Purification method of raffinate acid

Abstract

The invention provides a method for purifying raffinate acid, which comprises the following steps: mixing a quaternary ammonium salt eutectic solvent and the raffinate acid, extracting, standing and separating liquid to obtain the purified raffinate acid, the quaternary ammonium salt eutectic solvent is obtained by mixing and stirring quaternary ammonium salt and fatty acid to react. Metal ions are removed through the eutectic solvent, the method has the advantages that the preparation process is simple, raw materials are easy to obtain, purification is not needed, cost is low and the like, the content of impurities in the raffinate acid can be effectively reduced, and conditions are directly or indirectly created for recycling of phosphorus resources.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wet-process phosphoric acid purification, in particular to a purification method of raffinate acid. BACKGROUND

[0002] With the development of phosphate fertilizer industry in China, the phosphate rock with content of more than 30% is increasingly scarce, and the Ministry of Land and Resources has listed the phosphate rock as one of the 20 mineral resources which cannot meet the requirements of national economic development after 2010. At present, the preparation of phosphoric acid in industry mainly adopts hot process and wet process. The wet-process phosphoric acid mainly adopts sulfuric acid method, but in the process of preparing the wet-process phosphoric acid, the leaching solution contains a large amount of soluble metal salts such as magnesium, aluminum and iron, which leads to a large amount of raffinate acid after extracting phosphoric acid. Although the existing organic solvent extraction process such as phosphoric acid ester, fatty alcohol and ketone can extract phosphoric acid in the wet-process phosphoric acid, the raffinate acid is the raffinate of the phosphoric acid extraction section, has a large viscosity, has been extracted for many times previously, and the remaining phosphorus resources are recovered by using the phosphoric acid extractant. Meanwhile, the metal salt content in the raffinate acid is very high, and a large amount of metal is brought into the organic phase during the secondary extraction of phosphoric acid, thereby causing the metal salt content in the extracted phosphoric acid to exceed the standard, and if the extracted phosphoric acid is returned to the extraction section for reuse, the purity of the existing wet-process phosphoric acid will be greatly affected. If a new type of extractant with good extraction ability and selectivity to metal ions can be prepared, the metal salt in the raffinate acid can be extracted and removed, so that the content of the metal salt in the raffinate acid can be greatly reduced, thereby meeting the requirements of reuse of the raffinate acid.

[0003] The raffinate acid and refined phosphoric acid are produced in the same proportion, and the P2O5 content in the raffinate acid is more than 30%. If the raffinate acid is not utilized, not only the phosphorus resources will be wasted, but also a large amount of industrial waste liquid will be produced, which brings great environmental problems to the production. Therefore, it is urgent to remove the impurities in the raffinate acid and reduce the content of the metal (sesquioxide) in the raffinate acid, so that the phosphorus resources in the raffinate acid can be recycled and reused to enter the phosphoric acid extraction device, thereby realizing the recycling and reuse of the phosphorus resources in the raffinate acid waste liquid, reducing the loss rate of phosphorus in the wet-process phosphoric acid industry, and having important significance for improving the utilization rate of phosphorus resources. Therefore, the quaternary ammonium salt eutectic solvent with good solubility to metal ions is used to extract the raffinate acid, so that the concentration of the metal ions in the raffinate acid is effectively reduced, and more favorable conditions are created for the organic solvent extraction of the wet-process phosphoric acid. SUMMARY

[0004] Therefore, the present application aims to solve the technical problem of providing a purification method of raffinate acid, and the method provided by the present application has good purification effect on the raffinate acid.

[0005] The present application provides a purification method of raffinate acid, which comprises the following steps:

[0006] The purified raffinate acid is obtained after the quaternary ammonium salt-based deep eutectic solvent and the raffinate acid are mixed for extraction and static separation.

[0007] In some embodiments, the raffinate acid contains 20-48 wt% P2O5, 0.1-1.8 wt% iron oxide, 0.8-2.8 wt% magnesium oxide, 1.2-3.4 wt% aluminum oxide, and 0.2-1.2 wt% calcium oxide.

[0008] In some embodiments, the quaternary ammonium salt is at least one of methyl tributyl ammonium chloride, tetrabutyl ammonium chloride, tetraoctyl ammonium chloride, methyl trioctyl ammonium chloride, ethyl trioctyl ammonium chloride, butyl trioctyl ammonium chloride, and hexyl trioctyl ammonium chloride.

[0009] In some embodiments, the fatty acid is at least one of heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, and oleic acid.

[0010] In some embodiments, the molar ratio of the quaternary ammonium salt to the fatty acid is (0.5-3):1.

