30+ YEARS OF EXPERIENCE IN CARBON INDUSTRY

Electrode paste (self-baking electrode) is a core conductive consumable in the production of ferroalloys, calcium carbide, and titanium slag in submerged arc furnaces. The quality of the binder asphalt directly determines the electrode sintering speed, mechanical strength, and conductivity, directly affecting the incidence of electrode soft break, hard break, and electrode hanging. Traditional domestic electrode pastes generally use medium-temperature pitch as a binder. However, modified pitch (high-temperature pitch), with its advantages of high coking value, high β-resin, and low volatile matter, is gradually becoming the upgrade direction for closed pastes and electrode pastes for large-scale, high-load submerged arc furnaces.

Coal pitch solidifies at certain temperatures into a brittle solid with a conchoidal fracture, exhibiting a glassy phase. It does not have a definite melting point, melting only within a certain range, and solidifies without a thermal effect.

The pitch composition is very complex, mostly consisting of aromatic hydrocarbons with three or more rings, as well as heterocyclic compounds containing oxygen, nitrogen, and sulfur, and small amounts of high-molecular-weight carbonaceous substances.

Medium-temperature coal pitch is a residue from tar distillation, accounting for 54-56% of the total tar yield. The molecular weight of the pitch component ranges from 200 to 2000, with a maximum of 3000. Medium-temperature pitch is classified based on its softening point, a softening point of 65-90℃ is considered medium-temperature pitch.

The mainstream binder for domestically produced electrode paste typically uses a mixture of electric calcined anthracite(ECA), metallurgical coke powder, and a small amount of graphite powder as aggregate, with an asphalt content generally between 20% and 24%. It is suitable for low-to-medium power open submerged arc furnaces and calcium carbide furnaces operating under low-load conditions, in production lines where electrode consumption requirements are not stringent.

Currently, the application of modified asphalt in the electrode paste industry is still under exploration, and medium-temperature asphalt remains the mainstream binder for electrode paste manufacturing.