Production of high purity lithium compounds directly form lithium containing brines

Abstract

A process for reducing the amount of magnesium in a lithium-containing brine by adding an aqueous solution of KCl to the brine to precipitate at least some of the magnesium as carnallite salt is disclosed. Lithium salts prepared using this magnesium removal process are also disclosed.

1 - 8 . (canceled) 
     
     
         9 . Lithium carbonate prepared by a continuous process for directly preparing high purity lithium carbonate from lithium containing brines comprising: preparing a brine containing about 6.0 wt % lithium and further containing other ions naturally occurring in brines; adding a solution of KCl to precipitate magnesium as carnallite; extracting to remove boron; adding mother liquor containing carbonate from a prior precipitation step to precipitate magnesium as magnesium carbonate; adding a solution of CaO and sodium carbonate to remove calcium and residual magnesium; precipitating lithium carbonate from the purified brine by adding soda ash solution; filtering the resultant solution to obtain solid lithium carbonate; preparing an aqueous slurry of the lithium carbonate in a reactor equipped with an inlet for introducing carbon dioxide gas and introducing carbon dioxide gas through the inlet into said aqueous slurry to form an aqueous lithium bicarbonate solution, the reactor being at a temperature in the range from −10 to +40° C.; passing said aqueous lithium bicarbonate solution through a filter to clarify the solution and optionally an ion exchange column for further calcium and magnesium removal; introducing said filtered lithium bicarbonate solution into a second reactor and adjusting the temperature of the solution to from 60 to 100° C. to precipitate ultra-pure lithium carbonate with sodium less than 0.0002 wt %, calcium less than 0.00007 wt % and magnesium less than 0.00001 wt %. 
     
     
         10 . The lithium carbonate of  claim 9 , wherein the lithium bicarbonate is only passed through a filter and proceeds to the second reactor at 60 to 100° C. to precipitate low sodium lithium carbonate with a sodium content of less than 0.0002 wt %. 
     
     
         11 . The lithium carbonate of  claim 9 , wherein the temperature in the lithium bicarbonate formation reactor is from −5 to +35° C., and the temperature of the reactor for precipitating high purity lithium carbonate is from 70 to 95° C. 
     
     
         12 . The lithium carbonate of  claim 9 , wherein the lithium bicarbonate solution is maintained at greater than or equal to atmospheric pressure when below ambient temperature. 
     
     
         13 . The lithium carbonate of  claim 9 , comprising less than 20 ppm sodium as an impurity. 
     
     
         14 . The lithium carbonate of  claim 9 , comprising less than 2 ppm sodium as an impurity. 
     
     
         15 . Purified lithium carbonate comprising: greater than 99.4 wt. % L 2 CO 3 ; less than 0.0007 wt. % Mg; less than 0.0010 wt. % Na; less than 0.00025 wt. % K; less than 0.0120 wt. % Ca; less than 0.0001 wt. % B; less than 0.0002 wt. % Al; less than 0.0001 wt. % As; less than 0.0001 wt. % Fe; less than 0.0010 wt. % Si; less than 0.00005 wt. % Zn; less than 0.037 wt. % SO 4 ; and less than 0.005 wt. % Cl, prepared by a continuous process for directly preparing high purity lithium carbonate from lithium containing brines comprising: preparing a brine containing about 6.0 wt % lithium and further containing other ions naturally occurring in brines; adding a solution of KCl to precipitate magnesium as carnallite; extracting to remove boron; adding mother liquor containing carbonate from a prior precipitation step and soda ash solution to precipitate magnesium carbonate; filtering to remove magnesium carbonate; adding CaO and soda ash to remove magnesium and calcium and to yield a purified lithium containing brine; adding soda ash to said purified brine to precipitate lithium carbonate; filtering the solution to recover the precipitated lithium carbonate, preparing an aqueous lithium carbonate slurry in a reactor where such reactor is equipped with an inlet for introducing carbon dioxide gas and introducing carbon dioxide gas through the inlet into the lithium carbonate slurry to produce an aqueous lithium bicarbonate solution, wherein the reactor is at a temperature in the range of −10 to +40° C.; passing the aqueous lithium bicarbonate solution through a clarifying filter and optionally an ion exchange column for further calcium and magnesium removal; introducing the filtered solution into a second reactor and adjusting the temperature of the solution to from 60 to 100° C. to precipitate the ultra-pure lithium carbonate; and filtering, washing, and drying the ultra-pure lithium carbonate. 
     
