Coal-based improved artificial soil and preparation method and use thereof

Abstract

The present application relates to a kind of coal-based improved artificial soil and its preparation method and purposes.It includes improved coal gangue and seedling filling material, and the weight of improved coal gangue is 75% to 85%, humic acid is activated by acid-base method treatment, and acid-base method treatment includes: humic acid salt is obtained by alkaline solution treatment, and improved coal gangue is obtained by acid solution treatment;Seedling filling material includes 0.1% to 0.5% of gamma-polyglutamic acid, 4% to 5% of microbial combination and 10% to 20% of soil filling material;Microbial combination includes arbuscular mycorrhizal fungi, Trichoderma harzianum and bacillus mucilaginosus;Soil filling material includes grass charcoal, vermiculite and perlite.

Description

Technical Field

[0001] This invention relates to artificial soil, specifically to a technology for forming artificial soil using coal gangue. Background Technology

[0002] Coal gangue is a solid waste generated during coal mining and washing, containing abundant minerals and organic matter. However, due to its loose structure and unstable content of components such as pH and heavy metals, direct utilization can harm the environment. Currently, methods for improving soil using coal gangue mainly focus on simple physical and chemical modifications, which suffer from low processing efficiency and environmental pollution, failing to fully realize the potential value of coal gangue.

[0003] While some existing technologies have attempted to improve coal gangue soil by adding organic matter or chemical amendments, the results have been less than satisfactory. Therefore, developing a highly efficient and environmentally friendly coal-based soil amendment that can be applied to coal-based artificial soils to effectively utilize coal gangue resources, improve soil structure, and enhance soil fertility is of significant practical importance and promising application prospects. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the problem of insufficient utilization of coal gangue in the prior art, thereby providing a technology for improving coal gangue and applying it to artificial soil.

[0005] To achieve the above objectives, the present invention provides a coal-based improved artificial soil, comprising coal gangue and seedling filler; The modified coal gangue has a weight of 75% to 85%, and the humic acid is activated by acid-base treatment. The acid-base treatment includes: alkaline solution treatment to obtain humate salt, and acidic solution treatment to obtain modified coal gangue. The seedling filling material includes 0.1% to 0.5% γ-polyglutamic acid, 4% to 5% microbial composition, and 10% to 20% soil filler; the microbial composition includes arbuscular mycorrhizal fungi, Trichoderma harzianum, and Bacillus mucilaginosus; the soil filler includes peat moss, vermiculite, and perlite.

[0006] Preferably, peat moss, vermiculite, and perlite are mixed in a 3:1:1 ratio as soil filler.

[0007] Preferably, the composition is 80% coal gangue, 0.24% γ-polyglutamic acid, 0.17% Trichoderma harzianum, 3% arbuscular mycorrhizal fungi, 1% Bacillus mucilaginosus, 3.118% vermiculite, 3.118% perlite, and 9.354% peat moss.

[0008] Preferably, the acidic electrolyzed water is prepared using a proton exchange membrane electrolyzer, employing a titanium-based ruthenium-iridium coated anode and a platinum / titanium cathode. The 0.5–1.0 mol / L H₂SO₄ solution is electrolyzed under controlled conditions of 1.8–2.5 V voltage, 50–120 mA / cm² current density, and 30–45 °C. The cathode region produces a product containing a high concentration of H₂. + Acidic electrolysis of water containing reactive oxygen species; Preferably, the amount of alkaline electrolyzed water added is 10%~20% (v / w) of the dry basis mass of coal gangue, and the alkaline electrolyzed water is prepared by the following steps: (1) Electrolyte preparation: KOH or NaOH solution with a concentration of 0.8~1.2 mol / L is used as electrolyte; (2) Electrolysis parameters: 2.2~2.8 V DC voltage is applied, and the current density is controlled at 10~50 mA / cm²; (3) Electrode selection: Nickel-based electrodes are used as cathode and anode; (4) Membrane setting: Alkali-resistant anion exchange membrane is used to separate the anode and cathode regions to ensure that the pH of the cathode region is stable at 13~14. Preferably, the acidic electrolyzed water has a pH of 1 and a H+ of 1. + The concentration is 1.0~1.2 mol / L, the reactive oxygen species ORP≥1000 mV, and the nickel-based electrode is nickel foam or nickel mesh.

[0009] The present invention provides a method for preparing coal-based modified artificial soil, comprising: Pretreatment: The coal gangue is dried and ground, sieved to remove large impurities, and crushed to a particle size of less than 6mm; Humic acid extraction: First, coal gangue is dissolved using acidic and alkaline solutions to extract humic acid; Activation: Add γ-polyglutamic acid (γ-PGA), Trichoderma harzianum, arbuscular mycorrhizal fungi and Bacillus mucilaginosus to the treated coal gangue; Seedling filling material mixing: Mix peat moss, vermiculite and perlite in a ratio of 3:1:1 as seedling filling material; Final mixing: The improved coal gangue treated above is mixed evenly with the seedling filler and then applied to artificial soil.

