Geo Environmental Assessment on Abandoned Mine Filling with Coal Ash SOUMYAPRAKASH SAHOO

Geo Environmental Assessment on Abandoned Mine Filling with Coal Ash SOUMYAPRAKASH SAHOO
Geo Environmental Assessment on
Abandoned Mine Filling with Coal
Ash
A Thesis Submitted in Partial Fulfillment of the Requirements for the
Degree of
Master of Technology
In
Civil Engineering
SOUMYAPRAKASH SAHOO
DEPARTMENT OF CIVIL ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELA
2014
Geo Environmental Assessment on
Abandoned Mine Filling with Coal Ash
A Thesis Submitted in Partial Fulfillment of the Requirements for the
Degree of
Master of Technology
In
Civil Engineering
Under the guidance and supervision of
Prof C.R.Patra
Submitted By
Soumyaprakash Sahoo
(ROLL NO. 212CE1029)
DEPARTMENT OF CIVIL ENGINEERING
NATIONAL INSTITUTE OF TECHNOLOGY, ROURKELA
2014
1
Dedicated
To
Mr Pramod Kumar Sahoo
&
Mrs Sanjikta Sahoo
2
NATIONAL INSTITUTE OF TECHNOLOGY
ROURKELA
CERTIFICATE
This is to certify that the thesis entitled “Geo Environmental Assessment Of Abandoned
Mine Filling With Coal Ash” being submitted by Soumyaprakash Sahoo is partial fulfilment
of the requirements for the award of Master Of Technology in Civil Engineering with
specialization in GEOTECHNICAL ENGINEERING at National Institute Of Technology
Rourkela, is an authentic work carried out by his under my guidance and supervision.
To the best of my knowledge, the matter embodied in this report has not been
submitted to any other university/institute for the award of any degree or diploma.
Place: Rourkela
Dr. Chittaranjan Patra
Professor
Date:
Dept. of Civil Engineering
NIT, Rourkela
3
ACKNOWLEDGEMENTS
First of all, I would like to express my sincere gratitude to my supervisor Prof.
Chittaranjan Patra, for his guidance and constant encouragement and support during the
course of my work in the last one year. I truly appreciate and value of his esteemed guidance
and encouragement from the beginning to the end of thesis.
I would like to thank Prof. N Roy, Head of Civil Engineering, National Institute of
Technology, Rourkela, who has enlightened me during my project.
I am also thankful to Prof. S.K. Das, Prof. S.P. Singh, Prof. R.N. Behera and all
professors of Civil Engineering department. Also I thanks to Prof. D.N. Singh from IIT,
Bombay and Prof. S.B. Attarde of School of Environmental and Earth Science, North
Maharashtra University for their assistance during my research work.
A special words of thanks to Mr Sunil Khuntia, M.Tech research Scholar of civil
Engineering department, for his suggestion, comments entire support throughout the project
work. I am also thankful to staff member of Geotechnical Engineering laboratory especially
Mr. Harihar Garnayak, Mr Chamuru Suniani for their assistance & co-operation during
exhaustive experiments in the laboratory. I express to my special thanks to my dear friends
Rakesh, Barda, Subhrajit, Aparupa, Shakti, Ganesh, Partha, Aditya, Amit Bhai, Ellora,
Sovan, Zishan, Alam, Suchi, Raj, Dipti Bhai, Sumanta Bhai, Jagyan Bhai, for their
continuous support and suggestion and love.
Friendly environment and cooperative company I had from my classmates and
affection received from my seniors and juniors will always remind me of my days as a
student at NIT Rourkela. I wish thank all my friends and well-wisher who made my stay at
NIT Rourkela, memorable and pleasant.
Finally, I would like to thank my parents and family members for their unwavering
support and invariable source of motivation.
Soumyaprakash Sahoo
1
Table of Contents
Abstract ..................................................................................................................................... i
List of Figures ......................................................................................................................... iii
List of Tables .......................................................................................................................... iv
CHAPTER-1 .............................................................................................................................1
INTRODUCTION....................................................................................................................1
1.1 Origin of Project ........................................................................................................................... 2
1.2 Objective ....................................................................................................................................... 3
CHAPTER-2 .............................................................................................................................4
LITERATURE REVIEW .......................................................................................................4
2.1 Introduction ................................................................................................................................... 4
2.2 Review of Literature ..................................................................................................................... 5
CHAPTER-3 ...........................................................................................................................13
MATERIALS AND METHODOLOGY .............................................................................13
3.1 Introduction ................................................................................................................................. 13
3.2 Material used............................................................................................................................... 13
3.2.1 Coal ash................................................................................................................................ 13
3.2.2 Water sample ....................................................................................................................... 13
3.3 Experimental Procedure .............................................................................................................. 15
3.3.1 Specific Gravity Test (By Density Bottle Method) IS: 2720 (Part-III/SEC-I)..................... 15
3.3.2 Grain Size Analysis (By Sieve Analysis and Hydrometer Analysis) IS: 2720 (Part-IV) .... 15
3.3.3 Water holding capacity of coal ash ...................................................................................... 17
3.3.4 BET specific surface area test (IS 11578 – 1986) ................................................................ 18
3.3.5 X-Ray Diffraction of coal Ash ............................................................................................. 19
3.3.6 Scanning Electron Microscope (SEM) AND Energy Dispersive X-Ray Spectroscopy (EDS)
of coal ash ..................................................................................................................................... 19
3.3.7 Batch Leaching Test (ASTM- D 4793-09) .......................................................................... 20
3.3.8 Toxicity Characteristic Leaching Procedure (USEPA-TCLP Method 1311) ...................... 22
3.3.9 pH of coal ash (IS 2720 (Part 26)) ....................................................................................... 22
3.3.10 Coal ash slurry ................................................................................................................... 22
3.3.11 pH value (electrometric methods) (IS 3025 (Part-11)) ...................................................... 23
3.3.12 Measurement of Turbidity (IS 3025 (Part-10)) .................................................................. 24
2
3.3.13 Measurement of Total Suspended Solids (IS 3025 (Part-17)) ........................................... 25
3.3.14 Measurement of Total Hardness (EDTA method) (IS 3025 (Part-21)) ............................. 26
3.3.15 Methodology for measurement of Alkalinity (IS 3025 (Part-23)) ..................................... 27
3.3.16 Atomic Absorption Spectrometer test ................................................................................ 29
CHAPTER-4 ...........................................................................................................................30
RESULTS & DISCUSSION .................................................................................................30
4.1 Introduction ................................................................................................................................. 30
4.2 Specific Gravity of coal ash ........................................................................................................ 30
4.3 Particle size distribution of coal ash ........................................................................................... 30
4.4 Water Holding Capacity of Coal Ash ......................................................................................... 31
4.5 X-Ray diffraction of coal ash ...................................................................................................... 32
4.6 Morphology of coal ash .............................................................................................................. 34
4.7 Compositional analysis of coal ash ............................................................................................. 35
4.7.1 Chemical composition (wt. %) of fly ash............................................................................. 35
4.7.2 Chemical composition (Wt. %) of bottom ash ..................................................................... 35
4.7.3 Chemical composition (Wt. %) pond ash ............................................................................ 36
4.8 Specific Surface Area of Coal Ash ............................................................................................. 37
4.9 pH of Coal Ash ........................................................................................................................... 37
4.10 Leaching Analysis of Coal Ash ................................................................................................ 37
4.10.1 Batch Leaching Test of coal ash ........................................................................................ 37
4.10.2 Toxicity Characteristic Leaching Procedure (TCLP) method............................................ 44
4.11 Mine Water Assessment............................................................................................................ 45
4.12 Coal Ash Slurry and Mine Water Interaction ........................................................................... 46
4.12.1 Coal Ash Slurry.................................................................................................................. 46
4.12.2 Coal ash slurry- mine water interaction ............................................................................. 47
CHAPTER-5 ...........................................................................................................................48
CONCLUSION ......................................................................................................................48
REFERENCES .......................................................................................................................50
3
Abstract
In India, large quantity of fly ash is produced from coal based thermal power plants
because most of our energy demand is fulfilled through coal based resources. In our country
fly ash generation increased from 40 million tons to 135 million tons in between 1994 to
2012. As per Technology Information Forecasting and Assessment Council and Fly Ash
Utilization Programme, the generation of ash is expected in between 300-400 MT in 2017,
