Method for recovering lithium and method for producing lithium carbonate

A method for producing lithium carbonate from slag containing at least aluminum and lithium, the slag being provided by melting a lithium-ion secondary battery to be disposed of to obtain molten metal containing valuable metal and molten slag containing at least aluminum and lithium and separating the slag containing at least aluminum and lithium from the molten metal containing valuable metal, wherein a condition of the melting of the lithium-ion secondary battery is adjusted such that the slag has an aluminum to lithium mass ratio, Al/Li, of 6 or less,

• the method comprising:
• contacting the slag with an aqueous liquid to obtain a leachate containing lithium leached from the slag,
• contacting the leachate with a basic substance to cause an unwanted metal contained in the leachate to precipitate in the form of a slightly soluble substance, followed by solid-liquid separation to obtain a purified solution having lithium dissolved therein, and
• contacting the purified solution with a carbonate or carbon dioxide to precipitate a carbonate of lithium in the solution.