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Graphite electrode related information

Release time:2019-11-04 From: Zhengnai Industry in China

Graphite electrode is a consumable material

Graphite electrodes are consumable materials. Although only a few kilograms of graphite electrodes are consumed per ton of electric furnace steel, the price of graphite electrodes is relatively high, and the electrode cost generally accounts for 5% to 10% of the cost of electric steelmaking. The oxidation loss of the electrode and the sublimation of the electrode tip at high temperature and the slag scouring are inevitably consumed. In addition, mechanical damage (mainly breakage or nipple hole expansion causes the nipple and the lower electrode to fall off) often accounts for a certain proportion.


Performance of natural graphite electrodes

The natural graphite electrode is an electrode produced by using natural graphite as a main raw material. Natural graphite is a non-metallic mineral with good conductivity. The ash content of the selected natural graphite can be reduced to less than 5%. The natural graphite and coal tar pitch can be obtained by kneading, molding, roasting and mechanical processing to obtain a natural graphite electrode, and the electrical resistivity thereof is generally 15~2μΩ·m. The electrical resistivity of the artificial graphite electrode produced by using petroleum coke as a raw material is higher. It is about 1 time, and its mechanical strength is low, and it is easy to break during use.

Carbon electrode

Carbon electrode is made of carbon materials by molding, roasting and mechanical processing of conductive electrode, once called carbon electrode.Carbon electrodes include various kinds of electrodes that are not graphitized after being burned, such as natural graphite electrode produced with natural graphite as raw material, and recycled electrode made with graphite scrap (waste or cutting debris of graphite electrode).


Composition and use principle of water-cooled graphite electrode

Water-cooled composite graphite electrode this is the conductive electrode used after the graphite electrode is connected with a special section of steel tube. The upper section of the water-cooled composite electrode is a seamless steel tube that is not consumed. The lower section is the graphite electrode connected with the upper section of steel tube through a water-cooled metal nipple. Water-cooling steel pipe outside surface is smooth, and electrode in contact is good, because the graphite electrode in the bottom of the water cooling pipe, so the connection electrode must be whole root steel tube nipple electrode from the electrode hole of furnace cover out and sent to a special assembly station to connect the new electrode, a specially designed quick mounted hose to ensure water on or off quickly, to prevent to produce steam or damaged due to overheating in water cooling tube.

Water-cooled composite electrode can save the main reason for graphite electrode consumption

The main reason why water-cooled composite electrode can save graphite electrode consumption is that the surface area of graphite electrode exposed to air is greatly reduced by about 40%. However, the operation of connecting electrodes is troublesome, which has a certain impact on the production efficiency of electric furnace. Therefore, it was not widely popularized in electric furnace steel mills until the end of 1980s.

Index of UHP Graphite electrode

Item Unit UHP
300-500mm 550-600mm 700-800mm
Electric resistivity Electrode μΩm 4.6-6.2 4.5-6.0 4.5-5.8
Nipple 3.5-5.0 3.4-4.5 3.3-4.3
Bending strength Electrode Mpa ≥10.5 ≥10.0 ≥10.0
Nipple ≥20.0 ≥22.0 ≥23.0
Elastic modulus Electrode Gpa ≤14.0 ≤14.0 ≤14.0
Nipple ≤20.0 ≤22.0 ≤22.0
Bulk density Electrode g/cm3 1.66-1.73 1.68-1.74
Nipple 1.75-1.82 1.78-1.85
CTE(100-600℃) Electrode 10-6/℃ 1.20-1.50 1.10-1.50
Nipple 1.10-1.40 1.00-1.30
Ash % ≤0.3


Vertical method

It is characterized in that the roasting product is perpendicular to the bottom of the furnace. Most of our large and medium-sized products use this method because it is labor-saving and efficient.

Bedding method

Our company produces small-size products mostly by the horizontal dressing method. The main feature of the horizontal dressing method is that the position of the baked goods into the furnace is perpendicular to the longitudinal direction of the furnace core and horizontally placed on the bottom mat.
Horizontal clothing is often used in the production of small-sized products.


Mixed furnace method

Some calcined products have a relatively short length, and the core space cannot be fully utilized in both vertical and horizontal installations, so that several rows of products can be stacked on one side of the product in a furnace. Regardless of whether the diameter of the roasting products in vertical or horizontal installations should be the same or the difference is small, only the mixing method of several rows of products is installed on the side of the furnace core, which is prone to large deviation of the temperature inside the furnace core and increase the quantity of waste products.

Misplaced method

The larger the diameter of the calcined product, the more likely the crack is to be generated when the temperature rises too fast or the furnace temperature is not uniform during the graphitization process. The phenomenon that the local temperature rises too fast in the furnace core is not only related to the rising power of the electric current, but also to the furnace core. The composition of the resistor is related. One of the disadvantages of the Acheson graphitization furnace is that the furnace resistance composed of the calcined product and the coke particles is not uniform, the current is passed through where the resistance is small, and the current is passed through where the resistance is large.