Coal-based improved artificial soil as well as preparation method and application thereof

Abstract

The invention relates to coal-based improved artificial soil as well as a preparation method and application thereof. The soil conditioner comprises improved coal gangue and seedling raising filler, the weight of the improved coal gangue is 75-85%, humic acid is treated and activated through an acid-alkali method, and the acid-alkali method treatment comprises the steps that humate is obtained through treatment with an alkaline solution, and the improved coal gangue is obtained through treatment with an acidic solution; the seedling raising filler comprises 0.1%-0.5% of gamma-polyglutamic acid, 4%-5% of a microbial composition and 10%-20% of a soil filler; the microorganism combination comprises arbuscular mycorrhizal fungi, trichoderma harzianum and bacillus mucilaginosus; the soil filler comprises turf, vermiculite and perlite.

Description

Technical Field

[0001] The present invention relates to artificial soil, and in particular to a technology for forming artificial soil by processing coal gangue. Background Art

[0002] Gangue, a solid waste generated during coal mining and washing, is rich in minerals and organic matter. However, due to its loose structure, unstable pH, and unstable content of components such as heavy metals, its direct use can be harmful to the environment. Currently, methods for using gangue for soil improvement primarily focus on simple physical and chemical treatments, which suffer from low treatment efficiency and environmental pollution, and thus fail to fully realize the potential value of gangue.

[0003] While some attempts have been made to improve gangue soils by adding organic matter or chemical amendments, the results have been less than satisfactory. Therefore, developing an efficient, environmentally friendly coal-based soil amendment that can be applied to coal-based artificial soils to effectively utilize gangue resources, improve soil structure, and enhance soil fertility has important practical significance and 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] In order to achieve the above-mentioned object, the present invention provides a coal-based improved artificial soil, which comprises coal gangue and seedling-raising filler; The weight of the improved gangue is 75% to 85%, and humic acid is activated by acid-base treatment. The acid-base treatment includes: alkaline solution treatment to obtain humate, and acid solution treatment to obtain improved gangue; The seedling filler includes 0.1% to 0.5% of γ-polyglutamic acid, 4% to 5% of microbial combination and 10% to 20% of soil filler; the microbial combination includes arbuscular mycorrhizal fungi, Trichoderma harzianum and Bacillus niger; the soil filler includes peat, vermiculite and perlite.

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

[0007] Preferably, the coal gangue accounts for 80%, γ-polyglutamic acid accounts for 0.24%, Trichoderma harzianum accounts for 0.17%, fascicular mycorrhizal fungi account for 3%, Bacillus subtilis accounts for 1%, vermiculite accounts for 3.118%, perlite accounts for 3.118%, and peat accounts for 9.354%.

[0008] Preferably, the acidic electrolyzed water is prepared by a proton exchange membrane electrolyzer, using a titanium-based ruthenium-coated iridium anode and a platinum / titanium cathode, and electrolyzing a 0.5-1.0 mol / L H2SO4 solution at a voltage of 1.8-2.5 V, a current density of 50-120 mA / cm², and a temperature control of 30-45°C. The cathode region produces a high concentration of H + and acidic electrolysis of water containing reactive oxygen species; Preferably, the amount of alkaline electrolyzed water added is 10% to 20% (v / w) of the dry mass of the gangue, and the alkaline electrolyzed water is prepared by the following steps: (1) electrolyte configuration: using a KOH or NaOH solution with a concentration of 0.8 to 1.2 mol / L as the electrolyte; (2) electrolysis parameters: applying a DC voltage of 2.2 to 2.8 V, and controlling the current density to be 10 to 50 mA / cm²; (3) electrode selection: using nickel-based electrodes as the cathode and anode; (4) diaphragm setting: using an alkaline-resistant anion exchange membrane to separate the anode and cathode regions, ensuring that the pH of the cathode region is stable at 13 to 14; Preferably, the pH of the acidic electrolyzed water is 1, H + The concentration is 1.0~1.2 mol / L, the ORP of active oxygen species is ≥1000 mV, and the nickel-based electrode is nickel foam or nickel mesh.

