© Ahmed Al Malik, Lab Engineer, UOG Page 1

Ordinary Portland Cement

Prepared by; Lab Engineer

Ahmad Al Malik

© Ahmed Al Malik, Lab Engineer, UOG Page 2

Introduction(1)

Cement is a powdery substance made by calcining lime and clay, mixed with water to form

mortar or mixed with sand, gravel, and water to make concrete.

Cement is made by grinding together a mixture of limestone and clay, which is then heated at a

temperature of 1,450°C. What results is a granular substance called "clinker," a combination of

calcium, silicate, alumina and iron oxide.

HISTORICAL BACKGROUND(2)

The term cement is commonly used to refer to powdered materials which develop strong

adhesive qualities when combined with water. These materials are more properly known as

hydraulic cements. Gypsum plaster, common lime, hydraulic lime, natural pozzolan, and

Portland cements are the more common hydraulic cements, with Portland cement being the most

important in construction.

Cement was first invented by the Egyptians. Cement was later reinvented by the Greeks and the

Babylonians who made their mortar out of lime. Later, the Romans produced cement from

pozzolan, an ash found in all of the volcanic areas of Italy, by mixing the ash with lime.

Cement is a fine grayish powder which, when mixed with water, forms a thick paste. When this

paste is mixed with sand and gravel and allowed to dry it is called concrete.

About ninety-nine percent of all cement used today is Portland cement. The name Portland

cement is not a brand name. This name was given to the cement by Joseph Aspdin of Leeds,

England who obtained a patent for his product in 1824. The concrete made from the cement

resembled the color of the natural limestone quarried on the Isle of Portland in the English

Channel. The balance of cement used today consists of masonry cement, which is fifty percent

Portland cement and fifty percent ground lime rock.

The first cement manufactured in the United States was produced in 1871 by David Saylor of

Coplay, Pennsylvania.

Type of cement(3)

I. Ordinary Portland cement (Type I)

II. Modified Portland cement

III. Rapid Hardening or High Early Strength Portland cement (Type III)

IV. Quick Setting Cement

V. Low Heat Portland cement (Type IV)

VI. Sulphate Resistant Portland cement (Type V)

VII. Water Repellent Portland cement

© Ahmed Al Malik, Lab Engineer, UOG Page 3

VIII. Water Proof Portland cement

IX. High Alumina Cement

X. Portland Slag Cement

XI. Air Entraining Portland cement (Type I-A, II-A, III-A)

XII. Pozzolan Portland cement

XIII. Supersulphated Cement

XIV. Masonry Cement

XV. Expansive Cement

1. Ordinary Portland Cement

It is used in general construction works. All other varieties of Cement are derived from this

Cement.

White Cement o OPC with pure white color produced with white chalk or clay free from iron

oxide. .

o Much more costly than OPC. Colored Cement

o Suitable pigments used to impart desired color.

o Pigments used should be chemically inert and durable under light, sun or weather.

2. Modified Portland cement

This cement on setting develops less heat of generation than OPC.

It is best suited in hot climate for civil works construction.

3. Rapid Hardening or High Early Strength Cement (Type

III)

Gains strength faster than OPC. In 3 days develops 7 days strength of OPC with same

water cement ratio.

o After 24 hours – not less than 160 kg/cm2

o After 72 hours – not less than 275 kg/cm2

Initial and final setting times are same as OPC.

Contains more tri-calcium silicate (C3S) and finely ground.

Emits more heat during setting, therefore unsuitable for mass concreting.

Lighter and costlier than OPC. Short curing period makes it economical.

Used for structures where immediate loading is required e.g. repair works.

© Ahmed Al Malik, Lab Engineer, UOG Page 4

4. Quick Setting Cement

Sets faster than OPC.

Initial setting time is 5 minutes.

Final setting time is 30 minutes.

Used for concreting underwater and in running water.

Mixing and placing has to be faster to avoid initial setting prior to laying.

