An integrated method for sand control and soil improvement based on coal gangue.

Abstract

This invention discloses an integrated method for sand control and soil improvement based on coal gangue. The specific steps are as follows: After crushing and grading the coal gangue, coal gangue with a particle size of 0.1~10 mm is selected and activated by adding Bacillus thuringiensis and compound additives. The activated coal gangue is mixed with sand particles, and then coal gangue with a particle size of 10~100 mm is laid on the desert surface to complete the integrated treatment. Under the combined action of Bacillus thuringiensis and compound additives, the coal gangue is accelerated to degrade into a fine-particle matrix, and the organic matter contained therein is simultaneously degraded to generate humic acid. At the same time, the metabolites and bioenzymes of Bacillus thuringiensis can promote the slow release of nutrients such as silicon, potassium, and phosphorus in the coal gangue, thereby improving the physicochemical properties of desert sand particles. Combined with the surface laying effect of coarse-particle coal gangue, the dual purpose of sand control and soil improvement is finally achieved.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization of coal gangue and desert control technology, and relates to an integrated method for sand prevention and fixation and soil improvement based on coal gangue. Background Technology

[0002] Currently, the main ways to comprehensively utilize coal gangue are as follows: (1) Production of building materials: The addition of activated coal gangue can significantly improve the pore structure, and the activated coal gangue can be used as a cement raw material; (2) Preparation of chemical products: Coal gangue can be extracted and utilized in a high-value manner through different process methods, such as the synthesis of polyaluminum chloride, white carbon black, water glass and molecular sieve, so as to maximize the utilization of resources; (3) Underground backfilling and road filling: It can be used for road construction, backfilling of mining voids and subsidence areas to save costs and transportation expenses; (4) Use for soil improvement: Coal gangue is rich in organic matter, and its content can reach 15%~25%. In addition, coal gangue also contains a variety of trace elements and nutrients, which are similar to the composition of soil; Coal gangue powder has a large porosity, and its pore structure can inhibit soil adhesion and increase soil permeability. Simultaneously, it can absorb air and moisture, creating a favorable soil environment for microbial growth, promoting the metabolism of aerobic and facultative bacteria, enhancing biological activity, thereby improving soil fertility and promoting plant growth. However, due to limitations imposed by the different physicochemical properties of coal gangue and transportation distances, current methods of utilizing coal gangue suffer from drawbacks such as a single recycling target, high consumption of reagents and energy, inability to achieve large-scale resource utilization, and failure to realize the comprehensive management goal of sand control and stabilization in the arid northwest regions.

[0003] Based on this, the present invention is proposed. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention aims to provide an integrated method for sand control and soil improvement based on coal gangue. The specific steps are as follows: Coal gangue is crushed and graded, with particles ranging from 0.1 to 10 mm selected. Bacillus thuringiensis and a compound additive are added for activation. The activated coal gangue is mixed with sand particles, and then coal gangue with particles ranging from 10 to 100 mm is laid on the desert surface, thus completing the integrated treatment. Under the combined action of Bacillus thuringiensis and the compound additive, the coal gangue degrades rapidly to form a fine-particle matrix, and its organic matter simultaneously degrades to generate humic acid. Simultaneously, the metabolites and enzymes of Bacillus thuringiensis promote the slow release of nutrients such as silicon, potassium, and phosphorus from the coal gangue, thereby improving the physicochemical properties of the desert sand particles. Combined with the surface laying effect of coarse-particle coal gangue, the dual purpose of sand control and soil improvement is ultimately achieved.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An integrated method for sand control and soil improvement based on coal gangue is carried out in the following steps:

[0007] S1. The coal gangue is subjected to closed-circuit coarse crushing and sieved to a particle size of <100 mm, and then subjected to medium crushing to obtain coal gangue particles and coal gangue powder.

[0008] Coal gangue is the primary ore discharged during the coal mining process, which contains more than 50% silicon dioxide, less than 10% carbon, less than 100 mg / kg of available silicon, less than 200 mg / kg of available potassium, and less than 50 mg / kg of available phosphorus.

