Method for removing wet-process phosphoric acid metal impurities by adopting mixed solvent

Abstract

The invention discloses a method for removing metal impurities in wet-process phosphoric acid by adopting a mixed solvent, which comprises the following steps: uniformly mixing a solvent A and a solvent B, then mixing with a raw material wet-process phosphoric acid, extracting, separating, washing, reversely extracting and concentrating to obtain a finished product of 85% phosphoric acid, the solvent A is one or a mixture of more of methyl isobutyl ketone, n-butyl alcohol and TBP; and the solvent B is one or a mixture of more of dimethyl heptyl methylphosphonate, bis (2, 4, 4-trimethylpentyl) phosphonic acid, 2-ethylhexyl phosphate mono 2-ethylhexyl ester, dioctyl phosphate and dialkyl dithiophosphonic acid, and the solvent B is one or more of dimethyl heptyl methylphosphonate, bis (2, 4, 4-trimethylpentyl) phosphonic acid, 2-ethylhexyl phosphate mono 2-ethylhexyl ester, dioctyl phosphate and dialkyl dithiophosphonic acid. The method is simple in process, environment-friendly and low in production cost, the solvent A and the solvent B are mixed according to the proportion, the removal efficiency of metal impurities and the product purity are improved, the product obtained through the method is high in purity, the industrial requirements of high-end electronic products, food, medicine, electronics, new energy and the like are met, and the method is suitable for industrial production. The additional value of the purified phosphoric acid is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wet-process phosphoric acid purification, and in particular to a method for removing metal impurities from wet-process phosphoric acid by using a mixed solvent. Background Art

[0002] Wet-process phosphoric acid is an important product of phosphorus chemical industry. Currently, wet-process phosphoric acid is used to produce fertilizers or prepare industrial-grade phosphates after impurities removal. Some are used in food additives, new energy fields, and high-end industries such as pharmaceuticals, coatings, flame retardants, and printing and dyeing after further purification. However, the various impurities contained in phosphoric acid, such as iron, aluminum, magnesium, fluorine, titanium, and zinc, restrict its application in high-end fields.

[0003] There are several methods for removing impurities from wet phosphoric acid, including chemical precipitation, ion exchange, crystallization, membrane separation, and solvent extraction. Chemical precipitation is simple to operate and has low cost, but causes large phosphorus loss; ion exchange separates metal impurities through ion exchange resins, but has limited capacity and high cost; crystallization has mild operating conditions and does not require the addition of chemical reagents, but requires multiple crystallizations to achieve high purity requirements, and has low yields; membrane separation uses selective permeability to separate impurities, but this method has limited selectivity and flux for materials and is prone to membrane instability; solvent extraction separates metal ions by replacing functional groups in the extractant, but due to the selectivity of the solvent for metals, some metals are difficult to remove through extraction and washing.

[0004] At present, there are studies on the use of solvent extraction to purify wet-process phosphoric acid. For example, the patent with publication number CN112875662A discloses "a method for purifying wet-process phosphoric acid by solvent extraction". This method obtains purified phosphoric acid by extracting, washing and stripping the raw acid, reducing the concentration of impurity ions in the extractant. However, this patent only uses a single solvent for extraction and separation. When faced with wet-process phosphoric acid with a high impurity content, some impurities such as titanium and zinc cannot be completely separated. The patent with publication number CN117049488A discloses "a method for purifying heavy metal zinc from wet-process phosphoric acid". The zinc ions in wet-process phosphoric acid are chelated with an auxiliary agent, and then regenerated and recycled by ion exchange resin adsorption, reducing environmental pollution. However, this method only separates zinc, and the removal efficiency is about 50%. There is a problem that the chelating agent cannot be removed and the cost is high. The separation efficiency of the ion exchange resin is low, and it is difficult to achieve industrialization. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the prior art and provide a method for removing metal impurities from wet-process phosphoric acid using a mixed solvent, which has a simple process, is environmentally friendly and has low production cost. The method is particularly suitable for removing titanium and zinc metal impurities from wet-process phosphoric acid produced using phosphate ore with a high metal content as a raw material.

[0006] The technical solution adopted by the present invention is as follows: A method for removing metal impurities from wet-process phosphoric acid by using a mixed solvent, wherein solvent A and solvent B are mixed evenly and then mixed with raw wet-process phosphoric acid for extraction, and a finished product of 85% phosphoric acid is obtained through separation, washing, stripping and concentration; the solvent A is a mixture of one or more of MIBK (methyl isobutyl ketone), n-butanol and TBP (tributyl phosphate); the solvent B is a mixture of one or more of P350 (dimethylheptyl methylphosphonate), C272 (bis(2,4,4-trimethylpentyl)phosphonic acid), P507 (2-ethylhexyl phosphate mono-2-ethylhexyl ester), P204 (dioctyl phosphate) and C301 (dialkyl dithiophosphonic acid).

