Process for producing a granular anti-hygroscopic dipotassium hydrogen phosphate

Abstract

The present application relates to a kind of production processes of granular anti-hygroscopic dibasic potassium phosphate, comprising the following steps: neutralization, polymerization furnace one-step drying, cooling, screening.Potassium hydrogen phosphate neutralization slurry is obtained by mixing phosphoric acid, water and alkali after heating reaction, control pH 8.8-8.9, specific gravity 1.5-1.6g / ml;The neutralization slurry is transported to polymerization furnace, flow 2.0-2.5 m³ / h, high-pressure pump pressure 4.5-5.5MPa, furnace head temperature is 150-170℃, polymerization furnace tail temperature is 125-135℃, in polymerization furnace heating time 25-35 min, after cooling, screening to get granular anti-hygroscopic dibasic potassium phosphate product.The present application makes dibasic potassium phosphate content, moisture up to standard, can form specific uniform small particles, product density is improved, reduces the hygroscopicity of anti-hygroscopic dibasic potassium phosphate.The method is simple, can continuous production to improve yield;Significantly reduce the load of dust collector bag, more efficient environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of dipotassium hydrogen phosphate technology related to phosphorus compounds, and specifically relates to a production process for granular, moisture-resistant dipotassium hydrogen phosphate. Background Technology

[0002] Dipotassium hydrogen phosphate is a commonly used food additive. In the food industry, it is used as a water-retaining agent, leavening agent, acidity regulator, dairy improver, and in coffee creamer to adjust acidity, enhance sweetness, and stabilize foam. It can also be used as a bacterial culture medium. Dipotassium hydrogen phosphate is usually a powder product, which is highly hygroscopic and easily dissolves, causing the product to clump and become sticky within its shelf life, inconveniencing customers. Developing a low-hygroscopic anhydrous dipotassium hydrogen phosphate product can meet the widespread market demand.

[0003] The main method used in the industry to produce anhydrous dipotassium hydrogen phosphate is spray drying. While spray drying allows for continuous production, it also has some drawbacks: First, the resulting powder is very light and fine, with about 25-30% of the fine powder being removed by the bag filter, affecting output. Furthermore, the removed potassium salts adhere to the filter bags, severely corroding them and shortening their lifespan. Second, the fine powder is highly susceptible to moisture absorption and clumping. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a production process for granular, moisture-resistant dipotassium hydrogen phosphate. Granular anhydrous dipotassium hydrogen phosphate is produced using a one-step heating method in a polymerization furnace. The neutralization reaction precisely controls the pH and specific gravity to obtain a slurry, which is then pumped into the polymerization furnace for direct combustion heating and drying via a high-pressure pump. Through a specific feeding system, the feed flow rate, pressure, discharge orifice diameter, the position of the discharge port relative to the combustion flame, heating temperature, and time are adjusted to ensure the dipotassium hydrogen phosphate slurry is fully heated, completely removing moisture without initiating a polymerization reaction that produces potassium pyrophosphate. The resulting anhydrous dipotassium hydrogen phosphate is granular, and the product's hygroscopicity is significantly reduced. This process is simpler than the crystallization method and facilitates continuous production; compared to the spray method, it increases output, reduces the load on baghouse dust collectors, protects the filter bags, and is more energy-efficient and environmentally friendly.

[0005] The technical solution of this invention is as follows:

[0006] A production process for granular, moisture-resistant dipotassium hydrogen phosphate includes the following steps:

[0007] S1, Neutralization: Phosphoric acid, water and alkali are mixed and heated to carry out a neutralization reaction to obtain dipotassium hydrogen phosphate slurry;

[0008] S2, One-step drying in polymerization furnace: The dipotassium hydrogen phosphate solution is pumped into the polymerization furnace and dried by combustion in the one-step polymerization furnace;

[0009] S3. Cooling, sieving and packaging: After the material flow from the tail end of the polymerization furnace is cooled, it is sieved and then packaged; thus completing the production of granular, moisture-resistant dipotassium hydrogen phosphate.

[0010] Preferably, in step S1, the alkali is potassium carbonate and / or potassium hydroxide; food phosphoric acid, water and alkali are mixed, heated with steam and kept warm, and the neutralization reaction temperature is 90-105℃.

[0011] Preferably, in step S1, the neutralization reaction endpoint is when the pH of the slurry is adjusted to 8.8-8.9 and the specific gravity to 1.5-1.6 g / mL.

