Thermal pre-treatment of reactive aluminium alloy waste powders

This study focussed on assessing the efficiency of thermal pre-treatment of Al alloy waste powders to facilitate their subsequent treatment and disposal. Five samples originating from aluminium surface finishing industries underwent thermogravimetric analyses and were subjected to a laboratory tub furnace. Four set temperatures (450, 475, 500, 525 degrees C) for the tubular furnace were selected based on the TG results. Using sequential images of the sample inside the tubular furnace, the ignition delay time was calculated. In addition, the efficiencies of medium-temperature thermal pre-treatment were determined using the gas volume method. The shot blasting samples (S1 and S2) exhibited shorter ignition delay times compared to the sandblasting (S3) and one of the polishing samples (S4). The influence of ZnO alloy content on the ignition delay time was investigated, revealing that the ignition delay time decreased with an increase in ZnO alloy content. The raw and pre-treated materials were analysed for morphology, composition and reactivity. The pre-treatment efficiency of the samples improved, especially with a retention time longer than the ignition delay of the samples. Recommendations for the storage and handling of pre-treated products were provided.