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CN-121992195-A - Method for selectively extracting and separating vanadium and aluminum from oxalic acid system

CN121992195ACN 121992195 ACN121992195 ACN 121992195ACN-121992195-A

Abstract

The invention provides a method for selectively extracting and separating vanadium and aluminum from an oxalic acid system, and relates to the technical field of extraction. Firstly, uniformly mixing trioctyl ammonium methyl oxalate, triethyl phosphate and light white oil to obtain an organic phase, then adjusting the pH value of an oxalic acid system containing vanadium and aluminum to 1-4 to obtain a pretreated oxalic acid system, then mixing the organic phase with the pretreated oxalic acid system, carrying out countercurrent extraction to obtain a loaded organic phase and vanadium-containing residual liquid, and further carrying out countercurrent back extraction after adding acid to the loaded organic phase to obtain a lean organic phase and aluminum-containing residual liquid. The extractant used in the method is environment-friendly, the extractant dosage is small, the cost is low, the extraction capacity is strong, and the finally obtained lean organic phase can be recycled after being treated.

Inventors

  • LIU ZISHUAI
  • LI QIANWEN
  • LUO HENG
  • LIU WENBIN
  • LV YANCHENG

Assignees

  • 江西理工大学

Dates

Publication Date
20260508
Application Date
20251223

Claims (10)

  1. 1. A method for selectively extracting and separating vanadium and aluminum in an oxalic acid system, which is characterized by comprising the following steps: S1, uniformly mixing trioctyl ammonium oxalate, triethyl phosphate and light white oil to obtain an organic phase; S2, adjusting the pH value of the oxalic acid system containing vanadium and aluminum to 1-4 to obtain a pretreated oxalic acid system; S3, mixing the organic phase with the pretreated oxalic acid system, and carrying out countercurrent extraction to obtain a loaded organic phase and vanadium-containing residual liquid; s4, carrying out countercurrent back extraction on the loaded organic phase after adding acid to obtain an organic-lean phase and an aluminum-containing residual liquid.
  2. 2. The method for selectively extracting and separating vanadium and aluminum in an oxalic acid system according to claim 1, wherein the trioctyl ammonium oxalate and the triethyl phosphate in the S1 occupy 10-40% of the total mass of an organic phase, and the mass ratio of the trioctyl ammonium oxalate to the triethyl phosphate is 1:1.
  3. 3. The method for selectively extracting and separating vanadium and aluminum in an oxalic acid system according to claim 1, wherein the concentration of oxalic acid radical in the oxalic acid system containing vanadium and aluminum in the S2 is 50-300 g/L, the pH value is not more than 1.5, and the concentration of vanadium and aluminum ions is not more than 8g/L.
  4. 4. The method for selectively extracting and separating vanadium from aluminum in oxalic acid system according to claim 1, wherein the pH adjustment of the oxalic acid system in S2 is performed by sodium hydroxide or potassium hydroxide.
  5. 5. The method for selectively extracting and separating vanadium and aluminum in an oxalic acid system according to claim 1, wherein the volume ratio of the organic phase in the step S3 to the pretreated oxalic acid system is 1:2-1:5.
  6. 6. The method for selectively extracting and separating vanadium from aluminum in oxalic acid system according to claim 1, wherein the countercurrent extraction in S3 is not less than two stages, and the obtained vanadium-containing raffinate is used for extracting vanadium.
  7. 7. The method for selectively extracting and separating vanadium from aluminum in oxalic acid system according to claim 1, wherein the acid in S4 is sulfuric acid with a volume concentration of 20%.
  8. 8. The method for selectively extracting and separating vanadium from aluminum in an oxalic acid system according to claim 1, wherein the volume ratio of the loaded organic phase to the acid in the S4 is 1:2-1:5.
  9. 9. The method for selectively extracting and separating vanadium and aluminum in an oxalic acid system according to claim 1, wherein the countercurrent back extraction in S4 is not less than two stages, and the obtained aluminum-containing raffinate is used for extracting aluminum.
  10. 10. The method for selectively extracting and separating vanadium and aluminum in oxalic acid system according to claim 1, wherein the lean organic phase obtained in S4 is mixed with an alkali solution for back extraction to obtain trioctylmethyl ammonium hydroxide, and the obtained trioctylmethyl ammonium hydroxide is mixed with oxalic acid solution for back extraction to obtain a regenerated organic phase to participate in extraction.

