The consumption of graphite electrode in electric furnace steelmaking is mainly related to the quality of the electrode itself, as well as the furnace condition and steelmaking operation.
Modern steelmaking methods mainly include converter steelmaking, open hearth steelmaking and electric steelmaking.
The open hearth steelmaking method has been basically eliminated. The most fundamental difference between the electric furnace steelmaking method and the converter steelmaking method is that the electric furnace steelmaking method USES electric energy as the heat source, while the electric arc furnace steelmaking method is the most widely used electric furnace steelmaking method.
What we usually refer to as electric furnace steelmaking, mainly refers to the electric arc furnace steelmaking, because other types of electric furnace such as induction furnace, electroslag furnace, etc. make less steel.
Electric arc furnace (eaf) steelmaking is a kind of steelmaking method that generates electric energy into heat energy in arc light by discharging electric arc between electrode and charge, and then heats and melts metal and slag by direct action of radiation and electric arc to make various steel and alloy.
The consumption of graphite electrode in electric steelmaking is mainly related to the quality of the electrode itself, as well as to the condition of the furnace (such as the old and new furnace, whether there is any mechanical fault, whether continuous production, etc.) and the operation of steelmaking (such as the smelting steel, oxygen blowing time, charge condition, etc.).
The consumption of the graphite electrode itself is only discussed here, and its consumption mechanism has the following aspects:
1. End consumption
These include the sublimation of graphite material caused by high temperature of electric arc and the loss of chemical reaction between electric extreme part and molten steel and slag.
The high temperature sublimation rate at the end mainly depends on the current density passing through the electrode, and is related to the diameter after oxidation of the side part of the electrode.
2. Side oxidation
The chemical composition of the electrode is carbon, which has oxidation reactions with air, water vapor and carbon dioxide under certain conditions. The oxidation amount of the electrode side is related to the unit oxidation rate and exposure area.
Generally, the oxidation of the electrode side should account for about 50% of the total electrode consumption.
In recent years, in order to improve the smelting speed of electric furnace, the frequency of oxygen blowing operation is increased, which leads to the increase of electrode oxidation loss.
The redness of the electrode trunk and the taper of the lower end are often observed in the process of steelmaking.
3. Stump loss
When the electrode is used continuously to the connection of the upper and lower electrodes, a small section of the electrode or the joint (that is, the residual body) will break off due to the oxidation thinning of the body or the penetration of cracks.
The size of the residual loss is related to the joint shape buckle, the internal structure of the electrode, the vibration and impact of the electrode column.
4. Surface peeling and dropping
In the process of smelting, the thermal shock resistance of the electrode itself is poor.
5. Electrode breaks
Include electrode trunk break and joint break.
Electrode fracture is related to the quality and processing of the graphite electrode and the joint, as well as the steelmaking operation.
