Shaft electric furnaces are mainly intended for thermal and chemical-thermal treatment (roasting, tempering, nitriding, carburizing, etc.) of long length and large-sized products. They are performed in the form of round or rectangular shafts. For the controlled atmosphere creation shaft furnaces are sometimes equipped with a retort and a system of atmosphere supply and control. In shaft furnaces with operating temperatures <750 °C there can be set a device for forced convection creation. There are also vacuum shaft furnaces, for example for the titanium sponge reduction (reduction and separation furnaces), etc.