Coal gangue and fine solid waste co-processing and solidification method

Abstract

This invention discloses a method for solidifying and stockpiling coal gangue and fine solid waste, comprising the following construction steps: Step 1, stockpiling the main skeleton; Step 2, internal expansion treatment; Step 3, external expansion treatment; Step 4, online detection of slurry properties, including online detection of the solid content, spreadability, viscosity, and initial setting time of the liquid slurry used. The overall construction method uses coarse aggregate coal gangue as the main skeleton for stockpiling. A slurry with an adjustable solid content of 35%~40% is prepared using fly ash / desulfurized gypsum / bottom slag solid waste as a pumping substrate to internally expand and fill the gaps in the main skeleton of the stockpile, resulting in a final porosity of ≤5%, far below the critical porosity for spontaneous combustion. The oxygen diffusion coefficient is reduced by more than 99%, failing to meet the oxygen demand of the oxidation reaction, and the residual carbon oxidation reaction is completely stopped. Simultaneously, the alkaline substances in the slurry neutralize the acidic substances produced by oxidation, further inhibiting the oxidation reaction and preventing spontaneous combustion.

Description

Technical Field

[0001] This invention relates to the field of solid waste storage and treatment technology in the coal gangue industry, and in particular to a method for solidifying and stockpiling coal gangue and fine solid waste together. Background Technology

[0002] my country is a major producer and consumer of coal. Coal gangue, a large-scale general industrial solid waste generated during coal mining and washing, has an annual increase of about 650 million tons, with a cumulative stockpile of over 7 billion tons. There are currently more than 2,000 gangue piles, covering an area of ​​over 200,000 mu (approximately 13,333 hectares). About 30% of these gangue piles pose a risk of spontaneous combustion. Coal gangue is one of the industrial solid wastes in my country with the largest stockpile, the most land occupation, and the most prominent environmental risks.

[0003] The current mainstream storage process for coal gangue is "truck transport + paving and compaction," which has four major irreversible drawbacks: First, the storage capacity utilization rate is extremely low. Coal gangue has a large particle size and high porosity, and the effective storage capacity is only 60% to 70% of the design value. Many storage yards will run out of capacity in 3 to 5 years, facing huge land acquisition and new construction costs. Second, the risk of spontaneous combustion cannot be eliminated. The high porosity of the loose pile provides a channel for oxygen diffusion, and the continuous oxidation of residual carbon will cause spontaneous combustion, resulting in a very high risk of environmental penalties. Third, the stability of the pile is poor. Loose piles are prone to landslides and collapses, and the height and slope of the pile are strictly limited, further reducing the storage capacity. Fourth, the co-processing capacity is weak. It is unable to simultaneously dispose of fine-particle solid wastes such as fly ash and desulfurization gypsum generated by power plants and coal chemical enterprises, and both types of solid waste face disposal challenges. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the co-solidification and stockpiling of coal gangue and fine solid waste, so as to solve the problem of coal gangue stockpiling and disposal.

[0005] The technical solution of this invention: a method for co-solidifying and stockpiling coal gangue and fine solid waste, comprising the following processing steps:

[0006] Step 1: The main framework is stockpiled, with coarse aggregate coal gangue as the main framework.

[0007] Step 2, internal expansion treatment: fly ash / desulfurized gypsum / bottom slag solid waste is used as pumping base material, and water and fast-hardening coagulant are added according to the ratio to prepare an adjustable fluid slurry with a solid content of 35%~40%. The obtained slurry is pressurized by a slurry pump and transported to the landfill through a closed pipeline to fill the gaps in the main skeleton of the pile body to form a solidified body.

[0008] Step 3, external expansion treatment, the resulting solidified body has an unconfined compressive strength ≥2.5MPa, an internal friction angle of 40°~45°, a safe stacking height of 60~80m, and a solidified body stacking slope of 45°-50°;

[0009] Step four: Online detection of slurry properties, including the solid content, spread, viscosity, and initial setting time of the liquid slurry used.

[0010] Furthermore, the coarse aggregate coal gangue in step one has a particle size range of 5mm-100mm.

[0011] Furthermore, the fly ash in step two has a particle size of <0.045mm and a dry basis mass ratio of 72% to 97%.

