A method for preparing calcium dihydrogen phosphate using calcium phytate

Abstract

The application discloses a method for preparing calcium dihydrogen phosphate by using calcium phytate, and first hydrolyzes the calcium phytate under the condition that the pH is 3-4; insoluble impurities are removed from the obtained hydrolyzate by normal-pressure flash evaporation and hot filtration; the obtained filtrate is cooled by vacuum flash evaporation to make calcium dihydrogen phosphate supersaturated and precipitate; the calcium dihydrogen phosphate wet product is obtained by filtration; and the calcium dihydrogen phosphate finished product is obtained after drying. In the application, calcium dihydrogen phosphate and inositol are obtained by hydrolyzing calcium phytate under the condition that the pH is specific; the calcium dihydrogen phosphate product is separated from the calcium dihydrogen phosphate and inositol by twice flash evaporation and cooling crystallization; and the calcium dihydrogen phosphate product has the advantages of good bioavailability, high product value and good economic benefits, as compared with the tricalcium phosphate product obtained by adding lime water to the calcium phytate hydrolyzate for precipitation in the prior art.

Description

Technical Field

[0001] This invention relates to the field of phytate hydrolysis technology, and in particular to a method for preparing calcium dihydrogen phosphate using phytate. Background Technology

[0002] Inositol, chemically known as cyclohexanehexol, is an essential vitamin required by higher animals. It promotes fat metabolism, lowers blood cholesterol levels, and is used as an anti-fatty liver drug to treat cirrhosis, hepatitis, high cholesterol, excessive fat, and arteriosclerosis. Besides being used directly as a drug (such as inositol tablets, heparin, and liver-soothing tablets), inositol can also be used as a pharmaceutical intermediate to manufacture many drugs, such as nicotinic acid inositol ester, vasopressin, and the anticancer drug paclitaxel.

[0003] Calcium dihydrogen phosphate is an important chemical product. It is widely used as a feed additive for aquatic and livestock animals, primarily providing phosphorus, calcium, and other mineral nutrients to aquatic and juvenile animals. It improves palatability and significantly increases absorption and utilization rates, promoting weight gain and survival rates, and enhancing disease resistance and cold tolerance. In the food industry, it is used as a leavening agent, dough conditioner, buffer, nutritional supplement, emulsifier, and stabilizer, among other quality improvers. Calcium dihydrogen phosphate can also be used as an analytical reagent, in the refractory industry, in wastewater treatment, and as a plastic fixative.

[0004] In existing technologies, inositol production often uses calcium phytate (Fettin) as a raw material. After hydrolyzing calcium phytate to obtain inositol and phosphoric acid, lime is added for neutralization, yielding tricalcium phosphate or calcium hydrogen phosphate as byproducts. For example, document CN110643643B describes a process for preparing inositol using Fettin, which involves adding lime milk to the hydrolysate for neutralization, followed by filtration, concentration, and cooling crystallization to obtain crude inositol. Compared to calcium dihydrogen phosphate, tricalcium phosphate and calcium hydrogen phosphate have poor water solubility and low bioavailability, limiting their use, especially for aquatic animals and young livestock with low gastric acid secretion. Calcium dihydrogen phosphate is the ideal additive for supplementing calcium and phosphorus in these animals.

[0005] In summary, there is an urgent need to establish a process for obtaining calcium dihydrogen phosphate from the hydrolysis of calcium phytate. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a method for preparing calcium dihydrogen phosphate using calcium phytate, which overcomes the technical problems of the prior art, such as adding lime milk / lime water to calcium phytate hydrolysate to precipitate tricalcium phosphate byproduct, which cannot obtain calcium dihydrogen phosphate with a wider range of applications and better properties.

[0007] To achieve the above objectives, the present invention provides a method for preparing calcium dihydrogen phosphate using calcium phytate, comprising the following steps:

[0008] Calcium phytate is hydrolyzed, and the pH of the hydrolysis process is controlled at 3-4 to obtain a hydrolysate containing calcium dihydrogen phosphate and inositol.

[0009] The temperature of the hydrolysate is controlled at 160-170℃. After being cooled to 95-100℃ by flash evaporation under normal pressure, insoluble impurities are filtered while hot to obtain the first filtrate.

[0010] After the first filtrate is cooled to 50-60°C by vacuum flash evaporation, calcium dihydrogen phosphate supersaturates and precipitates out. The filtrate is then filtered to obtain the second filtrate and wet calcium dihydrogen phosphate 1.

[0011] The wet calcium dihydrogen phosphate product 1 is dried to obtain the finished calcium dihydrogen phosphate product.

