Carbon black feedstock
You are not buying oil. You are buying the carbon that survives the reactor.
FCC decant and clarified slurry oil, ethylene cracker tar, coal tar and anthracene oil, and blends we declare as blends — supplied as heated parcels and quoted on BMCI, asphaltenes, catalyst fines and the metals that decide how long your reactor runs between shutdowns.
The desk
BMCI sets the price. Everything else sets the risk.
Carbon black producers buy feedstock on the Bureau of Mines Correlation Index because it correlates with aromaticity, and aromaticity is how much carbon stays behind when the rest of the molecule burns. It is the one number that maps to yield, so it is the number that maps to money.
It is also the only number most offers contain, which is where the trouble starts. BMCI tells you what a feed is worth if the reactor runs. It tells you nothing about whether the reactor will run — that is decided by catalyst fines, by asphaltenes, by sodium and potassium, and by insolubles that coke the preheater and score the nozzle. A parcel can carry the best index on the table and still be the most expensive cargo you buy this year.
So we quote BMCI with the distillation and density it was calculated from, and we put the fouling parameters on the same page rather than in an appendix. If a cargo is strong on index and weak somewhere that matters to your reactor, you will hear it from us before you hear it from your maintenance schedule.
The index
BMCI is calculated, not measured.
Worth stating plainly, because it changes what a certificate has to show. Nobody puts a sample in a machine and reads off a BMCI. It is derived from two things you can measure — how heavy the oil is and where it boils.
where SG is specific gravity and T is the mean boiling point in kelvin, taken as 273 + (T10 + T30 + T50 + T70 + T90) / 5, from the high-temperature simulated distillation curve in degrees Celsius.
| What follows from that | Why it matters commercially |
|---|---|
| A BMCI figure with no distillation curve and no density behind it is unauditable. | You cannot recompute it, so you cannot dispute it. We publish the inputs on the certificate as a matter of course, and we treat an index quoted bare as an incomplete offer rather than a competitive one. |
| Two parcels can share a BMCI and behave differently. | The index compresses a whole distillation curve into one number. A heavy tail and a light one can average to the same place and coke very differently. |
| Typical carbon black feedstock specifications call for BMCI above about 132. | Clarified slurry oil as produced commonly sits in the 110–130 band, frequently below 126. A large share of what is offered into this market as "CBFS" is therefore below the target and needs upgrading or blending to reach it — which is a fact about the market, not a defect in any one cargo. |
| Raising BMCI is a real operation with a real cost. | When someone offers an on-spec index at an off-spec price, the question is what was blended in to get there and what it did to the rest of the specification. |
Routes
Four ways to fill the same tank.
FCC decant oil and clarified slurry oil
Our primary stream and the market's. Bottoms from the fluid catalytic cracker's main fractionator, held to let entrained catalyst settle before the clarified oil is drawn off — which is exactly where the grade's characteristic problem comes from.
Catalyst fines are the parameter that separates a professional offer from an amateur one. Whatever settling does not remove stays in the oil as hard alumina-silica particles. They report as ash and as aluminium and silicon on a metals scan, and in a reactor they behave like a slow abrasive on every pump, valve and atomising nozzle the feed passes through. A decant cargo is bought on BMCI and rejected on fines.
Sulphur follows the refinery's crude slate rather than the unit, so it varies by origin more than by grade, and it reports through into the finished black and into the plant's stack. Aromaticity is good but rarely outstanding: this is the route that most often needs help to reach a target index.
- Where the specification usually lands
- Asphaltenes to a maximum around 6 % by weight, sulphur commonly capped near 3 %, specific gravity up to about 1.10 at 15 °C, with BMCI as the headline. Every buyer's table differs; these are the shapes, not the terms.
- What we insist on reporting
- Ash, plus aluminium and silicon explicitly. A metals scan that omits Al and Si on a decant cargo is not a metals scan.