[0012] Furthermore, in step two, the particle size of the rapid-hardening coagulant is <0.15mm, and the dry basis mass ratio is in the range of 3%~8%.

[0013] Furthermore, in step two, the desulfurized gypsum has a particle size of <0.15mm and a dry basis weight percentage of 0%~20%.

[0014] Furthermore, in step two, the bottom slag particle size is <0.15mm, and the dry basis mass ratio is in the range of 0%~20%.

[0015] Furthermore, in step two, after the slurry fills the gaps in the main skeleton of the pile, the void ratio of the pile is ≤5%.

[0016] The beneficial effects of this invention compared to existing technologies are as follows: The overall construction method uses coarse aggregate coal gangue as the main skeleton for stockpiling. A slurry with an adjustable solid content of 35%~40% is prepared using fly ash / desulfurized gypsum / bottom slag solid waste as a pumping substrate to internally expand and fill the gaps in the main skeleton of the stockpile, resulting in a final porosity of ≤5%, far below the critical porosity for spontaneous combustion. The oxygen diffusion coefficient is reduced by more than 99%, failing to meet the oxygen demand of the oxidation reaction, and the residual carbon oxidation reaction is completely stopped. Simultaneously, the alkaline substances in the slurry neutralize the acidic substances produced by oxidation, further inhibiting the oxidation reaction and expanding the external solidified body. With the same land area, the storage capacity can be increased by 2 to 3 times, achieving a comprehensive expansion effect of 2 to 5 times. The process of using waste to treat waste, coarse and fine solid waste, gravity injection, and rapid hardening and drying completely solves the core problem of large-diameter coal gangue that cannot be pumped. The process is extremely simple and the construction efficiency is high. There are a large number of mature fly ash injection and mine backfilling engineering cases to support it, which can be implemented quickly. It can simultaneously treat two types of bulk industrial solid waste, namely coal gangue (coarse solid waste) and fly ash, desulfurization gypsum, etc. (fine solid waste), without the need to add additional raw materials such as cement and sand. All raw materials are industrial solid waste, which not only solves the problem of coal gangue storage, but also meets the disposal needs of fine solid waste. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the construction process framework of the present invention. Detailed Implementation

[0018] 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, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0020] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0021] See Figure 1 The present invention discloses a method for the co-solidification and stockpiling of coal gangue and fine solid waste, comprising the following processing steps:

[0022] Step 1: Main skeleton stockpiling, with coarse aggregate coal gangue as the main stockpiling skeleton, the particle size range of coarse aggregate coal gangue is 5mm-100mm;

[0023] Step two, internal expansion treatment: using fly ash / desulfurization gypsum / bottom slag solid waste as the pumping substrate, water and a rapid-hardening coagulant are added according to the specified ratio to prepare an adjustable fluid slurry with a solid content of 35%~40%. The slurry spread is ≥350mm, and the viscosity is ≤800mPa·s. Under natural gravity, the effective penetration radius can reach 8~10m. For a 50m×40m unit pool, only 2~3 injection ports need to be set up at the pool edge to achieve full-section coverage without dead corners, without the need for grouting pipes or pressure grouting. The obtained slurry is pressurized by a slurry pump and then transported to the landfill through a closed pipeline to fill the gaps in the main skeleton of the pile and form a solidified body. After the slurry fills the gaps in the main skeleton of the pile, the porosity of the pile is ≤5%, which is far below the critical porosity for spontaneous combustion. The oxygen diffusion coefficient is reduced by more than 99%, which cannot meet the oxygen demand of the oxidation reaction, and the residual carbon oxidation reaction is completely stopped. At the same time, the alkaline substances in the slurry can neutralize the acidic substances produced by oxidation, further inhibiting the oxidation reaction and eliminating spontaneous combustion at the source, without the need for subsequent fire prevention and extinguishing.

[0024] The fly ash in step two has a particle size of <0.045mm and a dry basis weight ratio ranging from 72% to 97%. It is the core substrate of the slurry, making it the most abundant main material in the slurry. Its core function is to ensure the slurry has excellent pumpability and self-flowing permeability, fully fill all the voids in the spread coal gangue, and provide basic structural strength for the solidified body, perfectly aligning with the project's core positioning of "treating waste with waste and synergistically disposing of large quantities of fine solid waste."

