Lecture Slides by Prof. Imitaz Ali at Ghulam Ishaq Khan Institute for Engineering Sciences and Technology (GIKI).

1. Fer lizers
Introduc on
A fer lizer is a material that furnishes one or more of the chemical
elements necessary for the proper development and growth of plants.
The most important fer lizers are chemical or mineral fer lizers,
manures, and plant residues.
Plant Nutrients
Chemical elements that are essen al for the proper development and
growth of plants are typically referred to as plant nutrients. sixteen.
Expression
Quan es or percentages of the primary nutrients in terms of elemental
nitrogen (N), phosphorus penta oxide (P2O5), and potassium oxide (K2O).
Secondary nutrients and micronutrients usually are expressed on an
elemental basis although calcium and magnesium some mes are
expressed in the oxide form.
However, several countries express all plant nutrients on an elemental
basis.

2. Introduc on

3. Introduc on
Fer lizer grade
All fer lizer labels have three bold numbers. The first number is the
amount of nitrogen (N), the second number is the amount of
phosphate (P2O5) and the third number is the amount of potash
(K2O). A bag of 10-10-10fer lizer contains 10% N, 10% P2O5 and
10% K2O
mixing two or more nutrient sources together to form a blend
mixed fer lizers
Nitrogen sources include ammonium nitrate (33.5-0-0), urea (46-0-
0), sodium nitrate (16-0-0) and liquid nitrogen (30-0-0).
Phosphorus is provided as 0-46-0 and potash as 0-0-60or 0-0-50
Introduc on
Terminology and Defini ons
Interna onal Associa on for Standardiza on (ISO) and Associa on of
American Plant Food Control Officials (AAPFCO)
Fer lizer (AAPFCO):
Contains important quan es of no more than one of the primary
plant nutrients (N, P, or K).
Has 85% or more of its plant nutrient content present in the form of a
single chemical compound.
Is derived from a plant or animal residue or by product or natural
material deposit which has been processed in such a way that its
content of plant nutrients has not been materially changed except by
purifica on and concentra on.
Soil Condi oner Material added to soils, the main func on of which is
to improve their physical and/ or chemical proper es and/ or their
biological ac vity.

4. Introduc on
Liming Material containing one or both of the elements calcium and
magnesium, generally in the form of an oxide, hydroxide, or carbonate, maintain
or raise the pH of soil.
Straight Fer lizer: nitrogenous, phospha c, or potassic fer lizer having a
declarable content of only one of the primary plant nutrients, i.e. nitrogen,
phosphorus, or potassium.
Compound Fer lizer: A fer lizer that has a declarable content of at least two of
the plant nutrients nitrogen, phosphorus and potassium, obtained chemically or
by blending or both.
Granular Fer lizer: formed into par cles of a predetermined mean size.
Coated Fer lizer Granular fer lizer that is covered with a thin of a different
material in order to improve the behavior and/ or modify the characteris cs of the
fer lizer.
Fer lizer unit The unit mass of a fer lizer nutrient (in the form of the element
or an oxide) generally 1 kg.
Plant Food Ra o The ra o of the numbers of fer lizer units in a given mass of
fer lizer expressed in the order N P K.

6. Fer lizers

7. EECA (Russia and Ukraine)
West Asia (Iran, Qatar, Saudi Arabia)

8. Sr. No. Name Loca on Product
1 Fauji Fer lizer Company Limited Plant I Rahim Yar Khan Urea
Plant II Rahim Yar Khan Urea
Plant III Mirpur Mathelo Urea
2 Fauji Fer lizer Bin Qasim Limited Plant I Bin Qasim Urea
Plant II Bin Qasim DAP
3 Engro Fer lizer Limited Plant I Dharki Urea
Plant II Bin Qasim NPK
Plant III Dharki Urea
4 Dawood Hercules Chemicals Limited Sheikhopura Urea
5 Fa ma Fer lizer Company Limited
(Pak Arab Fer lizer Limited)
Plant I Multan Urea
Plant II Multan NP
Plant III Multan CAN
6 Fa ma Fer lizer Company Limited Plant I Rahim Yar Khan Urea
Plant II Rahim Yar Khan CAN
Plant III Rahim Yar Khan NPK
7 Agritech Limited Mianwali Urea
8 Hazar Phosphate Fer lizers Limited Haripur SSP
9 Lyallpur Chemicals & Fer lizers Limited Jaranwala SSP
11 are in Punjab, 6 in Sindh and 1 in Khyber Pakhtunkhwa
Urea