- Availability
- Multi-origin. Refinery-specific historical assay tables are released to qualified buyers through the Technical Library rather than published, because an assay implies a standing offer and dates the moment a unit changes crude.
Ethylene cracker tar (pyrolysis fuel oil)
The heavy bottom from a steam cracker's quench system. Highly aromatic by construction — the cracking severity that makes ethylene also condenses ring structures — so this route usually carries the higher index of the two petroleum streams, and usually carries less sulphur.
The trade-offs are availability and stability. Availability is set by the cracker's own feed: a naphtha or gasoil cracker produces meaningful tar, an ethane cracker produces very little, so regional supply follows petrochemical economics rather than refining economics and can disappear for reasons that have nothing to do with carbon black.
Stability is the operational catch. Cracker tar can carry reactive olefinic and styrenic species that continue to polymerise in storage, so viscosity climbs and gums form over time. A parcel that was fluid at load can be a problem at discharge if it has sat warm for weeks. That makes storage history a specification question on this route, not a logistics footnote.
- Strengths
- High aromaticity, generally low sulphur, and a clean metals profile compared with a decant cargo — no catalyst fines, because there is no catalyst.
- Watch items
- Sodium and potassium, which act as structure modifiers in the reactor and attack refractory; storage stability and viscosity growth; and batch-to-batch variability driven by the cracker's feed slate.
- What we ask the producer
- Age of the parcel, storage temperature, and whether it has been inhibited. Where we cannot get that history we say so instead of presenting the parcel as fresh.
Coal tar and anthracene oil
The coal-derived route: tar from coke ovens and the anthracene fraction distilled from it. The most aromatic material of the four and therefore the strongest on yield — which is why it persists despite everything below.
What it brings with it is insolubles. Quinoline insolubles and toluene insolubles — the primary QI being fine carbonaceous carryover from the coke oven itself — are not impurities in the ordinary sense; they are solid carbon that never atomises, and they build in the preheater and on the nozzle. QI and TI belong on the specification for this route the way catalyst fines belong on a decant specification. Nitrogen also runs higher, which follows through to the plant's emissions.
The route also sits in a different legal and operational world from the petroleum streams, in two ways that are easy to miss until they cost money. Under CLP it is assessed against a coal-derived note keyed to benzo[a]pyrene rather than the petroleum note keyed to DMSO extract, and under IMO rules it is a chemical tanker cargo rather than an oil cargo. Both are covered below.
- Strength
- Highest aromaticity and the best index of the four routes.
- Specify or regret
- Quinoline insolubles and toluene insolubles, both with ceilings. Also nitrogen, ash and water.
- Different ship
- Coal tar is an IBC Code cargo — see carriage. If your enquiry assumed a product tanker, this route changes the freight before it changes anything else.
- Different paperwork
- See PAH, CLP and REACH. The classification logic is not the same as for the petroleum routes, and an SDS copied across from one to the other is wrong.
Declared blends and multi-origin supply
Blending is how most cargoes reach a target index, and there is nothing wrong with it. What is wrong is presenting the result as a single-origin stream, because the buyer then plans a reactor around a consistency that does not exist.
Our rule is simple and it is the reason this block exists on the page: if a parcel is blended, the offer says so and names the components and their proportions. A blend you know about is a specification. A blend you find out about is a claim.
Blending also has a technical failure mode worth naming. Aromatic streams hold asphaltenes in solution; introduce something more paraffinic to correct a density or a viscosity and the asphaltenes can drop out — in the tank, in the line, or in the preheater. Compatibility is checked before components are combined, not assumed because both numbers looked right on paper.
- What a blended offer carries
- Components, proportions, the resulting BMCI with its underlying distillation and density, and the full fouling parameter set on the blend as blended — not the weighted average of the components' certificates.
- Consistency across liftings
- On a term programme, whether the recipe is fixed or whether components may substitute. If it may vary, that is stated at contract rather than discovered at the third lifting.
