This document discusses the productivity of LHD machines in underground coal mines. It provides background on coal mining in India and describes the types of underground mining technologies used. Side Discharge Loaders (SDL) and Load Haul Dump (LHD) machines are discussed as examples of intermediate mining technology. The document then calculates the productivity of LHD machines in different coal seams and faces based on machine parameters, haul distances, and cycle times measured from observational data. Productivity is found to range from 103-452 tonnes per day depending on the specific mining conditions and face layout. Longer haul distances and steeper gradients are shown to reduce productivity.

2. TITLE
study of the productivity of LHD in underground COAL
mines

3. Coal mining in India has a history of over 225years.
The industry currently occupies a covetable third
ranking in the world league table of hard coal
production after China and the USA. Mechanization
has made possible major breakthroughs in coal
mining technology. The record of production and
productivity of Indian underground coal mines over
the years is dismal, to say the least. At the time of
nationalization (1971) of the coal industry contribution
of national coal production by underground and
opencast mines was 77.5% and 22.5% respectively. By
2000, the share of coal production from underground
mines declined to 21.35%.
Introduction

4. There are three types of underground mining
technologies-
1. Conventional (drilling and blasting,
manual loading)
2. Intermediate Technology (Mechanized
blasting and SDL/LHD)
3. Mass Production Technology
(mechanized PSLW and continuous miner)
The share of coal production by different methods
may be stated thus: bord and pillar (conventional)—
55.98%; mechanized (SDL/LHD)—34.01%; longwall
(conventional)—0.6%; mechanized 7.44% and
othermethods 1.97%.

5. There have been a gradual shift from manual
mining to intermediate mining technology in
the last few decades. Intermediate mining
technology has certain advantages over
manual mining-higher productivity ,
flexibility, high production, mobility and
versatility ,development speed and cost.

6. Side Discharge Loader(SDL) and Load haul
Dump(LHD) machines are underground mining
equipment which is mainly used in Intermediate
mining technology in underground mines.
LHD/SDL machine in which load, haulage,
transportation and dump are integrated is a kind
of trackless equipment used in underground
mines, and featured by big shoveling force, anti-
spillage in transportation, convenient operation,
and mobile turning.

7. A LHD/SDL plays a very important role for the
loading of coal on a chain or belt conveyor. It
has a front-end bucket designed to carry and
dump bulk material. Since an LHD/SDL is
conceived for underground mining, it is
compact and of low profile. It is bi-directional
in operation, with powered steering
controlled by a driver sitting mostly at right
angles to the direction of the vehicle’s
movement.

8. These machineries are usually used in association with
mechanized drilling and blasting (solid blasting).
In conventional bord and pillar workings coal loading
and transport have been mechanized, eliminating the
human labor and drudgery to a large extent. The use of
such equipment for underground operations required
elimination of conventional roof support or other type
of roof to roof type of support to allow movement of
machines in confined space.

9. Factors governing selection & deployment of
LHD
The material characteristics, the job conditions, roof
supports, ventilation ,inclination and height of seam,
nature of floor, type of transportation ,amount of
blasted coal available and the required production will
determine the selection and deployment of LHD . The
information presented at the end of the selection
procedure should permit an initial choice of
equipment. The compilation includes many job
conditions from underground operations. The initial
choice must then be followed by an estimate of its
operating and ownership costs.

10. A comparison of this cost with the estimated
costs of other types of mechanism should
result in a selection giving the lowest cost and
meeting the overall job requirements.

11. Applicability
1.LHD is a wheel mounted machine ,so the condition of
the floor should be good.
2.The limiting gradient for LHD is 1 in 7.
3.The height of working for LHD ≥ 2.5m
4.The maximum gradient for SDL should be 1 in 5
5.The general height of working for SDL is 2.3m and in
case of low profile SDL it is 1.5m.
6.In watery floor condition the tire mounted LHD skids,
so crawler mounted SDL is preferred.
7.Normally the production of SDL is 105-111te/day
whereas in case of LHD it is 195-205te/day.
(A=78%,U=50%)
8.The travelling distance should be less for both the
machines(normally 40-50m).

12. Calculation of SDL and LHD productivity
Machine parameters
 Bucket capacity in m3
 Fill factor,
 Swell factor
 Cycle time, which is the sum of:
 Loading
 Hauling
 Dumping and
 Return time of machine.
 Hauling distance
 Density of coal

13. KHOTTADIH COLLIERY, ECL
SEAM NO. R-VI
PIT NO. 1 face no.1
Trip No. Dump Time
(in secs)
Empty haul time
(in secs)
Loading Time
(in secs )
Loading haul time
(in secs)
Idle Time
1. 12 2x60=120 6 3x60=180
2. 15 2x60=120 10 3x160=180
3. 15 2x60=120 10 3x60=180
4. 15 2x60=120 7 3x60=180
5. 13 2x60=120 8 3x60=180
6. 13 2x60=120 6 3x60=180
7. 15 2x60=120 7 3x60=180

