Synthesis of Hercynite from Aluminium Dross at 1550°C: Implication for Industrial Waste Recycling

Abstract

Aluminium dross is a waste from aluminium melting process, containing approximately 70 wt% of Al2O3. Disposal of dross in landfill causes soil and ground water pollutions, leading to the difficulty of waste management. This work aims to utilize aluminium dross as a source of Al2O3 for the synthesis of hercynite (FeAl2O4). Aluminium dross was heated at 1200°C for 1 hour in air and then compacted into a substrate using a hydraulic press. The substrate was brought into contact with two different types of iron chip at 1550°C in air for 6 hours. Pure iron chip and iron chips containing 0.8 wt% carbon were employed in this experiment in order to investigate the effect of carbon content in the iron chip on the formation of hercynite. The samples after reactions were characterized using XRD, SEM and EDS techniques. It was found that the final product is hercynite having a dark grey solid phase. The formation of hercynite was due to the interaction of Al2O3 in the dross with Fe and/or FeO in the system. FeO came from the oxidization of iron chip due to the excess of oxygen in the system. Carbon content in the iron was found to effect the formation of FeO in the system, which in turn effect the formation of hercynite. This research is one of the possible way to recycling aluminium dross instead of bury in a landfill.