CN110817826A - Method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid - Google Patents

Method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid Download PDF

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CN110817826A
CN110817826A CN201810906998.XA CN201810906998A CN110817826A CN 110817826 A CN110817826 A CN 110817826A CN 201810906998 A CN201810906998 A CN 201810906998A CN 110817826 A CN110817826 A CN 110817826A
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dihydrogen phosphate
sodium dihydrogen
phosphoric acid
wet
solution
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吴正奇
许琦
徐歆
李摇摇
姚其凤
吴龙
李倩
陈小强
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Hubei University of Technology
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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
    • C01B25/301—Preparation from liquid orthophosphoric acid or from an acid solution or suspension of orthophosphates
    • A—HUMAN NECESSITIES
    • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
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    • C01B25/00—Phosphorus; Compounds thereof
    • C01B25/16—Oxyacids of phosphorus; Salts thereof
    • C01B25/18—Phosphoric acid
    • C01B25/234—Purification; Stabilisation; Concentration
    • C01B25/237—Selective elimination of impurities
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    • C01B25/2375—Fluoride or fluosilicate anion
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    • 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
    • C01B25/18—Phosphoric acid
    • C01B25/234—Purification; Stabilisation; Concentration
    • C01B25/237—Selective elimination of impurities
    • C01B25/2372—Anionic impurities, e.g. silica or boron compounds
    • C01B25/2377—Sulfate
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    • 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
    • C01B25/18—Phosphoric acid
    • C01B25/234—Purification; Stabilisation; Concentration
    • C01B25/237—Selective elimination of impurities
    • C01B25/238—Cationic impurities, e.g. arsenic compounds
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    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
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    • C01P2006/80—Compositional purity

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Abstract

A process for preparing food-class sodium dihydrogen phosphate from industrial wet-purified phosphoric acid includes such steps as diluting ⑴ with water, adding pure water to acid-proof container, stirring, diluting, neutralizing ⑵, adding defluorinating agent and sodium hydroxide, stirring, membrane filtering to obtain the neutralized liquid, oxidizing ⑶ to remove arsenic, slightly alkaline, removing heavy metal and membrane filtering, regulating pH value to slightly alkaline, adding oxidant, heating, cooling, membrane filtering to obtain concentrated liquid, regulating ⑷ pH value, concentrating, regulating pH value with phosphoric acid to obtain concentrated sodium dihydrogen phosphate, cooling ⑸, cooling, crystallizing, cooling, solid-liquid separation to obtain wet sodium dihydrogen phosphate crystal, drying ⑹, drying wet crystal, and drying.

Description

Method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid
Technical Field
The invention relates to the technical field of food additive processing, in particular to a method for preparing food-grade sodium dihydrogen phosphate by industrial wet-process purified phosphoric acid.
Background
Sodium dihydrogen phosphate is an important chemical raw material and is widely applied to industrial departments such as biological fermentation, food, medicine, feed, chemical industry, agriculture and the like. The production method of sodium dihydrogen phosphate mainly includes a neutralization method, an extraction method, an ion exchange method, a double decomposition method, a direct method, a crystallization method, an electrolytic method, and the like, and the main production method is the neutralization method. Phosphoric acid can be classified into wet-process phosphoric acid obtained by acidifying phosphate ore as a raw material and hot-wet-process phosphoric acid obtained by burning pure phosphorus as a raw material according to the source of the phosphoric acid used, and thus sodium dihydrogen phosphate can be classified into hot-process sodium dihydrogen phosphate and wet-process sodium dihydrogen phosphate, wherein the hot-process sodium dihydrogen phosphate has high purity but high cost; according to the purity, the sodium dihydrogen phosphate can be divided into industrial grade, agricultural grade and food grade, wherein the quality standard of the food grade sodium dihydrogen phosphate is highest. Food grade sodium dihydrogen phosphate is typically produced from hot process phosphoric acid via a neutralization process.
The method has the advantages that the method has abundant phosphate ore resources in China, industrial-grade wet-process phosphoric acid and phosphate represented by sodium dihydrogen phosphate are prepared by using the phosphate ore as a raw material, the technology is mature, the cost is low, the product quality is stable, but the impurity content is high, the purity is low, and the requirement of food grade cannot be met. In contrast, the production of phosphoric acid by a thermal process and phosphates represented by sodium dihydrogen phosphate from phosphorus has a high cost, although the technology is mature, the product quality is stable, the purity is high, the impurity content is low, and the requirement of food grade can be met. Therefore, how to utilize abundant phosphate rock resources in China to prepare food-grade phosphoric acid and phosphate represented by sodium dihydrogen phosphate through wet-process phosphoric acid is economically important and urgent in demand.
The core problem to be solved for preparing the food-grade sodium dihydrogen phosphate is prepared from wet-process phosphoric acid (comprising a diluted phosphoric acid semi-finished product with the mass percentage concentration of 20-50% and industrial wet-process purified phosphoric acid with the mass percentage concentrations of 75% and 85%), and comprises the following steps: a. how to separate a small amount of toxic elements such as lead, cadmium, mercury and arsenic in industrial wet-process phosphoric acid to ensure that the product meets the necessary sanitary and safety requirements of food additives; b. how to separate fluorine, iron, calcium and other conventional elements in the industrial wet-process phosphoric acid to ensure that the product reaches the corresponding quality limit index; c. how to separate solid particles, pigment particles and the like in industrial wet-process phosphoric acid to ensure that each index of a product reaches corresponding quality requirements. A large number of researchers at home and abroad research the process technology for preparing food-grade phosphoric acid by refining and purifying wet-process phosphoric acid and preparing food-grade phosphate represented by sodium dihydrogen phosphate by taking the wet-process phosphoric acid as a raw material, and a batch of new processes, new technologies and new achievements are brought forward. For example, Hubei Sanning chemical company develops a new technology which is mainly characterized by extracting wet phosphoric acid from melamine, back-extracting and sodium chloride sodium treatment to obtain food-grade sodium dihydrogen phosphate, and is industrialized. Chinese patent CN201210473441.4 discloses a preparation method of sodium dihydrogen phosphate dodecahydrate; chinese patent CN201510606518.4 discloses a method for preparing sodium dihydrogen phosphate by separating impurities through ammoniation by using wet-process phosphoric acid; chinese patent CN200910102800.3 discloses a method for preparing food-grade sodium dihydrogen phosphate by directly neutralizing and concentrating dilute phosphoric acid; chinese patent CN200910028905.9 discloses a method for co-producing high-purity formic acid and sodium dihydrogen phosphate by the reaction of calcium formate and superphosphoric acid; chinese patent CN86101186.4 discloses a method for preparing sodium dihydrogen phosphate by an "association-displacement" method; US7601319 discloses a process for the production of sodium dihydrogen phosphate.
How to remove toxic and harmful components in industrial wet-process purified phosphoric acid and improve the purity of sodium dihydrogen phosphate with high efficiency and low cost to meet the requirement of food additives on sanitation and safety is a core technical problem of preparing food-grade sodium dihydrogen phosphate by industrial wet-process purified phosphoric acid and is also a fundamental development direction for improving economic benefits in the wet-process phosphoric acid industry.