[0011] In some embodiments, the stirring reaction is performed at a temperature of 60-100°C for 1-8 hours at a stirring speed of 100-200 rpm / min.

[0012] In some embodiments, the extraction is performed at a temperature of 20-60°C.

[0013] In some embodiments, the extraction is performed for 10-60 minutes.

[0014] In some embodiments, the volume ratio of the quaternary ammonium salt-based deep eutectic solvent to the raffinate acid is 1:1-6:1.

[0015] In some embodiments, the raffinate acid further includes a pretreatment, which includes allowing the raffinate acid to stand and taking the supernatant; the standing time is ≥20 hours.

[0016] Compared with the prior art, the present application provides a purification method for raffinate acid, which includes: mixing a quaternary ammonium salt-based deep eutectic solvent and a raffinate acid for extraction, and obtaining a purified raffinate acid after static separation; the quaternary ammonium salt-based deep eutectic solvent is obtained by mixing and stirring a quaternary ammonium salt and a fatty acid. The present application removes metal ions by using a deep eutectic solvent, has the advantages of simple preparation process, easily available raw materials, no need for purification, and low cost, and can effectively reduce the impurity content in the raffinate acid, thereby directly or indirectly creating conditions for the recycling of phosphorus resources. DETAILED DESCRIPTION

[0017] The present application provides a kind of purification method of raffinate acid, and those skilled in the art can improve process parameters appropriately according to the content herein to realize.It is particularly pointed out that all similar substitutions and changes are obvious to those skilled in the art, and they all belong to the scope protected by the present application.The method and application of the present application have been described by preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application herein without departing from the content, spirit and scope of the present application to realize and apply the present application technology.

[0018] The present application discloses a kind of purification method of raffinate acid, and those skilled in the art can improve process parameters appropriately according to the content herein to realize.It is particularly pointed out that all similar substitutions and changes are obvious to those skilled in the art, and they all belong to the scope protected by the present application.The method and application of the present application have been described by preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application herein without departing from the content, spirit and scope of the present application to realize and apply the present application technology.

[0019] The present application provides a kind of purification method of raffinate acid, and those skilled in the art can improve process parameters appropriately according to the content herein to realize.It is particularly pointed out that all similar substitutions and changes are obvious to those skilled in the art, and they all belong to the scope protected by the present application.The method and application of the present application have been described by preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application herein without departing from the content, spirit and scope of the present application to realize and apply the present application technology.

[0020] The present application provides a kind of purification method of raffinate acid, and those skilled in the art can improve process parameters appropriately according to the content herein to realize.It is particularly pointed out that all similar substitutions and changes are obvious to those skilled in the art, and they all belong to the scope protected by the present application.The method and application of the present application have been described by preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application herein without departing from the content, spirit and scope of the present application to realize and apply the present application technology.

[0021] In some embodiments, the P2O5 content of the raffinate acid is 20-48 wt%, the Fe2O3 content is 0.1-1.8 wt%, the MgO content is 0.8-2.8 wt%, the Al2O3 content is 1.2-3.4 wt%, and the CaO content is 0.2-1.2 wt%.

[0022] The present application does not limit the raffinate acid, which is well known to those skilled in the art.

[0023] In some embodiments, the raffinate acid further includes a pretreatment, which includes allowing the raffinate acid to stand and taking the supernatant; the standing time is ≥20 h; more preferably, 20-24 h; specifically, 20 h, 21 h, 22 h, 23 h, or 24 h; preferably, 24 h.

[0024] The quaternary ammonium salt-based deep eutectic solvent includes a quaternary ammonium salt and a fatty acid obtained by mixing and stirring reaction.

[0025] The present application uses the quaternary ammonium salt and the fatty acid to cooperatively prepare the quaternary ammonium salt-based deep eutectic solvent, which has good selectivity for metal ions in the raffinate acid, effectively reduces the content of metal ions in the raffinate acid, and improves the purity of the wet-process phosphoric acid and the utilization rate of phosphorus resources.

[0026] In some embodiments, the quaternary ammonium salt is selected from at least one of methyltributylammonium chloride, tetrabutylammonium chloride, tetraoctylammonium chloride, methyltrioctylammonium chloride, ethyltrioctylammonium chloride, butyltrioctylammonium chloride, hexyltrioctylammonium chloride.

[0027] In some embodiments, the fatty acid is selected from at least one of heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, oleic acid.

[0028] In some embodiments, the molar ratio of the quaternary ammonium salt to the fatty acid is (0.5-3):1.

