Verfahren und Vorrichtung zur Reinigung von Industrieabgasen

摘要

Fluorine values are recovered from industrial waste gases containing fluorine and/or hydrogen fluoride, notably from gases evolved in the manufacture of aluminum through electrolysis of alumina in the presence of cryolite, by scrubbing with a highly acidic aqueous solution containing hydrogen fluoride in a first washing zone and then with an aqueous sodium hydroxide solution with formation of sodium fluoride in solution without precipitation in a second washing zone, splitting the stream of solution from each washing zone into a recycle stream for return to the zone wherein it was formed, and into a precipitation stream, and the two precipitation streams are combined to precipitate sodium fluoride, which is recovered with recirculation of resultant mother liquor to the first washing zone.