500MT in 2022 and 1000 MT/YR in 2032. In the future, production rate of fly ash is likely to
increase drastically to meet power demand for number of coal based power plants
contributing to total power production is around 80%. Indian coals are generally low in
sulphur content, due to which, huge amount of ash is generated during its burning. Also
disposal of these ashes in land without proper disposal facilities causes environmental
pollution. A number of researchers have discussed the utilization of coal ash in various
Geotechnical applications.
For minimizing surface subsidence, river sand is mostly used in abandoned coal
mines filling. Due to increase in the use of the river sand in the construction industries, the
mining industries are facing scarcity of river sand to fill abandoned mine. After extraction of
coal from mines, large number of coal mines leave without filling, which creates surface
subsidence. Therefore, the mining industry is searching for an alternate filling material which
is easily available in large quantity and in minimal cost. The present work aims to
characterize and utilize the largely available coal ashes in abandoned mine filling applications
and to study the various issues related to geo- environmental aspects of the same.
From the experimental results, it is concluded that coal ashes can replace the
conventional river sand normally used for mine filling applications and thereby cost of the
project as well as the environmental problems relating to coal ash can be reduced to a
significant extent. It was observed that the water holding capacity of bottom ash considerably
i
lower than pond and fly ashes. XRD results show that coal ash has more numbers of quartz,
mullite and iron oxide peaks. The coal ash used in this study is classified under Class „F‟
according to ASTM C618. However, in general Class „F‟ fly ash can provide a better filler
material than Class „C‟ fly ash, because the calcium content is low. Heavy metal
concentrations were leached more from fly ash as compared to bottom ash and pond ash.
Initially, when neutral coal ash is mixed with acidic water, the pH value increases and after
24 hours it gradually decreases and attains value confirming to drinking water standard.
ii
List of Figures
Figure 1.1 Fly ash generation and utilisation by NTPC power plants ....................................... 2
Figure 2.1 Schematic diagram of ash generation in power plant ............................................... 5
Figure 3.1 Sample collection ................................................................................................... 14
Figure 3.2 Keen‟s Box Apparatus ............................................................................................ 18
Figure 3.3 Rotary Flask Shaker ............................................................................................... 21
Figure 3.4 Sample Extraction Procedure ................................................................................. 21
Figure 3.5 pH Meter ................................................................................................................. 24
Figure 3.6 Turbidity Meter ...................................................................................................... 25
Figure 3.7 Atomic Absorption Spectrometer ........................................................................... 29
Figure 4.1 Particle Size distribution curve of fly ash............................................................... 31
Figure 4.2 Particle Size distribution curves of bottom ash and pond ash ................................ 31
Figure4.3 XRD graph of fly ash .............................................................................................. 32
Figure4.4 XRD graph of bottom ash........................................................................................ 33
Figure4.5 XRD graph of pond ash ........................................................................................... 33
Figure 4.6 SEM photography of fly ash at 1000X and 2500X ................................................ 34
Figure 4.7 SEM photography of bottom ash at 1000X and 2500X ......................................... 34
Figure4.8 SEM photography of pond ash at 1000X and 2500X.............................................. 34
Figure 4.9 Heavy metal Concentration of coal ash in L/S=100 ............................................... 38
Figure 4.10 Heavy metal concentration of coal ash in L/S=50................................................ 39
Figure 4.11 Heavy metal concentration of coal ash in L/S=20................................................ 40
Figure 4.12 Heavy metal concentration of coal ash in L/S=10................................................ 41
Figure 4.13 Heavy metal concentration of coal ash in L/S=5.................................................. 42
Figure 4.14 Total heavy metals leached from fly ash .............................................................. 42
Figure 4.15 Total heavy metals leached from Bottom ash ...................................................... 43
Figure 4.16 Total heavy metals leached from Pond ash .......................................................... 43
Figure 4.17 Heavy metal concentration of coal ash in TCLP method ..................................... 44
iii
List of Tables
Table 2.1 List of concentrations of heavy metals in the Indian fly ash by Hajarnavis (2000) .. 6
Table 2.2 List of case studies in mine filling by Murarka et al. (2006) ..................................... 9
Table 3.1 Details of water sample collection ........................................................................... 14
Table 4.1 Specific gravity (G) of coal ash ............................................................................... 30
Table 4.2 Grain size distribution of coal ash ........................................................................... 31
Table 4.3 Water holding capacity of coal ash .......................................................................... 31
Table 4.4 Chemical composition of fly ash ............................................................................. 35
Table 4.5 Chemical composition of bottom ash ...................................................................... 35
Table 4.6 Chemical composition of pond ash .......................................................................... 36
Table 4.7 Specific surface area of coal ash .............................................................................. 37
Table 4.8 pH of coal ash .......................................................................................................... 37
Table 4.9 pH range of coal ash (Hajarnavis 2000) .................................................................. 37
Table 4.10 Heavy metal concentration of coal ash in L/S=100 ............................................... 37
Table 4.11 Heavy metal concentration of coal ash in L/S=50 ................................................. 38
Table 4.12 Heavy metal concentration of coal ash in L/S=20 ................................................. 39
Table 4.13 Heavy metal concentration of coal ash in L/S=10 ................................................. 40
Table 4.14 Heavy metal concentration of coal ash in L/S=5 ................................................. 401
Table 4.15 Heavy metal concentration of coal ash in TCLP method ...................................... 44
Table 4.16 Experimental results of water quality test.............................................................. 45
Table 4.17 pH value of coal ash slurry .................................................................................... 46
Table 4.18 pH value of coal ash slurry and mine water mix in 1:1 ......................................... 47
Table 4.19 pH value of coal ash slurry and mine water mix in 1:2 ......................................... 47
iv
CHAPTER-1
INTRODUCTION
In India, large quantity of fly ash is produced from coal based thermal power plants
because most of our energy demand is fulfilled through coal based resources. In our country
fly ash generation increased from 40 Million Tons to 135 Million Tons in between 1994 to
2012. As per Technology Information Forecasting and Assessment Council (TIFAC) and Fly
Ash Utilization Programme (FAUP), the generation of ash is 300-400 MT in 2017, 500MT in
2022 and 1000 MT/YR in 2032. In the future, production rate of fly ash is likely to increase
drastically to meet power demand for number of coal based power plants contributing around
80% of total power production. However, current utilization of fly ash is rather limited and
also safe removal of this huge amount of fly ash is a big deal in order to mitigate
environmental issues arising from current disposal method. Coal is plenty available, has been
a main cause of energy till date and is likely to remain so in near future. Indian coals are low
in sulphur which generate huge amount of ash (about 35-45%), which leads to huge
generation of fly ash in India. Due to disposal of coal ash in the land causes environmental
pollution due to leaching of its toxic metal. The utilization of coal ashes is limited for
geotechnical purposes. However, many researchers discussed the utilization of coal ash in
many geotechnical applications. Non-availability and high cost of natural material such as
river sand as a filling material in abandoned mines creates problems with mine filling
operations and is largely depends on such material. Hence a suitable alternative material has
to introduce for the above stated problem and the alternatives proposed should not create any
problem with environments. As such, the present investigation is to study the suitability of
coal ash in mine filling applications. Hence utilization of a large quantity of coal ash for mine
filling and problem related to the environment can be avoided. The present work is also
1
intended to study the various environmental related issues in the application of coal ashes in
such areas through laboratory experiments.
Figure 1.1 Fly ash generation and utilisation by NTPC power plants
(http://cbrienvis.nic.in)
1.1 Origin of Project
Coal is being used effectively in many small scale and large scale thermal power projects
in India as it is cost effective and available in large quantity. Coal ash, which is the byproduct of combustion of coal in thermal power plants. The largest amount of coal ash (275
Million Tons) is being generated in India in each year and is stored in ash pond as pond ash.
Now for storage of pond ash in ash pond occupies nearly 70000 acres of land in each year,
which creates problem related to land and environment. In India, utilization of coal ashes in
areas like cement manufacturing as a partial replacement of fly ash with cement,
manufacturing of cost effective fly ash bricks, base material in road construction,
construction of dams and dykes etc. is in practice.
For minimizing surface subsidence, river sand is mostly used in abandoned coal mines
filling. Due to increase use of the river sand in civil engineering structures, the mining
industry facing shortage of river sand in the abandoned mine filling. Therefore, after
2
extraction of coal from mines, large numbers of coal mines leave without filling, which
creates surface subsidence. Therefore, the mining industry is searching for a substitute filling
material which is easily available in large quantity and in minimal cost. Therefore the current
research work is to characterize and utilize the largely available coal ashes in abandoned
mine filling applications and study the various issues related to geo environmental aspects.
1.2 Objective
The objective of the present study is

