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. 19, 1985
Filed:
Feb. 07, 1977
Johann-Nikolaus Meussdoerffer, Leverkusen, DE;
Hans Niederprum, Monheim, DE;
Hans-Georg Nieder-Vahrenholz, Cologne, DE;
Wolfgang Bockelmann, Leverkusen, DE;
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
In the disintegration of a chromite or chromium-containing residue, wherein the chromium-containing material is disintegrated with an alkaline compound in the presence of oxygen and a diluent at a temperature above about 800.degree. C. and thereafter leached, the improvement which comprises pre-roasting the chromium-containing material prior to addition of the alkaline compound. Pre-roasting can be effected at 400.degree. to 1200.degree. C. with addition of certain amounts of silica dioxide and/or aluminum oxide and such additives, depending on the chromium containing material, if still required, are added--prior to disintegration and leaching--in such a quantity to establish a ratio of SiO.sub.2 : AL.sub.2 O.sub.3 of about 2:1 and further a ratio, calculated on the basis of NaOH as the alkaline compound, of SiO.sub.2 : Na.sub.2 O of about 1:0.5 plus a Cr.sub.2 O.sub.3 : Na.sub.2 O ratio of about 1:2 to 1:4. Residues from previous leaching cycles can be present during disintegration as solid diluents but their contents of SiO.sub.2 and/or Al.sub.2 O.sub.3 are not taken into account in calculating the SiO.sub.2 :AL.sub.2 O.sub.3 ratios. The process gives excellent results even with starting materials relatively high in SiO.sub.2 which are difficult to disintegrate to materials of desirable properties by other methods.