Extraction of alumina from fly ash by ammonium hydrogen sulfate roasting technology

Abstract NH 4 HSO 4 roasting technology was used for preparing Al 2 O 3 from fly ash. First, Al and Fe were extracted from fly ash by NH 4 HSO 4 roasting and deionized water leaching. Then, the Al and Fe in the leached liquid were precipitated by adding NH 4 HCO 3 solution. After the mixed precipitations of Al(OH) 3 and Fe(OH) 3 were leached by NaOH solution, the NaAl(OH) 4 solution was decomposed by carbonation. Finally, the pure Al(OH) 3 was calcined to α-Al 2 O 3 . The optimal conditions of the whole technology were determined by experiments. The quality of α-Al 2 O 3 product is up to the technical indicator of YS/T 274-1998 standard.