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

NH4HSO4 roasting technology was used for preparing Al2O3 from fly ash. First, Al and Fe were extracted from fly ash by NH4HSO4 roasting and deionized water leaching. Then, the Al and Fe in the leached liquid were precipitated by adding NH4HCO3 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-Al2O3. The optimal conditions of the whole technology were determined by experiments. The quality of α-Al2O3 product is up to the technical indicator of YS/T 274-1998 standard.