Process method for recovering inositol and byproducts of tricalcium phosphate and phytic acid desorption agent from monopotassium phosphate mother liquor

Abstract

The invention relates to the technical field of corn soaking water treatment, in particular to a process method for recovering inositol and by-producing tricalcium phosphate and a phytic acid desorption agent from monopotassium phosphate mother liquor, which comprises the following steps: adding a neutralizer into the collected monopotassium phosphate crystallization mother liquor, reacting, filtering, drying a filter cake, treating the filtrate with a hollow fiber membrane, and recovering the inositol from the monopotassium phosphate mother liquor. Adding hydrochloric acid into the collected first permeate for neutralization reaction, then concentrating, respectively collecting second trapped fluid and second permeate, concentrating the collected trapped fluid, decolorizing, cooling and crystallizing, and drying the collected filter cake to obtain an inositol product; and then concentrating the second permeate to obtain a concentrated solution containing potassium chloride as the phytic acid desorption agent. According to the process method, an inositol product with high purity, high yield and high content can be obtained from the monopotassium phosphate mother liquor, meanwhile, a byproduct tricalcium phosphate can be obtained, and potassium ions in the monopotassium phosphate mother liquor can be recycled.

Description

Technical Field

[0001] The invention relates to the technical field of corn soaking water treatment, and in particular to a process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and a phytic acid decomposing agent as byproducts. Background Art

[0002] Corn soaking water is a waste product produced during the wet production of corn starch, in which the phytic acid content is 1-2%. At present, a process for recovering phytic acid from corn soaking water, preparing potassium phytate, and then producing inositol and potassium dihydrogen phosphate through hydrolysis, separation, concentration, and crystallization has been reported. Compared with traditional potassium dihydrogen phosphate production processes such as neutralization method and double decomposition method, the production of potassium dihydrogen phosphate using corn soaking water as raw material not only avoids the environmental damage caused by the phosphate rock mining process, but also realizes the recycling of phosphorus resources in plants, which has obvious economic and social benefits.

[0003] In the existing process, potassium dihydrogen phosphate and inositol obtained after corn soaking water is treated are usually separated by simulated moving bed chromatography to obtain potassium dihydrogen phosphate solution and inositol solution. However, inositol and potassium dihydrogen phosphate are both soluble in water. In actual production, the obtained potassium dihydrogen phosphate solution is usually limited by the separation degree of chromatographic resins, process parameters and other conditions. A certain concentration of inositol is contained in the obtained potassium dihydrogen phosphate solution. In the process of potassium dihydrogen phosphate crystallization, inositol, pigments, proteins, calcium, magnesium, chloride ions and other substances are gradually enriched in the potassium dihydrogen phosphate mother liquor, and the final inositol concentration in the mother liquor can reach 25-45g / L. At present, the potassium dihydrogen phosphate crystallization mother liquor is mostly sold directly as liquid fertilizer, and the value of inositol therein is not fully utilized, resulting in a large loss.

[0004] The existing patent discloses a process for recovering inositol from potassium dihydrogen phosphate mother liquor. Although the process can recover inositol from potassium dihydrogen phosphate mother liquor, the small molecule salt is not separated from inositol during crude product crystallization, resulting in a low inositol yield and insufficient recovery of potassium ions in the mother liquor. Therefore, in view of the above problems, it is necessary to develop a process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in view of the deficiencies in the prior art, a process method for recovering inositol from a potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and a phytic acid decomposing agent as byproducts is provided. The process method can be used to recover inositol in the mother liquor, and potassium ions in the mother liquor can also be recovered to obtain potassium chloride as a phytic acid decomposing agent, and tricalcium phosphate byproduct is also obtained.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid decomposing agent as by-products comprises the following steps:

[0008] (1) adding a neutralizing agent to the collected potassium dihydrogen phosphate mother liquor, stirring, adjusting the pH of the liquid to not less than 7, controlling the reaction temperature and reaction time, and the liquid obtained after the reaction is completed is ready for use;

[0009] (2) taking the feed liquid described in step (1), filtering and collecting the filtrate for later use, and drying the collected filter cake to obtain a tricalcium phosphate product;

[0010] (3) taking the filtrate described in step (2), treating it through a hollow fiber membrane, and collecting a first retentate and a first permeate respectively;

