Varieties of graphite electrodes
Electric arc steelmaking furnaces are generally divided into three categories, namely ordinary power electric furnaces, high power electric furnaces and ultra-high power electric furnaces. Corresponding to the power level of electric furnace steelmaking, graphite electrodes are also divided into 3 varieties accordingly, namely ordinary power graphite electrodes (code RP grade), high power graphite electrodes (code HP grade) and ultra-high power graphite electrodes (code UHP grade) ). The nominal diameter of the electrode ranges from 75mm to 700mm. The physical and chemical properties of high-power and ultra-high-power graphite electrodes are better than those of ordinary power graphite electrodes, such as low electrical resistivity, high volume density, high mechanical strength, low linear expansion coefficient, and excellent oxidation resistance.
Selection of Graphite Electrode for AC Arc Steelmaking Furnace
The electrode diameter of AC arc steelmaking furnace is shown in Table 2. Electric furnaces of different power should use graphite electrodes of corresponding varieties, such as high-power electric furnaces should use high-power electrodes. Different power furnaces have different choices of graphite electrode diameter. It is generally considered that ordinary power furnaces choose RP electrodes with diameters of 75～500mm; high power furnaces choose HP electrodes with diameters greater than 300mm; and ultrahigh power furnaces choose UHP electrodes with diameters greater than 400mm.
Graphite electrode diameter for AC arc steelmaking furnace：
Nominal capacity of electric furnace, t
Equipped electrode diameter,mm
Transformer capacity kVA
Ordinary power furnace
|High power furnace|
Ultra high power furnace
Attention should be paid to the use of conical joint connecting electrode
The biggest advantage of the conical joint is that the longitudinal section of the hole wall of the electrode connection hole is tapered, the outer wall is thin, the inner wall is thick, the overall strength is large, and it is not easy to burst. The middle of the joint has a large diameter and is not easy to be broken.
Note the following when using graphite electrodes:
(1) When selecting the electrode type and diameter, please refer to the capacity of the electric furnace and the capacity of the equipped transformer.
(2) During loading, unloading and transportation, the graphite electrode should be handled with care to protect the thread and prevent damage.
(3) During transportation and storage, the graphite electrode should be protected from moisture, otherwise it must be dried before use.
(4) Before connecting, use compressed air to blow off the dust in the thread of the electrode connector hole, and then tighten the connector and electrode, and the tightening torque must meet the requirements. In order to ensure that the electrodes of different specifications can reach the required tightening torque when connecting, some electric furnace steel plants have specially manufactured a tightening wrench. The tightening wrench has a sign indicating the size of the tightening torque to ensure correct operation. The holder should be clamped below or above the bottom of the electrode connector hole.
(5) The electrode lifting device of the electric furnace should react flexibly and should not be shaken during operation to prevent the electrode from being broken or the connector from being loosened and tripped.
(6) When charging the furnace, the bulk material should be placed in the lower part to prevent the material from collapsing and breaking the electrode during melting.
(7) During the refining period, the electrode can not be immersed in molten steel to increase carbon, so as to prevent the electrode from becoming thin and causing the electrode to break or the joint to fall.
(8) In order to prevent the electrode connector from loosening and tripping, it is recommended to use connector pins.