Disclosure of Invention
Aiming at the defects that the sodium dihydrogen phosphate prepared by industrial wet-process purified phosphoric acid cannot meet the food-grade requirement and the prior art has, the invention aims to provide the preparation method of the food-grade sodium dihydrogen phosphate, which has the advantages of low cost, high purity, sufficient removal of arsenic and heavy metal ions, high sanitary safety, simple and convenient process, high raw material utilization rate, good dissolving performance and mechanized production.
The technical concept of the invention is as follows: the method comprises the steps of utilizing the salting-out effect that sulfate ions and fluoride ions in industrial wet-process purified phosphoric acid are easier to generate barium fluosilicate and barium sulfate precipitates and sodium dihydrogen phosphate under the weak acid condition and simultaneously carrying out defluorination and desulfurization, arsenite can be oxidized into insoluble arsenate, heavy metal ions generate insoluble precipitates under the neutral alkali condition, phosphoric acid is neutralized into sodium dihydrogen phosphate and sodium dihydrogen phosphate with high solubility, the solubility of the sodium dihydrogen phosphate and the sodium dihydrogen phosphate is obviously changed along with the temperature, adding water to the industrial wet-process purified phosphoric acid for dilution, adding a defluorination and debaterization agent and membrane filtration after neutralization and simultaneously carrying out defluorination and desulfurization on filtrate, oxidizing dearsenization and precipitation of the heavy metal ions by using an oxidant under the weak alkaline condition, and obtaining the food-grade sodium dihydrogen phosphate through pH adjustment, concentration, crystallization and drying.
In order to achieve the purpose, the invention adopts the following technical measures:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴ adding water to dilute the phosphoric acid, placing the phosphoric acid into an acid-proof container, adding water with the mass multiple of 0.5-3.1 times of the phosphoric acid under the condition of stirring to obtain a dilute phosphoric acid solution with the mass percentage concentration of 20.7-56.7%, and continuously stirring to obtain the diluted phosphoric acid solution for industrial wet purification.
The industrial wet-process phosphoric acid purification comprises defluorination and desulfurizationAnd wet-process phosphoric acid which is subjected to extraction-back extraction purification treatment and has a mass percentage concentration of 85 percent, wherein the mass of the wet-process phosphoric acid is superior, first-class and qualified products which meet the requirements of HG/T4069 + 2008 industrial wet-process purified phosphoric acid; the water refers to the conductivity of less than 10-3s/m reverse osmosis process pure water, ion exchange process pure water, and distillation condensation process pure water.
Preferably, the industrial wet-process purified phosphoric acid is subjected to defluorination, desulfurization and extraction-back extraction purification treatment, and has a mass percentage concentration of 85%, and the mass of the industrial wet-process purified phosphoric acid is a first-class product and a qualified product which meet the requirements of HG/T4069-2008 industrial wet-process purified phosphoric acid; the water refers to the conductivity of less than 10-3s/m reverse osmosis pure water.
⑵ neutralization reaction and defluorination and desulfurization, namely, putting phosphoric acid diluent ⑴ into an acid-resistant container, adding defluorination and desulfurization agent with the mass fraction of 0.1-1% of the phosphoric acid diluent under the condition of stirring, continuously stirring to ensure that the defluorination and desulfurization agent are fully dissolved and fully reacted with fluoride ions and sulfate radicals in the phosphoric acid diluent purified by the industrial wet method to obtain a reaction mixture, neutralizing the reaction mixture by using sodium hydroxide solution with the mass percentage concentration of 20-50% under the condition of stirring until the pH value is 3.8-4.8, continuously stirring to obtain a neutralization solution, controlling the temperature of the neutralization solution to be 20-60 ℃, and precisely filtering the neutralization solution by using membrane filtration equipment to obtain the precisely filtered neutralization solution for later use.
The defluorination and desulfurization agent is analytically pure or chemically pure barium carbonate and barium bicarbonate; the sodium hydroxide is analytically pure or chemically pure solid sodium hydroxide; the membrane filtration equipment has the membrane material of silicon carbide, the membrane component is a honeycomb briquette type inner tubular membrane, and the sizes of membrane pores are 1, 0.5, 0.1 and 0.04 mu m.
Preferably, the defluorination and desulfurization agent is analytically pure barium carbonate and barium bicarbonate; the sodium hydroxide is analytically pure solid sodium hydroxide; the membrane filtering equipment has the membrane material of silicon carbide, the membrane component is a honeycomb briquette type inner tubular membrane, and the sizes of membrane pores are 0.1 and 0.04 mu m.
⑶ oxidizing and dearsenifying, slightly alkaline heavy metal removing and membrane filtering, under the condition of continuously stirring, adjusting the pH value of the neutralized liquid obtained by the precise filtering with 20-50% by mass of sodium hydroxide solution, adjusting the pH value of the neutralized liquid obtained by ⑵ to 7.0-8.0, adding oxidant with the mass fraction of 0.1-4% of the neutralized liquid, heating the mixture to the temperature required by arsenic oxidation and maintaining the temperature, refluxing, preserving heat and oxidizing for 0.5-8 hours under the condition of stirring, then opening cooling water to reduce the temperature of the mixture to 20-60 ℃, continuously stirring for 0.5-10 hours, and precisely filtering the mixture by membrane filtering equipment to obtain the slightly alkaline heavy metal removing and the oxidized dearsenifying liquid for later use.
The sodium hydroxide is analytically pure or chemically pure solid sodium hydroxide; the oxidant is analytically pure or chemically pure hydrogen peroxide (hydrogen peroxide) and bleaching powder; the temperature required by the arsenic oxidation is 50-100 ℃; the membrane filtration equipment has the membrane material of silicon carbide, the membrane component is a honeycomb briquette type inner tubular membrane, and the sizes of membrane pores are 1, 0.5, 0.1 and 0.04 mu m.
Preferably, the sodium hydroxide is analytically pure solid sodium hydroxide; the oxidant is analytically pure or chemically pure hydrogen peroxide (hydrogen peroxide); the temperature required by the arsenic oxidation is 70-95 ℃; the membrane filtering equipment has the membrane material of silicon carbide, the membrane component is a honeycomb briquette type inner tubular membrane, and the sizes of membrane pores are 0.1 and 0.04 mu m.
⑷ adjusting and concentrating the pH of the ⑶ obtained alkalescent heavy metal and arsenic removal liquid to 3.7-4.6 with phosphoric acid under the condition of continuous stirring to obtain sodium dihydrogen phosphate solution, and concentrating the sodium dihydrogen phosphate solution to 45-65% by mass percentage concentration by a forced circulation vacuum concentration method under the conditions of a vacuum degree of 0.8-0.99 MPa and a temperature of 70-110 ℃ to obtain sodium dihydrogen phosphate concentrated solution for later use.
The purity of the phosphoric acid is analytically pure, chemically pure and food grade, and the mass percentage concentration of the phosphoric acid is 75% and 85%.
Preferably, the phosphoric acid is food-grade phosphoric acid with a mass percentage concentration of 85%.
