A process for recovering potassium dihydrogen phosphate and inositol from a potassium dihydrogen phosphate mother liquor and co-producing a phytase resolving agent

Abstract

The present application relates to the technical field of corn soaking water treatment, and particularly relates to a process method for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and by-product phytate resolving agent, comprising the following contents: collected potassium dihydrogen phosphate mother liquor is adjusted to be acidic, stirring and filtering, the collected filtrate is treated by a hollow fiber membrane, the collected first permeate is treated by a nanofiltration membrane, the collected second retentate is treated by a simulated moving bed chromatography separation system, the collected inositol phase is concentrated, then decolorized, filtered, cooled and crystallized, filtered, eluted, dried and crushed to obtain an inositol product; the collected salt phase is concentrated, cooled, filtered and dried to obtain a potassium dihydrogen phosphate product. The second permeate is treated by a reverse osmosis membrane to obtain a concentrated solution containing potassium chloride. The above process method can obtain an inositol product with high yield and high purity, and can also obtain a potassium dihydrogen phosphate product; in addition, a phytate resolving agent can be by-produced, and the use of phytate resolving agent raw materials is reduced.

Description

Technical Field

[0001] This invention relates to the field of corn soaking water treatment technology, and in particular to a process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid desorption agent as a byproduct. Background Technology

[0002] Corn soaking water is a byproduct of wet corn starch production, containing 1-2% phytic acid. Currently, there are reported methods for recovering phytic acid from corn soaking water to prepare potassium phytate, followed by hydrolysis, separation, concentration, and crystallization to produce inositol and potassium dihydrogen phosphate. Compared to traditional potassium dihydrogen phosphate production processes such as neutralization and metathesis, using corn soaking water as a raw material not only avoids the environmental damage caused by phosphate rock mining but also achieves the recycling of phosphorus resources from plants, resulting in significant economic and social benefits.

[0003] Current processes typically separate potassium dihydrogen phosphate (KH2PO4) and inositol obtained from corn soaking water using simulated moving bed chromatography. This separation yields KH2PO4 and inositol solutions. However, both inositol and KH2PO4 are readily soluble in water. In actual production, limitations imposed by chromatographic resin separation and process parameters mean that the resulting KH2PO4 solution usually contains a certain concentration of inositol. During KH2PO4 crystallization, inositol, pigments, proteins, calcium and magnesium, chloride ions, and other substances gradually accumulate in the mother liquor, eventually reaching a KH2PO4 concentration of 25-45 g / L. Currently, the KH2PO4 crystallization mother liquor is mostly sold directly as liquid fertilizer, resulting in significant underutilization of its inositol value and substantial losses.

[0004] Currently, a patent discloses a process for recovering inositol from potassium dihydrogen phosphate mother liquor. While this process can recover inositol from the mother liquor, small molecule salts are not separated from inositol during crude product crystallization, resulting in a low inositol yield. Furthermore, it does not fully recover phosphate and potassium ions from the mother liquor. Therefore, to address these issues, it is necessary to develop a process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor, while also producing phytic acid as a byproduct. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid desorption agent as a byproduct, in order to address the shortcomings of the prior art. This process can obtain a high yield of inositol product, recover potassium dihydrogen phosphate, and also obtain phytic acid desorption agent as a byproduct, thereby increasing the economic benefits for enterprises.

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

[0007] A process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct includes the following steps:

[0008] (1) Add alkali or carbonate to the collected potassium dihydrogen phosphate mother liquor, stir, adjust the pH of the liquid to acidic, control the reaction temperature, and set aside the liquid after the reaction is completed.

[0009] (2) Take the liquid material described in step (1), filter it and collect the filtrate for later use;

[0010] (3) Take the filtrate from step (2), process it through a hollow fiber membrane, and collect the first retentate and the first permeate respectively;

[0011] (4) Take the first permeate from step (3), and after treatment with a nanofiltration membrane, collect the second retentate and the second permeate respectively;

[0012] (5) Take the second retentate from step (4), process it through a simulated moving bed chromatography separation system, and collect the inositol phase and salt phase respectively;

[0013] (6) Take the inositol phase described in step (5), concentrate it, and then decolorize and filter it. The collected decolorized liquid is cooled and crystallized, filtered and washed. The collected filter cake is dried and crushed to obtain the inositol product. The collected filtrate is combined with the potassium dihydrogen phosphate mother liquor.

[0014] (7) Take the salt phase described in step (5), concentrate, cool, and filter. The collected filter cake is dried to obtain potassium dihydrogen phosphate product, and the collected filtrate is used as a component of liquid organic fertilizer.

