Chelated selenium fertilizer preparation method based on soil healthy cultivation

Abstract

The invention provides a preparation method of a chelated selenium fertilizer based on soil healthy cultivation. The preparation method of the chelated selenium fertilizer based on soil healthy cultivation comprises the following steps: S1, accurately proportioning raw materials; s2, pre-dissolving and preparing a solution; s3, performing mixing and chelation reaction; s4, filtering and purifying; s5, concentration detection and adjustment; s6, testing stability; and S7, sub-packaging and storing finished products. The preparation method of the chelated selenium fertilizer based on soil healthy cultivation has the advantages that through accurate proportioning, efficient chelation, multi-stage purification and stability optimization, the core problems of proportioning error, impurity residue, low utilization rate, poor stability and the like of the traditional selenium fertilizer are comprehensively solved, and a green process and a standardized production mode of the chelated selenium fertilizer have a wide application prospect. The safety and fertilizer efficiency of the selenium fertilizer are improved, the comprehensive cost is reduced, and reliable technical support is provided for healthy cultivation of soil and development of selenium-rich agricultural products.

Description

Technical Field

[0001] The present invention relates to the technical field of fertilizers, and particularly relates to a preparation method of chelated selenium fertilizer based on soil health cultivation. Background Art

[0002] Selenium was discovered by a Swedish chemist in 1818 and was previously considered a toxic and carcinogenic substance until the WHO announced in 1973 that selenium is an essential nutrient trace element for organisms, and selenium proteins with enzymatic activity play a protective role against oxidative stress. Currently, selenium has been recognized as one of the essential trace elements for the human body. Its basic functions are antioxidant, free radical scavenging, and participation in metabolism, and it has very important and unique effects in enhancing immunity, antagonizing toxins, delaying aging, promoting growth and development, and assisting in preventing various human diseases. Some studies have shown that: as the central organ of energy metabolism, the normal function and occurrence of diseases of the liver are closely related to selenium. Selenium exerts its biological functions through the catalysis of selenoproteases in the liver and is closely related to chronic hepatitis, liver fibrosis, non-alcoholic fatty liver disease, and hepatocellular carcinoma; some studies have shown that selenium can prevent or improve diabetes. The prevalence of diabetes in adults over 18 years old in China has reached 12.8%, and the number of diabetic patients is about 140 million, ranking first in the world. Compared with 10 years ago, the increase rate is as high as 56%. Diabetes has become one of the major chronic non-communicable diseases seriously threatening the health of Chinese residents. Diabetes and its complications not only seriously affect the quality of life of patients, but also cause a heavy economic burden on the families and society of patients; a large amount of animal experiment data, epidemiological data, and intervention trials have shown that selenium compounds have a definite role in the anti-tumor effect of preventing specific cancers and the initial stage of cancer.

[0003] In order to realize the chain of "soil selenium - agricultural product selenium - human selenium" and ultimately achieve the goal of supplementing selenium in the human body, modern agriculture effectively improves the selenium content in soil and agricultural products through the technology of applying selenium fertilizer. However, in the preparation of selenium fertilizer, there are generally problems such as low chelation efficiency, unstable fertilizer efficiency, insufficient chelate formation rate (usually <80%), and low utilization rate of selenium element, which seriously restricts the development of the selenium fertilizer industry.

[0004] Therefore, it is necessary to provide a new preparation method of chelated selenium fertilizer based on soil health cultivation to solve the above technical problems. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a preparation method of chelated selenium fertilizer based on soil health cultivation, which comprehensively solves the core problems of traditional selenium fertilizers, such as formulation errors, impurity residues, low utilization rate, and poor stability, through precise formulation, efficient chelation, multi-stage purification, and stability optimization. Its green process and standardized production mode not only improve the safety and fertilizer efficiency of selenium fertilizers but also reduce the comprehensive cost, providing reliable technical support for soil health cultivation and the development of selenium-rich agricultural products.

