Graphite electrodes refer to a high-temperature resistant graphite conductive material made from petroleum coke and asphalt coke as aggregate and coal pitch as binder through processes such as raw material calcination, crushing and grinding, batching, kneading, molding, baking, impregnation, graphitization, and mechanical processing. They are mainly used for steelmaking, as well as for smelting yellow phosphorus, industrial silicon, abrasives, etc. In electric furnaces, they act as conductors that release electrical energy in the form of an arc to heat and melt the charge. The production process of graphite electrodes can be divided into three types: pressure vibration method, CNC automatic forming method, and mechanical processing method.
Graphite electrodes can be divided into regular power graphite electrodes, high power graphite electrodes, and ultra-high power graphite electrodes.
Regular power graphite electrodes (RP), which allow a current density of less than 17A/cm². The raw materials for these types of graphite electrodes are mainly petroleum coke and coal pitch, with a production cycle of about 45 days. They are mainly used for smelting ordinary steel, silicon, and yellow phosphorus.
High power graphite electrodes (HP) allow a current density between 18~25A/cm². These types of graphite electrodes use petroleum coke, coal pitch, and the addition of needle coke as raw materials. The production cycle is about 60 days and they are mainly used for steelmaking.
Ultra-high power graphite electrode (UHP) allows a current density greater than 25A/cm². The raw materials include petroleum coke, needle coke, and coal pitch, with a higher content of needle coke than high-power graphite electrodes. The production cycle is more than 65 days, and they are used for smelting refined steel and special steel.
Raw material costs account for a large proportion of the total cost of all types of graphite electrodes, exceeding 65%. The key material for graphite electrodes is needle coke. Using needle coke to produce ultra-high power electrodes for steelmaking can shorten the smelting time by 30%~50%, save electricity by 10%~50%, and effectively reduce steelmaking costs. A ton of finished ultra-high power graphite electrodes contains 0.85 tons of needle coke, and producing one ton of ultra-high power graphite electrodes requires 1.05 tons of needle coke.
The diameter of graphite electrodes ranges from 200-700mm, and due to the limitations of the molding machine, their diameter is difficult to exceed 700mm. The length generally ranges from 1800-3000mm, with the mainstream in China being 1800-2400mm.
Graphite electrodes belong to high-energy-consumption and high-emission industries. Under the background of restrictions on high energy consumption and high emissions, future capacity expansion may be restricted. Producing one ton of graphite electrodes consumes about 1.69 tons of standard coal. According to the conversion method of 2.66 tons of carbon dioxide per ton of standard coal, the carbon emission per ton of graphite electrodes is 4.48 tons, therefore future capacity expansion might be limited.
