A method for producing potassium dihydrogen phosphate by using corn soaking water

Abstract

This invention discloses a method for producing potassium dihydrogen phosphate (KH2PO4) using corn soaking water, relating to the field of KH2PO4 production technology. Potassium ions in the corn soaking water are adsorbed by a cation exchange resin column, then eluted with sulfuric acid to obtain an eluent. The eluent is reacted with lime milk, filtered, and the precipitate is collected. The precipitate is hydrolyzed and reacted with the cation exchange resin eluent and a neutralizing agent to remove calcium sulfate, yielding a mixture of KH2PO4 and inositol. This mixture is then separated by simulated moving bed chromatography to obtain an inositol solution and a KH2PO4 solution. The KH2PO4 solution is concentrated, decolorized, crystallized, centrifuged, and dried to finally obtain the finished KH2PO4 product. By recovering and utilizing potassium ions from the corn soaking water, the need for purchasing potassium salts is reduced, significantly lowering production costs. Simultaneously, calcium phosphate is converted into KH2PO4, which has a wider range of applications, increasing economic benefits. Furthermore, it avoids generating difficult-to-treat hazardous waste, making it environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of potassium dihydrogen phosphate production technology, specifically to a method for producing potassium dihydrogen phosphate using corn soaking water. Background Technology

[0002] Potassium dihydrogen phosphate (KH2PO4) is an important chemical product widely used in agriculture, industry, food, and medicine. Industrially, it is used as a buffer and culture medium; in agriculture, it is used as a high-efficiency phosphorus-potassium compound fertilizer, offering numerous benefits such as increased yield and income, improved quality, lodging resistance, pest and disease resistance, and prevention of premature aging; in the food industry, KH2PO4 can be used as a fermentation agent, flavoring agent, and leavening agent; in medicine, a compound potassium dihydrogen phosphate injection, composed of KH2PO4 and KH2PO4, is used as a parenteral nutrition supplement.

[0003] Corn soaking water is a byproduct of wet corn starch production, containing 1-2% phytic acid. A relatively mature process exists for recovering phytic acid from corn soaking water to prepare calcium phytate, followed by hydrolysis, neutralization, filtration, concentration, and crystallization to produce inositol and tricalcium phosphate. Tricalcium phosphate is mainly used as a feed additive. Due to its poor solubility and low bioavailability, its selling price is relatively low; moreover, the production process of tricalcium phosphate usually requires high-temperature incineration to remove organic impurities, which has a significant environmental impact. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method for producing potassium dihydrogen phosphate using corn soaking water, which is low in energy consumption, high in economic benefits, and environmentally friendly, in order to address the shortcomings of the existing technology.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A method for producing potassium dihydrogen phosphate using corn soaking water includes the following steps:

[0007] A: The corn soaking water enters the cation exchange resin column, and the effluent is collected;

[0008] B: The cation exchange resin column is eluted with sulfuric acid solution, and the eluent is collected;

[0009] C: Add lime milk to the effluent, filter to obtain calcium phytate and filtrate;

[0010] D: Add calcium phytate to a hydrolysis reactor and hydrolyze it at 160-180℃ and 0.6-0.8MPa for 10-12 hours to obtain hydrolysate;

[0011] E: Then the eluent and the hydrolysate are mixed, and then a neutralizing agent is added. After the reaction, the reaction solution is obtained.

[0012] F: The reaction solution was filtered to obtain a mixture of potassium dihydrogen phosphate and inositol;

[0013] G: The mixture of potassium dihydrogen phosphate and inositol was separated by simulated moving bed chromatography to obtain inositol solution and potassium dihydrogen phosphate solution;

[0014] H: Potassium dihydrogen phosphate solution is subjected to -0.07 to -0.09 MPa and a temperature of 80-90℃. The solid content of the concentrate is 50-60%wt. Activated carbon is added to the concentrate for decolorization, and the solution is filtered to obtain the decolorized solution.