[0006] To solve the above technical problems, the preparation method of chelated selenium fertilizer based on soil health cultivation provided by the present invention includes the following steps: S1: Precise formulation of raw materials: Weigh potassium selenite and potassium pyrophosphate according to the mass ratio of 6:4. S2: Pre-dissolution and solution preparation: Dissolve potassium selenite and potassium pyrophosphate separately in deionized water until the solution is completely transparent and free of precipitation. S3: Mixing and chelation reaction: Slowly pour the two solutions into the same reaction kettle, turn on the constant temperature magnetic stirrer, set the temperature at 25°C, the stirring rate at 400 rpm, and continuously stir for 5 hours. S4: Filtration and purification: After chelation, vacuum filter the mixture through a 0.45 μm microporous membrane to remove unreacted particulate matter and impurities. S5: Concentration detection and adjustment: Use atomic fluorescence spectrometry to detect the concentration of potassium selenite in the mother liquor to ensure that the content is ≥20 g / L; if the concentration is insufficient, concentrate by vacuum evaporation; if the concentration is too high, add deionized water to dilute to the target value, and at the same time detect the chelation rate and heavy metal content. S6: Stability test: Place the mother liquor in an incubator at 40°C for accelerated aging for 7 days, observe whether precipitation or stratification occurs, and detect the particle size distribution of the chelate by a dynamic light scattering instrument to ensure that the liquid fertilizer is stable in the long term and no crystallization precipitates. S7: Finished product packaging and storage: Pack the qualified chelated selenium fertilizer into light-proof polyethylene barrels, seal it, and label the production batch, concentration, and validity period. The storage environment should be cool and dry, the temperature ≤30°C, avoid direct sunlight or contact with acidic substances, and the shelf life is set at 12 months.

[0007] Preferably, in S1, the purity of potassium selenite is ≥99%, and potassium pyrophosphate has no heavy metal residues and the water solubility is ≥95%; the electronic balance needs to be calibrated before weighing, and the error is controlled within ±0.1% to avoid the influence of formulation deviation on the chelation effect.

[0008] Preferably, in S2, the dissolution temperature is controlled at 25-30 °C, the stirring rate is 200 rpm, and the dissolution container needs to be made of corrosion-resistant material to avoid metal ion contamination.

[0009] Preferably, in S3, the pH value of the solution needs to be monitored in real time during the reaction, maintained between 6.5 and 7.5. When necessary, a buffer is added to adjust the acidity and alkalinity to ensure the stable formation of the chelate.

[0010] Preferably, in S4, the filtrate needs to be centrifuged twice. The rotational speed of the second centrifugation is 3000 rpm and the time is 10 minutes to further separate colloids or minute precipitates and obtain a clear and transparent chelated selenium fertilizer mother liquor.

[0011] Preferably, in S4, a filtration and purification integrated machine is used to filter and purify the solution after chelation.

[0012] Preferably, the filtration and purification integrated machine includes a support frame. An centrifugation mechanism is installed on the support frame. An air extraction mechanism is arranged above the centrifugation mechanism. A filtration mechanism is arranged above the air extraction mechanism. The air extraction mechanism and the filtration mechanism are both fixedly installed on the support frame. The filtration mechanism, the air extraction mechanism, and the centrifugation mechanism are connected in sequence.

[0013] Preferably, the centrifugation mechanism includes a centrifugation tank. Two bearings are fixedly sleeved on the outer side of the centrifugation tank. The outer rings of the bearings are fixedly connected to the support frame. A first connecting pipe is arranged at the bottom of the centrifugation tank. A manual valve is arranged on the first connecting pipe. A centrifugation power mechanism is arranged on the support frame. The centrifugation power mechanism includes a motor. A first gear is fixedly installed on the output shaft of the motor. A second gear is fixedly sleeved on the outer side of the first connecting pipe. The second gear is located below the manual valve. The first gear meshes with the second gear. The bottom end of the first connecting pipe is rotatably installed with a rotating seal sleeve. One end of a discharge pipe is connected to the bottom end of the rotating seal sleeve.