To characterize coal ash collected from TSTPS, Kaniha, Odisha.

To study leachate characteristics of coal ash by batch leaching and TCLP method.

To analyse quality of water samples collected near my area in accordance with Indian
standard (IS: 10500-2012)

To study the suitability of coal ash slurry for mine filling application.
3
CHAPTER-2
LITERATURE REVIEW
2.1 Introduction
Coal ash is the by-product produced largely from coal based thermal power plants in
the combustion process (In fig-2.1). Generally, coal ash consists of both fly ash and bottom
ash. In which fly ash is collected from electrostatic precipitator since fly ash are very fine
particle and fly in nature and large particle like bottom ash falls in the bottom hopper of a
coal burning furnace.
Fly ash contributing typically around 85-90% of the total ash production and these
lighter, light grey powder material are made up of glass spheres whose size varies from submicron to 100 microns (98% lesser than 75 microns, 70-80% smaller than 45 microns). In
general, fly ash found to have low specific gravity and density. Due to fine in nature, fly ash
specific surface area lies between 2000-6800 sq. cm per gram. Also, this ash contains a small
portion of hollow spherical particle called cenosphere having a particularly 0.4-0.6 ton per
cubic meter of bulk density, which constitute up to 5% of the ash weight. Cenosphere are
suitable to utilize for special industrial applications.
Bottom ash constitutes about 10%-15% of the overall ash produced. Bottom ash has a
look same to dark grey coarse sand and particles are clusters of micron-sized granules, up to
10 mm diameter (60-70% lesser than 2 mm, 10-20% smaller than 75 microns). Bottom ash
has a maximum density and bulk density of 1200-1500 kg per cubic meter and 1 ton per
cubic meter respectively.
In India, wet disposal of fly ash is adopted by most of the power plants in which both fly ash
and bottom ash are mixed with sufficient amount of water (75 to 80%) to form fly ash slurry
which was transported and disposed of in ash pond. After settling of ash particles the free
4
standing water is discharged to a natural water stream. The so called settled ash is generally
referred to as pond ash.
Figure 2.1 Schematic diagram of ash generation in power plant
(http://www.flyashaustralia.com.au)
2.2 Review of Literature
In this section, literature related to leaching of coal ash and some of the case study of
mine filling by coal ash has been reported.
Suresh et al. (1998) presented that ash pond is a common available dumping facility
for thermal power plants. The pond ash is exposed to weathering and the metals present in
ash travel to the soil and consequently to the ground water over a period of time. At
Vijayawada thermal power station, Andhra Pradesh, ground water quality examined has been
weakening due to the presence of fly ash ions (macro and micro such as Fe, Ca, Mg etc.)
which were leached out from the ash up to some extent. The pollution is likely to rise in the
case of toxic and other ions with the passage of time.
Hajarnavis (2000) explained the concentrations of heavy metals in the Indian fly ash
are given in Table 2.1.
5
Table 2.1 List of concentrations of heavy metals in the Indian fly ash by Hajarnavis (2000)
Metal
Concentration (mg/kg)
Fe
193-22785
Cd
20
Cr
4.0-74
Cu
5.0-73
Mn
63-722
Zn
71-815
Pb
71-815
Ni
5-300
Cherry et al. (2001) stated that the Ely Creek watershed in Lee County, VA, USA,
holds a lot of abandoned mine land ranges with acidic mine waste that defile most of the river
and its combining into Stone Creek. Acidic pH estimations ran from 2.73 to 5.2 at a few
stations all through the watershed. Residue had high contamination of iron, aluminium,
magnesium and manganese, and living space was halfway to non-supporting at 50% of the
stations because of sedimentation. Benthic macro-invertebrate overviews at six of 20 stations
examined in the watershed transformed no macro-spineless creatures, while eight others had
absolute plenitudes of stand out to nine living beings. Four reference stations held > or = 100
organic objects and no less than 13 various taxa. Ten parameters that were specifically
impacted by AMD through physical, chemical, biological and toxicological endpoints were
adjusted into an Eco-toxicological rating to structure a score of 0-100 focuses for the 20
testing stations, and the bring down the score the more excellent the AMD stress. Twelve of
the 15 examining stations affected by AMD accepted an ETR score of 13.75-57.5, which
were arranged as extremely focused on and deserving of the most elevated necessity for
future natural reclamation exercises in the watershed.
6
Praharaj et al. (2002) has reported that Fe, Ba, Cu, Mn, S, Pb, V and Zn were in
groundwater near to the ash pond in Angul, Orissa. This is because of high leachability of
numerous trace elements from fly ash by the infiltrating rainwater.
Roy et al. (2003) carried out a number of experiments found out that mining affects a
huge area of the land and affect the quality of surface and underground water. The
contaminants and toxic compounds make it unsafe for drinking and industrial usage,
disturbing the hydrology of the area. They discovered that the major sources of liquid
effluents were: surface run-off, mine water pumped put during drainage operation, spent
water from handling plants, dust extractors and dust suppression systems, and leaches/washoff from waste/tailing dumps.
As per their findings, Acid mine drainage is produced whenever in a mine of any type
permeable formations interacts with the water table, aquifer, or perched water body, or where
surface water finds its way into a mine were analysed (particularly pyrites) are present in the
ore or country rock. Amongst objectionable features of the acid mine drainage are low pH
and high levels of sulphates, iron, and total dissolved solids.
These deplete oxygen levels in the water, increase the toxicity by rendering heavy
metals soluble, and create corrosion problems. Acid mine drainage can be effectively
controlled by preventing its formation at source, by diluting the acid mine drainage to
acceptable effluent quality, and by employing standard waste water treatment methods for
neutralization and removal of dissolved solids.
In addition to the acid mine drainage, they claim another source of water pollution to
be the carry-off the fine solid particles from the surface mining sites and coal preparation
plants, especially during rainy seasons, into the streams and watercourses. Sometimes the
overburden is dumped along the banks of the streams and watercourses, causing blockage of
7
free flow and contamination of water. It has also caused a severe damage to the crops
irrigated by the river water downstream.
Plant spillage, truck haulage, conveyor transfer points, and rail wagon loading areas,
are common sources contributing fines top the surface runoff. Abandoned mine tailings, coal
refuse heaps, spoil heaps, and other waste dumps in the mining area contain significant
amounts of dissolved minerals, are chronic sources of stream pollution, apart from presenting
eyesore sights. Mining is also responsible for changing the hydrology of an area in many
ways. Subsidence due to underground mining affects underground water, disruption of
surface drainage patterns and resulting contribution to stream pollution. Sometimes it may
change the river course and discharge, thereby affecting the agriculture and flora and fauna of
the area.
Ugurul (2004) mentioned, in aquatic environment disposal of coal ash is a big
concern for environment due to the leaching of metals from coal ash. In both the ash samples
which were collected from ESP and ash pond Ca, Na, K, Mn, Fe, S and Pb indicated greatest
leachability, though, Cd, Mg, Cu, Cr, Zn and Co demonstrated least leachability. The
leachability of substantial metals was low for the examined fly ash. The low metal leaching
because of high pH brought about low damage of the leachate. The leached concentration of
Mg, Pb and Mn diminished when they were in contact with normal rock samples from below
the ash pond. Then again, the components (Na, K, Mg, Pn, Mn, and SO4) that don't or that
weakly connected with the underlying rock sorts will presumably be transported to the
ground water.
The metals from coal ash are mixed with ground water by the help of rain water or
surface water. This process is called leaching. This caused pollution in ground water. The
concentration of this leached metals are more than drinking water.
8
Pandiana (2004) proposed that fly ash has a low specific gravity, easily draining
nature, ease of compaction, insensitive to changes in moisture content, good frictional
properties, etc. can be usefully used in the construction of embankments, roads, reclamation
of low-lying areas, fill behind retaining structures, etc. It also helps in preserving the valuable
top soil required for growing food.
Mishra et al. (2006) explained fly ash composite material (FCM) as an substitute to
sand as a paste backfilling material with the adding of lime and gypsum.
Murarka et al. (2006) presented that the use of Coal Ash and their benefits and
limitations on environmentally compatible in mining. The summary is given in a tabular form
below.
Table 2.2 List of case studies in mine filling by Murarka et al. (2006)
Mine under
Investigation
Wyodak Mine
Major Findings
The normal groundwater quality in the Wyodak site
compares satisfactorily with the Wyoming department of
Environmental Quality livestock use standard. Mean
absorptions of all the measured constituents in wells are at
or below livestock standards.
Keensburg Mine
The ground water quality at the Keensburg mine does not
appear to be impacted by employment of coal ash.
Trapper Mine
Comparison of the historic groundwater absorption data with
Colorado standards show little or no sign of groundwater
impacts associated with most of the analysed ingredients.
Savage Mine
The ground water quality at Savage mine does not appear to
be impacted by placement of coal ash.
Strom Strip Mine
The down-gradient ground water quality is not affected by
coal ash placement. No ash has been sited below the water
table, because the ground water table is deeper than the mine
floor.
9
Mine under
Investigation
Universal Mine
Major Findings
The coal ash leachate defused the acidic pH, improved
alkalinity, essentially removed acidity, and considerably
decreased manganese, iron, and sulphate concentrations.
There were no signs of any other trace metal migration via
the mine seep. However, the coal ash leachate did
significantly increase boron concentrations in the mine seep
water.
Midwestern
Abandoned Mine
Alkaline coal ash decrease infiltration and increased the
water quality by neutralization.
The Arnold Willis
Groundwater monitoring records specified that trace metals
“City” Underground
and sulphides remained natural by the placement of FSS
(mixture of FGD scrubber sludge, fly ash, lime, and water).
Coal Mine
Harwick Mine
Complex
The water quality figures from samples of the mine water
indicate no adversarial effect on the water in the Harwick
Mine complex.
Clinton County
The addition of grout caused a short-term increase in pH
from about 2.3 to about 9, as the alkaline FBC ash
neutralized the acidic AMD waters. But within a short
period, the pH again became acidic.
Big Gorilla Pit
The Big Gorilla water has continued a consistently high pH
value in reply to the placement of ash. One long-term effect
of ash placement in the former Big Gorilla mine pool will be
the prevention of acidic water invention through the surface
mine pool.
Red Oak Mine
The alkalinity from the Coal ash counterbalanced the acidity
in mine pool waters, leading to a rise in pH, which in turn
caused the precipitation of metals as hydroxides and
carbonates within the mine, thereby improving water
quality.
10
Mine under
Investigation
Frazee Mine
Major Findings
The coal Ash grout combination can be usefully used for an
abandoned underground coal mine to decrease acid
formation as well to fill mine voids with a high-strength,
low-permeability
material
that
would
control
mine
subsidence. The use of the CCP grout appears to have not
caused an undesirable water quality impact either.
Prasad et al. (2007) investigated the ground water feature at the Damoda abandoned
open cast mine. They found that fluoride concentrations were initially, significantly higher
than the given drinking water specifications, but after that its concentration slowly decreased.
Concentrations of manganese were found to be raised above prescribed drinking water limits
through the period of study. The rest of the parameters were raised, but still less than drinking
water specifications in the absence of any alternative source. Ground water quality at the
outside of the ash-filled zone was apparently somewhat affected and there was no outward
effect on ground water quality half kilometre away from the ash-filled region, where the
ground water is used for drinking water.
Dutta et al (2009) proposed that substantial release of toxic heavy metals would
occur mainly under acidic leaching circumstances. The inborn alkalinity of fly ash is not
sufficient to contest this phenomenon. Since the mobility of toxic elements (except arsenic)
from fly ash was slight when the final pH of the leachate was alkaline or nearly neutral,
proper conditioning of coal fly ash with an proper lime dosing can offer a low cost practical
solution to the refilling of surface coal mines as well as remediation of acid mine drainage.
Mishra et al. (2010) proposed that the appropriateness of Talcher coal fly ash for
stowing in the nearby underground coal mines based on their physical, chemical and
mineralogical study. The physical properties such as bulk density, specific gravity, particle
11
size distribution, porosity, permeability and water holding capacity etc. have been
determined. From the chemical classification it was found that the ash samples were
enhanced predominantly in Silica (SiO2), Alumina (Al2O3) and Iron oxides (Fe2O3), along
with a little amount of CaO, and fall under the Class F fly ash group. In addition, the mineral
phases recognized in the ash samples were Quartz, Mullite, Magnetite, and Hematite. From
the particle size and permeability approach, pond ash may be considered a better stowing
material than fly ash.
Naik et al. (2012) described fly ash as a good grading material, lot of fine particles,
higher specific area and low specific gravity, which easily flows through pipe to fill the mine
voids in mines.
Shivpuri et al. (2012) suggested that elements in coal fly ash show fluctuating
behaviour for different leaching conditions like leaching medium and pH. The fly ash may be
enriched in Ca, Ni and Fe and show greater leachability in acidic or ion-exchangeable
conditions. Fe is tightly bound to the ash and does not leach simply while Ca is highly soluble
and leaches out in almost all mediums. Se, Cd and Ni leach out at less aggressive conditions
in ion exchange able conditions, while As, Cr, Cd, Pb and Zn leach under more aggressive
conditions. Also, the SO3 content of coal fly ash may affect the leaching behaviour of fly ash
as exhibited by fly Ash, which has relatively higher percentage of SO3 and indicated different
leaching trends during Sequential Extraction Procedure. Thus, toxic metal mobility is also
