METHOD OF PRODUCTION OF ALUMINUM OXIDE Russian patent published in 2003 - IPC

FIELD: inorganic chemistry; methods of production of aluminum oxide from aluminum-containing ores through treatment with nitric acid; non-ferrous metallurgy; production of aluminum. SUBSTANCE: proposed method includes calcination, grinding, leaching by nitric acid and cleaning solution of aluminum nitrate from iron by introducing nitrate crocus. Leaching with nitric acid is performed at boiling point of solution till pH of solution in not above 1.5; prior to introducing nitrate crocus, dibasic aluminum nitrate is added to aluminum nitrate solution thus obtained for neutralization of excessive acid and separation of sediment of ferric hydroxide; product thus obtained is filtered and nitrate crocus in the amount no less than 20-fold amount of excess in terms of residual amount of ferric oxide is introduced in the solution thus obtained; after introduction of nitrate crocus, solution is kept for an hour at boiling point; product is filtered and is subjected to thermal hydrolysis at temperature not above 330 C; then, compounds of alkali and alkali-earth metals are separated from the product thus obtained and solid residue is calcined to obtain aluminum oxide; after thermal hydrolysis separation of compounds of alkali and alkali-earth metals is performed in distilled water at temperature of 70-80 C by mixing and filtration of suspension; thermal hydrolysis includes return of nitric acid for leaching. Proposed method simplifies technological scheme of process due to avoidance of autoclave treatment at content of iron in finished product not above 0.05% (in terms of ferric oxide). EFFECT: enhanced efficiency. 3 cl