A method for preparing a soil conditioner based on coal gangue infrared activation

Abstract

The application discloses a kind of based on coal gangue infrared activation preparation soil conditioner's method, comprising the following steps: S1.preparation activated coal gangue;S2.mixed with slow-release fertilizer, modified zeolite, extrusion granulation, obtain basic granule, long-acting compound microbial agent is diluted into microbial agent suspension with deionized water, adopt low-temperature spray way and spray on the surface of basic granule, low-temperature drying, obtain core material;S3.mixed with kaolin, humic acid, calcium hydrogen phosphate, sodium alginate and water, obtain coating slurry, coating slurry is coated on core material, obtain shell-core material;S4.mixed with polyvinyl alcohol, talcum powder, composite additive and water, obtain outer coating slurry, outer coating slurry is coated on shell-core material, obtain soil conditioner.The application realizes waste resource utilization by infrared activation treatment to coal gangue, then preparation into high value-added soil conditioner.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil improver, in particular to a method for preparing soil improver based on coal gangue infrared activation. BACKGROUND

[0002] Desertification is a major ecological problem affecting human survival and development. Desert land reclamation, as an important way to alleviate the shortage of arable land resources and achieve ecological restoration, has received high attention from the state and society.

[0003] Desert soil has unique physicochemical properties due to long-term exposure to arid environments. Its soil particles are coarse, mainly composed of quartz sand, lacking clay and silt particles, resulting in loose soil structure, high porosity but low effective porosity. This structural feature makes desert soil have poor water retention capacity, and precipitation or irrigation water quickly penetrates and is lost, failing to provide sustained water supply for plants. At the same time, desert soil has extremely low organic matter content, usually less than 0.1%, and is severely lacking in macronutrients such as nitrogen, phosphorus, and potassium, as well as micronutrients such as iron, zinc, and manganese, making the soil extremely poor in fertility. In addition, the microbial activity in desert soil is extremely low, and there is a lack of effective biological circulation system, making it difficult to form a stable soil ecological environment. Now, through technical development, these deserts are improved into clay soil, the newly formed deserts are restored, the desertification process is reversed, and further planting effects that are compatible with water and fertilizer resources are achieved, which is a goal that people strive for.

[0004] Traditional desert improvement techniques have many limitations. Although the guest soil improvement has obvious effect, the transportation cost is high, and the economy is poor in large-area application. The function of chemical improver is relatively single, mainly solving a certain problem, such as pure water retention or fertilizer supply, which is difficult to comprehensively improve the comprehensive performance of desert soil, and the effective period is short, which needs frequent application. Although the biological improvement method is environmentally friendly, it is slow-acting and has poor adaptability in extreme desert environments, making it difficult to quickly establish a stable ecological system.

[0005] At the same time, coal gangue produced by coal mining is accumulated in large quantities, which not only occupies land resources but also may cause environmental pollution. Coal gangue contains silicon, aluminum, calcium, magnesium, potassium, iron and various trace elements, and can be used as a source of mineral substances for soil improvement after proper treatment. How to convert these coal gangues into valuable soil improvement materials not only solves the problem of waste disposal but also provides an economically viable source of raw materials for desert improvement, which is a technical problem that needs to be solved urgently.

[0006] Therefore, it is urgent to develop a soil improver specially suitable for desert land reclamation, which should have the characteristics of water and fertilizer retention, comprehensive nutrition, long effective period, strong environmental adaptability, etc., and at the same time make full use of industrial waste to realize the recycling of resources, and provide effective technical support for the ecological restoration and agricultural development in desert areas. Summary of the Invention

[0007] Based on the problems existing in the background technology, the present invention provides a method for preparing soil conditioner based on infrared activation of coal gangue. The prepared soil conditioner can achieve water and fertilizer retention, provide a variety of mineral nutrients required for plant growth, and solve the soil fertility problem in the early stage of desert land reclamation.

[0008] This invention is implemented through the following technical solutions:

[0009] A method for preparing soil conditioner based on infrared activation of coal gangue includes the following steps:

[0010] S1. Pretreatment and activation of coal gangue to obtain activated coal gangue;

[0011] S2. Mix activated coal gangue with slow-release fertilizer and modified zeolite, then add water accounting for 30-45% of the weight of the mixture, and continue mixing until the material is in loose granular form. Granulate it by extrusion granulation, dry it to obtain basic particles, dilute the long-acting compound bacterial agent with deionized water to form a bacterial agent suspension, and spray it evenly on the surface of the basic particles using a low-temperature spraying method. Dry it at low temperature to obtain the core material.

