Longwall exp india-expectations

Longwall Mining in India-
Experiences and Expectations

SYNOPSIS:

With ever increasing demand of coal, need for implementation of bulk
producing coal-mining projects has become inevitable. In the past two decades the
increased demand for coal was met by opening more number of opencast mines. With
the depletion of shallow reserves its high time that most modern high productive
technologies are adopted in future. Mechanization in underground mines has been
very slow; particularly disappointing has been the performance of high
investment/high technology Long wall. It is accepted that mechanization is essential
not only to reduce human drudgery in manual mining, but also for economic survival.
Very low productivity and high rate of accidents due to large employment at active
working zones make one wonder as to how is it that there has not been much of
change in underground mines. This paper attempts to deal with longwall experiences
in India and various reasons for slow progress of longwall mining and the necessity
for immediate action for long term sustenance of coal mining industry.

ENERGY SCENARIO

World

Economic growth the world over is driven by energy, whether in the form of
finite resources such as coal, oil and gas or in renewable forms such as hydroelectric,
wind, solar and biomass, or its converted form, electricity. Coal provides for around
23% of global primary energy needs and generating 38% of world’s electricity at
present. World coal consumption is projected to go up from 4.7 billion tonnes in 1999
to 6.4 billion tonnes by 2020 primarily in China and India, which are expected to
account for 75% of the increased consumption.
Coal use in developing Asia alone is projected to increase by 1.8 billion tons.
China and India together are projected to account for 29 percent of the total increase
in energy consumption worldwide between 1999 and 2020 and 83 percent of the
world’s total projected increase in coal use, on a BTU basis.

INDIA
Coal accounts for 63% of the country's energy needs. Commercial energy
consumption in India has grown from a level of about 26% to 68% in the last four & half
decades. The current per capita primary energy consumption in India is about 243
kgoe/year, which is well below that of developed countries. Driven by the rising
population, expanding economy and a quest for improved quality of life, energy usage in
India is expected to rise to around 450 kgoe/year in 2010. Considering the limited reserve
potentiality of petroleum & natural gas, eco-conservation restriction on Hydel projects
and geo-political perception of nuclear power, coal will continue to occupy centre-stage
of India's energy scenario.
India’s installed capacity for power generation has tripled over the last 20 years
and now exceeds 101,000 MW. However, the total demand is expected to increase by
another 3.5 times in the next two decades, even under a best-case scenario that envisions
intensified efforts to modernize power plants, improve transmission and distribution
efficiency, and adopt more efficient generation technologies.
The soaring demand for power will necessitate a tripling of the installed
generation capacity from 101,000 to 292,000 MW over the next two decades. The
projected fuel mix for power generation from various sources is shown below. At least
two-thirds of this power will have to come from thermal sources—coal, oil and gas—

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even under the best-case scenario (Best Case Scenario- BCS, Business As Usual- BAU).
This will mean a spiraling cost for imported fuels, including coal, since even a doubling
of domestic coal production would not be sufficient to meet the demand.

The overall growth in demand for all forms of fuel will mirror the growth in the
power sector. Even under the alternative scenario, total coal demand will nearly double,
and both oil and gas demand will triple, as shown in Table 1. There does not appear any
alternative to coal for meeting the energy needs of the country in the foreseeable future.
Table-1
Year Coal Oil Gas
(Million tonnes) (Million tonnes) (Million tonnes)
1997 311 83 21.5
2020 (BAU) 688 245 70.8
2020 BCS 538 195 64.7
Source: Planning Commission’s India Vision 2020
COAL RESERVES- TECHNOLOGICAL OPTIONS

India is the third largest coal producer in the world. With hard coal reserves of
around 240 billion tonnes, out of which 90 billion tonnes are proven, Indian coal offers a
unique eco-friendly fuel source to domestic energy market for the next century and

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beyond. In World’s hard coal production scenario1, 70 percent of coal comes from
underground mining. Out of the total underground production 70% is contributed by
mechanized longwall constituting about 50% of the total hard coal production. Scenario
in India is just the reverse.
Total annual coal production in India is about 340 million tonnes (m.t) out of
which nearly 80% is from Opencast Mines. Coal India produces about 90% of total
Indian coal production and SCCL’s share is about 10%. Coal production has to be
increased by over 500 m.t in the next 15 years 2, Public sectors companies are expected to
increase their production level by over 250 m.t by 2011-12, a gap of over 260 m.t which
still remains would have to met by imports or induction of private capital.