[0009] The present invention provides a method for preparing coal-based improved artificial soil, which comprises: Pretreatment: Dry and grind the gangue, sieve to remove large impurities, and crush to a particle size of less than 6mm; Humic acid extraction: First, use acidic solution and alkaline solution to dissolve the coal gangue and extract humic acid; Activation: Adding γ-polyglutamic acid (γ-PGA), Trichoderma harzianum, phytohormone fungi and Bacillus gloeosporioides to the treated coal gangue; Seedling filler mixture: Mix peat, vermiculite and perlite in a ratio of 3:1:1 as seedling filler; Final mixing: Mix the modified coal gangue after the above treatment with the seedling filling material evenly and apply it to the artificial soil.

[0010] The present invention provides a method for preparing coal-based improved artificial soil. Steps for improving coal gangue: acid leaching treatment: use acidic electrolyzed water with pH=1 for acid leaching, heat and stir in a boiling water bath for 1.5 hours, let it stand to room temperature, and then filter and wash until neutral; alkali solution extraction: use alkaline electrolyzed water with pH=14, add electrolyzed water at a liquid-solid ratio of 3:1, heat and stir in a boiling water bath for 2 hours, cool and filter after the reaction is completed; filtrate treatment: use acidic electrolyzed water with pH=1 for acidification, add it in batches until the pH of the system stabilizes at 1-2, let it stand for 45 minutes, then filter, wash the filter cake with deionized water and dry it in an 80°C oven to obtain improved coal gangue.

[0011] The present invention provides a method for preparing coal-based improved artificial soil. The stable single particles of improved coal gangue are agglomerated with each other through humic acid, microorganisms, metabolic products and liquid film adhesives to form complex particles or sticky clusters; then, these complex particles further bond together to form microaggregates step by step, and the microaggregates are agglomerated multiple times to eventually form a larger aggregate structure.

[0012] The coal-based improved artificial soil provided by the present invention is used for growing drought-resistant and salt-resistant plants.

[0013] The invention provides a method for growing drought- and salt-tolerant plants using the coal-based improved artificial soil, which includes: the drought- and salt-tolerant plants are alfalfa, ryegrass, sweet clover, purslane or alkali reed.

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

[0015] Gangue typically has highly acidic and infertile soil properties, making it unfavorable for plant growth. To improve its properties, this technology combines gangue with other materials to adjust the structure and chemistry of the gangue soil. This neutralizes the soil's acidity, raises the soil's pH, improves plant root absorption, and promotes nutrient release and availability.

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

[0017] The environmental advantages of the electrolytic water treatment method are: zero chemical addition: electrolytic water generates H in situ by electrolyzing NaCl or KOH solution. + / OH -, no external strong acid or alkali is required, reducing the use of hazardous chemicals; closed-loop circulation: waste liquid can be regenerated and reused through the electrolytic cell, reducing the cost of wastewater treatment (comparison: ordinary acid-base method produces high-salt wastewater that needs neutralization treatment). BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a specific embodiment of the improved artificial soil of the present invention; Figure 2 is a chemical structure diagram of γ-PGA, a substance to which the present invention is applied; Figure 3 This is a diagram showing the process of the gangue artificial soil of the present invention acting on plants; Figure 4 This is a comparison chart of pollution risk control indicators in the application of the gangue artificial soil of the present invention; Figure 5 Schematic diagram of the principle of the gangue soil aggregate structure of the present invention; wherein: a. Gangue aggregate structure; b. Aggregate internal composition structure; c. Structural type; d. Gangue artificial soil; Figure 6 This is a schematic diagram of the composition principle of the artificial soil formed from coal gangue of the present invention; Figure 7 The present invention is a flow chart of the method for preparing coal-based artificial soil and the selection of supporting suitable plants. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

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

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

[0023] The present invention provides a method for preparing coal-based improved artificial soil, which comprises: Pretreatment: Dry and grind the gangue, sieve to remove large impurities, and crush to a particle size of less than 6mm; Humic acid extraction: First, use acidic solution and alkaline solution to dissolve the coal gangue and extract humic acid; Activation: Adding γ-polyglutamic acid (γ-PGA), Trichoderma harzianum, phytohormone fungi and Bacillus gloeosporioides to the treated coal gangue; Seedling filler mixture: mix peat, vermiculite and perlite in a ratio of 3:1:1 as seedling filler; Final mixing: Mix the modified coal gangue after the above treatment with the seedling filling material evenly and apply it to the artificial soil.

