Process and method for refining lithium carbonate starting from an impure lithium chloride solution
A method for refining lithium from a crude brine includes charging a crude brine into a feeder tank held at a temperature T 1 and containing a sufficient carbonate source to precipitate all carbonate-forming solids in the crude brine to form a precipitate mixture and a crystal free supernatant; pumping the crystal free supernatant from the feeder tank to a first crystallization reactor that is held at a temperature T 2 to crystallize a lithium carbonate salt out of the crystal free supernatant; wherein the temperature T 1 is lower than the temperature T 2 ; and controlling a flow rate to maintain a steady state concentration of the lithium carbonate salt in the solution phase of the crystallization reactor.
1. A method for refining lithium from a crude brine, comprising:
charging a crude brine into a feeder tank held at a temperature T 1 and containing a sufficient carbonate source to precipitate carbonate-forming solids in the crude brine to form a precipitate mixture and a crystal free supernatant; and
pumping the crystal free supernatant from the feeder tank to a first crystallization reactor that is held at a temperature T 2 to crystallize a lithium carbonate salt out of the crystal free supernatant;
wherein the temperature T 1 is lower than the temperature T 2 ;
controlling a flow rate of the crystal free supernatant from the feeder tank to the first crystallization reactor to maintain a steady state concentration of lithium carbonate in a solution phase of the crystallization reactor; and
pumping a solution phase in the first crystallization reactor into a second crystallization reactor that is held at a temperature T 3 ;
wherein the temperature T 3 is higher than the temperature T 2 .
2. The method of claim 1 , further comprising:
pumping a solution phase in the first crystallization reactor back into the feeder tank.
3. The method of claim 1 , wherein the first crystallization reactor is seeded with lithium carbonate crystal seeds.
4. The method of claim 1 , wherein the carbonate source is sodium carbonate, potassium carbonate, or carbon dioxide.
5. The method of claim 1 , further comprising:
continuing the method of pumping a solution phase from an “n” crystallization reactor to an “n+1” crystallization reactor wherein the “n+1” crystallization reactor is held at a temperature higher than the temperature of the “n” crystallization reactor;
wherein “n” is an integer greater than or equal to 2.
6. The method of claim 1 , wherein the flow rate of the crystal free supernatant from the feeder tank to the first crystallization reactor is sufficient to maintain a steady state concentration of dissolved lithium carbonate in the solution phase, such that the rate of crystallization is faster than the maximum flow rate employed.
7. The method of claim 1 , wherein the flow rate is adjusted to accommodate an addition rate of crystal free supernatant to crystallize between 50-250g Li 2 CO 3 per hour.