5. Low Heat Cement

Low percentage (5%) of tri-calcium aluminates (C3A) and silicate (C3S) and high (46%)

of di-calcium silicate (C2S) to keep heat generation low.

It has low lime content and less compressive strength.

Initial and final setting times nearly same as OPC.

Very slow rate of developing strength.

Not suitable for ordinary structures.

o Shuttering required for long duration so cost will increase.

o Prolonged curing is required.

o Structure utilization will be delayed.

6. Sulphate Resistant Portland cement

Percentage of tri-calcium Aluminate (C3A) is kept below 5% resulting in increase in

resisting power against sulphates.

Heat developed is almost same as Low Heat Cement.

Theoretically ideal cement. Costly manufacturing because of stringent composition

requirements.

Used for structures likely to be damaged by severe alkaline conditions like bridges,

culverts, canal lining, siphons, etc.

7. Water Repellent Portland cement

It contains a small percentage of water-proofing material with the cement and is

manufactured under the name “Aqua-crete”.

The cement is prepared with ordinary or rapid hardening cement and white cement.

It is used in to check moisture penetration in basements etc.

8. Water Proof Portland cement

It is prepared by mixing ordinary or rapid hardening cement and some percentage of

some metal stearate (Ca, Al etc).

It is resistant to water and oil penetration.

It is also resistant to acids, alkaline and salt discharged by industrial water.

It is used for water retaining structure like tanks, reservoir, retaining walls, pool, dam etc

© Ahmed Al Malik, Lab Engineer, UOG Page 5

9. High Alumina Cement

Black chocolate color cement produced by fusing bauxite and limestone in correct

proportion, at high temperature.

Resists attack of chemicals, Sulphates, seawater, frost action and also fire. Useful in

chemical plants and furnaces.

Ultimate strength is much higher than OPC.

Initial setting time is 2 hours, followed soon by final setting.

Most of the heat is emitted in first 10 hrs. Good for freezing temperatures in cold regions

(below 18°C).

Develops strength rapidly, useful during wartime emergency.

Unsuitable for mass concrete as it emits large heat on setting.

10. Portland Slag Cement

Produced by mixing Portland cement clinker, gypsum and granulated blast furnace slag.

Cheaper than OPC, blackish grey in color.

Lesser heat of hydration. Initial setting in 1 hr and final setting 10 hrs.

Better resistance to soil agents, sulphates of alkali metals, alumina, iron and acidic

waters.

Suitable for marine works, mass concreting.

Due to low early strength, not suitable for RCC.

11. Air Entraining Cement

OPC with small quantity of air entraining materials (resins, oils, fats, fatty acids) ground

together.

Air is entrained in the form of tiny air bubbles during chemical reaction.

Concrete is more plastic, more workable, more resistant to freezing.

Strength of concrete reduces to some degree.

Quantity of air entrained should not be more than 5% to prevent excess strength loss.

12. Portland Pozzolan Cement

OPC clinker and Pozzolan (Calcined Clay, Surkhi and Fly ash) ground together.

Properties same as OPC.

Produces less heat of hydration and offers great resistance to attacks of Sulphates and

acidic waters.

Used in marine works and mass concreting.

Ultimate strength is more than OPC but setting timings are same as OPC.

© Ahmed Al Malik, Lab Engineer, UOG Page 6

Ordinary Portland cement

It is most common type of cement and often referred to as OPC orOrdinary Portland Cement It is

a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount

of calcium sulfate (which controls the set time) and up to 5% minor constituents (as allowed by

various standards).

