The evacuation of liquid metals or mattes from metallurgical furnaces presents many operational challenges due to safety issues and the fast destruction of tapping blocks. Particularly, a continuous smelting and converting processes requires continuous tapping out with a precise control of the liquid metal or matte flow. Siphons are used in numerous metallurgical reactors including shaft furnaces for copper concentrate smelting and the Mitsubishi electric furnace. A new technique for the precise tapping out of metals or mattes has been developed. It is based on the apparent change of specific gravity of conducting liquids placed in a cross of a constant electric field and a permanent magnetic field. Additionally, the Lorentz' force in uniform electric and magnetic fields can be controlled by the magnetic flux and current intensity. This allows for a precise temperature control of the metal or matte. Fluidodynamic and heat transfer modeling, supported by low temperature physical modelin