Preparation method of vitamin B2 waste liquid composite coated controlled-release fertilizer

Abstract

The invention belongs to the field of fertilizers, and particularly relates to a preparation method of a vitamin B2 waste liquid composite coated controlled-release fertilizer, which comprises the following steps: mixing a vitamin B2 waste liquid initial liquid fertilizer with light-resistant stability with a binder by a spray granulation method, and carrying out spray granulation to obtain the vitamin B2 waste liquid composite coated controlled-release fertilizer. Spraying the mixed solution into tiny liquid drops through a sprayer, and then gradually curing the liquid drops in the drying process to form particles; the preparation method comprises the following steps: preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer, namely adding fertilizer particles into a rotary drum, and preparing the vitamin B2 waste liquid composite coated controlled-release fertilizer through a coating technology. The light-resistant stabilizer is added into a vitamin B2 waste liquid initial fertilizer, and the vitamin B2 in the light-resistant stabilizer fertilizer has ultraviolet radiation resistance; the fertilizer efficiency of the initial fertilizer of the vitamin B2 waste liquid is effectively improved, and the problem that the light stability of the vitamin B2 in the fertilizer is poor is effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of fertilizers, in particular to a method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer. Background Art

[0002] With the rapid development of modern agriculture in my country, especially the continuous expansion of green organic agricultural planting area, integrating specific microorganisms into fertilizers to produce fertilizer products that are beneficial to the soil and have comprehensive functions has become the focus of research and development of fertilizer manufacturers today. Microbial agents are not fertilizers themselves, but rely on the life activities of the bacteria to produce metabolites to provide nutrients for crops. They can directly or indirectly improve the soil, make the soil loose and breathable, improve fertilizer supply capacity, prevent soil-borne diseases, improve crop disease resistance and stress resistance, increase fruit and vegetable yield and quality, and protect the ecological environment. In particular, polyglutamic acid in natural metabolites has a good water and fertilizer retention effect. Polyglutamic acid has the potential function of promoting crop growth and thus increasing crop yield in agriculture. Therefore, research on new fertilizers containing polyglutamic acid is also a popular research direction of compound microbial fertilizers. However, the fertilizers obtained by the existing preparation methods of fertilizers containing polyglutamic acid often have the problems of short fertilizer effect, complex preparation process and high cost. Therefore, it is urgent to find a preparation method for a new fertilizer containing polyglutamic acid with better water retention performance, more obvious production increase effect, longer fertilizer effect and reduced preparation cost.

[0003] Vitamin B2, also known as riboflavin, is an important water-soluble vitamin. Its physicochemical defects may involve many aspects. The following is a detailed analysis of the physicochemical defects of riboflavin: Riboflavin is unstable under light, especially easy to decompose under ultraviolet light. Free riboflavin is sensitive to ultraviolet light and can be photolyzed into photoflavin under acidic conditions and photolyzed into photopigment under alkaline conditions and loses its biological activity. Therefore, when storing and using riboflavin, it is necessary to avoid long-term exposure to light to ensure its stability and effectiveness, making it difficult for vitamin B2-related fertilizers to exert their fertilizer effect more efficiently. Summary of the invention

[0004] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer of the present invention comprises the following steps: Step 1: preparing a light-stable vitamin B2 waste liquid initial fertilizer: using soybean meal, corn syrup, starch and glucose as culture medium, using Ashwagandha yeast, Candida utilis, Saccharomyces cerevisiae, Bacillus subtilis and Corynebacterium ammoniagenes to ferment and extract vitamin B2, and then putting the fermentation waste liquid into a fermentation tank and heating it to 80-100°C to kill the bacteria; adding a raw material containing a light-stable stabilizer to each liter of liquid; using the liquid as a culture medium, the culture condition is 37°C, the inoculation amount is 8% Bacillus subtilis, and the rotation speed is 220r / min. After 22 to 24 hours, the light-stable vitamin B2 waste liquid initial liquid fertilizer is obtained, and then the light-stable vitamin B2 waste liquid initial liquid fertilizer and a binder are mixed by a spray granulation method, and the mixed liquid is sprayed into tiny droplets by a sprayer, and then these droplets are gradually solidified to form particles during the drying process; Step 2: Prepare vitamin B2 waste liquid composite coated controlled-release fertilizer: add fertilizer particles into a rotating drum, and prepare vitamin B2 waste liquid composite coated controlled-release fertilizer by coating technology.

