Download Uses of Phosphoric Acid

SAL College of Engineering
Department Of Chemical Engineering
ALA PRESENTATION
Subject: Chemical Process Industries 1
Topic: Manufacturing of Phosphoric Acid
Prepared By: Divya D Patel (131130105040)
Ketan B Patel (131130105042)
Guided By: Greeshma Nair
Introduction
 Phosphoric acid also known as orthophosphoric acid or
phosphoric(V) acid is a mineral (inorganic) acid having the
chemical formula H3PO4.
 Orthophosphoric acid molecules can combine with themselves
to form a variety of compounds which are also referred to as
phosphoric acids, but in a more general way.
The term phosphoric acid can also refer to a chemical or reagent
consisting of phosphoric acids, such as pyrophosphoric acid or
triphosphoric acid, but usually orthophosphoric acid.
 The concentration of phosphoric acid is normally expressed as
%P2O5(percent phosphoric anhydride) rather than % H3PO4
(percent phosphoric acid).
Properties of Phosphoric Acid
Molecular formula
H3PO4
Molar mass
98.00 g/mol
Density
1.885 g/ml (liquid)
Melting point
315.50 K (anhydrous)
302.47 K (hemihydrates)
Boiling point
431 K, 486 K
Decomposes
Solubility
Soluble in ethanol
Refractive index (nD)
1.34203
Viscosity
2.4-9.4 cP(85%aq. Soln.)
147 cP (100%)
Structure of Phosphoric Acid
H3PO4
Production
 Phosphoric
acid can be produced by 3 main
commercial methods:
1. Wet process
2. Thermal process
3. Dry kiln process
Wet Process:
Wet process is by far the most common route and the acid can be
used in phosphate fertilizers production. (DAP).
Thermal Process:
Thermal process phosphoric acid is of a much higher purity and
is used in the manufacture of high grade chemicals,
pharmaceuticals, detergents, food products, and other nonfertilizer
products.
Dry Kiln Process:
The last method, using a rotary kiln, is a promising alternative
because of its reduced environmental footprint and potential cost
saving.
The Full Manufacturing of
Phosphoric Acid by the Wet Process
Phosphoric acid is produced from fluorapatite, known as
phosphate rock, Ca3(PO4)2, by the addition of concentrated
(93%) sulfuric acid in a series of well-stirred reactors.
 This results in phosphoric acid and calcium sulfate
(gypsum) plus other insoluble impurities.
 Water is added and the gypsum is removed by filtration
along with other insoluble materials (e.g. silica).
Although the reaction takes place in stages involving calcium
dihydrogen phosphate, the overall reaction can be represented as:
Ca3(PO4)2 + 3H2SO4 + 6H2O
2H3PO4 + 3CaSO4·2H2O
The product from the 'wet process' acid is impure but can be used,
without further purification, for fertilizer manufacture (see below).
Alternatively it can be evaporated further to ca 70% P2O5, a
solution called super phosphoric acid which is used directly as a
liquid fertilizer.
To make industrial phosphates, the acid is purified by solvent
extraction using, for example, methyl isobutyl ketone (MIBK) in
which the acid is slightly soluble and concentrated to give 60%
P2O5 content.
This acid can be further purified using solvents to extract it from
heavy metals and defluorinated (by evaporation) to produce a
product of food grade quality.
Figure – Dependance of Calcium Sulphate Hydrate
Crystallisation on Temperature and P2O5.
Annual production of
Phosphoric Acid:
World
:
Europe
:
North America :
Asia
:
38 million tones
4 million tones
10 million tones
14 million tones
The Advantages of Wet Process in
Production of Phosphoric Acid:
 There is no phosphate rock quality limitation
 On-line time is high
 Operating temperatures are low
 Start-up and shut-down are easy
 Wet rock can be used (saving drying costs)
The Disadvantages of Wet
Process in Production of
Phosphoric Acid:
 Relatively weak product acid (26-32% P2O5)
High energy consumption in the acid concentration stage
4-6% P2O5 losses, most of them co-crystallised with the
calcium sulphate
Common Uses of Phosphoric Acid:
Uses of Phosphoric Acid:
Phosphoric acid is one of the most widely known and used acid. This
acid is also known as orthophosphoric acid and is a mineral acid.
Removal of Rust
Use in Processed Food
Medical Uses
Phosphoric acid is used as the electrolyte in phosphoric acid fuel cells.
As a catalyst in the hydration of alkenes to produce alcohols,
predominantly ethanol.
TECHNOLOGICAL STATUS OF INDIAN
INDUSTRY(CAPACITY IN TONNES P2O5)
Sr.
No.
Manufacture
Installed
Capacity
Process
Licensor
Engineering
Contractor
1
Paradeep Phosphates
Ltd. (under
construction)
2,25,000
Jacobs
International
Inc.
with Indian
associate
Hindustan Dorr
Oliver Ltd.
Hindustan
Dorr Oliver
Limited
2
FACT Limited,
Cochin
1,18,800
Societe-dePrayon
Belgium through
FEDO
3
Coromandel
Fertilisers Ltd.
91,000
Dorr Oliver,
USA
Dorr Oliver
USA
4
FACT Limited
Udyogmandal
33,000
Dorr
Oliver.U.S.A.
Hindustan
Dorr Oliver, Ltd
FEDO