Recovery of high surface area alumina from aluminium dross tailings

Aluminium dress tailings (ADT), a chemical waste from a factory producing aluminium in Egypt, was used for the recovery of the aluminium content in the form of alumina (Al2O3). Extraction of the aluminium was carried out via atmospheric- and high-pressure leaching with caustic soda. Then, it was separated from the sodium aluminate solutions thus obtained, using six different precipitation methods. The precipitates were filtered, washed, dried and calcined at 600 degrees C to produce the test aluminas. The precipitates and the calcination products were analysed for their chemical and crystalline phase compositions. The calcination products (aluminas) were subjected to sorpometry for surface area determination, and to particle sizing. The results indicated that highly pure (SiO2 < 0.53% and Na2O<0.1-14%), well-defined crystalline gamma-aluminas of high surface areas (>200m(2)g(-1)) and uniform small crystallite sizes (60-70 Angstrom) could be efficiently recovered from ADT. Optimal recovery conditions were examined and determined. (C) 2000 Society of Chemical Industry.