A zero-residue treatment process for full-component high-value resource of stale household garbage

Abstract

The application discloses a kind of stale domestic waste full-component high-value resource zero residue treatment processes, belong to solid waste treatment field.There are problems such as low resource rate, secondary pollution risk, low product added value in existing technology landfill stale garbage processing.The stale garbage of the present application is sequentially subjected to primary separation, plastic purification, humus metal separation and brick making utilization four stages, and nearly ten kinds of components such as stone, sand, rubber, glass, scrap iron, plastic, copper, aluminum are all high-purity separated and converted into saleable products, and finally the leftovers are made into floor tiles.The present application realizes full-component resource, product high-value, zero emission and zero residue in production process, can reduce the dependence on government subsidies, and has significant economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of landfill treatment and relates to waste recycling, particularly to a zero-residue treatment process for high-value resource recovery of all components of aged domestic waste. Background Technology

[0002] For a long time, my country's municipal solid waste disposal has relied mainly on landfilling, with approximately 8 billion tons of waste already landfilled, occupying nearly 100,000 hectares of land. With the acceleration of urbanization and the improvement of environmental standards, the remediation of old landfills and the resource utilization of existing waste have become urgent issues to be addressed.

[0003] Currently, there are two main traditional processes for treating aged municipal solid waste in landfills in China: The first method is direct incineration after excavation. After excavating aged municipal solid waste from the landfill, it is sent directly to a waste-to-energy plant for incineration without any screening. The drawbacks of this process are: the aged waste has a high moisture content of 45%–70% and a low calorific value (approximately 1000 kcal / kg), resulting in low incineration efficiency and requiring a large amount of auxiliary fuel; simultaneously, a large amount of non-combustible materials such as slag, metal, and glass are fed into the furnace, which not only reduces incineration efficiency but also accelerates equipment wear and increases operating costs.

[0004] The second method involves simple screening, incinerating the oversize and backfilling the undersize. Old household waste undergoes simple screening; the oversize (combustible materials such as plastics and fabrics) is sent to an incineration plant, while the undersize (humus) is backfilled on-site. The drawback of this process is that it only achieves "volume reduction" rather than "resource recovery." The humus still contains pollutants such as heavy metals and microplastics, posing a continued risk of secondary pollution to the soil and groundwater after backfilling. Furthermore, a large amount of recyclable resources (plastics, metals, glass, etc.) are wasted or mixed in with the humus and cannot be utilized.

[0005] In addition, some improvements have been made in the existing technology. For example, CN119909927A discloses a "bag-in-bag" dry sorting method for municipal solid waste, which achieves waste component separation through multi-stage sorting such as hook vibration sorting, reciprocating puncture sorting, air separation, and magnetic separation; CN114210717A discloses a method for the resource utilization of aged waste, which removes large-sized objects, iron objects, and humus through pretreatment, and then treats plastic film materials through friction dry washing, air separation, drying, and polymerization modification; CN108746152A discloses a method for making building materials from aged waste, which makes bricks by inorganically treating humus slag. However, the above-mentioned existing technologies still have the following shortcomings: The sorting chain is incomplete, often only targeting a certain type of material (such as plastic or humus) for deep processing, without forming a closed-loop resource utilization system for all components; The sorted plastics are simply recycled or incinerated, failing to be utilized at a high value. Metals (copper, aluminum, etc.) in humus soil are not properly sorted, resulting in a waste of resources; Ultimately, there are still residues that need to be landfilled or discharged, failing to achieve "zero residue".

[0006] To address the shortcomings of existing technologies, this invention provides a high-value, zero-residue treatment process for the complete utilization of all components of aged municipal solid waste. This process separates nearly ten valuable components from the aged waste into high-purity products and converts them into marketable goods, achieving "zero residue and zero waste." Summary of the Invention

[0007] The purpose of this invention is to overcome the technical defects of existing aged municipal solid waste treatment processes, such as low resource utilization, high risk of secondary pollution, and low product added value, and to provide a treatment process that is comprehensive, high-value-added, and leaves no residue, so that aged municipal solid waste can be transformed from an "environmental burden" into a "profitable resource".

