A furnace includes a tank having outer and inner walls defining a closed canal to be filled with molten metal continuously circulating along the canal. The canal includes at least one heating area having a heating component for transferring energy to the molten metal thus overheating it; at least one loading area for loading metal or metallic waste into the molten metal; a melting/treatment area for receiving the overheated molten metal and material dragged on its surface. The overheated molten metal transfers its exceeding energy to the material, causing its melting/treatment. The furnace has a central hollow delimited by the inner wall and a driving component within the hollow, having a rotor with at least one magnet body and coupled to a motor and configured to rotate upon activation of the motor, generating a magnetic field capable of causing circulation of the molten metal in a continuous and cyclical manner.