[0025] The fast-setting coagulant used has a particle size of <0.15mm and a dry basis weight ratio of 3%~8%. It is the core component for adjusting the slurry function, used to regulate the initial setting time of the slurry, ensuring a construction window of 4~12h, and significantly improving the early strength, overall density and structural stability of the solidified body. This ensures that the retaining wall can be demolded 15~24h after grouting and that the pile can be used for upper-level operations 24h after grouting. The final solidified body has an unconfined compressive strength ≥2.5MPa, meeting the requirements for storage safety and prevention of spontaneous combustion. This dosage range also takes into account the performance requirements and project cost control needs.

[0026] The desulfurized gypsum has a particle size <0.15mm and a dry basis weight percentage of 0%~20%, while the bottom ash has a particle size <0.15mm and a dry basis weight percentage of 0%~20%. Desulfurized gypsum and bottom ash serve as auxiliary base materials to optimize slurry pumping stability and improve the density of the solidified body. They can be added in combination with desulfurized gypsum to further expand the scope of co-processing of fine solid waste. Both can be added individually, in combination, or not at all, but their combined dry basis weight percentage should not exceed 20%. Adding these two components aims to further co-process bulk industrial fine solid waste and increase the amount of solid waste co-processed. Not adding them will not have a substantial adverse effect on the core pumping performance, self-flowing filling performance, or core mechanical properties of the solidified body. Conventional slurry pumps can smoothly pump particles with a permissible diameter of 5mm, achieving a conveying distance of over 1000m. Micron-sized particles can completely penetrate and fill the millimeter-sized voids in coal gangue without the risk of pipe blockage or wear. After the coal gangue and slurry solidify in situ, they form an integral solidified pile with no loose or weak layers. The unconfined compressive strength is ≥2.5MPa, the shear strength is 5 to 8 times higher than that of traditional piles, and the internal friction angle is increased to 40° to 45°. It can withstand extreme conditions such as earthquakes and heavy rainfall, and completely eliminate safety risks such as landslides, collapses, debris flows, and dam failures.

[0027] Step 3, external expansion treatment, the resulting solidified body has an unconfined compressive strength ≥2.5MPa, an internal friction angle of 40°~45°, a safe stacking height of 60~80m, and a stacking slope of 45°-50°; by filling the voids in the coal gangue with slurry, the final porosity of the stack is reduced from 35%~50% to ≤5%, and the dry density of the stack is increased from 1.4~1.6t / m³ to 1.9~2.1t / m³. Under the same volume, slope, and stacking height conditions, the coal gangue stockpile is increased by more than 35%, while simultaneously disposing of solid wastes such as fly ash and desulfurization gypsum, thus improving space utilization.

[0028] Step four involves online testing of the slurry properties, including the solids content, spread, viscosity, and initial setting time of the liquid slurry. The solids content should be controlled between 35% and 40%. The testing method involves installing an online densitometer on the main slurry pumping pipeline. The "slurry density - solids content" correspondence is pre-calibrated in the laboratory and input into the device. The device can measure the slurry density in real time, automatically calculate the real-time solids content, and update the data every second, providing continuous online monitoring without manual operation. The slurry spread should be no less than 350mm; this is a key indicator to ensure the slurry can flow freely and fill all the voids in the coal gangue. The testing method involves connecting a bypass automatic sampling pipeline to the discharge port of the pulping station, equipped with an online automatic spreadability detector. The instrument automatically takes a sample every 5-10 minutes, simulating the manual spreadability measurement process: automatic filling and unloading of the slurry, and then measuring the diameter of the spread slurry, providing the result directly without manual intervention. The slurry viscosity must not exceed 800 mPa·s; this is crucial for ensuring smooth pumping and preventing pipe blockage. The testing method involves installing an online vibratory viscometer on the main pumping pipeline. The equipment monitors the slurry viscosity in real time, automatically alarming when the value exceeds the set upper limit. Continuous monitoring is maintained throughout the process, eliminating the need for manual sampling and testing. The initial setting time of the slurry must be controlled within 4-12 hours; this is a key indicator for controlling the construction window and preventing premature solidification and pipe blockage, or slow solidification that delays subsequent construction. The testing method involves equipping the slurry with an online automatic setting time meter. Each batch of slurry is produced, and the instrument automatically takes a sample. By periodically measuring the hardening resistance in the slurry sample, the instrument can predict and output the initial setting time of the slurry in real time, thus accurately controlling the construction time.