[0015] I: The decolorizing solution enters the crystallization tank and is cooled and crystallized at 25-35℃ for 8-12 hours. The resulting crystallized solution enters a centrifuge and is centrifuged to obtain wet potassium dihydrogen phosphate. After drying, the wet product is obtained as the finished potassium dihydrogen phosphate.

[0016] The equation for the double displacement reaction is: H₂SO₄ + KHSO₄ + 2Ca(H₂PO₄)₂ + H₃PO₄ + 4KOH → 2CaSO₄↓ + 5KH₂PO₄ + 4H₂O

[0017] Preferably, in step A, the feed flow rate of the corn soaking water is 2-3 BV / h, and the feed amount is 10-15 BV.

[0018] Preferably, in step B, the concentration of the sulfuric acid solution is 10-15% wt, the amount of sulfuric acid solution used is 1.5-3 BV, and the desorption flow rate is 1-2 BV / h.

[0019] Preferably, in step C, lime milk is added until the pH of the system is 6-8.

[0020] The filtrate in step C is used to produce corn gluten meal, and the filter residue in step F is gypsum, a byproduct.

[0021] In step E, the molar ratio of calcium ions in the hydrolysate to sulfate ions in the reaction solution is 1:1 to 1.1.

[0022] The neutralizing agent in step E is potassium hydroxide or potassium carbonate, the reaction temperature is 50-70℃, the reaction time is 3-5h, and the final pH of the reaction is 4-5.

[0023] In step H, the amount of activated carbon used is 1-2% wt of the concentrated solution, the decolorization temperature is 70-80℃, and the time is 1-2h.

[0024] In step G, the inositol solution is concentrated to a solid content of 40-50%wt at -0.07 to -0.09 MPa and 85-95℃ to obtain a concentrated solution. The concentrated solution is then fed into a crude crystallization tank and cooled and crystallized at 25-35℃ for 8-10 hours. The resulting crystallized liquid is then fed into a centrifuge and centrifuged to obtain crude inositol and crude mother liquor.

[0025] Crude inositol is added to a dissolving and decolorizing tank, purified water is added and heated to dissolve, then activated carbon is added for decolorization, and the decolorized solution is filtered. The decolorized solution is then introduced into a crystallization tank and cooled and crystallized at 25-35℃ for 8-10 hours. The resulting crystallized solution is then introduced into a centrifuge and centrifuged to obtain wet inositol and recrystallization mother liquor. The wet inositol is dried to obtain the finished inositol product.

[0026] The crude mother liquor is returned to the simulated moving bed chromatography, and the recrystallization mother liquor is returned to the concentration process.

[0027] The ratio of crude inositol to purified water is 1:1.5-2 w / w;

[0028] The amount of activated carbon used is 2-3% wt of the concentrated solution, the decolorization temperature is 85-90℃, and the time is 0.5-1h.

[0029] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. Corn soaking water contains abundant potassium ions, approximately 5 kg per cubic meter. A cation exchange resin column can efficiently adsorb the potassium ions in the corn soaking water. Then, sulfuric acid solution is used to precipitate the cation exchange resin column, and the obtained potassium salt can be used as a raw material for the production of potassium dihydrogen phosphate, reducing the need to purchase potassium salt externally and greatly reducing production costs.

[0031] 2. The hydrolysis products of calcium phytate mainly contain calcium dihydrogen phosphate, phosphoric acid, inositol, etc. They undergo a metathesis reaction with potassium salts and neutralizing agents in the ion exchange resin column eluent to generate calcium sulfate precipitate and potassium dihydrogen phosphate. Calcium sulfate has extremely low solubility and is removed by filtration to obtain a solution containing potassium dihydrogen phosphate and inositol. The calcium sulfate can be used to produce by-product gypsum, which increases economic benefits.

[0032] 3. The filtrate obtained by reacting the effluent from the cation exchange resin column with lime milk can be used to produce corn gluten meal, further improving the economic efficiency of the process.