- What we will not do
- Blend to a number and let the origin field say something simpler than the truth.
The parameters
What each one does inside the plant.
A CBFS specification is short. Almost every line on it is there because someone's reactor once stopped. This is which line, and why.
| Parameter | What it governs | Route where it bites hardest |
|---|---|---|
| BMCI | Yield — carbon retained per tonne of feed, and therefore the economics of the whole purchase. | All four. The headline everywhere. |
| Ash, aluminium, silicon | Catalyst fines. Abrasive wear on pumps, valves and atomising nozzles; the classic cause of unplanned nozzle changes. | Decant and clarified slurry oil. |
| Asphaltenes (n-heptane insolubles) | Coking in the preheater and on the nozzle tip; incomplete atomisation; grit in the product. | Decant oil and coal tar; the constraint on blending. |
| Quinoline and toluene insolubles | Solid carbon that never atomises. Preheater and nozzle fouling, and grit carried into the black. | Coal tar and anthracene oil. |
| Sodium and potassium | Structure modifiers — they change the aggregate structure of the black itself — and they attack reactor refractory. | Ethylene tar especially; watched everywhere. |
| Sulphur | Reports into the finished carbon black and into the plant's stack. A product constraint and an emissions constraint at once. | Decant oil, following the crude slate. |
| Nitrogen | Emissions, and effects on product properties. | Coal tar route. |
| Water and sediment | You pay freight on water, and water entering a hot reactor flashes. A safety parameter, not only a commercial one. | All four; worst after a wet voyage or a poorly drained tank. |
| Viscosity and pour point | Whether the parcel can be pumped and atomised at the temperature your plant actually runs, and how much heating the voyage needs. | All four; acute on cracker tar that has aged. |
| Distillation profile | Half the BMCI calculation, and separately the heavy tail that decides coking behaviour. | All four. |
Downstream
What the feed becomes, and why the buyer is fussy.
Context rather than a service we offer — but it explains why a carbon black plant argues about sodium at parts per million when the cargo is priced in dollars per tonne.
Roughly 73 % of virgin carbon black goes into tyres, and over 90 % into rubber products generally — tread, sidewall, belts, hoses. The rest is pigment and conductive applications. In the oil furnace process the feedstock is atomised into a hot combustion gas stream, cracked, and quenched; the grade produced is set by reactor conditions, but the feedstock decides how much comes out and how clean it is.
Grades are classified under ASTM D1765, where the leading N marks the normal-curing furnace blacks that dominate the market and the digits track particle size class. Smaller particles mean more surface area, more reinforcement and more abrasion resistance — and a higher price.
| Grade family | Particle size | Typical use |
|---|---|---|
| N110–N121 (SAF) | 15–20 nm | Highest reinforcement — demanding tread compounds |
| N220–N234 (ISAF) | 20–25 nm | Tread |
| N330 (HAF) | 28–36 nm | The general-purpose workhorse |
| N550 (FEF) | 40–48 nm | Carcass, sidewall, extrusions |
| N660 (GPF) | 49–60 nm | General purpose, lower reinforcement |
| N762–N990 | 100–500 nm | Thermal blacks — low reinforcement, high loading |
Health & regulation
The polycyclic aromatics are the product, not the contaminant.
This is the section most CBFS offers leave out, and the one a serious buyer's HSE function asks about first. The value of the feed and its hazard profile come from the same molecules, so they cannot be separated by better refining.
