Diammonium phosphate (DAP) is a white, water-soluble powder with the chemical formula (NH4)2HPO4. It has a density of 1.619 g/cm3 and melts at 155°C. DAP is manufactured using ammonia, phosphoric acid, sulfuric acid, and urea through a process involving granulation, drying, screening, and packaging in multi-wall bags. It is commonly used as a nitrogen-phosphate fertilizer to temporarily increase soil pH.

3. Properties
Chemical Formula (NH4)2HPO4
Molar Mass 132.06 g/mol
Appearance white powder
Density 1.619 g/cm3
Melting Point 155 °C (311 °F; 428 K)
decomposes
Solubility in Water 57.5 g/100 mL (10 °C)
106.7 g/100 mL (100 °C)
Solubility Nature insoluble
in alcohol,acetone and
liquid ammonia
Refractive index (nD) 1.52
Other anions: Monoammonium phosphate,Triammonium
phosphate
Other cations: Disodium phosphate, Dipotassium phosphate

4. RAW MATERIALS REQUIRED:
Diammonium phosphate with grade 18:46:0, industrial manufacturing process
requires five starting materials .
•Anhydrous liquid & vapour ammonia (99.5% pure NH3)
•Phosphoric acid (52-54% P2O5)
•Sulfuric acid (93-98% H2SO4)
•Urea prills (99% NH2CONH2)
•Filler

5. Product Specification:
•Moisture per cent by weight (Maximum) – 2.5%
•Total Nitrogen per cent by weight (Minimum) – 18%
•Ammoniacal nitrogen form per cent by weight (Minimum) – 15.5%
•Total Nitrogen in the form of Urea per cent by weight (Maximum) – 2.5%
•Neutral ammonium citrate soluble phosphates (P2O5) per cent by weight
(Minimum) – 46%
•Water soluble Phosphates (as P2O5) per cent by weight (Minimum) – 41%

6. Product Description :
•Contains the second most important primary nutrient element,
Phosphorous besides Nitrogen.(Nutrient:18% N, 46% P2O5).
•Unique black colour and uniform size granules.
•Contains micro nutrients such as iron and important plant nutrients
such as sulphur,
calcium,
magnesium,
nitrogen and
phosphate.

7. Chemical reaction take place in the diammonium phosphate
fertilizer manufacturing pre-neutraliser
•NH3+H3PO4 → NH4H2PO4 (Mono ammonium phosphate)
•NH4H2PO4 + NH3 → (NH4)2HPO4 (Diammonium phosphate)

8. Manufacturing Process:
The resulting boiling slurry from pre-neutraliser is fed on the rotating bed of
recycle material in a rotary drum granulator and therefore it is ammoniated to
1.8 to 1.85 moleration by sparging liquid ammonia through the formation of
recent granules bed in the granulator.
The moist granulated material discharged from granulator is dried in a rotary
dryer using hot-quenched gas to reduce the moisture content of the material
from about 3% to 1%.
 Cascade screen separated the dried material based on the size of granule
particles.

9. Manufacturing Process (Contd……..):
The screened out particles are cooled by the rotary drum cooler the inclined
rotation enhance huge quantity of hot granules to contact with cool air blown
counter currently from the outlet.
The oversize materials from the screens are pulverized and recycled to the
granulator.
The grade of the DAP is adjusted by addition of urea and filler.
Conveyor system transports the Diammonium phosphate fertilizer to the
bagging system.Scrubbing system traps the fumes obtained from the granulator
and pre-neutraliser and the dry scrubber cleans vent out air that carries the
fertilizer particles generated from pulverizers, screens and product cooler.
Finally tail gas scrubber further scrubbers the air before discharging it into the
atmosphere

12. Uses:
DAP is used as a fertilizer. When applied as plant food, it temporarily increases
the soil pH, but over a long term the treated ground becomes more acidic than before
upon nitrification of the ammonium. It is incompatible with alkaline chemicals because
its ammonium ion is more likely to convert to ammonia in a high-pH environment.
The average pH in solution is 7.5–8.
DAP can be used as a fire retardant. It lowers the combustion temperature of the
material.
DAP is also used as a yeast nutrient in winemaking and mead brewing.
as an additive in some brands of cigarettes purportedly as a nicotine enhancer.
to prevent afterglow in matches, in purifying sugar.
 as a flux for soldering tin, copper, zinc and brass.
 to control precipitation of alkali-soluble and acid-insoluble colloidal dyes on wool.

13. Handling,Storage and Packing:
 DAP usually do not create any problem in the atmosphere
and it is free flowing in nature.
Granulated DAP on the other hand can be easily handled
and uniformly distributed in the field.
 It is stored in air conditioned silos
 It is packed in multi-wall lined gunny bags (or) HDPE bags.