High-phosphorus carbon-based stable fertilizer and preparation method thereof

Abstract

The invention provides a high-phosphorus carbon-based stable fertilizer and a preparation method thereof, and belongs to the technical field of fertilizers. The high-phosphorus type carbon-based stable fertilizer disclosed by the invention is prepared from the following components in parts by weight: 110 to 120 parts of phosphoric acid, 50 to 60 parts of urea, 20 to 50 parts of biochar and 0.3 to 0.8 part of N-n-butyl thiophosphoric triamine. The carbon-based fertilizer is prepared by adopting a blending crystallization method, so that the charcoal can be fully contacted and reacted with each component, and the formed carbon-based fertilizer is uniform in nutrient distribution. In the fertilizer preparation process, nutrient volatilization loss is avoided, and the actual nutrient content is equal to the theoretically calculated nutrient content. According to the prepared carbon-based fertilizer, all nutrients can be fully loaded on the biochar, the release and leaching speed of the nutrients is slowed down, the urease inhibitor N-n-butyl thiophosphoric triamine is added in a coupled mode, and the nitrogen fertilizer utilization rate is increased. The carbon-based fertilizer prepared by the invention is a slow-release nitrogen functional fertilizer, is acidic, and can be applied to barrier soil such as saline-alkali soil and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizers, and in particular relates to a high-phosphorus carbon-based stable fertilizer and a preparation method thereof. Background Art

[0002] Food security is inseparable from national security and is crucial in the process of national stability and development. Fertilizer, as "food of food", plays an irreplaceable role in agricultural crop production. The results of more than 5,000 fertilizer efficiency tests conducted by my country's National Fertilizer Experiment Network in the 1980s also proved that the reasonable application of fertilizers on rice, wheat and corn increased the yield by an average of 48% compared with the control without fertilizer. New fertilizers such as coated slow-release fertilizers are considered to be one of the effective ways to effectively improve the above problems.

[0003] Biochar is a porous, stable, and rich carbon product obtained by high-temperature pyrolysis of biomass such as agricultural and forestry waste under oxygen-limited conditions. Due to its special physical and chemical properties and structure, biochar can improve soil physical and chemical properties, enhance soil water holding capacity, and reduce soil nutrient leaching. However, due to the limited nutrient content in biochar, the application of single biochar cannot provide sufficient nutrients for crops, so it is generally prepared as a carbon-based fertilizer for use as a fertilizer. Biochar-based composite / compound fertilizers are generally made by mixing biochar with chemical fertilizers (nitrogen, phosphorus, potassium fertilizers, etc.), organic fertilizers (such as livestock and poultry manure, straw, etc.), and other ingredients that may be contained (such as trace elements, biologically active substances, etc.) in a certain proportion, using chemical methods and (or) physical methods to make fertilizers. Biochar has developed pores, a large specific surface area, rich functional groups, adsorption, and can absorb nutrients; the rich pore structure can reduce the contact between the nutrients embedded in it and water and soil, so biochar can be used as an excellent fertilizer carrier, which plays a role in slow release of fertilizer nutrients and improves fertilizer utilization. Biochar-based fertilizers made by mixing biochar with organic fertilizers / inorganic fertilizers have been proven to have a positive effect on soil physical and chemical properties and crop growth and development. Nowadays, biochar-based fertilizers are gaining more and more attention worldwide due to their advantages in improving soil physical and chemical properties, repairing environmental pollution, regulating nutrient release rates, and improving fertilizer utilization. Traditional carbon-based fertilizer preparation technologies mainly include blending, coating, mixed granulation, solid-liquid adsorption, and co-pyrolysis. However, the carbon-based fertilizers prepared by traditional processes have the disadvantages of difficulty in sufficient contact and reaction between biochar and fertilizers, high preparation costs, and complicated preparation processes. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a high-phosphorus carbon-based stable fertilizer and a preparation method thereof. The high-phosphorus carbon-based stable fertilizer is prepared by a blended crystallization method, which can enable sufficient contact and reaction between biochar and fertilizer, and the preparation process is simple. The nutrient distribution of the formed carbon-based fertilizer is uniform, and on this basis, the addition of urease inhibitor N-n-butylthiophosphoric acid triamide can improve the utilization rate of nitrogen fertilizer.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a high-phosphorus carbon-based stable fertilizer, comprising the following components in parts by weight:

[0007] 110-120 parts of phosphoric acid, 50-60 parts of urea, 20-50 parts of biochar, and 0.3-0.8 parts of N-n-butylthiophosphoric acid triamide.