[0033] 4. This process effectively recovers potassium and phosphorus resources collected from corn soaking water, increases the value of phosphorus resource products, and enhances economic benefits.

[0034] 5. In this process, the mother liquor from each centrifugation can be recycled, which improves the product yield.

[0035] 6. This process does not generate any hazardous waste that is difficult to treat, which greatly reduces the cost of hazardous waste treatment and is environmentally friendly. Attached Figure Description

[0036] Figure 1 This is a liquid chromatogram of the inositol product in Example 2 of the present invention. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to the embodiments.

[0038] Example 1

[0039] A method for producing potassium dihydrogen phosphate using corn soaking water includes the following steps:

[0040] A: 1000L of corn soaking water (phytic acid content 1.2%wt, potassium content 0.25%wt) is fed into the cation exchange resin column at a flow rate of 2BV / h, with a feed rate of 10BV, and 1000L of effluent is collected.

[0041] B: A 10% wt sulfuric acid solution was introduced into the cation exchange resin column at a flow rate of 1 BV / h for elution, and 150 L of elution solution was collected, of which 1.5 BV of sulfuric acid solution was used.

[0042] C: Add lime milk to the effluent until the pH of the system is 6. After filtration, 32.5 kg of calcium phytate and 1000 L of filtrate are obtained. The filtrate is used to produce corn gluten meal.

[0043] D: Add calcium phytate to a hydrolysis reactor and hydrolyze it at 160℃ and 0.6MPa for 10 hours to obtain 60L of hydrolysate;

[0044] E: Then the eluent and the hydrolysate are mixed, and the molar ratio of calcium ions in the hydrolysate to sulfate ions in the reaction solution is controlled to be 1:1. Then 2.3 kg of potassium hydroxide is added, and the reaction is carried out at 50℃ for 3 h. The final pH of the reaction is 4, and the reaction solution is obtained.

[0045] F: The reaction solution was filtered to obtain 200L of a mixture of potassium dihydrogen phosphate and inositol and 28.5kg of filter residue, of which the filter residue was gypsum, a by-product, which was sold externally;

[0046] G: The mixture of potassium dihydrogen phosphate and inositol was separated by simulated moving bed chromatography to obtain 300 L of inositol solution and 460 L of potassium dihydrogen phosphate solution;

[0047] H: Potassium dihydrogen phosphate solution was subjected to -0.07 MPa and 80℃, and the solid content of the concentrate was 50% wt. Activated carbon accounting for 1% wt of the concentrate was added to the concentrate, and the solution was decolorized at 70℃ for 1 h. After filtration, 21 L of decolorized solution was obtained.

[0048] I: The decolorizing solution enters the crystallization tank and is cooled and crystallized at 25°C for 8 hours. The resulting crystallized solution enters a centrifuge and is centrifuged to obtain wet potassium dihydrogen phosphate. After drying, 11.1 kg of finished potassium dihydrogen phosphate is obtained, with a yield of 75% and a purity of 98.8% (HG / T 2321-2016 "Fertilizer Grade Potassium Dihydrogen Phosphate").

[0049] J: The inositol solution was concentrated to a solid content of 40% wt at -0.07 MPa and 85°C to obtain a concentrated solution; the concentrated solution was fed into a crude crystallizer and cooled and crystallized at 25°C for 8 hours. The resulting crystallized liquid was fed into a centrifuge and centrifuged to obtain 2.7 kg of crude inositol and 8 L of crude mother liquor. The crude mother liquor was returned to the simulated moving bed chromatography.

