Answer: NPK fertilizer granulators are primarily designed for various single-nutrient fertilizers (nitrogen, phosphorus, and potassium) and mixed powdered raw materials. With a wide range of compatibility, they can handle the production of standard, high-concentration, and functional compound fertilizers, serving as the core equipment in compound fertilizer production lines. Whether using a double-roller extrusion granulator or a rotary drum granulator, the vast majority of powdered or fine-grained fertilizer raw materials can be processed; these materials generally fall into three main categories.

First are nitrogen fertilizer raw materials, commonly including urea, ammonium bicarbonate, ammonium sulfate, and ammonium chloride. These materials feature good water solubility and moderate adhesiveness, serving as the primary nitrogen sources for NPK compound fertilizers. Urea is the most widely used and versatile option; it is less prone to issues like machine clogging or poor granulation, making it suitable for producing both high- and low-concentration compound fertilizers.
Second are phosphorus fertilizer raw materials, primarily including monoammonium phosphate (MAP), diammonium phosphate (DAP), single superphosphate (SSP), and triple superphosphate (TSP). MAP offers excellent adhesiveness and acts as a high-quality granulation aid, effectively improving granule formation rates and strength; it is a key phosphorus source for NPK granulation. SSP and TSP materials are typically very fine; when mixed with nitrogen and potassium raw materials, they yield stable granulation results.
Finally, there are potassium fertilizer raw materials—mainly potassium chloride and potassium sulfate—which are compatible with all NPK granulation equipment. Potassium sulfate is suitable for producing chlorine-free compound fertilizers for fruits and vegetables, offering broader applicability, while potassium chloride is more cost-effective and commonly used for compound fertilizers intended for field crops.
In addition, auxiliary materials—such as binders like bentonite, talc powder, and attapulgite—can be used alongside the primary ingredients to enhance granule formation. It is important to ensure that raw materials remain dry and free of large, hard lumps. An optimal particle fineness of 80–100 mesh helps effectively prevent issues such as excessive dust, uneven granules, and machine clogging, thereby significantly increasing the pass rate of the finished product.