Aluminum chloride hexahydrate is thermally decomposed by using two dense fluidized-bed decomposers in series. The first decomposer is operated at 200 deg-400 deg c, part of the product gases from the second decomposer being recycled as fluidizing gas. The second decomposer is operated at 900 deg-1,000 deg c. In the first decomposer, 90-95 pct of the feed is decomposed. Thus, alcl3.6H2o was decomposed at 250 deg c for a residence time of 30 min in the presence of a fluidizing gas of steam and hcl in the volume ratio 2:1. The product contained 5 wt pct cl. In the second decomposer, operated at 1,000 deg c, the feed from the first decomposer was fluidized by a mixture of co2, n2, o2, and steam at a volume ratio of 1:10:1.6 For a residence time of 10 min. The product al2o3 contained <0.1 pct cl.
U.S. Patent Number 4,402,932, September 6, 1983, Chem. Abstr. 99:160,796M