[0008] Preferably, the phosphoric acid is wet-process phosphoric acid, and the mass fraction of the phosphoric acid is 70-80%.

[0009] The present invention also provides a method for preparing the high-phosphorus carbon-based stable fertilizer, comprising the following steps:

[0010] 1) mixing phosphoric acid and urea, reacting to generate urea phosphate;

[0011] 2) reacting urea phosphate and biochar to obtain product A;

[0012] 3) reacting the product A with N-n-butylthiophosphoric acid triamide, crystallizing, and drying to obtain a high-phosphorus carbon-based stable fertilizer.

[0013] Preferably, the biochar is obtained by high-temperature pyrolysis of corn stalks, the temperature of the high-temperature pyrolysis is 400-500° C., and the time of the high-temperature pyrolysis is 2-6 hours.

[0014] Preferably, the reaction temperature in step 1) is 70-75° C., and the reaction time is 30-40 min.

[0015] Preferably, the reaction temperature in step 2) is 70-75° C., and the reaction time is 30-50 min.

[0016] Preferably, the reaction temperature in step 3) is 70-75° C., and the reaction time is 10-30 min.

[0017] Preferably, the crystallization temperature in step 3) is 24-28° C., and the crystallization time is 18-30 hours.

[0018] Preferably, the drying temperature in step 3) is 50-60° C., and the drying time is 12-36 hours.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention adopts a co-crystallization method to prepare carbon-based fertilizer, which can make biochar fully contact and react with each component, and the nutrients of the formed carbon-based fertilizer are evenly distributed. In addition, during the fertilizer preparation process, there is no nutrient volatilization loss, and the actual nutrient content is equal to the theoretically calculated nutrient content.

[0021] The carbon-based fertilizer prepared by the present invention can fully load various nutrients on biochar, slow down the speed of nutrient release and leaching, and add urease inhibitor N-n-butylthiophosphoric acid triamide to delay the conversion and release of nitrogen and improve the utilization rate of nitrogen fertilizer. The fertilizer product has the slow-release performance of stable fertilizer and endows biochar with functions, and is a slow-release nitrogen functional fertilizer.

[0022] The carbon-based fertilizer prepared by the invention is acidic and can be used as a special functional fertilizer in specific environments, such as saline-alkali land and other obstructive soils. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the difference rate of urea residue of high-phosphorus carbon-based stable fertilizers prepared in different embodiments. DETAILED DESCRIPTION

[0024] The present invention provides a high-phosphorus carbon-based stable fertilizer, comprising the following components in parts by weight:

[0025] 110-120 parts of phosphoric acid, 50-60 parts of urea, 20-50 parts of biochar, and 0.3-0.8 parts of N-n-butylthiophosphoric acid triamide.

[0026] In the present invention, the amount of phosphoric acid is preferably 102 to 115 parts, the phosphoric acid is preferably wet-process phosphoric acid, the mass fraction of the phosphoric acid is preferably 70 to 80%, and more preferably 72 to 78%; the amount of urea is preferably 52 to 58 parts; the amount of biochar is preferably 25 to 45 parts; the amount of N-n-butylthiophosphoric acid triamide is preferably 0.4 to 0.7 parts.

[0027] The present invention also provides a method for preparing the high-phosphorus carbon-based stable fertilizer, comprising the following steps:

[0028] 1) mixing phosphoric acid and urea, reacting to generate urea phosphate;

[0029] 2) reacting urea phosphate and biochar to obtain product A;

[0030] 3) reacting the product A with N-n-butylthiophosphoric acid triamide, crystallizing, and drying to obtain a high-phosphorus carbon-based stable fertilizer.

[0031] In the present invention, the biochar is obtained by high-temperature pyrolysis of corn straw. The corn straw is cut into segments before high-temperature pyrolysis, and the length of the segments is preferably 1 to 3 cm, and more preferably 1.5 to 2.5 cm; the temperature of the high-temperature pyrolysis is preferably 400 to 500°C, and more preferably 420 to 480°C; the time of the high-temperature pyrolysis is preferably 2 to 6 hours, and more preferably 3 to 5 hours.

[0032] In the present invention, phosphoric acid and urea are mixed and reacted to generate urea phosphate. The phosphoric acid is preheated before the reaction, and the reaction temperature is preferably 70 to 75° C., more preferably 71 to 74° C.; the reaction time is preferably 30 to 40 minutes, more preferably 32 to 38 minutes.

