This document discusses the cement manufacturing process. It describes how cement is made by quarrying raw materials like limestone and clay, grinding them into a slurry, and firing the slurry in a rotary kiln to form clinkers. The clinkers are then cooled, ground into a powder, and packaged. It also mentions cement industries located in Nagpur, India and concludes that cement is a key construction material used worldwide in structures.

1. Activity
On
Cement
Industries

2. Content
1.0 Introduction
1.1 Mortar and Concrete
1.2 Hydraulic and non hydraulic cement
1.3 Raw materials for Cement
Manufacturing
1.3.1 Chalk
1.3.2 Limestone
1.3.3 Clay component
1.3.4 Marls
1.4 Cement manufacturing process
1.4.1 The quarry
1.4.2 Making clinkers
1.4.3 Cooling of Clinkers
1.4.4 Grinding of clinkers
1.4.5 Packaging
1.5 Cement Industries in Nagpur
1.6 Conclusion
References

3. 1.0 Introduction
Cement is very important building material in
construction industry. It has replaced all other
building materials, like clay and lime, which ruled
high for centuries in construction.
Cement is now used in many construction
trade items like plain cement concrete, reinforced
cement concrete, mortar, plaster, grouts, paints and
in pre-cast elements. One of the characteristic of a
developed country is its growing infrastructure and
hence cement is an important element for the
development of country and its economy. As on
date natural materials like lime has many
limitations, while modern binder materials like
polymers, epoxy etc. are very costly and hence
cement is the best alternative.

4. 1.1 Mortar and Concrete
Cements may be used alone (i.e., “neat,” as grouting
materials), but the normal use is in mortar and
concrete in which the cement is mixed with inert
material known as aggregate. Mortar is cement
mixed with sand or crushed stone that must be less
than approximately 5 mm (0.2 inch) in size.
Concrete is a mixture of cement, sand or other fine
aggregate, and a coarse aggregate that for most
purposes is up to 19 to 25 mm (0.75 to 1 inch) in
size, but the coarse aggregate may also be as large
as 150 mm (6 inches) when concrete is placed in
large masses such as dams. Mortars are used for
binding bricks, blocks, and stone in walls or as
surface renderings. Concrete is used for a large
variety of constructional purposes. Mixtures of soil
and portland cement are used as a base for roads.
Portland cement also is used in the manufacture of
bricks, tiles, shingles, pipes, beams, railroad ties,
and various extruded products

5. 1.2 Hydraulic and non
hydraulic cement
Cements used in construction can be characterized
as being either hydraulic or non-hydraulic,
Depending upon the ability of the cement to set in
the presence of water .Non-hydraulic cement will
not set in wet conditions or underwater; rather, it
sets as it dries and reacts with carbon dioxide in the
air. It can be attacked by some aggressive chemicals
after Hydraulic cements (e.g., Portland cement) set
and become adhesive due to a chemical reaction
between the dry ingredients and water.

6. 1.3 Raw materials for Cement
Manufacturing
The first step in the manufacture of cement is to
combine a variety of raw ingredients so that the
resulting cement will have the desired chemical
composition. Since the final composition and
properties of cement are specified within rather
strict bounds, it might be supposed that the
requirements for the raw mix would be similarly
strict. Raw ingredients used to provide each of the
main cement elements are,

7. 1.3.1 Chalk
Chalk is a fine grained white
limestone or micrite. On
average, it consists of 97.5 –
98.5% .Calcium carbonate. Clay
and quartz are the most
common impurities. Most chalk
is soft friable rock that does not
required explosives in mining
1.3.2 Limestone
It is of predominantly fine
grained crystalline structure,
its hardness is between 1.8 to
3.0 of the scale of hardness
and specific gravity 2. To 2.8.
Limestone usually contains
admixtures of clay substance
or iron compounds, which
influences its color.
1.3.3 Clay Component
The second important raw material for cement
production is clay. The main component of clay is

8. formed by hydrous aluminium silicates.The
chemical composition of clay may vary from those
close to the pure clay, to that containing a
significant amount of admixtures as iron hydroxide,
iron sulfide, sand, calcium carbonate, etc.
1.3.4 Marls:
Limestone with admixtures of
silica, clay substance and iron
oxide are called marls. Marls
form the transition element
to the clay. Because of the
wide distribution of marls,
they are frequently used as
raw material for cement
production.

