Let us first examine the initial crushing stage. Decomposed organic materials typically have a moisture content of 20% to 50%; they are highly viscous and prone to fiber entanglement. Traditional crushers often struggle with this "semi-wet" state—screens become clogged with wet material, causing the machine to idle without discharging product. The solution offered by the semi-wet material crusher is to eliminate the bottom screen and adopt a tandem dual-rotor structure: material is first coarsely crushed by high-speed impact from the upper rotor, then thrown into the lower rotor for fine pulverization, creating a dual-crushing effect of "hammer-on-material" and "material-on-material." The output particle size directly meets subsequent granulation requirements and can be flexibly adjusted within a specific range. While this step may appear to be merely "breaking things up," it is actually the starting point of the entire post-processing chain; without uniformly fine powder, the subsequent granulation and ball-shaping stages would be impossible.

Once granulation is complete, the task of perfecting the granules' appearance falls to the ball shaping machine. Granules produced via extrusion or stirring-tooth granulation often feature angular cross-sections and rough, uneven surfaces. The operating principle of the spheronizer is straightforward: a high-speed rotating disc generates centrifugal force, causing granules to tumble repeatedly and rub against one another within the shaping chamber. This action gradually rounds off sharp edges and compresses or smooths out surface pits. Parameter control is crucial to this process: the rotation speed is typically set between 30 and 50 revolutions per minute (rpm), and the chamber tilt angle is adjusted to between 3 and 6 degrees. A shallower tilt angle extends the granules' residence time in the chamber, resulting in superior sphericity. Furthermore, a design utilizing multiple spheronization chambers in series enables progressive shaping, achieving a sphericity of over 95% in the finished product while simultaneously enhancing density and strength.

If the spheronizer ensures the product "looks good," the coating machine ensures it "performs well." The core value of fertilizer coating lies in regulating the nutrient release rate; by encapsulating granules in a slow-release material, nutrients are supplied gradually in response to crop needs rather than being released all at once. A rotary coating machine operates much like a slowly rotating drum: as granules tumble continuously inside, a spray system applies the coating liquid evenly across their surfaces. The drum typically rotates at 15 to 16 rpm, and hot air is used to cure the coating, ultimately forming a uniform, dense film on the granule surface. The thickness and composition of this film determine the nutrient release duration—ranging from several weeks to several months—making this a critical technical step in the production of slow- and controlled-release fertilizers.