The University of Padua (UNIPD) recently completed a new milestone for CRM-geothermal relating to the development of membranes and extraction fluids.
The related project task focused on the development of ion-exchange polymers formed into beads able to carry out the separation of Li+ from the other cations found in a brine (e.g., Na+, K+, Mg2+, Ca2+). In a later step, such ion-exchange polymers will be formed into membranes to carry out such separation in conjunction of an “extracting fluid”.
At the present stage, lithium separation from the brine is carried out by a multi-step process. The latter consists in the following elementary steps:
(i) selective binding of the brine cations into the beads;
(ii) concentration of the cations and modulation of the counter-anions; and
(iii) final separation of lithium by means of high-efficiency solvent extraction.
The beads used for selective lithium separation consist of a very inexpensive ion-exchange aromatic polymer, whose production is straightforward and whose physicochemical properties are easy to modulate to tailor selectivity.
UNIPD will mainly focus on the extraction of lithium from the brines, strontium extraction being considered for a later stage. The lithium extraction will be first tested on synthetic brines and later implemented on natural brines.
