3. COAL
Most abundant fossil fuel
Major fuel used for electricity
generation world wide
Safe and secure fossil fuel
Cost effective
4. WORLD ELECTRICITY GENERATION
(% By Fuel-2005)
Consumption by India World
Fuel (%) (%)
Oil 32 37
Natural Gas 8 24
Coal 54 27
Nuclear Energy 1 6
Hydro-Electric 5 6
Total 100 100
(Source: BP Statistical Review of World Energy 2005)
5. WORLD SCENARIO
As the International Energy Agency has
commented:
“World reserves of coal are enormous and compared with
oil and natural gas, widely dispersed... The world’s proven
reserve base represents about 200 years of production at
current rates... Proven coal reserves have increased by
over 50% in the past 22 years. The correlation of strong
growth of proven coal reserves with robust production
growth suggests that additions to proven coal reserves will
continue to occur in those regions with strong, competitive
coal industries.”
6. INDIAN SCENARIO
Coal accounts for 63% of Country’s
energy needs.
Coal based thermal power generation
capacity presently stands at 61,476MW
and a capacity addition of around 60,000
MW has been targeted in next 7 years.
Total annual hard coal production in India
is about 373.79 million tonnes (2004-05)
out of which nearly 80% is from Opencast
Mines. SCCL share is 10%.
7. INDIAN SCENARIO
Coal Demand & Production
(in Million Tonnes)
2011-12
Demand 707
Production 550
Gap 157
(Source: Coal Summit 2005)
12. Longwall in India
First mechanized powered support longwall
caving face was introduced in August 1978
at Moonidih, CIL.
First Longwall face introduced in GDK.7
Incline in September 1983 in SCCL.
There is no much improvement taken place
in India in respect of Longwall technology
due to various reasons.
13. Longwall in India
Reasons for less concentration on Longwalls in India
Serious efforts not made perhaps due to
availability of alternate technologies.
Upgrading not made when most of the world
improved in 90s.
Spares management was poor.
Coal India do not need due to opencast and
flat gradients.
Use of indigenous spares of low quality is
increased, which deteriorated the condition of
faces.
14. Australian Coal Industry
World’s largest exporter of coal
230 mt worth Au$ 16 b (Rs. 53,000 crs)
in 2004.
Most of the 74 bt reserves in NSW and QLD
378 mt in 2004, 82 mt from underground.
24 longwalls produced 73 mt in 2004 and
plans to produce 96 mt in 2006.
148 wagons per rake 2 km length, 8,500 t.
15. Australian Coal Industry
Less than 25,000 employees.
Each mine has 120 to 200 permanent
and 100 contractors’ men.
Productivity:
OMY is 15,000 t.
OMH 5t for UG, 10t for OC
16. Longwall Geometry - World
Width
Time Length (m)
(m)
1970’s 150 1200
1980’s 225 1800
Today 330 3000
18. LONGWALL GENERAL LAYOUT
TOP Gate
FACE
Dip direction
Bottom
Gate
- Longwall mining method includes drivage of two long
roadways in coal and joining them at the end by a
perpendicular drivage forming a face.
23. Advantages of Longwall Method
High Recovery.
Lower Operating Costs.
Easier to Supervise.
Easier to Train Miners.
Works Under Weak Roof.
Clean Coarse Product.
Simple Ventilation.
24. Disadvantages of Longwall Method
Small Problems = Big Production
Losses.
Dust Control Difficult.
Overloading Conveyor System.
25. Retreat Longwall Mining
Advantages Over Advance Longwall Mining
Reserves are “Proven” on Development
Gateroads in the “Solid”
Gateroad Development is Separate
Water Easier to Control
Recovering Equipment Easier
Easier Ventilation
49. STRATA CONTROL PLAN OF
A LONGWALL PANEL
1000 m
120 m
Barrier Pillar
Top Gate 50 L X C L C L
X
S
RETREAT
INDEX:
GOAF
C Convergence Station
Longwall Panel dimensions
L Load Cell 1000 m x 115 m
X Extensometers
S Stress cell
FACE
S S
Bottom Gate 53 L X X C L C L
1000 m
200 m
120 m
Barrier Pillar
Not to scale
50. Strata monitoring of in
a Longwall Panel
• Gate Road ways studies.
