The invention discloses a method for extracting
lithium from
magnesium-removal bittern and preparing battery-grade
lithium carbonate. The method uses a reaction-separating
coupling technology for separating, extracting a
lithium resource from
magnesium-removal bittern and generating the battery-grade
lithium carbonate, a technology comprises the following steps:
aluminium salt is added in
high sodium bittern after
magnesium removal, and steps of
nucleation and
crystallization are carried out with alkali lye in a
colloid grinder to obtain a lithium-
aluminium composite
metal hydroxide solid, lithium ions are introduced into a
solid phase, the sodions stay in a solution, so that lithium ions and sodions are effectively separated. The lithium-
aluminium composite
metal hydroxide is dissolved by acid to obtain a solution containing lithium ions and aluminum ions, then lithium and aluminium are separated by an
electrodialysis apparatus, the separated solution containing aluminium can be recycled, a lithium-rich solution is subjected to a
precipitation reaction, and the battery-grade
lithium carbonate is obtained. A reaction-separation
coupling technology is used, while lithium and
sodium are separated, the battery-grade
lithium carbonate is prepared, so that high efficiency and high value utilization of the
salt lake lithium resource can be realized.