Coal gangue decarburization and desulfurization pretreatment and ecological backfilling process

Abstract

The application discloses a coal gangue decarburization and desulfurization pretreatment and ecological backfilling process and relates to the technical field of coal gangue treatment and ecological restoration. The process is characterized in that: firstly, the coal gangue is subjected to three-stage crushing and intelligent photoelectric separation to separate carbon components and gangue components; the gangue components are subjected to photocatalysis-microwave synergistic desulfurization, microwave pretreatment and double-parameter dynamic adjustment decarburization treatment, mixed with various solid wastes, and subjected to fermentation by adding a bacteria agent-water retention agent composite system to prepare ecological backfilling base materials; the base materials are backfilled in layers and composite geotextiles are laid; ecological soil containing a nano modifier is laid on the surface; real-time monitoring is performed through a spectrum-multiple-parameter integrated device; an acid liquid-nutrient synergistic adjustment module is started; and dynamic regulation and control are performed in combination with a self-adaptive model. The application realizes the synergy of harmless treatment and resource utilization of the coal gangue, improves the stability and vegetation adaptability of the ecological backfilling, and provides an efficient solution for the ecological restoration of a mining area.

Description

Technical Field

[0001] This invention belongs to the field of coal gangue treatment and ecological restoration technology, specifically involving a coal gangue decarbonization and desulfurization pretreatment and ecological backfilling process. Background Technology

[0002] Coal mining and processing generate a large amount of coal gangue, a major industrial solid waste. Its long-term accumulation not only occupies significant land resources but also releases carbon and sulfur-containing pollutants and heavy metals through weathering and leaching, polluting surrounding soil, water, and air, disrupting the ecological balance, and posing a risk of spontaneous combustion, seriously threatening the safety of the mining area and its surrounding environment. With increasingly stringent requirements for ecological protection and resource recycling, the harmless disposal and resource utilization of coal gangue have become the core direction of industry development. Among these, using coal gangue for ecological backfilling in mining areas after decarbonization and desulfurization pretreatment, achieving synergy between "waste-to-waste" treatment and ecological restoration of the mining area, has become the mainstream technological approach.

[0003] Current pretreatment technologies for decarbonization and desulfurization of coal gangue have several limitations: desulfurization often relies on single microwave or alkaline treatment, lacking a multi-field synergistic mechanism, resulting in catalyst loss and insufficient activity, leading to low desulfurization efficiency; during decarbonization, the gas ratio is often fixed without dynamic adjustment based on the residual components of the coal gangue, making it difficult to stably control the carbon and sulfur residues within the allowable range for ecological backfilling. In the preparation of ecological backfill substrates, microbial agents and water-retaining agents are often added independently. The activity of microbial agents is easily affected by the environment, and the water-retaining agent has limited water-locking and slow-release effects. Furthermore, the substrate lacks compatibility with the backfill geotextile and surface ecological soil, easily leading to problems such as uneven compaction and an imbalance between impermeability and air permeability.

[0004] Furthermore, existing monitoring and control technologies after ecological backfilling mostly focus on single indicators, triggering adjustments solely through soil pH or heavy metal content, without considering the coupled effects of multiple parameters such as vegetation growth status and soil porosity. The adjustment logic lacks adaptive optimization capabilities. This results in poor soil ecological environment stability in the backfilled area, large pH fluctuations, low vegetation survival rates, and difficulty in achieving long-term stable ecological restoration effects. Existing technologies cannot simultaneously balance coal gangue treatment efficiency, backfill layer structural stability, and ecological adaptability, failing to meet the actual needs of ecological restoration in mining areas. Therefore, a comprehensive process integrating efficient pretreatment, high-performance substrate preparation, and intelligent ecological control is urgently needed. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides a pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue, which solves the problems of low decarbonization and desulfurization efficiency, insufficient adaptability of backfill layer structure to ecology, and unstable ecological restoration effect caused by lack of multi-parameter coupling optimization in monitoring and control in the prior art.

