Method for producing high-purity ammonium phosphate solution and co-producing industrial-grade MAP from residual raffinate

Abstract

This invention relates to a method for producing high-purity ammonium phosphate solution and co-producing industrial-grade MAP from raffinate, belonging to the field of chemical technology. The method for producing high-purity ammonium phosphate solution from raffinate includes: A. Extraction 1: Extracting the raffinate using a metal cation extractant A, followed by phase separation to obtain an oil phase 1 and an aqueous phase 1. Step A involves a multi-stage three-stage countercurrent extraction, with 2 to 10 stages; B. Concentration: Concentrating the aqueous phase 1; C. Extraction 2: Extracting the concentrated raffinate from step B using extractant B, followed by phase separation to obtain an oil phase 2 and an aqueous phase 2. The aqueous phase 2 is returned to the raffinate from step A. Extractant B is at least one of lipids, sulfoxides, organophosphates, organic ketones, organic alcohols, and organic basic extractants; D. Back-extraction 2. This invention enables the production of high-purity ammonium phosphate solution and industrial-grade MAP from raffinate, achieving high-value utilization of the raffinate.

Description

Technical Field

[0001] This invention relates to a method for producing high-purity ammonium phosphate solution from residual raffinate and co-producing industrial-grade MAP, belonging to the field of chemical technology. Background Technology

[0002] Monoammonium phosphate (MAP) is an important raw material in industrial production, widely used in compound fertilizers, battery materials, flame retardants, fire extinguishing agents, and food additives, with a large market demand. However, with the exploitation and utilization of phosphate rock resources, the quality of raw ore has declined year by year, resulting in lower P2O5 content and higher impurity content in wet-process phosphoric acid. The Ca, Fe, Al, Mg, and F ions contained in the raw ore severely affect product quality, increasing the difficulty of purification and production costs in subsequent processing, making it difficult to balance product quality and production costs.

[0003] Raffinate is a residue containing a large amount of metal ion impurities generated during the purification of dilute or concentrated phosphoric acid. With the continuous mining of phosphate rock resources and the decline in phosphate rock quality, the amount of slag acid and raffinate produced during phosphoric acid refining also increases. Besides containing the effective component P2O5, raffinate also contains Fe. 3+ Al 3+ Mg 2+ F - SO4 2- Impurities such as Fe2O3 are present. Furthermore, the P2O5 content in the residual acid can reach over 40%, similar to that of wet-process phosphoric acid, but its metal ion content is higher. 3+ Al 3+ Mg 2+ The solid content is higher than that of wet-process phosphoric acid. This is due to the presence of Mg in the residual acid. 2+ Al 3+ The high content of phosphate rock results in high viscosity and difficulty in processing, which limits the efficient utilization of residual acid and is a major challenge in improving the utilization rate of phosphate rock.

[0004] The industrial production of monoammonium phosphate (MAP) mainly involves two methods: the thermal ammonium phosphate neutralization method and the wet ammonium phosphate neutralization method. The thermal ammonium phosphate neutralization method involves introducing ammonia gas into 50%–55% thermal phosphoric acid to adjust the pH to 4.2–4.6, followed by hot filtration, cooling crystallization, separation, and drying to obtain the finished product. However, the thermal method requires high-quality phosphate rock, is complex, energy-intensive, polluting, and costly, limiting its application. The wet method requires purifying the wet phosphoric acid to remove ionic impurities before introducing ammonia for neutralization, separation, concentration, crystallization, and drying. Compared to the thermal method, the wet method has lower production costs, but it generates residual acid and results in significant P2O5 loss. Furthermore, the high impurity ion content in the wet method leads to significant viscosity changes during ammonia neutralization, easily generating insoluble or poorly soluble substances such as magnesium ammonium phosphate, calcium hydrogen phosphate, and ammonium hexafluorosilicate, which hinders transportation and filtration, affecting product quality.

[0005] Patent application CN2023104356279 discloses a method for preparing high-quality industrial-grade monoammonium phosphate. The method involves reacting wet-process phosphoric acid with phosphate rock powder via pressure filtration, adding sodium carbonate for defluorination via pressure filtration, filtering the filtrate in a water tank equipped with chelating resin, and then sending the filtrate to a neutralization and concentration unit where nitrogen is passed through to obtain an ammonium phosphate slurry. The slurry is concentrated, crystallized, separated, and dried to obtain industrial-grade monoammonium phosphate. However, this method generates a large amount of filter residue, resulting in ineffective utilization of fluorine resources. Furthermore, the use of chelating resin for metal ion removal is low-capacity and costly, making industrial-scale production difficult.

