In fertilizer production, high-moisture raw materials (such as fermented organic fertilizers and wet materials after compound fertilizer granulation) are prone to caking and mold if not dried promptly, affecting product quality and storage life. Drum fertilizer dryers, with their “continuous drying + uniform heating” characteristics, have become a core dehydration equipment in the fertilizer industry. Their operating principle is precisely adapted to the characteristics of fertilizer raw materials.

The core structure of a drum fertilizer dryer is an inclined rotating drum equipped with a heating system and a discharge device. During operation, high-moisture fertilizer (30%-50% moisture content) enters the drum through the high-end feed port. The motor drives the drum to slowly rotate, continuously turning the material and moving it forward. Simultaneously, the high-temperature hot air generated by the heating system fully contacts the material, rapidly removing moisture from the material through a dual heat transfer process of “convection and conduction.”

To prevent fertilizer clumping, a lifting plate is often installed inside the drum. This plate continuously lifts and drops the material, increasing the heating surface and ensuring uniform drying of each portion. The drum’s tilt angle is adjustable to control the material’s residence time within the drum, thereby precisely controlling the moisture content after drying. The entire process is continuous and stable, suitable for the mass production needs of organic fertilizer production lines. The dried material is loose and free of lumps, eliminating the need for secondary crushing.

Small and medium-sized organic fertilizer companies are characterized by moderate production capacity, diverse raw materials, and large batch sizes. The design features of the flat die granulator perfectly meet these needs, making it a cost-effective choice for these companies.

1. Low Equipment Investment Cost

The flat die granulator has a relatively simple structure and does not require a complex transmission system. The purchase cost of a single unit is only 60%-70% of that of similar granulator equipment with similar production capacity. Furthermore, installation does not require a complex foundation, saving small and medium-sized companies from the high initial investment.

2. Flexible Raw Material Adaptability

Small and medium-sized organic fertilizer companies often purchase local raw materials, which can have large fluctuations in moisture and fiber content. The flat die granulator’s wide adaptability allows it to handle high-fiber straw materials, and the vertical compression of the rollers prevents tangling. For fermented materials with slightly higher moisture content, the flat die surface is easy to clean and prevents sticking.

3. Convenient Production Changeover

Small and medium-sized companies often produce a variety of products in small batches, requiring frequent adjustments to pellet size. It only takes 1-2 people to replace the flat die of the flat die granulator, and it can be completed within 30 minutes. In addition, the cost of flat dies with different apertures is low. The company can reserve multiple sets of flat dies and quickly switch product specifications to meet the needs of different customer orders.

In the fertilizer industry, the physical properties of organic fertilizers (mostly made from fermented manure and straw) and compound fertilizers (mostly made from phosphate rock, potassium chloride, and urea) differ significantly. Organic fertilizers are fibrous, highly moist, and prone to sticking together, while compound fertilizers are hard, fiberless, and require high-hardness molding. Ring die granulators, through their “adjustable structure + material adaptability,” can meet the granulation needs of both fertilizer types.

For organic fertilizer granulation, ring die granulators offer two key design advantages: First, they utilize a “low compression ratio” ring die (3:1-5:1) to avoid excessive compression that damages the organic matter and bacterial inoculant activity in the raw material, while ensuring that the granules do not break apart. Second, they feature an “anti-sticking die conditioning system” that precisely controls the amount of water added and a small amount of binder (such as starch residue) to reduce material sticking to the die, thereby improving molding efficiency and discharge speed.

For compound fertilizer granulation, the ring die granulator focuses on “wear resistance and high extrusion capacity”: the ring die is made of wear-resistant alloy material, which can withstand the high-frequency friction of mineral raw materials and has a service life three times longer than that of ordinary materials; the pressure roller is hardened to enhance the extrusion force, and is equipped with a “high compression ratio ring die” (6:1-8:1) to ensure that the hardness of the compound fertilizer particles meets the standard.

The core difference between bio-fertilizer production and conventional organic fertilizer and compound fertilizer production lies in the need to preserve the activity of the inoculant. Furthermore, the raw materials often consist of specialized materials such as fungus residue, traditional Chinese medicine residue, and fermented straw. This places special demands on grinding equipment: low temperature, pollution prevention, and precise particle size. Through targeted modifications, fertilizer crushers have become the ideal choice for bio-fertilizer production.

1. Low-temperature crushing preserves inoculant activity

The functional bacteria in bio-fertilizer (such as Bacillus subtilis and phosphate-solubilizing bacteria) are not tolerant to high temperatures. Excessive frictional heat (above 45℃) generated during the grinding process can inactivate the bacteria. High-quality fertilizer crushers optimize the impeller speed (to avoid excessive friction) and some are equipped with a “water-cooling jacket” to circulate cold water to remove heat from the chamber walls, maximizing inoculant activity.

2. Anti-residue design prevents cross-contamination

Bio-fertilizer production often requires switching between different inoculant formulations. If residual material from previous batches remains in the equipment, bacterial strains can mix. The fertilizer crusher‘s “fully open cleaning structure” solves this problem. The grinding chamber door can be fully opened, and the smooth, corner-free interior allows for quick cleaning without disassembling core components, reducing the risk of cross-contamination.

3. Precise Particle Size for Microbial Agent Mixing

Bio-fertilizer production requires uniform particle size (typically 1-3mm) after grinding. Uneven particle size results in incomplete mixing of the microbial agent and raw material, impacting fertilizer efficiency. The horizontal crusher can precisely control particle size deviation within ±0.5mm, providing a high-quality raw material foundation for subsequent microbial agent inoculation and mixing.

To achieve the goal of efficient fertilizer production, low-energy retrofitting of NPK fertilizer production lines has become an industry imperative, with key improvements focused on optimizing technologies in high-energy-consuming processes.

In the raw material pretreatment stage, a waste heat recovery system is used to redirect 80-120°C exhaust gases generated during the drying process into the pulverization process, reducing energy consumption by 18%-22% and simultaneously reducing thermal emissions.

In the granulation process, a core energy consumer, traditional steam heating is gradually being replaced by electromagnetic heating, increasing heating speed by 50% and boosting thermal efficiency from 65% to over 90%. This reduces energy consumption per ton of product by approximately 80 kWh.

A closed-loop cooling system is introduced in the cooling process, increasing water reuse from 30% to 95% while minimizing the impact of circulating water on the surrounding environment.

In addition, the NPK fertilizer production line has achieved refined management and control through motor frequency conversion and an intelligent energy consumption monitoring platform. This platform monitors power changes across each device in real time, allowing for timely adjustment of operating parameters and avoiding idle energy consumption. Data shows that after systematic low-energy consumption upgrades, the NPK fertilizer production line can reduce overall energy consumption per ton of NPK fertilizer by 25%-30%, achieving both environmental and economic benefits.