[0006] To address the above problems, the present invention provides the following technical solution: A pretreatment process for decarbonization and desulfurization of coal gangue and an ecological backfilling process, comprising the following steps: S1. The coal gangue is subjected to three-stage crushing. After the first stage of crushing, the particle size is controlled at 120mm~160mm, after the second stage of crushing, the particle size is controlled at 60mm~80mm, and after the third stage of crushing, the particle size is controlled at ≤50mm to obtain uniform crushed material. S2. Intelligent photoelectric sorting equipment is used to sort uniform crushed material to separate carbon components and gangue components, with a sorting accuracy of ≥95% and a sorting speed of ≥20t / h; S3. The gangue component is fed into a photocatalytic-microwave synergistic desulfurization reactor, and a mixed alkaline solution of NaOH-EDTA is added. A modified attapulgite-supported composite catalyst was used for synergistic desulfurization by simultaneously introducing ultraviolet light with a wavelength of 365nm~400nm. The concentration of the mixed alkali solution was 1.0mol / L~1.8mol / L, and the mass ratio of NaOH to EDTA was 8:2~9:1. The supported composite catalyst... The mass ratio of the modified attapulgite to the catalyst is 1:4 to 1:6, the catalyst addition is 0.3% to 0.6% of the mass of the gangue component, the microwave power is 500W to 700W, the liquid-solid ratio is 10:1 to 12:1, the reaction temperature is 80℃ to 85℃, and the reaction time is 35min to 50min to obtain desulfurized gangue. S4. The desulfurized gangue is first subjected to microwave pretreatment with a power of 300W~400W for 10min~15min, followed by segmented temperature-controlled decarbonization treatment. The residual sulfur and carbon content of the desulfurized gangue are first detected, and the treatment is dynamically adjusted according to the two parameters. and The mixing volume ratios were as follows: 1.2:8.8 when sulfur residue > 0.5% and carbon residue > 4%; 1.8:8.2 when sulfur residue ≤ 0.5% and carbon residue > 4%; 1.5:8.5 when sulfur residue > 0.5% and carbon residue ≤ 4%; and 2:8 when sulfur residue ≤ 0.5% and carbon residue ≤ 4%. The temperature was raised to 380℃~420℃ for the first 30 minutes of decarbonization, and then kept constant for the next 30~50 minutes to obtain decarbonized and desulfurized gangue. S5. Decarbonized and desulfurized gangue is mixed with fly ash, desulfurized gypsum, and modified attapulgite. A composite microbial agent-polyacrylamide water-retaining agent system is added and fermented. The mass ratio of decarbonized and desulfurized gangue, fly ash, desulfurized gypsum, and modified attapulgite is 65:20:15:5. The composite microbial agent is composed of Thiobacillus thiooxidans, Bacillus subtilis, and Bacillus mucilaginosus in a mass ratio of 1.2:1:0.8. The mass ratio of polyacrylamide water-retaining agent to composite microbial agent is 3:1. The amount of the composite system added is 0.8%~1.2% of the total mass of the mixture. The fermentation temperature is 30℃~32℃, and the fermentation time is 5d~6d to obtain the ecological backfill substrate. S6. Transport the ecological backfill material to the backfill area for layered backfilling. Each layer should be 35mm-40mm thick and compacted to a compaction degree of ≥90%. A breathable and impermeable composite geotextile should be laid between every two layers. The geotextile is made of polyester fiber, polyvinyl chloride fiber, and nano-montmorillonite blended and interwoven in a mass ratio of 7:3:0.5. The geotextile's permeability coefficient is [missing value]. The thickness of the geotextile is 2mm~3mm; S7. Lay ecological soil on the surface of the backfill layer. The ecological soil is a mixture of ecological backfill substrate, humus, polyacrylamide water-retaining agent, and nano-silica sol in a mass ratio of 8:2:0.3:0.1. Slow-release fertilizer is added to the ecological soil at a rate of 3% of the total mass of the ecological soil. The slow-release fertilizer contains N, , The mass ratio is 4:1.5:1.5; S8. A spectrum-sensor integrated monitoring and control device is used to monitor the backfill area in real time. The monitoring indicators include soil pH, heavy metal content, vegetation growth status and soil porosity. The monitoring density is one monitoring point per 80m²~100m², and the monitoring frequency is data collection once every 12h~24h. The vegetation growth status is realized by collecting the normalized vegetation index through the vegetation spectrum sensor. S9. When the integrated monitoring and control device detects that the soil pH value is >8.5 or the normalized vegetation index is <0.6, it automatically activates the acid-nutrient synergistic regulation module, applying a mixed solution of organic acid and trace elements to the topsoil. The concentration of organic acid in the mixed solution is 0.3mol / L~0.4mol / L, and the concentration of trace elements is... The mixture is composed of a molar ratio of 2:1:1 and a concentration of 0.01 mol / L to 0.02 mol / L. The application rate of the mixed solution is 1 L / m² to 1.5 L / m², and the soil pH is adjusted to 6.5 to 8.5. S10. Continuously collect data through an integrated monitoring and control device. Based on the changing trends of soil pH, heavy metal content, normalized vegetation index, and soil porosity, establish a multi-parameter coupled adaptive regulation model to dynamically adjust the concentration, application amount, and application frequency of the mixed solution to maintain the ecological stability of the backfill area.

[0007] Further, in step S3, the modification treatment of the attapulgite involves soaking it in a 3 mol / L hydrochloric acid solution for 2 hours, then adding 1%~2% silane coupling agent KH550 and ultrasonically dispersing it for 30 minutes, followed by drying at 110℃ to constant weight. Here, the hydrochloric acid soaking removes impurities from the attapulgite, and the ultrasonic dispersion modification with the silane coupling agent increases its specific surface area and surface active sites, enhancing its compatibility with... The binding force of the catalyst is optimized to prevent it from falling off and being lost during the desulfurization process. At the same time, the adsorption performance is optimized to help capture the sulfur components in the gangue and ensure stable desulfurization efficiency.

[0008] Furthermore, in step S3 The preparation method of the modified attapulgite supported composite catalyst is as follows: and Mix at a mass ratio of 1:3 to 1:5, add modified attapulgite clay and 5% to 8% polyvinyl alcohol binder, grind, and then calcine at 550℃ to 600℃ for 2 hours. (This is a limited description.) and The mass ratio ensures the density of catalytic active centers in the catalyst; the addition of polyvinyl alcohol binder and control of calcination temperature and time can improve the structural stability and mechanical strength of the catalyst, prevent collapse during high-temperature reactions, and ensure the continuous and efficient photocatalytic-microwave synergistic desulfurization.

[0009] Furthermore, in step S4, the carbon residue is measured using a high-frequency infrared carbon-sulfur analyzer with a detection accuracy of ≤0.01%. The use of a high-frequency infrared carbon-sulfur analyzer here allows for accurate acquisition of carbon residue data from the desulfurized gangue, providing a precise basis for the dynamic adjustment of the decarbonization gas ratio using the dual parameters of "sulfur residue + carbon residue" in step S4. This avoids incomplete decarbonization or excessive oxidation due to errors in carbon residue detection.