⑸ cooling crystallization, transferring the concentrated solution of sodium dihydrogen phosphate ⑷ into crystallization equipment, crystallizing sodium dihydrogen phosphate within the temperature range of a metastable zone of the sodium dihydrogen phosphate crystallization for 1-25 hours, cooling to-5-10 ℃ at a cooling rate of 1-10 ℃/hour, continuously crystallizing for 1-50 hours until no crystal is generated, performing solid-liquid separation on the crystallized mixture to obtain wet crystals of sodium dihydrogen phosphate and a crystallization mother liquor of sodium dihydrogen phosphate (the crystallization mother liquor of sodium dihydrogen phosphate is concentrated-crystallized or concentrated-spray dried to obtain agricultural grade sodium dihydrogen phosphate which is used as agricultural sodium phosphate fertilizer), and taking wet crystals of sodium dihydrogen phosphate for standby.
The temperature range of the sodium dihydrogen phosphate crystal metastable zone is 5-35 ℃.
Preferably, the temperature range of the sodium dihydrogen phosphate crystal metastable zone is 5-20 ℃.
⑹ drying the crystals, drying the ⑸ wet crystals of sodium dihydrogen phosphate by hot air at normal pressure until the moisture content of the product is required, cooling and packaging to obtain the food grade sodium dihydrogen phosphate product, and controlling the temperature of the materials in the whole process of the step to be less than or equal to 120 ℃.
The required moisture content is less than or equal to 2 percent by mass.
Preferably, the water requirement is less than 2% in percentage by mass.
Compared with the prior art, the method has the advantages and beneficial effects that:
1. the method mainly solves the separation of tiny solid particles (including pigments) in industrial wet-process purified phosphoric acid by filtering through a silicon carbide film with strong acid resistance, realizes the precipitation and precipitation of main impurities with high contents of fluorine, sulfur and the like in wet-process diluted phosphoric acid by neutralizing to subacidity, solves the technical problems and difficulties of removing toxic and harmful arsenic, lead, cadmium and other heavy metals in the wet-process diluted phosphoric acid by oxidizing dearsenification, alkalescence deaddition and film filtering, and mainly achieves the technical effects of separating impurities, removing toxic and harmful substances and improving the purity of sodium dihydrogen phosphate so that the product meets the food-grade quality requirement. Compared with the prior art, the invention is characterized in that the prior art can only utilize industrial wet-process purified phosphoric acid to prepare the industrial grade sodium dihydrogen phosphate, and the invention realizes the technical breakthrough of directly preparing the food grade sodium dihydrogen phosphate by utilizing the industrial wet-process purified phosphoric acid.
2. Through the technical treatment of the invention, the removal rate of insoluble impurities in industrial wet-process purified phosphoric acid is 100 percent, the removal rate of pigments is more than 95 percent, and the appearance is clear and transparent; the removal rate of main impurities such as fluorine ions, sulfur ions (sulfate ions) and the like is more than 99 percent; the removal rate of toxic and harmful substances such as arsenic, lead, cadmium and the like is more than 99.99 percent; the phosphoric acid retention rate is more than 99.5 percent. Through determination, the obtained food-grade sodium dihydrogen phosphate is white crystalline powder or granules, and all indexes of the food-grade sodium dihydrogen phosphate meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
3. Low cost, high purity, sufficient removal of arsenic and heavy metal ions, high sanitary safety, simple and convenient process, high utilization rate of raw materials, good solubility, mechanized production and suitability for large-scale and small-scale production.
Drawings
FIG. 1 is a process flow diagram for producing food grade sodium dihydrogen phosphate from industrial wet-purified phosphoric acid.
Detailed Description
The applicant shall now describe the process of the present invention in further detail with reference to specific examples.
Example 1:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt & lt & gt, adding reverse osmosis pure water with the mass multiple of 1.12 times of the mass of the product under the condition of stirring, continuing to stir for 0.5 hour to obtain industrial wet purification phosphoric acid diluent with the mass percentage.
⑵ neutralization and defluorination and desulfurization 2.29kg of 40% diluted solution of industrial wet-process purified phosphoric acid obtained in step ⑴ is taken, barium carbonate with the mass fraction of 0.3% is added as a defluorination and desulfurization agent under the condition of continuous stirring, the stirring is continued for 4.5 hours until no air bubbles (carbon dioxide) are generated, the barium carbonate is fully dissolved and fully reacted with the fluorine ions and the sulfate radicals in the diluted solution of the industrial wet-process purified phosphoric acid, a reaction mixture is obtained, the stirring is maintained, the reaction mixture is neutralized by 45% sodium hydroxide solution until the pH value is 3.9, the stirring is continued for 7 hours, a neutralization solution is obtained, the temperature of the neutralization solution is controlled at 30 ℃, the neutralization solution is precisely filtered by a microporous membrane device with a membrane material of silicon carbide, a membrane pore size of 0.04 mu m and a membrane component form of a honeycomb coal type inner tubular membrane, barium sulfate, barium fluorosilicate and other solid particles are separated, and the precisely filtered neutralization solution is obtained.
⑶ oxidizing to remove arsenic, removing heavy metal with alkalescence, filtering with membrane, adjusting pH of the neutralized solution obtained in step ⑵ to 7.2 with 45% sodium hydroxide solution by mass percentage, adding bleaching powder with 0.5% neutralized solution mass fraction as oxidant, heating the mixture to 85 deg.C, maintaining at 85 deg.C, refluxing under stirring, maintaining the temperature, oxidizing for 4.5 hr, cooling with water to reduce the temperature of the oxide to 40 deg.C, stirring for 5 hr, filtering with microporous membrane equipment with membrane material of silicon carbide, membrane pores of 0.04 μm and inner tubular membrane of honeycomb briquette type, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide and cadmium oxide, and separating heavy metal with alkalescence and arsenic removing solution with stirring speed of 115 rpm.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained alkalescent heavy metal and arsenic oxide removing solution of ⑶ to 4.0 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 55 wt% under vacuum degree of 0.95MPa and temperature of 95 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed of 145 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 20 deg.C to crystallize sodium dihydrogen phosphate for 10 hours, cooling to-2 deg.C at a rate of 1 deg.C/hour, continuously crystallizing for 35 hours until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother liquor of sodium dihydrogen phosphate crystal (the mother liquor of sodium dihydrogen phosphate crystal can be concentrated-crystallized or concentrated-spray dried to obtain agricultural sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate for use.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 105 deg.C, 3.5m/s and 70% relative humidity until the water content is less than 2%, and cooling to obtain 1.35kg of food grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 2:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt, adding reverse osmosis pure water with the mass multiple of 0.98 times of the mass of the qualified products and the industrial wet purification phosphoric acid with the mass percentage concentration of 85% into an acid-resistant container under the condition of stirring, continuously stirring for 1.
