A process for producing superfine powder potassium dihydrogen phosphate by using corn soaking water

Abstract

The application discloses a process method for producing superfine powder potassium dihydrogen phosphate by using corn soaking water and relates to the technical field of potassium dihydrogen phosphate production. Corn soaking water is subjected to anion exchange resin column, nanofiltration membrane, hydrolysis tank and simulated moving bed chromatographic separation to obtain potassium dihydrogen phosphate solution and inositol solution. The potassium dihydrogen phosphate solution is concentrated by a multi-effect concentrator and a crystallizer to obtain high-concentration potassium dihydrogen phosphate raw material solution. Then, the raw material solution is rapidly cooled under the double actions of vacuum evaporation and refrigerated water to obtain a crystallization material solution. The crystallization material solution is subjected to dehydration in a centrifugal machine. The centrifugal wet product after dehydration is subjected to drying and sieving in a flash evaporation dryer to obtain potassium dihydrogen phosphate products.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of potassium dihydrogen phosphate production, in particular to a process for producing superfine powder potassium dihydrogen phosphate by using corn soaking water. BACKGROUND

[0002] Potassium dihydrogen phosphate is used as a buffer and a culture agent in industry, and as a high-efficiency phosphorus-potassium compound fertilizer in agriculture, which is widely used in various types of economic crops, food, melons and fruits, vegetables, etc., and has many excellent effects such as significant yield increase, quality improvement, anti-lodging, disease and pest resistance, early decline prevention, and the effect of overcoming the nutrient deficiency caused by the root system aging and absorption capacity decline in the later growth period of crops.

[0003] Commercially available potassium dihydrogen phosphate is generally divided into granular potassium dihydrogen phosphate and powder potassium dihydrogen phosphate. Compared with granular potassium dihydrogen phosphate, powder potassium dihydrogen phosphate has a faster dissolution rate and is better absorbed by crops. It is particularly suitable for use as a water-soluble fertilizer for drip irrigation or foliar spraying, and its market price is higher than that of granular potassium dihydrogen phosphate.

[0004] Corn soaking water is a by-product produced in the process of wet production of corn starch, and the phytic acid content is 1-2% w / w. At present, there are reports on the process for recovering phytic acid from corn soaking water, preparing potassium phytate, and then producing inositol and potassium dihydrogen phosphate through hydrolysis, separation, concentration and crystallization. However, the obtained products are mostly granular products, which are limited in use and affect the product sales price. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a process for producing superfine powder potassium dihydrogen phosphate by using corn soaking water, which solves the problems existing in the prior art, and the obtained powder potassium dihydrogen phosphate has small particle size, good solubility and high economic benefit.

[0006] To solve the above technical problems, the technical solution of the present application is as follows:

[0007] A process for producing superfine powder potassium dihydrogen phosphate by using corn soaking water, comprising the following steps:

[0008] A: corn soaking water with a solid content of 10-15% w / w is introduced into an anion exchange resin column at a speed of 2-3 BV / h to adsorb phytic acid, and then a potassium chloride solution with a concentration of 10-15% g / L is used to elute the anion exchange resin column at a speed of 1-2 BV / h to obtain an eluate;

[0009] B: the eluate is concentrated by using a nanofiltration membrane with a molecular weight cut-off of 200-500 Dal to obtain a nanofiltration concentrate and a nanofiltration clear liquid, wherein the main component of the nanofiltration clear liquid is potassium chloride, which is recovered for preparation of a potassium chloride solution;

[0010] C: The nanofiltration concentrated solution enters the hydrolysis tank, and the phytate potassium hydrolysis solution is obtained after hydrolysis;

[0011] D: The phytate potassium hydrolysis solution is separated by simulated moving bed chromatography to obtain a potassium dihydrogen phosphate raw solution, and the potassium dihydrogen phosphate raw solution enters a chelate type cation exchange resin column to obtain a calcium and magnesium ion removed solution;

[0012] E: After removing the calcium and magnesium ions, the solution enters a multi-effect concentrator, and is concentrated under vacuum-0.06-0.09 MPa and at a temperature of 70-90°C to obtain a primary concentrated solution;

[0013] F: The primary concentrated solution is added with activated carbon for decolorization, and after the decolorization is completed, the activated carbon is removed by plate and frame filtration to obtain a decolorized solution;

[0014] G: The decolorized solution enters a crystallizer, and is concentrated under vacuum-0.06-0.09 MPa and at a temperature of 75-95°C to obtain a secondary concentrated solution;

[0015] H: After the concentration is completed, the crystallizer jacket steam is turned off, the jacket is supplied with chilled water, and the vacuum in the crystallizer is maintained at-0.06-0.09 MPa, and rapid cooling is performed under the dual action of vacuum evaporation and chilled water to obtain a crystallization solution;

[0016] I: The crystallization solution enters a centrifuge for dehydration, and after the dehydration, the centrifugal wet product enters a flash drying machine for drying and sieving to obtain a potassium dihydrogen phosphate product.

[0017] Preferably, in step C, the nanofiltration concentrated solution is hydrolyzed at 160-180°C and under a pressure of 0.6-0.8 MPa for 8-12 h in the hydrolysis tank or is hydrolyzed by adding phytase at 60-80°C and under pH 4-6 for 10-15 h in the hydrolysis tank, wherein the amount of phytase is 2-5‰ w / w of the nanofiltration concentrated solution, and the enzyme activity of the phytase is 50-100 thousand units / g.

