Edited by RALPHK. BIRDWHISTELL University 01 West Florida Pensacola. FL 32504
textbook forum Textbook Error: Industrial ProductionOf Alumina Colln H. L. Kennard Unlverslty of Queensland Bnsbane. Q 4067
Australla
Most first-year chemistry textbooks comment on the Bayer process where alumina is extracted from bauxite by sodium hydroxide at high temperatures and pressures: A1203(s)+ 2OH-(aq)
-
2AlO,-(aq)
alumina. This might he chemically feasible but is c o m e r cially unlikely. In the industrial world', the A1(OH)4- is reprecipitated by dropping the temperature and pressure, and the supersaturated solution seeded. 2Al(OH),-
-
Al2O33H2O(s) + SOH-(aq)
A good review of both hauxite and aluminium production has already been publi~hed.~
+ H,0(1)
Solid impurities such as Fez03 and SiOn are removed. These textbooks then state that the pH of the solution is lowered by addition of carbon dioxide to precipitate the
'
Mullins-Gunst. K. L. "Bauxite to Aluminium"; Alcoa Australia. Nov. 1982. Lancash'we, R. Educ. Chem. 1982, (May), 74.
Volume 66
Number 4
April 1989
313