[0012] This invention provides a method for preparing calcium dihydrogen phosphate from calcium phytate. First, calcium phytate is hydrolyzed at pH 3-4 to obtain a hydrolysate containing calcium dihydrogen phosphate and inositol. The hydrolysate is then subjected to flash evaporation at normal pressure while being cooled to a certain temperature. During this process, insoluble impurities in the hydrolysate can be removed by hot filtration. The filtrate is then subjected to vacuum flash evaporation while being cooled to a certain temperature, causing calcium dihydrogen phosphate to precipitate from the solution due to supersaturation. After filtration and drying, the calcium dihydrogen phosphate product is obtained. Compared to the existing technique of adding lime water / lime milk to the calcium phytate hydrolysate to adjust the pH and precipitate phosphate to obtain tricalcium phosphate as a byproduct, the calcium dihydrogen phosphate product obtained by this invention has the advantages of good bioavailability, high product value, and good economic benefits. It is a more rational and economical method and also provides a new approach and idea for the preparation of calcium dihydrogen phosphate. Detailed Implementation

[0013] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0014] This invention provides a method for preparing calcium dihydrogen phosphate using calcium phytate, comprising the following steps:

[0015] Calcium phytate is hydrolyzed, and the pH of the hydrolysis process is controlled at 3-4 to obtain a hydrolysate containing calcium dihydrogen phosphate and inositol.

[0016] The temperature of the hydrolysate is controlled at 160-170℃. After being cooled to 95-100℃ by flash evaporation under normal pressure, insoluble impurities are filtered while hot to obtain the first filtrate.

[0017] After the first filtrate is cooled to 50-60°C by vacuum flash evaporation, calcium dihydrogen phosphate is supersaturated and precipitated. The filtrate is then filtered to obtain the second filtrate and wet calcium dihydrogen phosphate product 1.

[0018] The wet calcium dihydrogen phosphate product 1 is dried to obtain the finished calcium dihydrogen phosphate product.

[0019] This invention first hydrolyzes calcium phytate, controlling the pH of the hydrolysis process to 3-4 to obtain a hydrolysate containing calcium dihydrogen phosphate and inositol. In this invention, the calcium phytate is preferably pulped before hydrolysis. This invention does not have specific limitations on the equipment and parameters for the pulping process; conventional methods are sufficient. The pH of the calcium phytate hydrolysate is preferably 3-4, more preferably 3.5. The calcium phytate hydrolysis is preferably performed using phytase hydrolysis, with an enzyme activity preferably of 10000-60000 U / g. The hydrolysis temperature is preferably 40-60℃, and the hydrolysis time is preferably 12-18 hours. The hydrolysis of calcium phytate in this invention can refer to the scheme described in document CN110643643B. It is important to understand that the products obtained after hydrolysis of calcium phytate are inositol and calcium salts, and the form of the calcium salts varies depending on the pH of the solution. At a solution pH of 3-4, it is calcium dihydrogen phosphate; at a pH of 5-7, it is mostly calcium monohydrogen phosphate and a small amount of calcium dihydrogen phosphate; at a pH of 8-10, it is mostly tricalcium phosphate and a small amount of calcium monohydrogen phosphate; and at a pH greater than 10, it is mainly tricalcium phosphate. For example, in the prior art, calcium phosphate is obtained by adjusting the pH to alkaline by adding lime water / lime milk; the present invention obtains calcium dihydrogen phosphate by controlling the pH of the hydrolysis process to 3-4.

[0020] After obtaining the hydrolysate, this invention controls the hydrolysate temperature at 160-170℃, performs atmospheric pressure flash evaporation while simultaneously cooling to 95-100℃, and then filters out insoluble impurities while hot to obtain the first filtrate. It should be understood that the purpose of raising the hydrolysate temperature to 160-170℃ before flash evaporation is twofold: firstly, to inactivate enzymes, and secondly, to promote the denaturation of organic impurities such as proteins, producing precipitates. In this invention, the purpose of atmospheric pressure flash evaporation is to remove the solvent from the hydrolysate, reducing the amount of insoluble impurities dissolved. Furthermore, since the flash evaporation process is accompanied by cooling, this invention controls the cooling to 95-100℃, which further reduces the solubility of impurities, causing them to precipitate. This precipitates protein decomposition products, calcium and magnesium salts, and other impurities, which can then be removed by subsequent filtration. In this invention, hot filtration is preferably performed using plate and frame filtration, and the filter cloth pore size is preferably 300-400 mesh. The purpose of hot filtration in this invention is to remove insoluble impurities such as protein decomposition products and calcium and magnesium salts obtained by flash evaporation.