[0018] Preferably, in step D, the chelate type cation exchange resin column is a potassium type cation exchange resin column containing aminomethyl phosphonic acid group.

[0019] The feeding speed of the potassium dihydrogen phosphate raw solution is 1-2 BV / h, and the feeding amount is 10-20 BV, and the calcium in the obtained calcium and magnesium ion removed solution is ≤20 ppm, and the magnesium is ≤200 ppm.

[0020] Preferably, in step E, the solid content of the primary concentrated solution is 35-45% w / w.

[0021] In step F, the amount of activated carbon is 2-5% w / v of the volume of the primary concentrated solution, and the transmittance of the obtained decolorized solution is ≥85%.

[0022] In step G, the solid content of the secondary concentrated solution is 50-70% w / w.

[0023] The cooling time in step H is 1-2 hours, and the terminal cooling temperature is 25-35 DEG C.

[0024] The stirring speed during the cooling process in step H is 100-150 rpm.

[0025] The moisture content of the centrifuged wet product in step I is ≤7% w / w.

[0026] The inlet air temperature of the flash dryer in step I is 160-180 DEG C, and the outlet air temperature is 70-80 DEG C.

[0027] The sieving equipment is an air flow sieve, and the mesh size is 200-300 mesh.

[0028] The crushing chamber of the flash dryer in step I is in a 48-sided polygonal structure, and the direction of the material is changed after impacting the inner wall, so that the contact probability with the blades is increased, and the crushing effect is improved.

[0029] Due to the adoption of the above technical solutions, the application has the following beneficial effects:

[0030] 1. The heat exchanger of the multi-effect concentrator is a tube or plate type, and when the concentration is too high, crystals are precipitated, which can block the heat exchanger. By performing secondary concentration in the crystallizer, the material liquid in the crystallizer exchanges heat with the steam in the jacket, and evaporates under the condition of boiling, so that the concentration can be increased to a high level. On the one hand, the crystallization yield can be improved, and on the other hand, a large number of crystal nuclei are generated under high concentration, which limits the trend of increasing the size of the crystalline particles.

[0031] 2. The four-effect concentrator uses 0.3 m 3 of steam to evaporate one ton of water, and the crystallizer needs 1.2 m 3 of steam to evaporate one ton of water, so that the combination of the multi-effect concentrator and the crystallizer is more energy-saving, which saves the production cost and also reduces the pressure on the environment.

[0032] 3. The corn soaking water contains divalent metal ions such as calcium and magnesium, and the content of magnesium ions is particularly high. During the recovery of phytic acid, part of the calcium and magnesium metal ions remain in the phytate solution. After the hydrolysis of phytate, phosphate is produced, and because the solubility of calcium and magnesium phosphate is low, scaling of the concentrator is easy to occur during the concentration process, and the tube is seriously blocked. The saturated calcium and magnesium in the material liquid are precipitated during the crystallization and cooling process, which affects the product content and causes the clarity of the product to decrease. Therefore, by using the selective adsorption capacity of the chelating cation exchange resin column, the calcium and magnesium ions in the material liquid can be removed, which can greatly alleviate the above problems.

[0033] 4. The flash dryer can realize further crushing of the material while drying the material through the shearing action of the stirring device in the crushing chamber, and is especially suitable for drying sticky blocky material. Potassium dihydrogen phosphate is sticky and its crystal is brittle. In order to further reduce the average particle size of potassium dihydrogen phosphate and realize the production of superfine potassium dihydrogen phosphate, the commonly used fluidized bed drying is replaced by flash drying to realize drying and crushing integration, and avoid the poor working environment and material loss caused by separate crushing.

[0034] 5. In order to shorten the residence time of the material liquid in the metastable zone, after concentration, the jacket is connected to the refrigerated water to rapidly cool the material liquid, so that the material liquid rapidly enters the unstable zone to form "crystal explosion". In combination with rapid stirring, the potassium dihydrogen phosphate product is maintained in a small particle size range. DETAILED DESCRIPTION

[0035] The application is further described below in combination with examples.

[0036] Example 1

[0037] a. Potassium phytate adsorption and desorption: 80 m 3 of corn soaking water (solid content 15% w / w, phytic acid content 1.5% w / w) is passed through a 10 m 3 long weakly basic anion exchange resin column at a flow rate of 2 BV / h. The saturated resin is washed with 3 BV of water to remove impurities on the surface of the resin, and then a potassium chloride solution is used to elute the adsorbed phytic acid on the resin. The concentration of the potassium chloride solution is 10% (g / L), the amount of the potassium chloride solution is 2.5 BV of the volume of the resin, and the elution speed is 2 BV / h, and 25 m 3 of dilute potassium phytate solution is obtained.

