Production method of instant puffed monopotassium phosphate

Abstract

The invention belongs to the technical field of chemical product preparation, and provides a production method of instant expanded monopotassium phosphate. The method comprises the following steps: (1) neutralization: neutralizing a potassium hydroxide solution and a phosphoric acid solution to prepare monopotassium phosphate slurry; (2) spray drying: performing sectional drying on the monopotassium phosphate slurry in a vertical high-tower spray drying tower, wherein the vertical high-tower spray drying tower is set into a top high-temperature section, a middle shaping section and a bottom cooling section according to the length ratio from top to bottom, and high-temperature hot air is arranged at an inlet of the top high-temperature section; low-temperature hot air is supplemented into the joint of the middle shaping section and the top high-temperature section; separating, dedusting and recycling at an outlet of the bottom cooling section to obtain monopotassium phosphate primary product particles; and (3) cooling and screening to obtain a finished product. According to the production method, low-energy-consumption and high-efficiency production is realized through sectional type high tower spray drying, and the instant puffed monopotassium phosphate product with high puffing rate and high stability can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of potassium dihydrogen phosphate production, and specifically relates to a production method of instant expanded potassium dihydrogen phosphate. Background Art

[0002] Potassium dihydrogen phosphate (K2HPO4) is a highly efficient phosphorus-potassium compound fertilizer, which is widely used in fields such as agricultural foliar fertilizers, soilless cultivation, and industrial buffers. Potassium dihydrogen phosphate has become the mainstream in the market due to its advantages such as fast dissolution rate, low bulk density, and easy dispersion.

[0003] Currently, the production of industrial expanded potassium dihydrogen phosphate generally adopts the "neutralization method + spray drying" process. The production steps include: neutralizing potassium hydroxide and phosphoric acid to generate a slurry; drying the slurry into particles at a single high temperature (380 - 450 °C) through a pressure atomizer; and screening the dried particles to obtain the finished product.

[0004] The existing process has the following defects: (1) High energy consumption: The single high-temperature drying time is as long as 2 - 3 hours, and the steam consumption reaches 1.8 - 2.2 tons / ton of product; (2) Uneven particle structure: High temperature causes the surface of the particles to melt, with a low internal porosity, and the dissolution time exceeds 120 seconds; (3) Poor stability: It is easy to absorb moisture and caking during storage, and the caking rate reaches 15% - 20%.

[0005] Currently, there is an urgent need for a production method of instant expanded potassium dihydrogen phosphate with low energy consumption and excellent product performance. Summary of the Invention

[0006] Aiming at the above deficiencies in the prior art, the purpose of the present invention is to provide a production method of instant expanded potassium dihydrogen phosphate; this production method realizes low-energy consumption and high-efficiency production through segmented high-tower spray drying, and can obtain an instant expanded potassium dihydrogen phosphate product with a high expansion rate and high stability.

[0007] To achieve the above object, the solution adopted by the present invention is:

[0008] A production method of instant expanded potassium dihydrogen phosphate, comprising: (1) Neutralization: Neutralize a potassium hydroxide solution and a phosphoric acid solution to prepare a potassium dihydrogen phosphate slurry with a solid content of 35% - 40%; (2) Spray drying: Perform segmented drying of the potassium dihydrogen phosphate slurry in a vertical high-tower spray drying tower. The vertical high-tower spray drying tower is set from top to bottom as a top high-temperature section, a middle shaping section, and a bottom cooling section with a length ratio of 5:12:8: Set the hot air temperature at the inlet of the top high-temperature section to be 450 - 500 °C, the hot air flow rate to be 8000 - 10000 m 3 / h, and the potassium dihydrogen phosphate slurry is fed at a rate of 80 - 120 L / h; At the connection between the middle shaping section and the top high-temperature section, the flow rate is 2000 - 3000 m3 Inject low-temperature hot air at 80 - 120°C; separate, dust-remove and recycle at the outlet of the bottom cooling section to obtain the primary potassium dihydrogen phosphate particles; (3) Secondary drying: Feed the primary potassium dihydrogen phosphate particles into a fluidized bed and dry until the moisture content is less than or equal to 0.1%; (4) Cool and screen to obtain the finished product.