influenced by the mode of amount of metals within the ash, especially for the metals which
reduce on the surface of the particles in the furnace.
12
CHAPTER-3
MATERIALS AND METHODOLOGY
3.1 Introduction
The experimental program was designed to utilize the coal ash of Talcher Super
Thermal Power Station (TSTPS), Kaniha, Odisha in the abandoned mine filling. For this
purpose, laboratory tests have been conducted to characterize coal ash, heavy metal analysis
from coal ash by leaching test and study the environmental aspects.
3.2 Material used
3.2.1 Coal ash
Ash samples were collected from Talcher Super Thermal Power Station, Kaniha. Fly
ash, bottom ash was collected from the discharge point of the plant in gunny bag made of
strong poly-coated cotton with 50 kg capacity. Pond ash was collected from an ash pond in
50 kg gunny bag. The mouth of each bag was immediately closed after collection and put
those bags in another polypack to prevent atmospheric influences. The bags were transported
with utmost care from the power plant to the laboratory and kept in a secure and controlled
environment. After taking to the laboratory, the samples were screened through a 2 mm sieve,
to separate out the vegetation and foreign material. The materials are stored in airtight
container, for subsequent use.
3.2.2 Water sample
The three numbers of water samples were collected from near the abandoned coal
mine area of Mahanadi Coal field, Talcher. The samples were collected in plastic non
reacting bottles of 5 liters capacity. Immediately after collection, the bottles were recapped
and sealed by the small polythene sheet and kept in a cool place till it was carried out to NIT
13
Rourkela for analysis. The locations of sample collected are given in Figure 3.1 and Table
3.1.
Table 3.1 Details of water sample collection
Sample
No.
Sample Id
Location
Date of
Collection
1
S-1
Pond 200 Meter from
abandoned coal mines
19/12/2013
2
S-2
Tube well 500 Meter from
abandoned coal mines
19/12/2013
3
S-3
Tube well 1 K.M. from
abandoned coal mines
10/12/2013
(1)
(2)
(3)
Figure 3.1 Sample collection
14
3.3 Experimental Procedure
3.3.1 Specific Gravity Test (By Density Bottle Method) IS: 2720 (Part-III/SEC-I)
Specific gravity is defined as the ratio of the weight in air of a given volume of a
material at a specified temperature to the weight in air of an equal volume of distilled water at
a specified temperature. The purpose of the test is to define the specific gravity of soil
passing the 4.75 mm sieve by density bottle method.
50g of sample of fly ash is taken in each 3 bottles and added to distilled water; the
weight of the water + bottle is taken. Then all the 3 bottles are subjected to sand bath, heating
is done up to air bubbles are seen in the bottle. This is done to remove the entrapped air in the
mixture; the bottle is kept for around 1 hour so that the temperature comes to 27oC.
Calculation:
Specific Gravity, G 
W2  W1
W2  W1   (W3  W1 )
Where
W1= Wt. of density bottle in gm
W2=Wt. of bottle with dry soil in gm
W3=Wt. of bottle with soil and water in gm
W4=Wt. of bottle full of water in gm
3.3.2 Grain Size Analysis (By Sieve Analysis and Hydrometer Analysis) IS: 2720 (Part-IV)
3.3.2.1 Sieve analysis
Sieving is conducted by arranging the various sieves over one another in order of their
mesh openings biggest aperture at the top and smallest at the bottom. A holder is kept at the
bottom and a cover is put at the top of the whole setup. The soil is put through the top sieve
and adequate amount of shaking is done to let the soil particles pass through the various
15
sieves. 4.25mm, 2mm, 1mm, 425 micron, 150 micron and 75 micron IS sieves were used to
perform the sieving.
The results of sieve analysis are plotted on a graph of percentage passing versus the
sieve size. On the graph the sieve size scale is logarithmic. To find the percentage of
cumulative passing through each sieve, the percentage retained on each sieve is found. The
following equation is used for this:
% Retained=
X100
Where WSieve = the weight of aggregate in a particular sieve
WTotal = the total weight of the aggregate.
After this the cumulative percentage of aggregate retained in a sieve is found. To do
so, the total amount of aggregate that is retained on each sieve and the amount in the previous
sieve are added up. The cumulative percentage passing of the aggregate is found by
subtracting the percentage retained from 100%.
The values are then plotted on a graph with cumulative percentage passing on the y
axis and logarithmic sieve size on the x axis.
3.3.2.2 Hydrometer analysis
This process defines the quantitative determination of the distribution of particle sizes
in soils. The distribution of particle sizes larger than 75 m is determined by a sedimentation
process, by means of a hydrometer to secure the essential data.
Dispersing agent – Sodium metaphosphate solution is prepared in distilled or demineralized
water. 40gm of sodium hexametaphosphate/liter is used in the solution.
About 50gm of fly ash is taken and added with water and sodium hexametaphosphate
and put into the mechanical stirring cup. Stirring process occurs for a period of 15 minutes.
After that it is poured into the hydrometer flask.
16
After 20 seconds the Hydrometer is inserted gently to a depth slightly below its
floating position.
Hydrometer readings are taken in the interval of ½, 1, 2,4,8,15,30 minutes, 1, 2,
4,8,16 and 24 hours. After that it was taken out and rinse with distilled water.
The hydrometer was re-inserted in the suspension and readings were taken over
periods of 8, 15, and 30 minutes; 1, 2, 4, 8, 16 and 24 hours after shaking. The hydrometer is
removed and rinsed with water after each reading.
3.3.3 Water holding capacity of coal ash
Keen‟s Box Apparatus (Figure 3.2) was used in the experiment consisting of a brass
box (diameter approximately 5 cm and height 1.6 cm) with a perforated base.
Suitable filter paper was placed in the perforated base of the Keen‟s box and weighed
in a physical balance. The keen‟s box was filled with soil by adding small quantities at a time
and tapping the box after each addition to ensure uniform packing. Surplus soil is stricken
with a sharp blade. The box was kept in a small tray, which contained water up to ¼ inch and
left for a night. At the end of the period, the box was removed and its outside was wiped with
a dry cloth and weight was taken immediately. The box containing the wet soil was placed in
an oven and the soil was dried at 1050 C till a constant weight was obtained. The amount of
water absorbed by the filter paper was determined by taking 10 pieces of filter paper together,
weighing as such, and then saturating with water and weighing again. This moisture absorbed
by each filter paper (m) can be determined.
Calculation
Weight of box + filter paper = a gm
Weight of box + filter paper + oven dry soil = b gm
Weight of box + wet filter paper + saturated soil=c gm
Max. water holding capacity of soil =
17
Figure 3.2 Keen‟s Box Apparatus
3.3.4 BET specific surface area test (IS 11578 – 1986)
This test is established by Brunauer, Emmett, and Teller in 1938. The specific surface
area is defined as the ratio A/m (unit: m2/gm) between the total surface area of a solid and its
mass (sample weight). The surface area contains all parts of accessible inner surfaces (mainly
pore wall surfaces).
A small amount of the sample was taken on the tube and the tube was placed in a
Dewar flask containing liquid nitrogen (Liq. N2). Initially the sample was degasified to
remove the impurities and gases. Then gaseous nitrogen was passed through the sample and
based on adsorption of the gas, the surface area of the sample was calculated.
This procedure is based on, Brunauer Emmett Teller, (BET) which explain the
physical attraction of gas molecules on its solid surfaces, which is based on important
analysis for measurement of the specific surface area of material. The conception of this
theory is the extension of Langmuir theory, which says that, gas molecule monolayer
adsorption to multilayer adsorption. This hypothesis is based on (i) the gas molecules
physically adsorbed to the solid surfaces infinite no of pores. (ii) There is no interaction
18
between each layer of adsorption. (iii) After, that Langmuir theory can be applied to each
layer. The specific surface of powder or powder porous material, quantity of nitrogen covers
the surface of solid area, is calculated independently in accordance with IS: 11578-1986. The
number of such gas molecules, multiplied by the area of each molecule of contact surface
gives the total area per unit material.
3.3.5 X-Ray Diffraction of coal Ash
The X-ray diffraction technique gives the idea about the structure of the materials
which is a key requirement for understanding material properties. The process of ash
formation controls or retards the morphology and crystal growth of minerals. Even though fly
ash is regarded as an amorphous Ferro alumina silicate material, the X-ray diffraction spectra
of different fly ash indicate that they contain both crystalline and amorphous phases of
materials. The samples were dried at 105oC and mainly taken into powered form for X-ray
diffraction analysis. X-ray powder diffraction was firstly carried out on the powders for
qualitative identification of mineral phases. The sample was analysed by passing through a
Philips diffractometer with a Cu K (radiation source and single crystal graphite
monochromatic. An angular range of 10o-80o of 2 value in 0.500 increments was used
throughout.
3.3.6 Scanning Electron Microscope (SEM) AND Energy Dispersive X-Ray Spectroscopy (EDS)
of coal ash
A scanning electron microscope (SEM) is a kind of electron microscope that gives
picture of a sample by scanning it with an absorbed beam of electrons. The electrons
interrelate with electrons in the sample, creating several signals that can be detected and that
contain information about the sample‟s surface topography and composition. The electron
beam is usually scanned in a raster scan form, and the beam‟s position combines with the
identified signal to produce an image. SEM can achieve resolution better than 1 nanometre.
19
Specimens can be observed in high vacuum, low vacuum and in environmental conditions.
SEM specimens can be observed in wet conditions.
Energy dispersive x-ray spectroscopy is an analytic technique used for the
characterization of chemical constituent in the sample. It uses the x-ray spectrum emitted by
the specimen sample bombarded with a beam of electrons for chemical characterization. All
elements ranging from atomic number 4 to 92 can be detected by EDS method. Qualitative
analysis involves the identification of the spectral lines. Quantitative analysis entails
measuring line intensities meant for each element in the sample and for the same elements in
calibration standards of known composition. In the present study SEM, JOEL, JSM840A
(Japan) have been used with the gold plated sample.
3.3.7 Batch Leaching Test (ASTM- D 4793-09)
For the batch leaching test, required liquid/ solid (L/S) ratio of 5, 10, 20, 50 and 100
have been considered. Hence three 5gm samples of fly ash (as it is, without drying) in three
conical flask bottles were taken and 50ml extracting reagent (deionized water in case of our
leaching experiments) was added to each bottle. A stirring was performed on a rotary shaker
(Figure 3.3) for 24 hours. After extraction, the extracts were separated from the solid residue
by filtration through a Whatman No.42 filter paper (Figure 3.4). Five drops of 1 N Nitric acid
(HNO3) were added to it, to avoid the precipitation of some extracted metals as their
hydroxides on storage and extracts were stored in a refrigerator (4oC) until metal
determination. The metal concentrations were determined by AAS (Atomic Absorption
Spectrometer). This was repeated three times for triplicate estimation.
20
.
Figure 3.3 Rotary Flask Shaker
Figure 3.4 Sample Extraction Procedure
21
3.3.8 Toxicity Characteristic Leaching Procedure (USEPA-TCLP Method 1311)
The Toxicity Characteristic Leaching Procedure needs the use of an extraction fluid
made of buffered acidic medium to run the experiment. 1 M sodium acetate buffer was used
as an extraction liquid; pH has been maintained 5±0.01 as per United States Environment
Protection Agency (USEPA) procedure. A 5 gm fly ash sample was taken and then extraction
fluid equal to 20 times the amount of sample taken was added to it. The system was tightly
closed and then placed on the rotating shaker (Figure 3.3) for 18 hours, rotating at 30 ±2
RPM at a room temperature of about 250C. Triplicate extractions have been performed using
the same mass of the sample and the same volume of the extracting agent. Heavy metal
analysis was carried out on AAS and the results are expressed as averages of the results of
triplicate estimation. Till the metal analysis is completed the sample was stored in the
refrigerator at 40C.
3.3.9 pH of coal ash (IS 2720 (Part 26))
The coal ash samples were sieved through 425-micron IS sieve before pH test. 50gm
of the ash sample was taken in 250-ml beaker. 125 ml of distilled water was added to it. The
suspension was stirred for a few seconds. The beaker was covered with a cover glass and
allowed to stand for one hour, with occasional stirring. Then the water sample was extracted
from the beaker with the help of Whatman filter paper of 42 No. Then the collected sample
was taken for pH measurement by pH meter.
3.3.10 Coal ash slurry
The coal ash sample and normal water were mixed in a beaker with a proportion of
1:10 and kept for 24 hours in rotary shaker. Then slurry was prepared. Then slurry and mine
water (near the abandoned mine) mix has been tested with 1:1 and 1:2 proportion in rotary
shaker. For pH test, slurry and slurry mine water mix was filtered with Whatman paper No.42
and the sample was collected.
22
3.3.11 pH value (electrometric methods) (IS 3025 (Part-11))
The pH of a liquid solution is determined as the negative logarithm of hydrogen ion
concentration. At a given temperature, the concentration of the acidic or basic character of a
solution is indicated by pH or hydrogen ion concentration. pH values from 0 to 7 are falling
in acidic, 7 to 14 falling in alkaline and 7 is neutral. pH value is governed largely by the
carbon dioxide/ bicarbonate/ carbonate equilibrium. It may be affected by human substances,
by changes in the carbonate equilibriums due to the bioactivity of plants and in some cases by
hydrolysable salts. It is used in several calculations in analytical work and its adjustment to
an appropriate value is absolutely necessary in many of the analytical procedure.
Calibration
Calibrate the electrode system against standard buffer solution of known pH. Use
distilled water of a conductivity of less than 2µ Siemens at 25°C and pH 5.6 to 6.0 for the
preparation of all standard solutions. For unchanging investigation, commercially presented
buffer tablets, powders or solutions of testing quality also are allowed. Buffer having pH 4.0,
7.0 and 9.2 are available. In making buffer solutions from solid salts, all the material is
melted in it; otherwise, the pH calibration will be improper. The electrode system with buffer
solutions have been prepared and standardized with a pH similar to that of the sample, to
minimize error resulting from nonlinear response of the electrode.
Procedure

