Training material cement process (NXPowerLite)

ISO Team Training
04-Sept-2007
CEMENT PROCESS


CONTENT
1. Hon Chong flow chart
2. Raw material preparation
3. Raw meal preparation
4. Clinker producing
5. Cement grinding
6. Co-processing


Hon Chong Flow chart

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ISO Team Training - Manufacturing

Cement Process ppt


Cement Production Diagram
Production of Cement by the Dry Process
Feed Bins
Sampling Station

Quarry

Raw Materials Storage

Crushing Plant (s)

Corrective Materials

and Preblending

Electrostatic
Precipitator

Homogenizing and
Storage Silo

Cooler Dedusting

Coal
Raw Meal

W ater

Air-to-Air
Cooler

Coal
Mill

Cyclone
Preheater

Rotary Kiln

Clinker Cooler

Conditioning
Tower

Raw Mill

Filter

Mineral
Gypsum Components

Bulk Dispatch

Cement
Silo

Clinker
Storage

Packing Machine

Bag Palletisation

Cement
Silo

Cement Mill

Zement-trocken-englisch.dsf

Kma 27.4.98

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Cement Process ppt


Cement Production Process _ Steps
 Mining of limestone

drilling or blasting
 crushing of limestone


 pre homogenization
 grinding of raw material
 homogenization of raw meal
 pyroprocessing

coal grinding, co-processing
 cement grinding


Raw material extraction
Raw material preparation
Raw meal preparation
Clinker production

 cement storage, packing, and dispatching
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Cement Process ppt


Raw Material Preparation-Crusher
CRUSHER
Type: Impact crusher
Size reduction: 1.2 m to 0.1/ 0.05m
Using impact forces do the size reduction
of raw materials from the quarry.
It is easier to transport smaller material,
and spread it along the pre-blending
stockpile.

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Cement Process ppt


Raw Material Preparation-General
Reduction ratios:
3:1 to 7:1 by compression
To 50:1 by impact and
combination of 2-3 stages

The type of crushers depends on:
The work index of the material
Abrasiveness
Stickiness
Throughput, tons per hour etc.
Size of feed
Power consumption
Reduction Ratios needed
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Cement Process ppt


RMP_ Crusher type application

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Cement Process ppt


RMP_ Pre-blending
CHEVRON METHOD
 ‘To and fro’ stacker movement over the

ridge of the pile.
Chemical uniform in full length due to

fast stacker movement.
Particle and composition segregation in

the area of the end-cones
The pre-blending efficiency is a function

of the number of layers: the higher the
number of layers the better the preblending effect.
Pre-blending will be sufficient with

material reclaim in thin slices from the
front
Pre-blending will be insufficient when

material is reclaimed in lateral slices
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RMP_ Pre-blending
 Mixing LS and Clay/sand for reducing impact

of sticky clay
Sand is silica corrective material
Mixing process controlled by PGNAA, and

weighing system of sand, clay, and limestone
Process control parameters are ratio of clay to

limestone, percentage of sand, stockpile volume
Quality control parameters: LSF and SR of

stockpiles
Other quality factors for controlling: MgO,

P205, SO3
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Cement Process ppt


RMP_ key concerns
 Wet and sticky materials in raining season
 PGNAA operation and maintenance
 Quarry master and mixing muck-piles at quarry
 Accuracy of weigh feeders
 Limestone size control for OPC LS mixing in cement
 Cement quality impact of MgO, P205
 Kiln process impact of SO3

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Cement Process ppt


Raw Meal Preparation- Function

Purposes of raw grinding systems


Producing a raw meal fineness (particle size and distribution) adequate for

the production of the required clinker quality



Provide the proper proportioning of the components in the correct ratios



Mixing the components



Drying of the raw material to enable transport of the raw meal
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Raw Meal Preparation- Fineness
R90

R200

Fineness targets:
R90: 10-15%
R200<1.5%

Factors affect fineness


Feed material grindability



Grinding pressure



Grinding tools (roller tyres, grinding table)



Separator effectiveness
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Raw Meal Preparation- VRM and grinding process
95oC

90oC

Separator
Separator guide vanes
Gridcone
Roller

Grinding table
250oC
hot gas

25oC
material

Gearbox
Motor
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Cement Process ppt


Raw Meal Preparation- VRM and grinding process
Drying


Drying heat source: the hot gas from the kiln or hot gas generator



Fine material is lifted up, exposed to and flash-dried by the hot gas
stream



The drying process occurs mainly in a short distance from the
nozzle ring area to raw mill outlet

Drying is necessary to guarantee proper:


Material handling
Too wet material => build up, transport and maintenance problems.