[0009] It should be noted that in this application, the injection of low-temperature hot air in the middle shaping section can be achieved by setting an air inlet at the corresponding position of the drying tower to inject hot air, or by other technical means in the prior art that can realize opening an air inlet at a specific position of the drying tower.

[0010] Further, in a preferred embodiment of the present invention, in step (1), a potassium hydroxide solution with a concentration of 48% is added to a phosphoric acid solution with a concentration of 75%, and stirring is carried out at a rotation speed of 80 - 120 r / min and a temperature of 85 - 100°C. At the same time, the pH value is monitored in real time. When pH = 4.0 - 5.0, feeding is stopped, and then heat preservation reaction is carried out for 30 - 40 min to obtain the potassium dihydrogen phosphate slurry.

[0011] Further, in a preferred embodiment of the present invention, in step (1), a surfactant is added to the potassium dihydrogen phosphate slurry.

[0012] Further, in a preferred embodiment of the present invention, in step (1), the surfactant is dissolved in water at 50 - 60°C, the addition amount of the surfactant is 0.1% - 0.5% of the potassium dihydrogen phosphate slurry, and the mixing time is 5 - 10 min.

[0013] Further, in a preferred embodiment of the present invention, the surfactant includes PEG-400 and sodium dodecyl sulfate with a mass ratio of 1:1.

[0014] Further, in a preferred embodiment of the present invention, an antagonist is sprayed on the surface of the primary potassium dihydrogen phosphate particles.

[0015] Further, in a preferred embodiment of the present invention, the preparation of the antagonist includes: mixing magnesium stearate and silicon dioxide according to a mass ratio of 2:1 to obtain a mixed powder, and dispersing the mixed powder in ethanol with a concentration of 95% to make a dispersion with a solid content of 10% - 15%, thus obtaining the antagonist.

[0016] Further, in a preferred embodiment of the present invention, the spraying amount of the antagonist is 0.2 - 0.4% of the mass of the expanded potassium dihydrogen phosphate particles.

[0017] The beneficial effects of a production method of instant expanded potassium dihydrogen phosphate provided by the present invention are:

[0018] (1) The production method of this instant soluble expanded potassium dihydrogen phosphate provided by the present invention adopts a segmented drying process: combining high-temperature rapid drying with low-temperature shaping, which solves the contradiction between the expansion degree and particle strength in the traditional process. Specifically: in the high-temperature section at the top, the inlet temperature is raised to 450 - 500 °C, and the high-temperature air flow is used to instantaneously evaporate the moisture on the surface of the material to form a porous expanded structure; in the shaping section in the middle, low-temperature hot air at 80 - 120 °C is introduced to quickly solidify the surface of the particles and prevent collapse; the above-mentioned segmented drying process can shorten the drying time to 30 - 40 minutes and reduce the energy consumption by more than 30%.

[0019] (2) The production method of this instant soluble expanded potassium dihydrogen phosphate provided by the present invention adds a surfactant to the potassium dihydrogen phosphate slurry: the addition of the surfactant under the specific technical conditions of this application can reduce the surface tension of the potassium dihydrogen phosphate slurry, promote the dispersion of the potassium dihydrogen phosphate slurry, and form a honeycomb-like porous structure, thereby improving the dissolution rate.

[0020] (3) The production method of this instant soluble expanded potassium dihydrogen phosphate provided by the present invention, under the specific technical conditions of this application, in the secondary drying stage, in the fluidized bed, the antagonist of this application is evenly sprayed on the primary potassium dihydrogen phosphate particles to form an anti-caking protective film with a "lubricating layer + barrier layer" composite structure on the surface of the primary potassium dihydrogen phosphate particles to prevent particle agglomeration. The antagonist of this application adopts a compounding method, in which the layered structure of magnesium stearate can reduce the friction between particles, and the porous structure of silicon dioxide can adsorb surface moisture, and the two work together to reduce the contact area between particles by more than 40%.

