Synthesis of high-grade alumina from aluminium dross and its utilization for the sorption of radioactive cobalt

Abstract

Aluminium dross (AD) forms on the surface of molten metal as the latter reacts with the furnace atmosphere and is usually considered a waste of aluminium production. AD contains a complex mixture of mostly aluminium oxide (AO), nitride, carbide and sulfide, some alloying elements and salts. Nevertheless, AD is considered as hazardous waste and a rich source of alumina. In the present study, waste dross rich in alumina was treated with either acid or base dissolution to recover alumina. Aluminium sulphate (AS) and AO were produced using sulfuric acid and sodium hydroxide leaching, respectively. AS sample was calcined at 500°C, 700°C and 900°C, individually. At 900°C, AS was thermally degraded and transformed into AO. Also AO, (AO/H2 SO4) and (AO/HCl), was prepared using AD dissolution by NaOH and neutralized by dropwise addition of either 2 N H2 SO4 (AO/H2 SO4) or 2 N HCl (AO/HCl). The resulting samples were characterized by X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The resulting samples produced from acid and base leaching were applied to remove a harmful radionuclide (Co2+) from liquid waste. The maximum Co2+ adsorption capacity was 193, 180, 197, 296 and 235 mg g–1 for the as-prepared AS, where AS calcinated at 700°C, AO calcinated at 900°C, AO/HCl and AO/H2 SO4, respectively.