Abstract A method for the preparation of alumina, the method comprising the steps of: treating aluminous material to increase the alumina content to over about 30 %; treating the aluminous material to provide particle size less than about 0.5 mm; calcining the aluminous material at about 400 - 700 0C; treating the aluminous material to provide particle sizes less than about 500 [tm; leaching the aluminous material with a mineral acid to provide a pregnant liquor; conducting a plurality of steps of precipitating aluminium chloride hexahydrate; conducting a plurality of ion exchange steps; and calcining aluminium chloride hexahydrate to provide alumina.
formerly, the impression was ATC was proposing to produce HPA using a 45 micron feed with 42.3% recovery, per the bottom table below. However, with Iggy Tan, this appeared to change to 300 micron feed with 70% recovery, per the top table below.
Since the patent application refers to "particle size less than about 0.5 mm" [500 microns] the impression is ATC is seeking a patent for its 300 micron processing
Whether ATC will succeed in patenting what they formerly appeared to say was "old technology" for their "300 micron" feed remains to be confirmed. However, other companies, such as FYI & HEG, have not mentioned using a 300 micron processing plan. HEG in particularly have identified their optimal micron size to be 63 microns
