Carbon Black Users Guide - Timcal

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The thermal black process uses natural gas, consistingprimarily of methane or heavy aromatic oils, asfeedstock material. The process uses a pair of furnacesthat alternate approximately every five minutesbetween preheating and carbon black production.The natural gas is injected into the hot refractorylinedfurnace, and, in the absence of air, the heatfrom the refractory material decomposes the naturalgas into carbon black and hydrogen. The aerosolmaterial stream is quenched with water sprays andfiltered in a bag house. The exiting carbon blackmay be further processed to remove impurities,pelletized, screened, and then packaged for shipment.The hydrogen off-gas is burned in air to preheat thesecond furnace.CARBON BLACK, SOOT, AND BLACK CARBONCarbon black is not soot or black carbon, whichare the two most common, generic terms appliedto various unwanted carbonaceous by-productsresulting from the incomplete combustion ofcarbon-containing materials, such as oil, fuel oilsor gasoline, coal, paper, rubber, plastics and wastematerial. Soot and black carbon also contain largequantities of dichloromethane- and tolueneextractablematerials, and can exhibit an ash contentof 50% or more.Carbon black is chemically and physically distinctfrom soot and black carbon, with most types containinggreater than 97% elemental carbon arrangedGeneral PropertiesTables 1 and 2 report general information related to carbon black. Detailed physical and chemicalanalysis for a particular grade of carbon black may be requested from your carbon black supplier.Table 1. Commercial names and chemical identification of carbon blackChemical NameSynonymsCAS NameCAS Registry NumberChemical (Molecular) FormulaCarbon BlackAcetylene Black, Channel Black,Furnace Black, Gas Black,Lampblack, Thermal BlackCarbon Black1333-86-4CTable 2. Properties and characteristics of carbon black (furnace process)Formula weightPhysical stateFlammable limits (vapor)Lower limit for explosionMinimum ignition temperatureVDI 2263 (German), BAM FurnaceGodbert-Greenwald FurnaceMinimum ignition energyBurn Velocity:VDI 2263, EC Directive 84/449Flammability classification (OSHA)SolubilityColor12 (as carbon)solid: powder or pelletLEL: not applicableUEL: not applicable50 g/m 3 (carbon black in air)>932°F (>500°C)>600°F (>315°C)>10J>45 seconds: Not classifiable as“Highly Flammable” or “Easily Ignitable”Combustible solidWater: insolubleSolvents: insolubleBlack2
as aciniform (grape-like cluster) particulate. On thecontrary, typically less than 60% of the total particlemass of soot or black carbon is composed of carbon,depending on the source and characteristics of theparticles (shape, size, and heterogeneity).In the case of commercial carbon blacks, organiccontaminants such as polycyclic aromatic hydrocarbons(PAHs) can only be extracted under veryrigorous laboratory analytical procedures (soxhletextraction using organic solvents and hightemperatures). These extracts, though they may besimilar to those derived from soot, are unique,however, because carbon black extracts exist only inextremely small quantities. Water and body fluidsare ineffective in removing PAHs from the surfaceof carbon black and, therefore, they are notconsidered to be biologically available.Two other commercial carbonaceous products oftenconfused with carbon black are activated carbonand bone black. Each is produced by processesdifferent from commercial carbon black and possessesunique physical and chemical properties.OTHER PARTICLE SIZE CHARACTERISTICSThe term “primary particle diameter” raises manyquestions when describing carbon black particle size.Because manufactured carbon black is made eitherby partial combustion or thermal decomposition ofliquid or gaseous hydrocarbons, the final product isincorrectly characterized as having exceptionallysmall particles, sometimes even described as ultrafines(particles < 0.1 micrometers in aerodynamic diameter).In fact, while the starting particle or nodule of carbonblack is extremely small (typically less than 300nanometers), a complex structure sequence rapidlyfollows within the closed reactor. The near sphericalnodules coalesce into particle aggregates thatbecome the basic indivisible entities of carbonblack. Strong electrical forces maintain the bondbetween aggregates and promote the formation ofagglomerates, which are the result of hundreds tothousands of strongly adhering aggregates. Carbonblack in commerce is encountered as agglomerates.Once formed, agglomerates do not break down tothe aggregate level. Figure 2 depicts the sequence ofstructure development, while providing typicalparticle size ranges at each stage. When carbon blackis shipped, it is normally formed into pellets tofacilitate the ease of handling and to reduce thecreation of dust. Carbon black pellets generally fallbetween 0.1 and 1.0 millimeters in size.Figure 2. Sequence of Structure DevelopmentNODULE15-300 nanometersAGGREGATE85 to 500 nanometersAGGLOMERATE1-100+ micrometers3
Page 1 and 2: I C B ACarbon Black User’s GuideS
Page 3 and 4: PurposeThis guide summarizes essent
Page 5: General InformationWHAT IS CARBON B
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Page 16 and 17: APPENDIX AMortality and Morbidity S
Page 22 and 23: ReferencesAmerican Conference of Go
Page 24 and 25: ReferencesRobertson, J., and K. Inm
Page 26 and 27: Notes______________________________
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