PURPOSE: To dispense with a large-scale piping work by connecting a fluorine- contg. water storage tank to a detachable granular calcium carbonate-packed tower through a pipeline, returning the treated water leaving the tower to the storage tank and separately treating the fluorine-contg. water.
CONSTITUTION: The fluorine-contg. water 1 discharged from the semiconductor production field, etc., is firstly introduced into a storage tank 2, and dilution water 3 such as demineralized water and city water is injected to adjust the fluorine concn. The water 1 in the storage tank 2 is then introduced into a granular calcium carbonate-packed tower 4 upward through a liq. pipeline 5 provided with a circulating pump 7 and allowed to react with calcium carbonate, and the fluorine is recovered as calcium fluoride. The water leaving the tower 4 is returned to the storage tank 2 through a circulating pipeline 6 and recycled. When complete conversion of the calcium carbonate in the tower 4 to calcium fluoride is confirmed from the fluorine concn., the tower 4 is exchanged for a fresh packed tower 4.
SATO SHIN
TAKADOI TADASHI
MIKI MASAHIRO
FUKUTOME TOSHIRO
MAENO MATAGORO
HASHIMOTO CHEM CORP