A process for recovering inositol from potassium dihydrogen phosphate mother liquor and by-product tricalcium phosphate and 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 inositol from potassium dihydrogen phosphate mother liquor and byproduct tricalcium phosphate and phytase resolving agent, which comprises the following steps: adding collected potassium dihydrogen phosphate crystallization mother liquor into a neutralizer for reaction, filtering, drying the filter cake, treating the filtrate through a hollow fiber membrane, adding the collected first permeate into hydrochloric acid for neutralization reaction, then concentrating, collecting the second retentate and the second permeate respectively, concentrating the collected retentate, decolorizing, cooling and crystallizing, drying the collected filter cake to obtain inositol products; then concentrating the second permeate to obtain a concentrated solution containing potassium chloride as a phytase resolving agent. The process method can obtain high-purity, high-yield and high-content inositol products from potassium dihydrogen phosphate mother liquor, and can also obtain byproduct tricalcium phosphate, and can also recycle and utilize potassium ions in the potassium dihydrogen phosphate mother liquor.

Description

Technical Field

[0001] This invention relates to the field of corn soaking water treatment technology, and in particular to a process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid desorption agent as byproducts. 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] Existing patents disclose 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 and insufficient recovery of potassium ions from the mother liquor. Therefore, to address these issues, it is necessary to develop a process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid as byproducts. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid desorption agent as byproducts, in order to address the shortcomings of the prior art. This process can recover inositol from the mother liquor, and can also recover potassium ions from the mother liquor to obtain potassium chloride as a phytic acid desorption agent. In addition, tricalcium phosphate byproduct is also obtained.

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

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

[0008] (1) Add a neutralizing agent to the collected potassium dihydrogen phosphate mother liquor, stir, adjust the pH of the liquid to not less than 7, control the reaction temperature and reaction time, and use the liquid obtained after the reaction is completed.

[0009] (2) Take the liquid material described in step (1), filter it and collect the filtrate for later use. The collected filter cake is dried to obtain tricalcium phosphate product.

[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), adjust the pH to acidic, and then process it through a nanofiltration membrane to collect the second retentate and the second permeate respectively.

[0012] (5) Take the second retentate from step (4), continue to concentrate it, and then decolorize and filter it to obtain a decolorized liquid for later use;

[0013] (6) Take the decolorizing liquid described in step (5), cool it down to crystallize, filter it, and rinse it to collect the filter cake and filtrate respectively;

[0014] (7) Take the filtrate from step (6), concentrate, cool and crystallize, filter, rinse, combine the collected filter cake with the filter cake from step (6), dry to obtain inositol product, and use the collected filtrate as a feed additive component or organic fertilizer component.

[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 neutralizing agent in step (1) is calcium oxide or calcium hydroxide, the pH of the liquid is adjusted to 7-9, the reaction temperature is controlled at 30-60℃, and the reaction time is 1-3h.

[0017] As an improved technical solution, a plate and frame filter with a filter cloth pore size of 400 mesh is used for filtration in step (2).

[0018] 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 30-60℃, and every 20-40 minutes of operation, the permeate is backflushed for 30-60 seconds. Filtration is stopped when the permeate volume is reduced to 5-10% of the original volume. The hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-60-80.

[0019] As an improved technical solution, in step (4), 3-5 wt% HCl is used to adjust the pH to 4-6, and a nanofiltration membrane with a molecular weight cutoff of 100-200 Da is used for treatment.

[0020] As an improved technical solution, the solid content of the concentrate in step (5) is 45-60 wt%.

[0021] As an improved technical solution, the decolorizing liquid in step (6) is cooled to 25-40℃ within 4-6 hours and kept at that temperature for 1 hour for crystallization.

[0022] As an improved technical solution, when the filtrate in step (7) is concentrated to a solid content of 45-60 wt%, it is cooled to 30-40℃ in 4-8 hours.

[0023] As an improved technical solution, in step (8), the second permeate is concentrated using a reverse osmosis membrane, with an operating temperature of 30-60℃ and an operating pressure of 4.5-6.0MPa.

[0024] As an improved technical solution, the potassium chloride concentrate in step (8) has a solid content of 8-15 wt%.

