To stabilize the batching error and improve the nutrient qualification rate of the NPK blending fertilizer produciton line, improvements and optimizations should be made in four aspects: raw material control, equipment calibration, electrical control settings, and on-site management. First, ensure proper control of raw material warehousing. Urea, ammonium chloride, and potash fertilizer are prone to moisture absorption and clumping. Clumped materials should be crushed and screened beforehand. Large pieces blocking the material can cause inconsistent feeding, directly affecting metering. Raw materials should be stored in separate bins to avoid mixing and cross-contamination. Each raw material should have an independent bin to prevent cross-contamination during unloading.

Second, optimize the structure of the NPK blending machine. Install a variable frequency discharge screw at the hopper discharge port, replacing the old-style gate discharge. Variable frequency speed control allows for fast and slow feeding: large materials are fed quickly, while materials approaching the set weight are fed slowly, effectively reducing overshoot. Install a vibration anti-bridging device on the inner wall of the hopper to prevent material from being suspended and causing material shortages or under-weighing. Regularly calibrate the weighing sensors and clean fertilizer dust adhering to the scale body. Dust accumulation can change the zero-point value, causing continuous measurement deviations.

The electrical control system utilizes a PLC-based segmented batching program, setting individual drop compensation parameters for each raw material based on its flowability. Urea, with its rapid flow and large drop, has its compensation value adjusted separately. The scale is zeroed daily upon startup, and calibrated twice daily using standard weights. Dustproofing is ensured for belts and hopper seals, and moisture-corrosion-resistant sensors are promptly protected against corrosion.

Finally, standardized production operations are implemented to avoid arbitrarily changing raw material batches during production. Different manufacturers produce fertilizers of the same specifications with varying densities, and abruptly changing materials can easily lead to imbalances in the proportions. After optimization, the batching error per hopper can be controlled within ±0.3%, significantly increasing the nutrient content compliance rate of the finished product and reducing rework losses caused by improper proportions.