[0014] Preferably, the air extraction mechanism includes an air extraction tank. A second connecting pipe is fixedly installed at the top of the air extraction tank. A third connecting pipe is fixedly installed at the bottom of the air extraction tank. The bottom end of the third connecting pipe extends into the centrifugation tank. A first electric valve is fixedly installed on the third connecting pipe. An exhaust pipe is fixedly installed on one side of the air extraction pipe. A connector is installed at one end of the exhaust pipe. The connector is located outside the air extraction tank.

[0015] Preferably, the filtering mechanism includes a filtering hopper, a supporting plate is arranged in the filtering hopper, filtering holes are formed in the braking plate, a concave filter paper is arranged in the filtering hopper, the bottom of the concave filter paper is in contact with the top of the supporting plate, the top of the concave filter paper extends outside the filtering hopper and is in contact with the top of the filtering hopper, a plurality of mounting frames are fixedly installed on the outer wall of the filtering hopper, a connecting rod is slidably installed on the mounting frame, the bottom end of the connecting rod penetrates through the mounting frame, one end of a spring is fixedly installed on the mounting frame, the other end of the spring is fixedly connected with the connecting rod, the bottom ends of the plurality of connecting rods are fixedly installed with the same pressing ring, the bottom of the pressing ring is in contact with the concave filter paper, a limiting rod is fixedly installed on the outer wall of the filtering hopper, a limiting block is rotatably installed at the top end of the limiting rod, two lifting handles are symmetrically and fixedly installed on the top of the pressing ring, the lifting handles are adapted to the limiting blocks, the bottom of the filtering hopper is fixedly installed with a fourth connecting pipe, the fourth connecting pipe is located in the second connecting pipe, and the fourth connecting pipe is hermetically connected with the second connecting pipe, and a second electric valve is fixedly installed on the fourth connecting pipe.

[0016] Compared with the related art, the chelated selenium fertilizer preparation method provided by the present invention based on soil health cultivation has the following beneficial effects: High-precision ratio and improved chelation efficiency: Through precise weighing (error ≤ ±0.1%) and mass ratio control (potassium selenite∶potassium pyrophosphate = 6∶4), combined with constant-temperature magnetic stirring (25°C, 400 rpm, 5 h) and real-time pH monitoring (6.5 - 7.5), the chelation rate is significantly increased to ≥95%. This process optimization enables selenium elements to exist in a stable chelated state, avoiding the oxidation or loss of selenium in traditional selenium fertilizers, increasing the crop absorption rate by more than 30%, and effectively reducing the fertilization frequency; High purity and safety guarantee: Adopting a multi-stage purification process (0.45μm membrane filtration + 3000 rpm centrifugation), completely removing unreacted particles and colloidal impurities to ensure that the fertilizer is clear and transparent. At the same time, the raw materials are strictly screened (potassium selenite purity ≥ 99%, potassium pyrophosphate water solubility ≥ 95%), and heavy metals are detected by atomic fluorescence spectrometry (meeting the NY1429—2010 standard), eliminating the pollution risk from the source and ensuring soil health and agricultural product safety; Excellent stability and long-lasting effect: Controlling the chelate particle size by a dynamic light scattering instrument (D90 ≤ 100nm), combined with a 40°C accelerated aging test (no precipitation in 7 days), ensuring that no crystallization or stratification occurs in the liquid fertilizer within a 12-month shelf life. The stable chelation structure can also slow down the leaching loss of selenium elements in the soil and extend the duration of fertilizer effectiveness, especially suitable for selenium-deficient soil areas that require long-term selenium supplementation; Process Greening and Energy Conservation and Consumption Reduction: Use corrosion-resistant reactors (glass or 316L stainless steel) and a closed-loop production process to reduce metal ion pollution and wastewater discharge. In the pre-dissolution stage, low-temperature (25~30°C) stirring is adopted, reducing energy consumption by more than 40% compared to traditional high-temperature reactions, which is in line with the development trend of low-carbon agriculture; Multi-scenario Applicability and Economy: The finished product can be flexibly packaged into liquid (light-proof polyethylene barrels) or the concentration can be adjusted by concentration (vacuum evaporation / dilution), adapting to various fertilization methods such as drip irrigation and foliar spraying. The high chelation rate and stability reduce the dosage per unit area, and the cost per hectare is reduced by 15%~20% compared to traditional selenium fertilizers. At the same time, the selenium content in rice is increased to 438 μg / kg (field test data), helping farmers increase their income and promoting the development of functional agriculture; Standardized Production and Quality Control: From raw material detection (purity, water solubility), reaction monitoring (pH, temperature) to finished product inspection (concentration, particle size, heavy metals), standardized processes and instrumental control (such as atomic fluorescence spectrometry, HPLC) are adopted throughout the process to ensure batch consistency, meet the needs of large-scale industrial production, and promote the technological upgrading of the selenium fertilizer industry. Description of the Drawings