[0038] b. Potassium phytate concentration: the dilute potassium phytate solution obtained in step a is concentrated by using a nanofiltration membrane to obtain 6.0 m 3 of potassium phytate concentrate with a concentration of 23% (g / L). The molecular weight cut-off of the nanofiltration membrane is 500 Dal;

[0039] c. Potassium phytate hydrolysis: the potassium phytate concentrate obtained in step b is put into a hydrolysis kettle, steam is introduced, and the temperature is heated to 160℃ and the pressure is 0.6 MPa. After 12 h of heat preservation and pressure maintenance, the hydrolysis is completed, and 7 m 3 of hydrolysis liquid is obtained.

[0040] d. Chromatographic separation: the hydrolysis liquid obtained in step c is cooled by flash evaporation, and the temperature after flash evaporation is 50℃ (feed temperature 150℃, vacuum-0.09 MPa). After cooling, the material liquid is filtered by a plate and frame filter, and the filtrate is separated by a simulated moving bed chromatograph. The filler of the simulated moving bed chromatograph is a strong acid cation exchange resin, and the mobile phase is purified water. The separation conditions are as follows: the temperature is 50℃, the pressure is 0.1 MPa, the valve switching time is 10 min, and the flow rate of the material liquid is 5 m 3 / h, the flow rate of the mobile phase was 10 m 3 / h. The separated monosodium phosphate solution was 9 m 3 3 ;

[0041] e. First concentration: The separated monosodium phosphate solution in step d was first put into a column containing potassium-type cation exchange resin with phosphor-amino groups, the column bed volume was 4 m 3 , the feeding flow rate was 1 BV / h, the effluent calcium was 15 ppm, and the magnesium was 100 ppm. The effluent was concentrated by a plate four-effect concentrator, the concentration vacuum was -0.06 MPa, and the temperature was 90°C, to obtain a concentrated solution 3.5 m 3 , the solid content was 35% (w / w).

[0042] f. Decolorization filtration: The concentrated solution in step e was added with activated carbon, the amount of activated carbon was 2% (w / v) of the amount of the solution, and the decolorization was performed at 90°C for 1 h, and then the solution was filtered by a candle filter to obtain a decolorized filtrate 3.5 m 3 , the filtrate transmittance was 85%.

[0043] g. Second concentration and cooling crystallization: The decolorized filtrate obtained in step f was put into a crystallization tank, the vacuum and jacket steam of the crystallization tank were opened, and the second concentration was performed, the concentration vacuum was -0.06 MPa, and the temperature was 95°C, and the concentration was performed until the solid content was 70% (w / w). The jacket steam was stopped, the jacket cooling water was opened, the cooling water temperature was 5°C, the vacuum in the crystallization tank was maintained at -0.06 MPa, and the stirring speed was 100 rpm. The temperature was cooled to 35°C, and the cooling time was 2 h.

[0044] h. Centrifugation: After crystallization, the solution was put into a centrifuge, and monosodium phosphate wet product 1040 kg was obtained by centrifugation, and the moisture content of the wet product was 7%.

[0045] i. Drying and packaging: After the monosodium phosphate wet product obtained in step h was subjected to the processes of flash drying (the inlet air temperature was 160°C, and the outlet air temperature was 70°C), sieving, and packaging, monosodium phosphate product 960 kg was obtained, and the mesh size of the airflow sieve was 200 mesh.

[0046] j. Preparation of inositol: The inositol solution separated in step d was first concentrated by a plate four-effect concentrator, the concentration vacuum was -0.07 MPa, and the temperature was 90°C, to obtain a concentrated solution 0.55 m 3 , and the solid content was 50% (w / w). Then, activated carbon was added for decolorization, the amount of activated carbon was 2% (w / v) of the amount of the solution, and the solution was filtered by a candle filter, and then the solution was put into a crystallization tank for cooling crystallization, the cooling rate was 8°C / h, the temperature was cooled to 35°C, and centrifugation was performed, to obtain inositol wet product 220 kg. After the centrifuged wet product was subjected to the processes of fluidized bed drying (the inlet air temperature was 140°C, and the outlet air temperature was 75°C), crushing, and packaging, inositol product was obtained, and the weight was 200 kg.

[0047] Example 2​

[0048] a. Potassium phytate adsorption and desorption: 80 m 3 L of corn steep liquor (solid content 10% w / w, phytic acid content 1.4% w / w) was passed through a 10 m 3 weak base anion exchange resin column at a flow rate of 3 BV / h. The resin saturated with adsorption was washed with 3 BV of water to remove the impurities on the surface of the resin, and then the adsorbed phytic acid on the resin was desorbed with a potassium chloride solution. The concentration of the potassium chloride solution was 15% (g / L), and the amount of the potassium chloride solution was 1.5 BV of the volume of the resin, and the elution rate was 1 BV / h, and 15 m 3 L of dilute potassium phytate solution was obtained.

[0049] b. Potassium phytate concentration: The dilute potassium phytate solution obtained in step a was concentrated by using a nanofiltration membrane, and 7.0 m 3 L of potassium phytate concentrate with a concentration of 20% (g / L) was obtained. The nanofiltration membrane had a molecular weight cut-off of 200 Dal;

[0050] c. Potassium phytate hydrolysis: The potassium phytate concentrate obtained in step b was put into a hydrolysis kettle, steam was introduced, and the temperature was heated to 180°C, the pressure was 0.8 MPa, and after the temperature and pressure were maintained for 8 h, the hydrolysis was completed, and 8 m 3 L of hydrolysis liquid was obtained.