[0009] S2. After the above-mentioned medium-crushed coal gangue with a particle size of 0.1~10 mm is mixed evenly with Bacillus thuringiensis, compound additives are added, and after stirring evenly, fermentation is carried out to obtain a coal gangue mixture.

[0010] S3. Use a rotary tiller to mix the coal gangue mixture with sand evenly, and the rotary tillage depth is 250-500mm during mixing; then spread the coal gangue with a particle size of 10-100 mm from step S1 evenly on the desert surface at a rate of 20-50 tons / acre, and lightly compact it.

[0011] As a limitation of the present invention, in step S1, the proportion of 10-100 mm particles in the coal gangue after medium crushing is 20%-30%, the proportion of 1 mm-10 mm particles is 20%-30%, and the proportion of <1 mm particles is 40%-60%.

[0012] As another limitation of the present invention, in step S2, the compound additive is composed of magnesium sulfate, sucrose, humic acid and sodium molybdate.

[0013] As a third limitation of the present invention, in step S2, the mass ratio of the coal gangue with a particle size of 0.1~10 mm to Bacillus thuringiensis, magnesium sulfate, sucrose, humic acid and sodium molybdate is (10000~50000):1:(10~150):(20~250):(300~4500):(2~25).

[0014] As a fourth limitation of the present invention, in step S2, the Bacillus thuringiensis is a bacterial powder containing a solid culture medium, wherein the proportion of live bacteria effective ingredients is 10-40%.

[0015] As a fifth limitation of the present invention, in step S2, the fermentation temperature is 15~45°C and the time is 3~7 days.

[0016] As a sixth limitation of the present invention, in step S3, when the coal gangue mixture is mixed with sand, the coal gangue mixture is mixed with sand at a rate of 30 to 150 tons per acre.

[0017] As a seventh limitation of the present invention, in step S3, the rotary tiller used for rotary tillage is a single-shaft type, the height difference between the left and right blade tips does not exceed 1 cm, and the angle between the drive shaft and the forward direction is less than 8 degrees. ° .

[0018] This invention utilizes Bacillus thuringiensis, magnesium sulfate, sucrose, humic acid, and sodium molybdate to activate coal gangue, wherein: magnesium sulfate provides Mg... 2+ and SO4 2- It can react with Ca in coal gangue 2+ Al 3+ The formation of soluble salts disrupts the silicate structure, releasing nutrients such as Si, P, and K. Sucrose serves as a carbon source driving the metabolism of Bacillus thuringiensis, and the key enzymes in sucrose decomposition require Mg. 2+ The presence of magnesium sulfate increases sucrose metabolism efficiency by over 30%, significantly enhancing the dissolution of nutrients; humic acid can reduce Fe through chelation. 3+ Al 3+ It fixes phosphorus, increases the dissolution of available phosphorus, and can also react with Mg in magnesium sulfate. 2+ Formation of soluble complexes to prevent Mg 2+ It is fixed by silicates, while maintaining the excessive acidification caused by the decrease in pH due to sucrose metabolism, thus improving bioavailability; sodium molybdate activates the nitrogen-fixing and phosphorus-solubilizing genes of Bacillus thuringiensis, increasing the production of organic acids and phosphatases; magnesium sulfate contains Mg 2+ This ensures that sodium molybdate functions efficiently, and the electron shuttle ability of humic acid can enhance the catalytic efficiency of molybdenum, further releasing fixed nutrients such as phosphorus and potassium.

[0019] Furthermore, silicon, phosphorus, and potassium dissolved from coal gangue can achieve a slow-release effect by working in conjunction with magnesium sulfate, sucrose, humic acid, and sodium molybdate. Silicon can promote the absorption of magnesium by plants. 2+ Phosphorus enhances the absorption of nutrients, thus improving photosynthesis and enzyme activity. When combined with humic acid, it can enhance plant resistance to stresses (such as drought and heavy metal stress). Phosphorus and magnesium have a synergistic effect in ATP synthesis. Both phosphorus and molybdenum are essential elements for plants, and they can work together to promote plant growth. Potassium can promote the transport of sucrose, while sucrose serves as an energy source to support the absorption of potassium.