[0012] Preferably, in step S2, a high-pressure pump delivers the feed material at a flow rate of 2.0-2.5 m³ / s. 3 / h, high-pressure pump pressure 4.5-5.5MPa.

[0013] Preferably, in step S2, the polymerization furnace head feeding device is equipped with a slurry spray gun and a gas gun, and the output end of the slurry spray gun is equipped with an atomizer.

[0014] It is equipped with a slurry spray gun and a gas gun, and the output end of the slurry spray gun is equipped with an atomizer.

[0015] Preferably, the atomizer is 30-35cm away from the outer flame of the polymerization furnace.

[0016] Preferably, in step S2, the temperature of the polymerization furnace head is 150-170℃, the temperature of the polymerization furnace tail is 125-135℃, and the heating time in the polymerization furnace is 25-35 minutes.

[0017] More preferably, the outside of the polymerization furnace head is covered with insulating cotton material.

[0018] Preferably, the material dried at the tail of the furnace flows into a cooling drum for cooling, and after cooling, it is sieved and packaged.

[0019] Preferably, in step S1, after the neutralization reaction yields dipotassium hydrogen phosphate slurry, sodium percarbonate or hydrogen peroxide is added to the slurry, with the amount added being 1.5-2% of the mass of the dipotassium hydrogen phosphate slurry.

[0020] Preferably, the sodium percarbonate or hydrogen peroxide is added to the potassium dihydrogen phosphate slurry by stirring at a speed of 100-200 r / min for 5-10 min, and then kept warm and allowed to stand for 3-5 min after stirring.

[0021] The granular, moisture-resistant dipotassium hydrogen phosphate obtained by the method has the following characteristics: main content ≥98%; product pH value 9.0-9.2; granular appearance; passes through a standard sieve of 20 mesh completely, residue ≥30% on a 40 mesh sieve, residue ≥50% on a 60 mesh sieve, residue ≥75% on a 100 mesh sieve, and density ≥0.4g / mL.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention precisely controls the parameters of dipotassium hydrogen phosphate slurry; the slurry is sprayed out under specific pressure, flow rate, and orifice size, so that the spray angle and range of the liquid are reasonable to achieve non-sticking to the wall; the liquid is sprayed into the outer flame of the direct-fired flame, so that it is heated fully and evenly, and the content and moisture of the dipotassium hydrogen phosphate product meet the standards; it can also form specific uniform small particles, increasing the product density; and reduce the moisture absorption of the moisture-resistant dipotassium hydrogen phosphate.

[0024] 2. The direct-fired drying process in the polymerization furnace can produce dipotassium hydrogen phosphate at lower temperatures, resulting in greater energy savings. The furnace head is wrapped with insulation cotton to reduce heat loss and temperature fluctuations within the furnace, ensuring better particle morphology and content in the product.

[0025] 3. This method has a simple process, can be continuously produced to increase output, with a daily output of 20t-30t / day; it can also significantly reduce the load on the dust collector bags, protect the bags and reduce waste production, making it more efficient and environmentally friendly. Attached Figure Description

[0026] Figure 1 Schematic diagram of the feeding section of the polymerization furnace head;

[0027] Figure 2 Atomizer structural diagram;

[0028] Figure 3 The prepared samples are shown in the image (Example 1 is on the left, and Comparative Example 5 is on the right).

[0029] Figure 4 The prepared sample was placed in the air for 10 hours and the actual image is shown (the left side is Example 1, and the right side is Comparative Example 5).

[0030] Figure 5 This is an electron microscope image of Example 1;

[0031] Figure 6 This is a detailed electron microscope image of Example 1;

[0032] Figure 7 This is a full electron microscope image of Comparative Example 5;

[0033] Figure 8 This is a detailed electron microscope image of Comparative Example 5;

[0034] Figure 9 The image shows the physical sample of Example 3 (the left side is the initial state after production, and the right side is the state after 10 hours).

[0035] Figure 10 The image shows the actual product of Comparative Example 9 (the left side shows the initial state after production, and the right side shows the state after 10 hours).

[0036] In the figure, there is a slurry spray gun 1, a gas gun 2, an atomizer 3, a mounting base 31, a distributor 32, a main hole 33, a branch hole 34, and a nozzle 35. Detailed Implementation

[0037] The technical solution of the present invention will be described in detail below with reference to the embodiments of the present invention. It should be noted that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the content of the claims. Modifications and equivalent substitutions made by those skilled in the art without creative effort after fully understanding the technical solution of the present invention all fall within the scope of protection of the present invention.