[0017] Figure 1 It is a flow chart of the preparation method of the chelated selenium fertilizer based on soil health cultivation provided by the present invention; Figure 2 It is a schematic structural diagram of the filtration and purification integrated machine in the preparation method of the chelated selenium fertilizer based on soil health cultivation provided by the present invention; Figure 3 It is Figure 2 A schematic structural diagram of another perspective shown in; Figure 4 It is Figure 2 A schematic cross-sectional structural diagram after removing the concave filter paper shown in; Figure 5 It is Figure 3 A schematic cross-sectional structural diagram after removing the concave filter paper shown in; Figure 6 It is Figure 2 A schematic structural diagram of the filtration mechanism shown in; Figure 7 It is Figure 6 A schematic structural diagram after removing the concave filter paper shown in; Figure 8 It is Figure 5 A schematic connection structural diagram of the air extraction mechanism and the filtration mechanism shown in; Figure 9 It is Figure 5 A schematic connection structural diagram of the centrifugation mechanism, the centrifugation power mechanism and the air extraction mechanism shown in; Figure 10 It is Figure 2Schematic diagram of the connection structure between the centrifugal power mechanism and the centrifugal mechanism shown

[0018] Reference numerals in the figure: 1, support frame; 2, centrifugal mechanism, 201, centrifugal tank, 202, bearing, 203, first connecting pipe, 204, manual valve, 205, rotating seal sleeve, 206, discharge pipe; 3, air extraction mechanism, 301, air extraction tank, 302, second connecting pipe, 303, exhaust pipe, 304, connector, 305, third connecting pipe, 306, first electric valve; 4, filtering mechanism, 401, filtering hopper, 402, concave filter paper, 403, support plate, 404, filtering holes, 405, mounting frame, 406, connecting rod, 407, spring, 408, pressing ring, 409, limiting rod, 410, limiting block, 411, handle, 412, fourth connecting pipe, 413, second electric valve; 5, centrifugal power mechanism, 501, motor, 502, first gear, 503, second gear Detailed implementation manners

[0019] The present invention will be further described below with reference to the accompanying drawings and implementation manners

[0020] Please refer to Figures 1 - 10 , where Figure 1 is the flowchart of the preparation method of the chelated selenium fertilizer based on soil health cultivation provided by the present invention Figure 2 is the schematic diagram of the structure of the filtration and purification integrated machine in the preparation method of the chelated selenium fertilizer based on soil health cultivation provided by the present invention Figure 3 is Figure 2 the schematic diagram of the structure from another perspective shown Figure 4 is Figure 2 the sectional structure schematic diagram after removing the concave filter paper shown Figure 5 is Figure 3 the sectional structure schematic diagram after removing the concave filter paper shown Figure 6 is Figure 2 the schematic diagram of the structure of the filtering mechanism shown Figure 7 is Figure 6 the schematic diagram of the structure after removing the concave filter paper shown Figure 8 is Figure 5 the schematic diagram of the connection structure between the air extraction mechanism and the filtering mechanism shown Figure 9 is Figure 5 the schematic diagram of the connection structure among the centrifugal mechanism, the centrifugal power mechanism and the air extraction mechanism shown Figure 10 is Figure 2 the schematic diagram of the connection structure between the centrifugal power mechanism and the centrifugal mechanism shown. The preparation method of the chelated selenium fertilizer based on soil health cultivation includes the following steps S1: Precise proportioning of raw materials Weigh potassium selenite and potassium pyrophosphate according to the mass ratio of 6:4, ensuring that the purity of potassium selenite is ≥99% and potassium pyrophosphate meets the agricultural fertilizer standard (such as no heavy metal residue, water solubility ≥95%). The electronic balance needs to be calibrated before weighing, and the error is controlled within ±0.1% to avoid affecting the chelation effect due to deviation in the ratio.