[0006] As a further solution of the present invention: in step 1, the raw materials containing the light-resistant stabilizer are the following raw materials in grams: molasses 100-120, sodium glutamate 50-60, ammonium sulfate 6-8, magnesium sulfate 0.5-0.7, potassium dihydrogen phosphate 15-20, and light-resistant stabilizer 1-3.

[0007] As a further solution of the present invention: in step 1, the binder includes corn starch and bentonite.

[0008] As a further solution of the present invention: the preparation process of the light-resistant stabilizer comprises the following steps: Dissolve 2,4-dihydroxybenzophenone in tetrahydrofuran, then add triethylamine to obtain a mixed solution A; Acryloyl chloride and tetrahydrofuran are mixed to obtain an acryloyl chloride solution, and the acryloyl chloride solution is dripped into the mixed solution A drop by drop at a temperature of 0°C-10°C for 0.5h-2h, and then reacted at a temperature of 0°C-10°C for 6h-12h to obtain a mixed solution B; Under the condition of a centrifugal speed of 8000r / min-20000r / min, the mixed solution B is centrifuged for 10min-30min to obtain a supernatant, and the supernatant is dripped dropwise into a saturated sodium bicarbonate solution, and the solid is filtered to obtain a light-resistant stabilizer.

[0009] As a further embodiment of the present invention: the mass ratio of 2,4-dihydroxybenzophenone to tetrahydrofuran is 1 g:(2-10) mL.

[0010] As a further solution of the present invention: in step 1, the mass ratio of 2,4-dihydroxybenzophenone to triethylamine is 1 g:(0.5-2) mL.

[0011] As a further solution of the present invention: the volume ratio of acryloyl chloride to tetrahydrofuran is 1:(2-7); the volume ratio of acryloyl chloride solution to mixed solution A is 1:(1-3).

[0012] As a further scheme of the present invention: in step 1, fertilizer particles are added to a rotating drum and the fertilizer is preheated to 50-70°C; polyolefin wax is sprayed onto the surface of the preheated fertilizer particles to form a polyolefin wax coating; starch, a liquefier and a catalyst are evenly mixed, heated at 100-200°C for reaction, and cooled to 80-100°C to obtain a starch liquefaction coating liquid; the starch liquefaction coating liquid and a curing agent are mixed and sprayed onto the surface of the polyolefin wax coating of the fertilizer particles, cured into a film, and formed a starch-based polyurethane layer; epoxy resin and amine are mixed to prepare an epoxy resin mixed coating liquid; the epoxy resin mixed coating liquid is sprayed onto the surface of the starch-based polyurethane layer of the fertilizer particles, cured into a film, and an epoxy resin is formed, thereby obtaining a vitamin B2 waste liquid composite coated controlled-release fertilizer.

[0013] As a further solution of the present invention: a polyolefin wax coating, a starch-based polyurethane layer and an epoxy resin layer are sprayed on the surface of the fertilizer particles in sequence; the polyolefin wax coating accounts for 0.1-1.0% of the total weight of the fertilizer particles; the starch-based polyurethane layer accounts for 1.0-10.0% of the total weight of the fertilizer particles; and the epoxy resin layer accounts for 1.0-10.0% of the total weight of the fertilizer particles.

[0014] As a further embodiment of the present invention: in step 1, the wax used in the polyolefin wax coating is one or a mixture of poly 2-butene wax, poly 1-pentene wax, poly 3-hexene wax, poly 1-octene wax, poly 4-methyl-1-pentene wax or polypropylene wax.

