The equipment sequence in an organic fertilizer production line is not arbitrary; it follows the objective principles of how the material’s state changes during processing. When factories experience frequent clogging, low granulation rates, or high drying energy consumption after commissioning, the root cause is often not the quality of a single machine, but an incorrect equipment sequence. From fermentation and turning to semi-wet crushing and dry granulation, each step prepares the material in the appropriate state for the next stage.
The first step must be fermentation and turning, not crushing. High-moisture livestock manure often has a water content exceeding 60%; if fed directly into a crusher, the wet material quickly adheres to the rotor and clogs the screen, causing the motor current to spike. The correct starting point is the double-screw compost turner. This machine uses symmetrical screw shafts to turn material from the bottom of the pile to the surface, introducing fresh air into the core; moisture evaporates continuously during turning, and the organic matter decomposes simultaneously. It achieves a turning depth of 1.2–2.5 meters, a material mixing uniformity of over 92%, and a fermentation cycle of approximately 15 days. After this step, the moisture content drops from over 60% to 35%–45%, and the decomposition is uniform, creating the right conditions for subsequent crushing.
The second step is semi-wet material crushing, not direct granulation. Although the fermented material has a lower moisture content, the turning and compression processes often create hard clumps and tangled fiber masses. This is where the semi-wet material crusher is required. It employs a dual-stage rotor structure: the upper stage performs coarse crushing and breakup, while the lower stage handles fine crushing and homogenization. Its screenless design allows material with 30%–50% moisture content to discharge directly, preventing wet material from clogging the screen. The crushed material has greater uniformity and increased specific surface area, providing a stable feed state for the granulation stage. Skipping this step allows clumps and long fibers to enter the granulator, leading to material sticking to the pan surface, extrusion roller slippage, and inconsistent granule strength. Dry granulation is the third step, distinct from forced wet granulation methods. Dry processes, such as twin-roll extrusion, require the material’s moisture content to be controlled between 8% and 15%; consequently, the pulverized material must undergo drying and cooling before entering the dry granulator. Dry granulation relies on mechanical pressure for direct forming—eliminating the need for added water or binders—and offers high granule strength alongside low energy consumption. However, the process is highly sensitive to feed fineness and moisture levels: insufficient fineness hinders material intake, while excessive moisture causes sticking and slippage on the rollers. All work performed in the preceding two steps is aimed at ensuring the material enters the dry granulator in optimal condition.