The proven technology for production and productivity all over the World is
Longwall. Longwall mining in the world is moving towards increased face dimensions,
least cost per tonne, higher productivity and lesser face transfer periods. The production
from each face is ranging from 1 million tonnes per annum (mtpa) to 4 mtpa, though
there are certain extremes of 8 mtpa.

The trend for the past three decades (during post nationalized period) in India of
meeting the increased demand of coal by opening more number of open cast mines
cannot continue indefinitely. Especially this assumes greater significance in view of the
higher (Two and a Half times) Reserves/Production ratio of underground mineable
reserves when compared to opencastable reserves. Environmental degradation, problems
in diverting forestland may further limit the expansion of open cast mines.
The increasing trend in the consumption of coal requires the construction of new
mines and expansion of existing mines. The future challenges are confined not only to
increase the coal production but also to increase the coal recovery, productivity, health
and safety conditions and to minimize environmental disturbances resulting from the
production processes. In view of long gestation period for deep underground mines it is
time that appropriate strategies for meeting demand of coal from underground mines are
put into operation. For bulk production of coal from underground mining, particularly at
greater depths, the proven technology world over is Long wall. To compensate the
diminishing production from opencast mines, longwall faces are to be planned with
minimum production capability of 1 million tonnes per annum.

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For economic survival of the nation, not only the physical targets of coal
production are to be fulfilled, but also is to be produced at competitive costs. In
formulating an overall strategy on the means and measures of raising the quantum of
production, a major consideration will be that of choice of technology.

The reserves amenable to opencast mining also include reserves locked up under
reserves forest, under built up area, which are difficult to evaluate under the present
socio-political milieu. As the opencast mines are gradually going into adverse economic
stripping ratio, higher production has to be achieved from underground mines to meet
growing demand of coal4.

Thickness wise coal reserves in India

Coal seam thickness (m) % of share
0.5.1.5 15
1.5.3.5 15
3.5.5.0 12
5.0.10.0 20
10.0.20.0 19
Above 20 19
Longwall mining, with its accompanying advantages of higher extraction, increased
safety and higher established as a mining method for coal seams of 1-5m thickness,
although the initial investment for longwall mining panel is substantially higher than that
for bord & pillar method. In other words this method assumes greater importance because
much of high quality coal found in deeper seams can be mined out only by Longwall
mining method.

The tables / graphs given below present the status of longwall in India.
LONGWALL PRODUCTION
(LT)
YEAR CIL SCCL
1983-84 1.33
1984-85 3.99 2.47
1985-86 6.48 5.75
1986-87 11.05 6.18

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1987-88 8.13 6.12
1988-89 11.82 6.12
1989-90 11.86 4.62
1990-91 14.87 6.32
1991-92 14.12 12.17
1992-93 11.08 13.2
1993-94 10.72 16.1
1994-95 18.19 10.4
1995-96 15.84 20.19
1996-97 14.52 22.9
1997-98 11.15 19.3
1998-99 17.59 16.42
1999-00 19.34 15.79
2000-01 13.66
20001-02 11.27
STATUS OF INDIAN LONGWALL MINING

Sl.No. PROJECT Rated Capacity
(TPD)
ECL
1 Jhanjra 1&2 Inc. 1476
2 Jhanjra 1&2 Inc. 3000
3 Jhanjra-MIC 1476
BCCL
4 ML-IV 860
5 ML-V 840
6 ML-VI 470
7 ML-VII 3200
SECL
8 Balarampur 1950
9 New Kumuda 1950
10 Rajendra 2300
SCCL
11 VK-7 Inc 1600
12 JK-5 Inc 2000
13 GDK-10A Inc 2200
14 GDK-9 Inc 1900
15 PVK 2200

India was not a late starter in its approach towards this technology, but for reasons
discussed in this paper, Longwall mining had limited success so far. However in view of
the necessity for exploiting deeper deposits and for the aforementioned reasons
(Demand-Supply, Reserves etc.,) there is no doubt that Longwall Mining will be the need
of the day. Hence it is imperative to reflect on our (Indian) experiences in Longwall

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mining and arrive at tangible measures to make Longwall mining in India more
productive and progressive.

