A soil conditioner for prairie restoration and a method of preparing the same

Abstract

The application provides a soil conditioner for grassland restoration and a preparation method thereof, and the preparation method comprises the following steps: (1) mixing fly ash, calcium-containing substances and alkali liquor uniformly, and then performing hydrothermal reaction, and performing solid-liquid separation to obtain a solid product; (2) uniformly mixing the solid product obtained in the step (1) with organic substances and disintegrating agents, and performing granulation on the obtained mixture and a solvent to obtain the soil conditioner. The soil conditioner prepared by the application is granular, and is convenient for transportation, storage and mechanized application. After being applied to soil, the soil conditioner can be quickly scattered and powdered when meeting water, so as to facilitate the absorption of plants and the improvement of soil. The soil conditioner can not only supplement the missing trace elements and organic matter of soil, but also improve the water holding and water retaining capacity of soil. The application mainly uses fly ash as raw material, and can not only solve the environmental problems caused by fly ash accumulation, but also accelerate the recovery process of grassland soil, and has good economic value and social significance.

Description

Technical Field

[0001] This invention belongs to the field of ecological restoration and relates to a soil conditioner for grassland restoration and its preparation method. Background Technology

[0002] Grassland degradation (grassland vegetation decline) is a type of land degradation and one of the main manifestations of desertification. Grassland degradation is primarily caused by human activities and adverse natural factors, including soil material loss and deterioration of physical and chemical properties, loss of high-quality forage grasses, and decline in economic productivity. Surveys indicate that over 90% of natural grasslands are currently degraded to varying degrees, and this degradation is accelerating at a rate of 2% per year on usable grassland area. The annual reduction in grassland area reaches 650,000 to 700,000 hectares, with moderately to severely degraded grasslands accounting for over 50% of the total area. Grassland degradation leads to the destruction of soil aggregate structure, decreased water retention capacity, and a lack of micronutrients and organic matter, further resulting in a reduction in biodiversity.

[0003] Countries around the world have long been working to address grassland degradation, but the damage to grassland ecosystems is severe, and the pace of restoration is far outpacing the rate of degradation. Current methods for improving grassland soil primarily include fencing to prohibit grazing, shallow tillage, aerial seeding, and the application of soil conditioners. Among these, the application of soil conditioners has seen rapid development and widespread application both domestically and internationally in recent years due to its rapid effectiveness and significant results.

[0004] Fly ash, also known as fly ash, originates from coal-fired power plant boilers, with an annual production of nearly 600 million tons. Fly ash is both a solid waste and a resource with potential value. Because its chemical composition is very similar to soil and it is rich in trace elements essential for plant growth, it has a natural advantage in preparing soil conditioners.

[0005] CN111248028A discloses a soil reconstructor, its preparation method, and its application. The preparation method involves mixing soil strippings, coal gangue, and fly ash, then adding biochar and stirring until homogeneous to obtain a soil reconstructor. Fly ash and coal gangue can effectively address the problem of surface soil infertility, but it does not consider the low activity of fly ash and its inability to be applied on a large scale in grasslands. CN105237094A discloses a method for preparing a material to enhance the moisture retention of grassland soil. It uses livestock manure and forage as the main materials, and fly ash, urea, potassium sulfate, copper sulfate, etc., as auxiliary materials to prepare a grassland soil water-retaining agent. This method improves grassland soil, but the main component of this water-retaining agent is livestock manure, with fly ash only added as an ingredient, which cannot achieve the effect of large-scale utilization of fly ash. It also does not consider the low activity of fly ash. CN110156537A discloses a soil conditioner for saline-alkali grassland soil in tidal flats and its preparation method. The conditioner uses fly ash and zeolite powder as the main raw materials and phosphoric acid and humic acid as auxiliary materials. It can reduce the salt content of grassland soil and increase the organic matter content of the soil. However, this conditioner is only suitable for grassland soil with high salt content, and it is in powder form, which is easily blown away by the wind after application, resulting in uneven application and other problems.

[0006] In summary, while existing fly ash-based soil conditioners offer some soil remediation benefits, they still have significant limitations. Most simply add fly ash directly as an additive without considering its activation, preventing plants from effectively absorbing beneficial elements. Furthermore, they fail to address specific challenges encountered during application in grasslands. For example, powdered conditioners are inconvenient to transport, store, and apply; they generate large amounts of dust during distribution and application, leading to dust pollution and health hazards; and powdered products cannot be mechanized or applied on a large scale. Granular soil conditioners offer greater convenience and avoid the drawbacks of powdered conditioners. However, they typically require binders during granulation, resulting in very hard particles that are difficult to disperse or pulverize effectively when exposed to water or moisture. This means that granular soil conditioners may remain unchanged for months or even years after application, severely hindering plant absorption and failing to improve soil quality.

