As the raw material of the binder, when the electrode paste is self-baked and sintered, the remaining coking residue can increase the strength of the electrode paste and make it uniform. The best binders are coal pitch and coal tar.
1. Coal tar
Coal tar is a group of fractions with a lower temperature than coal tar pitch. It is a viscous liquid with a color ranging from dark brown to black and a relative density of 1.05~1.25. The quality of tar mainly depends on the temperature conditions of coking and the structure of the furnace. In the furnace of the same structure, the temperature is the same, and the tar with the same composition and physical properties can be obtained when coking coal with different compositions.
2. Coal pitch
Asphalt is a black shiny solid substance with a relative density of 1.245 to 1.299. When the distillation temperature is 360. The residue left after the other components in the tar are extracted at the above is the pitch.
According to the size of the softening point, asphalt can be divided into soft asphalt (40-50.), medium asphalt (65-75.), hard asphalt (higher than 80.).