[0021] (4) The production method of this instant soluble expanded potassium dihydrogen phosphate provided by the present invention prepares the potassium dihydrogen phosphate slurry through a neutralization reaction, adds a surfactant, then adopts a segmented high-tower spray drying, and sprays an anti-caking agent in the secondary drying. This method solves the problems of high energy consumption and product caking in the traditional process, realizes the technical effects of improved dissolution rate and reduced energy consumption, and is suitable for large-scale production of high-value-added instant soluble expanded potassium dihydrogen phosphate products. Specific Embodiments

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0023] The features and properties of the present invention will be further described in detail below in conjunction with the embodiments.

[0024] Example 1

[0025] A production method of instant expanded potassium dihydrogen phosphate, comprising:

[0026] (1) Neutralization: Add a potassium hydroxide solution with a concentration of 48% to a phosphoric acid solution with a concentration of 75%, stir at a rotation speed of 100 r / min and a temperature of 90 °C, and simultaneously monitor the pH value in real time. Stop feeding when the pH = 4.5, and then keep the reaction at a constant temperature for 35 min to obtain a potassium dihydrogen phosphate slurry.

[0027] (2) Spray drying: Segmentally dry the potassium dihydrogen phosphate slurry in a vertical high tower spray drying tower. The vertical high tower spray drying tower is set from top to bottom as a top high temperature section, a middle shaping section and a bottom cooling section with a length ratio of 5:12:8: Set the hot air temperature at the inlet of the top high temperature section to 480 °C, and the hot air flow rate to 9000 m 3 / h, and the potassium dihydrogen phosphate slurry is fed at a rate of 100 L / h; Supplement low-temperature hot air at a flow rate of 2500 m 3 / h at 100 °C at the connection between the middle shaping section and the top high temperature section; Separate dust and recover the primary potassium dihydrogen phosphate particles at the outlet of the bottom cooling section;

[0028] (3) Feed the primary potassium dihydrogen phosphate particles into a fluidized bed and dry until the moisture content is less than or equal to 0.1%.

[0029] (4) Cool and screen to obtain the finished product.

[0030] Example 2

[0031] This example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: (2) Spray drying: Segmentally dry the potassium dihydrogen phosphate slurry in a vertical high tower spray drying tower. The vertical high tower spray drying tower is set from top to bottom as a top high temperature section, a middle shaping section and a bottom cooling section with a length ratio of 5:12:8: Set the hot air temperature at the inlet of the top high temperature section to 450 °C, and the hot air flow rate to 10000 m 3 / h, and the potassium dihydrogen phosphate slurry is fed at a rate of 80 L / h; Supplement low-temperature hot air at a flow rate of 3000 m 3 / h at 80 °C at the connection between the middle shaping section and the top high temperature section; Separate dust and recover the primary potassium dihydrogen phosphate particles at the outlet of the bottom cooling section.

[0032] Example 3

[0033] This embodiment provides a production method of instant expanded potassium dihydrogen phosphate, which is different from that of Embodiment 1 in that: (2) Spray drying: The potassium dihydrogen phosphate slurry is subjected to segmented drying in a vertical high tower spray drying tower. The vertical high tower spray drying tower is set from top to bottom as a top high temperature section, a middle shaping section and a bottom cooling section with a length ratio of 5:12:8. The hot air temperature at the inlet of the top high temperature section is set to 500 °C, and the hot air flow rate is 8000 m 3 / h, and the potassium dihydrogen phosphate slurry is fed at 120 L / h; at the connection between the middle shaping section and the top high temperature section, low-temperature hot air at 120 °C is supplemented at a flow rate of 3000 m 3 / h; the initial potassium dihydrogen phosphate particles are obtained by separating, dust removing and recycling at the outlet of the bottom cooling section.

