Disc granulation production lines and NPK fertilizer production lines are distinct systems with different market positioning, rather than merely different stages of the same process.

The disc granulation line centers on a disc granulator and features a streamlined process: raw material crushing → mixing → disc granulation → drying → cooling → screening → packaging. It primarily targets organic fertilizers, organic-inorganic compound fertilizers, and low-to-medium concentration fertilizers, often utilizing raw materials such as livestock manure and decomposed crop straw. Relying on the rolling and agglomeration of materials into spheres, it is well-suited for organic materials and offers a low investment threshold, making it ideal for small-to-medium-scale operations that require frequent formula changes.

In contrast, NPK fertilizer production lines are designed for inorganic compound fertilizers. They primarily utilize inorganic salts—such as urea, monoammonium phosphate (MAP), and potassium chloride—resulting in higher nutrient concentrations. Granulation methods include rotary drums, extrusion, and high-tower melt granulation; while disc granulation is an option, it is not the mainstream choice for high-concentration products due to difficulties in sphere formation and high recycle rates. These lines impose much stricter requirements regarding ingredient precision, drying and cooling processes, and anti-caking measures compared to disc granulation lines.

The core differences lie in: raw material systems (organic materials vs. inorganic salts); nutrient concentrations (low-to-medium vs. high); process complexity (streamlined stages vs. comprehensive systems); and investment scale (entry-level vs. medium-to-high investment).

When selecting a line, first clarify the product positioning: for organic fertilizers or low-concentration compound fertilizers, the disc granulation line offers superior cost-effectiveness; for high-concentration NPK compound fertilizers, a comprehensive NPK production line is required, necessitating a more suitable choice of granulation technology.