[0006] Patent application CN2021115542845 discloses a method for producing industrial phosphoric acid and co-producing ammonium polyphosphate or solid phosphoric acid using a wet-process phosphoric acid production method. This method includes pretreatment, removal of metal ions, decolorization, concentration, extraction, washing, back-extraction, and concentration of the extract phase to obtain industrial-grade phosphoric acid. The residual raffinate is used to produce ammonium polyphosphate or for the production of solid phosphoric acid. This invention concentrates the purified acid after metal ion removal into a high-concentration anhydrous phosphoric acid before it enters the phosphoric acid extraction stage. The residual raffinate does not need to be concentrated and can be directly used as a raw material for producing water-soluble APP liquid fertilizer, achieving high-value utilization of the residual raffinate. Its phosphoric acid extraction process is extremely efficient, requiring no multi-stage countercurrent extraction, resulting in a high phosphorus yield and extraction rate, and producing high-purity industrial phosphoric acid with few impurities. However, it requires concentrating the purified acid after metal ion removal into a high-concentration anhydrous phosphoric acid before entering the phosphoric acid extraction stage, leading to high energy consumption.

[0007] Patent application number 201210203327X discloses a method for producing industrial monoammonium phosphate (MAP) and fertilizer-grade MAP using residual raffinate. This method involves reacting residual raffinate and ammonia in a specific ratio. Metal ions react with ammonia to form a stable, citrate-soluble precipitate containing fluorine. The separated filtrate undergoes concentration, crystallization, centrifugation, drying, and packaging to obtain industrial-grade MAP. The filter residue is then re-slurried with crude phosphoric acid and reacted with ammonia in a specific ratio, followed by concentration, granulation, and drying to obtain fertilizer-grade MAP. This invention allows the modified residue to be reacted with ammonia after re-slurrying with phosphoric acid to produce fertilizer-grade MAP (or diammonium phosphate), achieving the graded utilization of residual raffinate. However, this method suffers from high viscosity of the residual raffinate, making filtration of the citrate-soluble precipitate formed with ammonia difficult and hindering industrial-scale operation. Furthermore, the metal ions in the residual raffinate are untreated, resulting in a high impurity content in the obtained fertilizer-grade MAP.

[0008] Patent application number 2018102016977 discloses a method and apparatus for producing monoammonium phosphate (MAP) by adding residual raffinate and slag acid to dilute phosphoric acid. This method involves adding residual raffinate, slag acid, and phosphorus-containing wastewater generated during the production of MAP to dilute phosphoric acid. The residual raffinate and slag acid are mixed with dilute phosphoric acid in an acid mixing tank to obtain a mixed acid. The mixed acid reacts with gaseous ammonia to form a slurry, which is then concentrated, sprayed under high pressure, and dried to produce MAP. This patent reduces the amount of dilute phosphoric acid used and achieves comprehensive utilization of residual raffinate and slag acid; however, the metal ions in the raw acid are not treated, making it difficult to obtain high-purity MAP. Summary of the Invention

[0009] The first objective of this invention is to provide a novel method for producing high-purity ammonium phosphate from residual raffinate.

[0010] To achieve the first objective of this invention, the method includes:

[0011] A. Extraction 1: Extract the residual acid using metal cation extractant A. After extraction, separate the phases to obtain oil phase 1 and aqueous phase 1. The extraction described in step A is a 2-10 stage three-stage countercurrent extraction.

[0012] B. Concentration: The aqueous phase 1 is concentrated.

[0013] C. Extraction 2: Extract the residual acid from step B using extractant B. After extraction, separate the phases to obtain oil phase 2 and aqueous phase 2. The aqueous phase 2 is returned to the residual acid from step A. The extractant B is at least one of lipids, sulfoxides, organic phosphates, organic ketones, organic alcohols, and organic basic extractants.

[0014] D. Back-extraction 2: The oil phase 2 is back-extracted using liquid ammonia to separate the phases into oil phase 3 and aqueous phase 3, which is a high-purity ammonium phosphate solution.

[0015] High-purity ammonium phosphate solution refers to ammonium phosphate solution with a total impurity ion content of less than 600 ppm and a purity of more than 70%.

