EP 0777628 A1 19970611 - IMPROVED PROCESS FOR THE EXTRACTION OF ALUMINA FROM BAUXITE
Title (en)
IMPROVED PROCESS FOR THE EXTRACTION OF ALUMINA FROM BAUXITE
Title (de)
VERBESSERTES VERFAHREN ZUR EXTRAKTION VON ALUMINIUMOXID AUS BAUXIT
Title (fr)
PROCEDE AMELIORE CONCERNANT L'EXTRACTION D'ALUMINE A PARTIR DE LA BAUXITE
Publication
Application
Priority
- AU 9500526 W 19950823
- AU PM761194 A 19940823
Abstract (en)
[origin: WO9606043A1] A process for the extraction of alumina from bauxite having a relatively high boehmite content including the steps of digestion of the gibbsite fraction of the bauxite over a period of about 2 to 2.5 minutes at a temperature of about 135 DEG to 145 DEG C and at an A/C ratio of about 0.76, to achieve negligible boehmite reversion, substantially complete kaolinite dissolution and substantially no precipitation of DSP, subjecting the liquid fraction from the gibbsite digestion stage to post-desilication in the presence of hydroxysodalite seed to reduce the silica concentration close to the solubility of hydroxysodalite, subjecting the liquid fraction to secondary desilication using tricalcium aluminate produced externally by the addition of lime to spent liquor to minimise alumina losses from the pregnant liquor and to reduce the silica content in the spent liquor to reduce scaling, subjecting the residue from the biggsite digestion to an additional digestion step to digest the boehmite, said digestion of the boehmite fraction being formed at lower temperature and/or lower residence time than is normally the case.
IPC 1-7
IPC 8 full level
C01F 7/062 (2022.01); C01F 7/47 (2022.01)
CPC (source: EP)
C01F 7/062 (2013.01); C01F 7/47 (2013.01)
Designated contracting state (EPC)
DE ES FR IE IT
DOCDB simple family (publication)
WO 9606043 A1 19960229; AU PM761194 A0 19940915; BR 9508761 A 19980113; CA 2197457 A1 19960229; EP 0777628 A1 19970611; EP 0777628 A4 19990609
DOCDB simple family (application)
AU 9500526 W 19950823; AU PM761194 A 19940823; BR 9508761 A 19950823; CA 2197457 A 19950823; EP 95928901 A 19950823