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Reclamation of Coal Mines by Fly Ash –
An Experience in U.S.
“Optimum Utilization of Fly Ash by Power Plants”
“Fly Ash Utilization Conference & Expo Awards” March 15-16, 2018
Mission Energy Foundation Vivanta by Taj, Dwarka, New Delhi
Presenter Dr. Shiv Kumar Dube
Senior Fellow , TERI, New Delhi
Work and Contribution: Professor Barry E. Scheetz*
Materials Research Laboratory, Materials Research Institute,
The Pennsylvania State University,
University Park, Pennsylvania, USA
* With informal permission from
About TERI
• TERI has a presence in different regions of
India with offices in Delhi, Mumbai,
Bangalore, Guwahati, Goa, Gurgaon, and
Mukteshwar. It is a highly regarded
research institution that has also
established a presence in North America,
Europe, Africa, Kuwait, and Japan.
• TERI has been at the forefront in providing
expertise and professional services to
national and international clients.
• Site: http://www.teriin.org/
About TERI’s-Mission
• Tackle issues of concernto Indian society, and the
world at large, and develop innovative and cost
effective solutions.
• Enhance networking for sustainable interventions.
• Realize potential for national and international
leadership as a knowledge based agent of change
in the fields of energy, environment, other natural
resources and sustainable development.
• Inspire and reach out to diverse stakeholders for
realizing a shared vision of global sustainable
development that could be translated into action.
About TERI
• TERI works closely with utilities, regulatory
commissions, government agencies, and
bilateral and multilateral organizations (e.g.,
The World Bank, Asian Development Bank,
Japan Bank for International Cooperation,
UK Department for International
Development, United Nations, and U.S.
Agency for International Development).
About TERI
• Dr. Ajay Mathur, TERI’s Director General was
previously the Director General of the Bureau
of Energy Efficiency in the Ministry of Power;
Senior Member and spokesperson for the
Indian negotiating team at COP-21 in Paris,
and Director of the Interim Secretariat of the
Green Climate Fund when it was initially
established. TERI has a strong reputation
with governments of foreign countries,
Central & State Government departments;
and National & International level
organizations and multilateral agencies.
India would continue to rely heavily on
coal based electricity generation
• Indian Power sector is dominated by coal
based thermal power plants, constituting
58.32% share ( ~1,92,972 MW) of total
installed capacity of ~3,30,861 Megawatt
(MW), as on December 31, 2017.
• In general, production of Indian coal
has increased by 7.5 times and
production of electricity has increased
by 13 times, since 1970-71
India would continue to rely heavily on
coal based electricity generation • Furthermore, Niti Aayog projects that the
total installed capacity for electricity generation in the country will range from 300-700 GW by 2047 under different policy initiative scenarios.
• Considering the practicality of implementation, even with best of efforts for flexibilation to diversify the fuel and technology mix in the power generation sector, India would continue to rely heavily on coal based electricity generation, accounting for at least 50-60% of the total capacity for many years.
Indian Coal Ash Scenario
• As per Ministry of Power, today, India’s Coal based thermal capacity is ~ 1,92,972 MW.
• And as per the data gathered by CEA for 155 coal/lignite based thermal power stations (installed capacity of 1,57,377 MW, the Ash generation for the year 2016-17 reported is 169.25 million tonne.
Indian Coal Ash Scenario
• As per CEA the utilization of fly ash has increased from 6.64 million tonne in 1996-97 to a level of 107.10 million-tonne by the year 2016-17 amounting to 63.28% which is behind the target set by MoEF&CC vide it’s notification dated 03.11.2009.
• The matching coal consumed was 509.46 million tonne indicating that the average ash content was 33.6% in the coal used by power stations.
Scope of Ash Utilization
• The avenues of fly ash utilization
such as in Building materials, Fly
ash bricks, Fly Ash Blocks, Panels,
Fly ash-concrete etc. provide limited
scope for Fly ash Utilization.
• The most reasonable solution for
maximum ash utilization seems to
be backfilling in mines.
Major Options for Ash filling
• Dry ash (moist) in Water pit of Mine
• Dry ash (moist) in Dry Pit of Mine
• Paste in Dry Pit of Mine
• Paste in Water Pit of Mine
• Slurry in Dry Pit of Mine
• Slurry in Water Pit of Mine
Reclamation of Coal Mines by Fly Ash –
An Experience in U.S.
• The Best Option for High Volume Fly Ash
Utilization is the Reclamation of Mine
through Coal Ash Backfilling.
• Here is a Case Study executed at Big
Gorilla Mine located in Pennsylvania, USA
Why Big Gorilla Mine?
• After careful evaluation the option No. 1 of Dry
ash (moist) in Water pit of Mine was chosen.
• This is a typical example of backfilling of coal
ash in mine filled with acidic water.
• It is pertinent to mention that there is a
legislation in West Virginia, USA that permit for
coal mining is granted only when the Coal
Mining Company agrees to take ash back in the
coal mine.
• Thus it is interesting to discuss the example of
Big Gorilla Mine.
Why Big Gorilla Mine?
• This mine was full of acidic water and had
witnessed the accident of children in the
mine.
• This backfilling has proved that mine filled
with acidic water is not the difficult case of
mine backfilling.
• The backfilling of this mine also proved that
the threat to the environment was
eliminated.
The Big Gorilla Mine pit • The Big Gorilla pit was an abandoned anthracite
surface mine located near Hazelton,
Pennsylvania in the Silverbrook Basin. It was
filled with about 427 m (1400 feet) long by 122 m
(400 feet) wide and 27.4 m (90 feet )deep.