[0024] Example 1: The formula in this embodiment includes eight components: modified coal gangue, γ-polyglutamic acid, a microbial combination (Trichoderma harzianum, fascicular mycorrhizal fungi, and Bacillus colloidosus), vermiculite, perlite, peat, and drought- and salt-tolerant plants (such as alfalfa, ryegrass, sweet clover, purslane, and alkali grass). In a preferred embodiment, the weight ratio of the modified coal gangue and the filler (γ-polyglutamic acid, microbial combination, vermiculite, perlite, and peat) is 8:2, that is, the modified coal gangue accounts for 80% and the filler accounts for 20%. The proportions of the specific components of the filler are: γ-polyglutamic acid accounts for 0.24%, Trichoderma harzianum accounts for 0.17%, fascicular mycorrhizal fungi accounts for 3%, Bacillus colloidosus accounts for 1%, vermiculite accounts for 3.118%, perlite accounts for 3.118%, and peat accounts for 9.354%. That is Figure 1 Scale shown.

[0025] Improved coal gangue is coal gangue that has been treated with acid and alkaline water. The specific treatment process is as follows: The present invention uses electrolytic water to activate humic acid in coal gangue. The humic acid in low-rank coal in the gangue is activated by using the anode and cathode products (i.e., acidic and alkaline water) of water electrolysis. The entire activation process includes pretreatment, dissolution reaction, and acid precipitation separation. The detailed process is as follows: The general route for activating humic acid from coal gangue is: coal drying → grinding and screening → impurity removal with acidic water → filtration and washing → activation with alkaline water → filtration → acidification of filtrate → standing and stratification → filtration and washing → filter cake drying → product.

[0026] The final product is modified coal gangue, which contains extracted humic acid and some separated trace elements. The following Table 1 has an analysis of the nutritional components.

[0027] Specific implementation method of improved 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 it stand to room temperature, and then filter and wash until neutral; Step 3: After adding distilled water, add alkaline electrolyzed water with a pH of 14, preferably 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; Step 4: Acidification is performed using acidic electrolyzed water with a pH of 1, which is added in portions until the pH of the system stabilizes at 1-2. After standing for 45 minutes, the filter is filtered and the filter cake is washed with deionized water and dried in an oven at 80°C to obtain improved coal gangue. The finished improved coal gangue is mainly composed of humic acid and contains other components that can be separated from the humic acid.

[0028] Research results: The free humic acid content accounted for 45.03%, and the total humic acid accounted for 49.24%.

[0029] 1. Free humic acid determination (45.03%): Test standard: Based on GB / T 11957-2001 "Determination of humic acid yield in coal" Method 3; The experimental process is as follows: alkaline extraction: take 1.0g of dry coal sample (80 mesh), add 100mL of 1% NaOH solution, and shake in a water bath at 90℃ for 2 hours; centrifugal separation: centrifuge at 4000r / min for 15 minutes (retain the supernatant); acidification precipitation: adjust the pH to 1.5-2.0 (using 6mol / L HCl), and let it stand for 12 hours; gravimetric determination: after filtration, dry at 80℃ to constant weight, calculate: free humic acid (%) = (precipitate mass / coal sample mass) × 100 × correction factor (0.92).

[0030] 2. Determination of total humic acid (49.24%): Test 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) and reflux at 95°C for 4 hours; Secondary extraction: Repeat the extraction of the residue twice (cumulative extraction efficiency > 98%); UV spectrometry: Dilute the combined extract to an appropriate concentration and measure the absorbance at a wavelength of 465 nm (standard curve method, R² > 0.999). Calculation formula: Total humic acid (%) = (C × V × D) / (m × 10 6 ) × 100; (C: standard curve concentration, V: volume, D: dilution factor, m: sample mass).

[0031] The present invention uses γ-polyglutamic acid (γ-PGA), which is polymerized from L-type and D-type glutamic acid monomers through α-amino and γ-carboxyl groups via amide bonds (polymerized from 500-5000 glutamic acid monomers), and has good water solubility, water absorption, water retention, biodegradability, heavy metal ion adsorption, and promotion of aggregate structure. At the same time, the water absorption multiple of γ-PGA in its natural state can reach up to 1108.4 times, which is more than 1 times higher than the water absorption multiple of polyacrylic acid absorbent resins. The absorption multiple of γ-PGA for soil moisture is between 30-80 times, and it has significant drought resistance and seedling promotion effects and slow-release effects. The chemical structure is as follows: Figure 2 shown.

