2026/03/12
In NPK compound fertilizer production, the double roller press granulator, with its advantages of no binder required, low energy consumption, and high granule strength, has become an ideal choice for processing low-moisture raw materials. However, the stable operation of the equipment highly depends on standardized operating procedures and timely troubleshooting. Based on practical experience with the DZJ series double roller press granulators, this article outlines the key operational points for operators throughout the entire process, from start-up preparation to daily maintenance.
Preparation before start-up directly affects the granulation effect. First, the roller gap needs to be adjusted according to the formula requirements: for easily formed raw materials such as ammonium sulfate and potassium chloride, the gap should be set at 0.5-1.5mm; for raw materials with higher hardness, it can be widened to 2-3mm. Too small a gap will lead to accelerated roller wear, while too large a gap will result in loose and poorly formed granules.
Material pretreatment is equally crucial. The raw material needs to be crushed to a fineness of 80-200 mesh, and the initial moisture content should be strictly controlled at 8%-12%—the optimal state is when it can be formed into a ball by hand but crumbles easily under light pressure. Excessive moisture content can cause the particles to stick to the rollers, while insufficient moisture content makes compaction difficult. Simultaneously, install the corresponding mold according to the target particle size (e.g., cylindrical, oblate), ensuring the roller grooves match the product requirements.
After starting the equipment, gradually adjust to the set parameters. Roller pressure is a decisive factor in molding quality: when processing ordinary NPK raw materials, control the pressure between 10-30 MPa; for high-hardness materials or when increasing particle strength, the pressure can be increased to 50 MPa, but care must be taken not to exceed the equipment's rated value. The linear speed is recommended to be maintained at 0.5-2 m/s—too high a speed will lead to insufficient material filling and decreased particle density; too low a speed will affect production capacity.
Uniform feeding is key to stable operation. Use a variable frequency speed-regulating screw feeder to ensure continuous and stable material entry between the two rollers. Observe ammeter fluctuations: if the current remains consistently high, it may indicate overfeeding or insufficient roller gap; if the current is low, check if the hopper is empty. During operation, check the particle appearance every 15 minutes and fine-tune the parameters as needed.
Even with proper operating procedures, occasional malfunctions are difficult to completely avoid. Here are quick solutions for three common problems:
Roller jamming is often caused by foreign objects (such as metal fragments or hard lumps) entering the rollers or by excessively wet and sticky material. If jamming is detected, stop the machine immediately and reverse the machine jogging to remove the foreign objects. If the material is too wet, clean the dried material from the roller surface and check if the pre-treatment moisture content is excessive.
Loose granules are usually caused by insufficient pressure or excessively dry material. First, check if the hydraulic system pressure is sufficient, and gradually increase the pressure until granules are formed. If the pressure is normal, test the moisture content of the raw material and replenish it to 9%-11% using atomized spraying before trying again.
Abnormal noise often indicates insufficient bearing lubrication or roller wear. After stopping the machine, check the bearing lubrication and add high-temperature grease. If the noise is accompanied by vibration, disassemble and inspect the rollers, measure the wear, and replace the roller sleeves if necessary.
Daily maintenance guidelines: Prevention is better than cure.
After each shift, clean the rollers and hopper of any remaining material to prevent dried material from damaging the equipment upon the next startup. Check the lubrication oil level weekly and add grease to the drive bearings; check the roller wear monthly and record changes in clearance. Wear parts such as liners and scrapers should be replaced every 6-12 months depending on usage frequency—liner wear can lead to material leakage, and dull scrapers affect roller surface cleaning.
The value of the double roller press granulator lies in its "dry forming, zero emissions," but its stable operation depends on the operator's standardized procedures. Precise control of every step, from start-up and commissioning to troubleshooting, is the cornerstone of ensuring the continuous and efficient operation of the production line.
The precise control required for the double roller press granulator highlights the importance of upstream material preparation. Before material ever reaches this core npk fertilizer granulator, it must be accurately proportioned and homogenized. For a granulated product, this often involves an npk blending machine or a more intensive mixer to create a uniform powder feed. However, it's crucial to distinguish this from a purely physical blending operation. A dedicated npk blending fertilizer production line, which produces BB fertilizer, relies on a different set of equipment. The heart of such a line is the npk bulk blending machine or BB fertilizer blender, which accurately meters and mixes granular components without any chemical reaction or the need for a subsequent npk fertilizer granulator machine. While the process is simpler, modern npk bulk blending machine systems are increasingly automated. Ultimately, whether your goal is a chemically granulated product requiring a precise npk fertilizer granulator or a simple physical blend, the principles of accurate batching and standardized operation are the keys to a consistent, high-quality final product.