The entire double roller press granualtor is a dry process, requiring no water, binders, or drying. It consists of six steps: raw material pretreatment → forced feeding → extrusion molding → threshing → screening → finished product.

Raw material pretreatment: Organic fertilizer and NPK raw materials are crushed in a half-wet material crusher(compost crusher), with a fineness controlled below 2mm. The material moisture content is strictly controlled between 6% and 8%. Lumps, stones, and iron filings are screened out. High moisture content easily leads to sticking and roller blockage, while excessive dryness results in poor molding and excessive powder. Multiple raw materials are pre-mixed evenly to avoid component segregation affecting granule quality.

Forced feeding process: The mixed material is stored in a buffer hopper, and a variable frequency screw feeder forces the material into the gap between the two rollers. Variable frequency speed control is used to match the main machine load, preventing inconsistent feeding, one-sided feeding, and localized wear on the roller skin.

Extrusion Molding: Two rollers rotate synchronously inwards, and the roller die holes, under high pressure, compress the powder into the die cavity, forming strip-shaped granules. The extrusion pressure and roller gap size are adjusted by a hydraulic cylinder; a smaller gap results in higher particle density.

Scraper De-granulation: After the rollers exit the die holes, a fixed scraper removes the embedded strips, naturally breaking them into short cylindrical granules. If the die holes become clogged, the machine is stopped immediately for cleaning to prevent blockage.

Screening and Grading: The degraded material is fed into a drum screen. Larger pieces are returned for secondary crushing and re-extrusion, while finer powder is returned to the batching silo for re-granulation. Particles in the middle (2-4mm) are considered qualified semi-finished granules.

Optional Post-Polishing Process: The semi-finished product enters an organic fertilizer ball shaping machine to remove sharp edges, improving roundness and product appearance.

Process Advantages: Short process flow, eliminates drying stage, low energy consumption; high granule strength, less prone to moisture absorption and pulverization, suitable for organic-inorganic compounding and high-salt NPK production. Maintaining stable moisture content and uniform feeding is key to ensuring a molding rate of over 85%.