Electrodes after storage solutions were removed and washed with distilled water.

Electrodes were dry by softly staining with a soft tissue paper; standardize the
instrument with electrodes deep in a buffer solution within 2 pH units of sample pH.

Electrodes were detached from the buffer, washed thoroughly with distilled water and
stained dry.
23

Electrodes were immersed in a second buffer below pH 10, around 3 pH units
different from the first. It must be taken care that the reading must be within 0.1 units
for the pH of second buffer.

For sample analysis, balance was established between the electrodes and sample by
stirring the sample to confirm homogeneity and measure pH.

For buffered samples, the electrodes were conditioned after cleaning by dropping
them into the same sample, and reading pH.

With poorly buffered solutions, electrodes were calibrated by dipping in three or four
successive portions of samples.

The pH value was obtained directly from the instrument (Figure 3.5).
Figure 3.5 pH Meter
3.3.12 Measurement of Turbidity (IS 3025 (Part-10))
Turbidity can be determined by its effect on the scattering light, which is termed as
Nephelometry. Turbiditimeter can be used for sample with moderate turbidity and
nephelometer for sample with low turbidity. The higher intensity of scattered light, higher the
turbidity. Turbidity is an expression of the optical property that causes light to be scattered
and absorbed rather than transmitted in straight lines through the sample. The standard
24
method for the determination of turbidity has been based on the Jackson candle turbidity
meter. An indirect method is necessary to estimate the turbidity in the range of 0-5 units; the
turbidity of treated water generally falls in this range. Most commercial turbidity meters
available for measuring low turbidity give comparatively good indicators of the intensity of
light scattered in one particular direction, predominantly at right angle to the incident light.
Results of Nephlometric measurements are expressed as Nephelometric Turbidity units
(NTU). The NTU value is directly obtained from the instrument (Figure 3.6)
.
Figure 3.6 Turbidity Meter
3.3.13 Measurement of Total Suspended Solids (IS 3025 (Part-17))
The residue left after the disappearance and successive drying in oven at specific
temperature 103-105°C of a known volume of sample are total solids. Total solids include
“Total Suspended Solids (TSS)” and “Total Dissolved Solids (TDS)”. Whereas loss in weight
on ignition of the same sample at 500°C, 50°C, in which organic matter is converted to CO2
volatilisation of inorganic matter as much as consistent with complete oxidation of organic
matter, are volatile solids.
25
Procedure

A known volume of a well-mixed sample in a tarred dish ignited to constant
weight (W1) was taken.

The sample was evaporated to desiccation at 103-105°C for 24hrs.

Next the sample was cool in a desiccator and it was weighed and reading was
recorded (W2).

The dish was burnt for 15-20 minutes in a muffle furnace maintained at
550±50°C.

The dish was partly cooled in air until most of the heat was dissipated, and then
transferred to a desiccator for final cooling in a dry atmosphere and final weight
(W3) was noted.

The concentration was calculated in percentage by weight.
Calculation
The total and the unstable solids are expressed as:
Total solids, mg L = (W2  W1 )  1000 mL of sample
and
(W2  W3 )  1000 mL of sample
Where W1, W2 and W3 are noted on mg.
3.3.14 Measurement of Total Hardness (EDTA method) (IS 3025 (Part-21))
Hardness is determined by the EDTA method by alkaline condition; EDTA and its
sodium salts from a soluble chelated complex with certain metal ions. Calcium and
Magnesium ions develop wine red colour with Eriochrome black T in aqueous solution at pH
10.0 ± 0.1. When EDTA is added as a titrant, Calcium and Magnesium divalent ions get
complexes resulting in a sharp change from wine red to blue which indicates endpoint of the
titration. Magnesium ion must be present to yield satisfactory point of the titration. A small
26
amount of complexometically neutral magnesium salt of EDTA is added to the buffer. At a
higher pH, i.e. at about 12.0 Mg++ ions precipitate and only Ca++ ions remain in solution. At
this pH murexide (Ammonium Purpurate) indicator forms a pink color with Ca++. When
EDTA is added Ca gets complexes resulting in a change from pink to purple, which indicates
the end point of the reaction.
Procedure

25 or 50mL of well mixed sample was taken in a conical flask.

1-2mL of buffer solution was added, followed by 1mL inhibitor.

A pinch of Eriochrome black T was added and titrated with standard EDTA (0.01M)
till wine red colour turn to blue, the required volume of EDTA (X) was noted down.

Ammonium Purpurate was added and the volume of EDTA (Y) was noted down.

Volume of EDTA required by sample, A = (X-Y) was calculated.

