Reclamation of Coal Mines by Fly Ash An Experience in U.S. Presenter Dr. Shiv Kumar Dube Senior Fellow, TERI, New Delhi

Transcription

1 Reclamation of Coal Mines by Fly Ash An Experience in U.S. 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 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 * With informal permission from

2 Conference Reference

3 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:

4 About TERI s-mission Tackle issues of concern to 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.

5 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).

6 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.

7 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, In general, production of Indian coal has increased by 7.5 times and production of electricity has increased by 13 times, since

8 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 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.

9 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 reported is million tonne.

10 Indian Coal Ash Scenario As per CEA the utilization of fly ash has increased from 6.64 million tonne in to a level of milliontonne by the year amounting to 63.28% which is behind the target set by MoEF&CC vide it s notification dated The matching coal consumed was million tonne indicating that the average ash content was 33.6% in the coal used by power stations.

11 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.

12 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

13 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

14 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.

15 Location of Big Gorilla Coal Mine in Pennsylvania, USA

16 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.

17 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 m 3 (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)

18 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 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).

19 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)

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23 Spring 2001 Ash front

24 Boreholes

25 Closure status as of March 2002

26 Status of Closure as of February 2003

27 Jul-97 Oct-97 Jan-98 Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Oct-99 Jan-00 Apr-00 Jul-00 Oct-00 Jan-01 Apr-01 Jul-01 Oct-01 Jan-02 Apr-02 Jul-02 Oct-02 Jan-03 Ash input (metric tons) ph Ash input vs. ph in the Big Gorilla Ash Input ph Date

28 Jul-97 Oct-97 Jan-98 Apr-98 Jul-98 Oct-98 Jan-99 Apr-99 Jul-99 Oct-99 Jan-00 Apr-00 Jul-00 Oct-00 Jan-01 Apr-01 Jul-01 Oct-01 Jan-02 Apr-02 Jul-02 Oct-02 Jan-03 Ash input (metric tons) Alkalinity (mg/l CaCO3) Ash input vs. alkalinity in the Big Gorilla Ash Input alkalinity Date

29 Concentration (mg/ L) 6/ 7/ 93 7/ 2/ 93 10/ 28/ 97 10/ 27/ 99 8/ 28/ 01 Al Fe < Mn Zn < 0.010

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31 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 * ph of water with ash * ph of water in Gorilla Mine

32 Field Bearing Capacity Testing [average >10,000 psf] X X X X X X X X X X

33 Silverbrook Outfall

34 Ref: Coal ash beneficial use at mine sites in Pennsylvania, Roger J. Hornberger et al.; 2005 World of Coal Ash April 11-15, 2005

35 Ref: Coal ash beneficial use at mine sites in Pennsylvania, Roger J. Hornberger et al.; 2005 World of Coal Ash April 11-15, 2005

36 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.

37 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.

38 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.

39 Acknowledgement: Profuse thanks are due to Prof. Barry E. Scheetz of Pennsylvania State University, USA for his candid Support.

40 March 15, 2018