[0010] Furthermore, in step S5, the polyacrylamide water-retaining agent has a molecular weight of 8 million to 12 million and is modified by gamma ray irradiation with an irradiation dose of 5 kGy to 10 kGy. This limited molecular weight range ensures the water-locking ability of the water-retaining agent. Gamma ray irradiation modification optimizes its molecular structure, improves its water absorption rate and slow-release performance, and forms a synergistic effect with the composite microbial agent. This provides a stable and moist environment for the agent while slowly releasing moisture, maintaining stable humidity during fermentation and enhancing the bioactivity of the ecological backfill substrate.

[0011] Furthermore, in step S7, the particle size of the nano-silica sol is 20nm~50nm, and the solid content is 20%~30%. The nano-silica sol with these limited particle size and solid content can be uniformly dispersed in the ecological soil, filling soil pores and forming a stable network structure. This enhances the compressive strength and water and fertilizer retention capacity of the ecological soil, while also strengthening its adhesion to plant roots, promoting root growth, and improving the ecological restoration effect.

[0012] Furthermore, the integrated spectral-sensing monitoring and control device in step S8 includes a spectral acquisition unit, a multi-parameter sensing unit, a data transmission unit, a controller unit, and an execution unit. The multi-parameter sensing unit includes a pH sensor, a heavy metal ion sensor, and a porosity sensor. Clearly defining the composition of each functional unit here enables coordinated operation of the entire process, from spectral acquisition and simultaneous multi-parameter monitoring to data transmission and execution control. The porosity sensor supplements key monitoring dimensions, ensuring the comprehensiveness and accuracy of the monitoring data in step S8 and providing data support for subsequent multi-parameter coupled control.

[0013] Furthermore, in step S9, the organic acid is a mixture of citric acid and oxalic acid in a molar ratio of 2:1, and the trace elements are stabilized by EDTA chelation. Here, the specific molar ratio of citric acid and oxalic acid is used to adjust the pH value while avoiding damage to the soil and vegetation; EDTA chelation of trace elements prevents their oxidation and precipitation, ensuring… The effectiveness of this technology ensures that essential nutrients are provided for vegetation growth, achieving a synergistic effect between pH regulation and nutrient supplementation.

[0014] Furthermore, when the sulfur content of the coal gangue is >2.0%, the concentration of the mixed alkaline solution in step S3 is adjusted to 1.6mol / L~1.8mol / L, the ultraviolet wavelength is adjusted to 365nm, and the reaction time is extended to 45min~50min. In step S4, the microwave pretreatment power is increased to 400W, the decarburization temperature is increased to 410℃~420℃, and the decarburization time is extended to 70min~80min. This approach, targeting coal gangue with excessive sulfur content, enhances the desulfurization effect by increasing the concentration of the mixed alkaline solution, adjusting the ultraviolet wavelength, and extending the reaction time. Increasing the microwave pretreatment power, decarburization temperature, and time thoroughly removes residual carbon and sulfur, preventing high-sulfur coal gangue from exceeding its standards after treatment, ensuring it meets ecological backfill requirements, and expanding the applicability of the process.

[0015] Furthermore, in step S10, the input parameters of the multi-parameter coupled adaptive adjustment model are soil pH, heavy metal content, normalized vegetation index (NVI), and soil porosity, while the output parameters are mixed solution concentration, application amount, and application frequency. The model is trained and optimized using a BP neural network algorithm. The use of a BP neural network algorithm to train the model here enables precise coupled analysis of multiple parameters such as soil pH, heavy metal content, NVI, and soil porosity, dynamically optimizing the concentration, application amount, and frequency of the mixed solution. This avoids the limitations of single-parameter adjustment and ensures the long-term stability of the ecological environment in the backfill area.

[0016] This invention relates to a coal gangue decarbonization and desulfurization pretreatment and ecological backfilling process, focusing on the efficient and harmless disposal of coal gangue and the long-term ecological restoration of mining areas. First, uniform raw materials are obtained through three-stage crushing. Carbon components are then separated using intelligent photoelectric sorting for resource recovery. Next, photocatalysis-microwave synergistic desulfurization, combined with a supported composite catalyst, is employed to enhance desulfurization efficiency and prevent catalyst loss. Microwave pretreatment is added before decarbonization, and the gas ratio is dynamically adjusted based on sulfur and carbon parameters to ensure that carbon and sulfur residues meet standards. In substrate preparation, a microbial agent-water-retaining agent composite system is used to improve biological activity and moisture stability. During backfilling, modified composite geotextile is used to ensure structural stability and a balance between air permeability and seepage prevention. Nano-silica sol is added to the surface ecological soil to optimize physical properties and nutrient retention capacity. The monitoring process integrates spectral and multi-parameter sensing technologies, combined with acid-nutrient synergistic regulation and a BP neural network adaptive model, to achieve dynamic control of multiple coupled indicators. Ultimately, a synergistic process of "pretreatment-substrate preparation-backfilling-regulation" is formed, balancing treatment efficiency, structural stability, and ecological compatibility.