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

[0033] 1. Extraction Principle Humic acid is insoluble in acid but soluble in alkali. 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 easily form complexes with humic acid, thus affecting the extraction effect, this technology uses acidic water for preliminary treatment to remove some of the calcium, magnesium, iron and other ions, and then performs alkaline extraction and acid precipitation to extract humic acid.

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

[0035] Alkali dissolution: Use hydroxide-containing alkaline water to dissolve humic acid. The carboxyl group (—COOH) and phenolic hydroxyl group (—OH) in humic acid react with alkaline substances (such as KOH, NaOH, Na2CO3, Na4P2O7, ammonia water, etc.) to form soluble humates.

[0036] Acid precipitation: Finally, use acidic water to adjust the pH to <2, perform solid-liquid separation, and achieve the purification and separation of humic acid.

[0037] 3. Acid and alkaline water characteristics The characteristics of acidic and alkaline water are as follows: alkaline water contains hydroxide and potassium ions, which are essential for plants; acidic water contains acidic hydrogen ions and hypochlorite ions. Experiments have shown that acidic water tends to become neutral over time after use. Therefore, it is feasible to use acidic and alkaline water instead of sodium hydroxide and hydrochloric acid to activate humic acid in low-rank coal.

[0038] More specifically, the electrochemical characteristics of the electrolyzed water 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 high ORP (≥1000 mV) of hydroxyl radicals (·OH) can oxidatively decompose the encapsulation structure of silicate minerals in coal gangue, releasing the bound humic acid; at the same time, ·OH undergoes a decarboxylation reaction with the aromatic ring in the humic acid macromolecule to generate small molecular humic acid fragments, thereby improving its bioavailability.

[0039] Alkaline electrolyzed water: The high pH environment in the cathode area (pH = 13 ~ 14) promotes the reaction of humic acid and K + / Na + Combined to form water-soluble humates, avoiding the traditional alkali treatment due to Ca 2+ / Mg 2+ In addition, nanobubbles (particle size <100 nm) in electrolyzed water can penetrate into the micropores of coal gangue and enhance the mass transfer efficiency.

[0040] 4. Extraction routes and methods Extraction route: weathered coal drying → grinding and screening → acid removal → filtration and washing → alkali activation → filtration → filtrate acidification → standing 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 amount of the mixture, add acidic water with pH = 1, heat and stir in a boiling water bath for 1 hour, let it stand at room temperature, and then filter and wash until neutral; (3) After adding distilled water, add alkaline electrolyzed water with a pH of 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) Acidification was performed using electrolyzed acidic water with a pH of 1, which was added in portions until the pH of the system was stabilized at 1 to 2. After standing for 45 minutes, the mixture was filtered and the filter cake was washed with deionized water and dried in an oven at 80°C to obtain improved gangue. The improved gangue product was mainly composed of humic acid and contained other components that could be separated from the humic acid.

[0042] 5. Effect of alkali dosage Taking NaOH as an example, an experiment was conducted: 50g of weathered coal was taken at a solid-liquid ratio of 1:3, and NaOH was added at ratios 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 25°C water bath for 1 hour, and the humic acid extraction rate was measured. The experimental results showed that the humic acid extraction rate gradually increased with increasing NaOH dosage, but the increase slowed down 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 by a proton exchange membrane electrolyzer, using a titanium-based ruthenium-coated iridium anode and a platinum / titanium cathode, and electrolyzing a 0.5-1.0 mol / L H2SO4 solution at a voltage of 1.8-2.5 V, a current density of 50-120 mA / cm², and a temperature control of 30-45°C. The cathode region produces a high concentration of H + and acidic electrolysis of water containing reactive oxygen species; Preferably, the amount of alkaline electrolyzed water added is 10% to 20% (v / w) of the dry mass of the gangue, and the alkaline electrolyzed water is prepared by the following steps: (1) electrolyte configuration: using a KOH or NaOH solution with a concentration of 0.8 to 1.2 mol / L as the electrolyte; (2) electrolysis parameters: applying a DC voltage of 2.2 to 2.8 V, and controlling the current density to be 10 to 50 mA / cm²; (3) electrode selection: using nickel-based electrodes as the cathode and anode; (4) diaphragm setting: using an alkaline-resistant anion exchange membrane to separate the anode and cathode regions, ensuring that the pH of the cathode region is stable at 13 to 14; Preferably, the pH of the acidic electrolyzed water is 1, H + The concentration is 1.0~1.2 mol / L, the ORP of active oxygen species is ≥1000 mV, and the nickel-based electrode is nickel foam or nickel mesh.