[0021] After obtaining the first filtrate, the present invention subjectes the first filtrate to vacuum flash evaporation while simultaneously cooling it to 50-60°C, causing calcium dihydrogen phosphate to precipitate as a supersaturated product. The filtrate is then filtered to obtain a second filtrate and wet calcium dihydrogen phosphate product 1. In this invention, the vacuum degree of the vacuum flash evaporation is preferably -0.05 MPa to -0.07 MPa. The purpose of vacuum flash evaporation is to remove some of the solvent. Furthermore, since the flash evaporation process is accompanied by cooling, controlling the temperature to 50-60°C further reduces the solubility of calcium dihydrogen phosphate, causing it to precipitate due to supersaturation. In this invention, the filtration is preferably performed using a plate and frame filter, with a filter cloth pore size preferably of 300-400 mesh. The purpose of filtration is to separate the precipitated calcium dihydrogen phosphate to obtain wet calcium dihydrogen phosphate product 1.

[0022] It should be understood that flash evaporation is the phenomenon where a high-pressure saturated liquid enters a relatively low-pressure container, and due to the sudden drop in pressure, the saturated liquid transforms into a portion of the container's saturated vapor and saturated liquid at the container's pressure. The pressure drop is accompanied by a decrease in boiling point. Upon entering the flash tank, the fluid temperature is higher than the boiling point at that pressure, causing the fluid to rapidly boil and vaporize within the flash tank, resulting in two-phase separation. Simultaneously, because boiling absorbs a significant amount of heat, the flash evaporation process is also accompanied by a decrease in liquid temperature. In this invention, the flash evaporation process ends when the target temperature is reached.

[0023] After obtaining wet calcium dihydrogen phosphate 1, the present invention dries the wet calcium dihydrogen phosphate 1 to obtain the finished calcium dihydrogen phosphate product. In the present invention, the drying is preferably carried out by a fluidized bed, wherein the inlet air temperature of the fluidized bed is preferably 120-130°C, the outlet air temperature is preferably 55-65°C, and the drying time is preferably 3-5 minutes.

[0024] Furthermore, after obtaining the second filtrate, the present invention further includes: the second filtrate is subjected to chromatography for separation to obtain the remaining calcium dihydrogen phosphate phase and inositol phase;

[0025] After vacuum concentration, cooling crystallization and centrifugation, the calcium dihydrogen phosphate phase was used to obtain wet calcium dihydrogen phosphate product 2.

[0026] The wet calcium dihydrogen phosphate product 2 and the wet calcium dihydrogen phosphate product 1 are mixed and dried to obtain the finished calcium dihydrogen phosphate product.

[0027] This invention separates the second filtrate into a chromatogram to obtain the remaining calcium dihydrogen phosphate phase and inositol phase. In this invention, the chromatography is preferably a simulated moving bed chromatography; the operating temperature of the chromatography is preferably 55-65℃; the stationary phase is preferably a chelating cation exchange resin; further, the resin skeleton is preferably polystyrene, and the functional groups are preferably aminophosphates; the volume ratio of the stationary phase to the second filtrate in a single feed is (8-10):1; the mobile phase is preferably purified water, and the volume ratio of the mobile phase to the second filtrate is preferably (2-3):1. The simulated moving bed chromatography separation of inositol and phosphate in this invention includes the following three processes: feed top salt / water infusion to remove inositol, circulation partitioning, and water infusion to remove phosphate. The circulation partitioning process utilizes the difference in adsorption strength between inositol and phosphate on the resin to achieve their separation. After separation, inositol and phosphate are enriched on different resin sections, and the separated inositol and calcium dihydrogen phosphate phases are obtained by analysis with water or feed solution.

[0028] After obtaining the calcium dihydrogen phosphate phase, the present invention performs vacuum concentration, cooling crystallization, and centrifugation on the calcium dihydrogen phosphate phase to obtain wet calcium dihydrogen phosphate product 2. In the present invention, the vacuum degree of the vacuum concentration is preferably -0.07 MPa to -0.09 MPa, the temperature is preferably 70-80°C, and the solid content after concentration is 35-50 wt%. The present invention does not have any special limitations on the equipment or method for vacuum concentration; commonly used concentration equipment or methods in the art can be used. In the present invention, the cooling crystallization temperature is preferably 30-35°C, and the time is preferably 8-10 hours. In the present invention, the centrifugation is preferably performed using a centrifuge, and the maximum centrifugation speed is preferably 1050 r / min.

[0029] Furthermore, the present invention also includes mixing the crystallization mother liquor with the filter residue obtained after the aforementioned flash evaporation and filtration to prepare a liquid organic fertilizer for sale.

[0030] After obtaining wet calcium dihydrogen phosphate 2, the present invention mixes and dries the wet calcium dihydrogen phosphate 2 with wet calcium dihydrogen phosphate 1 to obtain the finished calcium dihydrogen phosphate product. In the present invention, the inlet air temperature of the fluidized bed is preferably 120-130℃, the outlet air temperature is preferably 55-65℃, and the drying time is preferably 3-5 min.