9. Uses
Main N2 fer lizer
Ca le feed supplement (protein food supplements)
where it is cheap
As an ingredient in the manufacture of melamine
plas cs and various adhesives (Urea Formaldehye,
urea melamine formaldehyde)
in the manufacture of resins and coa ngs
Tex les an -shrink agents and ion exchange resins
intermediate in the manufacture of ammonium
sulfamate, sulfamic acid and pthalocyanines.
Urea produc on

10. Urea import
Companies
Engro Fer lizers Ltd (Engro UREA)
Fauji Fer lizer Company Ltd (Sona Urea)
Dawood Hercules (Bubber Sher)
Fa ma Fer lizer Company Ltd (Sarsabz Urea)
Agritech Ltd (Tara Urea)

11. Urea
Engro 2plants
FFC 4plants
Fa ma 2plants
Dawood 1plants
Agritech 1plants

12. Produc on
Reac on of ammonia and carbon dioxide at high pressure forming
ammonium carbamate, which is then dehydrated by applying heat,
forming urea and water:
2 NH3 + CO2 NH2COONH4 CO(NH2)2+ H2O
Both reac ons take place in the liquid phase in the same reactor
and are in equilibrium.
Reac on 1 is fast and exothermic and essen ally goes to
comple on under the industrial reac on condi ons used
Reac on 2 is slower and endothermic and does not go to
comple on
The conversion (on a CO2 basis) is usually in the order of 50 80 %.
The conversion increases with increasing temperature and NH3/CO2
ra o and decreases with increasing H2O/CO2 ra o.
Produc on
Equilibrium reac ons are
hydrolysis of urea:
CO(NH2)2 + H2O NH2COONH4 NH3 + CO2
The hydrolysis reac on takes place in the presence
of water. Acids or alkaline solu ons accelerate
hydrolysis
forma on of biuret:
2 CO(NH2)2 NH2CONHCONH2 + NH3
forma on of isocyanic acid:
CO(NH2)2 NH4NCO NH3 + HNCO

13. Urea Processes
Once Through
Par al recycle
Total recycle (All new plants)
Once through
The once through process is simplest and least expansive (both
capital and opera ng cost)
Least flexible and cannot be operated unless some provision is
made to u lize large amount of ammonia and off-gas.

14. Par al recycle
Part of the off gas is
recycled back to the reactor.
The amount of ammonia is
reduced to 15% to that of
once through that must be
used in other processes.
Investment cost is
somewhat lower than the
total recycle process, this
advantage apparently does
not compensate the
inflexibility arising from the
necessity to operate a co-
product plant with mutual
interdependency problems.
Total recycle
At an economical conversion rate of NH3 and CO2 to
urea, the process is designed to efficiently separate
urea from the other reac on components, to
recover excess NH3, and to decompose residual
ammonium carbamate to NH3 and CO2 for recycling
into the process.
This is usually realized by stripping (s ll at high
pressure) and subsequent depressurisa on/hea ng
of the urea solu on or combina ons of both.

15. Total recycle
Total recycling processes
Conven onal processes without stripping
CO2 stripping processes, e.g. Stamicarbon
NH3 stripping processes, e.g. Snamproge
Isobaric Double Recycling process (IDR), applying
stripping with NH3 and CO2, e.g. Montedison
Total recycle

16. Total recycle
All unconverted NH3 and CO2 is recycled back
to the reactor (99% conversion).
No nitrogen co-product is necessary.
Most flexible urea process as it depends only
NH3 and CO2 supply.
Most expensive in investment and opera ng
cost.

17. Urea Finishing Processes
Urea solu on from the synthesis/recycling stages of the
process is concentrated via evapora on or crystalliza on to a
urea melt for conversion to a solid prilled or granular product
for use as a fer lizer or technical grade.
Prilling:
Spinning bucket, shower head or acous c vibrators
All prilling tower have dust problem
Induced dra , forced dra or natural dra .
Inline cooling or fluidized bed cooling.
Granula on:
Less dust problem, uniform size, be er crushing
and impact, transport and handling strength.
Ammonium nitrate (AN)
& Calcium ammonium nitrate (CAN)

18. nitrogenous fer lisers
ammonium nitrate containing 33.5 34.5 %
nitrogen
calcium ammonium nitrate containing less than
28 % nitrogen.
The world produc on of ANs is es mated to
be 40 45 Mtonnes per year.
Fa ma Fer lizer Company Limited (Pak Arab Fer lizer Limited) Plant III Multan
Fa ma Fer lizer Company Limited Plant II Rahim Yar Khan
Ammonium nitrate
AN is produced by neutralizing 50 70 wt-% aqueous HNO3
with gaseous NH3
NH3 + HNO3 NH4NO3
The reac on is highly exothermic and proceeds rapidly. The
heat produced is o en used to generate steam.
The obtained AN solu on can be concentrated by
evapora on.
Most applied produc on processes comprise three main
opera ons: neutralisa on, evapora on and solidifica on
(prilling or granula on).