[0044] In order to further illustrate the difference between the effects of the electrolyzed acid-base water of the present invention and ordinary acid-base solutions, the following comparative examples are given for illustration.

[0045] Comparative Example 1: Comparison of humic acid extraction efficiency between electrolyzed acid-base water and ordinary acid-base solution: Experimental design: The same weathered coal sample (free humic acid content 45.03%) was 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] Treatment conditions: liquid-to-solid ratio 3:1, heating in a boiling water bath for 2 hours, and testing the humic acid extraction rate after filtration.

[0047] Experimental results:

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

[0049] Comparative Example 2: Synergistic Effect of Electrolyzed Water on Microbial Activity Experimental design: Trichoderma harzianum (0.17%) and Bacillus subtilis (1%) were inoculated into the following two groups: Group A: modified coal gangue treated with electrolyzed water; Group B: Coal gangue treated with ordinary acid and alkali.

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

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

[0052] Mechanism explanation: The trace amount of reactive oxygen species (such as H2O2) remaining in electrolyzed water can stimulate microorganisms to produce stress enzymes (such as SOD, catalase), thereby increasing their metabolic activity. + / Na + Ions (from alkaline electrolyzed water) form chelates with humic acid, promoting the fixation and release of phosphorus and potassium by microorganisms. Therefore, after using this electrolyzed water to treat coal gangue, the activity of microorganisms inoculated on it is correspondingly increased, which is beneficial to plant growth.

[0053] The environmental advantages of the electrolytic water treatment method are: zero chemical addition: electrolytic water generates H in situ by electrolyzing NaCl or KOH solution. + / OH - , no external strong acid or alkali is required, reducing the use of hazardous chemicals; closed-loop circulation: waste liquid can be regenerated and reused through the electrolytic cell, reducing the cost of wastewater treatment (comparison: ordinary acid-base method produces high-salt wastewater that needs neutralization treatment).

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

[0055] Selection and application of microorganisms in the present invention: This technology uses arbuscular mycorrhizal fungi, Trichoderma harzianum and Bacillus spp. to synergistically activate gangue to prepare artificial soil: 1. Arbuscular mycorrhizal fungi (AMF): They significantly increase the available nutrient content in the soil, improving substrate fertility and promoting plant growth. In mining wasteland reclamation, AMF coexist with 90% of higher plants, improving underground ecosystems and increasing their productivity and diversity.

[0056] 2. Trichoderma harzianum: Highly adaptable and harmless to humans, animals, and plants, it acquires mineral nutrients through its hyphae, increasing phosphorus and potassium levels in the soil and supporting plant growth. It also improves plant biomass, root function, and soil enzyme activity, and has demonstrated significant effectiveness in preventing and controlling soil-borne plant diseases.

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

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

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

[0060] 5. Plant selection: In order to improve efficiency and economic benefits, this technology selects drought- and salt-tolerant plants, such as alfalfa, ryegrass, sweet clover, purslane and alkali grass, which have shown good drought and salt tolerance in research by many scholars.

[0061] Experimental example of basic nutritional components detection of the improved coal gangue prepared by the present invention: Improved coal gangue (powder): moisture content 7.51%, pH 7.63, organic matter 2.53%, alkaline nitrogen 0.53 mg / kg, available phosphorus 117.44 mg / kg, available potassium 172.22 mg / kg, and the rest are inorganic matter.

[0062] The inorganic components of improved coal gangue (powder) (calculated on a dry basis) are as follows: 1. Silicon aluminum oxide (accounting for 60-75%): SiO2: 45-55% (mainly from silicate minerals such as quartz and feldspar); Al2O3: 15-25% (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 compounds (8-15%): Fe2O3: 6-12% (in the form of hematite and goethite); FeS2: 0.5-2% (residual pyrite, the content is significantly reduced after oxidation treatment); 3. Calcium and magnesium compounds (5-10%): CaO: 3-6% (in the form of calcite and gypsum); MgO: 1-3% (in the form of dolomite and magnesite); Acid neutralization capacity (ANC): ≥2.5 mol H + / kg; 4. Other metal oxides (2-5%): TiO2: 0.5-1.5% (anatase, rutile forms); 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 carbonate mineral content (e.g., calcite) is reduced to <3%, the sulfide oxidation rate is >85%, and the cation exchange capacity (CEC) is increased to 15-20 cmol(+) / kg. The specific surface area measured by BET is 25-35 m² / g, and the porosity is maintained in the range of 35-40%.