[0011] (4) taking the first permeate in step (3), adjusting the pH to acidic, and then treating it with a nanofiltration membrane to collect a second retentate and a second permeate respectively;

[0012] (5) taking the second retentate in step (4), further concentrating it, decolorizing it, and filtering it to obtain a decolorized liquid for later use;

[0013] (6) taking the decolorized liquid in step (5), cooling and crystallizing, filtering, and eluting, and collecting the filter cake and filtrate respectively;

[0014] (7) taking the filtrate described in step (6), concentrating, cooling crystallization, filtering, rinse, the collected filter cake and the filter cake in step (6) merge, dry to obtain an inositol product, and the collected filtrate is used as a feed additive component or an organic fertilizer component;

[0015] (8) The second permeate in step (4) is concentrated to obtain a concentrated solution containing potassium chloride as a phytic acid decomposing agent.

[0016] As an improved technical solution, the neutralizing agent in step (1) is calcium oxide or calcium hydroxide, the pH of the feed solution is adjusted to 7-9, the reaction temperature is controlled at 30-60°C, and the reaction time is 1-3h.

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

[0018] As an improved technical solution, when hollow fiber membrane is used for treatment in step (3), the operating pressure is controlled at 0.4-0.6MPa, the operating temperature is 30-60°C, and the permeate is backflushed for 30-60s every 20-40min of operation, and the filtration is stopped when the filtration volume reaches 5-10% of the original volume; the material of the hollow fiber membrane is polyvinylidene fluoride, and the membrane model of the hollow fiber membrane 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 concentrated solution in step (5) is 45-60wt%.

[0021] As an improved technical solution, the decolorized liquid in step (6) is cooled to 25-40°C within 4-6 hours and kept warm for crystallization for 1 hour.

[0022] As an improved technical solution, when the filtrate in step (7) is concentrated to a solid content of 45-60 wt%, the temperature is then reduced to 30-40° C. within 4-8 hours.

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

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

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

[0026] The present invention adds a neutralizing agent to the collected potassium dihydrogen phosphate crystal mother liquor for neutralization reaction, and then the filter cakes collected by filtration are dried to obtain tricalcium phosphate products, and the collected filtrate is processed by hollow fiber membrane, and the first permeate collected adds hydrochloric acid for neutralization reaction, and then nanofiltration membrane is used for concentration, and the second retentate and the second permeate are collected respectively, wherein the second retentate collected is concentrated, decolorized, and crystallized by cooling, and the collected filter cakes are dried to obtain inositol products, and the collected filtrate continues to be concentrated, crystallized by cooling, and filtered, and the collected filter cakes are merged with the inositol products after drying; Then the second permeate, after concentration, obtains a concentrated solution containing potassium chloride as a phytic acid parsing agent. The above-mentioned process method can obtain a high-purity, high-yield and high-content inositol product from potassium dihydrogen phosphate mother liquor, and can also obtain a byproduct tricalcium phosphate, and the potassium ions in the potassium dihydrogen phosphate mother liquor can also be recovered to obtain a concentrated solution containing potassium chloride as a phytic acid parsing agent. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] Example 1

[0029] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid decomposing agent as by-products comprises the following steps:

[0030] (1) adding a neutralizing agent (calcium oxide) to 1000 L of collected potassium dihydrogen phosphate mother liquor (inositol concentration 35 g / L, inorganic phosphorus concentration 149 g / L, potassium ion concentration 108 g / L), stirring, adjusting the pH of the liquid to 7, controlling the reaction temperature at 30° C., reacting for 1 h, and obtaining 1088 L of the liquid for later use;

[0031] (2) taking 1088 L of the feed liquid in step (1), filtering it using a plate and frame filter with a filter cloth pore size of 400 mesh, collecting 796 L of filtrate for later use, and collecting 372.8 kg of filter cake, and drying to obtain a tricalcium phosphate product;

[0032] (3) 796 L of the filtrate in step (2) was taken and treated with a hollow fiber membrane (the operating pressure was controlled at 0.4 MPa, the operating temperature was 30° C., and the permeate was backflushed for 30 s every 20 min of operation, and the filtration was stopped when the volume was 5% of the original volume; the material of the hollow fiber membrane was polyvinylidene fluoride, and the membrane model of the hollow fiber membrane was NF-60), and 40 L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 758 L of the first permeate were collected respectively;