• Face monitoring.
• Goaf monitoring.
52. The maximum convergence depends on
the following factors
Caving properties of the strong bed
causing weightings, indicated by the
Caving Index Number ‘I’ of the strong
bed.
Thickness of cavable beds forming the
immediate roof in between strong bed
and the coal seam in terms of height of
extraction.
Resistance offered by the support
system.
53. Convergence and Roof Degradation at
Longwall Weightings (GDK.10A)
Maximum Expected Roof
Convergence Condition
Upto 60 mm/m Convergence within permissible
limit
Above 60 upto 100 mm/m Minor roof fracturing increasing
with the value of convergence
Above 100 upto 160 mm/m Significant roof fracturing and
roof degradation. Seriousness
increasing with increase in
convergence
Above 160 mm/m Rock fall zone.
54. Face monitoring–
Strata monitoring
• Leg Pressures
• Leg Closures
• Face Convergence
PRESSURE SURVEY
Continuous Pressure Recorder in Mid Face
of a Longwall Panel
40
Yield Pressure
35
30
PRESSURE (M pa)
25
Setting Pressure
20
15
33.6
39.3
56.2
74.1
95.4
111
119
141
163
180
198
220
237
259
279
305
324
345
369
386
412
FACE RETREAT in mts
55. Rated Support Resistance
The Rated Support Resistance should
take into account the following
deficiencies during the actual operation.
1. Leakage in leg circuit
2. Setting load deficiencies
3. Miscellaneous (deviation from normal
span, premature bleeding of leg
circuits, etc.)
56. Goaf monitoring – Strata monitoring
• Remote convergence indicator
• Multi Point Borehole Extensometer
(MPBEx)
CAVING OF THE STRATA WITH RESPECT TO FACE PROGRESS
sensors
SURFACE
SOIL-2.7m
YellowSST 8m
Light Brown Anc4 - 15m
SST-7m 36m
Hard Brown
Anc3 -26m
SST-17m
25m
Anc2 -37.5m
Grey & Brown 13.5m
SST-12m
Anc 1- 45m
6m
Shaly Coal3m
68.0m
80.0m
141m
Face progress Anchor1 Anchor2 Anchor3 Anchor4 Remarks
57. Longwall Caving Diagram
Main Overburden
Immediate Roof
Hc F Dc T Cl Ro
A
Gob
Shield
Hs Coal Support
Floor
Hs = Seam Height Dc = Depth of Cut Ro = Rear Overhang
Hc = Caving Height A = Caving Angle T = Canopy Tip to Face
Cl = Canopy Length F = Forward Zone Sw = Shield Width (not shown)
58. Longwall Caving
Cut after cut, shear after shear the AFC & subsequently
Chock shield supports will be advanced and the
immediate roof rock above caves in.
59. Main Fall
- As the retreat further proceeds substantial area of main
roof rock forms a plate & caves in by imposing load on
supports, known as main weighting.
66. MESHING
Wire meshing is laid in roof from 12 to 15m
behind the face stop line with individual roof
bolts for 5 to 8m and later on along with W-
straps/Channel for balance portion at 1m
interval.
Maximum height will be extracted for the last
8m from face stop line, sothat enough
clearance is there for PRS passing underneath
the line supports.
After stoppage of the face, meshing and
bolting is done to the face also.
67. DISMANTLING
All the equipment in the face are dismantled
except chocks and loaded on to the GMT (Gyro
Machine Trolley) and transported to surface of
new face.
Shearer is dismantled into two parts for easy
transport.
AFC pansets were dismantled in such a way
that 5 pansets together forms a unit for
loading onto GMT.
Similarly BSL, Belt sections are dismantled and
loaded on GMT.
68. CHOCKS TRANSPORT
PRS turning is done generally from dip to
raise and 2 buttress supports are used as
goaf edge supports at dip most point of the
face.
PRS are being marched with self hydraulic
power upto loading station and shifted on
to GMT for further transport to surface or
to new face.
