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

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, Al 4 C 3 , Al 2 S 3 , 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 NH 3 , CH 4 , H 2 S, and PH 3 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 Al 4 C 3 , Al 2 S 3 and AlP were hydrolyzed and transformed into honeycomb boehmite (AlOOH). The leachability of F - , Cl - , NH 4 + , 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 m 2 /g and 1.30 cm 3 /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.