Microencapsulated high-alkalinity auxiliary material and application thereof in preparation of high-alkalinity earthworm manure

Abstract

The invention discloses a microencapsulated high-alkalinity auxiliary material and application thereof in preparation of high-alkalinity earthworm manure. The microencapsulated high-alkalinity auxiliary material is prepared from the following raw materials: a high-alkalinity auxiliary material, sodium alginate, a trihydroxymethyl aminomethane hydrochloride solution and a calcium chloride solution, wherein the weight ratio of the high-alkalinity auxiliary material to the sodium alginate to the Tris-HCl solution to the calcium chloride solution is 1: (1-3): (40-150): (150-200); the microencapsulated high-alkalinity auxiliary material is prepared through scientific and reasonable process steps, meanwhile, the microencapsulated high-alkalinity auxiliary material is introduced into earthworm compost, the adverse effect of the microencapsulated high-alkalinity auxiliary material on earthworm vital activities is reduced, and the high-alkalinity earthworm manure which is stable in pH and excellent in fertilizer efficiency is prepared so as to meet the requirement of the acid soil environment for the fertilizer.

Description

Technical Field

[0001] This invention relates to the field of fertilizer preparation technology, specifically to a microencapsulated high-alkalinity adjuvant and its application in the preparation of high-alkalinity earthworm castings fertilizer. Background Technology

[0002] Vermicompost is a fertilizer produced by adding livestock manure, straw, and other organic waste to the earthworm bed during earthworm farming. The earthworms utilize and decompose this organic matter through their digestive processes, resulting in fine granular material mixed with the soil. Vermicompost contains high levels of organic matter, as well as essential macro- and micronutrients, providing ample readily available nutrients for plant growth. Furthermore, the numerous aggregates in vermicompost loosen and improve soil aeration, water retention, and nutrient retention in farmland. Therefore, vermicompost is widely used in agricultural production as a high-quality organic fertilizer. During the process of converting waste into organic matter, the various microorganisms release acidic substances, bringing the pH of the vermicompost closer to neutral, thus providing a soil environment conducive to plant growth. However, for acidic soils, the application of slightly neutral vermicompost does not significantly increase crop yields. Therefore, preparing highly alkaline vermicompost is key to improving its effectiveness in acidic soils.

[0003] Alkaline tailings originate from tailings generated during the beneficiation of metal mines (such as lead-zinc and copper mines) and waste products from some chemical industries (such as calcium carbide production and chlor-alkali industry). Due to their high content of alkaline substances such as hydroxides, carbonates, and silicates, alkaline tailings typically share characteristics such as high pH values ​​and fine particle sizes. For example, calcium carbide slag has an average particle size of 40-60 μm, its main component is calcium hydroxide, and its pH value is as high as 12-14; finely crushed steel slag typically has a particle size of 30-45 μm, and its main components are calcium oxide, magnesium oxide, and silicon dioxide, with a pH value reaching 11-13. Globally, a total of 1.7 billion tons of alkaline tailings byproducts are generated annually. Improper disposal can lead to a series of environmental problems, such as soil alkalization, affecting plant growth, and alkaline wastewater seeping into groundwater or flowing into surface water bodies, altering the chemical properties of the water and damaging aquatic ecosystems. If these alkaline tailings could be applied to the vermicomposting process, it would help increase the pH of vermicompost and produce highly alkaline vermicompost. However, given the adverse effects of these highly alkaline materials on earthworm life activities, there is currently no technology to combine the two for development and utilization. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a microencapsulated high-alkalinity excipient and its application in the preparation of high-alkalinity vermicompost. This invention prepares the microencapsulated high-alkalinity excipient through scientific and reasonable process steps, and introduces the microencapsulated high-alkalinity excipient into vermicompost to reduce its adverse effects on the life activities of earthworms, thereby preparing a high-alkalinity vermicompost with stable pH and excellent fertilizer effect to meet the fertilizer requirements of acidic soil environments. To achieve the above objectives, the technical solution designed by the present invention is as follows: This invention provides a microencapsulated high-alkalinity excipient, the raw materials of which include a high-alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution; wherein the weight ratio of the high-alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution is 1:1~3:40~150:150~200; The raw materials for the high alkalinity auxiliary material are composed of alkaline tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1~2:1~2; and the concentration of the Tris-HCl solution is 40~60 mmol / L. The mass fraction of calcium chloride solution is 2-4%; the concentration range of potassium hydroxide solution is 0.5-1.0 mol / L.