[0038] In the embodiments and comparative examples, the polymerization furnace head feed is equipped with a slurry spray gun 1 and a gas gun 2. An atomizer 3 is installed at the output end of the slurry spray gun 1. The atomizer 3 is equipped with a mounting base 31, and a distributor 32 is coaxially connected to the mounting base 31. A main hole 33 is opened in the center of the distributor 32, and branch holes 34 are evenly arranged around the main hole 33. The atomizer 3 is 30-35cm away from the outer flame of the polymerization furnace. A nozzle 35 is coaxially installed on the mounting base 31.

[0039] The conditions for standing for 10 hours in the examples and comparative examples were: 22°C and 65% humidity.

[0040] Example 1

[0041] S1, Neutralization: Food-grade phosphoric acid (85%), water and potassium carbonate (99.5%) are added to a 500L neutralization pot for reaction. Steam is passed through to maintain the temperature at 100±5℃. The pH of the neutralization solution is adjusted to 8.85 and the specific gravity to 1.55g / mL to obtain dipotassium hydrogen phosphate slurry.

[0042] S2. Direct-fired drying in the polymerization furnace: The neutralized slurry is pumped into the polymerization furnace via a high-pressure pump at a feed flow rate of 2.5 m³ / s. 3 / h, high-pressure pump pressure 5.0 MPa, slurry spray gun nozzle diameter 3.5mm; the distance between the slurry spray gun nozzle and the outer flame of combustion is 35cm, and the furnace head is insulated. The polymerization furnace head temperature is 150-160℃, the polymerization furnace tail temperature is 125-135℃, and the product is removed from the furnace after heating for 30 minutes.

[0043] S3. Cooling, crushing, screening and packaging: The high-temperature material at the tail of the furnace flows into the cooling drum for cooling, and after cooling, it passes through a 20-mesh sieve and is packaged.

[0044] The system operated continuously for 48 hours without any wall buildup inside the furnace, ensuring stable and continuous production; daily capacity reached 28 tons / day. The product's main content was 98.8%, pH 9.05, moisture 0.1%, 33% residue on a 40-mesh sieve, 54% residue on a 60-mesh sieve, and 83% residue on a 100-mesh sieve, with an apparent density of 0.54 g / mL. The product exhibited a spherical granular appearance (e.g., ...). Figure 5-6 As shown), the powder content is small. The product has good flowability and does not clump under static conditions (10 hours at room temperature). Figure 3 The sample on the left in the middle shows that the hygroscopicity is reduced (as shown in the image on the right). Figure 4 (As shown in the sample on the left).

[0045] Example 2

[0046] S1. Neutralization: Food-grade phosphoric acid, water, and alkali (potassium carbonate and / or potassium hydroxide) are added to a neutralization pot for reaction. Steam is passed through to maintain the temperature at 100±5℃. The final pH value of the slurry is controlled to be 8.85 and the specific gravity is 1.60g / mL to obtain dipotassium hydrogen phosphate slurry.

[0047] S2. The neutralized slurry is pumped into the polymerization furnace using a high-pressure pump at a feed flow rate of 2.0 m³ / s. 3 The high-pressure pump operates at 4.5 MPa per hour, with a nozzle diameter of 3.0 mm. The nozzle is positioned approximately 30 cm from the outer flame of the combustion chamber, and the furnace head is insulated. The furnace head temperature is 150-160℃, and the furnace tail temperature is 125-135℃. The product is heated in the furnace for 30 minutes before being removed from the furnace. Granular, moisture-resistant dipotassium hydrogen phosphate is obtained.

[0048] S3. Cooling, crushing, screening and packaging: The high-temperature material at the tail of the furnace flows into the cooling drum for cooling, and after cooling, it passes through a 20-mesh sieve and is packaged.

[0049] The system operated continuously for 48 hours without any wall formation inside the furnace; the production capacity reached 20 tons per day. The main content of the product was 99.3%, pH 9.1, moisture 0.12%, 29% residue on a 40-mesh sieve, 50% residue on a 60-mesh sieve, 80% residue on a 100-mesh sieve, and apparent density 0.52 g / mL. The product has the appearance of small round granules.