[0051] d. Separation: The hydrolysis liquid obtained in step c was cooled by flash evaporation, and after flash evaporation, the temperature was 60°C (feed temperature 170°C, vacuum-0.07 MPa). After cooling, the liquid was filtered by plate and frame filtration, and the filtrate was separated by simulated moving bed chromatography. The simulated moving bed chromatography filler was a strong acid cation exchange resin, and the mobile phase was purified water. The separation conditions were: temperature 50°C, pressure 0.1 MPa, valve switching time 10 min, liquid flow rate 5 m 3 / h, and mobile phase flow rate 10 m 3 / h. Inositol solution 10.5 m 3 L and potassium dihydrogen phosphate solution 17.5 m 3 L were obtained.

[0052] e. Concentration: The potassium dihydrogen phosphate solution separated in step d was first passed through a potassium type cation exchange resin column containing aminomethyl phosphonic acid group, the column bed volume was 4 m 3 , the feed flow rate was 2 BV / h, the calcium content in the effluent was 20 ppm, and the magnesium content was 200 ppm. The effluent was concentrated by a plate four-effect concentrator, the concentration vacuum was-0.09 MPa, and the temperature was 70°C, and 2.8 m 3 L of concentrated solution was obtained, and the solid content was 45% (w / w).

[0053] f. Decolorization and filtration: The concentrated solution in step e was added with activated carbon, the amount of activated carbon was 5% (w / v) of the amount of the liquid, and the decolorization was carried out at 70°C for 0.5 h. The decolorized filtrate 2.8 m3 , the filtrate transmittance is 95%.

[0054] g. Secondary concentration and cooling crystallization: the decolorized filtrate obtained in step f is put into a crystallization tank, vacuum and jacket steam are opened, secondary concentration is carried out, the concentration vacuum is -0.09 MPa, the temperature is 75°C, the concentration is carried out until the solid content is 50% (w / w). The jacket steam is stopped, the jacket cooling water is opened, the cooling water temperature is 10°C, the vacuum in the crystallization tank is maintained at -0.09 MPa, the stirring speed is 150 rpm. The temperature is cooled to 25°C, the cooling time is 1 h.

[0055] h. Centrifugation: after crystallization, the material liquid enters the centrifuge, and 960 kg of potassium dihydrogen phosphate wet product is obtained by centrifugation, and the moisture content of the wet product is 3%.

[0056] i. Drying and packaging: the potassium dihydrogen phosphate wet product obtained in step h is subjected to flash drying (inlet air temperature 180°C, outlet air temperature 80°C), sieving, packaging and other processes to obtain 925 kg of potassium dihydrogen phosphate product, wherein the screen mesh size of the air flow screen is 300 mesh.

[0057] j. Inositol preparation: the inositol solution separated in step d is first concentrated by a plate four-effect concentrator, the concentration vacuum is -0.09 MPa, the temperature is 75°C, and the obtained concentrated liquid is 0.65 m 3 L, and the solid content is 40% (w / w). Then, activated carbon is added in an amount of 4% (w / v) of the liquid, and the activated carbon is decolorized. After filtration by a candle filter, the solution is cooled and crystallized in a crystallization tank, the cooling rate is 5°C / h, the temperature is cooled to 35°C, and centrifugation is carried out to obtain 220 kg of inositol wet product. After fluidized bed drying (inlet air temperature 140°C, outlet air temperature 75°C), crushing, packaging and other processes, 195 kg of inositol product is obtained.

[0058] Example 3

[0059] a. Potassium phytate adsorption and elution: 80 m 3 L of corn soaking water (solid content 13% w / w, phytic acid content 1.5% w / w) is passed through a 10 m 3 L of weakly basic anion exchange resin column at a flow rate of 2.5 BV / h; the saturated resin is washed with 3 BV of water to remove impurities on the surface of the resin, and then the adsorbed phytic acid on the resin is eluted with a potassium chloride solution; wherein the concentration of the potassium chloride solution is 12% (g / L), the amount of the potassium chloride solution is 2 BV of the volume of the resin, and the elution rate is 1.5 BV / h, to obtain 20 m 3 L of dilute potassium phytate solution.

[0060] b. Potassium phytate concentration: the dilute potassium phytate solution obtained in step a is concentrated by using a nanofiltration membrane to obtain 6.5 m 3 L of potassium phytate concentrated solution with a concentration of 22% (g / L), and the nanofiltration membrane has a molecular weight cut-off of 300 Dal;

[0061] c. Potassium phytate hydrolysis: The concentrated potassium phytate solution obtained in step b is put into a hydrolysis kettle, steam is introduced, and the temperature is raised to 170°C and the pressure is 0.7 MPa. After 10 h of holding, the hydrolysis is completed, and a hydrolysis solution 7.5 m 3 ;

[0062] d. Separation: The hydrolysis solution obtained in step c is cooled by flash evaporation, and the temperature after flash evaporation is 55°C (feed temperature 160°C, vacuum -0.08 MPa). After cooling, the solution is filtered by plate and frame filtration, and the filtrate is separated by simulated moving bed chromatography. The simulated moving bed chromatography uses strong acid cation exchange resin as the filler, and purified water as the mobile phase. The separation conditions are: temperature 50°C, pressure 0.1 MPa, valve switching time 10 min, flow rate of the solution 5 m 3 / h, and flow rate of the mobile phase 10 m 3 / h. The separation obtains an inositol solution 11.5 m 3 and a potassium dihydrogen phosphate solution 18.5 m 3 ;

