A system for cooling non-ferrous metal dross comprises an open-top metal pan to receive the dross which pan is divided by internal partitions into open-top compartments and has sufficient heat capacity to act as a heat sink to absorb heat from the dross, and a hood shaped to fit over the pan when filled with dross to form a substantially closed cavity round the pan. An inert gas such as argon is introduced into this cavity to displace oxygen and reduce the extent of oxidation of residual metal in the dross.