As a key piece of equipment in fertilizer production lines, the double roller press granulator is widely used due to its low cost and high granulation rate. Its operating process can be divided into three core stages: raw material pretreatment, extrusion molding, and crushing and screening. Each stage works closely together to achieve efficient granulation.

In the raw material pretreatment stage, powdered raw materials (such as compound fertilizer powder and organic fertilizer raw materials) must be blended and mixed. The equipment uses a metered feeding system to uniformly convey the raw materials, with a moisture content of 8%-15%, to the pretreatment unit to remove impurities and ensure material uniformity. This step is fundamental to granulation quality. Excessive impurities or inappropriate moisture content in the raw materials will directly affect subsequent molding and may even cause equipment blockage.
In the core extrusion molding stage, the pretreated raw materials are conveyed between two counter-rotating extrusion rollers. The roller surfaces are engraved with evenly distributed semicircular or trapezoidal grooves. When the material falls into the gap between the two rollers, it is forced into the grooves under high pressure of 5-15 MPa, forming a continuous columnar or sheet-like pellet. During this process, the speed of the extrusion rollers must be precisely controlled (typically 10-30 rpm). Excessively fast speeds can lead to uneven material loading, while too slow speeds can reduce production efficiency. Therefore, these machines are often equipped with variable frequency speed control systems to accommodate varying raw material requirements.
The final stage is the crushing and screening process. The formed pellets first enter the crushing unit, where rotating blades cut them into irregular particles. These particles are then graded and screened by a vibrating screen. Pellets that meet the required particle size (typically 1-5 mm) are output as finished products, while oversized or undersized particles are returned to the raw material system for re-extrusion. This creates a closed-loop process of "raw material - granulation - screening - return material," significantly improving raw material utilization and typically achieving a yield rate exceeding 90%.
Overall, the double roller press granulator utilizes the core principle of "physical extrusion molding," eliminating the need for binders. This reduces production costs and avoids chemical contamination. Its modular workflow also facilitates maintenance and parameter adjustment, making it a mainstream option for solid particle production.