[0063] e. Concentration: The potassium dihydrogen phosphate solution obtained in step d is first passed through a column containing potassium-type cation exchange resin with an amino group, and the column bed volume is 4 m 3 . The feed flow rate is 1.5 BV / h, and the effluent contains 10 ppm of calcium and 150 ppm of magnesium. The effluent is concentrated by a plate four-effect concentrator under vacuum -0.075 MPa and at a temperature of 80°C, and a concentrated solution 3.2 m 3 with a solid content of 40% (w / w) is obtained.

[0064] f. Decolorization and filtration: The concentrated solution in step e is added with activated carbon in an amount of 3.5% (w / v) of the solution, and decolorized at 80°C for 0.75 h. The solution is filtered by a candle filter, and a decolorized filtrate 3.2 m 3 with a light transmittance of 93% is obtained.

[0065] g. Secondary concentration and cooling crystallization: The decolorized filtrate obtained in step f is put into a crystallization tank, and secondary concentration is performed under vacuum -0.075 MPa and at a temperature of 85°C until the solid content reaches 60% (w / w). The jacket steam is stopped, and the jacket cooling water is turned on. The cooling water temperature is 7.5°C, the vacuum in the crystallization tank is maintained at -0.075 MPa, and the stirring speed is 125 rpm. The temperature is cooled to 30°C in 1.5 h.

[0066] h. Centrifugation: The solution after crystallization is put into a centrifuge, and a wet potassium dihydrogen phosphate product 1060 kg is obtained by centrifugation, and the moisture content of the wet product is 5%.

[0067] i. Drying, packing: The wet product of potassium dihydrogen phosphate obtained in step h is subjected to the processes of flash drying (inlet temperature 170°C, outlet temperature 75°C), sieving, packing, etc. to obtain the product of potassium dihydrogen phosphate 1000 kg, wherein the screen mesh size of the air flow sieve is 250 mesh.

[0068] j. Inositol preparation: The inositol solution separated in step d is first concentrated by a plate four-effect concentrator, the concentration vacuum is -0.08 MPa, and the temperature is 85°C, to obtain a concentrated solution 0.6 m 3 L, and the solid content is 45% w / w. Then, 3% (w / v) of activated carbon is added to the solution to decolorize, and the solution is filtered by a candle filter to enter a crystallization tank for cooling crystallization, the cooling rate is 5°C / h, and the temperature is lowered to 35°C for centrifugation to obtain the wet product of inositol 220 kg. The wet product of inositol is subjected to the processes of fluidized bed drying (inlet temperature 140°C, outlet temperature 75°C), crushing, and packing, etc. to obtain the product of inositol, weight 210 kg.

[0069] Example 4

[0070] a. Potassium phytate adsorption and desorption: 80 m 3 of corn soaking water (solid content 13% w / w, phytate content 1.5% w / w) is passed through a 10 m 3 of weakly basic anion exchange resin column at a flow rate of 2.5 BV / h; the saturated resin is washed with 3 BV of water to remove impurities on the surface of the resin, and then the adsorbed phytate on the resin is desorbed with a potassium chloride solution; wherein the concentration of the potassium chloride solution is 12% (g / L), the amount of the potassium chloride solution is 2 BV of the volume of the resin, and the elution rate is 1.5 BV / h, to obtain 20 m 3 of dilute potassium phytate solution.

[0071] b. Potassium phytate concentration: the dilute potassium phytate solution obtained in step a is concentrated by using a nanofiltration membrane to obtain 6.5 m 3 of potassium phytate concentrate with a concentration of 22% (g / L), and the nanofiltration membrane has a molecular weight cut-off of 300 Dal;

[0072] c. Potassium phytate hydrolysis: the potassium phytate concentrate obtained in step b is put into a hydrolysis kettle, steam is introduced, heated to a temperature of 60°C, 5‰ (w / w) of phytase is added, the activity of the phytase is 50,000 units / g, and the temperature is kept for 10 h until the hydrolysis is completed, to obtain 6.5 m 3 of hydrolysis solution;

[0073] d. Separation: the hydrolysis solution obtained in step c is subjected to plate and frame filtration, and the filtrate is subjected to separation by a simulated moving bed chromatography, the filler of the simulated moving bed chromatography is strongly acidic cation exchange resin, and the mobile phase is purified water; the separation conditions are as follows: the temperature is 50°C, the pressure is 0.1 MPa, the valve switching time is 10 min, the flow rate of the feed solution is 5 m 3 / h, and the flow rate of the mobile phase is 10 m3 / h. The inositol solution 10.5 m 3 3

[0074] e. Concentration: The potassium dihydrogen phosphate solution separated in step d is first passed through a column of potassium type cation exchange resin containing amino-methyl phosphonic groups, with a column bed volume of 4 m 3 , a feed flow rate of 1.5 BV / h, and an effluent of 12 ppm calcium and 160 ppm magnesium. The effluent is concentrated in a plate four-effect concentrator at a concentration vacuum of -0.075 MPa and a temperature of 80°C to obtain a concentrated solution 3.1 m 3 with a solid content of 40% (w / w).