⑵ neutralization and defluorination and desulfurization, 11.56kg of industrial wet-process purified phosphoric acid diluent with the mass percentage of 43 percent obtained in the step ⑴ is taken in an acid-proof container, barium carbonate with the mass percentage of 0.5 percent is added as a defluorination and desulfurization agent under the condition of continuous stirring, the stirring is continued for 3 hours until no bubbles (carbon dioxide) are generated, the barium carbonate is fully dissolved and fully reacted with the fluorinion and the sulfate radical in the industrial wet-process purified phosphoric acid diluent to obtain a reaction mixture, the stirring is maintained, the reaction mixture is neutralized by sodium hydroxide solution with the mass percentage of 40 percent to the pH value of 4.1, the stirring is continued for 9 hours to obtain a neutralized solution, the temperature of the neutralized solution is controlled to 35 ℃, the neutralized solution is precisely filtered by microporous membrane equipment with a membrane material of silicon carbide, a membrane pore diameter of 0.1 mu m and a membrane component form of a honeycomb coal type inner tubular membrane, barium sulfate, barium fluosilicate and other solid particles are separated to obtain the precisely filtered neutralized solution for standby, and the stirring speed is controlled to be 160rpm in the whole process of the step.
⑶ oxidizing dearsenification, slightly alkaline heavy metal removal and membrane filtration, under the condition of continuously stirring, using a sodium hydroxide solution with the mass percentage concentration of 40%, adjusting the pH value of the neutralization solution obtained in the step ⑵ to 7.2, adding hydrogen peroxide with the mass fraction of 3% of the neutralization solution as an oxidant, heating the mixture to 85 ℃ and maintaining the temperature at 85 ℃, after refluxing, heat-preserving and oxidizing for 3 hours under the condition of stirring, opening cooling water to reduce the temperature of the mixture to 40 ℃, continuing to stir for 6 hours, precisely filtering the mixture by using microporous membrane equipment with a membrane material of silicon carbide, membrane pores of 0.1 mu m and a membrane component form of a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide, cadmium oxide and the like, and obtaining the slightly alkaline heavy metal removal and the oxidizing dearsenification solution for the precise filtration, wherein the stirring speed is controlled to be 120rpm in the whole process.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 4.1 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 58.5 wt% under vacuum degree of 0.95MPa and temperature of 100 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed of the step at 135 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 15 deg.C to crystallize sodium dihydrogen phosphate for 11 hours, cooling to-0.5 deg.C at a rate of 1 deg.C/hour, continuously crystallizing for 32 hours until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother liquor of sodium dihydrogen phosphate crystal (the mother liquor of sodium dihydrogen phosphate crystal can be concentrated-crystallized or concentrated-spray dried to obtain agricultural sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate for use.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 110 deg.C, speed of 3.5m/s and relative humidity of 70%, drying until the water content is less than 2%, and cooling to obtain 7.31kg of food-grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 3:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt, adding reverse osmosis pure water with the mass multiple of 1.30 times of the mass of the product under the condition of stirring, continuing to stir for 0.5 hour to obtain 37% industrial wet purification phosphoric acid diluent, and controlling the stirring speed to be.
⑵ neutralization and defluorination and desulfurization 5.75kg of industrial wet-process purified phosphoric acid diluent with the mass percentage concentration of 37 percent obtained in the step ⑴ is put in an acid-proof container, barium carbonate with the mass percentage of 0.6 percent is added as a defluorination and desulfurization agent under the condition of continuous stirring, the stirring is continued for 2.3 hours until no air bubbles (carbon dioxide) are generated, the barium carbonate is fully dissolved and fully reacted with the fluorinion and the sulfate radical in the industrial wet-process purified phosphoric acid diluent to obtain a reaction mixture, the stirring is maintained, the reaction mixture is neutralized by a sodium hydroxide solution with the mass percentage concentration of 50 percent until the pH value is 4.3, the stirring is continued for 7 hours to obtain a neutralized solution, the temperature of the neutralized solution is controlled to 35 ℃, the neutralized solution is precisely filtered by a microporous membrane device with a membrane material of silicon carbide, a membrane pore size of 0.04 mu m and a membrane assembly form of a honeycomb coal type inner tubular membrane, barium sulfate, barium fluorosilicate and other solid particles are separated to obtain the precisely filtered neutralized solution for standby, and the stirring speed is controlled to be 140rpm in the whole.
⑶ oxidizing to remove arsenic, slightly alkaline to remove heavy metal and membrane filtration under the condition of continuous stirring, using 50% sodium hydroxide solution by mass percentage concentration, adjusting the pH of the neutralization solution obtained in the step ⑵ to 7.3, adding hydrogen peroxide with 2.5% of the neutralization solution by mass fraction as oxidant, heating the mixture to 80 ℃ and maintaining the temperature at 80 ℃, after refluxing and insulating for oxidation for 5 hours under the condition of stirring, opening cooling water to reduce the temperature of the mixture to 35 ℃, continuing to stir for 5 hours, precisely filtering the mixture by using microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.04 mu m and a membrane component of a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide and cadmium oxide, and the like, to obtain the slightly alkaline to remove heavy metal and the oxidizing to remove arsenic solution of the precise filtration, controlling the stirring speed to be 110rpm in the whole process.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 4.05 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 55.5 wt% under vacuum degree of 0.96MPa and temperature of 105 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed at 160 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 18 deg.C to crystallize sodium dihydrogen phosphate for 9 hr, cooling to 0 deg.C at a rate of 1.5 deg.C/hr, continuously crystallizing for 30 hr until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother liquor of sodium dihydrogen phosphate crystals (concentrated-crystallized mother liquor of sodium dihydrogen phosphate can be concentrated-crystallized or concentrated-spray dried to obtain agricultural sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate for use.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 55 deg.C, 4.5m/s speed and 65% relative humidity until the water content is less than 2%, and cooling to obtain 3.13kg of food grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 4:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products and industrial wet-process purified phosphoric acid with the mass percentage concentration of 85 percent, which meet the requirements of HG/T4069-2008 < industrial wet-process purified phosphoric acid >, into an acid-resistant container, adding reverse osmosis pure water with the mass multiple of 0.85 time under the condition of stirring, and continuously stirring for 1.5 hours to obtain industrial wet-process purified phosphoric acid diluent with the mass percentage concentration of 46 percent, wherein the stirring speed is controlled to be 100rpm in the whole process of the step.
⑵ neutralization and defluorination and desulfurization step ⑴ was carried out by putting 1680kg of 46% diluted solution of industrial wet-process purified phosphoric acid obtained in step ⑴ as defluorination and desulfurization agent in an acid-proof container, continuously stirring for 4.5 hours while adding barium carbonate with a mass fraction of 0.45% as defluorination and desulfurization agent until no bubble (carbon dioxide) was generated, dissolving barium carbonate sufficiently and reacting sufficiently with fluoride ion and sulfate radical in the diluted solution of industrial wet-process purified phosphoric acid to obtain a reaction mixture, stirring while maintaining, neutralizing the reaction mixture with 35% by mass sodium hydroxide solution to a pH of 4.3, and continuously stirring for 8.5 hours to obtain a neutralized solution, controlling the temperature of the neutralized solution to 40 ℃, and finely filtering the neutralized solution with a microporous membrane device with a membrane material of silicon carbide, a membrane pore size of 0.1 μm and a membrane assembly of a honeycomb briquette type inner tubular membrane to separate barium sulfate, barium fluorosilicate and other solid particles to obtain a finely filtered neutralized solution.