[0034] Embodiment 4

[0035] This embodiment provides a production method of instant expanded potassium dihydrogen phosphate, which is different from that of Embodiment 1 in that: (1) Neutralization: The potassium hydroxide solution with a concentration of 48% is added to the phosphoric acid solution with a concentration of 75%, and stirring is carried out at a rotation speed of 100 r / min and a temperature of 90 °C. At the same time, the pH value is monitored in real time. When the pH = 4.5, the feeding is stopped, and after heat preservation reaction for 35 min, a potassium dihydrogen phosphate slurry is obtained;

[0036] Then, a surfactant is added to the potassium dihydrogen phosphate slurry; the surfactant includes PEG-400 and sodium dodecyl sulfate with a mass ratio of 1:1; the surfactant is dissolved in water at 55 °C, and the added mass of the surfactant is 0.3% of the potassium dihydrogen phosphate slurry, and the mixing time is 8 min.

[0037] Embodiment 5

[0038] This embodiment provides a production method of instant expanded potassium dihydrogen phosphate, which is different from that of Embodiment 1 in that: (1) Neutralization: The potassium hydroxide solution with a concentration of 48% is added to the phosphoric acid solution with a concentration of 75%, and stirring is carried out at a rotation speed of 80 r / min and a temperature of 100 °C. At the same time, the pH value is monitored in real time. When the pH = 4.0, the feeding is stopped, and after heat preservation reaction for 40 min, a potassium dihydrogen phosphate slurry is obtained;

[0039] Then, a surfactant is added to the potassium dihydrogen phosphate slurry; the surfactant includes PEG-400 and sodium dodecyl sulfate with a mass ratio of 1:1; the surfactant is dissolved in water at 50 °C, and the added mass of the surfactant is 0.1% of the potassium dihydrogen phosphate slurry, and the mixing time is 5 min.

[0040] Embodiment 6

[0041] This embodiment provides a production method of instant expanded potassium dihydrogen phosphate, which is different from that of Embodiment 1 in that: (1) Neutralization: Add a potassium hydroxide solution with a concentration of 48% to a phosphoric acid solution with a concentration of 75%, stir at a rotation speed of 120 r / min and a temperature of 85 °C, and simultaneously monitor the pH value in real time. After stopping the feeding when the pH = 5.0, keep the reaction warm for 30 min to obtain a potassium dihydrogen phosphate slurry.

[0042] Then, add a surfactant to the potassium dihydrogen phosphate slurry; the surfactant includes PEG-400 and sodium dodecyl sulfate with a mass ratio of 1:1; dissolve the surfactant in water at 60 °C, and the added mass of the surfactant is 0.5% of the potassium dihydrogen phosphate slurry, and the mixing time is 10 min.

[0043] Embodiment 7

[0044] This embodiment provides a production method of instant expanded potassium dihydrogen phosphate, which is different from that of Embodiment 1 in that: Step (3) further includes: spraying an antagonist on the surface of the primary potassium dihydrogen phosphate particles in the fluidized bed stage. The preparation of the antagonist includes: mixing magnesium stearate and silica in a mass ratio of 2:1 to obtain a mixed powder, and dispersing the mixed powder in ethanol with a concentration of 95% to make a dispersion with a solid content of 13%, that is, obtained; the spraying amount of the antagonist is 0.3% of the mass of the expanded potassium dihydrogen phosphate particles.

[0045] Embodiment 8

[0046] This embodiment provides a production method of instant expanded potassium dihydrogen phosphate, which is different from that of Embodiment 1 in that: Step (3) further includes: spraying an antagonist on the surface of the primary potassium dihydrogen phosphate particles in the fluidized bed stage. The preparation of the antagonist includes: mixing magnesium stearate and silica in a mass ratio of 2:1 to obtain a mixed powder, and dispersing the mixed powder in ethanol with a concentration of 95% to make a dispersion with a solid content of 10%, that is, obtained; the spraying amount of the antagonist is 0.4% of the mass of the expanded potassium dihydrogen phosphate particles.