[0050] Crude inositol was added to a dissolving and decolorizing tank, purified water was added, and the mixture was heated to dissolve. The ratio of crude inositol to purified water was 1:1.5 w / w. Then, activated carbon (2% wt) of the concentrate was added, and the mixture was decolorized at 85°C for 0.5 h. The decolorized solution was filtered to obtain 5.5 L of decolorized solution. The decolorized solution was then fed into a crystallization tank and cooled to crystallize at 25°C for 8 h. The resulting crystallized solution was centrifuged to obtain 2.2 kg of wet inositol and 5 L of recrystallization mother liquor. The recrystallization mother liquor was returned to the concentration process. After drying, the wet inositol yielded 2.1 kg of finished inositol product, with a yield of 65% and a purity of 99.7%.

[0051] Example 2

[0052] A method for producing potassium dihydrogen phosphate using corn soaking water includes the following steps:

[0053] A: 1000L of corn soaking water (phytic acid content 1.2%wt, potassium content 0.25%wt) is fed into the cation exchange resin column at a flow rate of 2.5BV / h, with a feed rate of 12BV, and 1000L of effluent is collected.

[0054] B: A 12% wt sulfuric acid solution was introduced into a cation exchange resin column at a flow rate of 1.5 BV / h for elution, and 200 L of elution solution was collected, of which 2.5 BV of sulfuric acid solution was used.

[0055] C: Add lime milk to the effluent until the pH of the system is 7. After filtration, 34 kg of calcium phytate and 1000 L of filtrate are obtained. The filtrate is used to produce corn gluten meal.

[0056] D: Calcium phytate was added to a hydrolysis reactor and hydrolyzed at 170℃ and 0.7MPa for 11 hours to obtain 62L of hydrolysate.

[0057] E: Then the eluent and hydrolysate are mixed, and the molar ratio of calcium ions in the hydrolysate to sulfate ions in the reaction solution is controlled to be 1:1.05. Then 3 kg of potassium carbonate is added, and the reaction is carried out at 60℃ for 4 h. The final pH of the reaction is 4.5, and the reaction solution is obtained.

[0058] F: The reaction solution was filtered to obtain 255L of a mixture of potassium dihydrogen phosphate and inositol and 29kg of filter residue, of which the filter residue was gypsum, a by-product, which was sold externally;

[0059] G: The mixture of potassium dihydrogen phosphate and inositol was separated by simulated moving bed chromatography to obtain 400 L of inositol solution and 600 L of potassium dihydrogen phosphate solution;

[0060] H: Potassium dihydrogen phosphate solution was subjected to a pressure of -0.08 MPa and a temperature of 85°C. The solid content of the concentrate was 55% wt. Activated carbon (1.5% wt) was added to the concentrate, and the solution was decolorized at 75°C for 1.5 h. After filtration, 19.5 L of decolorized solution was obtained.

[0061] I: The decolorizing solution enters the crystallization tank and is cooled and crystallized at 30°C for 10 hours. The resulting crystallized solution enters a centrifuge and is centrifuged to obtain wet potassium dihydrogen phosphate. After drying, 11.8 kg of finished potassium dihydrogen phosphate is obtained, with a yield of 79.7% and a purity of 99.2% (HG / T 2321-2016 "Fertilizer Grade Potassium Dihydrogen Phosphate").

[0062] J: The inositol solution was concentrated to a solid content of 45%wt at -0.08MPa and 90℃ to obtain a concentrated solution; the concentrated solution was fed into a crude crystallizer and cooled and crystallized at 30℃ for 9h; the resulting crystallized liquid was fed into a centrifuge and centrifuged to obtain 2.8kg of crude inositol and 7L of crude mother liquor; the crude mother liquor was returned to the simulated moving bed chromatography.

[0063] Crude inositol was added to a dissolving and decolorizing tank, purified water was added, and the mixture was heated to dissolve. The ratio of crude inositol to purified water was 1:1.8 w / w. Then, activated carbon (2.5% wt) of the concentrate was added, and the mixture was decolorized at 88°C for 0.8 h. The decolorized solution was filtered to obtain 6 L of decolorized solution. The decolorized solution was then fed into a crystallization tank and cooled to crystallize at 30°C for 9 h. The resulting crystallized solution was centrifuged to obtain 2.3 kg of wet inositol and 5.5 L of recrystallization mother liquor. The recrystallization mother liquor was returned to the concentration process. After drying, the wet inositol yielded 2.2 kg of finished inositol product, with a yield of 68.1% and a purity of 99.8%.

