Lithium Extraction Method, and Metal Recovery Method

Abstract

To provided a method for recovering lithium from a lithium ion battery using comparatively simple equipment and without using a cumbersome process. A lithium extraction method for extracting lithium from the positive electrode material of a lithium ion battery containing lithium and cobalt, the method being characterized in that the positive electrode material is immersed into an acidic solution at 50° C. or less, lithium ions are selectively leached into the acidic solution while inhibiting the leaching of cobalt ions, and the leaching of lithium ions is stopped while the amount of lithium contained in the positive electrode material is sufficient.

1 . A lithium extraction method extracting from a cathode material of a lithium ion battery, containing lithium and cobalt, the lithium extraction method comprising:
 a step of leaching lithium ion into an acidic solution by soaking the cathode material in the acidic solution at 50° C. or lower, and   a step of terminating the leaching of lithium ion when a lithium content of the cathode material is 30% or more of a lithium content of the cathode material before the step of leaching.   
     
     
         2 . The lithium extraction method according to  claim 1 , wherein the acidic solution comprises sulfuric acid. 
     
     
         3 . The lithium extraction method according to  claim 2 , wherein the acidic solution is concentrated sulfuric acid. 
     
     
         4 . The lithium extraction method according to  claim 1 , wherein the acidic solution comprises an oxidation-reduction control agent. 
     
     
         5 . The lithium extraction method according to  claim 4 , wherein the oxidation-reduction control agent is hydrogen peroxide. 
     
     
         6 . A metal recovery method comprising:
 a step of recovering lithium from the leached lithium ion-containing solution obtained by the lithium extraction method according to  claim 1 ; and   a step of recovering Co from the cathode material used in the lithium extraction method according to  claim 1 .   
     
     
         7 . The metal recovery method according to  claim 6 ,
 wherein the metal recovery method comprises a step of further separating the leached lithium ion-containing solution into a solution having a larger proportion of lithium ion and a solution having a larger proportion of Co ion; and   lithium is recovered from the solution having a larger proportion of lithium ion.