fThis paper was presented in MGMI Kothagudem chapter. This maily deals with various options for mechanisation od underground mines and their merits and demerits. The various advantages of Longwall technology and its supremacy in the different geo-mining conditions.

1. 1.5 Mtpa Longwall faces in
Shanthikhani and KK-7.
G.Rajendar Reddy GM, Proj.Plng
MD. Suresh Kumar Add.Mgr,
Proj.Plng

2. MMR shaft block KK-7 LW Project
D
B C
E
A
Geo-Reserves 101.57 MT
Mine Take Area: 857.91 Ha
Rated Capacity 1.5MT
Forest 60.51
Grade F, E, C
No-Forest 797.4
BH Density 13/sq.km
Seams 7
Seams workable 3 (IA, I,III)
Gradient 1 in 3.5 to 5
Depth 92 to 606 m

3. Shanthikhani shaft block SK LW Project
Mine Take Area 1184.3 Ha Geo-Reserves 45.496 MT
Forest Land 648.11 Ha Ext. Reserves 26.22
Non-Forest Land 536.18 Ha Rated Capacity 1.5MT
BH Density 13.5 /sq.km Depth 244-662m
Seams avble 7 seams
Seams workable 1 (SJ Top&Bot)
Rated Capacity 1.5MT
Grade D Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
Roof underground Strata Control- Planning issues

4. Working under Sst roof Past Experience
LW failures under hard roof in India
• LW collapsed at Balrampur, Kumda, Churcha, Kottadi and Gdk9inc, 11A.
• Major roof collapse in VK-7 during salvage under Sst roof.
• P-21 worked under Sst roof in PVK.
Preparedness for working under Sst in PVK
• Supports Refurbishment: Around new 200 legs (50% of
total legs), all control valve blocks, all bleed valves, all
line distribution blocks, all connectors, hoses, filters,
advancing rams, rams of extension canopies were
replaced with indigenous and imported spares.
• New 3rd power pack pump.
• Ring-main circuit.
• Multi Point Borehole Extensometers (MPBEx) - 2 Nos.
• The additional boreholes at 30 and 60m were logged too. 21
P-
• The physic-mechanical properties of older/newer
boreholes compared and studied in-detail.
• Calculation of layer wise cavability index.
• Numerical modeling were done with the help of CIMFR.
• Around 500 blast holes were drilled & blasted.
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

5. Working under Sst roof Past Experience
Actual Situation… 0 10 20 30 40
Support #
50 60 70 80 90 100
120 0
• Excessive abutment pressure &
loading on Power supports. 100
-5
• Floor heaving-AFC got lifted up,
Hydraulic run of Legs (cm s)
Supports dislodged in gates 80
Hanging Goaf (m )
-10
• Change of roof RL within the face:
60
Frequent change of section- AFC
-15
damage. 40 Front 24/9
• Stone intrusion: had to cut by Rear 24/9
Front 25/9
shearer--Damage to picks, drums, 20 Rear 25/9
-20
gear box, abrasion of AFC Hanging 24/9
Hanging25/9
fleights, chains. 0 -25
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

6. Working under Sst roof Past Experience
Coal roof Vs Stone roof
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

7. Selection of seam and sequence of Operation
Seams of MMR shaft Block Seams of SK shaft Block
4.5m
2.5m 3.7m
1.7m
2.0m
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

8. Selection of seams and Sequence of Oprn.
LW workability options
KK-7 SK
•Projected Reserves in IA : 33.9 MT (upto750m). •Projected Reserves in SJ Bot: 34.3MT (Upto750m).
•No of Cycles =34000 •No of cycles = 34000
LW Unit-1 with 30000 cycles LW Unit-2 with 30000 cycles
Thin seams (2.5m)
•Projected Reserves in III seam of KK-7 : 8.5 MT (Upto 750m). No of Cycles = 14775
•Projected Reserves in I seam of KK-7 : 6.8 MT (Upto 750m) No of Cycles = 16144
•Projected Reserves in SJ (Top)seam of SK : 9.7 MT (Upto 750m). No of Cycles = 9760
LW Unit-3 with 30000 cycles (1.7 to 2.5 Ht Control- Planning issues
Workshop on Strata
of Extn)