[0033] (4) taking 758 L of the first permeate in step (3), adjusting the pH to 4 with 5 wt % HCl, treating with a nanofiltration membrane with a molecular weight cutoff of 100 Da, and collecting 233 L of the second retentate and 2010 L of the second permeate respectively;

[0034] (5) taking 233 L of the second retentate in step (4), continuing to concentrate to obtain a concentrate having a solid content of 45 wt% and a temperature of 95° C., adding 0.8 kg of activated carbon at a ratio of 100:1 by volume of the concentrate to the weight of activated carbon, stirring, filtering, and obtaining 78.2 L of decolorized liquid for standby use;

[0035] (6) Take 78.2 L of the decolorized liquid in step (5), cool it to 40°C within 4 hours, keep it warm for crystallization for 1 hour, filter it, and rinse it, and collect 22.3 kg of filter cake and 58.5 L of filtrate respectively;

[0036] (7) taking 58.5 L of the filtrate in step (6), after heat concentration treatment, 36.1 L of a concentrated solution having a solid content of 45 wt % was obtained, the solution was cooled to 40 ° C. for 4 h, filtered, rinsed, and the collected 10.4 kg filter cake was combined with the filter cake in step (6), and dried to obtain an inositol product, and the collected filtrate was used as a feed additive component or an organic fertilizer component;

[0037] (8) The second permeate in step (4) was concentrated using a reverse osmosis membrane (operating temperature 30° C., operating pressure 4.5 MPa) to obtain 1282 L of concentrated solution containing potassium chloride as a phytic acid decomposing agent.

[0038] Example 2

[0039] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid decomposing agent as by-products comprises the following steps:

[0040] (1) Add a neutralizer (calcium hydroxide) to the collected 1000 L potassium dihydrogen phosphate mother liquor (inositol concentration 35 g / L, inorganic phosphorus concentration 149 g / L, potassium ion concentration 108 g / L), stir, adjust the pH of the liquid to 7.5, control the reaction temperature at 40° C., and react for 1.5 h to obtain 1091 L of the liquid for use;

[0041] (2) 1091 L of the feed liquid in step (1) was filtered using a plate and frame filter with a filter cloth pore size of 400 mesh, 793 L of the collected filtrate was reserved, and 381.1 kg of the collected filter cake was dried to obtain a tricalcium phosphate product;

[0042] (3) 793 L of the filtrate in step (2) was taken and treated with a hollow fiber membrane (the operating pressure was controlled at 0.45 MPa, the operating temperature was 37° C., and the permeate was backflushed for 35 s every 25 min, and the filtration was stopped when the filtration volume was 6% of the original volume; the material of the hollow fiber membrane was polyvinylidene fluoride, and the membrane model of the hollow fiber membrane was NF-70), and 48 L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 747 L of the first permeate were collected respectively;

[0043] (4) taking 747 L of the first permeate in step (3), adjusting the pH to 4.5 with 3 wt % HCl, treating with a nanofiltration membrane with a molecular weight cutoff of 200 Da, and collecting 212 L of the second retentate and 3068 L of the second permeate respectively;

[0044] (5) taking 212 L of the second retentate in step (4), continuing to concentrate to obtain a concentrate having a solid content of 50 wt% and a temperature of 95° C., adding 1.1 kg of activated carbon at a ratio of 100:1.5 of the concentrate volume to the activated carbon weight, stirring, filtering, and obtaining 77.1 L of decolorized liquid for standby use;

[0045] (6) Take 77.1 L of the decolorized liquid in step (5), cool it to 30°C within 4.5 hours, keep it warm for 1 hour for crystallization, filter it, and rinse it, and collect 23.1 kg of filter cake and 55.2 L of filtrate respectively;

[0046] (7) taking 55.2 L of filtrate in step (6), obtaining 30.2 L of concentrated solution having a solid content of 50 wt % after heat concentration treatment, cooling to 32 ° C. for 5 h, filtering, and leaching, the collected 8.5 kg filter cake and the filter cake in step (6) are merged and dried to obtain an inositol product, and the collected filtrate is used as a feed additive component or an organic fertilizer component;

[0047] (8) The second permeate in step (4) was concentrated using a reverse osmosis membrane (operating temperature 40° C., operating pressure 5 MPa) to obtain 2483 L of concentrated solution containing potassium chloride as a phytic acid decomposing agent.

