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:
Jul. 02, 1985
Filed:
Jan. 23, 1984
Seppo I Blomquist, Tornio, FI;
Markku T Saarela, Kokkokangas, FI;
Hannu J Pouru, Pori, FI;
Bror G Nyman, Vanha-Ulvila, FI;
Kaj-Henrik Lindroos, Helsinki, FI;
Timo T Koivunen, Vanha-Ulvila, FI;
Sigmund P Fugleberg, Pori, FI;
Outokumpu Oy, Helsinki, FI;
Abstract
The residual acid mixture containing metals which has been produced in the steel pickling process is regenerated to become new HF/HNO.sub.3 pickling acid by applying H.sub.2 SO.sub.4 addition and evaporation. The metal sulphate salt produced in evaporation is converted into scarcely soluble iron jarosite Na[Fe.sub.3 (SO.sub.4).sub.2 (OH).sub.6 ] and chrome and nickel hydroxide, the last mentioned metal hydroxide being obtained as a separately utilizable precipitate. The metal sulphate salt is separated from 60% H.sub.2 SO.sub.4 solution, wherein the main part of the salt is also crystallized. For promoting the crystallization, part of the salt is crystallized in a side line where 80% H.sub.2 SO.sub.4 concentration is used. The acid slurry produced is carried back to the crystallizing stage in the main line.