[0005] Further, the high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution; wherein, the weight ratio of the high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution is 1:1~2:40~100:150~200; The weight ratio of the alkaline tailings, quicklime, and potassium hydroxide solution is 1:1~1.5:1~1.5; Furthermore, the concentration of the Tris-HCl solution is 45~55 mmol / L; The mass fraction of calcium chloride solution is 2-3%.

[0006] The concentration range of potassium hydroxide solution is 0.5~1.0 mol / L.

[0007] Furthermore, the high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution; wherein the weight ratio of the high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution is 1:1~2:40~100:150~200; The weight ratio of the alkaline tailings, quicklime, and potassium hydroxide solution is 1:1~1.5:1~1.5; And the concentration of the Tris-HCl solution was 50 mmol / L; The calcium chloride solution has a mass fraction of 2.5%.

[0008] The alkaline tailings mentioned above are selected from lead tailings, iron tailings, copper tailings, and tungsten tailings.

[0009] This invention also provides a method for preparing the above-mentioned microencapsulated high-alkalinity excipient, comprising the following steps: 1) Weigh the alkaline tailings, quicklime, and potassium hydroxide solution according to the above weight ratio; 2) Grind the alkaline tailings into powder using a ball mill, then mix the ball-milled alkaline tailings particles with quicklime, and finally add them to a potassium hydroxide solution and stir until homogeneous to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After completion, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient. 4) Weigh the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution according to the above weight ratio; 5) Add sodium alginate to the Tris-HCl solution and stir to mix thoroughly for the first time; a first mixed solution containing sodium alginate is obtained, and the mass fraction of sodium alginate in the first mixed solution is 2.0~2.5%; 6) Add high-alkalinity excipients to the first mixed solution and stir and mix for a second time to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. After standing and hardening, the microcapsules were collected, washed, and microencapsulated high alkalinity excipient was obtained.

[0010] Furthermore, in step 2), the particle size of the alkaline tailings ball milling particles is ≤100μm.

[0011] Furthermore, the particle size of the high-alkalinity excipients is ≤100μm.

[0012] Furthermore, in step 5), the conditions for the first stirring are: The stirring temperature was 30℃, the stirring speed was 300 r / min, and the stirring time was 1 hour.

[0013] The conditions for the second stirring are: The stirring temperature was 30℃, the stirring speed was 250 r / min, and the stirring time was 1 h.

[0014] Furthermore, in step 6), the static hardening temperature is 20°C and the time is 30 minutes; The microcapsule particle size of the microencapsulated high-alkalinity excipient is 450μm~550μm.

[0015] This invention also provides a method for preparing highly alkaline earthworm castings fertilizer, comprising the following steps: a. Earthworm compost is prepared by aerobic fermentation of cow dung and crushed straw, wherein... b. Mix microencapsulated high-alkalinity additives into the earthworm composting raw materials, and inoculate with Eisenia fetuses (Eisenia rubra). Eisenhower stinky The environmental temperature and humidity are controlled during vermicomposting (the vermicomposting method is one-time feeding and overall harvesting, and the entire vermicomposting process must be completed within 30 days); among which, the amount of microencapsulated high-alkalinity additives mixed into the vermicomposting raw materials is 25~35%; c. After the earthworm composting is completed, promptly separate the earthworms and collect the earthworm castings to obtain highly alkaline earthworm casting fertilizer.

[0016] Furthermore, in step a, the pH value of the earthworm compost material is 6.5~7.5, the carbon-to-nitrogen ratio (C / N) is 20~30:1, and the moisture content is 60%~70%. In step b, the inoculation amount of Eisenia fetida is 15-30g earthworms / kg earthworm compost material.

[0017] The above-mentioned earthworm composting raw materials are prepared as follows: a. Dry fresh cow dung for 1-2 days, while simultaneously crushing corn stalks, wheat stalks, or rice stalks to 1-3 cm; b. Mix cow dung and straw evenly at a weight ratio of 60%~70%: 30%~40%, adjust the moisture content to 60%~65%, and pile for 15~20 days until the raw material turns dark brown, has no obvious odor, and the straw fiber softens and becomes brittle.

[0018] The beneficial effects of this invention are: 1. Compared with traditional vermicomposting technology, this invention, by microencapsulating the auxiliary materials and controlling the vermicomposting conditions, introduces alkaline tailings into the vermicomposting process while ensuring earthworm activity and vermicomposting efficiency, thus realizing the resource utilization of alkaline tailings.

