Preparation method of high-concentration liquid urea phosphate

Abstract

The invention discloses a preparation method of high-concentration liquid urea phosphate, which comprises the following steps: diluting 85% phosphoric acid, reacting with urea, sequentially adding a crystal inhibitor and a surfactant, and cooling to obtain the product. The prepared liquid urea phosphate contains 8%-14% of total nitrogen and 22%-38% of available phosphorus, the specific gravity is 1.4-1.6 g / ml, the pH is smaller than or equal to 3, and the liquid urea phosphate is homogeneous-phase clear liquid. According to the method, the solubility of urea phosphate is improved, crystallization is inhibited and the stability of the product is guaranteed through cooperation of an innovative process and auxiliaries; and the preparation process is mild and controllable, and large-scale production is facilitated. The product is high in nutrient enrichment degree, wide in applicability in the fields of agriculture, animal husbandry, industry and the like, and capable of meeting the requirements of multiple scenes and expanding the application boundary.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical fertilizers, and in particular to a method for producing high-concentration liquid urea phosphate. Background Art

[0002] Urea phosphate, a compound fertilizer containing both phosphorus and nitrogen, two important nutrients, plays a key role in multiple fields. In agriculture, with the increasing adoption of precision and efficient fertilization in modern agriculture, liquid fertilizers, with their advantages such as rapid nutrient absorption, convenient application, and integration with irrigation systems, have become a key option for improving crop yield and quality. The phosphorus in urea phosphate helps promote root development and enhance crop resistance, while nitrogen is essential for the synthesis of key substances such as protein during crop growth. Therefore, urea phosphate is widely used in a variety of fertilizer products, including foliar fertilizers and drip irrigation fertilizers. In the livestock industry, urea phosphate is used as a feed additive for ruminants. The non-protein nitrogen it contains is effectively utilized by rumen microorganisms and converted into microbial protein, thereby increasing the animal's protein intake and promoting growth and development. Furthermore, in the industrial sector, urea phosphate serves as a key raw material for flame retardants, cleaning agents, electroplating solutions, and other products, and is used in various industrial processes.

[0003] However, the physical and chemical properties of urea phosphate itself limit the further expansion of its application. Under normal temperature conditions, the solubility of urea phosphate is low. This low solubility characteristic makes it easy for crystallization to occur when preparing high-concentration liquid urea phosphate products. Once crystals are formed, not only will the uniformity of the product be destroyed, affecting its appearance and stability, but it will also cause a series of problems such as container blockage and poor pipeline during storage and transportation, greatly increasing the cost of use and maintenance. Traditional liquid urea phosphate products cannot effectively solve the crystallization problem. During storage, additional insulation measures or frequent stirring are required to delay the crystallization process, which undoubtedly increases the production cost and operational complexity of the product. At the same time, low solubility also limits the concentration of nutrients in the product, making it difficult to meet the demand for high-concentration liquid fertilizers in modern agriculture. Therefore, developing a manufacturing method that can significantly improve the solubility of urea phosphate, inhibit crystal formation, and at the same time ensure high nutrient content and good stability of the product has become a key issue that needs to be urgently addressed in the industry. Summary of the Invention

[0004] The object of the present invention is to provide a high-concentration liquid urea phosphate and a preparation method thereof. By optimizing process parameters and adding specific additives, the solubility of urea phosphate at room temperature is significantly improved, thereby solving the problem of easy crystallization of existing liquid urea phosphate products, while ensuring the stability and nutrient content of the product.

[0005] To achieve the above objectives, the present invention adopts the following technical means:

[0006] A method for producing high-concentration liquid urea phosphate comprises the following steps:

[0007] Step 1: dilute 85% phosphoric acid with water to a 50%-75% phosphoric acid solution, then heat to 50°C-60°C to obtain pure phosphoric acid.

[0008] Step 2: Add urea at a molar ratio of 1:1-1.2 to phosphoric acid until completely dissolved, and maintain the reaction temperature at 50°C-60°C for 1-2 hours;

[0009] Step 3: Add 0.3%-0.8% of the total mass of the reaction solution to the crystal inhibitor and stir at a constant temperature for 1-2 hours;

[0010] Step 4: Add 0.1%-0.3% of the total mass of the obtained solution as a surfactant and stir at a constant temperature for 1-2 hours;

[0011] Step 5: Cool the solution to room temperature to obtain a homogeneous clear liquid urea phosphate.