[0031] Further, after obtaining the remaining calcium dihydrogen phosphate phase, before the calcium dihydrogen phosphate phase is vacuum concentrated, cooled and crystallized, and centrifuged, the present invention further includes: decolorizing the calcium dihydrogen phosphate phase with activated carbon, and filtering it to obtain the decolorized calcium dihydrogen phosphate phase. In the present invention, the amount of activated carbon is preferably 2-5 g / L, the pore size of the activated carbon is preferably 50-100 nm, and the source of activated carbon is not particularly limited, commercially available products can be used; the decolorization time is preferably 0.5-1 h; the filtration is preferably carried out using a candle filter, and the pore size of the filter cloth is preferably 400-600 mesh; the purpose of the above filtration in the present invention is to separate the decolorized activated carbon to obtain the decolorized calcium dihydrogen phosphate phase.

[0032] After obtaining the inositol phase, the present invention further includes: removing impurities from the inositol phase by ion exchange to obtain an effluent, wherein the conductivity of the effluent is 0-20 μs / cm;

[0033] The effluent is concentrated under vacuum conditions of -0.07MPa to -0.09MPa and temperature of 80-90℃ to obtain a concentrated solution with a solid content of 35-50%.

[0034] The concentrate was crystallized at 25-35℃ for 12-24 hours, and then centrifuged to obtain the inositol product.

[0035] In this invention, the ion exchange is preferably carried out using an ion exchange resin. This invention does not have any special limitations on the type and source of the ion exchange resin, and common ion exchange resins and commercially available products in the art can be used.

[0036] The present invention does not impose any special limitations on the equipment and method for vacuum concentration; conventional vacuum concentration equipment and methods in the art can be used.

[0037] In this invention, centrifugation is preferably carried out using a centrifuge, with a maximum centrifugation speed of 1050 r / min.

[0038] Furthermore, after obtaining a concentrated solution through vacuum concentration, before crystallization, the present invention further includes: adding activated carbon to the concentrated solution for decolorization and filtering to obtain a decolorized concentrated solution. In this invention, the amount of activated carbon is preferably 3-5 g / L, the pore size of the activated carbon is preferably 50-100 nm, and the source of the activated carbon is not particularly limited; commercially available products can be used. The decolorization time is preferably 0.5-1 h. In this invention, the filtration is preferably performed using a candle filter, and the filter cloth pore size is preferably 400-600 mesh. The purpose of the above filtration is to separate the decolorized activated carbon to obtain the decolorized concentrated solution.

[0039] To better illustrate the technical solution of the present invention, the following specific embodiments are also provided. It should be understood that, unless otherwise specified, all raw materials used in the following embodiments are commercially available.

[0040] Example 1

[0041] S1. Adjust the pH of the phytate (calcium phytate) slurry to 3. Add 5‰ phytase (enzyme activity 10000U / g) based on the mass of phytate. After stirring and mixing, react at 40℃ for 15h to obtain a hydrolysate containing 72.5g / L calcium dihydrogen phosphate and 18.5g / L inositol, and 5.8g / L of impurities.

[0042] S2. Take 5000L of the above Fettin hydrolysate and flash evaporate it at 165℃ under normal pressure. After the temperature drops to 98℃, filter it while it is hot (the filter cloth has a pore size of 350 mesh) to obtain 4500L of the first filtrate.

[0043] S3. The first filtrate was subjected to vacuum flash evaporation at a vacuum degree of -0.06MPa. After the temperature dropped to 55℃, it was filtered by plate and frame filtration (the filter cloth pore size is 350 mesh) to obtain 4000L of the second filtrate and 360kg of wet calcium dihydrogen phosphate 1.

[0044] S4. Add the wet calcium dihydrogen phosphate 1 obtained in S2 to a fluidized bed (inlet air temperature is 125℃, outlet air temperature is 60℃) and dry for 4 minutes to obtain 215.5 kg of finished calcium dihydrogen phosphate.

[0045] Tests showed that the finished product of calcium dihydrogen phosphate had a purity of 98.8% and a yield of 58.7%.

[0046] Example 2

[0047] S1. Adjust the pH of the phytate (calcium phytate) slurry to 4. Add 5‰ phytase (enzyme activity 30000U / g) based on the mass of phytate. After stirring and mixing, react at 50℃ for 12h to obtain a hydrolysate containing 62.1g / L of calcium dihydrogen phosphate and 15.9g / L of inositol, and 6.6g / L of impurities.

[0048] S2. Take 5000L of the above Fetin hydrolysate and perform normal pressure flash evaporation at a temperature of 170℃. After the temperature drops to 95℃, filter it while it is hot (the filter cloth has a pore size of 300 mesh) to obtain 4400L of the first filtrate.

[0049] S3. The first filtrate was subjected to vacuum flash evaporation at a vacuum degree of -0.05MPa. After the temperature dropped to 50℃, it was filtered by plate and frame filtration (the filter cloth pore size is 400 mesh) to obtain 3900L of the second filtrate and 300kg of wet calcium dihydrogen phosphate 1.

