Sulphur
Nobody sets out to produce sulphur.
It arrives whether the market wants it or not — the involuntary by-product of taking sulphur out of oil and gas. That one fact explains how this market behaves. The second thing to know is that the form you buy, not the purity, decides how it can be carried.
The desk
A market where supply cannot answer the price.
Almost all the sulphur in world trade is recovered, not mined. It comes out of refineries and sour gas plants because sulphur has to be removed from crude and from natural gas before the products can be sold, and the Claus units that do the removing turn it into elemental sulphur as a matter of course.
Which means the volume produced is set by how much crude is being refined and how much sour gas is being processed — not by what sulphur is worth. A refiner does not run harder because sulphur is expensive, and does not stop desulphurising because it is cheap. Production is, in the strict sense, involuntary.
The consequence is a price that moves further and faster than the underlying demand does. Sulphur has traded from a few tens of dollars a tonne to several hundred and back inside a couple of years, on demand shifts that would barely register in a market where producers could respond. If you are buying sulphur, the practical implication is that a long fixed-price contract is a real position rather than a convenience, and the pricing mechanism deserves as much attention as the specification. We will say so before we quote.
Forms
Six ways to buy the same element.
Molten sulphur leaving a Claus unit is solidified in whatever form the market wants. The chemistry is identical across all of them; the handling, the freight, the dust and the carriage classification are not.
| Form | What it is | Where it suits |
|---|---|---|
| Granular | Rounded granules built up in a drum or fluid bed, typically a few millimetres, hard and low in dust. | The workhorse of the seaborne trade. Best handling and lowest dust of the solid forms, and the usual default unless something else is specified. |
| Prilled | Formed by dropping molten sulphur through a cooling medium. Similar size to granular, generally softer with a slightly higher fines content. | Widely traded and often interchangeable with granular commercially — but not identical on friability, so the two are worth distinguishing in a contract rather than writing "granular/prilled". |
| Pastilles / hemispheres | Dropped onto a moving steel belt and solidified as flattened domes. | Very low dust and consistent size. Favoured where dust control at discharge is the binding constraint. |
| Slate / flake | Solidified as a thin layer on a chilled drum or belt, then broken. | Common in regional and containerised trade. More fines than granular, so dust and handling losses need to be priced in. |
| Crushed lump / coarse grained | Broken from bulk solidified sulphur — block or vat sulphur — rather than formed. | The cheapest solid form, and the one that changes the carriage regime. Read that section before choosing it on price. |
| Molten / liquid | Kept liquid at roughly 135–140 °C in heated tanks and heated vessels or rail cars. | Short-haul supply to an acid plant that can receive it. Avoids forming and re-melting costs entirely, and carries its own hazards — see below. |
Carriage
Formed solid is Group C. Crushed lump is Group B.
The same element, at the same purity, travels under two different schedules of the IMSBC Code depending only on how it was solidified. This is the single most consequential thing on the page and it is routinely missed at enquiry stage.
| Schedule | Group | What it means in practice |
|---|---|---|
| Sulphur (formed, solid) Granular, prilled, pastilles, slate | C — neither liquefies nor presents a chemical hazard | Carried as an ordinary dry bulk cargo. No dangerous-goods documentation, no special hold preparation beyond the usual, and a much wider set of vessels and berths available to you. |
| Sulphur, UN 1350 (crushed lump and coarse grained) | B — chemical hazard | A dangerous good. Fine sulphur dust forms explosive atmospheres and ignites easily; the cargo requires a dangerous goods declaration, controls on ignition sources, particular attention to dust during loading and discharge, and it narrows the vessel and port options considerably. |
Dust is the hazard, not the sulphur
Solid sulphur in lump form generates fines through every transfer. Those fines are what make it a Group B cargo — low ignition energy, and an explosible dust cloud in a confined space. Formed product exists precisely to keep the fines down.
Molten carries H₂S
Molten sulphur holds dissolved hydrogen sulphide, which comes out of solution in the vapour space of a tank. It is lethal at concentrations well below what a nose reliably detects, and residual H₂S content is a specification line on molten sulphur for that reason, not a footnote.
It attacks the ship
Sulphur plus moisture makes an acidic environment that corrodes steel holds and tank coatings. Hold protection, wash-down and the condition on redelivery are commercial terms in a sulphur fixture and they belong in the charterparty rather than in a conversation afterwards.
Loading
Three ways it leaves, and each one is a different quotation.
Direct into a vessel by chute, out of railway wagons into a ship at the berth, or off the terminal onto trucks. The material is the same; the handling rate, the dust exposure, the packaging cost and the documentation are not, and the route you need is worth putting in the first message rather than the third.
Into the vessel, in bulk
Formed product through a shore chute straight into the hold. The fastest rate and the lowest unit cost, and the route that needs the fewest people — but it needs a berth with the equipment and a cargo that suits bulk carriage.