[0012] S3. Activated coal gangue is mixed with kaolin, humic acid, dicalcium phosphate, sodium alginate and water to obtain a coating slurry with a solid content of 35-45%. Fluidized bed coating technology is used to coat the core material with the coating slurry to obtain the core-shell material.

[0013] S4. Modified activated coal gangue is mixed with polyvinyl alcohol, talc, composite additives and water to obtain an outer coating slurry with a solid content of 30-40%. Fluidized bed coating technology is used to coat the outer coating slurry onto the core material to obtain a soil conditioner.

[0014] Further, the pretreatment and activation treatment of coal gangue in step S1 are specifically as follows: the collected coal gangue is crushed to a particle size of less than 5 mm, then put into a ball mill to be pulverized to a particle size of less than 200 mesh, magnetic separation is used to remove ferromagnetic impurities, and the coal gangue is dried to constant weight; the dried coal gangue is put into a high-temperature furnace and activated by infrared calcination at 700-900℃ for 1-2 hours, and then naturally cooled to room temperature to obtain activated coal gangue.

[0015] Furthermore, in step S2, the mass ratio of activated coal gangue, slow-release fertilizer, modified zeolite and long-acting compound microbial agent is (60-80):(20-30):(10-20):(2-5).

[0016] Furthermore, the slow-release fertilizer in step S2 is NPK 15-15-15 compound fertilizer;

[0017] The modified zeolite is specifically obtained by treating it with a 2-4% hydrochloric acid solution for 2-4 hours, rinsing it until neutral, then soaking it in a 5% sodium chloride solution for 2-4 hours, and finally drying it.

[0018] The long-acting compound microbial agent includes Bacillus megaterium, Bacillus pumilus, Bacillus subtilis, and Bacillus licheniformis. The preparation method specifically involves: activating and culturing Bacillus megaterium, Bacillus pumilus, Bacillus subtilis, and Bacillus licheniformis; collecting the bacterial cells by centrifugation; preparing a mixed bacterial suspension at a mass ratio of 3:1.5:2:2.5; and adjusting the bacterial concentration to 1×10⁻⁶. 9 Take CFU / mL, mix the same volume of 2wt% sodium alginate solution as the mixed bacterial suspension, add 2wt% calcium chloride solution to form microcapsules, transfer the microcapsules to 1wt% chitosan solution with a pH of 5.5, soak at room temperature for 30 min, freeze dry under vacuum for 24 h, and add 5% sucrose as a protectant to obtain the long-acting compound bacterial agent.

[0019] Furthermore, the diameter of the core material in step S2 is 4-6 mm.

[0020] Further, in step S3, the mass ratio of activated coal gangue, kaolin, humic acid, dicalcium phosphate, and sodium alginate is (40-60):(20-35):(5-15):(8-18):(3-8);

[0021] The fluidized bed coating in step S4 specifically involves suspending the core material in a fluidized bed, uniformly spraying the coating slurry through a nozzle, coating in 3-5 layers, and finally coating a thickness of 0.3-0.6 mm.

[0022] Further, in step S4, the mass ratio of modified activated coal gangue to polyvinyl alcohol, talc powder, and composite additives is (50-70):(8-18):(10-15):(2-5);

[0023] Among them, the modified activated coal gangue is activated coal gangue treated with 3% by mass of silane coupling agent KH560;

[0024] The fluidized bed coating in step S4 specifically involves suspending the core and shell materials in a fluidized bed, uniformly spraying the outer coating slurry onto the surface of the core and shell materials through a nozzle, coating in 2-3 times, with a final coating thickness of 0.1-0.3 mm.

[0025] Furthermore, the composite additive in step S4 includes calcium hydroxide and magnesium oxide in a mass ratio of (5-8):(2-3).

[0026] The present invention also discloses the application of the prepared soil conditioner based on infrared activation of coal gangue in desert land reclamation, wherein the amount of the soil conditioner used is 800-1500 kg / mu.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention utilizes infrared activation treatment of industrial waste coal gangue to prepare a high-value-added soil conditioner, achieving waste resource utilization. This not only reduces the accumulation of industrial solid waste and environmental pollution but also provides an economically feasible source of raw materials for desert soil improvement. The activation treatment can disrupt the original mineral structure, releasing essential mineral nutrients for plants such as silicon, aluminum, magnesium, and potassium, while simultaneously enhancing the material's adsorption performance and ion exchange capacity.

