Urea possesses good plasticity but has a relatively low melting point. Fertilizer granules compaction machines, which utilize a dry, ambient-temperature extrusion process, offer a viable solution for the granulation of urea.
The fertilizer granules compaction process is purely physical; it requires no water or binders, thereby eliminating the need for a drying stage. Urea powder is compacted through mechanical pressure, then crushed and screened to produce the final granules. This streamlined process consumes less energy and prevents the loss of urea nutrients that would otherwise occur due to thermal decomposition at high temperatures. The equipment can process pure urea or be used to blend urea with phosphorus and potassium raw materials to produce high-nitrogen compound granular fertilizers.
However, friction during extrusion generates localized heat. Since urea tends to soften and become sticky when heated, improper pressure control can lead to the material adhering to the molds or clogging the extrusion chamber, resulting in poor discharge and deformed granules. When producing urea fertilizer, it is essential to strictly control the moisture content of the raw materials—keeping it low—and to set the extrusion pressure appropriately, rather than striving blindly for higher granule hardness.
Urea granules produced via extrusion are dense and possess high mechanical strength, making them resistant to pulverization during storage and transport. Their oblate, spherical shape is well-suited for mechanized spreading. Compared to products made through melt granulation, extruded urea has slightly lower water solubility, making it particularly suitable for use as a basal (base) fertilizer.
Overall, the production of urea fertilizer using a fertilizer compaction machine is a simple process with moderate capital investment. By effectively managing raw material pre-treatment, as well as pressure and temperature conditions, manufacturers can achieve stable production—a solution well-suited for small to medium-sized fertilizer processing operations.