[0048] Example 3

[0049] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid decomposing agent as by-products comprises the following steps:

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

[0051] (2) taking 1095 L of the feed liquid in step (1), filtering it using a plate and frame filter with a filter cloth pore size of 400 mesh, collecting 788 L of filtrate for later use, and collecting 392.7 kg of filter cake, and drying to obtain a tricalcium phosphate product;

[0052] (3) taking 788 L of the filtrate in step (2), and treating it with a hollow fiber membrane (controlling the operating pressure at 0.5 MPa, the operating temperature at 45° C., and back-flushing the permeate for 45 s every 30 min, and stopping the filtration when the filtration volume reaches 7% of the original volume; the material of the hollow fiber membrane is polyvinylidene fluoride, and the membrane model of the hollow fiber membrane is NF-80), and collecting 55 L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 735 L of the first permeate;

[0053] (4) taking 735 L of the first permeate in step (3), adjusting the pH to 5 with 4 wt % HCl, treating with a nanofiltration membrane with a molecular weight cutoff of 150 Da, and collecting 199 L of the second retentate and 2400 L of the second permeate respectively;

[0054] (5) 199 L of the second retentate in step (4) was taken and further concentrated to obtain a concentrated solution with a solid content of 55 wt% and a temperature of 95° C. 1.36 kg of activated carbon was added at a ratio of 100:2 of the volume of the concentrated solution to the weight of the activated carbon. The mixture was stirred and filtered to obtain 68.9 L of a decolorized liquid for later use;

[0055] (6) Take 68.9 L of the decolorized liquid in step (5), cool it to 35°C within 5 hours, keep it warm for crystallization for 1 hour, filter, and rinse, and collect 25.1 kg of filter cake and 45.5 L of filtrate respectively;

[0056] (7) taking 45.5 L of the filtrate in step (6), obtaining 26.3 L of a concentrated solution having a solid content of 50 wt % after heat concentration treatment, cooling to 35 ° C. for 6 h, filtering, and leaching, the collected 8.0 kg filter cake and the filter cake in step (6) are combined and dried to obtain an inositol product, and the collected filtrate is used as a feed additive component or an organic fertilizer component;

[0057] (8) The second permeate in step (4) was concentrated using a reverse osmosis membrane (operating temperature 50° C., operating pressure 5.3 MPa) to obtain 1819 L of concentrated solution containing potassium chloride as a phytic acid decomposing agent.

[0058] Example 4

[0059] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid decomposing agent as by-products comprises the following steps:

[0060] (1) Add a neutralizer (calcium hydroxide) to the collected 1000 L potassium dihydrogen phosphate mother liquor (inositol concentration 35 g / L, inorganic phosphorus concentration 149 g / L, potassium ion concentration 108 g / L), stir, adjust the pH of the liquid to 8.5, control the reaction temperature at 55° C., and react for 2.5 h to obtain 1096 L of the liquid for use;

[0061] (2) taking 1096 L of the feed liquid in step (1), filtering it using a plate and frame filter with a filter cloth pore size of 400 mesh, collecting 790 L of the filtrate for later use, and collecting 394.2 kg of the filter cake, and drying to obtain a tricalcium phosphate product;

[0062] (3) 790 L of the filtrate in step (2) was taken and treated with a hollow fiber membrane (the operating pressure was controlled at 0.55 MPa, the operating temperature was 52° C., and the permeate was backflushed for 50 s every 35 min of operation, and the filtration was stopped when the filtration volume was 9% of the original volume; the material of the hollow fiber membrane was polyvinylidene fluoride, and the membrane model of the hollow fiber membrane was NF-70), and 71 L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 721 L of the first permeate were collected respectively;

[0063] (4) taking 721 L of the first permeate in step (3), adjusting the pH to 5.5 with 3 wt % HCl, treating with a nanofiltration membrane with a molecular weight cutoff of 200 Da, and collecting 167 L of the second retentate and 3039 L of the second permeate respectively;

[0064] (5) 167 L of the second retentate in step (4) was taken and further concentrated to obtain a concentrated solution with a solid content of 58 wt% and a temperature of 95° C. 1.6 kg of activated carbon was added at a ratio of 100:2.5 of the volume of the concentrated solution to the weight of the activated carbon. The mixture was stirred and filtered to obtain 65.5 L of a decolorized liquid for later use;

