CN118343703A - Method for producing high-purity ammonium phosphate solution and co-producing industrial grade MAP by raffinate acid - Google Patents

Abstract

The invention relates to a method for producing high-purity ammonium phosphate solution and co-producing industrial grade MAP by raffinate acid, belonging to the technical field of chemical industry. The method for producing the high-purity ammonium phosphate solution by using the raffinate acid comprises the following steps: A. extraction 1: extracting raffinate acid by using a metal cation extractant A, and separating phases after extraction to obtain an oil phase 1 and a water phase 1, wherein the extraction in the step A is three-stage countercurrent extraction with the number of stages of 2-10 stages; B. concentrating: concentrating the water phase 1; C. extraction 2: extracting the raffinate acid concentrated in the step B by using an extractant B, and separating phases after extraction to obtain an oil phase 2 and a water phase 2, wherein the water phase 2 returns to the raffinate acid in the step A, and the extractant B is at least one of lipids, sulfoxides, organic phosphates, organic ketones, organic alcohols and organic alkaline extractants; D. and back extraction 2. The invention can produce high-purity ammonium phosphate solution and industrial grade MAP by using the raffinate acid, thereby realizing the high-value utilization of the raffinate acid.

Description

Method for producing high-purity ammonium phosphate solution and co-producing industrial-grade MAP by extracting raffinate

Technical Field

The invention relates to a method for producing high-purity ammonium phosphate solution and co-producing industrial-grade MAP by extracting raffinate, and belongs to the technical field of chemical industry.

Background technique

Monoammonium phosphate is an important raw material for industrial production, widely used in compound fertilizers, battery materials, flame retardants, fire extinguishing agents, food additives and other fields, with a large market demand. However, with the exploitation and utilization of phosphate resources, the quality of raw ore has declined year by year, resulting in a decrease in the _P2O5 content and a high _impurity content in wet-process phosphoric acid. The Ca, Fe, Al, Mg, F and other ion impurities contained in the raw ore impurities seriously affect the product quality, increase the purification difficulty and production cost in the subsequent product processing and production process, and make it difficult to balance product quality and production cost.

Raffinate acid is a raffinate acid containing a large amount of metal ion impurities produced during the concentration and purification of dilute phosphoric acid or concentrated phosphoric acid. With the continuous exploitation of phosphate resources and the decline in the quality of phosphate ore, the slag acid and raffinate acid produced in the process of refined phosphoric acid also increase. In addition to the effective ingredient _P2O5 , the raffinate acid also contains impurities such as ^{Fe3 +} , Al3 ⁺ , Mg2 ⁺ , ^F- , _SO42- , etc. _{The P2O5} content in the raffinate acid can be as high as 40% or more, _which is similar to wet-process phosphoric acid, but its metal ion Fe3 ⁺ , Al3 ⁺ , ^Mg2 + and solid content are higher than those of wet-process phosphoric acid. Due to the high content of Mg2 ⁺ and Al3 ⁺ in the raffinate acid, it has high viscosity and is difficult to handle, which limits the efficient utilization of the raffinate acid and is also a major problem in improving the utilization rate of phosphate ore.

The industrial production of monoammonium phosphate mainly includes two preparation methods: thermal phosphoric acid ammonium neutralization method and wet phosphoric acid ammonium neutralization method. The thermal phosphoric acid ammonium neutralization method is to adjust the pH to 4.2-4.6 by introducing ammonia into 50%-55% thermal phosphoric acid by mass, filter while hot, cool and crystallize, separate and dry to obtain the finished product. However, the use of thermal phosphoric acid to produce monoammonium phosphate has high requirements on the quality of phosphate ore, the production process is relatively cumbersome, the production energy consumption is high, the pollution is large and the cost is high, and its application is limited. The use of wet phosphoric acid as a raw material to prepare monoammonium phosphate requires first purifying the ionic impurities in the wet phosphoric acid, and then introducing ammonia for neutralization, separation, concentration, crystallization, and drying. Compared with thermal phosphoric acid, wet phosphoric acid has a low production cost, but this method is accompanied by the production of _raffinate acid, resulting in a large loss of _P2O5 . In addition, due to the high content of impurity ions in wet phosphoric acid, the viscosity of the raw materials changes greatly during the ammonia neutralization process, and insoluble or poorly soluble substances such as magnesium ammonium phosphate, calcium hydrogen phosphate, and ammonium hexafluorosilicate are easily generated, which is not conducive to transportation and filtration, affecting product quality.