⑶ oxidizing dearsenification, slightly alkaline heavy metal removal and membrane filtration, under the condition of continuous stirring, using 35% sodium hydroxide solution by mass percentage concentration, adjusting the pH value of the neutralization solution obtained in the step ⑵ to 7.25, adding hydrogen peroxide with the mass fraction of the neutralization solution being 1.5% as an oxidant, heating the mixture to 90 ℃ and maintaining the temperature at 90 ℃, after refluxing and heat preservation and oxidation for 4 hours under the condition of stirring, opening cooling water to reduce the temperature of the mixture to 40 ℃, continuing to stir for 6.5 hours, precisely filtering the mixture by using microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.1 mu m and a membrane component of a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide, cadmium oxide and the like, and obtaining the slightly alkaline dearsenification solution and the precise filtration, wherein the stirring speed is 130rpm in the whole process of the step.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 4.15 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 58.1 wt% under vacuum degree of 0.95MPa and temperature of 90 deg.C by forced circulation vacuum concentration method, and controlling stirring speed at 160 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 17 deg.C to crystallize sodium dihydrogen phosphate for 12 hr, cooling to 1 deg.C/hr to crystallize it for 35 hr until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother solution of sodium dihydrogen phosphate crystals (concentrated-crystallized or concentrated-spray dried mother solution of sodium dihydrogen phosphate to obtain agricultural sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate for use.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 105 deg.C, speed of 3m/s and relative humidity of 75%, drying until the water content is less than 2%, and cooling to obtain food grade sodium dihydrogen phosphate product 1136 kg.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 5:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt, adding reverse osmosis pure water with the mass multiple of 1.43 times of the mass of the phosphoric acid into the acid-resistant container under the condition of stirring, and continuing stirring for 0.5 hour to obtain industrial wet purification phosphoric acid diluent with the mass.
⑵ neutralization and defluorination and desulfurization 5.14kg of 35% industrial wet-process purified phosphoric acid diluent obtained in step ⑴ is put in an acid-proof container, barium carbonate with the mass fraction of 0.21% is added as a defluorination and desulfurization agent under the condition of continuous stirring, the stirring is continued for 3.5 hours until no air bubbles (carbon dioxide) are generated, so that the barium carbonate is fully dissolved and fully reacted with the fluoride ions and sulfate radicals in the industrial wet-process purified phosphoric acid diluent to obtain a reaction mixture, the stirring is maintained, the reaction mixture is neutralized to the pH value of 4.1 by 50% sodium hydroxide solution, the stirring is continued for 6.5 hours to obtain a neutralization solution, the temperature of the neutralization solution is controlled to be 30 ℃, the neutralization solution is precisely filtered by a microporous membrane device with a membrane material of silicon carbide, a membrane pore size of 0.04 mu m and a membrane component form of a honeycomb briquette type inner tubular membrane, barium sulfate, barium fluorosilicate and other solid particles are separated, and the precisely filtered neutralization solution is obtained.
⑶ oxidizing to remove arsenic, slightly alkaline to remove heavy metal and membrane filtration, under the condition of continuously stirring, using 50% sodium hydroxide solution by mass percentage concentration, adjusting the pH of the neutralization solution obtained in the step ⑵ to 7.15, adding hydrogen peroxide with the mass fraction of 1.5% of the neutralization solution as oxidant, heating the mixture to 78 ℃ and maintaining the temperature at 78 ℃, after refluxing, preserving heat and oxidizing for 5.5 hours under the condition of stirring, opening cooling water to reduce the temperature of the mixture to 40 ℃, continuing to stir for 6 hours, precisely filtering the mixture by using microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.04 mu m and a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide, cadmium oxide and the like, and obtaining the slightly alkaline to remove heavy metal and oxidizing to remove arsenic of the precise filtration for standby, controlling the stirring speed to be 100rpm in the whole process of the step.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 4.05 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 59.5 wt% under vacuum degree of 0.95MPa and temperature of 95 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed at 160 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 16 deg.C to crystallize sodium dihydrogen phosphate for 13 hr, cooling to-1.5 deg.C at a rate of 1.1 deg.C/hr, crystallizing for 34 hr until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother solution of sodium dihydrogen phosphate (the mother solution of sodium dihydrogen phosphate can be concentrated-crystallized or concentrated-spray dried to obtain agricultural grade sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate.
⑹ drying crystal, namely drying wet crystal of sodium dihydrogen phosphate obtained in step ⑸ by using hot air with the temperature of 110 ℃, the speed of 3m/s and the relative humidity of 75% until the mass percentage of water is less than 2%, and cooling to obtain 2.64kg of food-grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 6:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt, adding reverse osmosis pure water with the mass multiple of 0.77 times of the mass of the qualified products and the industrial wet purification phosphoric acid with the mass percentage concentration into the acid-resistant container under the condition of stirring, and continuously stirring for 1.5.
⑵ neutralization and defluorination and desulfurization, namely, 907g of 48 mass percent industrial wet-process purified phosphoric acid diluent obtained in the step ⑴ is taken in an acid-proof container, barium carbonate with the mass fraction of 0.60 percent is added as a defluorination and desulfurization agent under the condition of continuous stirring, the stirring is continued for 3 hours until no bubbles (carbon dioxide) are generated, the barium carbonate is fully dissolved and fully reacted with fluoride ions and sulfate radicals in the industrial wet-process purified phosphoric acid diluent to obtain a reaction mixture, the stirring is maintained, the reaction mixture is neutralized by 35 mass percent sodium hydroxide solution until the pH value is 4.25, the stirring is continued for 9 hours to obtain a neutralized solution, the temperature of the neutralized solution is controlled to be 35 ℃, the neutralized solution is precisely filtered by microporous membrane equipment with a membrane material of silicon carbide, the membrane pores are 0.1 mu m and the membrane component is a honeycomb coal type inner tubular membrane, barium sulfate, barium fluosilicate and other solid particles are separated to obtain the precisely filtered neutralized solution, the stirring speed is controlled to be rpm in the whole process 165.