[0050] Example 3

[0051] Based on Example 1, the difference is that after the reaction in step S1 is completed, 1.8% (based on the mass of the slurry) of food-grade sodium percarbonate is added to the neutralization pot. The sodium percarbonate is first completely dissolved in deionized water and then slowly added dropwise to the slurry. The stirring speed is controlled at 150 r / min. After stirring for 5 minutes, the mixture is kept warm and allowed to stand for 3 minutes before proceeding to step S2. The rest is the same as in Example 1.

[0052] The system ran continuously for 48 hours without any wall clogging inside the furnace, and the slurry showed no bubble agglomeration issues; the production capacity reached 29 tons / day. The main content of the product was 99.2%, pH 9.15; moisture 0.12%, 33% residue on a 40-mesh sieve, 59% residue on a 60-mesh sieve, 87% residue on a 100-mesh sieve, and apparent density 0.55 g / mL. The product had a spherical granular appearance, consistent with the electron microscopy image characteristics of Example 1, and the particle size distribution uniformity was significantly improved compared to Example 1. It did not clump under static conditions (10 hours of static placement in air at room temperature). Figure 9 The left side shows the initial state after production, and the right side shows the state after 10 hours.

[0053] Sodium percarbonate slowly decomposes in a weakly alkaline slurry at 90-105℃, generating hydrogen peroxide (H2O2) and trace amounts of carbon dioxide (CO2). H2O2 further decomposes to release oxygen and water, effectively oxidizing and removing residual trace impurities in the raw materials, preventing impurities from adsorbing onto the surface of slurry particles and causing uneven atomization in the subsequent process. Oxygen and CO2 form uniform microbubbles, which can significantly improve the dispersibility and flowability of the slurry. After the slurry is transported by a high-pressure pump and atomized by an atomizer, the droplet size difference is greatly reduced, resulting in more sufficient contact with the outer flame of the polymerization furnace and a consistent drying rate, ultimately optimizing the uniformity of the finished product particle size distribution.

[0054] Example 4

[0055] Based on Example 3, 2.0% (by slurry mass) of 30% hydrogen peroxide was used to replace sodium percarbonate, and the remaining process parameters and operating procedures were the same as in Example 3.

[0056] The system operated continuously for 48 hours without any wall-forming within the furnace, and production remained relatively stable. A small amount of bubble aggregation was observed in the slurry, with an average daily capacity of 28.3 tons. The finished product had a main content of 99.1%, a pH of 9.13, and a moisture content of 0.12%. Particle size distribution was as follows: 33% residue on a 40-mesh sieve, 57% residue on a 60-mesh sieve, and 85% residue on a 100-mesh sieve. The apparent density was 0.54 g / mL. The finished product exhibited a spherical granule appearance, consistent with the electron microscopy images of Examples 1 and 3, but with slightly less uniform particle size distribution than sodium percarbonate, and a slightly higher amount of fine powder compared to Example 3. Hydrogen peroxide decomposes in a weakly alkaline slurry at 90-105℃, releasing oxygen and water. The oxidation effect of hydrogen peroxide can remove some trace impurities from the raw materials, achieving a certain impurity removal effect. However, the O2 bubbles generated by the decomposition have poor stability and are prone to slight aggregation, which has a limited effect on improving the dispersibility and flowability of the slurry. Compared with the CO2 bubbles of sodium percarbonate, the uniformity of droplet size after atomization is slightly worse, which in turn affects the degree of optimization of the particle size distribution of the finished product.

[0057] Comparative Example 1

[0058] Based on Example 1, the difference is that in S1, the pH value of the neutralizing solution is adjusted to 8.6, otherwise it is the same as Example 1.

[0059] The obtained dipotassium hydrogen phosphate product had a main content of 94%, which is unqualified.

[0060] Comparative Example 2

[0061] Based on Example 1, the difference lies in S2, where the high-pressure pump pressure is 5.5 MPa and the flow rate is 2.8 m³ / h, otherwise the same as in Example 1. The main content of the product is 95%, and the moisture content is 5%. After the system has been running continuously for 20 hours, furnace wall slagging occurs.

[0062] Comparative Example 3

[0063] Based on Example 1, the difference lies in S2, where the high-pressure pump pressure is 4 MPa and the flow rate is 1.8 m³ / h; otherwise, it is the same as in Example 1. The resulting product has a main content of 97.5%. No furnace wall adhesion occurred after 48 hours of continuous system operation; the production capacity reached 16 t / day. Moisture content was 0.1%, with 20% residue on a 40-mesh sieve, 43% residue on a 60-mesh sieve, and 60% residue on a 100-mesh sieve; the apparent density was 0.4 g / mL. The product contained more fine powder.