The invention patent application with application number CN2023104356279 discloses a method for preparing high-quality industrial-grade monoammonium phosphate, which comprises reacting wet-process phosphoric acid and phosphate rock powder and filtering them, adding sodium carbonate and filtering them for defluorination, filtering the filtrate into a water tank device provided with a chelating resin, and then sending the filtrate to a neutralization and concentration machine to pass nitrogen to obtain ammonium phosphate slurry, concentrating and crystallizing the slurry, separating and drying, and obtaining industrial-grade monoammonium phosphate. However, this method produces a large amount of filter residue, and fluorine resources are not effectively utilized. The use of chelating resin to remove metal ions has a small treatment capacity and high cost, making it difficult to achieve industrial production.

The invention patent application with application number CN2021115542845 discloses a method for producing industrial phosphoric acid and co-producing ammonium polyphosphate or solid phosphoric acid by wet phosphoric acid. The method includes pretreatment, removal of metal ions, decolorization, concentration, extraction, washing, stripping and concentration of the extract phase to obtain industrial-grade phosphoric acid, and the raffinate acid produces ammonium polyphosphate or is used to produce solid phosphoric acid. The present invention concentrates the purified acid from which metal ions are removed into a high-concentration anhydrous phosphoric acid and then enters the phosphoric acid extraction section. The raffinate acid can be directly used as a raw material for producing water-soluble APP liquid fertilizer without concentration, thereby realizing the high added value utilization of the raffinate acid. The phosphoric acid extraction process is extremely efficient, does not require multi-stage countercurrent extraction, has a high phosphorus yield, and has a high extraction rate. The industrial phosphoric acid obtained has high purity and few impurities. However, it is necessary to concentrate the purified acid from which metal ions are removed into a high-concentration anhydrous phosphoric acid and then enter the phosphoric acid extraction section, which consumes a lot of energy.

The invention patent application with application number 201210203327X discloses a method for producing industrial monoammonium phosphate and fertilizer-grade monoammonium phosphate by using raffinate acid. In this method, raffinate acid and ammonia are reacted in proportion, and metal ions and ammonia generate a stable citric acid-soluble precipitate containing fluorine. The separated filtrate is concentrated, crystallized, centrifuged, dried, packaged and other processes to obtain an industrial-grade monoammonium phosphate product; the filter residue is re-pulped with crude phosphoric acid and reacted with ammonia in proportion, concentrated, granulated, dried and other processes to obtain a fertilizer-grade monoammonium phosphate product. In the method of the present invention, the modified residue is re-pulped with phosphoric acid and reacted with ammonia to produce fertilizer-grade monoammonium phosphate (or diammonium phosphate), thereby realizing the graded utilization of raffinate acid. However, the viscosity of the raffinate acid in this method is large, and the citric acid-soluble precipitate generated with ammonia is difficult to filter, making it difficult to carry out industrial operation. In addition, the metal ions in the raffinate acid are not treated, and the impurity content of the obtained fertilizer-grade monoammonium phosphate is high.

The invention patent application with application number 2018102016977 discloses a method and device for producing monoammonium phosphate products by adding raffinate acid and slag acid to dilute phosphoric acid. The method produces monoammonium phosphate by adding raffinate acid, slag acid and phosphorus-containing wastewater generated in the production process of monoammonium phosphate to dilute phosphoric acid. The raffinate acid and slag acid are mixed with dilute phosphoric acid in an acid preparation tank to obtain a mixed acid, and the mixed acid reacts with gaseous ammonia to form a slurry, which is then concentrated, high-pressure powdered and dried to produce monoammonium phosphate. This patent reduces the amount of dilute phosphoric acid used and realizes the comprehensive utilization of raffinate acid and slag acid, but the metal ions in the raw acid are not treated, so it is difficult to obtain high-purity monoammonium phosphate.

Summary of the invention

The first object of the present invention is to provide a new method for producing high-purity ammonium phosphate by using raffinate acid.

To achieve the first object of the present invention, the method comprises:

A. Extraction 1: extracting the raffinate with metal cation extractant A, and separating the phases to obtain oil phase 1 and water phase 1 after extraction. The extraction in step A is 2 to 10 stages of three-stage countercurrent extraction;

B. Concentration: Concentrating the aqueous phase 1;

C. Extraction 2: extracting the concentrated raffinate in step B with an extractant B, separating the phases to obtain an oil phase 2 and an aqueous phase 2, and returning the aqueous phase 2 to the raffinate in step A, wherein the extractant B is at least one of lipids, sulfoxides, organic phosphates, organic ketones, organic alcohols, and organic alkaline extractants;

D. Stripping 2: Stripping the oil phase 2 with liquid ammonia to obtain an oil phase 3 and an aqueous phase 3 by phase separation. The aqueous phase 3 is a high-purity ammonium phosphate solution.

High-purity ammonium phosphate solution refers to an ammonium phosphate solution with a total impurity ion content of less than 600ppm and a purity of more than 70%.