[0007] Furthermore, the solvent A and the solvent B are uniformly mixed in a volume ratio of (2-4):0.5.

[0008] Furthermore, the organic phase (a mixture of solvent A and solvent B) and the raw material wet-process phosphoric acid are extracted in a volume ratio of (2-4):1.

[0009] Furthermore, the solvent A is one or two or more of methyl isobutyl ketone, n-butanol, and TBP tributyl phosphate, mixed in equal volumes; the solvent B is one or more of dimethylheptyl methylphosphonate, bis(2,4,4-trimethylpentyl)phosphonic acid, 2-ethylhexyl mono-2-ethylhexyl phosphate, dioctyl phosphate, and dialkyl dithiophosphonic acid, mixed in equal volumes.

[0010] Furthermore, the extraction time is 10-20 minutes, and the extraction temperature is 25-30°C.

[0011] Furthermore, the washing adopts phosphoric acid with low metal impurity content as raw material, wherein P2O5: 36-38%, and metal impurity content is less than 2ppm.

[0012] Furthermore, the stripping raw material is UP water, and the stripping phase ratio is 5:1.

[0013] Furthermore, the raw material wet-process phosphoric acid of the present invention has a P2O5 content of 45-52% and a MER value of 10-12%.

[0014] Furthermore, the volume ratio of the washing medium is 7:1.

[0015] Beneficial effects of the present invention: 1. The mixture of solvent A and solvent B of the present invention has different solubility and selectivity for metal ions in the raw material wet-process phosphoric acid. The polar and non-polar solvents are mixed in proportion, thereby improving the removal efficiency of metal impurities and the purity of the product.

[0016] 2. The process of the present invention is simple, the mixed solvent of solvent A and solvent B is recycled, and the extractant is recycled and reused after back extraction, which is environmentally friendly and reduces production costs.

[0017] 3. The product obtained by the method of the present invention has high purity, which meets the needs of high-end electronic products, food, medicine, electronics, new energy and other industries, and increases the added value of purified phosphoric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a production process flow chart of the present invention. DETAILED DESCRIPTION

[0019] The following describes the embodiments of the present invention in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0020] Example 1 like Figure 1 As shown, a method for removing metal impurities from wet-process phosphoric acid using a mixed solvent comprises the following steps: (1) Preparation of mixed solvent: First, mix the solvent P350 and C272 in an equal volume ratio of 1:1 to obtain solvent B, and then mix it with MIBK in solvent A in a volume ratio of (solvent A = 4: solvent B = 0.5) for later use; (2) extracting the mixed solvent of step (1) with wet-process phosphoric acid P2O5 (45%, MER value 10%) at a volume ratio of 4:1, with an extraction time of 10 min and an extraction temperature of 30°C; after the extraction is completed, standing for 10 min to separate the phases, and separating the phosphorus-containing organic phase and the residual acid; (3) washing the organic phase containing phosphorus in step (2), adding washing acid with a P2O5 content of 38% and a metal ion content of less than 5 ppm, reacting the washing phase in a ratio of 7:1 for 10 min at a reaction temperature of 30°C. After the reaction is completed, standing for 10 min to separate the phases, and separating the washed organic phase and the residual washing acid; (4) The organic phase after washing in step (3) was added with UP water at a volume ratio of 5:1 for stripping. The stripping time was 10 min and the reaction temperature was 30°C. After the reaction was completed, the phases were allowed to stand for 10 min to separate the stripping organic phase and the stripping acid. The stripping organic phase could be recycled. The stripping acid was subjected to activated carbon adsorption, hydrogen peroxide bleaching and concentration to finally obtain purified 85 phosphoric acid.

[0021] The chemical analysis data of the purified 85 phosphoric acid in this example are shown in the following table:

[0022] Example 2 like Figure 1As shown, a method for removing metal impurities from wet-process phosphoric acid using a mixed solvent comprises the following steps: Preparation of mixed solvent: First, mix the solvents P350 and P507 in an equal volume ratio of 1:1 to obtain solvent B, and then mix it with MIBK in solvent A in a volume ratio of (solvent A=3:solvent B=0.5) for later use; (2) extracting the mixed solvent of step (1) with wet-process phosphoric acid (P2O5 is 50%, MER value is 11%) at a volume ratio of 4:1, the extraction time is 10 minutes, and the extraction temperature is 30°C; after the extraction is completed, the phases are allowed to stand for 10 minutes to separate and obtain the phosphorus-containing organic phase and the residual acid; (3) washing the organic phase containing phosphorus in step (2), adding washing acid with a P2O5 content of 38% and a metal ion content of less than 5 ppm, reacting the washing phase in a ratio of 7:1 for 10 min at a reaction temperature of 30°C. After the reaction is completed, standing for 10 min to separate the phases, and separating the washed organic phase and the residual washing acid; (4) The organic phase after washing in step (3) was added with UP water at a volume ratio of 5:1 for stripping. The stripping time was 10 min and the reaction temperature was 30°C. After the reaction was completed, the phases were allowed to stand for 10 min to separate the stripping organic phase and the stripping acid. The stripping organic phase could be recycled. The stripping acid was subjected to activated carbon adsorption, hydrogen peroxide bleaching and concentration to finally obtain purified 85 phosphoric acid.

