CN110395702B - Method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by wet-process phosphoric acid - Google Patents
Method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by wet-process phosphoric acid Download PDFInfo
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Abstract
The invention relates to a method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by using wet-process phosphoric acid, belonging to the technical field of chemical production. The technical problem solved by the invention is to provide a method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by using wet-process phosphoric acid, which comprises the following steps: a. extracting wet-process phosphoric acid by using an extracting agent, and carrying out phase separation to obtain a water phase A and an organic phase A; b. mixing the water phase A with a defluorinating agent, adjusting the pH to 2.5-3.0, and filtering to obtain a filtrate B and a white fertilizer; c. mixing the filtrate B with a precipitator, adjusting the pH to 5.5-6.5, filtering to obtain filtrate C and filter cake C, and drying the filter cake C to obtain feed-grade DCP; d. mixing the organic phase A with a stripping agent for stripping, and splitting phases to obtain an organic phase D and a water phase D; e. solid MAP was prepared from aqueous phase D. The invention has simple process, low cost, high utilization rate of phosphorus element and better social and economic benefits.
Description
Technical Field
The invention relates to a method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by using wet-process phosphoric acid, belonging to the technical field of chemical production.
Background
Monoammonium phosphate (MAP), also known as monoammonium phosphate. Ammonium dihydrogen phosphate is often used as a fire extinguishing agent and a fire retardant in industry, and is also a main raw material for producing ammonium polyphosphate fire retardant; the fertilizer is a high-purity nitrogen-phosphorus binary compound fertilizer in agriculture, and is a quick-soluble efficient compound drip irrigation fertilizer and a main raw material for preparing a water-soluble fertilizer; is used as a leavening agent, a nutrient agent and the like in the food industry. With the rapid development of industry and agriculture, the demand of ammonium dihydrogen phosphate is increasing.
The production method of industrial-grade ammonium dihydrogen phosphate mainly has three methods, namely a neutralization method, a double decomposition method and an extraction method. The neutralization method can be divided into two methods, one is that the thermal method phosphoric acid is used as raw material, and ammonia gas is introduced into the thermal method phosphoric acid for preparation. Because the thermal phosphoric acid preparation method has large pollution, high energy consumption and high cost, the process has simple equipment and good product quality but has high production cost; secondly, the wet-process phosphoric acid is used as a raw material, and ammonia gas is introduced into the refined wet-process phosphoric acid to prepare monoammonium phosphate, the process flow is long and complicated, and the process cannot be popularized in a large scale due to the blockage of the wet-process phosphoric acid refining technology. The double decomposition method is to react wet-process phosphoric acid with ammonium bicarbonate to prepare ammonium dihydrogen phosphate, and the method has no three-waste discharge, has low cost, but has poor product quality which can only reach the fertilizer grade standard generally. The extraction method is to extract metal ions or phosphoric acid by using an organic solvent to achieve the purposes of enriching phosphoric acid and reducing the content of the metal ions, and then to react refined phosphoric acid with ammonium chloride to prepare ammonium dihydrogen phosphate.
Feed-grade calcium hydrophosphate (DCP), which is feed calcium for short, is a poultry and livestock feed additive rich in two nutrient elements of phosphorus and calcium, and because the phosphorus-calcium ratio (1:1.29) is the closest to the phosphorus-calcium ratio in animal bones, and the calcium hydrophosphate can be completely dissolved in animal gastric acid and can easily enter animal bodies to participate in metabolism, important life substances such as hormones, enzymes and vitamins required by animal bodies are formed, the diseases such as chondropathy, paralysis and the like caused by the lack of phosphorus and calcium of the animals are prevented while the rapid growth of the animals is stimulated, and the mating rate and the survival rate of the animals can be improved. The feed grade calcium hydrophosphate is one of the best feed mineral additives recognized at home and abroad at present, and the economic benefit is very obvious.