[0075] f. Decolorization and filtration: The concentrated solution in step e is decolorized with activated carbon at a dosage of 3.5% (w / v) of the solution volume at 80°C for 0.75 h, and filtered with a candle filter to obtain a decolorized filtrate 3.1 m 3 with a filtrate transmittance of 92%.

[0076] g. Secondary concentration and cooling crystallization: The decolorized filtrate obtained in step f is passed into a crystallization tank, and a secondary concentration is performed by opening the vacuum and jacket steam of the crystallization tank at a concentration vacuum of -0.075 MPa and a temperature of 85°C until the solid content reaches 60% (w / w). The jacket steam is stopped, the jacket cooling water is opened at a temperature of 7.5°C, the vacuum in the crystallization tank is maintained at -0.075 MPa, and the stirring speed is 125 rpm. The temperature is cooled to 30°C at a cooling rate of 5°C / h.

[0077] h. Centrifugation: The solution after crystallization is passed into a centrifuge to obtain a potassium dihydrogen phosphate wet product 1050 kg with a moisture content of 5.5%.

[0078] i. Drying and packaging: The potassium dihydrogen phosphate wet product obtained in step h is subjected to a flash drying process (inlet air temperature 170°C, outlet air temperature 75°C), sieving, and packaging to obtain a potassium dihydrogen phosphate product 985 kg, wherein the airflow sieve has a mesh size of 250 mesh.

[0079] j. Inositol preparation: The inositol solution separated in step d is first concentrated in a plate four-effect concentrator at a concentration vacuum of -0.08 MPa and a temperature of 85°C to obtain a concentrated solution 0.6 m 3 with a solid content of 45% w / w. Then, the concentrated solution is decolorized with activated carbon at a dosage of 3% (w / v) of the solution volume, filtered with a candle filter, and then cooled and crystallized in a crystallization tank at a cooling rate of 5°C / h to 35°C and centrifuged to obtain an inositol wet product 215 kg. The inositol wet product is subjected to a fluidized bed drying process (inlet air temperature 140°C, outlet air temperature 75°C), crushing, and packaging to obtain an inositol product weighing 208 kg.

[0080] Example 5​​

[0081] a. Phytate adsorption and desorption: 80 m 3 Corn steep liquor (solid content 13% w / w, phytate content 1.5% w / w) was passed through a 10 m 3 Weak base anion exchange resin column; the resin saturated with adsorption was washed with 3 BV of water to remove the impurities on the surface of the resin, and then the adsorbed phytate on the resin was desorbed with a potassium chloride solution; the concentration of the potassium chloride solution was 12% (g / L), the amount of the potassium chloride solution was 2 BV of the volume of the resin, and the elution speed was 1.5 BV / h, and a dilute potassium phytate solution of 20 m 3 .

[0082] b. Phytate potassium concentration: the dilute potassium phytate solution obtained in step a was concentrated by using a nanofiltration membrane to obtain a phytate potassium concentrate of 22% (g / L) of 6.5 m 3 , the molecular weight cut-off of the nanofiltration membrane was 300 Dal;

[0083] c. Phytate potassium hydrolysis: the phytate potassium concentrate obtained in step b was put into a hydrolysis kettle, steam was introduced, heated to a temperature of 60°C, 2‰ (w / w) of phytase was added, the phytase activity was 100,000 units / g, and the hydrolysis was kept for 15 h until the hydrolysis was completed, and a hydrolysis solution of 6.5 m 3 ;

[0084] d. Separation: the hydrolysis solution obtained in step c was filtered by a plate and frame filter, and the filtrate was separated by a simulated moving bed chromatography, the filler of the simulated moving bed chromatography was a strong acid cation exchange resin, and the mobile phase was purified water; the separation conditions were as follows: the temperature was 50°C, the pressure was 0.1 MPa, the valve switching time was 10 min, the flow rate of the feed liquid was 5 m 3 / h, and the flow rate of the mobile phase was 10 m 3 / h. Inositol solution of 10.5 m 3 and potassium dihydrogen phosphate solution of 17.5 m 3 were obtained by separation.

[0085] e. Concentration: the potassium dihydrogen phosphate solution separated in step d was first introduced into a potassium type cation exchange resin column containing an aminomethyl phosphonic group, the column bed volume was 4 m 3 , the feeding flow rate was 1.5 BV / h, the calcium content in the effluent was 15 ppm, and the magnesium content was 180 ppm. The effluent was concentrated by a plate four-effect concentrator, the concentration vacuum was -0.075 MPa, and the temperature was 80°C, and a concentrated solution of 3.1 m 3 was obtained, and the solid content was 40% (w / w).

[0086] f. Decolorization and filtration: the concentrated solution in step e was added with activated carbon, the amount of the activated carbon was 3.5% (w / v) of the amount of the feed liquid, the decolorization was performed at 80°C for 0.75 h, and the decolorized filtrate of 3.1 m 3, the filtrate transmittance is 93%.