[0047] Embodiment 9

[0048] This embodiment provides a production method of instant expanded potassium dihydrogen phosphate, which is different from that of Embodiment 1 in that: Step (3) further includes: spraying an antagonist on the surface of the primary potassium dihydrogen phosphate particles in the fluidized bed stage. The preparation of the antagonist includes: mixing magnesium stearate and silica in a mass ratio of 2:1 to obtain a mixed powder, and dispersing the mixed powder in ethanol with a concentration of 95% to make a dispersion with a solid content of 10%, that is, obtained; the spraying amount of the antagonist is 0.2% of the mass of the expanded potassium dihydrogen phosphate particles.

[0049] Embodiment 10

[0050] A production method of instant expanded potassium dihydrogen phosphate, comprising:

[0051] (1) Neutralization: Add a potassium hydroxide solution with a concentration of 48% to a phosphoric acid solution with a concentration of 75%, stir at a rotation speed of 100 r / min and a temperature of 90 °C, and simultaneously monitor the pH value in real time. Stop feeding when the pH = 4.5, and then keep the reaction at a constant temperature for 35 min to obtain a potassium dihydrogen phosphate slurry.

[0052] Then, add a surfactant to the potassium dihydrogen phosphate slurry; the surfactant includes PEG-400 and sodium dodecyl sulfate with a mass ratio of 1:1; dissolve the surfactant in water at 55 °C, and the added mass of the surfactant is 0.3% of the potassium dihydrogen phosphate slurry, and the mixing time is 8 min.

[0053] (2) Spray drying: Segmentally dry the potassium dihydrogen phosphate slurry in a vertical high tower spray drying tower. The vertical high tower spray drying tower is set from top to bottom as a top high temperature section, a middle shaping section and a bottom cooling section with a length ratio of 5:12:8: Set the hot air temperature at the inlet of the top high temperature section to 480 °C, and the hot air flow rate to 9000 m 3 / h, and the potassium dihydrogen phosphate slurry is fed at a rate of 100 L / h; supplement low-temperature hot air at 100 °C at a flow rate of 2500 m 3 / h at the connection between the middle shaping section and the top high temperature section; separate and collect dust at the outlet of the bottom cooling section to obtain the primary potassium dihydrogen phosphate particles.

[0054] (3) Send the primary potassium dihydrogen phosphate particles into a fluidized bed and dry until the moisture content is less than or equal to 0.1%; spray an antagonist on the surface of the primary potassium dihydrogen phosphate particles at the fluidized bed stage. The preparation of the antagonist includes: mixing magnesium stearate and silicon dioxide in a mass ratio of 2:1 to obtain a mixed powder, and dispersing the mixed powder in ethanol with a concentration of 95% to make a dispersion with a solid content of 13%, that is, obtained; the spraying amount of the antagonist is 0.3% of the mass of the expanded potassium dihydrogen phosphate particles.

[0055] (4) Cool and screen to obtain the finished product.

[0056] Comparative Example 1

[0057] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, comprising:

[0058] (1) Neutralization: Add a potassium hydroxide solution with a concentration of 48% to a phosphoric acid solution with a concentration of 75%, stir at a rotation speed of 100 r / min and a temperature of 90 °C, and simultaneously monitor the pH value in real time. Stop feeding when the pH = 4.5, and then keep the reaction at a constant temperature for 35 min to obtain a potassium dihydrogen phosphate slurry.

[0059] (2) Spray drying: The potassium dihydrogen phosphate slurry is spray-dried in a vertical high tower spray drying tower. The hot air temperature at the inlet of the high-temperature section at the top is set at 380 °C, and the hot air flow rate is 9000 m 3 / h. The potassium dihydrogen phosphate slurry is fed at 100 L / h; at the outlet of the cooling section at the bottom, the potassium dihydrogen phosphate primary product particles are separated, dust-removed and recovered; the potassium dihydrogen phosphate primary product particles are sent to a fluidized bed and dried to a moisture content less than or equal to 0.1%.

[0060] (3) Cooling and screening to obtain the finished product.

