A method for extracting water-soluble organic phosphorus-silicon fertilizer from coarse fiber organic waste

Abstract

The present application belongs to the field of agricultural waste resource utilization and fertilizer raw material preparation technology, and particularly relates to a method for extracting water-soluble organic phosphorus-silicon fertilizer from coarse-fiber organic waste. The method comprises: pretreating the organic waste, uniformly mixing the obtained organic waste reaction matrix with an alkaline activator and water, heating the obtained mixed suspension system to perform an activation reaction, obtaining an activation system stock solution, adding a phosphorus source reagent to the activation system stock solution which is lowered to room temperature, adjusting the pH of the reaction system, and then heating to perform a modification reaction, thereby obtaining the water-soluble organic phosphorus-silicon fertilizer. The method realizes the synergistic water-soluble conversion of silicon and phosphorus in coarse-fiber organic waste, has a high silicon water-soluble conversion rate, and greatly reduces the process energy consumption compared with traditional methods. The prepared product is suitable for water-fertilizer integrated scenarios, and the preparation process does not discharge pollutants, has the advantages of resource recycling and green environmental protection, and is suitable for large-scale industrial application.

Description

Technical Field

[0001] This invention belongs to the field of agricultural waste resource utilization and fertilizer raw material preparation technology, specifically relating to a method for extracting water-soluble organic phosphorus and silicon fertilizer from crude fiber organic waste. Background Technology

[0002] Corn stalks, wheat stalks, rice stalks, peanut shells, and waste wood chips are coarse-fiber organic wastes that are produced in large quantities during my country's agricultural production. These resources are abundant, inexpensive to obtain, and possess extremely high resource utilization value. These wastes are naturally rich in essential plant nutrients such as silicon, phosphorus, calcium, carbon, and nitrogen. Silicon content can reach 5%-15% of the waste's dry weight, and phosphorus content is 0.1%-0.5%, making them excellent natural carriers of phosphorus-silicon composite raw materials. If efficient resource conversion can be achieved, they can effectively replace traditional chemically synthesized agricultural fertilizer raw materials, contributing to the green and low-carbon development of agriculture.

[0003] Currently, the industry's resource utilization methods for coarse fiber organic waste mainly focus on conventional pathways such as direct return to the field, high-temperature carbonization, and microbial fermentation. However, all of these technologies have obvious defects and application limitations. In the direct return of straw to the field mode, the natural degradation cycle of waste such as straw is long and the decomposition efficiency is low. Moreover, the phosphorus and silicon elements in the material are mostly in the form of stable and insoluble silicates, which cannot be quickly absorbed and utilized by crop roots, resulting in extremely low nutrient utilization. Traditional high-temperature carbonization process can only produce conventional carbon-based silicon fertilizer, and the water-soluble conversion efficiency of silicon in straw is less than 30%, resulting in poor conversion effect. In addition, the high-temperature carbonization process only focuses on the activation of silicon element and cannot achieve the simultaneous fixation and water-soluble conversion of phosphorus element, making it difficult to form a phosphorus-silicon synergistic nutrient system. Conventional chemical extraction process often uses high-concentration strong alkali and ultra-high temperature reaction conditions to enhance the dissolution of silicon element. Although it improves the silicon extraction rate to a certain extent, it is very easy to cause the loss of valuable nutrients such as phosphorus in the system. Furthermore, the phosphorus and silicon components in the final product cannot combine to form a stable water-soluble complex, which is prone to precipitation and stratification during storage, making it unsuitable for modern water-saving agricultural application scenarios such as drip irrigation, sprinkler irrigation, and fertigation.

[0004] In addition, existing straw-based phosphate and silicon fertilizer preparation technologies generally suffer from industry pain points such as incomplete technical systems and unstable product performance. Most technical solutions neglect the core technical requirements of synergistic fixation and simultaneous water solubility of phosphorus and silicon, resulting in nutrient imbalance in the prepared products. On the one hand, this leads to adequate effective silicon content but a lack of effective phosphorus nutrients; on the other hand, it results in poor binding stability of phosphorus and silicon components, making them prone to precipitation and failure, failing to meet the production needs of modern agriculture for balanced and long-term supply of dual nutrients. At the same time, existing straw-based phosphate and silicon fertilizers lack a sound quality control system, with neither clear standards for heavy metal content control nor quantitative data supporting nutrient storage stability. This leads to inconsistent product quality, posing potential safety hazards in agricultural production and severely limiting the large-scale and industrialized promotion and application of this type of fertilizer.

[0005] Water-soluble organic phosphorus and silicon fertilizers, as a new type of high-quality agricultural fertilizer, can simultaneously supplement crops with phosphorus and silicon, two core nutrients. They effectively promote root development, strengthen plant resistance to lodging, pests and diseases, and enhance stress resistance. Furthermore, their water-soluble properties are perfectly suited to water-saving agricultural systems. Currently, most water-soluble phosphorus and silicon fertilizers on the market rely on pure chemical raw materials for synthesis, resulting in high production costs, high energy consumption, and significant environmental pressure. At the same time, they fail to achieve the synergistic and efficient extraction and high-value utilization of natural phosphorus and silicon resources from agricultural waste, leading to low resource utilization and poor economic benefits.

