Chemistry of inorganic compounds – Treating mixture to obtain metal containing compound – Group vib metal
Patent
1989-05-15
1990-09-04
Stoll, Robert L.
Chemistry of inorganic compounds
Treating mixture to obtain metal containing compound
Group vib metal
423 53, 423122, 423127, 423132, 423140, C22B 300, C01G 3700, C01F 700
Patent
active
049541684
ABSTRACT:
A method is provided for treating sludge containing substantial amounts of chromium, aluminum and iron and residuals of other elements. The method comprises forming a slurry of the sludge in water at a temperature ranging from ambient to 150.degree. F. with the specific gravity of the slurry ranging from about 1.05 to 1.25, and adding a mineral acid to the slurry to provide a pH ranging from about 0.1-3 to dissolve selectively the aluminum and the chromium and leave a solids residue containing gangue material comprising an oxidized iron compound, calcium sulfate, calcium fluoride, calcium silicate among other solids. The pH of the solution is controlled at range of about 2 to 3.5 to precipitate undesirable elements, including iron, without substantially adversely affecting the dissolved chromium and aluminum. The chromium/aluminum-containing solution is separated from the solids therein to provide a substantially purified solution of chromium/-aluminum, and the pH of the solution raised to a range of about 12 to 13.8 to precipitate chromium as chromium hydroxide and provide a pregnant aluminate solution. The chromium hydroxide-containing solution is then subjected to solid/liquid separation to extract chromium hydroxide therefrom and providea pregnant aluminate solution which is thereafter treated to recover alumina therefrom.
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Case Andrew B.
Crnojevich Ranko
Wiewiorowski Edward I.
Amax Inc.
Bos Steven J.
Ciomek Michael A.
Kalil Eugene J.
Stoll Robert L.
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