Preparation of adsorbent from secondary aluminum dross by deep hydrolysis of active aluminum components

Abstract

As a hazardous waste, secondary aluminum dross (SAD) has troubled the aluminum industry for many years. The inefficient and incomplete hydrolysis of active aluminum components such as AlN, Al4C3, Al2S3, AlP in SAD was the main obstacle, which can react with water or even humid air to release toxic, harmful, flammable and odorous gases such as NH3, CH4, H2S, and PH3 to the environment. In this study, a novel approach to prepare adsorbent was proposed by the deep hydrolysis of active aluminum components from SAD with the aid of grinding activation. High-energy grinding could increase the hydrolysis rate of AlN by ∼30% and reduce the apparent activation energy of AlN hydrolysis by ∼40 kJ⋅mol−1 in SAD. After grinding-leaching treatment, up to 94.3% AlN, and most of Al4C3, Al2S3 and AlP were hydrolyzed and transformed into honeycomb boehmite (AlOOH). The leachability of F-, Cl-, NH4+, and heavy metals of the treated SAD was evaluated and met the specified requirements for pollution control. Moreover, adsorbent with uniformly covered active γ-alumina was prepared by roasting the harmless product at 600℃ for 2 h. The BET surface area and total pore volume of the as-prepared adsorbent reached 424 m2/g and 1.30 cm3/g, respectively, and the adsorption capacity of the adsorbent for F- reached 6.40 mg/g. Overall, the novel approach had the advantages of no additives, short process, and simple operation, which was expected to provide deep insights into the harmless treatment and reutilization of SAD.