2026/06/16
NPK 20-10-15 is a high-nitrogen, medium-phosphorus, and medium-potassium compound fertilizer formula, with a total nutrient content of 45%. This formula has a significantly higher nitrogen content than phosphorus and potassium, making it particularly suitable for leafy vegetables, corn, rice, and other crops with high nitrogen requirements. Due to its high nitrogen content and urea as the main raw material, the requirements for preventing sticking to the wall, controlling moisture, and adjusting temperature are more stringent during production. The following is the complete process flow of a standardized production line with an annual output of 50,000 tons.
I. Raw Material Weighing: Precise Feeding of High-Nitrogen Formula
The typical raw material combination for NPK 20-10-15 is: urea (N≥46%), monoammonium phosphate (11-44-0 or 10-50-0), potassium chloride (K₂O≥60%), and a small amount of filler and regulator.
Example Formulation (per ton of product): Urea approximately 435 kg, monoammonium phosphate (11-44-0) approximately 227 kg, potassium chloride approximately 250 kg, filler (such as clay or diatomaceous earth) approximately 68 kg, plus 20-30 kg of bentonite as a binder.
Weighing Equipment: Use a multi-compartment static electronic scale or a loss-in-weight belt scale, with dynamic cumulative error controlled within ±0.5%. In high-nitrogen formulations, urea constitutes a large proportion, and its flowability is significantly affected by humidity; therefore, the weighing compartment must be equipped with a vibration-damping device.
Calibration Frequency: Calibrate the sensors every 50 tons produced to ensure that the nitrogen, phosphorus, and potassium content deviations do not exceed ±0.5%.
II. Mixing: Moisture Absorption Prevention and Uniformity
Because both urea and potassium chloride are highly hygroscopic, the mixing process must be rapid and sealed.
Equipment Selection: Twin-shaft paddle mixer or horizontal ribbon mixer, mixing time 2-3 minutes, uniformity coefficient of variation (CV) < 10%. The mixing chamber should be made of stainless steel and fitted with a sealed cover to prevent ambient moisture from entering.
Auxiliary Addition: Add 0.1%-0.2% of anti-caking powder (such as talc or modified zeolite powder) during the mixing stage to reduce the surface activity of the particles in advance.
III. Granulation: Steam Drum Granulation and Anti-sticking High-nitrogen formulations tend to have urea easily melt and adhere to the drum wall during granulation, thus requiring a higher standard for the granulator.
Equipment Selection: A steam drum granulator is recommended, with a drum diameter of 2.2-2.5 meters and a rotation speed of 12-15 rpm. Introduce 0.3-0.5 MPa saturated steam to control the material temperature at 55-60℃ (3-5℃ lower than conventional formulations to prevent excessive softening of urea).
Anti-sticking Measures: Install a high-molecular-weight polyethylene liner on the inner wall of the drum or periodically spray an anti-sticking agent; simultaneously maintain a filling rate of 15%-18% to avoid excessive material accumulation.
Granulation Expectations: The output particle size should be concentrated between 2-4mm, with a granulation rate of approximately 65%-70%. If the particles are too small or there is too much powder, the rotation speed can be appropriately reduced by 1-2 rpm or the steam volume increased.
IV. Drying and Cooling: Low-Temperature, High-Volume Strategy
High-nitrogen granules are heat-sensitive; a low-temperature, high-volume process must be used during the drying stage to prevent urea decomposition or surface hardening of the granules.
Dryer: Counter-current rotary drum; inlet hot air temperature 140-160℃ (lower than the conventional 180℃); material temperature inside the drum should not exceed 65℃; moisture content after drying should be reduced from 4%-5% to below 1.8%. Chain-type or L-shaped lifting plates are recommended to reduce material adhesion to the walls.
Cooler: After drying, the granules enter a rotary cooler and are cooled to ≤40℃ with ambient air. Insufficient cooling will lead to clumping after packaging; in severe cases, residual thermal stress inside the granules will reduce their strength.
Sieving: 2-4mm qualified granules are separated by a double-layer grading sieve (upper layer 4mm, lower layer 2mm). Large particles are crushed and returned to the granulator along with fine powder for reuse.
V. Coating and Packaging: Double Anti-caking To address the hygroscopic nature of high-nitrogen products, a two-stage anti-caking treatment is recommended.
First Coating: At the cooler outlet, spray 0.2%-0.3% liquid anti-caking agent (mineral oil-based or polyether-modified silicone oil) using a high-pressure nozzle.
Second Coating: Line the packaging bag with a PE moisture-proof film and use a heat-sealing process.
Packaging Specifications: Commonly used are 25kg or 50kg woven bags, clearly marked with "Moisture-proof and Sun-proof".
The successful production of NPK 20-10-15 highlights the sophistication of modern npk fertilizer manufacturing process, where every stage—from raw material intake to final bagging—must be precisely orchestrated. It all begins with npk fertilizer raw materials processing: urea, monoammonium phosphate, potassium chloride, and conditioners are accurately weighed and mixed in sealed ribbon blenders to prevent moisture absorption, forming the backbone of the high‑nitrogen formula. This prepared mixture then enters the core of the npk fertilizer production line – the npk fertilizer granulator machine (steam rotary drum granulator) with anti‑stick liners, low‑temperature steam control, and a gentle rolling action that creates uniform 2‑4 mm granules. After drying, cooling, and precise sieving, the granules are perfectly suited not only for compound fertilizers but also for downstream npk bulk blending machine or BB fertilizer blender applications, where uniform particle size distribution guarantees no segregation during blending. Throughout the entire npk fertilizer formula processing, strict parameters (granulation temperature ≤60°C, drying inlet air ≤160°C, final moisture ≤1.8%) ensure high particle strength and nutrient accuracy. The integrated use of advanced npk compound fertilizer machine systems – including twin‑shaft mixers, low‑temperature dryers, dual‑coating drums – transforms challenging hygroscopic formulas into premium, free‑flowing granules. Whether you are establishing a dedicated NPK 20‑10‑15 line or upgrading an existing facility, mastering the synergy between raw material preprocessing, steam granulation, and anti‑caking coating enables stable production of high‑quality compound fertilizer with nutrient deviation below 0.5% and crushing strength ≥14N. With complete process control from npk fertilizer raw materials processing to final double‑coated packaging, manufacturers can achieve consistent, pearl‑like granules that stand out in the competitive market – delivering both agronomic efficiency and excellent handling properties.
Summary: The NPK 20-10-15 production line uses "precise weighing—rapid mixing—low-temperature steam granulation—gentle drying—double anti-caking" as its core control logic. Special attention should be paid to ensuring the granulation section temperature does not exceed 60℃, the drying section air temperature does not exceed 160℃, and the finished product moisture content is controlled below 1.8%. This ensures the stable production of high-quality compound fertilizer with a particle strength ≥14N and a nutrient deviation qualification rate ≥97%. If you are planning to build a high-nitrogen compound fertilizer production line, please contact us. We provide complete sets of high-nitrogen formula equipment and process optimization solutions, such as NPK 20-10-15, equipped with steam drum granulators, low-temperature high-volume drying systems, and dual anti-caking coating devices. Our professional team is on-site for commissioning, helping you to stably produce high-quality compound fertilizer with a particle strength ≥14N and a nutrient deviation ≤0.5%.