77. General Organisation of SCCL
C&MD
SO Marketing
Dir/ Fin. Dir/ P&P Dir/ Oprs. Dir/ PAW Dir/ E&M
Finance Areas Areas Personnel E&M, UGM
Int. Audit Forestry Civil Medical E&M, OC
SO Safety R&D Estates PH&WS
Co. Secy. CP&P Qual. Mgt IE Central WS
Corp. Plg HRD Purchase
Cap. budget Edn. Stores
Proj. Plg. Vigilance
Explrn. Security
Survey IT
Environ. Law
78. General Organisation of Areas
GM
SO
Mines Safety
IE Civil
Finance IT
Survey Medical
HRD Purchase
Qual.Mgt. Coal handling
Personnel E&M
Township Workshop
WM Comn. Stores
79. General Organisation in the Mines
Mine Manager
Pit Office
Safety Ventilation
E&M Mntnce Min. Mntnce.
Survey Welfare
Production
Shifts
Drilling, Blasting
Loading, Transport,
Mine support,
Coal handling etc.
80. Organisation of statutory personnel
Owner Directors
on the Board
Corporate HoDs
(Deemed Agents)
General Manager
(deemed Agents)
Named Agent
(group of mines)
Mine Manager
Officers
For various
disciplines
Supervisors
Competent
persons
82. INTRODUCTION
The first Longwall was commissioned in SCCL
at GDK.7 Incline, RG-II in September, 1983.
Till now 10 sets of Longwall were purchased
by SCCL. Mainly the equipment was
purchased from UK and China.
Till now 70 Longwall panels have been
completed in SCCL and presently 4 Longwall
units are in operation in 4 Underground
mines.
83. EXISTING LONGWALL MINES OF SCCL
2006-07
S Name of the mine No of
No Units
1 PVK-5 Incline,KGM Area 1 unit
2 GDK-9 Incline,RG-II Area 1 unit
3 GDK-10A Incline,RG-II Area 1 unit
4 JK-5 Incline, YLD Area 1 unit
85. INTRODUCTION OF LW SETS
S Mine where LW sets No.of sets Support
No introduced & Yr. capcities
1 GDK.7/9 Incline, RG-II 1, 1983 4 x 360T
2 VK-7 Incline, KGM 1, 1984 4 x 360T
3 GDK.11A Incline, RG-I 3, 1990-92 4x450T(2),
4x430T(1)
4 JK-5 Incline, YLD 1, 1990 4x450T
5 GDK.9Extention, RG-II 1, 1996 4x800T
6 GDK.10A Incline, RG-II 1, 1994 4x800T
7 Padmavathikhani, KGM 2, 1995-96 4x760T
86. GDK.7 INCLINE
Longwall equipment introduced in no.3 seam
bottom section in September 1983.
After completion of two panels, due to non
availability of the property the equipment
was shifted to adjacent GDK.9 Incline.
Main Problem - Strength of coal is high for
Shearer cutting & sand stone bands running
across the panel.
88. GDK.7 INCLINE
Two panels have worked with 4x360T
supports in No.3 seam bottom section
with a face lengths of 110m and 96m.
The production achieved is 0.8LT with
an average production of 1900T/day.
89. VK.7 INCLINE
Longwall equipment with 4x360T Conventional
supports was introduced in Top seam in 1985.
With 4x360T supports, 8 panels of 120m face length
and 7 panels of 60m face length have been worked
successfully.
Second set (4x450T IFS) shifted from GDK.11A Inc in
1994 & is presently in operation.
Experience in – varied face lengths, up hill transport,
crossing the developed gallery, working in between
goaves, fault running across the panel.
Main Problems – Underrated capacity of supports,
Cavity formation.
91. VK.7 INCLINE
8 panels of 120m face length have completed
With 4x360T supports by producing around
3.6MT and daily production varied from 400
to 1800T.
7 panels of 60m face length have completed
With 4x450T supports by producing around
1.6MT and daily production varied from 1000
to 1300T.
92. GDK.11A INCLINE
Two longwall sets were introduced with
4x450T/4x430T supports during 1991, followed by 3rd
Longwall unit with 4x450T supports during 1992.
