Defluorination of WPA to feed grade levels (P:F > 100) was found to be effective with acids of low Al content. Acids with higher Al levels cannot be defluorinated effectively due to a sharp decrease in the distribution coefficient of the fluorine. This is attributable to complexation of fluorine by Al. An important part of manufactured phosphoric acids contain aluminum in levels that render defluorination to feed grade requirements impractical. Treating such acids with SiO2as well as preconcentration prior to extraction result in some improvement in extractability but provides for marginal improvements only.