[0019] 2. Compared with traditional vermicompost fertilizer, the product prepared by this invention has a higher alkalinity. When applied to acidic soil, the product can effectively neutralize hydrogen ions in the soil, exert a precise acid reduction and long-lasting acid suppression effect, and improve its beneficial effects in acidic soil.

[0020] 3. Compared with alkaline tailings, this invention uses the process of earthworms to couple minerals and organic matter, resulting in an acidic soil amendment product that also has fertilization function. After application, it can quickly improve the acidic environment of the soil, restore soil structure and nutrient availability, and alleviate problems such as soil compaction and plant toxicity caused by the application of alkaline tailings alone.

[0021] 4. The high alkalinity earthworm castings prepared by this invention have the dual functions of reducing acidity and improving fertility. The high content of active silicon, calcium and potassium can effectively address the problem of loss of silicon, calcium and potassium in acidic soils. When applied to acidic soils, it can significantly improve crop yield and quality.

[0022] 5. The preparation method of the present invention is simple to operate, has a stable process, is suitable for large-scale industrial production, and can provide a large amount of high-quality, high-alkalinity earthworm castings fertilizer for agricultural production. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can understand it.

[0024] Example 1 The preparation method of microencapsulated high-alkalinity excipient 1 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1:2; wherein the concentration of potassium hydroxide solution is 0.5 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh out the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution according to the above weight ratio of 1:1.5:70:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30°C and 300 r / min to mix thoroughly; a first mixed solution containing sodium alginate was obtained, and the mass fraction of sodium alginate in the first mixed solution was 2.2%; 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient 1 with a particle size of 450μm-550μm was obtained.

[0025] Example 2 The preparation method of microencapsulated high-alkalinity excipient 2 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1.5:2; wherein the concentration of potassium hydroxide solution is 0.5 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh out the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution according to the above weight ratio of 1:1.5:70:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30℃ and 300 r / min to mix thoroughly; a first mixed solution containing sodium alginate was obtained, and the mass fraction of sodium alginate in the first mixed solution was 2.2%; 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient 2 with a particle size of 450μm-550μm was obtained.

[0026] Example 3 The preparation method of microencapsulated high-alkalinity excipient 3 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1.5:2; wherein the concentration of potassium hydroxide solution is 1.0 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh out the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution in the above weight ratio of 1:1.5:70:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30℃ and 300 r / min to mix thoroughly; a first mixed solution containing sodium alginate was obtained, and the mass fraction of sodium alginate in the first mixed solution was 2.2%; 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient 3 with a particle size of 450μm-550μm was obtained.

[0027] Example 4 The preparation method of microencapsulated high-alkalinity excipient 4 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1.5:2; wherein the concentration of potassium hydroxide solution is 1.0 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution according to the above weight ratio of 1:1.5:60:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30°C and 300 r / min to mix thoroughly; a first mixed solution containing sodium alginate was obtained, and the mass fraction of sodium alginate in the first mixed solution was 2.5%; 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient 4 with a particle size of 450μm-550μm was obtained.

[0028] Comparative Example 1 The preparation method of microencapsulated high-alkalinity excipient D1 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:3:2; wherein the concentration of potassium hydroxide solution is 0.5 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh out the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution in the above weight ratio of 1:1.5:70:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30℃ and 300 r / min to mix thoroughly; a first mixed solution containing sodium alginate was obtained, and the mass fraction of sodium alginate in the first mixed solution was 2.2%; 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient D1 with a particle size of 450μm-550μm was obtained.

[0029] Comparative Example 2 The preparation method of microencapsulated high-alkalinity excipient D2 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1:2; wherein the concentration of potassium hydroxide solution is 2.5 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh out the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution in the above weight ratio of 1:1.5:70:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30℃ and 300 r / min to mix thoroughly; a first mixed solution containing sodium alginate was obtained, and the mass fraction of sodium alginate in the first mixed solution was 2.2%; 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient D2 with a particle size of 450μm-550μm was obtained.

[0030] Comparative Example 3 The preparation method of microencapsulated high-alkalinity excipient D3 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1:2; wherein the concentration of potassium hydroxide solution is 0.5 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution according to the above weight ratio of 1:1.5:30:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30°C and 300 r / min to obtain a first mixed solution containing sodium alginate, with a mass fraction of 5.0% for sodium alginate. 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient D3 with a particle size of 400μm-600μm was obtained.