[0015] The beneficial effects of the present invention are as follows: 1. The present invention provides a method for preparing a composite coated controlled-release fertilizer of vitamin B2 waste liquid. By adding a light-resistant stabilizer to the initial fertilizer of the vitamin B2 waste liquid, the vitamin B2 in the light-resistant stabilizer fertilizer has the ability to resist ultraviolet radiation, which will effectively increase the fertilizer efficiency of the initial fertilizer of the vitamin B2 waste liquid and effectively overcome the problem of poor light stability of vitamin B2 in the fertilizer.

[0016] 2. The present invention provides a method for preparing a composite coated controlled-release fertilizer of vitamin B2 waste liquid, which adopts a process of composite coating of three layers of different coating materials, and provides a new coating method for coated controlled-release fertilizers. The coating material adopts polyolefin wax as the base coat. The use of polyolefin wax increases the specific surface area and smoothness of the particles, reduces the amount of film material used, and improves the initial controlled-release performance. The middle layer adopts starch as the main coating material. The raw material source is wide, low-priced and renewable, which reduces the use of petrochemical products and realizes the sustainable development of coating materials. At the same time, the starch coating material is biodegradable, and the membrane shell remaining in the soil can be degraded quickly; it promotes the development of coated controlled-release fertilizers towards environmental friendliness. The outermost layer adopts epoxy resin coating, which makes up for the shortcomings of strong hydrophilicity, dense micropores and strong swelling of bio-based polyurethane, increases the controlled release performance, wear resistance and extrusion resistance of the coated controlled-release fertilizer, and makes the fertilizer less likely to be damaged during transportation. DETAILED DESCRIPTION

[0017] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0018] Embodiment 1 The method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to an embodiment of the present invention comprises the following steps: Step 1: preparing a light-stable vitamin B2 waste liquid initial fertilizer: using soybean meal, corn syrup, starch and glucose as culture medium, fermenting with Ashwagandha yeast, Candida utilis, Saccharomyces cerevisiae, Bacillus subtilis and Corynebacterium ammoniagenes to extract vitamin B2, and then putting the fermentation waste liquid into a fermentation tank and heating it to 80-100°C to kill the bacteria; adding the following grams of raw materials to each liter of liquid: 100 grams of molasses, 50 grams of sodium glutamate, 6 grams of ammonium sulfate, 0.5 grams of magnesium sulfate, 15 grams of potassium dihydrogen phosphate, and 1 grams of light-stable stabilizer; using the liquid as culture medium, the culture condition is 37°C, the inoculation amount is 8% of Bacillus subtilis, and the rotation speed is 220r / min. After 22 to 24 hours, the light-stable vitamin B2 waste liquid initial liquid fertilizer is obtained, and then the light-stable vitamin B2 waste liquid initial liquid fertilizer and the binder are mixed by a spray granulation method, and the mixed liquid is sprayed into tiny droplets by a sprayer, and then these droplets are gradually solidified to form particles during the drying process; Among them, the binder can be corn starch: corn starch is a natural starch binder, often used to replace traditional chemical synthetic binders; bentonite: bentonite has good bonding properties; Step 2: preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer: adding fertilizer particles into a drum, and preheating the fertilizer to 50-70°C; spraying polyolefin wax onto the surface of the preheated fertilizer particles to form a polyolefin wax coating; uniformly mixing starch, a liquefier and a catalyst, heating them at 100-200°C for reaction, and cooling them to 80-100°C to obtain a starch liquefaction coating liquid; mixing the starch liquefaction coating liquid and a curing agent and spraying them onto the surface of the polyolefin wax coating of the fertilizer particles, curing them into a film, and forming a starch-based polyurethane layer; mixing an epoxy resin and an amine to prepare an epoxy resin mixed coating liquid; spraying the epoxy resin mixed coating liquid onto the surface of the starch-based polyurethane layer of the fertilizer particles, curing them into a film, and forming an epoxy resin, thereby obtaining a vitamin B2 waste liquid composite coated controlled-release fertilizer; The fertilizer particles are sequentially sprayed with a polyolefin wax coating, a starch-based polyurethane layer and an epoxy resin layer; the polyolefin wax coating accounts for 0.1% of the total weight of the fertilizer particles; the starch-based polyurethane layer accounts for 1.0% of the total weight of the fertilizer particles; the epoxy resin layer accounts for 1.0% of the total weight of the fertilizer particles; the wax used in the polyolefin wax coating is one or a mixture of poly-2-butene wax, poly-1-pentene wax, poly-3-hexene wax, poly-1-octene wax, poly-4-methyl-1-pentene wax or polypropylene wax; Most importantly, the preparation process of the light-resistant stabilizer includes the following steps: Dissolve 2,4-dihydroxybenzophenone in tetrahydrofuran, then add triethylamine to obtain a mixed solution A; the mass ratio of 2,4-dihydroxybenzophenone to the volume ratio of tetrahydrofuran is 1 g:2 mL; the mass ratio of 2,4-dihydroxybenzophenone to the volume ratio of triethylamine is 1 g:0.5 mL; Acryloyl chloride and tetrahydrofuran are mixed to obtain an acryloyl chloride solution, and the acryloyl chloride solution is dripped into the mixed solution A drop by drop at a temperature of 0°C-10°C for 0.5h-2h, and then reacted at a temperature of 0°C-10°C for 6h-12h to obtain a mixed solution B; the volume ratio of acryloyl chloride to tetrahydrofuran is 1:2; the volume ratio of acryloyl chloride solution to mixed solution A is 1:1; Under the condition of a centrifugal speed of 8000r / min-20000r / min, the mixed solution B is centrifuged for 10min-30min to obtain a supernatant, and the supernatant is dripped dropwise into a saturated sodium bicarbonate solution, and the solid is filtered to obtain a light-resistant stabilizer.

