Preparation method of high-purity tricalcium phosphate
Through the two-stage neutralization reaction of wet phosphoric acid and lime milk, the dependence on high-quality raw materials and high production costs in the prior art are solved, and the low-cost and efficient production of high-purity tricalcium phosphate is achieved.
Patent Information
- Application Number
- CN202510188692.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-20
- Publication Date
- 2025-05-23
AI Technical Summary
The existing tricalcium phosphate production methods are limited by high-quality raw materials, with high production costs and complex processes that are difficult to control.
Wet phosphoric acid and lime milk were used to perform two neutralization reactions, and high-purity tricalcium phosphate was prepared by controlling the reaction temperature, pH value and aging time.
The production of high-purity tricalcium phosphate has been achieved, breaking the dependence on high-quality raw materials, reducing production costs, simplifying the process, and improving the stability of product quality.
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Figure CN120024879A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of fine phosphate production, and in particular relates to a method for synthesizing high-purity tricalcium phosphate with a purity above industrial grade. Background Art
[0002] Tricalcium phosphate has been increasingly recognized due to its good biological activity, biocompatibility, biodegradation rate and comprehensive performance, and has become one of the current research hotspots of calcium phosphate salts.
[0003] Tricalcium phosphate is a product with a wide range of applications, mainly due to the increasing demand for it in many fields such as food, medicine, construction, and agriculture. For example, in the food field, tricalcium phosphate is used as an emulsifier and stabilizer, in the pharmaceutical field it can improve the solubility of drugs, in the agricultural field it can be used as a fertilizer additive, soil conditioner, and plant growth promoter, and it is widely used in the construction industry, especially in the ceramic industry, where it can be added as an additive in the production process of ceramics to reduce energy and time consumption, while also improving the physical properties and chemical stability of ceramics, giving them a better service life and corrosion resistance.
[0004] The existing tricalcium phosphate production method mainly involves: reacting a saturated calcium chloride solution with food-grade trisodium phosphate in the presence of excess ammonia to generate insoluble tricalcium phosphate, which is then filtered, washed, and dried to obtain the finished product. Alternatively, food phosphoric acid and refined calcium hydroxide may be reacted, which are then filtered, washed, and dried to obtain the finished product, but these methods are limited by high-quality raw materials and have high production costs. Summary of the invention
[0005] The purpose of the present invention is to break the limitation of high-quality raw materials and provide a method for preparing high-purity tricalcium phosphate with low production cost, simple production conditions and easy-to-control production process.
[0006] The technical solution adopted by the present invention is as follows: A method for preparing high-purity tricalcium phosphate, the method steps are as follows: S1. Raise the temperature of the dilute phosphoric acid solution to 40-60°C, add lime milk and auxiliary materials (arsenic removal agent) under stirring conditions to react, control the reaction pH to 2.2-2.5, and prepare a reaction slurry; the auxiliary material is sodium sulfide or phosphorus pentasulfide, and the amount of the auxiliary material added is 3-5 times the molar mass of arsenic in the dilute phosphoric acid solution; S2. The reaction slurry prepared in step S1 is further aged, filtered after aging, to obtain a neutralization solution and fertilizer-grade calcium hydrogen phosphate; S3. The first stage neutralization solution obtained in step S2 is further added to the lime milk for reaction, the reaction temperature is controlled at 65-80°C, and then aged to thicken to obtain a second stage neutralization solution and a second stage neutralization thick slurry; the second stage neutralization solution is filtered to obtain a clarified second stage neutralization solution; S4. The temperature of the clarified second-stage neutralization liquid is raised to 65-80°C, and added to the lime milk under stirring conditions, and the reaction pH is controlled to 6.5-7.5 to obtain a secondary reaction slurry; S5. The secondary reaction slurry obtained in step S4 is further aged, and filtered after aging to obtain tricalcium phosphate and a mother liquor; S6. The tricalcium phosphate obtained in step S7 is washed and dried to obtain a tricalcium phosphate product with a purity of more than 99%.