INDIAN LONGWALL MINING- PAST EXPERIENCES

In seventies, the mining community of India at large, forced by the technological
developments in the competitive oil industry, was forced to make substantial progress in
terms of productivity and cost reduction. During this period there were many innovative
initiatives and successful projects, which gave the required boost to the mining industry.
With this tempo the industry marched forward for considerable period. It will not be out
of place to mention that the during those eventful years there was overall development in
all mining technologies irrespective of their contribution to the overall quantity of
production. Further, sufficient thought, innovation and development took place in all
direction. The longwall technology was also give the required attention along with others
and ambitious projects were envisaged. Unfortunately, this tempo could not be continued
as a result of exploration shallower deposits.

The introduction of first mechanized powered support longwall caving face in
August 1978 at Moonidih marked a major step forward in the introduction of advanced
technology mining system in India coal Industry. In between 1978 to 1985, a number of
first generation mechanized longwall packages were introduced in Moonidih colliery
(total 3 longwall packages, first one installed in August 1978, second one in July 1980
and third one in October 1985 of Jhanjra Coal field, Seetalpur colliery (One longwall
package installed in October 1982) and Dhemomain colliery (one longwall package
installed in November 1982) of Raniganj Coalfield, Pathakhera colliery (One longwall
package installed in September 1982) of Satpura coal basin and GDK-7/VK-7 mines of
Singareni Collieries Company Limited (One longwall package in each mine, first one
installed in September 1983 and the second one installed in June 1985) of Pranahita
Godavari Valley Coal field.

In SCCL, Longwall technology was introduced at GDK-7 Incline in 1983 and
after successful completion of two faces equipment was shifted to GDK-9 Incline where
the Longwall face collapsed due to inadequacy of support capacity. In GDK-11A initially

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3 longwall faces have planned with 450T capacity supports, which also failed due to
underrating of supports. Later in GDK-10A Incline Longwall method is introduced with
increased capacity of powered supports (from 450 to 800T) where it worked successfully
by producing 3.5MT of coal. First time in PVK, 2-Chinese Longwall sets are introduced
to work the Top seam coal, performance of these sets are good to some extent, but
effected by lot of breakdowns of Shearer and other connected machinery with poor
metallurgy. In VK-7 Incline first Longwall face was introduced in 1984 with 360T
capacity, in due course of time the face length is reduced to 90m 150m to suit the
underrated capacity of supports. JK-5 Incline Longwall experiences are also in the similar
lines with further successful experiments in working under caved goaf and working in
inclined seams (1 in 3).
The faces at SCCL in GDK-7 and VK-7 did well in comparison with the other
faces, which experienced caving difficulties. The supports, which were underrated, got
damaged. Among various designs of longwall cutter loader, the Anderson-Shearer type
has been found to be the most successful.
In early nineties, higher capacity longwall powered supports were provided for
the faces at Churcha (seam V) in SECL, Jhanjra (RVII seam) in ECL, JK-5 (Queen
seam), GDK-11A 3sets (seam-1), GDK-10A (seam-1) and PVK (Queen seam)-2sets.
Churcha longwall face, which was worked with 680T supports, yielded promising
results initially but collapsed at a distance of 189m from barrier due mainly to dynamic
weighting.
The Jhanjra project represents a totally unique situation. The depth of mining was
less than 50m in most of the panels with thickness of hard cover as low as 16m at some
locales. This project, which was started in collaboration with USSR, ran into acute spares
problem due to turmoil in USSR. Later determined efforts by our people made the
development of indigenous spares possible.
Longwall faces at Kottadih worked well with single lift extraction of 4.5m but
third panel of Kottadih collapsed due to dynamic weighting and underrated supports
causing three fatalities. The longwall powered supports from Dhemomain and Churcha
projects were shifted to Jhanjra.

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The unfavorable Geo-mining condition has been the main hindrance in the
success of longwall technology. This is evident from the fact that a number of longwall
faces, which were planned for the working longwall, have been withdrawn. Moonidih
project, Pooteki-balihari project, Balgoth project of BCCL had to be changed from
Longwall and similarly longwall planned in Kaju area of CCL had to abandoned due to
presence of dykes/faults etc.
Barring the collapses, first at Churcha and then at Kottadih, the faces at Jhanjra,
GDK-10A, JK-5 and VK-7 mines in SCCL gave consistently good results.

