GB834121A - Improvements in or relating to the separation of lithium compounds from other compounds - Google Patents

Abstract

A relatively insoluble salt of lithium such as the borate, carbonate, fluoride or phosphate is precipitated from a solution containing one or more other metallic compounds in the presence of an organic substance forming soluble complex compounds with said other metal or metals, at a pH greater than 7. Suitable complexing agents are the alkali metal salts of ethylenediaminetetra-acetic acid and nitrilotriacetic acid, polymethylenediaminetetra-acetic acids and derivatives thereof, diaminocyclohexane-N : N1-tetraacetic acid and iminodiacetic acids (e.g. carboxyliminodiacetic acid, methyliminodiacetic acid, aminomalonicdiacetic acid, uramildiacetic acid, aniline diacetic acid and sulphonated and carboxylic derivatives of the latter compound, and N-g : g -dimethylbutyliminodiacetic acid). The complexing agent is preferably used in amounts of 120-300% of theoretical. In the example the precipitation mixture is heated to the boiling-point. After precipitation and removal of the precipitate, the mother liquor may be concentrated and recycled; a fraction of the recycle solution may be periodically withdrawn and the complexing agent recovered for reuse. In the case of the alkali metal salts of acids such as ethylenediaminetetra-acetic acid and nitrilotriacetic acid, the complexing agent may be precipitated and recovered from the mother liquor by addition of a strong acid.ALSO:A relatively insoluble salt of lithium such as an oxalate or stearate is precipitated from a solution containing one or more other metallic compounds in the presence of an organic substance forming soluble complex compounds with said other metal or metals, at a pH greater than 7. Suitable complexing agents are the alkali metal salts of ethylenediaminetetraacetic acid and nitrilotriacetic acid, polymethylenediaminetetra-acetic acids and derivatives thereof, diaminocyclohexane-N : N1-tetraacetic acid and iminodiacetic acids (e.g. carboxyliminodiacetic acid, methyliminodiacetic acid, aminomalonic - diacetic acid, uramildiacetic acid, aniline-diacetic acid and sulphonated derivatives of the latter compound, and N-g : g -dimethylbutylimino-diacetic acid). The complexing agent is preferably used in amounts of 120-300% of the theoretical quantity. The method is applicable to the recovery of lithium from its ores containing Al, Fe, Ca and other impurities (see Group III).