Method for processing and converting coal gangue into ecological soil

Abstract

The application discloses a method for processing and converting coal gangue into ecological soil, S1, degradation pretreatment: adding a degradation agent to the coal gangue in an aerobic environment at a temperature of greater than or equal to 20 DEG C; S2, crushing and screening: crushing the pretreated coal gangue to a target particle size; S3, high-temperature activation: calcining and activating at 400-950 DEG C at a temperature rising rate of 3 DEG C / min-20 DEG C / min to realize gradient temperature rising programmed decomposition of the coal gangue; S4, heavy metal passivation: adding a passivation agent to generate an acidic complexing / chelating reaction with metal ions for 12-72 h to reduce harmful components; and S5, curing and modification: adding a modifier and treating for 2-24 h to obtain the ecological soil. The method is used to solve the problems of heavy metal pollution, insufficient organic matter, slow conversion, high cost and complex process in traditional treatment of the coal gangue, and provides an environment-friendly, efficient and low-cost ecological soil preparation method.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and ecological governance technology, and in particular to a method for processing and converting coal gangue into ecological soil. Background Technology

[0002] Coal gangue is a solid waste generated during coal mining and washing. Its massive stockpiling not only occupies land but also poses serious environmental risks such as dust pollution, leaching pollution of water and soil, and migration of heavy metals. Traditional disposal methods (such as landfill and open-air dumping) are unsustainable and do not meet the requirements of sustainable development. There is an urgent need to explore large-scale, high-value, and safe resource utilization pathways.

[0003] Existing technologies for converting coal gangue into eco-soil often involve crushing the coal and then adding acids, alkalis, binders, and straw. These methods suffer from high costs, significant risks of heavy metal residue, low conversion efficiency, and long operating cycles, making them unsuitable for large-scale ecological restoration. For example, patent CN 118947491 A fails to consider the heavy metal risks in coal gangue and requires a reaction period of over 30 days to complete the eco-soil conversion, resulting in excessively long degradation times. Patent CN 117243086 A simply mixes crushed coal gangue with sand to obtain improved eco-soil, without improving the nutrient content or environmental risks of the coal gangue. Therefore, there is an urgent need for a coal gangue-to-eco-soil conversion technology to achieve the harmless and resource-based transformation of coal gangue, reducing harmful components and improving the performance of eco-soil. Summary of the Invention

[0004] In view of the above-mentioned problems, the purpose of this invention is to provide a method for processing and converting coal gangue into ecological soil. This method solves the problems of heavy metal pollution, insufficient organic matter, slow conversion, high cost and complex process in the traditional treatment of coal gangue, and provides an environmentally friendly, efficient and low-cost method for preparing ecological soil.

[0005] To address the problems in the existing technology, the technical solution adopted by this invention is as follows:

[0006] A method for processing and converting coal gangue into eco-friendly soil includes the following steps:

[0007] S1 degradation pretreatment: Add degradation agent to coal gangue in an aerobic environment at a temperature ≥20℃;

[0008] S2 crushing and screening: crushing the pretreated coal gangue to the target particle size;

[0009] S3 High Temperature Activation: Calcination activation at 400-950℃, with a heating rate of 3℃ / min-20℃ / min, to achieve gradient heating program decomposition of coal gangue;

[0010] S4 heavy metal passivation: Add passivating agent and react with metal ions in an acidic complexation / chelation reaction for 12-72 hours;

[0011] S5 maturation and modification: Add modifier and treat for 2-24 hours to obtain ecological soil.

[0012] Furthermore, the degrading agent is water rich in ozone and carbon dioxide, and the mass ratio of the degrading agent to coal gangue is no greater than 1:10000, with a pretreatment time of 0.3-48 hours.

[0013] Furthermore, the ozone concentration is 60-100 mg / L, and the carbon dioxide concentration is 1000-1200 mg / L.

[0014] Furthermore, the passivating agent is a high-temperature catalytic oxygenation product of a mixture of seaweed sludge and the bottom layer of duck farm manure, and the amount of passivating agent added is 0.03-0.10% of the mass of coal gangue.

[0015] Furthermore, the addition ratio of the seaweed sludge to the bottom layer of duck farm manure is 6-7:3-4, and the high-temperature catalytic conditions are 180-220℃, 0.5MPa O2, and 1-3h.

[0016] Furthermore, the modifier is an amphoteric organic small molecule containing amine, hydroxyl, carboxyl, quinone and short side chain small carbon rings, and the amount of modifier added is 0.05-0.30% of the mass of coal gangue.

[0017] Furthermore, the modifier comprises lignin degradation product sulfonate, tea polyphenol-iron complex and red wine lees fermentation product, with the mass ratio of each component being 4-6:2-3:2-3.

