The granulation process of double roller press granualtors is a dry physical granulation method. The core difference between this and wet agglomeration granulation methods such as disc and drum granulation lies in their granulation processes: one relies on "high-pressure extrusion," while the other relies on "water-based ball rolling."

1. Different Principles and Processes

Roller extrusion uses two high-pressure rollers to directly press dry powder materials into flakes, which are then crushed and screened. The entire process requires no water addition or drying, resulting in a shorter process and smaller footprint.

Wet granulation, on the other hand, requires the addition of steam or binders to the material, which then agglomerates into balls under rotation. This necessitates the installation of drying and cooling equipment, leading to a longer process and higher investment.

2. Significant Differences in Energy Consumption and Cost

Roller extrusion is a cold processing method, with a unit energy consumption of only about 8.5 kWh/ton. There are no heat source costs, and the overall operating cost is 30%-50% lower than that of wet granulation.

The drying stage in wet granulation consumes a significant amount of energy, typically accounting for over 60% of the total energy consumption. The total investment in fertilizer produciton machine is often 2-3 times that of dry granulation.

3. Different Finished Product Characteristics: Roller extrusion produces irregular cylindrical or oblate spherical granules with high density, high hardness, and extremely low moisture content (≤10%). These granules are less prone to clumping and can be packaged without drying.

Wet granulation produces spherical granules with a smooth, appealing appearance, but they are less strong and more brittle. High-temperature drying may also lead to the loss of heat-sensitive nutrients.

4. Different Raw Material Adaptability: Roller extrusion requires raw materials with a moisture content of 15%-25% and good flowability, making it suitable for dry organic fertilizers and compound fertilizers.

Wet granulation can process high-moisture, high-fiber materials (such as fresh manure and biogas residue) with a moisture content of 20%-35%, offering wider adaptability.