First time longwall was introduced in No.1 Seam of
Ramagundam.
Main Problems – Underrated capacity of supports,
Oblique fault running across the panel, high water
seepage, improper geo-technical investigations.
94. GDK.11A INCLINE
Longwall unit –I : 2 panels worked producing around
0.5MT of coal.
Longwall unit – II : 4 panels worked producing around
1.3MT of coal.
Longwall unit – III : 3 panels worked producing
around 0.96MT of coal.
While working with Longwall unit-II & III, experienced
more strata problems and cavity formations, due to
underrated capacity of supports.
95. PADMAVATHIKHANI
First time Chinese longwall was introduced in
PVK in 1995 in Queen Seam (Top seam).
2 sets were introduced, One in 1995 and the
other in 1996 with 4x760T supports.
11 panels have been completed by producing
around 5 MT.
Experience in – varied face lengths,
negotiation of fault, deviation of gate
roadways.
Main Problems – Non-availability of Spares.
96. PADMAVATHIKHANI
Borehole Section
showing Top seam
(Middle Section)
97. JK-5 INCLINE
Longwall with 4x450T supports (IFS) was
commissioned in June 1990.
Longwall panels were extracted in both, Top and
bottom sections of Queen (Top) seam after
allowing for goaf settlement.
2 panels in Queen seam bottom section and 8
panels in Queen seam Top section have been
completed by producing around 2.7MT of coal.
Experience in – varied face lengths, negotiation
of fault, in between goaves, steep gradient (1 in
3.6).
Main Problems – Geological disturbances, Cavity
formation, underrated capacity of supports.
98. JK-5 INCLINE
Borehole Section
showing Top seam
Top & Bottom section
99. GDK.9/9E INCLINE
Longwall equipment (4x360T) introduced in
no.3 seam bottom section in 1986 which was
shifted from GDK.7 Incline.
New Longwall set with 4x800T capacity was
introduced in No.1 seam in 1996.
Main Problem – underrated capacity of
supports for 3 seam, Cavity formation,
Insufficient geological data, slow progress in
development of panels, more water seepage,
spares mgmt.
101. GDK.10A INCLINE
Longwall equipment (4x800T IFS) was introduced in
no.1 seam in 1994.
GDK.10A longwall produced daily, weekly and
monthly record output in India. In the year 1997-98,
the mine produced 8.67LT.
GDK 10A produced 5.40 LT of coal against
the target of 5.38 LT in the year 2005-06.
Main Problem –more water seepage, non-availability
of good quality spares, Cavity formation.
104. FUTURE LONGWALL PROJECTS
• Adriyala Shaft Project
– Extension of GDK.10A dip side
• Jallaram Shaft Project
– Extension of GDK.9 Inc Dip side
• Peddampet Shaft Project
- Extension of GDK.11A Inc Dip side
• Kakatiya Longwall Project, Bhupalpally
- Steeply inclined, New mine.
• Shanthikhani Longwall Project, Bellampalli
- Extenstion of existing mine
105. STATUS OF APPROVAL OF LW PROJECTS
S. Project FR Status of EMP Status of GOI approval
No approved
by SCCL
Board
1 Adriyala July’ 2003 EC obtained Sanctioned from GoI in Sept 06
11.10.2004
2 Shanthikhani Dec’ 2003 EC obtained Submitted to GOI on 26.02.04.
24.01.2006 In principle approval received.
PIB note submitted on 01.01.05
3 KTK LW June’ 2005 EMP to be prepared Submitted to GOI 5.08.2005
4 Jallaram Oct’ 2004 Public hearing completed. Submitted to GOI 11.11.04
Application for EC under
preparation.
