency 60Hz, magnetic field strength 5000Gs). The results showed that the aluminum recovery rate was only 45%, the purity was 90%, and the aluminum content in the tailings was as high as 2.1%. When this tailings was used to prepare building blocks, the 28-day compressive strength was 22% lower than that of Comparative Example 1, which could not meet the building use standards.

[0042] Tables 1 to 3 summarize the key process parameters, main technical performance indicators, and resource utilization test results of the product obtained in Example 1 for each embodiment and comparative example.

[0043]

[0044] Table 1 Comparison of key process parameters between each embodiment and the comparative example.

[0045] Table 2 Comparison of technical effects of each embodiment and comparative example.

[0046] Table 3. Resource utilization effect of recycled aggregate and mud cake in Example 1 From Tables 1 to 3, we can see that: (1) Both Example 1 and Example 2 can operate stably within different ranges of process parameters, with aluminum recovery rate reaching 65% to 70%, purity reaching 96.8% to 97.5%, and aluminum content in tailings controlled below 0.5%, indicating that the process parameters of the present invention have a wide range of suitable adjustment.

[0047] (2) Compared with the examples, Comparative Example 1 did not include coagulation, sedimentation and filtration processes, and the SS of the recycled water was as high as 120 mg / L, which led to scaling and blockage of the system, and the continuous operation time was no more than 10 days; moreover, water recycling could not be achieved, and wastewater was discharged. This shows that the establishment of the multi-stage water treatment process of the present invention is the key to achieving long-term stable operation and zero discharge of the system.

[0048] (3) In Comparative Example 2, which only used single-stage eddy current separation, the aluminum recovery rate dropped significantly to 45%, and the aluminum content in the tailings was as high as 2.1%, which directly led to the failure of subsequent building materials to meet strength standards. This shows that the two-stage eddy current series separation process of the present invention plays an irreplaceable role in the efficient purification of aluminum and ensuring the quality of building materials.

[0049] (4) The compressive strength of the non-fired brick prepared from the recycled aggregate obtained in Example 1 reached 16.8 MPa, which meets the MU15 standard; the mortar strength retention rate reached 98% when the mud cake was used as a cement admixture with a mixing ratio of 8%, and the leaching toxicity test was qualified, indicating that the end product of the process of the present invention can realize full resource utilization.

Claims

1. A fully enclosed resource utilization treatment and zero-discharge water recycling process for slag, characterized in that: The process includes the following steps: (1) Layout of the work area and closed storage pretreatment: High-noise equipment is placed in the sunken work area and vibration reduction measures are taken. The material is transported from top to bottom by utilizing the elevation difference between the processing units. The slag raw material is unloaded into a closed storage area with sound-absorbing enclosure for atomized spraying to suppress dust. The spray water comes from the subsequent water treatment and reuse system. The storage area is maintained in a slightly negative pressure state. The extracted gas is discharged after being treated by dust removal, adsorption and photocatalysis. The drain water at the bottom of the storage area is collected into the circulating water collection system. (2) Closed-loop feeding and grading crushing: The slag in the storage area is screened through a closed conveyor. The material on the screen is picked out to remove impurities, and the material under the screen is sent to the crushing process. After crushing, the material reaches the set particle size. The entire feeding, screening and crushing process is carried out in a closed working space with sound absorption measures. The generated dust is collected and enters the dust removal system. Pre-magnetic separation and iron separation: After crushing, the material undergoes a primary magnetic separation process, where magnetic materials are separated and collected separately, while non-magnetic materials enter the next process. Jigging and auxiliary sorting: Non-magnetic materials enter the jigging separation process, and the jigging water is recycled clean water. The jigging frequency and amplitude are controlled. After jigging, the upper layer of light materials is separated from the incompletely burned raw materials by auxiliary separation, and the lower layer of heavy materials is separated from the solid iron blocks and other iron blocks by auxiliary separation. Wastewater generated during jigging is collected in a wastewater equalization tank. Vibrating bed sorting and secondary magnetic separation: The intermediate products after jigging are fed into a vibrating bed for separation, with the frequency of the vibrating bed controlled. The material after vibrating bed separation is then subjected to a secondary magnetic separation to recover residual magnetic particles. The wastewater generated by the vibrating bed separation and the secondary magnetic separation is collected in a wastewater equalization tank. Two-stage eddy current separation for aluminum extraction: After the secondary magnetic separation, the material enters the eddy current separator, which adopts a two-stage series mode, with the working frequency and magnetic field strength set separately. After separation, aluminum products are obtained, while ensuring that the aluminum content in the tailings is lower than the set threshold. The wastewater generated in this process is collected into the wastewater equalization tank. Copper crushing and water-sand separation: After eddy current separation, the coarse sand enters the copper crushing process. After being crushed to the set particle size, it enters the water-sand separation process to separate the copper particles from the fine sand and collect the copper products separately. Wastewater generated from water-sand separation is collected in a wastewater equalization tank. Multi-stage water treatment and recycling: The mixed wastewater in the sewage equalization tank is subjected to sedimentation treatment, coagulation sedimentation treatment and filtration treatment in sequence. After the treated water meets the reuse standard, it is all reused for the spray water in process (1), the jigging water in process (4), the vibrating bed water in process (5), the eddy current separation water in process (6) and the copper crushing and cooling water in process (7). Fine sand classification and finished product moisture content control: After water and sand separation, the fine sand is sent to the grading process and divided into different grades according to particle size; the graded recycled aggregate is sent to the sealed dewatering area for natural dewatering, and the moisture content of the recycled aggregate after dewatering is lower than the set value; the dewatered water is returned to the sewage equalization tank. (10) Slurry filtration and resource utilization: The sediment discharged in process (8) and the fine sludge collected in process (9) are concentrated for filter press dewatering. The moisture content of the filter cake after filter press is controlled within the set value. The filtrate generated by filter press is returned to the sewage equalization tank for reprocessing. The dewatered filter cake is transported off-site for resource utilization. (11) Integration of water resources across the entire region: All initial rainwater, washing water from various areas, aggregate drain water, and equipment cooling water in the factory area are collected and fed into the sewage regulating tank. They are then treated together with the production wastewater in process (8) and reused in a unified manner to ensure that no wastewater is discharged from the factory area. (12) Closed transfer of finished metal products: All sorted iron, copper, aluminum and their alloy products are transferred to the finished product area in a closed environment.

2. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, In process (1), the spraying water volume of the atomized spray is 0.5 to 1.5 m³ per ton of slag. 3 Spray pressure 0.2~0.4MPa; in process (2), the screening adopts a screen with a screen hole of 60~80mm, the particle size of the crushed material is ≤40mm, and the crushing level does not exceed three levels; in process (3), the magnetic field strength of the first-level magnetic separation is ≥3000Gs, and the magnetic field strength of the second-level magnetic separation in process (5) is ≥2500Gs; in process (4), the jigging frequency is 300~400 times / min, the amplitude is 10~15mm, the feed concentration is 20%~30%, and the water-to-material ratio is (3~5):1; in process (6), the first stage of the two-stage eddy current separation has a working frequency of 40~60Hz and a magnetic field strength of 4000~5000Gs, and the second stage has a working frequency of 70~90Hz and a magnetic field strength of 6000~7000Gs; in process (7), the particle size of the crushed copper is ≤10mm.

3. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, During the two-stage eddy current separation in process (6), the aluminum crude concentrate obtained after the first stage separation enters the second stage separation, and the tailings from the second stage separation are returned to the first stage feed inlet for recycling separation.

4. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, In step (8), the hydraulic retention time of the sedimentation treatment is ≥3h; in the coagulation sedimentation treatment, 10-30mg / L of polyaluminum chloride and 0.5-2mg / L of polyacrylamide are added, and after the reaction, the mixture enters the secondary sedimentation tank with a hydraulic retention time of 2-4h; the filtration treatment adopts multi-media filtration with a filtration accuracy of ≤10μm; after treatment, the water is reused after the SS index reaches ≤10mg / L, COD ≤30mg / L, and turbidity ≤5NTU.

5. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, During the coagulation and sedimentation treatment, acid or alkali adjusters are added according to the pH value of the wastewater to maintain the reaction pH at 6.5~8.0; when the heavy metal ions in the wastewater exceed the standard, heavy metal scavenging agents are added simultaneously.

6. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, In the process (9), the sealed drainage area is set up with multiple partitions, which are stored according to the aggregate particle size. The drainage time of different partitions is adjusted independently. The drainage time of the coarse sand area is ≥36h, and the drainage time of the fine sand area is ≥60h. During the drainage period, the temperature inside the silo is kept ≤30℃ and the relative humidity is kept ≤60%. The set value of the moisture content at the factory is 20%.

7. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, In the process (10), the filter press adopts the plate and frame filter press method, the feed pressure is ≥0.6MPa, the filter press cycle is ≤60min, and the moisture content of the filter cake after filter press is ≤60%. Before filter press, lime or polyacrylamide is added to the slurry as a filter aid, and the amount added is 0.5% to 2% of the dry solids of the slurry.

8. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, All waste gas generated during the entire process is introduced into the central dust removal system through a gas collection pipeline, and is treated by a combination of bag filtration, activated carbon adsorption and ultraviolet photocatalysis to meet emission standards.

9. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, When the process is first run, clean water is injected as the initial circulating water. Subsequently, only the water lost due to mud cake and evaporation is replenished, and the amount of water replenished does not exceed 5% of the total circulating water. The dust collected by the dust removal system in process (2) is returned to the jigging feed inlet of process (4), mixed with the jigging feed, and then re-enters the sorting process.

10. The fully enclosed resource utilization treatment and zero-discharge water recycling process for slag according to claim 1, characterized in that, The fine sand separated in step (7) is graded and collected into three grades: coarse sand, medium sand and fine sand, and used to prepare recycled building materials of different specifications. The mud cake after dehydration in step (10) is sent to a cement plant as a raw material admixture or used to produce lightweight wall panels. The magnetic material separated in step (3) is crushed and then magnetically separated again to separate refined iron, large iron blocks and stainless steel, which are collected as finished metal products.

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