The document compares the operational difficulties of longwall mining in dip-rise panels versus strike panels. Dip-rise panels have more challenges, including more difficult gate road development and material transport, increased water pumping requirements, higher risk of face spalling, and reduced production rates. Strike panels are preferable from an operational perspective where feasible, with difficulties in strike panels addressed through oblique gate road development and increased roof support. Dip-rise panels present overcomeable difficulties but require more effort to operate safely and efficiently.

1. “COMPARISION OF
OPERATIONAL DIFFICULTIES
IN LONGWALL DIP RISE &
STRIKE PANELS”
- A.Venkateshwer Reddy,
Addl. Manager,
Project Planning Department
The Singareni Collieries Company Limited

2. BACK DROP
• It is necessity to explore low capacity
Longwall mining, where geological
conditions permits to work 500m to 1000m
length panels in SCCL to get bulk
production as well as to reduce the cost of
production.

3. BACK DROP
• The major challenges a head is, whether
to follow principal stress direction while
driving Gate roads or to plan according to
the shape of property.
• Most of the future Longwall mine panels
need to be laid in Dip Rise Direction, if
Principal stress direction is taken into
consideration.

4. EXPERIENCE
• Though, GDK-10A mine is being worked
Strike & Dip rise Panels successfully, the
gradient of Dip Rise Panels is 1 in 6 to 7.
Where as in the proposed Longwall mines,
Dip Rise Panels are around 1 in 4
gradient.

5. TRUNKS
• Formation & Maintenance of Trunk roadways is
problem in a direction perpendicular to principal
stresses.
• Trunk roadways have to maintain longer periods
and needs high stability.
• Under increased stress condition on gate roads,
needs additional supporting like resin bolting,
cable bolting, roof stitching, arching etc.

6. GATE ROADS
• More stable when laid parallel to principal stress
direction.
• Accumulation of Water in dip galleries, increased head of
pumping in developing gate roads and insufficient
quantity of water for dealing with high head pumps.
• Low Gate road progress per month, i.e., less than 100m
• If twin or multiple entry system for gate road
development adopted in future, drivage is difficult in dip
rise panels.
• Difficulty in Material Transport and handling on increased
gate road gradients.
• Necessitates high capacity haulers /conveyor belts,
including man riding if provided.

7. GATE ROADS
• Movement of free steered vehicles along gate roads is not feasible
on increased gradients.
• Only rail car man riding system for men transport along lengthy gate
roads is applicable. Chair lift system is not possible as frequent
shifting of return pulley while Longwall face under retreat.
• Switch train shifting is tedious and generally for every 100 m,
necessitates mono rail system for handling cables.
• Emulsion supplied to supports could not return to Power pack tank
through ring main system, leading poor quality of water emulsion
mixture and more consumption of emulsion oil.
• Increased Load on relay bars, advancing rams, face sprags of
powered roof supports.
• Ram capacity & plate size for face sprags of powered roof supports
need to be increased.

8. FACE
• Face spalling is more and directly falls between AFC, on
spill plates & walkway
• Requires advancing chocks by adjacent control due to
face spalling while lowering support.
• Leading to uneven wear of pans of AFC and flights
overriding due to increased cross gradient of face.
• Proper cleaning is required for advancing AFC, even
shearer provided with cowl.
• Shearer goaf side track shoe life reduces as more weight
of shearer shifted due to cross gradient factor.
• Wear & tear of rack bars & spacers is high, as above.
• Less load on shearer haulage due to reduced
longitudinal gradient.

9. FACE
• Increased risk to shearer operator &others working
nearby due to face spalling.
• Subsidence is not uniform due to panel varies from
shallow to high depth- possibility of increased breathing
from surface.
• Whenever heating or fire problem arises, could not easily
dealt by method of inertisation and also not possible to
drown the workings with water as an ultimate option.
• For outby transport of coal in gate road need to provide
two or more gate belt drive heads due to increased lift.