[0065] (6) Take 65.5 L of the decolorized liquid in step (5), cool it to 38°C within 5.5 h, keep it warm for 1 h to crystallize, filter, and rinse, and collect 24.6 kg of filter cake and 43.9 L of filtrate respectively;

[0066] (7) taking 43.9 L of the filtrate in step (6), obtaining 22.3 L of a concentrated solution having a solid content of 58 wt % after heat concentration treatment, cooling to 38 ° C. for 7 h, filtering, and elution washing, the collected 7.8 kg filter cake and the filter cake in step (6) are combined and dried to obtain an inositol product, and the collected filtrate is used as a feed additive component or an organic fertilizer component;

[0067] (8) The second permeate in step (4) was concentrated using a reverse osmosis membrane (operating temperature 55° C., operating pressure 5.5 MPa) to obtain 1923 L of concentrated solution containing potassium chloride as a phytic acid decomposing agent.

[0068] Example 5

[0069] A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid decomposing agent as by-products comprises the following steps:

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

[0071] (2) taking 1098 L of the feed liquid in step (1), filtering it using a plate-and-frame filter with a filter cloth aperture of 400 mesh, collecting 791 L of the filtrate for later use, and collecting 395.5 kg of the filter cake, and drying to obtain a tricalcium phosphate product;

[0072] (3) taking 791 L of the filtrate in step (2), and treating it with a hollow fiber membrane (controlling the operating pressure at 0.6 MPa, the operating temperature at 60° C., and back-flushing the permeate for 60 s every 40 min, and stopping the filtration when the volume is 10% of the original volume; the material of the hollow fiber membrane is polyvinylidene fluoride, and the membrane model of the hollow fiber membrane is NF-80), and collecting 79 L of the first retentate (mixed with the next batch of potassium dihydrogen phosphate mother liquor) and 714 L of the first permeate;

[0073] (4) taking 714 L of the first permeate in step (3), adjusting the pH to 6 with 5 wt % HCl, treating with a nanofiltration membrane with a molecular weight cutoff of 100 Da, and collecting 168 L of the second retentate and 2038 L of the second permeate respectively;

[0074] (5) 168 L of the second retentate in step (4) was taken and further concentrated to obtain a concentrated solution with a solid content of 60 wt% and a temperature of 95° C. 1.9 kg of activated carbon was added at a ratio of 100:3 by volume of the concentrated solution to the weight of activated carbon. The mixture was stirred and filtered to obtain 65.7 L of decolorized liquid for later use;

[0075] (6) Take 65.7 L of the decolorized liquid in step (5), cool it to 40°C within 6 hours, keep it warm for crystallization for 1 hour, filter it, and rinse it, and collect 24.2 kg of filter cake and 43.4 L of filtrate respectively;

[0076] (7) taking 43.4 L of the filtrate in step (6), obtaining 20.4 L of a concentrated solution having a solid content of 60 wt % after heat concentration treatment, cooling to 40 ° C. for 8 h, filtering, and leaching, the collected 7.6 kg filter cake and the filter cake in step (6) are combined and dried to obtain an inositol product, and the collected filtrate is used as a feed additive component or an organic fertilizer component;

[0077] (8) The second permeate in step (4) was concentrated using a reverse osmosis membrane (operating temperature 60° C., operating pressure 6.0 MPa) to obtain 1464 L of concentrated solution containing potassium chloride as a phytic acid decomposing agent.

[0078] In order to better prove that the process method of the present invention can obtain high-purity, high-yield, high-yield inositol products, and can also obtain high-yield by-product tricalcium phosphate, and can also obtain a phytic acid decomposing agent, 13 comparative examples are given with reference to Example 3, and the details are shown below.

[0079] Comparative Example 1

[0080] The difference from Example 3 is that in step (1), the pH of the feed solution is adjusted to 6.5, and the remaining operations are the same.

[0081] Comparative Example 2

[0082] The difference from Example 3 is that the temperature in step (1) is controlled to 25° C., and the rest of the operations are the same.

[0083] Comparative Example 3

[0084] The difference from Example 3 is that the operating pressure of the membrane in step (3) is 0.3 MPa, and the rest of the operations are the same.

[0085] Comparative Example 4

[0086] The difference from Example 3 is that the operating temperature of the membrane in step (3) is 20°C, and the rest of the operations are the same.

