Granular agricultural-grade ammonium chloride is the same salt at the same purity as the crystalline product; what is being bought is a particle size distribution. The reason that distribution is worth paying for is bulk blending — a blended fertilizer is a physical mixture, not a compound, and it stays mixed only if its components share a size distribution. This page covers blending behaviour; granule mechanical properties are covered on the compacted and hydraulic granular pages.
Substance identity
| Chemical name | Ammonium chloride |
| Synonyms | Sal ammoniac, muriate of ammonia |
| Formula | NH₄Cl |
| CAS | 12125-02-9 |
| Molar mass | 53.49 g/mol |
| Appearance | White to off-white granules, typically angular and irregular rather than spherical, since they are produced by compaction and crushing rather than by drum or pan granulation |
Specification
| Parameter | Value | Basis |
|---|---|---|
| NH₄Cl content | ≥ 94–96 % | Typical commercial range |
| Nitrogen (N) | ≥ 25.0–25.4 % | Typical commercial range |
| Moisture | ≤ 0.5–1.0 % | Typical commercial range |
| Particle size | Commonly specified as a 2–4 mm band; 1–2 mm and 3–5 mm cuts are also produced | Typical commercial cuts |
| Oversize / undersize | Both tails should be limited numerically in the specification | To be agreed |
| Bulk density | Approximately 0.9–1.05 t/m³ | Typical, approximate; confirm per lot |
Properties
Chemical properties are those of the salt and are unchanged by granulation: freely water-soluble (about 37 g per 100 g water at 20 °C), endothermic on dissolution, acidic in solution at pH 4.5–6.0 for a 5 % solution, dissociating to ammonia and hydrogen chloride on strong heating. Granulation changes only rate and mechanics. The specific surface area of a 3 mm granule is roughly an order of magnitude below that of a 0.3 mm crystal, so a granule dissolves more slowly, absorbs atmospheric moisture more slowly, and cakes less readily — the same three consequences of one geometric fact.
Applications
Direct field application by spinner or pneumatic spreader, and as the nitrogen component of bulk blends. In blending, the governing variable is not nominal size but the match between components. Particles of differing size and density separate during every subsequent transfer — augering, coning into a heap, pouring into a spreader hopper, and the spreader’s own throw. A granule that matches the urea, DAP or MOP it is blended with stays with them; one that does not produces a field where the nitrogen and the phosphate land in different places, at a nominal analysis that remains perfectly correct on the bag. Two components are commonly compared by median particle diameter and by size-distribution spread, and the practical rule is that the medians should be close and the spreads similar.
Handling and storage
Store dry. Granules resist caking better than powder but do not cake less severely once caking begins, since consolidated granular material forms hard lumps rather than soft ones. Handle blends more carefully than straight material: mixtures containing urea or ammonium nitrate have a critical relative humidity below that of either component alone, so a blend can absorb moisture in conditions in which neither ingredient would. Minimise drop heights and transfer points, both to preserve the size distribution against attrition and to control dust. Keep away from lime, cement and other alkaline materials.
Notes
A blend specification that states only nominal granule size is incomplete. Ask for the full size distribution of every component intended for the same blend, and compare them against one another rather than against a nominal figure.