Process for producing aluminum oxide from aluminum ash and inhibiting secondary dissolution of fluorine

The invention provides a process for inhibiting secondary dissolution of fluorine in aluminum oxide production from aluminum ash, the process comprises an aluminum ash harmless treatment system and a Bayer process aluminum oxide production system which are communicated, and the aluminum ash harmless treatment system comprises the following steps: carrying out size mixing and dissolution on the aluminum ash to obtain dissolved slurry; lime milk is added into the dissolved-out slurry to carry out primary fluorine fixing treatment on the dissolved-out slurry, and then solid-liquid separation is carried out to obtain filtrate and first-section dissolved-out filter residues; adding sodium carbonate and calcium into the obtained first-section dissolution filter residue to prepare raw slurry, sintering, cooling and ball-milling the obtained slurry, and feeding the slurry into a dissolution tank; during ball milling, the first filtrate and/or dilute alkali liquor are/is introduced to dissolve out aluminum oxide; a fl