[0016] In one specific embodiment, the extractant A in step A includes at least one of organophosphorus extractants, organophosphorus extractants, organosulfonic acid extractants, organocarboxylic acid extractants, and tertiary carbonate extractants; preferably, the extractant A is at least one of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate, di(2,4,4-trimethylpentyl)phosphine, 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester, N,NN-n-octylaminedimethylenephenylphosphonic acid, N,NN-n-hexylaminedimethylenephenylphosphonic acid, toluenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, xylenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, cinnamic acid, fatty acids, lauric acid, and naphthenic acid.

[0017] In one 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 phosphate, tributyl phosphate, methyl isobutyl ketone, cyclohexanone, isoamyl alcohol, sec-octanol, and substituted primary alcohols.

[0018] In one specific embodiment, the main elements in the residual acid from step A, calculated by their oxides, are: P2O5 content 30 wt.%–60 wt.%, Al2O3 content 0.5 wt.%–10 wt.%, MgO content 0.5 wt.%–10 wt.%, Fe2O3 content 0.1 wt.%–5 wt.%, CaO content 0.1 wt.%–1 wt.%, and F content 0.1 wt.%–2 wt.%.

[0019] In one specific embodiment, the extraction temperature in step A is 25–85°C, with a volume ratio of O / A of 1–10:1; the number of stages is preferably 3.

[0020] In one specific embodiment, the concentration temperature in step B is 60–90°C, and the concentration of residual acid P2O5 at the concentration endpoint is 40 wt.%–60 wt.%.

[0021] In one specific embodiment, step C, extraction 2, is a 1-3 stage countercurrent extraction; the number of stages in extraction 2 is preferably 1 stage, the extraction temperature is preferably 25-85°C, and the volume ratio O / A is 1-10:1.

[0022] The method further includes oil-water separation 3: oil phase 2 is separated into oil and water, the separated aqueous phase is incorporated into aqueous phase 2, and the separated organic phase is fed into step D.

[0023] In one specific embodiment, the back-extraction temperature in step D is 25–85°C, with a volume ratio of O / A of 1–10:1; the phase separation in step D is preferably carried out at 25–85°C.

[0024] The method further includes oil-water separation 4: separating the aqueous phase 3 into oil and water to obtain a high-purity ammonium phosphate solution, and incorporating the separated organic phase into the oil phase 3;

[0025] Oil-water separation 5: The oil phase 3 is separated into oil and water. The separated water phase is added to the high-purity ammonium phosphate solution, and the separated oil phase is returned as extractant 2 for recycling.

[0026] In one specific embodiment, the method further includes the treatment of oil phase 1: adding stripping agent A to oil phase 1 to strip the metal cations in oil phase 1, resulting in oil phase 4 and aqueous phase 4. Oil phase 4 is returned to step A as extractant A for recycling, and aqueous phase 4 is returned as stripping agent A for recycling. Stripping agent A is preferably at least one of ammonium oxalate solution, a mixed solution of ammonium oxalate and ammonium sulfate, preferably with an ammonium oxalate concentration of 1 wt.% to 20 wt.% and an ammonium sulfate concentration of 0 wt.% to 35 wt.%.

[0027] A more preferred method further includes: oil-water separation 1: separating the oil phase 4 into oil and water, and merging the separated water phase into the water phase 4; oil-water separation 2: separating the water phase 1 into oil and water, merging the separated oil phase into the oil phase 1, and separating the water phase to proceed to step B.

[0028] The second objective of this invention is to provide a new method for producing industrial-grade MAPs.

[0029] To achieve the second objective of the present invention, the method includes:

[0030] The high-purity ammonium phosphate solution is cooled and crystallized, and solid-liquid separation is performed to obtain industrial-grade MAP. The mother liquor from the crystallization is returned to back-extraction 2. The crystallization temperature is 0-30℃, and the crystallization is preferably carried out under stirring at 200-500 r / min. The high-purity ammonium phosphate solution is prepared by the above-mentioned method of producing high-purity ammonium phosphate solution from residual raffinate. The purity of the industrial-grade MAP is 97.56% or higher, preferably 99.23% or higher.

[0031] Beneficial effects:

[0032] 1. This invention employs specific extraction and back-extraction methods to separate high-purity ammonium phosphate solution from residual acid. The extractant can be recycled after back-extraction, and various metal ions in phosphoric acid can be effectively separated, avoiding the generation of insoluble substances such as magnesium ammonium phosphate that could affect product quality.