Manufacturing and Raw material for OPC;

The raw material used in manufacturing of ordinary Portland cement is given

o Lime or calcium oxide, CaO: from limestone, chalk, shells, shale or calcareous

rock

o Silica, SiO2: from sand, old bottles, clay or argillaceous rock

o Alumina, Al2O3: from bauxite, recycled aluminum, clay

o Iron, Fe2O3: from clay, iron ore, scrap iron and fly ash

o Gypsum, CaSO4.2H20: found together with limestone

The materials, without the gypsum, are proportioned to produce a mixture with the desired

chemical composition and then ground and blended by one of two processes - dry process or wet

process. The materials are then fed through a kiln at 1450°C to produce grayish-black pellets

known as clinker. The alumina and iron act as fluxing agents which lower the melting point of

silica from 1670 to 1405°C. After this stage, the clinker is cooled, pulverized and gypsum added

to regulate setting time. It is then ground extremely fine to produce cement.

Chemical shorthand(4)

Because of the complex chemical nature of cement, a shorthand form is used to denote the

chemical compounds.

The shorthand for the basic compounds is:

Compound Formula Shorthand form

Calcium oxide (lime) Ca0 C

Silicon dioxide (silica) SiO2 S

Aluminum oxide

(alumina)

Al2O3 A

Iron oxide Fe2O3 F

Water H2O H

Sulfate SO3 S

© Ahmed Al Malik, Lab Engineer, UOG Page 7

Properties of cement compounds(4)

These compounds contribute to the properties of cement in different ways

Tricalciumaluminate, C3A:-

It liberates a lot of heat during the early stages of hydration, but has little strength

contribution. Gypsum slows down the hydration rate of C3A. Cement low in C3A is

sulfate resistant.

Tricalcium silicate, C3S:-

This compound hydrates and hardens rapidly. It is largely responsible for Portland

cement’s initial set and early strength gain.

Dicalcium silicate, C2S:

C2S hydrates and hardens slowly. It is largely responsible for strength gain after one

week.

Tetra calcium AluminoFerrite, C4AF: This is a fluxing agent which reduces the melting temperature of the raw materials in the

kiln (from 3,000o F to 2,600

o F). It hydrates rapidly, but does not contribute much to

strength of the cement paste.

By mixing these compounds appropriately, manufacturers can produce different types of cement

to suit several construction environments.

Ingredients of cement

Clinker

Gypsum

© Ahmed Al Malik, Lab Engineer, UOG Page 8

Chemical composition of clinker The cement clinker formed has the following typical composition

Approximate composition of Portland cement (ASTM type’s I–V) (5)

ASTM type

and name Composition (%)* characteristics applications

C3S C2S C3A C4AF

I (Ordinary) 42–65 10–30 0–17 6–18 no special

requirements

general construction (e.g.,

sidewalks)

II (Modified) 35–60 15–35 0–8 6–18 moderate sulfate

resistance,

moderate heat of

hydration

drainage systems, sea

walls, floor slabs,

foundations

III (High-

early-strength)

45–70 10–30 0–15 6–18 higher strength

soon after

pouring

cold-weather construction

IV (Low-

heat)

20–30 50–55 3–6 8–15 low heat of

hydration

massive structures (e.g.,

dams)

V (Sulfate-

resistant)

40–60 15–40 0–5 10–18 high sulfate

resistance

foundations in high-

sulfate soils

*Source: American Concrete Institute, Guide to the Selection and Use of Hydraulic Cements

(1985).

Types of processes(6)

Wet process

Dry process

Wet process

The original rotary cement kilns were called 'wet process' kilns. In their basic form they were

relatively simple compared with modern developments. The raw meal was supplied at ambient

temperature in the form of slurry.

A wet process kiln may be up to 200m long and 6m in diameter. It has to be long because a lot of

water has to be evaporated and the process of heat transfer is not very efficient.

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The slurry may contain about 40% water. This takes a lot of energy to evaporate and various

developments of the wet process were aimed at reducing the water content of the raw meal. An

example of this is the 'filter press' (imagine a musical accordion 10-20 meters long and several

meters across) - such adaption were described as 'semi-wet' processes.

The wet process has survived for over a century because many raw materials are suited to

blending as slurry. Also, for many years, it was technically difficult to get dry powders to blend

adequately.