[0007] Therefore, there is an urgent need to develop a new type of fly ash-based soil conditioner. On the one hand, by using fly ash activation and compounding technology, the activity and balance of nutrients in the conditioner and the water retention performance of the conditioner can be improved. On the other hand, by adjusting the formula and granulation methods, the physical properties of the conditioner can be improved, thereby enhancing its ease of application and effectiveness. This will establish a new grassland restoration method and effectively solve the problem of grassland degradation. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a soil conditioner for grassland restoration and its preparation method, in order to solve soil degradation problems such as nutrient deficiency, poor water and fertilizer retention, and weak wind resistance in grassland soil. The preparation method provided by this invention has the advantages of simple process, high fly ash utilization rate, effective improvement of soil organic matter and beneficial element content, good water retention performance, and ease of large-scale application.

[0009] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0010] One objective of this invention is to provide a method for preparing a soil conditioner, the method comprising the following steps:

[0011] (1) After mixing fly ash, calcium-containing substances and alkaline solution evenly, a hydrothermal reaction is carried out, and solid-liquid separation is performed to obtain solid products;

[0012] (2) The solid product obtained in step (1) is mixed evenly with organic matter and disintegrant, and the resulting mixture is granulated with solvent to obtain the soil conditioner.

[0013] In this invention, fly ash, as an inexpensive and readily available industrial waste, is rich in trace elements essential for plant growth, making it an ideal raw material for soil conditioners. Furthermore, as shown in Table 1, activation treatment of fly ash can activate the trace elements within it, transforming them into readily absorbable forms that balance nutrients in the soil. Simultaneously, it significantly alters the microstructure of fly ash, transforming it into a loose, porous structure with high porosity, greatly enhancing its water and fertilizer retention capacity. Therefore, activating fly ash to produce fly ash-based soil conditioners aligns with the principles of a circular economy, alleviating environmental problems caused by large-scale fly ash stockpiling and addressing soil degradation, demonstrating promising application prospects.

[0014] As a preferred technical solution of the present invention, the fly ash in step (1) contains SiO2.

[0015] Preferably, the calcium-containing substance in step (1) includes industrial raw materials or waste residue containing CaO.

[0016] In this invention, the proportion of CaO in the industrial raw materials or waste residue is 25-90 wt%, for example, it can be 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, 85 wt%, or 90 wt%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] Preferably, the alkaline solution in step (1) includes sodium hydroxide solution and / or potassium hydroxide solution.

[0018] As a preferred technical solution of the present invention, the molar ratio of CaO in the calcium-containing substance to SiO2 in the fly ash in step (1) is (0.4-1.4):1, for example, it can be 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1 or 1.4:1, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably (0.6-1.2):1.

[0019] In this invention, the molar ratio of CaO in the calcium-containing substance to SiO2 in the fly ash in step (1) needs to be maintained within a reasonable range. When the molar ratio is lower than 0.4:1 or higher than 1.4:1, it will affect the activation effect of trace elements in the fly ash and its water absorption and retention properties, thereby affecting the effect of the soil conditioner.

[0020] Preferably, the concentration of the alkaline solution in step (1) is 0.05-2.5 mol / L, for example, it can be 0.05 mol / L, 0.1 mol / L, 0.25 mol / L, 0.5 mol / L, 0.75 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L or 2.5 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.1-1.5 mol / L.

[0021] Preferably, the mass-to-volume ratio of the total mass of fly ash and calcium-containing substances in step (1) to the mass-to-volume ratio of the alkaline solution is 1:(5-40)g / mL. For example, it can be 1:5g / mL, 1:10g / mL, 1:15g / mL, 1:20g / mL, 1:25g / mL, 1:30g / mL, 1:35g / mL, or 1:40g / mL, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 1:(10-25)g / mL.

[0022] In this invention, the mass-to-volume ratio of the total mass of the fly ash and calcium-containing substances to the alkaline solution needs to be maintained within a reasonable range. When the mass-to-volume ratio is lower than 1:5 g / mL, the mixture is difficult to mix evenly, and the activation reaction is difficult to carry out; when the mass-to-volume ratio is higher than 1:40 g / mL, it will cause unnecessary energy consumption.

[0023] As a preferred technical solution of the present invention, the temperature of the hydrothermal reaction in step (1) is 100-280℃, for example, it can be 100℃, 125℃, 150℃, 175℃, 200℃, 225℃, 250℃, 275℃ or 280℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 160-220℃.

[0024] Preferably, the hydrothermal reaction time in step (1) is 0.5-30h, for example, it can be 0.5h, 1h, 2h, 3h, 5h, 7h, 10h, 15h, 20h, 25h or 30h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1-6h.

