What is the correct production sequence for NPK fertilizer?
The industrial production of NPK compound fertilizer follows a fixed and rigorous standardized process. Each step is interconnected and directly determines the fertilizer's nutrient uniformity, granule quality, and storage stability. The standardized NPK fertilizer production sequence is: raw material pretreatment → precise proportioning and mixing → granulation and molding → drying and cooling → screening and coating → quality inspection and packaging. This orderly process is the core foundation for ensuring the finished fertilizer meets standards. Raw material pretreatment is the first step in production. Before production, the purity and quality of core raw materials such as urea, monoammonium phosphate, and potassium chloride must be verified, and impurities and lumps must be removed. Subsequently, the raw materials are pulverized to a standard fineness of 80 to 100 mesh using a pulverizer, and pre-drying is performed simultaneously to control the initial moisture content of t...