[0025] After adopting the above technical solution, the beneficial effects of the present invention are:

[0026] This invention involves adding a neutralizing agent to the collected potassium dihydrogen phosphate crystallization mother liquor for neutralization, followed by drying the filtered cake to obtain tricalcium phosphate. The collected filtrate is then treated with a hollow fiber membrane. The first permeate is neutralized with hydrochloric acid and concentrated using a nanofiltration membrane. The second retentate and the second permeate are collected separately. The second retentate is concentrated, decolorized, and cooled for crystallization. The collected filter cake is dried to obtain inositol. The collected filtrate is further concentrated, cooled for crystallization, and filtered. The collected filter cake is dried and combined with the inositol product. The second permeate is then concentrated to obtain a potassium chloride-containing concentrate, which can be used as a phytic acid desorption agent. This process can obtain high-purity, high-yield, and high-content inositol from potassium dihydrogen phosphate mother liquor, while also yielding the byproduct tricalcium phosphate. Furthermore, potassium ions in the potassium dihydrogen phosphate mother liquor can be recovered to obtain a potassium chloride-containing concentrate for use as a phytic acid desorption agent. Detailed Implementation

[0027] 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.

[0028] Example 1

[0029] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid as byproducts includes the following steps:

[0030] (1) Add a neutralizing agent (calcium oxide) to 1000L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 35g / L, inorganic phosphorus concentration 149g / L, potassium ion concentration 108g / L), stir, adjust the pH of the liquid to 7, control the reaction temperature at 30℃, and 1088L of liquid is obtained after 1 hour of reaction for later use.

[0031] (2) Take 1088L of the liquid from step (1) and filter it using a plate and frame filter press with a filter cloth pore size of 400 mesh. Collect 796L of filtrate for later use. Collect 372.8kg of filter cake and dry it to obtain tricalcium phosphate product.

[0032] (3) Take 796L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.4MPa, the operating temperature at 30℃, and backflush with permeate for 30s every 20min, 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-60). Collect 40L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 758L of the first permeate respectively.

[0033] (4) Take 758L of the first permeate from step (3), adjust the pH to 4 with 5wt% HCl, and treat it with a nanofiltration membrane with a molecular weight cutoff of 100Da. Collect 233L of the second retentate and 2010L of the second permeate respectively.

[0034] (5) Take 233L of the second retentate from step (4) and continue to concentrate it to obtain a concentrated solution with a solid content of 45wt% and a temperature of 95℃. Add 0.8kg of activated carbon at a ratio of 100:1 between the volume of the concentrated solution and the weight of the activated carbon. Stir and filter to obtain 78.2L of decolorizing solution for later use.

[0035] (6) Take 78.2L of the decolorizing liquid from step (5), cool it to 40℃ within 4 hours, keep it at the temperature for 1 hour for crystallization, filter, rinse, and collect 22.3kg of filter cake and 58.5L of filtrate respectively;

[0036] (7) Take 58.5L of the filtrate from step (6), and after heat concentration treatment, obtain 36.1L of concentrate with a solid content of 45wt%. Cool to 40℃ for 4 hours, filter, rinse, collect 10.4kg filter cake and filter cake from step (6), combine and dry to obtain inositol product. The collected filtrate is used as a feed additive component or organic fertilizer component.

[0037] (8) Take the second permeate from step (4) and concentrate it using a reverse osmosis membrane (operating temperature 30℃, operating pressure 4.5MPa) to obtain 1282L of potassium chloride concentrate as phytic acid desorption agent.

[0038] Example 2

[0039] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid as byproducts includes the following steps:

[0040] (1) Add a neutralizing agent (calcium hydroxide) to 1000L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 35g / L, inorganic phosphorus concentration 149g / L, potassium ion concentration 108g / L), stir, adjust the pH of the liquid to 7.5, control the reaction temperature at 40℃, and after reacting for 1.5h, 1091L of liquid is obtained for later use.

[0041] (2) Take 1091L of the liquid from step (1) and filter it using a plate and frame filter press with a filter cloth pore size of 400 mesh. Collect 793L of filtrate for later use. Collect 381.1kg of filter cake and dry it to obtain tricalcium phosphate product.

[0042] (3) Take 793L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.45MPa, the operating temperature at 37℃, and backflush with permeate for 35s every 25min, 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-70). Collect 48L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 747L of the first permeate respectively.

[0043] (4) Take 747L of the first permeate from step (3), adjust the pH to 4.5 with 3wt% HCl, and treat it with a nanofiltration membrane with a molecular weight cutoff of 200Da. Collect 212L of the second retentate and 3068L of the second permeate respectively.

