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. 21, 1999
Filed:
Nov. 24, 1997
Robert J Barnett, Goldendale, WA (US);
Michael B Mezner, Sandy, OR (US);
Goldendale Aluminum Company, Goldendale, WA (US);
Abstract
A process for treating spent potliner material from aluminum reduction cells and recovering useful products. In the process, spent potliner material is introduced into an acid digester containing, for example, sulfuric acid. A gas component is produced which includes hydrogen fluoride and hydrogen cyanide. A slurry component is produced which includes carbon, silica, alumina, sodium compounds such as sodium sulfate, aluminum compounds such as aluminum sulfate, iron compounds such as iron sulfate, magnesium and calcium compounds such as magnesium and calcium sulfate. The slurry component remains in the digester after the gas component is removed. The gas component is recovered and heated an effective amount to convert or decompose the hydrogen cyanide to a remaining gas component including CO.sub.2, H.sub.2 O, and nitrogen oxides, as well as HF gas. The remaining gas component is directed through a water scrubber in which the HF gas is converted to liquid hydrofluoric acid. The hydrofluoric acid is then admixed with alumina trihydrate to form aluminum fluoride and water. Valuable refractory materials and salts are recovered also.