14. Face dimension: 4.1x4.8
LHD make: EIMCO
No. of holes: 16
Bucket Capacity: 1 m3
Drilling pattern: wedge
Drilling time: 20-30 min
Explosive loading time: 30-35 min.
Blasting time: 5 min
Fume clearance time: 5 min
Dressing: 10 min
Haul distance: 25+12.5= 37.5m

15. KHOTTADIH COLLIERY, ECL SEAM NO. R-VI
PIT NO. 1
LEVEL: 49/2
FACE NO. 2
Trip No. Dump Time
(in secs)
Empty haul time (in
secs)
Loading Time
(in secs)
Loading haul time (in
secs)
Idle Time
1. 25 5x60=300 7 7x60=420
2. 24 5x60=300 9 7x160=420
3. 25 5x60=300 10 7x60=420
4. 23 5x60=300 7 7x60=420
5. 25 5x60=300 8 7x60=420

16. .
Face dimension: 4.1x4.8
Travel time (Pit top to working face):45 min.
No. of holes: 16
Maintenance hour is in general shift: 8am-12pm
Drilling pattern: wedge
Bucket Capacity: 1.2m3
Drilling time: 20-30 min
LHD make: EIMCO
Explosive loading time: 30-35 min.
Blasting time: 5 min
Fume clearance time: 5 min
Dressing: 10 min
Haul distance: 25x3=75 m.

17. KHOTTADIH COLLIERY ECL
SEAM: R III/II PIT NO.2
LEVEL: 46E LEVEL
FACE NO. 1
Trip No. Dump Time (in
secs)
Empty haul time (in
secs)
Loading Time (in
secs)
Loading haul time
(in secs)
Idle Time
1. 30 2x60=120 10 3x60=180
2. 32 2x60=120 13 3x160=180
3. 33 2x60=120 10 3x60=180
4. 35 2x60=120 14 3x60=180
5. 35 2x60=120 15 3x60=180
6. 35 2x60=120 14 3x60=180
7. 35 2x60=120 15 3x60=180

18. Face dimension: 3x4.8
Travel time (Pit top to working face):45 min.
No. of holes: 16
Maintenance hour is in general shift: 8am-12pm
Drilling pattern: wedge
Bucket capacity=3 m3
Drilling time: 20-30 min
density: 1.4te/m3
Explosive loading time: 30-35 min.
Pull: 1 m
Blasting time: 5 min
LHD make: EIMCO
Fume clearance time: 5 min
LHD No. 145
Dressing: 10 min
Haul distance: 45x3=135 m.

19. KHOTTADIH COLLIERY , ECL
SEAM: R III/II PIT NO.2
LEVEL: 46E LEVEL
FACE NO. 2
Trip No. Dump Time (in secs) Empty haul time (in
secs)
Loading Time (in
secs)
Loaded haul time
(in secs)
Idle Time
1. 30 60 10 2x60=180
2. 32 60 13 2x60=120
3. 33 60 10 2x60=120
4. 35 60 14 2x60=120
5. 35 60 15 2x60=120
6. 35 60 14 2x60=120
7. 35 60 15 2x60=120

20. Face dimension: 3x4.8
Travel time (Pit top to working face):45 min.
No. of holes: 16
Maintenance hour is in general shift: 8am-12pm
Drilling pattern: wedge
Bucket capacity=3 m3
Drilling time: 20-30 min
Density: 1.4te/m3
Explosive loading time: 30-35 min.
Pull: 1m
Blasting time: 5 min
LHD make: EIMCO
Fume clearance time: 5 min
LHD No. 144
Dressing: 10 min
Haul distance=45m.

22. A.
FOR R-VI SEAM (FACE NO. 1)
IN LEVEL GALLERY, HAUL
DISTANCE =37.5MTRS.

23. Total numbers of trips observed -7.
Trip time=dump time+empty haul time+loading
time+lauded haul time
Trip 1= (12+120+6+180) secs=318secs=5.30min
Trip 2= (15+120+10+180) secs=325secs=5.42min
Trip 3= (15+120+10+180) secs=325secs=5.42min
Trip 4= (15+120+7+180) secs=322secs=5.37min
Trip 5= (13+120+8+180) secs=321secs=5.35min
Trip 6= (13+120+6+180) secs=319secs=5.32min
Trip 7= (15+120+7+180) secs=322secs=5.37min
Avg. trip time= (5.30+5.42+5.42+5.37+5.35+5.32+5.37)
mins / 7=5.36min

24. Total trips made by machine in an hour =60/5.36=11.194=11
Production Capacity of the machine /hr. =bucket size X fill factor X
Swell factor X total trips
=1 X .80 X .702 X 11
=6.1776 m3=6.178m3
Production in tonnage /hr. =solid bucket size (m3) X density of
Coal
= 6.178 X 1.4=8.649 te
Utilization (as per CIL guidelines) =50%
Therefore production of the machine per day in tonnage, TPD
=8.649 te X 12
=103.788
Note
CIL guidelines for availability & utilization of LHDs in where LHDs load on
conveyors
•Availability percentage is to be maintained about 78%.
•If the machine utilization is maintained at about 50% and idle hours maintained
at about 28% in relation to total available hours then the productivity of LHDs
loading into the conveyors can be ensured between 195-205 TPD.

