(19) TZZ ¥¥_T (11) EP 2 536 663 B1 (12) EUROPEAN PATENT SPECIFICATION (45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C01D 15/08 (2006.01) C01B 25/10 (2006.01) 26.03.2014 Bulletin 2014/13 C01D 15/04 (2006.01) C01D 15/02 (2006.01) C01B 25/45 (2006.01) C01B 25/30 (2006.01) (2006.01) (2006.01) (21) Application number: 11707259.5 C07F 1/02 C01B 11/18 C01B 35/06 (2006.01) C07F 5/02 (2006.01) C25B 1/02 (2006.01) C25B 3/00 (2006.01) (22) Date of filing: 17.02.2011 (86) International application number: PCT/US2011/025256 (87) International publication number: WO 2011/103298 (25.08.2011 Gazette 2011/34) (54) PROCESS FOR PREPARING HIGHLY PURE LITHIUM CARBONATE VERFAHREN FÜR DIE ZUBEREITUNG VON HOCHREINEM LITHIUMCARBONAT PROCÉDÉ POUR LA PRÉPARATION DE CARBONATE DE LITHIUM DE HAUTE PURETÉ (84) Designated Contracting States: (74) Representative: Barton, Matthew Thomas AL AT BE BG CH CY CZ DE DK EE ES FI FR GB Forresters GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO Skygarden PL PT RO RS SE SI SK SM TR Erika-Mann-Strasse 11 80636 München (DE) (30) Priority: 17.02.2010 US 305213 P (56) References cited: (43) Date of publication of application: WO-A1-99/29624 DE-A1- 19 809 420 26.12.2012 Bulletin 2012/52 GB-A- 2 190 668 US-A1- 2006 115 396 (73) Proprietor: Simbol , Inc. • DATABASE WPI Week 200512 Thomson Pleasanton CA 94566 (US) Scientific, London, GB; AN 2005-109280 XP002666413, & RU 2 243 157 C2 (NOVOS CHEM (72) Inventors: CONCENTRATES STOCK CO) 27 December 2004 • HARRISON, Stephen (2004-12-27) Benicia, CA (US) • BLANCHET, Robert Palm Desert, CA (CA) Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 2 536 663 B1 Printed by Jouve, 75001 PARIS (FR) EP 2 536 663 B1 Description BACKGROUND OF THE INVENTION 5 Field of the Invention [0001] The invention generally relates to the field of selectively preparing highly pure lithium carbonate. Description of the Related Art 10 [0002] Lithium carbonate (Li 2CO3) is typically produced commercially from two sources: (1) the extraction from pegm- atite mineral sources such as spodumene, lithiophyllite, or lepidolite, which can be obtained through traditional mining; and (2) extraction from lithium-containing brines, such as those found in the Salar de Atacama in Chile, Silver Peak Nevada, Salar de Uyuni in Bolivia, or the Salar de Hombre Muerte in Argentina. There are alternative brine sources, 15 such as, geothermal, oilfield, Smackover, and relict hydrothermal brines. These brines, however, have not previously been commercially exploited. [0003] There are a number of commercial applications for lithium carbonate including: use as an additive in aluminum smelting (molten salt electrolysis); enamels and glasses; to control manic depression (when used in its purer forms); and in the production of electronic grade crystals of lithium niobate, tantalite and fluoride. High purity lithium carbonate 20 is required for the fabrication of several materials in lithium ion batteries, such as, the cathode materials and electrolyte salts, and also in more avant-garde secondary batteries which require highly pure lithium metal. [0004] In the case of lithium ion batteries, purified lithium carbonate may be required for the fabrication of the cathode, as well as in the active materials for cathodes such as, and without limitation, lithium cobalt oxide, lithium manganese oxide or lithium iron phosphate, as well as, mixed metal oxides, such as, lithium cobalt nickel manganese oxide. 25 [0005] Several processes currently exist for the removal of lithium from lithium chloride-rich brines or other lithium containing liquids, however, none of the currently employed methods are suitable for the production of lithium carbonate containing low levels of magnesium and calcium, thus limiting the ability of the lithium carbonate to be used as a battery grade lithium product without first undergoing further purification. Methods for extracting lithium carbonate from mineral sources, such as spodumene or lithium aluminum s ilicate ore (LiAlSi2O6), similarly produce materials that lack sufficient 30 purity for use in batteries. The purity of the resulting material using these processes is not sufficiently pure for battery grade lithium metal production, or for pharmaceutical grade lithium carbonate. Therefore, there is a need for a method for extracting lithium from lithium-containing brines and to produce lithium salts such as chloride and carbonate of sufficient purity to produce high-purity lithium metal. [0006] US 2006/0115396 discloses methods and apparatus for the production of low sodium lithium carbonate and 35 lithium chloride from a brine concentrated to about 6.0 wt % lithium. [0007] WO 99/29624 discloses processes for preparing high purity lithium carbonate which can be