5 Peddampeta Dec’ 2003 Public hearing completed. Submitted to GOI 26.02.04
Application for EC under
preparation
106. ADRIYALA SHAFT PROJECT
1. Location : Ramagundam coal belt
Ramagundam Area
2. Geological Block : RG SB-II & RG SB-III
3. Geological Reserves : 109.59 Mt
4. Extractable Reserves (Apr.) : 43.38 Mt
5. Area (in Sq.Km) : 3.40
6. Capacity (MTPA) : 2.14
7. Life of the Mine : 31 years
8. Face length : 150m
9. Panel length : 700 - 1300 m
10. Depth range : 294 – 644m
11. Gradient : 1 in 6.0 to 1 in 7.8
:
107. ADRIYALA SHAFT PROJECT
Details of seams:
Seam Avg. Height of Geological Extractable Grade
Thickness Extraction Reserves Reserves
(m) (m) (Mt) (MT)
I 5.64 3.5 27.99 10.98 E
II 3.27 2.0 15.24 6.07 D
III 9.40 3.5(Top)/ 43.09 23.31 D
3.5(Bot)
IV 3.66 3.5 15.56 11.28 C
108. SHANTIKHANI LONGWALL PROJECT
1. Location : Dorli - Bellampalli coal belt
Bellampalli Area
2. Geological Block : Shantikhani Extn Block
3. Geological Reserves : 8.87 Mt
4. Extractable Reserves (Apr.) : 17.78 Mt
5. Area (in Sq. Km) : 6.81
6. Capacity (MTPA) : 1.17
7. Life of the Mine : 23 Years
8. Face length : 150m
9. Panel length : 450 - 2000 m
10. Depth range : 309 – 596m
11. Gradient : 1 in 3.5 to 1 in 5
109. SHANTIKHANI LONGWALL PROJECT
Details of seams (Phase-I)
Seam Avg. Height of Geological Extractable Grade
Thickness Extraction Reserves (Mt) Reserves
(m) (m) (Mt)
SJ Top 1.88 1.5 18.96 3.91 F
SJ Bot 3.18 2.5, 3.5 29.91 13.87 D
110. KAKATIYA LONGWALL PROJECT
1. Location : Mulug coal belt
Bhoopalpalli Area
2. Geological Block : Gollapalli block & Peddapur block
3. Geological Reserves : 67.45 Mt (Phase-I)+ 60.06 Mt (Phase-II)
4. Extractable Reserves (Apr.) : 40.02 Mt (Phase-I)+ 35.99 Mt (Phase-II)
5. Area (in Sq. Km) : 9.71
6. Capacity (MTPA) : 2.16
7. Life of the Mine : 24 + 22 Years
8. Face length : 250m
9. Panel length : 1200 - 2900 m
10. Depth range : 35 – 412m
11. Gradient : 1 in 2.8 to 1 in 3.3
111. KAKATIYA LONGWALL PROJECT
Details of seams (Phase-I)
Seam Avg. Height of Geological Extractable Grade
Thickness Extraction Reserves Reserves (Mt)
(m) (m) (Mt)
IA 2.02 2.0 12.16 7.62 E
I 2.66 2.5 17.18 9.45 F
II 2.72 2.5 17.55 9.71 F
III 3.05 3.0 20.53 13.24 B
112. JALLARAM SHAFT PROJECT
1. Location : Ramagundam coal belt
Ramagundam Area
2. Geological Block : RG SB-II
3. Geological Reserves : 206 Mt
4. Extractable Reserves (Apr.) : 79 Mt
5. Area (in Sq.Km) : 7.29
6. Capacity (MTPA) : 2.28
7. Life of the Mine : 53 years
8. Face length : 200m
9. Panel length : 500 - 1800 m
10. Depth range : 123 – 579m
11. Gradient : 1 in 5 to 1 in 8
113. JALLARAM SHAFT PROJECT
Details of seams
Seam Avg. Height of Geological Extractable Grade
Thickness Extraction Reserves Reserves
(m) (m) (Mt) (Mt)
I 5.09 3.0 53.99 14.13 E
II 2.99 2.0 27.43 12.17 E
III 8.79 3.0 (Top)/ 85.04 36.91 D
3.5 (Bot)
IV 3.00 3.0 29.19 16.21 B
114. PEDDAMPETA SHAFT PROJECT
1. Location : Ramagundam coal belt
Ramagundam Area
2. Geological Block : GDK-6B Integrated Mine Block
3. Geological Reserves : 112.62 Mt
4. Extractable Reserves (Apr.) : 41.40 Mt
5. Area (in Sq.Km) : 7.25
6. Capacity (MTPA) : 1.46
7. Life of the Mine : 32 Years
8. Face length : 150m
9. Panel length : 470 - 1200 m
10. Depth range : 118 – 443m
11. Gradient : 1 in 6 to 1 in 10
115. PEDDAMPETA SHAFT PROJECT
Details of seams
Seam Avg. Height of Geological Extractable Grade
Thickness Extraction Reserves (Mt) Reserves
(m) (m) (Mt)
II 2.64 2.0 24.27 7.06 E
III 8.69 2.0 (Top)/ 65.69 21.39 D
3.5 (Bot)
