Process for the purification of a solution of lithium salts contaminated by metallic cations and use of this process in the production of zeolites exchanged with lithium

Process for the purification of a solution of lithium salts contaminated by metallic cations other than lithium, comprising the steps of:

• (i) passing a solution to be purified through an exchange zone packed with a zeolite adapted to exchange Li.sup.+ cations with said metallic cations other than lithium, said zeolite being initially loaded with more than 95% Li.sup.+ cations and having a better affinity for said metallic cations other than lithium than for the Li.sup.+ cations, so as to fix all the contaminating metallic cations on said zeolite by displacement of Li.sup.+ cations, whereby the solution of lithium salts recovered at the outlet of said exchange zone is stripped of said contaminating metallic cations;
• and
• (ii) regenerating said zeolite by replacing the contaminating metallic cations fixed on said zeolite with Li.sup.+ cations, by:
• a) contacting the zeolite with a solution containing NH.sub.4.sup.+ cations, whereby all of the metallic cations fixed on said zeolite are displaced by NH.sub.4.sup.+ cations;
• b) heating the zeolite from previous step a) to a temperature between 150 and 350.degree. C., whereby said zeolite is converted to its acid form giving off ammonia;
• and
• c) contacting the zeolite in its acid form, resulting from step b) above, with an aqueous solution of lithium hydroxide, whereby said zeolite is thus regenerated.