[0019] Embodiment 2 The method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to an embodiment of the present invention comprises the following steps: Step 1: preparing a light-stable vitamin B2 waste liquid initial fertilizer: using soybean meal, corn syrup, starch and glucose as culture medium, using Ashwagandha yeast, Candida utilis, Saccharomyces cerevisiae, Bacillus subtilis and Corynebacterium ammoniagenes to ferment and extract vitamin B2, and then putting the fermentation waste liquid into a fermentation tank and heating it to 80-100°C to kill the bacteria; adding the following grams of raw materials to each liter of liquid: 110 grams of molasses, 55 grams of sodium glutamate, 7 grams of ammonium sulfate, 0.6 grams of magnesium sulfate, 18 grams of potassium dihydrogen phosphate, and 2 grams of light-stable stabilizer; using the liquid as a culture medium, the culture condition is 37°C, the inoculation amount is 8% of Bacillus subtilis, and the rotation speed is 220 r / min. After 22 to 24 hours, the light-stable vitamin B2 waste liquid initial liquid fertilizer is obtained, and then the light-stable vitamin B2 waste liquid initial liquid fertilizer and a binder are mixed by a spray granulation method, and the mixed liquid is sprayed into tiny droplets by a sprayer, and then these droplets are gradually solidified to form particles during the drying process; Among them, the binder can be corn starch: corn starch is a natural starch binder, often used to replace traditional chemical synthetic binders; bentonite: bentonite has good bonding properties; Step 2: preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer: adding fertilizer particles into a drum, and preheating the fertilizer to 50-70°C; spraying polyolefin wax onto the surface of the preheated fertilizer particles to form a polyolefin wax coating; uniformly mixing starch, a liquefier and a catalyst, heating them at 100-200°C for reaction, and cooling them to 80-100°C to obtain a starch liquefaction coating liquid; mixing the starch liquefaction coating liquid and a curing agent and spraying them onto the surface of the polyolefin wax coating of the fertilizer particles, curing them into a film, and forming a starch-based polyurethane layer; mixing an epoxy resin and an amine to prepare an epoxy resin mixed coating liquid; spraying the epoxy resin mixed coating liquid onto the surface of the starch-based polyurethane layer of the fertilizer particles, curing them into a film, and forming an epoxy resin, thereby obtaining a vitamin B2 waste liquid composite coated controlled-release fertilizer; The fertilizer particles are sequentially sprayed with a polyolefin wax coating, a starch-based polyurethane layer and an epoxy resin layer; the polyolefin wax coating accounts for 0.5% of the total weight of the fertilizer particles; the starch-based polyurethane layer accounts for 5.0% of the total weight of the fertilizer particles; the epoxy resin layer accounts for 5.0% of the total weight of the fertilizer particles; the wax used in the polyolefin wax coating is one or a mixture of poly-2-butene wax, poly-1-pentene wax, poly-3-hexene wax, poly-1-octene wax, poly-4-methyl-1-pentene wax or polypropylene wax; Most importantly, the preparation process of the light-resistant stabilizer includes the following steps: Dissolve 2,4-dihydroxybenzophenone in tetrahydrofuran, then add triethylamine to obtain a mixed solution A; the mass ratio of 2,4-dihydroxybenzophenone to the volume ratio of tetrahydrofuran is 1 g:6 mL; the mass ratio of 2,4-dihydroxybenzophenone to the volume ratio of triethylamine is 1 g:1 mL; Acryloyl chloride and tetrahydrofuran are mixed to obtain an acryloyl chloride solution, and the acryloyl chloride solution is dripped into the mixed solution A drop by drop at a temperature of 0°C-10°C for 0.5h-2h, and then reacted at a temperature of 0°C-10°C for 6h-12h to obtain a mixed solution B; the volume ratio of acryloyl chloride to tetrahydrofuran is 1:4; the volume ratio of acryloyl chloride solution to mixed solution A is 1:2; Under the condition of a centrifugal speed of 8000r / min-20000r / min, the mixed solution B is centrifuged for 10min-30min to obtain a supernatant, and the supernatant is dripped dropwise into a saturated sodium bicarbonate solution, and the solid is filtered to obtain a light-resistant stabilizer.