[0087] Comparative Example 5

[0088] The difference from Example 3 is that the operating temperature of the membrane in step (3) is 70°C, and the rest of the operations are the same.

[0089] Comparative Example 6

[0090] The difference from Example 3 is that the model of the membrane in step (3) is NF-55, and the rest of the operations are the same.

[0091] Comparative Example 7

[0092] The difference from Example 3 is that the model of the membrane in step (3) is NF-85, and the rest of the operations are the same.

[0093] Comparative Example 8

[0094] The difference from Example 3 is that step (4) is missing, and the remaining operations are the same.

[0095] Comparative Example 9

[0096] The difference from Example 3 is that in step (4), the pH is adjusted to 6.5, and the remaining operations are the same.

[0097] Comparative Example 10

[0098] The difference from Example 3 is that the content of the concentrated liquid in step (5) is 40wt%, and the rest of the operations are the same.

[0099] Comparative Example 11

[0100] The difference from Example 3 is that the content of the concentrated liquid in step (5) is 65wt%, and the remaining operations are the same.

[0101] Comparative Example 12

[0102] The difference from Example 3 is that the temperature is lowered to 20° C. in step (6), and the remaining operations are the same.

[0103] Comparative Example 13

[0104] The difference from Example 3 is that the temperature is lowered to 45° C. in step (6), and the remaining operations are the same.

[0105] Table 1

[0106]

[0107]

[0108] It can be found from Table 1 that, by adopting the process method of the present invention, the inositol yield, yield and purity, the tricalcium phosphate yield and the phytic acid decomposing agent yield obtained in Example 3 are significantly higher than those in 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 in the protection scope of the present invention.

Claims

1. A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts, characterized in that: The following steps are involved: (1) adding a neutralizing agent to the collected potassium dihydrogen phosphate mother liquor, stirring, adjusting the pH of the liquid to not less than 7, controlling the reaction temperature and reaction time, and the liquid obtained after the reaction is completed is ready for use; (2) taking the feed liquid described in step (1), filtering and collecting the filtrate for later use, and drying the collected filter cake to obtain a tricalcium phosphate product; (3) taking the filtrate described in step (2), treating it through a hollow fiber membrane, and collecting a first retentate and a first permeate respectively; (4) taking the first permeate in step (3), adjusting the pH to acidic, and then treating it with a nanofiltration membrane to collect a second retentate and a second permeate respectively; (5) taking the second retentate in step (4), further concentrating it, decolorizing it, and filtering it to obtain a decolorized liquid for later use; (6) taking the decolorized liquid in step (5), cooling and crystallizing, filtering, and eluting, and collecting the filter cake and filtrate respectively; (7) taking the filtrate described in step (6), concentrating, cooling crystallization, filtering, rinse, the collected filter cake and the filter cake in step (6) merge, dry to obtain an inositol product, and the collected filtrate is used as a feed additive component or an organic fertilizer component; (8) The second permeate in step (4) is concentrated to obtain a concentrated solution containing potassium chloride as a phytic acid decomposing agent.

2. A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts according to claim 1, characterized in that: The neutralizing agent in step (1) is calcium oxide or calcium hydroxide, the pH of the feed solution is adjusted to 7-9, the reaction temperature is controlled at 30-60° C., and the reaction time is 1-3 h.

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

4. A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts according to claim 1, characterized in that, When hollow fiber membrane treatment is used in step (3), the operating pressure is controlled at 0.4-0.6MPa, the operating temperature is 30-60°C, and the permeate is backflushed for 30-60s every 20-40min of operation, and the filtration is stopped when the filtration volume reaches 5-10% of the original volume; the material of the hollow fiber membrane is polyvinylidene fluoride, and the membrane model of the hollow fiber membrane is NF-60~80.

5. A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts according to claim 1, characterized in that, 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.

6. A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts according to claim 1, characterized in that: The solid content of the concentrated solution in step (5) is 45-60wt%.

7. A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts according to claim 1, characterized in that: In step (6), the decolorized liquid is cooled to 25-40° C. within 4-6 hours and kept warm for crystallization for 1 hour.

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

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

10. A process for recovering inositol from potassium dihydrogen phosphate mother liquor and producing tricalcium phosphate and phytic acid analytical agent as byproducts according to claim 1, characterized in that: The solid content of the concentrated solution containing potassium chloride in step (8) is 8-15wt%.

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