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a high-value, zero-residue treatment process for all components of aged municipal solid waste, characterized by comprising the following four process flow segments: First process flow stage: Primary sorting system The aged domestic waste excavated from the landfill is transported through a closed conveyor system to the receiving silo in a fully enclosed workshop, where it undergoes the following processing: Relaxation screen grading: The aged waste is fed into the relaxation screen for screening. According to the moisture content and composition characteristics of the aged waste, the relaxation frequency of the relaxation screen is controlled at 400~600 times / minute, and the screen hole size is set to 25~50mm. First, large pieces of construction waste are screened out, and then the oversize and undersize materials are obtained. Manual sorting platform: Manually sorts out materials with larger dimensions (>100mm) from the material on the tension screen to separate recyclable materials such as large pieces of rubber, large pieces of glass, and large pieces of scrap iron; Crushing process: The manually sorted materials are fed into the crusher for crushing until the particle size is <80mm; Mud and stone separation: The crushed material is fed into a mud and stone separator, which uses the differences in density and particle size between the materials to separate them into two main categories: Heavy mixed materials (undersize): mainly include humus, fine sand, broken glass, small-diameter stones, a small amount of broken ceramics and undissociated metal particles, etc. This part of the material enters the third process flow section (humus metal separation system) for fine separation; Lightweight mixed materials (oversize material): mainly includes lightweight combustible materials such as plastics, cloth, fibers, and films. This part of the material enters the second process flow section (plastic purification system) for deep purification.

[0009] At this stage, the mud-stone separator only completes the initial binary separation of "heavy" and "light" components, and does not directly produce pure single products such as gravel, sand, or glass. The above components are gradually separated and purified in subsequent stages through multi-stage combined sorting methods such as drum screening, crushing, jigging, and shaking tables.

[0010] Product allocation in the first process flow segment: Screened material (heavy mixture, containing humus, sand, gravel, broken glass, metal particles, etc.) → enters the third process flow section; The material remaining on the sieve (lightweight mixture containing plastics, fabrics, fibers, etc.) → enters the second process flow section; Large pieces of glass, rubber, stainless steel, etc., that are manually sorted out are sold directly as by-products.

[0011] Second process flow section: Deep purification system for plastics and combustibles The material (a mixture of plastic, fabric, etc.) produced in the first process flow section is processed sequentially as follows: Crushing: The material on the screen is fed into a crusher for crushing until the particle size is <30mm; Magnetic separation: Residual ferrous metals are removed by using a magnetic separator (magnetic induction intensity of 0.4~0.6T on the drum surface); Drying: The material is fed into a dryer and dried at 80~120℃ until the moisture content is ≤20%. The heat source can be the surplus low-cost heat source of the waste-to-energy plant. Rotary drum screen: Further screening is performed using a rotary drum screen to remove fine soil particles; Dry cleaning: The material is fed into a dry cleaning machine, where mechanical friction is used to remove humus and dust adhering to the plastic surface; Air separation: The air separator uses the difference in specific gravity to separate light plastics and heavy impurities. The air separation speed is adjustable from 5 to 15 m / s. Manual sorting: The plastics after air separation are manually sorted to remove small amounts of impurities such as rubber and fabric that are still mixed in.

[0012] Products of the second process flow section: High-purity clean plastics (purity ≥ 95%) → are sent to oil refineries as raw materials or used for plastic granulation; Small amount of impurities → Return to the first process flow segment or proceed to the fourth process flow segment.

[0013] Third process flow section: Fine sorting system for valuable metals in humus soil The undersize material (humus) produced in the first process flow section is processed sequentially as follows: Rotary drum screening: The humus is fed into a rotary drum screen for grading and screening to remove residual impurities with a particle size >10mm; Suspended iron separator: grabs large iron blocks.

[0014] Crushing: The screened material is fed into a crusher for fine crushing to fully separate the agglomerated humus particles. The crushed particle size is controlled to be <3mm. Permanent magnet drum magnetic separator: Through strong magnetic separation (magnetic induction intensity of 0.8~1.0T on the drum surface), ferrous metals (iron powder, iron filings) are separated. Eddy current separation: non-ferrous metals such as aluminum, copper, and zinc.

[0015] Ti-jigging separation: The material after magnetic separation is fed into a jigging machine, which utilizes the difference in specific gravity and the jigging effect to concentrate non-ferrous metal particles, rather than... Titanium and heavy minerals were separated. ; Aluminum separation: The material after titanium separation is fed into the aluminum separation machine for further separation of aluminum metal; Shaking table separation: The material after aluminum removal is fed into multiple shaking tables. Utilizing the combined effect of inclined water flow and table shaking, residual non-ferrous metals such as copper and aluminum are finely separated according to their specific gravity differences, while clean stones and sand are obtained at the same time.

[0016] Products of the third process flow segment: High-purity iron (purity ≥ 90%) → sold directly to external customers; High-purity copper, aluminum and other non-ferrous metals (purity ≥ 85%) → sold directly to external customers; Cleaned pebbles and sand → enter the fourth process flow stage for use as raw materials for brick making; The purified humus (with residual metal content ≤0.5%) enters the fourth process flow stage for use as raw material for brick making.