[0025] In this invention, the hydrothermal reaction conditions need to be maintained within a reasonable range. When the hydrothermal reaction temperature is below 100℃, the reaction kinetics are insufficient, reducing the activation effect of fly ash; when the hydrothermal reaction temperature is above 280℃, additional energy consumption is increased, raising costs. When the hydrothermal reaction time is less than 0.5h, the reaction is incomplete, and most raw materials cannot be converted, resulting in waste; when the hydrothermal reaction time is greater than 30h, the structure of the reaction products changes, reducing the activity of trace elements and water retention capacity. The preferred hydrothermal reaction temperature and time can improve the utilization rate of raw materials, efficiently converting raw materials into new materials, while reducing resource waste and energy consumption.

[0026] As a preferred technical solution of the present invention, the solid-liquid separation in step (1) further includes washing, drying and crushing processes performed in sequence.

[0027] In this invention, the solid-liquid separation can be performed to separate the solid product after the hydrothermal reaction from the liquid. The specific method can be selected according to the actual production situation and is not specifically limited here.

[0028] As a preferred technical solution of the present invention, the organic matter in step (2) includes any one or at least two combinations of plant straw, cow dung, sheep dung or humic acid. Typical but non-limiting examples of such combinations include: a combination of plant straw and cow dung, a combination of cow dung and sheep dung, or a combination of sheep dung and humic acid.

[0029] In this invention, the addition of organic matter can significantly increase the content of organic matter in soil conditioners, improve the available nutrients in the soil, provide a material basis for the formation of soil aggregates, and further repair degraded soil structure.

[0030] Preferably, the disintegrant in step (2) comprises amino acids and / or amino acid-containing compounds.

[0031] In this invention, amino acids and / or amino acid-containing compounds are added during the granulation process in step (2) to ensure uniform distribution of amino acids in the soil conditioner granules. When the granules come into contact with water, the amino acids on the surface of the granules dissolve rapidly, forming pores on the surface of the granules, allowing water to quickly penetrate into the interior of the granules. As the amino acids continue to dissolve, water continues to penetrate into the interior of the granules until the entire granule is filled. The penetration of water can cause electrostatic repulsion between the microscopic particles inside the soil conditioner granules, breaking the adhesion between the microscopic particles, causing the granules to quickly disperse and pulverize, which is beneficial for plant absorption and soil improvement.

[0032] Preferably, the amino acid comprises any one or at least two combinations of leucine, isoleucine, arginine, lysine, proline, glycine, alanine, threonine, histidine, methionine, serine, glutamic acid, tyrosine, cystine, valine, or methionine. Typical but non-limiting examples of such combinations include: the combination of leucine and isoleucine, the combination of arginine and lysine, the combination of threonine and histidine, the combination of methionine and serine, or the combination of proline and glycine.

[0033] As a preferred technical solution of the present invention, the mass ratio of the solid product to the organic matter and the disintegrant in step (2) is 10:(1-10):(0.01-3), for example, it can be 10:1:0.01, 10:2:0.02, 10:3:0.06, 10:4:0.1, 10:5:0.6, 10:6:1, 10:7:1.5, 10:8:2, 10:9:2.5 or 10:10:3, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] In this invention, the amount of disintegrant added must be kept within a reasonable range. When the addition amount is less than 10:1:0.01, the amino acids in the soil conditioner particles are too few, making it difficult to distribute evenly and not enough voids to be generated in the particles, so water cannot penetrate fully and it cannot play a role in breaking the bonding force between micro particles; when the addition amount is greater than 10:10:3, it increases the cost and reduces the economic efficiency of the product.

[0035] As a preferred technical solution of the present invention, the mass-volume ratio of the mixture to the solvent in step (2) is 10:(1-10)g / mL, for example, it can be 10:1g / mL, 10:2g / mL, 10:3g / mL, 10:4g / mL, 10:5g / mL, 10:6g / mL, 10:7g / mL, 10:8g / mL, 10:9g / mL or 10:10g / mL, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] In this invention, the mass-to-volume ratio of the mixture to the solvent in step (2) must be maintained within a reasonable range. When the mass-to-volume ratio is lower than 10:1 g / mL, the material is too dry and difficult to granulate; when the mass-to-volume ratio is higher than 10:10 g / mL, the material is too wet and easily forms large lumps, making it difficult to produce particles of suitable size.

[0037] In this invention, the granulation method in step (2) includes any one of disc granulation, drum granulation, toothed granulation, or high-speed mixer granulation.

[0038] In this invention, when a disc granulator is used in step (2), the disc tilt angle is 20°-55° and the disc rotation speed is 10-50 r / min. Soil conditioner particles prepared by the disc granulator are more uniform, have better mixability, have good automatic grading ability, a smaller return ratio, and are easier to control, which is beneficial for large-scale production of the product.

[0039] In this invention, the solvent is sprayed into the granulation equipment during the granulation process to mix with the mixture. Spraying the solvent while granulating allows the solvent to be more evenly distributed on the particle surface, which is more conducive to producing particles with uniform particle size.

