How to make NPK compound fertilizer 17:17:17

NPK17:17:17 compound fertilizer is a balanced fertilizer commonly used in agricultural production. Every 100 kg of finished product must contain precisely 17 kg of nitrogen (N), 17 kg of phosphorus pentoxide (P₂O₅), and 17 kg of potassium oxide (K₂O). Its production requires strict raw material ratios and specialized equipment operation. It's difficult for individuals to achieve industrial standards, and it requires standardized industrial processes.

Raw material selection and dosage calculation must be carefully tailored to crop needs and raw material characteristics. Urea (nitrogen content 46%, easy to dissolve, and fast fertilizer effect) is the preferred raw material for nitrogen. If it is aimed at sulfur-loving crops, it can be partially replaced with ammonium sulfate (nitrogen content 21% with sulfur). Monoammonium phosphate (containing 55% P₂O₅ and 11% nitrogen, which can reduce the amount of nitrogen source used) is commonly used for phosphorus. If a higher nitrogen content is required, diammonium phosphate (containing 46% P₂O₅ and 18% nitrogen) can be used. As for potassium, potassium chloride (containing 60% K₂O, low cost) is used for crops that are not sensitive to chlorine, while potassium sulfate (containing 50% K₂O, wide applicability) is required for crops that are sensitive to chlorine. For example, to produce 100 kg of finished product using a mixture of urea, monoammonium phosphate, and potassium sulfate: First, based on phosphorus requirements, calculate the required monoammonium phosphate (MAP) to approximately 30.91 kg (which also provides 3.4 kg of nitrogen). Then, divide the remaining nitrogen requirement (17-3.4 kg) by the nitrogen content of urea to arrive at approximately 29.57 kg of urea. Finally, based on potassium requirements, calculate the required potassium sulfate to 34 kg. The remaining 5.52 kg is filled with talc or bentonite to ensure accurate nutrient concentration.

In industrial production, various specialized equipment perform their respective functions. During the raw material pretreatment stage, bulk raw materials such as monoammonium phosphate are first crushed in a half-wet material crusher and then screened through a vibrating screen to ensure that the particle size meets the 80-100 mesh standard to prevent uneven mixing. A double axis mixer is used to mix the nitrogen, phosphorus, and potassium raw materials and fillers in appropriate proportions for 15-20 minutes. A double-helix staggered mixing structure ensures uniform distribution of the ingredients. Granulation is performed using either a rotary drum granulator (suitable for large-scale production, where the rotating drum aggregates the powder into 2-4 mm granules) or an double roller press granulator (which produces high granular hardness and is suitable for small-batch customization) depending on the needs. During drying and cooling, the wet granules first enter a drum fertilizer dryer, where they are dried at 80-120°C to a moisture content of less than 1% to prevent clumping. They are then rapidly cooled to room temperature in a cooler to prevent the high temperature from affecting nutrient content. Finally, a vibrating screen is used to remove oversized and undersized particles. Qualified products are weighed and sealed by an automatic quantitative packaging machine, and labeled with the nutrient content and production date.

Two points should be noted during the production process: First, the compatibility of the raw materials. For example, urea and ammonium nitrate are prone to moisture absorption and agglomeration when mixed, so they should be avoided, and the ambient humidity should be controlled below 50% throughout the process. Second, equipment maintenance should be carried out by regularly cleaning the crusher screen and residual materials on the inner wall of the mixer to ensure stable equipment operation and ultimately produce NPK17:17:17 compound fertilizer that meets the standards.