# US 2025/0154625 A1 · Method for recovering extractant in aqueous solution, and method for separating and recovering metal from aqueous metal solution > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0154625 A1 - Document ID: US20250154625A1 - Status: Published application - Kind: A1 - Application number: 18/839,190 - Filed: 2022-10-20 - Published: 2025-05-15 - Earliest claimed: 2022-02-18 - Assignees: Jx Metals Circular Solutions Co., Ltd. - Applicants: Jx Metals Circular Solutions Co., Ltd - Inventors: Junichi ARAKAWA - Web page: https://patentgrep.com/patent/US20250154625A1 ## CPC - C22B 3/38: containing phosphorus - H01M 10/54: Reclaiming serviceable parts of waste accumulators - B01D 11/04: of solutions which are liquid - B01D 11/0488: {Flow sheets} - B01D 11/0492: {Applications, solvents used} - C22B 3/326: {Ramified chain carboxylic acids or derivatives thereof, e.g. "versatic" acids} - C22B 3/3844: {Phosphonic acid, e.g. H2P(O)(OH)2} - C22B 23/0461: {by chemical methods} - Y02P 10/20: Recycling - Y02W 30/84: Recycling of batteries or fuel cells - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS - Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT ## Abstract A method for recovering neodecanoic acid or a phosphonate ester-based extractant from an aqueous solution containing the neodecanoic acid or the phosphonate ester-based extractant, wherein an equilibrium pH is 5.5 or less when the neodecanoic acid or the phosphonate ester-based extractant is recovered. ## Claims ### Claim 1 A method for recovering neodecanoic acid or a phosphonate ester-based extractant from an aqueous solution comprising the neodecanoic acid or the phosphonate ester-based extractant, wherein an equilibrium pH is 5.5 or less when the neodecanoic acid or the phosphonate ester-based extractant is recovered. ### Claim 2 (depends on 1) The method for recovering an extractant in an aqueous solution according to claim 1, wherein the neodecanoic acid or the phosphonate ester-based extractant is separated from the aqueous solution at the equilibrium pH, and the neodecanoic acid or the phosphonate ester-based extractant is recovered. ### Claim 3 (depends on 1) The method for recovering an extractant in an aqueous solution according to claim 1, wherein the aqueous solution is brought into contact with a solvent, the neodecanoic acid or the phosphonate ester-based extractant is transferred from the aqueous solution to the solvent at the equilibrium pH, and the solvent is then separated and the neodecanoic acid or the phosphonate ester-based extractant is recovered into the solvent. ### Claim 4 (depends on 1) The method for recovering an extractant in an aqueous solution according to claim 1, wherein the equilibrium pH during recovery of the phosphonate ester-based extractant is 5.0 or less. ### Claim 5 (depends on 1) The method for recovering an extractant in an aqueous solution according to claim 1, wherein a TOC in the aqueous solution is 200 mg/L or more. ### Claim 6 (depends on 1) The method for recovering an extractant in an aqueous solution according to claim 1, wherein the aqueous solution has a pH of 6 to 8 before recovering the neodecanoic acid or the phosphonate ester-based extractant. ### Claim 7 A method for separating and recovering metals from an aqueous metal solution, the method comprising: a solvent extraction step of subjecting the aqueous metal solution to solvent extraction with a solvent comprising neodecanoic acid or a phosphonate ester-based extractant to extract metals contained in the aqueous metal solution; and a recovery step of recovering the neodecanoic acid or the phosphonate ester-based extractant from an extracted solution obtained after extracting the metals in the solvent extraction step, wherein an equilibrium pH during recovery in the recovery step is lower than an equilibrium pH during extraction in the solvent extraction step. ### Claim 8 (depends on 7) The method for separating and recovering metals from an aqueous metal solution according to claim 7, wherein, in the recovery step, the neodecanoic acid or the phosphonate ester-based extractant is separated from the extracted solution at the equilibrium pH, and the neodecanoic acid or the phosphonate ester-based extractant is recovered. ### Claim 9 (depends on 7) The method for separating and recovering metals from an aqueous metal solution according to claim 7, wherein, in the recovery step, the extracted solution is brought into contact with a solvent, and the neodecanoic acid or the phosphonate ester-based extractant is transferred from the extracted solution to the solvent at the equilibrium pH, and the solvent is then separated and the neodecanoic acid or the phosphonate ester-based extractant is recovered into the solvent. ### Claim 10 (depends on 9) The method for separating and recovering metals from an aqueous metal solution according to claim 9, wherein the solvent used in the recovery step comprises the same neodecanoic acid or phosphonate ester-based extractant as the neodecanoic acid or the phosphonate ester-based extractant contained in the solvent used in the solvent extraction step. ### Claim 11 (depends on 7) The method for separating and recovering metals from an aqueous metal solution according to claim 7, wherein the solvent used in the solvent extraction step comprises neodecanoic acid, and wherein the equilibrium pH during recovery in the recovery step is 5.5 or less. ### Claim 12 (depends on 7) The method for separating and recovering metals from an aqueous metal solution according to claim 7, wherein the solvent used in the solvent extraction step comprises a phosphonate ester-based extractant, and wherein the equilibrium pH during recovery in the recovery step is 5.0 or less. ### Claim 13 (depends on 7) The method for separating and recovering metals from an aqueous metal solution according to claim 7, wherein a TOC in the extracted solution after extracting the metals in the solvent extraction step is 200 mg/L or more. ### Claim 14 (depends on 7) The method for separating and recovering metals from an aqueous metal solution according to claim 7, wherein the extracted solution after extracting the metals in the solvent extraction step has a pH of 6 to 8. ### Claim 15 (depends on 14) The method for separating and recovering metals from an aqueous metal solution according to claim 14, wherein the solvent extraction step comprises a plurality of extraction steps, wherein the solvent and the aqueous metal solution used in the solvent extraction step undergo the plurality of extraction steps in the reversed order to each other, and wherein the equilibrium pH in the last extraction step that is undergone by the aqueous metal solution among the plurality of extraction steps is 6 to 8. ### Claim 16 (depends on 9) The method for separating and recovering metals from an aqueous metal solution according to claim 9, wherein the solvent used in the recovery step is derived from an organic phase after being subjected to the solvent extraction step. ### Claim 17 (depends on 7) The method for separating and recovering metals from an aqueous metal solution according to claim 7, wherein the solvent recovered in the recovery step is used as a solvent in the solvent extraction step.