Carbon black is virtually pure elemental carbon in the form of colloidal particles that are produced by incomplete combustion or thermal decomposition of gaseous or liquid hydrocarbons under controlled conditions. Its physical appearance is that of a black, finely divided pellet or powder. Its use in tires, rubber and plastic products, printing inks and coatings is related to properties of specific surface area, particle size and structure, conductivity and colour. Carbon black is also in the top 50 industrial chemicals manufactured worldwide, based on annual tonnage. Approximately 90% of carbon black is used in rubber applications, 9% as a pigment, and the remaining 1% as an essential ingredient in hundreds of diverse applications.
Modern carbon black products are direct descendants of early "lamp blacks" first produced by the Chinese over 3,500 years ago. These early lamp blacks were not very pure and differed greatly in their chemical composition from current carbon blacks. Since the mid-1970s, most carbon black has been produced by the oil furnace process, which is most often referred to as furnace black.
Two carbon black manufacturing processes (furnace black and thermal black) produce nearly all of the world's carbon blacks, with the furnace black process being the most common. The furnace black process uses heavy aromatic oils as feedstock. The production furnace uses a closed reactor to atomize the feedstock oil under carefully controlled conditions (primarily temperature and pressure). The primary feedstock is introduced into a hot gas stream (achieved by burning a secondary feedstock, e.g., natural gas or oil) where it vaporizes and then pyrolyzes in the vapour phase to form microscopic carbon particles. In most furnace reactors, the reaction rate is controlled by steam or water sprays. The carbon black produced is conveyed through the reactor, cooled, and collected in bag filters in a continuous process. Residual gas, or tail gas, from a furnace reactor includes a variety of gases such as carbon monoxide and hydrogen. Most furnace black plants use a portion of this residual gas to produce heat, steam, or electric power.
The thermal black process uses natural gas, consisting primarily of methane or heavy aromatic oils, as feedstock material. The process uses a pair of furnaces that alternate approximately every five minutes between preheating and carbon black production. The natural gas is injected into the hot refractory lined furnace, and, in the absence of air, the heat from the refractory material decomposes the natural gas into carbon black and hydrogen. The aerosol material stream is quenched with water sprays and filtered in a bag house. The exiting carbon black may be further processed to remove impurities, pelletized, screened, and then packaged for shipment. The hydrogen off-gas is burned in air to preheat the second furnace.
Carbon Black Applications
|Rubber||Reinforcing filler in tires and mechanical rubber components, conductivity|
|Printing Inks||Pigmentation, rheology, tinting|
|Coatings||Black and grey pigmentation, tinting, UV protection, conductivity, conductor coating|
|Paper||Black and grey pigmentation, conductivity, decorative and photo-protective papers|
|Construction||Cement and concrete pigmentation, conductivity|
|Power||Carbon brushes, electrodes, battery cells|
|Metal reduction compounds||Metal smelting, friction compound|
|Metal carbide||Reduction compound, carbon source|
|Fireproofing||Reduction of mineral porosity|
|Insulation||Graphite furnaces, polystyrene and PU foam|
|Wire and Cable||UV protection and conductivity|
|Thermal Insulation||Improvement of insulation properties|
* Other grades available as per requirement for industrial, rubber and speciality carbon blacks.