[0087] g. Secondary concentration and cooling crystallization: the decolorized filtrate obtained in step f is fed into a crystallization tank, vacuum and jacket steam are opened, secondary concentration is carried out, the concentration vacuum is -0.075 MPa, the temperature is 85°C, the concentration is carried out until the solid content is 60% (w / w). The jacket steam is stopped, the jacket cooling water is opened, the cooling water temperature is 7.5°C, the vacuum in the crystallization tank is maintained at -0.075 MPa, the stirring speed is 125 rpm. The temperature is cooled to 30°C, the cooling time is 1.5 h.

[0088] h. Centrifugation: after crystallization, the material liquid is fed into a centrifuge, and monopotassium phosphate wet product 1050 kg is obtained by centrifugation, and the moisture content of the wet product is 5.0%.

[0089] i. Drying and packaging: the monopotassium phosphate wet product obtained in step h is subjected to flash drying (inlet air temperature 170°C, outlet air temperature 75°C), sieving, packaging and other processes to obtain monopotassium phosphate product 990 kg, wherein the screen mesh size of the air flow sieve is 250 mesh.

[0090] j. Inositol preparation: the inositol solution separated in step d is first concentrated by a plate four-effect concentrator, the concentration vacuum is -0.08 MPa, the temperature is 85°C, and the obtained concentrated liquid 0.6 m 3 L is obtained. Then 3% (w / v) of activated carbon based on the amount of liquid is added to the activated carbon for decolorization, and the solution is filtered by a candle filter and then fed into a crystallization tank for cooling crystallization, the cooling rate is 5°C / h, the temperature is cooled to 35°C, and the inositol wet product 215 kg is obtained by centrifugation. After the wet product is subjected to fluidized bed drying (inlet air temperature 140°C, outlet air temperature 75°C), crushing, packaging and other processes, inositol product with a weight of 200 kg is obtained.

[0091] Comparative Example 1

[0092] The potassium-type cation exchange resin column containing phosphoramidic groups in step e of Example 1 is removed, and other conditions remain unchanged. The weight of the monopotassium phosphate product is 950 kg, and the weight of the inositol product is 202 kg.

[0093] Comparative Example 2

[0094] The potassium-type cation exchange resin column containing phosphoramidic groups in step e of Example 2 is replaced with an equal amount of hydrogen-type chelating cation exchange resin column containing phosphoramidic groups, and other conditions remain unchanged. The weight of the monopotassium phosphate product is 895 kg, and the weight of the inositol product is 195 kg.

[0095] Comparative Example 3

[0096] The secondary concentration process in step g of Example 3 is removed, and other conditions remain unchanged. The weight of the monopotassium phosphate product is 850 kg, and the weight of the inositol product is 205 kg.

[0097] Comparative Example 4

[0098] The cooling water temperature in step g of Example 4 was changed to 30℃, the crystallization tank was changed to normal pressure, the cooling time was 10h, and the other conditions were unchanged. The weight of the potassium dihydrogen phosphate product was 960kg, and the weight of the inositol product was 205kg.

[0099] Comparative Example 5

[0100] The drying equipment in step i of Example 5 was changed to a vibrating fluidized bed dryer (inlet air temperature 170℃, outlet air temperature 75℃), and the other conditions were unchanged. The weight of the potassium dihydrogen phosphate product was 985kg, and the weight of the inositol product was 210kg.

[0101] Result analysis:

[0102] The product data obtained from Examples 1-5 and Comparative Examples 1-5 were analyzed. The detection of potassium dihydrogen phosphate was carried out according to the method of HG / T2321-2016, and the detection results are shown in Table 1:

[0103] Table 1: Detection results of potassium dihydrogen phosphate obtained from Examples 1-5 and Comparative Examples 1-5

[0104]

[0105]

[0106] From the detection results of potassium dihydrogen phosphate in the examples and comparative examples, it can be seen that:

[0107] In Comparative Example 1, the potassium-type cation exchange resin column containing aminomethyl phosphonic acid group in step e of Example 1 was removed, and the residual multivalent metal ions in the feed solution could not be removed, resulting in an increase in water-insoluble substances in the product; the product purity was also reduced.

[0108] In Comparative Example 2, the potassium-type cation exchange resin column containing aminomethyl phosphonic acid group in step e of Example 2 was replaced with an equal amount of hydrogen-type chelating cation exchange resin column containing aminomethyl phosphonic acid group. While removing multivalent metal ions, a part of potassium ions was also adsorbed, resulting in a decrease in the yield of potassium dihydrogen phosphate.

[0109] In Comparative Example 3, the secondary concentration process in step g of Example 3 was removed. Due to the low solid content of the feed solution, the crystallization speed was slow, resulting in a decrease in the crystallization yield of potassium dihydrogen phosphate; the crystal particle size distribution test results showed that the 300 mesh passing rate of the product in Comparative Example 3 was also significantly lower than that in Example 3. This was because the crystalline nucleus was less when the lower concentration feed solution reached supersaturation, and the crystal growth space was large, resulting in an increase in the average particle size of the crystal.

[0110] The cooling water temperature in step g of Example 4 was changed to 30℃, and the crystallization tank was changed to normal pressure, and the cooling time was 10h. Due to the high cooling water temperature and the normal pressure in the tank, the cooling rate of the feed liquid was slowed down, and the temperature of the feed liquid reached 30℃ only after 10h. The long crystallization time not only affects the crystallization efficiency, but also makes the crystal have a long growth time, resulting in a larger average particle size of the crystal and a lower 300 mesh passing rate.