19. Ammonium nitrate
Neutralisa on is carried out in a two-stage
neutraliser operates with
low pH in the first stage (acidic condi ons)
neutral pH in the second stage.
The equipment can operate at a variety of
opera ng pressures and temperatures.
Pressure, temperature and concentra ons in
most neutralisers are linked by the boiling point
characteris cs of the AN solu ons, with only two
of these variables being independent.
Ammonium nitrate
The thermal instability of AN
requires:
small reactor volume
pure (chloride-free) nitric acid
avoidance of an excess of acid
Post treatment :
AN is highly hygroscopic
a apulgite, kieselguhr or clay are used
single-stage
or
two-stages

20. Calcium ammonium nitrate
CAN is a valuable source of nitrogen. As a fer lizer it can be
applied for all types of soil and all plants.
It is a nitrogen fer lizer supplying nutri ve elements (N as
NH4+ and NO3-, Mg and Ca as carbonates). It is suitable for
blending with other granulated fer lizers
Commonly used on fruit, process and vegetable crops
Calcium ammonium nitrate
ammonium nitrate solu on with powdered limestone
CAN is preferred to ammonium nitrate in acid soils
Calcium ammonium nitrate is obtained by
reac on of lump limestone with concentrated nitric acid
addi on of ammonia to neutralize excess of acid
evapora on of the resul ng solu on
prilling or flaking the melt
The resul ng product is a double salt, Ca(NO3)2NH4NO3 called calcium
ammonium nitrate
calcium ammonium nitrate granules are coated with thin layer of soap
stone powder, which; acts as a protec ve coa ng and prevents the
absorp on of moisture during storage and transporta on

21. Calcium ammonium nitrate
NH3 + HNO3 NH4NO3
CaCO3 + 2HNO3 Ca(NO3)2 + CO2 + H2O
__________________________________________________
CaCO3 + NH3+ 3HNO3 Ca(NO3)2 + NH4NO3 + CO2+H2O
Prilling process
1 to 3 % China clay, kieselghur or calcined fuller's earth is used to
condi on the prilled CAN.
Granula on process
Pug mill process
Drum process
Cold spherodizer pro

22. Single supper phosphate (SSP)
Hazar Phosphate Fer lizers Limited Haripur
Lyallpur Chemicals & Fer lizers Limited Jaranwala
Produc on
SSP is an excellent source of three plant
nutrients.
Phosphorous, Sulfur and Calcium
The manufacturing process depends on
reac ng phosphate rock with sulfuric acid and
the fer lizer contains about (16- 20 %) P2O5.
The net reac on proceeds as follows:
Ca3(PO4)2 + 2H2SO4 + H2 2PO4)2.H2O + 2CaSO4

23. Produc on
It is generally agreed that the reac on proceeds
in two stages:
sulfuric acid reacts with part of the rock, forming
phosphoric acid and calcium sulfate
The phosphoric acid formed in the first step reacts
with more phosphate rock, forming monocalcium
phosphate.
Two reac ons take place concurrently, but the
first stage is completed rapidly while the second
stage con nues for several days or weeks.
Produc on
Step 1
Finely ground phosphate rock (34% P2O5 content) is mixed with
sulfuric acid.
The acid usually is diluted to 68% - 75% H2SO4 before it is mixed with
the rock.
When concentrated sulfuric acid is diluted, much heat is generated;
many plants cool the acid in heat exchangers to about 70°C before use.
Step 2
The fluid material from the mixer goes to a den where it solidifies.
Solidifica on results from con nued reac on and crystalliza on of
monocalcium phosphate.
The superphosphate is excavated from the den a er 0.5 - 4.0 hours.
At this me it is s ll somewhat plas c, and its temperature is about
100°C.