9. Selection of Working section Development
Trunks
Gate Roads
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

10. Selection of Working section Extraction
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

11. Panel Layouts Dip-Rise Panels
Why Dip-Rise panel in KK-7 ??
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

12. Panel Layouts Dip-Rise Panels
Advantages
1. Face gradient is 1 in 6. Gate roads gradient is 1 in 6.
2. The position of abutment load and tensile load gets shifted from
supports towards goaf.
3. The intensity of abutment load reduced drastically and the caving is
very smooth.
4. No abnormal roof convergence and floor heaving are experienced
& expected.
5. Gate road supports are intact.
6. No water problem along bottom gate road ways.
a. Min 10 persons/ day/ km gate belt-be avoided.
b. Min 4 weak joints/week-avoided
c. Reduction in Belt life.
d. Advancing of gate end supports, BSL, Gate belt tail end unit becomes
easier.
e. BSL and gate belt is free of water.
f. No rusting & pitting problems of BSL bottom plates, fleights and chain.
g. Quality of coal is maintained.
Limitations
1. Men transport upto face and Advancing of switch train.
2. Shear failure of face results in falling of boulders onto
AFC and injuring persons working at face.
3. Reduction of shearer thrust for cutting the coal in
raising direction. Roof Bolting Practice in underground mines-needs ‘ Review & Policy’

13. Panel Layouts Strike panels
Problems to be focused..
• Face gradient is 1 in 3.8 to 1 in 4.5. Gate road gradient is 1 in 50.
• Power requirement of Shearer:
• For cutting the face At 1 in 3.8 gradient is around 900KW for 3.6m/4m Ht of Extrn.
• For haulage of shearer at 1 in 3.8 gradient is around 70 KW.
• Contours swing for about 500m in few panels towards North.
• Straight gate: Gates dipping at 1 in 50, RL difference 10m, Water should be
pumped out.
• Deviation in Gate (90) : Face has to negotiate deviation with strata problems, time
loss.
• Possible Roof damage to bottom Gate of Twin gates due to LW retreat.
• Maintaining such gates for 1-1.5 years including Pumping, Ventilation, inspection etc.,
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

14. Selection of Equipment Power Roof Supports
Support resistance
1. Convergence method
2. Bending stress/Moment/
Beam method
• Ht of caving is 10T.
• Weighted avg of Ts is considered.
• Cavability index calculated layer-wise.
• Caving beds are assumed as cantilever beams.
• Bending stress/moment of Beams calculated
and equated.
• Main Fall is expected at : 65m
• Periodic Fall span : 15.85m
• Required Support Density : 129.7 t/m2 (Main weight) 64.7 t/m2 (Periodic Weighting)
• Load on Support : 915.4 T (Main weighting) 641.4 (Periodic Weighting)
• The recommended Support Capacity is 1000-1100T with support Resistance of 110-120T/m2
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

15. Selection of Equipment Power Roof Supports
Structural Features
• 2 Legged Shield
• Base width : 1.7 or 1.8m
• Advancing Ram : atleast 60T capacity.
• Face frogs
• Anti skid + Anti topple
• Base lifting rams.
• Support Resistance : 110-120T/m2
• Support capacity : 1000-1100T
Base
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

16. Coal Evacuation system Belts Vs Skip
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

17. Coal Evacuation system Belts Vs Skip
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

18. Men & material Transport Haulers Vs Monorail
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

19. Men & material Transport Haulers Vs Monorail
Roof Bolting Practice in Workshop on mines-needs ‘ Review & Policy’
underground Strata Control- Planning issues

20. Conclusion

21. Thank You Sir..