[0029] The above processing methods can be applied to different sites to realize the storage and treatment of solid waste such as coal gangue and fly ash / desulfurization gypsum / bottom slag, including flat landfills / gangue hills, valley landfills, and open-pit mine backfilling.

[0030] Specifically, the core adaptability of flat landfill / gangue pile construction is: it is suitable for building new coal gangue landfills on flat land and expanding and renovating existing gangue piles on plains, without natural mountain barriers, and artificially constructing U-shaped safety barriers to maximize storage capacity.

[0031] Core layout: Taking a standard 500m×400m site as an example, an 8m wide Z-shaped turnaround uphill lane is reserved on the east side (maximum slope ≤8%, to meet the needs of heavy-duty dump trucks and semi-trailers). The north, south and west sides are constructed with U-shaped three-sided enclosed and solidified outer embankments, forming a basin-like closed structure with "high outside and low inside".

[0032] The specific steps are as follows:

[0033] Step 1, Construction of the Three-Sided Solidified Outer Dam: Modularly constructed reusable plastic steel molds are erected in 50m×50m standard units. The first unit pool is supported by four molds, while adjacent unit pools share the pre-formed retaining wall, requiring only three molds to be erected, maximizing mold reuse and reducing material consumption; fine solid waste slurry is poured into the molds, and after filling, it is left to stand naturally for 15-24 hours to reach the demolding strength, after which the mold is removed to form the unit retaining wall; the demolded unit pools are filled with fine solid waste slurry for curing to form a solid dam body, with a single dam section width of 50m and a single layer height of 1m; the construction of 26 unit pools on three sides is completed in a cycle to form a U-shaped integral outer dam, ensuring that the top surface of the dam body is always 1m higher than the internal filling surface throughout the process, forming a natural safety barrier against slurry leakage and collapse.

[0034] Step 2, Internal Basin-Style Circulating Filling and Solidification: The central area is divided into 6 independent working blocks. A temporary sub-dam is built in each block (no mold required, ultimately buried in the pile body, no waste generated), with a 4-6m wide access opening for vehicles. Dump trucks unload coal gangue into Block 1, and loaders spread it to a thickness of 80cm without compaction, retaining natural gaps to facilitate slurry penetration. After Block 1 is paved, the dump trucks instantly switch to Block 2 to continue unloading, with zero interruption and no waiting during the entire coal gangue feeding process. Simultaneously, slurry injection is started in Block 1, with the slurry level at 20cm. Relying on gravity flow, it completely fills all the gaps in the coal gangue. After filling, it is left to stand and dry for 24 hours to form an integral solidified pile body. The 6 blocks operate in a cyclical manner, with paving and grouting completely parallel, without any downtime or waiting, suitable for daily processing capacities of tens of thousands of tons.

[0035] Specifically, the core compatibility of valley-type landfills is as follows: It is suitable for valley-type / gully-type coal gangue landfills, with natural mountain walls on both sides, a high-level feed inlet at one end and a low-level valley outlet at the other end, which effectively solves the risks of dam failure and coal gangue slippage at the valley outlet.

[0036] Core dam design: A single, wide-body solidified dam is constructed at the valley exit, traversing the valley and seamlessly connecting the two sides of the mountain. It employs a "double parallel retaining wall + solid infill in the middle" structure, with a fixed net distance of 200m between the two retaining walls. The single formwork height is 1m; for every 1m increase in height, both retaining walls simultaneously contract inward by 50cm. For every 5m cumulative increase, the outer retaining wall contracts inward by 2-3m at once, forming a maintenance passage. The dam's length is widened in sync with the valley's natural "narrow at the bottom, wide at the top" shape.

[0037] The specific steps are as follows:

[0038] Step 11, Valley bottom foundation treatment: Clear loose soil, loose rocks and accumulated water from the valley bottom outlet area, level and compact the entire foundation area of ​​the dam body, with a compaction degree ≥93%, to ensure that the foundation bearing capacity meets the standards;

[0039] The axes of the two parallel retaining walls upstream and downstream were precisely laid out and marked. The distance between the two axes was fixed at 200m. The two ends of the axes were seamlessly connected to the slopes on both sides of the mountain, without gaps or disconnections.