For natural waters of low hardness, a larger sample volume, i.e. 100-1000mL should
be taken for titration and proportionally larger amounts of buffer, inhibitor and
indicators should be added. Standard EDTA titrant should be slowly added from a
micro burette and run a blank using redistilled, deionized water of the same volume as
a sample. Blank correction is applied for computing the results.
Calculation
Total Hardness as CaCO3 mg L = ( A  B  1000 mL of sample
Where, A= volume of EDTA required by sample
B= mg CaCO3 equivalent to 1mL EDTA titrant
3.3.15 Methodology for measurement of Alkalinity (IS 3025 (Part-23))
Sample preparation
Alkalinity of the sample can be determined by titrating with standard sulphuric acid
(0.02N) at room temperature using phenolphthalein and methyl orange indicator. Titration to
27
decolourisation of phenolphthalein indicator will indicate complete neutralization of OH- and
½ of CO3--, while sharp change from yellow to orange of methyl orange indicator will
indicate total alkalinity (complete neutralization of OH-, CO3--, HCO3-).
Procedure
3.3.15.1 Indicator method
20ml or a suitable amount of sample is pippeted into 100 ml beaker. If the pH of the
sample is over 8.3, then 2 or 3 drops of phenolphthalein indicator are added and titrated with
a standard sulphuric acid solution till the pink colour observed by indicator just disappears.
The volume of standard sulphuric acid solution used is recorded. About 2 to 3 drops of
indicator is mixed into the solution in which the phenolphthalein alkalinity has been
determined. This is titrated with the standard acid to light pink colour (equivalent of pH 3.7).
The volume of standard acid used after phenolphthalein alkalinity is recorded.
3.3.15.2 Potentiometer method
In a pipette, 20 ml or a suitable amount of sample is taken and titrated with standard
sulphuric acid to pH 8.3 and then to pH 3.7, using a potentiometer. No indicator is required.
Calculation
Phenolphthalein alkalinity (as mg/L of CaCO3) =
Total alkalinity (as mg/L of CaCO3) =
A  N  50000
V
 A  B   N  50000
V
Where,
A= ml of standard sulphuric acid used to titrate to pH 8.3,
B= ml of standard sulphuric acid used to titrate from pH 8.3 to pH3.7
N=normality of acid used, and
V=Volume in ml of sample taken for test.
28
3.3.16 Atomic Absorption Spectrometer test
Atomic absorption spectrometer (Figure 3.5) is used for detecting metals in solution.
The sample is fragmented into very small drops (atomized). It is then fed into a flame.
Isolated metal atoms interact with radiation that has been pre-set to certain wavelengths. This
interaction is measured and interpreted. Atomic absorption exploits different radiation
wavelengths absorbed by different atoms.
Figure 3.7 Atomic Absorption Spectrometer
The instrument is most reliable when a simple line relates absorption-concentration.
Atomizer or flame and monochromator instruments are key to making the AAS device work.
Relevant variables of AAS include flame calibration and unique metal based interaction.
29
CHAPTER-4
RESULTS & DISCUSSION
4.1 Introduction
The experiments have been conducted on coal ash collected from Talcher Super
Thermal Power Station (TSTPS), Kaniha, Odisha for abandoned mine filling. The analysis of
results is discussed in details in the following paragraphs.
4.2 Specific Gravity of coal ash
The specific gravity of Indian coal ash lies between 2.06-1.64 (Pandian et al. 1998)
which is much less than soil. The specific gravity of collecting sample fly ash is higher than
pond ash and bottom ash. The value of TSTPS coal ash with distilled water as pore medium
is given in Table 4.1
Table 4.1 Specific gravity (G) of coal ash
Ash Type
Specific Gravity (G)
Fly ash
Bottom Ash
Pond Ash
2.05
1.95
1.92
Specific Gravity
(Pandian et al., 1998)
2.06-1.70
2.05-1.73
2.05-1.64
4.3 Particle size distribution of coal ash
Percentage Finer (%)
100
Particle Size Distribution
80
60
40
20
0
0.001
0.01
0.1
Particle diameter (mm)
30
1
Percent Finer (%)
Figure 4.1 Particle Size distribution curve of fly ash
Particle Size Distribution
100
90
80
70
60
50
40
30
20
10
0
0.01
BOTTOM
ASH
POND ASH
0.1
Particle Size (mm)
1
10
Figure 4.2 Particle Size distribution curves of bottom ash and pond ash
Table 4.2 Grain size distribution of coal ash
Ash Type
Clay %
Silt %
Sand %
Cc
Cu
Fly Ash
50%
23%
17%
0.11
6.54
Bottom Ash
-
-
100%
2.21
1.72
Pond Ash
-
-
100%
2.5
1.03
From the grain size distribution curve (shown in Figure 4.1 and 4.2 and Table 4.2), fly
ash is fine grained substances consisting of silt and clay. Bottom ash and pond ash are poorly
graded sand.
4.4 Water Holding Capacity of Coal Ash
The water holding capacity of coal ash is given in Table 4.3
Table 4.3 Water holding capacity of coal ash
Ash Type
Water Holding Capacity, %
Fly Ash
59.90
Bottom Ash
77.34
Pond Ash
68.76
31
From the Table 4.3 it shows that Bottom ash has more water holding capacity than
Pond ash and Fly ash. The bottom ash is coarser than pond ash and fly ash. The bottom ash is
coarser than pond ash and fly ash. So water holding capacity is a function of particle size of
coal ash. The sample holding greater amount of fine particles has less water holding capacity.
So bottom ash will absorb more water after filling and allow the least amount of water to the
ground.
4.5 X-Ray diffraction of coal ash
Figure 4.3 XRD graph of fly ash
32
Figure 4.4 XRD graph of bottom ash
Figure 4.5 XRD graph of pond ash
The XRD outlines of the fly ash, pond ash and bottom ash (shown in Figure 4.3, 4.4
& 4.5) samples have specific peaks of quartz (SiO2), mullite (Al6Si2O13) and iron oxides such
as magnetite (Fe3O4) and hematite (Fe2O3) which arise in crystalline form.. In all the ash
samples, the most extreme 2θ=26.660 is known as the main peak due to quartz. The
occurrence of heavy minerals like magnetite and hematite are showed by their individual
peaks. The most common phases and minerals found in the ash samples contain quartz and
mullite. The amount of quartz increases the strength of coal ash. So after filling the
abandoned coal the place can be used for public use.
33
4.6 Morphology of coal ash
Figure 4.6 SEM photography of fly ash at 1000X and 2500X
Figure 4.7 SEM photography of bottom ash at 1000X and 2500X
Figure4.8 SEM photography of pond ash at 1000X and 2500X
34
The SEM (Figure 4.6, 4.7 and 4.8 shows) shows that fly ash samples are sphereshaped and the brighter particles are cenosphere. In bottom ash, it shows the particles are
hollow spherical and plate like structures is there. Pond ash consists of both hollow, spherical
and plate like structures. The spherical morphology of the fly ash and pond ash creates the
ball-bearing effect which affects a frictionless flow in the pipe with low wear and tear. So the
pond ash and fly ash is good for filling in an abandoned mine.
4.7 Compositional analysis of coal ash
4.7.1 Chemical composition (wt. %) of fly ash
The chemical composition of fly ash is given in Table 4.4.
Table 4.4 Chemical composition of fly ash
Compound
SiO2
Al2O3
Fe2O3
Na2O
K2O
MgO
TiO2
SO3
Zr2O3
LOI
Percentages (%)
41.24
24.17
5.58
0.53
2.15
0.76
2.09
1.07
22.38
0.13
From the Table 4.4, SiO2+Al2O3+Fe2O3=41.24+24.17+5.58=70.99%
4.7.2 Chemical composition (Wt. %) of bottom ash
The chemical composition of bottom ash is given in Table 4.5.
Table 4.5 Chemical composition of bottom ash
Compound
Percentages (%)
SiO2
35.83
Al2O3
17.51
Fe2O3
35.19
Na2O
0.81
K2O
1.02
35
Compound
Percentages (%)
MgO
0.81
TiO2
2.31
P2O5
2.30
CaO
1.10
SO3
0.34
LOI
2.78
From the Table 4.5, SiO2+Al2O3+Fe2O3=35.83+17.51+35.19=88.57%
4.7.3 Chemical composition (Wt. %) pond ash
The chemical composition of pond ash is given in Table 4.6.
Table 4.6 Chemical composition of pond ash
Compound
Percentages (%)
SiO2
55.21
Al2O3
27.93
Fe2O3
3.58
TiO2
3.85
K2O
1.63
MgO
1.04
P2O5
2.96
CaO
0.82
SO3
0.32
LOI
2.66
From the Table 4.6, SiO2+Al2O3+Fe2O3=55.21+27.93+3.58=86.72%
From the entire Table (4.4, 4.5 and 4.6) it was found that SiO2+Al2O3+Fe2O3 >70%,
as per ASTM-618, the coal ash was Class „F‟ coal ash. Class „F‟ coal ash is a better filler
material than Class „C‟ fly ash.
36
4.8 Specific Surface Area of Coal Ash
The specific surface area of coal ash is given in Table 4.7.
Table 4.7 Specific surface area of coal ash
Ash Type
Fly Ash
Bottom Ash
Pond Ash
SSA (m2/Kg)
229.5
153.4
186.7
The specific surface area of Indian coal ashes is in between 130-530 m2/Kg
(Sridharan et al., 2000). It concludes that if more in specific gravity and finer ash particles,
then more the specific surface area value.
4.9 pH of Coal Ash
The pH of coal ash is given in Table 4.8
Table 4.8 pH of coal ash
Ash Type
Fly Ash
Bottom Ash
Pond Ash
pH
7.21
6.90
7.01
Table 4.9 pH range of coal ash (Hajarnavis 2000)
pH
Class
<4.0
Highly Acidic
4.0 – 6.5
Moderately Acidic
6.5 – 7.5
Slightly Acidic
From the result of pH (shows in Table 4.9) value it is found that the coal ash of
TSTPS is slightly acidic in nature.
4.10 Leaching Analysis of Coal Ash
4.10.1 Batch Leaching Test of coal ash
4.10.1.1 For L/S=100
Table 4.10 Heavy metal concentration of coal ash in L/S=100
