The bottom electrode of the electric furnace is composed of conductive refractory materials, anode copper plates, outlet terminals and air cooling systems, and is required to be insulated from the furnace shell. It requires that the refractory material itself not only has good high temperature performance, but also has good conductive performance. In the conductive furnace bottom air-cooled bottom electrode system, the furnace bottom conductive refractory material used as the anode must have the following characteristics:
(1) The resistance should be as low as possible, uniform and stable. This requires that the conductive refractory material must have good conductivity, otherwise the resistance will be too large, resulting in increased power consumption, increased furnace bottom temperature and reduced service life. For this reason, it is required that the resistivity should be between 10-4 and 10-3Q·m. At the same time, the resistivity of the conductive refractory material is required to be uniform and not change with temperature or change very little.
(2) Thermal conductivity is low. To ensure less heat loss and improve the thermal efficiency of the electric furnace.
(3) High resistance to thermal chemical and thermophysical corrosion coefficients. That is to say, it is required to have good slag resistance, shedding resistance, oxidation resistance and high compressive strength, so as to achieve low consumption and long service life.
Meeting the above requirements has important implications for the normal operation of DC electric furnaces. First of all, when the furnace starts to transmit power, the furnace bottom electrode has low resistance and good conductivity. It can be started without any preheating or turning on the electrode. Secondly, the stable and uniform conductive performance prevents the current density from being too high, causing the substrate to overheat, causing hot spots and premature damage.