[0010] The present invention provides a method for preparing coal-based modified artificial soil. Improved coal gangue processing steps: Acid leaching: Acid leaching is performed using acidic electrolyzed water with pH=1. The mixture is heated and stirred in a boiling water bath for 1.5 hours, then allowed to stand at room temperature before filtration and washing until neutral. Alkaline extraction: Alkaline electrolyzed water with pH=14 is added at a liquid-to-solid ratio of 3:1. The mixture is heated and stirred in a boiling water bath for 2 hours. After the reaction is complete, the mixture is cooled and filtered. Filtrate treatment: Acidification is performed using acidic electrolyzed water with pH=1, added in portions until the pH of the system stabilizes at 1-2. After standing for 45 minutes, the mixture is filtered. The filter cake is washed with deionized water and dried in an oven at 80℃ to obtain improved coal gangue.

[0011] The present invention provides a method for preparing coal-based modified artificial soil. Stable single particles of modified coal gangue aggregate with each other through humic acid, microorganisms, metabolites and liquid film binders to form compound particles or agglomerates; subsequently, these compound particles further agglomerate, gradually forming micro-agglomerates, which then undergo multiple agglomerations to eventually form larger agglomerate structures.

[0012] The coal-based modified artificial soil provided by this invention is used for the growth of drought- and salt-tolerant plants.

[0013] The coal-based improved artificial soil provided by this invention is used for the growth of drought- and salt-tolerant plants, which include alfalfa, ryegrass, sweet clover, purslane or alkali grass.

[0014] The beneficial effects of this invention are as follows: This technology adopts the methods of "using waste to treat waste", "rational utilization of resources", "adjusting the properties of soil solution" and "microorganisms combined with plants", which work together with the organic matter, minerals, iron and aluminum oxides and other components of coal gangue to optimize the structure of coal gangue artificial soil, create soil suitable for plant growth, effectively improve the properties of coal gangue, improve nutrient supply and water retention capacity, and provide an excellent growth environment for plants.

[0015] Coal gangue typically exhibits high acidity and poor soil characteristics, which are detrimental to plant growth. To improve these properties, this technology couples coal gangue with other materials to adjust the structure and chemical properties of the gangue soil. This neutralizes soil acidity, increases soil pH, improves the absorption capacity of plant roots, and promotes nutrient release and supply.

[0016] Meanwhile, by adjusting the concentration of electrolytes, solute types, and pH value in the soil solution, the properties of the soil solution are improved, and the characteristics of coal gangue itself are enhanced to construct a stable soil aggregate structure, providing a good living environment for plants and microorganisms.

[0017] The environmental advantages of this invention's water electrolysis treatment include: zero chemical additives: water is electrolyzed to generate H+ in situ through the electrolysis of NaCl or KOH solution. + / OH -No external strong acids or bases are required, reducing the use of hazardous chemicals; closed-loop circulation: waste liquid can be regenerated and reused through an electrolytic cell, reducing wastewater treatment costs (in contrast: ordinary acid-base methods produce high-salt wastewater that requires neutralization treatment). Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a specific embodiment of the improved artificial soil of the present invention; Figure 2 This is the chemical structure diagram of γ-PGA, the substance used in this invention; Figure 3 This is a diagram illustrating the process of applying coal gangue artificial soil to plants according to the present invention. Figure 4 This is a comparison chart of pollution risk control indicators for the application of the coal gangue artificial soil of the present invention; Figure 5 This is a schematic diagram illustrating the principle of coal gangue soil aggregate structure according to the present invention; wherein, a. gangue aggregate structure; b. internal composition structure of aggregates; c. types of structures; d. coal gangue artificial soil; Figure 6 This is a schematic diagram illustrating the composition principle of the artificial soil formed from coal gangue according to the present invention; Figure 7 This is a flowchart of the preparation method of coal-based artificial soil and the selection of suitable plants according to the present invention. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0021] This invention provides a coal-based improved artificial soil, which includes coal gangue and seedling filler; Improved coal gangue, with a weight of 75% to 85%, is activated by acid-base treatment to obtain humic acid. The acid-base treatment includes: alkaline solution treatment to obtain humate salts, and acidic solution treatment to obtain improved coal gangue. The seedling filling material includes 0.1% to 0.5% γ-polyglutamic acid, 4% to 5% microbial composition, and 10% to 20% soil filler; the microbial composition includes arbuscular mycorrhizal fungi, Trichoderma harzianum, and Bacillus mucilaginosus; the soil filler includes peat moss, vermiculite, and perlite.

[0022] Preferably, peat moss, vermiculite, and perlite are mixed in a 3:1:1 ratio as soil filler.

[0023] The present invention provides a method for preparing coal-based modified artificial soil, comprising: Pretreatment: The coal gangue is dried and ground, sieved to remove large impurities, and crushed to a particle size of less than 6mm; Humic acid extraction: First, coal gangue is dissolved using acidic and alkaline solutions to extract humic acid; Activation: Add γ-polyglutamic acid (γ-PGA), Trichoderma harzianum, arbuscular mycorrhizal fungi and Bacillus mucilaginosus to the treated coal gangue; Seedling filling material mixing: Mix peat moss, vermiculite and perlite in a ratio of 3:1:1 as seedling filling material; Final mixing: The improved coal gangue treated above is mixed evenly with the seedling filler and then applied to artificial soil.