Generally, feed-grade calcium hydrophosphate is divided into two production processes according to the source of phosphoric acid, one is that hot-process phosphoric acid is used as a raw material, lime milk is used for neutralizing the hot-process phosphoric acid to prepare the calcium hydrophosphate, the hot-process phosphoric acid has low productivity, large pollution and high energy consumption and cost, and the process is simple but has high production cost; secondly, using wet-process phosphoric acid as a raw material, directly reacting phosphate rock meeting the quality requirement with sulfuric acid to obtain the wet-process phosphoric acid, metering the wet-process phosphoric acid, then feeding the wet-process phosphoric acid into a first-stage neutralization tank, neutralizing the wet-process phosphoric acid with lime milk, filtering filter residues to produce low-value fertilizer calcium hydrophosphate (white fertilizer), and purifying impurities such as iron, aluminum, sulfate radicals and the like in the phosphoric acid after the first-stage neutralization; the filtrate enters a second-stage neutralization tank, lime milk is used for continuous neutralization, the filtrate is filtered and returned to prepare the lime milk, and the filter cake is dried and crushed by airflow to obtain the product.
The patent ZL201410135425.3 discloses a method for co-producing industrial-grade ammonium dihydrogen phosphate and feed-grade calcium phosphate by defluorinated phosphoric acid, wherein raw material defluorinated phosphoric acid reacts with a primary neutralizer (at least one of calcium oxide, calcium carbonate, calcium hydroxide and tricalcium phosphate), a filtrate obtained by filtering reacts with a secondary neutralizer (at least one of ammonia water, liquid ammonia, ammonium carbonate, ammonium bicarbonate, diammonium phosphate and triammonium phosphate), the pH is controlled to be 3.0-5.0, diammonium phosphate meeting a certain standard can be obtained by concentrating the filtrate, and a filter cake obtained by filtering twice can be dried to obtain the feed-grade calcium phosphate. Compared with the traditional neutralization method, the method utilizes metal ions in wet-process phosphoric acid to realize zero emission of slag, and simultaneously produces a certain amount of MAP, and has the defects of higher requirement on the quality of phosphoric acid, and pre-defluorination of the used wet-process phosphoric acid, which undoubtedly increases the cost; furthermore, this method does not implement P2O5The hierarchical utilization of (2).
Disclosure of Invention
Aiming at the defects, the technical problem solved by the invention is to provide the method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by using wet-process phosphoric acid, and raw materials used in the method do not need to be defluorinated in advance, so that the production cost is greatly reduced.
The method for coproducing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by using wet-process phosphoric acid comprises the following steps:
a. and (3) extraction: extracting wet-process phosphoric acid by using an extracting agent, and carrying out phase separation to obtain a water phase A and an organic phase A; wherein the content of P in the wet-process phosphoric acid is P2O515-60 wt%, the content of F is 0.15-1.8 wt%, and the extractant is at least one of organic amine extractant, organic ketone extractant, organic ester extractant, organic alcohol extractant and organic ether extractant;
b. defluorination and impurity removal: mixing the water phase A with a defluorinating agent, adjusting the pH to 2.5-3.0, and filtering to obtain a filtrate B and a white fertilizer; wherein the defluorinating agent is at least one of calcium oxide, calcium hydroxide and calcium carbonate;
c. preparing feed-grade DCP: mixing the filtrate B with a precipitator, adjusting the pH to 5.5-6.5, filtering to obtain filtrate C and filter cake C, and drying the filter cake C to obtain feed-grade DCP; the precipitant is at least one of calcium oxide and calcium hydroxide;
d. back extraction: mixing the organic phase A with a stripping agent for stripping, and splitting phases to obtain an organic phase D and a water phase D; the stripping agent is at least one of ammonia water, ammonium bicarbonate and ammonium carbonate solution; the water phase D is MAP solution;
preparation of MAP: solid MAP was prepared from aqueous phase D.
