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JP-7854995-B2 - Method for removing fluoride from alkaline hydroxide solution

JP7854995B2JP 7854995 B2JP7854995 B2JP 7854995B2JP-7854995-B2

Inventors

  • ボルン，ニルス－オロフ，ヨアヒム
  • ジャコミニ，マッティア
  • ゲルケ，ビルギット
  • ゼーラー，ファビアン
  • ローデ，ヴォルフガング
  • シールレ－アルント，ケルシュティン
  • フォーゲルザンク，レギナ

Assignees

  • ビーエーエスエフ ソシエタス・ヨーロピア

Dates

Publication Date
20260507
Application Date
20211119
Priority Date
20201120

Claims (8)

  1. A method for extracting fluoride from a solution, wherein the solution is as follows: A method comprising contacting an alkaline earth salt containing a carbonate anion, an oxo anion, a sulfate anion, or a phosphate anion, and an alkaline earth salt containing a mixture of such anions or a mixture of such anions and a hydroxyl anion, and b) a solid-phase adsorbent selected from a cation-binding resin loaded with one or more trivalent cations selected from trivalent cations of Al, Ga, In, Fe, Cr, Sc, Y, La, and lanthanides, wherein the solution contains more than 0.1 moles per liter of alkali hydroxides and/or alkolates dissolved in a polar solvent selected from water, C1-C4 alcohols, and mixtures thereof.
  2. The method according to claim 1, wherein the solution is an alkaline aqueous solution.
  3. The solid-phase adsorbent is The method according to claim 1 or 2, selected from a) an alkaline earth salt comprising calcium phosphate, calcium hydroxyphosphate, calcium sulfate, magnesium carbonate, magnesium oxide, calcium hydroxyapatite and/or tricalcium phosphate, and b) a cation-bonded resin loaded with one or more trivalent cations selected from the trivalent cations of aluminum and lanthanum.
  4. The method according to claim 1 or 3, wherein the solution is an alkaline aqueous solution and/or methanol-alkaline solution containing more than 0.1 moles of alkali hydroxide and/or methanol per liter, and 50% by mass or more of the total liquid consists of water and/or methanol.
  5. The method according to any one of claims 1 to 4, wherein the alkali hydroxide is a lithium hydroxide and the alkali alcoholate is a lithium alcoholate .
  6. The method according to any one of claims 1 to 5, wherein the solution of the alkali hydroxide and/or alkolate contains 0.2 moles or more, or 0.35 moles or more, of alkali hydroxide and/or alkolate in a dissolved state per liter.
  7. The method according to any one of claims 1 to 6, wherein the contact between the alkaline solution and the solid-phase adsorbent is carried out at a pressure between 0.1 bar and 100 bar, and at a temperature higher than the melting point of the liquid under actual pressure conditions and below the boiling point of the liquid, or between 0°C and 150°C.
  8. The method according to any one of claims 1 to 7, wherein the solid-phase adsorbent (a) is a powder or granular material, or a material in the form of beads or pellets with a diameter (D 50 ) of 10 micrometers to 10 mm, or 100 micrometers to 5 mm.

Description

This application claims the benefits of European Patent Application No. 20208982.7, filed on November 20, 2020, the contents of which are incorporated herein by reference in their entirety. The project leading to this application is funded by the Bundesministerium für Wirtschaft und Energy (DE; FKZ: 16BZF101A), and all disclosures in this document are the responsibility of the applicant. This disclosure relates to a method for extracting fluoride from a high pH, typically pH 13 or higher, alkaline aqueous solution, characterized by contacting an alkaline solution with a solid-phase adsorbent selected from alkaline earth salts containing carbonate anions, oxo anions, sulfate anions, phosphate anions, or mixtures thereof, or mixtures thereof with hydroxyl anions, and cation-binding resins loaded with one or more trivalent cations. An example of application of this method is the removal of fluoride from a solution of lithium hydroxide obtained from used lithium-ion batteries. Removing fluoride from aqueous solutions is often necessary in the treatment of drinking water. Ion exchange is one common method for defluoridating drinking water with a pH near neutral. One application of this method is the recovery of high-purity lithium hydroxide from lithium-containing resources that also contain fluoride ions. Such resources may be geological, for example, lepidolite (a lithium mineral), or anthropogenic waste lithium-ion batteries containing at least one transition metal selected from nickel, manganese, and cobalt. A typical method for lithium extraction from lepidolite is calcining the mineral with limestone. From a solution of the mineral containing lithium hydroxide and lithium fluoride, most of the lithium fluoride can be removed after concentration and filtration. The resulting filtrate may still contain low amounts of fluoride, determined by solution equilibrium. Similar situations can occur in the recycling of lithium-ion batteries or lithium-ion battery materials. In recycling, lithium is extracted as lithium hydroxide and/or lithium carbonate, and the material and liquid stream typically also contain fluoride. International Publication No. WO2020/011765 describes such extraction, particularly in its Examples 2–4. Fluoride-containing lithium hydroxide solutions may also result from the electrochemical conversion of solutions of lithium salts, such as lithium chloride or lithium sulfate. Such electrochemical conversions, including electrolysis or electrodialysis, are also described in the context of lithium-ion batteries or the recycling of lithium-ion battery materials (WO2014138933, EP2906730). The alkaline solutions treated by this disclosure may also arise from lithium-containing materials such as brine, ore, slag, and flue gas ash. The amount of fluoride impurities is typically about 121 ppm or more, e.g., about 300 ppm or more, or about 500 ppm or more, e.g., 1% or more, 0.05–5%, or 1.4–3.2% of ionic fluorides, each relative to the total mass of lithium contained, and dissolved in such liquids. The alkali salts present include hydroxides and alcoholates. In the case of lithium hydroxide, it may exist in a dry form, either anhydrous or as lithium hydroxide monohydrate. The liquid may contain one or more further impurities from the group of other alkali salts, aluminum salts, and/or zinc salts. The total amount of alkali, aluminum, and zinc impurities is approximately 100 to 500 ppm or more, for example, approximately 500 to 10,000 ppm, or approximately 500 to 5,000 ppm, relative to the dry mass of the crude alkali hydroxide (or alkole) solid. High concentrations of hydroxyl ions are known to displace fluoride from potential binding sites on adsorbents, allowing them to exist at high pH values (P. Loganathan et al., J. Haz. Mat. 248-249 (2013), see, for example, Figure 1 on page 3 and paragraph 3.1 on page 4; Loganathan also reported numerous adsorbents that are active in the pH range below 12). International public access number WO2020/011765WO2014138933EP2906730 P. Loganathan et al. , J. Haz. Mat. 248-249 (2013) Figure 1 shows the configuration of a column for reducing fluoride at high pH according to this disclosure.Figure 2 shows a block flow diagram of the lithium leaching process starting from black lumps (particulate matter, PM) obtained from waste lithium-ion batteries, illustrating the fluoride reduction process of the present invention, exemplified by the F-adsorption step onto apatite.Figure 3 shows a block flow diagram of another embodiment of a lithium leaching process starting from black lumps (particulate matter, PM) obtained from waste lithium-ion batteries, illustrating the fluoride reduction process of the present invention, exemplified by the F-adsorption step to apatite.Figure 4 shows the X-ray powder diffraction pattern (Mo Ka) of the reduced aggregate from the waste lithium-ion battery after heating/reduction treatment, obtained in Example 1a and used in Educt Example 2a, as well as