Grinding
Too high moisture contents strongly reduce mill capacity.



Product quality
Excessive moisture in the cement leads to undesirable cement
hydration.

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Cement Process ppt


Raw Meal Preparation- VRM and grinding process

Grinding


Feed material consisting of fresh feed plus return from
separator is fed onto the center of the grinding table



There it is centrifuged and ground by compression of rollers
when passing below the rollers.



Optimal and effective grinding can only be achieved when the
material bed is stable and has the proper thickness

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Cement Process ppt

Raw Meal Preparation- VRM and grinding process
Separation
Two separations occur inside the mill:
1.Coarse separation
The armored ring orients the gas/air
flow so that the coarse particles that
cannot be lifted up to the separator by
the gas/air fall back to the grinding
table.
2.Fine separation

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

The rest of the material arrives to the to
the rotor cage separator where fine
separation takes place.



The coarse material is returned to the
grinding table through the separator
grits cone.



The fine product with the gas/air
stream leave the mill

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Cement Process ppt


Raw Meal Preparation- Quality aspects
Feed material components:
1.

LS/Clay provides majority of CaO, SiO2 affect LSF, SR

2.

Laterite provides majority of Fe2O3, Al2O3 affect AR

3.

High grade limestone provides majority of CaO affect LSF

Quality control factors:
LSF: 99-100, SR: 2.4-2.5, AR: 1.4-1.5
Process control:
% weigh feeder, separator speed, mill outlet temperature

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Cement Process ppt


Raw Meal Preparation- Blending Silo
It is the last step in the line of the raw mix preparation processes
with the aim to reduce the residual variations in composition.
The inverted cone (central cone) features:


Equipped with a large inverted cone covering most of the center of the
bottom area



The remaining annulus is divided into sectors that are covered by open air
slides. Each sector is equipped with its own outlet.



Raw meal is aerated by air supply to the individual sectors at a low rate
and a low pressure. This air leaves the silo together with the activated raw
meal.



Aeration is switched systematically by means of solenoid valves sector by

sector.



Height / diameter ratio: up to 2.5:1



Spec. power cons. system: 0.1-0.2 kWh/t
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Cement Process ppt


Clinker Manufacturing- Basis reaction sequence

Raw mixture
(20°C)

reactants + products
+
intermediate products
(450 - 1300°C)

alite + belite
+

melt (1450°C)

cooled
clinker

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Cement Process ppt


Sequence of Reactions Occurring in a Rotary Kiln
Heating (°C)
20 - 100

Evaporation of H2O

100 - 300 Loss of physically adsorbed water
400 - 900 Removal of structural H2O (H2O and OH groups)
from clay minerals
>500 Structural changes in silicate minerals
600 - 900 Dissociation of carbonates
>800 Formation of belite, intermediate products, aluminate
and ferrite
>1250
Formation of liquid phase (aluminate and ferrite
melt)

~1450

Completion of reaction and growth of alite
and belite

Cooling (°C)
1300 - 1240 Crystallization of liquid phase into mainly aluminate
and ferrite
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Cement Process ppt


Basis Reactions-Calcination
At ≈ 800 °C Limestone
decomposes into free lime
and carbon dioxide.
CaCO3 → CaO + CO2

As long as this dissociation
process is underway,
the hot meal temperatures
will remain in the
750 ~ 900+ºC range.

CALCINING

Calcination will continue until all
the calcium carbonate is
converted to lime and carbon
dioxide.

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Argillaceous Components

While calcination is taking place, the
argillaceous components are
breaking down, making Al2O3, Fe2O3
and SiO2 available.

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Cement Process ppt

Lime & Silica Reaction

At elevated
temperatures of the
process, lime will
react readily with
silica to form C2S
belite

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Cement Process ppt


Lime, Aluminum & Iron

C3A

At elevated temperatures of
the process lime will also
react readily with aluminum
and Iron to form a number of
intermediate products. The
resulting synthetic minerals
C3A and C4AF
are key components not only

in cement but as precursors to
the liquid phase of the
sintering process

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Cement Process ppt