[0061] Comparative Example 2

[0062] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: (2) Spray drying: The potassium dihydrogen phosphate slurry is dried in sections in a vertical high tower spray drying tower. The vertical high tower spray drying tower is set from top to bottom as a top high-temperature section, a middle shaping section and a bottom cooling section with a length ratio of 5:12:8: The hot air temperature at the inlet of the top high-temperature section is set at 550 °C, and the hot air flow rate is 7000 m 3 / h. The potassium dihydrogen phosphate slurry is fed at 150 L / h; at the connection between the middle shaping section and the top high-temperature section, low-temperature hot air at 50 °C is supplemented at a flow rate of 4000 m 3 / h; at the outlet of the bottom cooling section, the potassium dihydrogen phosphate primary product particles are separated, dust-removed and recovered.

[0063] Comparative Example 3

[0064] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: (1) Neutralization: A 48% potassium hydroxide solution is added to a 75% phosphoric acid solution, and stirring is carried out at a rotation speed of 100 r / min and a temperature of 90 °C. At the same time, the pH value is monitored in real time. When the pH = 4.5, the feeding is stopped, and after heat preservation reaction for 35 min, a potassium dihydrogen phosphate slurry is obtained;

[0065] Then, a surfactant is added to the potassium dihydrogen phosphate slurry; the surfactant is PEG-400; the surfactant is dissolved in water at 55 °C, and the added mass of the surfactant is 0.3% of the potassium dihydrogen phosphate slurry, and the mixing time is 8 min.

[0066] Comparative Example 4

[0067] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: (1) Neutralization: Add a potassium hydroxide solution with a concentration of 48% to a phosphoric acid solution with a concentration of 75%, stir at a rotation speed of 100 r / min and a temperature of 90 °C, and simultaneously monitor the pH value in real time. After stopping the feeding when pH = 4.5, keep the reaction at a constant temperature for 35 min to obtain a potassium dihydrogen phosphate slurry;

[0068] Then add a surfactant to the potassium dihydrogen phosphate slurry; the surfactant is sodium dodecyl sulfate; dissolve the surfactant in water at 55 °C, and the added mass of the surfactant is 0.3% of the potassium dihydrogen phosphate slurry, and the mixing time is 8 min.

[0069] Comparative Example 5

[0070] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: (1) Neutralization: Add a potassium hydroxide solution with a concentration of 48% to a phosphoric acid solution with a concentration of 75%, stir at a rotation speed of 100 r / min and a temperature of 90 °C, and simultaneously monitor the pH value in real time. After stopping the feeding when pH = 4.5, keep the reaction at a constant temperature for 35 min to obtain a potassium dihydrogen phosphate slurry;

[0071] Then add a surfactant to the potassium dihydrogen phosphate slurry; the surfactant includes PEG-400 and sodium dodecyl sulfate with a mass ratio of 1:1; dissolve the surfactant in water at 65 °C, and the added mass of the surfactant is 0.8% of the potassium dihydrogen phosphate slurry, and the mixing time is 3 min.

[0072] Comparative Example 6

[0073] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: Step (3) further includes: spraying an antagonist on the surface of the primary potassium dihydrogen phosphate particles in the fluidized bed stage. The preparation of the antagonist includes: dispersing magnesium stearate in ethanol with a concentration of 95% to make a dispersion with a solid content of 13%, that is, obtaining; the spraying amount of the antagonist is 0.3% of the mass of the expanded potassium dihydrogen phosphate particles.

[0074] Comparative Example 7

[0075] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: Step (3) further includes: spraying an antagonist on the surface of the primary potassium dihydrogen phosphate particles in the fluidized bed stage. The preparation of the antagonist includes: dispersing silica in ethanol with a concentration of 95% to make a dispersion with a solid content of 13%, that is, obtaining; the spraying amount of the antagonist is 0.3% of the mass of the expanded potassium dihydrogen phosphate particles.