[0024] Example 1: The formulation in this embodiment comprises eight components: modified coal gangue, γ-polyglutamic acid, a microbial blend (Trichoderma harzianum, arbuscular mycorrhizal fungi, and Bacillus mucilaginosus), vermiculite, perlite, peat moss, and drought- and salt-tolerant plants (such as alfalfa, ryegrass, sweet clover, purslane, and alkali grass). In a preferred embodiment, the weight ratio of modified coal gangue to filler (γ-polyglutamic acid, microbial blend, vermiculite, perlite, and peat moss) is 8:2, i.e., modified coal gangue accounts for 80%, and filler accounts for 20%. The specific proportions of each component of the filler are as follows: γ-polyglutamic acid 0.24%, Trichoderma harzianum 0.17%, arbuscular mycorrhizal fungi 3%, Bacillus mucilaginosus 1%, vermiculite 3.118%, perlite 3.118%, and peat moss 9.354%. Figure 1 The proportions shown.

[0025] Improved coal gangue is coal gangue that has undergone acid and alkaline water treatment. The specific treatment process is as follows: This invention employs a method for activating humic acid in coal gangue using water electrolysis. The activation of humic acid in low-rank coal gangue is achieved by using the products from the electrolysis of the anode and cathode (i.e., acid-base solution). The entire activation process includes pretreatment, dissolution reaction, and acid precipitation separation. A more detailed process is as follows: The general route for activating humic acid from coal gangue is as follows: coal drying → grinding and sieving → acidic water impurity removal → filtration and washing → alkaline water activation → filtration → filtrate acidification → settling and stratification → filtration and washing → filter cake drying → product.

[0026] The final product obtained is modified coal gangue, which contains extracted humic acid and some isolated trace elements. Table 1 below shows the nutritional composition analysis.

[0027] Specific implementation methods for improving coal gangue preparation: Step 1: Dry the coal gangue, grind it, and pass it through a 30-mesh sieve; Step 2: Weigh a certain mass, add acidic electrolyzed water with pH=1, heat and stir in a boiling water bath for 1.5 hours, let stand to room temperature, and then filter and wash until neutral. Step 3: After adding distilled water, add alkaline electrolyzed water with pH=14. It is preferable to add electrolyzed water at a liquid-to-solid ratio of 1:3. Heat and stir in a boiling water bath for 2 hours. After the reaction is complete, cool and filter. Step 4: Acidification is carried out using acidic electrolyzed water with pH=1. The solution is added in portions until the pH of the system stabilizes at 1-2. After standing for 45 minutes, the mixture is filtered. The filter cake is washed with deionized water and then dried in an oven at 80℃ to obtain modified coal gangue. The modified coal gangue product is mainly composed of humic acid and contains other components that can be separated together with humic acid.

[0028] Research results: Free humic acid accounted for 45.03%, and total humic acid accounted for 49.24%.

[0029] 1. Determination of free humic acid (45.03%): According to Method III of GB / T 11957-2001 "Determination of Humic Acid Yield in Coal"; The experimental procedure is as follows: Alkali extraction: Take 1.0 g of dry coal sample (80 mesh), add 100 mL of 1% NaOH solution, and shake in a water bath at 90℃ for 2 hours; Centrifugation: Centrifuge at 4000 r / min for 15 minutes (retain the supernatant); Acidification precipitation: Adjust the pH to 1.5-2.0 (using 6 mol / L HCl), and let stand for 12 hours; Gravimetric determination: After filtration, dry at 80℃ to constant weight, and calculate: Free humic acid (%) = (precipitate mass / coal sample mass) × 100 × correction coefficient (0.92).

[0030] 2. Determination of Total Humic Acid (49.24%): Standard: Refer to ISO 5073:2013 "Determination of Humic Acid in Lignite"; Key Steps: Sodium Pyrophosphate Extraction: Use a mixture of 0.1 mol / L sodium pyrophosphate and 0.1 mol / L NaOH (volume ratio 1:1), reflux at 95℃ for 4 hours; Secondary Extraction: Repeat extraction of the residue twice (cumulative extraction efficiency > 98%); Ultraviolet Spectroscopy: Dilute the combined extract to a suitable concentration and measure the absorbance at 465 nm (standard curve method, R² > 0.999); Calculation Formula: Total Humic Acid (%) = (C × V × D) / (m × 10⁻⁶) 6 ) × 100; (C: standard curve concentration, V: volume, D: dilution factor, m: sample mass).

[0031] This invention utilizes γ-polyglutamic acid (γ-PGA), which is polymerized from L- and D-type glutamic acid monomers via amide bonds between α-amino and γ-carboxyl groups (polymerized from 500-5000 glutamic acid monomers). It possesses excellent water solubility, water absorption, water retention, biodegradability, heavy metal ion adsorption, and ability to promote aggregate structure. Furthermore, γ-PGA can absorb up to 1108.4 times its weight in water under natural conditions, more than twice that of polyacrylate superabsorbent resins. γ-PGA's absorption capacity for soil moisture ranges from 30 to 80 times, exhibiting significant drought resistance, seedling promotion, and slow-release effects. The chemical structure is as follows: Figure 2 As shown.