[0020] This invention employs a comprehensive treatment method of crushing, compounding and activation, and laying and rotary tillage to treat coal gangue for desertification control, sand fixation, and soil improvement. Specifically, the coal gangue is graded and classified according to its quality. Large pieces of gangue play a role in windbreak and sand fixation, replacing straw checkerboard and reducing the cost of sand control. Powdered coal gangue, under the action of Bacillus thuringiensis, magnesium sulfate, sucrose, humic acid, and sodium molybdate, improves the sand particles in the desert, accelerating the weathering and degradation of coal gangue into small-particle soil. At the same time, the coal can be degraded into humic acid, and the active products such as phosphatase secreted by Bacillus thuringiensis during its growth and metabolism can catalyze the dissociation reaction of mineral phases in the coal gangue, promoting the slow release of nutrients such as silicon, potassium, and phosphorus, thereby improving the physical and chemical properties of poor-quality sandy soil.

[0021] The above-mentioned technical solution of the present invention is a whole in which each step is closely related and mutually influential, and together they determine the morphological characteristics and performance of the product.

[0022] The above technical solution has the following advantages or beneficial effects:

[0023] 1. This invention uses a crushing process to lay large coal gangue pieces of 10 mm to 100 mm onto the desert surface, which plays a role in windbreak and sand fixation. It can replace straw checkerboard and reduce the cost of sand control. After being mixed and activated with Bacillus thuringiensis and compound additives, coal gangue powder of 0.1 to 10 mm can be weathered and degraded into small particles of soil. At the same time, the coal in the gangue is degraded into humic acid, and nutrients such as silicon, potassium, and phosphorus are released under the action of biological enzymes.

[0024] 2. After implementing sand control and soil improvement using the method of this invention, all key indicators have been optimized and improved: under wind speed conditions of 5.0~12.0 m / s, the sand blocking rate increased from less than 60% to more than 90%; the pH value of desert soil was adjusted from 6.3~7.9 to 6.6~7.4, with significantly enhanced stability; the soil electrical conductivity increased from less than 0.2 dS / m to 0.53~1 dS / m, which is within the suitable range for plant growth; and the soil organic matter content increased from less than 0.78% to more than 1.51%.

[0025] 3. The coal gangue comprehensive treatment process of the present invention is simple to operate, requires no complicated equipment, and has low energy consumption. It can be implemented on-site in desertified areas, achieving both the ecological protection effect of windbreak and sand fixation and the soil remediation goal of improving the physical and chemical properties of sand.

[0026] This invention is applicable to sand control and soil improvement.

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0028] Figure 1The images show the surface morphology of raw coal gangue and the product after activation of coal gangue in step S2 of Example 1 of this invention, wherein: (a) is a scanning electron microscope (SEM) image of raw coal gangue, (b) is a SEM image of activated coal gangue, (c) is an EDS (energy dispersive spectroscopy) spectrum of raw coal gangue, (d) is an EDS spectrum of activated coal gangue, (a1) is a silicon surface morphology image of raw coal gangue, (a2) is an aluminum surface morphology image of raw coal gangue, (a3) ​​is a potassium surface morphology image of raw coal gangue, (a4) is a silicon surface morphology image of raw coal gangue, (a5) is a silicon surface morphology image of raw coal gangue, (a6) is a silicon surface morphology image of raw coal gangue, (a7) is a silicon surface morphology image of raw coal gangue, (a8) is a silicon surface morphology image of raw coal gangue, (a9) is a silicon surface morphology image of raw coal gangue, (a0) is a silicon surface morphology image of raw coal gangue, (a1) is a silicon surface morphology image of raw coal gangue, (a2) is a silicon surface morphology image of raw coal gangue, (a3) ​​is a potassium surface morphology image of raw coal gangue, (a4 ...1) is a silicon surface morphology image of raw coal gangue, (a2) is a silicon surface morphology image of raw coal gangue, (a1) is a silicon surface (a5) is the surface morphology of iron in primary coal gangue, (a6) is the surface morphology of sulfur in primary coal gangue, (b1) is the surface morphology of phosphorus in primary coal gangue, (b2) is the surface morphology of silicon in activated coal gangue, (b3) is the surface morphology of aluminum in activated coal gangue, (b4) is the surface morphology of potassium in activated coal gangue, (b5) is the surface morphology of iron in activated coal gangue, (b6) is the surface morphology of sulfur in activated coal gangue, and (b7) is the surface morphology of phosphorus in activated coal gangue.

