On trending technologies of aluminium dross recycling: A review

The objective of this review is to critically evaluate important aspects of aluminium dross generation, classification, properties, applications, and its commercial recycling techniques. A by-product of aluminium industry, aluminium dross is recycled by pyrometallurgy, hydrometallurgy, and hydrothermal processes, leading to aluminium recovery and generation of valuable products. The dominance of pyrometallurgy on the industrial scale is evident, owing to the efficient metal recovery processes, namely, Rotary salt furnace (RSF) and salt-free technologies (SFT). On the laboratory research front, hydrometallurgy and hydrothermal processes emerge as promising routes of dross recycling. Production of zeolites, ion exchangers, molecular sieves, and layered double hydroxides is achieved by hydrothermal route and important aluminium-rich products, along with gases like H2, CH4, and NH3 are produced by hydrometallurgical route. The advantages and disadvantages of each route govern the applicability of these processes. With a plethora of modern technologies emphasising on the recycling of aluminium dross, a detailed investigation of each route is vital. The recycling of dross also contributes to the judicious preservation of natural resources consumed during aluminium production. In addition, the adverse effects of improper dross disposal on human health and the environment have been discussed.