| Instrument | What it says | What it means for CBFS |
|---|---|---|
| CLP Annex VI, Note L (petroleum-derived streams) | The carcinogen classification need not apply if the substance contains less than 3 % DMSO extract, measured by IP 346. | A genuine carbon black feedstock will not pass that test — the DMSO extract is measuring precisely the polycyclic aromatics the buyer is paying for. So the classification stands and the cargo is labelled accordingly. An offer of CBFS accompanied by a safety data sheet showing no carcinogenicity classification has either mis-specified the product or mis-run the test, and we treat it as a red flag rather than a bargain. |
| CLP Annex VI, Note M (coal-derived streams) | Classification is not required if benzo[a]pyrene is below 0.005 % w/w. | The coal tar route is assessed on this threshold instead. Different note, different test, different documentation — an SDS copied from a petroleum cargo onto a coal tar cargo is simply the wrong document. |
| Notes N and P | Note N: classification may be waived where the full refining history is known and the parent substance is not a carcinogen. Note P: classification not required where benzene is below 0.1 % w/w. | Relevant to how a specific registered substance is classified. Which note applies follows the substance identity on the registration, not the commercial product name on the invoice. |
| REACH Annex XVII, entry 50 | Restricts extender oils placed on the market for tyre manufacture to 1 mg/kg benzo[a]pyrene or 10 mg/kg total of eight listed PAHs; and consumer articles with rubber or plastic parts in skin contact to 1 mg/kg of any listed PAH. | This does not restrict carbon black feedstock. Entry 50 governs extender and process oils — the reason the industry moved from DAE to TDAE — and finished articles. CBFS is neither. The confusion comes up in nearly every first conversation with a new buyer's compliance team, and clearing it early saves a fortnight. |
Carriage
Same product name. Two entirely different ships.
The route does not merely change the specification. On the coal tar side it changes what may legally carry the cargo, which is worth establishing before a freight indication rather than after.
| Item | Position |
|---|---|
| Petroleum routes (decant, slurry, cracker tar) | Carried as an oil cargo. Carbon black feedstock does not appear in chapter 17 of the IBC Code. Heated parcel tankers and, for smaller lots, heated ISO tank containers. |
| Coal tar route | Coal tar is listed in IBC Code chapter 17: pollution category X, ship type 2, tank type 2G. That is a chemical tanker with the corresponding certification, not a standard product tanker — and category X carries the strictest discharge and prewash regime. Coal tar pitch (molten) sits alongside it at ship type 2, tank type 1G. |
| Heating | These are viscous, high-pour cargoes. Loading, voyage and discharge temperatures are agreed in advance and recorded — not left to the vessel — because viscosity climbs steeply as the parcel cools and a cargo that cannot be pumped at the receiving terminal is a demurrage problem before it is a quality problem. |
| Tank history | Previous cargo matters more here than on most products. A paraffinic residue in an otherwise clean tank can destabilise an aromatic parcel and drop asphaltenes. Three-cargo history is requested as standard. |
| Quantity and sampling | Shore tank figures and vessel figures both recorded, with sampling under independent supervision at a point agreed before arrival. Temperature at each sampling point recorded with the sample. |
Scope
We supply the feed. Your reactor decides the yield.
One boundary on this page matters more than the others, and it is the one most often blurred in this market.
- We will not warrant a yield figure
- Yield is a property of your reactor, your combustion air, your quench and your target grade as much as it is a property of our oil. We will give you the index and the full parameter set that feed your own yield model, and we will discuss what a stream has historically achieved elsewhere. We will not put a percentage in a contract that our cargo cannot control, and an offer that does should be read carefully.
- What we do
- Source and supply CBFS across the four routes as heated seaborne parcels and ISO tanks — FOB, CFR, CIF or delivered to a nominated terminal — with independent inspection, the full certificate, and the specification argued out before the fixture.
- What we do not do
- We do not operate carbon black plants, reactors or blending terminals. We do not upgrade or hydrotreat feedstock. We do not supply carbon black itself — the finished black is our customer's product, not ours.
- Permits and classification
- Import registration, REACH representation where required, and site permitting are the buyer's. We will name what we know to be required and will not quote around a restriction we can see.
How to specify
Six lines and we can price it properly.
Most CBFS enquiries arrive as a BMCI and a tonnage. These six turn that into an offer.