[0040] Step 22, Construction of the first-layer wide-body dam: Two parallel fixed plastic steel molds are erected along the marked axis. Only the front and rear facades of the retaining walls need to be erected. The left and right ends use the mountain as natural side molds, without the need for additional molds. The height of each mold is 1m. Fine solid waste slurry is poured into the molds simultaneously. After drying for 15-24 hours to reach the demolding strength, the molds are demolded to form two 1m high parallel solidified retaining walls, which enclose a 200m wide closed large cell. Using an excavator, a temporary retaining wall is built every 50m along the length of the dam within the large cell, dividing the large cell into multiple 50m long independent grouting chambers to solve the core problem of uneven grout flow and incomplete filling in large-volume grouting. Fine solid waste slurry is continuously poured from one side of the mountain to the other chamber by chamber. After filling, it is cured to form the first-layer 1m high and 200m wide integral solidified dam.

[0041] Step 33, gradual increase and graded contraction: Repeat the process of "formwork erection → formwork removal → temporary compartmentation → compartmentalized grouting". The height of each formwork erection is always kept at 1m. For every 1m of upward construction, the two retaining walls simultaneously contract 50cm into the valley. For every 5m of cumulative height (completing 5 cycles of 1m units), the upstream outer retaining wall contracts 2-3m into the valley at once, forming a 2-3m wide maintenance passage. Settlement and displacement monitoring points are set up simultaneously. The dam body gradually widens upward with the valley topography, always maintaining a seamless connection with the mountains on both sides, with no disconnection or risk of leakage.

[0042] Step 44, Coordinated internal coal gangue landfill: For every 1m layer of dam construction completed, a 1m thick layer of coal gangue is simultaneously landfilled internally, ensuring that the top surface of the dam is always 0.5~1m higher than the internal landfill surface throughout the process; temporary sub-dams are built in the internal area, and after the dump trucks feed and spread the material, the feed inlet is sealed and grout is injected simultaneously to fill all the voids in the coal gangue, achieving root-cause prevention of spontaneous combustion; the dam construction and internal landfill are completely parallel, adapting to the continuous operation requirements of a daily processing capacity of 10,000 tons.

[0043] Step 55, Mountain Shape Connection and Process Transition: After the dam body is built to the lowest connection elevation of the two mountains, the natural barrier of the valley disappears, and the smooth transition is to the flat three-sided dam construction process. Continue to build upwards to the final design elevation.

[0044] Specifically, the core adaptability of open-pit mine backfilling for land reclamation is: it is suitable for natural basin-shaped sites such as open-pit coal mines and quarries. The pit walls are fully enclosed natural barriers, eliminating the need for artificial dam construction. The process is the simplest, the fastest, and the lowest in cost, simultaneously achieving solid waste disposal and land reclamation.

[0045] The specific steps are as follows:

[0046] Step 111, pit foundation treatment: clean up the loose soil, accumulated water and dangerous rocks at the bottom of the pit, level the working base, check the stability of the pit wall slope, and set up the pit top drainage system to prevent rainwater from washing into the pit; the pulping station is built at the entrance of the mine pit slope, and the conveying pipeline is laid along the mine pit slope to the working face, which can be extended upwards in sync with the pile height.

[0047] Step 222, Central Radial Circulating Filling: The mine pit is divided into multiple 50m×50m large-sized working blocks, and the operation begins from the first block at the center of the pit bottom; dump trucks enter the site from the mine pit ramp and directly dump coal gangue into the target block, and the loader spreads it to a thickness of 80cm without compaction; after the block is spread, the dump trucks instantly switch to the adjacent block and advance outward from the center as the origin, with zero interruption in coal gangue feeding throughout the process; at the same time, fine solid waste slurry is injected into the spread block to completely fill the voids in the coal gangue and fully encapsulate the particles, and after drying for 24 hours, a solidified pile is formed; the operation is repeated until the entire first layer of the mine pit is filled.

[0048] Step 333, layered stacking: After the first layer is filled, repeat the "central radial zoning operation" on the upper layer directly. No retaining wall pouring is required. Just make sure that when each layer is laid, the perimeter of the block is 5-10cm higher than the center to form a shallow basin structure to prevent the grout from overflowing. Stack the grout layer by layer until it is backfilled to the design elevation. There are no redundant procedures throughout the process, and the work efficiency is maximized.