[0017] Fourth process flow segment: Scrap material brick making system The gravel and sand produced in the first process stage, the clean gravel and sand and purified humus produced in the third process stage, and the non-reusable waste materials produced in each stage are processed into permeable paving bricks according to the following steps: Ingredient mixing: Mix according to the following weight ratios: 60-75 parts of waste material (mixture of sand, gravel, and humus), 15-25 parts of cement, and 10-15 parts of water, and mix evenly using a forced mixer. Mold forming: The mixture is fed into a steel permeable brick mold and pressed into shape under the combined action of a high-frequency vibrator (vibration frequency 50~100Hz) and a pressing brick machine (pressing pressure ≥15MPa); Curing: After molding, the brick blanks are cured for 7 to 28 days under natural conditions or steam curing conditions to obtain finished paving bricks.

[0018] A high-value, zero-residue treatment system for the complete utilization of all components of aged municipal solid waste, used to implement the treatment process described in any one of claims 1 to 8, comprising: Primary sorting unit: consisting of a tension screen, a manual sorting platform, a crusher, and a mud-stone separator connected in sequence; Plastic purification unit: consisting of a crusher, magnetic separator, dryer, drum screen, dry cleaning machine, air separator, and manual sorting platform connected in sequence; Metal sorting unit: connected in sequence, including a drum screen, a crusher, a magnetic separator, a titanium separator, an aluminum separator, and a shaking table; Brick making unit: forced mixer, steel permeable brick mold, high frequency vibrator, pressing brick machine, curing facilities.

[0019] Compared with the prior art, the advantages and positive effects of the present invention are as follows: Full component resource recovery: It can separate nearly ten valuable components such as stones, sand, rubber, glass, scrap iron, plastic, copper and aluminum from aged waste with high purity and realize resource utilization. The resource recovery rate is close to 100%, which is far higher than the 30% to 50% of traditional processes.

[0020] Product value enhancement: The sorted plastics with a purity of ≥95% can be supplied to oil refineries, and the metals with a purity of ≥85% can be sold directly. The final waste materials are made into paving bricks, all of which are transformed into products with market value, enabling the project to have independent profitability and reducing its dependence on government processing service fees.

[0021] Environmentally friendly: Heavy metals and pollutants in humus are effectively separated and solidified in the brick body, eliminating the risk of secondary pollution; the production process is completely closed and has zero emissions, completely removing the label of "environmentally damaging" from rotten waste.

[0022] Economic sustainability: The project operation is supported by the sales revenue of high value-added products, which transforms the treatment of aged waste from a "pure input type" to a "profitable type", and has broad market promotion prospects.

[0023] The clean water treated with leachate during the metal sorting process is used for recycling with zero discharge and zero addition of tap water. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the process for high-value resource recovery and zero-residue treatment of all components of aged municipal solid waste according to the present invention. Detailed Implementation

[0026] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0027] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0028] This embodiment uses aged waste from a municipal solid waste landfill in southern my country as the treatment object. The landfill was put into operation in 2008 and closed in 2018, with a landfill age of 10 years and a waste accumulation of approximately 450,000 tons. Preliminary sampling and testing revealed the following basic characteristics of the aged waste in the landfill: average moisture content 38.5%, humus (particle size <40mm) accounting for approximately 54.7%, rubber, plastics, and textiles accounting for approximately 32.1%, metals accounting for approximately 1.9%, bricks, tiles, and stones accounting for approximately 8.6%, and other components accounting for approximately 2.7%. The aged waste has a relatively high chromium (Cr) content, and the environmental risks associated with its non-direct agricultural use warrant attention. This underscores the necessity of resource utilization rather than simple backfilling.

[0029] I. First Process Flow Section: Primary Sorting System After the landfill waste is excavated by a negative excavator, it is transported into the fully enclosed workshop receiving silo using a closed loader and belt conveyor. The system is designed to process 1,200 tons / day (approximately 150 tons / hour).

[0030] (1) Receiving and equalizing materials The excavated waste is loaded into a receiving hopper using a loader. A plate feeder is installed at the hopper's outlet, with variable frequency speed control to regulate the feeding rate and ensure uniform feeding to subsequent equipment. The feeding rate is maintained between 100 and 170 tons per hour. Simultaneously, a dust collection hood is installed above the receiving hopper to introduce dust and odorous gases generated during unloading into the workshop's negative pressure dust and odor removal system.

[0031] (2) Classification by tension sieve The aged waste output from the receiving silo is fed into the tension screen via a closed belt conveyor. The tension frequency of the tension screen is set to 500 times / minute, and the screen aperture size is set to 30mm. Depending on the moisture content of the aged waste (usually between 30% and 45%), the tension frequency can be adjusted within the range of 400 to 600 times / minute. When the moisture content is high, the tension frequency should be appropriately increased to enhance the screening efficiency.

