Slag/dross and
leaching residue are produced from the process of metal extraction. The commonly-seen
slag/dross/residue includes copper dross, lead dross, tin slag, zinc leaching
residue, antimony/arsenic dross, cadmium residue/cake, sulfur residue/cake,
vanadium slag, nickel slag, iron tailing and iron bearing red-mud waste.
Due to its low
concentration, it may be not profitable to extract single metal, so it is
usually landfilled. However, the increasing awareness of environment protection
requires a safer and better treatment method. Comprehensive recovery of these
slag/dross has been emphasized with greater attention.