Abstract: A process for removing fluorine from phosphoric acid solutions comprising combining relatively dilute (e.g. 28% P.sub.2 O.sub.5) fluorine-containing phosphoric acid with up to about 2% colloidal silica, heating said slurry to a temperature of about 190.degree. F under reduced pressure in phosphoric acid concentrators and removing silicon tetrafluoride in a vapor stream. The liquid stream is concentrated (50% to 54% P.sub.2 O.sub.5) phosphoric acid having a fluorine content of less than about 0.5%. The gaseous silicon tetrafluoride which also contains water vapor is alternatively scrubbed with a solution of ammonium bifluoride to convert said silicon tetrafluoride to fluosilicic acid and ammonium fluosilicate or with a solution of ammonium fluoride to convert said silicon tetrafluoride to ammonium fluosilicate.