Target BMCI, and whether it is a floor
A minimum, or a window. And confirm you want the distillation and density behind it on the certificate — we will send them either way.
Which routes you will accept
Petroleum only, or is cracker tar and coal tar in play? This decides the freight, the paperwork and half the specification.
Fouling ceilings
Ash, aluminium and silicon for decant; asphaltenes; QI and TI if coal tar is admitted. The lines that protect the nozzle.
Sodium and potassium, sulphur, nitrogen
Metals as ppm ceilings, sulphur as a maximum. Say if sulphur is bound by your stack permit rather than by product quality — it changes what we look for.
Heating and discharge temperature
The temperature your terminal can receive at, your tank heating, and the viscosity your pumps will accept. Parcel size and basis with it.
Single origin or blend
Whether a declared blend is acceptable at all, and if so whether the recipe must hold across liftings.
Quality
The certificate has to show its working.
Because the headline number is calculated rather than measured, a CBFS certificate that reports only the result is not a certificate a buyer can rely on. Ours reports the inputs alongside it, so the index can be recomputed by anyone who cares to.
Inspection is by an independent agency appointed for the cargo — SGS, Bureau Veritas or Intertek — instructed jointly, sampling under supervision at a point both sides agreed in advance, with the temperature recorded at every sampling point because on a heated cargo it changes what the sample is.
- Core test set
- Density at 15 °C; high-temperature simulated distillation reported as a full curve, not a single point; BMCI calculated and shown with its inputs; sulphur; asphaltenes as n-heptane insolubles; ash; water and sediment; kinematic viscosity at two temperatures; flash point; and a metals scan.
- Metals scan
- Sodium, potassium, aluminium, silicon, vanadium, nickel, iron and calcium as a minimum. Aluminium and silicon are not optional on a decant cargo.
- Route-specific additions
- Quinoline and toluene insolubles on coal tar and anthracene oil. Storage age, storage temperature and any inhibitor treatment on cracker tar. Blend components and proportions on a declared blend.
- Health documentation
- Safety data sheet in the destination language, REACH registration position for the substance identity supplied, and IP 346 or PAH data where the buyer's compliance work calls for it.
- Retained samples
- Sealed retains held against the parcel, so a later dispute is settled on the oil rather than on correspondence.
- Documentation per parcel
- Certificate of Quality, Certificate of Analysis, Certificate of Quantity, Certificate of Origin, safety data sheet, bill of lading, three-cargo tank history and the independent inspection report.
Straight answer
What we will tell you before you ask.
- That we will not warrant your yield
- We will give you every number your yield model needs and the history of the stream. The percentage that comes out of your reactor is yours, and anyone who contracts it is selling you something they do not control.
- That a bare BMCI is not a specification
- Without the distillation curve and the density it was calculated from, the index cannot be checked and cannot be disputed. We send the inputs as standard and we read a bare index in someone else's offer as a question, not an answer.
- That decant oil is rejected on fines, not on index
- Ash, aluminium and silicon are the parameters that decide whether a clarified oil cargo damages your plant. They belong on the enquiry, not on the post-mortem.
- That a blend is declared as a blend
- Components and proportions on the offer. If the recipe may change across liftings on a term deal, that is written into the contract rather than discovered later.
- That a clean carcinogenicity SDS is a warning sign
- Real CBFS does not pass the IP 346 threshold, because the polycyclic aromatics are what you are buying. A document saying otherwise means something is wrong with the product or with the testing — and it is your compliance exposure, not just ours.
- Where an origin cannot be cleared
- Heavy aromatic streams come from a small number of refineries and crackers, several in jurisdictions requiring careful screening. Origin and counterparty are screened per consignment before we quote, and where it cannot be cleared we decline rather than structure around it — see Compliance.
Enquiries
Every enquiry is answered by the desk that handles it.
Send the product, quantity, delivery basis, destination and timing. We revert with availability, an indication and the documentation that accompanies it. Specifications are released once we know who we are speaking with.