[0021] S2: Pre-dissolution and solution preparation: Dissolve potassium selenite and potassium pyrophosphate separately in deionized water. The dissolution temperature is controlled at 25~30°C, and the stirring rate is 200 rpm until the solution is completely transparent and has no precipitation. The dissolution container should be made of corrosion-resistant materials (such as glass or 316L stainless steel) to avoid metal ion contamination.

[0022] S3: Mixing and chelation reaction: Slowly pour the two solutions into the same reaction kettle, turn on the constant-temperature magnetic stirrer, set the temperature at 25°C, and the stirring rate at 400 rpm, and continuously stir for 5 hours. During the reaction process, the pH value of the solution needs to be monitored in real time and maintained between 6.5 and 7.5. When necessary, add a buffer to adjust the acidity and alkalinity to ensure the stable formation of the chelate.

[0023] S4: Filtration and purification: After chelation is completed, vacuum filter the mixed solution through a 0.45μm microporous filter membrane to remove unreacted particulate matter and impurities. The filtrate needs to be centrifuged twice (3000 rpm, 10 minutes) to further separate colloids or fine precipitates to obtain a clear and transparent mother liquor of chelated selenium fertilizer.

[0024] S5: Concentration detection and adjustment: Use atomic fluorescence spectrometry to detect the concentration of potassium selenite in the mother liquor and ensure that the content is ≥20 g / L. If the concentration is insufficient, it can be concentrated by vacuum evaporation; if the concentration is too high, add deionized water to dilute it to the target value. At the same time, detect the chelation rate (≥95%) and heavy metal content (meeting the NY1429—2010 standard).

[0025] S6: Stability test: Place the mother liquor in a 40°C constant-temperature incubator to accelerate aging for 7 days, and observe whether there is precipitation or stratification. Use a dynamic light scattering instrument to detect the particle size distribution of the chelate (D90≤100nm) to ensure the long-term stability of the liquid fertilizer and no crystal precipitation.

[0026] S7: Finished product packaging and storage: Pack the qualified chelated selenium fertilizer into light-proof polyethylene barrels, seal it, and label the production batch, concentration, and validity period. The storage environment should be cool and dry, with a temperature ≤30°C, avoiding direct sunlight or contact with acidic substances, and the shelf life is set at 12 months.

[0027] The present invention also provides a filtering and purification integrated machine for filtering and purifying the solution after chelation. The filtering and purification integrated machine includes a support frame 1, on which a centrifugal mechanism 2 is installed. Above the centrifugal mechanism 2, there is an air extraction mechanism 3, and above the air extraction mechanism 3, there is a filtering mechanism 4. Both the air extraction mechanism 3 and the filtering mechanism 4 are fixedly installed on the support frame 1, and the filtering mechanism 4, the air extraction mechanism 3, and the centrifugal mechanism 2 are connected in sequence.

[0028] The filtering mechanism 4 includes a filtering hopper 401. Inside the filtering hopper 401, there is a support plate 403. Filtering holes 404 are formed in the braking plate 403. Inside the filtering hopper 401, there is a concave filter paper 402. The concave filter paper 402 is a 0.45μm filter membrane. The bottom of the concave filter paper 402 is in contact with the top of the support plate 403, and the top of the concave filter paper 402 extends outside the filtering hopper 401 and is in contact with the top of the filtering hopper 401. A plurality of mounting frames 405 are fixedly installed on the outer wall of the filtering hopper 401. A connecting rod 406 is slidably installed on the mounting frame 405. The bottom end of the connecting rod 406 penetrates through the mounting frame 405. One end of a spring 407 is fixedly installed on the mounting frame 405, and the other end of the spring 407 is fixedly connected to the connecting rod 406. The bottom ends of a plurality of the connecting rods 406 are fixedly installed with the same pressing ring 408. The bottom of the pressing ring 408 is in contact with the concave filter paper 404. A limiting rod 409 is fixedly installed on the outer wall of the filtering hopper 401. A limiting block 410 is rotatably installed at the top end of the limiting rod 409. Two lifting handles 411 are symmetrically and fixedly installed on the top of the pressing ring 408. The lifting handle 411 is adapted to the limiting block 410. The bottom of the filtering hopper 412 is fixedly installed with a fourth connecting pipe 412. The fourth connecting pipe 412 is located inside the second connecting pipe 302, and the fourth connecting pipe 412 is hermetically connected to the second connecting pipe 302. A second electric valve 413 is fixedly installed on the fourth connecting pipe 412.

