Regeneration of Aluminum Fluoride From Pure Bath

Commercial aluminum fluorideAluminum fluoride production is currently dependent on fluorspar, listed by the USGS and EU as a critical mineral, as a feedstock. Surplus pure bathPure bath, continuously generated during aluminum electrolysisAluminum electrolysis from a reaction between the sodium oxide present in aluminaAlumina and the molten cryolitic bath, presents an option as an alternative fluoride source for the production of aluminum fluorideAluminum fluoride. Solidified cryolitic bath is composed of numerous different fluoride phases including cryolite, chiolite, calcium cryolite, and neighborite. An elevated temperature, solid-state reaction between aluminumAluminum sulfate and solidified cryolitic bath is capable of converting the fluoride components of the bath to aluminum fluorideAluminum fluoride and sodium, calcium, and magnesiumMagnesium sulfates. The sulfates can then be separated from the aluminum fluorideAluminum fluoride fraction through a sequence of aqueous washes. Due to the low aqueous solubilitySolubility of aluminum fluorideAluminum fluoride, this results in a solid fraction with purity comparable to commercially available smelter grade aluminum fluorideAluminum fluoride.