Alpha alumina production in a steam-fluidized reactor
AssigneeAluminum Company of America
InventorSteven W. Sucech
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Abstract
A process for transforming alumina hydrate into an anhydrous product comprising at least 10 wt % alpha alumina. Alumina hydrate is dehydrated, heated and transferred to a reactor where it is fluidized with steam and maintained at a temperature of about 900.degree.-1350.degree. C. Steam fluidization enhances crystal growth and results in a product having uniform quality and superior grinding characteristics.
Claims20
A process for transforming alumina hydrate into an anhydrous alumina product containing alpha alumina, said process comprising
- (a) heating alumina hydrate in a dehydrating zone to a sufficiently high temperature and for a sufficient time to obtain an alumina having a residual water content below about 15 wt%,
- (b) transferring the alumina from said dehydrating zone into a heating zone and there heating the alumina to an elevated temperature greater than the temperature in said dehydrating zone,
- (c) transferring the alumina from said heating zone into a reactor separate from said heating zone and there maintaining the alumina in a fluidized bed at a temperature of about 900.degree.-1350.degree. C. for a sufficient time to transform the alumina into an anhydrous alumina product comprising at least about 10 wt% alpha alumina, and
- (d) fluidizing the alumina in the reactor at a pressure of less than about 1.5 atmospheres with a fluidizing gas comprising principally steam.
A process for transforming alumina hydrate into an anhydrous alumina product containing alpha alumina, said process comprising
- (a) heating alumina hydrate in a dehydrating zone to a sufficiently high temperature and for a sufficient time to obtain an alumina with residual water content below about 10 wt%,
- (b) transferring the alumina from said dehydrating zone into a heating zone and there heating the alumina to an elevated temperature greater than the temperature in said dehydrating zone,
- (c) transferring the alumina from said heating zone into a reactor separate from said heating zone and there maintaining the alumina in a fluidized bed at a temperature of about 1100.degree.-1300.degree. C. for a sufficient time to transform the alumina into an anhydrous alumina product comprising at least about 65 wt% alpha alumina, and
- (d) fluidizing the alumina in the reactor at a pressure of less than about 1.5 atmospheres with a fluidizing gas comprising principally steam.
Dependencies are inferred from the claim text.