Carbon black is a highly dispersible black powder produced by the incomplete combustion of hydrocarbons. It is highly pure, with an ash content generally less than 0.5%. Its particle size is extremely small, typically ranging from 10.0 to 500.0 nm, and its specific surface area is as high as 30 to 150 m2/g. Carbon black comes in a wide variety of varieties, and its production methods are also diverse.
Based on the production method, carbon black can be broadly classified into three categories: contact black, furnace black, and thermal black.
1. Contact black.
Contact black is produced when the flame of a burning gas contacts a cooler collecting surface, causing the carbon black produced by cracking to cool and adhere to the surface. Examples of contact blacks include channel black, drum black, and disc black.
2. Furnace black.
Furnace black is produced by using gaseous hydrocarbons, liquid hydrocarbons, or a mixture thereof as raw materials, supplied with appropriate air, and then burning and cracking them in a specially designed reactor. The resulting carbon black is suspended in the flue gas, then cooled and collected. Examples include gas furnace black, oil furnace black, and the long-standing lamp black.
3. Pyrolytic carbon black.
This type of carbon black, such as pyrolytic black and acetylene black, is produced by using gaseous hydrocarbons as raw materials and thermally cracking them in a reactor isolated from air. Carbon black is commonly used to produce isotropic electrical carbon products with high resistivity, mechanical strength, and purity. In addition, a small amount of carbon black may be added to the production of high-density carbon products to fill the micropores between the coke particles, providing densification and reinforcement.