Preferably, in step a, the extractant is tributyl phosphate, TBP-cyclohexane, n-butanol, n-octanol, cyclohexanol, benzyl alcohol, isoamyl alcohol, methyl isobutyl ketone, isobutyl acetate, isoamyl acetate, diisopropyl ether, diethyl ether or trioctyl tertiary amine.
Preferably, in the step a, the volume ratio of the extracting agent to the wet-process phosphoric acid is 1-3: 1, and more preferably, the volume ratio of the extracting agent to the wet-process phosphoric acid is 3: 1.
Preferably, in the step a, the extraction time is 1-60 min, and the extraction temperature is 30-70 ℃; preferably, the extraction time is 30min and the extraction temperature is 60 ℃.
Preferably, in the step b, the reaction temperature is 30-100 ℃, and more preferably, the reaction temperature is 60 ℃.
Preferably, in the step c, the reaction temperature is 30-100 ℃; more preferably, the reaction temperature is 60 ℃.
Preferably, in step d, NH in the stripping agent4 +With P in the organic phase A2O5The molar ratio of (A) to (B) is 1.5-2.5: 1; more preferably, NH in the stripping agent4 +With P in the organic phase A2O5In a molar ratio of 2: 1.
Preferably, in the step d, the back extraction time is 1-60 min, and the back extraction temperature is 30-70 ℃; more preferably, the stripping time is 30min and the stripping temperature is 60 ℃.
Preferably, in step e, solid MAP is prepared from aqueous phase D by the following method: concentrating the water phase D, filtering to obtain a filtrate E and a filter cake E, drying the filter cake E to obtain granular MAP, and returning the filtrate E to a back extraction or concentration section; or directly cooling and crystallizing the water phase D, filtering to obtain a filtrate F and a filter cake F, drying the filter cake F to obtain granular MAP, and returning the filtrate F to a back extraction section; preferably, the cooling crystallization temperature is 20-30 ℃, and more preferably, the cooling crystallization temperature is 30 ℃; or concentrating the water phase D, and spray drying to obtain powdery MAP; or directly spray-drying the water phase D to obtain the powdery MAP.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention directly takes wet-process phosphoric acid as a raw material, does not need to be defluorinated in advance, has low requirement on the quality of the raw material wet-process phosphoric acid, and replaces hot-process phosphoric acid with the wet-process phosphoric acid to produce ammonium dihydrogen phosphate and calcium hydrophosphate, thereby reducing the production cost.
2. The method of the invention divides the wet-process phosphoric acid into two parts in an extraction mode, and the phosphoric acid with high quality is used for producing ammonium dihydrogen phosphate, thereby reducing the influence of impurities on the ammonium dihydrogen phosphate and ensuring the quality of the ammonium dihydrogen phosphate product. The low-quality phosphoric acid is used for producing calcium hydrophosphate, and P in a water phase is reduced by extracting phosphoric acid in wet-process phosphoric acid2O5Concentration, thereby reducing P entrained with calcium phosphate salts2O5The dosage of the defluorinating agent and the precipitating agent is reduced, and the cost is reduced.
3. The method has simple process, and P carried in the white fertilizer2O5Low content, high utilization rate of phosphorus element, and good social and economic benefits.
Drawings
FIG. 1 is a process flow diagram of the present invention for co-production of ammonium dihydrogen phosphate and feed grade calcium hydrogen phosphate by wet process phosphoric acid.
Detailed Description
The method for coproducing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by using wet-process phosphoric acid comprises the following steps:
a. and (3) extraction: extracting agent for wet process phosphorusExtracting with acid, and separating phases to obtain a water phase A and an organic phase A; wherein the content of P in the wet-process phosphoric acid is P2O515-60 wt%, the content of F is 0.15-1.8 wt%, and the extractant is at least one of organic amine extractant, organic ketone extractant, organic ester extractant, organic alcohol extractant and organic ether extractant;
b. defluorination and impurity removal: mixing the water phase A with a defluorinating agent, adjusting the pH to 2.5-3.0, and filtering to obtain a filtrate B and a white fertilizer; wherein the defluorinating agent is at least one of calcium oxide, calcium hydroxide and calcium carbonate;
c. preparing feed-grade DCP: mixing the filtrate B with a precipitator, adjusting the pH to 5.5-6.5, filtering to obtain filtrate C and filter cake C, and drying the filter cake C to obtain feed-grade DCP; the precipitant is at least one of calcium oxide and calcium hydroxide;
d. back extraction: mixing the organic phase A with a stripping agent for stripping, and splitting phases to obtain an organic phase D and a water phase D; the stripping agent is at least one of ammonia water and ammonium bicarbonate; the water phase D is MAP solution;
preparation of MAP: solid MAP was prepared from aqueous phase D.