[0064] Filler (peat: 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 rest is inorganic matter.

[0065] The relevant technical indicators of the artificial soil of the present invention after processing are shown in Table 1 below: Table 1 Related technical indicators of nutrient composition of coal gangue artificial soil

[0066] Soil electrical conductivity EC in the table: represents the soluble salt ions (Na + , K + , Ca 2+ Mg 2+ 、Cl - 、SO4 2- The unit is usually dS / m (decisiemens / meter) or mS / cm (millisiemens / centimeter), 1 dS / m=1 mS / cm.

[0067] Application cases as plant cultivation: Coal-based artificial soil was used in greenhouse alfalfa cultivation. Compared to loess, the plants grew healthier, with significantly increased plant height and biomass. Soil pollution risk indicators were superior to those in the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB 15618-2018). Specific growth results are shown in Tables 2 and 3 below.

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

[0069] Control group: Pure mining soil was used for indoor cultivation of alfalfa, with 50 plants planted, and other conditions remained unchanged.

[0070] After 20 days, the plant height, biomass, and heavy metal content of alfalfa were recorded, as shown in Tables 2 and 3.

[0071] Table 2 Plant growth statistics

[0072] Table 3 Statistics of changes in heavy metals in aboveground parts (dry weight)

[0073] As shown in Table 2, the plant height and biomass of alfalfa in the coal-based artificial soil were higher than those in the blank control group. Observation of the growth process revealed that the leaves of alfalfa in the coal-based artificial soil were bright green, the soil moisture was maintained for a long time, the soil was not compacted, and the air permeability was good, which effectively promoted the growth of alfalfa.

[0074] In addition, a comparative analysis of heavy metal content in the aboveground dry weight of alfalfa grown in coal-based artificial soil and loess soil revealed a deviation of less than 2% (Table 3), indicating that the coal-based artificial soil performed the same well as the soil. After multiple rounds of planting, the fertilizer efficiency remained relatively high, with alfalfa growing in the coal-based artificial soil still outperforming that in ordinary soil. Furthermore, the pollution risk indicators in the coal-based artificial soil were compared with the risk control values ​​for pollutants in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial) (GB 15618-2018), and it was found that all indicators were superior to the control standard values. For details, see [Table 3]. Figure 4 As shown. Figure 4 It can be seen that the concentrations of arsenic, copper, zinc, lead, nickel and chromium are significantly lower than those in the standard group, which shows that the pollutants have been effectively controlled.

[0075] Preferably, the present invention requires testing the composition of coal gangue, including information on its mineral composition, chemical composition, and physical and chemical properties. Analysis of this information can provide basic data support for the direction of coal-based artificial soil and soil improvement, functional design, technical solution planning, plant screening, and microbial configuration. The main measurement items are as follows: a) Organic matter content: The content of organic matter in the gangue to assess its contribution to soil fertility; b) pH value: determines the acidity and alkalinity of coal gangue, providing 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: Determine the content of major nutrient elements in coal gangue to provide reference for plant selection and nutrient management.

[0076] Principle of coal gangue artificial soil technology: This technology adopts the methods of "using waste to treat waste", "rational utilization of resources", "adjustment of soil solution properties" and "combination of microorganisms and plants", and cooperates with the organic matter, minerals, iron and aluminum oxides and other components of coal gangue to optimize the structure of coal gangue artificial soil, produce soil suitable for plant growth, effectively improve the properties of coal gangue, enhance nutrient supply and water retention capacity, and provide an excellent growth environment for plants (see Figure 3 ).

[0077] Gangue typically has highly acidic and infertile soil properties, making it unfavorable for plant growth. To improve its properties, this technology combines gangue with other materials to adjust the structure and chemistry of the gangue soil. This neutralizes the soil's acidity, raises the soil's pH, improves plant root absorption, and promotes nutrient release and availability.

[0078] At the same time, by adjusting the concentration of soil solution electrolytes, solute type and pH value, the properties of soil solution are improved, and the characteristics of coal gangue are coordinated to build a stable soil aggregate structure (see Figure 5 ), providing a good living environment for plants and microorganisms.

[0079] In addition, in order to prevent the precipitation of stable heavy metals in coal gangue from affecting the environment, this technology uses ion replacement and heavy metal passivation to carry out plant and microbial remediation and prevention.