25. B.
FOR R-VI SEAM (FACE
NO. 2) IN DIP-RISE
GALLERY, HAUL

26. Total numbers of trips observed -5.
Trip time=dump time+empty haul time+loading
time+lauded haul time
Trip 1 = (25+300+7+420) secs =752 secs=12.53
min
Trip 2= (24+300+9+420) secs =753 secs=12.55
min
Trip 3 = (25+300+10+420) secs=755 secs=12.58
min
Trip 4 = (23+300+7+420) secs=750 secs=12.50
min
Trip 5= (25+300+8+420)secs = 753 secs = 12.55

27. Total numbers of trips made by the machine in an hour=60/12.542
=4.783
=5
Production Capacity of the machine per hour =1.2 X .80 X .702 X 5
=3.3696 m3
Production in tonnage /hr. =3.3696 X 1.4
=4.71744 te
Utilization (as per CIL guidelines) =50%
Therefore production of the machine per day in tonnage, TPD
=4.71744 te X 12
=56.60928
Low production due to higher cycle time
Influenced by-
•Lower speed (dip rise gallery)
•Longer haul distance
•Watery conditions
•New operator

28. C.
FOR R III/II SEAM, FACE
NO.1 IN LEVEL GALLERY,
HAUL DISTANCE =45
MTR.

29. •Total numbers of trips observed -7.
Trip time=dump time+empty haul time+loading
time+lauded haul time
Trip 1 = (30+60+10+120) secs=220 secs=3.67
min
Trip 2 = (32+60+13+120) secs=225 secs=3.75
min
Trip 3 = (33+60+10+120)secs=223 secs=3.72
min
Trip 4 = (35+60+14+120) secs=229secs=3.82
min
Trip 5 = (35+60+15+120) secs=230

30. Total numbers of trips made by the machine in an hour=60/3.78
=15.873
=16
Production capacity of the machine per hour=3 X .80 X .702 X 16
=26.9568m3
Production in tonnage/hr. =26.9568m3X 1.4te/m3
=37.73952 te
Utilization (as per CIL guidelines) =50%
Therefore production of the machine per day in tonnage, TPD
=37.73952 te X 12
=452.87424
Larger production due to
1.Shorter haul distance
2.Larger bucket size (3m3 )

31. D.
FOR R III/II SEAM, FACE
NO.2 IN LEVEL
GALLERY, HAUL
DISTANCE =135 MTRS.

32. •Total numbers of trips observed -7.
Trip 1= (30+120+10+180) =340secs= 5.67 min
Trip 2= (32+120+13+180) =345 secs=5.75min
Trip 3= (33+120+10+180) =343 secs=5.72 min
Trip 4= (35+120+14+180) =349 secs=5.82 min
Trip 5 = (35+120+15+180) =350 secs=5.83 min
Trip 6= (35+120+14+180) = 349 secs=5.82 min
Trip 7 = (35+120+15+180) = 350 secs = 5.83 min
Avg . trip timing of the machine
=(5.67+5.75+5.72+5.82+5.83+5.82+5.83) min/7
=40.44/7
=5.78min

33. Total numbers of trips made by the machine
=60/5.78=10.380=10
Production capacity of the machine per hour =
3X.80X.702X10
=
16.85m3
Production in tonnage /hr. = 16.85m3 X 1.4 Te/m3
=23.59 te
Utilization (as per CIL guidelines) =50%
Therefore production of the machine per day in
tonnage, TPD
=23.59 te X 12
=283.05

34. Analysis and Evaluation Of
Research/Investigation Results

35. Seam Lhd type
with
bucket
capacity
Lev
el
galle
ry
Dip
rise
galle
ry
Haul
distance
(mtr)
TPD Avg.
speed
of
machi
ne
(empt
y
haul)
in
KMP
H
Avg.
speed
of
machi
ne
(loade
d
haul)
in
KMP
H
R –VI
(face
No.1)
Eimco
557(1
m3)
√
37.5 103.788 1.125 0.75
R-VI
(face
No. 2)
Eimco
558(1.2
m3)
√
25x3=75 56.609 0.9 0.64
R-III/II
(face
no.1)
Eimco
144(3m3
)
√
45
452.874
2.7 1.35

36. Performance of the mine for the year (april,2011-
feb,2012)
Total production =2,93,653 te
Actual Avg. tpd of the 4 LHDs under observation
=615.45
Calculated avg. tpd of the 4 lhds (1 hr)=896.321

37. Conclusion

38. Capacity of the machine is greatly influenced
by-
•Haul distance.
•Gradient of the road and floor
conditions.(speed of the LHD)
•Efficiency of coal preparation at the working
face
•Transport system (conveyors/mine tubs)
Actual production and calculated production
is varied due to limited time observation of the
machine operation.