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GUJARAT TECHNOLOGICAL UNIVERSITY
Subject : Chemical Process
Topic : Ceramic Industries
Cement is a powdery substance made by calcining lime
and clay,mixed with water to form mortar and mixed with
sand to form concrete.
Manufacturing Process of Portland Cement
1.Calcareous materials:-CaO , Lime
2.Agrillaceous materials:-𝐴𝑙2 𝑂3 , 𝑆𝑖𝑂2
It involves the following steps:-
2.Mixing wet process
6. Storage and packaging
This is the first step in the manufacturing of Portland
Jaw crushers of various sizes are use for the crushing
Raw materials are crushed by crushers till the size of the
raw material reduces to ¾ of an inch.
It is then send for either wet process or dry process.
2.Mixing wet process:-
calcareous materials are crushed , powdered and stored
Argillaceous materials is mixed with water and washed.
Then it removes any adhering organic impurities.
Powdered, calcareous and washed argillaceous materials
are mixed in proper proportions to get a slurry.
This slurry is then fed into a rotary kiln.
Grinding can be done by the two stages.
Slurry is brunt in rotary kiln.
kiln is divided into three zones
1.Drying zone – 200-500°c
2.Calcinating zone – 1000°c
3.Clinkering zone – 1400-1600°c
1.Drying Zone :-
This is the upper part of the kiln.
Temperature is maintained about 200-500°c.
Most of water gets evaporated from the slurry by means
of hot gases.
This process is done in the middle portion of the kiln.
The temperature is maintained about 1000°c
Here in organic matter burns away and 𝐶𝑎𝐶𝑂3decomposes
to quick lime and 𝐶𝑂2 escapes away.
Materials forms small lumps formed.
𝐶𝑎𝐶𝑂3 CaO + 𝐶𝑂2
This is the lower portion of the kiln.
The temperature is between 1400-1600°c.
Here lime and clay nodules melts with chemical fusion and
gives calcium aluminates and silicates.
And then forms small hard stones called clinkers and then
cooled to form crystals.
2CaO + 𝑆𝑖𝑂2 𝐶𝑎2 𝑆𝑖𝑂4
3CaO+ 𝑆𝑖𝑂2 𝐶𝑎3 𝑆𝑖𝑂5
3Cao+𝐴𝑙2 𝑂3 𝐶𝑎3 𝐴𝑙2 𝑂6
4CaO+𝐴𝑙2 𝑂3 +𝐹𝑒2 𝑂3 𝐶𝑎4 𝐴𝑙2 𝐹𝑒2 𝑂12
Clinkers are finally grinded in the ball mill and tube mill
to a fine powder.
Cement is stored in bins from which it is fed to automatic
packing machines.Each bag usually contains 50 Kg of
Major Engineering Problems:-
Ceramic is an inorganic,nonmetallic solid prepared by the
action of heat and subsequent cooling.
Ceramic materials may have a crystalline or partly
crystalline structure, or may be amorphous(e.g. glass).
The word"ceramic" comes from the Greek word Keramos
means burnt stuff.
Earlier the term ceramic was applied to products made from
natural earth material that was not exposed to heat. But
nowadays the silicate mainly used in the construction
industries and prepared by burning the clay products are called
A broad sense classification divides the ceramic products in
to two classes
1.Heavy clay products e.g. bricks, roofing tiles, drain tiles,
hollow tiles, stoneware and refractories
2.Pottery products e.g. chinaware, wall tiles, electric
Ceramic may also be classified as
The porosity is depends on particle size, moulding pressure
and temperature of vitrification.
Further, ceramic may be classified based on the
method of production and its uses into
2.Structural clay products
4.Special ceramic products
The raw materials for ceramics are divided into
a)Plastics material such as clay
b)Fluxes such as feldspar
c)Non-plastics materials such as silica
a)Clay:-Clay gives the main body to the ceramics.
The advantage of using clay are it is plastic when mixed
with water becomes hard after drying and finally it becomes
irreversibly solid after firing.
Clay is chosen according to the requirements of particular
products and Is often blended.
Impurities in common clay incorporate specific qualities as
Iron oxide in common clay gives red colour to the burnt
Lime, magnesia, iron oxide and alkali oxides act as flux
which lowers the fusion point of clay.
Silica increases its porosity and refractory nature, while
Clay containing very little and good deals of silica known
as fire clays.
Feldspar is general name given to the group of minerals.
Flux materials like feldspar (Na2OAl2O3.6SiO2) which is
easily melting material decreases the melting point of sand or
quartz present in the ceramic body.
So, that after firing glass like material is obtained called as
vitrified material, which is highly impervious and stable to the
Fluxes are used for adding vitrifications, reducing porosity,
to increase the strength of cold articles and for bonding.
Feldspar is used as fluxing constituent in ceramic
formulations along with clay.
The common fluxing agents which lower the temperature
are borax, boric acid, soda ash, sodium nitrate, potassium
carbonate, calcined bones, lead oxides, lithium & barium
Type of feldspar
Soda feldspar Na2O.Al2O3.6SiO2
Lime feldspar CaO.Al2O3.6SiO2
c)Silica or quartz
The non-plastic or leading admixture like sand or quartz
gives strength to the body. It is incorporated in ceramic
formulation to reduce shrinkage and cracking which is occurs
during drying and firing.
Ceramic is one of the oldest materials used in
construction with the time quality and decoration has been
added to its property and therefore they are at present used
1. Construction and decoration as bricks and tiles
2. Metallurgy as construction material of furnace
3. Chemical products as stoneware and porcelain
4. In drainage of water
5. In sanitation
The small uses includes pottery work, specialty ceramic
like peuzo electric and insulation material in electrical
Therefore, we conclude that ceramics deals with
manufacture and technical characteristics and raw material
for article building.