The wet-process phosphoric acid in the step a is crude phosphoric acid produced by a wet-process phosphoric acid process, and the classification utilization of phosphorus is realized through the extraction in the step a without pre-defluorination: part of phosphorus is in a water phase containing more metal ions and is used for preparing and obtaining feed-grade calcium hydrophosphate; part of the phosphorus is in the extractant which is basically free of impurities and is used for preparing ammonium dihydrogen phosphate, so that the additional value of the phosphorus is improved.
The method is suitable for wet-process phosphoric acid with high fluorine content, and preferably, the content of F in the wet-process phosphoric acid is 0.85-1.8 wt%.
Extractants commonly used in the art are suitable for use in the present invention. Preferably, in step a, the extractant is tributyl phosphate (TBP), TBP-cyclohexane, N-butanol, N-octanol, cyclohexanol, benzyl alcohol, isoamyl alcohol, methyl isobutyl ketone (MIBK), isobutyl acetate, isoamyl acetate, diisopropyl ether, diethyl ether, trioctyl tertiary amine (N235), and the like.
Preferably, in the step a, the volume ratio of the extracting agent to the wet-process phosphoric acid is 1-3: 1, and more preferably, the volume ratio of the extracting agent to the wet-process phosphoric acid is 3: 1.
In order to improve the reaction efficiency, in the step a, the extraction time is 1-60 min, and the extraction temperature is 30-70 ℃; preferably, the extraction time is 30min and the extraction temperature is 60 ℃.
And b, after the step a, dividing the wet-process phosphoric acid into two parts, and respectively preparing ammonium dihydrogen phosphate and calcium hydrogen phosphate. In the method of the present invention, step b and step c are processes for preparing calcium hydrogen phosphate, and step d and step e are processes for preparing ammonium dihydrogen phosphate, which have no time sequence, and steps b and c can be performed first, and then steps d and e can be performed; steps d and e may be performed first, and then steps b and c may be performed, or steps d and e may be performed simultaneously with steps b and c.
And b, adding a defluorinating agent for defluorination and impurity removal, wherein the addition amount of the defluorinating agent is based on the pH value of the final liquid being 2.5-3.0. Namely, the pH value is adjusted by adding a defluorinating agent in the step b. The equation for the reaction that occurs with the relevant metal ion during this period is as follows:
Ca2++2H3PO4＝Ca(H2PO4)2+2H+
Fe3++H3PO4+2H2O＝FePO4·2H2O↓+3H+
Al3++H3PO4+2H2O＝AlPO4·2H2O↓+3H+
Mg2++H3PO4+3H2O＝MgHPO4·3H2O↓+2H+
3Ca(OH)2+H2SiF6＝3CaF2↓+SiO2↓+4H2O
Ca2++2H2SO4+2H2O＝CaSO4·2H2O↓+2H+
Ca(H2PO4)2+Ca(OH)2+2H2O＝2CaHPO4·2H2O↓
in order to improve the reaction efficiency, preferably, in the step b, the reaction temperature is 30-100 ℃, and more preferably, the reaction temperature is 60 ℃.
And d, after defluorination and impurity removal, filtering to obtain a solid white fertilizer, and continuing the step c on the filtrate B.