[0044] (5) Take 212L of the second retentate from step (4), and continue to concentrate it to obtain a concentrated solution with a solid content of 50wt% and a temperature of 95℃. Add 1.1kg of activated carbon at a ratio of 100:1.5 between the volume of the concentrated solution and the weight of the activated carbon. Stir and filter to obtain 77.1L of decolorizing solution for later use.

[0045] (6) Take 77.1L of the decolorizing liquid from step (5), cool it to 30℃ within 4.5h, keep it at the temperature for 1h for crystallization, filter, rinse, and collect 23.1kg of filter cake and 55.2L of filtrate respectively;

[0046] (7) Take 55.2L of the filtrate from step (6), and after heat concentration treatment, obtain 30.2L of concentrate with a solid content of 50wt%. Cool down to 32℃ for 5 hours, filter, rinse, collect 8.5kg filter cake and filter cake from step (6), combine and dry to obtain inositol product. The collected filtrate is used as a feed additive component or organic fertilizer component.

[0047] (8) Take the second permeate from step (4) and concentrate it using a reverse osmosis membrane (operating temperature 40℃, operating pressure 5MPa) to obtain 2483L of potassium chloride concentrate as phytic acid desorption agent.

[0048] Example 3

[0049] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid as byproducts includes the following steps:

[0050] (1) Add a neutralizing agent (calcium oxide) to 1000L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 35g / L, inorganic phosphorus concentration 149g / L, potassium ion concentration 108g / L), stir, adjust the pH of the liquid to 8, control the reaction temperature at 45℃, and after 2 hours of reaction, 1095L of liquid is obtained for use.

[0051] (2) Take 1095L of the liquid from step (1) and filter it using a plate and frame filter press with a filter cloth pore size of 400 mesh. Collect 788L of filtrate for later use. Collect 392.7kg of filter cake and dry it to obtain tricalcium phosphate product.

[0052] (3) Take 788L 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 45s every 30min, 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-80). Collect 55L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 735L of the first permeate respectively.

[0053] (4) Take 735L of the first permeate from step (3), adjust the pH to 5 with 4wt% HCl, and treat it with a nanofiltration membrane with a molecular weight cutoff of 150Da. Collect 199L of the second retentate and 2400L of the second permeate respectively.

[0054] (5) Take 199L of the second retentate from step (4) and continue to concentrate it to obtain a concentrated solution with a solid content of 55wt% and a temperature of 95℃. Add 1.36kg of activated carbon at a ratio of 100:2 between the volume of the concentrated solution and the weight of the activated carbon. Stir and filter to obtain 68.9L of decolorizing solution for later use.

[0055] (6) Take 68.9L of the decolorizing liquid from step (5), cool it to 35℃ within 5h, keep it at the temperature for 1h for crystallization, filter, rinse, and collect 25.1kg of filter cake and 45.5L of filtrate respectively;

[0056] (7) Take 45.5L of the filtrate from step (6), and after heat concentration treatment, obtain 26.3L of concentrate with a solid content of 50wt%. Cool to 35℃ for 6 hours, filter, rinse, collect 8.0kg filter cake and filter cake from step (6), combine and dry to obtain inositol product. The collected filtrate is used as a feed additive component or organic fertilizer component.

[0057] (8) Take the second permeate from step (4) and concentrate it using a reverse osmosis membrane (operating temperature 50℃, operating pressure 5.3MPa) to obtain 1819L of potassium chloride concentrate as phytic acid desorption agent.

[0058] Example 4

[0059] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid as byproducts includes the following steps:

[0060] (1) Add a neutralizing agent (calcium hydroxide) to 1000L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 35g / L, inorganic phosphorus concentration 149g / L, potassium ion concentration 108g / L), stir, adjust the pH of the liquid to 8.5, control the reaction temperature at 55℃, and after reacting for 2.5h, 1096L of liquid is obtained for later use.

[0061] (2) Take 1096L of the liquid from step (1) and filter it using a plate and frame filter press with a filter cloth pore size of 400 mesh. Collect 790L of filtrate for later use. Collect 394.2kg of filter cake and dry it to obtain tricalcium phosphate product.

[0062] (3) Take 790L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.55MPa, the operating temperature at 52℃, and backflush with permeate for 50s every 35min, and stop filtering when the original volume is reduced to 9%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-70). Collect 71L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 721L of the first permeate respectively.