⑶ oxidizing dearsenification, slightly alkaline heavy metal removal and membrane filtration, under the condition of continuous stirring, using 35% sodium hydroxide solution by mass percentage concentration, adjusting the pH value of the neutralization solution obtained in the step ⑵ to 7.1, adding hydrogen peroxide with 2% of the mass fraction of the neutralization solution as an oxidant, heating the mixture to 90 ℃ and maintaining the temperature at 90 ℃, after refluxing, preserving heat and oxidizing for 3 hours under the condition of stirring, opening cooling water to reduce the temperature of the mixture to 40 ℃, continuing to stir for 7 hours, precisely filtering the mixture by using microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.1 mu m and a membrane component of a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide, cadmium oxide and the like, and obtaining the slightly alkaline heavy metal removal and the oxidizing dearsenification solution for the precise filtration, wherein the stirring speed is controlled to be 130rpm in the whole process.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained slightly alkaline heavy metal and arsenic oxide removing solution ⑶ to 4.15 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 54.5 wt% under vacuum degree of 0.95MPa and temperature of 95 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed at 120 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 17 deg.C to crystallize sodium dihydrogen phosphate for 20 hours, cooling to-2 deg.C at a rate of 1.5 deg.C/hour, further crystallizing for 25 hours until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother liquor of sodium dihydrogen phosphate crystal (concentrating-crystallizing or concentrating-spray drying mother liquor of sodium dihydrogen phosphate to obtain agricultural sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 105 deg.C, speed of 3m/s and relative humidity of 75%, drying until the water content is less than 2%, and cooling to obtain food grade sodium dihydrogen phosphate product 640 g.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 7:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt & lt & gt, adding reverse osmosis pure water with the mass multiple of 1.80 times of the mass of the qualified products and the industrial wet purification phosphoric acid with the mass percentage concentration of 85% into an acid-resistant container under the condition of stirring.
⑵ neutralization and defluorination and desulfurization 7.84kg of industrial wet-process purified phosphoric acid diluent with the mass percentage concentration of 30.4 percent obtained in the step ⑴ is taken in an acid-proof container, barium carbonate with the mass percentage of 0.18 percent is added as a defluorination and desulfurization agent under the condition of continuous stirring, the stirring is continued for 4.5 hours until no bubbles (carbon dioxide) are generated, so that the barium carbonate is fully dissolved and fully reacted with the fluorine ions and the sulfate radicals in the industrial wet-process purified phosphoric acid diluent to obtain a reaction mixture, the stirring is maintained, the reaction mixture is neutralized by sodium hydroxide solution with the mass percentage concentration of 45 percent until the pH value is 3.9, the stirring is continued for 9 hours to obtain a neutralized solution, the temperature of the neutralized solution is controlled to be 30 ℃, the neutralized solution is precisely filtered by a microporous membrane device with a membrane material of silicon carbide, membrane pores of 0.04 mu m and a membrane assembly form of a honeycomb coal type inner tubular membrane, barium sulfate, barium fluorosilicate and other solid particles are separated, and the precisely filtered neutralized solution is obtained.
⑶ oxidizing dearsenification, slightly alkaline heavy metal removal and membrane filtration, under the condition of continuous stirring, using a sodium hydroxide solution with the mass percentage concentration of 45%, adjusting the pH value of the neutralization solution obtained in the step ⑵ to 7.2, adding hydrogen peroxide with the mass fraction of 1.3% of the neutralization solution as an oxidant, heating the mixture to 85 ℃ and maintaining the temperature at 85 ℃, after refluxing, preserving the heat and oxidizing for 4 hours under the condition of stirring, opening cooling water to reduce the temperature of the mixture to 40 ℃, continuing to stir for 6.3 hours, precisely filtering the mixture by using microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.04 mu m and a membrane component of a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide, cadmium oxide and the like, and obtaining the slightly alkaline dearsenification solution and the slightly alkaline dearsenification solution for the precise filtration, wherein the stirring speed is controlled to be 90rpm in the whole process.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 4.05 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 57.5 wt% under vacuum degree of 0.95MPa and temperature of 95 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed at 140 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 19 deg.C to crystallize sodium dihydrogen phosphate for 13 hr, cooling to-1.5 deg.C at a rate of 0.5 deg.C/hr, crystallizing for 35 hr until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother solution of sodium dihydrogen phosphate (the mother solution of sodium dihydrogen phosphate can be concentrated-crystallized or concentrated-spray dried to obtain agricultural grade sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 105 deg.C, speed of 3m/s and relative humidity of 75%, drying until the water content is less than 2%, and cooling to obtain 3.51kg of food grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 8:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt, adding reverse osmosis pure water with the mass multiple of 0.70 times of the mass of the qualified products and the industrial wet purification phosphoric acid with the mass percentage concentration of 85% into an acid-resistant container under the condition of stirring, continuously stirring for 0.
⑵ neutralization and defluorination and desulfurization 3.95kg of 50% diluted solution of industrial wet-process purified phosphoric acid obtained in step ⑴ was placed in an acid-proof container, and while continuously stirring, 0.5% by mass of barium bicarbonate was added as a defluorination and desulfurization agent, and the stirring was continued for 2.5 hours until no bubble (carbon dioxide) was generated, so that the barium bicarbonate was sufficiently dissolved and reacted with the fluoride ions and sulfate radicals in the diluted solution of industrial wet-process purified phosphoric acid, to obtain a reaction mixture, the stirring was maintained, the reaction mixture was neutralized with 30% by mass of sodium hydroxide solution to a pH of 4.15, and the stirring was continued for 8.5 hours to obtain a neutralized solution, the temperature of the neutralized solution was controlled at 35 ℃, the neutralized solution was finely filtered with a microporous membrane device having a membrane material of silicon carbide, a membrane pore size of 0.1 μm, and a membrane assembly form of a honeycomb briquette type inner tubular membrane, to separate barium sulfate, barium fluorosilicate, and other solid particles, and the finely filtered neutralized solution was obtained.
⑶ oxidizing to remove arsenic, slightly alkaline to remove heavy metal and membrane filtration under the condition of continuous stirring, using 30% sodium hydroxide solution by mass percentage concentration, adjusting the pH of the neutralization solution obtained in the step ⑵ to 7.25, adding hydrogen peroxide with the mass fraction of the neutralization solution being 2.0% as oxidant, heating the mixture to 80 ℃ and maintaining the temperature at 80 ℃, after refluxing and heat-preserving for oxidation for 4 hours under the condition of stirring, opening cooling water to reduce the temperature of the oxidant to 40 ℃, continuing to stir for 6.6 hours, precisely filtering the mixture by microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.1 mu m and a membrane component of a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide, cadmium oxide and the like, and obtaining the slightly alkaline to remove heavy metal and oxidizing to remove arsenic by membrane filtration, controlling the stirring speed to be 110rpm in the whole process.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 4.0 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 56.5 wt% under vacuum degree of 0.95MPa and temperature of 95 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed at 140 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 14 deg.C to crystallize sodium dihydrogen phosphate for 11 hr, cooling to-2 deg.C at a rate of 0.5 deg.C/hr, crystallizing for 38 hr until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother solution of sodium dihydrogen phosphate crystals (concentrated-crystallized mother solution of sodium dihydrogen phosphate can be concentrated-crystallized or concentrated-spray dried to obtain agricultural sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate for use.
⑹ drying crystal, namely drying wet crystal of sodium dihydrogen phosphate obtained in step ⑸ by hot air with the temperature of 105 ℃, the speed of 3m/s and the relative humidity of 75% until the mass percentage of water is less than 2%, and cooling to obtain 2.90kg of food grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 9:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt & lt & gt, adding reverse osmosis pure water with the mass multiple of 3.10 times of the mass of the qualified products and the industrial wet purification phosphoric acid with the mass percentage concentration of 85% into an acid-resistant container under the condition of stirring.