[0033] 2. This invention uses high-purity ammonium phosphate solution to cool and crystallize directly to obtain industrial monoammonium phosphate, without the need for impurity removal, thus reducing production costs.

[0034] 3. This invention uses residual raffinate as a raw material to prepare high-purity ammonium phosphate solution, thereby realizing the high-value utilization of residual raffinate. Attached Figure Description

[0035] Figure 1 This is a process flow diagram of one specific embodiment of the present invention. Detailed Implementation

[0036] To achieve the first objective of this invention, the method includes:

[0037] A. Extraction 1: Extract the residual acid using metal cation extractant A. After extraction, separate the phases to obtain oil phase 1 and aqueous phase 1. The extraction described in step A is a 2-10 stage three-stage countercurrent extraction.

[0038] B. Concentration: The aqueous phase 1 is concentrated.

[0039] C. Extraction 2: Extract the residual acid from step B using extractant B. After extraction, separate the phases to obtain oil phase 2 and aqueous phase 2. The aqueous phase 2 is returned to the residual acid from step A. The extractant B is at least one of lipids, sulfoxides, organic phosphates, organic ketones, organic alcohols, and organic basic extractants.

[0040] D. Back-extraction 2: The oil phase 2 is back-extracted using liquid ammonia to separate the phases into oil phase 3 and aqueous phase 3, which is a high-purity ammonium phosphate solution.

[0041] High-purity ammonium phosphate solution refers to ammonium phosphate solution with a total impurity ion content of less than 600 ppm and a purity of more than 70%.

[0042] In one specific embodiment, the extractant A in step A includes at least one of organophosphorus extractants, organophosphorus extractants, organosulfonic acid extractants, organocarboxylic acid extractants, and tertiary carbonate extractants; preferably, the extractant A is at least one of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate, di(2,4,4-trimethylpentyl)phosphine, 2-ethylhexylphosphonic acid mono(2-ethylhexyl) ester, N,NN-n-octylaminedimethylenephenylphosphonic acid, N,NN-n-hexylaminedimethylenephenylphosphonic acid, toluenesulfonic acid, p-toluenesulfonic acid, benzenesulfonic acid, xylenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, cinnamic acid, fatty acids, lauric acid, and naphthenic acid.

[0043] In one 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 phosphate, tributyl phosphate, methyl isobutyl ketone, cyclohexanone, isoamyl alcohol, sec-octanol, and substituted primary alcohols.

[0044] In one specific embodiment, the main elements in the residual acid from step A, calculated by their oxides, are: P2O5 content 30 wt.%–60 wt.%, Al2O3 content 0.5 wt.%–10 wt.%, MgO content 0.5 wt.%–10 wt.%, Fe2O3 content 0.1 wt.%–5 wt.%, CaO content 0.1 wt.%–1 wt.%, and F content 0.1 wt.%–2 wt.%.

[0045] In one specific embodiment, the extraction temperature in step A is 25–85°C, with a volume ratio of O / A of 1–10:1; the number of stages is preferably 3.

[0046] In one specific embodiment, the concentration temperature in step B is 60–90°C, and the concentration of residual acid P2O5 at the concentration endpoint is 40 wt.%–60 wt.%.

[0047] In one specific embodiment, step C, extraction 2, is a 1-3 stage countercurrent extraction; the number of stages in extraction 2 is preferably 1 stage, the extraction temperature is preferably 25-85°C, and the volume ratio O / A is 1-10:1.

[0048] The method further includes oil-water separation 3: oil phase 2 is separated into oil and water, the separated aqueous phase is incorporated into aqueous phase 2, and the separated organic phase is fed into step D.

[0049] In one specific embodiment, the back-extraction temperature in step D is 25–85°C, with a volume ratio of O / A of 1–10:1; the phase separation in step D is preferably carried out at 25–85°C.

[0050] The method further includes oil-water separation 4: separating the aqueous phase 3 into oil and water to obtain a high-purity ammonium phosphate solution, and incorporating the separated organic phase into the oil phase 3;

[0051] Oil-water separation 5: The oil phase 3 is separated into oil and water. The separated water phase is added to the high-purity ammonium phosphate solution, and the separated oil phase is returned as extractant 2 for recycling.

