2026/11/12
In the production of organic fertilizer from cow dung, the mixing stage is the most prone to issues: materials sticking to the walls, fibers wrapping around the shaft, and uneven blending of additives. When selecting a mixer, one should not merely consider whether it can rotate; rather, it must be capable of handling the three inherent physical challenges of cow dung: high moisture content, high viscosity, and the presence of fibers of varying lengths.
A double shaft paddle mixer is the preferred choice. After fermentation, cow dung typically has a moisture content of 30%–40% and is highly viscous. In a standard single-shaft ribbon mixer, "dead zones" easily form between the ribbon and the vessel wall, leading to a buildup of material. In a double shaft paddle mixer, the two shafts rotate in opposite directions, and the paddles provide forced shearing, tossing, and convection. This prevents wet, sticky manure from adhering to the equipment, ensures a short mixing time—typically achieving uniformity in just 3–5 minutes—and, when additives like straw powder or mushroom substrate residue are included, the shearing force helps break up manure clumps, reducing the workload for the upstream crushing equipment.
The use of a horizontal ribbon mixer comes with conditions. If the cow dung has undergone solid-liquid separation or aging, reducing its moisture content to below 25%, a ribbon mixer can perform effectively, providing uniform mixing with minimal residue. However, once the moisture content exceeds 30%, material will quickly stick to the ribbon and the vessel walls, causing a sharp drop in efficiency. Therefore, this type is better suited for "drier" formulations or the mixing of recycled material (recycled fines), rather than for processing high-moisture cow dung fresh from the fermentation bay.
A vertical disc mixer is suitable for small-scale production and simple formulations. It features a straightforward design and requires a lower initial investment; it also offers a reasonable tolerance for high-moisture materials. However, the uniformity of the mix depends on the residence time, and because cow dung and additives often have different densities, they tend to separate (stratify). This type is appropriate for small processing facilities with a daily output of only a few tons, but it is not recommended for production lines manufacturing commercial granular fertilizer.
Three key operational points: First, break up any clumps using a crusher before feeding the material into the mixer. Second, ensure accurate measurement of additives, as the ratio of cow dung to materials like straw powder directly affects the moisture content required for granulation. Third, the capacity of the mixer should be slightly higher than that of the granulator, and a buffer silo should be installed to ensure a continuous supply of material. While a mixer does not directly determine the roundness of the granules, it does ensure that the cow dung and auxiliary materials are thoroughly integrated within each individual particle. Choosing the right type of mixer is the key to preventing clogging and sticking in a cow dung organic fertilizer production line—right from the very start.