In a specific embodiment, the extractant A in step A includes at least one of an organic phosphorus extractant, an organic phosphine extractant, an organic sulfonic acid extractant, an organic carboxylic acid extractant, and a tertiary carbonic acid extractant; preferably, the extractant A is at least one of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate 2-ethylhexyl ester, di(2,4,4-trimethylpentyl) hypophosphorous acid, 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester, N,N-N-octylamine dimethylenephenylphosphonic acid, N,N-N-hexylamine dimethylenephenylphosphonic acid, toluenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, xylenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, cinnamic acid, fatty acid, lauric acid, and cycloalkane acid.

In a specific embodiment, the extractant B is at least one of trialkylmethylamine, didecylamine, trioctylamine, trinonylamine, ethyl acetate, amyl acetate, butyl acetate, dioctyl sulfoxide, diphenyl sulfoxide, alkyl sulfoxide, di(2-ethylhexyl)hexyl phosphate, dioctyl octyl phosphate, tributyl phosphate, methyl isobutyl ketone, cyclohexanone, isopentanol, secondary octanol, and substituted primary alcohols.

In a specific embodiment, the main elements in the raffinate acid in step A are calculated as their oxides: _P2O5 content is _30wt .%-60wt.%, _Al2O3 content is 0.5wt.%-10wt.%, MgO content is 0.5wt.%- _10wt .%, _Fe2O3 content is 0.1wt.%-5wt.%, CaO content is 0.1wt.%-1wt.%, _and F content is 0.1wt.%-2wt.%.

In a specific embodiment, the extraction temperature in step A is 25-85° C., the volume ratio O/A is 1-10:1, and the number of stages is preferably 3.

In a specific embodiment, the concentration temperature in step B is 60-90°C, and the concentration of raffinate P ₂ O ₅ at the concentration endpoint is 40 wt.%-60 wt.%.

In a specific embodiment, the extraction 2 in step C is 1 to 3 stages of countercurrent extraction; the number of stages of extraction 2 is preferably 1 stage, the extraction temperature is preferably 25 to 85° C., and the volume ratio O/A is 1 to 10:1;

The method further comprises oil-water separation 3: oil phase 2 is subjected to oil-water separation, the separated water phase is incorporated into water phase 2, and the separated organic phase is put into step D.

In a specific embodiment, the stripping temperature in step D is 25 to 85° C., and the volume ratio of O/A is 1 to 10:1; the phase separation in step D is preferably performed at 25 to 85° C.;

The method further comprises oil-water separation 4: performing oil-water separation on the aqueous phase 3 to obtain a high-purity ammonium phosphate solution, and the separated organic phase is incorporated into the oil phase 3;

Oil-water separation 5: The oil phase 3 is subjected to oil-water separation, the separated water phase is incorporated into the high-purity ammonium phosphate solution, and the separated oil phase is returned to be recycled as the extractant 2.

In a specific embodiment, the method further comprises treating the oil phase 1: adding a stripping agent A to the oil phase 1 to strip metal cations in the oil phase 1 to obtain an oil phase 4 and an aqueous phase 4, wherein the oil phase 4 is returned to step A for recycling as an extractant A, and the aqueous phase 4 is returned for recycling as a stripping agent A; the stripping agent A is preferably at least one of an ammonium oxalate solution and a mixed solution of ammonium oxalate and ammonium sulfate, and the ammonium oxalate concentration in the stripping agent A is preferably 1 wt.% to 20 wt.%, and the ammonium sulfate concentration is 0 wt.% to 35 wt.%;

A more preferred method further comprises: oil-water separation 1: separating oil phase 4 from water, and merging the separated water phase into water phase 4; oil-water separation 2: separating oil phase 1 from water phase 1, and merging the separated oil phase into oil phase 1, and entering step B for the separated water phase.

The second object of the present invention is to provide a novel method for producing industrial-grade MAP.

To achieve the second object of the present invention, the method comprises:

The high-purity ammonium phosphate solution is cooled and crystallized, and solid-liquid separation is performed to obtain industrial-grade MAP, and the crystallization mother liquor is returned to stripping 2; the crystallization temperature is 0-30°C, and the crystallization is preferably carried out under stirring at 200-500r/min; the high-purity ammonium phosphate solution is prepared by the above-mentioned method for producing high-purity ammonium phosphate solution by extracting raffinate; the purity of the industrial-grade MAP is above 97.56%, preferably above 99.23%.

Beneficial effects:

1. The present invention adopts a specific extraction and stripping method to separate a high-purity ammonium phosphate solution from the residual acid. The extractant can be recycled after stripping, and various metal ions in phosphoric acid can be effectively separated, which can avoid the generation of insoluble substances such as magnesium ammonium phosphate that affect product quality.

2. The present invention adopts cooling crystallization of high-purity ammonium phosphate solution to directly obtain industrial monoammonium phosphate, without the need for impurity removal, thereby reducing production costs.