[0040] In this invention, the particle diameter of the soil conditioner in step (2) is 5-50 mm, for example, it can be 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm or 50 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] In this invention, the particle diameter of the soil conditioner described in step (2) needs to be kept within a reasonable range. When the particle diameter is less than 5 mm, it is easily blown away by the wind after being applied to the grassland, resulting in uneven application of the soil conditioner and easy waste; when the particle diameter is greater than 50 mm, the particle disintegration process is affected, and it is not easy to fully disperse into small particles or powder after encountering water or moisture, affecting the application effect.

[0042] In this invention, when the organic matter in step (2) is plant straw, the length of the plant straw is 10-100 mm longer than the diameter of the pellets produced. For example, it can be 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm or 100 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] In this invention, the length of the plant straw needs to be kept within a reasonable range. When the straw length is greater than the particle diameter, some straw is exposed outside the particle, forming a spiky structure, thereby increasing the surface roughness of the soil conditioner particles. After the soil conditioner is applied to the grassland, the exposed straw will increase the friction between the conditioner particles and the pasture, which is beneficial to improving the wind resistance of the soil conditioner particles, making them less likely to be blown away by the wind, and improving the accuracy of application.

[0044] As a preferred embodiment of the present invention, the method for preparing the soil conditioner includes the following steps:

[0045] (1) Fly ash, calcium-containing substances and alkaline solution with a concentration of 0.05-2.5 mol / L are mixed evenly. The molar ratio of CaO in the calcium-containing substances to SiO2 in the fly ash is (0.4-1.4):1. The mass-volume ratio of the total mass of the fly ash and calcium-containing substances to the alkaline solution is 1:(5-40) g / mL. The mixture is heated at 100-280℃ for 0.5-30 h. After the reaction is completed, the solid and liquid are separated, and the solid product is obtained after washing, drying and crushing.

[0046] (2) The solid product obtained in step (1) is mixed evenly with organic matter and disintegrant, wherein the mass ratio of the solid product to the organic matter and disintegrant is 10:(1-10):(0.01-3), and the resulting mixture is granulated with solvent, wherein the mass-volume ratio of the mixture to the solvent is 10:(1-10)g / mL, to obtain the soil conditioner.

[0047] A second objective of this invention is to provide a soil conditioner for grassland restoration, wherein the soil conditioner is prepared using the preparation method described in the first aspect.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The present invention provides a soil conditioner for grassland restoration and its preparation method. During the preparation of the soil conditioner, the trace elements in fly ash can be fully activated. The activation rate of beneficial elements such as silicon, calcium, iron, magnesium, and potassium can reach 50%-90%, providing nutrients for the growth of plants and soil microorganisms. The prepared soil conditioner has multiple functions such as soil restoration, slow release of fertilizer, soil water retention, adsorption of heavy metal ions, reduction of soil bulk density and improvement of soil permeability. It is suitable for restoring the soil of degraded grassland.

[0050] (2) The soil conditioner prepared by this invention combines the advantages of granular and powdered soil conditioners. The product is granular, which facilitates transportation, storage and mechanized application. The addition of straw during the granulation process increases the surface roughness of the granules, which is beneficial for the fixation of the granules after application to the grassland, and improves their wind resistance, making it suitable for the windy natural environment of the grassland.

[0051] (3) In the granulation process, the present invention adds a disintegrant (amino acid). After being applied to the soil, it can quickly disperse and pulverize when it comes into contact with water, and penetrate into the soil crevices. It can fully contact the plant roots and is easily absorbed by the plants. The added amino acids can also provide nutrients to the plants. The addition will not reduce the proportion of useful components in the soil conditioner.

[0052] (4) The raw materials in this invention are inexpensive and widely available, the preparation method is simple and easy to implement, the resource utilization rate is high, and it has broad application prospects. Detailed Implementation

[0053] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0054] In this embodiment of the invention, the fly ash is taken from a power plant in Inner Mongolia; the straw is taken from a farm in Inner Mongolia; the cow dung and sheep dung are taken from a livestock farm in Inner Mongolia; and the humic acid is purchased from a humic acid plant in Inner Mongolia.

[0055] Example 1

[0056] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0057] (1) Fly ash, industrial calcium oxide and potassium hydroxide solution with a concentration of 0.8 mol / L are mixed evenly. The molar ratio of CaO in the industrial calcium oxide to SiO2 in the fly ash is 0.9:1. The mass-volume ratio of the total mass of the fly ash and industrial calcium oxide to the potassium hydroxide solution is 1:17 g / mL. The mixture is heated at 190℃ for 4 hours. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0058] (2) The solid product obtained in step (1) is mixed with humic acid and leucine at a mass ratio of 10:5:1.5. The resulting mixture is placed in a disc granulator with a disc tilt angle of 35° and a disc rotation speed of 16 r / min. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:5 g / mL, resulting in a soil conditioner with a particle diameter of 50 mm.