[0064] Example 3

[0065] A method for producing potassium dihydrogen phosphate using corn soaking water includes the following steps:

[0066] A: 1000L of corn soaking water (phytic acid content 1.2%wt, potassium content 0.25%wt) is fed into the cation exchange resin column at a flow rate of 3BV / h, with a feed rate of 15BV, and 1000L of effluent is collected.

[0067] B: A 15% wt sulfuric acid solution was introduced into a cation exchange resin column at a flow rate of 2 BV / h for elution, and 200 L of elution solution was collected, of which 3 BV of sulfuric acid solution was used.

[0068] C: Add lime milk to the effluent until the pH of the system is 8. After filtration, 34.5 kg of calcium phytate and 1000 L of filtrate are obtained. The filtrate is used to produce corn gluten meal.

[0069] D: Calcium phytate was added to a hydrolysis reactor and hydrolyzed at 180℃ and 0.8MPa for 12 hours to obtain 63L of hydrolysate;

[0070] E: Then the eluent and the hydrolysate are mixed, and the molar ratio of calcium ions in the hydrolysate to sulfate ions in the reaction solution is controlled to be 1:1.1. Then 2.35 kg of potassium hydroxide is added, and the reaction is carried out at 70℃ for 5 h. The final pH of the reaction is 5, and the reaction solution is obtained.

[0071] F: The reaction solution was filtered to obtain 260L of a mixture of potassium dihydrogen phosphate and inositol and 29.5kg of filter residue, of which the filter residue was gypsum, a by-product, which was sold externally;

[0072] G: The mixture of potassium dihydrogen phosphate and inositol was separated by simulated moving bed chromatography to obtain 400 L of inositol solution and 600 L of potassium dihydrogen phosphate solution;

[0073] H: Potassium dihydrogen phosphate solution was subjected to -0.09 MPa and 90℃, and the solid content of the concentrate was 60% wt. Activated carbon accounting for 2% wt of the concentrate was added to the concentrate, and the solution was decolorized at 80℃ for 2 hours. 18L of decolorized solution was obtained by filtration.

[0074] I: The decolorizing solution enters the crystallization tank and is cooled and crystallized at 35°C for 12 hours. The resulting crystallized solution enters a centrifuge and is centrifuged to obtain wet potassium dihydrogen phosphate. After drying, 11.3 kg of finished potassium dihydrogen phosphate is obtained, with a yield of 76.4% and a purity of 98.5% (HG / T 2321-2016 "Fertilizer Grade Potassium Dihydrogen Phosphate").

[0075] J: The inositol solution was concentrated to a solid content of 50% wt at -0.09 MPa and 95°C to obtain a concentrated solution; the concentrated solution was fed into a crude crystallizer and cooled to crystallize at 35°C for 10 hours. The resulting crystallized liquid was fed into a centrifuge and centrifuged to obtain 2.75 kg of crude inositol and 6.5 L of crude mother liquor. The crude mother liquor was returned to the simulated moving bed chromatography.

[0076] Crude inositol was added to a dissolving and decolorizing tank, purified water was added, and the mixture was heated to dissolve. The ratio of crude inositol to purified water was 1:2 w / w. Then, activated carbon (3% wt) of the concentrate was added, and the mixture was decolorized at 90°C for 1 hour. The decolorized solution was filtered to obtain 7 L of decolorized solution. The decolorized solution was then fed into a crystallization tank and cooled to crystallize at 35°C for 10 hours. The resulting crystallized solution was centrifuged to obtain 2.2 kg of wet inositol and 6.5 L of recrystallization mother liquor. The recrystallization mother liquor was returned to the concentration process. After drying, the wet inositol yielded 2.08 kg of finished inositol, with a yield of 64.4% and a purity of 99.5%.