[0032] After screening by a tension sieve: The screened material (particle size <30mm) accounts for about 55% of the feed, mainly humus soil (containing some fine stones and slag), which is sent to the third process flow section by belt conveyor; The material oversize (particle size ≥ 30mm) accounts for about 42% of the feed, mainly a mixture of plastics, cloth, rubber, glass, stones, etc., which is conveyed to the manual sorting platform by belt conveyor.

[0033] (3) Manual sorting platform The manual sorting platform is located at the discharge end of the tension screen, with 8 workstations (4 on each side). Workers wear dust masks and gloves during operation. The sorting targets are: Large pieces of rubber (such as tire blocks) with a size greater than 150mm are sorted, collected, and sold externally. Large pieces of glass and bottles with a size greater than 150mm are sorted, collected, and sold externally. Scrap metal blocks larger than 150mm (such as iron drums and steel bars) are sorted and sent to the scrap metal collection bin.

[0034] The materials manually sorted account for about 3% to 5% of the feed. The remaining materials after sorting (mainly plastics, cloth, and small-diameter stones) are sent to the crusher via belt conveyor.

[0035] (4) Crushing process The manually sorted materials are fed into a hammer crusher, which is equipped with a set of high-speed hammers. The particle size of the crushed material is controlled to be <80mm. A magnetic separator drum (magnetic induction intensity of 0.6T on the drum surface) is installed at the discharge port of the crusher to initially remove residual ferrous metals exposed during the crushing process.

[0036] (5) Separation of mud and rocks (preliminary separation of heavy and light mud): Mud and stone separation is achieved using a roller screen: the crushed material is fed into the roller screen. The roller screen consists of multiple parallel rollers, each equipped with several cutter discs, with the cutter discs on adjacent rollers arranged alternately. Driven by a drive unit, the rollers rotate in the same direction, and the cutter discs tumble, shear, and push the material forward. Based on differences in particle size and physical morphology, the material is separated into two main categories: Undersize material (heavy mixture): The material that passes through the gap between the rollers mainly includes humus, fine sand, broken glass, small-diameter stones, a small amount of broken ceramics and undissociated metal particles. This part of the material enters the third process flow section (humus metal separation system) for fine separation. Oversize material (lightweight mixed materials): The material pushed onto the screen by the cutter head and conveyed forward is mainly lightweight combustible materials such as plastic film, plastic bottle flakes, woven bags, cloth strips, and fibers. This part of the material enters the second process flow section (plastic purification system) for deep purification.

[0037] At this stage, the roller screen only completes the initial binary separation of "heavy" and "light" components, and does not directly produce pure single products such as gravel, sand, and glass. The above components are gradually separated and purified in subsequent processes through multi-stage combined separation methods such as drum screening, crushing, magnetic separation, jigging, and shaking tables.

[0038] II. Second Process Flow Section: Deep Purification System for Plastics and Combustibles The mixture (plastics, fabrics, etc.) generated in the first stage is sent to the second stage for processing by a closed belt conveyor. The designed processing capacity of this stage is about 150 tons / day.

[0039] (1) Broken The mixture is fed into a single-shaft shredder for crushing. The main shaft of the shredder rotates at 60 r / min, and the particle size of the crushed material is <30 mm. The purpose of crushing is: 1) to make large pieces of material flow evenly in subsequent equipment; 2) to loosen and remove humus and impurities adhering to the plastic surface.

[0040] (2) Magnetic separation After crushing, the material passes through a suspended magnetic separator (magnetic induction intensity of 0.5T on the drum surface) to remove the ferrous metals (mainly iron nails, iron wires, iron filings, etc.) exposed during the crushing process. The ferrous metals separated by magnetic separation are collected and combined with the first stage of scrap iron for sale.

[0041] (3) Drying After magnetic separation, the material is fed into a three-pass dryer. The dryer drum has a diameter of 1.5m and a length of 8m. The heat source is steam from an external municipal solid waste power plant, and the hot air temperature is controlled at 100±10℃. The material stays in the dryer drum for approximately 12 minutes, and the moisture content of the discharged material decreases from approximately 35% to ≤18%. A temperature sensor is installed at the dryer outlet, which automatically alarms when the material temperature exceeds the set value.

[0042] (4) Drum screening After drying, the material is fed into a drum screen (5mm screen hole) to remove fine slag that falls off during the drying process (accounting for about 15% to 20% of the dried material). The undersize material is collected and sent to the third stage copper and aluminum separation system, while the oversize material enters the dry cleaning process.

