Method for processing and converting coal gangue into ecological soil

Abstract

The invention discloses a method for processing and converting coal gangue into ecological soil, which comprises the following steps: S1, degradation pretreatment: adding a degradation agent into coal gangue in an aerobic environment at the temperature of more 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 the heating rate of 3-20 DEG C / min to realize gradient heating program decomposition of the coal gangue; s4, heavy metal passivation is conducted, specifically, a passivator is added and subjected to an acid complexing / chelating reaction with metal ions for 12-72 h, and harmful components are reduced; and S5, curing modification: adding a modifier, and treating for 2-24 hours to obtain the ecological soil. The method is used for solving the problems of heavy metal pollution, insufficient organic matters, slow conversion, high cost, complex process and the like in the traditional treatment of the coal gangue, and an environment-friendly, efficient and low-cost ecological soil preparation method is provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste resource utilization and ecological governance, in particular to a method for processing and converting coal gangue into ecological soil. BACKGROUND

[0002] Coal gangue is a solid waste generated during coal mining and washing. Its large-scale storage not only occupies land, but also poses serious environmental risks such as dust emission, leaching pollution of soil and water, and heavy metal migration. Traditional disposal methods such as landfill and open-air storage are unsustainable and do not meet the requirements of sustainable development. It is urgent to explore resource utilization approaches that are large-scale, high-value, and safe.

[0003] Existing coal gangue conversion ecological soil treatment technologies mostly use methods such as adding acid, alkali, binder, and straw after crushing. These methods have high costs, high risk of heavy metal residue, low conversion efficiency, long operation cycle, and other problems, making it difficult to meet the demand for large-scale ecological restoration. For example, patent CN 118947491 A does not consider the risk of heavy metals in coal gangue and requires more than 30 days of reaction period to complete the conversion of ecological soil, which is too long a degradation time. Patent CN 117243086 A crushes coal gangue and mixes it with sand to obtain improved ecological soil, but does not improve the nutrient content and environmental risk of coal gangue. Therefore, there is an urgent need for a coal gangue conversion ecological soil treatment technology to achieve harmless and resourceful conversion of coal gangue, reduce harmful components, and improve the performance of ecological soil. SUMMARY

[0004] To address the above-mentioned problems, the present application aims to provide a method for processing and converting coal gangue into ecological soil, which solves the problems of heavy metal pollution, insufficient organic matter, slow conversion, high cost, and complex process in traditional coal gangue treatment, and provides an environmentally friendly, efficient, and low-cost ecological soil preparation method.

[0005] To solve the problems of the prior art, the technical solution adopted by the present application is as follows:

[0006] A method for processing and converting coal gangue into ecological soil, comprising the following steps:

[0007] S1 Degradation pretreatment: adding a degradation agent to coal gangue in an aerobic environment at a temperature of 20℃ or higher;

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

[0009] S3 High-temperature activation: calcining and activating at 400-950℃ with a heating rate of 3℃ / min-20℃ / min to achieve gradient temperature programmed decomposition of coal gangue;

[0010] S4 Heavy metal passivation: adding a passivation agent and allowing it to react with metal ions through acid complexation / chelation for 12-72h;

[0011] S5 maturation modification: adding modifier, treating 2-24h, obtaining ecological soil.

[0012] Further, the degradation agent is water rich in ozone and carbon dioxide, the degradation agent is not more than 1:10000 in mass ratio with coal gangue, and the pretreatment time is 0.3-48h.

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

[0014] Further, the passivation agent is a mixture of seaweed sludge and bottom layer of duck farm feces, and the high-temperature catalytic oxygenolysis product, and the passivation agent is added in an amount of 0.03-0.10% of the mass of the coal gangue.

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

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

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

[0018] Further, the red wine lees fermentation product is a fermentation product of one or more of Cabernet Sauvignon, Pinot Noir or Merlot red wine lees

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

[0020] The performance indicators of the obtained ecological soil are: (1) organic phase 5-300g / Kg; pH value 6.0-9.5; Tclp-Cd: (2) in line 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 in line with or better than GB15618 control standard; (5) engineering ecological soil meets "Land for Greening Planting" (CJ / T340); (5) safety assessment in line with "Solid Waste Leaching Toxicity Leaching Method" (HJ / T299-2007); (6) TSi: 0.5-60%; TFe / Al component 0.2-25%; (7) cost lower than conventional 60%.