[0064] Comparative Example 4

[0065] Based on Example 1, the difference lies in S2, where the polymerization furnace head temperature is 190-200℃ and the polymerization furnace tail temperature is 145-155℃, otherwise the same as in Example 1. The resulting product has a main content of 90.5% and a pyrophosphate content of 9.5%.

[0066] Comparative Example 5: Conventional Spray Drying

[0067] Step S1 is the same, the difference being that step S2 uses a conventional spray drying process (drying conditions: centrifugal spray dryer, inlet air temperature 185℃, outlet air temperature 90℃, atomization pressure 0.8MPa, slurry feed flow rate 1.5m³ / h) to produce powdered, moisture-resistant dipotassium hydrogen phosphate. The product is a fine powder (e.g., ...). Figure 7-8 As shown), density 0.3 g / mL, 2% residue on 40 mesh sieve, 15% residue on 60 mesh sieve, and 41% residue on 100 mesh sieve. Extremely hygroscopic and deliquescent (e.g., ...). Figure 4 As shown on the right (placed in room temperature air for 10 hours)).

[0068] Comparative Example 6

[0069] Based on Example 3, the difference is that 1% sodium percarbonate is added after neutralization in step S1, otherwise it is the same as Example 3.

[0070] The system can operate continuously for 48 hours without wall formation, with a production capacity of 28.2 tons per day.

[0071] The resulting product had a main content of 98.9%, pH 9.08, and moisture content of 0.11%; 33% residue on a 40-mesh sieve, 55% residue on a 60-mesh sieve, and 84% residue on a 100-mesh sieve; and an apparent density of 0.54 g / mL. Due to insufficient sodium percarbonate addition, the amount of H2O2 and CO2 produced by decomposition was limited, resulting in weak oxidation and impurity removal, slurry dispersion, and no significant optimization effect on particle size distribution.

[0072] Comparative Example 7

[0073] Based on Example 3, 2.5% (by mass of slurry) of food-grade sodium percarbonate was added after neutralization, and the dissolution, stirring, and settling parameters were the same as in Example 3.

[0074] After 30 hours of continuous operation, the system experienced slight wall formation inside the furnace, resulting in a decrease in production capacity to 27 tons per day. The product had a main content of 99.0%, pH of 9.12, and moisture content of 0.15%. The residue on a 40-mesh sieve was 31%, on a 60-mesh sieve it was 52%, and on a 100-mesh sieve it was 78%. The apparent density was 0.52 g / mL. Excess sodium percarbonate caused decomposition, generating a large amount of CO2 bubbles. This resulted in uneven atomization of the slurry, leading to wall formation inside the furnace. At the same time, the particles were irregularly formed, with an increased amount of fine powder, poor particle size distribution uniformity, and reduced particle density, resulting in negative effects on both production and product quality.

[0075] Comparative Example 8

[0076] S1. Neutralization: Food-grade phosphoric acid, potassium carbonate and 1.8% (by slurry mass) sodium percarbonate are added to the neutralization pot at the same time, and steam is introduced for reaction. The remaining neutralization parameters (pH, specific gravity, temperature) are the same as in Example 1; everything else is the same as in Example 1.

[0077] Continuous 48-hour cell wall formation without caking, production capacity 28t / day; main content 98.5%, pH 8.75, moisture 0.1%; 40 mesh sieve residue 31%, 60 mesh 50%, 100 mesh 82%; apparent density 0.54g / mL. Sodium percarbonate decomposes prematurely in the strong acid-base neutralization reaction system, resulting in rapid loss of H2O2 and CO2, completely negating its optimizing effects of oxidation, impurity removal, and slurry dispersion; simultaneously, the decomposition product sodium carbonate slightly interferes with the neutralization reaction, leading to slurry pH deviation, decreased main content of the product, and no optimization of particle size distribution.

[0078] Comparative Example 9

[0079] Based on Example 3, the difference is that in step S1, the pH value of the neutralizing solution is adjusted to 8.7; otherwise, it is the same as Example 3.