LONGWALL TECHNOLOGY IN INDIA - THE PRESENT AND THE FUTURE

For depths beyond 300m, Long wall is likely to be the main method for bulk
production, and probably continuous miners will be used wherever conditions permit.
Unfortunately no serious efforts has been made in respect of R&D for liquidating
standing pillars which account for huge locked up reserves to the tune of about 3000
million tonnes. Maintaining these workings itself involves high cost in addition to losses
due to deterioration, fires and safety problems. Present method of extraction of these
reserves particularly in multi-seam workings by stowing is a slow process and the
availability of sand is not assured in many coal-mining areas. There is an urgent need for
planning liquidation of these reserves by mechanized methods. It is possible to use
Longwall at many such places but the same needs determined effort and major policy
decisions. There is a need to look objectively in order to avoid earlier mistakes from
recurring. With the likely reduction of contribution from Open cast and the more or less
stagnant production from Underground mining by Conventional methods, it is time that
an impetus is given to boost Long wall Technology to able to meet the future energy
needs of the country.

Though the first fully mechanized Long wall face was commissioned in India in
1978 in Moonidih Colliery and more long wall sets came up in CIL and SCCL, Long
wall mining has not really taken off in India, barring a few exceptions of moderately
successful faces (in range of 2500 to 3000 t/day). Even the one’s which have
comparatively performed better have not proved economically viable beyond

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second/third year of operation due to variety of reasons. In retrospect it appears that the
Longwall technology in India has neither been accepted nor rejected.

In all the forums and discussions at various levels it is accepted that longwall
technology needs to be pushed forward vigorously. There is a consensus also that time is
running out and unless immediate steps are taken coal industry may be facing a serious
problem because the gestation period in underground projects is quite long. Something
more than seminars, discussions, forming committees needs to be done. In the present
public sector scenario longwall is difficult to work economically as is the case with most
of the underground mining, yet there is no alternative to longwall on long term, if coal is
to be produced from underground.

On the positive side, coal companies have now gained sufficient experiences right
from senior executive level to front line workforce to be able to plan, execute and work
longwall faces. What are required are policy decisions and logistics. It is obvious that
with the high cost of imported equipment and irregular supply of critical spares, without
large blocks of coal identified for longwall, hesitation to make investment in view of its
limited economic success has resulted in slow pace of longwall. The reasons for failure
are not due to any deficiency in the technology but due to comparison of the economics
with the opencast providing short-term cheap alternative. Yet the fact remains that
beyond 300mts depth, Longwall method of mining will remain predominant method of
work and it is better that solutions are sought now.
LONGWALL IN SCCL- FUTURE

1. 14 Coal Mining Blocks have been identified in SCCL and the project reports in
respect of Seven Projects are in various stages.
2. A beginning is made in regard to Shaft sinking in GDK-10A property for reaching
deeper deposits of GDK-10A and the same will be replicated for Vakilpalli block
also. Further, the Bhoopalpalli coalfields (KTK-7 & KTK-8 Blocks) of SCCL are
steeply inclined where it is proposed to introduce Longwall technology. In view
of the limited in house expertise in working inclined seams with longwall
mechanization, consultants are being contacted for developing effective method
of mining.

LONGWALL TECHNOLOGY- REASONS FOR SLOW PROGRESS

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 Large expansion in open cast mining in the past two decades provided cheaper
and safe method for bulk coal production and as a result long wall had to take
back seat.

 Clear strategies were not pursued for its sustenance as there was mixed results
from long wall in the early years of its introduction.

 Longwalls were introduced mostly in the blocks left over by working bord and
pillar method. Clean and extensive blocks have not been identified. Even the
smaller blocks, which were identified, were of inferior grade coal.

 Longwall had to co exist with the conventional mining in most of the mines,
which caused management problems.

 There were some deficiencies in the spares management. Most of the spares had
to be imported and the supplies were not reaching in time.

 Coal companies were sensitive to the failures of a few long wall faces and were
not prepared to risk huge investments.

 Development could not keep pace with the extraction of Long wall panels, slow
progress in dip has delayed the formation of Long wall panels and affected the
performance.

In spite of Long wall not having achieved any great success yet the cost of production in
Long wall taken alone, safety and productivity are in favour of Long wall than any other
underground method5. The accident statistics reveal that the fatality rate for million
tonnes of coal produced by Longwall is very near to that of opencast.

