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    Seminar Presentation: Fly Ash: Utilization and Disposal

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    Civil 2
    Fly ash is a byproduct of coal combustion in power plants. It can be utilized in construction materials like concrete and bricks, as well as in applications like mine fills and soil stabilization. However, much of it is currently disposed of in landfills and ash ponds, which can pollute air, water, and soil if not properly managed. The document discusses the history, composition, types, production, uses, disposal methods, and environmental impacts of fly ash. Utilizing fly ash provides benefits like reduced waste and embodied energy compared to producing new materials, but also has disadvantages like potential groundwater contamination if not handled correctly.

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    Seminar Presentation: Fly Ash: Utilization and Disposal

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    Civil 2
    34 views29 pages
    Fly ash is a byproduct of coal combustion in power plants. It can be utilized in construction materials like concrete and bricks, as well as in applications like mine fills and soil stabilization. However, much of it is currently disposed of in landfills and ash ponds, which can pollute air, water, and soil if not properly managed. The document discusses the history, composition, types, production, uses, disposal methods, and environmental impacts of fly ash. Utilizing fly ash provides benefits like reduced waste and embodied energy compared to producing new materials, but also has disadvantages like potential groundwater contamination if not handled correctly.

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    Utilization of fly ash

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    flyashdisposalandutilization-161125151246

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    Fly ash is a byproduct of coal combustion in power plants. It can be utilized in construction materials like concrete and bricks, as well as in applications like mine fills and soil stabilization. However, much of it is currently disposed of in landfills and ash ponds, which can pollute air, water, and soil if not properly managed. The document discusses the history, composition, types, production, uses, disposal methods, and environmental impacts of fly ash. Utilizing fly ash provides benefits like reduced waste and embodied energy compared to producing new materials, but also has disadvantages like potential groundwater contamination if not handled correctly.

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    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    34 views29 pages

    Seminar Presentation: Fly Ash: Utilization and Disposal

    Uploaded by

    Civil 2
    Fly ash is a byproduct of coal combustion in power plants. It can be utilized in construction materials like concrete and bricks, as well as in applications like mine fills and soil stabilization. However, much of it is currently disposed of in landfills and ash ponds, which can pollute air, water, and soil if not properly managed. The document discusses the history, composition, types, production, uses, disposal methods, and environmental impacts of fly ash. Utilizing fly ash provides benefits like reduced waste and embodied energy compared to producing new materials, but also has disadvantages like potential groundwater contamination if not handled correctly.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
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    of 29

    SEMINAR PRESENTATION

    FLY ASH : UTILIZATION AND DISPOSAL

    Submitted by:
    Jyoti kumari
    Environmental Engineering
    National Institute of Technology
    Content:
     Introduction
     History
     Chemical composition
     Types of fly ash
     Ash generation and effects
     Production Process
     Utilisation
     Disposal
     Environmental consideration
     Advantages & disadvantages
     Conclusion
     References
    Introduction
     Fly ash is one of the residues created during the
    combustion of coal in coal-fired power plants.

     Fine particles rise with flue gasses and are collected


    with filter bags or electrostatic precipitators

     Fly ash is a waste by-product material that must be


    disposed of or recycled

     Fly Ash is considered as amorphous and mixture of


    Ferro- alluminosilicate minerals.
    History

    The Roman Colosseum Ghatghar Dam


    Chemical Composition
     Because fly ash is a by-product material chemical
    constituents can vary considerably but all fly includes:
     Silicon Dioxide (SiO2)
     Calcium Oxide (CaO) also known as Lime
     Iron (III) Oxide (Fe2O3)
     Aluminum Oxide (Al2O3)
     Depending on source coal may include one or more toxic
    chemicals in trace amounts:
     Arsenic, Beryllium, Boron, Cadmium, Chromium, Cobalt,
    Lead, Manganese, Mercury, Molybdenum, Selenium,
    Strontium, Thallium, and Vanadium
    Types of Fly ash
     ASTM C618 Defines two classes of fly ash:

