CN108408706B - Preparation method of food-grade anhydrous disodium hydrogen phosphate - Google Patents
Preparation method of food-grade anhydrous disodium hydrogen phosphate Download PDFInfo
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- CN108408706B CN108408706B CN201810333000.1A CN201810333000A CN108408706B CN 108408706 B CN108408706 B CN 108408706B CN 201810333000 A CN201810333000 A CN 201810333000A CN 108408706 B CN108408706 B CN 108408706B
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- caustic soda
- hydrogen phosphate
- disodium hydrogen
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/30—Alkali metal phosphates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Abstract
The invention relates to a preparation method of food-grade anhydrous disodium hydrogen phosphate, which comprises the following steps: adjusting the temperature and the concentration of the raw material phosphoric acid liquid alkali after filtering; adding phosphoric acid and liquid caustic soda into the neutralization kettle, controlling the feeding speed of the liquid caustic soda, controlling the reaction temperature and the reaction end point after the liquid caustic soda is completely added, and curing. Concentrating the neutralized clear liquid; dehydrating; and drying by adopting a fluidized bed to prepare the food-grade anhydrous disodium hydrogen phosphate. The method effectively ensures the yield and purity of the synthesized product by controlling the processing, neutralizing processes and parameters of the raw materials, and then realizes the steps from concentration to crystallization to one-step drying by a fluidized bed process, thereby solving the problem of preparing the anhydrous disodium hydrogen phosphate by a common two-step method. Effectively saves human resources, saves energy consumption, and effectively improves the yield and stable product quality.
Description
Technical Field
The invention relates to a preparation method of a food additive, in particular to a preparation method of food-grade anhydrous disodium hydrogen phosphate.
Background
Disodium hydrogen phosphate (sodium hydrogen phosphate), molecular formula Na2HPO4Relative molecular mass 141.96. There are anhydrous, dihydrate and dodecahydrate fractions. The dodecahydrate is colorless to white crystal or crystalline powder, can be rapidly weathered into heptahydrate salt in air, is easily soluble in water, and is insoluble in ethanol. The anhydrous substance is white powder, has hygroscopicity, and can gradually become heptahydrate salt in air.
The anhydrous disodium hydrogen phosphate is prepared by using phosphoric acid and caustic soda solution or sodium carbonate solution, and is obtained by concentrating, crystallizing and drying. The method comprises a one-step method and a two-step method, wherein the concentration, crystallization and drying are continuous and uninterrupted, the method is called the one-step method, and the method is called the two-step method by adopting other means for drying after the crystallization is finished. The one-step method has the advantages of simpler flow, more labor and energy saving, more stable product quality, higher energy consumption of the two-step method, higher labor cost and no contribution to large-scale production.
In the prior art, most of the preparation methods of disodium hydrogen phosphate adopt a two-step method, so that the labor input is large, the energy consumption is large, the yield is not high, and the quality is not stable.
Disclosure of Invention
The invention aims to solve the technical problems of high labor input, high energy consumption, low yield, unstable quality and the like in the prior art, and provides a novel preparation method of food-grade anhydrous disodium hydrogen phosphate, which can save energy consumption and effectively improve yield.
The technical problem to be solved by the present invention is achieved by the following technical means. The invention relates to a preparation method of food-grade anhydrous disodium hydrogen phosphate, which is characterized in that phosphoric acid and liquid alkali are used as raw materials, and the preparation method comprises the following specific steps:
(1) preparing raw materials: after filtering, the temperature of the phosphoric acid is adjusted to 45-60 ℃, and the concentration is adjusted to 51-53 DEG Be; filtering the liquid caustic soda, and adjusting the temperature to 45-60 ℃ and the concentration to 30-40 DEG Be;
(2) neutralizing: adding phosphoric acid into a neutralization kettle, stirring, simultaneously opening a liquid caustic soda feed valve, controlling the liquid caustic soda feeding speed to be 0.3-0.4 kg/s, adding liquid caustic soda according to the speed, after the liquid caustic soda is completely added, controlling the reaction temperature to be 80-100 ℃, controlling the pH value of a reaction end point to be 8.3-8.9, closing the feed valve, and curing for 20-60 minutes;
(3) concentration and crystallization: pumping the neutralized clear liquid into a neutralized liquid storage tank through a bag filter, and pumping the neutralized clear liquid into a concentration kettle through a neutralized liquid pump, wherein the concentration temperature is 90-105 ℃;
(4) and (3) dehydrating: starting a centrifugal machine, putting the crystallized material into the centrifugal machine for dehydration, separating crystals from mother liquor, conveying wet materials to a drier, and returning the mother liquor to a mother liquor storage tank;
(5) and (3) drying: the food-grade anhydrous disodium hydrogen phosphate is prepared by drying the mixture at the inlet temperature of the fluidized bed of 120-130 ℃ and the outlet temperature of 70-80 ℃.
