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urea bulk density

Urea – whether used as a high nitrogen fertilizer, industrial production raw material, or a component of diesel exhaust fluid (DEF) – is typically transported and stored in bulk form. At each stage of this process, a key but often overlooked parameter is the urea bulk density (kg/m ³). This indicator determines the amount of urea that can be accommodated per unit volume, directly affecting storage capacity, transportation costs, and even application efficiency.

What is the bulk density?

Bulk density refers to the mass per unit volume of granular or powdery material, measured in kilograms per cubic meter (kg/m ³) or pounds per cubic foot (lb/ft ³).

For urea, it specifically refers to the degree of tightness of the accumulation of urea particles (granular urea) in bulk storage (such as silos, trucks, or packaging bags).

The bulk density of urea is mainly divided into two categories, which need to be distinguished:

Loose packing density: the density of urea when poured into a container without compaction (such as filling a silo by gravity);

Compacted bulk density: The density of urea after slight compaction (such as vibration during transportation or container impact). Due to compaction reducing the gaps between particles, the compacted packing density is always higher than the loose packing density.

What is the urea bulk density?

Firstly, it is essential to note that the urea bulk density is not a fixed, single value. It mainly depends on the form of urea – small particles (Prilled) or large particles (Granular).

The following are typical ranges recognized by the industry:

Prilled Urea: 720-770 kg/m³
Granular Urea: 760-800 kg/m³

Key point: Large particle urea usually has a higher packing density than small particle urea because its particles are larger, rounder, and have relatively smaller gaps between particles.

Urea Bulk density vs. particle density

To accurately understand, we must distinguish between “bulk density” and “particle density”.

Bulk Density: Refers to the mass occupied by a large number of urea particles in a specific container divided by their total volume (including air gaps between particles). This can be imagined as the density of a truck of sand.

Density (particle/solid particle density): refers to the mass of a single urea particle divided by its own volume (excluding any air transparency). This can be imagined as the density of an object. The particle density of urea is approximately 1335 kg/m3.

The main components affecting the support density of urea

1. Particle size and uniformity

Larger and more uniform particles: higher packing density (e.g., granular urea has a higher packing density than granular urea because larger particles can be more tightly packed);

Particles are small or contain dust: the packing density is lower (although dust fills the gaps between particles, the mass proportion is small, and the overall density decreases).

2. Moisture content

Urea has hygroscopicity (absorbing moisture from the air). Even a small amount of moisture (exceeding 1.0%) can cause particle adhesion (agglomeration), resulting in an increase in compacted packing density but a decrease in fluidity.

Example: Urea with a moisture content of 0.5% and a loose bulk density of 750 kg/m³; If the moisture content rises to 2.0%, the particles will agglomerate and the loose packing density may decrease to 700 kg/m³ (due to uneven filling), while the compacted packing density will soar to 880 kg/m³ (due to excessive compaction).

3. Handling and transportation

The vibration during transportation will compact the urea, increasing the compacted bulk density. For example, urea with a loose bulk density of 750 kg/m³ may have a compacted bulk density of 820 kg/m³ after being transported over long distances by truck. Therefore, it is necessary to measure the bulk density before and after transportation to avoid overloading the silo.

Why is the urea bulk density so important?

1.Warehousing and storage design

Engineers must use bulk density to calculate the maximum storage capacity (in tons) of silos, warehouses, or hoppers when designing them. Incorrect use of particle density can result in a design capacity far exceeding the actual capacity.

2.Logistics and Transportation

Logistics managers need to use it to calculate the maximum payload of trucks, train carriages, or cargo containers. This ensures that transportation vehicles are not overloaded, allowing them to achieve maximum cost-effectiveness.

3.Agricultural applications

Farmers and agronomists need accurate packing density when calibrating fertilizer spreaders to ensure the correct amount of nitrogen fertilizer is applied per hectare of land. Inaccurate density can lead to either excessive or insufficient fertilization, which in turn affects crop yield and the environment.

4.Equipment and process design

In chemical plants, the design and selection of conveyors, hoppers, and reactors for urea processing rely on an understanding of their bulk density to ensure smooth and controlled material flow.

urea bulk density Practical Calculation Example

Question: How many metric tons of large granular urea can be stored in a silo with a capacity of 150 cubic meters (m3) at most?

Solution:
1. Select a saved large particle urea deposition density value, such as 780 kg/m³.
2. Formula: Total mass=Volume x LED density
3. Calculation: 150 m ³ × 780 kg/m ³=117000 kg
4. Convert to metric tons (1 metric ton=1000 kg): 117000 kg/1000=117 metric tons

Answer: The silo can store approximately 117 metric tons of large particle urea.

conclusion

Although the urea bulk density (kg/m³) is a simple number, it is a fundamental parameter that affects the entire process of urea handling, from storage, transportation, to application and quality control. By understanding standard values, accurately measuring density, and controlling factors such as moisture and particle size, operational efficiency can be optimized, costs can be reduced, and product performance can be ensured to be stable.

Whether you are an agricultural distributor storing fertilizers, an industrial manufacturer producing resins using urea, or a fleet manager handling DEF urea, valuing bulk density can help you simplify processes and avoid costly downtime losses.

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urea bulk density