Carbon black industry is on the verge of a thorough transformation. Several producers are forced to phase the relevant facilities out because of obsolescence and pollution, leaving room to new modern and efficient plants. While in the past the carbon black producers where located in the proximity of main consumers, without being integrated upstream, in the future a tight control over the main factor of OPEX, the CB feedstock, is of the essence for widening the carbon black plants profitability.

The vicinity to the consumers is nowadays less strategic as the carbon black product doesn’t suffer shipping on long distances and it doesn’t deteriorate.

ASTM STANDARDS

Carbon black classification encompasses a number series and grades in accordance to ASTM standard.
N110, N220, N330 series are defined as hard black grades, N440, N550, N660, N770 series, as soft grades.
Particle size, aggregate size, morphology, surface area, bulk properties are the most important parameters that identify the specific grade of the final product and therefore its range of applications.

CARBON BLACK FEEDSTOCK

Carbon black is obtained using as feedstock heavy residues coming from refinery conversion units for instance. Feedstocks may differ in composition, characteristics and properties, which have to be carefully examined during the process design in order to obtain the required carbon black product qualities.
Bureau of Mines Correlation Index (BMCI) measures the feedstock aromaticity and it’s a good index for characterize the yield. This index has to be adjusted for sulphur, oxygen and nitrogen feedstock contents as these components have a detrimental effect on carbon black yields.
The sulphur content in general is influential for a high BMCI, though sulphur does not contribute to the production yield. While sulphur is tolerated in most carbon black grades, nevertheless it shouldn’t exceed 2-3% in weight, as it is responsible for the formation of corrosive gases that ultimately deteriorate the equipment downstream the reactor. Some high-end grades such as N115 and N220 mostly applied in the UV pipes for water supply should feature 0.1-0.2% wt. sulphur content so to comply with the so called “smell & taste” characteristics.
Iron, nickel, vanadium, catalyst are associated with ash, their presence can be detrimental to the reactors refractory and contribute to the high grit in the final product.
Pentane insoluble, when present in appreciable amount, have a detrimental effect on the abrasion resistance and the surface area of the carbon black grades.