24. Produc on
Step 3
The product is removed from the den and conveyed to storage piles for final curing,
which requires 2 6 weeks, depending on the nature and propor ons of the raw
materials and the condi ons of manufacture.
During curing, the reac on approaches comple on.
The free acid, moisture, and unreacted rock contents decrease, and the available and
water-soluble P2O5 contents increase.
The material hardens and cools.
A er curing, the product from storage is fed to a disintegrator, usually of the hammer
mill or cage mill type. The product from the mill is discharged onto an inclined screen of
about 6-mesh size.
The material that fails to pass the screen is returned to the mill for further grinding.
Step 4
If granular superphosphate is desired, the product is granulated either before or a er it
is cured. Granula on before curing has the advantage that less water or steam is
required.
A er granula on, the product is dried in a direct contact dryer and screened; the fines
are returned to the granula on unit.

25. Advantages
The process is simple, requiring li le technical skill and
small capital investment.
The economies of scale are minor; thus, small plants can be
economical.
Since the process is not capital intensive, there is li le
advantage of a high percentage u liza on of capacity.
In fact, many SSP plants operate on a planned seasonal
schedule.
The fer lizer effec veness of SSP is unques oned. In fact, it
is a standard of comparison for other phosphate fer lizers.
SSP supplies two secondary elements, sulfur and calcium,
which are some mes deficient in the soil.
H2SO4 (NH4)2SO4 20%N
ammonium sulfate
HNO3 NH4NO3 33%N
ammonium nitrate
CO2 (NH2)2CO 45%N
urea
H3PO4 NH4H2PO4 11-18%N
ammoniated phosphates
11-48-0
18-46-0
HNO3/rock phosphate nitric phosphates
NH3 +

26. Monoammonium phosphate (MAP)
& Diammonium phosphate (DAP)
Uses of MAP and DAP
Used as non-chloride N, P compound fer lizer
Used in manufacturing of yeast, vinegar, yeast
foods, and bread improvers
Used as a fire preven on agent for fabric,
mber and paper, as well as a fire preven on
coa ng, and dry powder for fire ex nguisher
For food grade, it is mainly used as a
fermenta on agent, nourishment agent

27. Produc on of MAP and DAP
Ammonium phosphates are manufactured by
reac ng anhydrous NH3 with H3PO4.
Types of ammonium phosphate which are
monoammonium phosphate (MAP, NH4H2PO4)
diammonium phosphate (DAP, (NH4)2HPO4)
Produc on of MAP and DAP
Monoammonium phosphate (MAP)
NH3 with H3PO4 gives MAP. It is a fer lizer or
fer lizer intermediate with high P2O5 content of
about 55% and nitrogen content 11-12%.
Diammonium phosphate (DAP)
With more ammonia, technical grade DAP
containing 16 -18% nitrogen and 46% P2O5 is
formed.

28. Produc on of MAP and DAP
The two principal steps are
Neutraliza on
Granula on
Reac ons
NH3 + H3PO4 NH4H2PO4
NH3 + NH4H2PO4 (NH4)2HPO4

29. TVA Process
Produc on of MAP and DAP
Neutraliza on
Quan es of NH3 with H3PO4 in the neutraliza on
step are different for MAP and DAP.
To manufacture MAP, NH3 / H3PO4 ra o is 0.6 in
the neutralizer and then 1.0 in the granulator.
While for DAP, NH3 / H3PO4 ra os are 1.4 and 1.0
in the neutralizer and granulator respec vely.

30. Produc on of MAP and DAP
Neutraliza on
The exothermic reac on heats the slurry nearly
to the boiling point (130°C).
Unreacted and excess NH3 vapor is collected from
the top and recharged for reducing NH3 losses
(less than 3%).
The hot slurry containing about 16 to 20% water
is pumped into the granulator, where more
ammonia is added to increase the molar ra o to
approximately 2.0.
Produc on of MAP and DAP
Granula on
Slurry from neutralizer is mixed with KCl and absorbed in a bed of
dry recycle fer lizer moving through a rota ng drum granulator.
This provides a tumbling ac on to coal recycle material with a slurry
film.
Drier reduces the moisture to less than 1%, with 10 minute contact
me with air ini ally at 1500C.
Dried product is separated into three frac ons on a double deck
screen.
A por on of the product from the deck of the lower screen is sent to
bagging opera ons.
The balance, together with pulverized oversize and fines, is returned
to the granulator.

31. Major engineering problem
Ammonia losses
Ammonia loss should be kept below 3%. It can be
achieved by using mul stage reactors along with
efficient recycling mechanism of collec ng the
vapour of ammonia from top of the
neutraliza on tower and recycle back to the
process.
Corrosion
Use of corrosion resistance material like SS316 for
hot acid and fumes ducts, carbon steel for
granula on, drying and screening