Wagons to the ship, in big bags
Rail delivery to the quay, then slung out of the wagons and into the hold by the ship's crane. Slower and more expensive per tonne than bulk, and it buys dust control, part-load flexibility and a cargo that is documented as packaged goods rather than solid bulk.
Terminal to trucks
Big bags lifted from the terminal onto flatbeds for inland delivery. The route for regional supply and for buyers without rail or quay access, and the one where bag integrity on arrival matters most, because every extra handling is another chance to split a bag.
01 · Into the vessel
Formed sulphur running into a hold from a shore chute.
The stream is the argument for formed product over crushed lump. It leaves the chute as pellets and lands as pellets. Lump generates fines at every transfer, and fines are what put a cargo under the Group B schedule — with the dangerous-goods declaration, the ignition controls and the narrowed berth list that come with it.
Specification
Seven lines, and purity is the least contested of them.
Recovered sulphur is inherently pure — the Claus process produces a clean product almost regardless of the feed. So the argument is rarely about sulphur content and almost always about what came with it.
| Parameter | Typical trade basis | Why it matters |
|---|---|---|
| Sulphur purity | 99.5 % minimum, commonly 99.8–99.9 % on a dry basis | The headline. Rarely the binding constraint, because recovered sulphur meets it as produced. |
| Moisture | 0.5 % maximum is the common ceiling | Weight you pay freight on, the driver of hold corrosion, and a handling problem in cold weather. The parameter most likely to be out of line on a poorly stored cargo. |
| Acidity, as H₂SO₄ | 0.02 % maximum is typical | Free acid from oxidation during storage. It corrodes handling equipment and, in an acid plant, upsets the front end. A high figure tells you the cargo has been sitting in the open. |
| Ash | 0.05 % maximum is typical | Inorganic residue. High ash points to contamination during storage or reclaim rather than to the process. |
| Organic carbon | 0.05 % maximum is typical | Carries over from the feed and darkens the product. In sulphuric acid manufacture it fouls catalyst and colours the acid, so a technical-acid buyer holds a tighter limit than a fertiliser-acid buyer. |
| Arsenic, selenium, tellurium | Named individually where the buyer's process is sensitive | Catalyst poisons in downstream chemistry. Not every buyer needs them reported; the ones who do, need them badly, so we ask rather than assume. |
| Sizing and fines | Size distribution with a fines ceiling below a stated mesh | The parameter that decides dust at discharge, handling loss, and whether the cargo behaves like the form it was sold as. On formed product this is more useful than purity. |
Demand
Where it goes, and why fertiliser sets the tone.
Sulphuric acid for phosphate
By far the largest single use. Sulphur burns to sulphuric acid, and the acid digests phosphate rock into phosphoric acid and phosphogypsum. Roughly half of world sulphur demand ends up here, which is why the sulphur market takes its direction from the phosphate market rather than the other way round.
Metal leaching
Sulphuric acid for copper, nickel, cobalt and uranium hydrometallurgy. A growing pull, and one tied to the same battery-metal demand that shapes several other pages on this site.
Industrial chemistry
Caprolactam and other intermediates, titanium dioxide by the sulphate route, pulp and paper, and a long tail of processes that consume acid rather than sulphur as such.
Sulphur as a nutrient
Sulphur is a macronutrient in its own right — supplied either as elemental sulphur or, in combined form, as the ammonium sulphate on our nitrogen book. It is a nutrient, and decades of cleaner fuels have removed the atmospheric deposition that used to supply it. Elemental sulphur fertilisers and sulphur-bentonite pastilles serve that deficit directly — a small volume next to acid, and the part of the market with the clearest structural growth.
Rubber and specialities
Vulcanisation, agricultural fungicides, and a set of small high-specification uses where the trace-element limits above stop being optional.
What this means for your contract
An acid plant, a leach operation and a fertiliser blender want different things from the same tonne. Tell us the end use and we will write the specification around the parameters your process actually cares about instead of the ones that are conventional to quote.
Pricing
Regional benchmarks, and a curve that means something different here.
Sulphur prices off published regional assessments rather than an exchange. Which one applies follows the trade route, and the spread between them is a freight and availability story rather than a quality one.
- The references
- FOB Middle East is the export benchmark that anchors much of the seaborne trade. CFR China, CFR India and CFR Brazil are the main import assessments, and they track the phosphate and leaching demand in each. FOB Black Sea and FOB North Africa cover their regions. Name the assessment and the publication in the contract, not just the region.
- Quarterly and monthly settlements
- Large tonnages in this market have historically settled on negotiated quarterly or monthly terms rather than continuously. That convention matters: it means a spot assessment and a contract settlement can be a long way apart, and comparing one to the other is a common way to reach a wrong conclusion about whether an offer is competitive.