[0080] The system ran continuously for 48 hours without any wall clogging inside the furnace, and the slurry showed no bubble agglomeration issues; the production capacity reached 28 tons / day. The main content of the product was 97.3%, pH 8.72; moisture 0.11%, 29% residue on a 40-mesh sieve, 55% residue on a 60-mesh sieve, 83% residue on a 100-mesh sieve, and apparent density 0.48 g / mL. The product has a spherical granular appearance. It does not clump under static conditions (10 hours of static standing in air at room temperature). Figure 10 The left side of the image shows the initial state after production, and the right side shows the state after 10 hours. Comparative Example 9 controlled the pH of the neutralized slurry at 8.7, but by adding 1.8% sodium percarbonate and using a polymerization furnace drying process, the resulting product still exhibited good particle morphology, and no clumping occurred after standing at room temperature for 10 hours. Its moisture resistance was better than that of conventional spray-dried products (Comparative Example 5).

[0081] Overall, using the process parameters and feeding and combustion system of this invention, the resulting moisture-resistant dipotassium hydrogen phosphate is granular, and its moisture absorption is significantly reduced.

[0082] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this patent.

Claims

1. A production process for granular, moisture-resistant dipotassium hydrogen phosphate, characterized in that, Includes the following steps: S1. Neutralization: Phosphoric acid, water, and alkali are mixed, with potassium carbonate and / or potassium hydroxide as the alkali; a neutralization reaction is carried out by heating to obtain dipotassium hydrogen phosphate slurry. After obtaining dipotassium hydrogen phosphate slurry by neutralization reaction, sodium percarbonate or hydrogen peroxide is added to the slurry, with the amount added being 1.5-2% of the mass of dipotassium hydrogen phosphate slurry; the sodium percarbonate or hydrogen peroxide is added to dipotassium hydrogen phosphate slurry by stirring, and after stirring, it is kept at 90-105℃ and allowed to stand. S2. One-step drying in the polymerization furnace: The dipotassium hydrogen phosphate solution is pumped into the polymerization furnace. The furnace head temperature is 150-170℃, and the furnace tail temperature is 125-135℃. After combustion drying in the one-step polymerization furnace, the feed is delivered using a high-pressure pump with a slurry flow rate of 2.0-2.5 m³ / h. 3 / h, high-pressure pump pressure 4.5-5.5MPa; S3. Cooling, sieving and packaging: After the material flow from the tail end of the polymerization furnace is cooled, it is sieved and then packaged; thus completing the production of granular, moisture-resistant dipotassium hydrogen phosphate.

2. The production process of granular, moisture-resistant dipotassium hydrogen phosphate according to claim 1, characterized in that, In step S1, food-grade phosphoric acid, water, and alkali are mixed, heated with steam, and kept warm at a neutralization reaction temperature of 90-105℃.

3. The production process of granular, moisture-resistant dipotassium hydrogen phosphate according to claim 1, characterized in that, In step S1, the neutralization reaction endpoint is when the pH of the slurry is adjusted to 8.8-8.9 and the specific gravity to 1.5-1.6 g / mL.

4. The production process of granular, moisture-resistant dipotassium hydrogen phosphate according to claim 1, characterized in that, In step S2 The feeding device of the polymerization furnace head is equipped with a slurry spray gun (1) and a gas gun (2), and the output end of the slurry spray gun (1) is equipped with an atomizer (3).

5. The production process of granular, moisture-resistant dipotassium hydrogen phosphate according to claim 4, characterized in that, In step S2, the atomizer (3) is 30-35cm away from the outer flame of the polymerization furnace.

6. The production process of granular, moisture-resistant dipotassium hydrogen phosphate according to claim 1, characterized in that, In step S2, the polymerization furnace is heated for 25-35 minutes; the outside of the polymerization furnace head is covered with insulation cotton material.

7. The production process of granular, moisture-resistant dipotassium hydrogen phosphate according to claim 1, characterized in that, Sodium percarbonate or hydrogen peroxide is added to potassium dihydrogen phosphate slurry by stirring at a speed of 100-200 r / min for 5-10 min. After stirring, the mixture is kept warm and allowed to stand for 3-5 min.

8. The granular, moisture-resistant dipotassium hydrogen phosphate production process according to any one of claims 1-7, characterized in that, The granular, moisture-resistant dipotassium hydrogen phosphate obtained by the process has the following characteristics: main content ≥98%; product pH value 9.0-9.2; granular appearance; passes through a standard 20-mesh sieve completely, with a residue of ≥30% on a 40-mesh sieve, ≥50% on a 60-mesh sieve, ≥75% on a 100-mesh sieve, and a density ≥0.4g / mL.

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