[0031] Comparative Example 4 The preparation method of microencapsulated high-alkalinity excipient D4 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1:2; wherein the concentration of potassium hydroxide solution is 0.5 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After the reaction is completed, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient with a particle size ≤100μm. 4) Weigh out the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution according to the above weight ratio of 1:4:180:200; wherein the concentration of Tris-HCl solution is 50 mmol / L, and the mass fraction of calcium chloride solution is 2.5%; 5) Sodium alginate was added to Tris-HCl solution and stirred for 1 hour at 30℃ and 300 r / min to mix thoroughly; a first mixed solution containing sodium alginate was obtained, and the mass fraction of sodium alginate in the first mixed solution was 2.2%; 6) Add high-alkalinity excipients to the first mixed solution and stir for a second time for 1 hour at a stirring temperature of 30℃ and a stirring speed of 250 r / min to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. The mixture was allowed to stand and harden for 30 minutes at 20°C. The microcapsules were collected, washed, and microencapsulated high alkalinity excipient D4 with a particle size of 400μm-600μm was obtained.

[0032] Comparative Example 5 The preparation method of high alkalinity excipient D5 includes the following steps: 1) Weigh lead tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1:2; wherein the concentration of potassium hydroxide solution is 0.5 mol / L; 2) Grind the lead tailings into powder using a ball mill, then mix the lead tailings particles with a particle size ≤100μm with quicklime, and then add them to a potassium hydroxide solution and stir evenly to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After completion, the product is taken out, filtered, dried, and ball-milled to obtain high-alkalinity excipient D5 with a particle size ≤100μm.

[0033] In Examples 1-4 and Comparative Examples 1-5, the pH, active SiO2, active K2O, and active CaO content of the microencapsulated high-alkalinity excipients were measured during the preparation process. The average particle size, particle size range, and breakage rate of the microencapsulated high-alkalinity excipients were also measured. After obtaining the vermicompost, the changes in earthworm biomass, pH, organic matter content, total nutrient content, and seed germination rate of the vermicompost were measured. The results are as follows: Table 1. Comparison of pH, active SiO2, active K2O, and active CaO content of different microencapsulated high-alkalinity excipients

[0034] In acidic soils, the concentration of hydrogen ions is high. Hydrogen ions exchange with calcium, potassium, and other cations adsorbed on soil colloids. The exchanged calcium, potassium, and other cations are lost with soil moisture movement under conditions such as rainfall. Furthermore, aluminum and iron ions, which are abundant in acidic soils, compete with silicon ions for adsorption sites on the soil colloid surface. Silicon ions have weak adsorption capacity and are easily exchanged and lost into the soil solution. Therefore, increasing the content of active SiO2, K2O, and CaO in the additives is crucial for replenishing the lost calcium, potassium, and silicon ions in acidic soils. Table 1 shows that although the pH of the high-alkalinity additives obtained in the control example and the examples is above 11, the high-alkalinity additives obtained in Examples 1-4 all have active SiO2 content greater than 26%, active K2O content greater than 0.74%, and active CaO content greater than 14.5%, demonstrating stable properties and effectively replenishing the lost calcium, potassium, and silicon ions in acidic soils. Conversely, Comparative Examples 1 and 2, due to improper ratios of tailings to quicklime or improper concentrations of KOH solution, showed significantly lower contents of active SiO2, K2O, and CaO compared to the examples, indicating a weaker effect in replenishing calcium, potassium, and silicon ions in acidic soils.

[0035] Table 2. Average particle size, particle size range, and breakage rate of microencapsulated high-alkalinity excipients

[0036] The purpose of microencapsulation is to reduce the irritation of the earthworm's intestines by the high alkalinity of the excipients, allowing the earthworms to feed smoothly. Therefore, the average particle size and particle size uniformity of the microencapsulated high alkalinity excipients determine whether they can be well mixed with earthworm composting materials to reduce the possibility of selective feeding by earthworms. The rupture rate of the microencapsulated high alkalinity excipients affects the stability of the excipients' properties throughout the earthworm composting process. In Table 2, Comparative Example 5 did not undergo microencapsulation of the high alkalinity excipients, therefore no data is available. Except for Comparative Example 5, the average particle size of the microencapsulated high alkalinity excipients obtained in all comparative examples and examples was between 495-510 µm. However, Comparative Examples 3 and 4, due to inappropriate sodium alginate concentrations or high alkalinity excipient:sodium alginate ratios, had microcapsule particle size differences reaching 100 µm, significantly higher than the examples (difference less than 40 µm). Furthermore, the microcapsule rupture rates of Comparative Examples 3 and 4 exceeded 20%, while those of Examples 1-4 were all below 12%.

