Cement manufacturing process

1. Universityof Sulaimani
College of Science
chemistry dept.
Cement manufacturing process
prepared by:
1-Haval Arf
2-Rawand Wahid

2. Cement and history
Cement is a common construction material, that hardens in the presence of water. Cement is used as a
binding material in mortar, concrete, etc.
Cement has been made since Roman times, but over time the recipes used to make cement have been
refined. The earliest cements were made from lime and pozzoulana (a volcanic ash containing significant
quantities of SiO2 and Al2O3) mixed with ground water. This cement was not improved upon until 1758,
when Smeaton noticed that using a limestone that was 20 - 25 % clay and heating the mixture resulted in a
cement that could harden under water. He called this new cement 'hydraulic lime

3. Types of cement
 Port land cement
 Natural cement
 Expansive cement
 High alumina cement

4. Cement production
 A cement production plant consists of the following three processes.
 1. Raw material process
 2. Clinker burning process
 3. Finish grinding process
 The raw material process and the clinker burning process are each classified into
the wet process and the dry process.

5. Dry process
 . In the dry process, crushed raw materials are dried in a cylindrical rotary drier having a
diameter of 2 m and a length of about 20 m for example, mixed by an automatic weigher,
ground and placed in storage tanks. The resultant mixture is further mixed to make the
ingredients uniform, and sent to a rotary kiln for clinker burning.
 In the dry process, there are the dry long kiln, the short kiln with boiler and the SP kiln.
The dry long kiln is mainly used in the Near and Middle East where rain falls less and
alkaline components in raw material are large; its characteristics are similar to the wet
process long kiln. A complex succession of chemical reactions take place as The formation
of clinker requires very high temperatures. Modern dry process cement plants use
preheater towers such as shown in Figure bellow to pre-process the kiln feed and thus save
energy. the temperature rises, converting the calcium and silicon oxides into calcium
silicates – cement's primary constituent.

6. At the lower end of the kiln, the raw materials
emerge as a new substance called clinker.

9. Wet process
 In the wet process, raw materials are crushed to a diameter of approximately 20 mm
by a crusher and mixed in an appropriate ratio using an automatic weigher, Then, with
water added thereto, the mixture is further made finer by a combined tube mill with
adiameter of 2 to 3.5 m and a length of 10 to 14 m into slurry with a water content of
35 to 40%. The slurry is put in a storage tank with a capacity of several hundred tons,
mixed to be homogenized with the corrective materials, and is sent to a rotary kiln for
clinker burning. In the wet process, the slurry can be easily mixed but a large amount
of energy is consumed in clinker burning due to water evaporation.

11. Portlant cement
 Portland cement was first produced commercially in 19th century in england.
Portland cement is currently defined as a mixture of argillaceous (i.e. clay-like) and
calcaneous (i.e. containing CaCO3 or other insoluble calcium salts) materials mixed
with gypsum (CaSO4⋅2H2O) sintered and then pulverised into a fine powder.
• A hydraulic cement made by finely pulverizing the clinker produced by
calcining to incipient fusion a mixture of argillaceous and calcareous materials
• Portland cement is the fine gray powder that is the active ingredient in concrete

12. concrete

13. Portlant cement
• Basic Chemical Components of Portland Cement:
 – Calcium (Ca)
 – Silicon (Si)
 – Aluminum (Al)
 – Iron (Fe)
• Typical Raw Materials:
 – Limestone (CaCO3)
 – Sand (SiO2)
 – Shale, Clay (SiO2, Al2O3, Fe2O3)
 – Iron Ore/Mill Scale (Fe2O3)

14. Portlant cement
• Calcareous Component
 (providing Lime - CaO)
 – limestone
 – marly limestone
 – chalk
 – coral limestone
 – marble
 – lime-sand
 – shell deposits
 – lime sludge
• Argillaceous Component
 (SiO2, Al2O3, and Fe2O3)
 – clay
 – shale
 – calcareous marl
 – marl
 – marly clay
 – tuff, ash
 – phyllite, slate
 – glass

15. Portlant cement
 • Clinker Chemistry
 – Tricalcium silicate (3CaO.SiO2), (50-70%)
 – Dicalcium silicate (2CaO.SiO2), (15-30%)
 – Tricalcium aluminate (3CaO.Al2O3), (5-10%)
 – Tetracalcium aluminoferrite (4CaO.Al2O3.Fe2O3), (5-15%)

24. Quarry
Crusher
Conveyor
Mixing bed
Raw mill
Filter
Preheater
Kiln
Cooler
Clinker silo
Cement mill
Logistics

25. Production of cement and environmental effect
In the cement manufacturing process many gas emmited (Nox, Co2, Sox…)and dust
of clinker.
Collection and recycling of dust in kiln gases is required to improve the efficiency of
the operation and to reduce atmospheric emissions. And
Using filter
Use low-NOx burners with the optimum level
of excess air.
• Use low sulfur fuels in the kiln.
• Operate control systems to achieve the required
emissions levels.

27. QUALITY TESTS OF CEMENT:

(1) Fineness Test, (sieving)
(2) setting time test ( needle)
(3)Compressive strength test

28. References:
1-European Community. 1989. “Technical Note on Best
Available Technologies Not Entailing Excessive Cost for the Manufacture of Cement.”
December 7. Paper presented to BAT Exchange of Information
2-Committee, Brussels.
Cement plant operation hand book 5th edition
3-http://www.ianr.unl.edu/pubs/farmbuildings/g623.htm
4-http://www.caricement.com
5-www.epa.gov/climatechange/emissions/ghgrulemaking.html