Integrated lithium production process
A lithium hydroxide production process integrating a lithium stripping stage with a lithium hydroxide production process performed in a two-compartment electrolysis cell.
1 . A method of producing an aqueous lithium-containing solution from a lithium-loaded organic medium, the method comprising:
(a) providing a two-compartment electrolysis cell having an anode, a cathode, and a membrane barrier disposed therebetween, said membrane barrier being permeable to lithium (Li + ) cations and to protons (H + );
(b) stripping the lithium-loaded organic medium by means of an aqueous stripping solution, to extract said lithium cations from the lithium-loaded organic medium into the aqueous stripping solution, producing an aqueous, lithium-containing intermediate solution along with a stripped organic medium;
(c) introducing said aqueous, lithium-containing intermediate solution into an anodic compartment of said two-compartment electrolysis cell, to form an anolyte;
(d) introducing an aqueous medium into a cathodic compartment of said two-compartment electrolysis cell to form a catholyte;
(e) operating said cell so as to:
(i) generate oxygen gas at said anode;
(ii) produce said protons (H + ) within said anolyte; and
(iii) generate hydrogen gas and hydroxide (OH − ) at said cathode;
and such that a portion of said lithium cations and a portion of said protons traverse said membrane barrier, whereby said protons react with said hydroxide to produce water in said catholyte;
(f) removing an aqueous product stream from said cathodic compartment, said product stream containing dissolved lithium hydroxide values; and
(g) recycling a discharge stream containing said anolyte, from said anodic compartment, for use in said stripping of the lithium-loaded organic medium;
the method further comprising:
(h) between steps (b) and (c), separating said lithium-containing aqueous intermediate solution from said stripped organic medium;
(i) returning said stripped organic medium to an extraction stage; and
(j) mixing an aqueous lithium-containing feed solution with said stripped organic medium, in said extraction stage, to produce said lithium-loaded organic medium;
wherein said discharge stream contains said lithium cations and said protons (H + ) in a molar ratio within a range of 100:1 to 1:1 of Li + to H + .
2 . The method of claim 1 , wherein the method is a continuous method.
3 . A method of producing an aqueous lithium-containing solution from a lithium-loaded organic medium, the method comprising:
(a) providing a two-compartment electrolysis cell having an anode, a cathode, and a membrane barrier disposed therebetween, said membrane barrier being permeable to lithium (Li + ) cations and to protons (H + );
(b) stripping the lithium-loaded organic medium by means of an aqueous stripping solution, to extract said lithium cations from the lithium-loaded organic medium into the aqueous stripping solution, producing an aqueous, lithium-containing intermediate solution along with a stripped organic medium;
(c) introducing said aqueous, lithium-containing intermediate solution into an anodic compartment of said two-compartment electrolysis cell, to form an anolyte;
(d) introducing an aqueous medium into a cathodic compartment of said two-compartment electrolysis cell to form a catholyte;
(e) operating said cell so as to:
(i) generate oxygen gas at said anode;
(ii) produce said protons (H + ) within said anolyte; and
(iii) generate hydrogen gas and hydroxide (OH − ) at said cathode;
and such that a portion of said lithium cations and a portion of said protons traverse said membrane barrier, whereby said protons react with said hydroxide to produce water in said catholyte;
(f) removing an aqueous product stream from said cathodic compartment, said product stream containing dissolved lithium hydroxide values; and
(g) recycling a discharge stream containing said anolyte, from said anodic compartment, for use in said stripping of the lithium-loaded organic medium;
the method further comprising:
(h) between steps (b) and (c), separating said lithium-containing aqueous intermediate solution from said stripped organic medium;
(i) returning said stripped organic medium to an extraction stage; and
(j) mixing an aqueous lithium-containing feed solution with said stripped organic medium, in said extraction stage, to produce said lithium-loaded organic medium;
wherein, within said lithium-containing intermediate solution, said lithium cations are a predominant cation;
wherein, within said lithium-containing intermediate solution, sulfate anions are a predominant anion; and
wherein said discharge stream contains said lithium cations (Li + ) and said protons (H + ) in a molar ratio within a range of 40:1 to 1:2.
4 . The method of claim 3 , wherein the method is a continuous method.
5 . The method of claim 3 , wherein said molar ratio is within a range of 10:1 to 1:2.
6 . The method of claim 5 , wherein the method is a continuous method.
7 . The method of claim 5 , wherein said molar ratio is at least 1:1.
8 . The method of claim 7 , wherein the method is a continuous method.