This document discusses fly ash management from thermal power plants. It begins with an abstract that outlines how fly ash is a major byproduct of coal-based power generation in India that can pollute the environment if not properly utilized or disposed of. The document then covers the production process of fly ash, its properties, types of ash generated, methods of disposal, and various beneficial uses like manufacturing bricks and cement. It also discusses environmental impacts and the need for proper fly ash management.

1. 1
A Seminar Report On
FLY ASH MANAGEMENT
Submitted in partial fulfillment of requirement for the award of degree of
Bachelor of Technology
In
Civil Engineering
By
RAMAKANTA PANDA
REGD NO.1421110008
GOVERNMENT COLLEGE OF ENGINEERING KALAHANDI
BHAWANIPATNA-766002

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CONTENTS
Page No.
ABSTRACT ……………………………………………… 3
1. INTRODUCTION ……………………………………………... 4
2. PRODUCTION PROCESS …………………………………….. 6
3. PROPERTIES OF FLY ASH …………………………………….. 7
4. DISPOSAL OF FLY ASH …………………………………….. 8
5. VARIOUS USES OF FLY ASH …..…………………………….. 9
6. CASE STUDY …………………………………………………… 10
7. ENVIRONMENTAL IMPACTS ……………………………….. 13
8. MINIMIZATION OF ASH CONTENT OF COAL …………… 17
9. FUTURE SCOPE ………………………………………………. 17
10. REFERENCES ……………………………………………….. 18

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ABSTRACT
Power Industry has been, and continues to be, a key factor in the economic growth of most of
the developed and developing countries. In general, the power sector represents the industries
with highest environmental impact and has constantly been subject of increasing pressure from
new economic, energy saving and environmental issues. Coal based Power Generation has been
the backbone of the any developing country. Indian coal is of low grade, having ash content as
high as 45% in comparison to imported coals which have low ash content of the order of 10-
15%.
Fly ash is a major byproduct of Thermal power plant, which makes a lot of pollution to the
environment due to its fineness. As a large amount of fly ash is dumped in the nearby places of
power plants it mixes in all segment of environment like water, air as well as soil. Though it
can be utilized for different useful purposes due to lake of technical knowhow and proper
motivation no progress has been made in its utilization. It has been observed that the fly ash can
be used for making a varieties of building materials by using simple low cost or high investment
processes. The strength of the bricks increases with increasing time. Moreover it can be used in
its optimal quantity for better production of crops like rice, wheat etc.
Key Words: - Fly ash, Thermal Power Plant, clay bricks, Segment of environment, Building
materials.

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1. INTRODUCTION
Fly ash is a major by product of thermal power plant. It is a very fine material about 60-70% of
which has a size below 0.076 mm. as it is formed by the burning of pulverized coal. The disposal
of such fly ash is creating a serious problem as per its storage space and cost involved in its
storage. At the same time there is a lot of pollution of the environment due to the fineness of
the fly ash. The effects for its utilization for many gainful purposes have been made since late
sixties of this century by various research institutions and public enterprises, but nothing
spectacular has really been seen yet in commercial utilities. The present utilization of the fly
ash is about 2% of the total generation. For the present development scenario of India, one of
the thrust area is infrastructure where generation of power holds major share. It is estimated that
at present about 125 million tonnes of fly ash is generated every year from 82 thermal power
plants. This amount will reach 200 million tonnes very soon. The fly ash disposal is going to be
a major problem in near future.
Coal based thermal power plants, contributing to the 61.5 percent of total installed power
capacity, are the major source of electricity generation in India (CEA, 2015). Most of industries
are using pulverized coal as the fuel, producing enormous quantities of coal fly ash every year.
India has 211 billion tonnes of coal reserves. Indian coal used in thermal power plants is of low
grade quality and has an ash content of 40 to 50% .The power generation in India was about
200,000 MW in 2012 and it is expected to increase up to 300,000 MW by 2017. The present fly
ash generation rate is about 131.09 million tonnes per year and the utilization rate of coal is
73.13 million tonnes per year. The coal reserve of India is about 200 billion tones (bt) and its
annual production reaches 250 million tonnes (MT) approximately. About 70% of this is used
in the power sector. In India, unlike in most of the developed countries, ash content in the coal
used for power generation is 30–40%. High ash coal means more wear and tear of the plant and
machinery, low thermal efficiency of the boiler, slogging, choking and scaling of the furnace
and most serious of them all, generation of a large amount of fly ash. India ranks fourth in the
world in the production of coal ash as by-product waste after USSR, USA and China, in that
order. Fly ash is defined in Cement and Concrete Terminology (ACI Committee 116) as the
‘finely divided residue resulting from the combustion of ground or powdered coal, which is
transported from the fire-box through the boiler by flue gases’. Fly ash is fine glass powder, the
particles of which are generally spherical in shape and range in size from 0.5 to 100 μm. Fly ash
is classified into two types according to the type of coal used. Anthracite and bituminous coal
produces fly ash classified as class F. Class C fly ash is produced by burning lignite or sub-
bituminous coal. Class C fly ash has self-cementing properties. Fly ash generation & utilization
data for the Years 2011-12 and 2012-13 has been received from 124 (One hundred twenty four)
and 138 (One hundred thirty eight) coal/lignite based thermal power stations of various power
utilities in the country. statistics received has been analyzed to derive conclusions on present
status of fly ash generation and its utilization in the country as a whole.

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TABLE-I
SUMMARY OF FLY ASH GENERATION AND UTILIZATION DURING THE YEAR 2011-
12 AND 2012-13
Description 2011- 12 2012-13 2013-14 2014-15
Nos. of Thermal
Power Stations
from which data
was received
124 138 143 145
Installed capacity
(MW)
1,05,925.3 1,20312.30 1,33,381.30 1,38,915.80
Coal consumed
(Million tons)
437.41 482.97 523.52 549.72
Average Ash
Content (%)
33.24 33.87 172.87 184.14
Fly Ash
Generation(Million
tons)
145.42 163.56 99.62 102.54
Fly Ash Utilization
(Million tons)
85.05 163.56 57.63 55.69
Percentage
Utilization
58.48 61.37 33.02 33.50
The pie diagram showing the modes of utilization of fly ash during the Year 2014-15

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2. PRODUCTION PROCESS
Fly ash material solidifies while suspended in the exhaust gases and is collected by electrostatic
precipitators or filter bags. Since the particles solidify rapidly while suspended in the exhaust
gases, fly ash particles are generally spherical in shape and range in size from 0.5 µm to 300 µm.
The major consequence of the rapid cooling is that few minerals have time to crystallize, and
that mainly amorphous, quenched glass remains. Nevertheless, some refractory phases in the
pulverized coal do not melt (entirely), and remain crystalline. In consequence, fly ash is a
heterogeneous material. SiO2, Al2O3, Fe2O3 and occasionally CaO are the main chemical
components present in fly ashes. The mineralogy of fly ashes is very diverse. The main phases
encountered are a glass phase, together with quartz, mullite and the iron oxides hematite,
magnetite and/or maghemite. Other phases often identified are cristobalite, anhydrite, free lime,
periclase, calcite, sylvite, halite, portlandite, rutile and anatase.
Two classes of fly ash are defined by ASTM C618: Class F fly ash and Class C fly ash. The
chief difference between these classes is the amount of calcium, silica, alumina, and iron content
in the ash. The chemical properties of the fly ash are largely influenced by the chemical content
of the coal burned (i.e., anthracite, bituminous, and lignite).

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3. PROPERTIES OF FLY ASH
The fly ash or pulverised fuel ash is formed as a result of burning pulverised coal. The principal
contents of fly ash are normally silica (30-60%), alumina (15-30%), iron oxide and carbon in
the form of unburnt fuel up to 20%, lime 7% and small quantities of magnesium oxide and
sulphate. Indian coals normally contain 25 to 40% ash. The main problem of utilization of fly
ash comes from the unburnt carbon as it has no binding force or any other properties which can
be utilize other than the fuel. The fly ash samples are collected from Nandira seam (Talcher),
Bharatpur seam (NALCO) and power plant (Rourkela Steel Plant). The fly ash are analysed by
standard methods and the data are summerised in the Table
Compounds
Nandira seam,
Talcher
Bharatpur seam,
NALCO
Power plant,
RSP
SiO2 53.6 55.7 59.2
Al2O3 18.3 18.2 17.9
Fe2O3 12.7 11.2 9.5
CaO 3.8 2.5 3.2
MgO 1.2 1.9 1.3
Sulphate 1.3 0.9 1.2
Unburnt
carbon
7.2 7.5 7.0
Other oxides 1.9 2.1 0.7
PHYSICAL PROPERTIES :
1) The fly ash particles are generally glassy, solid or hollow and spherical in shape. The
hollow spherical particles are called as cenospheres.
2) The fineness of individual fly ash particle rage from 1 micron to 1 mm size. The fineness
of fly ash particles has a significant influence on its performance in cement concrete.
3) The specific gravity of fly ash varies over a wide range of 1.9 to 2.55.

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4. TYPES OF ASH
Any coal based thermal power station may have the following four kinds of ash:
Fly Ash : This kind of ash is extracted from flue gases through Electrostatic Precipitator in dry
form. This ash is fine material & possesses good pozzolanic property. Fly ash is a by-product
of pulverized coal combustion in thermal power plants. Fly ash particles are light and have the
potential to get airborne and pollute the atmosphere, Fly ash, also known as "pulverised fuel
ash" in the United Kingdom, is a coal combustion product composed of fine particles that are
driven out of the boiler with the flue gases.
Bottom Ash : This kind of ash is collected in the bottom of boiler furnace. It is comparatively
coarse material and contains higher unburnt carbon. It possesses zero or little pozzolanic
properties. It is a part of the non-combustible residue of combustion in a furnace or incinerator.
In an industrial context, it usually refers to coal combustion and comprises traces of
combustibles embedded in forming clinkers and sticking to hot side walls of a coal-burning
furnace during its operation. The portion of the ash that escapes up the chimney or stack is,
however, referred to as fly ash. The clinkers fall by themselves into the bottom hopper of a coal-
burning furnace and are cooled. The above portion of the ash is referred to as bottom ash too.
Pond Ash : When fly ash and bottom ash or both mixed together in any proportion with the
large quantity of water to make it in slurry form and deposited in ponds wherein water gets
drained away. The deposited ash is called as pond ash. An pond ash is an engineered structure
for the disposal of bottom ash and fly ash. The wet disposal of ash into ash ponds is the most
common ash disposal method, but other methods include dry disposal in landfills. Dry-handled
ash is often recycled into useful building materials. Wet disposal has been preferred due to
economic reasons, but increasing environmental concerns regarding leachate from ponds has
decreased the popularity of wet disposal.The wet method consists of constructing a large "pond"
and filling it with fly ash slurry, allowing the water to drain and evaporate from the fly ash over
time.Ash ponds are generally formed using a ring embankment to enclose the disposal site. The
embankments are designed using similar design parameters as embankment dams, including
zoned construction with clay cores. The design process is primarily focused on handling seepage
and ensuring slope stability.
Mound Ash : Fly ash and bottom ash or both mixed in any proportion and deposited in dry
form in the shape of a mound is termed as mound ash. Neolithic ash mounds (sometimes termed
as cinder mounds) are man-made landscape features found in some parts of southern India
(chiefly around Bellary) that have been dated to the Neolithic period (3000 to 1200 BC). They
have been a puzzle for long and have been the subject of many conjectures and scientific studies.
They are believed to be of ritual significance and produced by early pastoral and agricultural
communities by the burning of dung and animal.

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5. DISPOSAL OF FLY ASH
Scientific disposal and management of fly ash is still a most important problem by coal
based thermal power plants. Fly ash emissions from a variety of coal combustion in thermal
power generation units prove a broad range of composition. All elements below atomic
number 92 are present in coal ash. The fine particles of fly ash reach the pulmonary region
of the lungs and remain there for long periods of time; they behave like cumulative poisons.
The residual particles being silica (40–73%) cause silicosis. All the heavy metals (Ni, Cd,
Sb, As, Cr, Pb, etc.) generally found in fly ash are toxic in nature. Fly ash can be disposed-
off in a dry or wet state. Studies show that wet disposal of this waste does not protect the
environment from migration of metal into the soil. Heavy metals cannot be degraded
biologically into harmless like other organic waste. Studies also show that coal ash satisfies
the criteria for landfill disposal, according to the Environmental Agency of Japan (JEAN,
1973). According the hazardous waste management and handling rule of 1989, fly ash is
considered as non-hazardous. With the present practice of fly-ash disposal in ash ponds
(generally in the form of slurry), the total land required for ash disposal would be about
82,200 ha by the year 2020 at an estimated 0.6 ha per MW. Fly ash can be treated as a by-
product rather than waste.
In the past fly ash produced from coal power plants was simply entrained in flue gasses and
released into the environment.
Now in the U.S., EPA regulations requires greater than 99% of total fly ash produced in a
plant to be captured and either stored, recycled, or disposed.
Worldwide, more than 65% of fly ash produced in the world is disposed of in landfills or
ash ponds.
In India alone fly ash landfills comprise 40,000 acres of land.
Disposal of fly ash

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6. VARIOUS USES OF FLY ASH
The fly ash can be used for making a verity of building materials, some using simple low cost
processes and others high investment processes producing high quality products. They can also
be used as fertilizer. The fly ash is processed to increase the surface area by grinding and to
remove and reduce the unburnt carbon. This fly ash so produced is activated fly ash and gives
superior engineering properties like higher crushing strength and are more reactive with lime or
cement. It can be blended uniformly to give portlant pozzolana cement. It can be mixed directly
with lime to give desired properties of mortar or concrete, as required. Fly ash can be mixed in
varied proportions with lime or portland cement to give blends for better engineering properties.
FLY ASH BRICKS:
Fly ash is being used in manufacturing of fly ash based building products like bricks, blocks, tiles
etc which results in saving of fertile top soil. Fly ash based bricks/blocks/tiles are as good as clay
based conventional building products. It has substantial potential of fly ash utilization especially for
thermal power stations located near load centers Manufacturing process of clay fly ash bricks by
manual or extrusion process involves mixing of fly ash(60%) with clay of moderate plasticity.The
green bricks are dried under ambient atmospheric condition or in shed to equilibrium moisture level
of below 3%.The dried bricks are fired in traditional bricks kilns at 1000°C ± 30°C with a soaking
period of 5-7 hours.
Fly Ash Bricks / Blocks

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CEMENT CONCRETE:
Fly ash could be an expensive replacement for Portland cement in concrete and using it,
improves strength, segregation and ease of pumping concrete. The rate of substitution
typically specified is a minimum of 1 to 1 ½ pounds of fly ash to 1 pound of cement. Fly
Ash particles provide a greater workability of the powder portion of the concrete mixture
which results in greater workability of the concrete and a lowering of water requirement for
the same concrete consistency.Fly ash having both pozzolanic and hydraulic property and
is consequently serves as a suitable raw material. Cement containing fly ash typically show
a lower early strength compared to OPC at similar fineness. They also exhibit a lower water
demand, and improved workability, a higher long term strength. According to European
standard (en 197-1) various cement types containing siliceous and calcareous, fly ash from
6%-55% by mass are possible. For every ton of clinker substituted, energy need for clinker
production can be saved 3.58 GJ/T –clinker . For every ton of clinker substituted, CO2
emission associated with its production can be avoided(855Kg/t-clinker) .
View of tunnel of Delhi Metro Rail Corporation where fly ash has been used
FLY ASH IN ROAD CONSTRUCTION :
There are many techniques available which utilize fly ash in road construction. These can
be used as granular sub material and as soil stabilizer. It can also be utilized in semi-rigid
and rigid pavement as lean cement fly ash concrete, lime fly ash concrete, fly ash in rigid
pavement construction, fly ash as filler in bituminous/asphalt concrete and roller compacted
concrete.

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Fly ash concrete rigid pavement
SOIL STABILIZATION:
Soil stabilization is the permanent physical and chemical alteration of soils to enhance their
properties. Using Fly ash a soil stabilization can increase shear strength, control the shrink-swell
properties of the soil and improves the load bearing capacity. Benefits include higher resistance
values, reduction in plasticity, lower permeability and elimination of excavation.
Soil stabilisation using fly ash

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EMBANKMENT AND BACK FILL:
Fly ash is relatively lighter than Earth. Well compacted fly ash Exhibits good shear strength
comparable to soils normally used in Earth fill operations. It is easier to compact coal ash as
compared to Earth..
About 1.5 lac tonnes of pond ash has been utilized in this bridge
MINE FILLING:
• At Talcher-Thermal, ash is
being filled in South Balanda
Mine,
utilizing about 10 lakhs cum
ash /
annum (100%)
• Efforts are on to take up Random
filling of ash along with over
burden of an operating mine as a
pilot study.

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7. CASE STUDY
Utilization of fly ash in NTPC (Talcher, Odisha) during the year 2014-15 as per the
Annual report of CEA.
Description Quantity
Coal consumed (million ton) 17.634
Ash content of coal (million ton) 36.974
Fly ash generation (million ton) 6.520
Fly Ash used in making
Bricks/Blocks/Tiles (million ton)
0.092
Manufacturing of Portland Pozzolana
cement (million ton)
0.034
In ash Dyke rising (million ton) 2.478
Others (million ton) 0.153
Total Utilization (million ton) 2.757
Percent Utilization of Fly ash (% age) 42.285

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Fly ash utilization in India as per MoEF&CC
SL.NO YEAR GENERATION
(Million Ton)
UTILISATION
(Million Ton)
PERCENTAGE
UTILISATION
1 1998-1999 78.98 9.60 12.16
2 1999-2000 74.03 10.88 13.51
3 2000-2001 86.29 13.51 15.61
4 2001-2002 82.81 15.61 18.85
5 2002-2003 91.65 20.79 22.68
6 2003-2004 96.28 28.17 29.26
7 2004-2005 98.57 37.51 38.06
8 2005-2006 98.97 45.32 45.79
9 2006-2007 108.15 55.07 50.92
10 2007-2008 116.94 61.98 53.00
11 2008-2009 116.69 66.64 57.11
12 2009-2010 123.54 77.34 62.66
13 2010-2011 130.77 72.87 55.73
14 2011-2012 145.42 85.05 58.48
15 2012-2013 163.53 100.37 61.37
16 2013-2014 172.87 99.62 57.63

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8. ENVIRONMENTAL IMPACTS
Environmental pollution by the coal based thermal power plants all over the world is cited
to be one of the major sources of pollution affecting the general aesthetics of environment
in terms of land use, health hazards and air, soil and water in particular and thus leads to
environmental dangers. The greatest part of the radioactivity in coal remains with the ash
but some of the fly ash from coal-fired power plants escapes into the atmosphere. Air
pollution in the vicinity of a coal fired thermal power station affects soil, water, vegetation,
the whole ecosystem and human health.
It reduces green house gas emission as a cement replacement material. For every one ton of
cement produced about 6.5 million BTUs of energy is consumed. Replacing that 1 ton of
cement with fly ash would save enough electricity to power the average American home for
almost a month. For every one ton of cement produced about one ton of carbon dioxide is
released which can be reduced by using fly ash. It reduces volume of landfill space used for
disposal of fly ash. There is possibility of leaching toxic substances into soil, water,
atmosphere.EPA has proven that heavy metals have been leached from fly ash into ground
water and underground aquifers in 39 locations in the U.S. The extent of leaching and
hazardousness to humans of fly ash leachate is still unclear but the EPA is investigating it
currently.Large ruptures of fly ash ponds, dams, or retention walls can cause catastrophic
environmental damage to ecosystems and contaminate large areas with toxic substances.
9. FUTURE SCOPE
Exploration on the possibilities of manufacturing geo-polymer concrete in India with Indian
fly ash, study on the flexural behaviour of reinforced fly ash based geo-polymer concrete
beams and their durability characteristics when exposed to harsh environment can be
investigated. The Indian fly ash contains some quantity of calcium and iron, and hence
durability study on reinforced geo polymer concretes is necessitated for their structural
applications which led to the investigation on flexural behaviour of reinforced geo-polymer
concrete beams exposed and unexposed to aggressive solutions. There is a lot of scope in
managing the use of fly ash. Researches can also be done to use fly ash in geo-polymers. As
it is a very stable material so its use as geo-polymer can be very much helpful. It can also
be as a catalyst in various chemical reaction because of its inertness. Fly ash can also be
used as a wood substitute material.

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10.REFERENCES
1. Haque , Emamul M., “Indian coal: production and ways to increase coal supplies” ,
International journal of scientific and research publication (IJSRP) volume 3 , issue 2 ,
February 2013.
2. Rao, B.K and Kumar Vimal, 1996, “Fly ash in high strength concrete” , Recent
advances in Civil Engineering , Nation seminar Sept. 28, pp. 115-12
3. Bhattacharjee U, Kandpal T C, “Potential of fly ash utilization in India, Energy” 2002,
27: 151-66.
4. Annual Report on fly Ash utilization, Central Electricity Authority India 2015.
5. Bijen, J. (2005) Other uses of fly ash. In K. I.Wesche, & K. Wesche (Ed.),Fly ash in
concrete (pp. 173-179). London, UK: Chapman & Hall.