Brief introduction of a graphite electrode for electric arc furnace
The graphite electrode of the electric arc furnace refers to the conductor material that the electric arc furnace releases electric energy in the form of an electric arc to heat and melt the charge. It mainly uses petroleum coke and needle coke as raw materials, and coal tar pitch is used as a binder. It is calcined, batched, kneaded, and pressed. , Roasting, graphitization, and machining.
According to its quality indicators, it can be divided into regular power graphite electrodes, high power graphite electrodes, and ultra-high power graphite electrodes.
The steel-making electric arc furnace uses graphite electrodes as conductive materials and transfers heat energy to the charge through arc discharge to melt the charge. An ordinary electric arc furnace has three electrodes, each of which consists of 3 to 4 electrodes connected together with a tapered joint. The electrode is clamped by the gripper at the end of the cantilever. The cantilever and the soft bus connected to the power supply rise and fall together.
The heat during smelting is generated by the arc discharge between the electrode and the metal charge. The arc formed at its tip converts electrical energy into heat for smelting needs. Since most of it is in the furnace, it bears the radiant heat of the high-temperature furnace gas, the surface of the molten pool, the furnace wall, and the arc column at the electrode tip.
The furnace gas washes the surface of the electrode and heats the electrode by convection heating. This heat transfer effect is strengthened with the increase of furnace gas and material temperature and furnace gas volume.
It is precisely because of the harsh working environment that compared with other conductive materials, graphite materials have some excellent or irreplaceable characteristics under high-temperature conditions.
Graphite electrodes can be used at relatively high temperatures. The sublimation temperature is 3650℃. It is a high-temperature conductive material that can withstand high temperatures. In actual use, there is no other material that can replace it.
Graphite's strength increases with temperature at high temperatures; compared with other metals, graphite has the lowest coefficient of thermal expansion.
The consumption mechanism of graphite electrodes
The consumption of graphite electrodes in electric furnace steelmaking is mainly related to the quality of the electrode itself, as well as the condition of the steelmaking furnace (such as new and old furnaces, whether there is a mechanical failure, whether continuous production, etc.) and steelmaking operations (such as smelting steel types, blowing steel, etc.). Oxygen time, charge conditions, etc.) are very important. Here only discuss the consumption of the graphite electrode itself, its consumption mechanism has the following aspects:
Including the sublimation of the graphite material caused by the high temperature of the arc and the loss of the chemical reaction between the electrode end and the molten steel and slag. The high-temperature sublimation rate of the end mainly depends on the current density through the electrode, and secondly is related to the diameter of the side of the electrode after oxidation, and the end consumption is also related to whether the electrode is inserted into the molten steel to increase carbon.
The chemical composition of the electrode is carbon. Under certain conditions, carbon will undergo oxidation reactions with air, water vapor, and carbon dioxide. The amount of oxidation on the side of the electrode is related to the unit oxidation rate and exposed area. In general, the introduction of oxygen electric furnace steelmaking on the side of the electrode and the consumption mechanism of the graphite electrode account for about 50% of the total consumption of the electrode. In recent years, in order to increase the smelting speed of the electric furnace, the frequency of oxygen blowing operations has been increased, resulting in an increase in the oxidation loss of the electrode. Frequent observation of the redness of the electrode trunk and the taper of the lower end during the steelmaking process is an intuitive way to measure the electrode's oxidation resistance.
When the electrode is continuously used to the connection of the upper and lower electrodes, a small section of the electrode or the joint (ie the residue) will be separated due to the oxidation of the body and the penetration of the crack. The size of the stub loss is related to the shape of the joint, the internal structure of the electrode, the vibration, and the impact of the electrode column.
Surface peeling and falling blocks
In the process of smelting, the result is that the electrode has poor thermal vibration resistance due to the rapid cooling and heating.
Including broken electrode torso and broken joints. Electrode breakage is related to the quality and processing coordination of graphite electrodes and joints, as well as steelmaking operations. The cause is often the focus of disputes between steel mills and electrode manufacturers.
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All materials are tested to ensure they meet industry standards before entering the manufacturing phase.
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Our graphite electrode products have strict consumption control, low resistivity, low ash content, high temperature strength, low thermal expansion coefficient, good thermal conductivity and electrical conductivity, compact structure, high oxidation resistance, high mechanical stability and other significant advantages.