Patent ID: 6547969
Filing Date: 2003-04-15
Classification: B01D,C02F,Y10S

Abstract:
A process for treating a fluorine-containing waste solution discharged during semiconductor process which treating process comprises adding calcium salt to said waste solution to form microparticles containing calcium fluoride, adding an inorganic coagulant to said waste solution containing the microparticles to form a coarse coagulated calcium fluoide, adjusting the pH of the waste solution to 7 to 10, wherein said inorganic salt is an iron salt selected from the group consisting of ferrous sulfate, ferric sulfate, ferric chloride, chlorinated copperas, and [Fe2(OH)n(SO4)3âˆ’n/2]m, wherein m and n each is a positive integer followed by filtration of said waste solution by cross-flow filtration so that said product is selectively accumulated on a filter membrane.