[0111] In Comparative Example 5, the drying equipment in step i of Example 5 was changed to a vibrating fluidized bed dryer (inlet air temperature 170℃, outlet air temperature 75℃). From the particle size test results, compared with the vibrating fluidized bed, the flash drying equipment can further crush the potassium dihydrogen phosphate crystals while drying the potassium dihydrogen phosphate, reducing the average particle size of the crystals. For the production of ultrafine potassium dihydrogen phosphate powder, the flash drying equipment is more suitable.

[0112] The inositol was detected according to the method in the fourth part of the Pharmacopoeia of the People's Republic of China 2020 edition. The detection results of Examples 1-5 and Comparative Examples 1-5 meet the standard requirements.

[0113] It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. Furthermore, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the claims attached hereto.

Claims

1. A process for producing ultrafine powder potassium dihydrogen phosphate using corn steep liquor, characterized by comprising the steps of: The method comprises the following steps: ​ A: corn soaking water with solid content of 10-15% w / w is introduced into an anion exchange resin column at a speed of 2-3 BV / h to adsorb phytic acid, and then a potassium chloride solution with a concentration of 10-15% g / L is used to elute the anion exchange resin column at a speed of 1-2 BV / h to obtain an eluate; B: the eluate is concentrated by using a nanofiltration membrane with a molecular weight cut-off of 200-500 Dal to obtain a nanofiltration concentrate and a nanofiltration clear liquid, wherein the main component of the nanofiltration clear liquid is potassium chloride, and the potassium chloride is recovered for preparation of a potassium chloride solution; C: the nanofiltration concentrate is introduced into a hydrolysis tank, and after hydrolysis, a potassium phytate hydrolysate is obtained; D: the potassium phytate hydrolysate is separated by a simulated moving bed chromatography to obtain a potassium dihydrogen phosphate raw material liquid, and the potassium dihydrogen phosphate raw material liquid is introduced into a chelating cation exchange resin column to obtain a calcium and magnesium ion-removed liquid, wherein the chelating cation exchange resin column is a potassium type cation exchange resin column containing an aminomethyl phosphonic acid group, the feeding speed of the potassium dihydrogen phosphate raw material liquid is 1-2 BV / h, and the feeding amount is 10-20 BV, and the calcium content in the obtained calcium and magnesium ion-removed liquid is ≤20 ppm, and the magnesium content is ≤200 ppm; E: the liquid after removal of calcium and magnesium ions is introduced into a multi-effect concentrator, and concentrated under vacuum at -0.06 to -0.09 MPa and at a temperature of 70-90 ℃ to obtain a primary concentrated liquid; F: the primary concentrated liquid is added with activated carbon for decolorization, and after the decolorization is completed, the activated carbon is removed by plate and frame filtration to obtain a decolorized liquid; G: the decolorized liquid is introduced into a crystallizer, concentrated under vacuum at -0.06 to -0.09 MPa and at a temperature of 75-95 ℃ to obtain a secondary concentrated liquid; H: after the concentration is completed, the jacket steam of the crystallizer is turned off, cold water is introduced into the jacket, and the vacuum in the crystallizer is maintained at -0.06 to -0.09 MPa, and rapid cooling is performed under the double actions of vacuum evaporation and cold water to obtain a crystallization liquid; I: the crystallization liquid is introduced into a centrifuge for dehydration, and after dehydration, the centrifugal wet product is introduced into a flash drying machine for drying and sieving to obtain a potassium dihydrogen phosphate product.

2. The process for producing superfine powder potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step C, the nanofiltration concentrate is hydrolyzed in the hydrolysis tank at 160-180 ℃ and under a pressure of 0.6-0.8 MPa for 8-12 h, or hydrolyzed in the hydrolysis tank at 60-80 ℃ and under a pH of 4-6 for 10-15 h by adding phytase, wherein the amount of phytase is 2-5 ‰ w / w of the nanofiltration concentrate, and the enzyme activity of the phytase is 50-100 thousand units per gram.

3. The process for producing ultrafine powder of potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step E, the solid content of the primary concentrated liquid is 35-45% w / w.

4. The process for producing superfine powder potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step F, the amount of activated carbon is 2-5% w / v of the volume of the primary concentrated liquid, and the transmittance of the decolorized liquid is ≥85%.

5. The process for producing ultrafine powder potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step G, the solid content of the secondary concentrated liquid is 50-70% w / w.

6. The process for producing ultrafine powder potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step H, the cooling time is 1-2 h, and the terminal cooling temperature is 25-35 ℃.

7. The process for producing ultrafine powder potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step H, the stirring speed during the cooling process is 100-150 rpm.

8. The process for producing ultrafine powder potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step I, the moisture content of the centrifugal wet product is ≤7% w / w.

9. The process for producing ultrafine powder potassium dihydrogen phosphate using corn steep liquor according to claim 1, characterized in that: In step I, the inlet air temperature of the flash drying machine is 160-180 ℃, and the outlet air temperature is 70-80 ℃. The sieving equipment is an air flow sieve with a mesh size of 200-300 meshes.

Images