The core points of pre-processing before NPK blending fertilizer produciton line are to ensure uniform particle size, controlled moisture content, and removal of impurities.  Specifically:

1. Raw material screening and impurity removal: Basic raw materials such as urea, potassium chloride, and monoammonium/diammonium phosphate are screened to remove impurities such as stones, metal fragments, and packaging bag fragments. This prevents damage to the conveying and mixing components of the NPK blending machine and prevents impurities from affecting the quality of the fertilizer product.

2. Particle size matching: Different raw materials are crushed to a uniform particle size range (usually 2-4mm). Excessive differences in particle size can lead to stratification during the blending process, affecting the uniformity of fertilizer efficacy; for raw materials that are prone to caking (such as urea and ammonium chloride), arch breaking and crushing treatment are required to ensure loose particles.

3. Strict moisture control: Control the moisture content of each raw material to within 2%-3%. Excessive moisture will cause the raw materials to clump and stick to the inner wall of the equipment, and will also reduce the uniformity of blending; if the moisture content of the raw materials exceeds the standard, low-temperature drying treatment is required to avoid high temperatures damaging the fertilizer nutrients.

4. Precise raw material metering: Calibrate metering equipment (such as electronic scales and hopper meters) in advance according to the formula ratio to ensure accurate and precise addition of raw materials such as urea, ammonium phosphate, and potassium fertilizer. This is a key prerequisite for ensuring that the NPK blended fertilizer meets nutrient standards and has a stable formula.