[0029] Figure 2 This is a diagram illustrating the leaching mechanism of nutrient elements from coal gangue after activation in step S2 of Example 1 of the present invention.

[0030] Figure 3 XRD patterns of raw coal gangue and activated coal gangue are shown, where: (a) is the XRD pattern of raw coal gangue and (b) is the XRD pattern of activated coal gangue. Detailed Implementation

[0031] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0032] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0033] Example 1

[0034] This embodiment provides an integrated method for sand control and soil improvement based on coal gangue, the process and steps of which are as follows:

[0035] S1. The coal gangue is subjected to closed-circuit coarse crushing and sieved to a particle size of <100mm, and then subjected to medium crushing. After medium crushing, the proportion of 10~100 mm particles in the coal gangue is 20%, the proportion of 1 mm~10 mm particles is 20%, and the proportion of <1 mm particles is 60%, to obtain coal gangue particles and coal gangue powder.

[0036] S2. Mix 10 t of medium-crushed coal gangue with a particle size of 0.1~10 mm with 1 kg of Bacillus thuringiensis (a bacterial powder containing solid culture medium, in which the effective content of live bacteria is 10%). Then add 10 kg of magnesium sulfate, 20 kg of sucrose, 300 kg of humic acid and 2 kg of sodium molybdate, stir well, and ferment at 15℃ for 7 days to obtain a coal gangue mixture.

[0037] S3. Use a rotary tiller to evenly mix the coal gangue mixture with sand at a rate of 30 tons / acre. The tillage depth during mixing should be 250 mm. The rotary tiller used should be a single-shaft type, with the height difference between the left and right blade tips not exceeding 1 cm, and the angle between the drive shaft and the forward direction less than 8 degrees. ° Then, surface paving is carried out, and the coal gangue with a particle size of 10~100 mm from step S1 is evenly spread on the desert surface at a rate of 20 tons / acre, and lightly compacted.

[0038] Example 2

[0039] This embodiment provides an integrated method for sand control and soil improvement based on coal gangue, the process and steps of which are as follows:

[0040] S1. The coal gangue is subjected to closed-circuit coarse crushing and sieved to a particle size of <100mm, and then subjected to medium crushing. After medium crushing, the proportion of 10~100 mm particles in the coal gangue is 25%, the proportion of 1 mm~10 mm particles is 25%, and the proportion of <1 mm particles is 50%, to obtain coal gangue particles and coal gangue powder.

[0041] S2. Mix 30 t of medium-crushed coal gangue with a particle size of 0.1~10 mm with 1 kg of Bacillus thuringiensis (bacterial powder containing solid culture medium, of which the effective content of live bacteria accounts for 20%) evenly; then add 90 kg of magnesium sulfate, 150 kg of sucrose, 2000 kg of humic acid and 15 kg of sodium molybdate, stir evenly, and ferment at 30℃ for 5 days to obtain a coal gangue mixture;

[0042] S3. Use a rotary tiller to evenly mix the coal gangue mixture with sand at a rate of 60 tons / acre. The tillage depth during mixing should be 300 mm. The rotary tiller used should be a single-shaft type, with the height difference between the left and right blade tips not exceeding 1 cm, and the angle between the drive shaft and the forward direction less than 8 degrees. ° Then, surface paving is carried out, and the coal gangue with a particle size of 10~100 mm from step S1 is evenly spread on the desert surface at a rate of 30 tons / acre, and lightly compacted.