[0037] Combining the results in Tables 1 and 2, it can be seen that the microencapsulated high-alkalinity excipient preparation method of the present invention (Examples 1-4) increases the content of active SiO2, K2O, and CaO through alkali activation, and obtains microcapsules with uniform size and low microcapsule rupture rate. In contrast, the active SiO2, K2O, and CaO contents of Comparative Examples 1-2 are significantly lower than those of the Examples, and the microcapsule rupture rate of Comparative Examples 3-4 is significantly higher than that of the Examples, and none of them can achieve good microencapsulation treatment of high-alkalinity excipients.

[0038] Examples 5-8 A method for preparing a high-alkalinity vermicompost fertilizer 1-4 includes the following steps: a. Prepare vermicompost raw materials by aerobic fermentation of cow dung and crushed straw. The vermicompost raw materials have a pH of 6.5-7.5, a carbon-to-nitrogen ratio (C / N) of 20-30:1, and a moisture content of 60%-70%. The specific steps are as follows: ① Dry fresh cow dung for 1-2 days, while crushing corn stalks, wheat stalks, or rice stalks into 1-3 cm pieces; ② Mix cow dung and straw evenly at a weight percentage of 60%-70%: 30%-40%, adjust the moisture content to 60%-65%, and pile for 15-20 days until the raw material turns dark brown, has no obvious odor, and the straw fiber softens and becomes brittle.

[0039] b. Mix microencapsulated high-alkalinity additives 1-4 into the earthworm composting raw materials, and inoculate with Eisenia fetuses (Eisenia rubra). Eisenhower stinky The environmental temperature and humidity are controlled during vermicomposting (the vermicomposting method is one-time feeding and overall harvesting, and the entire vermicomposting process must be completed within 30 days); among which, the amount of microencapsulated high-alkalinity additives mixed into the vermicomposting raw materials is 30%; c. After earthworm composting is completed, promptly separate the earthworms and collect the earthworm castings to obtain 1-4% high-alkalinity earthworm casting fertilizer.

[0040] Example 9 The preparation method of the high-alkalinity vermicompost 5 in this embodiment is basically the same as that of the high-alkalinity vermicompost 1, except that: The amount of microencapsulated high-alkalinity excipient 1 mixed into the earthworm compost raw material is 35%.

[0041] Comparative Examples 6-9 The preparation methods for high-alkalinity vermicompost fertilizer d1-d4 in Comparative Examples 6-9 are basically the same as those for high-alkalinity vermicompost fertilizer 1, with the following differences: Microencapsulated high-alkalinity additives d1-d4 were mixed into the earthworm compost raw materials.

[0042] Comparative Example 10 The preparation method of high-alkalinity vermicompost fertilizer d5 in this comparative example is basically the same as the preparation method of high-alkalinity vermicompost fertilizer 1, except that: Microencapsulated high-alkalinity additive 1 was mixed into the earthworm compost raw material, and the amount of microencapsulated high-alkalinity additive 1 mixed into the earthworm compost raw material was 50%.

[0043] Comparative Example 11 The preparation method of high-alkalinity vermicompost d6 in this comparative example is basically the same as that of high-alkalinity vermicompost 1, except that: Microencapsulated high-alkalinity additive 1 was mixed into the earthworm compost raw material, and the amount of microencapsulated high-alkalinity additive 1 mixed into the earthworm compost raw material was 10%.

[0044] Comparative Example 12 The preparation method of high-alkalinity vermicompost fertilizer d7 in this comparative example is basically the same as the preparation method of high-alkalinity vermicompost fertilizer 1, except that: Microencapsulated high-alkalinity adjuvant 1 was mixed into the earthworm composting raw materials, and the earthworm composting period was 50 days.

[0045] Comparative Example 13 The preparation method of high-alkalinity vermicompost fertilizer d8 in this comparative example is basically the same as that of high-alkalinity vermicompost fertilizer 1, except that: Microencapsulated high-alkalinity additive D5 was mixed into the earthworm compost raw materials.