[0006] In summary, current technologies for the resource utilization of coarse fiber organic waste suffer from numerous drawbacks, including low phosphorus-silicon conversion efficiency, poor nutrient synergy, high energy consumption, insufficient product stability, and poor environmental friendliness. There is a lack of a mild, low-energy, green, and pollution-free preparation technology that can simultaneously achieve efficient water-soluble conversion of phosphorus and silicon in waste, and produce products with balanced nutrients, strong stability, and safety compliance. Therefore, developing a method for preparing water-soluble organophosphorus and silicon fertilizers based on coarse fiber organic waste that is suitable for large-scale production and meets the needs of modern agricultural development is of significant practical importance and industrial value for promoting the high-value recycling of agricultural waste, reducing fertilizer production costs, and developing green and ecological agriculture. Summary of the Invention

[0007] Based on the above technical background, the main objective of this invention is to provide a method for extracting water-soluble organic phosphorus and silicon fertilizer from crude fiber organic waste, so as to overcome the problems of low phosphorus and silicon conversion efficiency, asynchronous conversion, poor nutrient synergy, low water-soluble conversion rate, high process energy consumption, and insufficient product stability in the existing technology.

[0008] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0009] This invention provides a method for extracting water-soluble organophosphorus and silicon fertilizers from coarse fiber organic waste, the method comprising the following steps: Step 1: Crush, sieve, homogenize, and dry the organic waste to obtain the organic waste reaction matrix; Step 2: Mix the organic waste reaction matrix with the alkaline activator, then add water and mix evenly. Heat the resulting mixed suspension system to carry out the activation reaction and obtain the activated system stock solution. Step 3: Add phosphorus source reagent to the activated system stock solution that has cooled to room temperature, then add acid-base regulator to adjust the pH of the reaction system, and then heat up to carry out the modification reaction to obtain water-soluble organic phosphorus-silicon fertilizer.

[0010] The steps described above are described in detail below.

[0011] In step 1, the organic waste is selected from one or more of the following: corn stalks, wheat stalks, rice stalks, peanut shells, and waste wood chips.

[0012] Preferably, the organic waste is selected from one or more of corn stalks, wheat stalks, and rice stalks.

[0013] More preferably, the organic waste is obtained by mixing corn stalks, wheat stalks and rice stalks in a mass ratio of (2-4):(1-2):5.

[0014] For example, the organic waste is obtained by mixing corn stalks, wheat stalks and rice stalks in a mass ratio of 3:2:5.

[0015] The crushed organic waste is sieved to obtain granular organic waste with a particle size of 80-180 mesh.

[0016] Preferably, the crushed organic waste is sieved to obtain granular organic waste with a particle size of 100-160 mesh.

[0017] More preferably, the crushed organic waste is screened to obtain granular organic waste with a particle size of 120-160 mesh.

[0018] Homogenize the granular organic waste at 85–120°C for 10–45 minutes.

[0019] Preferably, the granular organic waste is homogenized at 100°C for 30 minutes.

[0020] The homogenized organic waste granules are dried at 60–110°C for 2–7 hours.

[0021] Preferably, the homogenized organic waste granules are dried at 70–100°C for 4–6 hours.

[0022] More preferably, the homogenized organic waste granules are dried at 80–100°C for 6 hours.

[0023] Through pretreatment processes such as crushing, sieving, homogenization, and drying, organic waste can form a regular microstructure and initial pore structure, thereby achieving homogenization of the organic waste precursor structure and providing a stable and uniform reaction matrix for subsequent alkali-promoted phosphorus silicon lattice reconstruction activation and directional phosphorus doping functionalization reactions.

[0024] In step 2, the organic waste reaction matrix and alkaline activator are mixed at a mass ratio of 1: (1-5), and then water is added to prepare a mixed suspension system with a solid-liquid ratio of 1: (5-20).

[0025] Preferably, the organic waste reaction matrix and the alkaline activator are mixed at a mass ratio of 1:(2-4), and then water is added to prepare a mixed suspension system with a solid-liquid ratio of 1:(5-15).

[0026] More preferably, the organic waste reaction matrix and the alkaline activator are mixed at a mass ratio of 1:4, and then water is added to prepare a mixed suspension system with a solid-liquid ratio of 1:15.

[0027] The alkaline activator is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide.

[0028] Preferably, the alkaline activator is selected from one or two of tetramethylammonium hydroxide and tetraethylammonium hydroxide.

[0029] More preferably, the alkaline activator is obtained by mixing tetramethylammonium hydroxide and tetraethylammonium hydroxide in a mass ratio of 1:(2-4).

[0030] For example, the alkaline activator is obtained by mixing tetramethylammonium hydroxide and tetraethylammonium hydroxide in a mass ratio of 1:3.

[0031] Before adding the alkaline activator to the organic waste reaction matrix, the alkaline activator must first be prepared into an alkaline aqueous solution with a mass concentration of 2-5 mol / L before being added to the organic waste reaction matrix.

[0032] Preferably, before adding the alkaline activator to the organic waste reaction matrix, the alkaline activator should be prepared into an alkaline aqueous solution with an alkaline concentration of 3 mol / L before being added to the organic waste reaction matrix.

[0033] Under continuous stirring conditions of 300–700 r / min, the resulting mixed suspension system was heated to 300–600 °C at a heating rate of 3–8 °C / min for activation reaction, and the activation reaction time was 1–5 h.

[0034] Preferably, under continuous stirring at 350–600 r / min, the obtained mixed suspension system is heated to 300–550°C at a heating rate of 3–5°C / min for activation reaction, and the activation reaction time is 2–4 h.

[0035] More preferably, under continuous stirring conditions of 450–600 r / min, the obtained mixed suspension system is heated to 550°C at a heating rate of 5°C / min for activation reaction, and the activation reaction time is 4 h.

[0036] During the activation reaction, the concentration of the alkaline solution, the activation temperature, and the activation time all affect the progress and outcome of the activation reaction. If the alkaline concentration is too low, the activation temperature is insufficient, or the activation time is too short, the lattice etching of the organic waste reaction matrix will be incomplete, and the pore development will be inadequate. Conversely, if the alkaline concentration is too high, the activation temperature is too high, or the activation time is too long, the organic waste reaction matrix framework may collapse and its structure may be damaged. Through precise control of these parameters and their synergistic effect, the dissociation of the phosphorus-silicon lattice and framework reconstruction in the organic waste reaction matrix can be achieved, enabling the in-situ generation of a multi-level porous structure and significantly increasing the specific surface area and the number of active sites in the final agricultural fertilizer material.

[0037] In step 3, the phosphorus source reagent is selected from one or more of hydroxyethylidene diphosphonic acid, ammonium polyphosphate, potassium pyrophosphate, sodium pyrophosphate, sodium tripolyphosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate.

[0038] Preferably, the phosphorus source reagent is selected from one or two of ammonium polyphosphate and potassium pyrophosphate.

[0039] More preferably, the phosphorus source reagent is ammonium polyphosphate.

[0040] Add phosphorus source reagent to the activated system stock solution cooled to room temperature. The mass ratio of phosphorus source reagent to activated system stock solution is (0.2-1.2):1.

[0041] Preferably, the mass ratio of the phosphorus source reagent to the original activation system solution is (0.5~1.0):1.

[0042] More preferably, the mass ratio of the phosphorus source reagent to the original activation system solution is 1:1.

[0043] After adjusting the pH of the reaction system to 4-8 by adding an acid-base regulator, the reaction system is heated to 150-250℃ under continuous stirring at a speed of 400-500 r / min. The modification reaction is carried out at this temperature for 2-6 hours to complete the slow-release crosslinking interface modification of organophosphorus compounds.

[0044] Preferably, after adjusting the pH of the reaction system to 5-7 by adding an acid-base regulator, the reaction system is heated to 180-220°C under continuous stirring at a stirring speed of 400-450 r / min, and the modification reaction is carried out at this temperature for 3-5 hours to complete the organophosphorus slow-release crosslinking interface modification.

[0045] More preferably, after adjusting the pH of the reaction system to 7 by adding an acid-base regulator, the reaction system is heated to 220°C under continuous stirring at a stirring speed of 450 r / min, and the modification reaction is carried out at this temperature for 5 h to complete the organophosphorus slow-release crosslinking interface modification.

[0046] The acid-base regulator is selected from one or more of hydrochloric acid, phosphoric acid, oxalic acid, sodium bicarbonate, and ammonia water.

[0047] Before the modification reaction, an acid-base regulator must be added to adjust the pH of the reaction system to the range specified in this application before heating can begin. If the pH is too low, the phosphorus component will rapidly agglomerate and precipitate; if the pH is too high, it will inhibit the bonding reaction of the phosphorus-silicon functional groups. Simultaneously, abnormal reaction temperatures can also result in insufficient slow-release crosslinking interface modification or excessive surface loading. This step, through precise control of the system pH and reaction parameters, enables the directional anchoring and covalent bonding of phosphorus-silicon lattice active groups in the pores and surface of the final agricultural fertilizer material. This allows for uniform and stable organophosphorus-silicon functionalization modification of the agricultural fertilizer material, avoiding problems such as physical adsorption and uneven doping; ultimately producing a resource-recyclable, water-soluble organic phosphorus-silicon agricultural fertilizer.

[0048] The beneficial effects of this invention are as follows: (1) The method described in this invention achieves synergistic water-soluble conversion of phosphorus and silicon nutrients, significantly improving nutrient utilization and completely solving the shortcomings of traditional agricultural fertilizer preparation methods, such as single nutrient content and unstable binding. This invention uses an alkaline-promoted lattice reconstruction activation process to precisely etch the lattice structure of straw-like coarse fiber organic waste, constructing a multi-level porous structure in situ in this type of organic waste, which greatly increases the specific surface area and active sites of the material. Combined with the addition and modification reaction of phosphorus source reagent, phosphorus elements are stably bonded to the silicon lattice through covalent bonds, rather than the simple physical adsorption of traditional processes, effectively avoiding the precipitation, sedimentation, and stratification of phosphorus and silicon nutrients. The silicon water-soluble conversion rate of the extraction method of this invention can reach more than 65%, which is much higher than the silicon conversion efficiency of less than 30% of the traditional carbonization process. The effective phosphorus (calculated as P2O5) content of the prepared agricultural fertilizer can reach more than 10%, and the effective silicon (calculated as SiO2) content can reach more than 11%. The nutrient content is excellent and balanced. The prepared agricultural fertilizer can simultaneously supply crops with dual core nutrients of phosphorus and silicon, effectively promote crop root growth, enhance the plant's resistance to lodging, pests and diseases, and stress resistance, and significantly improve crop yield and quality.

[0049] (2) By optimizing core process parameters such as activation temperature, heating rate, and solid-liquid ratio, this invention reduces overall process energy consumption by 30% to 40% compared to traditional strong alkali high-temperature extraction processes. The process conditions are mild and controllable, making it suitable for large-scale industrial production. Furthermore, this preparation method produces no pollutants such as waste gas, wastewater, or waste residue. Using agricultural waste such as straw, peanut shells, and waste wood chips as raw materials, it achieves resource utilization and high-value recycling of agricultural and forestry solid waste. It can replace traditional high-cost chemical raw material synthesis processes, significantly reducing the energy consumption and raw material costs of water-soluble phosphorus-silicon agricultural fertilizer production.

[0050] (3) The chromium, cadmium, lead, mercury and arsenic content of the agricultural fertilizer product prepared by the method strictly complies with the national standard GB / T 17420-2021 "Organic-Inorganic Compound Fertilizer". The risk of heavy metal accumulation is extremely low and it is suitable for green organic agricultural production scenarios. At the same time, the agricultural fertilizer product has excellent storage stability. After 12 months of storage under normal temperature and humidity conditions, the retention rate of effective phosphorus and effective silicon components is ≥95%. Even under long-term storage in complex climatic environments such as low temperature and high humidity in the south and high temperature and low humidity in the north, it can still maintain an effective component retention rate of more than 93% and a water solubility rate of more than 96%. It is not easy to clump and become ineffective, and it is suitable for the storage and use needs of different regions across the country. In addition, the water-soluble organic phosphorus and silicon agricultural fertilizer prepared by this invention has a water solubility rate of 80% to 98% and no insoluble residue. It is suitable for water and fertilizer integration modern agricultural application scenarios such as drip irrigation, sprinkler irrigation and foliar spraying, and solves the industry problem that traditional straw-based fertilizers have poor solubility and cannot be used for water-saving irrigation.

[0051] (4) This invention can not only prepare high-quality phosphorus-silicon fertilizers using single straw raw materials such as rice, corn, and wheat, but also achieve compound production of various coarse fiber wastes. The straw compound system can further improve the water-soluble conversion rate of silicon and reduce the risk of heavy metal accumulation, resulting in fertilizer products with superior performance. At the same time, by precisely controlling the process parameters during the preparation process, the method can prepare different types of water-soluble phosphorus-silicon fertilizers and compound fertilizers, such as foliar spray type and soil-improving type. This can not only meet the nutrient supply needs of crops to improve quality and yield, but also improve soil structure, increase soil organic matter, and reduce soil bulk density. It is suitable for various planting scenarios such as ordinary farmland and barren land, and has strong versatility and practicality. The process parameters of this invention are standardized, highly controllable, and have high production stability, making it suitable for large-scale, industrialized mass production. Detailed Implementation

[0052] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0053] This invention provides a method for extracting water-soluble organophosphorus and silicon fertilizer from coarse fiber organic waste, the method comprising the following steps: Step 1: Crush the organic waste, which is selected from one or more of corn stalks, wheat stalks and rice stalks. Screen the crushed organic waste to obtain granular organic waste with a particle size of 100-160 mesh. Homogenize the granular organic waste at a homogenization temperature of 85-120℃ for 10-45 minutes. Dry the homogenized organic waste granules at 70-100℃ for 4-6 hours to obtain the organic waste reaction matrix. Step 2: Mix the organic waste reaction matrix with the alkaline activator at a mass ratio of 1:(2-4), and then add water to prepare a mixed suspension system with a solid-liquid ratio of 1:(5-15). The alkaline activator is selected from one or two of tetramethylammonium hydroxide and tetraethylammonium hydroxide. The mass concentration of the alkaline solution is controlled at 2-5 mol / L. The obtained mixed suspension system is heated to 300-550℃ at a heating rate of 3-5℃ / min for activation reaction. The activation reaction time is 2-4h. During the activation reaction, the stirring speed is maintained at 350-600 r / min. After the activation reaction is completed, the original activated system solution is obtained. Step 3: Add a phosphorus source reagent to the activated system stock solution cooled to room temperature. The phosphorus source reagent is selected from one or two of ammonium polyphosphate and potassium pyrophosphate. The mass ratio of the phosphorus source reagent to the activated system stock solution is (0.5-1.0):1. Then, add an acid-base regulator to adjust the pH of the reaction system to 5-7. Under continuous stirring at a stirring speed of 400-450 r / min, heat the reaction system to 180-220℃. At this temperature, perform the modification reaction for 3-5 hours to complete the slow-release cross-linking interface modification of organophosphorus fertilizer and obtain water-soluble organophosphorus-silicon fertilizer.

[0054] Example The present invention is further illustrated below with specific examples. These embodiments are merely illustrative and not intended to limit the scope of the invention. Except for rice straw, all other raw materials used in the embodiments of the present invention were commercially available.

[0055] Example 1 A method for extracting water-soluble silicon phosphate fertilizer from rice straw includes the following steps: Step 1: Pre-regulation of raw material structure: Select rice straw, remove weeds, soil and other impurities, crush, screen, homogenize and dry the raw material, and control the crushing particle size to 100 mesh; homogenize the screened material at a homogenization temperature of 100℃ for 30 minutes, and place the homogenized material in a negative pressure hot air gradient energy-saving drying machine for pre-drying treatment, with the drying temperature controlled at 80℃ and the drying time at 4 hours. Through the above pretreatment, a rice straw reaction matrix with regular microstructure and initial pore structure can be obtained.

[0056] Step 2, Alkali-Promoted Lattice Reconstruction Activation Treatment: The pre-regularized rice straw reaction matrix and alkaline activator were uniformly mixed at a mass ratio of 1:2, and deionized water was added to prepare a mixed suspension system with a solid-liquid ratio of 1:5. The alkaline activator was tetramethylammonium hydroxide, and the alkaline concentration was controlled at 3 mol / L. The mixed suspension system was placed in an etching activation reactor, and the activation reaction temperature was controlled at 400℃, with a heating rate of 3℃ / min and a constant temperature activation time of 2 h. During the activation reaction, continuous stirring was maintained at a stirring speed of 350 r / min. The original solution of the phosphorus silicon lattice activation system was obtained through the above parameter control.

[0057] Step 3: Targeted Phosphorus Doping Functionalization Construction: After the activated system stock solution naturally cools to room temperature, a phosphorus source reagent is added to the activated system stock solution. The mass ratio of the phosphorus source reagent to the phosphorus-silicon lattice activated system stock solution is controlled at 0.5:1, and ammonium polyphosphate is selected as the phosphorus source. The pH value of the reaction system is adjusted to 5 using an acid-base regulator. Subsequently, the reaction system is heated to 200℃ to complete the slow-release cross-linking interface modification of organophosphorus. The modification reaction is carried out at 200℃ for 3 hours, with continuous stirring during the modification reaction at a stirring speed of 400 r / min, to generate a resource-recyclable organic water-soluble phosphoric acid silicon fertilizer.

[0058] The test results of the organic water-soluble phosphoric acid silicon fertilizer product are as follows: the average content of available phosphorus (P2O5) (the available phosphorus content was tested according to the test standard GB / T 8573 "Determination of Available Phosphorus Content in Compound Fertilizers", the same below) is 12%, the average content of available silicon (SiO2) (the available silicon content was tested according to the industry standard HG / T 4216 "Silicon-containing Fertilizers", the same below) is 10.2%, the water solubility (the water solubility was tested according to NY 1107 "Water-soluble Fertilizers of Macroelements", the same below) is 98.6%, the pH is 5.9-7.5, the average phosphorus-silicon conversion efficiency (the conversion efficiency is calculated according to the formula: conversion efficiency (%) = (total amount of available silicon or available phosphorus in the product / total amount of silicon or phosphorus in the raw material) × 100%, the same below) is 85.3%, the fertilizer product has no visible residue, the heavy metal content in the fertilizer meets the standard of GB / T 17420-2021, and meets the raw material standard of water-soluble phosphoric acid silicon fertilizer.

[0059] Example 2 A method for extracting water-soluble silicon phosphate fertilizer from corn stalks includes the following steps: Step 1: Pre-regulation of raw material structure: Select corn stalks, remove weeds, soil and other impurities, crush, sieve, homogenize and dry the raw materials, controlling the crushing particle size to 120 mesh. Homogenize the sieved material at 90℃ for 30 minutes. Place the homogenized material in a negative pressure hot air gradient energy-saving drying machine for drying at 70℃ for 5 hours. Through the above pretreatment, a corn stalk reaction matrix with regular microstructure and initial pore structure can be obtained.

[0060] Step 2, Alkali-Promoted Lattice Reconstruction Activation Treatment: The pre-regularized corn stalk reaction matrix and alkaline activator were uniformly mixed at a mass ratio of 1:3, and deionized water was added to prepare a mixed suspension system with a solid-liquid ratio of 1:10. The alkaline activator was tetraethylammonium hydroxide compound, and the alkaline concentration was controlled at 2 mol / L. The mixed suspension system was placed in an etching activation reactor, and the activation reaction temperature was controlled at 300℃, the heating rate at 5℃ / min, and the isothermal activation time at 3 h. During the activation reaction, continuous stirring was maintained at a stirring speed of 400 r / min. The stock solution of the phosphorus silicon lattice activation system was obtained through the above parameter control.

[0061] Step 3: Targeted Phosphorus Doping Functionalization Construction: After the activated system stock solution naturally cools to room temperature, a phosphorus source reagent is added to the activated system stock solution. The mass ratio of the phosphorus source reagent to the phosphorus-silicon lattice activated system stock solution is controlled at 0.7:1. Potassium pyrophosphate is selected as the phosphorus source. The pH of the reaction system is adjusted to 7 using an acid-base regulator. Subsequently, the reaction system is heated to 180℃ to complete the slow-release crosslinking interface modification of organophosphorus. The modification reaction is carried out at 180℃ for 4 hours, with continuous stirring during the modification reaction at a stirring speed of 450 r / min, to generate a resource-recyclable organic water-soluble phosphoric acid silicon fertilizer.

[0062] The test results of the organic water-soluble phosphate silicon fertilizer product are as follows: water solubility rate 94.2%, pH=6.4, average phosphorus-silicon conversion efficiency 80.3%, no visible residue, and heavy metal content in the fertilizer meets the GB / T 17420-2021 standard, satisfying the requirements for use as fertilizer raw material.

[0063] Example 3 (Preparation of carbon-based silicon phosphate compound fertilizer by compounding straw) A method for preparing an organic water-soluble carbon-based silicon phosphate compound fertilizer using wheat, corn, and rice straw as raw materials includes the following steps: Step 1: Pre-regulation of raw material structure: Select 50kg of rice straw, 30kg of corn straw, and 20kg of wheat straw, mix them, remove impurities, and crush, sieve, homogenize, and dry the raw solid materials, controlling the crushing particle size to 160 mesh; homogenize the sieved material at a homogenization temperature of 115℃ for 15 minutes, and then place the homogenized material in a negative pressure hot air gradient energy-saving drying machine for drying, controlling the drying temperature at 100℃ for 6 hours. Through the above, a compound straw reaction matrix with regular microstructure and initial pore structure is obtained.

[0064] Step 2, Alkali-Promoted Lattice Reconstruction Activation Treatment: The pre-regularized compound straw reaction matrix and alkaline activator were uniformly mixed at a mass ratio of 1:4, and deionized water was added to prepare a mixed suspension system with a solid-liquid ratio of 1:15. The alkaline activator was a mixture of tetramethylammonium hydroxide and tetraethylammonium hydroxide at a mass ratio of 1:3, with an alkaline concentration controlled at 5 mol / L. The mixed suspension system was placed in an etching activation reactor, and the activation reaction temperature was controlled at 550℃, with a heating rate of 5℃ / min and a constant temperature activation time of 4 h. During the activation reaction, continuous stirring was maintained at a stirring speed of 600 r / min. The stock solution of the phosphorus silicon lattice activation system was obtained through the above parameter control.

[0065] Step 3: Targeted Phosphorus Doping Functionalization Construction: After the activated system stock solution naturally cools to room temperature, a phosphorus source reagent is added to the activated system stock solution. The mass ratio of the phosphorus source reagent to the phosphorus-silicon lattice activated system stock solution is controlled at 1:1. Ammonium polyphosphate is selected as the phosphorus source reagent. The pH value of the reaction system is adjusted to 7 using an acid-base regulator. Subsequently, the reaction system is heated to 220℃ to complete the slow-release crosslinking interface modification of organophosphorus. The modification reaction is carried out at 220℃ for 5 hours, with continuous stirring during the modification reaction at a stirring speed of 450 r / min, ultimately producing a resource-recyclable organic water-soluble phosphoric acid silicon fertilizer.

[0066] The test results of the organic water-soluble phosphoric acid silicon fertilizer product are as follows: the water-soluble conversion rate of silicon reaches 88.3% (3%-5% higher than that of single straw), the water-soluble conversion rate of phosphorus reaches 85.2%, the water solubility rate is 95.7%, the pH is 6.7, the fertilizer product has no visible residue, the heavy metal content in the fertilizer meets the GB / T 17420-2021 standard, meets the requirements for use as fertilizer raw material, has excellent stability, and is suitable for high-requirement fertilizer production scenarios.

[0067] Comparative Example Comparative Example 1 The organic water-soluble silicon phosphate fertilizer was prepared in a manner similar to that in Example 1, except that in step 2, the mass concentration of the alkali solution was controlled to be 1.5 mol / L.

[0068] The test results of organic water-soluble phosphoric acid silicon fertilizer products are as follows: silicon water-soluble conversion rate is 80.5%, phosphorus water-soluble conversion rate is 83.2%, and water solubility rate is 92.5%.

[0069] Comparative Example 2 The organic water-soluble silicon phosphate fertilizer was prepared in a manner similar to that in Example 1, except that in step 2, the mass concentration of the alkali solution was controlled at 5.5 mol / L.

[0070] The test results of organic water-soluble phosphoric acid silicon fertilizer products are as follows: silicon water-soluble conversion rate is 81.3%, phosphorus water-soluble conversion rate is 82.3%, and water solubility rate is 90.58%.

[0071] Comparative Example 3 The organic water-soluble silicon phosphate fertilizer was prepared in a manner similar to that in Example 1, except that in step 2, the activation reaction temperature was controlled at 250°C, the heating rate was 3°C / min, and the constant temperature activation time was 1.5 h.

[0072] The test results of organic water-soluble phosphoric acid silicon fertilizer products are as follows: silicon water-soluble conversion rate is 81.5%, phosphorus water-soluble conversion rate is 83.9%, and water solubility rate is 91.4%.

[0073] Comparative Example 4 The organic water-soluble silicon phosphate fertilizer was prepared in a manner similar to that in Example 1, except that in step 2, the activation reaction temperature was controlled at 600°C, the heating rate was 3°C / min, and the constant temperature activation time was 5.5 h.

[0074] The test results of organic water-soluble silicon phosphate fertilizer products are as follows: the silicon water-soluble conversion rate is 83.8%, and the water solubility rate is 91.1%.

[0075] Comparative Example 5 The organic water-soluble silicon phosphate fertilizer was prepared in a manner similar to that in Example 1, except that in step 3, a phosphorus source reagent was added to the activated system stock solution cooled to room temperature, and the mass ratio of the phosphorus source reagent to the activated system stock solution was 0.1:1.

[0076] The test results of organic water-soluble phosphoric acid silicon fertilizer products are as follows: silicon water-soluble conversion rate is 82.2%, phosphorus water-soluble conversion rate is 83.1%, and water solubility rate is 91.05%.

[0077] Comparative Example 6 The organic water-soluble silicon phosphate fertilizer was prepared in a manner similar to that in Example 1, except that in step 3, a phosphorus source reagent was added to the activated system stock solution cooled to room temperature, and the mass ratio of the phosphorus source reagent to the activated system stock solution was 1.3:1.

[0078] The test results of organic water-soluble silicon phosphate fertilizer products are as follows: silicon water-soluble conversion rate is 80.2%, and water solubility rate is 87%.

[0079] Comparative Example 7 The organic water-soluble silicon phosphate fertilizer was prepared in a manner similar to that in Example 1, except that in step 3, the temperature was raised to 140°C and the modification reaction was carried out at 140°C for 3 hours.

[0080] The test results of organic water-soluble phosphoric acid silicon fertilizer products are as follows: the water-soluble conversion rate of silicon is 82%, and the water-soluble conversion rate of phosphorus is 84.2%.

[0081] Experimental Example Experiment 1: Heavy Metal Detection The agricultural fertilizer products obtained in Examples 1, 2, and 3 were selected and subjected to full heavy metal testing according to GB / T 17420-2021 "Organic-Inorganic Compound Fertilizers". The detection method adopted microwave digestion pretreatment with a mixed digestion solution of HNO3-HCl-HClO4 (volume ratio of HNO3, HCl, and HClO4 of 3:1:1). Atomic absorption spectrophotometry (GB / T 17138) was used to detect lead, cadmium, and chromium, and atomic fluorescence spectrophotometry (GB / T 22105) was used to detect mercury and arsenic. The test results are shown in Table 1. Table 1

[0082] As shown in Table 1, the lead, cadmium, chromium, mercury, and arsenic contents of the agricultural fertilizer products obtained in Examples 1 and 3 are all far below the national standard limits, meeting the requirements for the use of green agricultural fertilizers. Among them, the agricultural fertilizer product obtained in Example 3 has the lowest heavy metal content, making it suitable for high-standard organic agriculture. The above results indicate that the extraction and preparation method for agricultural fertilizer described in this invention can effectively control the heavy metal content, especially the three-straw compound scheme, which can significantly reduce the risk of heavy metal accumulation, while traditional high-temperature processes are prone to causing heavy metal exceedances.

[0083] Experiment Example 2: Field Application Effect Detection Using the foliar spray type silicon phosphate fertilizer of Example 2 and the compound fertilizer of Example 3 as test samples, and commercially available ordinary water-soluble silicon fertilizer as a control, a field plot experiment was conducted in a paddy field with a test area of ​​10m². 2 The experiment was conducted in one plot, repeated three times, with routine water and fertilizer management. Crop traits and yield were measured at harvest. Testing methods: plant height was measured with a ruler; thousand-grain weight was measured using an electronic balance (accuracy 0.01g); lodging rate was determined using the plot counting method; and soil parameters were determined according to NY / T 1121 standard. Results are as follows: Example 2 Foliar fertilizer treatment group: The rice plant height increased by 8.3% compared with the control group, the lodging resistance was enhanced, the lodging rate of Example 2 was only 2.1% compared with the control group of 8.5%, the thousand-grain weight increased by 3.2g compared with the control group, the yield per mu increased by 12.5% ​​compared with the control group, and the incidence of leaf diseases decreased by 15.3% compared with the control group.

[0084] Example 3: The fresh weight of rice roots increased by 18.6% compared with the control group, the soil organic matter content increased by 0.32% compared with the pre-sowing level, the soil bulk density decreased by 10.1%, and the yield per mu increased by 9.8% compared with the control group. The results show that the carbon-based compound fertilizer prepared in Example 3 is suitable for barren soil plots.

[0085] The growth of the control group was lower than that of the fertilizer sample prepared in the embodiment of the present invention, and the soil improvement effect was not obvious.

[0086] The above results indicate that the agricultural fertilizer product prepared by the method of the present invention has the functions of nutrient supply, stress resistance and soil improvement.

[0087] Experiment Example 3: Stability Testing under Different Storage Environments The agricultural fertilizer product obtained in Example 1 was divided into three equal portions and placed in three different storage environments (low temperature and high humidity: 10℃, RH 85%; normal temperature and humidity: 25℃, RH 60%; high temperature and low humidity: 35℃, RH 40%) for 12 months. The content of effective ingredients, water solubility, and clumping were tested periodically. The test results are shown in Table 2 below. Table 2

[0088] As can be seen from Table 2, the effective phosphorus retention rate of the fertilizer prepared in Example 1 was 94.2%, the effective silicon retention rate was 94.5%, the water solubility rate was 97.1%, and the agglomeration rate was 6.3% in a low temperature and high humidity environment. Slight agglomeration did not affect its use after breaking, indicating that the prepared fertilizer is suitable for storage in humid southern regions.

[0089] The fertilizer prepared in Example 1 had an effective phosphorus retention rate of 95.8%, an effective silicon retention rate of 96.1%, and a water solubility rate of 97.8% under normal temperature and humidity conditions. It showed no clumping and had the best stability, making it the recommended storage condition.

[0090] The fertilizer prepared in Example 1 had an effective phosphorus retention rate of 93.5%, an effective silicon retention rate of 93.8%, and a water solubility rate of 96.9% in a high temperature and low humidity environment. It did not clump and only slightly absorbed moisture, indicating that the prepared fertilizer is suitable for storage in arid and high temperature areas in the north.

[0091] The above results show that the agricultural fertilizer product prepared by this invention has good stability under different climatic conditions, with an effective component loss of ≤6.5% within 12 months and a water solubility of ≥96.9%, meeting the needs of large-scale storage in different regions of the country.

[0092] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for extracting water-soluble organophosphorus and silicon fertilizer from coarse fiber organic waste, characterized in that, The method includes the following steps: Step 1: The organic waste is crushed, sieved, homogenized and dried in sequence to obtain the organic waste reaction matrix; Step 2: Mix the organic waste reaction matrix with the alkaline activator, then add water to mix and obtain a mixed suspension system. Heat the obtained mixed suspension system to carry out the activation reaction and obtain the activated system stock solution. Step 3: Add phosphorus source reagent to the activated system stock solution that has cooled to room temperature, then add acid-base regulator to adjust the pH of the reaction system, and then heat up to carry out the modification reaction to obtain water-soluble organic phosphorus-silicon fertilizer.

2. The method according to claim 1, characterized in that, In step 1, The organic waste is selected from one or more of the following: corn stalks, wheat stalks, rice stalks, peanut shells, and waste wood chips.

3. The method according to claim 1, characterized in that, In step 1, The crushed organic waste is sieved to obtain granular organic waste with a particle size of 80-180 mesh.

4. The method according to claim 1, characterized in that, In step 1, The homogenized organic waste was dried at 60–110°C for 2–7 hours.

5. The method according to claim 1, characterized in that, In step 2, Organic waste reaction matrix and alkaline activator are mixed at a mass ratio of 1: (1-5), and then water is added to prepare a mixed suspension system with a solid-liquid ratio of 1: (5-20).

6. The method according to claim 1, characterized in that, In step 2, The alkaline activator is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide.

7. The method according to claim 1, characterized in that, In step 2, Under continuous stirring conditions of 300–700 r / min, the resulting mixed suspension system was heated to 300–600 °C at a heating rate of 3–8 °C / min for activation reaction, and the activation reaction time was 1–5 h.

8. The method according to claim 1, characterized in that, In step 3, The phosphorus source reagent is selected from one or more of the following: hydroxyethylidene diphosphonic acid, ammonium polyphosphate, potassium pyrophosphate, sodium pyrophosphate, sodium tripolyphosphate, potassium dihydrogen phosphate, and ammonium dihydrogen phosphate.

9. The method according to claim 1, characterized in that, In step 3, Add phosphorus source reagent to the activated system stock solution cooled to room temperature. The mass ratio of phosphorus source reagent to activated system stock solution is (0.2-1.2):

1.

10. The method according to claim 1, characterized in that, In step 3, After adjusting the pH of the reaction system, the reaction system was heated to 150–250°C under continuous stirring at a speed of 400–500 r / min, and the modification reaction was carried out at this temperature for 2–6 h.

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