[0049] Step 44, Site Closure and Land Reclamation: After the mine pit is backfilled to the design elevation, the top is leveled and compacted, and the entire area is equipped with a drainage and seepage prevention system. Because the pile is an integral solidified structure, there is no uneven settlement or risk of spontaneous combustion in the later stage. It can be directly used for farmland reclamation, industrial construction land, and ecological park construction, realizing a closed loop of solid waste disposal and land resource regeneration.

[0050] More specifically, the construction of flat landfills / gangue hills, valley landfills, and open-pit mine backfilling also includes layered cyclic storage. After all the work blocks of the first layer are completed and dried to meet the standards, the construction of the upper layer begins. In flat / valley-shaped scenarios, the upper retaining wall / dam body is recessed inward by 0.5~1.0m relative to the edge of the lower layer, and the retaining wall / dam body pouring process is repeated to form the upper working surface. The core process of "coal gangue spreading → gravity-flow injection → drying for 24 hours" is repeated to complete the construction of the upper unit. The storage is carried out in a cyclical and layer-by-layer manner, with a 2m wide inspection platform set up every 5m of height. At the same time, settlement, displacement, and temperature monitoring points are set up to monitor the stability of the pile in real time. The stepped inward-recessed pile structure, combined with high-strength solidified body, can achieve a 45° safe pile slope, and the maximum safe pile height can reach 60~80m, maximizing the storage capacity. The finishing process involves fully covering and leveling the top of the pile and all slopes, eliminating the need for an additional impermeable layer; improving the drainage system of the top of the pile and slopes by constructing intercepting ditches and drainage ditches to prevent rainwater erosion and infiltration; and laying planting soil on the covering layer to carry out vegetation restoration, thus completing the closed loop of the entire life cycle.

[0051] In addition to the preferred embodiments described above, the present invention has other embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection claimed by the present invention.

Claims

1. A method for co-solidifying and stockpiling coal gangue and fine solid waste, characterized in that, The processing steps include the following: Step 1: The main framework is stockpiled, with coarse aggregate coal gangue as the main framework. Step 2, internal expansion treatment: fly ash / desulfurized gypsum / bottom slag solid waste is used as pumping base material, and water and fast-hardening coagulant are added according to the ratio to prepare an adjustable fluid slurry with a solid content of 35%~40%. The obtained slurry is pressurized by a slurry pump and transported to the landfill through a closed pipeline to fill the gaps in the main skeleton of the pile body to form a solidified body. Step 3, external expansion treatment, the resulting solidified body has an unconfined compressive strength ≥2.5MPa, an internal friction angle of 40°~45°, a safe stacking height of 60~80m, and a solidified body stacking slope of 45°-50°; Step four: Online detection of slurry properties, including the solid content, spread, viscosity, and initial setting time of the liquid slurry used.

2. The method for co-solidification and stockpiling of coal gangue and fine solid waste according to claim 1, characterized in that, The coarse aggregate coal gangue in step two has a particle size range of 5mm-100mm.

3. The method for co-solidification and stockpiling of coal gangue and fine solid waste according to claim 1, characterized in that, The fly ash in step two has a particle size of <0.045mm and a dry basis weight ratio of 72% to 97%.

4. The method for co-solidification and stockpiling of coal gangue and fine solid waste according to claim 1, characterized in that, In step two, the particle size of the rapid-hardening coagulant is <0.15mm, and the dry basis mass ratio is 3%~8%.

5. The method for co-solidification and stockpiling of coal gangue and fine solid waste according to claim 2, characterized in that, In step two, the desulfurized gypsum has a particle size of <0.15mm and a dry basis weight percentage of 0% to 20%.

6. The method for co-solidification and stockpiling of coal gangue and fine solid waste according to claim 4, characterized in that, In step two, the bottom slag particle size is <0.15mm, and the dry basis mass ratio is 0%~20%.

7. The method for co-solidification and stockpiling of coal gangue and fine solid waste according to claim 1, characterized in that, In step two, the slurry fills the gaps in the main skeleton of the stack, resulting in a stack porosity of ≤5%.

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