How long does the production cycle of graphite electrodes take?

What is the impact of electrical resistivity performance on the use of electrodes in steelmaking?
The resistivity of graphite electrodes is a physical indicator that reflects the conductivity of the electrode, which is related to the manufacturing process of the electrode. The country has qualitative regulations on the resistivity of graphite electrodes of different specifications and varieties. Generally speaking, when selecting electrodes of a certain specification, steel mills must choose within the resistivity range specified by the national metallurgical standards. Excessive resistivity will cause the electrode to turn red and heat up when energized, increasing the consumption of electrode oxidation.
What is the impact of bulk density performance on the use of electrodes in steelmaking?
The bulk density of graphite electrodes reflects the dense state of the electrodes and is closely related to the manufacturing process of the electrodes. The country has specified values for the bulk density of graphite electrodes of different specifications and varieties. Products with low bulk density indicate that the overall porosity of the product structure is high, and the oxidation rate of the product is faster at high temperatures, which can easily lead to increased electrode consumption. Generally speaking, when steel mills choose electrodes, it is better for the bulk density of the electrode to be within the specified value, but the higher the bulk density, the better. Because some electrodes with high bulk density sometimes have poor thermal shock resistance and are prone to surface peeling, chipping, and cracking during steelmaking, which can actually affect steelmaking.
Why should steel mills prevent the mixing of multiple products when using graphite electrodes?
The graphite electrodes used by steel mills are often supplied by multiple manufacturing companies, and multiple products are mixed during steelmaking. This not only makes it difficult for steel mills to calculate the consumption of a single product, but also results in differences in the physical and chemical properties and processing tolerances of electrodes and joints due to the different raw materials and manufacturing processes used by each manufacturer. Therefore, the fitting tolerance and other factors that may occur during mixing can easily lead to electrode detachment and breakage. The correct way to use is to use a product from one manufacturer alone and then connect it to another manufacturer's product. It is necessary to reduce the number of electrode replacements from different manufacturers and use connectors that are compatible with the same manufacturer's electrodes to prevent mixing.
What are the characteristics of needle coke?
Needle coke is a high-quality carbon raw material, divided into coal series and oil series. Its surface has obvious strip-shaped patterns, and most of them are long needle shaped fragments when broken. Under a microscope, fibrous structures can be observed, hence it is called needle coke. Needle coke is prone to graphitization at high temperatures above 2000 degrees. The graphite electrodes made from it not only have low electrical resistivity and high bulk density, but also have a small coefficient of thermal expansion, making it an essential raw material for producing ultra-high power electrodes and high-power electrodes. The price of needle coke is much higher than that of ordinary coke, currently about 5-8 times higher.
Will the dust collection system on the electric arc furnace have an impact on the consumption of electrodes?
The fan used in the vacuum system generates a certain negative pressure during operation, which increases the air flow velocity around the red hot electrode during steelmaking, thereby increasing the oxidation consumption of the electrode. When steelmaking, a well regulated vacuum system not only maintains a good working environment but also stabilizes the consumption of the electrode.
How to avoid increased electrode consumption during steelmaking?
To avoid an increase in electrode consumption during steelmaking, it is necessary to: (1) maintain a good power supply state and deliver electricity within the allowable current intensity range of the electrode according to the design requirements of the electric furnace. (2) Prevent the arc starting point from entering the molten pool. (3) Prevent immersion of electrodes into molten steel to increase carbonization. (4) If conditions permit, the electrode adopts spray cooling technology. (5) Set up the correct exhaust emission system. (6) Adopt the correct oxygen blowing system.
How long does the production cycle of graphite electrodes take?
The production process and corresponding time for a batch of ultra-high power or high-power graphite electrodes are as follows: electrode pressing (3 days) - baking (25 days) - immersion (4 days) - re baking (15 days) - graphitization (10 days) - machining and quality inspection (2 days) - finished product packaging and delivery (1 day). The fastest production cycle without interruption from feeding to product delivery is also 60 days, while the production cycle for electrode joints is as fast as 90 days due to the two immersion and three baking treatments required compared to electrodes.
What are the characteristics of electrodes produced by series connected graphitization furnaces?
The development direction of graphitization furnace is the internal heat series graphitization furnace. Due to the same current density of the series connected columns, the difference in electrode resistivity is very small; Secondly, the electrical resistivity at both ends of the internal series graphitization product is slightly lower than that in the middle (the electrical resistivity at both ends of the Acheson furnace graphitization product is higher than that in the middle), which is beneficial for reducing the resistance at the connection point during user use and alleviating the overheating and redness phenomenon at the joint connection point. Therefore, the electrode quality uniformity produced by the series series graphitization furnace is better than that of the Acheson furnace, and is more suitable for the production requirements of electric arc furnace steelmaking.
Why does the quality of electrode joints play an important role in electric arc furnace steelmaking?
The joint plays a crucial role in electrode steelmaking, and the quality of the joint directly affects the use of the electrode in electric furnace steelmaking. No matter how good the electrode quality is, if there is no high-quality joint to match it properly, problems will also occur during steelmaking. According to relevant information, more than 80% of electrode usage accidents in electric furnace steelmaking are caused by joint breakage and loosening. Therefore, selecting high-quality electrode joints is a guarantee for the normal use of electrodes in electric furnace steelmaking.
What quality indicators of graphite electrode (joint) products have an impact on electric furnace steelmaking?
(1) Quality indicators such as bulk density, resistivity, strength, elastic modulus, and thermal expansion coefficient of electrodes. (2) Quality indicators such as bulk density, resistivity, strength, elastic modulus, and thermal expansion coefficient of the joint. (3) The machining accuracy of electrodes and joints, no matter how good the quality of electrodes and joints is, without good machining accuracy (mainly referring to the fit between electrodes and joints), the use effect is not good. (4) The internal structural quality of electrodes and joints requires that there are no cracks that may cause potential hazards during use.
What are the consequences of severe oxidation of the electrode end face at the upper end of the electrode holder?
During steelmaking in a smelting furnace, scrap steel is burned inside the furnace. At the same time, due to oxygen blowing in the furnace, the height of the flame column is often higher than the electrode end face at the upper end of the gripper, which can easily oxidize the electrode end face. If the oxidation is severe, it can cause the electrode end face to deform from a flat surface to a sloping surface. When a new electrode is connected to the upper end, the oxidation deformation of the lower electrode end face cannot make good contact with the new electrode, and the electrode gap is large, which can easily cause oxidation and breakage of the internal joint. The best preventive measure without changing the steelmaking conditions is to add a protective cover on the electrode end face at the upper end of the gripper to block flames and air, in order to protect the electrode end face.