Quite a few wet process kilns are still in operation, usually now with higher-tech bits bolted on.

However, new cement kilns are of the 'dry process' type.

Dry process

In a modern works, the blended raw material enters the kiln via the pre-heater tower. Here, hot

gases from the kiln, and probably the cooled clinker at the far end of the kiln, are used to heat the

raw meal. As a result, the raw meal is already hot before it enters the kiln. The dry process is

much more thermally efficient than the wet process.

Firstly, and most obviously, this is because the meal is a dry powder and there is little or no

water that has to be evaporated.

Secondly, and less obviously, the process of transferring heat is much more efficient in a dry

process kiln.

An integral part of the process is a heat exchanger called a 'suspension preheaters'. This is a

tower with a series of cyclones in which fast-moving hot gases keep the meal powder suspended

in air. All the time, the meal gets hotter and the gas gets cooler until the meal is at almost the

same temperature as the gas.

The basic dry process system consists of the kiln and suspension preheaters. The raw materials,

limestone and shale for example, are ground finely in ball or roller mills and blended in silos to

produce the raw meal. The raw meal is fed in at the top of the preheaters’ tower and passes

through the series of cyclones in the tower. Hot gas from the kiln and, often, hot air from the

clinker cooler are blown through the cyclones. Heat is transferred efficiently from the hot gases

to the raw meal.

The heating process is efficient because the meal particles have a very high surface area in

relation to their size and because of the large difference in temperature between the hot gas and

the cooler meal. Typically, 30%-40% of the meal is decarbonated before entering the kiln. A

development of this process is the 'precalciner' kiln. Most new cement plant is of this type. The

principle is similar to that of the dry process preheaters system but with the major addition of

another burner, or precalciner. With the additional heat, about 85%-95% of the meal is

decarbonated before it enters the kiln.

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Process Flow Diagram (5)

Process Description

Cement is manufactured by number of stepsfirst step among them is raw material

acquisition.There are normally four type of raw material used in manufacturing of ordinary

Portland cement other than gypsum which is used with clinker to produce finished product.

Limestone

© Ahmed Al Malik, Lab Engineer, UOG Page 11

Calcium, the element of highest concentration in Portland cement, is obtained from a variety of

Calcareous raw materials, including limestone, chalk, marl, sea shells, aragonite, and an impure

Limestone known as "natural cement rock". These raw materials are obtained from open-face

quarries. Raw materials vary from facility to facility. Some quarries produce relatively pure

limestone. In other quarries, limestone is being mixed with clay.

Clay

Other element included in the raw mix is silicon (SiO2).it is also extracted from quarries with

limestone.

Laterite

This is an Iron ore. Its chemical composition is Fe2O3. It is also obtained in rock form.

Bauxite

This is an Aluminum ore. Its chemical composition is Al2O3

Gypsum

Gypsum a form of calcium sulfate (CaSO4) is introduced to the process during the finish

grinding operations. The raw material is obtained from quarries by blasting due which bigger

rocks are broken down in the form of lumps and then transported to the crusher areas by road

running machinery (loaders, dumpers)

Figure 1 Dumper (8)

Figure 2 Loader(7)

In pioneer cement two separated lines are used for cement manufacturing Line1 is old

technology unit having planetary cooler tubes for clinker cooling while line 2 is of modern

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technology having Grate cooler for clinker cooling and also have vertical roller mills for raw

material fine grinding.

Crushing of Raw Material

Through road running machinery raw material is transported to crusher area.Two separated

crushers are used for line 1 and 2. For line 1 limestone crusher is used having capacity of

600tons/hr which has product size of 25mm while for line 2 raw mix crusher is used having

capacity of 750tons/hr and product size of 75mm. Both crushers are hammer crushers after

crushing material transported to pile storage area through series of conveyor belts.