     Class C

     Class F

     ASTM C618 requirements:

     Loss of Ignition (LOI) < 4%

     75% of ash must have fineness of 45 µm or less

     Primary difference between Class C and Class F fly ash is the


    amount of calcium, silica, alumina, and iron content in the ash
    Class F
     Produced from burning harder, older anthracite and
    bituminous coal.
     Contains less than 20% lime
     Requires cementing agent like PC, quick lime
    , hydrated lime
     Used in high sulfate exposure conditions
     Used for structural concretes, HP concretes,
    high sulfate exposure concretes
     Useful in high fly ash content concrete
    mixes
    Class C
     Produced from burning younger lignite and subbituminous
    coal
     Higher concentration of alkali and sulfate
     Contains more than 20% lime
     Self-cementing properties
     Does not require activator
     Not for use in high sulfate conditions
     Primarily residential construction
     Limited to low fly ash content concrete
    mixes
    Ash Generation and Effects
     Ash is an inherited impurity of coal that will not burn. Typical
    range is 5% to 40%
     Reduces handling and burning capacity.
     Increases handling costs.
     Affects combustion efficiency and boiler efficiency
     Causes clinkering and slagging.
     Ash is generated as the product of combustion of coal
     Comprises of 80% Fly Ash and 20% Bottom Ash

    Parameter Indian Coal Indonesian South African Coal


    Coal

    Ash content 38.63% 13.99% 17%


    (%)
    Scenario in India:
    Production / Segregation process
    Utilization
     In developed countries more than 80% Fly Ash is used for the
    manufacturing following:-

     In agriculture
     Building material
     Bricks construction
     Mine fills
     Metallurgy
     Use of new material
     Environmental control
     Embankment
    Details on Utilization
     Agriculture
     Indian Fly Ash is alkaline and as such improves soil quality. In a research
    conducted by MSEB, it was found that with dose of 10MT per hectare and just
    50% dose of chemical fertilizers there is increase of 20% yield in terms of grains
    and fodder

     Mine Fills
     Utilization of Fly Ash in Mine fills has potential to consume large quantity of Fly
    Ash. This single application of Fly Ash can utilise about 1/4th of total Fly Ash
    generation

    • Metallurgy
     The Fly Ash contains about 20%-25% alumina. CPRI Bengaluru has developed a
    process to extract alumina from Fly Ash.
     About 1 tonne of Fly Ash with 400 kg of other additives like lime and gypsum can
    produce 150 kg of alumina and 1250 kg of pozzolanic cement, which is a good raw
    material for quality bricks
     Precast Fly Ash concrete units

     It can be used in production of various types of precast building units such as


    solid and hollow core slabs, doors and window frames

     Clay Fly Ash Bricks

     About 0.25 – 0.80 times of calay can be replaced by fly ash.


     Further, the residual carbon content in Fly Ash brings about an economy in
    fuel consumption during firing of bricks.

     Cement

     Fly Ash being an artificial pozzolanic material can be used for manufacturing
    of Portland Pozzalona Cements (PPC), as partly replacement of cement in
    mortar and concrete
     Building material

     Fly Ash is a Pozzolanic material containing silica in good proportion. It


    has tremendous potential to be used as an alternative material for
    building construction
     Road construction material

     Utilization of Fly Ash in bulk quantities for road works depending on the
    intersection between Coal ash and sub-grade soil.

     Use of new material

     In order to maintain the present rate of technological development some


    alternative materials viz., fly ash, fibre glass, reinforced plastics and glass,
    reinforced gypsum are used as building materials.
     Embankment

     Lower unit weight reduces dead loads and induced settlement of sub-soil
     High shear strength compared with its low unit weight for good bearing
    support
     Ease of placement and compaction can reduce construction time and cost

     Soil Stabilization

     A sheep’s foot roller is commonly used to add the fly ash to the soil.Also
    specialized equipment can be utilized to pump fly ash or other stabilizers
    into the soil.Class C fly ash is used in soil stabilization

