PROCESS FOR OBTAINING HIGH PURITY LITHIUM FROM AN AQUEOUS LITHIUM SALT-CONTAINING SOLUTION
There is disclosed a process for selectively purifying a lithium chloride product stream from an aqueous lithium salt-containing solution, the process comprising the steps of: introducing the aqueous lithium salt-containing solution to one or more columns filled with a lithium selective sorbent; flowing the aqueous lithium salt-containing solution through the one or more columns to adsorb lithium chloride from the aqueous lithium salt-containing solution onto a sorbent and form a sorbent with a greater lithium chloride content than the sorbent prior to introducing the solution; flowing a desorbent fluid once-through the at least one or more columns to desorb lithium chloride from the sorbent into an eluate stream, wherein the desorbent fluid is flowed in a co-current direction with respect to the direction of flow of the aqueous lithium salt-containing solution, and recovering a lithium chloride product stream from the eluate stream, wherein the eluate stream has a Li:TDS ratio of 0.08 or more.
1 . A process for selectively purifying a lithium chloride product stream from an aqueous lithium salt-containing solution, the process comprising the steps of:
a. introducing the aqueous lithium salt-containing solution to one or more columns filled with a lithium selective sorbent;
b. flowing the aqueous lithium salt-containing solution through the one or more columns to adsorb lithium chloride from the aqueous lithium salt-containing solution onto a sorbent and form a sorbent with a greater lithium chloride content than the sorbent prior to introducing the solution;
c. flowing a desorbent fluid once-through the at least one or more columns to desorb lithium chloride from the sorbent into an eluate stream, wherein the desorbent fluid is flowed in a co-current direction with respect to the direction of flow of the aqueous lithium salt-containing solution, and
d. recovering a lithium chloride product stream from the eluate stream, wherein the eluate stream has a Li:TDS ratio of 0.08 or more.
2 . The process of claim 1 , wherein the aqueous lithium salt-containing solution is a naturally-occurring solution, a synthetic solution or a mixture thereof.
3 . The process of claim 1 , wherein the aqueous lithium salt-containing solution is subject to a pre-treatment step of mechanical pre-treatment, temperature adjustment, chemical pre-treatment or pH adjustment.
4 . The process of claim 1 , wherein the lithium selective sorbent is an ion sieve sorbent, a lithium-metal oxide sorbent, a mixed metal oxide sorbent, an alkali or alkali earth metal/alumina matrix, transition metal/alumina matrix or a molecular sieve sorbent.
5 . The process of claim 1 , wherein the one or more columns are packed-bed columns.
6 . The process of claim 1 , wherein the desorbent fluid is water, pH adjusted water or a polar organic solvent.
7 . The process of claim 1 , wherein the desorbent fluid is derived from a process operation or is a recycled process stream.
8 . The process of claim 1 , further comprising a step between step b) and step c) of addition of a conductive metal salt solution.
9 . The process of claim 8 , wherein the conductive metal salt solution is an alkali metal salt solution.
10 . The process of claim 9 , wherein the alkali metal salt solution is any mono-valent water-soluble salt.
11 . The process of claim 1 , further comprising a step e) of concentrating the lithium chloride product stream using reverse osmosis, solvent extraction, evaporation, ion exchange or a combination.
12 . The process of claim 11 , wherein the reverse osmosis is any of seawater reverse osmosis, osmotically assisted reverse osmosis or ultra-high pressure reverse osmosis.
13 . The process of claim 11 , further comprising repeating steps a) to e).
14 . The process of claim 1 , wherein the step of flowing the aqueous lithium salt-containing solution through the one or more columns at a variable velocity is performed within the range of 4 to 800 LPM/M 2 column cross sectional area.
15 . The process of claim 14 , wherein the range is 80 to 400 LPM/M 2 column cross sectional area.
16 . The process claim 1 , wherein the flowing of the desorbent fluid in step c) is carried out at a variable velocity within the range of 4 to 800 LPM/M 2 column cross sectional area.
17 . The process of claim 16 , wherein the range is 80 to 400 LPM/M 2 column cross sectional area.