The Manufacturing Process of Portland Cement G4

8/2/2019 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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Documents

The Manufacturing Process of Portland Cement G4