Precipitation–dissolution equilibrium of lithium sodium cryolite

A strong affinity is observed between fluorine and aluminum, which can both easily undergo sixth-level complexation to form \begin{document}${\mathrm{AlF}}_{{6}}^{{3-}} $\end{document}. Their coexistence with alkali metal ions (such as Li and Na) leads to the formation of a homogeneous solid solution, namely aluminum–sodium composite lithium salt, based on the stoichiometric ratio between the ions. The considerable affinity between fluorine–aluminum bonds and the insoluble nature of fluoroaluminate precipitation provide important guidance for the harmless treatment of fluorine-containing wastewater, aluminum removal from lithium battery positive electrode powder acid leaching solution, electrolytic aluminum smelting industry, and the geochemical and environmental chemical behavior research of aluminum and phosphorus in acidic fluorine-polluted soil. A current research hotspot focuses on the high-value recycling and reusing of iron and phosphorus components in waste lithium iron phosphate (LiFePO4) batteries d