[0033] In the present invention, urea phosphate and biochar are reacted to obtain product A. The reaction temperature is preferably 70-75° C., more preferably 71-74° C.; the reaction time is preferably 30-50 min, more preferably 35-45 min.

[0034] In the present invention, product A is reacted with N-n-butylthiophosphoric acid triamide, crystallized, and dried to obtain a high-phosphorus carbon-based stable fertilizer. The reaction temperature is preferably 70-75°C, more preferably 71-74°C; the reaction time is preferably 10-30 minutes, more preferably 15-25 minutes; the crystallization temperature is preferably 24-28°C, more preferably 25-27°C, the crystallization time is preferably 18-30 hours, more preferably 21-27 hours; the drying temperature is preferably 50-60°C, more preferably 50-60°C, and the drying time is preferably 12-36 hours, more preferably 18-30 hours.

[0035] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] Example 1

[0037] A high-phosphorus carbon-based stable fertilizer is composed of the following components in parts by weight: 113.5 parts of 75% wet-process phosphoric acid, 53 parts of urea, 24.5 parts of biochar, and 0.5 part of N-n-butylthiophosphoric acid triamide.

[0038] The preparation method is as follows:

[0039] S1. First, take the corn stalks, wash and dry them, cut them into 2 cm small segments with a guillotine, slowly heat them to 450 °C and pyrolyze them for 4 hours, cool and grind them, sieve them, put them into self-sealing bags and seal them as biochar raw materials for later use;

[0040] S2, set the water bath to 72.5°C, add 113.5 parts of 75% wet-process phosphoric acid into the reactor for preheating, and then add 53 parts of urea to react for 35 minutes;

[0041] After the reaction of S3 and S2 was completed, 24.5 parts of biochar prepared in S1 were added to the reactor and continued to react at 72.5°C for 35 min;

[0042] After the reaction in S4 and S3 is completed, 0.5 parts of urease inhibitor N-n-butylthiophosphoric acid triamide is added and reacted at a temperature of 72.5°C for 15 minutes;

[0043] S5. Pour the reaction product into a crystallization dish, crystallize it at room temperature for 24 hours, and then put it into an oven at 55°C for 24 hours to obtain a high-phosphorus carbon-based stable fertilizer.

[0044] Example 2

[0045] A high-phosphorus carbon-based stable fertilizer is composed of the following components in parts by weight: 113.5 parts of 75% wet-process phosphoric acid, 53 parts of urea, 34.5 parts of biochar, and 0.5 part of N-n-butylthiophosphoric acid triamide.

[0046] The preparation method is as follows:

[0047] S1. First, take the corn stalks, wash and dry them, cut them into 2 cm small segments with a guillotine, slowly heat them to 450 °C and pyrolyze them for 4 hours, cool and grind them, sieve them, put them into self-sealing bags and seal them as biochar raw materials for later use;

[0048] S2, set the water bath to 72.5°C, add 113.5 parts of 75% wet-process phosphoric acid into the reactor for preheating, then add 53 parts of urea and continue the reaction for 35 minutes;

[0049] After the reaction of S3 and S2 was completed, 34.5 parts of biochar prepared in S1 were added to the reactor and continued to react at 72.5°C for 35 min;

[0050] After the reaction in S4 and S3 is completed, 0.5 parts of urease inhibitor N-n-butylthiophosphoric acid triamide is added and reacted at a temperature of 72.5°C for 15 minutes;

[0051] S5. Pour the reaction product into a crystallization dish, crystallize it at room temperature for 24 hours, and then put it into an oven at 55°C for 24 hours to obtain a high-phosphorus carbon-based stable fertilizer.

[0052] Example 3

[0053] A high-phosphorus carbon-based stable fertilizer is composed of the following components in parts by weight: 113.5 parts of 75% wet-process phosphoric acid, 53 parts of urea, 46 parts of biochar, and 0.5 parts of N-n-butylthiophosphoric acid triamide.

[0054] The preparation method is as follows:

[0055] S1. First, take the corn stalks, wash and dry them, cut them into 2 cm small segments with a guillotine, slowly heat them to 450 °C and pyrolyze them for 4 hours, cool and grind them, sieve them, put them into self-sealing bags and seal them as biochar raw materials for later use;

[0056] S2. Set the water bath to 72.5°C, add 113.5 parts of 75% wet-process phosphoric acid into the reactor for preheating, then add urea and continue the reaction for 35 minutes;

[0057] After the reaction of S3 and S2 was completed, 46 portions of biochar prepared in S1 were added to the reactor and continued to react at 72.5°C for 35 min;

[0058] After the reaction in S4 and S3 is completed, 0.5 parts of urease inhibitor N-n-butylthiophosphoric acid triamide is added and reacted at a temperature of 72.5°C for 15 minutes;

[0059] S5. Pour the reaction product into a crystallization dish, crystallize it at room temperature for 24 hours, and then put it into an oven at 55°C for 24 hours to obtain a high-phosphorus carbon-based stable fertilizer.