[0023] The chemical analysis data of the purified 85 phosphoric acid in this example are shown in the following table:

[0024] Example 3 like Figure 1 As shown, a method for removing metal impurities from wet-process phosphoric acid using a mixed solvent comprises the following steps: Preparation of mixed solvent: First, mix solvent C272 and P204 in an equal volume ratio of 1:1 to obtain solvent B, and then mix it with n-butanol in solvent A in a volume ratio of (solvent A=3:solvent B=0.5) for later use; (2) extracting the mixed solvent of step (1) with wet-process phosphoric acid (P2O5 is 50%, MER value is 11%) in a volume ratio of 3:1, the extraction time is 10 minutes, and the extraction temperature is 30°C; after the extraction is completed, the phases are allowed to stand for 10 minutes to separate, and the phosphorus-containing organic phase and the residual acid are separated; (3) washing the organic phase containing phosphorus in step (2), adding washing acid with a P2O5 content of 38% and a metal ion content of less than 5 ppm, reacting the washing phase in a ratio of 7:1 for 10 min at a reaction temperature of 30°C. After the reaction is completed, standing for 10 min to separate the phases, and separating the washed organic phase and the residual washing acid; (4) The organic phase after washing in step (3) is added with UP water at a volume ratio of 5:1 for stripping. The stripping time is 10 min and the reaction temperature is 30°C. After the reaction is completed, the phases are allowed to stand for 10 min to separate and obtain the stripping organic phase and stripping acid. The stripping organic phase can be recycled. The stripping acid is subjected to activated carbon adsorption, hydrogen peroxide bleaching, and concentration to finally obtain purified 85 phosphoric acid.

[0025] The chemical analysis data of the purified 85 phosphoric acid in this example are shown in the following table:

[0026] Example 4 like Figure 1 As shown, a method for removing metal impurities from wet-process phosphoric acid using a mixed solvent comprises the following steps: Preparation of mixed solvent: First, mix the solvent MIBK and n-butanol in an equal volume ratio of 1:1 to obtain solvent A, and then mix it with P350 in solvent B in a volume ratio of (solvent A=2:solvent B=0.5) for later use; (2) extracting the mixed solvent of step (1) with wet-process phosphoric acid (P2O5 is 50%, MER value is 11%) in a volume ratio of 4:1, the extraction time is 10 minutes, and the extraction temperature is 25°C; after the extraction is completed, the phases are allowed to stand for 10 minutes to separate, and the phosphorus-containing organic phase and the residual acid are separated; (3) washing the organic phase containing phosphorus in step (2), adding washing acid with a P2O5 content of 38% and a metal ion content of less than 5 ppm, reacting the washing phase in a ratio of 7:1 for 10 min at a reaction temperature of 30°C. After the reaction is completed, standing for 10 min to separate the phases, and separating the washed organic phase and the residual washing acid; (4) The organic phase after washing in step (3) is added with UP water at a volume ratio of 5:1 for stripping. The stripping time is 10 min and the reaction temperature is 30°C. After the reaction is completed, the phases are allowed to stand for 10 min to separate and obtain the stripping organic phase and stripping acid. The stripping organic phase can be recycled. The stripping acid is subjected to activated carbon adsorption, hydrogen peroxide bleaching, and concentration to finally obtain purified 85 phosphoric acid.

[0027] The chemical analysis data of the purified 85 phosphoric acid in this example are shown in the following table:

[0028] Example 5 like Figure 1 As shown, a method for removing metal impurities from wet-process phosphoric acid using a mixed solvent comprises the following steps: (1) Preparation of mixed solvent: First, the solvent MIBK and n-butanol were mixed in an equal volume ratio of 1:1 to obtain solvent A; then, P350 and dioctyl phosphate were mixed in a volume ratio of 1:1 to obtain solvent B; finally, solvent A = 3: solvent B = 0.5 were mixed in a volume ratio for later use; (2) extracting the mixed solvent of step (1) with wet-process phosphoric acid (P2O5 is 50%, MER value is 11%) in a volume ratio of 3:1, the extraction time is 10 minutes, and the extraction temperature is 25°C; after the extraction is completed, the phases are allowed to stand for 10 minutes to separate, and the phosphorus-containing organic phase and the residual acid are separated; (3) washing the organic phase containing phosphorus in step (2), adding washing acid with a P2O5 content of 38% and a metal ion content of less than 5 ppm, reacting the washing phase in a ratio of 7:1 for 10 min at a reaction temperature of 30°C. After the reaction is completed, standing for 10 min to separate the phases, and separating the washed organic phase and the residual washing acid; (4) The organic phase after washing in step (3) is added with UP water at a volume ratio of 5:1 for stripping. The stripping time is 10 min and the reaction temperature is 30°C. After the reaction is completed, the phases are allowed to stand for 10 min to separate and obtain the stripping organic phase and stripping acid. The stripping organic phase can be recycled. The stripping acid is subjected to activated carbon adsorption, hydrogen peroxide bleaching, and concentration to finally obtain purified 85 phosphoric acid.