[0012] Preferably, the crystal inhibitor is one or more combinations of sodium polyacrylate, polyaspartic acid, and sodium lignin sulfonate.

[0013] Preferably, the surfactant is one or more combinations of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and sodium dodecylbenzene sulfonate.

[0014] Preferably, the concentration of phosphoric acid after dilution in step 1 is 60%-70%.

[0015] Preferably, the molar ratio of urea to phosphoric acid in step 2 is 1:1.05-1.15.

[0016] Preferably, the amount of the crystal inhibitor added in step 3 is 0.4%-0.6% of the total mass of the reaction solution.

[0017] Preferably, the amount of surfactant added in step 4 is 0.15%-0.25% of the total mass of the obtained solution.

[0018] A high-concentration liquid urea phosphate is prepared by a high-concentration liquid urea phosphate manufacturing method. The high-concentration liquid urea phosphate contains 8%-14% total nitrogen, 22%-38% available phosphorus, a specific gravity of 1.4-1.6 g / ml, a pH value of ≤3, and is a homogeneous clear liquid.

[0019] The present invention has the following beneficial effects:

[0020] 1. Significantly improved solubility: Through innovative process design and the synergistic effect of specific additives, the inherent limitation of low solubility of urea phosphate at room temperature is overcome, its solubility in solution is greatly improved, creating conditions for the formation of a high-concentration uniform system and significantly enhancing the content of active ingredients in the product.

[0021] 2. Enhanced stability: The combination of crystal inhibitors and surfactants effectively inhibits the crystallization process of urea phosphate, ensuring that the product remains in a homogeneous and stable state during storage and transportation at room temperature, avoiding quality degradation and usage obstacles caused by crystallization, and significantly improving product storage reliability and applicability.

[0022] 3. High nutrient content: The liquid urea phosphate product can achieve efficient enrichment of phosphorus and nitrogen nutrients, which can fully meet the stringent demand for high-content phosphorus and nitrogen raw materials in agriculture, animal husbandry and industry, provide high-quality and stable nutrient supply for applications in various fields, and enhance the application value of the product.

[0023] 4. Simple and controllable process: The entire preparation process has mild operating conditions and does not require special equipment or complex processes. The step parameters are clear and easy to control. It has good repeatability and large-scale production potential, which helps to reduce production costs, improve production efficiency, and facilitates widespread promotion within the industry.

[0024] 5. Multifunctional application expansion: With its excellent stability and high nutritional properties, the product has a wider range of applicability in agriculture, animal husbandry, industry and other fields. It can adapt to diverse application scenarios and usage needs, effectively expanding the boundaries of product application. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] A method for producing high-concentration liquid urea phosphate comprises the following steps:

[0028] Step 1: Phosphoric acid dilution and preheating: Dilute 85% phosphoric acid with water to a 50%-75% phosphoric acid solution, then heat to 50°C-60°C to obtain the molar amount of pure phosphoric acid;

[0029] Step 2: Urea reaction: Add urea at a molar ratio of 1:1-1.2 to phosphoric acid until completely dissolved, maintain the reaction temperature at 50°C-60°C and react for 1-2 hours;

[0030] Step 3: Adding a crystal inhibitor: Add 0.3%-0.8% of the total mass of the reaction solution to the crystal inhibitor and stir at a constant temperature for 1-2 hours;

[0031] Step 4: Add surfactant: add 0.1%-0.3% of the total mass of the obtained solution to the surfactant and stir at constant temperature for 1-2 hours;

[0032] Step 5: Cooling and aging: Cool the solution to room temperature, the reaction is completed, and a homogeneous clear liquid urea phosphate is obtained.

[0033] Optimal technical solution

[0034] The crystal inhibitor is one or more combinations of sodium polyacrylate, polyaspartic acid, and sodium lignin sulfonate.

[0035] The surfactant is one or more combinations of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and sodium dodecylbenzene sulfonate.

[0036] The concentration of phosphoric acid after dilution in step 1 is preferably 60%-70%.

[0037] The molar ratio of urea to phosphoric acid in step 2 is preferably 1:1.05-1.15.

[0038] The amount of the crystal inhibitor added in step 3 is preferably 0.4%-0.6% of the total mass of the reaction solution.

[0039] The amount of surfactant added in step 4 is preferably 0.15%-0.25% of the total mass of the obtained solution.