3. The present invention adopts raffinate as a raw material to prepare a high-purity ammonium phosphate solution, thereby realizing high-value utilization of raffinate.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a process flow chart of a specific embodiment of the present invention.

Detailed ways

To achieve the first object of the present invention, the method comprises:

A. Extraction 1: extracting the raffinate with metal cation extractant A, and separating the phases to obtain oil phase 1 and water phase 1 after extraction. The extraction in step A is 2 to 10 stages of three-stage countercurrent extraction;

B. Concentration: Concentrating the aqueous phase 1;

C. Extraction 2: extracting the concentrated raffinate in step B with an extractant B, separating the phases to obtain an oil phase 2 and an aqueous phase 2, and returning the aqueous phase 2 to the raffinate in step A, wherein the extractant B is at least one of lipids, sulfoxides, organic phosphates, organic ketones, organic alcohols, and organic alkaline extractants;

D. Stripping 2: Stripping the oil phase 2 with liquid ammonia to obtain an oil phase 3 and an aqueous phase 3 by phase separation. The aqueous phase 3 is a high-purity ammonium phosphate solution.

High-purity ammonium phosphate solution refers to an ammonium phosphate solution with a total impurity ion content of less than 600ppm and a purity of more than 70%.

In a specific embodiment, the extractant A in step A includes at least one of an organic phosphorus extractant, an organic phosphine extractant, an organic sulfonic acid extractant, an organic carboxylic acid extractant, and a tertiary carbonic acid extractant; preferably, the extractant A is at least one of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate 2-ethylhexyl ester, di(2,4,4-trimethylpentyl) hypophosphorous acid, 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester, N,N-N-octylamine dimethylenephenylphosphonic acid, N,N-N-hexylamine dimethylenephenylphosphonic acid, toluenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, xylenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, cinnamic acid, fatty acid, lauric acid, and cycloalkane acid.

In a specific embodiment, the extractant B is at least one of trialkylmethylamine, didecylamine, trioctylamine, trinonylamine, ethyl acetate, amyl acetate, butyl acetate, dioctyl sulfoxide, diphenyl sulfoxide, alkyl sulfoxide, di(2-ethylhexyl)hexyl phosphate, dioctyl octyl phosphate, tributyl phosphate, methyl isobutyl ketone, cyclohexanone, isopentanol, secondary octanol, and substituted primary alcohols.

In a specific embodiment, the main elements in the raffinate acid in step A are calculated as their oxides: _P2O5 content is _30wt .%-60wt.%, _Al2O3 content is 0.5wt.%-10wt.%, MgO content is 0.5wt.%- _10wt .%, _Fe2O3 content is 0.1wt.%-5wt.%, CaO content is 0.1wt.%-1wt.%, _and F content is 0.1wt.%-2wt.%.

In a specific embodiment, the extraction temperature in step A is 25-85° C., the volume ratio O/A is 1-10:1, and the number of stages is preferably 3.

In a specific embodiment, the concentration temperature in step B is 60-90°C, and the concentration of raffinate P ₂ O ₅ at the concentration endpoint is 40 wt.%-60 wt.%.

In a specific embodiment, the extraction 2 in step C is 1 to 3 stages of countercurrent extraction; the number of stages of extraction 2 is preferably 1 stage, the extraction temperature is preferably 25 to 85° C., and the volume ratio O/A is 1 to 10:1;

The method further comprises oil-water separation 3: oil phase 2 is subjected to oil-water separation, the separated water phase is incorporated into water phase 2, and the separated organic phase is put into step D.

In a specific embodiment, the stripping temperature in step D is 25 to 85° C., and the volume ratio of O/A is 1 to 10:1; the phase separation in step D is preferably performed at 25 to 85° C.;

The method further comprises oil-water separation 4: performing oil-water separation on the aqueous phase 3 to obtain a high-purity ammonium phosphate solution, and the separated organic phase is incorporated into the oil phase 3;

Oil-water separation 5: The oil phase 3 is subjected to oil-water separation, the separated water phase is incorporated into the high-purity ammonium phosphate solution, and the separated oil phase is returned to be recycled as the extractant 2.

In a specific embodiment, the method further comprises treating the oil phase 1: adding a stripping agent A to the oil phase 1 to strip metal cations in the oil phase 1 to obtain an oil phase 4 and an aqueous phase 4, wherein the oil phase 4 is returned to step A for recycling as an extractant A, and the aqueous phase 4 is returned for recycling as a stripping agent A; the stripping agent A is preferably at least one of an ammonium oxalate solution and a mixed solution of ammonium oxalate and ammonium sulfate, and the ammonium oxalate concentration in the stripping agent A is preferably 1 wt.% to 20 wt.%, and the ammonium sulfate concentration is 0 wt.% to 35 wt.%;

A more preferred method further comprises: oil-water separation 1: separating oil phase 4 from water, and merging the separated water phase into water phase 4; oil-water separation 2: separating oil phase 1 from water phase 1, and merging the separated oil phase into oil phase 1, and entering step B for the separated water phase.