[0052] In one specific embodiment, the method further includes the treatment of oil phase 1: adding stripping agent A to oil phase 1 to strip the metal cations in oil phase 1, resulting in oil phase 4 and aqueous phase 4. Oil phase 4 is returned to step A as extractant A for recycling, and aqueous phase 4 is returned as stripping agent A for recycling. Stripping agent A is preferably at least one of ammonium oxalate solution, a mixed solution of ammonium oxalate and ammonium sulfate, preferably with an ammonium oxalate concentration of 1 wt.% to 20 wt.% and an ammonium sulfate concentration of 0 wt.% to 35 wt.%.

[0053] A more preferred method further includes: oil-water separation 1: separating the oil phase 4 into oil and water, and merging the separated water phase into the water phase 4; oil-water separation 2: separating the water phase 1 into oil and water, merging the separated oil phase into the oil phase 1, and separating the water phase to proceed to step B.

[0054] The second objective of this invention is to provide a new method for producing industrial-grade MAPs.

[0055] To achieve the second objective of the present invention, the method includes:

[0056] The high-purity ammonium phosphate solution is cooled and crystallized, and solid-liquid separation is performed to obtain industrial-grade MAP. The mother liquor from the crystallization is returned to back-extraction 2. The crystallization temperature is 0-30℃, and the crystallization is preferably carried out under stirring at 200-500 r / min. The high-purity ammonium phosphate solution is prepared by the above-mentioned method of producing high-purity ammonium phosphate solution from residual raffinate. The purity of the industrial-grade MAP is 97.56% or higher, preferably 99.23% or higher.

[0057] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the embodiments described herein.

[0058] Example 1

[0059] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0060] (1) Extraction 1: The residual acid containing 44.67 wt.% P2O5, 3.2 wt.% Al2O3, 3.02 wt.% MgO, 0.3 wt.% Fe2O3, 0.1 wt.% CaO, and 0.2 wt.% F was subjected to three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain oil phase 1 and aqueous phase 1. The extraction temperature of each stage was 60℃, and the volume ratio O / A was 4:1.

[0061] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction 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 back-extraction. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0062] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at a temperature of 60°C until the phosphoric acid concentration is 50 wt.%.

[0063] (4) Extraction 2: Trioctylamine was used as extractant B to perform a first-stage countercurrent extraction on the concentrated clear liquid. The extraction temperature was 60℃ and the volume ratio O / A was 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 residual acid for extraction.

[0064] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 60℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0065] (6) Cooling crystallization: High-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0066] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0067] Example 2

[0068] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0069] (1) Extraction 1: The residual acid containing P2O5 of 44.55 wt.%, Al2O3 of 3.0 wt.%, MgO of 2.9 wt.%, Fe2O3 of 0.3 wt.%, CaO of 0.1 wt.%, and F of 0.2 wt.% was subjected to three-stage countercurrent extraction with 2-ethylhexyl phosphate to obtain oil phase 1 and aqueous phase 1. The extraction temperature of each stage was 60℃, and the volume ratio O / A was 4:1.

[0070] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction agent A, wherein the concentration of ammonium oxalate is 5 wt.% and the concentration of ammonium sulfate is 35 wt.%. A three-stage countercurrent back-extraction is performed on the oil phase 1 loaded with metal ions. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0071] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at 60°C until the phosphoric acid concentration is 50 wt.%.

[0072] (4) Extraction 2: Using TBP (tributylphosphine) as extractant B, the filtered liquid was subjected to a single-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 residual acid for further extraction.

[0073] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 60℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0074] (6) Cooling crystallization: High-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0075] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0076] Example 3

[0077] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0078] (1) Extraction 1: The residual acid containing 44.68 wt.% P2O5, 3.3 wt.% Al2O3, 2.9 wt.% MgO, 0.3 wt.% Fe2O3, 0.1 wt.% CaO, and 0.2 wt.% F was subjected to three-stage countercurrent extraction with N,NN-n-octylaminedimethylenephenylphosphonic acid to obtain oil phase 1 and aqueous phase 1. The extraction temperature of each stage was 60℃, and the volume ratio O / A was 4:1.

[0079] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction 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 back-extraction. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0080] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at a temperature of 60°C until the phosphoric acid concentration is 50 wt.%.

[0081] (4) Extraction 2: Using MIBK (methyl isobutyl ketone) as extractant B, the filtered liquid was subjected to a single-stage countercurrent extraction at an extraction temperature of 60°C and a 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 residual acid for further extraction.