[0020] Embodiment 3 The method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to an embodiment of the present invention comprises the following steps: Step 1: preparing a light-stable vitamin B2 waste liquid initial fertilizer: using soybean meal, corn syrup, starch and glucose as culture medium, fermenting with Ashwagandha yeast, Candida utilis, Saccharomyces cerevisiae, Bacillus subtilis and Corynebacterium ammoniagenes to extract vitamin B2, and then putting the fermentation waste liquid into a fermentation tank and heating it to 80-100°C to kill the bacteria; adding the following grams of raw materials to each liter of liquid: 120 grams of molasses, 60 grams of sodium glutamate, 8 grams of ammonium sulfate, 0.7 grams of magnesium sulfate, 20 grams of potassium dihydrogen phosphate, and 3 grams of light-stable stabilizer; using the liquid as a culture medium, the culture condition is 37°C, the inoculation amount is 8% of Bacillus subtilis, and the rotation speed is 220 r / min. After 22 to 24 hours, the light-stable vitamin B2 waste liquid initial liquid fertilizer is obtained, and then the light-stable vitamin B2 waste liquid initial liquid fertilizer and a binder are mixed by a spray granulation method, and the mixed liquid is sprayed into tiny droplets by a sprayer, and then these droplets are gradually solidified to form particles during the drying process; Among them, the binder can be corn starch: corn starch is a natural starch binder, often used to replace traditional chemical synthetic binders; bentonite: bentonite has good bonding properties; Step 2: preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer: adding fertilizer particles into a drum, and preheating the fertilizer to 50-70°C; spraying polyolefin wax onto the surface of the preheated fertilizer particles to form a polyolefin wax coating; uniformly mixing starch, a liquefier and a catalyst, heating them at 100-200°C for reaction, and cooling them to 80-100°C to obtain a starch liquefaction coating liquid; mixing the starch liquefaction coating liquid and a curing agent and spraying them onto the surface of the polyolefin wax coating of the fertilizer particles, curing them into a film, and forming a starch-based polyurethane layer; mixing an epoxy resin and an amine to prepare an epoxy resin mixed coating liquid; spraying the epoxy resin mixed coating liquid onto the surface of the starch-based polyurethane layer of the fertilizer particles, curing them into a film, and forming an epoxy resin, thereby obtaining a vitamin B2 waste liquid composite coated controlled-release fertilizer; The fertilizer particles are sequentially sprayed with a polyolefin wax coating, a starch-based polyurethane layer and an epoxy resin layer; the polyolefin wax coating accounts for 1.0% of the total weight of the fertilizer particles; the starch-based polyurethane layer accounts for 10.0% of the total weight of the fertilizer particles; the epoxy resin layer accounts for 10.0% of the total weight of the fertilizer particles; the wax used in the polyolefin wax coating is one or a mixture of poly-2-butene wax, poly-1-pentene wax, poly-3-hexene wax, poly-1-octene wax, poly-4-methyl-1-pentene wax or polypropylene wax; Most importantly, the preparation process of the light-resistant stabilizer includes the following steps: Dissolve 2,4-dihydroxybenzophenone in tetrahydrofuran, then add triethylamine to obtain a mixed solution A; the mass ratio of 2,4-dihydroxybenzophenone to the volume ratio of tetrahydrofuran is 1 g:10 mL; the mass ratio of 2,4-dihydroxybenzophenone to the volume ratio of triethylamine is 1 g:2 mL; Acryloyl chloride and tetrahydrofuran are mixed to obtain an acryloyl chloride solution, and the acryloyl chloride solution is dripped into the mixed solution A drop by drop at a temperature of 0°C-10°C for 0.5h-2h, and then reacted at a temperature of 0°C-10°C for 6h-12h to obtain a mixed solution B; the volume ratio of acryloyl chloride to tetrahydrofuran is 1:7; the volume ratio of acryloyl chloride solution to mixed solution A is 1:3; Under the condition of a centrifugal speed of 8000r / min-20000r / min, the mixed solution B is centrifuged for 10min-30min to obtain a supernatant, and the supernatant is dripped dropwise into a saturated sodium bicarbonate solution, and the solid is filtered to obtain a light-resistant stabilizer.