The second object of the present invention is to provide a novel method for producing industrial-grade MAP.

To achieve the second object of the present invention, the method comprises:

The high-purity ammonium phosphate solution is cooled and crystallized, and solid-liquid separation is performed to obtain industrial-grade MAP, and the crystallization mother liquor is returned to stripping 2; the crystallization temperature is 0-30°C, and the crystallization is preferably carried out under stirring at 200-500r/min; the high-purity ammonium phosphate solution is prepared by the above-mentioned method for producing high-purity ammonium phosphate solution by extracting raffinate; the purity of the industrial-grade MAP is above 97.56%, preferably above 99.23%.

The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

Example 1

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The raffinate having _{a P2O5 content} of 44.67wt.%, _{an Al2O3 content} of 3.2wt.%, a MgO content of 3.02wt.%, _{a Fe2O3 content} of 0.3wt.%, a CaO content of 0.1wt.%, and a F content of 0.2wt.% was subjected to three-stage three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain an oil phase 1 and an aqueous phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: Using a mixed solution of ammonium oxalate and ammonium sulfate as stripping agent A, wherein the concentration of ammonium oxalate is 5 wt.%, and the concentration of ammonium sulfate is 35 wt.%, the oil phase 1 loaded with metal ions is subjected to two-stage three-stage countercurrent stripping, the temperature of each stripping stage is 60°C, the phase volume ratio O/A is 1:3, phase separation, oil-water separation, the oil phase is recycled as a regenerated extractant, and the water phase is mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator with the concentration temperature maintained at 60° C. to a phosphoric acid concentration of 50 wt.%.

(4) Extraction 2: Trioctylamine was used as the extractant B to perform a first-stage countercurrent extraction on the concentrated clear liquid. The extraction temperature was 60°C and the phase volume ratio O/A was 2:1. After phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. The aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 60°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Example 2

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The _raffinate with _{a P2O5} content of 44.55wt.%, _{an Al2O3 content of} 3.0wt.%, a MgO content of 2.9wt.%, _{a Fe2O3} content of 0.3wt.%, a CaO content of 0.1wt.%, and a F content of 0.2wt.% was subjected to three-stage three-stage countercurrent extraction with 2-ethylhexyl phosphate to obtain an oil phase 1 and an aqueous phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: A mixed solution of ammonium oxalate and ammonium sulfate was used as stripping agent A, wherein the concentration of ammonium oxalate was 5 wt.%, and the concentration of ammonium sulfate was 35 wt.%. The oil phase 1 loaded with metal ions was subjected to a three-stage countercurrent stripping. The temperature of each stripping stage was 60° C. The phase volume ratio O/A was 1:3. The phases were separated and the oil and water were separated. The oil phase was recycled as a regenerated extractant, and the water phase was mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator maintained at 60° C. to a phosphoric acid concentration of 50 wt.%.

(4) Extraction 2: TBP (tributylphosphine) was used as the extractant B to perform a first-stage countercurrent extraction on the filtered clear liquid. The extraction temperature was 60°C, the phase volume ratio O/A was 2:1, and after phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. The aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 60°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Example 3

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The raffinate with _{a P2O5 content} of 44.68wt.%, _{an Al2O3 content} of 3.3wt.%, a MgO content of 2.9wt.%, _{a Fe2O3} content of 0.3wt.%, a CaO content of 0.1wt.%, and a F content of 0.2wt.% was subjected to three-stage three-stage countercurrent extraction with N,NN-n-octylamine dimethylenephenylphosphonic acid to obtain an oil phase 1 and an aqueous phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: Using a mixed solution of ammonium oxalate and ammonium sulfate as stripping agent A, wherein the concentration of ammonium oxalate is 5 wt.%, and the concentration of ammonium sulfate is 35 wt.%, the oil phase 1 loaded with metal ions is subjected to two-stage three-stage countercurrent stripping, the temperature of each stripping stage is 60°C, the phase volume ratio O/A is 1:3, phase separation, oil-water separation, the oil phase is recycled as a regenerated extractant, and the water phase is mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator, the concentration temperature was maintained at 60°C, and the concentration was concentrated to a phosphoric acid concentration of 50 wt.%.