[0046] Comparative Example 14 High-alkalinity vermicompost D9 is obtained by directly mixing microencapsulated high-alkalinity adjuvant D5 with the material after the earthworms have passed through their digestive system, with the amount of earthworm compost raw material being 10%.

[0047] Comparative Example 15 High-alkalinity vermicompost D10 is obtained by directly mixing microencapsulated high-alkalinity adjuvant 1 with the material after the earthworms have passed through their digestive system, with the amount of earthworm compost raw material being 300%.

[0048] Table 3. Changes in earthworm biomass and the pH, organic matter content, total nutrient content, and seed germination rate of earthworm castings.

[0049] The purpose of this invention is to introduce alkaline tailings into vermicomposting to prepare highly alkaline vermicompost. The feeding and excretion behaviors of earthworms are crucial to vermicomposting, and changes in earthworm biomass are an important indicator of the success of vermicomposting. Comparative Examples 14 and 15 did not involve the vermicomposting process, therefore no corresponding data are available.

[0050] Table 3 shows that after vermicomposting, the earthworm biomass in the examples nearly doubled compared to before composting, indicating that the vermicomposting process proceeded smoothly and that good earthworm protein production was achieved after composting. Furthermore, the pH of the vermicompost obtained in the examples was consistently above 8.5, significantly higher than that of traditional vermicompost (usually between 6.5 and 7.5), indicating that the vermicompost obtained in the examples possesses a certain acid-lowering function. The organic matter content of the vermicompost obtained in the examples was consistently above 36%, the total nutrient content was consistently above 4.7%, and the seed germination rate was consistently above 74%, meeting the requirements of the corresponding indicators in NY525.

[0051] In contrast, both Comparative Examples 10 and 13 showed a decrease in earthworm biomass, indicating that the materials adversely affected the earthworms and caused their death, preventing the earthworm composting process from starting. The reasons for this are as follows: Comparative Example 10 added an excessive amount of microencapsulated high-alkalinity additives, making the material unsuitable for earthworm consumption; Comparative Example 13 did not microencapsulate the high-alkalinity additives, and the high-alkalinity characteristics of the additives directly led to earthworm death. Comparative Example 12 had an excessively long earthworm composting time, causing the microencapsulated high-alkalinity additives to rupture later, adversely affecting the earthworms and leading to their death. Comparative Examples 6, 7, 8, and 9 showed no significant change in earthworm biomass, indicating low earthworm composting efficiency and limiting the production of earthworm products. In particular, the germination index of the earthworm castings obtained in Comparative Examples 8 and 9 did not meet the requirements of NY525. In Comparative Example 11, the amount of microencapsulated high-alkalinity additive added was too low. Although vermicomposting proceeded smoothly and the earthworm castings showed good organic matter, total nutrients, and germination index, its pH was only 7.7, which is inconsistent with the purpose of this invention in preparing high-alkalinity earthworm castings fertilizer. In Comparative Example 14, the high-alkalinity additive was directly mixed in, and the additive came into direct contact with the seeds, resulting in a germination index that did not meet the requirements. The product obtained in Comparative Example 15 had similar properties to the examples, but it did not undergo the earthworm digestion process; instead, it was a simple mixing process of traditional earthworm castings and microencapsulated high-alkalinity additives.

[0052] To meet the NY525 requirement of a seed germination index ≥70%, earthworm castings products from Comparative Examples 6, 11, and 15, and Examples 5-9, along with traditional earthworm castings and high-alkalinity tailings powder, were selected for pot experiments. A control (CK) without any materials was also included for comparison. Soil samples were collected from Xianning, Hubei Province, with a pH of 4.8, an organic matter content of 12.8 g / kg, and available nitrogen, phosphorus, and potassium contents of 42.1 g / kg, 11.2 mg / kg, and 112 mg / kg, respectively. Each material was mixed with the soil at 10% of its content, and the soil moisture content was adjusted to 23%. Two Shanghai bok choy seedlings with 2-3 true leaves were transplanted and potted in a greenhouse for 30 days before harvest. After the Shanghai bok choy harvest, two more seedlings were transplanted for a second crop to verify the product's long-lasting acid-suppressing effect. Plant and soil-related indicators were measured at both Shanghai bok choy harvests. The results are as follows: Table 4 Soil acidity and acid buffering capacity

