2. Classification of Phosphate Based Fertilizers
Phosphate
Rock
Single Super
Phosphate
Direct Application Phosphoric Acid
Triple Super
Phosphate
Monoammonium
Phosphate
Diammonium
Phosphate
Nitric Acid
Potassium
NPK Compound
Fertilizer
Sulfuric Acid Sulfuric Acid
Phosphate Rock Ammonia Ammonia
3. Other Fertilizers Made From Phosphoric Acid
1. Ammonium Phosphate Sulphate (APS):
The best known grade is 16-20-0, which essentially consist of MAP and
ammonium sulphate (AS).
2. Ammonium Phosphate Chloride (APC):
Ammonium chloride is used in japan and some other countries, both as
straight nitrogen fertilizer and as an ingredient of NP (18-22-0) and NPK (14-
14-14) fertilizers.
3. Ammonium Phosphate Nitrate (APN):
Available in the grades of 25-25-0 and 30-10-0.
4. Urea-Ammonium Phosphate (UAP):
Ammonium phosphate is supplied either as slurry or in the solid form as MAP
or DAP. Urea is supplied as a solid, as a melt or as a concentrated solution.
UAP grades are 28-28-0,22-22-11,18-18-18.
4. 1. Principal fertilizer for more than a century and supplied over 60% of the
world’s phosphate as late as 1955.
2. It supplied only 20% of phosphate fertilizer in 1975.
3. In 1988, its supply was only 17%.
The advantages of SSP are
1. The process is simple, requiring little technical skill and small capital
investment.
2. SSP supplies two secondary elements, Sulphur and calcium, which are
sometimes deficient to soil.
Single Super Phosphate (SSP)
5. Overall Chemical Reaction:
Ca10F2(PO4)6 + 7H2SO4 + 3H2O 3Ca(H2PO4)2. H2O + 7CaSO4 + 2HF
Monocalcium
phosphate
monohydrate (MCP)
Calcium
Sulfate
(gypsum)
Single Super
Phosphate (SSP)
Chemical Properties:
• P2O5 content:
18 to 20%
• Calcium (Ca) content:
18 to 21%
• S content: 11 to 12%
Continued
6. Manufacturing
Process Steps:
1. Mixing of ground phosphate rock (90% < 100-mesh) with sulfuric acid (68-76%).
2. Solidification of the mixture.
3. Curing of the final product.
4. Granulation (if desired)
Batch Manufacturing of
Single Super Phosphate
Sulfuric Acid
Ground Phosphate Rock
Phosphate
Hopper
Pan Mixer
Acid Scale
Rock Scale
Den/Accumulator
Cutter
To Scrubbing System
(90% < 100-mesh)
(68-76%)
(0.5 – 4.0 hours)
(100 C)
(2 – 6 weeks)
Screening
(2 minutes)
Slurry
Storage Pile
(6 – Mesh Size)
5
7. Continuous Manufacturing of Single Super Phosphate
To Scrubbing System
Storage Pile
Phosphate
Rock
Rock
Storage
Silo
Bucket
Elevator
Surge
Hopper
Metering
Screw
Weigh Feeder
Water
H2SO4
Cone Mixer
Slat Conveyor
Continuous Den Belt Conveyor
8. Phosphate Rock (Direct Application)
Direct use of phosphate rock avoids the extra processing. The minimal
processing may results in a lower cost nutrient source and make it
acceptable for crop production systems.
To optimize the effectiveness of phosphate rock, consider these factors:
Soil PH: PRs require acidic soil conditions to effectively nourish crops.
It is usually recommended for the with the pH 6 or less.
Soil P-fixing capacity: The dissolution of phosphate rock increases
with the greater P-fixing capacity of soil.
Placement: Broadcasting phosphate rock and
incorporating it with tillage speed and reaction of
the soil.
Timing: The time required for the dissolution of
phosphate rock necessities its application in
advance of the plant demand.
9. Continued
Advantages:
1. The principal advantage of PR is its low cost.
2. A very low capital investment is required for processing.
3. Energy requirement is small.
4. No particular technical skill are required.
5. There is little or no loss in processing.
Disadvantages:
1. Relatively low P2O5 content as compared to TSP or ammonium
phosphates.