[0043] Example 3

[0044] This embodiment provides an integrated method for sand control and soil improvement based on coal gangue, the process and steps of which are as follows:

[0045] S1. The coal gangue is subjected to closed-circuit coarse crushing and sieved to a particle size of <100mm, and then subjected to medium crushing. After medium crushing, the proportion of 10~100 mm particle size in the coal gangue is 30%, the proportion of 1 mm~10 mm particle size is 30%, and the proportion of <1 mm particle size is 40%, to obtain coal gangue particles and coal gangue powder.

[0046] S2. Mix 50 t of medium-crushed coal gangue with a particle size of 0.1~10 mm with 1 kg of Bacillus thuringiensis (a bacterial powder containing solid culture medium, in which the effective content of live bacteria accounts for 40%). Then add 150 kg of magnesium sulfate, 250 kg of sucrose, 4500 kg of humic acid and 25 kg of sodium molybdate, stir evenly, and ferment at 45℃ for 3 days to obtain a coal gangue mixture.

[0047] S3. Use a rotary tiller to evenly mix the coal gangue mixture with sand at a rate of 150 tons / acre. The tillage depth during mixing should be 500 mm. The rotary tiller used should be a single-shaft type, with the height difference between the left and right blade tips not exceeding 1 cm, and the angle between the drive shaft and the forward direction less than 8 degrees. ° Then, surface paving is carried out, and the coal gangue with a particle size of 10~100 mm from step S1 is evenly spread on the desert surface at a rate of 50 tons / acre, and lightly compacted.

[0048] Comparative Example

[0049] To investigate the effects of different activation formulations on the activation degree of coal gangue and the performance of the final product during the preparation process of this invention, the following comparative experiments were conducted. The comparative examples below show coal gangue activated using different methods and then applied to desert soil improvement and sand fixation, as detailed below:

[0050] Comparative Example 1

[0051] This comparative example provides an integrated method for sand control and soil improvement based on coal gangue. The process is similar to that of Example 1, except that no compound additives are added in step S2, namely, magnesium sulfate, sucrose, humic acid and sodium molybdate are added.

[0052] Comparative Example 2

[0053] This comparative example provides an integrated method for sand control and soil improvement based on coal gangue. The process is similar to that of Example 1, except that Bacillus thuringiensis is not added in step S2.

[0054] Comparative Example 3

[0055] This comparative example provides an integrated method for sand control and soil improvement based on coal gangue. The process is similar to that of Example 1, except that in step S2, Bacillus thuringiensis is replaced with Bacillus megaterium.

[0056] Performance testing

[0057] A series of tests were conducted on the soils improved using the methods described in Examples 1-3 and Comparative Examples 1-3 of this invention, as follows:

[0058] Through the two-stage crushing process described in this invention, large coal gangue pieces ranging from 10 mm to 100 mm are laid on the desert surface to prevent wind erosion and stabilize sand, replacing straw checkerboard mats and reducing the cost of sand control. Powdered coal gangue ranging from 0.1 mm to 10 mm, after being activated by a mixture of Bacillus thuringiensis and compound additives, can be weathered and degraded into small-particle soil (such as...). Figure 1 As shown in the figure, at the same time, the coal in the gangue degrades into humic acid, and under the action of biological enzymes, nutrients such as silicon, potassium, and phosphorus are released.

