There is no single table that describes every commercial granular sulfur product worldwide. Producers can work to different specifications, and end users can require different acceptance limits.
The table below has a narrower purpose: it describes the current documented supply range available through Coolak International Group.
Parameter | Unit | Current Coolak Supply Range |
Sulfur (S) | % | 99.5–99.98 |
Colour | — | Bright yellow |
Moisture | % | ≤ 0.5 |
Ash | % | ≤ 0.05 |
Acidity, as H₂SO₄ | % | ≤ 0.05 |
Organic matter / hydrocarbons | % | ≤ 0.02 |
Packaging | — | Bulk or jumbo bags, subject to order and transport requirements |
These values are not presented as a universal industry standard. They describe the current sulfur product supply data published by Coolak International Group. Final specifications are to be confirmed against the COA for the relevant shipment and fixed in the contract.
Current product information is available on the Granular & Micronized Sulphur product page.
Parameters That Matter on a Sulfur COA
Sulfur content: The S percentage indicates how much of the tested sample is elemental sulfur. A higher number is not automatically the correct choice for every process; the buyer’s technical requirement should define the acceptable limit.
Moisture: Moisture affects delivered mass, storage behaviour and material handling. The contract should define the limit and, where relevant, the test basis.
Ash: Ash represents non-combustible residue under the applicable test procedure. It can matter where a process needs tighter control of mineral impurities.
Acidity: Acidity may be reported on a defined basis such as H₂SO₄. Buyers comparing two specifications should confirm that the units and reporting basis are equivalent.
Organic matter or hydrocarbons: These may be controlled in recovered sulfur, especially when downstream processing is sensitive to contamination.
Particle-size distribution: A notation such as “2–6 mm” is more useful when accompanied by the percentage within that range and acceptable limits for oversize particles and fines. The same nominal size range can describe products with noticeably different distributions.
Matching the Specification to the End Use
A useful specification connects each limit to the buyer’s process. A facility with a particular conveyor, pneumatic transfer system or discharge arrangement may place more emphasis on particle-size distribution and fines. A chemical process may place more emphasis on sulfur content and impurities.
This is why commercial labels such as “premium grade” or “export grade” should not replace numerical specifications. Those expressions can describe market positioning, but they do not tell a plant engineer what the cargo will contain or how it will behave.
Five Checks Before Technical Acceptance
Confirm that the physical form matches the purchase requirement: granular, prilled, lump or micronized.
Compare sulfur content and impurity limits directly with the contractual specification.
Confirm that the COA refers to the relevant shipment or batch rather than only to a generic historical sample.
Specify particle-size distribution and fines limits when they matter to the receiving equipment.
Match packaging, SDS information and transport classification to the actual physical form being shipped.
These checks do not replace inspection or contractual quality control. They reduce the risk of treating one headline purity figure as a complete technical definition.
Granular vs Prilled vs Lump Sulfur
The main distinction between these sulfur forms is physical structure and forming method, not an automatic difference in chemical purity.
Form | General Physical Character | Practical Consideration |
Granular sulfur | Formed, relatively dense and regular particles | Suitable for many bulk-handling systems |
Prilled sulfur | Small particles formed by cooling individual droplets | Size and mechanical strength depend on the prilling process |
Lump sulfur | Irregular solid pieces with a wider size range | Breakage during handling can create additional fines |
Powder / micronized sulfur | Very fine particles with high surface area | Useful where faster reaction is required, with greater dust-control needs |
A buyer should therefore avoid assuming that “granular” automatically means higher purity or that “prilled” automatically means lower quality. The correct form depends on the process, storage system, reaction requirements, loading method and specification.
Prilled Sulfur vs Granular Sulfur
Prilling generally forms individual droplets that solidify during cooling. Granulation can build a particle progressively by adding and solidifying layers of sulfur around a seed.
Those process differences can affect particle properties, but buyers should focus on measurable results rather than the process name alone. Particle strength, size distribution, fines and handling behaviour should be checked against the producer’s data or the shipment specification.
Lump Sulfur vs Granular Sulfur
Lump sulfur consists of irregular pieces and can have a broad particle-size range. Repeated mechanical handling can break pieces and increase the amount of fines.