[0018] Furthermore, the fermentation product of the red wine lees is the fermentation product of one or more red wine lees selected from Cabernet Sauvignon, Pinot Noir, or Merlot.

[0019] Furthermore, in step S2, the target particle size is 60-1000 mesh, preferably 80-200 mesh.

[0020] The performance indicators of the obtained ecological soil are as follows: (1) Organic phase 5-300g / Kg; pH value 6.0-9.5; Tclp-Cd: (2) Complies with GB5085.3 standard; (3) TN: 0.2-3.0g / Kg; TP: 5-400mg / Kg; TK: 5-500mg / Kg; (4) Agricultural use, EC and heavy metals meet or exceed GB15618 control standards; (5) Ecological soil for engineering meets the requirements of "Greening Planting Land" (CJ / T340); (6) Safety assessment meets the requirements of "Solid Waste Leaching Toxicity Leaching Method" (HJ / T299-2007); (7) TSi: 0.5-60%; TFe / Al component 0.2-25%; (8) Cost is 60% lower than conventional.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. The processing technology involved in this invention operates continuously and efficiently throughout the entire process, reducing energy consumption and costs. The resulting ecological soil products can be used for land improvement, ecological restoration, environmental management, and planting applications in environmental scenarios such as forestry, animal husbandry, agriculture, greening, tidal flats, river and lakeside land, abandoned mines, coal mining subsidence areas, and solid waste dumps. They can also be used for the treatment of acidified land, saline-alkali land, and environmentally polluted land.

[0023] 2. This invention employs a high-temperature activation method, which restructures the mineral structure of coal gangue, greatly enhancing the activity of mineral elements. The resulting product is rich in essential nutrients for plant growth, environmental and soil ecological restoration, such as potassium, nitrogen, phosphorus, calcium, iron, magnesium, silicon, aluminum, and sulfur, as well as appropriate amounts of trace elements and usable minerals such as zinc, copper, manganese, boron, molybdenum, nickel, and selenium. These beneficial minerals can balance and replenish soil mineral nutrients, improve soil fertility, reduce pests and diseases, and decrease the amount of chemical fertilizers used, thereby achieving the effect of soil quality improvement.

[0024] 3. This invention, through high-temperature activation, can reduce the content of heavy metals, harmful elements, and toxic organic matter in coal gangue under pyrolysis, oxygenation, and gasification, thereby reducing agricultural non-point source pollution, inhibiting soil acidification, regulating soil pH balance, and alleviating soil compaction.

[0025] 4. This invention controls the activation temperature between 400-950℃, balancing activation effectiveness and energy efficiency. Excessive temperature reduces mineral activity and dramatically increases energy consumption. Furthermore, excessively high temperatures can damage the heavy metal encapsulation structure, increasing the risk of leaching of some heavy metals.

[0026] 5. The high-temperature bursting effect of this invention can increase the porosity and specific surface area of ​​coal gangue particles, thereby increasing the adsorption of nutrients in the soil and improving the nutrient absorption efficiency of crops; moreover, the high-temperature bursting effect promotes particle refinement, improves the permeability of ecological soil, and improves soil structure.

[0027] 6. The modifier involved in this invention is an amphoteric organic small molecule that regulates the physical and chemical properties of soil;

[0028] 7. The metal passivating agent involved in this invention has a dual effect of acidic complexation and chelation with metal ions, which can further reduce harmful components in coal gangue and fix heavy metals for a long time.

[0029] 8. The degradation agent involved in this invention is inexpensive, low-carbon, and environmentally friendly, achieving high-efficiency degradation with extremely low addition amount (<0.01%). Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] The degradation agent involved in Examples 1-4 below is water rich in ozone and carbon dioxide, wherein the ozone concentration is 80 mg / L and the carbon dioxide concentration is 1000 mg / L.

[0032] The passivating agent involved in Examples 1-4 below is a high-temperature catalytic oxygenation product of a mixture of seaweed sludge and the bottom layer of duck farm manure, with an addition ratio of 2:1. The high-temperature catalytic conditions are 190°C, 0.5MPa O2, and 2h.

[0033] The modifiers involved in Examples 1-4 below are composed of: lignin degradation product sulfonate + tea polyphenol-iron complex + Cabernet Sauvignon wine lees fermentation product, with a mass ratio of 2:1:1.