[0059] from Figure 1 (a) and Figure 1 (b) shows a complete and clear surface morphology of the coal gangue, while the untreated coal gangue [ Figure 1 (a)] exhibits a regular and dense surface structure, and after activation treatment according to the present invention, [ Figure 1 (b)], its surface undergoes significant changes: the original mineral phase undergoes selective dissolution, forming numerous irregular pits and porous structures, confirming that the organic acids produced by Bacillus thuringiensis combined with compound additives can achieve directional decomposition and dissolution of the coal gangue mineral phase. Combined with the energy dispersive spectroscopy of activated coal gangue [ Figure 1 (c) and Figure 1 [d] The analysis results showed that the relative contents of Fe and Al on the surface of the activated coal gangue were significantly increased (Al increased from 25.1% to 32.7%, and Fe increased from 0% to 14.7%). This phenomenon is due to the bacterial metabolic process dissolving the insoluble Fe and Al elements in the coal gangue mineral phase and redepositing them on the mineral surface to form hydroxide precipitates. Meanwhile, EDS data showed a significant decrease in the Si and K contents of the activated coal gangue, indicating that some Si and K were released from the mineral lattice and converted into available silicon and readily available potassium that can be absorbed and utilized by plants, entering the solution phase. Furthermore, the EDS distribution map of phosphorus showed that the phosphorus distribution density in the original coal gangue was significantly higher than that in the residue after activation treatment, indicating that some insoluble phosphorus was converted into available phosphorus and dissolved together with Si and K, achieving the activation and release of mineral nutrients. In addition, the non-uniform distribution of pits in Figure 1(b) indicates that Bacillus thuringiensis has a significant selective erosion effect on coal gangue minerals; the bacteria preferentially adsorb onto the surface of the desired mineral phase, producing organic acids to decompose these minerals (such as...). Figure 2 As shown in the figure, this effectively activates the nutrient elements in the coal gangue.

[0060] Depend on Figure 3 (a) and Figure 3XRD analysis of (b) shows that in the coal gangue activated by Bacillus thuringiensis strain combined with compound additives, the characteristic peaks of quartz and kaolinite did not change significantly, while those of P-containing triclinic calcium phosphate (CaHPO4) and K and Si-containing muscovite [KAl2(AlSi3O4)] showed significant changes. 10 The diffraction peak intensities of [(OH)2] were all weakened or even disappeared, indicating that these phosphorus and potassium-containing minerals were dissolved during the treatment with Bacillus thuringiensis and compound additives. Iron mica [KFe3FeSi3O] 10 The diffraction peak of [(OH)2] also weakened, which also indicates that Bacillus thuringiensis can dissolve ferrous iron to obtain energy, and the organic acids produced by its metabolism can simultaneously promote the solubilization of K and Si.

[0061] The composition of the soil improved using the methods described in Example 1 and Comparative Examples 1-2 of this invention was analyzed, and the specific results are shown in Table 1:

[0062] Table 1. Soil composition analysis after treating coal gangue with different activation methods.

[0063]

[0064] As can be seen from the table above, after soil improvement using the coal gangue activation method of Example 1 of this invention, the contents of available phosphorus, available potassium, and available silicon all increased, and were higher than those of Comparative Examples 1 and 2. This is because the combined action of microorganisms and compound additives can improve microbial metabolism and bioavailability, further releasing nutrients such as silicon, phosphorus, and potassium from the coal gangue. Comparative Example 1 relies on a single microorganism for nutrient dissolution, and its biological activity is easily inhibited, leading to insufficient secretion of metabolites, and thus failing to effectively dissolve nutrients from the coal gangue. Comparative Example 2 relies solely on the chemical action of the compound additives to dissolve nutrients, achieving rapid short-term release, but it cannot improve soil structure, regulate the soil environment, or achieve long-term supply. Therefore, compared with Example 1, Comparative Examples 1 and 2 all showed significant deficiencies in the dissolution of available phosphorus, available potassium, and available silicon. This result further confirms that the combined action of microorganisms and compound additives can more effectively improve the content of nutrients in the soil.