[0050] S4. The second filtrate is introduced into a simulated moving bed chromatograph (the chromatographic operating temperature is 55℃, the stationary phase is 1000L of chelating cation exchange resin, and the mobile phase is 11000L of purified water) to separate 10000L of the remaining calcium dihydrogen phosphate phase and 4900L of the inositol phase.

[0051] S5. The remaining calcium dihydrogen phosphate phase was concentrated under vacuum at -0.07 MPa and 80°C until the solid content was 50 wt%. The concentrate was then crystallized at 35°C for 8 hours. The crystallized solution was then added to a centrifuge and centrifuged at a maximum speed of 1050 r / min to obtain 215 kg of wet calcium dihydrogen phosphate product 2.

[0052] S6. Mix the wet calcium dihydrogen phosphate 1 obtained in S2 and the wet calcium dihydrogen phosphate 2 obtained in S4, and add them to a fluidized bed (inlet air temperature is 120℃, outlet air temperature is 55℃) and dry for 5 minutes to obtain 290kg of finished calcium dihydrogen phosphate.

[0053] Tests showed that the finished product of calcium dihydrogen phosphate had a purity of 97.4% and a yield of 91.0%.

[0054] Example 3

[0055] S1. Adjust the pH of the phytate (calcium phytate) slurry to 3.5. Add 5‰ phytase (enzyme activity 60000U / g) based on the mass of phytate. After stirring and mixing, react at 60℃ for 18h to obtain a hydrolysate containing 68.6g / L of calcium dihydrogen phosphate and 17.6g / L of inositol, and 5.2g / L of impurities.

[0056] S2. Take 5000L of the above Fettin hydrolysate and perform normal pressure flash evaporation at a temperature of 165℃. After the temperature drops to 98℃, filter it while it is hot (the filter cloth has a pore size of 350 mesh) to obtain 4500L of the first filtrate.

[0057] S3. The first filtrate was subjected to vacuum flash evaporation at a vacuum degree of -0.06MPa. After the temperature dropped to 55℃, it was filtered by plate and frame filtration (the filter cloth pore size is 350 mesh) to obtain 4000L of the second filtrate and 360kg of wet calcium dihydrogen phosphate 1.

[0058] S4. The second filtrate is introduced into a simulated moving bed chromatograph (the chromatographic operating temperature is 60℃, the stationary phase is 1000L of chelating cation exchange resin, and the mobile phase is 10000L of purified water) to separate the remaining 9500L of calcium dihydrogen phosphate phase and 4500L of inositol phase.

[0059] S5. Add 19 kg of activated carbon (50 nm pore size) to the remaining calcium dihydrogen phosphate phase for decolorization for 1 h, and then filter it through a candle filter (500 mesh filter cloth) to obtain 9500 L of decolorized calcium dihydrogen phosphate phase.

[0060] S6. The decolorized calcium dihydrogen phosphate phase was vacuum concentrated to a solid content of 40wt% under a vacuum of -0.08MPa and 75℃. The concentrated solution was then crystallized at 32℃ for 9h. The crystallized solution was then added to a centrifuge and centrifuged at a maximum speed of 1050r / min to obtain 218kg of wet calcium dihydrogen phosphate product 2.

[0061] S7. Mix the wet calcium dihydrogen phosphate 1 obtained in S2 and the wet calcium dihydrogen phosphate 2 obtained in S5, and add them to a fluidized bed (inlet air temperature is 125℃, outlet air temperature is 60℃) and dry for 4 minutes to obtain 328 kg of finished calcium dihydrogen phosphate.

[0062] Tests showed that the finished product of calcium dihydrogen phosphate had a purity of 98.8% and a yield of 94.3%.

[0063] Example 4

[0064] S1. Adjust the pH of the phytate (calcium phytate) slurry to 4. Add 5‰ phytase (enzyme activity 30000U / g) based on the mass of phytate. After stirring and mixing, react at 50℃ for 12h to obtain a hydrolysate containing 63.4g / L of calcium dihydrogen phosphate and 16.2g / L of inositol, and 6.8g / L of impurities.

[0065] S2. Take 5000L of the above Fetin hydrolysate and perform normal pressure flash evaporation at a temperature of 170℃. After the temperature drops to 95℃, filter it while it is hot (the filter cloth has a pore size of 300 mesh) to obtain 4400L of the first filtrate.

[0066] S3. The first filtrate was subjected to vacuum flash evaporation at a vacuum degree of -0.05MPa. After the temperature dropped to 50℃, it was filtered by plate and frame filtration (the filter cloth pore size is 400 mesh) to obtain 3900L of the second filtrate and 300kg of wet calcium dihydrogen phosphate 1.

