Ammonium sulphate

1. AMMONIUM SULPHATE
Prepared by- Mr. Vishal B. Thakare
(M.Tech, Chemical SVNIT, Surat)
Assistant Professor, PARUL UNIVERSITY
Vadodara
vishalbt88@gmail.com

2. AMMONIUM SULFATE
 Ammonium sulfate containing 21% nitrogen is another important
nitrogenous fertilizer.
 MANUFACTURING METHOD
a) Flue Gas
Flue gases are source of the ammonium sulfate. The metallurgical
smelters and coal burning power plants liberate large quantities of SO2
that pollute the atmosphere. SO2 is collected and converted into sulfuric
acid, (NH4)2SO4 is then produced by passing ammonia gas through 60%
sulfuric acid placed in lead lines vats at about 60°C the crystals of
ammonium sulfate separate out on cooling.
2NH4OH + H2SO4 (NH4)2SO4 + 2H2O

3. b) As by-product from caprolactam
(NH4)2SO4 solution is formed during the manufacture of caprolactam. The
waste liquor containing 35% solution of ammonium sulfate is
concentrated, and ammonium sulfate, is recovered by crystallization,
centrifuging and drying. The crystals are dried after separation by
filtration or by centrifuge. The mother liquor overflowing from the
crystallizer is acidified and recycled to the absorber.
c) Direct neutralization or Synthetic manufacturing
2NH3 + H2SO4 (NH4)2SO4
Ammonia Sulphuric acid Synthetic ammonium sulfate
Ammonium sulfate made with manufactured ammonia and Sulphuric acid
is called synthetic ammonium sulfate

4. d) Gypsum Process
Raw materials
Ammonia ,CO2 Gypsum
Reaction
2NH3 + H2O + CO2 (NH4)2CO3
Ammonia Ammonium Carbonate
(NH4)2CO3 + CaSO4 (NH4)2SO4 + CaCO3
Ammonium Carbonate Gypsum Ammonium sulphate
CaCO3 CaO + CO2

6. Liquid ammonia and CO2 is absorbed in absorbing tower and form
ammonium carbonate at the pressure of about 2.1kg/cm2.
The prepared liquor strength corresponds to approximately 170gms
of ammonia and 225gms of CO2 per liter.
Natural gypsum or anhydrite, when used, is ground so that about
90% of the material passes through 120 mesh sieve.
When the byproduct gypsum of phosphoric acid plant is used, the
impurities are removed by repulping the filter cake prior to washing
and dewatering on a drum or disc filter.

7. Now proper proportion of finely ground gypsum or anhydrite is fed into
the aqueous solution of ammonium carbonate in large reactor, whereby
calcium carbonate is precipitated gradually as a result of double
decomposition.
Reactions of ammonium carbonate and gypsum solutions are carried out in
a series of wooden vessels or mild steel vessels having steam coils and
agitators to give a total retention time of 4 to 6 hours.
The slurry produced is vacuum filtered and the calcium carbonate cake
washed and dewatered.
The solution is evaporated and the crystals are centrifuged and dried in a
rotary drier at 1500oC to get ammonium sulphate crystal
CaCO3 obtained as by product is used as a raw material for the
manufacture of cement.