used in pharma- ceutical applications, electronic grade crystals of lithium or to prepare battery-grade lithium metal. [0008] DE 198 09 420 A1 discloses a method for producing a high purity lithium salt starting from lithium carbonate. [0009] RU 2 243 157 C2 discloses a method for preparing high purity lithium carbonate comprising preparing lithium 40 bicarbonate through reaction of lithium carbonate aqueous solution with carbon dioxide. [0010] GB 2 190 668 A discloses a process for removing boron from lithium carbonate. SUMMARY OF THE INVENTION 45 [0011] According to the present invention there is provided a method of producing high purity lithium carbonate, comprising the steps of: reacting a first aqueous solution comprising a technical grade Li 2CO3 with CO2 to form a second aqueous solution comprising dissolved LiHCO3; 50 separating unreacted CO2 and insoluble compounds from the second aqueous solution using a gas-iquid-solid separator to produce a third aqueous solution, supplying the third aqueous solution to a reverse osmosis apparatus to concentrate the Li 2CO3, wherein the reverse osmosis apparatus is operable to remove CO2 from the solution and cause Li2CO3 to precipitate; removing dissolved impurities from the third aqueous solution by contacting the third aqueous solution with an ion 55 selective medium to produce a fourth aqueous solution; and precipitating Li2CO3 from the fourth aqueous solution, wherein the Li 2CO3 has a purity of at least about 99.99%. [0012] Preferably, the insoluble compounds separated from the second aqueous solution are recycled to the first 2 EP 2 536 663 B1 aqueous solution. [0013] Advantageously, the method further comprises the step of preheating the third aqueous solution to a temperature of about 50°C before precipitating Li2CO3. 5 BRIEF DESCRIPTION OF THE DRAWINGS [0014] The characteristic novel features of the invention are set forth in the appended claims. So that the manner in which the features, advantages and objects of the invention, as well as others that will become apparent, may be understood in more detail, more particular description of the invention briefly summarized above may be had by reference 10 to the embodiment thereof which is illustrated in the appended drawings, which form a part of this specification. Note, however, that the drawings illustrate only an embodiment of the invention and are therefore not to be considered limiting of the invention’s scope as it may apply to other equally effective embodiments. FIG. 1 is a schematic illustration of one embodiment of the present invention. 15 FIG. 2 is a schematic illustration of one embodiment of the present invention. FIG. 3 is a cross-section of an exemplary reactor for the production of lithium bicarbonate. 20 FIG. 4 is a schematic illustration a method for resin regeneration. FIG. 5 is a schematic illustration of a method of regenerating the cartridge. FIG. 6 is a graph showing the variation in lithium hydroxide concentration during four experimental runs. 25 FIG. 7 is graph showing cell voltage during operation of electrolysis cell to convert LiCl to LiOH. FIG. 8 is a graph showing the reduction in current efficiency observed at different LiOH outlet concentrations. 30 FIG. 9 is a graph showing energy consumption for production of LiOH at various outlet concentrations of LiOH. FIG. 10 is a graph illustrating the pH of the LiOH solution more or less remains constant until the entire lithium hydroxide gets converted into lithium carbonate. The sudden drop in pH is associated with the formation of lithium bicarbonate and completion of carbonation reaction. 35 DETAILED DESCRIPTION [0015] DEFINITIONS. As used herein the following terms shall have the following meanings: [0016] The term "high purity lithium" or "highly pure lithium" means lithium in excess of 99.9% purity. 40 [0017] The term "ultra high purity lithium" means lithium in excess of 99.999% purity. [0018] As used herein, the term "a total lithium carbonate concentration" includes both dissolved lithium carbonate (Li2CO3) and lithium bicarbonate (LiHCO3). [0019] As used herein, the term "weak liquor" means the filtrate solution from the lithium carbonate recovery, which has a total lithium carbonate concentration between about 0.5 wt % and about 0.15 wt %, depending on operating mode 45 (heating, cooling, and flow rate), operating conditions, and system design parameters. [0020] As used herein, the term "strong liquor" means the solution from carbonation reactor having a typical total lithium carbonate concentration normally lying between about 4.0 and 5.0% by weight, typically about 4.4% by weight %, depending on operating mode (for example, heating, cooling, flow rate), operating conditions, and system design parameters.