[0032] Explanation of the principle: Coal-based solid waste often contains a large amount of organic matter, among which humic acid is an important organic matter with broad application prospects. Traditional humic acid extraction methods often use strong acids and strong alkalis, which cause serious environmental pollution. Therefore, developing an environmentally friendly extraction method is particularly important.

[0033] 1. Extraction Principle Humic acid is poorly soluble in acids but readily soluble in alkalis. Its extraction mainly relies on the following chemical reactions: ( R-(COOH)_n + OH - → R-(COOK)_n + nH2O ) ( R-(COOK)_n + H + → R-(COOH)_n + K + ) Considering that low-rank coal often contains a large amount of calcium, magnesium, iron and other ions, these metal ions are easy to form complexes with humic acid, thus affecting the extraction effect. This technology uses acidic water to treat the coal first to remove some of the calcium, magnesium and iron ions, and then performs alkaline extraction and acid precipitation to extract humic acid.

[0034] 2. Optimized steps Pretreatment: Low-rank coal (such as weathered coal and lignite) is pretreated with acidic water containing hypochlorite or chloride ions to remove metal ions such as calcium, magnesium, and iron from the coal and reduce their complexation with humic acid.

[0035] Alkaline dissolution: Humic acid is dissolved using alkaline water containing hydroxide ions. The carboxyl groups (-COOH) and phenolic hydroxyl groups (-OH) in humic acid react with alkaline substances (such as KOH, NaOH, Na2CO3, Na4P2O7, ammonia, etc.) to form soluble humate salts.

[0036] Acid precipitation: Finally, acidic water is used to adjust the pH to <2 to perform solid-liquid separation, thereby purifying and separating humic acid.

[0037] 3. Acid and alkaline water properties The properties of acidic and alkaline solutions are as follows: alkaline water contains hydroxide ions and potassium ions required by plants; acidic water contains acidic hydrogen ions and hypochlorite ions. Experiments show that acidic water tends to become neutral over time after use. Therefore, it is feasible to use acidic and alkaline solutions to replace sodium hydroxide and hydrochloric acid for the activation of humic acid in low-rank coal.

[0038] More specifically, the electrochemical characteristics of water electrolysis and the humic acid activation mechanism of the present invention are as follows: Acidic electrolyzed water: Acidic water (pH=1) produced by a proton exchange membrane electrolyzer is rich in H+. + ,ClO - The hydroxyl radical (·OH) has a high ORP (≥1000 mV) that can oxidize and decompose the encapsulated structure of silicate minerals in coal gangue, releasing the bound humic acid; at the same time, ·OH reacts with the aromatic ring in the humic acid macromolecule to generate small molecule humic acid fragments, thereby improving its bioavailability.

[0039] Alkaline electrolysis of water: The high pH environment (pH=13~14) in the cathode area promotes the reaction of humic acid and potassium. + / Na + This process combines to form water-soluble humates, avoiding the problems caused by Ca in traditional alkaline treatments. 2+ / Mg 2+ Precipitation leads to humic acid loss; in addition, nanobubbles (particle size <100 nm) in electrolyzed water can penetrate into the micropores of coal gangue, enhancing mass transfer efficiency.

[0040] 4. Extraction route and method Extraction route: Weathered coal drying → grinding and sieving → acid removal → filtration and washing → alkaline activation → filtration → filtrate acidification → settling and stratification → filtration and washing → filter cake drying → product.

[0041] Specific methods: (1) Dry the coal gangue, grind it, and pass it through a 30-mesh sieve; (2) Weigh a certain mass, add acidic water with pH=1, heat and stir in a boiling water bath for 1 hour, let stand to room temperature, and then filter and wash until neutral. (3) After adding distilled water, add alkaline electrolyzed water with pH=14, add electrolyzed water at a liquid-to-solid ratio of 1:3, heat and stir in a boiling water bath for 2 hours, and cool and filter after the reaction is complete. (4) Acidic electrolyzed water with pH=1 is used for acidification. The solution is added in portions until the pH of the system stabilizes at 1-2. After standing for 45 minutes, the solution is filtered. The filter cake is washed with deionized water and then dried in an oven at 80°C to obtain modified coal gangue. The modified coal gangue product is mainly composed of humic acid and contains other components that can be separated from humic acid.

[0042] 5. Effect of alkali dosage Taking NaOH as an example, the experiment was conducted as follows: Under a solid-liquid ratio of 1:3, 50g of weathered coal was taken and NaOH was added at proportions of 0.4 mol / L, 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, and 1.4 mol / L, respectively. The mixture was stirred in a water bath at 25℃ for 1 hour, and the extraction rate of humic acid was measured. The experimental results showed that the extraction rate of humic acid gradually increased with the increase of NaOH dosage, but the increase decreased when the NaOH dosage reached 0.8 mol / L - 1.0 mol / L. For industrial production, the optimal NaOH dosage is 0.8 mol / L - 1.0 mol / L, i.e., alkaline water with a pH of 13.9-14; that is, the pH of the alkaline electrolyzed water used in this application is equivalent to the dosage of 0.8 mol / L - 1.0 mol / L NaOH.