[0076] Comparative Example 8

[0077] This comparative example provides a production method of instant expanded potassium dihydrogen phosphate, which is different from Example 1 in that: step (3) further includes: spraying an antagonist on the surface of the initial potassium dihydrogen phosphate particles in the fluidized bed stage. The preparation of the antagonist includes: mixing magnesium stearate and silicon dioxide in a mass ratio of 2:1 to obtain a mixed powder, and dispersing the mixed powder in ethanol with a concentration of 75% to prepare a dispersion with a solid content of 8%, that is, obtaining it; the spraying amount of the antagonist is 0.6% of the mass of the expanded potassium dihydrogen phosphate particles.

[0078] Experimental Example 1

[0079] Experimental method:

[0080] Respectively test the following performance indicators of the instant expanded potassium dihydrogen phosphate prepared in Examples 1-10 and Comparative Examples 1-8:

[0081] Dissolution time: Optimized in combination with industry practice according to the dissolution conditions of "Determination of water-insoluble matter content" in HG / T 2321-2016 "Potassium dihydrogen phosphate for fertilizer grade". The specific steps are: weigh 10 g of the sample, add 250 mL of deionized water (water temperature 25 ± 2 °C), and dissolve it at a stirring speed of 200 r / min, and record the time for complete dissolution.

[0082] Bulk density: According to GB / T 23771-2009 "Determination of bulk density in inorganic chemical products", measure using the volumetric cylinder method: freely drop the sample into a measuring cylinder with a known volume, and calculate the mass per unit volume.

[0083] Compressive strength: According to GB / T 43091-2023 "Test method for compressive strength of powder", use a single-particle compressive strength tester to apply axial pressure to particles with a particle size of 20-40 mesh, and record the maximum load when the particles are crushed.

[0084] Caking rate: According to the caking test method in GB / T 21698-2008 "Potassium dihydrogen phosphate": Store the sample in an environment of 40 °C and 75% RH for 30 days, and calculate the caking rate by the sieving method (caking mass / total mass × 100%).

[0085] The results are shown in Table 1:

[0086] Table 1

[0087] Group Dissolution time / s <![CDATA[Bulk density / g / cm 3 > Compressive strength / N / granule Caking rate / % Example 1 9s 0.68 g / cm 0.4 N / piece 2.0％ Example 2 10s <![CDATA[0.72g / cm 3 > 0.5 N / piece 2.1％ Example 3 10s <![CDATA[0.71g / cm 3 > 0.5 N / piece 2.2％ Example 4 7s <![CDATA[0.48g / cm 3 > 0.3 N / piece 1.6％ Example 5 8s <![CDATA[0.51g / cm 3 > 0.4 N / piece 1.7％ Example 6 8s <![CDATA[0.50g / cm 3 > 0.4 N / piece 1.8％ Example 7 8s <![CDATA[0.66g / cm 3 > 0.4 N / piece 1.2％ Example 8 9s <![CDATA[0.70g / cm 3 > 0.4 N / piece 1.3％ Example 9 9s <![CDATA[0.71g / cm 3 > 0.4 N / piece 1.4％ Example 10 6s <![CDATA[0.32g / cm 3 > 0.2 N / piece 0.5％ Comparative Example 1 18s <![CDATA[1.11g / cm 3 > 1.5 N / piece 2.8％ Comparative Example 2 13s <![CDATA[0.92g / cm 3 > 0.8 N / piece 2.8％ Comparative Example 3 10s <![CDATA[0.88g / cm 3 > 0.5 N / piece 2.2％ Comparative Example 4 11s <![CDATA[0.76g / cm 3 > 0.5 N / piece 2.1％ Comparative Example 5 9s <![CDATA[0.65g / cm 3 > 0.6 N / piece 2.3％ Comparative Example 6 10s <![CDATA[0.78g / cm 3 > 0.5 N / piece 1.5％ Comparative Example 7 10s <![CDATA[0.83g / cm 3 > 0.6 N / piece 1.5％ Comparative Example 8 11s <![CDATA[0.81g / cm 3 > 0.6 N / piece 1.6％

[0088] As can be seen from the data in Table 1, compared with Comparative Example 1, the instant expanded potassium dihydrogen phosphate prepared by using the production method of instant expanded potassium dihydrogen phosphate provided in Examples 1-10 has significantly decreased dissolution time, bulk density, compressive strength and caking rate. This shows that by using the production method of instant expanded potassium dihydrogen phosphate provided in this application, an instant expanded potassium dihydrogen phosphate product with flash dissolution, high quality and high stability can be obtained.