During crushing huge amount of dust is produced which is collected by bag filters and again

mixed with material transporting to pile storage area by belt conveyors

Typical hammer crusher hammers

Figure 3 Hammer Crusher (9)

Figure 4 typical crusher’s hammers (10)

Storage & Pre-homogenization of raw materials

Now after crushing material is stored in form of pile this is called pre homogenization step and

piles are made with the help of stackers

Line 1

For line 1 three piles are made for limestone of 3000 tons capacity, two for clay of 1500 tons and

one for bauxite and laterite respectively of 1500 tons.

Line 2

For line 2 two piles are made of raw mix material having capacity of 13000tonsrax mix include

(limestone, clay and bauxite). While one pile is made for laterite of 1500tons and one for pure

high grate lime of capacity 1000 tons

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Figure 5 Pioneer cement pile storage areas (11)

Stacking methods

Longitudinal stores: The most commonly used stacking methods are Chevron, Windrow and

Cone Shell.

Basically these methods consist of stacking a large number of layers on top of each other in the

longitudinal direction of the pile.

According to the Chevron method material is deposited by the stacker moving to and fro over

the center line of the pile. The Chevron stacking method causes segregation of the material with

fine particles in the central part of the pile and coarse particles on the surface and at the bottom

of the pile. To ensure proper blending a Chevron pile must therefore be reclaimed from the face

of the pile, working across the entire cross section.

According to the Windrow method material is deposited from a number of positions across the

full width of the pile. The Windrow method prevents segregation and ensures more even

distribution of fine and coarse particles across the pile.

The Windrow method is preferred in cases where the reclaimer is only operating in one part of

the pile cross section at a time or in cases where segregation would make an open pile base

unacceptable – typically in coal stores.

The Cone Shell method is often used in cases where homogenization is not necessary. The pile

is formed by depositing material in a single cone from a fixed position. When this conical pile is

full, the depositing of material moves to a new position and a new cone is formed against the

shell of the first one. This process continues in the longitudinal direction of the store until the

stockpile is complete.

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Figure6 Different types of piles (12)

Circular stores: Continuous Chevron stacking is the most commonly used method. The circular store has a round

base with a ring-shaped pile being continuously stacked at one end and reclaimed at the other.

Stacking takes place in a fan shaped arc – typically120°. With each sweeping movement,

corresponding to two layers of material, the whole sector advances approximately 1/2° ahead.

Figure7 Circular storage pile (12)

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Material Reclaiming portion

Reclaiming methods

On/Off mode:

The reclaimer is usually equipped with constant speed motors. The reclaimed material is carried

by belt conveyors driven by constant speed motors and discharged into a feed bin of a relatively

large volume. Reclaiming capacity is higher than the mill requirement and the reclaimer

therefore operates in an On/Off mode controlled by maximum/minimum level indicators in the

feed bin. On leaving the bin, the material is proportioned and fed to the mill by weigh feeders.

Direct mode:

If the materials are difficult to handle, it may be an advantage to avoid the intermediate bin

between the reclaimer and the mill. This is possible in cases where material from one (or more)

store(s) is to be fed to a single mill. In principle, the reclaimer must be equipped with speed

regulated motor sand an integrated belt scale. The transport and subsequent proportioning of the

reclaimed material and additional raw material is affected by speed regulated conveyors

.Reclaiming capacity will always match the mill requirement and the reclaimer will operate

continuously. The reclaimer in combination with the transporting belt conveyors acts as a weigh

feeder for the reclaimed material.

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Figure8 Material reclaiming method

(12)

In next step material is reclaimed and transported in first step is material is reclaimed by different

methods for line 1 and 2

Line 1

For line1 two reclaimers are used for material reclaiming one from lime stone and one for clay

laterite and bauxite.

Line 2

For line 2 raw mix material is reclaimed by bridge reclaimer and side scraper used for laterite

and high lime reclaiming. After reclaiming material is transported through belt conveyors to raw

material storage hoppers where afterward it is transported to mill areas for fine grinding.