- Why fixed price is a position
- Because supply cannot respond, this price has a long history of doubling and halving. A twelve-month fixed price is a view on that, taken by whichever side agreed it. We would rather write an indexed mechanism with a named assessment and a stated pricing period, and tell you plainly when you are being offered a fixed number that only looks like certainty.
- What to fix
- The assessment, the publication, the pricing period, the basis (FOB or CFR), the form, and whether moisture is deducted. On sulphur, the form belongs in the price line itself — granular and crushed lump are not the same product at a discount.
Scope
Where our obligation ends.
- What we supply
- Elemental sulphur in granular, prilled, pastille, slate and crushed lump form, in cargo lots and containers, FOB or CFR, with independent inspection at load and discharge.
- Molten sulphur
- Handled only on routes where a heated receiving installation and heated transport both already exist. We do not build that chain for a single cargo, and we will say so rather than take an order we would then have to solve.
- What we do not do
- We do not operate Claus units, forming plants, terminals or vessels, and we do not manufacture sulphuric acid. We hold no equity in production.
- Carriage classification
- Established before offering, and stated in the offer. We will not present crushed lump as formed product, and we will not load a UN 1350 cargo without the dangerous-goods documentation in place.
- Origin
- Counterparty and origin screened per consignment. Recovered sulphur comes from refineries and gas plants, so its origin is a refinery's origin — and that is screened on the same basis as any other hydrocarbon-linked cargo. Where it cannot be cleared we decline at enquiry rather than at fixture, and do not refer it onward — see Compliance.
How to specify
Six lines and we can price it.
The first line is the one that decides which vessels and which berths are even available to you.
Form
Granular, prilled, pastille, slate, crushed lump or molten. Not "granular/prilled" — pick one, or state that either is acceptable and why.
End use
Acid plant, leaching, fertiliser blending, rubber or speciality chemistry. It decides which trace limits are real.
Specification ceilings
Moisture, acidity, ash, carbon, and any trace elements your process cannot tolerate. With rejection limits distinguished from penalty limits.
Sizing and fines
Size distribution and the maximum fines you can handle at discharge. This is the parameter that decides whether the cargo behaves.
Quantity, vessel and basis
Tonnes, the vessel size your berth takes, load and discharge rates, and FOB or CFR. One cargo or a term programme.
Pricing mechanism
Which assessment, which publication, the pricing period — or a fixed price, once you have decided that is what you want.
Inspection
Sampling a dusty cargo without changing it.
Independent inspection by an agency appointed for the cargo — SGS, Bureau Veritas or Intertek — instructed jointly, with sampling under supervision. Sulphur presents a particular sampling problem: the fines are not distributed like the granules, so a sample drawn carelessly reports a different cargo from the one in the hold.
- Sampling
- Mechanical or stopped-belt increment sampling to the applicable ISO procedure, with increment number and mass, division and preparation recorded. Sealed retained samples held by the inspector for the claim period. Sampling from the top of a stockpile is not sampling.
- Core analysis
- Purity, moisture, acidity as H₂SO₄, ash and organic carbon, reported on a stated basis with the moisture shown separately so wet and dry figures are never conflated.
- Sizing
- Full sieve analysis with the fines fraction reported explicitly, at load and again at discharge where handling loss is in dispute. Fines generated in transit are a real and measurable thing.
- Molten cargoes
- Temperature record throughout, and residual hydrogen sulphide determined before discharge. Vapour-space monitoring at the receiving tank is a safety procedure with its own protocol, not an inspection formality.
- Quantity and condition
- Draught survey at load and discharge with the governing survey named. Holds inspected and photographed before loading and after discharge — on this cargo, hold condition is a claim waiting to be evidenced or defended.
- Documentation per cargo
- Certificate of analysis, size analysis, moisture certificate, draught survey reports, certificate of origin, the IMSBC cargo declaration with the correct schedule and, for UN 1350 material, the dangerous goods declaration, plus bill of lading and the inspection report with photographs.
Straight answer
What we will tell you before you ask.
- That crushed lump is a dangerous good and formed sulphur is not
- Same element, same purity, two IMSBC schedules. If an offer is cheap because it is lump, the saving is usually spent on the regime that comes with it.
- That purity is not where the risk is
- Recovered sulphur is clean as produced. Moisture, acidity and fines are what go wrong, and they go wrong in storage rather than in the process.
- That a fixed price here is a position, not a comfort
- Supply cannot respond to price in this market, so it moves harder than the demand behind it. We will write you an indexed mechanism unless you have decided, knowingly, that you want the exposure.
- That molten needs a chain, not a cargo
- Heated tanks at both ends and heated transport between. If they are not already there, the answer is a formed product, and we would rather say that at the first reply.
- That the sulphur market follows phosphate
- About half of it becomes acid for phosphate fertiliser. If you want to know where sulphur is going, watch phosphate demand, not sulphur supply.
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.