[0034] Example 1

[0035] This embodiment discloses a method for processing and converting coal gangue into ecological soil, and its application in the preparation of high-fertility ecological soil for farmland improvement. Raw material: high-organic-matter coal gangue (TSi = 15%, TFe = 8%, initial organic phase value 80 g / kg), and the specific processing method is as follows:

[0036] 1. In a ventilated and aerobic environment at 30℃, add a degradation agent to coal gangue at a mass ratio of 1:50000 and treat continuously for 12 hours;

[0037] 2. The pretreated coal gangue is impact crushed to 300 mesh;

[0038] 3. Activate the crushed coal gangue at high temperature. When the temperature is below 400℃, increase the temperature at 5℃ / min and hold for 30min. When the temperature is between 400℃ and 700℃, increase the temperature at 12℃ / min. When the temperature is between 700℃ and 850℃, increase the temperature at 18℃ / min and hold for 50min.

[0039] 4. Add 0.05% heavy metal passivating agent to the activated coal gangue and react for 24 hours;

[0040] 5. Add 0.12% modifier to the coal gangue obtained in step 4 above, and perform aging and modification treatment for 6 hours;

[0041] 6. Finished powder packaging with moisture protection.

[0042] Obtained ecological soil performance data:

[0043] Organic phase 210 g / kg, pH 7.3, Tclp-Cd 0.2 mg / L (GB5085.3 limit 1.0 mg / L);

[0044] TN 2.8g / kg, TP 380mg / kg, TK 480mg / kg (meeting the requirements of Solanaceae crops);

[0045] EC value 1.2 mS / cm, other heavy metals are 50% below the limit of GB15618.

[0046] Cost: 85 yuan / ton (220 yuan / ton for conventional process)

[0047] Example 2:

[0048] This embodiment discloses the application of a method for processing and converting coal gangue into ecological soil in the preparation of ecological soil for coastal saline soil improvement (reduced EC type). The raw material is high-sodium coal gangue (initial EC = 8.2 mS / cm, TSi = 22%, pH = 10.5). The specific processing method is as follows:

[0049] 1. In a ventilated and aerobic environment at 25℃, add a 1:60000 degradation agent to the coal gangue and treat continuously for 12 hours.

[0050] 2. The pretreated coal gangue is impact crushed to 200 mesh.

[0051] 3. Activate the crushed coal gangue at high temperature. When the temperature is below 400℃, increase the temperature at 3℃ / min and hold for 30min. When the temperature is between 400℃ and 600℃, increase the temperature at 15℃ / min. When the temperature is between 600℃ and 800℃, increase the temperature at 18℃ / min and hold for 50min.

[0052] 4. Add 0.04% heavy metal passivating agent to the activated coal gangue and react for 48 hours.

[0053] 5. Add 0.08% modifier to the coal gangue obtained in step 4 above, and perform aging and modification treatment for 6 hours.

[0054] 6. Packaging of finished powder products.

[0055] Obtained ecological soil performance data:

[0056] EC value 0.9 mS / cm (GB15618 limit < 1.5 mS / cm), pH value 8.1, organic phase 120 g / kg;

[0057] TN 1.8g / kg, TP 280mg / kg;

[0058] Tclp-Cd 0.08mg / L (GB5085.3 limit 1.0mg / L), cost 70 yuan / ton (commercially available saline-alkali amendment costs 350 yuan / ton).

[0059] Example 3:

[0060] This embodiment discloses the application of a method for processing and converting coal gangue into ecological soil in the preparation of high-fertility ecological soil for saline-alkali land improvement. The raw material is high-calcium coal gangue (TSi = 18%, TFe = 6%, initial pH 10.2). The specific processing method is as follows:

[0061] 1. In a ventilated and aerobic environment at 30℃, add a degradation agent to coal gangue at a mass ratio of 1:100000 and treat continuously for 2 hours.

[0062] 2. The pretreated coal gangue is impact crushed to 300 mesh.

[0063] 3. Activate the crushed coal gangue at high temperature. When the temperature is below 400℃, increase the temperature at 5℃ / min. When the temperature is between 400℃ and 650℃, increase the temperature at 12℃ / min. When the temperature is between 650℃ and 850℃, increase the temperature at 20℃ / min and hold for 40 minutes.

[0064] 4. Add 0.03% heavy metal passivating agent to the activated coal gangue and react for 36 hours.

[0065] 5. Add 0.1% modifier to the coal gangue obtained in step 4 above, and perform aging and modification treatment for 8 hours.

[0066] 6. Finished powder packaging with moisture protection.

[0067] Obtained ecological soil performance data:

[0068] pH value 8.3, organic phase 185 g / kg, EC value 0.8 mS / cm (GB15618 limit <1.5 mS / cm);

[0069] TN 2.5g / kg, TP 320mg / kg, TK 420mg / kg, meeting the fertilizer requirements of rice;

[0070] Tclp-Cd 0.15mg / L (GB5085.3 limit 1.0mg / L), cost 78 yuan / ton (210 yuan / ton for conventional process).