[0007] Further, in step S1, the P 2 O 5 The mass concentration of lime is 8-12%; the mass concentration of CaO in lime milk is 5-10%, and the reaction pH is controlled at 2.2-2.5.
[0008] Furthermore, in step S2, the aging time of the reaction slurry is 20-50 min.
[0009] Furthermore, in step S3, the pH of the reaction between the neutralization solution and the lime milk is controlled to be 2.8-3.3, and the aging time for aging to thicken is 20-50 minutes.
[0010] Furthermore, in step S5, the aging time of the secondary reaction slurry is 24-72 hours.
[0011] Furthermore, in step S6, the tricalcium phosphate is washed three times with water, the amount of water added is 0.5 times the mass of the tricalcium phosphate filter cake, the drying temperature is 100-120° C., and the drying time is 2-4 hours.
[0012] Furthermore, the two-stage neutralization thick slurry obtained in step S3 is used to produce feed-grade calcium hydrogen phosphate.
[0013] The beneficial effects of the present invention are as follows: The present invention uses wet-process phosphoric acid to replace trisodium phosphate for food and phosphorus source in food phosphoric acid and reacts with lime milk to generate tricalcium phosphate, and obtains high-purity tricalcium phosphate with high product quality by controlling conditions such as aging time, reaction temperature and pH, and the raw material source is wide and the price is relatively low, and the purity of the obtained tricalcium phosphate is greater than 99%. The method of the present invention breaks the limitation of the existing technical method on high quality of raw materials, has low production cost, simple production conditions and easy control of the process, and the obtained product has stable quality and good development prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a schematic diagram of the production process of the present invention. DETAILED DESCRIPTION
[0015] The content of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.
[0016] A method for preparing high-purity tricalcium phosphate, wherein the phosphorus source in the prior art method is replaced by the two-stage neutralization solution of monocalcium phosphate, and the product is obtained by aging and thickening the product with lime milk, filtering, washing and drying. Specific embodiments are as follows. Example 1
[0017] like Figure 1 As shown, a method for preparing high-purity tricalcium phosphate, the method steps are as follows: S1. Add water to wet-process phosphoric acid for dilution to obtain P 2 O 5 The diluted phosphoric acid with a concentration of 11.12% was transported to the first neutralization tank by a delivery pump and heated to 55°C. Under mechanical stirring conditions, lime milk with a CaO concentration of 5.5% and a dearsenicizing agent (Na 2 S), Na 2 The amount of S added was 5 times the molar ratio of As in the dilute phosphoric acid, and the reaction temperature was controlled at about 55° C. and the reaction pH was controlled at 2.35 to prepare a reaction slurry.
[0018] S2. The reaction slurry prepared in step S1 is further aged for 30 minutes. After the aging is completed, the aged slurry is sent to the filter press through a delivery pump for filtration. The filtrate (first-stage neutralization liquid) is delivered to the second-stage neutralization tank through a delivery pump, and the filter residue (fertilizer-grade calcium hydrogen phosphate) is sent to produce fertilizer-grade calcium hydrogen phosphate.
[0019] S3. Add lime milk to the filtrate of the second-stage neutralization tank while stirring, and control the reaction temperature to 75℃, and the reaction pH to 2.98, and then send it to the thickener for aging and thickening for 30 minutes. The clear liquid (second-stage neutralization liquid) on the thickener is placed in the second-stage neutralization liquid storage tank, and the second-stage neutralization thick slurry at the bottom is directly sent to produce feed-grade calcium hydrogen phosphate. Filter the second-stage neutralization liquid to obtain a clarified second-stage neutralization liquid.
[0020] S4. The clarified second-stage neutralization liquid is heated to 75°C and transported via a delivery pump to a third-stage neutralization tank to which a measured amount of lime milk has been added in advance. The clarified second-stage neutralization liquid is added while stirring, and the reaction temperature is controlled at 75°C and the reaction pH is controlled at 6.85 to obtain a secondary reaction slurry.