[0021] Compared with the prior art, the application has the beneficial effects that:

[0022] 1、The processing technology of the application is high-efficiency continuous operation throughout, reduces energy consumption and cost, and the obtained ecological soil product can be used for land improvement, ecological restoration, environmental management and planting application requirements in environmental scenes such as forestry, animal husbandry, agriculture, greening, tidal flat, river and lake bank land, waste mine, coal mining subsidence area, solid waste stacking site, and can also be used for acidification land, saline-alkali land, and environmental pollution land management;

[0023] 2、The application adopts high-temperature activation, which can recombine the mineral structure of coal gangue, greatly improve the activity of mineral elements, and the obtained product is rich in potassium, nitrogen, phosphorus, calcium, iron, magnesium, silicon, aluminum, sulfur and other nutrient elements and appropriate trace elements such as zinc, copper, manganese, boron, molybdenum, nickel and selenium. Beneficial minerals can balance the soil mineral nutrients, improve soil fertility, reduce plant diseases and insect pests, and reduce the use amount of chemical fertilizers, so as to achieve the effect of improving soil quality;

[0024] 3、The application can reduce the content of heavy metals and harmful elements and toxic organic matter in coal gangue through high-temperature activation, reduce agricultural non-point source pollution, inhibit soil acidification and adjust soil PH balance, and reduce soil hardening;

[0025] 4、The application controls the activation temperature to be 400-950 DEG C, which can balance the activation effect and energy efficiency. Too high temperature will reduce the activity of minerals and greatly increase the energy consumption. At the same time, too high temperature will destroy the heavy metal package structure, and part of the heavy metal will increase the risk of dissolution;

[0026] 5、The high-temperature explosion effect of the application can increase the porosity of coal gangue particles and increase the specific surface area, increase the adsorption of nutrient elements in soil, and improve the nutrient absorption efficiency of crops. The high-temperature explosion effect promotes the refinement of particles, improves the air permeability of ecological soil, and improves the soil structure;

[0027] 6、The modifier involved in the application is an amphoteric organic small molecule, which regulates the soil physical and chemical properties;

[0028] 7、The metal passivator involved in the application has the dual effects of acidic complexation and chelation with metal ions, which can further reduce harmful components in coal gangue and long-acting fix heavy metals;

[0029] 8、The degradation agent involved in the application is low-carbon and environmentally friendly, and a small amount (less than 0.01%) can achieve high-efficiency degradation. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0031] The degrading agent involved in the following embodiments 1-4 is water rich in ozone and carbon dioxide, the ozone concentration is 80 mg / L, and the carbon dioxide concentration is 1000 mg / L.

[0032] The passivation agent involved in the following embodiments 1-4 is a mixture of seaweed sludge and duck farm feces bottom layer aging layer mixed high-temperature catalytic oxygenolysis products, the addition ratio of the two is 2:1, and the high-temperature catalytic conditions are 190℃, 0.5MPa O2, and 2h.

[0033] The composition of the modifier involved in the following embodiments 1-4 is: lignin degradation product sulfonate + tea polyphenol-iron complex + cabernet sauvignon red wine lees fermentation product, and the mass ratio of each component is 2:1:1.

[0034] Embodiment 1

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

[0036] 1. Under the condition of ventilation and oxygen environment at 30℃, add the degrading agent to the coal gangue at a mass ratio of 1:50000, and continuously treat for 12h;

[0037] 2. Impact crush the pretreated coal gangue to 300 mesh;

[0038] 3. High-temperature activate the crushed coal gangue, heat up at a rate of less than 400℃ at 5℃ / min, keep warm for 30min, heat up at a rate of 400→700℃ at 12℃ / min, heat up at a rate of 700→850℃ at 18℃ / min, and keep warm for 50min;

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

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

[0041] 6. Moisture-proof package of finished powder.

[0042] The performance data of the obtained ecological soil are as follows:

[0043] Organic phase 210 g / kg, pH 7.3, Tclp-Cd 0.2 mg / L (GB 5085.3 limit 1.0 mg / L);

[0044] TN 2.8 g / kg, TP 380 mg / kg, TK 480 mg / kg (satisfy the demand of solanaceous crops);

[0045] EC value 1.2 mS / cm, other heavy metals are lower than 50% of GB 15618 limit.

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

[0047] Example 2:

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

[0049] 1. In a ventilated aerobic environment at 25 DEG C, 1:60,000 degrading agent is added to the coal gangue, and continuous treatment is performed for 12 hours.

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

[0051] 3. The broken coal gangue is high-temperature activated, the temperature is raised at a speed of 3 DEG C / min below 400 DEG C, the temperature is kept for 30 min, the temperature is raised at a speed of 15 DEG C / min from 400 DEG C to 600 DEG C, the temperature is raised at a speed of 18 DEG C / min from 600 DEG C to 800 DEG C, and the temperature is kept for 50 min.

[0052] 4. 0.04% heavy metal passivator is added to the activated coal gangue, and reaction is performed for 48 hours.

[0053] 5. 0.08% modifier is added to the coal gangue obtained in the step 4, and maturation modification treatment is performed for 6 hours.

[0054] 6. The finished product powder is packaged.

[0055] The obtained ecological soil performance data are as follows:

[0056] EC value 0.9 mS / cm (GB 15618 limit <1.5 mS / cm), pH 8.1, organic phase 120 g / kg;

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

[0058] Tclp-Cd 0.08mg / L (GB5085.3 limit value 1.0mg / L), cost 70 yuan / ton (marketed saline-alkali ameliorant 350 yuan / ton).