     Flowable Fill

     Fly ash generally supplements the Portland cement in greater volume The
    fine particulate of the fly ash acts as ball bearings allowing it to flow
    freely. Generally Class C fly ash is used for flowable fill.
    Fly ash use
    Let us see what fly ash achieves in totality: -
     It delays the heat of hydration and hence reduces the thermal
    cracks in concrete
     It improves the workability of concrete
     It makes the mix homogeneous and hence reduces segregation
    and bleeding
     The concrete finish is improved due to perfectly spherical fly ash
    particles
     The concrete permeability is substantially reduced which
    enhances the life of the structure
     Fly ash contributes to the long term strength in concrete
    Examples of fly ash utilization

    Reclamation of saline soils using fly First fly ash embankment in the
    ash (75% savings in Gypsum) country (Okhla fly over, New Delhi)
    Examples of fly ash utilization

    Upper dam of Ghatghar Pumped Use of Fly ash for Road Embankment
    Storage Scheme constructed with RCC
    ( 65% replacement of cement with fly
    ash)
    Disposal
     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 65,000 acres of
    land.
    Modes of disposal
     Dry Fly Ash Disposal

     Fly Ash once collected in Electrostatic Precipitator gets


    transported to Fly Ash Bunkers using pressurized air and then
    gets transported via truck or conveyers at the site and disposed
    by constructing a dry embankment.

     Wet Fly Ash Disposal

     Fly Ash once collected in ESP is mixed with water to form slurry
    and then this slurry is transported through pipe to the ash ponds
    or dumping areas near the plants.
    Environmental Consideration of Disposal
     The environmental aspect of Fly Ash disposal aims at minimizing
    air and water pollution.
     The Fly Ash produced by thermal power plants can cause all three
    environmental risks-
     Air : Air pollution is caused by direct emissions of toxic gases
    from the power plants as well as wind-blown ash dust from ash
    mound/pond.
     surface water: The wet system of disposal in most power plants
    causes discharge of particulate ash directly into the nearby
    surface water system
     ground water pollution. The long storage of ash in pond can
    cause leaching of toxic metals from ash and contaminate the
    underlying soil and ultimately the groundwater system
    Schematically pathways of pollutant
    movement around Fly Ash disposal.
    Advantages of fly ash utilization
     Saving of space for disposal
     Saving of scare of natural resources
     Energy saving, firstly because the material is
    automatically produced as a by-product and no
    energy is consumed for its generation and secondly
    because it can replace material which otherwise
    would need to be produced by consuming energy.
     Protection of environment, as in construction it can
    partly replace cement, production of which entails
    energy consumption and CO2 emissions.
    Disadvantages of fly ash utilization
     Groundwater contamination due to runoffs carrying ill-treated
    fly ash.

     Cannot be used for structures requiring shorter setting time, a


    demand which is expected by most of the engineers and
    builders.

     It is very difficult to use in winter season due to further increase


    in already longer setting time.

     Difficult to control colour of cement containing flyash. Hence,


    a bit problematic to use where cosmetic quality plays a
    significant role.
    Conclusion
     Flyash can be proclaimed as one of the most advantageous
    waste material.
     Using it as a construction material will not only help in its
    disposal but will also add strength and durablity of
    structures.
     Since, the current usage of flyash in India is still around
    25% and below 45% even in the developed countries like
    United States, there is a huge scope for flyash in upcoming
    years.
     So let us harness a billion dollar resource that has been
    wasted so far.
    References
     http://www.flyash.com
     1st International Conference on Fly Ash Utilization, NDCC
    Convention Centre, New Delhi held during November 24-25,
    2011.

     Use of Fly Ash in Mine Filling- cbri


    enviwww.cbrienvis.nic.in/mine_filling.htm

     Fly Ash Technologies- National Metallurgical Laboratory (A


    constituent establishment of (CSIR)

     2nd Annual International Summit on Fly Ash Utilization, NDCC


    Convention Centre, New Delhi held during January 17-18, 2013.

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