Carbon black is a chemical product essentially composed of elemental carbon in the form of semispherical, colloidal particles, coalesced into each other forming particle aggregates.
Carbon black is mainly used in rubber applications, such as tires, belts, hoses, and non-rubber applications, such as plastic pipes, inks.
The carbon black particles are obtained by partial combustion and thermal decomposition of highly aromatic hydrocarbon oils under controlled conditions.
Coal Tar, Decant Oil from FCC, Ethylene Tar, collectively called Conversion Oils, are the typical feedstock for the production of carbon black.
There are many types of Carbon Blacks that differ in the physical-chemical properties of the particles, which are produced by varying the reactors operating conditions.
Besides the main classification dividing the Carbon Blacks into Hard and Soft Blacks, each of them is defined according to an ASTM standard.
The standard first defines for each grade many parameters, which are classified into:
- Size and specific surface parameters (identified by the series number 100, 200, 300, 500, 600 and 700)
- Structural parameters (properties like DBP for instance)
- Bulk Properties (bulk density, crushing strength, etc.)
The main parameters influencing the yield are BMCI and Sulphur content, BMCI being the most important.
The BMCI (Bureau of Mines Correlation Index) is a number correlated with the aromaticity of the feedstock.
To proper evaluate the BMCI one needs to know Specific Gravity and Mean Boling Point. Viscosity at 100°C is another useful parameter to evaluate the feedstock.
Carbon Black plants can handle up to 4% sulphur in the feed, but preferably work on a 2.5% because the sulphur, which will remain in the product, will influence the rubber properties.
Vicinity to the market was the main driving force for the Carbon Black Industry in the past. Nowadays the main driving force is the accessibility and vicinity to feedstock sources. This fact is incentivising new players, especially the refinery owners, to become strong players in the carbon black industry.