The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 14, 1989
Filed:
Oct. 13, 1987
Applicant:
Inventors:
Richard E Hall, Trenton, NJ (US);
Peter H Zeh, Fremont, CA (US);
Frederic B Jueneman, Newark, CA (US);
Assignee:
FMC Corporation, Philadelphia, PA (US);
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
C01B / ;
U.S. Cl.
CPC ...
4233 / ;
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.