[0082] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 60℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0083] (6) Cooling crystallization: High-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0084] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0085] Example 4

[0086] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0087] (1) Extraction 1: The residual acid containing 40.97 wt.% P2O5, 2.5 wt.% Al2O3, 2.1 wt.% MgO, 0.4 wt.% Fe2O3, 0.4 wt.% CaO, and 0.2 wt.% F was subjected to three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain aqueous phase 1 and oil phase 1. The extraction temperature of each stage was 60℃, and the volume ratio O / A was 4:1.

[0088] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction 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 back-extraction. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0089] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at a temperature of 60°C until the phosphoric acid concentration is 50 wt.%.

[0090] (4) Extraction 2: Trioctylamine was used as extractant B to perform a single-stage countercurrent extraction on the filtered liquid at an extraction temperature of 60°C and a 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 residual acid for extraction.

[0091] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 60℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0092] (6) Cooling crystallization: High-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0093] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0094] Example 5

[0095] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0096] (1) Extraction 1: The residual acid containing 48.26 wt.% P2O5, 3.5 wt.% Al2O3, 3.0 wt.% MgO, 0.4 wt.% Fe2O3, 0.4 wt.% CaO, and 0.1 wt.% F was subjected to three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain aqueous phase 1 and oil phase 1. The extraction temperature of each stage was 60℃, and the volume ratio O / A was 4:1.

[0097] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction 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 back-extraction. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0098] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at a temperature of 60°C until the phosphoric acid concentration is 50 wt.%.

[0099] (4) Extraction 2: Trioctylamine was used as extractant B to perform a single-stage countercurrent extraction on the filtered liquid at an extraction temperature of 60°C and a 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 residual acid for extraction.

[0100] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 60℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0101] (6) Cooling crystallization: High-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0102] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0103] Example 6

[0104] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0105] (1) Extraction 1: The residual acid containing 44.67 wt.% P2O5, 3.0 wt.% Al2O3, 3.0 wt.% MgO, 0.3 wt.% Fe2O3, 0.2 wt.% CaO, and 0.2 wt.% F was extracted with di(2-ethylhexyl) phosphate in a three-stage countercurrent extraction process to obtain aqueous phase 1 and oil phase 1. The extraction temperature of each stage was 60°C, and the volume ratio O / A was 4:1.

[0106] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction 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 back-extraction. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0107] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at a temperature of 60°C until the phosphoric acid concentration is 50 wt.%.

[0108] (4) Extraction 2: Dioctyl sulfoxide was used as extractant B to perform a single-stage countercurrent extraction on the filtered liquid at an extraction temperature of 60°C and a 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 residual acid for extraction.

[0109] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 70℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0110] (6) Cooling crystallization: The high-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 10℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0111] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0112] Example 7

[0113] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0114] (1) Extraction 1: The residual acid containing 44.67 wt.% P2O5, 3.0 wt.% Al2O3, 3.0 wt.% MgO, 0.3 wt.% Fe2O3, 0.2 wt.% CaO, and 0.1 wt.% F was subjected to three-stage countercurrent extraction with di(2-ethylhexyl) phosphate to obtain oil phase 1 and aqueous phase 1. The extraction temperature of each stage was 60℃, and the volume ratio O / A was 4:1.

[0115] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction 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 back-extraction. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0116] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at a temperature of 80°C until the phosphoric acid concentration is 60 wt.%.

[0117] (4) Extraction 2: Tributyl phosphate was used as extractant B to perform a two-stage countercurrent extraction on the filtered liquid at an extraction temperature of 60°C and a 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 residual acid for extraction.

[0118] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 70℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0119] (6) Cooling crystallization: The high-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 10℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0120] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0121] Comparative Example 1

[0122] like Figure 1 As shown, a method for producing high-purity ammonium phosphate solution and industrial-grade MAP from residual raffinate includes the following steps:

[0123] (1) Extraction 1: The residual acid containing 44.67 wt.% P2O5, 3.3 wt.% Al2O3, 2.8 wt.% MgO, 0.3 wt.% Fe2O3, 0.2 wt.% CaO, and 0.1 wt.% F was subjected to a two-stage countercurrent extraction with trioctylamine as the extractant. The extraction temperature was 60°C and the volume ratio O / A was 2:1. After phase separation and oil-water separation, the aqueous phase and oil phase were obtained.

[0124] (2) Back-extraction 1: Liquid ammonia is added to the oil phase for back-extraction at a temperature of 60°C. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, an NH4H2PO4 solution is obtained. The separated oil is recycled as a regenerated extractant.

