Raw Material Processing for NPK Fertilizer Production Lines: Sources, Scope, and Processing Technology

Raw materials are the foundation for producing high-quality NPK fertilizer. NPK fertilizer production lines utilize a wide range of raw materials from diverse sources, and their processing technology directly impacts fertilizer quality and production efficiency. Mastering the sources, classifications, and refined processing methods of raw materials is a core prerequisite for the stable operation of an NPK fertilizer production line. The core raw materials for NPK fertilizers are divided into three categories: Nitrogen sources mainly include urea (industrially synthesized, widely available), ammonium chloride (sea salt or coal chemical byproduct), and ammonium sulfate (steel plant desulfurization byproduct); Phosphorus sources are mainly monoammonium phosphate and diammonium phosphate, derived from acid hydrolysis after phosphate mining, with some companies using directly crushed phosphate rock powder; Potassium sources mainly include potassium chloride (sea salt or potash mining) and potassium sulfate (potassium chloride conversion or salt lake extraction). In addition, small amounts of trace elements (zinc, boron, molybdenum, etc.) and binders (bentonite, starch) need to be added. Raw material processing is the primary step in an NPK fertilizer production line, with standardized and rigorous operating procedures: The first step is screening, using a vibrating screen (0.5-1mm mesh) to remove impurities and stones from the raw materials, preventing damage to subsequent equipment. The second step is crushing, using a single-shaft urea crusher and fertilizer crusher to crush lumpy raw materials (such as urea and monoammonium phosphate) into 80-100 mesh powder, ensuring uniform mixing. The third step is drying, sending the crushed raw materials to a rotary drum dryer (temperature controlled at 80-100℃, speed 20r/min) to remove moisture to ≤5%, preventing clumping during batching. The key to raw material processing is meticulous control. For example, urea, after crushing, must be promptly sent to a buffer silo to prevent moisture absorption and clumping; phosphate rock powder requires acid hydrolysis pretreatment (adjusting the pH to 2-3 with sulfuric acid) to improve phosphorus utilization. Standardized raw material processing ensures smooth operation of subsequent batching and granulation processes, laying the foundation for producing high-quality NPK fertilizer.