2. Less effective for short-season crops grown under cool soil temperature.
3. Effective only on the soils with pH 6 or less.
10. 4. Process step are similar to those of SSP, except that phosphoric acid is used
instead of sulfuric acid.
Triple Super Phosphate
1. Triple superphosphate (TSP) was one of the first high analysis P
fertilizers that became widely used in the 20th century. Technically, it
is known as calcium dihydrogen phosphate and as monocalcium
phosphate, [Ca(H2PO4)2 . H2O]. It is an excellent P source, but its
use has declined as other P fertilizers have become more popular.
2. It has the highest P content of dry fertilizers that do not contain N
3. It contains about 2.5 times of P2O5 content of SSP.
11. Overall Chemical Reaction:
Ca10F2(PO4)6 + 14H3PO4 + 10H2O 10Ca(H2PO4)2. H2O + 2HF
Monocalcium
phosphate
monohydrate (MCP)
Triple Super
Phosphate (TSP)Chemical Properties:
• P2O5 content:
42-50 %
• Calcium (Ca) content:
13.6%
• S content: 1.4 %
Continued
12. Process Steps:
1. Mixing of ground phosphate rock (95%-98% < 100-mesh) with phosphoric acid (52%).
2. Solidification of the mixture.
3. Curing of the final product.
4. Granulation (if desired)
TSP Production By Den Process
Phosphoric Acid
Phosphate
Hopper
Cone Mixer
Rock Scale
Den/Accumulator
Chain Mill
(95%- 98% < 100-mesh)
(52%)
(10 – 30 minutes)
(3 – 6 weeks) Screening
Storage Pile
(6 – Mesh Size)
Ground Phosphate Rock
To Scrubbing System
Run-of-pile TSP
/ ROP-TSP
13. Granulation Of Cured ROP-TSP
Bucket Elevator
Cured TSP
Belt
Feeder
Screen
Crusher
Bucket Elevator
Bucket Elevator
To Scrubbing System
Surge
Hopper
Weigh
Feeder
Water
Steam
Granulator
Dryer
Air
Fuel
Screen
Crusher
Belt Feeder
Recycle
Bucket Elevator
TSP
cooling
and to
Storage
14. Ex-Den Granulation of TSP
Ground Phosphate
Rock
Phosphoric Acid
Hopper
Mixer
Slat Conveyor
Continuous Den
Belt Conveyor
Bucket Elevator
Steam
Water
Gases to Scrubber
Granulator
Dryer Screen
TSP cooling and to
Storage
Bucket Elevator
Crusher
Recycle
15. Slurry Process For The Manufacturing Of Granular TSP
Steam Heated
Reactor
Ground Phosphate
Rock
Phosphoric Acid
Blunger / Rotary
Drum
Bucket Elevator Dryer
Bucket Elevator
Cyclone
Cyclone
Gases to Scrubber
Screen
Crusher
Cooler
Product to Storage
Recycle
Belt Conveyor
Retention Time (30 minutes)
(90C)
Recycle Ratio:
For Blunger =10-12:1
For Granulator =8:1
16. Ammonium Phosphates
Raw Materials:
1. Phosphoric Acid
2. Anhydrous Ammonia
3. Sulfuric Acid (Used for grade adjustment)
Chemical Reactions
MAIN REACTIONS
1. NH3 + H3PO4 (NH4)H2PO4 (MAP) + 32.18 Kcal/mole
2. NH3 + (NH4)H2PO4 (NH4)2HPO4 (DAP) + 18.10 Kcal/mole
SIDE REACTION
1. 2NH3 + H2SO4 (NH4)2SO4 + 65.44 Kcal/mole
17. Ammonium Phosphates
Standard Grades:
1. MAP
- 11 % Nitrogen and 55 % Phosphate (P2O5)
- 10 % Nitrogen and 50 % Phosphate (P2O5)
- 11 % Nitrogen and 52 % Phosphate (P2O5)
MAP Production Methods:
Forward Titration:
The Pre-neutralizer is operated at an NH3:H3PO4 mole ratio of 0.6 and the balance of
ammonia is added in the granulator.
Reverse Titration:
The Pre-neutralizer is operated at an NH3:H3PO4 mole ratio of 1.4~1.5 and the
phosphoric acid is added in the granulator to decrease the ratio to 1.
