Material properties serve as the primary screening criterion. Different granulation methods have vastly different tolerances regarding raw material moisture content, fineness, and viscosity. While NPK fertilizer granulators perform excellently with inorganic salt materials, their granulation rate may drop below 60% if used directly with high-fiber organic materials. Organic fertilizer disc granulators are highly adaptable to viscous materials—achieving granulation rates exceeding 93%—but they impose strict requirements on powder fineness (≥60 mesh); if raw materials contain excessive coarse fiber, pre-treatment with a pulverizer is necessary. New-type organic fertilizer granulators and new-type two-in-one organic fertilizer granulators feature optimized designs that integrate mixing and granulation functions. They offer superior adaptability to viscous materials and handle both mixing and pelletizing in a single unit, making them particularly suitable for small-to-medium-scale organic fertilizer production.

Process objectives dictate the choice of equipment. If the goal is high sphericity and a smooth, rounded appearance, disc granulation production lines and standard organic fertilizer granulators are logical choices, though they require supporting drying systems. If high granule strength suitable for long-distance transport is required, extrusion granulation solutions should be evaluated. Conversely, if the priority is low investment costs, a small footprint, and the elimination of drying steps, the double-roller extrusion method is the superior option. When handling diverse raw materials and frequently switching formulas, the flexibility and rapid clean-out capabilities of a general-purpose granulator are critical considerations.

Verifying the compatibility between equipment principles and material behavior is essential. The best way to assess this compatibility is through trial runs: sending representative raw materials to the manufacturer to conduct small-batch granulation tests using the target model, while monitoring key metrics such as pelletization rate, granule strength, and energy consumption. These trials should simulate actual production conditions—specifically material moisture content and formulation—to avoid misleading data derived from "idealized" conditions. In the context of an NPK blending fertilizer production line, a lack of thorough material analysis and trial verification during the initial stages can lead to costs during the subsequent commissioning phase that far exceed the expense of the trials themselves. Investors are advised to include the trial report as an attachment to the technical agreement before signing the contract, clearly specifying performance indicators to ensure the equipment meets production targets and standards immediately upon commissioning.