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

[0081] exist Figure 3 In the soil system constructed by the present invention, a system suitable for plant growth is formed by adding a microbial combination and filler to the modified coal gangue. The artificial soil has increased water retention capacity, acid-base neutralization and is suitable for the growth needs of most plants. The diverse nutrients promote the normal growth and development of plants, and the added microbial combination maintains the biological activity of the soil.

[0082] Preparation process of artificial soil from waste rock: The process flow of preparing artificial soil from coal gangue in this scheme mainly includes the following steps: 1. Preprocessing: Remove large impurities and crush the coal gangue and necessary organic additives and inorganic minerals to a particle size less than 6mm to achieve the required particle size.

[0083] 2. Activation process ( Figure 7 Steps in the dotted box): Through the methods of "precise analysis and activation" and "checking for deficiencies and filling in the gaps", suitable nutrient activators are formulated to transform coal gangue aggregates into effective and high-quality artificial soil.

[0084] 3. Mixing-detection process: The pretreated material is then mechanically mixed with an activator to ensure uniform distribution of ingredients. Next, the nutrient content is adjusted based on the soil's physical and chemical properties and crop needs. After forming, the final gangue artificial soil is tested for key indicators, such as heavy metals, nutrients, and biomass, to ensure soil quality.

[0085] 4. Comparison and verification process: Finally, the prepared high-quality artificial soil is used in agricultural planting, greening, land restoration and other projects, and the effects are monitored to ensure that the soil resource utilization 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 It can be seen that the formation process of the artificial gangue ecological soil of the present invention includes multiple steps of particle formation, and the aggregate structure of the gangue soil is formed through multiple composite agglomerations. First, the stable single particles of gangue are agglomerated with each other through adhesives such as humic acid, microorganisms, metabolites and liquid films to form complex particles or sticky masses. Subsequently, these complex particles further bond together to form microaggregates step by step, and the microaggregates are agglomerated multiple times to eventually form a larger aggregate structure. From the appearance, it can be formed into columnar, flaky, blocky or granular shapes. The gangue itself is rich in organic matter, minerals, iron and aluminum oxides and other components that contribute to the formation of aggregate structure. This technology constructs an ecological artificial soil suitable for the survival of plants and microorganisms by improving the physical and chemical properties of gangue and retaining water and fertilizer.

[0088] The metabolites of the present invention are metabolites of microorganisms, and the liquid film is functional water. The specific description is 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 microorganisms (such as brown spherical nitrogen-fixing bacteria and Pseudomonas) 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 a peak at pH 6.5-7.8 (>200 U / mg); (2) extracellular polymers: β-glucan (molecular weight 10-50 kDa), lipopeptide biosurfactants (CMC value 0.05-0.2 g / L); (3) redox mediators: quinone electron shuttles (such as anthraquinone-2-sulfonate, redox potential +150 to +300 mV); Production pathway: α-ketoglutarate produced through the tricarboxylic acid cycle (TCA cycle) drives secondary metabolism. Under the induction of coal substrate, microorganisms start to express the hap gene cluster (RT-qPCR detection shows that the expression level increases by 3-5 times); 2. Structural characteristics and formation process of liquid membrane: Liquid membrane refers to a nano-functional water interfacial membrane, which is essentially an interfacial transition layer with special physical and chemical 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 - Oxidative micro-area (ORP>+800 mV); Surface active substances: humic acid-metal complexes (Fe-HA, Al-HA, etc.); Quartz, kaolinite, illite, and chlorite originate from the coal gangue itself; 3. Analysis of mineral occurrence status: XRD quantitative analysis shows the typical components of coal gangue:

[0089] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A coal-based improved artificial soil, characterized in that: include: Improved gangue, wherein the weight of improved gangue is 75% to 85%, and humic acid is activated by acid-base treatment, wherein the acid-base treatment includes: alkaline solution treatment to obtain humate, and acidic solution treatment to obtain improved gangue; the acidic solution is acidic electrolyzed water, and the alkaline solution is alkaline electrolyzed water; Seedling filler, the seedling filler includes 0.1% to 0.5% of γ-polyglutamic acid, 4% to 5% of microbial combination and 10% to 20% of soil filler; the microbial combination includes arbuscular mycorrhizal fungi, Trichoderma harzianum and Bacillus niger; the soil filler includes peat, vermiculite and perlite.