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Figure9 Bridge Reclaimer (13)

Raw Mills Sections

Line 1

Now from storage bins material is transported to mill by passing through weigh feeder for

proportioning. The size of material should be greater than 20mmØ.while finish product size is

less than 90µm. In line 1 ball mill of capacity 240tons/hr is used for material fine grinding. In

ball mill material grinding is take place by impact of rolling and tumbling of media metallic balls

of different sizes through mill fine grinded material is transported in form of dust, made of hot

gases from kiln, with the help of induced draught created by system fan. After passing through

separator where coarse and fine particle are separated coarse return back to mill and fine are

transferred to gas cleaning cyclones by induced draught. Where gas is cleaned out from dust and

dust is collected at the bottom of cyclones and further transported to C.F.Silo by series of air

slides and air lift. Afterward gas is passed through electrostatic precipitator for further cleaning

and after cleaning exhausted by stack chimney by E.P fan.

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Lime Stone

HopperLaterite

Hopper

Bauxite

Hopper

Clay

Hopper

Ball Mill

Separator

Cyclone

Screw

ConveyorBelt conveyor

Hot Gases from Kiln

Bucket

Elevator

System Fan

Storage Silo

Raw Feed Grinding Process flow Diagram

Hot gas

out to

Stack

Coarse Particles

return

Mix Feed

Belt conveyor

Belt

Conveyor

Line 2

For line 2 two vertical roller mills R2 and R3 of capacities 120 and 165 tons/hr respectively are

used. Material from hoppers is fed to mills by passing through weigh feeder with the help of

conveyor belts where it is grinded to ultra-fine size less than 90µm. The Raw material fed to

mills should be of size range between 75-90mmØ. In vertical roller mills materials is grinded

with impact of rollers and moveable horizontal table and hot gases from kiln lift up the material,

after passing through separator (where coarse and fine particle are separated) coarse return back

to mill and fine are transported to cyclones for gas cleaning and further transported to C.F.Silo

for material homogenization. In mill inlet feed is controlled by hydraulic driven valves.

Vertical roller mill(14)

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Pure Lime

Stone

Hopper

Laterite

Hopper

Belt conveyor

Hot Gases from Kiln

Storage Silo

Raw Feed Grinding Process flow Diagram

by using vertical roller mill

Hot Gases and

material dustCyclone

Separator

System Fan

Screw Conveyor

Bucket

Elevator

Belt Conveyor

Hot Gas Exhaust

Raw Mix

Hopper

Raw Meal and C.F.Silo section

The finish product from raw mills are called Raw meal and transported to C.F.Silo with the help

of air slides and bucket elevators. Where it is stored and homogenize by continuous aeration,

with the help of series of air slides

Control Flow Silo(15)

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Coal Grinding Section

In this section large lump of coal is fed to vertical roller mill like raw mill of capacity 50 tons/hr

for fine grinding. Material is transported to mill from open yard with the help of belt conveyors.

After grinding fine coal is transport to storage bin with the help of pneumatic conveying system.

The size of fine grinded coal should be less than 90µm.

Coal Conveyor Belt (16)

Precalcing and Kiln section

Now this is main section in cement manufacturing process. Here clinkerization process takes

place. In first step raw meal from C.F.Silo is fed from top of preheaters and hot gases from kiln

move upward in preheater. Material move downward due to gravity while hot gases move

upward in countercurrent way in this way moisture removing, calcining and other reactions

starts. When temperature reached at 850°Cor above calcining take place the reaction is given as

CaCO3 → CaO + CO2 (g)

In pioneer cement line 1 has four stages single string (Inline Calciner) preheaters while line 2 has

five stages double strings (Off line Calciner) preheaters.

Precalciner

When material is reached in the precalciner here material is heated up to 900°C temperature and

95% calcinations take place in line 2 preheaters. While in line 1 unit preheaters 65% calcinations

takes place.

