The bottom electrode of electric furnace is composed of conductive refractory, anode copper plate, outlet terminal and air cooling system, and it is required to be insulated from furnace shell. It requires that refractories not only have good high temperature function, but also have good conductive function. In the air-cooled bottom electrode system of conductive furnace bottom, it is necessary for the conductive refractory as anode to have the following characteristics:
(1) The resistance should be as low as possible, even and stable. This requires that the conductive refractories should have good conductivity, otherwise the resistance is too large, resulting in the increase of power consumption, the increase of furnace bottom temperature and the decrease of life. Therefore, it is required that the resistivity should be between 10-4 and 10-3 Q · m, and that the resistivity of conductive refractories should be uniform and not change with temperature or change little.
(2) The thermal conductivity is low. To ensure less heat loss and improve the thermal efficiency of electric furnace.
(3) High physical and chemical heat loss coefficient. It is required to have good slag resistance, anti shedding, oxidation resistance and high compressive strength, and then achieve low consumption and high life.
To meet the above requirements has the main meaning for the normal operation of DC furnace. First of all, when the furnace starts the power transmission operation, the resistance of the furnace bottom electrode is low and the conductivity is good. It can be started without any preheating or starting the electrode. Secondly, stable and uniform conductive function, to avoid the current density is too large, so that the backing overheating, hot spots and premature damage.