[0063] (4) Take 721L of the first permeate from step (3), adjust the pH to 5.5 with 3wt% HCl, and treat it with a nanofiltration membrane with a molecular weight cutoff of 200Da. Collect 167L of the second retentate and 3039L of the second permeate respectively.

[0064] (5) Take 167L of the second retentate from step (4) and continue to concentrate it to obtain a concentrated solution with a solid content of 58wt% and a temperature of 95℃. Add 1.6kg of activated carbon at a ratio of 100:2.5 between the volume of the concentrated solution and the weight of the activated carbon. Stir and filter to obtain 65.5L of decolorizing solution for later use.

[0065] (6) Take 65.5L of the decolorizing liquid from step (5), cool it to 38℃ within 5.5h, keep it at the temperature for 1h for crystallization, filter, rinse, and collect 24.6kg of filter cake and 43.9L of filtrate respectively;

[0066] (7) Take 43.9L of the filtrate from step (6), and after heat concentration treatment, obtain 22.3L of concentrate with a solid content of 58wt%. Cool to 38℃ for 7 hours, filter, rinse, collect 7.8kg filter cake and filter cake from step (6), combine and dry to obtain inositol product. The collected filtrate is used as a feed additive component or organic fertilizer component.

[0067] (8) Take the second permeate from step (4) and concentrate it using a reverse osmosis membrane (operating temperature 55℃, operating pressure 5.5MPa) to obtain 1923L of potassium chloride concentrate as phytic acid desorption agent.

[0068] Example 5

[0069] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid as byproducts includes the following steps:

[0070] (1) Add a neutralizing agent (calcium oxide) to 1000L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 35g / L, inorganic phosphorus concentration 149g / L, potassium ion concentration 108g / L), stir, adjust the pH of the liquid to 9, control the reaction temperature at 60℃, and after 3 hours of reaction, 1098L of liquid is obtained for use.

[0071] (2) Take 1098L of the liquid from step (1) and filter it using a plate and frame filter press with a filter cloth pore size of 400 mesh. Collect 791L of filtrate for later use. Collect 395.5kg of filter cake and dry it to obtain tricalcium phosphate product.

[0072] (3) Take 791L of filtrate from step (2) and process it through a hollow fiber membrane (control the operating pressure at 0.6MPa, the operating temperature at 60℃, and backflush with permeate for 60s every 40min, and stop filtering when the original volume is reduced to 10%; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-80), and collect 79L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 714L of the first permeate respectively.

[0073] (4) Take 714L of the first permeate from step (3), adjust the pH to 6 with 5wt% HCl, and treat it with a nanofiltration membrane with a molecular weight cutoff of 100Da. Collect 168L of the second retentate and 2038L of the second permeate respectively.

[0074] (5) Take 168L of the second retentate from step (4) and continue to concentrate it to obtain a concentrated solution with a solid content of 60wt% and a temperature of 95℃. Add 1.9kg of activated carbon at a ratio of 100:3 between the volume of the concentrated solution and the weight of the activated carbon. Stir and filter to obtain 65.7L of decolorizing solution for later use.

[0075] (6) Take 65.7L of the decolorizing liquid from step (5), cool it to 40℃ within 6 hours, keep it at the temperature for 1 hour for crystallization, filter, rinse, and collect 24.2kg of filter cake and 43.4L of filtrate respectively;

[0076] (7) Take 43.4L of the filtrate from step (6), and after heat concentration treatment, obtain 20.4L of concentrate with a solid content of 60wt%. Cool down to 40℃ for 8 hours, filter, rinse, collect 7.6kg filter cake and filter cake from step (6), combine and dry to obtain inositol product. The collected filtrate is used as a feed additive component or organic fertilizer component.

[0077] (8) Take the second permeate from step (4) and concentrate it using a reverse osmosis membrane (operating temperature 60℃, operating pressure 6.0MPa) to obtain 1464L of potassium chloride concentrate as phytic acid desorption agent.

[0078] 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 byproduct tricalcium phosphate and phytic acid desorption agent, 13 comparative examples are provided with reference to Example 3, as detailed below.

[0079] Comparative Example 1

[0080] Unlike Example 3, the pH of the feed solution was adjusted to 6.5 in step (1), while the rest of the operations were the same.