(4) Extraction 2: MIBK (methyl isobutyl ketone) was used as the extractant B to perform a first-stage countercurrent extraction on the filtered clear liquid. The extraction temperature was 60°C, the phase volume ratio O/A was 2:1, and after phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. The aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 60°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Example 4

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The raffinate having _{a P2O5 content} of 40.97wt.%, _{an Al2O3} content of 2.5wt.%, a MgO content of 2.1wt.%, _{a Fe2O3} content of 0.4wt.%, a CaO content of 0.4wt.%, and a F content of 0.2wt.% was subjected to three-stage three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain an aqueous phase 1 and an oil phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: Using a mixed solution of ammonium oxalate and ammonium sulfate as stripping agent A, wherein the concentration of ammonium oxalate is 5 wt.%, and the concentration of ammonium sulfate is 35 wt.%, the oil phase 1 loaded with metal ions is subjected to two-stage three-stage countercurrent stripping, the temperature of each stripping stage is 60°C, the phase volume ratio O/A is 1:3, phase separation, oil-water separation, the oil phase is recycled as a regenerated extractant, and the water phase is mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator, the concentration temperature was maintained at 60°C, and the concentration was concentrated to a phosphoric acid concentration of 50 wt.%.

(4) Extraction 2: Using trioctylamine as the extractant B, the filtered clear liquid was subjected to a first-stage countercurrent extraction at an extraction temperature of 60°C and a phase volume ratio of O/A of 2:1. After phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. Aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 60°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Example 5

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The raffinate having _{a P2O5 content} of 48.26wt.%, _{an Al2O3} content of 3.5wt.%, a MgO content of 3.0wt.%, _{a Fe2O3} content of 0.4wt.%, a CaO content of 0.4wt.%, and a F content of 0.1wt.% was subjected to three-stage three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain an aqueous phase 1 and an oil phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: Using a mixed solution of ammonium oxalate and ammonium sulfate as stripping agent A, wherein the concentration of ammonium oxalate is 5 wt.%, and the concentration of ammonium sulfate is 35 wt.%, the oil phase 1 loaded with metal ions is subjected to two-stage three-stage countercurrent stripping, the temperature of each stripping stage is 60°C, the phase volume ratio O/A is 1:3, phase separation, oil-water separation, the oil phase is recycled as a regenerated extractant, and the water phase is mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator with the concentration temperature maintained at 60° C. to a phosphoric acid concentration of 50 wt.%.

(4) Extraction 2: Using trioctylamine as the extractant B, the filtered clear liquid was subjected to a first-stage countercurrent extraction at an extraction temperature of 60°C and a phase volume ratio O/A of 2:1. After phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. Aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 60°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Example 6

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The raffinate having _{a P2O5 content} of 44.67wt.%, _{an Al2O3} content of 3.0wt.%, a MgO content of 3.0wt.%, _{a Fe2O3} content of 0.3wt.%, a CaO content of 0.2wt.%, and a F content of 0.2wt.% was subjected to three-stage three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain an aqueous phase 1 and an oil phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: Using a mixed solution of ammonium oxalate and ammonium sulfate as stripping agent A, wherein the concentration of ammonium oxalate is 5 wt.%, and the concentration of ammonium sulfate is 35 wt.%, the oil phase 1 loaded with metal ions is subjected to two-stage three-stage countercurrent stripping, the temperature of each stripping stage is 60°C, the phase volume ratio O/A is 1:3, phase separation, oil-water separation, the oil phase is recycled as a regenerated extractant, and the water phase is mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator with the concentration temperature maintained at 60° C. to a phosphoric acid concentration of 50 wt.%.

(4) Extraction 2: Using dioctyl sulfoxide as the extractant B, the filtered clear liquid was subjected to a first-stage countercurrent extraction at an extraction temperature of 60°C and a phase volume ratio O/A of 2:1. After phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. Aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 70°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 10°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Example 7

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The raffinate having _{a P2O5 content} of 44.67wt.%, _{an Al2O3} content of 3.0wt.%, a MgO content of 3.0wt.%, _{a Fe2O3} content of 0.3wt.%, a CaO content of 0.2wt.%, and a F content of 0.1wt.% was subjected to three-stage three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain an oil phase 1 and an aqueous phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: Using a mixed solution of ammonium oxalate and ammonium sulfate as stripping agent A, wherein the concentration of ammonium oxalate is 5 wt.%, and the concentration of ammonium sulfate is 35 wt.%, the oil phase 1 loaded with metal ions is subjected to two-stage three-stage countercurrent stripping, the temperature of each stripping stage is 60°C, the phase volume ratio O/A is 1:3, phase separation, oil-water separation, the oil phase is recycled as a regenerated extractant, and the water phase is mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator at a temperature of 80° C. until the phosphoric acid concentration was 60 wt.%.