[0043] (5) Dry cleaning The material passing through the screen is fed into a dry cleaning machine. Inside the machine are rotating friction rollers and a screen cylinder. Through mechanical friction and tumbling, dust, dirt, and other contaminants remaining on the plastic surface are effectively removed. The dry cleaning machine operates at 300 rpm, with a material residence time of approximately 3 minutes. Dust discharged from the dry cleaning process is collected by a bag filter via the machine's built-in pneumatic conveying system and then sent to the metal sorting production line.

[0044] (6) Wind sorting The dry-cleaned material is fed into a circulating air separator, which is equipped with an adjustable fan. The air speed is controlled by adjusting the fan's frequency converter. In this embodiment, the air separation speed is set to 10 m / s (adjustable range 5~15 m / s). Under the action of the airflow, lightweight plastics are blown into the lightweight material collection channel, while heavy debris (stones, glass shards, rubber sheets, etc.) settles into the heavy material outlet due to gravity.

[0045] After being selected by wind: Lightweight materials (mainly plastics) proceed to the next process, accounting for 65% to 70% of the materials fed into this stage; The heavier mixtures are sent to municipal solid waste power plants for incineration.

[0046] (7) Manual sorting After air separation, the lightweight material is conveyed by a belt conveyor to a manual sorting conveyor belt (belt speed 0.3m / s). There are 4 workstations where workers pick out any remaining small amounts of rubber sheets, cloth strips, colored plastics, and other impurities. The final product is a clean plastic product that is white / light gray in appearance and free of visible impurities.

[0047] Second-stage product specifications: Clean plastic yield: approximately 35% of the second stage feed (i.e., approximately 15% of the material over the first stage). Plastic purity: Tested by a third party, >96%, meeting the quality requirements for oil refining feedstock or granulation feedstock; Impurities (fine slag, heavy materials, etc.): approximately 45%, enter the metal sorting production line and are sent to the municipal solid waste power plant for incineration.

[0048] III. Third Process Flow Section: Fine Separation System for Valuable Metals in Humus Soil The undersize material (humus) produced in the first stage is sent to the third stage for processing by a closed belt conveyor. The designed processing capacity of this stage is about 275 tons / day.

[0049] (1) Drum screening: First, use a magnetic separator to pick out the ferrous metal on one side before crushing.

[0050] The humus is first fed into a drum screen (10mm mesh) to remove any particles larger than 10mm (such as gravel and plastic pieces) that may remain. The material that passes through the screen (approximately 5%) is then fed into the fourth-stage brick-making system, while the material that passes through the screen enters the crushing process.

[0051] (2) Crushing The undersize material is fed into an impact crusher with an 800mm rotor and a rotation speed of 750 rpm. This crusher thoroughly breaks down and separates the aggregated particles in the humus, controlling the particle size to <3mm after crushing. The purpose of crushing is to fully expose and separate fine-grained metallic minerals from the humus matrix, creating conditions for subsequent jigging and shaking table separation. A vibrating screen (3mm aperture) is installed at the crusher outlet for particle size control; unqualified material is returned to the crusher for further crushing.

[0052] (3) Magnetic separation The crushed material is passed through a high-intensity magnetic separator (magnetic induction intensity of 0.9T on the drum surface) to effectively separate ferrous metals (iron powder, iron filings, and iron oxide particles) from the humus. The ferrous metals separated by magnetic separation have a purity of ≥90% and are collected and sold. The material after magnetic separation proceeds to the next process.

[0053] (4) Titanium-skipping sorting The magnetically separated material enters the titanium-jumping machine. The titanium-jumping machine separates different mineral particles based on their settling velocity differences in the rising water flow. In this embodiment, the titanium-jumping machine's stroke is set to 25mm, the stroke rate to 250 strokes / min, and the feed water pressure to 0.15MPa. Titanium and heavy minerals, due to their higher specific gravity (titanium's specific gravity is approximately 4.5), settle to the bottom and are collected, while other light minerals are carried over to the next process. The titanium-jumping machine produces titanium concentrate (purity approximately 75%~80%), accounting for 0.3%~0.5% of the feed in this section.

[0054] (5) Aluminum sorting The overflow from the titanium jigging machine enters the aluminum jigging machine. The operating parameters of the aluminum jigging machine are adjusted to suit the sorting of aluminum metal: stroke 20mm, stroke rate 300 times / min, and water pressure 0.10MPa. Aluminum metal (specific gravity approximately 2.7) is concentrated at the bottom under the jigging action and is collected before entering the shaking table for further selection; the remaining material enters the shaking table feed box.