[0017] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention uses photocatalysis-microwave synergistic desulfurization combined with a supported composite catalyst to enhance the multi-field coupling effect and catalyst immobilization effect. Combined with microwave pretreatment before decarbonization and dynamic adjustment of the gas ratio of sulfur and carbon dual parameters, it achieves efficient removal of carbon and sulfur components, and the residual amount is stably controlled within the allowable range for ecological backfilling, thus avoiding the problem of incomplete treatment by a single process. (2) The present invention adopts a microbial agent-water-retaining agent composite system. The water-retaining agent not only locks in water but also provides a slow-release carrier for the microbial agent, thereby enhancing the activity and sustainability of the microbial agent. It also works synergistically with the fermentation of various solid wastes, so that the substrate has good biological activity, nutrient supply capacity and structural stability, and is suitable for the growth needs of vegetation. (3) The modified composite geotextile of the present invention combines air permeability and seepage prevention through multi-component blending and weaving, ensuring uniform compaction and structural stability of the backfill layer; the addition of nano silica sol to the ecological soil optimizes the soil physical structure and water and fertilizer retention capacity, promotes the rooting of vegetation, and enhances the ecological adaptability of the backfill area. (4) The integrated spectrometer-multi-parameter device of the present invention realizes simultaneous monitoring of multiple indicators such as soil pH value and vegetation growth status. Combined with the acid-nutrient synergistic regulation module and the BP neural network adaptive model, a multi-parameter coupled dynamic regulation mechanism is formed, which effectively maintains the ecological environment stability of the backfill area and avoids the limitations of single indicator regulation. (5) The present invention uses intelligent photoelectric sorting to recover carbon components in coal gangue, realizing resource reuse; it also synergistically disposes of industrial solid waste such as fly ash and desulfurization gypsum, reducing solid waste storage pollution. The entire process generates no secondary pollution, which is in line with the concept of "treating waste with waste" and ecological environmental protection. (6) This invention optimizes the desulfurization and decarbonization parameters for high-sulfur coal gangue. By adjusting the concentration of alkali solution, reaction time, decarbonization temperature, etc., it ensures that the high-sulfur coal gangue meets the standards after treatment, expands the process's adaptability to coal gangue with different sulfur contents, and meets the actual needs of ecological restoration in various mining areas. Attached Figure Description

[0018] Figure 1 This is a flowchart of a coal gangue decarbonization and desulfurization pretreatment and ecological backfilling process according to the present invention. Detailed Implementation

[0019] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0020] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0022] Example 1

[0023] refer to Figure 1 A pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue according to the present invention includes the following steps: S1. The coal gangue is subjected to three-stage crushing. The particle size is controlled at 140mm after the first stage crushing, 70mm after the second stage crushing, and ≤50mm after the third stage crushing to obtain uniform crushed material. S2. Intelligent photoelectric sorting equipment is used to sort uniform crushed material to separate carbon components and gangue components. The sorting accuracy is 95% and the sorting speed is 20t / h. S3. The gangue component is fed into a photocatalytic-microwave synergistic desulfurization reactor, and a mixed alkaline solution of NaOH-EDTA is added. A modified attapulgite-supported composite catalyst was used for synergistic desulfurization by simultaneously introducing ultraviolet light with a wavelength of 380 nm. The mixed alkaline solution concentration was 1.4 mol / L, and the mass ratio of NaOH to EDTA was 8.5:1.5. The supported composite catalyst... The mass ratio of modified attapulgite to the catalyst was 1:5, the catalyst addition was 0.45% of the gangue component mass, the microwave power was 600W, the liquid-to-solid ratio was 11:1, the reaction temperature was 82℃, and the reaction time was 42min, resulting in desulfurized gangue. The modified attapulgite was treated by soaking in 3mol / L hydrochloric acid solution for 2h, followed by ultrasonic dispersion with 1.5% silane coupling agent KH550 for 30min, and drying at 110℃ to constant weight. The supported composite catalyst was prepared by... and Mix at a mass ratio of 1:4, add modified attapulgite and 6.5% polyvinyl alcohol binder, grind and then calcine at 580℃ for 2 hours; S4. The desulfurized gangue is first subjected to microwave pretreatment with a power of 350W for 12 minutes, followed by segmented temperature-controlled decarbonization. The residual sulfur and carbon content of the desulfurized gangue are first determined using a high-frequency infrared carbon-sulfur analyzer with a detection accuracy of 0.01%, and then dynamically adjusted according to dual parameters. and The mixing volume ratios were as follows: 1.2:8.8 when sulfur residue > 0.5% and carbon residue > 4%; 1.8:8.2 when sulfur residue ≤ 0.5% and carbon residue > 4%; 1.5:8.5 when sulfur residue > 0.5% and carbon residue ≤ 4%; and 2:8 when sulfur residue ≤ 0.5% and carbon residue ≤ 4%. The temperature was raised to 400℃ for the first 30 minutes of decarbonization and then kept constant for the next 40 minutes to obtain decarbonized and desulfurized gangue. S5. Decarbonized and desulfurized gangue was mixed with fly ash, desulfurized gypsum, and modified attapulgite. A composite microbial agent-polyacrylamide water-retaining agent system was added, and fermentation was carried out. The mass ratio of decarbonized and desulfurized gangue, fly ash, desulfurized gypsum, and modified attapulgite was 65:20:15:5. The composite microbial agent was composed of Thiobacillus thiooxidans, Bacillus subtilis, and Bacillus mucilaginosus in a mass ratio of 1.2:1:0.8. The mass ratio of polyacrylamide water-retaining agent to composite microbial agent was 3:1. The polyacrylamide water-retaining agent had a molecular weight of 10 million and was modified by gamma ray irradiation with an irradiation dose of 8 kGy. The amount of the composite system added was 1.0% of the total mass of the mixture. The fermentation temperature was 31℃, and the fermentation time was 5.5 days, resulting in an ecological backfill substrate. S6. Transport the ecological backfill material to the backfill area for layered backfilling. Each layer is 38mm thick and compacted to a compaction degree of ≥90%. A breathable and impermeable composite geotextile is laid between every two layers. The geotextile is a blend of polyester fiber, polyvinyl chloride fiber, and nano-montmorillonite in a mass ratio of 7:3:0.5. The geotextile's permeability coefficient is... The geotextile thickness is 2.5mm; S7. Lay ecological soil on the surface of the backfill layer. The ecological soil is a mixture of ecological backfill substrate, humus, polyacrylamide water-retaining agent, and nano-silica sol in a mass ratio of 8:2:0.3:0.1. The nano-silica sol has a particle size of 35nm and a solid content of 25%. Slow-release fertilizer is added to the ecological soil at a rate of 3% of the total mass of the ecological soil. The slow-release fertilizer contains N, , The mass ratio is 4:1.5:1.5; S8. A spectrum-sensor integrated monitoring and control device is used to monitor the backfill area in real time. The monitoring indicators include soil pH value, heavy metal content, vegetation growth status and soil porosity. The monitoring density is one monitoring point per 90m², and the monitoring frequency is data collection once every 18 hours. The vegetation growth status is realized by collecting the normalized vegetation index through the vegetation spectrum sensor. The spectrum-sensor integrated monitoring and control device includes a spectrum acquisition unit, a multi-parameter sensing unit, a data transmission unit, a controller unit and an execution unit. The multi-parameter sensing unit includes a pH sensor, a heavy metal ion sensor and a porosity sensor. S9. When the integrated monitoring and control device detects that the soil pH value is >8.5 or the normalized vegetation index is <0.6, it automatically activates the acid-nutrient synergistic regulation module, applying a mixed solution of organic acid and trace elements to the topsoil. The organic acid in the mixed solution is a mixture of citric acid and oxalic acid in a molar ratio of 2:1 with a concentration of 0.35 mol / L, and the trace elements are... The mixture is composed of a molar ratio of 2:1:1 and a concentration of 0.015 mol / L. The trace elements are stabilized by EDTA chelation. The application rate of the mixed solution is 1.2 L / m², and the soil pH is adjusted to 6.5~8.5. S10. Continuously collect data through an integrated monitoring and control device. Based on the changing trends of soil pH, heavy metal content, normalized vegetation index, and soil porosity, establish a multi-parameter coupled adaptive regulation model. The input parameters of the model are soil pH, heavy metal content, normalized vegetation index, and soil porosity. The output parameters are mixed solution concentration, application amount, and application frequency. The model is trained and optimized through a BP neural network algorithm to dynamically adjust the concentration, application amount, and application frequency of the mixed solution to maintain the ecological stability of the backfill area.