[0067] S4. The second filtrate is introduced into a simulated moving bed chromatograph (the chromatographic operating temperature is 55℃, the stationary phase is 1000L of chelating cation exchange resin, and the mobile phase is 11000L of purified water) to separate 10000L of the remaining calcium dihydrogen phosphate phase and 4900L of the inositol phase.

[0068] S5. Add 30 kg of activated carbon (pore size 80 nm) to the remaining calcium dihydrogen phosphate phase for decolorization for 0.5 h, and then filter through a candle filter (filter cloth pore size 600 mesh) to obtain 10000 L of decolorized calcium dihydrogen phosphate phase.

[0069] S6. The decolorized calcium dihydrogen phosphate phase was vacuum concentrated to a solid content of 50wt% under a vacuum of -0.07MPa and 80℃. The concentrated solution was then crystallized at 35℃ for 8h. The crystallized solution was then added to a centrifuge and centrifuged at a maximum speed of 1050r / min to obtain 220kg of wet calcium dihydrogen phosphate product 2.

[0070] S7. Mix the wet calcium dihydrogen phosphate 1 obtained in S2 and the wet calcium dihydrogen phosphate 2 obtained in S5, and add them to a fluidized bed (inlet air temperature is 120℃, outlet air temperature is 55℃) and dry for 5 minutes to obtain 295kg of finished calcium dihydrogen phosphate.

[0071] Tests showed that the finished product of calcium dihydrogen phosphate had a purity of 98.3% and a yield of 91.4%.

[0072] Example 5

[0073] S1. Adjust the pH of the phytate (calcium phytate) slurry to 3.5. Add 5‰ phytase (enzyme activity 60000U / g) based on the mass of phytate. After stirring and mixing, react at 60℃ for 18h to obtain a hydrolysate containing 71.6g / L of calcium dihydrogen phosphate and 18.4g / L of inositol, and 5.2g / L of impurities.

[0074] S2. Take 5000L of the above Fetin hydrolysate and perform normal pressure flash evaporation at a temperature of 160℃. After the temperature drops to 100℃, filter it while it is hot (the filter cloth has a pore size of 400 mesh) to obtain 4600L of the first filtrate.

[0075] S3. The first filtrate was subjected to vacuum flash evaporation at a vacuum degree of -0.07MPa. After the temperature dropped to 60℃, it was filtered by plate and frame filtration (the filter cloth pore size is 300 mesh) to obtain 4100L of the second filtrate and 313kg of wet calcium dihydrogen phosphate 1.

[0076] S4. The second filtrate was introduced into a simulated moving bed chromatograph (the chromatographic operating temperature was 65℃, the stationary phase was 1000L of chelating cation exchange resin, and the mobile phase was 8200L of purified water) to separate 9000L of the remaining calcium dihydrogen phosphate phase and 3300L of the inositol phase.

[0077] S5. Add 36 kg of activated carbon (pore size 100 nm) to the remaining calcium dihydrogen phosphate phase for decolorization for 1 h, and then filter it through a candle filter (filter cloth pore size 400 mesh) to obtain 9000 L of decolorized calcium dihydrogen phosphate phase.

[0078] S6. The decolorized calcium dihydrogen phosphate phase was vacuum concentrated to a solid content of 35wt% under a vacuum of -0.09MPa and 70℃. The concentrated solution was then crystallized at 30℃ for 10h. The crystallized solution was then added to a centrifuge and centrifuged at a maximum speed of 1050r / min to obtain 272kg of wet calcium dihydrogen phosphate product 2.

[0079] S7. Mix the wet calcium dihydrogen phosphate 1 obtained in S2 and the wet calcium dihydrogen phosphate 2 obtained in S5, and add them to a fluidized bed (inlet air temperature is 130℃, outlet air temperature is 65℃) and dry for 3 minutes to obtain 330kg of finished calcium dihydrogen phosphate.

[0080] Tests showed that the finished product of calcium dihydrogen phosphate had a purity of 98.9% and a yield of 91.2%.

[0081] Example 6

[0082] S1. The 4500L inositol phase obtained in Example 3 was purified by passing it through 900L of ion exchange resin (450L of macroporous strong acid cation exchange resin and 450L of macroporous strong base anion exchange resin) to obtain 4500L of effluent with a conductivity of 20μs / cm.

[0083] S2. The effluent was concentrated under vacuum at -0.09 MPa and 85°C to obtain 200 L of concentrate with a solid content of 40 wt%.

[0084] S3. Add 1 kg of activated carbon (pore size 80 nm) to the concentrate and decolorize for 0.8 h to obtain 200 L of decolorized solution;

[0085] S4. Filter the decolorizing solution through a candle filter (filter cloth with a pore size of 500 mesh) to obtain 200L of concentrated decolorized solution;

[0086] S5. The decolorized concentrate was crystallized at 25°C for 12 hours; the crystallized solution was then added to a centrifuge and centrifuged at the highest speed of 1050 r / min. After drying, 70.5 kg of inositol product was obtained.