Metals
Fly ash
Bottom ash
Pond ash
Iron
2.129 ppm
0.91 ppm
0.998 ppm
Copper
0.098 ppm
0.019 ppm
0.017 ppm
37
Metals
Fly ash
Bottom ash
Pond ash
Magnesium
5.597 ppm
3.17 ppm8
2.997 ppm
Zinc
4.987 ppm
2.989 ppm
1.789 ppm
Lead
ND
ND
ND
Nickel
ND
ND
ND
ND: - Not Detected
L/S=100
6
F.A
P.A
B.A
Conc. (ppm)
5
4
3
2
1
0
Fe
Cu
Metals
Mg
Zn
Figure 4.9 Heavy metal Concentration of coal ash in L/S=100
From the Table 4.10 it is clear that maximum absorption of metals comes from Fly ash as
compared to Bottom ash and Pond ash.
4.10.1.2 For L/S=50
Table 4.11 Heavy metal concentration of coal ash in L/S=50
Metals
Fly ash
Bottom ash
Pond ash
Iron
3.419 ppm
1.049 ppm
1.029 ppm
Copper
0.298 ppm
0.039 ppm
0.029 ppm
Magnesium
5.879 ppm
3.926 ppm
3.059 ppm
Zinc
5.119 ppm
3.019 ppm
1.987 ppm
Lead
ND
ND
ND
Nickel
ND
ND
ND
ND: - Not Detected
38
L/S=50
7
F.A
6
P.A
B.A
Conc. (ppm)
5
4
3
2
1
0
Fe
Cu
Metals
Mg
Zn
Figure 4.10 Heavy metal concentration of coal ash in L/S=50
4.10.1.3 For L/S=20
Table 4.12 Heavy metal concentration of coal ash in L/S=20
Metals
Fly ash
Bottom ash
Pond ash
Iron
4.059
1.159
1.129
Copper
0.319
0.137
0.049
Magnesium
6.019
4.89
3.397
Zinc
5.369
3.158
2.168
Lead
ND
ND
ND
Nickel
ND
ND
ND
ND: - Not Detected
39
L/S=20
7
Conc. (ppm)
F.A
6
P.A
5
B.A
4
3
2
1
0
Fe
Cu
Mg
Zn
Metals
Figure 4.11 Heavy metal concentration of coal ash in L/S=20
4.10.1.4 For L/S=10
Table 4.13 Heavy metal concentration of coal ash in L/S=10
Metals
Fly ash
Bottom ash
Pond ash
Iron
4.979 ppm
1.258 ppm
1.917 ppm
Copper
0.398 ppm
0.149 ppm
0.053 ppm
Magnesium
6.978 ppm
5.578 ppm
3.567 ppm
Zinc
6.019 ppm
3.575 ppm
2.352 ppm
Lead
ND
ND
ND
Nickel
ND
ND
ND
ND: - Not Detected
40
F.A
L/S=10
8
P.A
B.A
7
Conc. (ppm)
6
5
4
3
2
1
0
Fe
Cu
Mg
Zn
Metal
Figure 4.12 Heavy metal concentration of coal ash in L/S=10
4.10.1.5 For L/S=5
Table 4.14 Heavy metal concentration of coal ash in L/S=5
Metals
Fly ash
Bottom ash
Pond ash
Iron
5.111 ppm
1.358 ppm
2.023 ppm
Copper
0.413 ppm
0.168 ppm
0.072 ppm
Magnesium
7.092 ppm
7.094 ppm
3.754 ppm
Zinc
6.238 ppm
3.984 ppm
2.572 ppm
Lead
ND
ND
ND
Nickel
ND
ND
ND
ND: - Not Detected
41
L/S=5
8
F.A
7
P.A
Conc. (ppm)
6
B.A
5
4
3
2
1
0
Fe
Cu
Mg
Zn
Metal
Figure 4.13 Heavy metal concentration of coal ash in L/S=5
4.10.1.6 Comparison between fly ash, bottom ash and pond ash
L/S=100
L/S=50
L/S=20
L/S=10
L/S=5
FLY ASH
8
7
Conc. (ppm)
6
5
4
3
2
1
0
Fe
Cu
Mg
Metal
Figure 4.14 Total heavy metals leached from fly ash
42
Zn
L/S=100
L/S=50
L/S=20
L/S=10
L/S=5
BOTTOM ASH
8
7
Conc. (ppm)
6
5
4
3
2
1
0
Fe
Cu
Mg
Zn
Metal
Figure 4.15 Total heavy metals leached from Bottom ash
L/S=100
L/S=50
L/S=20
L/S=10
L/S=5
POND ASH
4
Conc. (ppm)
3
2
1
0
Fe
Cu
Mg
Zn
Metal
Figure 4.16 Total heavy metals leached from Pond ash
The results of heavy metals concentration found from batch leaching test in different
liquid – solid ratio are shown in Table 4.10 to 4.14 and Figures 4.9 to 4.16. Lead and Nickel
did not leach from the coal ash sample. Magnesium and Zinc show solubility with deionized
water and leached in higher concentration in all samples of coal ash. The leached copper
43
concentration was low in comparison to magnesium; this is probably because copper is
precipitated as their insoluble hydroxides. Concentration of metals increases with the
decrease of liquid to solid ratio. So leaching of heavy metal concentration is inversely
proportional to liquid to solid ratio (L/S).
4.10.2 Toxicity Characteristic Leaching Procedure (TCLP) method
Table 4.15 Heavy metal concentration of coal ash in TCLP method
Metals
Fly ash
Bottom ash
Pond ash
Iron
2.05 ppm
2.32 ppm
1.21 ppm
Copper
7.15 ppm
5.48 ppm
8.16 ppm
Magnesium
239.97 ppm
186.68 ppm
167.59 ppm
Zinc
1.58 ppm
1.98 ppm
0.99ppm
Lead
0.89 ppm
ND
ND
Nickel
0.34 ppm
0.55 ppm
1.16 ppm
ND: - Not Detected
Result of TCLP Method
250
F.A
B.A
Conc. (ppm)
200
P.A
150
100
50
0
Fe
Cu
Mg
Metals
Zn
Pb
Ni
Figure 4.17 Heavy metal concentration of coal ash in TCLP method
The heavy metal concentrations as a result of TCLP are shown in above Table 4.15.
In this procedure sodium acetate buffer is used at pH 4.99. Mg and Cu show solubility in
44
weakly acidic medium and has been leached at higher amounts in all samples. Fe, Zn, Pb &
Ni also leached but at very low concentration. Lead is insoluble and does not leach out in
TCLP.
The concentration of metals in TCLP is found to be higher than the concentration of
metals found in the batch leaching test. This is because metal soluble generally decreases
with increase of pH. TCLP involved leaching in slightly acidic buffered condition (i.e. pH =
5) and in the batch leach test, the pH of distilled water to be added is around 7. This is due to
precipitation of metal ions as insoluble hydroxides at high pH values.
For all metals, lowest solubility is found in water extract. Trace metal concentration in
bottom ash and pond ash are lesser than fly ash. Trace element concentrations are well within
the limit of Indian standards for disposal of wastes. A similar comparison of TCLP and batch
leaching test indicated that all metals are within specified limits. So the coal ash is used as a
dry or wet disposal in the abandoned mine area.
4.11 Mine Water Assessment
Table 4.16 Experimental results of water quality test
Parameter
Sample-1
Sample-2
Sample-3
Permissible limit as per
IS 10500:2012
pH
5.01
6.51
7.56
6.5-8.5
Alkalinity (mg/L)
136.7
253
104.7
200-600 mg/L
TSS (Mg/L)
111.3
86.3
94.7
100 mg/L
Turbidity (NTU)
3.8
5.9
2.8
1 - 5 NTU
Hardness (mg/L)
295.7
559.7
426.8
200-600 mg/L
Lead (mg/L)
0
0
0.003
0.01 mg/L
Iron (mg/L)
0.153
0.061
0.014
0.3 mg/L
From Table 4.16 it is found that near the abandoned mine area water is acidic in
nature pH = 5.01), which is below the drinking standard and the pH value of water collected
away from the mines is increasing (at source 2 it is 6.51 and at source 3 it is 7.56) which is
45
between the permissible limit of Indian standards. Results of alkalinity of sample-1 and
sample-3 are below the acceptable limit of IS standard and sample-2 results in the range of
acceptable limits. Total suspended solid (111.3 mg/L) of sample -1 is above the IS standard
which is harmful to the environment. Turbidity of the sample – 2 (5.9 NTU) is above the
Indian standard range and the other two samples (3.8 & 2.8 NTU) are in the acceptable limit
of IS 10500: 2012. Hardness of all 3 samples (295.7, 559.7 and 426.8 mg/L) is in between
standard of drinking water (200-600 mg/L). For samples -1 and 2 lead percentages are not
found, but from sample–3 percentage of lead is found, it was in permissible liquid. The
concentration of iron is found below the acceptable limit.
The water collected from near the abandoned coal mine is acidic in nature (pH =5. 01)
and other parameters (turbidity, hardness, alkalinity, TSS, lead and iron) are as per IS
10500:2012.
The water collected from 500 m away from abandoned coal mine is high in turbidity
and other parameters are within the IS standard. The water collected from 1 km away from
abandoned coal mine is in the range of drinking water standard.
4.12 Coal Ash Slurry and Mine Water Interaction
4.12.1 Coal Ash Slurry
The coal ash slurry has been prepared in 1:10 proportion. The pH of the coal ash is
given in Table 4.17.
Table 4.17 pH value of coal ash slurry
Slurry Type
pH Value
Fly Ash
8.83
Bottom Ash
8.94
Pond Ash
8.75
After slurry preparation the pH value of coal ash is increased 7 to 8.3 in 1 hour.
46
4.12.2 Coal ash slurry- mine water interaction
The Coal ash slurry and mine water mixed with 1:1 proportion and the pH values
were given in Table 4.18.
Table 4.18 pH value of coal ash slurry and mine water mix in 1:1
Slurry
After 1hour pH
After 24 hour pH
Fly ash
8.15
6.72
Bottom ash
8.37
6.93
Pond ash
8.25
6.79
When the alkali slurry (i.e. pH = 8.83) mixes with acidic mine water (i.e. pH=5. 01) in
1:1 proportion its pH decreases slightly in 1 hour and after 24 hours it decreases and come to
the level of drinking water standards.
Coal ash slurry and mine water mixed with 1:2 proportion and the pH values were
given in Table 4.20
Table 4.19 pH value of coal ash slurry and mine water mix in 1:2
Slurry
After 1hour pH
After 24 hour pH
Fly ash
7.84
6.66
Bottom ash
7.90
6.94
Pond ash
7.78
6.71
When the alkaline slurry mixes with acidic mine water in 1:2 proportion its pH it
decreases slightly in 1hour as compared to 1:1 mix slurry and after 24 hours it decreases and
come to the level of drinking water standards.
47
CHAPTER-5
CONCLUSION
In the present study, the coal ash sample have been collected from Talcher Super Thermal
Power Station (TSTPS), Kaniha and water samples have been collected from Mahanadi coal
field, Talcher area. The mineralogical, morphological, chemical and geotechnical
characterizations of coal ash have been carried out. The leaching behaviour of coal ash has
been studied. The pH, turbidity, alkalinity, total suspended solids, iron and lead content of the
collected water samples from the abandoned coal mines have been determined. The changes
in slurry mine water interaction are also studied and the following conclusion has been drawn