[0055] (6) Selected shakers The bottom product and part of the tailings from the aluminum blast furnace are simultaneously fed into a shaking table for refining. The shaking table is a 6-S type double-layer shaking table with a 5° table slope, a stroke of 15mm, a stroke rate of 320 strokes / min, and a feed concentration of 20%~25%. The shaking table utilizes the combined effect of inclined water flow and the reciprocating shaking of the table surface to cause minerals of different specific gravities to be distributed in bands according to their specific gravity on the table surface. The heaviest metals, such as copper (specific gravity 8.9) and lead, are concentrated at the surface concentrate end of the bed and are collected as non-ferrous metal concentrates. Medium-gravity aluminum (specific gravity 2.7) and silicate minerals are distributed in the middle of the bed surface; The smallest humus particles are discharged with the tailings stream.

[0056] After separation on a shaking table, the total recovery rate of copper and aluminum non-ferrous metals is ≥85%, and the purity is ≥85%. The collected metals are then sold externally.

[0057] (7) Subsequent utilization The clean sand and gravel (particle size <3mm, mainly quartz sand) produced by the shaking table is mixed with purified humus and then sent to the fourth brick-making system. Testing showed that the residual metal content in the purified humus was ≤0.5%, and the content of heavy metals (Cr, Pb, Cd, etc.) decreased by more than 70% compared to before sorting.

[0058] Third-stage material balance (based on a 100% feeding rate in the third stage): IV. Fourth Process Flow Section: Waste Material Brick Making System All waste materials, including stones, sand, fine slag, and purified humus produced in the first, second, and third stages, are collected and sent to the fourth stage brick-making workshop. They are then blended according to the quality and moisture content of materials from different sources to ensure the stable quality of the finished bricks.

[0059] (1) Ingredients After testing the moisture content and sieving the particle size of the incoming materials at each stage, they are fed into the batch according to the following weight ratio (on a dry basis): When the moisture content of the humus soil is too high (>20%), it needs to be naturally sun-dried or hot-air-dried before mixing to adjust the moisture content to within the range of 10%~15% to ensure the formability of the mixture. In this embodiment, the purified humus soil has a moisture content of about 12%~15%, and no additional drying is required.

[0060] (2) Stirring The raw materials in the above proportions are fed sequentially into a planetary forced mixer with a capacity of 1.5 m³ and a mixing efficiency of 60 m³ / h. The feeding sequence is as follows: first, add the waste materials and cement, and dry mix for 30 seconds; then add water and wet mix for 120 seconds. Mix until the mixture is uniformly wet and loose, ideally able to be formed into a ball by hand but crumble easily when released.

[0061] (3) Mold forming The well-mixed material is conveyed via belt conveyor into a steel permeable brick mold. The mold is a compression molding type, and each mold can produce 4 permeable bricks (sizes: 115mm×230mm×60mm, 100×200×60, etc.). After the mixture is put into the mold, a high-frequency vibrator (vibration frequency 80Hz, amplitude 1.5mm) is first turned on to vibrate and compact for 15 seconds, so that the mixture is evenly filled in the mold and air bubbles are expelled; then the pressing brick machine is started, pressing at a pressure of 18MPa, and holding the pressure for 10 seconds before demolding.

[0062] (4) Maintenance After demolding, the brick blanks are placed on curing racks and covered with plastic film for curing at room temperature. During curing, they are sprayed with water regularly to keep the surface of the brick blanks moist. After 24 hours of curing, they can be stacked (able to withstand a certain amount of pressure); after 7 days of curing, the compressive strength can be tested to be above 15MPa; after 28 days of curing, they reach the design strength.

[0063] (5) Finished product inspection After 28 days of curing, samples were taken for testing, and the performance indicators are as follows: Finished bricks can be used for paving projects such as municipal sidewalks, squares, parking lots, and residential roads, fully meeting market demand.

[0064] (6) Zero emission control in this section The wastewater generated by the brick making system (mold cleaning water, excess spray water for curing) is treated by sedimentation in a sedimentation tank. The supernatant is reused for mixing and batching and spray curing, while the sediment is returned to the batching system, achieving zero wastewater discharge. Dust collection hoods are installed at the cement feeding port in the brick-making workshop. Dust-laden gas is treated by a bag filter and discharged in compliance with standards. The collected dust is returned to the batching system.

[0065] V. Overall Effect of the Entire Process After the production line in this embodiment is running stably, it is calculated that it can process 500 tons of aged waste per day: Summary of outputs: Key metrics: Total process resource utilization rate: ≥98% (almost all input materials are converted into products); Final residue: Apart from a small amount of dust (approximately 1% to 2%) collected by the workshop dust removal system, there is no solid waste discharged externally; Wastewater discharge: Zero discharge; Exhaust gas emissions: Meets emission standards; Project revenue: Daily output sales revenue is approximately 80,000 to 120,000 yuan, and the comprehensive production cost (including labor, equipment depreciation, energy consumption, auxiliary materials, etc.) is approximately 50,000 to 70,000 yuan per day, achieving profitability.