[0029] According to the present application, the molar ratio of the quaternary ammonium salt to the fatty acid is 0.5:1, 1:1, 2:1 or 3:1.

[0030] In some embodiments, the temperature of the stirring reaction is 60-100℃; specifically, it can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃.

[0031] The time is 1-8h; specifically, it can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h.

[0032] The speed of stirring is 100-200rpm / min; specifically, it can be 100rpm / min, 110rpm / min, 120rpm / min, 130rpm / min, 140rpm / min, 150rpm / min, 160rpm / min, 170rpm / min, 180rpm / min, 190rpm / min, 200rpm / min.

[0033] In some embodiments, the temperature of the extraction is 20-60℃; specifically, it can be 20℃, 30℃, 40℃, 50℃, 60℃.

[0034] In some embodiments, the time of the extraction is 10-60min; specifically, it can be 10min, 20min, 30min, 40min, 50min, 60min.

[0035] In some embodiments, the phase ratio of the quaternary ammonium salt-based deep eutectic solvent to the residual acid is 1:1-6:1; specifically, it can be 1:1, 2:1, 3:1, 4:1, 5:1 or 6:1.

[0036] The application provides a purification method of raffinate acid, comprising: mixing and extracting a quaternary ammonium salt eutectic solvent and the raffinate acid, and obtaining the purified raffinate acid after standing and separating; and the quaternary ammonium salt eutectic solvent is obtained by mixing and stirring a quaternary ammonium salt and a fatty acid. The metal ions are removed by the eutectic solvent, and the method has the advantages of simple preparation process, easily available raw materials, no need for purification and low cost, can effectively reduce the impurity content in the raffinate acid, and directly or indirectly creates conditions for the recycling of phosphorus resources.

[0037] It should be understood that the expression "one or more of" individually includes each object recited after the expression and various different combinations of two or more of the recited objects, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited objects should be understood to have the same meaning, unless otherwise understood from the context.

[0038] The use of the term "include", "have" or "contain", including the grammatical synonyms thereof, should generally be understood as open and non-limiting, for example, not excluding other non-recited elements or steps, unless otherwise specifically stated or understood from the context.

[0039] In this application, the term "and / or" describes the association relationship of associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent: A exists alone, A and B exist together, and B exists alone. Wherein A, B can be singular or plural.

[0040] In this application, "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single item or multiple items.

[0041] It should be understood that the order of steps or the order of performing certain actions is not important as long as the application is still operable. In addition, two or more steps or actions can be performed simultaneously.

[0042] The use of any and all examples, or exemplary language, such as "for example" or "including", in the present document, is intended merely to better illustrate the application and does not pose a limitation on the scope of the application unless claims are presented. Any language in the specification should not be interpreted as indicating any unclaimed element is essential to the practice of the application.

[0043] Also, the numerical ranges recited in the disclosure herein are approximations, and are intended to cover values approximating the stated ranges. Unless otherwise indicated, all ranges, numbers, values, and percentages recited in the disclosure herein are approximations. It is intended that the disclosure recited herein be interpreted to be flexible and that the recited ranges, numbers, values, and percentages are to be construed to encompass individual and subranges of the approximated ranges, unless otherwise indicated. Thus, for example, a range expressed as "1 to 10" is intended to encompass individual numbers, sub-ranges, and combinations thereof, such as 1 to 6.1, 2.1 to 4.8, 3.5, and 5.5 to 10, etc.

[0044] It should be understood that the size of the sequence of the above processes does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of the processes should be determined according to its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0045] Some cases are described in the embodiments and comparative examples of the present application, in which the embodiments show some implementations of the present application. However, this does not mean that the effects of the present application can only be achieved in these cases.

[0046] In order to further illustrate the present application, a purification method of raffinate acid provided by the present application is described in detail below in combination with embodiments.

[0047] Example 1

[0048] A raffinate acid sample was taken after standing for 24 h, and analysis and detection showed that the content of P2O5 in the upper clear liquid was 30.68 wt%, the content of iron oxide was 0.37 wt%, the content of magnesium oxide was 1.59 wt%, the content of aluminum oxide was 2.03 wt%, and the content of calcium oxide was 0.61 wt%. The upper clear liquid was extracted by a eutectic solvent synthesized by stirring tetrabutylammonium chloride and hexanoic acid at a molar ratio of 1:2 at 80°C for 2h, and the extraction conditions were: water to oil ratio 1:3, temperature 30°C, and time 30 min. The extraction rates of Al 3+ , Ca 2+ , Mg 2+ and Fe 3+ were 13.80%, 42.52%, 16.72% and 84.00%, respectively.