[0029] 2. The three-layer soil conditioner prepared in this invention possesses excellent water and fertilizer retention capabilities. The core slow-release fertilizer provides plants with a continuous and stable supply of nitrogen, phosphorus, and potassium nutrients; modified zeolite enhances fertilizer retention capacity; and the long-acting compound microbial agent helps establish a healthy soil microbial ecosystem, promoting organic matter decomposition and nutrient cycling. The middle layer of kaolin and humic acid significantly improves the soil's water-holding capacity and cation exchange capacity, addressing the problems of loose sandy soil structure and poor water retention. The outer coating design enables controlled release of nutrients, preventing the rapid loss of traditional fertilizers in desert environments.

[0030] 3. The synergistic effect of the composite additives and long-acting compound microbial agents in the soil conditioner of this invention is beneficial to improving the physicochemical properties of coal gangue carriers. The composite additives provide Ca... 2+ and Mg 2+ Under the influence of organic acids and extracellular polymers secreted by microorganisms, surface complexation and ion exchange reactions occur with the aluminosilicates on the surface of coal gangue, forming amorphous calcium silicate gels, magnesium carbonate, or magnesium silicate colloids and other amorphous products. This enhances the cementing and stability between coal gangue particles, thereby gradually altering their physicochemical properties. Over many years, the coal gangue particles gradually break down and disperse physically, mixing with surrounding soil particles. Chemically, the cementitious substances and complexes formed on the surface combine with clay minerals and organic matter in the soil, participating in the formation of soil aggregates. Although the main mineral composition of coal gangue itself remains stable at room temperature, compatibility with the soil system is achieved through changes in surface properties.

[0031] 4. The entire preparation process of this invention adopts mature granulation and coating technologies, ensuring stable and controllable product quality and facilitating mechanized application. This soil conditioner not only rapidly improves the physical and chemical properties of desert soils and establishes basic soil fertility, but also creates favorable conditions for subsequent vegetation establishment and ecosystem restoration, providing a new technical approach for desertification control and land greening. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0033] In the embodiments and comparative examples of the present invention:

[0034] The specific preparation method of activated coal gangue is as follows: the collected coal gangue is crushed to a particle size of less than 5 mm, then put into a ball mill to be pulverized to a particle size of less than 200 mesh, magnetic separation is used to remove ferromagnetic impurities, and the coal gangue is dried to constant weight; the dried coal gangue is put into a high-temperature furnace and activated by infrared calcination at 800℃ for 1.5 h, and then naturally cooled to room temperature to obtain activated coal gangue.

[0035] The slow-release fertilizer is NPK 15-15-15 compound fertilizer.

[0036] The specific preparation method of modified zeolite is as follows: zeolite is treated with a 3% hydrochloric acid solution for 3 hours, rinsed until neutral, and then soaked in a 5% sodium chloride solution for 3 hours. After drying, it is obtained.

[0037] The long-acting compound microbial agent includes Bacillus megaterium, Bacillus pumilus, Bacillus subtilis, and Bacillus licheniformis. The preparation method specifically involves: activating and culturing Bacillus megaterium, Bacillus pumilus, Bacillus subtilis, and Bacillus licheniformis; collecting the bacterial cells by centrifugation; preparing a mixed bacterial suspension at a mass ratio of 3:1.5:2:2.5; and adjusting the bacterial concentration to 1×10⁻⁶. 9 Take CFU / mL, mix the same volume of 2wt% sodium alginate solution as the mixed bacterial suspension, add 2wt% calcium chloride solution to form microcapsules, transfer the microcapsules to 1wt% chitosan solution with a pH of 5.5, soak at room temperature for 30 min, freeze dry under vacuum for 24 h, and add 5% sucrose as a protectant to obtain the long-acting compound bacterial agent.

[0038] The specific preparation method of modified activated coal gangue is as follows: activated coal gangue treated with 3% by mass of silane coupling agent KH560.

[0039] The composite additives include calcium hydroxide and magnesium oxide in a mass ratio of 6.5:2.5.

[0040] Example 1

[0041] A method for preparing soil conditioner based on infrared activation of coal gangue includes the following steps:

[0042] S1. Prepare raw materials according to the mass ratio of activated coal gangue, slow-release fertilizer, modified zeolite and long-acting compound microbial agent of 70:25:15:3. Mix activated coal gangue, slow-release fertilizer and modified zeolite, then add water accounting for 40% of the weight of the mixture, and continue mixing until the material is in loose granular form. Granulate by extrusion granulation machine, dry to obtain basic particles. Dilute the long-acting compound microbial agent with deionized water to form a microbial agent suspension, and spray it evenly on the surface of the basic particles by low temperature spraying. Dry at low temperature to obtain core material with a diameter of 5mm.