[0071] Example 4: This example discloses the application of a method for processing and converting coal gangue into ecological soil in the preparation of soil for remediation of heavy metal contaminated sites. Raw material: Cr / Ni-containing coal gangue (Cr: 85 mg / kg, Ni: 120 mg / kg). The specific processing method is as follows:

[0072] 1. In a ventilated and aerobic environment at 40℃, add a degradation agent to coal gangue at a mass ratio of 1:10000 and treat continuously for 24 hours;

[0073] 2. The pretreated coal gangue is impact crushed to 800 mesh;

[0074] 3. Activate the crushed coal gangue at high temperature. When the temperature is below 450℃, increase the temperature at a rate of 6℃ / min and hold for 40min; when the temperature is between 450℃ and 800℃, increase the temperature at a rate of 10℃ / min and hold for 60min.

[0075] 4. Add 0.08% heavy metal passivating agent to the activated coal gangue and react for 60 hours;

[0076] 5. Add 0.25% modifier to the coal gangue obtained in step 4 above, and perform aging and modification treatment for 12 hours;

[0077] 6. Finished powder packaging with moisture protection.

[0078] Obtained ecological soil performance data:

[0079] pH value 7.8, organic phase 235g / kg;

[0080] Tclp-Cr 0.02 mg / L, Tclp-Ni 0.03 mg / L (HJ / T299 limits: Cr 0.1 mg / L, Ni 0.5 mg / L)

[0081] Bioavailable Cr decreased by 92%;

[0082] Cost: 135 yuan / ton (800 yuan / ton for professional repair materials).

[0083] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for processing and converting coal gangue into eco-friendly soil, characterized in that, Includes the following steps: S1 degradation pretreatment: Add degradation agent to coal gangue in an aerobic environment at a temperature ≥20℃; S2 crushing and screening: crushing the pretreated coal gangue to the target particle size; S3 high-temperature activation: calcination activation at 400-950℃, heating rate 3℃ / min-20℃ / min; S4 heavy metal passivation: Add passivating agent and react for 12-72 hours; S5 maturation and modification: Add modifier and treat for 2-24 hours to obtain ecological soil; The degradation agent is water rich in ozone and carbon dioxide; The passivating agent is a high-temperature catalytic oxygen decomposition product of a mixture of seaweed sludge and the bottom layer of duck farm manure; The modifier is an amphoteric organic small molecule containing amine, hydroxyl, carboxyl, quinone groups and short side chain small carbon rings.

2. The method for processing and converting coal gangue into ecological soil as described in claim 1, characterized in that, The mass ratio of the degrading agent to coal gangue is no greater than 1:10000, and the pretreatment time is 0.3-48 hours.

3. The method for processing and converting coal gangue into ecological soil as described in claim 2, characterized in that, The ozone concentration is 60-100 mg / L, and the carbon dioxide concentration is 1000-1200 mg / L.

4. The method for processing and converting coal gangue into ecological soil as described in claim 1, characterized in that, The amount of passivating agent added is 0.03-0.10% of the mass of coal gangue.

5. The method for processing and converting coal gangue into ecological soil as described in claim 4, characterized in that, The addition ratio of the seaweed sludge to the bottom layer of duck farm manure is 6-7:3-4, and the high-temperature catalytic conditions are 180-220℃, 0.5MPaO2, and 1-3h.

6. The method for processing and converting coal gangue into ecological soil as described in claim 1, characterized in that, The amount of modifier added is 0.05-0.30% of the mass of coal gangue.

7. The method for processing and converting coal gangue into ecological soil as described in claim 6, characterized in that, The modifier consists of lignin degradation product sulfonate, tea polyphenol-iron complex and red wine lees fermentation products, with a mass ratio of 4-6:2-3:2-3.

8. The method for processing and converting coal gangue into ecological soil as described in claim 7, characterized in that, The fermentation product of the red wine lees is the fermentation product of one or more red wine lees selected from Cabernet Sauvignon, Pinot Noir or Merlot.

9. A method for processing and converting coal gangue into ecological soil as described in claim 1, characterized in that, In step S2, the target particle size is 60-1000 mesh.

10. A method for processing and converting coal gangue into ecological soil as described in claim 1, characterized in that, The ecological soil contains 5-300 g / kg of organic phase, 0.2-3.0 g / kg of total nitrogen (TN), 5-400 mg / kg of total phosphorus (TP), and 5-500 mg / kg of total potassium (TK); the pH value is 6.0-9.5.