Process for producing metallic lithium
Provided is a safe and efficient method for producing lithium metal which facilitates efficient production of anhydrous lithium chloride without corrosion of the system materials by chlorine gas or molten lithium carbonate, and which allows production of lithium metal by molten salt electrolysis of the produced anhydrous lithium chloride as a raw material. The method includes the steps of (A) contacting and reacting lithium carbonate and chlorine gas in a dry process to produce anhydrous lithium chloride, and (B) subjecting the raw material for electrolysis containing the anhydrous lithium chloride to molten salt electrolysis under such conditions as to produce lithium metal, wherein the chlorine gas generated by the molten salt electrolysis in step (B) is used as the chlorine gas in step (A) to continuously perform steps (A) and (B).
1. A method for producing lithium metal comprising the steps of:
(A) contacting and reacting solid lithium carbonate and chlorine gas in a counterflow manner without a solvent in a dry process to produce anhydrous lithium chloride; and
(B) subjecting a raw material for electrolysis comprising said anhydrous lithium chloride obtained from step (A) to molten salt electrolysis in an electrolytic cell under such conditions as to produce lithium metal,
wherein said step (A) is performed outside said electrolytic cell,
wherein chlorine gas generated by said molten salt electrolysis in step (B) is recycled as said chlorine gas in step (A) performed outside said electrolytic cell to continuously perform steps (A) and (B),
wherein said lithium carbonate is in the form of powder or granule prepared by granulating powder, and
wherein said contacting and reacting in step (A) are carried out under stirring.
2. The method according to claim 1 , wherein said contacting and reacting in step (A) are carried out at a temperature of not lower than 350° C. and lower than 506° C.
3. The method according to claim 1 , wherein D90 (particle size at which cumulative volume fraction is 90%) of said lithium carbonate in powder form is not more than 0.70 mm.
4. The method according to claim 1 , wherein particle size distribution of said lithium carbonate in granular form is in the range of 0.1 to 5 mm.
5. The method according to claim 1 , wherein said lithium carbonate has a moisture content of not higher than 1 mass %.
6. The method according to claim 2 , wherein said lithium carbonate has a moisture content of not higher than 1 mass %.
7. The method according to claim 3 , wherein said lithium carbonate has a moisture content of not higher than 1 mass %.
8. The method according to claim 4 , wherein said lithium carbonate has a moisture content of not higher than 1 mass %.