2. DAP
- 18 % Nitrogen and 46 % Phosphate (P2O5)
18. Ammonium Phosphates
DAP Production Processes:
1. TVA Basic Process (Pre-neutralizer Process)
2. AZF dual pipe-reactor Process (Pipe Reactor Process)
3. Jacobs Slurry Process (Combination of Pre-neutralizer and Pipe Reactor)
Reactor Granulator Dryer Screen Cooler
Product to
Conditioning and
StorageRecycle
Ammonia & Dust
Collecting System Air to Atmosphere
H3PO4
H2SO4
NH3
19. Ammonium Phosphates
Early Technology for the Manufacturing of MAP/DAP:
1. TVA Basic Process.
H3PO4
NH3
Pre-neutralizer
N/P = 1.4
NH3
16%-20%
Moist.
Solid Recycle
Granulator
Dryer
Scrubbing
System
Scrubbing
System
Cyclone
Cyclone
Screen
Crusher
Cooler
Belt Conveyor
To
Storage
Bucket Elevator
Bucket Elevator
N/P = 2.0
N/P = 0.6
N/P = 1.0
H3PO4NH3
Reverse TitrationForward Titration Recycle Ratio:
For DAP = 5:1
Solid Recycle
20. Ammonium Phosphates
2. AZF dual pipe-reactor Process.
NH3
Solid Recycle
Scrubbing
System
Cyclone
Primary
Screen
Crusher
Belt Conveyor
To
Storage
After
Cooling
Bucket Elevator
Granulator
Dryer
H3PO4
NH3
H3PO4
Solid Recycle
Granulator
Pipe Reactor
Dryer Pipe
Reactor
Scrubbing
Liquor
Polishing
Screen
N/P 1.0
N/P 1.4-1.6
NH3
N/P 1.90
Air
Fuel
Recycle Ratio = 3:1
21. Ammonium Phosphates
3. Jacobs Slurry Process.
Scrubbing
Liquor
Crusher
Cooler
H3PO4
NH3
H2SO4
Granulator
Dryer
NH3
Belt Conveyor
Solid Recycle
Air
Fuel
Pre-neutralizer
Polishing Screen
Primary
Screen
Cyclone
Solid Recycle
To Storage
To Scrubbing
To Scrubbing
System
To Scrubbing
System
Recycle Ratio = 4:1
N/P 1.4-1.5
N/P 1.45-1.6 N/P 1.80
22. NPK Compound Fertilizers
NPK fertilizers are three-component fertilizers providing nitrogen, phosphorus
and potassium.
Compound fertilizers are usually manufactured to meet local or regional
requirement.
Compound fertilizer contains multiple nutrients in each individual granule.
This differs from a blend of fertilizers mixed together to achieve a desired
average nutrient composition.
Common compound fertilizers include: 10-10-10, 12-12-12, 17-17-17, 21-7-
14, and many others formulations.
23. Continued
NPK fertilizers can be produced by several processes depending upon the raw
materials and equipment used.
i. Urea
ii. Ammonium Sulphate
iii. Diammonium Phosphate
iv. Monoammonium Phosphate
v. Potassium Chloride
vi. Potassium Shulphate
vii. Sulfuric Acid
viii. Phosphoric Acid
i. Pan Granulator
ii. Drum Granulator
iii. Pugmill or Blunger
iv. Compactor
Raw Materials: Granulation Equipment:
24. Pan Granulator
Pan granulator, granulates by giving adequate moisture and binder to a
powdered material in a tilted rotating pan.
Applications:
i. Chemical Powders
ii. Fertilizers
iii. Coal Fines
25. Drum Granulator
Granulation drums work by tumbling material in a rotating drum, typically in the
presence of a binder. The binder causes the fines to become tacky and allows
them to pick up additional fines, forming agglomerates.
Applications:
i. DAP & MAP
ii. NPK grades
iii. Ammonium Sulphates
iv. SSP
v. TSP
26. Pug mill or blunger
Pug mills utilize dual rotating shafts with paddles assembly to create a
kneading and folding over motion inside the trough. The action of the paddles
moves material from the bottom of the trough, up the middle, and back down
the sides to create an intimate mixture of materials.