[0089] In summary, the production method of instant expanded potassium dihydrogen phosphate provided by the present invention is adopted; through segmented high tower spray drying, this production method realizes low energy consumption and high efficiency production, and can obtain an instant expanded potassium dihydrogen phosphate product with a high expansion rate and high stability.

[0090] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A production method of instant expanded potassium dihydrogen phosphate, characterized in that: Including: (1) Neutralization: Neutralize potassium hydroxide solution with phosphoric acid solution to prepare potassium dihydrogen phosphate slurry with a solid content of 35%-40%; (2) Spray drying: The potassium dihydrogen phosphate slurry is subjected to segmented drying in a vertical high tower spray drying tower. The vertical high tower spray drying tower is set from top to bottom as a top high temperature section, a middle shaping section, and a bottom cooling section with a length ratio of 5:12:

8. At the inlet of the top high temperature section, the hot air temperature is set to 450 - 500 °C, and the hot air flow rate is 8000 - 10000 m 3 / h. The potassium dihydrogen phosphate slurry is fed at 80 - 120 L / h. At the connection between the middle shaping section and the top high temperature section, low-temperature hot air at 80 - 120 °C is supplemented at a flow rate of 2000 - 3000 m 3 / h. At the outlet of the bottom cooling section, dust is separated and recovered to obtain the primary potassium dihydrogen phosphate particles; (3) Secondary drying: Feed the preliminary potassium dihydrogen phosphate particles into a fluidized bed and dry until the moisture content is less than or equal to 0.1%; (4) Cool and screen to obtain the finished product.

2. The production method of instant expanded potassium dihydrogen phosphate according to claim 1, characterized in that: In step (1), add the potassium hydroxide solution with a concentration of 48% to the phosphoric acid solution with a concentration of 75%, stir at a rotation speed of 80-120 r / min and a temperature of 85-100 °C, and simultaneously monitor the pH value in real time. Stop feeding when pH = 4.0-5.0, and then keep the reaction at a constant temperature for 30-40 min to obtain the potassium dihydrogen phosphate slurry.

3. The production method of instant expanded potassium dihydrogen phosphate according to claim 1, characterized in that: In step (1), add a surfactant to the potassium dihydrogen phosphate slurry.

4. The production method of instant expanded potassium dihydrogen phosphate according to claim 3, characterized in that: In step (1), dissolve the surfactant in water at 50-60 °C. The addition amount of the surfactant is 0.1%-0.5% of the potassium dihydrogen phosphate slurry, and the mixing time is 5-10 min.

5. The production method of instant expanded potassium dihydrogen phosphate according to claim 4, characterized in that: The surfactant includes PEG-400 and sodium dodecyl sulfate with a mass ratio of 1:

1.

6. The production method of instant expanded potassium dihydrogen phosphate according to claim 1, characterized in that: In step (3), spray an antagonist on the surface of the preliminary potassium dihydrogen phosphate particles.

7. The production method of instant expanded potassium dihydrogen phosphate according to claim 6, characterized in that: The preparation of the antagonist includes: Mix magnesium stearate and silica in a mass ratio of 2:1 to obtain a mixed powder, and disperse the mixed powder in ethanol with a concentration of 95% to make a dispersion with a solid content of 10%-15%, that is, obtain it.

8. The production method of instant expanded potassium dihydrogen phosphate according to claim 7, characterized in that: The spraying amount of the antagonist is 0.2-0.4% of the mass of the expanded potassium dihydrogen phosphate particles.