[0043] Preferably, the acidic electrolyzed water is prepared using a proton exchange membrane electrolyzer, employing a titanium-based ruthenium-iridium coated anode and a platinum / titanium cathode. The 0.5–1.0 mol / L H₂SO₄ solution is electrolyzed under controlled conditions of 1.8–2.5 V voltage, 50–120 mA / cm² current density, and 30–45 °C. The cathode region produces a product containing a high concentration of H₂. + Acidic electrolysis of water containing reactive oxygen species; Preferably, the amount of alkaline electrolyzed water added is 10%~20% (v / w) of the dry basis mass of coal gangue, and the alkaline electrolyzed water is prepared by the following steps: (1) Electrolyte preparation: KOH or NaOH solution with a concentration of 0.8~1.2 mol / L is used as electrolyte; (2) Electrolysis parameters: 2.2~2.8 V DC voltage is applied, and the current density is controlled at 10~50 mA / cm²; (3) Electrode selection: Nickel-based electrodes are used as cathode and anode; (4) Membrane setting: Alkali-resistant anion exchange membrane is used to separate the anode and cathode regions to ensure that the pH of the cathode region is stable at 13~14. Preferably, the acidic electrolyzed water has a pH of 1 and a H+ of 1. + The concentration is 1.0~1.2 mol / L, the reactive oxygen species ORP≥1000 mV, and the nickel-based electrode is nickel foam or nickel mesh.

[0044] To further illustrate the difference between the electrolytic acid-base solution of the present invention and ordinary acid-base solutions, the following comparative examples are provided.

[0045] Comparative Example 1: Comparison of humic acid extraction efficiency between electrolytic acid-base solutions and ordinary acid-base solutions: Experimental design: Identical weathered coal samples (free humic acid content 45.03%) were divided into three groups: Experimental group: The above-mentioned electrolyzed acidic water (pH=1, ORP≥1000 mV) and alkaline electrolyzed water (pH=14) were used. Control group 1: ordinary hydrochloric acid (HCl, pH=1) and sodium hydroxide solution (NaOH, pH=14). Control group 2: conventional acid (sulfuric acid, pH=1) and base (KOH, pH=14).

[0046] Processing conditions: liquid-to-solid ratio 3:1, boiling water bath heating for 2 hours, filtration followed by detection of humic acid extraction rate.

[0047] Experimental results:

[0048] Conclusion: The humic acid extraction efficiency of electrolytic acid-base water is significantly higher than that of ordinary acid-base water (by about 14%), and no additional chemical reagents are required, while the reaction time is shortened by more than 30%.

[0049] Comparative Example 2: The synergistic effect of electrolyzed water on microbial activity in this invention: Experimental design: Trichoderma harzianum (0.17%) and Bacillus mucilaginosus (1%) were inoculated into the following two groups respectively: Group A: Modified coal gangue treated by electrolysis; Group B: Coal gangue treated with ordinary acid and alkali.

[0050] Detection indicators: microbial metabolic activity (ATP content) and phosphorus solubility after 7 days.

[0051] The results are shown in the table below:

[0052] Mechanism explanation: Trace amounts of reactive oxygen species (such as H2O2) remaining in electrolyzed water can stimulate microorganisms to produce stress kinases (such as SOD and catalase), thereby enhancing their metabolic activity; simultaneously, the potassium in electrolyzed water... + / Na + Ions (from alkaline electrolyzed water) form chelates with humic acid, promoting the fixation and release of phosphorus and potassium by microorganisms. Therefore, after treating coal gangue with this type of electrolyzed water, the activity of microorganisms inoculated with it is correspondingly enhanced, which is beneficial to plant growth.

[0053] The environmental advantages of this invention's water electrolysis treatment include: zero chemical additives: water is electrolyzed to generate H+ in situ through the electrolysis of NaCl or KOH solution. + / OH - No external strong acids or bases are required, reducing the use of hazardous chemicals; closed-loop circulation: waste liquid can be regenerated and reused through an electrolytic cell, reducing wastewater treatment costs (in contrast: ordinary acid-base methods produce high-salt wastewater that requires neutralization treatment).

[0054] 6. Research Results Taking weathered coal as an example, the content of free humic acid is 45.03%, and the content of total humic acid is 49.24%.

[0055] Selection and application of microorganisms in this invention: This technology utilizes a combination of arbuscular mycorrhizal fungi, Trichoderma harzianum, and Bacillus mucilaginosus to synergistically activate gangue in the preparation of artificial soil. 1. Arbuscular mycorrhizal fungi (AMF): They can significantly increase the content of available nutrients in the soil, improve substrate fertility, and promote plant growth. In the reclamation of abandoned mining areas, AMF coexists with 90% of higher plants, improving the underground ecosystem and enhancing its productivity and diversity.

[0056] 2. Trichoderma harzianum: Highly adaptable and harmless to humans, animals, and plants, it obtains mineral nutrients through its mycelium, increasing the phosphorus and potassium content in the soil and supporting plant growth. Simultaneously, it enhances plant biomass, root function, and soil enzyme activity, achieving significant results in the control of soil-borne plant diseases.