27. Compactor
Compaction granulation is a dry particle size enlargement process in which
powdery material is pressed into sheets through the use of counter rotating
rolls.
Applications:
i. Fertilizers
ii. Pharmaceuticals
iii. Detergents
iv. Clay
v. Polymers
vi. Coal
28. NPK Compound Fertilizers
1. Ammonium phosphates are produced by mixing phosphoric acid and
anhydrous ammonia in a reactor to produce a slurry. (potassium and other
salts are added during the process.)
2. Compound fertilizer can be made by blending basic fertilizers such as
ammonium nitrate, MAP, DAP, and granular potash.
Hinweis der Redaktion
Introduction:
Production of fertilizer derived from phosphoric acid has increased significantly in the last 50 years because, these are high-analysis (A fertilizer that contains 30 percent or more of active ingredients) products.
Single Super Phosphate (SSP), also called normal or ordinary super phosphate, has been the principal phosphate fertilizer for more than a century and supplied over 60 % o the world’s phosphate as late as 1955. Since than its relative importance has declined steadily. In 1975 it supplied only 20% of the phosphate fertilizer, and this figure fell to 17% in 1988. For the world as a whole, TVA estimated 1972 SSP production at 7.87 million tonnes of P2O5, and IFDC mentions a figure of 7.083 million tonnes in 1988, which means a decrease of 10% over 16 years.
Economies of scale is the cost advantage that arises with increased output of a product. Economies of scale arise because of the inverse relationship between the quantity produced and per-unit fixed costs; i.e. the greater the quantity of a good produced, the lower the per-unit fixed cost
This material was once the most commonly used fertilizer, but other phosphorus (P) fertilizers have largely replaced SSP because of its relatively low P content.
The reaction proceeds in two stages: (1) the sulfuric acid reacts with the part of the phosphate rock, forming phosphoric acid and calcium sulfates and (2) phosphoric acid formed in the first step reacts with more phosphate roc, forming monocalcium phosphate. The two reactions take place concurrently, but first stage is completed rapidly while the second stage continues for several days or week.
The production of SSP involves the following three (or four) operations
The finely ground phosphate rock is mixed with the sulfuric acid having concentration about 68-76%. Pan mixer may have the capacity of 1 – 2 tones per batch.
The fluid material from the mixer goes to a den where it solidifies. A accumulator can hold 10 – 40 tonnes. The SSP is excavated from the den after 0.5-4.0 hours. At this time it is still somewhat plastic and its temperature is about 100C.
The product is removed from the accumulator and conveyed to the storage piles for final curing, which requires 2 – 6 weeks, depending on the nature and proportions of raw material and condition of manufacture. During curing reaction approaches completion. The free acid, moisture and unreacted rock contents decrease and the available and water soluble P2O5 increase. After curing the product is fed to a disintegrator, usually mill or cage mill. The product from the mill is discharge onto a screen of about 6-mesh size.
If granular SSP is desired, the product is granulated either before curing or after curing. Granulation before curing has the advantage that less water or steam is required. After granulation the product is dried and screened.
Product Properties:
At least 16% P2O5
93% water soluble
Granular 2 – 4 mm
FAO reports consumption of ground phosphate rock separately, in 1976 reported consumption was equivalent to about 5% of phosphate fertilizer consumption.
FAO reports consumption of ground phosphate rock separately, in 1976 reported consumption was equivalent to about 5% of phosphate fertilizer consumption.
In the era of 1953 the PRs consumption was more than 1 million tpy. In 1976 consumption amounted to only 37000 tpy. The decreased use was because of two factors. First, large scale production of high analysis phosphates (TSP and DAP). Secondly the granular phosphates are much easier to handle and apply to the soil than the finely ground PR.
This material was once the most commonly used fertilizer, but other phosphorus (P) fertilizers have largely replaced SSP because of its relatively low P content.
The reaction proceeds in two stages: (1) the sulfuric acid reacts with the part of the phosphate rock, forming phosphoric acid and calcium sulfates and (2) phosphoric acid formed in the first step reacts with more phosphate roc, forming monocalcium phosphate. The two reactions take place concurrently, but first stage is completed rapidly while the second stage continues for several days or week.
