Method for preparing urea ammonium phosphate by employing multi-level neutralization and acidic slurry concentration

The invention discloses a method for preparing urea ammonium phosphate by employing multi-level neutralization and acidic slurry concentration. Wet dilute phosphoric acid with P2O5 content of 19% -38% is produced from mid-low-grade phosphate rock and used as raw material. The preparation method comprises steps of: settling the raw material diluted phosphoric acid and then neutralizing for the first time; concentrating the acidic slurry and then neutralizing for the second time; mixing urea and acidic ammonium phosphate slurry for reaction, and then granulating by drum ammoniation to obtain a finished product. The invention not only reduces the leakage of ammonia and consumption of urea, moreover, the urea ammonium phosphate product (27-27-0) prepared from mid-low-grade phosphate rock is close to product (28-28-0) prepared from high-quality phosphate rock. The invention is suitable for the mid-low-grade phosphate rock with high content of impurity, and also suitable for high quality phosphate rock to produce h