[0015] (8) Take the second permeate from step (4), concentrate it to obtain a concentrated solution containing potassium chloride as a phytic acid desorption agent.

[0016] As an improved technical solution, the alkali in step (1) is potassium hydroxide, the carbonate is potassium carbonate or potassium bicarbonate, the reaction temperature is controlled at 35-55℃, and the pH of the feed solution is adjusted to 4.0-5.5.

[0017] As an improved technical solution, when using hollow fiber membrane in step (3), the operating pressure is controlled at 0.4-0.6MPa, the operating temperature is 35-55℃, and every 20-40 minutes of operation, the permeate is backflushed for 30-60 seconds, and filtration is stopped when the original volume is reduced to 4-8%; the hollow fiber membrane is made of polyvinylidene fluoride, and the membrane model is NF-40-50.

[0018] As an improved technical solution, in step (4), the first permeate is treated with a nanofiltration membrane with a molecular weight cutoff of 100-200 Da, and the solid content of the second retentate is 20-30 wt%.

[0019] As an improved technical solution, in step (5), when simulating the moving bed chromatography separation system, the operating cycle is 28-40 min, the chromatographic column packing is potassium-type cation resin with a particle size of 300±50 μm, the height-to-diameter ratio of the chromatographic column is 1-1.5:2.0, the feed rate is 15-17% of the volume of a single column, the feed flow rate is 0.6-0.8 BV / h, and the flow rates of circulation, water top salt, and water top inositol are all 1.1-1.5 BV / h.

[0020] As an improved technical solution, in step (7), the salt phase is thermally concentrated to obtain a concentrated solution with a solid content of 50-60 wt%, which is then cooled to 20-30℃ and filtered.

[0021] After adopting the above technical solution, the beneficial effects of the present invention are:

[0022] This invention involves adding alkali or carbonate to the collected potassium dihydrogen phosphate mother liquor to adjust the pH to acidic. After stirring and reacting, the liquid is filtered. The collected filtrate is treated with a hollow fiber membrane, and the first retentate and the first permeate are collected separately. The first permeate is then treated with a nanofiltration membrane. The collected second retentate is then processed in a simulated moving bed chromatography system, where the salt phase and the inositol phase are collected separately. The collected inositol phase is concentrated, then decolorized and filtered. The collected decolorized solution is then cooled, crystallized, filtered, and washed. The collected filter cake is dried and pulverized to obtain the inositol product. The collected salt phase is concentrated, cooled, and filtered. The collected filter cake is dried to obtain the potassium dihydrogen phosphate product. The second permeate is treated with a reverse osmosis membrane to obtain a concentrated solution containing potassium chloride, which is used as a phytic acid eluent. This process can obtain a high-yield, high-purity inositol product and also a potassium dihydrogen phosphate product, increasing the economic benefits for enterprises. In addition, it can also produce a phytic acid eluent as a byproduct, reducing the use of phytic acid eluent raw materials. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] Example 1

[0025] A process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct includes the following steps:

[0026] (1) Add alkali (1wt% potassium hydroxide solution) to 500L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 38.1g / L, potassium dihydrogen phosphate concentration 256.5g / L, potassium chloride concentration 36.8g / L), stir, adjust the pH of the solution to 4.0, control the reaction temperature to 35℃, and 1788L of the solution obtained after the reaction is completed for later use.

[0027] (2) Take 1788L of the material liquid in step (1), filter it through a plate and frame filter press with a filter cloth pore size of 400 mesh, and collect 1788L of the filtrate for later use.

[0028] (3) Take 1788L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.4MPa, the operating temperature at 35℃, and backflush with permeate for 30s every 20min, and stop filtering when the original volume is reduced to 4%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-40). Collect 72L of the first retentate (combined with the potassium dihydrogen phosphate mother liquor) and 1716L of the first permeate respectively.

[0029] (4) Take 1716L of the first permeate from step (3), and after treatment with a nanofiltration membrane with a molecular weight cutoff of 100Da, collect 538L of the second cutoff liquid (solid content of 30wt%) and 1180L of the second permeate.

[0030] (5) Take 538L of the second retentate from step (4) and process it through a simulated moving bed chromatography separation system (running cycle 28.9min, the column packing is potassium-type cation resin with a particle size of 300±50μm, the height-to-diameter ratio of the column is 1:2.0, the feed amount is 15% of the volume of a single column, the feed flow rate is 0.8BV / h, the flow rates of circulation, water top salt and water top inositol are all 1.5BV / h, the volume of each column is 50L, and the number of columns is 6), and collect 646L of inositol phase and 1345L of salt phase respectively.