[0021] S5. The secondary reaction slurry obtained in step S4 is placed in an aging tank for aging for 24 hours. After aging, the slurry is sent to a filter press through a delivery pump to obtain tricalcium phosphate filter cake and mother liquor.
[0022] S6. The tricalcium phosphate obtained in step S5 is washed three times with water, and the amount of water added for each washing is 0.5 times the mass of the tricalcium phosphate filter cake, the drying temperature is 100 ° C, and the drying time is 4 hours. The obtained tricalcium phosphate product refers to the analysis index of GB1886.332-2021, that is, the purity of the tricalcium phosphate product is 99%, and its P 2 O 5 The mass content of Shear is 45.35%, and the mass content of Ca is 36.45%. Example 2
[0023] A method for preparing high-purity tricalcium phosphate, the method steps are as follows: S1. Add water to wet-process phosphoric acid for dilution to obtain P 2 O 5 The diluted phosphoric acid with a concentration of 8.1% is transported to the first neutralization tank through a delivery pump and heated to 55°C. Under mechanical stirring conditions, lime milk with a CaO concentration of 9.8% and a dearsenicizing agent (Na 2 S), Na 2 The amount of S added is 3 times the molar ratio of As in dilute phosphoric acid, and the reaction temperature is controlled at about 55° C. and the reaction pH is controlled at 2.3 to prepare a reaction slurry.
[0024] S2. The reaction slurry prepared in step S1 is further aged for 30 minutes. After the aging is completed, the aged slurry is sent to the filter press through a delivery pump for filtration. The filtrate (first-stage neutralization liquid) is delivered to the second-stage neutralization tank through a delivery pump, and the filter residue (fertilizer-grade calcium hydrogen phosphate) is sent to produce fertilizer-grade calcium hydrogen phosphate.
[0025] S3. Add lime milk to the filtrate of the second-stage neutralization tank while stirring, and control the reaction temperature to 75℃, and the reaction pH to 2.98, and then send it to the thickener for aging and thickening for 30 minutes. The clear liquid (second-stage neutralization liquid) on the thickener is placed in the second-stage neutralization liquid storage tank, and the second-stage neutralization thick slurry at the bottom is directly sent to produce feed-grade calcium hydrogen phosphate. Filter the second-stage neutralization liquid to obtain a clarified second-stage neutralization liquid.
[0026] S4. The clarified second-stage neutralization liquid is heated to 75°C and transported via a delivery pump to a third-stage neutralization tank into which a measured amount of lime milk has been added in advance. The second-stage neutralization liquid is added while stirring, and the reaction temperature is controlled at 75°C and the reaction pH is controlled at 6.85 to obtain a secondary reaction slurry.
[0027] S5. The secondary reaction slurry obtained in step S4 is placed in an aging tank for aging for 48 hours. After aging, the slurry is sent to a filter press through a delivery pump for filtration to obtain tricalcium phosphate filter cake and mother liquor.
[0028] S6. The tricalcium phosphate obtained in step S5 is washed three times with water and then dried at a drying temperature of 110°C for 1 hour. The obtained tricalcium phosphate product refers to the analysis index of GB1886.332-2021, that is, the purity of the tricalcium phosphate product is 99.2%, and its P 2 O 5 The mass content of Ar is 45.44%, and the mass content of Ca is 36.53%. Example 3
[0029] A method for preparing high-purity tricalcium phosphate, the method steps are as follows: S1.P 2 O 5 The diluted phosphoric acid with a concentration of 8% is transported to the first neutralization tank and heated to 60°C. While stirring, lime milk with a CaO concentration of 9.85% and a dearsenicizing agent (P 2 S 5 ), P 2 S 5 The amount of addition is 3 times the molar ratio of As in dilute phosphoric acid, and the reaction temperature is controlled at 60° C. and the reaction pH is controlled at 2.2 to prepare a reaction slurry.
