Aluminium Recycling from Aluminium Dross in Secondary Aluminium Industry

Abstract

Aluminium dross, a byproduct from secondary aluminium production and a classified hazardous waste, has been regulated under Thai regulations. In general, the dross contains more than 50% aluminium metal by weight. Recovery of aluminium metal from the dross can not only add more value to the process, but reduce quantity of waste to be managed as well. In this study, effects of initial heating temperature and mixing time on the recovery of aluminium metal were investigated. The recovery process started with pouring byproduct from aluminium melting process and mixing it in the heated graphite crucible. Liquid aluminium metal was separated at the bottom solution and poured into receiving molds. Initial dross contained 70-80% aluminium metal by bromine-methanol decomposition and subsequent ICP analysis. The overall result showed that mixing time and initial temperature of graphite crucible did statistically affect the yield of aluminium metal recovery (P < 0.05). The condition that yielded the highest aluminium metal recovery (35-40% by mass) was found to be three minutes of mixing at 700-900 °C of crucible temperature. The recovered product was determined to contain 99% aluminium metal via spark optical emission spectroscopy.