RECOMMENDATIONS

a. Long wall should be promoted as a technology mission.

b. A high level thrust group could be constituted at national level with the following
objectives:
 To render expertise in long wall
 To promote research and professional excellence with technological
forecasting
 To interact with national and international organizations working in the
field for the promotion of the Long wall technology in Indian coal industry
 To coordinate the activities of various companies connected to Longwall
in the country to avoid duplication
 To identify and plan the training needs of long wall technology in the
country.

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c. Huge investments are required for extraction of coal from depth (more than
300m). Detailed exploration, sinking of shafts, development of infrastructure for
introduction of Long wall technology requires advance planning as the gestation
periods are long. But all these have to be treated as an investment for future. It is
suggested that special funds are generated by a cess on current OC production or
from other sources. This could be utilized for development of Long wall blocks
beyond 300m including shaft sinking, tunnel drivage, trunk roads and exploration
etc., a separate company or department could be formed to undertake exclusively
Long wall/ infrastructure development activities. Theses blocks may be planned
to last for 10 years and could be given to coal companies on the risk/gain share
basis, for high performance long wall faces. Only then it could be expected that
the long walls perform to the international standards.

d. R&D efforts are required for extraction of standing pillars, which approximate to
about 3000 million tonnes up to a depth of 300m. Approximately one third of the
standing pillars could be liquidated by application of modified Long wall system,
which could also open up large vistas for introduction of Long wall. This could in
turn give a fillip for the development of indigenous long wall equipment. It would
economic working of long wall in the country.

e. Concerted efforts are required by the policy makers, Coal companies and
manufacturers to translate the ideas into concrete action and reap the benefits of
technology in the years to come.

CONCLUSION

1. Decision-making by persons not conversant with Longwall is one of the factors
for poor performance of Longwall.
2. Improper Maintenance, indegenisation of Spares with inadequate expertise are
major reasons for the Indian Longwall failure
3. Adequate Support Calculations and implementation of Rapid face advance are
essential for the LW success.
4. Though Longwall expertise is there/they are not properly strengthened. Hence the
work done in past 20 years for indegenisation, which is the middle level of
learning curve, is not properly utilized. If proper strategies are adopted there is a
definite chance to climb the learning curve.

5. Foreign participation is required for extraction of thin seams and steeply inclined
seams. This may be adopted as a joint venture participation with country having
such expertise.

6. The manufacturing companies of India such as MAMC and Jessop are to be
reconstructed/ re-organized (with private company participation) to develop
quality indigenous longwall equipment with the collaboration of foreign

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manufacturing companies and even manufacturing of the equipment by the
foreign companies in India. This is possible only when sufficient numbers of
longwall blocks are identified and sufficient market is assured.

7. There is the capability to plan and execute longwall projects provided Govt. or
coal companies are prepared to make investments. There is also a need to have a
body at National level for policy guidance, R&D development, awareness and
monitoring to ensure implementation of long term strategies in respect of bulk
coal production from longwall on the lines of technology missions functioning in
respect of other important areas like C.DOT, Irrigation (Central Board of
Irrigation and Power) etc.

8. Concerted efforts are required by the policy makers, Coal companies and
manufacturers to translate the ideas into concrete action and reap the benefits of
Longwall Technology in the years to come.

ACKNOWLEDGEMENT

The views expressed are those of the authors and should not be attributed to
Singareni Collieries. Nor do any of the conclusions represent the official policy of
Singareni Collieries or it’s Directors or the country they represent.

REFERENCES

1. SN. Mukherjee., IM&EJ, Feb 2000, a Technical paper on “Future of underground
mine mechanization in India”.
2. Anwar Ahmed, EE (E&M), CMTM, March 2003, a Technical paper on
“Challenges before coal industry & strategies ahead (Balrampur Longwall
Experience)”.
3. Mukunda Reddy, CGM, SCCL., Indo-polish working group, a Technical paper on
“Technological options for future coal mining – A review”.
4. “Compendium on Experiences of Longwall Technology”, SCCL, June 2002.
5. CL.Hanjura, D.Suresh, L.Sudhakar, SCCL, MMF, December 2002., a Technical
paper on “Longwall technology – the need for promotion”.
6. Information Bulletin published by the Ministry of Coal, India

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