[0087] Testing revealed that the inositol product had a purity of 99.6% and a yield of 79.8%.

[0088] Example 7

[0089] S1. The 4900L inositol phase obtained in Example 4 was purified by passing it through 1000L of ion exchange resin (500L of macroporous strong acid cation exchange resin and 500L of macroporous strong base anion exchange resin) to obtain 4900L of effluent with a conductivity of 10μs / cm.

[0090] S2. The effluent was concentrated under vacuum at -0.07 MPa and 90°C to obtain 200 L of concentrate with a solid content of 35 wt%.

[0091] S3. Add 0.6 kg of activated carbon (pore size 100 nm) to the concentrate and decolorize for 0.5 h to obtain 200 L of decolorized solution;

[0092] S4. Filter the decolorizing solution through a candle filter (filter cloth with a pore size of 400 mesh) to obtain 200L of concentrated decolorized solution;

[0093] S5. The decolorized concentrate was crystallized at 30°C for 18 hours; the crystallized solution was then added to a centrifuge and centrifuged at the highest speed of 1050 r / min. After drying, 63.8 kg of inositol product was obtained.

[0094] Testing revealed that the inositol product had a purity of 99.6% and a yield of 78.5%.

[0095] Example 8

[0096] S1. The 3300L inositol phase obtained in Example 5 was purified by passing it through a 700L ion exchange resin (350L macroporous strong acid cation exchange resin and 350L macroporous strong base anion exchange resin) to obtain a 3300L effluent with a conductivity of 0μs / cm.

[0097] S2. The effluent was concentrated under vacuum at -0.08 MPa and 80°C to obtain 160 L of concentrate with a solid content of 50 wt%.

[0098] S3. Add 0.8 kg of activated carbon (pore size 50 nm) to the concentrate and decolorize for 1 hour to obtain 160 L of decolorized solution;

[0099] S4. Filter the decolorizing solution through a candle filter (600 mesh filter cloth) to obtain 160L of concentrated decolorized solution;

[0100] S5. The decolorized concentrate was crystallized at 35°C for 24 hours; the crystallized solution was then added to a centrifuge and centrifuged at the highest speed of 1050 r / min. After drying, 77.2 kg of inositol product was obtained.

[0101] Testing revealed that the inositol product had a purity of 99.5% and a yield of 83.4%.

[0102] Example 9

[0103] S1. The 4900L inositol phase obtained in Example 4 was purified by passing it through 1000L of ion exchange resin (500L of macroporous strong acid cation exchange resin and 500L of macroporous strong base anion exchange resin) to obtain 4900L of effluent with a conductivity of 10μs / cm.

[0104] S2. The effluent was concentrated under vacuum at -0.07 MPa and 90°C to obtain 200 L of concentrate with a solid content of 35 wt%.

[0105] S3. Filter the concentrate through a candle filter (filter cloth with a pore size of 400 mesh) to obtain 200L of concentrate;

[0106] S4. The decolorized concentrate was crystallized at 30°C for 18 hours; the crystallized solution was then added to a centrifuge and centrifuged at the highest speed of 1050 r / min. After drying, 62.0 kg of inositol product was obtained.

[0107] Tests showed that the purity of the finished inositol product was 97.5%, and the yield was 75.3%.

[0108] Comparative Example 1

[0109] In Example 1, step S1, "adjust the pH of the Fiding slurry to 3" is changed to "adjust the pH of the Fiding slurry to 5", while other conditions remain unchanged.

[0110] Tests showed that the hydrolysate containing calcium phytate contained 17.6 g / L of inositol, 8.3 g / L of dicalcium phosphate, and 63.6 g / L of calcium dihydrogen phosphate.

[0111] Comparative Example 2

[0112] In step S2 of Example 3, "perform flash evaporation at atmospheric pressure and wait for the temperature to drop to 98°C" is changed to "perform cooling and wait for the temperature to drop to 98°C", while other conditions remain unchanged.

[0113] Tests showed that the finished product of calcium dihydrogen phosphate had a purity of 90.1% and a yield of 87.2%.

[0114] Comparative Example 3

[0115] In Example 4, step S3, "perform vacuum flash evaporation and wait for the temperature to drop to 50°C" is changed to "perform static cooling at normal pressure and wait for the temperature to drop to 50°C", while other conditions remain unchanged.

[0116] Tests showed that the finished product of calcium dihydrogen phosphate had a purity of 97.3% and a yield of 86.6%.

[0117] Comparative Example 4

[0118] Replace the "chelating cation exchange resin" in step S4 of Example 4 with an equal amount of "macroporous adsorption resin", while keeping all other conditions unchanged.

[0119] Tests showed that the purity of the finished calcium dihydrogen phosphate product was 73.5%, and the yield was 77.2%.

