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:
Sep. 19, 1995
Filed:
Aug. 26, 1993
Applicant:
Inventors:
Dirk C Vermaire, Middelburg, NL;
Bernardus J Damman, Middelburg, NL;
Assignee:
Hoechst Aktiengesellschaft, Frankfurt am Main, DE;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
C22B / ; C22B / ; C22B / ;
U.S. Cl.
CPC ...
423 98 ; 423109 ;
Abstract
To remove lead, cadmium and zinc from dusts produced in the electrostatic precipitator in the electrothermal production of yellow phosphorus, the dusts are first digested by phosphoric acid having a content of at least 25% by weight of P.sub.2 O.sub.5 at temperatures above 60.degree. C. in a ventilated reaction zone. The digest solution is then separated in a filter zone into an essentially lead-, cadmium- and zinc-free solid residue and a phosphoric acid containing dissolved lead, cadmium and zinc.