[0043] S2. Activated coal gangue, kaolin, humic acid, dicalcium phosphate, sodium alginate and water are mixed in a mass ratio of 50:27:10:13:5 to prepare a coating slurry with a solid content of 40%. Fluidized bed coating technology is used to suspend the core material in a fluidized bed. The coating slurry is evenly sprayed onto the core material through a nozzle. The coating is performed in 4 layers, and the final coating thickness is 0.5 mm to obtain the core material.

[0044] S3. Modified activated coal gangue is mixed with polyvinyl alcohol, talc powder and composite additives at a mass ratio of 60:13:12:3. Water is added to prepare an outer coating slurry with a solid content of 35%. Fluidized bed coating technology is used to suspend the core material in a fluidized bed. The outer coating slurry is evenly sprayed onto the surface of the core material through a nozzle. The coating is done in 3 layers, and the final coating thickness is 0.2 mm, thus obtaining a soil conditioner.

[0045] Example 2

[0046] A method for preparing soil conditioner based on infrared activation of coal gangue includes the following steps:

[0047] S1. Prepare raw materials according to the mass ratio of activated coal gangue, slow-release fertilizer, modified zeolite and long-acting compound microbial agent as 68:30:12:2.5. Mix activated coal gangue, slow-release fertilizer and modified zeolite, then add water accounting for 40% of the weight of the mixture, and continue mixing until the material is in loose granular form. Granulate by extrusion granulation machine, dry to obtain basic particles. Dilute the long-acting compound microbial agent with deionized water to form a microbial agent suspension, and spray it evenly on the surface of the basic particles by low temperature spraying. Dry at low temperature to obtain core material with a diameter of 6mm.

[0048] S2. Activated coal gangue, kaolin, humic acid, dicalcium phosphate, sodium alginate and water are mixed in a mass ratio of 40:35:12:8:5 to prepare a coating slurry with a solid content of 40%. Fluidized bed coating technology is used to suspend the core material in a fluidized bed. The coating slurry is evenly sprayed onto the core material through a nozzle. The coating is performed in 3 layers, and the final coating thickness is 0.5 mm to obtain the core-shell material.

[0049] S3. Modified activated coal gangue is mixed with polyvinyl alcohol, talc powder and composite additives at a mass ratio of 50:15:10:3.5. Water is added to prepare an outer coating slurry with a solid content of 30%. Fluidized bed coating technology is used to suspend the core material in a fluidized bed. The outer coating slurry is evenly sprayed onto the surface of the core material through a nozzle. The coating is done in two stages, and the final coating thickness is 0.3 mm, thus obtaining a soil conditioner.

[0050] Comparative Example 1

[0051] Soil conditioner was prepared using unactivated coal gangue, i.e., coal gangue was only crushed, ground, demagnetized and dried, with the remaining process conditions the same as in Example 1.

[0052] Comparative Example 2

[0053] A single-structure soil conditioner is made by simply mixing activated coal gangue and slow-release fertilizer at a mass ratio of 80:20 and granulating them without any coating treatment.

[0054] Comparative Example 3

[0055] The core material was prepared according to the method in Example 1, with only the middle layer coated and no outer layer coated, forming a two-layer soil conditioner.

[0056] Comparative Example 4

[0057] The core material was prepared according to the method in Example 1. The order of the coating layers was reversed. The inner layer was coated with modified activated coal gangue slurry, and the outer layer was coated with activated coal gangue slurry, thus forming a soil conditioner with a reverse coating structure.

[0058] Experimental Example 1

[0059] The soil conditioners prepared in the examples and comparative examples were tested for water retention rate and fertilizer retention rate.

[0060] Water retention rate test method: Take 5000g of soil conditioner prepared in the examples and comparative examples respectively, add 1500g of water to each, mix evenly, seal and let stand for 1 day, then transfer to material trays, spread and compact into a 50-55mm thick material layer, and place in a constant temperature and humidity sealed room at 25℃ and 30% relative humidity for 10 days. The water retention rate is determined according to the weight loss of each material. The test results are shown in Table 1.

