Richard E. Hall - Trenton NJ Peter H. Zeh - Fremont CA Frederic B. Jueneman - Newark CA
Assignee:
FMC Corporation - Philadelphia PA
International Classification:
C01B 2516
US Classification:
423321R
Abstract:
Phosphoric acid is treated to remove and/or tie up heavy metals and antimony to enable the acid to be used in electrical semiconductor applications by reacting the acid with hydrogen sulfide and with hydrogen peroxide in separate treating steps. The hydrogen sulfide precipitates metal sulfides which are separated from the acid, and the hydrogen peroxide oxidizes dissolved antimony so that it is tied up and does not post-precipitate in the acid after removal of the metal sulfides.