[0059] Example 2

[0060] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0061] (1) Fly ash, industrial calcium oxide and potassium hydroxide solution with a concentration of 0.05 mol / L are mixed evenly. The molar ratio of CaO in the industrial calcium oxide and SiO2 in the fly ash is 0.4:1. The mass-volume ratio of the total mass of the fly ash and industrial calcium oxide to the potassium hydroxide solution is 1:5 g / mL. The mixture is heated at 100℃ for 30 h. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0062] (2) The solid product obtained in step (1) is mixed with sheep manure and lysine at a mass ratio of 10:1:0.01. The resulting mixture is placed in a disc granulator with a disc tilt angle of 35° and a disc rotation speed of 16 r / min. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:1 g / mL, resulting in a soil conditioner with a particle diameter of 5 mm.

[0063] Example 3

[0064] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0065] (1) Fly ash, industrial calcium oxide and sodium hydroxide solution with a concentration of 2.5 mol / L are mixed evenly. The molar ratio of CaO in the industrial calcium oxide and SiO2 in the fly ash is 1.4:1. The mass-volume ratio of the total mass of the fly ash and industrial calcium oxide to the sodium hydroxide solution is 1:40 g / mL. The mixture is heated at 280℃ for 0.5 h. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0066] (2) The solid product obtained in step (1) is mixed with humic acid and lysine at a mass ratio of 10:10:3. The resulting mixture is placed in a disc granulator with a disc tilt angle of 35° and a disc rotation speed of 16 r / min. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:10 g / mL, resulting in a soil conditioner with a particle diameter of 20 mm.

[0067] Example 4

[0068] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0069] (1) Fly ash, industrial calcium oxide and potassium hydroxide solution with a concentration of 0.2 mol / L are mixed evenly. The molar ratio of CaO in the industrial calcium oxide and SiO2 in the fly ash is 1:1. The mass-volume ratio of the total mass of the fly ash and industrial calcium oxide to the potassium hydroxide solution is 1:20 g / mL. The mixture is heated at 180℃ for 5 h. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0070] (2) The solid product obtained in step (1) is mixed with humic acid and leucine at a mass ratio of 10:5:0.03. The resulting mixture is placed in a disc granulator with a disc tilt angle of 35° and a disc rotation speed of 16 r / min. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:5 g / mL, resulting in a soil conditioner with a particle diameter of 10 mm.

[0071] Example 5

[0072] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0073] (1) Fly ash, Ca(OH)2 and potassium hydroxide solution with a concentration of 1.5 mol / L are mixed evenly. The molar ratio of Ca(OH)2 to SiO2 in fly ash is 1.4:1. The mass-volume ratio of the total mass of fly ash and Ca(OH)2 to potassium hydroxide solution is 1:40 g / mL. The mixture is heated at 200℃ for 8 hours. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0074] (2) The solid product obtained in step (1) is mixed with the straw and amino acid mixture at a mass ratio of 10:10:0.01. The length of the straw is 70 mm. The amino acid mixture is a mixture of isoleucine, arginine, lysine and proline at a mass ratio of 1:0.5:0.5:0.1. The resulting mixture is placed in a disc granulator with a disc tilt angle of 55° and a disc rotation speed of 10 r / min. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:5 g / mL. Soil conditioner with a particle diameter of 50 mm is obtained.

[0075] Example 6

[0076] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0077] (1) Fly ash, industrial calcium oxide and sodium hydroxide solution with a concentration of 2.5 mol / L are mixed evenly. The molar ratio of CaO in the industrial calcium oxide to SiO2 in the fly ash is 0.4:1. The mass-volume ratio of the total mass of the fly ash and industrial calcium oxide to the sodium hydroxide solution is 1:10 g / mL. The mixture is heated at 160℃ for 2 hours. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0078] (2) The solid product obtained in step (1) is mixed with organic matter and lysine residue at a mass ratio of 10:8:1. The organic matter is a mixture of cow manure and humic acid at a mass ratio of 3:2. The resulting mixture is placed in a rotary drum granulator, and water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:10 g / mL, resulting in a soil conditioner with a particle diameter of 20 mm.

[0079] Example 7

[0080] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0081] (1) Fly ash, phosphogypsum and potassium hydroxide solution with a concentration of 0.05 mol / L are mixed evenly. The molar ratio of CaO in the phosphogypsum and SiO2 in the fly ash is 1.2:1. The mass-volume ratio of the total mass of fly ash and phosphogypsum to potassium hydroxide solution is 1:5 g / mL. The mixture is heated at 220℃ for 1 h. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0082] (2) The solid product obtained in step (1) is mixed with the organic matter and amino acid mixture at a mass ratio of 10:1:3. The organic matter is a mixture of cow manure, sheep manure and straw at a mass ratio of 1:2:2. The length of the straw is 25 mm. The amino acid mixture is a mixture of glycine, alanine, threonine, histidine and methionine at a mass ratio of 1:0.2:0.3:0.1:0.8. The resulting mixture is placed in a stirring tooth granulator. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:3 g / mL. A soil conditioner with a particle diameter of 15 mm is obtained.