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

3. The coal-based improved artificial soil according to claim 1, characterized in that: The modified coal gangue accounted for 80%, γ-polyglutamic acid accounted for 0.24%, Trichoderma harzianum accounted for 0.17%, fascicular mycorrhizal fungi accounted for 3%, Bacillus subtilis accounted for 1%, vermiculite accounted for 3.118%, perlite accounted for 3.118%, and peat accounted for 9.354%.

4. The method for preparing coal-based improved artificial soil according to claim 1, characterized in that: include: Pretreatment: Dry and grind the gangue, sieve to remove large impurities, and crush to a particle size of less than 6mm; Humic acid extraction: First, use acidic solution and alkaline solution to dissolve the coal gangue and extract humic acid; Activation: Adding γ-polyglutamic acid (γ-PGA), Trichoderma harzianum, phytohormone fungi and Bacillus gloeosporioides to the treated coal gangue; Seedling filler mixture: mix peat, vermiculite and perlite in a ratio of 3:1:1 as seedling filler; Final mixing: Mix the modified coal gangue after the above treatment with the seedling filling material evenly and apply it to the artificial soil.

5. The method for preparing coal-based improved artificial soil according to claim 4, characterized in that: The steps of improving the coal gangue include: acid leaching treatment: using acidic electrolyzed water with a pH of 1 for acid leaching, heating and stirring for 1.5 hours in a boiling water bath, letting it stand to room temperature, and then filtering and washing until neutral; alkali solution extraction: using an alkaline electrolyzed water solution with a pH of 14, adding electrolyzed water at a liquid-solid ratio of 3:1, heating and stirring for 2 hours in a boiling water bath, cooling and filtering after the reaction is completed; filtrate treatment: using acidic electrolyzed water with a pH of 1 for acidification, adding in batches until the pH of the system stabilizes at 1-2, letting it stand for 45 minutes, and then filtering, washing the filter cake with deionized water and drying in an 80°C oven to obtain improved coal gangue.

6. The method for preparing coal-based improved artificial soil according to claim 5, characterized in that: The acidic electrolyzed water is prepared by a proton exchange membrane electrolyzer, using a titanium-based ruthenium-coated iridium anode and a platinum / titanium cathode to electrolyze a 0.5-1.0 mol / L H2SO4 solution at a voltage of 1.8-2.5 V, a current density of 50-120 mA / cm², and a temperature control of 30-45°C. The cathode region produces a high-concentration H + and acidic electrolysis of water containing reactive oxygen species; The amount of alkaline electrolyzed water added is 10% to 20% (v / w) of the dry mass of the coal gangue, and the alkaline electrolyzed water is prepared by the following steps: (1) electrolyte configuration: using a KOH or NaOH solution with a concentration of 0.8 to 1.2 mol / L as the electrolyte; (2) electrolysis parameters: applying a DC voltage of 2.2 to 2.8 V, and controlling the current density to be 10 to 50 mA / cm²; (3) electrode selection: using nickel-based electrodes as the cathode and anode; (4) diaphragm setting: using an alkaline-resistant anion exchange membrane to separate the anode and cathode regions, ensuring that the pH of the cathode region is stable at 13 to 14.

7. The method for preparing coal-based improved artificial soil according to claim 6, characterized in that: The pH of the acidic electrolyzed water is 1, H + The concentration is 1.0~1.2 mol / L, the active oxygen species ORP is ≥1000 mV, and the nickel-based electrode is nickel foam or nickel mesh; the high active oxygen species ORP is used to oxidatively decompose the encapsulation structure of silicate minerals in coal gangue and release the bound humic acid.

8. The method for preparing coal-based improved artificial soil according to claim 4, characterized in that: The stable single particles of improved coal gangue are agglomerated with each other through humic acid, microorganisms, metabolic products and liquid film adhesives to form complex particles or sticky clusters; then, these complex particles further bond together to form microaggregates step by step, and the microaggregates are agglomerated multiple times to eventually form a larger aggregate structure.

9. Use of the coal-based improved artificial soil according to any one of claims 1 to 3 for growing drought- and salt-tolerant plants.

10. Use of the coal-based improved artificial soil according to any one of claims 1 to 3 as a soil for growing drought- and salt-tolerant plants, characterized in that: include: Drought- and salt-tolerant plants include alfalfa, ryegrass, sweet clover, purslane or alkali reed.

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