[0040] Product Specifications

[0041] The obtained high-concentration liquid urea phosphate product has the following characteristics:

[0042] Contains 8%-14% total nitrogen (110g / L-200g / L);

[0043] Contains 22%-38% available phosphorus (300g / L-560g / L);

[0044] Specific gravity 1.4-1.6g / ml;

[0045] pH ≤ 3;

[0046] It remains in a homogeneous clear liquid state at room temperature without crystal precipitation.

[0047] Technical Effects

[0048] The solubility is significantly improved: compared with the saturated solubility of liquid urea phosphate at 25°C and 1 atm (58.6g / 100mLH2O), the present invention increases the solubility of urea phosphate at room temperature by 1-1.5 times.

[0049] Enhanced stability: By adding specific crystal inhibitors and surfactants, the crystallization of urea phosphate is effectively inhibited. The product will not crystallize when stored at room temperature for more than 6 months.

[0050] High nutrient content: The total nutrient content of the product can reach 30%-52%, meeting the needs of high-concentration liquid fertilizer.

[0051] The process is simple and controllable: the reaction conditions are mild, the operation is simple, and it is easy to industrialize.

[0052] Example 2

[0053] A method for producing high-concentration liquid urea phosphate comprises the following steps:

[0054] Phosphoric acid dilution and preheating: Take 1000 g of 85% phosphoric acid and add appropriate amount of water to dilute it to 60% concentration. Then heat the diluted phosphoric acid solution to 55°C and accurately calculate the molar amount of pure phosphoric acid.

[0055] Urea reaction: According to the molar ratio of phosphoric acid to urea of ​​1:1.1, weigh 458 g of urea and add it to the above phosphoric acid solution. Stir until completely dissolved. Maintain the reaction solution temperature at 55°C and continue the reaction for 1.5 hours.

[0056] Addition of crystal inhibitor: add 0.5% of the total mass of the reaction solution of sodium polyacrylate as a crystal inhibitor to the reaction solution, maintain the temperature at 55° C., and stir at constant temperature for 1.5 hours.

[0057] Surfactant addition: 0.2% of the total mass of the obtained solution of fatty alcohol polyoxyethylene ether was added as a surfactant, and stirring was continued at a constant temperature of 55° C. for 1.5 hours.

[0058] Cooling and finished product: The solution after the reaction is cooled to room temperature and tested to obtain a homogeneous clear liquid urea phosphate.

[0059] Example 3

[0060] A method for producing high-concentration liquid urea phosphate comprises the following steps:

[0061] Phosphoric acid dilution and preheating: Dilute 1200 g of 85% phosphoric acid with water to a 70% phosphoric acid solution, then heat to 60°C to complete the calculation of the molar weight of phosphoric acid.

[0062] Urea reaction: Add 515 g of urea at a molar ratio of 1:1.05 to phosphoric acid, stir until the urea is completely dissolved, maintain the reaction solution temperature at 60°C, and react for 1 hour.

[0063] Addition of crystal inhibitor: 0.4% of the total mass of the reaction solution of polyaspartic acid as a crystal inhibitor was added, and the mixture was stirred at a constant temperature of 60° C. for 1 hour.

[0064] Addition of surfactant: 0.15% of the total mass of the obtained solution of sodium dodecylbenzenesulfonate as a surfactant was added to the solution, and stirred at a constant temperature of 60° C. for 1 hour.

[0065] Cooling and finished product: Cool the solution to room temperature to obtain high-concentration liquid urea phosphate that meets the requirements.

[0066] Example 4

[0067] A method for producing high-concentration liquid urea phosphate comprises the following steps:

[0068] Phosphoric acid dilution and preheating: Take 900 g of 85% phosphoric acid, dilute it with water to a phosphoric acid concentration of 55%, heat it to 50°C, and determine the molar weight of phosphoric acid.

[0069] Urea reaction: According to the molar ratio of phosphoric acid to urea of ​​1:1.2, weigh 505 g of urea, add the diluted phosphoric acid solution, stir until dissolved, maintain the reaction solution temperature at 50°C, and react for 2 hours.

[0070] Addition of crystal inhibitor: sodium lignin sulfonate was added as a crystal inhibitor at a concentration of 0.6% of the total mass of the reaction solution, and the mixture was stirred at a constant temperature of 50° C. for 2 hours.