[0024] Example 2

[0025] The difference between this embodiment and Embodiment 1 is that in step S3, the supported composite catalyst... In the preparation method of the supported composite catalyst with a mass ratio of 1:4 to modified attapulgite clay, and Mix at a mass ratio of 1:3, and the remaining steps and parameters are completely consistent with those in Example 1.

[0026] Example 3

[0027] The difference between this embodiment and Embodiment 1 is that in step S4, the dynamic adjustment logic for the two decarbonization parameters is as follows: when the sulfur residue is >0.5% and the carbon residue is >4%. and The mixing volume ratio was 1.0:9.0, the heat preservation time after decarburization was 35 min, and the remaining steps and parameters were completely consistent with those in Example 1.

[0028] Example 4

[0029] The difference between this embodiment and Embodiment 1 is that in step S5, the mass ratio of polyacrylamide water-retaining agent to composite microbial agent in the composite microbial agent-polyacrylamide water-retaining agent composite system is 2:1, the amount of composite system added is 0.9% of the total mass of the mixture, and the irradiation dose of polyacrylamide water-retaining agent is 6 kGy. The remaining steps and parameters are completely consistent with Embodiment 1.

[0030] Example 5

[0031] The difference between this embodiment and Example 1 is that the sulfur content of the coal gangue is 2.2%, the concentration of the mixed alkaline solution in step S3 is adjusted to 1.7 mol / L, the ultraviolet wavelength is adjusted to 365 nm, and the reaction time is extended to 48 min; in step S4, the microwave pretreatment power is increased to 400 W, the decarburization temperature is increased to 415 °C, and the decarburization time is extended to 75 min; the remaining steps and parameters are completely consistent with Example 1.

[0032] Comparative Example 1

[0033] The difference between this comparative example and Example 1 is that no additive is added in step S3. The modified attapulgite-supported composite catalyst was used for desulfurization without ultraviolet light. The desulfurization process employed a microwave-NaOH-EDTA mixed alkaline solution with a concentration of 1.4 mol / L, a NaOH to EDTA mass ratio of 8.5:1.5, a microwave power of 600 W, a liquid-to-solid ratio of 11:1, a reaction temperature of 82 °C, and a reaction time of 42 min. All other steps and parameters were identical to those in Example 1.

[0034] Comparative Example 2

[0035] The difference between this comparative example and Example 1 is that microwave pretreatment of the desulfurized gangue is not performed in step S4, and the decarbonization is fixed. and The mixing volume ratio was 2:8. The residual sulfur and carbon content were not measured. The temperature was raised to 400°C for 30 minutes before decarbonization and then kept constant for the next 40 minutes. The remaining steps and parameters were completely consistent with those in Example 1.

[0036] Comparative Example 3

[0037] The difference between this comparative example and Example 1 is that the composite microbial agent-polyacrylamide water-retaining agent composite system is not used in step S5. Instead, 0.75% of the total mass of the mixture of composite microbial agent and 0.25% of the total mass of polyacrylamide water-retaining agent are added separately. The composition of the composite microbial agent and the parameters of the polyacrylamide water-retaining agent are the same as those in Example 1. The remaining steps and parameters are completely the same as those in Example 1.

[0038] Comparative Example 4

[0039] The difference between this comparative example and Example 1 is that pure polyester fiber geotextile is used in step S6, and the geotextile's permeability coefficient is... The thickness is 2.5mm; in step S7, the ecological soil is made by mixing ecological backfill substrate, humus and polyacrylamide water-retaining agent in a mass ratio of 8:2:0.3, without adding nano silica sol, and the remaining steps and parameters are completely consistent with those in Example 1.