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In PC, avoid clinker formation because of temperature sudden increase up to 1200°C or above

and it cause the chocking of lowest cyclone feed pipe therefore the temperature should maintain

in between the 850 to 9000C.After the precalciner material is fed to the kiln for further reaction.

Kiln Process overview

(17)

Kiln Line 1kiln is of capacity 150 tons/hr. while line 2 kiln capacity is 250 tons /hr. The rotary kiln

consists of a tube made from steel plate, approximately diameter range from 4.5~6.0 meters and

lined with refractory to prevent the shell from high temperature effect. The kiln slopes slightly

(1–4°) and slowly rotates on its axis between30 to250 revolutions per hour. Material from

precalciner is arrived in calcining zone of kiln

When temperature is reached to 1000°C then calcining is completed. Now material moved to

transition zone where fluxes Al2O3 and Fe2O3 are melt down to form liquid phase and

temperature approx. reached to 1250°C.

After transition zone material enters into burning zone which is high temperature zone and

temperature inside this zone is approx. 1450°C here Alite formation take place and clinkerization

process almost completed. After burning zone material enter into cooling zone where material is

cooled down .Inside kiln heating is produced by burning coal with help of burner. While air is

supplied by fan

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Kiln burner (18)

Reaction detail with temperature

70 to 110 °C - Free water is evaporated.

400 to 600 °C - clay-like minerals are decomposed into their constituent oxides;

principally SiO2 and Al2O3. Dolomite (Ca Mg (CO3)2) decomposes to calcium carbonate,

MgO and CO2.

650 to 900 °C - calcium carbonate reacts with SiO2 to form Belite (Ca2SiO4).

900 to 1050 °C - the remaining calcium carbonate decomposes to calcium oxide and CO2.

1300 to 1450 °C - partial (20–30%) melting takes place, and Belite reacts with calcium

oxide to form Alite (Ca3O·SiO4).Typical clinker nodules(01)

Alite is the characteristic constituent of Portland cement. Typically, a peak temperature of 1400–

1450°C is required to complete the reaction

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Clinker Cooler

Rapid cooling require for clinker produced in kiln as Alite formation is a reversible reaction and

if it is not quickly cooled down then it reverse back to form Belite lowering the quality of

clinker.

C3S (Alite) 1250-1450°C

C2S (Belite)

For line 1 planetary tubes cooler and for line 2 grate cooler is used for clinker cooling. After the

kiln clinker produced is transported to cooler. Presently mostly industries used cooler with

perforated plates for cooling rather than planter cooler tubes because cooling efficiency and heat

recapturing of cooler is better than tubes. Now in grate cooler cool air is delivered from fans

under the cooler plates and clinker is moved forward with the help of motor driven plates in to

and fro motion. In this way clinker is cooled down with the help of air up to approximately 100-

150°C after cooler large clinker particle or lumps are moved forward to clinker crusher mainly

made up of hammers, where it is crushed down to approximately 25mmØ size. Now cooled

clinker is transported to clinker silo with the help of bucket conveyor where it is stored.

Clinker Cooler (19)

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Clinker grinding unit

Clinker from storage silo is transported to cement mill hoppers with the help of conveyor belts

also crushed gypsum from crusher stored in separate hopper. Normally ball mills are used for

clinker grinding. Ball mills are divided into two portion or chamber. Chamber 1 is crushing

chamber in which normally ball sizes range from 50-90mmØ. Both chambers are separated by

diaphragm, fine material pass on to next chamber, with the help of induced draught produced by

fan. In next chamber fine grinding of material take place. In this chamber grinding ball sizes

range from 10-25mmØ. After this material is lifted up with the help of induced draught and

move to bag filters for cleaning of air in which material sticks to the bags and cleaned air is

passed on. Materials attached to the bags are thrown down by purging of compressed air inside

bag and material is further transported to cement silos for storage, with the help of air slide and

bucket elevator.

(Typical Ball mill)(20)

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(Ball Mill central Diaphragm) (21)

Cement silos

In pioneer cement limited there are three silos for storage of cement each of capacity 6500 tons.

