METHOD FOR RECOVERING FLUORINE IN WASTE WATER

摘要

PURPOSE:To recover F ion in a waste water as the reutilizable concnd. fluorine by bringing a weakly basic ion-exchange resin having adsorbed the F ion into contact with ammonium hydroxide and eluting the F ion. CONSTITUTION:A waste water contg. F ion is introduced into an active-carbon tower 2 from its storage tank 1 to remove impurities and then sent to a strongly acidic cation-exchange resin tower 3 to exchange the dissolved neutral salt of hydrofluoric acid for hydrofluoric acid. The waste water is then passed alternately through the first and second weakly basic ion-exchange resin towers 4 and 5 to saturation-adsorb the F ion on the weakly basic ion-exchange resin. The eluate contg. ammonium hydroxide is passed through the weakly basic ion-exchange resin to elute the F ion as ammonium fluoride and sent to a storage tank 7. The aq. ammonium fluoride soln. is then concentrated and recovered.