Consumption mechanism of graphite electrode
The consumption of graphite electrode in electric furnace steelmaking is mainly related to the quality of the electrode itself, and also has a great relationship with the furnace conditions of steelmaking (such as old and new furnace, whether there is mechanical failure, whether there is continuous production, etc.) and steelmaking operation (such as the type of steel, oxygen blowing time, charge condition, etc.). The consumption of the graphite electrode itself is only discussed here. The consumption mechanism has the following aspects:
► The end use
It includes the sublimation of graphite material caused by high temperature of electric arc and the loss of chemical reaction between electric extreme end and molten steel and slag. The high temperature sublimation rate at the end is mainly determined by the current density passing through the electrode, and it is also related to the diameter of the electrode after oxidation, and the consumption at the end is also related to whether the electrode is inserted into the molten steel to carbonize.
► Lateral oxidation
The chemical composition of the electrode is carbon. Under certain conditions, carbon will oxidize with air, water vapor and carbon dioxide. The amount of oxidation at the side of the electrode is related to the unit oxidation rate and exposed area. In general, the amount of oxygen on the side of the electrode accounts for about 50% of the total electrode consumption. In recent years, in order to improve the speed of electric furnace smelting, the frequency of oxygen blowing operation has been increased, leading to increased oxidation loss of electrodes. In the process of steelmaking, it is an intuitive method to measure the antioxidant capacity of the electrode by observing the redness degree of the electrode trunk and the taper degree of the lower end.
► Residual loss
When the electrode is continuously used to the connection of the upper and lower electrodes, a small section of the electrode or the joint (i.e. the residual body) will be detached due to the oxidation of the body and the fineness of the cracks. The residual loss is related to the shape of the joint, the internal structure of the electrode, the vibration and impact of the electrode column.
► Surface peeling and dropping
The result of the poor thermal vibration resistance of the electrode in the process of quenching and heating.
► Electrode broken
Includes electrode trunk fracture and joint fracture. The electrode fracture is related to the quality of graphite electrode and joint, the processing fit, and the steelmaking operation. The reason is often the focus of the dispute between steel mills and electrode manufacturers.