[0065] The soil improved using the methods described in Example 2 and Comparative Examples 1-2 of this invention was used for pot planting. The plants selected were Leymus chinensis and Leymus chinensis, which are difficult to grow in the Ordos Desert region. The specific experimental setup is as follows:

[0066] Take 500 g each of the original soil, Comparative Example 1, Comparative Example 2, and the soil obtained in Example 2. Sow 100 seeds of Leymus chinensis and Leymus chinensis into each of the four soil samples and transplant them into pots. Spray with an appropriate amount of distilled water to maintain a soil moisture content between 10% and 15%. Place the samples in a 28℃ constant temperature incubator, turning the soil and replenishing water periodically to keep the samples moist. Observe their growth. Specific results are shown in Table 2.

[0067] Table 2. Plant growth in soil treated with different activation methods after improving coal gangue.

[0068]

[0069] As can be seen from the table above, after the soil was improved by the coal gangue activation method of Example 2 of this invention, the germination rate and plant height of the planted sheepgrass and crested wheatgrass were higher than those of Comparative Examples 1 and 2 and the original soil. This indicates that after the coal gangue treated with microorganisms and compound additives is applied to sandy soil, it can significantly increase the content of nutrients in the soil through a coupling mechanism of biological regulation and chemical synergy, thereby effectively promoting the germination and growth of plants. In contrast, Comparative Example 1 relied solely on the activation effect of a single microorganism, and the organic acids produced by microbial metabolism were insufficient to effectively destroy the mineral structure, resulting in limited dissolution efficiency of elements such as phosphorus, potassium, and silicon. Comparative Example 2 only added compound additives, which, although able to release nutrients through chemical action, could not maintain a long-term supply of nutrients, resulting in lower germination rates and plant heights of the planted sheepgrass and crested wheatgrass compared to Example 2.

[0070] The slow-release effect of soil modified using the method described in Example 3 of this invention was tested, and the specific results are shown in Table 3:

[0071] Table 3. Slow-release effect of nutrients in soil

[0072]

[0073] As shown in the table above, after soil improvement using the method described in Example 3, microorganisms grew and metabolized rapidly in the first 24 hours, resulting in high nutrient dissolution rates. Available phosphorus increased from 78.5 mg / kg to 355.6 mg / kg, available potassium from 433.5 mg / kg to 1427.3 mg / kg, and available silicon from 217.0 mg / kg to 612.4 mg / kg. After 24 hours, the dissolution rate decreased significantly but continued to increase, indicating that the combined action of microorganisms and compound additives enhanced microbial activity, promoted their growth and metabolism, secreted more organic acids, further decomposed insoluble minerals in coal gangue, and slowly increased the dissolution of nutrients, thus achieving a slow-release effect. The combined action of microorganisms and compound additives achieved a long-term slow-release effect of nutrients, and also demonstrated that the combined action of microorganisms (Bacillus thuringiensis) and compound additives can significantly improve soil nutrient availability.

[0074] The nutrient components of coal gangue activated using the activation methods described in Example 1 and Comparative Example 3 of this invention were analyzed, and the specific results are shown in Table 4:

[0075] Table 4. Changes in nutrient composition before and after activation of coal gangue by different microorganisms.

[0076]

[0077] As can be seen from the table above, the content of key nutrients such as silicon (Si), phosphorus (P), and potassium (K) in primary coal gangue is relatively low. However, when treated with Bacillus thuringiensis and compound additives, the dissolution of available phosphorus and readily available potassium in coal gangue was significantly increased compared to Comparative Example 3, while the dissolution of available silicon decreased slightly. This result indicates that the combined effect of Bacillus thuringiensis and compound additives can effectively promote the release of phosphorus and potassium in coal gangue, but it did not show a significant promoting effect on the dissolution of silicon. Silicon is a beneficial element for plant growth but not an essential element. Although the silicon dissolution in Example 1 was slightly lower than that in Comparative Example 3, its phosphorus and potassium dissolution was significantly increased, meeting the needs of plant growth. If the dissolution of silicon is pursued alone while the supply of macronutrients such as phosphorus and potassium is ignored, it will inhibit plant growth due to nutrient imbalance.