[0066] Example 2: Adaptability of waste aged in landfills of different ages

[0067] The process of this invention was applied to the treatment of aged waste with different landfill ages (4 years, 9 years, and 15 years), and the results showed that: (1) Landfill waste aged 4 years: high moisture content (about 42%), humus content of about 50%, and plastics not yet fully degraded. The frequency of the first stage tension screen needs to be appropriately increased to 550 times / minute, the drying temperature of the second stage needs to be increased to 110~120℃, and the drying time needs to be extended to 15 minutes. The other parameters remain basically unchanged, and the quality of the final product is basically the same.

[0068] (2) Landfill waste aged 15 years: low moisture content (approximately 28%), humus content approximately 62%, severe plastic embrittlement, and slightly reduced recycling rate (approximately 75%). The speed of the third-stage crusher needs to be increased to 850 r / min for sufficient dissociation, and the jigging and shaking table parameters should be fine-tuned according to changes in material specific gravity. The final comprehensive resource recovery rate still reaches over 95%.

[0069] Example 3: Adaptability to different climatic conditions

[0070] (1) Operation during the rainy season: The moisture content of aged waste in southern regions increases significantly during the rainy season (up to 45%~55%). The countermeasures are: a) Add a draining grid to the receiving silo to allow some free water to drain out naturally before feeding; b) Increase the relaxation frequency of the relaxation screen to 580~600 times / minute; c) Increase the drying temperature of the second stage to 120℃ and appropriately extend the residence time; d) The screening effect of humus may decrease during the rainy season, and a hot air blowing device can be added to the third stage drum screen to assist screening.

[0071] (2) Low-temperature operation in winter: When the winter temperature in northern regions is below 0℃, the lubrication system needs to be preheated before starting the equipment; electric heat tracing and insulation need to be added to the water circulation pipeline; the brick curing process needs to be changed from natural curing to steam curing (60℃, 8 hours) to ensure that the brick blanks are properly hydrated and hardened in the low-temperature environment. After taking the above measures, the winter production capacity is about 90% of the designed capacity.

[0072] Example 4: Comparative Experiment on Process Parameter Optimization

[0073] To verify the rationality of the selection of parameters for each process in this invention, a comparative experiment was conducted: Comparison of screen aperture sizes for tension screens: Therefore, the preferred screen size of the present invention is 30 mm, which balances the recovery rate of humus and the purity of the undersize. Comparison of the effects of using a combination of titanium-aluminum-shaking bed: It is evident that the multi-stage separation process in the fourth stage of this invention is a core technical means to significantly improve the metal recovery rate.

[0074] Example 5: Description of a Complete Water Circulation System for Production This process operates in a closed workshop, achieving zero wastewater discharge throughout the entire process. The specific circulation path is as follows: (1) Floor washing water and equipment cooling water in the workshop are collected in the regulating tank through the drainage ditch; (2) After the effluent from the equalization tank is coagulated and settled (with the addition of PAC 50mg / L and PAM 2mg / L), the supernatant is sent to the clear water tank for reuse (for brick making batching, equipment cooling, etc., but not for workshop rinsing). (3) The sediment at the bottom of the sedimentation tank is dewatered by a plate and frame filter press, and the mud cake (mainly composed of fine slag) is sent to the fourth brick-making batching system. The dewatered filtrate is returned to the equalization tank. (4) After the initial rainwater collection pond settles, the rainwater in the factory area can also be added to the clear water pond for reuse; (5) When the water level in the clear water pool is low, a small amount of municipal tap water is added; when the water level is high, the excess clear water is used for irrigation of the green areas of the factory.

[0075] Through the above system, the annual wastewater recycling rate is ≥95%, and only a small amount of water needs to be replenished (≤5%) due to evaporation and water carried away by solid waste, basically achieving zero discharge.

[0076] Example 6: Product economics calculation (based on a daily processing capacity of 500 tons) Annual sales revenue of output (estimated at conservative market prices): Annual operating costs (including labor, electricity, water, natural gas, equipment depreciation, maintenance, management fees, etc.): approximately RMB 75 million per year.

[0077] Annual net profit: approximately RMB 37.75 million (before tax), with an investment payback period of approximately 3 to 4 years (based on a total investment of RMB 120 million).

[0078] The economic calculations show that the process of this invention is not only technically feasible but also has good economic sustainability. It can generate profits independently without relying on government processing service fees, which is in stark contrast to the traditional "pure input" model and has significant market promotion value.