And c, adding a precipitator to precipitate the DCP, wherein the addition amount of the precipitator is based on the pH value of the reaction end point being 5.5-6.5, namely the pH value is adjusted by adding the precipitator in the step c. During this time, the following reactions mainly occur:
Ca2++2H3PO4＝Ca(H2PO4)2+2H+
in order to improve the reaction efficiency, preferably, in the step c, the reaction temperature is 30-100 ℃; more preferably, the reaction temperature is 60 ℃.
And C, filtering after the reaction in the step C to obtain filtrate C and filter cake C, drying the filter cake C to obtain feed-grade DCP, and preferably returning the filtrate C to the phosphorite pulp working section for recycling.
In the step D, the organic phase A and a stripping agent are mixed for stripping to obtain an organic phase D and a water phase D, and the reaction in the step is as follows:
H3PO4+NH4 +＝NH4H2PO4+H+
further, in order to improve the stripping effect and save the dosage of the stripping agent, it is preferable that NH in the stripping agent is used4 +With P in the organic phase A2O5The molar ratio of (A) to (B) is 1.5-2.5: 1; more preferably, NH in the stripping agent4 +With P in the organic phase A2O5In a molar ratio of 2: 1.
In order to improve the reaction efficiency, preferably, in the step d, the back extraction time is 1-60 min, and the back extraction temperature is 30-70 ℃; more preferably, the stripping time is 30min and the stripping temperature is 60 ℃.
And (4) the organic phase D after back extraction is a regenerated extractant, and is preferably returned to the step a to be used as the extractant, so that the extractant can be recycled, and the production cost is reduced.
The water phase D after back extraction is MAP solution, and MAP solid can be prepared from the MAP solution by a conventional method.
Preferably, the MAP solid is prepared by any one of four methods:
the first is that the water phase D is concentrated and filtered to obtain filtrate E and filter cake E, the filter cake E is dried to obtain granular MAP, and the filtrate E returns to a back extraction or concentration working section;
the second is that the water phase D is directly cooled and crystallized, and is filtered to obtain filtrate F and filter cake F, the filter cake F is dried to obtain granular MAP, and the filtrate F returns to the back extraction section;
the third is that the water phase D is concentrated and spray dried to obtain powdery MAP;
the fourth is that the water phase D is directly sprayed and dried to obtain powdery MAP.
Preferably, the temperature of the cooling crystallization is 20-30 ℃, and more preferably the temperature of the cooling crystallization is 30 ℃.
The following examples are provided to further illustrate the embodiments of the present invention and are not intended to limit the scope of the present invention.
Example 1
a、P2O51000g of wet-process phosphoric acid with the content of 15.20 percent, TBP is used as an extracting agent, according to the proportion, the O/A is 3:1, namely the volume ratio of the extracting agent to the wet-process phosphoric acid is 3:1, the extraction reaction is carried out for 30 minutes at 55 ℃, and a water phase A and an organic phase A are obtained by phase separation;
b. adjusting the pH value of the water phase A to 2.9 by using lime milk, and filtering to obtain filter residue B and filtrate B;
c. adding calcium oxide into the filtrate B, controlling the pH value to be 5.6, controlling the reaction temperature to be 60 ℃, reacting for 1h, filtering to obtain a filter cake C and a filtrate C, circulating the filtrate C to a phosphoric acid ore pulp working section, and drying the filter cake C at 95 ℃ to obtain 94.5g of calcium phosphate product, wherein the product quality meets the I-type standard in GBT 22549-2008;
d. adding 10% ammonia water 434.6 as a stripping agent into the organic phase A, stirring, controlling the stripping temperature at 60 ℃, carrying out stripping for 30min, and carrying out phase separation to obtain an organic phase D and a water phase D, wherein the organic phase D is used as a regenerated extracting agent;
e. and (2) concentrating the water phase D, cooling and crystallizing at 30 ℃, filtering to obtain filtrate E and a filter cake E, returning the filtrate E to a concentration working section, and drying the filter cake E to obtain 144.39g of ammonium dihydrogen phosphate (MAP), wherein the concentration temperature is 80 ℃, the drying temperature is 80 ℃, the product quality meets the type I standard of ammonium phosphate in the standard HGT 4133-2010, and the total phosphorus yield is 83.1%.