[0078] Using the activated coal gangue from Example 1 of this invention, after completing the integrated desertification control treatment of sand fixation and soil improvement, the sand-blocking rate increased from less than 60% to over 90% under wind speeds of 5.0-12.0 m / s. The pH value of the desert soil varied from 6.3 to 7.9, while the pH value of the desert soil improved with coal gangue ranged from 6.6 to 7.4. This is because the organic acids or ammonia produced by Bacillus thuringiensis metabolism can buffer the pH value changes of the soil, thereby maintaining the relative stability of the soil pH value. The electrical conductivity of the desert soil was generally below 0.2 dS / m, while the electrical conductivity of the desert soil improved with coal gangue was greater than 0.530 dS / m and less than 1 dS / m, which is within the range suitable for plant growth. The organic matter content of the improved desert soil increased from less than 0.78% to over 1.51%. Furthermore, the activated coal gangue from step S2 of this invention was mixed with desert soil at a rate of 30 tons / acre, and the soil was tested on the 10th and 60th days after mixing. The results showed that the microbial α-diversity of the desert soil changed significantly, and the number of microbial species increased significantly. The specific results are shown in Table 5.

[0079] Table 5 Soil microbial α-diversity

[0080]

[0081] As shown in the table above, the α-diversity of desert soil microbial communities changed significantly with the extension of coal gangue activation time. On day 10 of activation, soil microbial species richness increased significantly. Even after 60 days of continuous activation, the microbial community maintained a high level of diversity. These results indicate that the amendment has a significant, sustained, and stable effect on improving desert soil microbial communities.

[0082] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An integrated method for sand control and soil improvement based on coal gangue, characterized in that, Follow these steps in sequence: S1. The coal gangue is subjected to closed-circuit coarse crushing and sieved to a particle size of <100 mm, and then subjected to medium crushing to obtain coal gangue particles and coal gangue powder. S2. After the above-mentioned medium-crushed coal gangue with a particle size of 0.1~10 mm is mixed evenly with Bacillus thuringiensis, compound additives are added, and after stirring evenly, fermentation is carried out to obtain a coal gangue mixture. The compound additive consists of magnesium sulfate, sucrose, humic acid and sodium molybdate; The mass ratio of the coal gangue with a particle size of 0.1~10 mm to Bacillus thuringiensis, magnesium sulfate, sucrose, humic acid and sodium molybdate is (10000~50000):1:(10~150):(20~250):(300~4500):(2~25). The Bacillus thuringiensis is a bacterial powder containing a solid culture medium, wherein the effective content of live bacteria is 10-40%. The fermentation temperature is 15~45℃, and the time is 3~7 days; S3. Use a rotary tiller to mix the coal gangue mixture with sand evenly, and the rotary tillage depth is 250-500 mm during mixing; then spread the coal gangue with a particle size of 10-100 mm from step S1 evenly on the desert surface at a rate of 20-50 tons / acre, and lightly compact it.

2. The integrated method for sand fixation and soil improvement based on coal gangue according to claim 1, characterized in that, In step S1, the proportion of 10-100 mm particles in the medium-crushed coal gangue is 20%-30%, the proportion of 1 mm-10 mm particles is 20%-30%, and the proportion of <1 mm particles is 40%-60%.

3. The integrated method for sand fixation and soil improvement based on coal gangue according to claim 1, characterized in that, In step S3, when the coal gangue mixture is mixed with sand, the coal gangue mixture is mixed with sand at a rate of 30-150 tons per acre.

4. The integrated method for sand fixation and soil improvement based on coal gangue according to claim 1, characterized in that, In step S3, the rotary cultivator used in the rotary tillage is single-shaft type, the height difference between left and right blade tips is not more than 1 cm, and the angle between the transmission shaft and the advancing direction is less than 8 ° .

Images