[0029] When the filtering mechanism 4 is used, only need to place the concave filter paper 402 in the filtering hopper 401, and then pour the filtrate after chelation into the concave filter paper 402 in the filtering hopper 401, and the filtrate after chelation can be filtered through the air extraction mechanism 3; through the settings of the support plate 403, the filtering holes 404 and the filtering hopper 401 in this process, the concave filter paper 402 can be supported. At the same time, through the settings of the mounting frame 405, the connecting rod 406, the spring 407, the pressing ring 408, the limiting rod 409, the limiting block 410 and the lifting handle 411, the concave filter paper 402 can be better attached to the inner wall of the filtering hopper 401, so as to ensure that the negative pressure generated by the air extraction mechanism 3 can ensure the filtering effect of the filtrate after chelation. At the same time, it is convenient to replace the concave filter paper 402.

[0030] The air extraction mechanism 3 includes an air extraction tank 301. A second connecting pipe 302 is fixedly installed at the top of the air extraction tank 301. A third connecting pipe 305 is fixedly installed at the bottom of the air extraction tank 301. The bottom end of the third connecting pipe 305 extends into the centrifugal tank 201. A first electric valve 306 is fixedly installed on the third connecting pipe 305. An exhaust pipe 303 is fixedly installed on one side of the air extraction pipe 301. One end of the exhaust pipe 303 is provided with a connector 304, and the connector 304 is located outside the air extraction tank 301.

[0031] The centrifugal mechanism 2 includes a centrifugal tank 201. Two bearings 202 are fixedly sleeved on the outer side of the centrifugal tank 201. The outer rings of the bearings 202 are fixedly connected to the support frame 1. A first connecting pipe 203 is provided at the bottom of the centrifugal tank 201. A manual valve 204 is provided on the first connecting pipe 203. A centrifugal power mechanism 5 is provided on the support frame 1. The centrifugal power mechanism 5 includes a motor 501. A first gear 502 is fixedly installed on the output shaft of the motor 501. A second gear 503 is fixedly sleeved on the outer side of the first connecting pipe 203. The second gear 503 is located below the manual valve 204. The first gear 502 meshes with the second gear 503. The bottom end of the first connecting pipe 203 is rotatably installed with a rotating seal sleeve 205. One end of a discharge pipe 206 is connected to the bottom end of the rotating seal sleeve 205.

[0032] By connecting the filtering mechanism 4, the air extraction mechanism 3, and the centrifugal mechanism 2 in sequence, the filtration and purification of the filtrate after chelation can be directly achieved, and the efficiency of the filtration and purification of the filtrate after chelation can be improved.