9. 1.4 Cement manufacturing
process
1.4.1 The quarry
Cement plants are usually located closely either to
hot spots in the market or to areas with sufficient
quantities of raw materials. The aim is to keep
transportation costs low. Basic constituents for
cement (limestone and clay) are taken from
quarries in these areas. Basically, cement is
produced in two steps:
1.4.2 Making clinker
So to make clinker there are three process:
Wet process
In the wet process, limestone is crushed into small
pieces. Then it is mixed with clay or shale and
water to form a slurry. The slurry contains about 35
to 40 percent water This slurry is then pumped into
slurry tanks or basins. Here, the slurry is kept
continuously agitated by blowing compressed air

10. into it. The chemical composition of the slurry is
kept as per the requirement by testing and making
corrections from time to time.
In a rotary kiln the slurry is then introduced into
the upper end of the rotary kiln. Rotary kiln is a
long steel cylinder, lined with refractory material,
fitted on roller bearings and capable of rotating
about its own axis. The length of the rotary kiln may
vary from 30 meters to 200 meters. The diameter is
about 3m to 8m. It rotates at a speed of 0.5 to 2
rpm. It is inclined at an angle of 3⁰-6⁰ . The kiln is
fired from the lower end by fuel ie. powdered coal.
The material slowly goes down towards the lower
end of the rotary kiln, and undergoes a series of
chemical reactions until finally, in the bottom most
part of the kiln, the oxides formed by the raw
materials combine to produce the clinkers

11. Dry process
The Cement Roasting Machine is the device to heat
and dry materials. The Materials in the coaxial type
roasting machine are roasted through retracing and
raising between the helical lobe and the
intermittent spiral plate. The sleeve structure of the
machine can severalfold shorten the length of
dryer, hereby the radiating surface and heat
consumption are significantly reduced, while the
increased heat exchange surface greatly enhance
thermal efficiency. As to the materials that could
not contact smoke, the multi drum cement roasting
machine is equipped with inside smokestacks and

12. ringlike smokestacks, and each smoke tube linked
through radial flue,
Reactions in the process:-
1.4.3 Cooling of clinkers
Clinkers are cooled with the help of cooler. The hot
clinkers are cooled by rotary coolers, where they
come in contact with cool air blown from the
opposite direction. The air cools the clinkers and
itself gets heated. Hot air thus produced is used
further for burning of coal or fuel. The quality of the
cement depends upon the rate of cooling of
clinkers.If the rate of cooling is slow then the

13. crystals of C2S are converted to fine powder and
have poor binding property. Such cooling results in
“dusting”. If the rate of cooling is fast then all
alumina and iron oxide solidify and crystals of C3A
and C4AF will not be formed. This affects the initial
setting of cement badly. If the rate of cooling is
medium than the formation of C3S takes place in
good amount which gives the highest strength to
the cement during setting and hardening.
1.4.4 Grinding of clinkers
Cooled clinkers are ground to fine powder in tube
mills or ball mills in the presence of additives.
During grinding 2-4% of gypsum is added.

14. 1.4.5 Packing
The finely powdered cement is first stored in
moisture free bags (known as silos) of 50 kg with
the help of machines. Wet Scrubbers are used.
Effluent possess high pH value, alkalinity,
suspended & dissolved impurities.
1.5 Cement Industries in
Nagpur

15. Cement Industries in Butibori

16. 1.6 Conclusion-
Cements are dry powders and should not be
confused with concretes or mortars, but they are an
important constituent of both of these materials, in
which they act as the ‘glue’ that gives strength to
structures. Mortar is a mixture of cement and sand
whereas concrete also includes rough aggregates;
because it is a major component of both of these
building materials, cement is an extremely
important construction material. It is used in the
production of the many structures that make up the
modern world including buildings, bridges,
harbors, runways and roads. It is also used for
facades and other decorative features on buildings.
The constant demand for all of these structures,
increasingly from the developing world, means that
cement is the second most consumed commodity in
the world after water.

17. References
 Energy and Environment by Dr. Kavita S Gour
and Mrs. Aditi Tulankar
 https://www.researchgate.net
 https://www.cementindusneed.com/raw-
materials/
 https://www.understanding-
cement.com/kiln.html
 Google maps