[0031] (6) Take 646L of the inositol phase from step (5), concentrate it to obtain 35.3L of concentrated solution with a solid content of 45wt%, add 353g of activated carbon (added at a dosage of 1% of the volume of concentrated solution) for decolorization for 0.5h, filter, cool the collected decolorized solution to 25℃ within 4h, keep it at the temperature for 1h for crystallization, filter and rinse, dry and crush the collected filter cake to obtain the inositol product; combine the collected filtrate with potassium dihydrogen phosphate mother liquor;

[0032] (7) Take the salt phase from step (5), and obtain a concentrated liquid with a solid content of 50wt% by heat concentration treatment. Then cool it down to 20℃ and filter it. The collected filter cake is dried to obtain potassium dihydrogen phosphate product. The collected filtrate is used as a component of liquid organic fertilizer.

[0033] (8) Take 1180L of the second permeate from step (4) and process it through a reverse osmosis membrane (temperature 30℃, pressure 4.5MPa) to obtain a concentrated solution containing potassium chloride (solid content 15wt%) as a phytic acid desorption agent.

[0034] Example 2

[0035] A process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct includes the following steps:

[0036] (1) Add carbonate (1wt% potassium bicarbonate solution) to 500L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 38.1g / L, potassium dihydrogen phosphate concentration 256.5g / L, potassium chloride concentration 36.8g / L), stir, adjust the pH of the solution to 4.5, control the reaction temperature to 40℃, and 1854L of the solution obtained after the reaction is completed for later use.

[0037] (2) Take 1854L of the liquid in step (1), filter it through a plate and frame filter press with a filter cloth pore size of 400 mesh, and collect 1856L of the filtrate for later use.

[0038] (3) Take 1856L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.45MPa, the operating temperature at 40℃, and backflush with permeate for 40s every 25min, and stop filtering when the original volume is reduced to 5%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-50). Collect 93L of the first retentate (combined with the potassium dihydrogen phosphate mother liquor) and 1763L of the first permeate respectively.

[0039] (4) Take 1763L of the first permeate from step (3), and after treatment with a nanofiltration membrane with a molecular weight cutoff of 200Da, collect 760L of the second cutoff liquid (solid content of 22wt%) and 1007L of the second permeate.

[0040] (5) Take 760L of the second retentate from step (4) and process it through a simulated moving bed chromatography separation system (running cycle 31.0min, the column packing is potassium-type cation resin with a particle size of 300±50μm, the height-to-diameter ratio of the column is 1.5:2.0, the feed rate is 17% of the volume of a single column, the feed flow rate is 0.75BV / h, the flow rates of circulation, water top salt and water top inositol are all 1.4BV / h, the volume of each column is 75L, and the number of columns is 6), and collect 912L of inositol phase and 1900L of salt phase respectively.

[0041] (6) Take 912L of the inositol phase from step (5), concentrate it to obtain 33.9L of concentrated solution with a solid content of 50wt%, add 509g of activated carbon (added at a dosage of 1.5% of the volume of concentrated solution) for decolorization for 0.6h, filter, cool the collected decolorized solution to 30℃ within 5h, keep it at the temperature for 1h for crystallization, filter and rinse, dry and crush the collected filter cake to obtain the inositol product; combine the collected filtrate with potassium dihydrogen phosphate mother liquor;

[0042] (7) Take the salt phase from step (5), and obtain a concentrated liquid with a solid content of 52wt% by heat concentration treatment. Then cool it down to 22℃ and filter it. The collected filter cake is dried to obtain potassium dihydrogen phosphate product. The collected filtrate is used as a component of liquid organic fertilizer.

[0043] (8) Take 1007L of the second permeate from step (4) and process it through a reverse osmosis membrane (temperature 40℃, pressure 5MPa) to obtain a concentrated solution containing potassium chloride (solid content 8wt%) as a phytic acid desorption agent.

[0044] Example 3

[0045] A process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct includes the following steps:

[0046] (1) Add alkali (1wt% potassium hydroxide solution) to 500L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 38.1g / L, potassium dihydrogen phosphate concentration 256.5g / L, potassium chloride concentration 36.8g / L), stir, adjust the pH of the solution to 5, control the reaction temperature to 45℃, and 1896L of the solution obtained after the reaction is completed for later use.

