Fusion Extraction of Base Metals (Al, Cr, Fe, Ti and V) Using Ammonium Phosphate Salt as Flux

The fusion method of using ammonium phosphate salt as flux was assessed for its ability to precipitate metaphosphate compounds containing trivalent ions M3+ = Al, Cr, Fe, Ti, and V as M(PO3)3 in inorganic salts and a certified reference material (CRM) mineral ore sample. Fusion analysis using mixtures of inorganic salts containing AlCl3, CrCl3, FeCl3, and VCl3 showed variable amounts of precipitates isolated as metaphosphate compounds in the order of iron (12%) < vanadium (13%) < chromium (30%) < (44%) aluminum. However, an analysis of the CRM (AMIS 0368) where magnetite (Fe3+/Fe2+) and ilmenite (Ti4+) are the dominant phases, showed that the obtained precipitates were in the order of chromium (less than 0.1%) < vanadium (1%) < aluminum (2%) < titanium (9%) < iron (68%). The metaphosphate compounds isolated via the use of this method were identified using XRD analysis. SEM–EDX analysis showed micro-crystalline particles from the inorganic salts that were irregular and clustered, contrary to the amorphous micro particles which were produced from the CRM. The degree of specificity improved considerably using CRM ore (AMIS 0368) with high iron content (~76%, Fe3+/Fe2+). This method was shown to be highly selective towards metals with a stable trivalent oxidation state. No other elements of a different oxidation state were precipitated.