Metal waste is a term used to describe the byproducts of metal production, such as SLAG and DROSS. SLAG is a glass-like material that is created when metal is melted and then cooled. It is usually composed of oxides of calcium, silicon, magnesium, and aluminum. DROSS is a solid material that is created when molten metal is exposed to air. It is composed of metal oxides, salts, and other impurities. Both SLAG and DROSS are considered metal waste and must be disposed of properly.