[0059] Example 3:

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

[0061] 1. Under the condition of ventilation and oxygenation at 30 DEG C, 1:100000 of degradation agent is added to the coal gangue, and the coal gangue is continuously treated for 2h.

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

[0063] 3. The broken coal gangue is high-temperature activated, the temperature is raised at a speed of 5 DEG C / min below 400 DEG C, the temperature is raised at a speed of 12 DEG C / min from 400 DEG C to 650 DEG C, the temperature is raised at a speed of 20 DEG C / min from 650 DEG C to 850 DEG C, and the temperature is kept for 40 min.

[0064] 4. 0.03% heavy metal passivator is added to the activated coal gangue, and the reaction is kept for 36h.

[0065] 5. 0.1% modifier is added to the coal gangue obtained in the step 4, and the modification treatment is kept for 8h.

[0066] 6. The finished product powder is packaged in a moisture-proof manner.

[0067] Performance data of the obtained ecological soil:

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

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

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

[0071] Example 4: The embodiment discloses application of a method for processing and converting coal gangue into ecological soil in the field of preparation of soil for repairing heavy metal pollution sites, raw material: coal gangue containing Cr / Ni (Cr: 85mg / kg, Ni: 120mg / kg), and specific processing modes are as follows:

[0072] 1. Adding degrading agent to coal gangue with mass ratio of 1:10000 under 40℃ ventilated oxygen environment, continuously treating for 24h;

[0073] 2. Impact breaking the pretreated coal gangue to 800 mesh;

[0074] 3. High temperature activation of the broken coal gangue, heating up at 6℃ / min below 450℃, keeping temperature for 40min; heating up at 10℃ / min from 450 to 800℃, keeping temperature for 60min;

[0075] 4. Adding 0.08% heavy metal passivator to the activated coal gangue, reacting for 60h;

[0076] 5. Adding 0.25% modifier to the coal gangue obtained in step 4, aging for 12h;

[0077] 6. Moisture-proof packaging of the finished powder.

[0078] The performance data of the obtained ecological soil:

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

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

[0081] Bioavailable Cr reduced by 92%;

[0082] Cost 135yuan / ton (professional repair material 800yuan / ton).

[0083] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies thereof, the present application also intends to include these modifications and variations.

Claims

1. A method for processing coal gangue into ecological soil, characterized in that, The method comprises the following steps: S1 degradation pretreatment: adding a degradation agent to the coal gangue in an aerobic environment at a temperature of ≥20℃; S2 crushing and screening: crushing the pretreated coal gangue to a target particle size; S3 high-temperature activation: calcining and activating at 400-950℃, with a heating rate of 3℃ / min-20℃ / min; S4 heavy metal passivation: adding a passivation agent and reacting for 12-72h; S5 maturation and modification: adding a modifier and treating for 2-24h to obtain the ecological soil.

2. The method for processing and converting coal gangue into ecological soil according to claim 1, characterized in that, The degradation agent is water rich in ozone and carbon dioxide, and the mass ratio of the degradation agent to the coal gangue is not greater than 1:10000, and the pretreatment time is 0.3-48h.

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

4. The method for processing and converting coal gangue into ecological soil according to claim 1, characterized in that, The passivation agent is a high-temperature catalytic oxygenolysis product of a mixture of seaweed sludge and duck farm feces bottom layer aging layer, and the addition amount of the passivation agent is 0.03-0.10% of the mass of the coal gangue.

5. The method of processing coal gangue into ecological soil according to claim 4, characterized in that, The addition ratio of the seaweed sludge to the duck farm feces bottom layer aging layer is 6-7:3-4, and the high-temperature catalytic conditions are 180-220℃, 0.5MPa O2, and 1-3h.

6. The method for processing and converting coal gangue into ecological soil according to claim 1, characterized in that, The modifier is an amphoteric organic small molecule containing an amine group, a hydroxyl group, a carboxyl group, a quinone group, and a short side chain small carbon ring, and the addition amount of the modifier is 0.05-0.30% of the mass of the coal gangue.

7. The method of processing coal gangue into ecological soil according to claim 6, characterized in that, The modifier composition comprises lignin degradation product sulfonate, tea polyphenol-iron complex, and red wine lees fermentation product, and the mass ratio of each component is 4-6:2-3:2-3.

8. The method of processing coal gangue into ecological soil according to claim 7, characterized in that, The red wine lees fermentation product is a fermentation product of one or more red wine lees of Cabernet Sauvignon, Pinot Noir, or Merlot.

9. The method for processing and converting coal gangue into ecological soil according to claim 1, characterized in that, In the step S2, the target particle size is 60-1000 mesh, and preferably, the target particle size is 80-200 mesh.

10. The method for processing and converting coal gangue into ecological soil according to claim 1, characterized in that, In the ecological soil, the organic phase is 5-300g / Kg, TN is 0.2-3.0g / Kg, TP is 5-400mg / Kg, TK is 5-500mg / Kg, and the pH value is 6.0-9.5.