[0047] (2) Take 1896L of the liquid in step (1), filter it through a plate and frame filter press with a filter cloth pore size of 400 mesh, and collect 1899L of the filtrate for later use.

[0048] (3) Take 1899L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.5MPa, the operating temperature at 45℃, and backflush with permeate for 47s every 30min, and stop filtering when the original volume is reduced to 6%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-45). Collect 114L of the first retentate (combined with the potassium dihydrogen phosphate mother liquor) and 1786L of the first permeate respectively.

[0049] (4) Take 1786L of the first permeate from step (3), and after treatment with a nanofiltration membrane with a molecular weight cutoff of 150Da, collect 608L of the second cutoff liquid (solid content of 27wt%) and 1178L of the second permeate.

[0050] (5) Take 608L of the second retentate from step (4) and process it through a simulated moving bed chromatography separation system (running cycle 33.3min, the column packing is potassium-type cation resin with a particle size of 300±50μm, the height-to-diameter ratio of the column is 1.2:2, the feed rate is 16% of the volume of a single column, the feed flow rate is 0.7BV / h, the flow rates of circulation, water top salt and water top inositol are all 1.3BV / h, the volume of each column is 60L, and the number of columns is 6). Collect 730L of inositol phase and 1520L of salt phase respectively.

[0051] (6) Take 730L of the inositol phase from step (5), concentrate it to obtain 29.2L of concentrate with a solid content of 53wt%, add 438g of activated carbon (add at a dosage of 1.5% of the volume of concentrate) for decolorization for 0.8h, filter, cool the collected decolorized liquid to 32℃ within 6h, keep it at the temperature for 1h for crystallization, filter and rinse, dry and crush the collected filter cake to obtain the inositol product; combine the collected filtrate with potassium dihydrogen phosphate mother liquor;

[0052] (7) Take the salt phase from step (5), and obtain a concentrated liquid with a solid content of 55wt% by heat concentration treatment. Then cool it down to 25℃ and filter it. The collected filter cake is dried to obtain potassium dihydrogen phosphate product. The collected filtrate is used as a component of liquid organic fertilizer.

[0053] (8) Take 1178L of the second permeate from step (4) and process it through a reverse osmosis membrane (temperature 50℃, pressure 5.5MPa) to obtain a concentrated solution containing potassium chloride (solid content 11wt%) as a phytic acid desorption agent.

[0054] Example 4

[0055] A process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct includes the following steps:

[0056] (1) Add carbonate (1wt% potassium carbonate solution) to 500L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 38.1g / L, potassium dihydrogen phosphate concentration 256.5g / L, potassium chloride concentration 36.8g / L), stir, adjust the pH of the solution to 5.2, control the reaction temperature to 50℃, and 1925L of the solution obtained after the reaction is completed for later use.

[0057] (2) Take 1925L of the liquid in step (1), filter it through a plate and frame filter press with a filter cloth pore size of 400 mesh, and collect 1936L of the filtrate for later use.

[0058] (3) Take 1936L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.55MPa, the operating temperature at 50℃, and backflush with permeate for 55s every 35min, and stop filtering when the original volume is reduced to 7%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-40). Collect 136L of the first retentate (combined with the potassium dihydrogen phosphate mother liquor) and 1807L of the first permeate respectively.

[0059] (4) Take 1807L of the first permeate from step (3), and after treatment with a nanofiltration membrane with a molecular weight cutoff of 200Da, collect 579L of the second cutoff liquid (solid content of 28wt%) and 1228L of the second permeate.

[0060] (5) Take 579L of the second retentate from step (4) and process it through a simulated moving bed chromatography separation system (running cycle 35.1min, the column packing is potassium-type cation resin with a particle size of 300±50μm, the height-to-diameter ratio of the column is 1.3:2.0, the feed rate is 15% of the volume of a single column, the feed flow rate is 0.7BV / h, the flow rates of circulation, water top salt and water top inositol are all 1.2BV / h, the volume of each column is 65L, and the number of columns is 6), and collect 695L of the inositol phase and 1448L of the salt phase respectively.

[0061] (6) Take 695L of the inositol phase from step (5), concentrate it to obtain 27L of concentrate with a solid content of 60wt%, add 540g of activated carbon (added at a dosage of 2% of the volume of concentrate) for decolorization for 0.8h, filter, cool the collected decolorized liquid to 35℃ within 7h, keep it at the temperature for 1h for crystallization, filter and rinse, dry and crush the collected filter cake to obtain the inositol product; combine the collected filtrate with potassium dihydrogen phosphate mother liquor;

[0062] (7) Take the salt phase from step (5), and obtain a concentrated liquid with a solid content of 58wt% by heat concentration treatment. Then cool it down to 28℃ and filter it. The collected filter cake is dried to obtain potassium dihydrogen phosphate product. The collected filtrate is used as a component of liquid organic fertilizer.