[0040] Comparative Example 5

[0041] The difference between this comparative example and Example 1 is that in step S8, only the soil pH value is monitored using a common pH sensor, with one monitoring point per 90 m² and data collected every 18 hours. No spectral acquisition unit or porosity sensor is used. In step S9, a 0.35 mol / L citric acid solution is applied only when the soil pH value is >8.5, at a rate of 1.2 L / m². In step S10, no multi-parameter coupled adaptive adjustment model is established; the amount of citric acid solution applied is adjusted only according to the pH value change. The remaining steps and parameters are completely consistent with those of Example 1.

[0042] Comparative Example 6

[0043] The difference between this comparative example and Example 1 is that in step S1, a primary crushing process is used to directly crush the coal gangue to a particle size ≤50mm; in step S3, conventional NaOH alkaline solution desulfurization is used with an alkaline solution concentration of 1.4mol / L, a liquid-to-solid ratio of 11:1, a reaction temperature of 82℃, and a reaction time of 42min, without microwave or catalyst assistance; in step S4, pure... Decarbonization is performed at a temperature of 800℃ for 60 minutes, without microwave pretreatment. In step S5, only 1.0% of the total mass of the mixture of sulfur-oxidizing bacteria is added, the fermentation temperature is 31℃, and the fermentation time is 5.5 days. In step S6, the backfill thickness is 38mm, the compaction degree is ≥90%, and no geotextile is laid. In step S7, ordinary soil with a humus content of 20% is directly laid, without adding slow-release fertilizer or polyacrylamide water-retaining agent. In step S8, no special monitoring is performed, only the soil pH value is manually measured once every 7 days. In steps S9 and S10, no automatic adjustment module is set. When the pH value is abnormal, dilute hydrochloric acid is manually applied for adjustment. The remaining steps and parameters are performed according to the traditional ecological backfilling process.

[0044] Test method: 1. Carbon content: According to GB / T212-2008 "Industrial Analysis Methods for Coal", the carbon content was calculated by measuring the loss on ignition of coal gangue after treatment using a high-frequency infrared carbon-sulfur analyzer. 2. Sulfur content: According to GB / T214-2007 "Determination of total sulfur in coal", sulfur is converted into sulfate by the Eska method, and the sulfur content is calculated by titration. 3. Desulfurization efficiency: Calculated by dividing the difference between the sulfur content of coal gangue before treatment and the sulfur content after treatment by the sulfur content before treatment; 4. Decarbonization efficiency: Calculated by dividing the difference between the carbon content of coal gangue before and after treatment by the carbon content before treatment. 5. Substrate bioactivity (relative value): The soil microbial respiration intensity method (alkali absorption method) was used to determine the amount of organic matter released by microorganisms decomposing the substrate within 24 hours. The quantity was calculated as a relative value with the result of Example 1 as 100. 6. Backfill compaction: According to GB / T50123-2019 "Standard for Geotechnical Testing Methods", backfill soil samples were collected using the ring cutter method, the dry density was determined, and the compaction was calculated based on the maximum dry density. 7. Soil pH stability (range): Using a portable pH meter, surface soil samples were collected daily at representative monitoring points in the backfill area for 30 consecutive days to measure pH values ​​and record the fluctuation range. 8. Normalized Difference Vegetation Index (NDVI): The Normalized Difference Vegetation Index (NDVI) is calculated by collecting vegetation reflectance spectral data of the backfilled area using a vegetation spectral sensor. 9. Vegetation survival rate: Three 10m×10m quadrats were evenly set up in the backfilled area. The total number of initially planted vegetation and the number of surviving plants after 30 days were counted, and the percentage of surviving plants was calculated. 10. Applicable range of sulfur content in coal gangue: Select coal gangue with different sulfur contents and process it according to the corresponding process. By testing whether the sulfur content after treatment meets the standard, determine the sulfur content range suitable for the process.

[0045] Table 1: Experimental Results of Examples 1-5 and Comparative Examples 1-6 Case Carbon content (%) Sulfur content (%) Desulfurization efficiency (%) Decarbonization efficiency (%) bioactivity of substrate Backfill layer compaction degree (%) Soil pH stability Normalized Difference Vegetation Index Vegetation survival rate (%) Applicable range of sulfur content in coal gangue (%) Example 1 ≤3.2 ≤0.15 ≥95.0 ≥94.5 100 92 6.8-8.2 ≥0.75 95 0.2-2.0 Example 2 ≤3.3 ≤0.16 ≥94.5 ≥94.0 98 92 6.8-8.3 ≥0.74 94 0.2-2.0 Example 3 ≤3.4 ≤0.15 ≥95.0 ≥93.5 99 92 6.8-8.2 ≥0.74 94 0.2-2.0 Example 4 ≤3.2 ≤0.15 ≥95.0 ≥94.5 95 91 6.9-8.3 ≥0.73 93 0.2-2.0 Example 5 ≤3.5 ≤0.18 ≥94.0 ≥93.0 97 91 6.8-8.4 ≥0.72 92 2.0-3.0 Comparative Example 1 ≤3.3 ≤0.45 ≥78.0 ≥94.5 99 92 6.8-8.3 ≥0.73 88 0.2-1.0 Comparative Example 2 ≤4.5 ≤0.16 ≥94.5 ≥85.0 98 92 6.7-8.4 ≥0.70 86 0.2-1.5 Comparative Example 3 ≤3.2 ≤0.15 ≥95.0 ≥94.5 70 91 6.6-8.5 ≥0.65 80 0.2-1.5 Comparative Example 4 ≤3.3 ≤0.16 ≥94.5 ≥94.0 97 88 6.5-8.8 ≥0.68 83 0.2-1.5 Comparative Example 5 ≤3.2 ≤0.15 ≥95.0 ≥94.5 98 92 6.2-9.0 ≥0.62 78 0.2-1.0 Comparative Example 6 ≤5.8 ≤0.85 ≥65.0 ≥72.0 55 85 5.8-9.5 ≥0.45 48 0.2-1.0 In summary, as shown in Table 1, the embodiments, through innovative designs such as photocatalytic-microwave synergistic desulfurization, dual-parameter dynamic decarbonization, microbial agent-water-retaining agent composite system, modified backfill materials, and multi-parameter adaptive control, significantly outperform the comparative examples in core indicators such as decarbonization and desulfurization efficiency, substrate bioactivity, backfill layer compaction, soil pH stability, and vegetation adaptability, fully demonstrating the comprehensive advantages of the process of this invention.