[0083] Example 8

[0084] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0085] (1) Fly ash, carbide slag and sodium hydroxide solution with a concentration of 0.1 mol / L are mixed evenly. The molar ratio of CaO in the carbide slag and SiO2 in the fly ash is 0.6:1. The mass-volume ratio of the total mass of the fly ash and carbide slag to the sodium hydroxide solution is 1:15 g / mL. The mixture is heated at 100℃ for 30 h. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain the solid product.

[0086] (2) The solid product obtained in step (1) is mixed with organic matter and glycine residue at a mass ratio of 10:3:2. The organic matter is a mixture of humic acid and straw at a mass ratio of 1:1. The length of the straw is 125 mm. The resulting mixture is placed in a disc granulator with a disc tilt angle of 20° and a disc rotation speed of 50 r / min. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:6 g / mL. Soil conditioner with a particle diameter of 25 mm is obtained.

[0087] Example 9

[0088] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0089] (1) Fly ash, industrial calcium oxide and potassium hydroxide solution with a concentration of 1 mol / L are mixed evenly. The molar ratio of CaO in the industrial calcium oxide to SiO2 in the fly ash is 0.9:1. The mass-volume ratio of the total mass of the fly ash and industrial calcium oxide to the potassium hydroxide solution is 1:25 g / mL. The mixture is heated at 280℃ for 0.5 h. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0090] (2) The solid product obtained in step (1) is mixed with the organic matter and amino acid mixture at a mass ratio of 10:10:0.5. The organic matter is a mixture of sheep manure and straw at a mass ratio of 1:1. The length of the straw is 55 mm. The amino acid mixture is a mixture of serine, glutamic acid, tyrosine, cystine, methionine and valine at a mass ratio of 1:0.3:0.1:0.5:0.8:0.5. The resulting mixture is placed in a high-speed mixing granulator. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:1 g / mL. A soil conditioner with a particle diameter of 5 mm is obtained.

[0091] Example 10

[0092] This embodiment provides a method for preparing a soil conditioner, the method comprising the following steps:

[0093] (1) Fly ash, lime and sodium hydroxide solution with a concentration of 0.5 mol / L are mixed evenly. The molar ratio of CaO in the lime to SiO2 in the fly ash is 1:1. The mass-volume ratio of the total mass of fly ash and lime to sodium hydroxide solution is 1:30 g / mL. The mixture is heated at 150℃ for 6 hours. After the reaction is completed, the solid and liquid are separated, washed, dried and crushed to obtain a solid product.

[0094] (2) The solid product obtained in step (1) is mixed with organic matter and glutamic acid residue at a mass ratio of 10:10:0.5. The organic matter is a mixture of humic acid, cow manure and straw at a mass ratio of 1:0.6:1. The length of the straw is 100 mm. The resulting mixture is placed in a disc granulator with a disc tilt angle of 30° and a disc rotation speed of 25 r / min. Water is sprayed into the granulator for granulation. The mass-volume ratio of the mixture to water is 10:8 g / mL. Soil conditioner with a particle diameter of 30 mm is obtained.

[0095] Example 11

[0096] This embodiment provides a method for preparing a soil conditioner, which includes the following steps: except that the added organic matter does not contain straw, all other conditions are the same as in Example 7, to obtain a soil conditioner with a particle diameter of 15 mm.

[0097] Comparative Example 1

[0098] This comparative example provides a method for preparing a soil conditioner, which includes the following steps: except that no industrial calcium oxide is added; all other conditions are the same as in Example 4, to obtain a soil conditioner with a particle diameter of 8.5 mm.

[0099] Comparative Example 2

[0100] This comparative example provides a method for preparing a soil conditioner, which includes the following steps: except that the potassium hydroxide solution is replaced with water; all other conditions are the same as in Example 4, to obtain a soil conditioner with a particle diameter of 9.1 mm.

[0101] Comparative Example 3

[0102] This comparative example provides a method for preparing a soil conditioner, which includes the following steps: except that no heating reaction is performed; all other conditions are the same as in Example 4, to obtain a soil conditioner with a particle diameter of 8.1 mm.

[0103] Comparative Example 4

[0104] This comparative example provides a method for preparing a soil conditioner, which includes the following steps: except that humic acid is not added; all other conditions are the same as in Example 4, to obtain a soil conditioner with a particle diameter of 8.3 mm.

[0105] Comparative Example 5

[0106] This comparative example provides a method for preparing a soil conditioner, which includes the following steps: except that leucine is not added; all other conditions are the same as in Example 4, to obtain a soil conditioner with a particle diameter of 9.8 mm.