[0030] S2. The reaction slurry prepared in step S1 is further aged for 20 minutes. After the aging is completed, the aged slurry is sent to a filter press for filtration, and the filtrate (first-stage neutralization liquid) is transported to a second-stage neutralization tank, and the filter residue (fertilizer-grade calcium hydrogen phosphate) is sent to produce fertilizer-grade calcium hydrogen phosphate.
[0031] S3. Add lime milk to the filtrate of the second-stage neutralization tank while stirring, and control the reaction temperature to 80°C, the reaction pH to 2.8, and then age and thicken for 20 minutes. The upper clear liquid (second-stage neutralization liquid) is placed in the second-stage neutralization liquid storage tank, and the lower second-stage neutralization thick slurry is directly sent to produce feed-grade calcium hydrogen phosphate. The second-stage neutralization liquid is filtered to obtain a clear second-stage neutralization liquid.
[0032] S4. The clarified second-stage neutralization liquid is heated to 80°C and transported via a delivery pump to a third-stage neutralization tank into which a measured amount of lime milk has been added in advance. The second-stage neutralization liquid is added while stirring, and the reaction temperature is controlled at 80°C and the reaction pH is controlled at 6.5 to obtain a secondary reaction slurry.
[0033] S5. The secondary reaction slurry obtained in step S4 is placed in an aging tank for aging for 60 hours. After aging, the slurry is sent to a filter press for filtration to obtain tricalcium phosphate filter cake and mother liquor.
[0034] S6. The tricalcium phosphate obtained in step S5 is washed three times with water and then dried at a drying temperature of 120°C for 2 hours. The obtained tricalcium phosphate product refers to the analysis index of GB1886.332-2021, that is, the tricalcium phosphate product with a purity of 99.15%, and its P2 O 5 The mass content of Shear is 45.42%, and the mass content of Ca is 36.48%. Example 4
[0035] A method for preparing high-purity tricalcium phosphate, the method steps are as follows: S1.P 2 O 5 The diluted phosphoric acid with a concentration of 12% is transported to the first neutralization tank and heated to 40°C. While stirring, lime milk with a CaO concentration of 10% and a dearsenicizing agent (P 2 S 5 ), P 2 S 5 The amount of addition is 5 times the molar ratio of As in dilute phosphoric acid, and the reaction temperature is controlled at 40° C. and the reaction pH is controlled at 2.5 to prepare a reaction slurry.
[0036] S2. The reaction slurry prepared in step S1 is further aged for 50 minutes. After the aging is completed, the aged slurry is sent to a filter press for filtration, and the filtrate (first-stage neutralization liquid) is transported to a second-stage neutralization tank, and the filter residue (fertilizer-grade calcium hydrogen phosphate) is sent to produce fertilizer-grade calcium hydrogen phosphate.
[0037] S3. Add lime milk to the filtrate of the second-stage neutralization tank while stirring, and control the reaction temperature to 70°C, the reaction pH to 3.3, and then age and thicken for 50 minutes. The upper clear liquid (second-stage neutralization liquid) is placed in the second-stage neutralization liquid storage tank, and the lower second-stage neutralization thick slurry is directly sent to produce feed-grade calcium hydrogen phosphate. The second-stage neutralization liquid is filtered to obtain a clear second-stage neutralization liquid.
[0038] S4. The clarified second-stage neutralization liquid is heated to 70°C and transported via a delivery pump to a third-stage neutralization tank into which a measured amount of lime milk has been added in advance. The second-stage neutralization liquid is added while stirring, and the reaction temperature is controlled at 70°C and the reaction pH is controlled at 7.5 to obtain a secondary reaction slurry.