[0125] (3) Cooling crystallization: High-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0126] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0127] Comparative Example 2

[0128] (1) Extraction 1: The residual acid containing P2O5 of 44.52 wt.%, Al2O3 of 3.2 wt.%, MgO of 2.9 wt.%, Fe2O3 of 0.3 wt.%, CaO of 0.2 wt.%, and F of 0.1 wt.% was subjected to a three-stage countercurrent extraction with 2-ethylhexyl phosphate to obtain aqueous phase 1 and oil phase 1. The extraction temperature of each stage was 60°C, and the volume ratio of O / A was 4:1.

[0129] (2) Back-extraction 1: A mixed solution of ammonium oxalate and ammonium sulfate is used as back-extraction agent A, wherein the concentration of ammonium oxalate is 5 wt.% and the concentration of ammonium sulfate is 35 wt.%. A three-stage countercurrent back-extraction is performed on the oil phase 1 loaded with metal ions. The temperature of each back-extraction stage is 60°C and the volume ratio of O / A is 1:3. Phase separation and oil-water separation are performed. The oil phase is used as a regenerated extractant and recycled. The aqueous phase is mixed with the back-extraction agent and recycled.

[0130] (3) Concentration: Aqueous phase 1 is concentrated in a vacuum evaporator at 60°C until the phosphoric acid concentration is 50 wt.%.

[0131] (4) Extraction 2: Using TBP (tributylphosphine) as extractant B, the filtered liquid was subjected to a single-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 residual acid for further extraction.

[0132] (5) Back-extraction 2: Liquid ammonia is added to oil phase 2 for back-extraction. The back-extraction temperature is 60℃. The volume ratio of O / A is 1:1. After phase separation and oil-water separation, NH4H2PO4 solution is obtained. The separated organic phase is used as a regenerated extractant for recycling.

[0133] (6) Cooling crystallization: High-purity NH4H2PO4 solution is cooled and crystallized under stirring to obtain crystals and slurry. The crystallization temperature is 20℃. After filtration and drying, industrial MAP is obtained. The mother liquor of crystallization is returned to back-extraction 2.

[0134] In this embodiment, ammonium phosphate solution and industrial MAP were prepared, and their MER values ​​and product purity are shown in Table 1.

[0135] Table 1. Fluorine content, MER value, and product purity in each example and comparative example.

[0136]

[0137] In the table above, the concentration of ammonium phosphate solution refers to the mass concentration of the resulting NH4H2PO4 solution. Industrial MAP purity refers to the purity of the product used in the preparation of industrial monoammonium phosphate.

Claims

1. A process for producing a high purity phosphonammonia solution from a raffinate acid, characterized in that, The method comprises: A. Extraction 1: extract the raffinate acid with metal cation extractant A, and after extraction, separate the phases to obtain oil phase 1 and water phase 1, the extraction in the A step is 2-10 stages of three-stage countercurrent extraction; the extractant A is at least one of di(2-ethylhexyl)phosphate, 2-ethylhexyl 2-ethylhexyl phosphonate, di(2,4,4-trimethylpentyl) phosphinic acid, 2-ethylhexyl phosphonic acid mono(2-ethylhexyl) ester, N,N-N-n-octylamine dimethylene phenyl phosphonic acid, N,N-N-n-hexylamine dimethylene phenyl phosphonic acid, p-toluenesulfonic acid, benzene sulfonic acid, xylene sulfonic acid, dodecyl benzene sulfonic acid, dinonyl naphthalene sulfonic acid, cinnamic acid, lauric acid, naphthenic acid; B. Concentration: concentrate the water phase 1, the concentration temperature is 60-90℃, the P2O5 concentration of the raffinate acid at the end of concentration is 40 wt.%-60 wt.%; C. Extraction 2: extract the raffinate acid after concentration in the B step with extractant B, and after extraction, separate the phases to obtain oil phase 2 and water phase 2, the water phase 2 is returned to the raffinate acid in the A step, the extractant B is at least one of trialkylamine, didecylamine, trioctylamine, trinonylamine, ethyl acetate, amyl acetate, butyl acetate, dioctyl sulfoxide, diphenyl sulfoxide, di(2-ethylhexyl) hexyl phosphonate, octyl phosphonic acid dioctyl ester, tributyl phosphate, methyl isobutyl ketone, cyclohexanone, isoamyl alcohol, secondary octanol; D. Stripping 2: use liquid ammonia to strip the oil phase 2, and separate the phases to obtain oil phase 3 and water phase 3, the water phase 3 is a high-purity phosphorus ammonium solution; The method further comprises treatment of the oil phase 1: add stripping agent A to the oil phase 1 to strip the metal cations in the oil phase 1, and obtain oil phase 4 and water phase 4, the oil phase 4 is returned to the A step to be used as extractant A for recycling, and the water phase 4 is returned to be used as stripping agent A for recycling; the stripping agent A is ammonium oxalate solution or a mixed solution of ammonium oxalate and ammonium sulfate.