[0021] Comparative Example 1 Comparative Example 1 adopts the method disclosed in Chinese Patent No. CN 108821828 B to produce liquid fertilizer containing polyglutamic acid by using fermentation tail liquid; In order to more intuitively illustrate the effect of the liquid fertilizer containing polyglutamic acid obtained in the embodiment of the present invention, the inventors selected a plurality of planting test fields with the same conditions in all aspects, randomly selected planting test fields with the same variety of tomatoes, the same fertility, and the same management, and applied 10 kg of fertilizer of the same weight as that of Example 9 in Comparative Example 1 and Examples 1-3 of the present invention. Except for the different fertilizers applied, the other growth conditions of the three groups of tests were the same. The data related to the growth of tomatoes are shown in Table 1:

[0022] Judging from the above data, the vitamin B2 waste liquid composite coated controlled-release fertilizer prepared by the present invention has better fertilization effect, which is more attributed to the photostability stabilizer added to the fertilizer of the present invention, which effectively overcomes the problem of poor photostability of vitamin B2 in the fertilizer.

[0023] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer, characterized in that: The following steps are involved: Step 1: preparing a light-stable vitamin B2 waste liquid initial fertilizer: using soybean meal, corn syrup, starch and glucose as culture medium, using Ashwagandha yeast, Candida utilis, Saccharomyces cerevisiae, Bacillus subtilis and Corynebacterium ammoniagenes to ferment and extract vitamin B2, and then putting the fermentation waste liquid into a fermentation tank and heating it to 80-100°C to kill the bacteria; adding a raw material containing a light-stable stabilizer to each liter of liquid; using the liquid as a culture medium, the culture condition is 37°C, the inoculation amount is 8% Bacillus subtilis, and the rotation speed is 220r / min. After 22 to 24 hours, the light-stable vitamin B2 waste liquid initial liquid fertilizer is obtained, and then the light-stable vitamin B2 waste liquid initial liquid fertilizer and a binder are mixed by a spray granulation method, and the mixed liquid is sprayed into tiny droplets by a sprayer, and then these droplets are gradually solidified to form particles during the drying process; Step 2: Prepare vitamin B2 waste liquid composite coated controlled-release fertilizer: add fertilizer particles into a rotating drum, and prepare vitamin B2 waste liquid composite coated controlled-release fertilizer by coating technology.

2. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 1, characterized in that: In step 1, the raw materials containing the light-resistant stabilizer are as follows: 100-120 grams of molasses, 50-60 grams of sodium glutamate, 6-8 grams of ammonium sulfate, 0.5-0.7 grams of magnesium sulfate, 15-20 grams of potassium dihydrogen phosphate, and 1-3 grams of the light-resistant stabilizer.

3. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 2, characterized in that: In step 1, the binder includes corn starch and bentonite.

4. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 3, characterized in that: The preparation process of the light-resistant stabilizer comprises the following steps: Dissolve 2,4-dihydroxybenzophenone in tetrahydrofuran, then add triethylamine to obtain a mixed solution A; Acryloyl chloride and tetrahydrofuran are mixed to obtain an acryloyl chloride solution, and the acryloyl chloride solution is dripped into the mixed solution A drop by drop at a temperature of 0°C-10°C for 0.5h-2h, and then reacted at a temperature of 0°C-10°C for 6h-12h to obtain a mixed solution B; Under the condition of a centrifugal speed of 8000r / min-20000r / min, the mixed solution B is centrifuged for 10min-30min to obtain a supernatant, and the supernatant is dripped dropwise into a saturated sodium bicarbonate solution, and the solid is filtered to obtain a light-resistant stabilizer.

5. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 4, characterized in that: The mass ratio of 2,4-dihydroxybenzophenone to the volume of tetrahydrofuran is 1g:(2-10)mL.

6. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 5, characterized in that: In step 1, the mass ratio of 2,4-dihydroxybenzophenone to the volume ratio of triethylamine is 1 g:(0.5-2) mL.

7. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 6, characterized in that: The volume ratio of acryloyl chloride to tetrahydrofuran is 1:(2-7); the volume ratio of acryloyl chloride solution to mixed solution A is 1:(1-3).

8. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 7, characterized in that: In step 1, fertilizer particles are added to a rotating drum, and the fertilizer is preheated to 50-70° C.; polyolefin wax is sprayed onto the surface of the preheated fertilizer particles to form a polyolefin wax coating; starch, a liquefier and a catalyst are mixed evenly, heated at 100-200° C. for reaction, and cooled to 80-100° C. to obtain a starch liquefaction coating liquid; the starch liquefaction coating liquid and a curing agent are mixed and sprayed onto the surface of the polyolefin wax coating of the fertilizer particles, and cured into a film to form a starch-based polyurethane layer; Mixing epoxy resin and amine to prepare epoxy resin mixed coating liquid; The epoxy resin mixed coating liquid is sprayed onto the surface of the starch-based polyurethane layer of the fertilizer particles, and solidified into a film to form an epoxy resin, thereby obtaining a vitamin B2 waste liquid composite coated controlled-release fertilizer.

9. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 8, characterized in that: The fertilizer particles are sequentially sprayed with a polyolefin wax coating, a starch-based polyurethane layer and an epoxy resin layer; the polyolefin wax coating accounts for 0.1-1.0% of the total weight of the fertilizer particles; the starch-based polyurethane layer accounts for 1.0-10.0% of the total weight of the fertilizer particles; and the epoxy resin layer accounts for 1.0-10.0% of the total weight of the fertilizer particles.

10. A method for preparing a vitamin B2 waste liquid composite coated controlled-release fertilizer according to claim 9, characterized in that: In step 1, the wax used in the polyolefin wax coating is one or a mixture of poly-2-butene wax, poly-1-pentene wax, poly-3-hexene wax, poly-1-octene wax, poly-4-methyl-1-pentene wax or polypropylene wax.

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