[0060] Experimental Example 1

[0061] Determination of nutrient content and biochar content in high-phosphorus carbon-based stable fertilizer

[0062] The P2O5 and N contents of fertilizer nutrients were determined by fully automatic intermittent chemical analyzer and continuous flow analyzer respectively after H2SO4-H2O2 digestion; the urea content determination method referred to the urea determination method in the national standard for stable fertilizers (GB / T35113-2017); the total nutrient content was the sum of P2O5 and N contents; the biochar content was the biochar mass / (pure phosphoric acid mass + urea mass + biochar mass) when the carbon-based fertilizer was prepared.

[0063] Since biochar itself carries a variety of mineral elements, such as K + , Ca 2+ Mg 2+ Etc., so the prepared carbon-based fertilizer also contains other trace elements beneficial to plant growth, etc. Since these elements are not mainly involved in the present invention, they are not indicated in Table 1, but it should be clear that they exist in the prepared carbon-based fertilizer.

[0064] Experimental results: as shown in Table 1.

[0065] Table 1 Nutrient content and biochar content in high-phosphorus carbon-based stable fertilizers

[0066] deal with <![CDATA[P2O5 content]]> N content Urea content Total nutrient content Biochar content Example 1 37％ 15％ 29％ 52％ 15％ Example 2 35％ 14％ 27％ 49％ 20％ Example 3 33％ 13％ 25％ 46％ 25％

[0067] It can be seen from Table 1 that the high-phosphorus carbon-based stable fertilizer prepared by the present invention has no nutrient volatilization loss, and the actual nutrient content is equal to the theoretically calculated nutrient content.

[0068] Experimental Example 2

[0069] Determination of urea residual difference rate in high phosphorus carbon-based stable fertilizer

[0070] The method for determining the difference rate of urea residues refers to the national standard for stable fertilizers GB / T 35113-2017.

[0071] Experimental results: Figure 1 As shown. Figure 1 It can be seen that with the increase of biochar addition, the urea residual difference rate shows a downward trend. As the amount of biochar added increases, the specific surface area provided by the biochar in the carbon-based fertilizer increases, providing more reaction sites for urease and urea, resulting in more urea being decomposed and the urea residual difference rate becoming smaller.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-phosphorus carbon-based stable fertilizer, characterized in that: The composition comprises the following components in parts by weight: 110-120 parts of phosphoric acid, 50-60 parts of urea, 20-50 parts of biochar, and 0.3-0.8 parts of N-n-butylthiophosphoric acid triamide.

2. The high-phosphorus carbon-based stable fertilizer according to claim 1, characterized in that: The phosphoric acid is wet-process phosphoric acid, and the mass fraction of the phosphoric acid is 70-80%.

3. The method for preparing the high-phosphorus carbon-based stable fertilizer according to claim 1 or 2, characterized in that: The following steps are involved: 1) mixing phosphoric acid and urea, reacting to generate urea phosphate; 2) reacting urea phosphate and biochar to obtain product A; 3) reacting the product A with N-n-butylthiophosphoric acid triamide, crystallizing, and drying to obtain a high-phosphorus carbon-based stable fertilizer.

4. The preparation method according to claim 3, characterized in that: The biochar is obtained by high-temperature pyrolysis of corn stalks, the temperature of the high-temperature pyrolysis is 400-500° C., and the time of the high-temperature pyrolysis is 2-6 hours.

5. The preparation method according to claim 3, characterized in that: Step 1) The reaction temperature is 70-75°C and the reaction time is 30-40 minutes.

6. The preparation method according to claim 3, characterized in that: Step 2) The reaction temperature is 70-75°C and the reaction time is 30-50 min.

7. The preparation method according to claim 3, characterized in that: Step 3) The reaction temperature is 70-75°C and the reaction time is 10-30 min.

8. The preparation method according to claim 3, characterized in that: Step 3) The crystallization temperature is 24-28° C. and the crystallization time is 18-30 hours.

9. The preparation method according to claim 3, characterized in that: Step 3) The drying temperature is 50-60° C. and the drying time is 12-36 hours.

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