[0039] S5. The secondary reaction slurry obtained in step S4 is placed in an aging tank for aging for 72 hours. After aging, the slurry is sent to a filter press for filtration to obtain tricalcium phosphate filter cake and mother liquor.
[0040] S6. The tricalcium phosphate obtained in step S5 is washed three times with water and then dried at a drying temperature of 110°C for 3 hours. The obtained tricalcium phosphate product refers to the analysis index of GB1886.332-2021, that is, a tricalcium phosphate product with a purity of 99.5%. 2 O 5 The mass content of Shear is 45.58%, and the mass content of Ca is 36.56%.
[0041] The invention directly adopts wet-process phosphoric acid and lime milk for two-stage neutralization to obtain a pure monocalcium phosphate solution, the monocalcium phosphate solution is neutralized with lime milk to 6.5-7.5, and tricalcium phosphate is obtained after aging and thickening, filter pressing, washing and drying. The pure monocalcium phosphate solution obtained by two-stage neutralization of wet-process phosphoric acid is used to replace the phosphorus source in food-grade trisodium phosphate and food phosphoric acid to produce tricalcium phosphate, with low production cost and good product quality.
Claims
1. A method for preparing high-purity tricalcium phosphate, characterized in that: The steps are as follows: S1. Raise the temperature of the dilute phosphoric acid solution to 40-60°C, add lime milk and auxiliary materials (arsenic removal agent) under stirring conditions to react, control the reaction pH to 2.2-2.5, and prepare a reaction slurry; the auxiliary material is sodium sulfide or phosphorus pentasulfide, and the amount of the auxiliary material added is 3-5 times the molar mass of arsenic in the dilute phosphoric acid solution; S2. The reaction slurry prepared in step S1 is further aged, filtered after aging, to obtain a neutralization solution and fertilizer-grade calcium hydrogen phosphate; S3. The first stage neutralization solution obtained in step S2 is further added to the lime milk for reaction, the reaction temperature is controlled at 65-80°C, and then aged to thicken to obtain a second stage neutralization solution and a second stage neutralization thick slurry; the second stage neutralization solution is filtered to obtain a clarified second stage neutralization solution; S4. The temperature of the clarified second-stage neutralization liquid is raised to 65-80°C, and added to the lime milk under stirring conditions, and the reaction pH is controlled to 6.5-7.5 to obtain a secondary reaction slurry; S5. The secondary reaction slurry obtained in step S4 is further aged, and filtered after aging to obtain tricalcium phosphate and a mother liquor; S6. The tricalcium phosphate obtained in step S7 is washed and dried to obtain a tricalcium phosphate product with a purity of more than 99%.
2. A method for preparing high-purity tricalcium phosphate as claimed in claim 1, characterized in that: In step S1, the mass concentration of P2O5 in the dilute phosphoric acid is 8-12%; the mass concentration of CaO in the lime milk is 5-10%.
3. A method for preparing high-purity tricalcium phosphate as claimed in claim 1, characterized in that: In step S2, the aging time of the reaction slurry is 20-50 min.
4. A method for preparing high-purity tricalcium phosphate as claimed in claim 1, characterized in that: In step S3, the pH of the reaction between the neutralization solution and the lime milk is controlled to be 2.8-3.3, and the aging time for aging to thicken is 20-50 minutes.
5. A method for preparing high-purity tricalcium phosphate as claimed in claim 1, characterized in that: In step S5, the aging time of the secondary reaction slurry is 24-72 hours.
6. A method for preparing high-purity tricalcium phosphate as claimed in claim 1, characterized in that: In step S6, the tricalcium phosphate is washed three times with water, the amount of water added is 0.5 times the mass of the tricalcium phosphate filter cake, the drying temperature is 100-120° C., and the drying time is 2-4 hours.
7. A method for preparing high-purity tricalcium phosphate as claimed in claim 1, characterized in that: The two-stage neutralization thick slurry obtained in step S3 is used to produce feed-grade calcium hydrogen phosphate.