The Manufacturing Process of Portland Cement G4
Transcript of The Manufacturing Process of Portland Cement G4
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The Manufacturing Process of
Portland Cement
Group members: No. Matriks
1. TAN PEI YING A133043
2. CHUA BOON YEN A133611
3. YEU WEE CHEK A133533
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1.
RAWMATERIALS
ACQUISITION
2.
RAWMATERIAL /KILN FEED
PREPARATION
3.PYROPROCESSI
NG
4.CEMENT
GRINDING
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Step 1: Raw Material Acquisition
Highest concentration in portland cement
Obtained from a variety of calcareous raw materialsCalcium
Can significantly increase emissions of sulfur dioxide
Found in deposits of limestone, clays, and shalesPockets of pyrite
Forms of Calcium Sulfate
Excavated from quarries or mines
Gypsum/ NaturalAnhydrite
Obtained from ores and minerals such as sand,shale, clay and iron ore
Silicon,aluminium, iron
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(left) obtain calcium from
limestone (calcium
carbonate)
(right) pyrite, usually
found in deposits oflimestone, clays and
shales.
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-Gypsum (or natural anhydrite) excavated
from quarries or mines.
-It will be added together with clinker inside grinding
mill ( function to prevent flash setting of concrete)
h l d
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Step 2: The Raw Mix or Kiln Feed
Preparation
For Pyroprocess operation Variety of blending and sizing operations
Wet and Dry process
Raw materials are received
with an initial moisturecontent varying from 1 tomore than 50 percent
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Step 2: (I) Dry Process
Moisture is reduced less than 1% before grinding
Impact dryers, drum dryers, paddle-equipped rapid dryers, air
separator, or autogenous mills
During grinding in ball-and-tube mills or roller mills
Thermal Energy for drying which is supplied by exhaust gassesfrom separate,direct fired coal, oil / gas burners
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Material
transportassociated withdry raw milling
system
Accomplished by a
variety mechanismexp : screwconveyors, beltconveyors and drag
conveyors
Dry raw mix
Pneumatically
blended Stored in specially
constructed silos
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Wet Process
Water is added to the rawmill, producing a pumpable
slurry
The slurry is agitated,blended
Stored in various kinds andsizes of cylinder tanks or
slurry basins
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Step 3 : Pyroprocessing System
Transforms the raw mix into clinkers
The Chemical reations and physical processesthat constitute the transformation are quitecomplex
Heart of manufacturing of cement
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Chemical & Physical Processes
Evaporation of water
Evolution of combinedwater in the argillaceous
components
Calcination of thecalcium carbonate to
calcium oxide
Reaction of CaO withsilica to form dicalcium
silicate
Reaction of CaO withthe aluminium and iron-bearing constituents toform the liquid phase
Formation of the clinkernodules
Evaporation of volatileconstituents
Reaction of Excess CaOwith dicalcium silicate toform tricalcium silicate
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4 Stages
Materials temperatures increased to 100C
Evaporation of uncombined water from raw
materials
Materials temperature increases from 100C 430C to formoxides of silica, aluminium and iron
Dehydration
Carbon dioxide is evolved in the temperature of 900C to formCarbon Oxide in the temperature of 982C
Calcination
Occur in the burning zone of the rotary kiln
Reaction of oxides ---T1510----> cement clinker
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Rotary Kilns
long cylinder rotating about its axis once
every minute or two. The axis is inclined at aslight angle, the end with the burner beinglower.
Mostcommonly
used kiln fuels Coal, natural gas, and oil
Used ofsupplementary
fuels
Waste solvents, scrap rubber, and petroleumcoke
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Left: Cement Kiln That We Can
Usually See Inside Laboratory.