The preparation method of the food-grade anhydrous disodium hydrogen phosphate provided by the invention has the further preferable technical scheme that: in the step (1), the mass content of the raw material phosphoric acid is 80-85%, the mass content of arsenic is less than or equal to 0.0002%, and the mass content of sodium hydroxide is 98-99.5%.
The preparation method of the food-grade anhydrous disodium hydrogen phosphate provided by the invention has the further preferable technical scheme that: in the step (1), in the liquid caustic soda, the mass concentration of NaOH is more than or equal to 50 percent, and Cl is added-≤0.004％。
The preparation method of the food-grade anhydrous disodium hydrogen phosphate provided by the invention has the further preferable technical scheme that: in the step (2), controlling the pH value of the reaction end point to be 8.5-8.7, closing the feeding valve, and curing for 30-40 minutes.
The preparation method of the food-grade anhydrous disodium hydrogen phosphate provided by the invention has the further preferable technical scheme that: in the step (3), after the neutralization solution is pumped in each step, the pipeline is cleaned by water to prevent crystallization; when the concentration is completed, the vacuum and the circulating water pump are turned off.
The preparation method of the food-grade anhydrous disodium hydrogen phosphate provided by the invention has the further preferable technical scheme that: in the step (5), the inlet temperature of the fluidized bed is 125 ℃, the outlet temperature is 75 ℃, and the drying loss of the anhydrous disodium hydrogen phosphate is controlled to be less than or equal to 5.0%.
Compared with the prior art, the method has the following beneficial effects: the method effectively ensures the yield and purity of the synthesized product by controlling the processing, neutralizing processes and parameters of the raw materials, and then realizes the steps from concentration to crystallization to one-step drying by a fluidized bed process, thereby solving the problem of preparing the anhydrous disodium hydrogen phosphate by a common two-step method. Effectively saves human resources, saves energy consumption, and effectively improves the yield and stable product quality.
Detailed Description
The following further describes particular embodiments of the present invention to facilitate further understanding of the present invention by those skilled in the art, and does not constitute a limitation to the right thereof.
Embodiment 1, a method for preparing food-grade anhydrous disodium hydrogen phosphate, which uses phosphoric acid and caustic soda liquid as raw materials, comprises the following steps:
(1) preparing raw materials: after filtering the phosphoric acid, adjusting the temperature to 45 ℃ and the concentration to 51 DEG Be; filtering the liquid caustic soda, and adjusting the temperature to 45 ℃ and the concentration to 30 Bee; the mass content of the raw material phosphoric acid is 80 percent, the mass content of arsenic is less than or equal to 0.0002 percent, and the mass content of sodium hydroxide is 98 percent.
(2) Neutralizing: adding phosphoric acid into the neutralization kettle, stirring, simultaneously opening a liquid caustic soda feed valve, controlling the liquid caustic soda feeding speed to be 0.3kg/s, adding liquid caustic soda according to the speed, after the liquid caustic soda is completely added, controlling the reaction temperature to be 80 ℃, controlling the pH value of the reaction end point to be 8.3, closing a feed valve, and curing for 20 minutes;
(3) concentration and crystallization: pumping the neutralized clear liquid into a neutralized liquid storage tank through a bag filter, and pumping the neutralized clear liquid into a concentration kettle through a neutralized liquid pump, wherein the concentration temperature is 90 ℃;
(4) and (3) dehydrating: starting a centrifugal machine, putting the crystallized material into the centrifugal machine for dehydration, separating crystals from mother liquor, conveying wet materials to a drier, and returning the mother liquor to a mother liquor storage tank;
(5) and (3) drying: the food-grade anhydrous disodium hydrogen phosphate is prepared by drying the mixture at the inlet temperature of 120 ℃ and the outlet temperature of 70 ℃ of a fluidized bed.