[0063] (8) Take 1228L of the second permeate from step (4) and process it through a reverse osmosis membrane (temperature 55℃, pressure 6MPa) to obtain a concentrated solution containing potassium chloride (solid content 13wt%) as a phytic acid desorption agent.

[0064] Example 5

[0065] A process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct includes the following steps:

[0066] (1) Add alkali (1wt% potassium hydroxide solution) to 500L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 38.1g / L, potassium dihydrogen phosphate concentration 256.5g / L, potassium chloride concentration 36.8g / L), stir, adjust the pH of the solution to 5.5, and control the reaction temperature to 55℃. After the reaction is completed, 1974L of the solution is prepared for use.

[0067] (2) Take 1974L of the liquid in step (1), filter it through a plate and frame filter press with a filter cloth pore size of 400 mesh, and collect 1977L of the filtrate for later use.

[0068] (3) Take 1977L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.6MPa, the operating temperature at 55℃, and backflush with permeate for 60s every 39.2min, and stop filtering when the original volume is reduced to 8%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-50). Collect 158L of the first retentate (combined with the potassium dihydrogen phosphate mother liquor) and 1821L of the first permeate respectively.

[0069] (4) Take 1821L of the first permeate from step (3), and after treatment with a nanofiltration membrane with a molecular weight cutoff of 150Da, collect 534L of the second cutoff liquid (solid content of 30wt%) and 1287L of the second permeate.

[0070] (5) Take 534 L of the second retentate from step (4) and process it through a simulated moving bed chromatography separation system (running cycle 40 min, the column packing is potassium-type cation resin with a particle size of 300±50 μm, the height-to-diameter ratio of the column is 1.1:2, the feed rate is 17% of the volume of a single column, the feed flow rate is 0.6 BV / h, the flow rates of circulation, water-to-salt and water-to-inositol are all 1.1 BV / h, the volume of each column is 55 L, and the number of columns is 6), and collect 641 L of the inositol phase and 1335 L of the salt phase respectively.

[0071] (6) Take 641L of the inositol phase from step (5), concentrate it to obtain 27.7L of concentrate with a solid content of 60wt%, add 277g of activated carbon (added at a dosage of 1% of the volume of concentrate) for decolorization for 1h, filter, cool the collected decolorized liquid to 40℃ within 8h, keep it at the temperature for 1h for crystallization, filter and rinse, dry and crush the collected filter cake to obtain the inositol product; combine the collected filtrate with potassium dihydrogen phosphate mother liquor;

[0072] (7) Take the salt phase from step (5), and obtain a concentrated liquid with a solid content of 60wt% by heat concentration treatment. Then cool it down to 30℃ and filter it. The collected filter cake is dried to obtain potassium dihydrogen phosphate product. The collected filtrate is used as a component of liquid organic fertilizer.

[0073] (8) Take 1287L of the second permeate from step (4) and process it through a reverse osmosis membrane (temperature 60℃, pressure 6.5MPa) to obtain a concentrated solution containing potassium chloride (solid content 9wt%) as a phytic acid desorption agent.

[0074] To better demonstrate that the process of the present invention can yield high-purity, high-yield, and high-volume inositol products, as well as high-volume potassium dihydrogen phosphate, and can also produce phytic acid desorption agent as a byproduct, 15 comparative examples are given with reference to Example 3, and details are provided below.

[0075] Comparative Example 1

[0076] Unlike Example 3, the pH of the feed solution was adjusted to 3.5 in step (1), while the rest of the operations were the same.

[0077] Comparative Example 2

[0078] Unlike Example 3, the temperature is controlled at 60°C in step (1), while the rest of the operation is the same.

[0079] Comparative Example 3

[0080] Unlike Example 3, the membrane operating pressure in step (3) is 0.3 MPa, while the rest of the operation is the same.

[0081] Comparative Example 4

[0082] Unlike Example 3, the membrane operating temperature in step (3) is 25°C, while the rest of the operation is the same.

[0083] Comparative Example 5

[0084] Unlike Example 3, the membrane operating temperature in step (3) is 65°C, while the rest of the operation is the same.

[0085] Comparative Example 6

[0086] Unlike Example 3, the membrane used in step (3) is NF-35, but the rest of the operation is the same.