(4) Extraction 2: Tributyl phosphate was used as the extractant B, and the filtered clear liquid was subjected to a two-stage countercurrent extraction at an extraction temperature of 60°C and a phase volume ratio of O/A of 1:1. After phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. Aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 70°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 10°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Comparative Example 1

As shown in FIG1 , a method for producing high-purity ammonium phosphate solution and industrial-grade MAP by extracting raffinate acid comprises the following steps:

(1) Extraction 1: The raffinate with _{a P2O5 content} of 44.67wt.%, _{an Al2O3 content} of 3.3wt.%, a MgO content of 2.8wt.%, _{a Fe2O3} content of 0.3wt.%, a CaO content of 0.2wt.%, and a F content of 0.1wt.% was subjected to a one-stage two-stage countercurrent extraction using trioctylamine as an extractant at an extraction temperature of 60°C and a phase volume ratio of O/A of 2:1. After phase separation and oil-water separation, an aqueous phase and an oil phase were obtained.

(2) Stripping 1: Liquid ammonia is added to the oil phase for stripping. The stripping temperature is 60°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated oil is recycled as a regenerated extractant.

(3) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Comparative Example 2

(1) Extraction 1: The _raffinate with _{a P2O5} content of 44.52wt.%, _{an Al2O3 content of} 3.2wt.%, a MgO content of 2.9wt.%, _{a Fe2O3} content of 0.3wt.%, a CaO content of 0.2wt.%, and a F content of 0.1wt.% was subjected to a three-stage countercurrent extraction with 2-ethylhexyl phosphate to obtain an aqueous phase 1 and an oil phase 1. The extraction temperature of each stage was 60°C, and the phase volume ratio O/A was 4:1.

(2) Stripping 1: A mixed solution of ammonium oxalate and ammonium sulfate was used as stripping agent A, wherein the concentration of ammonium oxalate was 5 wt.%, and the concentration of ammonium sulfate was 35 wt.%. The oil phase 1 loaded with metal ions was subjected to a three-stage countercurrent stripping. The temperature of each stripping stage was 60° C. The phase volume ratio O/A was 1:3. The phases were separated and the oil and water were separated. The oil phase was recycled as a regenerated extractant, and the water phase was mixed with the stripping agent and recycled.

(3) Concentration: The aqueous phase 1 was concentrated in a vacuum evaporator maintained at 60° C. to a phosphoric acid concentration of 50 wt.%.

(4) Extraction 2: TBP (tributylphosphine) was used as the extractant B to perform a first-stage countercurrent extraction on the filtered clear liquid. The extraction temperature was 60°C, the phase volume ratio O/A was 2:1, and after phase separation and oil-water separation, aqueous phase 2 and oil phase 2 were obtained. The aqueous phase 2 was returned to the raffinate acid for extraction.

(5) Stripping 2: Liquid ammonia is added to the oil phase 2 for stripping. The stripping temperature is 60°C. The volume ratio of O/A is 1:1. After phase separation and oil-water separation, NH ₄ H ₂ PO ₄ solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

(6) Cooling crystallization: High-purity NH ₄ H ₂ PO ₄ solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20°C. Industrial MAP is obtained by filtration and drying. The mother liquor of crystallization is returned to stripping 2.

In this example, ammonium phosphate solution and industrial MAP were prepared. The MER values and product purities thereof are shown in Table 1.

Table 1 Fluorine content, MER value and product purity in each embodiment and comparative example

In the above table, the concentration of ammonium phosphate solution is the mass concentration of the obtained NH ₄ H ₂ PO ₄ solution. The purity of industrial MAP is the purity of the product used to prepare industrial monoammonium phosphate.

Claims (10)

1. A method for producing a high purity ammonium phosphate solution from raffinate, the method comprising:

A. Extraction 1: extracting raffinate acid by using a metal cation extractant A, and separating phases after extraction to obtain an oil phase 1 and a water phase 1, wherein the extraction in the step A is 2-10 sections of three-stage countercurrent extraction;

B. concentrating: concentrating the water phase 1;

C. Extraction 2: extracting the raffinate acid concentrated in the step B by using an extractant B, and separating phases after extraction to obtain an oil phase 2 and a water phase 2, wherein the water phase 2 returns to the raffinate acid in the step A, and the extractant B is at least one of lipids, sulfoxides, organic phosphates, organic ketones, organic alcohols and organic alkaline extractants;

D. Back extraction 2: and (3) carrying out back extraction on the oil phase 2 by adopting liquid ammonia, and carrying out phase separation to obtain an oil phase 3 and a water phase 3, wherein the water phase 3 is the high-purity ammonium phosphate solution.

2. The method for producing a high-purity ammonium phosphate solution from raffinate acid as claimed in claim 1, wherein the extractant a in the step a comprises at least one of an organic phosphorus extractant, an organic phosphine extractant, an organic sulfonic acid extractant, an organic carboxylic acid extractant, and a tertiary carbonic acid extractant; preferably, the extractant A is at least one of di (2-ethylhexyl) phosphate, 2-ethylhexyl phosphate, di (2, 4-trimethylpentyl) hypophosphorous acid, 2-ethylhexyl phosphonic acid mono (2-ethylhexyl) ester, N-N-N-Xin Aner methylenephenylphosphonic acid, N-N-hexylamine dimethylene phenylphosphonic acid, toluene sulfonic acid, p-toluene sulfonic acid, benzene sulfonic acid, xylene sulfonic acid, dodecylbenzene sulfonic acid, dinonylnaphthalene sulfonic acid, cinnamic acid, fatty acids, lauric acid, and naphthenic acid.

