The mechanics of consumption of graphite electrodes in EAF steel making
The consumption of graphite electrode in EAF steel making is mainly related to the quality of electrode itself, Also has big relation with the exact EAF condition(furnace old or new, mechanical fault or not, continuous production or not) and the operation(Smelting steel grade, oxygen blow duration, furnace charge). Here we only discuss the consumption of graphite electrode itself, and the consumption mechanism is as follows:
The end use: These include the sublimation of graphite material caused by the high temperature of arc and the loss of chemical reaction between the electrode and the molten steel and slag.
High temperature sublimation rate at the end mainly depend on the current density going through the electrode; also related with the diameter of the electrode side after oxidation; End consumption is also related to whether to insert the electrode into the steel water to increase carbon.
Lateral oxidation: The chemical composition of the electrode is carbon, Carbon will oxidize with air, water vapor and carbon dioxide under certain conditions, and the oxidation amount of electrode side is related to unit oxidation rate and exposure area.
Normally, Electrode side oxidation accounts 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, oxidation loss of the electrode is increased. Observation of the redness of the electrode body and the taper of the lower end during steel making is an intuitive method to measure the antioxidant capacity of the electrode.
Residual loss: When the electrode is used continuously at the junction of the upper and lower electrodes, a small section of the electrode or joint is detached because of oxidative thinning of the body or penetration of cracks. Residual loss is related to the nipple shape, electrode internal structure, Vibration of electrode column and impaction.
4.Surface peeling and dropping
Surface peeling and dropping: The result of the poor thermal shock resistance of the electrode itself during the process of smelting.
Include electrode body broken and nipple broken. Electrode broken is related to the quality and machining of graphite electrode and nipple, also related to the operation of steel making. The reason is often a dispute between steel mills and electrode manufacturers.