[0057] 3. Bacillus mucilaginosus: It can dissolve phosphorus, potassium, and fix nitrogen, increase the content of available nutrients in the soil, and significantly promote plant growth, especially in the reclamation of abandoned mining areas.

[0058] Studies have shown that the combined use of these three microorganisms can significantly promote plant growth and ecological reclamation, thereby improving the efficiency and economic benefits of land reclamation in mining areas.

[0059] 4. Selection of seedling substrate: This invention selects peat moss, vermiculite, and perlite mixed in a 3:1:1 ratio as a seedling substrate. This substrate has good aeration, drainage, and water retention properties, is rich in nutrients required by plants, is disease-free, easy to transport and manage, and contains no pathogens or weed seeds. Furthermore, it is an ideal choice for promoting healthy and rapid plant growth in modern agriculture and horticulture.

[0060] 5. Plant selection: To improve efficiency and economic benefits, this technology selected drought- and salt-tolerant plants, such as alfalfa, ryegrass, sweet clover, purslane, and alkali grass, which have shown good drought and salt tolerance in numerous studies.

[0061] Experimental example of basic nutrient composition detection of the improved coal gangue prepared by this invention: Improved coal gangue (powder): moisture content 7.51%, pH 7.63, organic matter 2.53%, available nitrogen 0.53 mg / kg, available phosphorus 117.44 mg / kg, available potassium 172.22 mg / kg, the remainder being inorganic matter.

[0062] The inorganic composition (on a dry basis) of the improved coal gangue (powder) is as follows: 1. Silicon aluminum oxide (60-75%): SiO2: 45-55% (mainly derived from silicate minerals such as quartz and feldspar); Al2O3: 15-25% (existing in the form of clay minerals such as kaolinite, illite, and chlorite); Typical XRD characteristic peaks: quartz (2θ=26.6°), kaolinite (2θ=12.3°); 2. Iron-based compounds (8-15%): Fe2O3: 6-12% (in hematite and goethite forms); FeS2: 0.5-2% (residual pyrite, the content of which is significantly reduced after oxidation treatment); 3. Calcium and magnesium compounds (5-10%): CaO: 3-6% (calcite, gypsum form); MgO: 1-3% (dolomite, magnesite form); Acid neutralization capacity (ANC): ≥2.5 mol H₂ + / kg; 4. Other metal oxides (2-5%): TiO2: 0.5-1.5% (anatase, rutile form); K2O+Na2O: 1-2% (potassium feldspar and sodium feldspar residues); 5. Typical heavy metal content complies with GB 15618-2018 standard:

[0063] Note: After acid-base adjustment, the content of carbonate minerals (such as calcite) was reduced to <3%, the sulfide oxidation rate was >85%, and the cation exchange capacity (CEC) was increased to 15-20 cmol(+) / kg. The specific surface area, determined by BET, was 25-35 m² / g, and the porosity remained in the range of 35-40%.

[0064] Filler (peat moss:vermiculite:perlite = 3:1:1): organic matter 40.8%, total nutrients (N+P+K) 4.2%, total P: 1.26%, total K: 0.78%, pH 6.81, moisture 38.2%, the remainder is inorganic matter.

[0065] The relevant technical indicators of the artificial soil of the present invention obtained after processing are shown in Table 1 below: Table 1. Technical Indicators of Nutrient Components in Coal Gangue Artificial Soil

[0066] Soil electrical conductivity EC in the table: characterizes the amount of soluble salt ions (Na+) in the soil solution. + K + Ca 2+ Mg 2+ Cl - SO4 2- The total concentration (etc.) is usually expressed in dS / m (decimens per meter) or mS / cm (millisiemens per centimeter), where 1 dS / m = 1 mS / cm.

[0067] As an application case in plant cultivation: Coal-based artificial soil was applied to alfalfa cultivation in greenhouses. Compared with loess, the plants grew healthier, with significantly increased plant height and biomass. The soil pollution risk indicators were all better than the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB 15618-2018). The specific growth conditions are shown in Tables 2 and 3 below.

[0068] Experimental groups: coal-based artificial soils 1, 2, and 3, with 50 plants in each group, and other conditions remained unchanged.

[0069] Control group: Alfalfa was grown indoors in pure mineral soil, with 50 plants planted, and other conditions remained unchanged.

[0070] Twenty days later, the plant height, biomass, and heavy metal content of alfalfa were recorded, as detailed in Tables 2 and 3.

[0071] Table 2. Statistics on Plant Growth

[0072] Table 3. Statistical Table of Heavy Metal Variations in Aboveground Parts (Dry Weight)

[0073] Table 2 shows that alfalfa planted with coal-based artificial soil had higher plant height and biomass than the blank control group. Furthermore, observations of the growth process revealed that alfalfa planted with coal-based artificial soil had bright green leaves, maintained soil moisture for a longer period, did not compact, and had good aeration, effectively promoting the growth of alfalfa.