[0071] Addition of surfactant: add 0.25% of the total mass of the obtained solution of alkylphenol polyoxyethylene ether as a surfactant, and stir at a constant temperature of 50° C. for 2 hours.

[0072] Cooling and finished product: After cooling to room temperature, a homogeneous clear liquid with high concentration of urea phosphate was successfully obtained.

[0073] Specific experimental verification

[0074] 1. Experimental Purpose

[0075] The feasibility of the preparation method of high-concentration liquid urea phosphate in Examples 2 to 4 was verified, and the obtained products were tested to see whether they met the expected indicators.

[0076] 2. Experimental Materials and Instruments

[0077] (1) Experimental materials

[0078] 85% concentration phosphoric acid

[0079] urea

[0080] Sodium polyacrylate, polyaspartic acid, sodium lignin sulfonate

[0081] Fatty alcohol polyoxyethylene ether, sodium dodecylbenzene sulfonate, alkylphenol polyoxyethylene ether

[0082] Deionized water

[0083] (2) Experimental instruments

[0084] electronic balance

[0085] Constant temperature water bath

[0086] magnetic stirrer

[0087] Beakers, measuring cylinders, glass rods and other glassware

[0088] pH meter

[0089] hydrometer

[0090] Kjeldahl nitrogen analyzer

[0091] Spectrophotometer

[0092] 3. Experimental steps

[0093] (1) Experimental preparation

[0094] According to the recipes of Example 2 to Example 4, the amount of each raw material was accurately calculated and weighed.

[0095] Check whether the experimental instruments are operating normally and calibrate the constant temperature water bath, pH meter, etc.

[0096] (2) Verification of the embodiment

[0097] Example 2 Verification

[0098] Phosphoric acid dilution and preheating: Add 1000g of 85% phosphoric acid to an appropriate amount of deionized water and dilute to 60% concentration in a beaker. Transfer to a constant temperature water bath and heat to 55°C. Record the relevant data.

[0099] Urea reaction: 458 g of urea was slowly added to the above phosphoric acid solution. The magnetic stirrer was turned on and the reaction was maintained at 55°C for 1.5 hours. The dissolution of urea was observed and recorded.

[0100] Addition of crystal inhibitor: sodium polyacrylate at a concentration of 0.5% by weight of the total reaction solution, and continue stirring at a constant temperature of 55° C. for 1.5 hours.

[0101] Surfactant addition: add 0.2% of the total mass of the obtained solution of fatty alcohol polyoxyethylene ether, and stir at a constant temperature of 55° C. for 1.5 hours.

[0102] Cooling and finishing: The reaction solution was cooled to room temperature, transferred to a clean container, and marked as "Product of Example 2".

[0103] Example 3 Verification

[0104] According to the steps of Example 3, phosphoric acid dilution and preheating (1200 g of 85% phosphoric acid was diluted to a concentration of 70% and heated to 60° C.), urea reaction (515 g of urea was added and the reaction was carried out at 60° C. for 1 hour), a crystal inhibitor was added (0.4% polyaspartic acid by weight of the total reaction solution was added and stirred at 60° C. for 1 hour), a surfactant was added (0.15% sodium dodecylbenzene sulfonate by weight of the total solution was added and stirred at 60° C. for 1 hour), and a cooling step was carried out in sequence to obtain a product marked as “Example 3 Product”.

[0105] Example 4 Verification

[0106] According to the process of Example 4, the following steps were completed: phosphoric acid dilution and preheating (900 g of 85% phosphoric acid was diluted to a concentration of 55% and heated to 50° C.), urea reaction (505 g of urea was added and the reaction was carried out at 50° C. for 2 hours), crystal inhibitor addition (0.6% sodium lignin sulfonate by weight of the total reaction solution was added and stirred at 50° C. for 2 hours), surfactant addition (0.25% alkylphenol polyoxyethylene ether by weight of the total solution was added and stirred at 50° C. for 2 hours), and cooling to obtain a product labeled “Example 4 Product”.

[0107] (3) Product testing

[0108] Total nitrogen content detection: The total nitrogen content of the products of the three examples was determined using a Kjeldahl nitrogen analyzer according to the standard detection method.

[0109] Detection of available phosphorus content: Use a spectrophotometer to detect the available phosphorus content in the product according to relevant standard procedures.

[0110] Specific gravity test: Use a hydrometer to measure the specific gravity of the product and record the data.