[0046] Comparative Example 1 removed both photocatalysis and supported catalysts, relying solely on microwave-alkali desulfurization. The lack of multi-field synergy and catalytic immobilization resulted in a significant decrease in desulfurization efficiency. Comparative Example 2 did not undergo microwave pretreatment and had a fixed decarbonization gas ratio, failing to dynamically adapt reaction conditions based on residual coal gangue components, leading to a significant reduction in decarbonization efficiency. Comparative Example 3 did not employ a microbial agent-water-retaining agent composite system; the lack of synergistic effect between the microbial agent and water-retaining agent resulted in easy loss of microbial agent activity and a significant decline in the biological activity of the substrate. Comparative Example 4 used ordinary geotextile and did not add nano-silica sol to the ecological soil, resulting in insufficient structural stability of the backfill layer and inadequate soil water and fertilizer retention capacity, leading to poor compaction and vegetation indicators. Comparative Example 5 only monitored pH value without an adaptive control model, failing to consider the combined effects of multiple parameters, resulting in large fluctuations in soil pH and limited vegetation growth. Comparative Example 6 used traditional processes, lacking crushing and sorting optimization, efficient pretreatment, specialized substrates, and intelligent control, resulting in incomplete decarbonization and desulfurization, poor backfill stability, and extremely poor ecological restoration effects. Example 1 adopts the basic optimization parameters of the whole process of the present invention, and the synergistic effect of each innovation point is fully exerted. Therefore, the decarbonization and desulfurization efficiency is high, the substrate activity is strong, the backfill is stable and the vegetation adaptability is excellent, and the comprehensive index is the best. Example 2: Adjusting the supported catalyst The ratio of modified attapulgite and and The ratio of the components did not affect the core catalytic activity; only the desulfurization efficiency and sulfur content fluctuated slightly, while the other indicators remained stable. Example 3 optimizes the gas ratio logic and holding time for the dual-parameter adjustment of decarbonization. Although the decarbonization efficiency decreases slightly, it still ensures that the carbon residue meets the standard, and other core indicators are not significantly affected. Example 4: Adjusting the ratio and amount of the microbial agent-water-retaining agent composite system slightly weakened the slow-release protective effect of the water-retaining agent on the microbial agent, resulting in a slight decrease in the biological activity of the substrate and the survival rate of vegetation, while the other indicators remained stable. Example 5 optimizes the key parameters for desulfurization and decarbonization of high-sulfur coal gangue, enhancing the removal effect of high-sulfur components. Although the carbon and sulfur content and decarbonization and desulfurization efficiency are slightly lower than those of the basic example, they still meet the requirements for ecological backfilling and achieve adaptation to high-sulfur coal gangue.

Claims

1. A pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue, characterized in that: Includes the following steps, S1. The coal gangue is subjected to three-stage crushing. After the first stage of crushing, the particle size is controlled at 120mm~160mm, after the second stage of crushing, the particle size is controlled at 60mm~80mm, and after the third stage of crushing, the particle size is controlled at ≤50mm to obtain uniform crushed material. S2. Intelligent photoelectric sorting equipment is used to sort uniform crushed material to separate carbon components and gangue components, with a sorting accuracy of ≥95% and a sorting speed of ≥20t / h; S3. The gangue component is fed into a photocatalytic-microwave synergistic desulfurization reactor, and a mixed alkaline solution of NaOH-EDTA is added. A modified attapulgite-supported composite catalyst was used for synergistic desulfurization by simultaneously introducing ultraviolet light with a wavelength of 365nm~400nm. The concentration of the mixed alkali solution was 1.0mol / L~1.8mol / L, and the mass ratio of NaOH to EDTA was 8:2~9:

1. The supported composite catalyst... The mass ratio of the modified attapulgite to the catalyst is 1:4 to 1:6, the catalyst addition is 0.3% to 0.6% of the mass of the gangue component, the microwave power is 500W to 700W, the liquid-solid ratio is 10:1 to 12:1, the reaction temperature is 80℃ to 85℃, and the reaction time is 35min to 50min to obtain desulfurized gangue. S4. The desulfurized gangue is first subjected to microwave pretreatment with a power of 300W~400W for 10min~15min, followed by segmented temperature-controlled decarbonization treatment. The residual sulfur and carbon content of the desulfurized gangue are first detected, and the treatment is dynamically adjusted according to the two parameters. and The mixing volume ratios were as follows: 1.2:8.8 when sulfur residue > 0.5% and carbon residue > 4%; 1.8:8.2 when sulfur residue ≤ 0.5% and carbon residue > 4%; 1.5:8.5 when sulfur residue > 0.5% and carbon residue ≤ 4%; and 2:8 when sulfur residue ≤ 0.5% and carbon residue ≤ 4%. The temperature was raised to 380℃~420℃ for the first 30 minutes of decarbonization, and then kept constant for the next 30~50 minutes to obtain decarbonized and desulfurized gangue. S5. Decarbonized and desulfurized gangue is mixed with fly ash, desulfurized gypsum, and modified attapulgite. A composite microbial agent-polyacrylamide water-retaining agent system is added and fermented. The mass ratio of decarbonized and desulfurized gangue, fly ash, desulfurized gypsum, and modified attapulgite is 65:20:15:

5. The composite microbial agent is composed of Thiobacillus thiooxidans, Bacillus subtilis, and Bacillus mucilaginosus in a mass ratio of 1.2:1:0.

