Manufacture of Diammonium Phosphate

Diammonium phosphate (DAP) is a synthetic compound that is widely used as a fertilizer due to its high phosphorous and nitrogen content. It is produced through a chemical manufacturing process that involves the reaction between phosphoric acid and ammonia. This process typically occurs in large-scale industrial plants.

The manufacture of diammonium phosphate involves several key steps:

1. Production of phosphoric acid: Phosphoric acid is the primary raw material used in the synthesis of DAP. It is usually derived from phosphate rock through a wet process. In this process, the phosphate rock is mixed with sulfuric acid to produce phosphoric acid.
2. Reaction between phosphoric acid and ammonia: The phosphoric acid is then reacted with anhydrous ammonia to form DAP. This reaction is exothermic and occurs in a reactor vessel. The temperature and pressure must be carefully controlled to optimize the reaction and ensure high product quality.
3. Purification and crystallization: The reaction mixture obtained from the previous step contains impurities that need to be removed. Purification is typically achieved by filtration or centrifugation. Once purified, the solution is concentrated through evaporation to promote crystallization of DAP. The crystals are then separated from the remaining liquid through filtration or centrifugation.
4. Drying: The separated DAP crystals are dried to remove any remaining moisture. This is usually done using a rotary dryer or a fluidized bed dryer. The moisture content needs to be reduced to a specific level to ensure the product's stability and longevity.
5. Granulation: The dried DAP crystals can be further processed into granules to improve handling and application. Granulation involves the agglomeration of the crystals using a granulation drum or a granulation pan. The resulting granules are then screened to achieve the desired size distribution.

The manufacturing process of diammonium phosphate requires careful control of various parameters such as reaction temperature, pressure, and impurity levels. Stringent quality control measures are implemented to ensure the final product meets the required standards. The produced DAP can then be packaged and distributed for agricultural use as a highly efficient and balanced fertilizer.