Electric arc furnace steelmaking is to generate an arc between the graphite electrode and the loaded scrap steel. The heat source of the arc dissolves the scrap steel, oxidizes and removes impurities in molten steel, adjusts the composition, and then produces steel. Graphite electrodes are essential in the process of eaf steelmaking.
Graphite electrodes consumption
Furnace structure, operation, AC/DC mode, and graphite electrode quality will directly affect electrode consumption. Generally, in production, the electrode consumption per ton of steel is 1-4kg.
We found that the consumption of graphite electrodes for eaf steelmaking usually includes end consumption, side consumption, and loss. End loss is mainly due to sublimation and slag erosion caused by high-temperature arc heat at the end.
For example, in the AC ultra-high voltage operation refining process, the terminal consumption caused by high current increases, accounting for 50% of the total consumption. In the recently applied large-scale DC electric furnace, while using high current, the diameter of the electrode also increases accordingly, so the end loss caused by thermal shock becomes the primary consumption.
Graphite electrode vice consumption
Side consumption, and oxidation consumption, account for 50% of the total consumption of AC electric furnaces. Unlike terminal consumption, terminal consumption also occurs during power outages.
This consumption depends on electrode surface temperature, furnace surface area, gas composition and flow, and steel-making time. Generally, the bulk density of electrodes is increased to densify them to reduce oxidation consumption.
Graphite electrode for eaf steelmaking damage consumption
Damage consumption is an abnormal consumption different from the previous two consumptions and belongs to electrode accidents. Disconnection accidents include disconnection at the electrode hole, connector disconnection, and body disconnection. Coupled with loose tripping, the blocking material loss caused by the crack expansion at the end generally accounts for 0-10%.
After the graphite electrode for eaf steelmaking is energized, it will vibrate violently due to electromagnetic force and other reasons. At this time, if an external pressure exceeding the strength of the electrode is applied to generate thermal stress, the connection wire under the electrode’s main handle will break, significantly reducing production efficiency and increasing electrode consumption. You should avoid it as much as possible.
Properties of graphite electrodes
Specific ways to reduce consumption
Inclusion
The consumption in EAF steelmaking includes average consumption, such as arc light consumption, chemical consumption, and oxidation consumption; abnormal consumption, such as mechanical electrode breakage, common tripping, severe oxidation in the buckle, and expansion of the nipple will cause the electrode to burst, etc. The factory can avoid these situations in production.
The quality of graphite electrodes is critical to the EAF steelmaking process. Poor-quality products can prevent the electric arc from becoming unstable, resulting in incomplete steel melting and decreased productivity. Resistivity, bulk density, mechanical strength, and nipple quality are all related to consumption. Therefore, it’s essential to ensure that the products are of the highest possible quality.
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