[0087] Comparative Example 7

[0088] Unlike Example 3, the membrane used in step (3) is NF-55, but the rest of the operation is the same.

[0089] Comparative Example 8

[0090] Unlike Example 3, step (4) is missing; the rest of the operations are the same.

[0091] Comparative Example 9

[0092] Unlike Example 3, step (5) is missing; the rest of the operations are the same.

[0093] Comparative Example 10

[0094] Unlike Example 3, the particle size of the column packing material in step (5) is 600 μm, while the rest of the operation is the same.

[0095] Comparative Example 11

[0096] Unlike Example 3, in step (5), the feed flow rate is 1.0 BV / h, and the flow rates of circulation, water top salt, and water top inositol are all 2.0 BV / h. The rest of the operations are the same.

[0097] Comparative Example 12

[0098] Unlike Example 3, in step (7), the salt phase is concentrated to a solid content of 45 wt%, while the rest of the operation is the same.

[0099] Comparative Example 13

[0100] Unlike Example 3, in step (7), the salt phase was concentrated to a solid content of 65 wt%, while the rest of the operation was the same.

[0101] Comparative Example 14

[0102] Unlike Example 3, in step (7), the temperature is lowered to 15°C, while the rest of the operation is the same.

[0103] Comparative Example 15

[0104] Unlike Example 3, in step (7), the temperature is lowered to 35°C, while the rest of the operation is the same.

[0105] Table 1

[0106]

[0107] As can be seen from Table 1, the inositol yield, purity, potassium dihydrogen phosphate yield, and phytic acid eluent yield obtained in Example 3 using the process method of the present invention are significantly higher than those of other examples and comparative examples 1-15.

[0108] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct, characterized in that, Includes the following steps: (1) Add alkali or carbonate to the collected potassium dihydrogen phosphate mother liquor, stir, adjust the pH of the liquid to 4.0-5.5, control the reaction temperature to 35-55℃, and use the liquid obtained after the reaction is completed. (2) Take the liquid material described in step (1), filter it, and collect the filtrate for later use; (3) Take the filtrate from step (2), process it through a hollow fiber membrane, and collect the first retentate and the first permeate respectively; when using a hollow fiber membrane, control the operating pressure at 0.4-0.6 MPa and the operating temperature at 35-55℃, and backflush with the permeate for 30-60 seconds every 20-40 minutes of operation, and stop filtering when the original volume is reduced to 4-8%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-40-50; (4) Take the first permeate from step (3), treat it with a nanofiltration membrane, and collect the second retentate and the second permeate respectively; (5) Take the second retentate from step (4), process it through a simulated moving bed chromatography separation system, and collect the inositol phase and salt phase respectively; the chromatographic column packing is potassium-type cation exchange resin with a particle size of 300±50μm, and the feed flow rate is 0.6-0.8BV / h; (6) Take the inositol phase described in step (5), concentrate it, and then decolorize and filter it. The collected decolorized liquid is cooled and crystallized, filtered and washed. The collected filter cake is dried and crushed to obtain the inositol product. The collected filtrate is combined with the potassium dihydrogen phosphate mother liquor. (7) Take the salt phase described in step (5), concentrate it to obtain a concentrated liquid with a solid content of 50-60wt%, cool it down to 20-30℃ and filter it. The collected filter cake is dried to obtain potassium dihydrogen phosphate product, and the collected filtrate is used as a component of liquid organic fertilizer. (8) Take the second permeate from step (4), concentrate it to obtain a concentrated solution containing potassium chloride as a phytic acid desorption agent.

2. The process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct, as described in claim 1, is characterized in that... The alkali in step (1) is potassium hydroxide, and the carbonate is potassium carbonate or potassium bicarbonate.

3. The process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct, as described in claim 1, is characterized in that... In step (4), the first permeate is treated with a nanofiltration membrane with a molecular weight cutoff of 100-200 Da, and the solid content of the second retentate is 20-30 wt%.

4. The process for recovering potassium dihydrogen phosphate and inositol from potassium dihydrogen phosphate mother liquor and producing phytic acid as a byproduct, as described in claim 1, is characterized in that... In step (5), when simulating the moving bed chromatography separation system, the operating cycle is 28-40 min, the height-to-diameter ratio of the chromatographic column is 1-1.5:2.0, the feed rate is 15-17% of the volume of a single column, and the flow rates of circulation, water top salt, and water top inositol are all 1.1-1.5 BV / h.

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