This furnace gets its name from the fact that the electric arc is produced from direct or indirect contact with the metallic charge melted. In this kind of furnaces, any metal melted in the electric arc furnace and receives heat from the radiant heat obtained from the electric arc and from the refractory lining, which is heated by the arc. The rocking action of this furnace exposes more lining to the heat of the arc, which in turns allows the lining to deliver more heat to the metal. Basically, rocking allows the lining to heat the precious metals and the metal to cool the lining. The melt down time would be longer if the furnaces were not rocked and the lining would be damaged. Other advantage of this furnace is the mixing action given to the molten charge.
The construction of the furnace is quite simple. It consists of a barrel shaped steel shell with a heavy duty refractory lining. The electrodes for supplying the necessary energy for melting are centered on the axis of the barrel. A charging door is provided on the front of the barrel and the furnace is equipped with a special device supplied to rock the furnace automatically while it is in operation.
The power is supplied to the furnace from a transformer that steps down the 440 volt current delivered by the generator to 100 volts. The reactance control located on the transformer helps to stabilize the arc. Electrode regulation and power in put to the furnace is controlled in the control panel. A knife switch on the power panel is employed to isolate the panel form the source of power or to permit power to pass from the source of power to the panel. The amount of current passing through the carbon electrodes is controlled by the load adjusting rheostat.
Cross section of an electric arc furnace