[0061] Fertilizer retention rate test method: Take 5000g of soil conditioner prepared in the examples and comparative examples respectively, add 2000g of water to each, mix well and seal, and place at 25℃ for 10 days. Then, transfer them into material buckets, add 5000g of water to each, and slurry for 10 minutes. Take slurry samples to determine the phosphorus and potassium dissolution of each material. Then, calculate the phosphorus and potassium dissolution rate according to the total amount of phosphorus and potassium in each agent. Take the average value of each, and use 100% minus the average value as the fertilizer retention rate. The test results are shown in Table 1.

[0062] Table 1

[0063] Group Water retention rate (%) Fertilizer retention rate (%) Example 1 87.3 92.6 Example 2 85.8 91.2 Comparative Example 1 72.4 78.5 Comparative Example 2 64.7 69.3 Comparative Example 3 79.2 84.7 Comparative Example 4 68.9 73.8

[0064] As shown in Table 1, the three-layer coated soil conditioners prepared in Examples 1 and 2 were significantly superior to the comparative examples in terms of water retention and fertilizer retention. In Comparative Example 1, due to the lack of activation treatment, the original mineral structure of the coal gangue was not destroyed, resulting in insufficient release of active components and significantly inadequate water and fertilizer retention. Comparative Example 2, with its single structure and lack of coating design, experienced rapid loss of nutrients and exhibited the worst water and fertilizer retention performance. Comparative Example 3, with its two-layer structure consisting only of a middle coating and lacking an outer controlled-release design, suffered from insufficient nutrient release precision, thus limiting its performance. Comparative Example 4, by adjusting the middle and outer coatings, disrupted the rational sequence of nutrient release, resulting in poor performance.

[0065] Experimental Example 2

[0066] The soil conditioners prepared in the examples and comparative examples were used in field planting experiments.

[0067] The experimental plot was a desertified soil test field in Inner Mongolia, with soil organic matter content of 2.08-2.25%, sand content of 68.9-74.3%, physical clay particles with a diameter of less than 0.01 mm of 4.6-5.5%, and physical clay particles with a diameter of less than 0.001 mm of 0.3-1.7%.

[0068] The soil conditioners prepared in the examples and comparative examples were used in the experimental field at an application rate of 1000 kg / mu. Three replicates were set up for each soil conditioner, with each replicate measuring 5m × 5m. A blank control group (CK) was also set up.

[0069] After applying the soil conditioner, each plot was planted with the same size ryegrass and the same field management practices were adopted. The first harvest was conducted 60 days after planting, followed by harvesting every 30 days for a total of three harvests. The fresh weight of the forage was recorded after each harvest, and the average value was calculated. The harvested forage was then dried, and the dry weight was recorded and averaged. Simultaneously, after the third harvest, a 1m² section of forage was selected from each plot. 2The above-ground parts were cleaned up, and the roots were dug to a depth of 30cm. The roots were then sieved, dried, and the average value was calculated and recorded as the dry weight of the roots. The test results are shown in Table 2.

[0070] Table 2

[0071] Group Fresh weight of forage (kg) Dry weight of forage (kg) Root dry weight (g / m 2 ) Example 1 195.6 68.2 152.4 Example 2 188.3 65.7 148.9 Comparative Example 1 89.2 22.8 82.1 Comparative Example 2 76.5 18.5 71.3 Comparative Example 3 135.4 44.8 112.3 Comparative Example 4 82.7 20.9 76.8 CK 42.3 9.8 56.2

[0072] Table 2 shows that the three-layered soil conditioners prepared in Examples 1 and 2 performed excellently in the forage planting experiment. Compared with the blank control group, Example 1 showed a 362.4% increase in fresh forage weight and, more importantly, a 171.2% increase in root dry weight. This indicates that the improved soil not only promotes rapid plant growth but also supports the establishment of a strong root system, which is crucial for the long-term success of desert land reclamation. The field test results are basically consistent with the laboratory water and fertilizer retention performance test results. The two-layered structure of Comparative Example 3 revealed insufficient and sustained nutrient release in long-term field trials, resulting in insufficient fertilizer effect in the later stages. These findings further demonstrate the necessity of the three-layered coating design and infrared activation treatment of this invention.

