RECOVERY OF LITHIUM CARBONATE - Patent 3857920 Lithium carbonate is recovered from an aqueous slurry by first treating the sparingly soluble lithium carbonate with carbon dioxide to convert it to the much more soluble lithium bicarbonate. The bicarbonate solution is next separated from insoluble material present and then decarbonated to precipitate lithium carbonate, which is then recovered. The present process is of particular utility for the recovery of lithium carbonate from fly ash- and coke-containing filter cakes resulting from a process for the treatment of flue gas to remove sulfur dioxide present therein by absorption of the sulfur dioxide in a molten alkali metal carbonate mixture.The molten carbonate process for the removal of sulfur oxides from power-plant flue gases is of particular commercial interest and is shown in U.S. Pat. Nos. 3,438,722, 3,438,727, and 3,438,734. In its preferred aspects, the process broadly consists of scrubbing the sulfur oxide-containing flue gas with a molten mixture of the carbonates of lithium, potassium, and sodium at a minimum temperature of about 400°C. The resultant melt, containing up to 40% alkali metal sulfite salts, is regenerated by heating it to about 800°C, at which temperature the sulfites, as well as sulfates formed by disproportionation of the sulfites, can be reduced to sulfides by treatment with carbon. The alkali-metal sulfides in the melt are converted back to carbonates with the concurrent formation of hydrogen sulfide by reaction of the sulfides at about 450°-500°C with carbon dioxide and steam. For typical power-plant operating conditions, burning a coal containing about 3% sulfur and 10% ash, the resultant flue gas will contain about 0.2 vol.% sulfur oxides and from about 80 to 100% of the initially present coal ash in the form of finely divided fly ash. The presence of the fly ash in the flue gas raises several technological and economic problems in the removal of the sulfur oxides.
SOLUBILITY OF LITHIUM CARBONATE
lithium carbonate tablets
