Hydraulic granular ammonium chloride is produced by pressing fine crystalline material under high hydraulic pressure, without a binder, and then sizing the pressed product. The trade term denotes a route, and what it is intended to signal is a denser, harder, lower-dust granule than roll compaction yields. Whether a particular product delivers that must be established by measurement, since the name itself carries no standardised guarantee.
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 dense granules |
Specification
| Parameter | Value | Basis |
|---|---|---|
| NH₄Cl content | ≥ 94–96 % agricultural; higher for technical feed material | Typical commercial ranges; grade must be stated |
| Nitrogen (N) | ≥ 25.0–25.4 % on agricultural material | Typical commercial range |
| Moisture | ≤ 0.5–1.0 % | Typical commercial range |
| Particle size | 2–4 mm typical cut | Typical commercial range |
| Bulk density | Approximately 1.0 t/m³ or above | Typical, approximate; confirm per lot |
| True crystal density | 1.53 g/cm³ | Physical constant — this is the ceiling a granule approaches, never reaches |
| Crush strength | Specify a measured minimum and a test method | To be agreed |
| Binder | None | Bonding by plastic deformation under pressure |
Properties
The salt’s chemistry is unaltered: freely soluble at approximately 37 g per 100 g water at 20 °C and 77 g at 100 °C; endothermic dissolution at about +14.8 kJ/mol; 5 % solution pH 4.5–6.0 at 25 °C; dissociation to NH₃ and HCl on heating with apparent sublimation near 337.6 °C; critical relative humidity around 77 % at 30 °C.
The interesting property is the porosity that pressing removes. Bulk density is a composite of the granule’s own density and the void fraction between granules; a higher-pressure route raises the first by closing internal pores. Fewer internal pores mean less internal surface available to atmospheric moisture and less capillary structure to draw water in, which is why a densely pressed granule takes up water more slowly than a lightly bonded one of the same external size. The equilibrium is unchanged — at humidity above the critical relative humidity, the material will still take up water; it simply takes longer to get there. That difference is exactly what a long, humid supply chain converts into arriving in good or poor condition.
Applications
Suited to material that must survive extended storage, sea transport, repeated transhipment and mechanical handling. Denser granules give longer spreader throw and more consistent flight, so they support wider working widths. In industrial and technical applications the same hardness serves a different end: it allows metered mechanical feeding without excessive dust generation.
Handling and storage
Dry, sealed storage remains necessary — hardness delays moisture uptake, it does not prevent it. Density is an advantage in transport and a consideration in storage: dense material imposes higher loads on floors, silos and stacked packaging than a lighter product of the same volume, and bottom-of-stack consolidation drives caking. Keep away from alkaline materials. Protect copper alloys, mild steel, galvanised steel and aluminium from contact in humid conditions; chloride also raises pitting risk on austenitic stainless steel.
Notes
Ask for measured values. “Hydraulic granular” is a description of how the product was made, and two producers using the term can deliver materially different granules. A specification built on measured bulk density, crush strength, dust fraction and size distribution is verifiable on arrival; one built on a process name is not.