Embodiment 2, a method for preparing food-grade anhydrous disodium hydrogen phosphate, which uses phosphoric acid and caustic soda liquid as raw materials, comprises the following steps:
(1) preparing raw materials: after filtering the phosphoric acid, adjusting the temperature to 60 ℃ and the concentration to 53 DEG Be; filtering the liquid caustic soda, and adjusting the temperature to 60 ℃ and the concentration to 40 Be; the mass content of the raw material phosphoric acid is 85 percent, the mass content of arsenic is less than or equal to 0.0002 percent, and the mass content of sodium hydroxide is 99.5 percent.
(2) Neutralizing: adding phosphoric acid into the neutralization kettle, stirring, simultaneously opening a liquid caustic soda feed valve, controlling the liquid caustic soda feeding speed to be 0.4kg/s, adding liquid caustic soda according to the speed, after the liquid caustic soda is completely added, controlling the reaction temperature to be 100 ℃, controlling the pH value at the reaction end point to be 8.9, closing the feed valve, and curing for 60 minutes;
(3) concentration and crystallization: pumping the neutralized clear liquid into a neutralized liquid storage tank through a bag filter, and pumping the neutralized clear liquid into a concentration kettle through a neutralized liquid pump, wherein the concentration temperature is 105 ℃;
(4) and (3) dehydrating: starting a centrifugal machine, putting the crystallized material into the centrifugal machine for dehydration, separating crystals from mother liquor, conveying wet materials to a drier, and returning the mother liquor to a mother liquor storage tank;
(5) and (3) drying: the food-grade anhydrous disodium hydrogen phosphate is prepared by drying at the inlet temperature of 130 ℃ and the outlet temperature of 80 ℃ of a fluidized bed.
Embodiment 3, a method for preparing food-grade anhydrous disodium hydrogen phosphate, which uses phosphoric acid and caustic soda liquid as raw materials, comprises the following steps:
(1) preparing raw materials: after filtering the phosphoric acid, adjusting the temperature to 50 ℃ and the concentration to 52 DEG Be; filtering the liquid caustic soda, and adjusting the temperature to 50 ℃ and the concentration to 35 Be; the mass content of the raw material phosphoric acid is 82 percent, the mass content of arsenic is less than or equal to 0.0002 percent, and the mass content of sodium hydroxide is 99 percent.
(2) Neutralizing: adding phosphoric acid into the neutralization kettle, stirring, simultaneously opening a liquid caustic soda feed valve, controlling the liquid caustic soda feeding speed to be 0.35kg/s, adding liquid caustic soda according to the speed, after the liquid caustic soda is completely added, controlling the reaction temperature to be 90 ℃, controlling the pH value at the end point of the reaction to be 8.6, closing the feed valve, and curing for 40 minutes;
(3) concentration and crystallization: pumping the neutralized clear liquid into a neutralized liquid storage tank through a bag filter, and pumping the neutralized clear liquid into a concentration kettle through a neutralized liquid pump, wherein the concentration temperature is 100 ℃;
(4) and (3) dehydrating: starting a centrifugal machine, putting the crystallized material into the centrifugal machine for dehydration, separating crystals from mother liquor, conveying wet materials to a drier, and returning the mother liquor to a mother liquor storage tank;
(5) and (3) drying: the food-grade anhydrous disodium hydrogen phosphate is prepared by drying at the inlet temperature of 125 ℃ and the outlet temperature of 75 ℃ of a fluidized bed.
In the step (1), in the liquid caustic soda, the mass concentration of NaOH is more than or equal to 50 percent, and Cl is added-≤0.004％。
In the step (3), after the neutralization solution is pumped in each step, the pipeline is cleaned by water to prevent crystallization; when the concentration is completed, the vacuum and the circulating water pump are turned off.
The physicochemical indexes of the prepared food-grade anhydrous disodium hydrogen phosphate are as follows: the mass percentage content of the disodium hydrogen phosphate is more than 98 percent (calculated by dry basis), the arsenic content is less than 3mg/kg, the lead content is less than 4mg/kg, the fluorine content is less than 50mg/kg, and the water insoluble substance is less than 0.2 percent.