[0073] Finally, it should be noted that the above embodiments are merely illustrative of several implementations of the present invention and are not intended to limit the scope of the invention. For those skilled in the art, any modifications, equivalent substitutions, or improvements made without departing from the concept of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing soil conditioner based on infrared activation of coal gangue, characterized in that, Includes the following steps: S1. Pretreatment and activation of coal gangue: The collected coal gangue is crushed to a particle size of less than 5 mm, then put into a ball mill to be pulverized to a particle size of less than 200 mesh, magnetic separation is used to remove ferromagnetic impurities, and the coal gangue is dried to constant weight. The dried coal gangue is then placed in a high-temperature furnace and activated by infrared calcination at 700-900℃ for 1-2 hours, and then naturally cooled to room temperature to obtain activated coal gangue. S2. Mix activated coal gangue with slow-release fertilizer and modified zeolite, then add water accounting for 30-45% of the weight of the mixture, and continue mixing until the material is in loose granular form. Granulate it by extrusion granulation, dry it to obtain basic particles, dilute the long-acting compound bacterial agent with deionized water to form a bacterial agent suspension, and spray it evenly on the surface of the basic particles using a low-temperature spraying method. Dry it at low temperature to obtain the core material. S3. Activated coal gangue is mixed with kaolin, humic acid, dicalcium phosphate, sodium alginate and water to obtain a coating slurry with a solid content of 35-45%. Fluidized bed coating technology is used to coat the core material with the coating slurry to obtain the core-shell material. S4. Modified activated coal gangue is mixed with polyvinyl alcohol, talc, composite additives and water to obtain an outer coating slurry with a solid content of 30-40%. Fluidized bed coating technology is used to coat the outer coating slurry onto the core material to obtain a soil conditioner. In step S2, the modified zeolite is specifically treated with a 2-4% hydrochloric acid solution for 2-4 hours, rinsed until neutral, and then soaked in a 5% sodium chloride solution for 2-4 hours before drying. The long-acting compound microbial agent in step S2 includes Bacillus megaterium, Bacillus pumilus, Bacillus subtilis, and Bacillus licheniformis. The preparation method specifically involves: activating and culturing Bacillus megaterium, Bacillus pumilus, Bacillus subtilis, and Bacillus licheniformis; collecting the bacterial cells by centrifugation; preparing a mixed bacterial suspension at a mass ratio of 3:1.5:2:2.5; and adjusting the bacterial concentration to 1×10⁻⁶. 9 CFU / mL, take an equal volume of 2wt% sodium alginate solution and mix it evenly with the mixed bacterial suspension, add 2wt% calcium chloride solution to form microcapsules, transfer the formed microcapsules to 1wt% chitosan solution with a pH of 5.5, soak at room temperature for 30 min, freeze dry under vacuum for 24 h, add 5% sucrose as a protectant, and the long-acting compound bacterial agent is obtained; In step S4, the modified activated coal gangue is activated coal gangue treated with 3% by mass of silane coupling agent KH560. The composite additive in step S4 includes calcium hydroxide and magnesium oxide in a mass ratio of (5-8):(2-3).

2. The method according to claim 1, characterized in that, In step S2, the mass ratio of activated coal gangue, slow-release fertilizer, modified zeolite and long-acting compound microbial agent is (60-80):(20-30):(10-20):(2-5).

3. The method according to claim 1, characterized in that, The slow-release fertilizer in step S2 is NPK 15-15-15 compound fertilizer.

4. The method according to claim 1, characterized in that, The diameter of the core material in step S2 is 4-6 mm.

5. The method according to claim 1, characterized in that, In step S3, the mass ratio of activated coal gangue, kaolin, humic acid, dicalcium phosphate, and sodium alginate is (40-60):(20-35):(5-15):(8-18):(3-8); The fluidized bed coating in step S3 specifically involves suspending the core material in a fluidized bed, uniformly spraying the coating slurry through a nozzle, coating in 3-5 layers, and finally coating a thickness of 0.3-0.6 mm.

6. The method according to claim 1, characterized in that, In step S4, the mass ratio of modified activated coal gangue to polyvinyl alcohol, talc powder, and composite additives is (50-70):(8-18):(10-15):(2-5); The fluidized bed coating in step S4 specifically involves suspending the core and shell materials in a fluidized bed, uniformly spraying the outer coating slurry onto the surface of the core and shell materials through a nozzle, coating in 2-3 times, with a final coating thickness of 0.1-0.3 mm.

7. A soil conditioner prepared by infrared activation of coal gangue, as described in any one of claims 1-6.

8. The application of a soil conditioner prepared by infrared activation of coal gangue as described in claim 7 in desert land reclamation, characterized in that, The application rate of the soil conditioner is 800-1500 kg / mu.