Organic fertilizer granulation is a key process for improving the marketability of fertilizer and enhancing its application effects. Raw material processing before granulation, as a crucial preliminary step in the organic fertilizer production process, directly determines the quality of the granules, the molding rate, and production efficiency, making it an indispensable part of the organic fertilizer production. High-quality raw material pretreatment can effectively solve problems such as poor adhesion, loose granules, and equipment wear during the granulation process, laying a solid foundation for subsequent granulation steps.
Crushing is the primary step in raw material pretreatment. Organic fertilizer raw materials come from a wide range of sources, such as livestock and poultry manure, straw, and mushroom residue, and often have problems such as uneven particle size and coarse fibers. These materials need to be processed to a suitable particle size using crushing equipment. Generally, the particle size of the crushed raw materials should be controlled at 40-80 mesh. This increases the specific surface area of the raw materials, improves adhesion, and prevents coarse particles from clogging the equipment and affecting the uniformity of the granules. For fibrous raw materials such as straw, secondary crushing is also required to break down the fiber structure and enhance its compatibility with other raw materials.
Mixing and homogenization are core steps in ensuring balanced nutrients in organic fertilizer and a crucial step in optimizing the production quality of organic fertilizer. Different raw materials have significant differences in nutrient content and physical properties, so the crushed raw materials need to be thoroughly mixed according to the formula ratio. During the mixing process, it is necessary to ensure that all types of raw materials are evenly distributed, avoiding excessively high or low nutrient levels in certain areas. At the same time, an appropriate amount of binder (such as bentonite or starch residue) can be added to improve the adhesion of the raw materials and create conditions for granule formation. The selection of mixing equipment should be adapted to the characteristics of the raw materials to ensure a mixing uniformity of over 90%.
Moisture adjustment is a critical control point before granulation. The moisture content of the raw materials directly affects the granulation molding rate. Too high a moisture content can easily lead to granule adhesion and equipment scaling, while too low a moisture content makes it difficult to form dense granules. Generally, the suitable moisture content of raw materials before granulation is 25%-35%, which needs to be adjusted through drying, sun-drying, or spraying water, depending on the initial moisture content of the raw materials. For wet materials such as livestock and poultry manure, drying equipment can be used to reduce moisture; for dry materials such as straw, water needs to be sprayed evenly to increase moisture and ensure that the moisture penetrates into the raw materials.
Furthermore, some raw materials require harmless pretreatment, which is a necessary measure to ensure product safety during the organic fertilizer making process. If the raw materials contain pathogenic bacteria, insect eggs, or weed seeds, they must be treated through high-temperature fermentation and sterilization to ensure the safety of the organic fertilizer product and reduce adverse effects on crop growth. At the same time, impurities such as stones and metals must be removed from the raw materials to prevent wear and tear on the granulation equipment and extend its service life.
In summary, the pretreatment of raw materials before granulation must consider particle size, uniformity, moisture content, and safety. Strict control of standards at each stage is essential to provide high-quality raw materials for the subsequent granulation process, producing organic fertilizer products with uniform granules, sufficient strength, and balanced nutrients, thereby enhancing market competitiveness and agricultural application value.