Bottom ash absorbs more water and allows less water to the ground due to higher
water holding capacity. Water holding capacity is inversely proportional to the
particle size of the material.

Quartz, Mullite and Hematite minerals are greatly available in coal ash.

The spherical morphology of the pond ash and fly ash creates the ball-bearing effect
which affects a frictionless flow in the pipe with low wear and tear. So it can be stated
that, the fly ash and pond ash is good for filling in an abandoned mine.

From the chemical composition of coal ash it is found that it is Class „F‟ fly ash. As
per ASTM – 618 Class „F‟ fly ash is a better filler material than Class „C‟ fly ash.

The TSTPS coal ash is slightly acidic in nature.

Trace metals concentration in fly ash is more than pond ash and bottom ash in both
acidic and alkali medium.

Water sample collected near the Mahanadi Coal Field abandoned mines is acidic in
nature.
48

pH value of coal ash as found by mixing distilled water is slightly acidic (i.e.
pH=7.21). However, on mixing with normal tap water, it is becoming alkaline (i.e.
pH=8.94).

When the alkali slurry mixes with acidic mine water its pH value decreases slightly in
1hour and after 24 hours it decreases substantially and attains to the pH value (around
6.91) confirming to the drinking water standards.
49
REFERENCES
1. Amadi, A. N., Yisa, J., Ogbonnaya, I. C., Dan-Hassan, M. A., Jacob, J. O., & Alkali,
Y. B. (2012). “Quality evaluation of river chanchaga using metal pollution index and
principal component analysis.” Journal of Geography & Geology, 4(2).
2. ASTM D4793 – 09 Standard test method for sequential batch extraction of waste with
water.
3. Baba, A, & Kaya, A. (2004). “Leaching characteristics of fly ash from thermal plants
of Soma and Tuncbilek, Turkey.” Environmental monitoring and assessment, 91(1-3),
171-181.
4. Baba, A., & Usmen, M. A. (2006). “Effects of fly ash from coal-burning electrical
utilities on ecosystem and utilization of fly ash.” In Groundwater and ecosystems (pp.
15-31). Springer Netherlands.
5. Baba, A., & Ayyildiz, O. (2006). “Urban groundwater pollution in turkey.” In Urban
Groundwater Management and Sustainability (pp. 93-110). Springer Netherlands.
6. Babu, S., & Jaladurgam, R. (2014). “Strength and Deformation Characteristics of Fly
ash mixed with randomly distributed Plastic Waste.” Journal of Materials in Civil
Engineering.
7. Behera, B., & Mishra, M. K. (2012). “Strength behaviour of surface coal mine
overburden–fly ash mixes stabilised with quick lime.” International Journal of
Mining, Reclamation and Environment, 26(1), 38-54.
8. Cherry, D. S., Currie, R. J., Soucek, D. J., Latimer, H. A., & Trent, G. C. (2001). “An
integrative assessment of a watershed impacted by abandoned mined land
discharges.” Environmental Pollution, 111(3), 377-388.
50
9. Chinedu, S. N., Nwinyi, O. C., Oluwadamisi, A. Y., & Eze, V. N. (2011).
“Assessment of water quality in Canaanland, Ota, Southwest Nigeria.” Agriculture &
Biology Journal of North America, 2(4).
10. Dahl, O., Nurmesniemi, H., Pöykiö, R., & Watkins, G. (2010). “Heavy metal
concentrations in bottom ash and fly ash fractions from a large-sized (246MW)
fluidized bed boiler with respect to their Finnish forest fertilizer limit values.” Fuel
Processing Technology, 91(11), 1634-1639.
11. Das, S. K., Yudhbir. (2005). “Geotechnical characterization of some Indian fly
ashes.” Journal of Materials in Civil Engineering, ASCE, 17(5), 544-552.
12. Das, A., Jayashree, C., & Viswanadham, B. V. S. (2009). “Effect of randomly
distributed geofibers on the piping behaviour of embankments constructed with fly
ash as a fill material.” Geotextiles and Geomembranes, 27(5), 341-349.
13. Dutta, B. K., Khanra, S., & Mallick, D. (2009). “Leaching of elements from coal fly
ash: Assessment of its potential for use in filling abandoned coal mines.” Fuel, 88(7),
1314-132.
14. Farhadinejad, Z., Ehsani, M., Ahmadi-Joneidi, I., Shayegani, A. A., & Mohseni, H.
(2012). “Effects of UVC radiation on thermal, electrical and morphological behaviour
of silicone rubber insulators.” Dielectrics and Electrical Insulation, IEEE
Transactions on, 19(5), 1740-1749.
15. Fang, W. X., Wu, P. W., & Hu, R. Z. (2003). “Geochemical research of the impact of
Se–Cu–Mo–V-bearing coal layers on the environment in Pingli County, Shaanxi
Province, China.” Journal of Geochemical Exploration, 80(1), 105-115.
16. Fang, Z., & Qing, C. (2008, May). “Influence of Acid Rain on the Release
Characteristics of the Heavy Metals in Coal Ash.” In Bioinformatics and Biomedical
51
Engineering, 2008. ICBBE 2008. The 2nd International Conference on (pp. 41004103). IEEE.
17. Filippidis, A., & Georgakopoulos, A. (1992). “Mineralogical and chemical
investigation of fly ash from the Main and Northern lignite fields in Ptolemais,
Greece.” Fuel, 71(4), 373-376.
18. Foster, K. M., Rodriguez-Marek, A., & Green, R. A. “Preliminary results from a
study of the dynamic geotechnical properties of coal combustion products (CCP).” In
Geo-Congress 2014 Technical [email protected] Geo-characterization and Modeling for
Sustainability (pp. 377-388). ASCE.
19. Hajarnavis, M. R. (2000). “Studies of trace metals in acidic fly ash.” Journal of
Scientific and Industrial Research, 59(5), 381-388.
20. Hisyam bin Mohd Sani, M. S. (2012, May). “Effect of drying method on compressive
strength of special concrete with bottom ash.” In Innovation Management and
Technology Research (ICIMTR), 2012 International Conference on (pp. 475-480).
IEEE.
21. IS 2720: (1980-Part-III/sec 2) Method of test for soil, Determination specific gravity.
22. IS 2720: (1985-Part 4) Method of test for soil, Grain size analysis.
23. IS 2720: (1987-Part 26) Method of test for soil, Determination of pH value.
24. IS 11578: (1986) Method for determination of specific surface area of powders and
porous particles using low temperature gas adsorption techniques.
25. IS 3025: (1984-Part 10) Method of test for water and waste water, Determination of
turbidity.
26. IS 3025: (1983-Part 11) Method of test for water and waste water, Determination of
pH value.
52
27. IS 3025: (1984-Part 17) Method of test for water and waste water, Determination of
non-filterable residue (Total suspended solids).
28. IS 3025: (1983-Part 21) Method of test for water and waste water, Determination of
total hardness.
29. IS 3025: (1986-Part 23) Method of test for water and waste water, Determination of
alkalinity.
30. Iyer, R. S., & Stanmore, B. (1999). “The effect of water absorption and the role of
fines on the yield stress of dense fly ash slurries.” Cement and concrete research,
29(5), 765-767.
31. Izquierdo, M., & Querol, X. (2012). “Leaching behaviour of elements from coal
combustion fly ash: an overview.” International Journal of Coal Geology, 94, 54-66.
32. Kaniraj, S. R., & Gayathri, V. (2004). “Permeability and consolidation characteristics
of compacted fly ash.” Journal of energy engineering, 130(1), 18-43.
33. Kim, Y. T., Lee, C., & Park, H. I. (2011). “Experimental study on engineering
characteristics of composite geomaterial for recycling dredged soil and bottom ash.”
Marine Georesources and Geotechnology, 29(1), 1-15.
34. Kisku, G. C., Yadav, S., Sharma, R. K., & Negi, M. P. S. (2012). “Potential
environmental pollution hazards by coal based power plant at Jhansi (UP) India.”
Environmental Earth Sciences, 67(7), 2109-2120.
35. Mishra, D. P., & Das, S. K. (2010). “A study of physico-chemical and mineralogical
properties of Talcher coal fly ash for stowing in underground coal mines.” Materials
Characterization, 61(11), 1252-1259.
36. Mishra, M. K., & Karanam, U. R. (2006). “Geotechnical characterization of fly ash
composites for backfilling mine voids.” Geotechnical & Geological Engineering,
24(6), 1749-1765.
53
37. Mohanty, S., & Patra, N. R. (2012). “Assessment of Liquefaction Potential of Pond
Ash at Panipat in India Using SHAKE2000.” In GeoCongress [email protected] State of the Art
and Practice in Geotechnical Engineering (pp. 1829-1838). ASCE.
38. Newson, T., Dyer, T., Adam, C., & Sharp, S. (2006). “Effect of structure on the
geotechnical properties of bauxite residue.” Journal of geotechnical and
geoenvironmental engineering, 132(2), 143-151.
39. Ozverdİ, A., & Erdem, M. (2010). “Environmental risk assessment and
stabilization/solidification of zinc extraction residue: I. Environmental risk
assessment.” Hydrometallurgy, 100(3), 103-109.
40. Pandian, N. S. (2013). “Fly ash characterization with reference to geotechnical
applications.” Journal of the Indian Institute of Science, 84(6), 189.
41. Pandian, N. S., Rajasekhar, C., & Sridharan, A. (1998). “Studies of the specific
gravity of some Indian coal ashes.” Journal of testing and evaluation, 26(3), 177-186.
42. Patra, K. C., Rautray, T. R., Tripathy, B. B., & Nayak, P. (2012). “Elemental analysis
of coal and coal ASH by PIXE technique.” Applied Radiation and Isotopes, 70(4),
612-616.
43. Praharaj, T., Swain, S. P., Powell, M. A., Hart, B. R., & Tripathy, S. (2002).
“Delineation of groundwater contamination around an ash pond: geochemical and
GIS approach.” Environment international, 27(8), 631-638.
44. Prakash, K., & Sridharan, A. (2006). “A geotechnical classification system for coal
ashes.” Proceedings of the ICE-Geotechnical Engineering, 159(2), 91-98.
45. Prasad, B., & Mondal, K. K. (2008), “The impact of filling an abandoned open cast
mine with fly ash on ground water quality: a case study.” Mine Water and the
Environment, 27(1), 40-45.
54
46. Ram Rathan Lal, B., & Mandal, J. N. (2013). “Behavior of cellular-reinforced fly-ash
walls under strip loading.” Journal of Hazardous, Toxic, and Radioactive Waste,
18(1), 45-55.
47. Ram, L. C., & Masto, R. E. (2010). “An appraisal of the potential use of fly ash for
reclaiming coal mine spoil.” Journal of environmental management, 91(3), 603-617.
48. Sarode, D. B., Jadhav, R. N., Khatik, V. A., Ingle, S. T., & Attarde, S. B. (2010).
“Extraction and leaching of heavy metals from thermal power plant fly ash and its
admixtures.” Polish J. Environ. Stud, 19(6), 1325-1330.
49. Senapati, P. K., Mohapatra, R., Pani, G. K., & Mishra, B. K. (2012). “Studies on
rheological and leaching characteristics of heavy metals through selective additive in
high concentration ash slurry.” Journal of hazardous materials, 229, 390-397.
50. Senapati, P. K., & Mishra, B. K. (2012). “Design considerations for hydraulic
backfilling with coal combustion products (CCPs) at high solids concentrations.”
Powder Technology, 229, 119-125.
51. Shim, Y. S., Rhee, S. W., & Lee, W. K. (2005). “Comparison of leaching
characteristics of heavy metals from bottom and fly ashes in Korea and Japan.” Waste
Management, 25(5), 473-480.
52. Shivpuri, K. K., Lokeshappa, B., Kulkarni, D. A., & Dikshit, A. K. (2011). “Metal
leaching potential in coal fly ash.” American Journal of Environmental Engineering,
1(1), 21-27.
53. Shih, K., & Leckie, J. O. (2007). “Nickel aluminate spinel formation during sintering
of simulated Ni-laden sludge and kaolinite.” Journal of the European Ceramic
Society, 27(1), 91-99.
54. Singh, R., Gorai, A. K., & Segaran, R. G. (2013). “Characterisation of LD slag of
Bokaro Steel Plant and its feasibility study of manufacturing commercial'fly ash–LD
55
slag'bricks.” International Journal of Environmental Technology and Management,
16(1), 129-145.
55. Sridharan, A. (2009). “Coal Ashes in Geotechnical Engineering Practice: Beneficial
Aspects.” Emerging Trends in Geotechnical Engineering, 11
56. Suresh, I. V., Padmakar, C., Padmakaran, P., Murthy, M. V. R. L., Raju, C. B.,
Yadava, R. N., & Rao, K. V. (1998). “Effect of pond ash on ground water quality: a
case study.” Environmental Management and Health, 9(5), 200-208.
57. Tripathy, D. P., & Sisodia, A. (2014). “Some studies on the status of water quality in
an abandoned opencast limestone & dolomite quarry.” GE-International journal on
management research, Vol-2, Issue-3.
58. Tsiridis, V., Petala, M., Samaras, P., Kungolos, A., & Sakellaropoulos, G. P. (2012).
“Environmental hazard assessment of coal fly ashes using leaching and ecotoxicity
tests.” Ecotoxicology and environmental safety, 84, 212-220.
59. Ugurlu, A. (2004). “Leaching characteristics of fly ash.” Environmental Geology,
46(6-7), 890-895.
60. USEPA method 1311, (1992). “Toxicity characteristic leaching procedure.”
http://www.epa.gov/epaoswer/hazwaste/test/pdfs/1311.pdf.
61. Weng, C. H., & Huang, C. P. (1994). “Treatment of metal industrial wastewater by fly
ash and cement fixation.” Journal of Environmental Engineering, 120(6), 1470-1487.
62. Yeboah, N. N. N., & Burns, S. E. (2011). “Geological disposal of energy-related
waste.” KSCE Journal of Civil Engineering, 15(4), 697-705.
56
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement