Flyash Utilization and Disposal

7/28/2019 Flyash Utilization and Disposal

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BY

S. DHANABALANChief Manager / Civil

NLC Ltd.

NEYVELI


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What is Flyash?

Why utilize Flyash?

When to utilize Flyash?

How to manage Flyash?


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FLYASH What is F.A

Floating ACRONYM

Light Weight

YtterbiumAbrasive

SiliceousHazardous


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FLYASH

It is mineral residue got from the

combustion of Bituminous/Sub

Bituminous Coal


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Flyash Production

NLC 12 Lakh Tonnes

All India 180 million Tonnes


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Flyash Management

Effective Utilization

Safe Disposal


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Utilization Best Option

Cause pollution Air, Water and Land

Require Water

Occupies Land

Contains Heavy Metals

High Disposal Cost


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Historical Background

Use of ash dates back to 3000 BC.

Romans used volcano ash with horse

hair.


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s za onClassification Scientific

Way

Low value

Medium value High value


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Schematic Representation


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Characteristics of Flyash

CONTENTS LIGNITE FLYASH(%) COAL FLYASH (%)

L.O.I 1.0 TO 2.0 3-15

Sio2 45-59 40-64

Al2O3 23-33 15-29

Fe2O3 0.6-4.0 2-11

CaO 5.0-16.0 0.1-1.0

MgO 1.5-5.0 0.2-4.0

SO3 0-5.0 0.1-1.7


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Flyash as Pozzalone (PPC)

What is Pozzalone?

Pozzalone by itself is an inert material

But in the presence of water readily

reacts with lime to form hydrates.


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Mineral Composition Of

CementMINERALS COMPOSITION (%)

C3S 45-80

C2S 0-32

C3A 7-15

C3AF 4-14


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Reaction Of Cement With

Water

2 C3S + 6H C3S.H + 3CH

2 C2S + 4H C3s .H + CH

C3A + CH +18 H C4AH

C4AF + 3CH + 22 H C4AH + 3CFH


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Pozzalonic Reactions

3S + 3CH C3S.H

AL + 4CH + 15H C4A.19H

F + 3CH + 3H C3F.6H


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Codal Provisions

IS has prescribed certain minimum

physical and chemical parameters for

flyash for use as pozzalone in IS 3812.

Now IS has permitted use of FA upto35% in manufacture of PPC


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Characteristic Requirements Method of Test

Ref to

Siliceous

Pulverized

Fuel Ash

Calcareous

Pulverized

Fuel Ash

Annex IS No

Si02 + Al2o3 + Fe2o3 70 50 - IS 1727

Sio2 35 25 - IS 1727

Reactive Silica 20 20 B -

Mgo 5.0 5.0 - IS 1727

Sio3 3.0 3.0 - IS 1727

MgO 1.5 1.5 - IS 4032

Total Chlorides 0.05 0.05 - IS 12423

Loss in Ignition 5.0 5.0 - IS 1727


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Characteristics Requirements

Fineness-specific surface inm2/kg by Blaines permeability

method, &fin

320

Particles retained on

45 micron IS sieve (wet

sieving) in percent, Max

34

Lime reactivityAverage

compressive strength in

Nlmm3, Min

4.5

Compressive strength at

28 days in N/mm*, Miss

Not less than 80 percent

of the strength ofcorresponding plain

cement mortar cubes

Soundness by autoclave test

Expansion G_ specimen in

percent,Max

0.8


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Fly ash Bricks

Bricks are indispensible in construction

Used in Walls, Arches , Domes and

Roofs

Demand Supply Gap

Fertile top soil is exploited


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Process of Manufacturing Fly

ash Bricks

SINTERING Process

AUTOCLAVING Process

COLD Process


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Type of Fly ash Bricks

Cement Fly ash Bricks

FALG Bricks

Fly ash Lime Bricks

Clay Fly ash Bricks


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Strength Attainment in

Bricks 3CH + 2S C3S.3H

4CH + A + 15H C4A.19H

3CH + F + 3CH C3F.6H


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FA Brick Mfg In NLC

NLC is pioneer in FA brick manufacturing.

Flyash Lime Bricks manufactured manually

during 70s.

Cement Flyash Bricks using a manualpress during 90s.

Semi Automatic process to Mfg Flyash

Lime Gypsum Bricks from 1997. Flyash bottam ash,Cement bricks are now

manufactured.


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Advantages of FA Bricks

Better Dimensional Stability

Uniform Strength

Reduce Cost of Disposal

Low Mortar Requirement

Economical

Reduce Pollution


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Conclusion

Flyash is no more a waste material

Gained Momentum

In NLC all the dry collected Flyash is

utilized

More than 50% of the ash production

could be utilized in FA bricks and PPC


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THANK YOU

Documents

Flyash Utilization and Disposal