[0079] Comparison with existing technical solutions

[0080] Comparative Example 1 A certain old waste treatment project using the traditional "simple screening + incineration of oversize material + backfilling of undersize material" process has a processing capacity of 500 tons / day.

[0081] The process only uses a single-stage drum screen (40mm screen opening). About 40% of the material on the screen (mainly plastics and cloth) is sent directly to the incineration plant, about 55% of the material under the screen (humus) is backfilled on-site, and about 5% of the coarsely collected materials such as metals and stones are sold off-site.

[0082] Comparison results: It is evident that in Comparative Example 1, a large amount of reusable materials were wasted through incineration, and the backfilling with humus soil posed a risk of exceeding the standards for heavy metals such as Cr, failing to fundamentally address the environmental hazards.

[0083] Comparative Example 2 A patented solution (CN108746152A) that uses a "sorting + humus slag brick making" process has the following process route: after the aged waste is pre-screened, magnetically separated, crushed and air-separated, the humus slag is sent to a fluidized bed incinerator for inorganic treatment, and then mixed with cement and other auxiliary materials to make bricks.

[0084] The following is a comparison between this solution and the present invention: This invention does not use incineration to treat humus soil, but extracts valuable metals from it through physical sorting and reuses them, which reduces energy consumption and avoids the waste of metal resources.

[0085] Summary of the technical differences between the process of this invention and the traditional process

[0086] The above comparative data fully demonstrates that the present invention is significantly superior to the prior art in terms of resource utilization rate, product added value, environmental friendliness, and economic sustainability.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications 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 protection scope of the present invention.

Claims

1. A high-value, zero-residue treatment process for all components of aged municipal solid waste, characterized in that: Includes the following steps: (1) Primary sorting: The aged domestic waste is fed into the tension screen for screening. Large pieces of construction waste are screened out. Large pieces of glass, rubber, stainless steel, etc. are manually picked out. The undersize material is crushed to a particle size of <80mm by a crusher, and then separated into heavy and light materials by a mud-stone separator to obtain a heavy mixture material (undersize material) mainly composed of humus, fine sand, broken glass, and small-diameter stones, and a light mixture material (oversize material) mainly composed of plastics, cloth, and fibers. (2) Plastic purification: The material on the sieve in step (1) is successively crushed, magnetically separated, dried, drum screened, dry washed, air-separated and manually picked to obtain clean plastic with a purity of ≥95%, which can be used as raw material for oil refining or granulation. (3) Metal separation of humus: The humus undersize material from step (1) is sequentially screened by drum screen, crushed to a particle size <3mm, magnetically separated, titanium-skimmed, aluminum-skimmed, and separated by shaking table eddy current separator to obtain ferrous metals, copper and aluminum non-ferrous metals, tin, tungsten, clean sand and gravel and purified humus. (4) Brick making and utilization: The stones, sand and purified soil produced in steps (1) to (3) are mixed, cement and water are added, and the mixture is forced to be stirred, molded, subjected to high-frequency vibration and pressure, and cured to make permeable paving bricks.

2. The zero-residue treatment process for high-value resource utilization of all components of aged municipal solid waste according to claim 1, characterized in that, The relaxation frequency of the relaxation screen in step (1) is 400~600 times / minute, and the screen hole size is 25~50mm.

3. The zero-residue treatment process for high-value resource utilization of all components of aged municipal solid waste according to claim 1, characterized in that, The drying temperature in step (2) is 80~120℃, and the moisture content of the material after drying is ≤20%; the air separation speed is adjustable from 5 to 15m / s.

4. The zero-residue treatment process for high-value resource utilization of all components of aged municipal solid waste according to claim 1, characterized in that, The magnetic induction intensity of the cylinder surface in step (2) is 0.4~0.6T.

5. The high-value resource recovery and zero-residue treatment process for all components of aged municipal solid waste according to claim 1, characterized in that, The magnetic induction intensity of the cylinder surface in step (3) is 0.8~1.0T.

6. The zero-residue treatment process for high-value resource utilization of all components of aged municipal solid waste according to claim 1, characterized in that, The weight proportions of the ingredients in step (4) are: 60-75 parts of waste material, 15-25 parts of cement, and 10-15 parts of water.

7. The high-value resource recovery and zero-residue treatment process for all components of aged municipal solid waste according to claim 1, characterized in that, The frequency of the high-frequency vibration in step (4) is 50~100Hz, and the pressing pressure of the pressed brick is ≥15MPa.

8. The zero-residue treatment process for high-value resource utilization of all components of aged municipal solid waste according to claim 1, characterized in that, Steps (1) to (4) are carried out in a closed workshop, which is equipped with a negative pressure dust removal and deodorization system. Production water is recycled to achieve zero wastewater discharge.

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