The composition of the wet-process phosphoric acid is shown in table 1 (all weight percentages); the compositions of calcium hydrogen phosphate are shown in table 2 (all in weight percent); the composition of the ammonium dihydrogen phosphate is shown in Table 3 (all in weight percent).
Example 2
a、P2O51000g of wet-process phosphoric acid with the content of 25.02 percent, TBP is used as an extracting agent, according to the proportion, the O/A is 3:1, namely the volume ratio of the extracting agent to the wet-process phosphoric acid is 3:1, the extraction reaction is carried out for 30 minutes at the temperature of 60 ℃, and phase separation is carried out to obtain a water phase A and an organic phase A;
b. adjusting the pH value of the water phase A to 2.8 by using lime milk, and filtering to obtain filter residue B and filtrate B;
c. adding calcium oxide into the filtrate B, controlling the pH value of the filtrate B to be 5.5, controlling the reaction temperature to be 60 ℃, reacting for 1h, filtering to obtain a filter cake C and a filtrate C, circulating the filtrate C to a phosphoric acid ore pulp working section, and drying the filter cake C at 95 ℃ to obtain 184g of calcium phosphate product, wherein the product quality meets the I-type standard in GBT 22549-2008;
d. adding 617g of 10% ammonia water as a stripping agent into the organic phase A, stirring, controlling the stripping temperature at 60 ℃, carrying out stripping for 30min, and carrying out phase separation to obtain an organic phase D and a water phase D, wherein the organic phase D is used as a regenerated extracting agent;
e. and (3) spray drying the water phase D to obtain 200.6g of powdery ammonium dihydrogen phosphate (MAP), wherein the inlet air temperature of spray drying is 200 ℃, the feeding rate is 15ml/min, the product quality meets the I type standard of ammonium phosphate in the standard HGT 4133-2010, and the total phosphorus yield is 79.8%.
The composition of the wet-process phosphoric acid is shown in table 1 (all weight percentages); the compositions of calcium hydrogen phosphate are shown in table 2 (all in weight percent); the composition of the ammonium dihydrogen phosphate is shown in Table 3 (all in weight percent).
Example 3
a、P2O51000g of 43.72% wet process phosphoric acid using n-hexaneButanol is used as an extracting agent, according to the comparison, the O/A is 3:1, namely the volume ratio of the extracting agent to the wet-process phosphoric acid is 3:1, the extraction temperature is controlled at 60 ℃, the extraction time is 0.5h, and phase separation is carried out to obtain a water phase A and an organic phase A;
b. adjusting the pH value of the water phase A to 3.0 by using lime milk, and filtering to obtain filtrate B and filter residue B;
c. adding calcium oxide into the filtrate B, controlling the pH value of the filtrate B to be 6.5, controlling the reaction temperature to be 60 ℃, reacting for 1h, filtering to obtain a filter cake C and a filtrate C, circulating the filtrate C to a phosphoric acid ore pulp working section, and drying the filter cake C at 95 ℃ to obtain 257g of calcium phosphate product, wherein the product quality meets the I-type standard in GBT 22549-2008;
d. adding 807g of saturated ammonium bicarbonate solution at 60 ℃ into the organic phase A as a stripping agent, stirring, controlling the stripping temperature at 60 ℃, carrying out stripping for 30min, and carrying out phase separation to obtain an organic phase D and a water phase D, wherein the organic phase D is used as a regenerated extracting agent;
e. and cooling the water phase D to 30 ℃ for crystallization, filtering to obtain filtrate E and a filter cake E, returning the filtrate E to a back extraction section, and drying the filter cake E at 60 ℃ to obtain 428.9g of ammonium dihydrogen phosphate (MAP), wherein the product quality meets the type I standard of ammonium dihydrogen phosphate in the standard HGT 4133-2010, and the total phosphorus yield is 83.7%.
