# US 9,752,212 B2 · Method for extracting and separating rare-earth element > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,212 B2 - Document ID: US9752212B2 - Status: Granted - Kind: B2 - Application number: 14/389,300 - Filed: 2012-09-29 - Published: 2015-03-05 - Granted: 2017-09-05 - Earliest claimed: 2012-03-31 - Assignees: Changchun Institute of Applied Chemistry Chinese Academy of Science - Applicants: Changchun Institute of Applied Chemistry, Chinese Academy of Sciences - Inventors: Ji Chen; Lin Guo; Lu Shen; Yuefeng Deng; Jingbo Lan - Web page: https://patentgrep.com/patent/US9752212B2 ## CPC - C22B 59/00: Obtaining rare earth metals - C22B 3/04: by leaching (C22B3/18 takes precedence) - C22B 3/14: containing ammonia or ammonium salts - C22B 3/26: by liquid-liquid extraction using organic compounds - C22B 3/408: {using a mixture of phosphorus-based acid derivatives of different types} - Y02P 10/20: Recycling - C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract A method for extracting and separating a rare-earth element by extracting and separating the rare-earth element from an aqueous solution of rare-earth nitrate into n-heptane, with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester trialkyl methyl ammonium or di-2-ethylhexyl phosphoric acid trialkyl methyl ammonium as an extractant, and n-heptane as a diluent by contacting the aqueous solution of rare-earth nitrate with the extractant and the diluent to extract and separate the rare earth element into n-heptane from the aqueous solution of rare earth nitrate. ## Claims ### Claim 1 A method for extracting and separating a rare-earth element, comprising: extracting and separating the rare-earth element from an aqueous solution of rare-earth nitrate into n-heptane with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester trialkyl methyl ammonium or di-2-ethylhexyl phosphoric acid trialkyl methyl ammonium as an extractant, and n-heptane as a diluent by contacting the aqueous solution of rare-earth nitrate with the extractant and the diluent to extract and separate the rare earth element into n-heptane from the aqueous solution of rare earth nitrate. ### Claim 2 (depends on 1) The method for extracting and separating a rare-earth element according to claim 1, wherein the extraction temperature is 20˜50° C.; and/or wherein the aqueous solution of rare-earth nitrate has a concentration of 7˜9×10−4 mol/L; and/or wherein after extracting the rare-earth element from the aqueous solution of rare-earth nitrate into n-heptane, controlling the aqueous solution of rare-earth nitrate to have a pH of 1˜4; and/or wherein the rare-earth element is selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. ### Claim 3 (depends on 1) The method for extracting and separating a rare-earth element according to claim 1, further comprising mixing a NaNO3 solution with a concentration of 0.2˜1.5 mol/L as a salting-out agent with the aqueous solution of rare-earth nitrate. ### Claim 4 (depends on 3) The method for extracting and separating a rare-earth element according to claim 3, wherein the extracting the rare-earth element from the aqueous solution of rare-earth nitrate into n-heptane further comprises: mixing a solution of a quaternary ammonium ionic liquid extractant in n-heptane, the salting-out agent and the aqueous solution of rare-earth nitrate, and extracting the rare-earth element from the aqueous solution of rare-earth nitrate into n-heptane; the quaternary ammonium ionic liquid extractant being the 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester trialkyl methyl ammonium or the di-2-ethylhexyl phosphoric acid trialkyl methyl ammonium. ### Claim 5 (depends on 4) The method for extracting and separating a rare-earth element according to claim 4, wherein the solution of the quaternary ammonium ionic liquid extractant in n-heptane has a concentration of 0.03˜0.1 mol/L. ### Claim 6 (depends on 1) The method for extracting and separating a rare-earth element according to claim 1, further comprising: stripping the rare-earth elements which have been extracted into n-heptane with a nitric acid solution. ### Claim 7 (depends on 6) The method for extracting and separating a rare-earth element according to claim 6, wherein the nitric acid solution has a concentration of 0.04˜0.50 mol/L. ### Claim 8 A method for extracting and separating a rare-earth element, comprising: extracting the rare-earth element from an aqueous solution of rare-earth chloride into n-heptane, with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester trialkyl methyl ammonium or di-2-ethylhexyl phosphoric acid trialkyl methyl ammonium as an extractant, and n-heptane as a diluent by contacting the aqueous solution of rare-earth chloride with the extractant and the diluent to extract and separate the rare-earth element into n-heptane from the