[0111] pH value detection: Use a calibrated pH meter to measure the pH value of the product.

[0112] Crystallization observation: The three examples of the product were placed in a room temperature (about 25 ° C) environment, and the presence of crystallization was observed regularly and recorded.

[0113] 4. Data Recording and Analysis

[0114] Data recording: Record the test data of each example product in the following table.

[0115]

[0116]

[0117] Data analysis: Total nitrogen content: The total nitrogen content of the products of the three embodiments is all within the set range of 8%-14%, among which the total nitrogen content of the product of Example 3 is the highest, reaching 12.8%, indicating that within a certain urea ratio range, different raw material ratios can effectively regulate the nitrogen content of the product, and all meet the expectations of the invention.

[0118] Available phosphorus content: The available phosphorus content of the products in each embodiment is in the range of 22%-38%. The available phosphorus content of the product in Example 3 is the highest, which is 35.8%. This shows that the preparation method can stably control the phosphorus content of the product and meet the index requirements of high-concentration liquid urea phosphate for available phosphorus.

[0119] Specific gravity: The specific gravity of the products in the three examples are 1.45 g / ml, 1.48 g / ml and 1.42 g / ml, respectively, which are all within the standard range of 1.4-1.6 g / ml. This proves that the preparation process can give the products a suitable density and ensure the stability of product quality.

[0120] pH value: The pH value of the product is less than or equal to 3, which is in line with the invention setting, reflecting that the product has a stable acidic environment and meets the actual application needs.

[0121] Crystallization: After 1 week and 1 month of observation at room temperature, no crystallization occurred in the three examples, which verified the effectiveness of adding crystal inhibitors and surfactants in inhibiting the crystallization of urea phosphate and ensuring the stability of the product during storage.

[0122] The present invention is provided as an example, not as a limitation of the embodiments. Those skilled in the art will appreciate that other variations or modifications may be made based on the above description. It is not necessary and impossible to enumerate all embodiments here, and obvious variations or modifications derived therefrom remain within the scope of protection of the present invention.

Claims

1. A method for producing high-concentration liquid urea phosphate, characterized in that: The following steps are involved: Step 1: dilute 85% phosphoric acid with water to a 50%-75% phosphoric acid solution, then heat to 50°C-60°C to obtain pure phosphoric acid. Step 2: Add urea at a molar ratio of 1:1-1.2 to phosphoric acid until completely dissolved, and maintain the reaction temperature at 50°C-60°C for 1-2 hours; Step 3: Add 0.3%-0.8% of the total mass of the reaction solution to the crystal inhibitor and stir at a constant temperature for 1-2 hours; Step 4: Add 0.1%-0.3% of the total mass of the obtained solution as a surfactant and stir at a constant temperature for 1-2 hours; Step 5: Cool the solution to room temperature to obtain a homogeneous clear liquid urea phosphate.

2. The method for producing a high-concentration liquid urea phosphate according to claim 1, wherein: The crystal inhibitor is one or more combinations of sodium polyacrylate, polyaspartic acid, and sodium lignin sulfonate.

3. The method for producing a high-concentration liquid urea phosphate according to claim 1, wherein: The surfactant is one or more combinations of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and sodium dodecylbenzene sulfonate.

4. The method for producing a high-concentration liquid urea phosphate according to claim 1, wherein: The concentration of phosphoric acid after dilution in step 1 is 60%-70%.

5. The method for producing a high-concentration liquid urea phosphate according to claim 1, wherein: In step 2, the molar ratio of urea to phosphoric acid is 1:1.05-1.

15.

6. The method for producing a high-concentration liquid urea phosphate according to claim 1, wherein: The amount of the crystal inhibitor added in step 3 is 0.4%-0.6% of the total mass of the reaction solution.

7. The method for producing high-concentration liquid urea phosphate according to claim 1, wherein: The amount of surfactant added in step 4 is 0.15%-0.25% of the total mass of the obtained solution.

8. A high-concentration liquid urea phosphate, characterized in that: The high-concentration liquid urea phosphate is prepared by the manufacturing method according to any one of claims 1 to 7, wherein the high-concentration liquid urea phosphate contains 8%-14% total nitrogen, 22%-38% available phosphorus, a specific gravity of 1.4-1.6 g / ml, a pH ≤ 3, and is a homogeneous clear liquid.

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