[0053] Table 4 shows that, compared to the control (CK), the high-alkalinity vermicompost prepared in the examples significantly increased soil pH, reduced exchangeable acid content, and enhanced soil acid-base buffering capacity during the first crop planting. Furthermore, the high-alkalinity vermicompost had a long-lasting acid-suppressing effect; after the second crop planting, the soil did not show significant acidification, with a pH decrease of no more than 0.5 pH values. In contrast, direct application of high-alkalinity tailings powder showed the strongest acid-reducing ability during the first crop planting, but its effect was not sustained, with a soil pH decrease of 1.3 pH values ​​after the second crop planting. Comparative Example 15 performed worse than the examples in terms of long-lasting acid suppression, with a soil pH decrease of 0.9 pH values ​​after the second crop planting. Traditional vermicompost and the vermicompost prepared in Comparative Example 11, due to their inherently low pH, did not show any effect on improving soil acidity. Although Comparative Example 6 could maintain soil pH within a small range of fluctuation, the soil acid-base buffering capacity under its application was significantly lower than that of the examples.

[0054] Table 5 Soil Nutrient Status

[0055] Table 5 shows that, compared to the control (CK), the application of the high-alkalinity vermicompost prepared in the examples significantly improved soil nutrient content. This is partly due to the abundant readily available nutrients in vermicompost itself, and partly due to the increased soil pH and activation of fixed nutrients after application. Furthermore, the high-alkalinity vermicompost prepared in the examples has a good continuous nutrient supply capacity; as the organic matter in the manure continues to mineralize, it continuously replenishes the soil with nutrients that can be absorbed and utilized by crops. In contrast, the application of high-alkalinity tailings powder has virtually no ability to enrich the soil, and its soil nutrient content is almost the same as that of the control (CK) soil. The application of traditional vermicompost and the vermicompost prepared in Comparative Example 11 can supplement some readily available nutrients in the soil, but because they do not significantly improve soil acidity, they fail to effectively activate fixed nutrients in the soil, specifically resulting in a significantly lower readily available phosphorus content than in the examples. The effects of the products prepared in Comparative Examples 6 and 15 on soil nutrients are similar to those in the examples.

[0056] Table 6. Plant height, number of leaves, and biomass of Shanghai green plants

[0057] Table 6 shows that, compared to the control (CK), the application of the high-alkalinity vermicompost prepared in the examples significantly improved the growth of Shanghai bok choy, showing significantly higher plant height, leaf number, and biomass than other treatments in both crop cycles. The growth-promoting effect of the high-alkalinity vermicompost prepared in the examples on Shanghai bok choy is sustainable; even without repeated application of manure before the second crop, none of the Shanghai bok choy indicators showed a significant decline. In contrast, the vermicompost prepared in Comparative Example 11, traditional vermicompost, and high-alkalinity tailings powder did not significantly promote the growth of Shanghai bok choy compared to the control (CK). The promoting effect of Comparative Example 6 on Shanghai bok choy in both crop cycles was significantly lower than that in the examples. The vermicompost prepared in Comparative Example 15 showed the same performance as the examples in the first crop cycle, but the growth-related indicators of Shanghai bok choy significantly decreased in the second crop cycle, indicating that its effect was not sustainable.

[0058] In summary, the high-alkalinity vermicompost fertilizer prepared by this invention possesses the triple effects of precise acid reduction, long-lasting acid suppression, and soil fertilization. Compared with traditional vermicompost fertilizers and high-alkalinity mineral application, this product can significantly promote crop growth in acidic soils and achieve higher yields. Comparison of the examples and embodiments shows that the preparation of the high-alkalinity vermicompost fertilizer of this invention must be carried out in accordance with all the technical points required by this invention. Any change to any technical point will lead to a decrease in the effectiveness of the obtained vermicompost fertilizer in precisely reducing acidity, long-lasting acid suppression, or sustainably promoting crop growth.

[0059] All other parts not described in detail are existing technologies. Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A microencapsulated high-alkalinity excipient, characterized in that: Its raw materials include high alkalinity excipients, sodium alginate, Tris-HCl solution and calcium chloride solution; wherein, the weight ratio of the high alkalinity excipients, sodium alginate, Tris-HCl solution and calcium chloride solution is 1:1~3:40~150:150~200; The raw materials for the high alkalinity auxiliary material are composed of alkaline tailings, quicklime, and potassium hydroxide solution in a weight ratio of 1:1~2:1~2; and the concentration of the Tris-HCl solution is 40~60 mmol / L. The mass fraction of calcium chloride solution is 2-4%; the concentration range of potassium hydroxide solution is 0.5-1.0 mol / L.