3. The method for producing a high purity ammonium phosphate solution from raffinate acid according to claim 1, wherein the extractant B is at least one of trialkylmethylamine, didecylamine, trioctylamine, trisnonylamine, ethyl acetate, amyl acetate, butyl acetate, dioctylsulfoxide, diphenyl sulfoxide, hydrocarbon sulfoxide, di (2-ethylhexyl) hexyl phosphate, dioctyl octyl phosphate, tributyl phosphate, methyl isobutyl ketone, cyclohexanone, isoamyl alcohol, sec-octyl alcohol, substituted primary alcohol.

4. The method for producing a high purity ammonium phosphate solution from a raffinate acid according to claim 1 or 2, wherein the main elements in the raffinate acid in step a are calculated as oxides: 30 to 60 percent of P ₂O₅, 0.5 to 10 percent of Al ₂O₃, 0.5 to 10 percent of MgO, 0.1 to 5 percent of Fe ₂O₃, 0.1 to 1 percent of CaO and 0.1 to 2 percent of F.

5. The method for producing high-purity ammonium phosphate solution by using raffinate acid according to claim 1 or 2, wherein the extraction temperature in the step A is 25-85 ℃, and the ratio of O/A by volume is 1-10:1; the number of segments is preferably 3.

6. The method for producing a high purity ammonium phosphate solution according to claim 1 or 2, wherein the concentration temperature in the step B is 60 to 90 ℃, and the concentration of the raffinate P ₂O₅ at the concentration end point is 40 to 60wt.%.

7. The method for producing a high purity ammonium phosphate solution from raffinate acid as claimed in claim 1 or 2, wherein the extraction 2 in step C is a 1-3 stage countercurrent extraction; the number of the sections of the extraction 2 is preferably 1 section, the extraction temperature is preferably 25-85 ℃, and the ratio of O/A to O/A is 1-10:1;

the method further comprises the step of oil-water separation 3: oil-water separation is carried out on the oil phase 2, the separated water phase is integrated into the water phase 2, and the separated organic phase is put into the step D.

8. The method for producing high-purity ammonium phosphate solution by using raffinate acid according to claim 1 or 2, wherein the temperature of the back extraction in the step D is 25-85 ℃, and the ratio of O/A by volume is 1-10:1; the phase separation in the step D is preferably carried out at 25-85 ℃;

the method further comprises oil-water separation 4: oil-water separation is carried out on the water phase 3 to obtain a high-purity ammonium phosphate solution, and the separated organic phase is incorporated into the oil phase 3;

Oil-water separation 5: oil phase 3 is subjected to oil-water separation, the separated water phase is merged into high-purity ammonium phosphate solution, and the separated oil phase is returned to serve as extractant 2 for recycling.

9. The method for producing a high purity ammonium phosphate solution from raffinate acid according to claim 1 or 2, further comprising the treatment of oil phase 1: adding a stripping agent A into the oil phase 1 to strip metal cations in the oil phase 1 to obtain an oil phase 4 and a water phase 4, returning the oil phase 4 to the step A to serve as the stripping agent A for recycling, and returning the water phase 4 to serve as the stripping agent A for recycling; the back extraction agent A is preferably at least one of ammonium oxalate solution, ammonium oxalate and ammonium sulfate mixed solution, and the concentration of ammonium oxalate in the back extraction agent A is preferably 1-20 wt.%, and the concentration of ammonium sulfate is 0-35 wt.%;

More preferably the method further comprises: oil-water separation 1: oil-water separation is carried out on the oil phase 4, and a separated water phase is integrated into the water phase 4; oil-water separation 2: and (3) carrying out oil-water separation on the water phase 1, merging the separated oil phase into the oil phase 1, and separating the water phase to enter the step B.

10. A method for producing an industrial grade MAP, the method comprising: cooling and crystallizing the high-purity ammonium phosphate solution, and carrying out solid-liquid separation to obtain industrial grade MAP, and returning crystallization mother liquor to back extraction 2; the temperature of the crystallization is 0-30 ℃, and the crystallization is preferably carried out under the stirring of 200-500 r/min; the high-purity ammonium phosphate solution is prepared by adopting the method for producing the high-purity ammonium phosphate solution by using the raffinate acid according to any one of claims 1-9; the purity of the technical grade MAP is 97.56% or more, preferably 99.23% or more.