Description

Method for selectively extracting and separating vanadium and aluminum from oxalic acid system Technical Field The invention relates to the technical field of extraction, in particular to a method for selectively extracting and separating vanadium and aluminum from a oxalic acid system. Background Oxalic acid is a good reducing agent and complexing agent, and is widely applied to the production of metallic oxalate in the industries of metallurgy, chemical industry and the like. In the process of precipitating metals by using oxalic acid, a large amount of oxalic acid leaching liquid is often generated, and the oxalic acid leaching liquid is purified and enriched with valuable metals by adopting a solvent extraction method. Liu et al （Zishuai Liu, Jing Huang, Yimin Zhang, et al. Separation and Recovery of Vanadium and Iron from Oxalic-acid-based Shale Leachate by Coextraction and Stepwise Stripping[J]. Separation and Purification Technology. 2020, 244, 116532） used trioctylmethyl ammonium chloride as extractant, separated and recovered vanadium and iron from the vanadium shale oxalic acid leaching solution by co-extraction and step-by-step back extraction, and the leaching solution was subjected to 6-stage countercurrent extraction under conditions of initial pH=0.66, extractant concentration of 40% and O/A ratio of 1:2, with vanadium and iron extraction rates of 98.60% and 99.64%, respectively, and oxalate co-extraction rate of 60.16%. The obtained loaded organic phase is subjected to step back extraction to obtain qualified vanadium-rich liquid. The process finally realizes the separation of vanadium and iron, obtains qualified vanadium-rich liquid, and prepares corresponding vanadium products, but when trioctyl methyl ammonium chloride is adopted for extraction, a large amount of raffinate containing chloride ions is generated. Because hydrochloric acid has strong volatility and corrosiveness, the direct return of the extraction waste liquid to oxalic acid leaching has great influence on leaching conditions, equipment and environment. In addition, when trioctyl methyl ammonium chloride is adopted for extraction, oxalic acid radical is also extracted in a large amount, so that the concentration of the extractant is extremely high and reaches 40%, and the extraction cost is high. CN10108573a discloses adsorption of oxalic acid with ion exchange resins and recovery of oxalic acid by desorption with aqueous ammonia. The method can realize the recycling of oxalic acid in oxalic acid leaching liquid, and the valuable metals and inorganic acid in waste water are still neutralized and discharged by adding alkali, so that the full utilization of resources is not realized, and the serious environmental pollution is caused. In summary, the existing extraction technology from oxalic acid-containing systems has the problems of large extractant consumption, high production cost, serious oxalate co-extraction, incapability of directly recycling raffinate, no oxalic acid recovery and the like. Disclosure of Invention In order to solve the technical problems in the prior art, the embodiment of the invention provides a method for selectively extracting and separating vanadium and aluminum in an oxalic acid system. The technical scheme is as follows: a method for selectively extracting and separating vanadium and aluminum from an oxalic acid system, comprising: S1, uniformly mixing trioctyl ammonium oxalate, triethyl phosphate and light white oil to obtain an organic phase; S2, adjusting the pH value of the oxalic acid system containing vanadium and aluminum to 1-4 to obtain a pretreated oxalic acid system; S3, mixing the organic phase with the pretreated oxalic acid system, and carrying out countercurrent extraction to obtain a loaded organic phase and vanadium-containing residual liquid; s4, carrying out countercurrent back extraction on the loaded organic phase after adding acid to obtain an organic-lean phase and an aluminum-containing residual liquid. In the S1, the trioctyl ammonium oxalate and the triethyl phosphate occupy 10-40% of the total mass of the organic phase, and the mass ratio of the trioctyl ammonium oxalate to the triethyl phosphate is 1:1. The concentration of oxalic acid radical in the oxalic acid system containing vanadium and aluminum in the S2 is 50-300 g/L, the pH value is not more than 1.5, and the concentration of vanadium and aluminum ions is not more than 8g/L. The pH of the oxalic acid system in the step S2 is adjusted by sodium hydroxide or potassium hydroxide. And the volume ratio of the organic phase to the pretreated oxalic acid system in the step S3 is 1:2-1:5. And (3) countercurrent extraction in the step (S3) is not less than two stages, and the obtained vanadium-containing residual liquid is used for extracting vanadium. The acid in the S4 is sulfuric acid with the volume concentration of 20%. And the volume ratio of the loaded organic phase to the acid in the S4 is 1:2-1:5. And (4) co