Right: High Efficiency
Cement Kiln System InsideFactory. (where
pyroprocessing can take
place)
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Five different
processes toaccomplish thepyroprocessing
step
Wet process
Long Dry process
Semidry process Dry process with a
preheater
Dry Process with aprecalciner
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Wet Process and Long Dry Process
Occurs inrotary kiln
rotary kiln are simple & shorter
System ofChain
Provided at the feed end of the kiln
in the drying or preheat zones toimprove heat transfer from the hotgases to the solid materials
KilnRotation
Causes the hot chains to fall intothe cooler materials at the bottomof the kiln, then transfer the heatto the load
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Dry Process Pyroprocessing System
Preheater process
Additional of one ormore cyclone-typepreheater vessels inthe gas streamexiting the rotary kiln
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Hot exhaust gases from the rotary kiln pass countercurrently through the downward-moving raw materials in
the preheater vessels.
The hot gases are used as a source of heat for drying raw
materials in the raw mill
It is a production mechanics and pollution controldevices because the catch from the mechanicalcollectors, fabric filters, and electrostatic precipitators(ESP) will follow the raw mill returned to the process
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Dry Process Pyroprocessing System
Preheater / pre-cailciner process
Additional thermal efficiency
& productive gain is achievedby diverting some fuel to acailciner vessel at the base ofthe preheater tower
Determined by the availability and source ofthe oxygen for combustion in the calciner
Amountof the fuel
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Preheater and Precalciner Kiln System
Have analkali
bypasssystem
To remove the undesirablevolatile constituents(recirculate to the kiln)
It can restrict process and gasflow
The alkalicontent
is limited
Can cause deleteriousreactions in concrete
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Semidry Process
The water is added to the dry raw mix in apelletizer
To form moist nodules or pellets
Conveyed on a moving grate preheaterbefore being fed to the rotary kiln
The pellets are dried and partially calcinedby hot kiln exhaust gases passing throughthe moving gate
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Clinker Cooler
Last component of the pyroprocessing system
Recoups up to 30 percent of the heat input to the kiln system
Locks in desirable product qualities by freezing mineralogy
Makes it possible to handle the cooled clinker with conventionalconveying equipment
It is cooled from about1100C to 93C (2000F to 200F) by ambient air
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Commontypes
Reciprocating grate
Planetary Rotary
Reciprocating
grate cooler
Lower clinker discharge temperature areachieved by passing an additional
quantity of air through the clinker
Additional air
Cannot be utilized in the kiln for efficientcombustion
Vented to the atmosphere Used for drying coal or raw materials or as
combustion air source for precalciner
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Clinker Storage
Normally store 5-25% of its annual clinker productioncapacity
Equipment used to transfer the clinker from coolers tostorage areas and to the finish mill are conveyors andbucket elevators
Gravity drops and transfer points typically are vented todust collectors
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Final Step: Finish Grinding Mill
blending andgrinding
operationsthat
transformclinker tofinishedportlandcement
Up to 5 percentgypsum ornaturalanhydrite isadded to theclinker during
grinding To control the
cementsetting time
Other specialty
chemicals areadded asneeded
To impartspecificproductproperties
Finish milling isaccomplished
almostexclusively inball or tube
mills.Typically,
finishing isconducted in aclosed circuitsystem, with
product sizingby air
separation
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`Grinding Mill
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Packing and Loading
Finished product is transferred usingbucket elevators and conveyors to large,
storage silos on the shipping department
The portland cement is transported in
bulk by railway, truck, or barge, or in 43kg(94 pound) multiwalled paper bags
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Packing & Despatch
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Environmental Issues
Air pollutants
The combustion of fuel in rotary cementkilns generates nitrogen oxides from thenitrogen in the fuel or incomingcombustion air
Sulfur dioxide is generated from thesulfur compounds in the ores
Liquid andSolid wastes
Overflow from slurry equipment
Stripped overburden
The combustion processes of cementkilns and rotary kilns have been used todispose of hazardous waste material
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CONCLUSION:
The manufacturing of Portland cementrequired a sequence of process.
Roughly, we can convenient the process into 4
main steps : raw material acquisition, rawmix/clink feed preparation, pyroprocessing, andgrinding mill.
Comparing the wet process and dry process,dry process is more thermally efficient andsave cost.
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THE END
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