What are the raw materials for NPK fertilizer production line?

NPK fertilizer, a key type of compound fertilizer, simultaneously provides crops with three key nutrients: nitrogen (N), phosphorus (P), and potassium (K). The raw materials used in NPK fertilizer production line directly determine fertilizer quality and effectiveness. Understanding the characteristics of these raw materials is fundamental to mastering NPK fertilizer production technology.

Urea, ammonium chloride, and ammonium sulfate are commonly used nitrogen sources. Urea, with a nitrogen content of up to 46%, is easily soluble in water, and offers long-lasting fertilizer efficacy, making it one of the most widely used nitrogen sources and suitable for a wide range of soils and crops. Ammonium chloride, with a nitrogen content of approximately 25%, is relatively inexpensive, but due to its chloride ion content, caution is advised when using it in saline-alkali soils or for crops sensitive to chloride, such as tobacco and grapes. Ammonium sulfate, with a nitrogen content of approximately 21%, not only provides nitrogen but also supplements sulfur, making it suitable for sulfur-deficient soils. However, long-term use may cause soil acidification.

The phosphorus sources used in NPK fertilizer production lines primarily include monoammonium phosphate, diammonium phosphate, and superphosphate. Monoammonium phosphate (MAP) contains approximately 44%-46% phosphorus and 10%-12% nitrogen. Its water solubility allows for high crop absorption and utilization, making it a preferred phosphorus source for high-concentration NPK fertilizers. Diammonium phosphate (DAP) also offers excellent fertilizer efficiency, with a phosphorus content of approximately 42%-46% and a nitrogen content of 16%-18%. However, when applied to acidic soils, it should be combined with an alkaline fertilizer to prevent phosphorus fixation. Superphosphate (SP) has a lower phosphorus content of approximately 12%-20% and also contains impurities such as calcium and sulfur. It is commonly used in the production of medium- and low-concentration NPK fertilizers and is suitable for improving alkaline soils.

Potassium sources are primarily potassium chloride and potassium sulfate. Potassium chloride, with a potassium content of approximately 50%-60% and an affordable price, is a common potassium source for most crops, though chloride-sensitive crops should be avoided. Potassium sulfate, with a potassium content of approximately 45%-50% and no chloride ions, has a wider range of applications, particularly for chloride-sensitive crops such as tobacco and potatoes. However, its production cost is relatively high. NPK fertilizer production lines also require the addition of a small amount of auxiliary raw materials, such as fillers (talc, bentonite) to adjust the fertilizer's particle size and strength, and anti-caking agents to ensure the fertilizer maintains its optimal condition during storage and transportation. The optimal blend of these raw materials is crucial to producing high-quality NPK fertilizers, directly impacting crop growth and yield.