2. The method of claim 1, wherein the high purity ammonium phosphate solution is produced from the raffinate acid. The main elements in the raffinate acid in the A step are calculated as their oxides: P2O5 content is 30 wt.%-60 wt.%, Al2O3 content is 0.5 wt.%-10 wt.%, MgO content is 0.5 wt.%-10 wt.%, Fe2O3 content is 0.1 wt.%-5 wt.%, CaO content is 0.1 wt.%-1 wt.%, and F content is 0.1 wt.%-2 wt.%.

3. The method of claim 1 or 2, wherein the method is characterized by, The extraction temperature in the A step is 25-85℃, and the phase ratio O / A is 1-10:1 by volume.

4. The method of claim 1 or 2, wherein the high-purity phosphoric ammonium solution is produced from the raffinate acid. The number of stages of the extraction in the A step is 3 stages.

5. The method of producing a high-purity phosphorus ammonium solution from raffinate acid according to claim 1 or 2, characterized by, The extraction 2 in the C step is 1-3 stages of countercurrent extraction.

6. The method of claim 1 or 2, wherein the high-purity phosphoric ammonium solution is produced from the raffinate acid. The number of stages of the extraction 2 in the C step is 1 stage.

7. The method of claim 1 or 2, wherein the high-purity phosphoric ammonium solution is produced from the raffinate acid. The extraction temperature in the C step is 25-85℃, and the phase ratio O / A is 1-10:1 by volume. The method further comprises oil-water separation 3: perform oil-water separation on the oil phase 2, combine the separated water phase into the water phase 2, and put the separated organic phase into the D step.

8. The method of claim 1 or 2, wherein the high-purity phosphoric ammonium solution is produced from the raffinate acid. The stripping temperature in the D step is 25-85℃, and the phase ratio O / A is 1-10:1 by volume. The method further comprises oil-water separation 4: perform oil-water separation on the water phase 3 to obtain a high-purity phosphorus ammonium solution, and combine the separated organic phase into the oil phase 3; The method further comprises oil-water separation 4: perform oil-water separation on the water phase 3 to obtain a high-purity phosphorus ammonium solution, and combine the separated organic phase into the oil phase 3; Oil-water separation 5: oil-water separation of oil phase 3, the separated water phase is added into the high-purity ammonium phosphate solution, and the separated oil phase is recycled as extractant 2.

9. The method of producing a high-purity phosphorus ammonium solution from raffinate acid according to claim 1 or 2, characterized by, The phase separation in the D step is carried out at 25-85°C.

10. The method of producing a high-purity phosphorus ammonium solution from raffinate acid according to claim 1 or 2, characterized by, The concentration of ammonium oxalate in the back-extractant A is 1 wt.%-20 wt.%, and the concentration of ammonium sulfate is 0 wt.%-35 wt.%.

11. The method of claim 10, wherein the high purity ammonium phosphate solution is produced from the raffinate acid. The method further comprises: oil-water separation 1: oil-water separation of oil phase 4, the separated water phase is added into water phase 4; oil-water separation 2: oil-water separation of water phase 1, the separated oil phase is added into oil phase 1, and the separated water phase is added into the B step.

12. A method for the production of technical grade MAP, characterized in that, The method comprises: cooling crystallization of the high-purity ammonium phosphate solution, solid-liquid separation to obtain industrial-grade MAP, and return of the crystallization mother liquor to the back-extraction 2; the crystallization temperature is 0-30°C; the high-purity ammonium phosphate solution is prepared by the method for producing high-purity ammonium phosphate solution according to any one of claims 1-11; and the purity of the industrial-grade MAP is greater than 97.56%.

13. The method of producing industrial grade MAP according to claim 12, characterized in that, The crystallization is carried out under stirring at 200-500 r / min.

14. The method of producing industrial grade MAP according to claim 13, characterized in that, The purity of the industrial-grade MAP is greater than 99.23%. The purity of the industrial-grade MAP is greater than 99.23%.

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