Claims (1)
1. A preparation method of food-grade anhydrous disodium hydrogen phosphate is characterized in that phosphoric acid and liquid alkali are used as raw materials, and the method comprises the following specific steps:
(1) preparing raw materials: after filtering the phosphoric acid, adjusting the temperature to 50 ℃ and the concentration to 52 DEG Be; filtering the liquid caustic soda, and adjusting the temperature to 50 ℃ and the concentration to 35 Be; the mass content of the raw material phosphoric acid is 82 percent, the mass content of arsenic is less than or equal to 0.0002 percent, and the mass content of sodium hydroxide is 99 percent; in liquid caustic sodaThe mass concentration of NaOH is more than or equal to 50 percent, and Cl is added-≤0.004％；
(2) Neutralizing: adding phosphoric acid into the neutralization kettle, stirring, simultaneously opening a liquid caustic soda feed valve, controlling the liquid caustic soda feeding speed to be 0.35kg/s, adding liquid caustic soda according to the speed, after the liquid caustic soda is completely added, controlling the reaction temperature to be 90 ℃, controlling the pH value at the end point of the reaction to be 8.6, closing the feed valve, and curing for 40 minutes;
(3) concentration and crystallization: pumping the neutralized clear liquid into a neutralized liquid storage tank through a bag filter, and pumping the neutralized clear liquid into a concentration kettle through a neutralized liquid pump, wherein the concentration temperature is 100 ℃; after the neutralization solution is pumped in each step, cleaning the pipeline by water to prevent crystallization; when a large amount of particles are generated during concentration, the vacuum and the circulating water pump are closed;
(4) and (3) dehydrating: starting a centrifugal machine, putting the crystallized material into the centrifugal machine for dehydration, separating crystals from mother liquor, conveying wet materials to a drier, and returning the mother liquor to a mother liquor storage tank;
(5) and (3) drying: the food-grade anhydrous disodium hydrogen phosphate is prepared by drying at the inlet temperature of 125 ℃ and the outlet temperature of 75 ℃ of a fluidized bed.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3421846A (en) * | 1965-06-07 | 1969-01-14 | Hooker Chemical Corp | Production of sodium phosphates |
| CN101891172A (en) * | 2010-07-17 | 2010-11-24 | 天津市化学试剂研究所 | Preparation method for food grade disodium hydrogen phosphate |
| CN101891171A (en) * | 2010-07-17 | 2010-11-24 | 天津市化学试剂研究所 | Method for preparing food-grade anhydrous disodium hydrogen phosphate |
| CN101987727A (en) * | 2009-08-05 | 2011-03-23 | 天津市化学试剂研究所 | Preparation method of pH standard reagent disodium hydrogen phosphate |
| CN102249204A (en) * | 2011-06-15 | 2011-11-23 | 安徽恒星制药有限公司 | Method for preparing dipotassium phosphate |
| CN105174239A (en) * | 2015-09-22 | 2015-12-23 | 贵州开磷集团股份有限公司 | Method for preparing disodium hydrogen phosphate by means of phosphoric acid obtained by wet process |
| CN107662910A (en) * | 2016-07-30 | 2018-02-06 | 湖北永绍科技股份有限公司 | A kind of method for preparing disodium hydrogen phosphate using waste phosphoric acid, useless sodium hydroxide |
-
2018
- 2018-04-13 CN CN201810333000.1A patent/CN108408706B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3421846A (en) * | 1965-06-07 | 1969-01-14 | Hooker Chemical Corp | Production of sodium phosphates |
| CN101987727A (en) * | 2009-08-05 | 2011-03-23 | 天津市化学试剂研究所 | Preparation method of pH standard reagent disodium hydrogen phosphate |
| CN101891172A (en) * | 2010-07-17 | 2010-11-24 | 天津市化学试剂研究所 | Preparation method for food grade disodium hydrogen phosphate |
| CN101891171A (en) * | 2010-07-17 | 2010-11-24 | 天津市化学试剂研究所 | Method for preparing food-grade anhydrous disodium hydrogen phosphate |
| CN102249204A (en) * | 2011-06-15 | 2011-11-23 | 安徽恒星制药有限公司 | Method for preparing dipotassium phosphate |
| CN105174239A (en) * | 2015-09-22 | 2015-12-23 | 贵州开磷集团股份有限公司 | Method for preparing disodium hydrogen phosphate by means of phosphoric acid obtained by wet process |
| CN107662910A (en) * | 2016-07-30 | 2018-02-06 | 湖北永绍科技股份有限公司 | A kind of method for preparing disodium hydrogen phosphate using waste phosphoric acid, useless sodium hydroxide |
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Denomination of invention: Preparation method of food grade anhydrous disodium hydrogen phosphate Effective date of registration: 20221019 Granted publication date: 20211224 Pledgee: Bank of Nanjing Co.,Ltd. Lianyungang Branch Pledgor: JIANGSU RUIFENG PHARMACEUTICAL Co.,Ltd. Registration number: Y2022320000620 |