Patent ID: 11905180
Assignee: TORAY INDUSTRIES, INC.
Field: Chemical engineering (Chemistry)
Classification: CPC B  C  H  Y | IPC B  C

Claim 11:
12. The method for recovering a rare metal salt according to claim 1, wherein
the concentration step comprises a concentration step of obtaining non-permeated water having a higher concentration of the monovalent rare metal than that of the permeated water in the separation step and permeated water having a lower concentration of the monovalent rare metal than that of the permeated water in the separation step, by using a reverse osmosis membrane satisfying the following condition (2),
condition (2):
a removal ratio of isopropyl alcohol is 95% or more and a removal ratio of boron ions is 75% or more when the reverse osmosis membrane is immersed in a sulfuric acid aqueous solution having a pH of 1 and a temperature of 25° C. for 24 hours, and then an aqueous solution having a pH of 6.5 and a temperature of 25° C. and comprising 30 mg/L boric acid, 100 mg/L isopropyl alcohol, and 30000 mg/L lithium chloride is allowed to pass through the reverse osmosis membrane under an operating pressure of 5.5 MPa.