EAF graphite electrodes is primarily used in electric arc furnaces for the steel production process and also used in the refinement of steel and similar smelting processes.
What is eaf graphite electrodes?
EAF graphite electrodes are made of mixed petroleum coke and coal pitch, to be extruded, baked, impregnated, graphitized and machined for use as conductive material on EAF (Electric Arc Furnace) and LF (Ladle Furnace) for steelmaking.
Graphite electrode has many advantages that makes it used widely.
• It is easy to machine.
• It is very resistant to thermal shock.
• It has a low coefficient of thermal expansion (3 times lower than copper) which guarantees stability of electrode geometry during electro discharge machining.
• It is available in large blocks.
• It does not melt, but goes directly from the solid state to the gaseous at 3,400°C,
• which reduces wear.
• Its density is 5 times lower than that of copper, which results in lighter electrodes.
• It provides a higher metal removal rate than copper with less wear.
• It has the unique characteristic that the wear ratio tends to decrease as the peak current increases.
► Eaf graphite electrode consumption
The normal consumption of graphite electrode is divided into front consumption and side consumption. The following formula is calculated:
• Normal electrode consumption: CE=C +Cs
Front-end consumption: C =V ·TOntap/W,V =K ·I2/ DN
TOntap -- Electric furnace power supply time H,
W -- electric furnace steel weight T,
V -- electrode front consumption rate kg/h,
K -- front-end consumption constant (Bowman gives K =0.0361 and n is usually 0.58 for ac arc furnace),
I -- Arc current intensity kA,
D -- Electrode front diameter M,
• Side consumption: Cs=Vs· Ttop-top /W,Vs=3Ks·S
Ttop-top -- -- Electric furnace smelting cycle H,
W -- Electric furnace steel weight T,
Vs -- Electrode side consumption rate kg/h,
Ks -- Oxidation consumption rate kg/(m2·h),
S -- Oxidation surface area m2 in the electrode furnace,
At present, the Bowman electrode consumption model has been widely accepted in the production process. Once the smelting process is stable, the power supply current has the greatest influence on the single electrode consumption. According to the Bowman model, the influence of 60 T EAF current on the electrode consumption and smelting time is obtained, as shown in Table 1.
Table 1 Influence of current on electrode single consumption and smelting time