This product pairs the lowest-cost ammonium sulphate feed — coke-oven crystal from steel-industry gas cleaning — with the most demanding compaction method. The logic is straightforward: coke-oven crystal is fine and dusty, which is exactly the fault that high-pressure compaction addresses most effectively, and the resulting granule handles a long supply chain far better than the crystal it came from.
Substance identity
Ammonium sulfate · (NH₄)₂SO₄ · CAS 7783-20-2 · PubChem CID 6097028 · 132.14 g/mol · dense angular granules, 2–4 mm, grey to brown.
Specification
— typical commercial ranges
| Parameter | Typical range | Note |
|---|---|---|
| Total nitrogen (N) | 20.5 – 21.0 % min | inherits the feed guarantee |
| Sulfur (S) | 23 – 24 % | |
| Moisture (H₂O) | ≤ 0.5 % | |
| Free acid (as H₂SO₄) | ≤ 0.10 – 0.20 % | inherited; compaction does not reduce it |
| Water-insoluble matter | inherited from feed | not reduced by compaction |
| Particle size, 2 – 4 mm | ≥ 90 % | |
| Crushing strength | ≥ 3 kgf reported for this form | verify on the delivered lot |
| Colour | grey to brown | inherited |
Properties
The physical improvement over coke-oven crystal is the largest of any product in this range, because the starting point is the worst: dust falls from a persistent nuisance to a minor one, bulk density rises from roughly 0.95–1.05 to 1.0–1.1 t/m³, effective spread width from a spinning disc goes from narrow and drift-prone to comparable with other granular fertilisers, and caking under stack load largely disappears.
What is inherited is unchanged: free acidity, water-insoluble matter, iron, residual organics from tar and oil, and colour. Damp product remains mildly corrosive to unprotected mild steel. The product remains unsuitable for fertigation, drip systems, spray-water conditioning and colour-specified applications.
Applications
Field-scale bulk blending and mechanical broadcast application where cost per unit of nitrogen and sulfur governs and where the supply chain is long enough that granule strength earns its keep — import trade with multiple transfers being the typical case. Agronomically it is a straight N+S source with the same behaviour as any ammonium sulphate: ammonium retained on exchange sites then nitrified, sulfate immediately plant-available, and a strongly acidifying net effect.
Handling and storage
Dry, covered storage; away from strong alkalis. Keep handling equipment dry and clean out after use because of the inherited free acidity. Dust control requirements are much lighter than for the crystal feed but should not be dropped entirely — the fines that do form are the same fine coke-oven crystal.
Notes
When this product and a hydraulic granular from caprolactam feed are offered against the same size and strength specification, the difference is entirely in the inherited parameters. Compare free acid, insolubles and colour, and match the choice to the end use rather than to the granule specification.