[0120] Test case

[0121] A. Purity of calcium dihydrogen phosphate: Tested according to the method in national standard GB25559-2010.

[0122] B. Calcium dihydrogen phosphate yield = (weight of calcium dihydrogen phosphate product * purity of calcium dihydrogen phosphate product) / (volume of hydrolysate * concentration of calcium dihydrogen phosphate in hydrolysate)

[0123] C. Inositol purity: Tested according to the method in national standard GB23879-2009.

[0124] D. Inositol yield = (weight of inositol product * purity of inositol product) / (volume of hydrolysate * concentration of inositol in hydrolysate).

[0125] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing calcium dihydrogen phosphate using calcium phytate, characterized in that, Includes the following steps: Calcium phytate is hydrolyzed, and the pH of the hydrolysis process is controlled at 3-4 to obtain a hydrolysate containing calcium dihydrogen phosphate and inositol. The temperature of the hydrolysate is controlled at 160-170℃. After flash evaporation at atmospheric pressure and cooling to 95-100℃, insoluble impurities are filtered while hot to obtain the first filtrate. After the first filtrate is flash-evaporated under vacuum and cooled to 50-60°C, calcium dihydrogen phosphate is supersaturated and precipitated. The filtrate is then filtered to obtain the second filtrate and wet calcium dihydrogen phosphate 1. The wet calcium dihydrogen phosphate product 1 is dried to obtain the finished calcium dihydrogen phosphate product.

2. The method according to claim 1, characterized in that, The vacuum degree of the vacuum flash evaporation is -0.05MPa to -0.07MPa.

3. The method according to claim 1 or 2, characterized in that, The process of obtaining the second filtrate and wet calcium dihydrogen phosphate 1 includes: The second filtrate was then subjected to chromatographic separation to obtain the remaining calcium dihydrogen phosphate phase and inositol phase; After vacuum concentration, cooling crystallization and centrifugation, the calcium dihydrogen phosphate phase was used to obtain wet calcium dihydrogen phosphate product 2. The wet calcium dihydrogen phosphate product 2 and the wet calcium dihydrogen phosphate product 1 are mixed and dried to obtain the finished calcium dihydrogen phosphate product.

4. The method according to claim 3, characterized in that, The chromatography method used is simulated moving bed chromatography.

5. The method according to claim 4, characterized in that, The operating temperature of the chromatogram is 55-65℃; the stationary phase is a chelating cation exchange resin, the mobile phase is purified water, and the volume ratio of the stationary phase to the second filtrate in a single feed is (8-10):1; the volume ratio of the mobile phase to the second filtrate is (2-3):

1.

6. The method according to any one of claims 3-5, characterized in that, The vacuum concentration is performed at a vacuum level of -0.07 MPa to -0.09 MPa and a temperature of 70-80°C, resulting in a concentrated calcium dihydrogen phosphate phase solid content of 35-50 wt%; and / or, The cooling crystallization temperature is 30-35℃, and the time is 8-10 hours; and / or, The centrifugal separation is carried out using a centrifuge with a maximum centrifugal speed of 1050 r / min.

7. The method according to any one of claims 3-6, characterized in that, The process of mixing and drying the wet calcium dihydrogen phosphate 2 and wet calcium dihydrogen phosphate 1 includes: mixing the wet calcium dihydrogen phosphate 2 and wet calcium dihydrogen phosphate 1 and then drying them through a fluidized bed, wherein the inlet air temperature of the fluidized bed is 120-130℃, the outlet air temperature is 55-65℃, and the drying time is 3-5 minutes.

8. The method according to any one of claims 3-7, characterized in that, After obtaining the remaining calcium dihydrogen phosphate phase, before the calcium dihydrogen phosphate phase undergoes vacuum concentration, cooling crystallization, and centrifugation, it further includes: The calcium dihydrogen phosphate phase is decolorized by activated carbon and then filtered to obtain the decolorized calcium dihydrogen phosphate phase; wherein the amount of activated carbon used is 2-5 g / L and the decolorization time is 0.5-1 h.

9. The method according to claim 1, characterized in that, After obtaining the inositol phase, the process further includes: The inositol phase was purified by ion exchange to obtain an effluent with a conductivity of 0-20 μS / cm. The effluent is concentrated under vacuum conditions of -0.07MPa to -0.09MPa and temperature of 80-90℃ to obtain a concentrated solution with a solid content of 35-50%. The concentrate was crystallized at 25-35℃ for 12-24 hours, and then centrifuged to obtain the inositol product.

10. The method according to claim 9, characterized in that, After vacuum concentration to obtain a concentrated solution, the concentrated solution, before crystallization, further includes: Activated carbon is added to the concentrate for decolorization, and the solution is filtered to obtain a decolorized concentrate. The amount of activated carbon used is 3-5 g / L, and the decolorization time is 0.5-1 h.