Manila (Reuters)-Graphite electrodes are the main heating element used in electric arc furnaces, a steelmaking process that melts scrap from old cars or old electrical appliances to produce new steel.

Electric arc furnaces are cheaper to build than traditional blast furnaces, which use iron ore to make steel and use coking coal as fuel. But the cost of steelmaking is higher because they use scrap steel and are powered by electricity.

The electrode is part of the furnace lid and assembled into a column. The current then passes through the electrodes, forming a strong thermal arc, melting the scrap. Electrodes vary greatly in size, but can reach 0.75 meters (2.5 feet) in diameter and 2.8 meters (9 feet) in length. The maximum weight exceeds two metric tons.

Up to 3 kilograms (6.6 pounds) of graphite electrodes are required to produce one ton of steel.

The tip of the electrode will reach 3,000 degrees Celsius, which is half the temperature of the sun's surface. The electrodes are made of graphite because only graphite can withstand such intense heat.

Then tilt the furnace to one side and pour the molten steel into a huge bucket called a ladle. The ladle then transports the molten steel to the continuous casting machine in the steel mill, where the recycled scrap is used to make new products.

The electricity required for this process is enough to power a town with a population of 100,000. Each smelting in a modern electric arc furnace usually takes about 90 minutes and can produce 150 tons of steel, enough for 125 cars.

Needle coke is the main raw material used in electrodes, and manufacturers say that it may take up to six months to make these electrodes, including baking and rebake to convert the coke into graphite.

There are petroleum-based needle coke and coal-based needle coke, both of which can be used to produce graphite electrodes. "Petroleum coke" is a by-product of the oil refining process, while coal-based needle coke is made from coal tar that appears during the coke production process.

The following is the production capacity ranking of the world's top graphite electrode manufacturers in 2016:

Company name headquarters capacity share

*SGL Carbon stated in October 2016 that it would sell its graphite electrode business to Showa Denko.

Source: GrafTech International, British Steel, Tokai Carbon Co., Ltd.

Compiled by Manolo Serapio Jr.; Edited by Kenneth Maxwell and Richard Purin

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