The composition of the wet-process phosphoric acid is shown in table 1 (all weight percentages); the compositions of calcium hydrogen phosphate are shown in table 2 (all in weight percent); the composition of the ammonium dihydrogen phosphate is shown in Table 3 (all in weight percent).
Example 4
a、P2O51000g of wet-process phosphoric acid with the content of 55.0 percent, using MIBK as an extracting agent, comparing, wherein O/A is 3:1, namely the volume ratio of the extracting agent to the wet-process phosphoric acid is 3:1, extracting and reacting for 30 minutes at 60 ℃, and separating phases to obtain a water phase A and an organic phase A;
b. adjusting the pH value of the water phase A to 2.8 by using lime milk, and filtering to obtain filter residue B and filtrate B;
c. adding calcium oxide into the filtrate B, controlling the pH value of the filtrate B to be 5.5, controlling the reaction temperature to be 60 ℃, reacting for 1h, filtering to obtain a filter cake C and a filtrate C, circulating the filtrate C to a phosphoric acid ore pulp working section, and drying the filter cake C at 95 ℃ to obtain 660g of a calcium phosphate product, wherein the product quality meets the type I standard in GBT 22549-2008;
d. adding 357g of 19% ammonia water into the organic phase A as a stripping agent, stirring, controlling the stripping temperature to be 60 ℃, carrying out stripping time to be 30min, and carrying out phase separation to obtain an organic phase D and a water phase D, wherein the organic phase D is used as a regenerated extracting agent;
e. and cooling the water phase D to 30 ℃ for crystallization, filtering to obtain filtrate E and a filter cake E, returning the filtrate E to a back extraction section, and drying the filter cake E at 60 ℃ to obtain 224.1g of ammonium dihydrogen phosphate (MAP), wherein the product quality meets the type I standard of ammonium phosphate in HGT 4133-2010, and the total phosphorus yield is 73.58%.
The composition of the wet-process phosphoric acid is shown in table 1 (all weight percentages); the compositions of calcium hydrogen phosphate are shown in table 2 (all in weight percent); the composition of the ammonium dihydrogen phosphate is shown in Table 3 (all in weight percent).
TABLE 1 phosphoric acid composition by wet process
| Example numbering | P2O5％ | F％ | Fe2O3％ | Al2O3％ | MgO％ | CaO％ | SO3％ |
| Example 1 | 15.20 | 0.85 | 0.56 | 0.54 | 0.72 | 0.25 | —— |
| Example 2 | 25.02 | 1.05 | 0.72 | 0.78 | 0.85 | 0.4 | 2.5 |
| Example 3 | 43.72 | 1.6 | 0.72 | 0.6 | 0.89 | 0.43 | —— |
| Example 4 | 55.0 | 1.69 | 0.78 | 0.80 | 0.85 | 0.46 | —— |
TABLE 2 composition of calcium Hydrogen phosphate
| Example numbering | P2O5％ | Ca％ | F％ |
| Example 1 | 40.96 | 23.07 | 0.10 |
| Example 2 | 40.84 | 23 | 0.18 |
| Example 3 | 41.83 | 22.98 | 0.16 |
| Example 4 | 40.86 | 23 | 0.18 |
TABLE 3 composition of ammonium dihydrogen phosphate
| Example numbering | P2O5％ | N％ | F％ |
| Example 1 | 60.78 | 11.99 | 0.005 |
| Example 2 | 60.80 | 11.89 | 0.002 |
| Example 3 | 60.78 | 11.99 | 0.005 |
| Example 4 | 60.81 | 11.97 | 0.003 |
Claims (15)
1. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrophosphate by using wet-process phosphoric acid is characterized by comprising the following steps of:
a. and (3) extraction: extracting wet-process phosphoric acid by using an extracting agent, and carrying out phase separation to obtain a water phase A and an organic phase A; wherein is wetP content in the process phosphoric acid is expressed as P2O515-60 wt%, the content of F is 0.15-1.8 wt%, and the extractant is at least one of organic amine extractant, organic ketone extractant, organic ester extractant, organic alcohol extractant and organic ether extractant;
b. defluorination and impurity removal: mixing the water phase A with a defluorinating agent, adjusting the pH to 2.5-3.0, and filtering to obtain a filtrate B and a white fertilizer; wherein the defluorinating agent is at least one of calcium oxide, calcium hydroxide and calcium carbonate;
c. preparing feed-grade DCP: mixing the filtrate B with a precipitator, adjusting the pH to 5.5-6.5, filtering to obtain filtrate C and filter cake C, and drying the filter cake C to obtain feed-grade DCP; the precipitant is at least one of calcium oxide and calcium hydroxide;
d. back extraction: mixing the organic phase A with a stripping agent for stripping, and splitting phases to obtain an organic phase D and a water phase D; the stripping agent is at least one of ammonia water, ammonium bicarbonate and ammonium carbonate solution; the water phase D is MAP solution;
preparation of MAP: solid MAP was prepared from aqueous phase D.
2. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 1, wherein the method comprises the following steps: in the step a, the extractant is tributyl phosphate, TBP-cyclohexane, n-butanol, n-octanol, cyclohexanol, benzyl alcohol, isoamyl alcohol, methyl isobutyl ketone, isobutyl acetate, isoamyl acetate, diisopropyl ether, diethyl ether or trioctyl tertiary amine.
3. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 1, wherein the method comprises the following steps: in the step a, the volume ratio of the extracting agent to the wet-process phosphoric acid is 1-3: 1.
4. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 3, wherein the method comprises the following steps: in the step a, the volume ratio of the extracting agent to the wet-process phosphoric acid is 3: 1.
5. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 1, wherein the method comprises the following steps: in the step a, the extraction time is 1-60 min, and the extraction temperature is 30-70 ℃.
6. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 5, wherein the steps of: in the step a, the extraction time is 30min, and the extraction temperature is 60 ℃.
7. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 1, wherein the method comprises the following steps: in the step b, the reaction temperature is 30-100 ℃, and in the step c, the reaction temperature is 30-100 ℃.
8. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 7, wherein the steps of: in the step b, the reaction temperature is 60 ℃, and in the step c, the reaction temperature is 60 ℃.
9. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 1, wherein the method comprises the following steps: in step d, NH in the stripping agent4 +With P in the organic phase A2O5The molar ratio of (A) to (B) is 1.5-2.5: 1.
10. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 9, wherein the steps of: in step d, NH in the stripping agent4 +With P in the organic phase A2O5In a molar ratio of 2: 1.
11. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 1, wherein the method comprises the following steps: in the step d, the back extraction time is 1-60 min, and the back extraction temperature is 30-70 ℃.
12. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 11, wherein the steps of: in the step d, the back extraction time is 30min, and the back extraction temperature is 60 ℃.
13. The method for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by using wet-process phosphoric acid according to claim 1, wherein the method comprises the following steps: in step e, solid MAP is prepared from the aqueous phase D by the following method:
concentrating the water phase D, filtering to obtain a filtrate E and a filter cake E, drying the filter cake E to obtain granular MAP, and returning the filtrate E to a back extraction or concentration section;
or directly cooling and crystallizing the water phase D, filtering to obtain a filtrate F and a filter cake F, drying the filter cake F to obtain granular MAP, and returning the filtrate F to a back extraction section;
or concentrating the water phase D, and spray drying to obtain powdery MAP;
or directly spray-drying the water phase D to obtain the powdery MAP.
14. The process for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by wet process phosphoric acid according to claim 13, wherein: the temperature of cooling crystallization is 20-30 ℃.
15. The process for co-producing ammonium dihydrogen phosphate and feed-grade calcium hydrogen phosphate by wet process phosphoric acid according to claim 14, wherein: the temperature of the cooling crystallization is 30 ℃.
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