     
         16 . Lithium carbonate comprising: greater than 99.995 wt. % Li 2 CO 3 ; less than 0.00001 wt. % Mg; less than 0.0002 wt. % Na; less than 0.00015 wt. % K; less than 0.00007 wt. % Ca; less than 0.0001 wt. % B; less than 0.0002 wt. % Al; less than 0.0001 wt. % As; less than 0.0001 wt. % Fe; less than 0.00011 wt. % Si; less than 0.000014 wt. % Zn; less than 0.0030 wt. % SO 4 ; and less than 0.005 wt. % Cl prepared by a continuous process for directly preparing high purity lithium carbonate from lithium containing brines comprising: preparing a brine containing about 6.0 wt % lithium and further containing other ions naturally occurring in brines; adding a solution of KCl to precipitate magnesium as carnallite; extracting to remove boron; adding mother liquor containing carbonate from a prior precipitation step and soda ash solution to precipitate magnesium carbonate; filtering to remove magnesium carbonate; adding CaO and soda ash to remove magnesium and calcium and to yield a purified lithium containing brine; adding soda ash to said purified brine to precipitate lithium carbonate; filtering the solution to recover the precipitated lithium carbonate, preparing an aqueous lithium carbonate slurry in a reactor where such reactor is equipped with an inlet for introducing carbon dioxide gas and introducing carbon dioxide gas through the inlet into the lithium carbonate slurry to produce an aqueous lithium bicarbonate solution, wherein the reactor is at a temperature in the range of −10 to +40° C.; passing the aqueous lithium bicarbonate solution through a clarifying filter and optionally an ion exchange column for further calcium and magnesium removal; introducing the filtered solution into a second reactor and adjusting the temperature of the solution to from 60 to 100° C. to precipitate the ultra-pure lithium carbonate. 
     
     
         17 . Lithium chloride produced by a process comprising:
 preparing a brine containing about 6.0 wt % lithium, and further containing magnesium, calcium, and sulfate;   adding a solution of KCl to precipitate magnesium as carnallite;   extracting to remove boron;   adding CaO or Ca(OH) 2  to the brine to coprecipitate magnesium and calcium;   cooling to remove sodium chloride by precipitation;   adding a barium salt to remove sulfate by precipitating barium sulfate;   adding an oxalate source to remove remaining calcium by precipitating calcium oxalate;   adjusting the final pH of the brine to about 7.0;   concentrating to precipitate lithium chloride; and   filtering, optionally washing, and drying the lithium chloride.   
     
     
         18 . The lithium chloride of  claim 17 , wherein the barium salt is barium chloride. 
     
     
         19 . The lithium chloride of  claim 17 , wherein the oxalate source is oxalic acid. 
     
     
         20 . The lithium chloride of  claim 17 , wherein the oxalate source is lithium oxalate. 
     
     
         21 . Lithium carbonate of  claim 9 , comprising a reactor using absorption columns to facilitate absorption of carbon dioxide. 
     
     
         22 . Lithium carbonate of  claim 9 , wherein the absorption column is a sieve tray. 
     
     
         23 . Lithium carbonate of  claim 9 , wherein the absorption column is a Schiebel column. 
     
     
         24 . Lithium carbonate of  claim 10 , comprising a reactor having absorption columns to facilitate absorption of carbon dioxide. 
     
     
         25 . Lithium carbonate of  claim 10 , wherein the absorption column is a sieve tray column. 
     
     
         26 . The lithium carbonate of  claim 10 , wherein the absorption column is a Schiebel column. 
     
     
         27 . Lithium carbonate of  claim 11 , comprising a reactor that has absorption columns to facilitate absorption of carbon dioxide. 
     
     
         28 - 44 . (canceled)