1. Raw material pretreatment: Nitrogen sources (urea, ammonium chloride), phosphorus sources (monoammonium phosphate, superphosphate), and potassium sources (potassium chloride, potassium sulfate) are respectively sent to a crusher and pulverized to a suitable particle size.  At the same hand, binders or conditioning agents such as bentonite are added to the raw materials according to the formula requirements.

2. Batching and mixing: According to the set N-P-K ratio, each raw material is accurately measured by an automatic batching system and sent to the core equipment of the NPK blending fertilizer production line—a horizontal fertilizer mixer—for thorough mixing to form a uniform material mixture, preventing raw material stratification.

3. Granulation and shaping: The mixed materials are sent to a fertilizer granulator machine.  Drum granulation or disc granulation is commonly used in the granulation method. Steam or an aqueous solution of a binder is sprayed to make the material particles adhere to each other and roll to form wet granules with the required particle size.

4. Drying and cooling: The wet granules first enter a dryer (commonly a fertilizer rotary drum dryer) to remove moisture using hot air, and then are sent to a cooler to cool down to room temperature, preventing particle clumping or component decomposition. The processed granules are then subjected to preliminary screening using the auxiliary screening device of the NPK blending machine.

5. Screening and grading: The cooled granules are graded by a vibrating screen, separating out coarse particles and fine powders that do not meet the required particle size.

6. Coating and packaging: The qualified granules are sent to a coating machine, where anti-caking agents or functional coating materials are sprayed.  Finally, the granules are weighed and packaged using the metering and packaging equipment of the NPK blending fertilizer produciton line, and then stored in the warehouse.