[0029] The chemical analysis data of the purified 85 phosphoric acid in this example are shown in the following table:

[0030] Example 6 like Figure 1 As shown, a method for removing metal impurities from wet-process phosphoric acid using a mixed solvent comprises the following steps: (1) Preparation of mixed solvent: First, the solvent MIBK and tributyl phosphate were mixed in an equal volume ratio of 1:1 to obtain solvent A; then, P350 and C272 were mixed in an equal volume ratio of 1:1 to obtain solvent B; finally, solvent A = 4: solvent B = 0.5 were mixed in a volume ratio for later use; (2) extracting the mixed solvent of step (1) with wet-process phosphoric acid (P2O5 is 50%, MER value is 11%) in a volume ratio of 3:1, the extraction time is 10 minutes, and the extraction temperature is 25°C; after the extraction is completed, the phases are allowed to stand for 10 minutes to separate, and the phosphorus-containing organic phase and the residual acid are separated; (3) washing the organic phase containing phosphorus in step (2), adding washing acid with a P2O5 content of 38% and a metal ion content of less than 5 ppm, reacting the washing phase in a ratio of 7:1 for 10 min at a reaction temperature of 30°C. After the reaction is completed, standing for 10 min to separate the phases, and separating the washed organic phase and the residual washing acid; (4) The organic phase after washing in step (3) is added with UP water at a volume ratio of 5:1 for stripping. The stripping time is 10 min and the reaction temperature is 30°C. After the reaction is completed, the phases are allowed to stand for 10 min to separate and obtain the stripping organic phase and stripping acid. The stripping organic phase can be recycled. The stripping acid is subjected to activated carbon adsorption, hydrogen peroxide bleaching, and concentration to finally obtain purified 85 phosphoric acid.

[0031] The chemical analysis data of the purified 85 phosphoric acid in this example are shown in the following table:

[0032] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes within the equivalent meaning and scope of the claims be included within the scope of protection of the present invention.

Claims

1. A method for removing metal impurities from wet-process phosphoric acid using a mixed solvent, characterized in that: The solvent A and the solvent B are mixed evenly and then mixed with the raw material wet-process phosphoric acid for extraction, and 85% phosphoric acid is obtained through separation, washing, stripping and concentration; the solvent A is a mixture of one or more of methyl isobutyl ketone, n-butanol and tributyl phosphate; the solvent B is a mixture of one or more of dimethylheptyl methylphosphonate, bis(2,4,4-trimethylpentyl)phosphonic acid, 2-ethylhexyl mono-2-ethylhexyl phosphate, dioctyl phosphate and dialkyl dithiophosphonic acid.

2. The method according to claim 1, characterized in that The solvent A and solvent B are uniformly mixed in a volume ratio of (2-4):0.

5.

3. The method according to claim 2, characterized in that The solvent A is one or two of methyl isobutyl ketone, n-butanol, and TBP tributyl phosphate, which are mixed in equal volumes; the solvent B is one or more of dimethylheptyl methylphosphonate, bis(2,4,4-trimethylpentyl)phosphonic acid, 2-ethylhexyl mono-2-ethylhexyl phosphate, dioctyl phosphate, and dialkyl dithiophosphonic acid, which are mixed in equal volumes.

4. The method according to claim 1, characterized in that: The volume ratio of the mixture of solvent A and solvent B to the extraction of raw wet-process phosphoric acid is (2-4):

1.

5. The method according to claim 1, characterized in that The extraction time is 10-20 minutes, and the extraction temperature is 25-30°C.

6. The method according to claim 1, characterized in that The washing method uses phosphoric acid with low metal impurity content as raw material, wherein P2O5: 36-38%, and the metal impurity content is less than 2ppm.

7. The method according to claim 1, characterized in that The stripping raw material is UP water, and the stripping ratio is 5:

1.

8. The method according to any one of claims 1 to 7, characterized in that: The raw material wet-process phosphoric acid contains P2O5 of 45-52% and a MER value of 10-12%.

9. The method according to claim 6, characterized in that The volume ratio of the washing medium is 7:1.

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