• It was filled with about 4,23,966 m3 (120 million
gallon) of water that had been significantly
affected by AMD (Acid Mine Drainage). The
Silverbrook basin is approximately 8 km long and
1.6 km wide. It is drained by the Silverbrook
outfall which forms the headwaters of the Little
Schuykill River.
(Source Loop, Carline et al 2004)
The Big Gorilla Mine pit • This demonstration was dry to wet placement of
about 3 million tonne of Fluidized bed
combustion (FBC) ash into standing mine water.
Placement began in August 1997 and was
completed in 2004.
• The Ash was dumped into two working Platforms
by 45 tonne truck and then dozed into the pool.
As the mine pool was filled compaction was
accomplished. The ash came from Northern
eastern Power Company’s cogeneration facility in
McAdoo, Pennsylvania, which fires about 1700
tonne of coal refuse and 60 tonne of lime stone
per day. (Source Loop, Caroline et al 2004).
The Big Gorilla Mine pit • Five monitoring wells and three test boring
locations have been monitored continuously.
Numerous studies of mineralogy of the ash and
the evolution of the pit lake water chemistry have
been conducted the work used about 3 million
tonne of coal ash to eliminate the acid pool.
• The results included the possible reduction of the
acidity of the pool and decrease in some metal
concentration, a slight increase in some cations
and test of dry to wet placement.
• Some shots of Ash backfilling process could be
seen in next few slides.
(Source Loop, Carline et al 2004)
Ash input vs. pH in the Big Gorilla
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000Jul-97
Oct-
97
Jan-9
8
Apr-
98
Jul-98
Oct-
98
Jan-9
9
Apr-
99
Jul-99
Oct-
99
Jan-0
0
Apr-
00
Jul-00
Oct-
00
Jan-0
1
Apr-
01
Jul-01
Oct-
01
Jan-0
2
Apr-
02
Jul-02
Oct-
02
Jan-0
3
Date
Ash
in
pu
t (m
etr
ic t
on
s)
2
4
6
8
10
12
1497
97
98
98
98
98
99
99
99
99
00
00
00
00
01
01
01
01
02
02
02
02
03
pH
Ash Input
pH
Ash input vs. alkalinity in the Big Gorilla
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000Jul-97
Oct-
97
Jan-9
8
Apr-
98
Jul-98
Oct-
98
Jan-9
9
Apr-
99
Jul-99
Oct-
99
Jan-0
0
Apr-
00
Jul-00
Oct-
00
Jan-0
1
Apr-
01
Jul-01
Oct-
01
Jan-0
2
Apr-
02
Jul-02
Oct-
02
Jan-0
3
Date
Ash input
(metr
ic t
ons)
0
100
200
300
400
500
600
70097
97
98
98
98
98
99
99
99
99
00
00
00
00
01
01
01
01
02
02
02
02
03
Alk
alinity (
mg/L
CaC
O3)
Ash Input
alkalinity
Concentration
(mg/ L) 6/ 7/ 93 7/ 2/ 93 10/ 28/ 97 10/ 27/ 99 8/ 28/ 01
Al 3.5 4.2 0.57 0.38 0.41
Fe 0.52 0.40 0.11 < 0.020 0.15
Mn 0.71 0.72 0.011 0.010 0.014
Zn 0.22 0.20 0.008 0.052 < 0.010
* pH of water with ash -- 12.0
* pH of water in Gorilla Mine -- 12.1
Results from borehole testing of placed ash:
* The ash has a water table at the level of the Gorilla
* Capillary draw wets the ash above the water table
* The top 2 feet are hardened
Ref: Coal ash beneficial use at mine sites in Pennsylvania, Roger J. Hornberger et al.; 2005 World of Coal Ash April 11-15, 2005
Ref: Coal ash beneficial use at mine sites in Pennsylvania, Roger J. Hornberger et al.; 2005 World of Coal Ash April 11-15, 2005
An important agency to support such work • Mine Land Reclamation Center (NMRC) founded
by U.S. Congress in 1988 to deal with water
quality issues associated with coal mining.
• Headquartered at West Virginia University,
Morgantown, West Virginia.
• Director, Dr. Paul F. Ziemkiewicz
• NMLRC as a “Team Leader” of the US
Consortium formed by the USDOE/ US AID had
earlier conducted a feasibility study for filling
ash of NTPC Singrauli into Gorbi Mines of
Northern Coalfields Limited (NCL). The other
members of the consortium were Pennsylvania
State University, USA and HMI - A Hydrogeology
Expert.
An important agency to support such work
• National Mine Land Reclamation Center
(NMLRC)
• US DOE/ US AID provided technical and
financial support to do the project.
• The report was submitted to the
concerned authorities
• It recommend that Gorbi mine project is
a doable project and need to be taken up
as early as possible to avoid the damage
to the environment, specially the
prevailing underground water system.
Conclusions:
• Ash was structurally stable.
• High pH and alkalinity in Big Gorilla water
due to Ca(OH)2.
• Fe, Al, Mn, and Zn are decreased.
• No evidence of chemical change in the
Silverbrook outfall directly related to ash
placement in the Big Gorilla.
• The ash placement would decrease the
production of AMD and remove a surface
hazard.
Acknowledgement:
Profuse thanks are due to Prof. Barry E.
Scheetz of Pennsylvania State
University, USA for his candid Support.
[email protected] March 15, 2018