METHOD OF PROCESSING ALUMINATE SOLUTION IN PRODUCTION OF ALUMINA FROM NEPHELINE Russian patent published in 2002 - IPC

FIELD: production of alumina by sintering; production of alumina from nepheline raw material in particular. SUBSTANCE: proposed method includes leaching, desilicification, dividing the aluminate solution into two parts: one part is fed to soda battery and is decomposed through carbonization obtaining aluminum hydroxide and second part is fed to soda alkaline battery and is decomposed by carbonization and centrifuging; suspension thus obtained is classified in classifier; aluminum hydroxide and mother liquor are filtered. Solution admitted to soda alkaline battery is preliminarily mixed with aluminum hydroxide taken from upper zone of classifier and is kept at continuous mixing and at temperature of 87 to 65 C for 1 to 4 h. Then, suspension is mixed with aluminum hydroxide from soda battery and is treated with carbon dioxide. Amount of aluminum hydroxide taken from upper zone of classifier and returned to soda alkaline battery ranges from 0.07 to 0.5 of concentration of Al₂O₃ in aluminate solution. After treatment with carbon dioxide, suspension is kept at continuous mixing till caustic module of 3.1 to 4.1 has been obtained. EFFECT: low content of fine fractions in produced aluminum hydroxide. 3 cl, 5 tbl