[0033] Compared with the related art, the chelated selenium fertilizer preparation method provided by the present invention based on soil health cultivation has the following beneficial effects: High-precision proportioning and improved chelation efficiency: Through precise weighing (error ≤ ±0.1%) and mass ratio control (potassium selenite∶potassium pyrophosphate = 6∶4), combined with constant-temperature magnetic stirring (25°C, 400 rpm, 5 h) and real-time pH monitoring (6.5 - 7.5), the chelation rate is significantly increased to ≥95%. This process optimization enables selenium elements to exist in a stable chelated state, avoiding the oxidation or loss of selenium in traditional selenium fertilizers. The crop absorption rate is increased by more than 30%, effectively reducing the fertilization frequency; High purity and safety guarantee: Adopting a multi-stage purification process (0.45μm membrane filtration + 3000rpm centrifugation), thoroughly removing unreacted particles and colloidal impurities, ensuring that the fertilizer is clear and transparent. At the same time, raw materials are strictly screened (potassium selenite purity ≥ 99%, potassium pyrophosphate water solubility ≥ 95%), and heavy metals are detected by atomic fluorescence spectrometry (meeting the NY1429—2010 standard), eliminating pollution risks from the source and ensuring soil health and agricultural product safety; Excellent stability and long-acting property: Controlling the chelate particle size (D90 ≤ 100nm) through a dynamic light scattering instrument, combined with an accelerated aging test at 40°C (no precipitation in 7 days), ensuring that there is no crystal precipitation or stratification in the liquid fertilizer within a 12-month shelf life. The stable chelation structure can also slow down the leaching loss of selenium in the soil and extend the duration of fertilizer efficiency, especially suitable for selenium-deficient soil areas that require long-term selenium supplementation; Green process and energy conservation and consumption reduction: Using corrosion-resistant reactors (glass or 316L stainless steel) and a closed-loop production process, reducing metal ion pollution and wastewater discharge. In the pre-dissolution stage, low-temperature (25~30°C) stirring is adopted, reducing energy consumption by more than 40% compared with traditional high-temperature reactions, meeting the development trend of low-carbon agriculture; Multi-scenario applicability and economy: The finished product can be flexibly packaged into liquid (light-proof polyethylene barrels) or the concentration can be adjusted by concentration (vacuum evaporation / dilution), adapting to various fertilization methods such as drip irrigation and foliar spraying. The high chelation rate and stability reduce the dosage per unit area, and the cost per hectare is reduced by 15%~20% compared with traditional selenium fertilizers. At the same time, the selenium content in rice is increased to 438μg / kg (field test data), helping farmers increase income and promoting the development of functional agriculture; Standardized production and quality control: From raw material detection (purity, water solubility), reaction monitoring (pH, temperature) to finished product inspection (concentration, particle size, heavy metals), a standardized process and instrumental control (such as atomic fluorescence spectrometry, HPLC) are adopted throughout the process to ensure batch consistency, meet the needs of large-scale industrial production, and promote the technological upgrading of the selenium fertilizer industry.

[0034] The above are only embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for preparing chelated selenium fertilizer based on soil health cultivation, characterized in that: The following steps are involved: S1: Accurate proportion of raw materials: Weigh potassium selenite and potassium pyrophosphate according to a mass ratio of 6:4; S2: Pre-dissolution and solution preparation: Dissolve potassium selenite and potassium pyrophosphate separately in deionized water until the solution is completely transparent without precipitation; S3: Mixing and chelation reaction: The two solutions were slowly poured into the same reactor, and the constant temperature magnetic stirrer was turned on, the temperature was set to 25°C, the stirring rate was 400 rpm, and stirring was continued for 5 hours; S4: Filtration and purification: After chelation, the mixture was vacuum filtered through a 0.45 μm microporous filter membrane to remove unreacted particles and impurities; S5: Concentration detection and adjustment: The concentration of potassium selenite in the mother liquor was tested by atomic fluorescence spectrometry to ensure that the content was ≥20 g / L; if the concentration was insufficient, it was concentrated by reduced pressure evaporation; if the concentration was too high, deionized water was added to dilute it to the target value, and the chelation rate and heavy metal content were tested at the same time; S6: Stability test: The mother liquor was placed in a 40°C thermostat for accelerated aging for 7 days to observe whether precipitation or stratification occurred. The particle size distribution of the chelate was tested by a dynamic light scattering instrument to ensure that the liquid fertilizer was stable for a long time without crystallization. S7: Finished product packaging and storage: Qualified chelated selenium fertilizers should be packaged into light-proof polyethylene barrels, sealed and marked with production batch, concentration and expiration date. The storage environment should be cool and dry, with a temperature of ≤30°C, avoiding direct sunlight or contact with acidic substances. The shelf life is set at 12 months.

2. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 1, characterized in that: In the S1, the purity of potassium selenite is ≥99%, and the potassium pyrophosphate has no heavy metal residue and a water solubility of ≥95%. The electronic balance needs to be calibrated before weighing, and the error is controlled within ±0.1% to avoid the ratio deviation affecting the chelating effect.

3. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 1, characterized in that: In S2, the dissolution temperature is controlled at 25-30°C, the stirring rate is 200 rpm, and the dissolution container needs to be made of corrosion-resistant material to avoid metal ion contamination.

4. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 1, characterized in that: In S3, the pH value of the solution needs to be monitored in real time during the reaction and maintained between 6.5 and 7.

5. If necessary, a buffer is added to adjust the pH value to ensure stable formation of the chelate.

5. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 1, characterized in that: In S4, the filtrate needs to be centrifuged twice, and the secondary centrifugation speed is 3000 rpm for 10 minutes to further separate the colloid or micro-precipitate to obtain a clear and transparent chelated selenium fertilizer mother solution.

6. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 5, characterized in that: In S4, the chelated solution is filtered and purified by a filtering and purification integrated machine.

7. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 6, characterized in that: The integrated filtering and purification machine comprises a support frame, a centrifugal mechanism is installed on the support frame, an air suction mechanism is provided above the centrifugal mechanism, a filtering mechanism is provided above the air suction mechanism, the air suction mechanism and the filtering mechanism are both fixedly installed on the support frame, and the filtering mechanism, the air suction mechanism and the centrifugal mechanism are connected in sequence.

8. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 7, characterized in that: The centrifugal mechanism includes a centrifugal tank, an outer fixed sleeve of the centrifugal tank is provided with two bearings, the outer rings of the bearings are fixedly connected to the support frame, a first connecting pipe is provided at the bottom of the centrifugal tank, a manual valve is provided on the first connecting pipe, a centrifugal power mechanism is provided on the support frame, the centrifugal power mechanism includes a motor, a first gear is fixedly installed on the output shaft of the motor, a second gear is provided on the outer fixed sleeve of the first connecting pipe, the second gear is located below the manual valve, the first gear is meshed with the second gear, a rotating sealing sleeve is rotatably installed at the bottom end of the first connecting pipe, and the bottom end of the rotating sealing sleeve is connected to one end of a discharge pipe.

9. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 8, characterized in that: The vacuum mechanism includes a vacuum tank, a second connecting pipe is fixedly installed on the top of the vacuum tank, a third connecting pipe is fixedly installed on the bottom of the vacuum tank, the bottom end of the third connecting pipe extends into the centrifugal tank, a first electric valve is fixedly installed on the third connecting pipe, an exhaust pipe is fixedly installed on one side of the vacuum pipe, a connector is installed at one end of the exhaust pipe, and the connector is located outside the vacuum tank.

10. The method for preparing chelated selenium fertilizer based on soil health cultivation according to claim 9, characterized in that: The filtering mechanism comprises a filter bucket, a support plate is arranged in the filter bucket, a filter hole is opened on the brake plate, a concave filter paper is arranged in the filter bucket, the bottom of the concave filter paper is in contact with the top of the support plate, the top of the concave filter paper extends to the outside of the filter bucket and in contact with the top of the filter bucket, a plurality of mounting frames are fixedly mounted on the outer wall of the filter bucket, a connecting rod is slidably mounted on the mounting frame, the bottom end of the connecting rod passes through the mounting frame, one end of a spring is fixedly mounted on the mounting frame, and the other end of the spring is fixedly mounted on the connecting rod The filter hopper is fixedly connected, and the bottom ends of the multiple connecting rods are fixedly installed with the same pressure ring, the bottom of the pressure ring is in contact with the concave filter paper, a limit rod is fixedly installed on the outer wall of the filter hopper, and a limit block is rotatably installed on the top of the limit rod, and two handles are symmetrically fixedly installed on the top of the pressure ring, and the handles are adapted to the limit block, a fourth connecting pipe is fixedly installed on the bottom of the filter hopper, the fourth connecting pipe is located in the second connecting pipe, and the fourth connecting pipe is sealed and connected to the second connecting pipe, and a second electric valve is fixedly installed on the fourth connecting pipe.

Images