Ammonium sulphate: Characteristics
Granular or crystal, white or off-white
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.AS is sold on nitrogen and sulphur content and physical form. Granular AS (2-4 mm) blends with NPK and earns a premium; standard crystal is cheaper and used straight or in compound plants. Colour (white to off-white) and free acid matter for blends. By-product grades are checked for heavy metals and organics.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Nutrient content | 21% N and 24% S (pure); India FCO minimum 20.6% N (indicative) | value per unit N and S | stoichiometry; FCO (indicative) |
| Granule size | standard crystal under about 1 mm; granular 2-4 mm (indicative) | blending and spreading | indicative |
| Moisture | under about 1% (indicative) | caking | indicative |
| Free acid | under about 0.05% as H2SO4 (indicative) | corrosion and blend stability | indicative |
Commercial grades
- Caprolactam-grade crystal (benchmark grade)
- Standard and steel-grade (coke-oven) crystal
- Granular and compacted AS
- Food grade (E517)
- Technical grade for water treatment