ctep - unit - ii - cement production

CEMENT CEMENT PRODUCTIONPRODUCTION

BY K.R.SHANKAR M.E.,

ASSISTANT PROFESSOR DEPARTMENT OF CIVIL ENGINEERING

EBET GROUP OF INSTITUTIONS TRIPPUR DISTRICT

TAMUL NADU, INDIA – 638108 Email ID – [email protected]

Raw Materials Necessary for Raw Materials Necessary for Portland Cement Manufacture Portland Cement Manufacture

Must Provide the FollowingMust Provide the FollowingCalciumCalciumSilicaSilicaAluminaAluminaIronIron

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Calcium Calcium IronIron Silica Silica AluminaAlumina SulfatSulfatee

Alkali wasteAlkali wasteAragoniteAragoniteCalciteCalciteCement-kiln Cement-kiln dustdust

Cement rockCement rockChalkChalkClayClayFuller’s earthFuller’s earthLimestoneLimestoneMarbleMarbleMarlMarlSeashellsSeashellsShaleShaleSlagSlag

Blast-furnace Blast-furnace flue dustflue dust

ClayClayIron oreIron oreMill scaleMill scaleOre washingsOre washingsPyrite cindersPyrite cindersShaleShale

Calcium silicateCalcium silicateCement rockCement rockClayClayFly ashFly ashFuller’s earthFuller’s earthLimestoneLimestoneLoessLoessMarlMarlOre washingsOre washingsQuartziteQuartziteRice-hull ashRice-hull ashSandSandSandstoneSandstoneShaleShaleSlagSlagTraprockTraprock

Aluminum-ore Aluminum-ore refuserefuse

BauxiteBauxiteCement rockCement rockClayClayCopper slagCopper slagFlyFly ashashFuller’s earthFuller’s earthGranodioriteGranodioriteLimestoneLimestoneLoessLoessOre washingsOre washingsShaleShaleSlagSlagStauroliteStaurolite

AnhydriteAnhydriteCalcium Calcium sulfatesulfate

GypsumGypsum

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Traditional Manufacture of Portland Traditional Manufacture of Portland CementCement

1. Stone is first reduced to 125 mm (5 in.) size, then to 20 mm (3/4 in.), and stored. 55

2. Raw materials are ground to powder and blended.

or2. Raw materials are ground, mixed with water to

form slurry, and blended.

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3. Burning changes raw mix chemically into cement clinker.

Source: PCA, 200388

4. Clinker is ground with gypsum into portland cement and shipped.

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ClinkerClinker Gypsum

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CEMENT SILO

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DRY PROCESSDRY PROCESS

Water added – 30 – 50%Water added – 30 – 50%Rotary kilnRotary kiln

Length - 30-200 mLength - 30-200 m Dia. – 3-8 mDia. – 3-8 m Gypsum – 3-5 %Gypsum – 3-5 % Coal used- 350 kg / tonCoal used- 350 kg / ton

Water added – 12 – 14%Water added – 12 – 14%Rotary kilnRotary kiln

Length - 10-20 mLength - 10-20 m Gypsum – 2-3 %Gypsum – 2-3 % Coal used- 100 kg / tonCoal used- 100 kg / ton

WET PROCESSWET PROCESS

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a) Tricalcium Silicate (50%)a) Tricalcium Silicate (50%)

b) Dicalcium Silicate (25%)b) Dicalcium Silicate (25%)

c) Tricalcium Aluminate (10%)c) Tricalcium Aluminate (10%)

d) Tetracalcium Aluminoferrite (10%)d) Tetracalcium Aluminoferrite (10%)

e) Gypsum (5%)e) Gypsum (5%)

CHEMICAL COMPOSITION OF PORTLAND CEMENT

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FUNCTION :TRICALCIUM SILICATE (CFUNCTION :TRICALCIUM SILICATE (C33S)S)

Hardens rapidly Hardens rapidly and largely responsible for and largely responsible for initial set initial set

& early strength& early strength

The increase in percentage of this compound will The increase in percentage of this compound will

cause the cause the early strengthearly strength of Portland Cement to be of Portland Cement to be

higherhigher

A bigger percentage of this compound will produces A bigger percentage of this compound will produces

higher heat of hydration higher heat of hydration and accounts for and accounts for faster gain faster gain

in strengthin strength1616

FUNCTION :DICALCIUM SILICATE (CFUNCTION :DICALCIUM SILICATE (C22S)S)

Hardens slowlyHardens slowly

It effects on It effects on strength increases strength increases occurs at occurs at

ages beyond ages beyond one week one week

Responsible for Responsible for long term strengthlong term strength

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FUNCTION :TRICALCIUM ALUMINATE (CFUNCTION :TRICALCIUM ALUMINATE (C33A)A)

Contributes to Contributes to strength developmentstrength development in the in the first first

few daysfew days because it is the first compound to because it is the first compound to

hydrate hydrate

It turns out It turns out higher heat of hydration higher heat of hydration and and

contributes to contributes to faster gain in strengthfaster gain in strength

But it results in But it results in poor sulfate resistance poor sulfate resistance and and

increases the increases the volumetric shrinkage upon dryingvolumetric shrinkage upon drying1818

Cements with Cements with low Tricalcium Aluminate low Tricalcium Aluminate

contents usually generate contents usually generate less heatless heat, develop , develop

higher strengths higher strengths and and show greater resistanceshow greater resistance to to

sulfate attackssulfate attacks

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FUNCTION : TETRACALCIUM FUNCTION : TETRACALCIUM ALUMINOFERRITE (CALUMINOFERRITE (C44AF)AF)

Assist in the manufacture of Portland Cement by Assist in the manufacture of Portland Cement by

allowing allowing lower clinkering temperaturelower clinkering temperature

Also act as a Also act as a fillerfiller

Contributes Contributes very little strength very little strength of concrete even of concrete even

though it though it hydrates very rapidlyhydrates very rapidly

Also responsible for Also responsible for grey colour grey colour of Ordinary Portland of Ordinary Portland

CementCement2020

ctep - unit - ii - cement production

Engineering