UAN
Encyclopedia
UAN is a solution
of urea
and ammonium nitrate in water used as a fertilizer. The combination of urea and ammonium nitrate has an extremely low critical relative humidity
(18% at 30°C) and can therefore only be used in liquid fertilizers. The most commonly used grade of these fertilizer solutions is UAN 32.0.0 (32%N) also known as UN32 or UN-32, which consists of 45% ammonium nitrate, 35% urea
and only 20% water. Other grades are UAN 28, UAN 30 and UAN 18.
The solutions are quite corrosive towards mild steel (up to 500 MPY on C1010 steel) and are therefore generally equipped with a corrosion inhibitor to protect tanks, pipelines, nozzles, etc. Urea-ammonium nitrate solutions should not be combined with calcium ammonium nitrate (CAN-17) or other solutions prepared from calcium nitrate. A thick, milky-white insoluble precipitate forms that may plug nozzles and pipelines.
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
of urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
and ammonium nitrate in water used as a fertilizer. The combination of urea and ammonium nitrate has an extremely low critical relative humidity
Critical relative humidity
The critical relative humidity of a salt is defined as the relative humidity of the surrounding atmosphere at which the material begins to absorb moisture from the atmosphere and below which it will not absorb atmospheric moisture.When the humidity of the atmosphere is equal to the critical...
(18% at 30°C) and can therefore only be used in liquid fertilizers. The most commonly used grade of these fertilizer solutions is UAN 32.0.0 (32%N) also known as UN32 or UN-32, which consists of 45% ammonium nitrate, 35% urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
and only 20% water. Other grades are UAN 28, UAN 30 and UAN 18.
The solutions are quite corrosive towards mild steel (up to 500 MPY on C1010 steel) and are therefore generally equipped with a corrosion inhibitor to protect tanks, pipelines, nozzles, etc. Urea-ammonium nitrate solutions should not be combined with calcium ammonium nitrate (CAN-17) or other solutions prepared from calcium nitrate. A thick, milky-white insoluble precipitate forms that may plug nozzles and pipelines.
Physical and Chemical Characteristics of Urea Ammonium Nitrate Solutions
The solutions contain a remarkably low amount of water and nevertheless have a low salt-out temperature:| Grade, %N: | 28 | 30 | 32 |
|---|---|---|---|
| Ammonium Nitrate (%): | 40 | 42 | 45 |
| Urea (%): | 30 | 33 | 35 |
| Water (%): | 30 | 25 | 20 |
| Specific Gravity at 16°C: | 1.283 | 1.303 | 1.320 |
| Salt-out Temperature (°C): | -18 | -10 | -2 |