[0077] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for producing potassium dihydrogen phosphate using corn soaking water, characterized in that... Includes the following steps: A: The corn soaking water enters the cation exchange resin column, and the effluent is collected; B: The cation exchange resin column is eluted with sulfuric acid solution, and the eluent is collected; C: Add lime milk to the effluent, filter to obtain calcium phytate and filtrate; D: Add calcium phytate to a hydrolysis reactor and hydrolyze it at 160-180℃ and 0.6-0.8MPa for 10-12 hours to obtain hydrolysate; E: Then the eluent and the hydrolysate are mixed, and then a neutralizing agent is added. After the reaction, the reaction solution is obtained. F: The reaction solution was filtered to obtain a mixture of potassium dihydrogen phosphate and inositol; G: The mixture of potassium dihydrogen phosphate and inositol was separated by simulated moving bed chromatography to obtain inositol solution and potassium dihydrogen phosphate solution; H: Potassium dihydrogen phosphate solution is subjected to -0.07 to -0.09 MPa and a temperature of 80-90℃. The solid content of the concentrate is 50-60%wt. Activated carbon is added to the concentrate for decolorization, and the solution is filtered to obtain the decolorized solution. I: The decolorizing solution enters the crystallization tank and is cooled and crystallized at 25-35℃ for 8-12 hours. The resulting crystallized solution enters a centrifuge and is centrifuged to obtain wet potassium dihydrogen phosphate. After drying, the wet product is obtained as the finished potassium dihydrogen phosphate.

2. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: In step A, the feed flow rate of the corn soaking water is 2-3 BV / h, and the feed amount is 10-15 BV.

3. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: In step B, the concentration of the sulfuric acid solution is 10-15% wt, the amount of sulfuric acid solution used is 1.5-3 BV, and the desorption flow rate is 1-2 BV / h.

4. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: In step C, lime milk is added until the pH of the system is 6-8.

5. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: The filtrate in step C is used to produce corn gluten meal, and the filter residue in step F is gypsum, a byproduct.

6. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: In step E, the molar ratio of calcium ions in the hydrolysate to sulfate ions in the reaction solution is 1:1 to 1.

1.

7. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: The neutralizing agent in step E is potassium hydroxide or potassium carbonate, the reaction temperature is 50-70℃, the reaction time is 3-5h, and the final pH of the reaction is 4-5.

8. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: In step H, the amount of activated carbon used is 1-2% wt of the concentrated solution, the decolorization temperature is 70-80℃, and the time is 1-2h.

9. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 1, characterized in that: In step G, the inositol solution is concentrated to a solid content of 40-50%wt at -0.07 to -0.09 MPa and 85-95℃ to obtain a concentrated solution. The concentrated solution is then fed into a crude crystallization tank and cooled and crystallized at 25-35℃ for 8-10 hours. The resulting crystallized liquid is then fed into a centrifuge and centrifuged to obtain crude inositol and crude mother liquor. Crude inositol is added to a dissolving and decolorizing tank, purified water is added and heated to dissolve, then activated carbon is added for decolorization, and the decolorized solution is filtered. The decolorized solution is then introduced into a crystallization tank and cooled and crystallized at 25-35℃ for 8-10 hours. The resulting crystallized solution is then introduced into a centrifuge and centrifuged to obtain wet inositol and recrystallization mother liquor. The wet inositol is dried to obtain the finished inositol product.

10. The method for producing potassium dihydrogen phosphate using corn soaking water as described in claim 9, characterized in that: The crude mother liquor is returned to the simulated moving bed chromatography, and the recrystallization mother liquor is returned to the concentration process. The ratio of crude inositol to purified water is 1:1.5-2 w / w; The amount of activated carbon used is 2-3% wt of the concentrated solution, the decolorization temperature is 85-90℃, and the time is 0.5-1h.

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