2. The microencapsulated high-alkalinity excipient according to claim 1, characterized in that: The high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution; wherein the weight ratio of the high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution is 1:1~2:40~100:150~200; The weight ratio of the alkaline tailings, quicklime, and potassium hydroxide solution is 1:1~1.5:1~1.5; Furthermore, the concentration of the Tris-HCl solution is 45~55 mmol / L; The mass fraction of calcium chloride solution is 2-3%; The concentration range of potassium hydroxide solution is 0.5~1.0 mol / L.

3. The microencapsulated high-alkalinity excipient according to claim 1, characterized in that: The high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution; wherein the weight ratio of the high alkalinity excipient, sodium alginate, Tris-HCl solution, and calcium chloride solution is 1:1~2:40~100:150~200; The weight ratio of the alkaline tailings, quicklime, and potassium hydroxide solution is 1:1~1.5:1~1.5; The concentration of the Tris-HCl solution was 50 mmol / L, and the mass fraction of the calcium chloride solution was 2.5%.

4. A method for preparing the microencapsulated high-alkalinity excipient according to claim 1, characterized in that: Includes the following steps: 1) Weigh the alkaline tailings, quicklime, and potassium hydroxide solution according to the above weight ratio; 2) Grind the alkaline tailings into powder using a ball mill, then mix the ball-milled alkaline tailings particles with quicklime, and finally add them to a potassium hydroxide solution and stir until homogeneous to obtain a mixed slurry; 3) The mixed slurry is placed in a high-pressure digestion tank for hydrothermal reaction. After completion, the product is taken out, filtered, dried, and ball-milled to obtain a high-alkalinity excipient. 4) Weigh the high-alkalinity excipients, sodium alginate, Tris-HCl solution, and calcium chloride solution according to the above weight ratio; 5) Add sodium alginate to the Tris-HCl solution and stir to mix thoroughly for the first time; a first mixed solution containing sodium alginate is obtained, and the mass fraction of sodium alginate in the first mixed solution is 2.0~2.5%; 6) Add high-alkalinity excipients to the first mixed solution and stir and mix for a second time to obtain the second mixed solution; 7) The second mixture of the above-mentioned high alkalinity excipient and sodium alginate was added dropwise to calcium chloride solution to microencapsulate the high alkalinity excipient. After standing and hardening, the microcapsules were collected, washed, and microencapsulated high alkalinity excipient was obtained.

5. The preparation method according to claim 4, characterized in that: In step 2), The particle size of alkaline tailings ball milled particles is ≤100μm.

6. The preparation method according to claim 4, characterized in that: In step 3), the particle size of the high-alkalinity auxiliary material is ≤100μm.

7. The preparation method according to claim 4, characterized in that: In step 5), the conditions for the first stirring are: The stirring temperature was 30℃, the stirring speed was 300 r / min, and the stirring time was 1 hour. The conditions for the second stirring are: The stirring temperature was 30℃, the stirring speed was 250 r / min, and the stirring time was 1 h.

8. The preparation method according to claim 4, characterized in that: In step 6), the temperature for static hardening is 20°C and the time is 30 minutes. The microcapsule particle size of the microencapsulated high-alkalinity excipient is 450μm~550μm.

9. A method for preparing high-alkalinity vermicompost fertilizer, characterized in that: Includes the following steps: a. Earthworm compost is prepared by aerobic fermentation of cow dung and crushed straw, wherein... b. Mix microencapsulated high-alkalinity additives into the earthworm composting raw materials, inoculate with Eisenia fetidae, control the ambient temperature and humidity, and carry out earthworm composting; wherein, the amount of microencapsulated high-alkalinity additives mixed into the earthworm composting raw materials is 25-35%; c. After the earthworm composting is completed, promptly separate the earthworms and collect the earthworm castings to obtain highly alkaline earthworm casting fertilizer.

10. The preparation method according to claim 9, characterized in that: In step a, the earthworm compost raw material has a pH value of 6.5-7.5, a carbon-to-nitrogen ratio of 20-30:1, and a moisture content of 60%-70%. In step b, the inoculation amount of Eisenia fetida is 15-30g earthworms / kg earthworm compost material.

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