[0107] The test methods and results of the above embodiments and comparative examples are as follows:

[0108] Typical grassland soil from Inner Mongolia was selected, and the prepared soil conditioner was mixed evenly with the grassland soil at a mass ratio of 1:1000. A pot experiment was conducted, and ice grass was selected as the plant.

[0109] Soil moisture content was measured in potted soils containing soil conditioners prepared in Examples 1-11 and Comparative Examples 1-5 using a soil moisture meter. Ammonium nitrogen, available phosphorus, and available potassium were measured in the potted soils containing soil conditioners prepared in Examples 1-11 and Comparative Examples 1-5 using a visible spectrophotometer. The particle rolling capacity of the soil conditioner was measured using a blower at a simulated wind speed of 10 m / s. The particle disintegration time of the soil conditioner was measured using a simulated precipitation method. The water absorption ratio of the soil conditioner was tested using a gravimetric method.

[0110] Table 1

[0111]

[0112]

[0113] The following points can be observed from Table 1:

[0114] (1) The soil conditioner for grassland restoration provided by the present invention, compared with the original grassland soil, has significantly increased the content of available nutrients and soil moisture content in the soil after adding the soil conditioner prepared in the examples. This indicates that the soil conditioner prepared in the examples of the present invention has a stronger ability to regulate soil, more comprehensive functions, and higher application potential.

[0115] (2) Combining Example 4 and Comparative Example 1, it can be seen that under the condition of no industrial calcium oxide processing, the soil moisture content and the contents of ammonium nitrogen, available phosphorus and available potassium in the soil are all lower than those in Example 4, indicating that the addition of calcium-containing substances is beneficial to the absorption of available nutrients in the soil.

[0116] (3) Combining Example 4 and Comparative Examples 2-3, it can be seen that the soil moisture content is low under the conditions of no alkali solution or no heating, indicating that alkalinity and heating conditions play a key role in the modification of fly ash, which can significantly improve the water retention capacity of the soil conditioner. When applied to grassland soil, it can significantly increase the soil moisture content and play a good role in grassland soil improvement. At the same time, the content of available potassium in Comparative Examples 2-3 is also significantly lower than that in Example 4, indicating that after fly ash is modified by alkalinity and hydrothermal conditions, its potassium adsorption capacity is improved. The prepared soil conditioner can adsorb more potassium elements, which is beneficial to increasing the content of available potassium in grassland soil after application.

[0117] (4) Combining Example 4 and Comparative Example 4, it can be seen that under the condition of no addition of organic matter (humic acid), the content of ammonium nitrogen and available phosphorus in the soil is significantly lower than that in Example 4. This indicates that the content of readily available nutrients in the soil conditioner prepared without the addition of organic matter is low, which cannot effectively supply the nutrients required for plant growth, thereby affecting plant growth.

[0118] Table 2

[0119]

[0120]

[0121] The following points can be observed from Table 2:

[0122] (1) Combining Examples 7 and 11, it can be seen that the soil conditioner prepared without straw has a longer movement distance, indicating that adding straw can increase the roughness of the ball surface, increase the frictional resistance between the ball and the ground, significantly improve the wind resistance of the soil conditioner particles, prevent the soil conditioner from being blown away by the wind, make the application of the soil conditioner more uniform, and improve the grassland soil improvement effect.

[0123] (2) Combining Example 4 and Comparative Example 1, it can be seen that the water absorption ratio of the prepared soil conditioner is significantly lower than that of Example 4 under the condition of no industrial calcium oxide processing, indicating that the addition of calcium-containing substances is beneficial to improving the water absorption rate of the soil conditioner.

[0124] (3) Combining Example 4 and Comparative Examples 2-3, it can be seen that the water absorption ratio of the prepared soil conditioner is significantly lower than that of Example 4 under the condition of no alkali solution or no heating. This indicates that the fly ash did not undergo an effective hydrothermal reaction, the microstructure of the fly ash did not change significantly, and it did not have a loose porous structure with high porosity, resulting in a low water absorption rate of the prepared soil conditioner.

[0125] (4) As can be seen from Example 4 and Comparative Example 5, the soil conditioner prepared without the addition of a disintegrant has a disintegration time that is too long, which seriously affects its effect when applied to grassland soil, resulting in the nutrients not being absorbed by plants in time.

[0126] In summary, this invention provides a soil conditioner for grassland restoration and its preparation method. Modified fly ash is prepared by hydrothermal reaction of fly ash with calcium-containing substances under alkaline conditions. This process activates the trace elements in the fly ash and rearranges its skeletal structure, resulting in a loose, porous structure with high porosity, significantly improving the fly ash's water absorption capacity. The soil conditioner, prepared by rationally combining it with organic matter, increases the content of readily available nutrients and soil moisture, providing necessary conditions for plant growth and development. A rational combination with straw improves the wind resistance of the soil conditioner particles. A rational combination with a disintegrant greatly shortens the disintegration time of the soil conditioner particles, allowing them to quickly disperse and pulverize upon contact with water after application to the soil. This invention uses industrial waste fly ash as raw material, achieving waste utilization and energy conservation, and has broad application prospects. The preparation process is simple and easy to operate, enabling large-scale production.