IV 2.50 2.5 22.66 12.95 B
119. Punch Longwall
Advantages
Step change in cost and productivity
More production capacity
High productivity & low cost
Longer term and higher % of reserves extraction
Easy logistics – near surface
High gate road development rates feasible
Higher and faster returns on investment
Total investment ~ $100 million – compared with >
$300 millions UG
120. Longwall Top Coal Caving (LTCC)
Technical Principle Of Top Caving
Rock stress 1st pressure Low stress Stress 2nd pressure Compact
peak abrupt drop peak stress
Pressure curve of top coalseam
Fracture
Virgin
5600
Coal Broken Coal
coal goaf
caving
2800
Working
Height
Front AFC Rear AFC
back
122. Longwall Top Coal Caving (LTCC)
Advantages of LTCC
• Increased resource recovery in thick seams (> 75%)
• Lower face working height (better face control)
• Improved spontaneous combustion control
• More efficient capital utilisation/ financial
performance
• Reduced operating costs
• Improved production consistency
• Less gate road development requirements
• Some dust and gas issues
124. INDIAN LONGWALL
- PAST EXPERIENCE:
- Introduction of advanced technology system in Indian
coal mining industry marked a major step with the
installation of first mechanized Longwall Powered support
face at Moonidih in August 1978.
- In between 1978 to 1985, a major number of first
generation Longwall faces started through out India in
various mines of CIL such as Moonidih, Jhanjra, Seetalpur,
Dhemomain and Pathakhera Colliery and in SCCL at GDK-
7 & VK-7 Incline.
125. INDIAN LONGWALL
- PAST EXPERIENCE:
- Churcha Longwall face failed due to dynamic
loading.
- Jhanjra with shallow depth Longwall working face
ran into acute spares problem.
- Kottadih face failed after successful completion of
two Longwall panels due to dynamic loading and
underrated capacity of supports.
- GDK.11A failed due to underrated capacity of
supports.
126. LONGWALL- SCCL
- PAST EXPERIENCE:
Longwall technology was introduced in
Seven mines of SCCL. Their performance
has been:
• GDK-10A, JK-5 and VK-7 Incline gave
consistently good results, and
• The other four mines GDK-7, GDK-9, GDK-
11A and PVK suffered mainly due to non
availability of sufficient geological data.
127. INDIAN LONGWALL
MAIN REASON :
Insufficient geo-technical investigations
resulted in surprises by encountering major
geological disturbances while working the
longwalls. Thus effecting the performance of
Longwalls to the maximum extent.
128. INDIAN LONGWALL
- PRESENT & FUTURE :
- With the likely reduction of contribution from Open
cast and the more or less stagnant production from
Underground 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.
- 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 proper geo-technical
investigations for effective layout of longwall
panels.
129. REASONS FOR POOR PERFORMANCE
OF LONGWALL
>Large expansion in opencast 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.
130. REASONS FOR POOR PERFORMANCE
OF LONGWALL
>Long walls 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.
>Long wall had to co exist with the conventional
mining in most of the mines, which caused
management problems.
>There were some deficiencies in the imported
spares management and the supplies were not
reaching in time.
131. REASONS FOR POOR PERFORMANCE
OF LONGWALL
>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.
132. FUTURE REQUIREMENTS
- Longwall should be promoted as a
technology mission.
