MANUFACTURING OF CEMENT
The manufacture of Portland cement is a complex process and done in the following steps: grinding the
raw materials, mixing them in certain proportions depending upon their purity and composition, and
burning them to sintering in a kiln at a temperature of about 1350 to 1500 ⁰C. During this process, these
materials partially fuse to form nodular shaped clinker by broking of chemical bonds of the raw materials
and recombined into new compounds. manufacturing and production of Portland Cement following
mineral materials are used: calcareous materials (limestone or chalk), argillaceous material (shale or
clay), blast furnace slag, silica sand, iron ore, and gypsum as raw material. There are two processes
known as “wet” and “dry” processes depending upon whether the mixing and grinding of raw materials
are done in wet or dry conditionsThe most common way to manufacture portland cement is through a dry
method.
There are four stages in the manufacture of portland cement:
(1) crushing and grinding the raw materials.
(2) blending the materials in the correct proportions.
(3) burning the prepared mix in a kiln.
(4) grinding the burned product, known as “clinker,” together with some 5 percent of gypsum (to control
the time of set of the cement).
DRY METHOD
This is the most common method in the manufacture of cement. because of the modem development of
the technique of dry mixing of powdered materials using compressed air. dry and semi dry processes for
manufacturing of cement, the raw materials are crushed dried and reduced to very fine powder-like and
fed in the correct proportions into a grinding mill. The raw materials are dried and reduced in size to a
fine powder in to grinding mill. The dry material undergoes a series of chemical reactions in the hottest
part of the kiln and some 20 to 30 percent of the material becomes liquid, and lime, silica and alumina
recombine. Mixing of Raw Materials : The raw materials i.e. argillaceous and calcareous materials
are undergo the following stages :-
Crushing : The raw materials , first of all , are broken in crushers to small fragments that
vary in size. for dry grinding the raw materials first may need to be dried in cylindrical,
rotary dryers.
, Drying: The crushed materials are dried by heating at a sufficiently high temperature. It
may be done in drying kilns. The temperature at the firing end ranges from about 1,350 to
1,550 °C
Reduction of size: The drying materials are then grind by using ball mills and tube mills to
reduce the size of materials to find powder.
Mixing in correct proportion : The finely dried materials are mixed in exact proportions .
The mixing may be done either mechanically or by pneumatic methods(eg. pumped under
pressure).
Burning and Grinding: These operations are same as for wet process. Except for the mixing of raw
materials. In the dry process, the raw materials mixed, fined and then fed into kiln whereas in the wet
process, the raw materials are crushed separately and then directly mixed in correct proportion in the
presence of water to make a fine thin paste known as Slurry.
WET PROCESS
When the raw materials are soft , then the wet process is preferably to be used. The cement is
manufactured by the following procedure:-
Mixing of Raw Materials:
1. In the wet process, there are two raw materials e. calcareous and argillaceous. Initially,
Calcareous materials are crushed using crushers and argillaceous material are washed With
water in the container.
2. After crossing the line stones are stored in silos similarly after washing the clay is stored in
basins.
3. The crushed materials from different silos and basins are drawn in correct proportions in a
channel called wet grinding mills. Both the materials are intimately mixed in the
presence of water and to form a fine thin paste known as slurry
4. Slurry is then stored in another silo may be called as slurry silo where it is constantly
stirred. The composition of raw materials is checked again and, if required, corrected by
adding clay or chalk materials as desires.
The manufacture of Portland cement is a complex process and done in the following steps: grinding the
raw materials, mixing them in certain proportions depending upon their purity and composition, and
burning them to sintering in a kiln at a temperature of about 1350 to 1500 ⁰C. During this process, these
materials partially fuse to form nodular shaped clinker by broking of chemical bonds of the raw materials
and recombined into new compounds. manufacturing and production of Portland Cement following
mineral materials are used: calcareous materials (limestone or chalk), argillaceous material (shale or
clay), blast furnace slag, silica sand, iron ore, and gypsum as raw material. There are two processes
known as “wet” and “dry” processes depending upon whether the mixing and grinding of raw materials
are done in wet or dry conditionsThe most common way to manufacture portland cement is through a dry
method.
There are four stages in the manufacture of portland cement:
(1) crushing and grinding the raw materials.
(2) blending the materials in the correct proportions.
(3) burning the prepared mix in a kiln.
(4) grinding the burned product, known as “clinker,” together with some 5 percent of gypsum (to control
the time of set of the cement).
DRY METHOD
This is the most common method in the manufacture of cement. because of the modem development of
the technique of dry mixing of powdered materials using compressed air. dry and semi dry processes for
manufacturing of cement, the raw materials are crushed dried and reduced to very fine powder-like and
fed in the correct proportions into a grinding mill. The raw materials are dried and reduced in size to a
fine powder in to grinding mill. The dry material undergoes a series of chemical reactions in the hottest
part of the kiln and some 20 to 30 percent of the material becomes liquid, and lime, silica and alumina
recombine. Mixing of Raw Materials : The raw materials i.e. argillaceous and calcareous materials
are undergo the following stages :-
Crushing : The raw materials , first of all , are broken in crushers to small fragments that
vary in size. for dry grinding the raw materials first may need to be dried in cylindrical,
rotary dryers.
, Drying: The crushed materials are dried by heating at a sufficiently high temperature. It
may be done in drying kilns. The temperature at the firing end ranges from about 1,350 to
1,550 °C
Reduction of size: The drying materials are then grind by using ball mills and tube mills to
reduce the size of materials to find powder.
Mixing in correct proportion : The finely dried materials are mixed in exact proportions .
The mixing may be done either mechanically or by pneumatic methods(eg. pumped under
pressure).
Burning and Grinding: These operations are same as for wet process. Except for the mixing of raw
materials. In the dry process, the raw materials mixed, fined and then fed into kiln whereas in the wet
process, the raw materials are crushed separately and then directly mixed in correct proportion in the
presence of water to make a fine thin paste known as Slurry.
WET PROCESS
When the raw materials are soft , then the wet process is preferably to be used. The cement is
manufactured by the following procedure:-
Mixing of Raw Materials:
1. In the wet process, there are two raw materials e. calcareous and argillaceous. Initially,
Calcareous materials are crushed using crushers and argillaceous material are washed With
water in the container.
2. After crossing the line stones are stored in silos similarly after washing the clay is stored in
basins.
3. The crushed materials from different silos and basins are drawn in correct proportions in a
channel called wet grinding mills. Both the materials are intimately mixed in the
presence of water and to form a fine thin paste known as slurry
4. Slurry is then stored in another silo may be called as slurry silo where it is constantly
stirred. The composition of raw materials is checked again and, if required, corrected by
adding clay or chalk materials as desires.