[0074] In addition, a comparative analysis of heavy metal content in the aboveground dry weight of alfalfa planted in coal-based artificial soil and loess soil was conducted. The difference between the two results was less than 2% (Table 3), indicating that the effect of coal-based artificial soil was consistent with that of ordinary soil. After multiple rounds of planting, it still maintained a certain fertilizer effect, and the alfalfa growth in coal-based artificial soil was still better than that in ordinary soil. Furthermore, a comparison of the pollution risk indicators in coal-based artificial soil with the risk control values ​​of pollutants in the "Soil Environmental Quality Standard for Agricultural Land Soil Pollution Risk Control (Trial)" (GB 15618-2018) revealed that all indicators were better than the control standard values. (See details...) Figure 4 As shown. From Figure 4 As can be seen, the concentrations of arsenic, copper, zinc, lead, nickel, and chromium are all significantly lower than those in the standard group, indicating that the pollutants have been effectively controlled.

[0075] Preferably, this invention requires testing the composition of coal gangue, including information on its mineral composition, chemical composition, and physicochemical properties. Analysis of this information can provide fundamental data support for the direction, functional design, technical scheme planning, plant selection, and microbial configuration of coal-based artificial soils and soil improvement. The main testing items are as follows: a) Organic matter content: The organic matter content in gangue, and its contribution to soil fertility; b) pH value: Determine the acidity or alkalinity of coal gangue to provide a basis for soil conditioning and improvement; c) Content of trace elements such as potassium, calcium, magnesium, iron, and manganese: Analyze the content of trace elements in coal gangue to understand its nutrient supply. d) Nitrogen, phosphorus, and potassium content: This involves determining the content of major nutrient elements in coal gangue to provide a reference for plant selection and nutrient management.

[0076] Principles of Coal Gangue Artificial Soil Technology: This technology employs methods such as "waste-to-waste treatment," "rational resource utilization," "adjustment of soil solution properties," and "microbial-plant synergy" to optimize the structure of coal gangue-based artificial soil by leveraging its organic matter, minerals, and iron and aluminum oxides. This creates soil suitable for plant growth, effectively improving the properties of coal gangue, enhancing nutrient supply and water retention, and providing an excellent growing environment for plants (see details). Figure 3 ).

[0077] Coal gangue typically exhibits high acidity and poor soil characteristics, which are detrimental to plant growth. To improve these properties, this technology couples coal gangue with other materials to adjust the structure and chemical properties of the gangue soil. This neutralizes soil acidity, increases soil pH, improves the absorption capacity of plant roots, and promotes nutrient release and supply.

[0078] Simultaneously, by adjusting the concentration of electrolytes, solute types, and pH value in the soil solution, the properties of the soil solution are improved, and in conjunction with the inherent characteristics of coal gangue, a stable soil aggregate structure is constructed (see details). Figure 5 This provides a favorable living environment for plants and microorganisms.

[0079] In addition, to prevent the release of stable heavy metals from coal gangue from impacting the environment, this technology employs ion replacement and heavy metal passivation for phytoremediation and prevention using microorganisms.

[0080] Through the above methods, coal gangue can be transformed into soil suitable for plant growth, improving its properties, enhancing nutrient supply and water retention capacity, and providing a good growing environment for plants.

[0081] exist Figure 3 In this invention, the soil system constructed by modifying coal gangue, adding microbial combinations and fillers, forms a system suitable for plant growth. This artificial soil has increased water retention capacity, is acid-base neutralized to meet the growth needs of most plants, has diverse nutrients to promote normal plant growth and development, and the added microbial combinations maintain the biological activity of the soil.

[0082] Gangue artificial soil preparation process: The main processes for preparing artificial soil from coal gangue in this scheme include the following steps: 1. Pre-processing stage: Large impurities are removed, and coal gangue, along with necessary organic additives and inorganic minerals, are crushed to a particle size of less than 6 mm to achieve the required particle size.

[0083] 2. Activation process ( Figure 7 (Steps within the dashed box): By employing methods such as "precise analysis and activation" and "gap filling," suitable nutrient activators are formulated to transform coal gangue aggregate into effective and high-quality artificial soil.

[0084] 3. Mixing-Detection Process: Subsequently, the pretreated materials and activators are mechanically mixed to ensure uniform component distribution. Next, the nutrient composition is adjusted according to the soil's physicochemical properties and crop requirements. After molding, key indicators such as heavy metals, nutrients, and biomass are tested on the molded coal gangue artificial soil to ensure soil quality.

[0085] 4. Comparison and verification process: Finally, the high-quality artificial soil prepared is used for agricultural planting, greening and land reclamation projects, and the effects are monitored to ensure that the utilization of soil resources achieves the expected goals.

[0086] 5. Final artificial soil: The main components of coal gangue artificial soil include: coal gangue, air, water, organic matter, minerals, microorganisms, etc.