- A high level thrust group could be constitute
at national level to promote, coordinate and
interact different aspects related to Longwall
technology.
133. FUTURE REQUIREMENTS
- Huge investments incurred on different
operations for extraction of coal from greater
depths in future can be attained by imposing
a special cess on present OC production or
from other sources.
- R&D efforts are to be doubled.
- Efforts are required by the policy makers to
transform ideas into actions.
134. FUTURE REQUIREMENTS
- Foreign participation is required for
extraction of thin seams and steeply
inclined seams.
- The manufacturing companies of India
such as MAMC and Jessop are to be
reconstructed/ re-organized.
- More number of longwall blocks are to be
identified to assure the market for
manufacturers.
HR - no pillar remnants Costs - lower especially support costs Personnel concentrated in one place Training - easier method to learn Roof - can be weak but might affect gateroads Product coal is easy to wash, less fines Ventilation is more concentrated - good air upwind of shearer
Baal Bone Colliery Gateroads start from open cut
South Bulga is the most productive longwall in Australia (1996) 24,000 tonnes per man year Baal Bone is very productive too
Most Gates are TWO Entry Entries are about 5-m-wide Pillar dimensions are 100 m by 35 m Note that 4-way intersections are not used
HR - no pillar remnants Costs - lower especially support costs Personnel concentrated in one place Training - easier method to learn Roof - can be weak but might affect gateroads Product coal is easy to wash, less fines Ventilation is more concentrated - good air upwind of shearer
Problems such as poor supervision, machinery breakdowns, or rook control have disastrous production consequences. Dust and gas difficult to control because of high production rates. Limited flow area down longwall face limits air quantities for dilution. Conveyor systems too small - get the biggest conveyor money can buy.
Advance versus Retreat Longwall Most if not all longwalls are retreat Reserves are well-known. Gateroads are easier to keep open - less support Development operation is totally separate from the longwall Sealing is easier if fire occurs Mine uphill, water runs downhill into the gob Shorter distance for face recovery Better gateroad conditions for ventilation
Disadvantages to Retreat over Advance Longwalls are: More money invested in initial gateroad development. - Greater capital cost. Pressure in front of the longwall face can cause gateroad problems Junction of Face and Gateroads is especially critical
You need conventional R&P mining equipment first!!! To that add the LW equipment Shields Shearer Face Conveyor CONVEYOR SYSTEM
Here is the major equipment Shields or Powered Face Supports Note the articulation and hydraulics The AFC which moves the coal off the face The shearer which cuts the coal and moves it onto the AFC The whole system moves forward Sometimes 10s of meters per day
Here is a close-up of a single shield with a section of AFC The Hydraulic Pumps for the shields are located in the headgate ahead of the face. High Pressure hydraulic fluid is delivered via appropriate hoses.
The AFC looking at the drive motors on the headgate end. Face is to the left Note the back-plate on the left side of the AFC and the cable tray for electric power to the shearer.
A close-up view of the AFC Face is to the left Note back-plate cable-tray drive cog for the shearer
Here is the same equipment only underground Note the shearer drum The cut coal is moved by the AFC UNDER the shearer in this case. The AFC is moving into the picture Note the operator carrying a remote control for the shearer
Double Ranging-Arm Drum Shearer DRDS for short Shearer rides on the AFC and is COG-DRIVEN (typically) as we saw on the prior slides. Cut coal can pass UNDER the shearer on the AFC RANGING ARMS move the cutter up or down.
Shearer Parts Frame Ranging Arms Drive System Hydraulic Motors Electrical Systems Diagnostics Systems
Shearer Parts Frame Drive System Cutting System
Here is a close-up of that shearer drum. Note the way the main body of the shearer rides on the AFC. Cut coal can pass under the AFC. No bits are in this drum just yet.
I am not advertising for anyone, but it is a good photo of a cutter bit with the water spray for dust control. Also the spray helps COOL the bit and reduce the possibility of an ignition.
Conveyors are THE MOST IMPORTANT element in getting coal out of the mine. The floor-mounted, rigid-frame conveyor is common for main-line permanent belts. The roof-hung belt with catenary idlers is common for gateroad belts.
