Granular Sulphur Specifications Explained

“Granular sulphur, 99.9%” is not a complete specification. A buyer and seller can agree on nominal purity and still disagree on moisture, ash, acidity, organic matter, hydrogen sulphide, chloride, granule distribution, fines, packing, or test method.

Product form comes first

The Sulphur Institute distinguishes formed solid sulphur, including granules, prills, pellets, pastilles, and flakes, from lump, coarse-grained, liquid, and other forms. A request for granular product should not be answered with lump sulphur or a fertilizer product containing elemental sulphur unless the buyer explicitly permits it.

The common chemistry fields

• Purity: State whether the limit is on a dry basis and how it is calculated or measured.
• Moisture: This affects net dry product and can affect handling. State the maximum and test method.
• Ash: Non-combustible residue. The numerical limit is meaningless without its unit.
• Organic matter: A separate impurity field in many producer data sheets.
• Acidity as H₂SO₄: State the unit, maximum, and test method.
• Hydrogen sulphide and chloride: Include them when the end use or producer specification requires them.

Producer specifications differ. QatarEnergy’s Ras Laffan and QAPCO data sheets, for example, do not use identical limits across every field. They prove why a market phrase such as “standard spec” is inadequate. They do not establish the specification of another origin or lot.

Physical specification matters

Granule size distribution affects dust, degradation, handling, storage, conveying, and end use. A good requirement states the sieve range, the percentage inside that range, the allowed oversize and fines, and the test method.

“Low dust” or “free flowing” is not measurable unless the parties define an acceptance test. The same applies to colour, hardness, friability, caking, and contamination.

Bulk and FIBC are different commercial products

Bulk cargo requires vessel, hold, terminal, handling, contamination, and discharge planning. FIBC or jumbo-bag cargo adds bag material, net weight, pallet or sling method, markings, container or breakbulk plan, and bag integrity.

The packing basis must appear in the price and quantity. A bulk indication cannot be compared directly with a bagged delivered price by subtracting an assumed packing cost.

A generic sheet is not a lot COA

A technical data sheet describes a product specification or typical range. A certificate of analysis should identify the tested lot, date, laboratory or inspector, methods, and results. Neither document proves title, seller authority, current availability, or terminal access.

For qualification, GMC separates four items:

1. buyer-required specification;
2. seller’s product specification;
3. recent lot-linked analysis;
4. contract inspection and rejection terms.

The trade advances only when those four layers are compatible and attributable to the proposed transaction.

What purity should a buyer request?

There is no single number that fits every plant. The buyer should state its minimum, basis and test method. A seller should answer with its product specification and recent lot evidence, not replace the requirement with the phrase “international standard.”

How should moisture be handled commercially?

State the maximum moisture, test method and whether settlement uses gross weight or a dry-product adjustment. The contract should also define the inspection point and which result controls acceptance.

The one-page compatibility check

Put the buyer requirement and seller specification in adjacent columns. Mark exact matches, tolerances and open items. Then attach the lot COA and contract inspection clause as separate evidence. The commodity due-diligence checklist covers the identity and authority checks that the chemistry table cannot answer.

Sources and review record

These are the primary or authoritative sources used for this explainer. Listing a source does not imply endorsement of GMC.

1. Ras Laffan Granulated Sulphur Technical Data Sheet QatarEnergy · reviewed August 26, 2026
2. QAPCO Sulphur Standard Specification QatarEnergy · reviewed August 26, 2026
3. Sulphur glossary The Sulphur Institute · reviewed August 26, 2026