Granular material can offer more predictable handling in many mechanized systems, but “granular” should not be interpreted as “dust-free.” Abrasion, drops, conveyor transfer points and repeated handling can still create sulfur fines. Sound material handling therefore still requires dust management, housekeeping and appropriate control of ignition sources.
Granular Sulfur Packaging, Storage and Transport Classification
There is no single universal bag weight for granular sulfur. Packaging should be selected around order volume, handling equipment, mode of transport, warehouse conditions and the receiving facility.
Coolak International Group currently documents bulk and jumbo-bag supply for its sulfur product. The exact bag weight and packing configuration should be confirmed for the individual order rather than assumed from a generic market convention.
Storage planning should address product contamination, moisture exposure, generation of fines and dust, and potential ignition hazards associated with combustible fine particles. Good housekeeping is particularly relevant at transfer points where particles can be abraded.
Is Granular Sulfur Non-Dangerous Goods?
The most accurate answer is conditional.
Sulfur appears under UN 1350 in dangerous-goods regulations. However, Special Provision 242 creates a specific exemption for sulfur that has been formed into defined shapes.
Under ADR, sulfur is not subject to ADR requirements when it has been formed into shapes such as prills, granules, pellets, pastilles or flakes. The IMDG provisions contain a comparable exemption for sulfur formed into specific shapes.
This is why a blanket statement such as “granular sulfur is always Non-DG” is too broad. A more accurate commercial description is that formed granular sulfur may fall under the Special Provision 242 exemption, subject to the applicable regulation and the actual cargo form.
Before shipment, parties should still verify the product SDS, physical form, transport mode, carrier requirements, port rules and any jurisdiction-specific requirements. Transport classification should follow the shipment documentation, not a marketing description.
Main Industrial and Agricultural Uses of Granular Sulfur
Sulfur’s largest industrial role is closely connected to sulfuric acid production. USGS identifies sulfuric acid manufacture as the major end use for sulfur, with sulfuric acid itself feeding fertilizer production and many other industrial processes.
Sulfuric Acid Production
For sulfuric acid plants, the relevant sulfur feed specification depends on the plant and its operating requirements. Sulfur content, ash, moisture and other impurities can all form part of procurement criteria.
Calling a product “suitable for sulfuric acid” is therefore only a first screening statement. The plant’s feed specification remains the controlling technical reference.
Fertilizers and Agriculture
Sulfur has two distinct agricultural roles. It is an essential plant nutrient, and sulfur compounds are important in fertilizer manufacturing. Elemental sulfur can also be used as a soil amendment under appropriate conditions.
Sulfur-oxidizing microorganisms convert elemental sulfur over time, a process that can contribute to soil acidification. The result, however, depends strongly on soil conditions. Soil type, initial pH, temperature, moisture, microbial activity and carbonate content all affect the response.
Colorado State University Extension notes that elemental sulfur can lower soil pH in suitable soils, but that major pH reduction may be impractical in soils containing substantial free lime. The reaction can also take months rather than occurring immediately.
For this reason, granular sulfur should not be described as a guaranteed method for reducing soil pH or increasing crop yield. Agricultural use should be based on soil testing, agronomic requirements and the appropriate sulfur form.
Rubber Vulcanization
Sulfur is used in rubber vulcanization to create cross-links within polymer structures. This changes the mechanical properties of the rubber and is central to many rubber manufacturing processes.
The preferred sulfur form for rubber processing may differ from the form selected for high-volume bulk handling. Fine or specifically formulated sulfur products can be required where dispersion and reaction behaviour are critical.
Chemical and Mineral Processing
Sulfur and sulfur-derived chemicals participate in many chemical and mineral-processing chains. Here again, the product name is only the starting point. Buyers should work backward from the consuming process to define the required purity, impurity limits, particle form and handling characteristics.
Turn a Product Name into a Purchasable Specification
A sound granular sulfur purchase decision goes beyond asking, “What is the purity?” Sulfur content, moisture, ash, acidity, organic matter, particle-size distribution, fines, packaging and quality documentation can all influence acceptance.
Coolak International Group currently offers industrial sulfur in granular and micronized forms within its documented supply specification. Those figures define an available supply range; they do not replace the buyer’s technical standard. The shipment COA and agreed contractual specification remain the final quality references.
To review the current documented supply parameters or request product specifications, see Granular & Micronized Sulphur from Coolak International Group.