⑵ neutralization and defluorination and desulfurization 8.88kg of industrial wet-process purified phosphoric acid diluent with the mass percentage concentration of 20.7 percent obtained in the step ⑴ is put in an acid-proof container, barium carbonate with the mass percentage of 0.19 percent is added as a defluorination and desulfurization agent under the condition of continuous stirring, the stirring is continued for 3 hours until no bubbles (carbon dioxide) are generated, so that the barium carbonate is fully dissolved and fully reacted with the fluorine ions and the sulfate radicals in the industrial wet-process purified phosphoric acid diluent to obtain a reaction mixture, the stirring is maintained, the reaction mixture is neutralized by a sodium hydroxide solution with the mass percentage concentration of 50 percent until the pH value is 4.15, the stirring is continued for 9 hours to obtain a neutralized solution, the temperature of the neutralized solution is controlled to be 25 ℃, the neutralized solution is precisely filtered by a microporous membrane device with a membrane material of silicon carbide, membrane pores of 0.1 mu m and a membrane assembly form of a honeycomb coal type inner tubular membrane, barium sulfate, barium fluorosilicate and other solid particles are separated, and the precisely filtered neutralized solution is obtained.
⑶ oxidizing to remove arsenic, slightly alkaline to remove heavy metal and membrane filtration under the condition of continuous stirring, using 50% sodium hydroxide solution by mass percentage concentration, adjusting the pH of the neutralization solution obtained in the step ⑵ to 7.2, adding hydrogen peroxide with the mass fraction of the neutralization solution being 0.9% as oxidant, heating the mixture to 80 ℃ and maintaining the temperature at 80 ℃, after refluxing and insulating for oxidation for 4.5 hours under the condition of stirring, opening cooling water to reduce the temperature of the oxidant to 30 ℃, continuing to stir for 6 hours, precisely filtering the mixture by microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.1 mu m and a membrane component of honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide, cadmium oxide and the like, and obtaining the slightly alkaline to remove heavy metal and oxidizing to remove arsenic by membrane filtration, controlling the stirring speed to be 90rpm in the whole process of the step.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 4.1 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 54.5 wt% under vacuum degree of 0.95MPa and temperature of 95 deg.C by rotary evaporation vacuum concentration method, and controlling stirring speed of the step at 135 rpm.
⑸ cooling crystallization the concentrated solution of sodium dihydrogen phosphate obtained in step ⑷ is transferred to a crystallization device, after cooling to 13 ℃ to crystallize sodium dihydrogen phosphate for 11 hours, the temperature is reduced to-1.5 ℃ at the cooling rate of 0.5 ℃/hour, crystallization is continued for 39 hours until no crystallization is generated, the crystallization mixture is subjected to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother liquor of sodium dihydrogen phosphate crystallization (the mother liquor of sodium dihydrogen phosphate is concentrated-crystallized or concentrated-spray dried to obtain agricultural grade sodium dihydrogen phosphate which is used as agricultural sodium phosphate fertilizer), and the wet crystals of sodium dihydrogen phosphate are taken for standby.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 105 deg.C, speed of 3m/s and relative humidity of 75%, drying until the water content is less than 2%, and cooling to obtain 2.71kg of food-grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
Example 10:
a method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid comprises the following steps:
⑴, adding water to dilute, putting qualified products with the quality meeting the requirements of HG/T4069-2008 & ltIndustrial Wet purification phosphoric acid & gt 2008 & lt & gt, adding reverse osmosis pure water with the mass multiple of 0.50 times of the mass of the qualified products and the industrial wet purification phosphoric acid with the mass percentage concentration of 85% into an acid-resistant container under the condition of stirring, continuously stirring for 1.5.
⑵ neutralization and defluorination and desulfurization step ⑴, getting 56.7% by weight of industrial wet-process purified phosphoric acid diluent 625kg in an acid-proof container, adding 1.0% by weight of barium bicarbonate as defluorination and desulfurization agent under the condition of continuous stirring, continuing stirring for 3.4 hours until no bubbles (carbon dioxide) are generated, fully dissolving the barium bicarbonate and fully reacting with the fluoride ions and sulfate radicals in the industrial wet-process purified phosphoric acid diluent to obtain a reaction mixture, maintaining stirring, neutralizing the reaction mixture with 30% by weight of sodium hydroxide solution until the pH value is 4.1, continuing stirring for 7 hours to obtain a neutralized solution, controlling the temperature of the neutralized solution to 35 ℃, precisely filtering the neutralized solution by a microporous membrane device with a membrane material of silicon carbide, a membrane pore size of 0.04 mu m and a membrane component form of a honeycomb briquette type inner tubular membrane, separating barium sulfate, barium fluorosilicate and other solid particles to obtain the precisely filtered neutralized solution for later use, and controlling the stirring speed to be 145rpm in the whole process.
⑶ oxidizing to remove arsenic, slightly alkaline to remove heavy metal and membrane filtration under the condition of continuous stirring, using 30% sodium hydroxide solution by mass percentage concentration, adjusting the pH of the neutralization solution obtained in the step ⑵ to 7.1, adding hydrogen peroxide with 4.0% of the neutralization solution by mass fraction as oxidant, heating the mixture to 90 ℃ and maintaining the temperature at 90 ℃, after refluxing and insulating for oxidation for 3 hours under the condition of stirring, opening cooling water to reduce the temperature of the oxidant to 45 ℃, continuing to stir for 6 hours, precisely filtering the mixture by using microporous membrane equipment with a membrane material of silicon carbide, a membrane hole of 0.04 mu m and a membrane component of a honeycomb coal type inner tubular membrane, separating insoluble substances such as barium arsenate, sodium arsenate, lead oxide and cadmium oxide, and the like, to obtain the slightly alkaline to remove heavy metal and the oxidizing to remove arsenic solution after precise filtration, controlling the stirring speed to 145rpm in the whole process.
⑷ adjusting pH and concentrating under stirring, adjusting pH of the obtained heavy metal and arsenic oxide removing solution ⑶ to 3.95 with 85 wt% food grade phosphoric acid to obtain sodium dihydrogen phosphate solution, concentrating the sodium dihydrogen phosphate solution to 58.3 wt% under vacuum degree of 0.95MPa and temperature of 95 deg.C by forced circulation vacuum concentration method, and controlling stirring speed of the step at 135 rpm.
⑸ cooling and crystallizing, transferring the concentrated solution of sodium dihydrogen phosphate from step ⑷ into a crystallizing device, cooling to 16 deg.C to crystallize sodium dihydrogen phosphate for 13 hr, cooling to-1 deg.C at a rate of 1 deg.C/hr, continuously crystallizing for 38 hr until no crystal is formed, subjecting the crystallized mixture to solid-liquid separation to obtain wet crystals of sodium dihydrogen phosphate and mother solution of sodium dihydrogen phosphate crystals (concentrated-crystallized or concentrated-spray dried mother solution of sodium dihydrogen phosphate to obtain agricultural sodium dihydrogen phosphate used as agricultural sodium phosphate fertilizer), and collecting wet crystals of sodium dihydrogen phosphate.