From where material is transported to packing unit for bagging or bulk loading

Cement storage silo (22)

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Packing Unit

Material through air slide is transported from cement silo to packing plant. Packing plant consist

of 4 packers each having capacity of 125 tons/hr. packing. Each packer has 6 nozzles and

centrally mounted small storage bin. Workers manually attached bags with the nozzle and by air

pressure material from bin forces to fill in the bag. As soon as bag attain the desired weight of

approx. 50 kgs it drop on the conveyor belt where it is transported to loading vehicle for dispatch

Packing Machine (23)

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Statement of Installed Production Capacity of Cement Plant In Pakistan(24)

As on April 2014

Sr. No. Name Of Unit Operational Capacity

Clinker Cement

1 Askari Cement Limited - Wah 1,050,000 1,102,500

2 Al-Abbas Cement Limited - Nooriabad, Dadu 900,000 945,000

3 Askari Cement - Nizampur 1,500,000 1,575,000

4 Attock Cement Pakistan - Hub Chowki, Lasbela 1,710,000 1,795,500

5 Bestway Cement Limited - Hattar 1,170,000 1,228,500

6 Bestway Cement Limited - Chakwal 3,428,571 3,600,000

7 Bestway - Mustehkum Cement Limited - Hattar 1,035,000 1,086,750

8 Cherat Cement Company Limited-Nowshera 1,050,000 1,102,500

9 Dandot Cement Limited - Jehlum 480,000 504,000

10 DewanHattar Cement Limited - Hattar 1,080,000 1,134,000

11 DewanHattar Cement Limited - Dhabeji 750,000 787,500

12 D.G.Khan Cement Limited - D.G.Khan 2,010,000 2,110,500

13 D.G.Khan Cement Limited - Chakwal 2,010,000 2,110,500

14 Fauji Cement Company Limited - Fateh Jang 3,270,000 3,433,500

15 Fecto Cement Limited - Sangjani 780,000 819,000

16 Flying Cement Limited - Lilla 1,140,000 1,197,000

17 GharibWal Cement Limited - Jehlum 2,010,000 2,110,500

18 Kohat Cement Company Limited - Kohat 2,550,000 2,677,500

19 Lafarge Pakistan Cement Company Limited - Chakwal 1,950,000 2,047,500

20 Lucky Cement Limited - Pezu 3,605,714 3,786,000

21 Lucky Cement Limited - Indus Highway, Karachi 3,428,571 3,600,000

22 Maple Leaf Cement Factory Limited - Daudkhel 3,210,000 3,370,500

23 Pioneer Cement Limited - Khushab 1,933,571 2,030,250

24 Thatta Cement Limited - Thatta 465,000 488,250

Total 42,516,428 44,642,250

© Ahmed Al Malik, Lab Engineer, UOG Page 28

References

1. http://Wikipedia.org

2. www.window.state.tx.us

3. http://cescientist.com

4. www.engr.psu.edu

5. http://www.britannica.com

6. http://www.understanding-cement.com

7. www.transdiesel.com 8. www.nityanand.com

9. www.stonecrushingplants.net

10. http://crusher-spare-parts.com

11. www.pioneercement.com

12. http://conveyorbelt.en.alibaba.com

13. Stacker and reclaimer systems for cement plants by FL smith

14. http://www.askaricement.com.pk 15. www.cemnet.com 16. www.tradeindia.com 17. spanish.alibaba.com

18. www.intechopen.com 19. www.flsmidth.com 20. Cement Kilns: Grate Coolerswww.cementkilns.co.uk

21. Ball Millswww.mine-engineer.com

22. CementClinkerGrindingwww.pwiuae.com

23. Cement Silos 3D Model www.cgtrader.com

24. Cement Equipment Manufacturers, Grinding Millwww.cnbestmill.com

25. All Pakistan cement manufactures associationhttp://www.apcma.com