[0049] Example 2

[0050] A certain raffinate acid sample, after standing for 24h, the upper clear liquid was taken, analysis and detection showed that the content of P2O5 was 37.49wt%, the content of iron oxide was 0.41wt%, the content of magnesium oxide was 1.74wt%, the content of aluminum oxide was 2.37wt%, and the content of calcium oxide was 0.66wt%. The low eutectic solvent was synthesized by stirring at 80℃ for 2h with the molar ratio of methyltributylammonium chloride to hexanoic acid being 1:2, and the upper clear liquid was extracted. The extraction conditions were as follows: water to oil ratio 1:2, temperature 35℃, and time 30min. The extraction rates of Al 3+ , Ca 2+ , Mg 2+ and Fe 3+ were 12.93%, 66.61%, 17.73% and 78.53% respectively.

[0051] Example 3

[0052] A certain raffinate acid sample, after standing for 24h, the upper clear liquid was taken, analysis and detection showed that the content of P2O5 was 42.47wt%, the content of iron oxide was 0.29wt%, the content of magnesium oxide was 1.84wt%, the content of aluminum oxide was 2.08wt%, and the content of calcium oxide was 0.52wt%. The low eutectic solvent was synthesized by stirring at 80℃ for 2h with the molar ratio of tetraoctylammonium chloride to hexanoic acid being 1:2, and the upper clear liquid was extracted. The extraction conditions were as follows: water to oil ratio 1:2, temperature 35℃, and time 30min. The extraction rates of Al 3+ , Ca 2+ , Mg 2+ and Fe 3+ were 11.62%, 55.10%, 7.47% and 51.69% respectively.

[0053] Example 4

[0054] A certain raffinate acid sample, after standing for 24h, the upper clear liquid was taken, analysis and detection showed that the content of P2O5 was 40.92wt%, the content of iron oxide was 0.57wt%, the content of magnesium oxide was 1.97wt%, the content of aluminum oxide was 2.27wt%, and the content of calcium oxide was 0.71wt%. The low eutectic solvent was synthesized by stirring at 80℃ for 2h with the molar ratio of methyltrioctylammonium chloride to hexanoic acid being 1:2, and the upper clear liquid was extracted. The extraction conditions were as follows: water to oil ratio 1:2, temperature 35℃, and time 30min. The extraction rates of Al 3+ , Ca 2+ , Mg 2+ and Fe 3+ were 20.45%, 42.50%, 21.75% and 55.91% respectively.

[0055] Table 1 Performance of extractant for removing metal ions in raffinate acid

[0056]

[0057]

[0058] The above merely preferred embodiments of the present application, it should be noted that for those of ordinary skill in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered within the scope of the present application.

Claims

1. A method for purifying residual acid, characterized in that, include: The quaternary ammonium salt eutectic solvent and raffinate are mixed and extracted, and the purified raffinate is obtained after standing and separation; the quaternary ammonium salt eutectic solvent is obtained by mixing and stirring quaternary ammonium salt and fatty acid.

2. The method according to claim 1, characterized in that, The raffinate contains 20–48 wt% P2O5, 0.1–1.8 wt% iron oxide, 0.8–2.8 wt% magnesium oxide, 1.2–3.4 wt% aluminum oxide, and 0.2–1.2 wt% calcium oxide.

3. The method according to claim 1, characterized in that, The quaternary ammonium salt is selected from at least one of methyltributylammonium chloride, tetrabutylammonium chloride, tetraoctylammonium chloride, methyltrioctylammonium chloride, ethyltrioctylammonium chloride, butyltrioctylammonium chloride, and hexyltrioctylammonium chloride.

4. The method according to claim 1, characterized in that, The fatty acid is selected from at least one of the following: iodine, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, and oleic acid.

5. The method according to claim 1, characterized in that, The molar ratio of the quaternary ammonium salt to the fatty acid is (0.5–3):

1.

6. The method according to claim 1, characterized in that, The temperature of the stirring reaction is 60–100℃; the time is 1–8 h; and the stirring speed is 100–200 rpm / min.

7. The method according to claim 1, characterized in that, The extraction temperature is 20–60°C.

8. The method according to claim 1, characterized in that, The extraction time is 10–60 min.

9. The method according to claim 1, characterized in that, The volume ratio of the quaternary ammonium salt eutectic solvent to the residual acid is 1:1 to 6:

1.

10. The method according to claim 1, characterized in that, The residual acid also includes pretreatment, which includes allowing the residual acid to stand and taking the supernatant; the standing time is 20-24 hours (≥20 hours).

Images