⑹ drying crystal by wet crystallization of sodium dihydrogen phosphate obtained in step ⑸ with hot air at 105 deg.C, speed of 3m/s and relative humidity of 75%, drying until the water content is less than 2%, and cooling to obtain 521kg of food grade sodium dihydrogen phosphate product.
The obtained food grade sodium dihydrogen phosphate is white crystalline powder or granules by determination; sodium dihydrogen phosphate content (NaH)2PO4) (mass percent,%) is not less than 98.0, water-insoluble substances are not more than 0.2, arsenic (As, mg/kg) is not more than 3, heavy metals (mg/kg) is not more than 10, lead (Pb, mg/kg) is not more than 4, fluoride (mg/kg) is not more than 50, pH (10g/L) is 8.8-9.2, and dry weight loss (mass percent,%) is not more than 2.0. All physical and chemical indexes of the food additive meet or exceed the requirements of national food safety standard GB25564-2010 food additive sodium dihydrogen phosphate.
The specific embodiments described in this specification are merely illustrative of the spirit of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.

Claims (7)

1. A method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid is characterized by comprising the following steps:
⑴ adding water to dilute the phosphoric acid, placing the phosphoric acid into an acid-proof container, adding water with the mass multiple of 0.5-3.1 times of the phosphoric acid under the condition of stirring to obtain a dilute phosphoric acid solution with the mass percentage concentration of 20.7-56.7%, and continuously stirring to obtain a dilute phosphoric acid solution for industrial wet purification;
⑵ neutralization reaction and defluorination and desulfurization, namely, putting phosphoric acid diluent ⑴ into an acid-resistant container, adding defluorination and desulfurization agent with the mass fraction of 0.1-1% of the phosphoric acid diluent under the condition of stirring, continuously stirring to ensure that the defluorination and desulfurization agent are fully dissolved and fully reacted with fluoride ions and sulfate radicals in the phosphoric acid diluent purified by the industrial wet method to obtain a reaction mixture, neutralizing the reaction mixture by using sodium hydroxide solution with the mass percentage concentration of 20-50% under the condition of stirring until the pH value is 3.8-4.8, and continuously stirring to obtain a neutralization solution, controlling the temperature of the neutralization solution to be 20-60 ℃, and precisely filtering the neutralization solution by using membrane filtration equipment to obtain the precisely filtered neutralization solution for later use;
⑶, oxidizing to remove arsenic, slightly alkaline to remove heavy metal and membrane filtering, under the condition of continuous stirring, adjusting the pH of the neutralized liquid obtained by precise filtering with ⑵ to 7.0-8.0 by using a sodium hydroxide solution with the mass percentage concentration of 20-50%, adding an oxidant with the mass fraction of 0.1-4% of the neutralized liquid, heating the mixture and maintaining the temperature to the temperature required by arsenic oxidation, refluxing, preserving heat and oxidizing for 0.5-8 hours under the condition of stirring, then opening cooling water to reduce the temperature of the mixture to 20-60 ℃, continuously stirring for 0.5-10 hours, and precisely filtering the mixture by using membrane filtering equipment to obtain the slightly alkaline to remove heavy metal and the oxidized arsenic-removing liquid for later use;
⑷, adjusting and concentrating the pH of the ⑶ obtained alkalescent heavy metal removal and arsenic removal liquid to 3.7-4.6 by phosphoric acid under the condition of continuous stirring to obtain sodium dihydrogen phosphate solution, and concentrating the sodium dihydrogen phosphate solution to 45-65% by mass percent by a forced circulation vacuum concentration method under the conditions of a vacuum degree of 0.8-0.99 MPa and a temperature of 70-110 ℃ to obtain sodium dihydrogen phosphate concentrated solution for later use;
⑸ cooling crystallization, transferring the ⑷ sodium dihydrogen phosphate concentrated solution into crystallization equipment, after crystallizing sodium dihydrogen phosphate within the temperature range of a sodium dihydrogen phosphate crystallization metastable zone for 1-25 hours, cooling the temperature to-5-10 ℃ at a cooling speed of 1-10 ℃/hour, continuing crystallization for 1-50 hours until no crystallization is generated, performing solid-liquid separation on the crystallization mixture to obtain wet sodium dihydrogen phosphate crystals and a crystallization mother solution of sodium dihydrogen phosphate, and performing concentration-crystallization or concentration-spray drying on the crystallization mother solution of sodium dihydrogen phosphate to obtain agricultural grade sodium dihydrogen phosphate which is used as agricultural sodium phosphate fertilizer, and taking wet sodium dihydrogen phosphate crystals for standby;
⑹ drying the crystal, drying the ⑸ wet crystal of sodium dihydrogen phosphate with hot air under normal pressure until the product requires moisture, cooling and packaging to obtain food grade sodium dihydrogen phosphate product, wherein the temperature of the material in the whole process is controlled to be less than or equal to 120 ℃.
2. The method for preparing food grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid according to claim 1, wherein the industrial wet-process purified phosphoric acid obtained in step ⑴ is defluorinated, desulfurized, extracted, re-extracted and purified wet-process phosphoric acid with a mass percentage concentration of 85%, and the mass of the wet-process purified phosphoric acid is superior, first-class and qualified products according to HG/T4069-2008 "industrial wet-process purified phosphoric acid", and the water has an electrical conductivity of less than 10-3s/m reverse osmosis process pure water, ion exchange process pure water, and distillation condensation process pure water.
3. The method of claim 1, wherein the defluorinating agent used in step ⑵ is analytically or chemically pure barium carbonate or barium bicarbonate, the sodium hydroxide is analytically or chemically pure solid sodium hydroxide, and the membrane filtration device comprises a silicon carbide membrane module in the form of a honeycomb briquette type inner tube membrane with a pore size of 1, 0.5, 0.1 or 0.04 μm.
4. The method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid according to claim 1, wherein the sodium hydroxide in step ⑶ is analytically or chemically pure solid sodium hydroxide, the oxidants are analytically or chemically pure hydrogen peroxide (hydrogen peroxide) and bleaching powder, the temperature required by arsenic oxidation is 50-100 ℃, and the membrane material of the membrane filtration equipment is silicon carbide, the membrane component is a honeycomb coal type inner tubular membrane, and the size of the membrane pores is 1, 0.5, 0.1 or 0.04 μm.
5. The method as claimed in claim 1, wherein the phosphoric acid obtained in step ⑷ has a purity of analytically pure, chemically pure and food grade, and a concentration of 75% by mass and 85% by mass.
6. The method for producing food grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid according to claim 1, wherein the temperature range of the metastable zone of sodium dihydrogen phosphate crystals in the step ⑸ is 5-35 ℃.
7. The method for producing food grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid as claimed in claim 1, wherein the required water content in step ⑹ is less than or equal to 2% by weight.
CN201810906998.XA 2018-08-09 2018-08-09 Method for preparing food-grade sodium dihydrogen phosphate by using industrial wet-process purified phosphoric acid Withdrawn CN110817826A (en)

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