2026/06/18
NPK 25-10-10 is a high-nitrogen compound fertilizer with a total nutrient content of 45%, significantly higher than phosphorus and potassium. This formula is suitable for use as a base fertilizer or top dressing for gramineous field crops such as corn, wheat, and rice, as well as leafy vegetables. High nitrogen promotes rapid stem and leaf growth, while appropriate amounts of phosphorus and potassium ensure root development and lodging resistance. Due to the extremely high urea content (approximately 540 kg urea per ton of product), three major challenges must be addressed during production: preventing sticking to the wall, controlling melting, and gentle drying. The following is the complete process flow of a standardized production line with an annual capacity of 50,000 tons.
I. Raw Material Weighing: Precise Feeding for High-Nitrogen Formula
Typical raw materials for producing 25-10-10 include: urea (N≥46%), monoammonium phosphate (11-44-0 or 10-50-0), potassium chloride (K₂O≥60%), and a small amount of filler (such as clay or diatomaceous earth). Example Formulation (per ton of product): Urea approximately 543 kg, monoammonium phosphate (11-44-0) approximately 227 kg, potassium chloride approximately 167 kg, filler approximately 43 kg, plus 20-30 kg of bentonite as a binder and anti-sticking agent.
Weighing Equipment: Use a multi-compartment static electronic scale or a loss-in-weight belt scale, with a dynamic cumulative error ≤ ±0.5%. Urea is highly hygroscopic; the weighing compartment must be equipped with a vibration arch-breaking device and a dry air purging device.
Calibration Frequency: Calibrate the sensor every 50 tons to ensure nitrogen content deviation ≤ ±0.5%.
II. Mixing: Rapid, Uniform, and Moisture-Proof Both urea and potassium chloride are hygroscopic; the mixing process requires a closed and efficient system.
Equipment Selection: Double-shaft paddle mixer (mixing time 2 minutes) or twin-ribbon mixer (3 minutes), uniformity coefficient of variation (CV) < 10%. The mixing chamber is made of stainless steel, and a small amount of dry, hot air is introduced to prevent condensation.
Auxiliary Additives: Add 0.1% anti-caking powder (such as talc) and the aforementioned bentonite during mixing to reduce particle surface stickiness in advance.
III. Granulation: Steam Drum Granulation and Temperature Control for Anti-sticking High-nitrogen formulations are extremely sensitive to temperature. Urea begins to soften above 65℃, and melts and adheres to the drum wall in large quantities above 75℃. Therefore, the granulation process requires precise control.
Equipment Selection: Steam drum granulator, drum diameter 2.2-2.5m, rotation speed 12-14 rpm (slightly lower than conventional, reducing centrifugal material spillage). Introduce 0.25-0.4MPa saturated steam to strictly control the material temperature at 52-58℃.
Anti-sticking Measures: Install high-molecular-weight polyethylene lining plates on the inner wall of the drum; use multi-point distribution of steam nozzles to avoid localized overheating; spray anti-sticking oil (a mixture of waste engine oil and bentonite) once per shift.
Expected Granulation: Output particle size 2-4mm, granulation rate approximately 60%-65%. If the particles are too small or there is too much powder, the rotation speed can be slightly reduced or the steam pressure increased by 0.02 MPa.
IV. Drying and Cooling: Low Temperature and High Air Volume Preserve Particles
High-nitrogen particles easily form a hard shell on the surface and become porous internally after heating, even leading to urea decomposition. A low-temperature, high-air volume strategy must be used for drying.
Dryer: Counter-current rotary drum, inlet hot air temperature 130-150℃ (20-30℃ lower than conventional formulas), material temperature inside the drum not exceeding 55℃. After drying, the moisture content is reduced from 4%-5% to below 1.8%. Chain-type or L-shaped lifting plates are used to reduce adhesion to the walls.
Cooler: Rotary cooler, using forced cold air to cool to ≤35℃. High-nitrogen particles have a high specific heat capacity; insufficient cooling will lead to clumping and reduced strength after packaging.
Sieving: Double-layer grading sieve (upper layer 4mm, lower layer 2mm), qualified particles are 2-4mm. Oversized particles are crushed and returned to the granulator along with the fine powder.
V. Coating and Packaging: Moisture Protection and Stability The finished product is highly hygroscopic and requires strict coating and moisture-proof packaging.
Coating Machine: Small rotary drum, high-pressure atomization spraying of 0.3%-0.5% liquid anti-caking agent (mineral oil-based or polyether-modified silicone oil recommended).
The production of NPK 25‑10‑10 demands a systematic approach that integrates precise npk fertilizer formula processing with strict process control, from raw material weighing to final packaging. The core of the npk fertilizer manufacturing process lies in the steam drum granulation step, where the npk fertilizer granulator machine must operate at low temperatures (≤58°C) with anti‑sticking liners and precise steam distribution to prevent urea melt‑induced wall buildup. This granulation stage is embedded within a complete npk fertilizer production line that also includes low‑temperature drying (≤150°C), gentle cooling (≤35°C), and double‑layer screening to ensure uniform 2‑4 mm granules. Throughout the entire npk fertilizer manufacturing technology, every machine—from the twin‑shaft mixer to the rotary dryer, cooler, and coating drum—must be carefully selected and tuned to handle the hygroscopic, heat‑sensitive nature of high‑nitrogen formulas. The result is a stable, high‑efficiency line that consistently produces granules with moisture ≤1.8%, crushing strength ≥12N, and nutrient deviation within ±0.5%. By combining advanced npk compound fertilizer machine systems with real‑time process monitoring and automated control, manufacturers can overcome the challenges of urea‑rich formulations and deliver premium fertilizer that meets the demands of modern agriculture—supporting vigorous crop growth while ensuring excellent storage, handling, and application performance.
Summary: The core of the NPK 25-10-10 production line lies in "low-temperature granulation (≤58℃), low-temperature drying (≤150℃), and sufficient cooling (≤35℃)". Strict control of finished product moisture content ≤1.8% and particle strength ≥12N ensures stable production of high-nitrogen compound fertilizer that meets national standards. We specialize in the R&D and manufacturing of complete high-nitrogen compound fertilizer production lines. The NPK 25-10-10 formula is our mature solution—from low-temperature controlled melt granulation to gentle drying, sufficient cooling, and double moisture protection, we provide a one-stop supply of equipment for the entire process, ensuring your production line meets standards immediately upon commissioning.