10. FACE
• Shearer sump low due to increased cross face gradient.
• Face and gate roads are dry if drainage planned is
towards the goaf.
• Less humid and comfortable ventilation conditions.
• Crushing of barrier pillar is minimized compared to strike
panels.
• In AFC, Gravity component is eliminated for coal
transport.
• AFC motor capacity to be increased as gravity does not
support. (Requires high initial torque).
• No slushy condition at BSL.

11. FACE
• Face strata control problems are less.
• Periodic weighting interval is less
• Cavities formation in face is less due to front abutment
pressure is less and more load is shifted to goaf side.
• Salvaging is safe and easy due to load on PRS is less.
• Face progress is less compared to strike panels.
• Property loss is more because of shape of property
favors strike panels.
• Opined to work one dip rise short length panel in steep
seam on experimental basis.

12. SUMMARY
• As far as possible, strike panels are more
convenient in operational aspect. Gate roads
need to be laid oblique to Principal stress
direction and increasing support density to
counter the strata control problems.
• Wherever strike panels are not feasible
keeping in view of shape of deposit and
principal stress, it is obvious to work dip rise
panels by overcoming the operational
difficulties.

13. CONCLUSION
• It is suggested to work Strike panels,
instead of Dip Rise Panels in view of the
difficulties forecasted in dip rise panels
with 1 in 4 gradient.

14. COMPARISON OF DIP-RISE LONGWALL PANELS WITH STRIKE LONGWALL PANELS
S.No Parameters Dip Rise Panels Strike Panels
1 Drivage of Single or Moderate Difficult ✕ Easy ✔
multiple Gate
roads
2 Gate road progress Less ✕ More ✔
3 Gate road condition Dry ✔ Slushy ✕
4 Material and men Risky ✕ Less Risky ✔
Transport in Gate
roads
5 Laying & Dismantling Difficult ✕ Easy ✔
of gate belts
6 Number of Belts Two or More depends upon ✕ Single ✔
required in Main lift
gate
7 Switch train Shifting Tedious & cables handling ✕ Easy & shifting can be done ✔
is difficult daily
Requires one time shifting
for every 100m or more

15. 8 Water Drainage Requires pumping ✕ Does not require pumping ✔
During Development Good ✔ Not Good ✕
During extraction
9 Ventilation Comfortable due to dry ✔ Less Comfortable due to ✕
condition humid condition
10 Face Spalling More ✕ Less ✔
11 Main Weighting Span Less ✔ More ✕
12 Periodic weighting Similar ✔ Similar ✔
interval
13 Periodic weighting Less ✔ More ✕
intensity
14 Strata Control Problems Less ✔ Moderate ✕
15 Emulsion requirement More ✕ Less ✔
for supports
16 Safety to workmen Less ✕ Moderate ✔
17 Load on Shearer Less ✔ More ✕
haulage
18 Wear & tear of face More ✕ Less ✔
equipment (AFC &
Shearer Parts)
19 Face Equipment Creep Less ✔ More & Difficult ✕
problem & Control

16. 20 Sequence of Cutting Limited to Uni-directional ✕ Uni or Bi-directional ✔
only
21 Sump to each Cut Less ✕ More ✔
22 Production Less ✕ Moderate ✔
23 Coal Transport in AFC Gravity does not support ✕ Gravity supports ✔
24 AFC Motor Starting High ✕ Moderate ✔
Torque Requirement
25 Salvaging & installation Easy ✔ Moderate Difficult ✕
26 Dealing of Heating or Difficult & Unsafe ✕ Moderate Difficult & safe ✔
fire Problem
27 Subsidence over goaf Non-uniform ✕ More or less Uniform ✔
28 Effect of Principal stress More because aligned ✕ Less because aligned parallel ✔
on Trunks perpendicular
29 Effect of Principal stress Less because aligned ✔ More because aligned ✕
on gate roads parallel perpendicular
30 Alternative to lower Trunks need to be aligned ✔ Gate roads need to aligned ✔
effect of Principal stress oblique to stress direction oblique to stress direction
11 1
19 9
1
1