aqueous solution of rare-earth chloride. ### Claim 9 (depends on 8) The method for extracting and separating a rare-earth element according to claim 8, wherein the extraction temperature is 20˜50 ° C.; and/or wherein the aqueous solution of rare-earth chloride has a concentration of 7˜11×10−4 mol/L; and/or wherein after extracting the rare-earth element from the aqueous solution of rare-earth chloride into n-heptane, controlling the aqueous solution of rare-earth chloride to have a pH of 1˜5; and/or wherein the rare-earth element is selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. ### Claim 10 (depends on 8) The method for extracting and separating a rare-earth element according to claim 8, further comprising mixing a NaCl solution with a concentration of 0.2˜1.5 mol/L as a salting-out agent with the aqueous solution of rare-earth chloride. ### Claim 11 (depends on 10) The method for extracting and separating a rare-earth element according to claim 10, wherein the extracting the rare-earth element from the aqueous solution of rare-earth chloride into n-heptane further comprises: mixing a solution of a quaternary ammonium ionic liquid extractant in n-heptane, the salting-out agent and the aqueous solution of rare-earth chloride, and extracting the rare-earth element from the aqueous solution of rare-earth chloride into n-heptane; the quaternary ammonium ionic liquid extractant being the 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester trialkyl methyl ammonium or the di-2-ethylhexyl phosphoric acid trialkyl methyl ammonium. ### Claim 12 (depends on 11) The method for extracting and separating a rare-earth element according to claim 11, wherein the solution of the quaternary ammonium ionic liquid extractant in n-heptane has a concentration of 0.01˜0.08 mol/L. ### Claim 13 (depends on 8) The method for extracting and separating a rare-earth element according to claim 8, further comprising: stripping the rare-earth elements which have been extracted into n-heptane with a hydrochloric acid solution. ### Claim 14 (depends on 13) The method for extracting and separating a rare-earth element according to claim 13, wherein the hydrochloric acid solution has a concentration of 0.03˜0.20 mol/L. ### Claim 15 A method for extracting and separating a rare-earth element, comprising: extracting the rare-earth element from an aqueous solution of rare-earth sulfate into n-heptane, with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester trialkyl methyl ammonium as an extractant, and n-heptane as a diluent by contacting the aqueous solution of rare-earth sulfate with the extractant and the diluent to extract and separate the rare-earth element into n-heptane from the aqueous solution of rare-earth sulfate. ### Claim 16 (depends on 15) The method for extracting and separating a rare-earth element according to claim 15, wherein the extraction temperature is 25˜50 ° C.; and/or wherein the aqueous solution of rare-earth sulfate has a concentration of 7˜9×10−4 mol/L; and/or wherein after extracting the rare-earth element from the aqueous solution of rare-earth sulfate into n-heptane, controlling the aqueous solution of rare-earth sulfate to have a pH of 1˜7; and/or wherein the rare-earth element is selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y. ### Claim 17 (depends on 15) The method for extracting and separating a rare-earth element according to claim 15, further comprising mixing a Na2SO4 solution with a concentration of 0.1˜1.0 mol/L as a salting-out agent with the aqueous solution of rare-earth sulfate. ### Claim 18 (depends on 17) The method for extracting and separating a rare-earth element according to claim 17, wherein the extracting the rare-earth element from the aqueous solution of rare-earth sulfate into n-heptane further comprises: mixing a solution of a quaternary ammonium ionic liquid extractant in n-heptane, the salting-out agent and the aqueous solution of rare-earth sulfate, and extracting the rare-earth element from the aqueous solution of rare-earth sulfate into n-heptane; the quaternary ammonium ionic liquid extractant being the 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester trialkyl methyl ammonium. ### Claim 19 (depends on 18) The method for extracting and separating a rare-earth element according to claim 18, wherein the solution of the quaternary ammonium ionic liquid extractant in n-heptane has a concentration of 0.02˜0.08 mol/L. ### Claim 20 (depends on 15) The method for extracting and separating a rare-earth element according to claim 15, further comprising: stripping the rare-earth elements which have been extracted into n-heptane with a sulfuric acid solution. ### Claim 21 (depends on 20) The method for extracting and separating a rare-earth element according to claim 20, wherein the sulfuric acid solution has a concentration of 0.01˜0.1 mol/L.