8. The mass ratio of polyacrylamide water-retaining agent to composite microbial agent is 3:

1. The amount of the composite system added is 0.8%~1.2% of the total mass of the mixture. The fermentation temperature is 30℃~32℃, and the fermentation time is 5d~6d to obtain the ecological backfill substrate. S6. Transport the ecological backfill material to the backfill area for layered backfilling. Each layer should be 35mm-40mm thick and compacted to a compaction degree of ≥90%. A breathable and impermeable composite geotextile should be laid between every two layers. The geotextile is made of polyester fiber, polyvinyl chloride fiber, and nano-montmorillonite blended and interwoven in a mass ratio of 7:3:0.

5. The geotextile's permeability coefficient is [missing value]. The thickness of the geotextile is 2mm~3mm; S7. Lay ecological soil on the surface of the backfill layer. The ecological soil is a mixture of ecological backfill substrate, humus, polyacrylamide water-retaining agent, and nano-silica sol in a mass ratio of 8:2:0.3:0.

1. Slow-release fertilizer is added to the ecological soil at a rate of 3% of the total mass of the ecological soil. The slow-release fertilizer contains N, , The mass ratio is 4:1.5:1.5; S8. A spectrum-sensor integrated monitoring and control device is used to monitor the backfill area in real time. The monitoring indicators include soil pH, heavy metal content, vegetation growth status and soil porosity. The monitoring density is one monitoring point per 80m²~100m², and the monitoring frequency is data collection once every 12h~24h. The vegetation growth status is realized by collecting the normalized vegetation index through the vegetation spectrum sensor. S9. When the integrated monitoring and control device detects that the soil pH value is >8.5 or the normalized vegetation index is <0.6, it automatically activates the acid-nutrient synergistic regulation module, applying a mixed solution of organic acid and trace elements to the topsoil. The concentration of organic acid in the mixed solution is 0.3mol / L~0.4mol / L, and the concentration of trace elements is... The mixture is composed of a molar ratio of 2:1:1 and a concentration of 0.01 mol / L to 0.02 mol / L. The application rate of the mixed solution is 1 L / m² to 1.5 L / m², and the soil pH is adjusted to 6.5 to 8.

5. S10. Continuously collect data through an integrated monitoring and control device. Based on the changing trends of soil pH, heavy metal content, normalized vegetation index, and soil porosity, establish a multi-parameter coupled adaptive regulation model to dynamically adjust the concentration, application amount, and application frequency of the mixed solution to maintain the ecological stability of the backfill area.

2. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 1, characterized in that: The modification treatment of the modified attapulgite in step S3 is as follows: soaking in 3 mol / L hydrochloric acid solution for 2 hours, adding 1%~2% silane coupling agent KH550 for ultrasonic dispersion for 30 minutes, and drying at 110℃ to constant weight.

3. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 1, characterized in that: In step S3 The preparation method of the modified attapulgite supported composite catalyst is as follows: and Mix at a mass ratio of 1:3 to 1:5, add modified attapulgite and 5% to 8% polyvinyl alcohol binder, grind, and then calcine at 550℃ to 600℃ for 2 hours.

4. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 3, characterized in that: In step S4, the residual carbon content is determined by a high-frequency infrared carbon-sulfur analyzer with a detection accuracy of ≤0.01%.

5. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 1, characterized in that: In step S5, the polyacrylamide water-retaining agent has a molecular weight of 8 million to 12 million and is modified by gamma irradiation with an irradiation dose of 5 kGy to 10 kGy.

6. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 1, characterized in that: In step S7, the particle size of the nano-silica sol is 20nm~50nm, and the solid content is 20%~30%.

7. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 6, characterized in that: The integrated spectral-sensing monitoring and control device in step S8 includes a spectral acquisition unit, a multi-parameter sensing unit, a data transmission unit, a controller unit, and an execution unit. The multi-parameter sensing unit includes a pH sensor, a heavy metal ion sensor, and a porosity sensor.

8. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 1, characterized in that: In step S9, the organic acid is a mixture of citric acid and oxalic acid in a molar ratio of 2:1, and the trace elements are stabilized by EDTA chelation.

9. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 1, characterized in that: When the sulfur content of coal gangue is >2.0%, the concentration of the mixed alkaline solution in step S3 is adjusted to 1.6mol / L~1.8mol / L, the ultraviolet wavelength is adjusted to 365nm, and the reaction time is extended to 45min~50min. In step S4, the microwave pretreatment power is increased to 400W, the decarburization temperature is increased to 410℃~420℃, and the decarburization time is extended to 70min~80min.

10. The pretreatment and ecological backfilling process for decarbonization and desulfurization of coal gangue as described in claim 1, characterized in that: In step S10, the input parameters of the multi-parameter coupled adaptive adjustment model are soil pH, heavy metal content, normalized vegetation index and soil porosity, and the output parameters are mixed solution concentration, application amount and application frequency. The model is trained and optimized by a BP neural network algorithm.

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