Process for the manufacture of coarse aluminium hydroxide

摘要

A process for the manufacture of coarse aluminum hydroxide via the Bayer Process. The process involves the decomposition of a supersaturated alkaline aluminate liquor in a two stage precipitation process having an agglomeration stage and a growth stage. The agglomeration stage takes place in agglomeration tanks, where the liquor is seeded with fine aluminum hydroxide to induce precipitation and formation of a suspension, followed by a growth stage, where the suspension is seeded with a coarse aluminium hydroxide. Typically, the feed of the supersaturated alkaline aluminate liquor is split over a first agglomeration tank at a higher liquor temperature of 70° to 100° C. and a second agglomeration tank or one or more of a series of second agglomeration tanks at a lower liquor temperature of 50° to 80° C.