[0081] Comparative Example 2

[0082] Unlike Example 3, the temperature is controlled at 25°C in step (1), while the rest of the operation is the same.

[0083] Comparative Example 3

[0084] Unlike Example 3, the membrane operating pressure in step (3) is 0.3 MPa, while the rest of the operation is the same.

[0085] Comparative Example 4

[0086] Unlike Example 3, the operating temperature of the membrane in step (3) is 20°C, while the rest of the operation is the same.

[0087] Comparative Example 5

[0088] Unlike Example 3, the membrane operating temperature in step (3) is 70°C, while the rest of the operation is the same.

[0089] Comparative Example 6

[0090] Unlike Example 3, the membrane used in step (3) is NF-55, but the rest of the operation is the same.

[0091] Comparative Example 7

[0092] Unlike Example 3, the membrane used in step (3) is NF-85, but the rest of the operation is the same.

[0093] Comparative Example 8

[0094] Unlike Example 3, step (4) is missing; the rest of the operations are the same.

[0095] Comparative Example 9

[0096] Unlike Example 3, in step (4), the pH is adjusted to 6.5, while the rest of the operation is the same.

[0097] Comparative Example 10

[0098] Unlike Example 3, the concentration of the concentrate in step (5) is 40 wt%, while the rest of the operation is the same.

[0099] Comparative Example 11

[0100] Unlike Example 3, the concentration of the concentrate in step (5) is 65 wt%, while the rest of the operation is the same.

[0101] Comparative Example 12

[0102] Unlike Example 3, in step (6), the temperature is lowered to 20°C, while the rest of the operation is the same.

[0103] Comparative Example 13

[0104] Unlike Example 3, in step (6), the temperature is lowered to 45°C, while the rest of the operation is the same.

[0105] Table 1

[0106]

[0107]

[0108] As can be seen from Table 1, the inositol yield, purity, tricalcium 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 1-13.

[0109] 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 inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor, characterized in that, Includes the following steps: (1) Add a neutralizing agent to the collected potassium dihydrogen phosphate mother liquor, stir, adjust the pH of the liquid to 7-9, control the reaction temperature at 30-60℃ and the reaction time, 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. The collected filter cake is dried to obtain tricalcium phosphate product. (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 0.4-0.6MPa and the operating temperature at 30-60℃; the hollow fiber membrane is made of polyvinylidene fluoride and the membrane model is NF-60~80; (4) Take the first permeate from step (3), adjust the pH to 4-6, and then treat it with a nanofiltration membrane to collect the second retentate and the second permeate respectively; (5) Take the second retentate from step (4), continue to concentrate it to obtain a concentrated solution with a solid content of 45-60wt%, and then decolorize and filter it to obtain a decolorized solution for later use. (6) Take the decolorizing liquid described in step (5), cool it to 25-40℃ within 4-6 hours, keep it warm for 1 hour for crystallization, filter, rinse, and collect the filter cake and filtrate respectively; (7) Take the filtrate from step (6), concentrate, cool and crystallize, filter, and rinse. Combine the collected filter cake with the filter cake from step (6) and dry to obtain the inositol product. The collected filtrate is used as a feed additive component or an organic fertilizer component. (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 inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, The neutralizing agent mentioned in step (1) is calcium oxide or calcium hydroxide, and the reaction time is controlled at 1-3 hours.

3. The process for recovering inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (2), a plate and frame filter with a filter cloth pore size of 400 mesh is used for filtration.

4. The process for recovering inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, When using hollow fiber membranes in step (3), backflush the permeate for 30-60 seconds every 20-40 minutes of operation, and stop filtration when the volume is reduced to 5-10% of the original volume.

5. The process for recovering inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (4), 3-5 wt% HCl is used to adjust the pH, and a nanofiltration membrane with a molecular weight cutoff of 100-200 Da is used for treatment.

6. The process for recovering inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, When the filtrate in step (7) is concentrated to a solid content of 45-60 wt%, it is cooled to 30-40 °C in 4-8 hours.

7. The process for recovering inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, In step (8), the second permeate is concentrated using a reverse osmosis membrane at an operating temperature of 30-60℃ and an operating pressure of 4.5-6.0MPa.

8. The process for recovering inositol and producing tricalcium phosphate and phytic acid as byproducts from potassium dihydrogen phosphate mother liquor according to claim 1, characterized in that, The potassium chloride concentrate in step (8) has a solid content of 8-15 wt%.

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