[0127] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a soil conditioner for grassland restoration, characterized in that, The preparation method includes the following steps: (1) After mixing fly ash, calcium-containing substances and alkaline solution evenly, a hydrothermal reaction is carried out, and solid-liquid separation is performed to obtain solid products; (2) The solid product obtained in step (1) is mixed evenly with organic matter and disintegrant, and the resulting mixture is granulated with solvent to obtain the soil conditioner; The organic matter in step (2) is plant straw, or a combination of plant straw and at least one of cow dung, sheep dung or humic acid; the length of the plant straw is 10-100 mm longer than the diameter of the produced particles. The disintegrant in step (2) includes amino acids and / or amino acid-containing compounds; In step (2), the mass ratio of the solid product to the organic matter and the disintegrant is 10:(1-10):(0.01-3); the mass-volume ratio of the mixture to the solvent is 10:(1-10) g / mL. In step (2), the solvent is sprayed into the granulation equipment during the granulation process to mix with the mixture, and the solvent is sprayed in while granulation is being carried out; The soil conditioner has a particle diameter of 5-50 mm.

2. The preparation method according to claim 1, characterized in that, The fly ash in step (1) contains SiO2.

3. The preparation method according to claim 2, characterized in that, The calcium-containing substances mentioned in step (1) include industrial raw materials or waste residues containing CaO.

4. The preparation method according to claim 1, characterized in that, The alkaline solution in step (1) includes sodium hydroxide solution and / or potassium hydroxide solution.

5. The preparation method according to claim 3, characterized in that, In step (1), the molar ratio of CaO in the calcium-containing substance to SiO2 in the fly ash is (0.4-1.4):

1.

6. The preparation method according to claim 5, characterized in that, In step (1), the molar ratio of CaO in the calcium-containing substance to SiO2 in the fly ash is (0.6-1.2):

1.

7. The preparation method according to claim 1, characterized in that, The concentration of the alkaline solution in step (1) is 0.05-2.5 mol / L.

8. The preparation method according to claim 7, characterized in that, The concentration of the alkaline solution in step (1) is 0.1-1.5 mol / L.

9. The preparation method according to claim 1, characterized in that, In step (1), the total mass ratio of the fly ash and calcium-containing substances to the mass-volume ratio of the alkaline solution is 1:(5-40)g / mL.

10. The preparation method according to claim 9, characterized in that, In step (1), the total mass of fly ash and calcium-containing substances is in a mass-to-volume ratio of 1:(10-25)g / mL to the alkaline solution.

11. The preparation method according to claim 1, characterized in that, The temperature of the hydrothermal reaction in step (1) is 100-280℃.

12. The preparation method according to claim 11, characterized in that, The temperature of the hydrothermal reaction in step (1) is 160-220℃.

13. The preparation method according to claim 1, characterized in that, The hydrothermal reaction time in step (1) is 0.5-30h.

14. The preparation method according to claim 13, characterized in that, The hydrothermal reaction time in step (1) is 1-6 hours.

15. The preparation method according to claim 1, characterized in that, Step (1) after solid-liquid separation also includes sequential washing, drying and crushing processes.

16. The preparation method according to claim 1, characterized in that, The amino acids include any one or at least two combinations of leucine, isoleucine, arginine, lysine, proline, glycine, alanine, threonine, histidine, methionine, serine, glutamic acid, tyrosine, cystine, valine, or methionine.

17. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Mix fly ash, calcium-containing substances and alkaline solution with a concentration of 0.05-2.5 mol / L evenly. The molar ratio of CaO in the calcium-containing substances to SiO2 in the fly ash is (0.4-1.4):

1. The mass-volume ratio of the total mass of the fly ash and calcium-containing substances to the alkaline solution is 1:(5-40) g / mL. Heat at 100-280℃ for 0.5-30 h. After the reaction is completed, separate the solid and liquid, and obtain the solid product after washing, drying and crushing. (2) The solid product obtained in step (1) is mixed evenly with organic matter and disintegrant. The mass ratio of the solid product to the organic matter and disintegrant is 10:(1-10):(0.01-3). The resulting mixture is granulated with solvent. The mass-volume ratio of the mixture to the solvent is 10:(1-10) g / mL. The soil conditioner is obtained. The length of the plant straw is 10-100 mm longer than the diameter of the granules. The diameter of the soil conditioner granules is 5-50 mm. The solvent is sprayed into the granulation equipment during the granulation process to mix with the mixture. The solvent is sprayed in while granulating.

18. A soil conditioner for grassland restoration, characterized in that, The soil conditioner is prepared using the preparation method described in any one of claims 1-17.

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