[0087] from Figure 5 and Figure 6 As can be seen, the formation process of the artificial coal gangue ecological soil of the present invention includes multiple steps of particle formation, and the granular structure of the coal gangue soil is formed through multiple complex aggregations. First, stable single particles of gangue aggregate with each other through binders such as humic acid, microorganisms, metabolic products, and liquid films to form compound particles or agglomerates. Subsequently, these compound particles further agglomerate, gradually forming micro-agglomerates, which then undergo multiple aggregations to finally form larger granular structures. Visually, these aggregates can be columnar, flaky, blocky, or granular. Coal gangue itself is rich in organic matter, minerals, and iron and aluminum oxides that contribute to the formation of granular structures. This technology constructs ecological artificial soil suitable for the survival of plants and microorganisms by improving the physicochemical properties of coal gangue and by means of water and fertilizer retention.

[0088] The metabolic products of this invention are microbial metabolic products, and the liquid membrane is functional water. Specific details are as follows: 1. Composition and generation mechanism of metabolites: In the humic acid formation system, metabolites specifically refer to three key substances secreted by humifying microbial communities (such as Azotobacter spp. and Pseudomonas spp.) during the decomposition of organic matter: (1) Enzyme metabolites: lignin peroxidase (LiP, EC 1.11.1.14) and manganese peroxidase (MnP, EC 1.11.1.13), whose activity reaches its peak at pH 6.5-7.8 (>200 U / mg); (2) Extracellular polymers: β-glucan (molecular weight 10-50 kDa) and lipopeptide biosurfactants (CMC value 0.05-0.2 g / L); (3) Redox mediators: quinone electron shuttles (such as anthraquinone-2-sulfonate, redox potential +150~+300 mV); Production pathway: α-ketoglutarate produced through the tricarboxylic acid cycle drives secondary metabolism. Under the induction of coal matrix, microorganisms initiate the expression of the hap gene cluster (RT-qPCR detection showed an increase in expression level of 3-5 times). 2. Structural characteristics and formation process of liquid films: Liquid films refer to nano-functional water interface films, which are essentially interfacial transition layers with special physicochemical properties. The composition is as follows: Alkaline aqueous phase: containing OH- - -K - Hydrated clusters (particle size 1-3 nm, Zeta potential -30 to -40 mV); acidic aqueous phase: HClO / ClO - Oxidizing microregions (ORP > +800 mV); Surfactant substances: humic acid-metal complexes (Fe-HA, Al-HA, etc.); Quartz, kaolinite, illite, and chlorite are derived from coal gangue itself; 3. Mineral occurrence state analysis: XRD quantitative analysis revealed typical coal gangue components:

[0089] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A coal-based modified artificial soil, characterized in that, include: Improved coal gangue, comprising 75% to 85% by weight, is obtained through the following steps: (1) Use acidic electrolyzed water with pH=1 to acid leach coal gangue to remove calcium, magnesium and iron ions; (2) Alkaline extraction was performed using alkaline electrolyzed water with pH=14 to obtain humate; (3) Acidification treatment was carried out again using acidic electrolyzed water with pH=1, and improved coal gangue was obtained by precipitation; The seedling filling material comprises 0.1% to 0.5% γ-polyglutamic acid, 4% to 5% a microbial composition, and 10% to 20% soil filler; the microbial composition consists of arbuscular mycorrhizal fungi, Trichoderma harzianum, and Bacillus mucilaginosus; the soil filler comprises peat moss, vermiculite, and perlite. The acidic electrolyzed water is prepared using a proton exchange membrane electrolyzer, employing a titanium-based ruthenium-iridium coated anode and a platinum / titanium cathode, at a voltage of 1.8–2.5 V and a current of 50–120 mA / cm². 2 Electrolysis of 0.5~1.0 mol / L H2SO4 solution under controlled current density and temperature of 30~45℃; The amount of alkaline electrolyzed water added is 10%~20% (v / w) of the dry basis mass of coal gangue, and the alkaline electrolyzed water is prepared by the following steps: (1) Electrolyte preparation: KOH or NaOH solution with a concentration of 0.8~1.2 mol / L is used as electrolyte; (2) Electrolysis parameters: a DC voltage of 2.2~2.8 V is applied, and the current density is controlled at 10~50 mA / cm. 2 (3) Electrode selection: Nickel-based electrodes are used as cathodes and anodes; (4) Membrane setup: Alkali-resistant anion exchange membranes are used to separate the anode and cathode regions to ensure that the pH of the cathode region is stable at 13~14; The acidic electrolyzed water produced by the proton exchange membrane electrolyzer has a pH of 1 and is rich in H+. + ,ClO - And hydroxyl radicals ·OH, with an ORP ≥ 1000 mV, can oxidize and decompose the encapsulated structure of silicate minerals in coal gangue, releasing the bound humic acid. The nickel-based electrode is nickel foam or nickel mesh.

2. The coal-based improved artificial soil according to claim 1, characterized in that, Peat moss, vermiculite, and perlite were mixed in a 3:1:1 ratio as soil filler.

3. The method for preparing coal-based modified artificial soil according to claim 1, characterized in that, Stable single particles of modified coal gangue aggregate with each other through humic acid, microorganisms, metabolites and liquid film binders to form compound particles or agglomerates; subsequently, these compound particles further agglomerate, gradually forming micro-agglomerates, which then undergo multiple agglomerations to eventually form larger agglomerate structures.

4. The use of coal-based modified artificial soil according to any one of claims 1 to 2 for the growth of drought- and salt-tolerant plants.

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