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Working of dragline
1. WORKING OF DRAGLINE
I. Satyanarayana,
M.Tech,MBA,MCA
Dy. Manager, Project Planning, SCCL,
isnindian@gmail.com,
visit at
www.slideshare.net/isnindian
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3. DRAGLINE
• Walking draglines are for many years the most
popular machine for opencast mining due to their
flexibility, utility and availability.
• their low operating costs for waste mining
• Draglines are deployed wherever there is scope for
side casting Overburden above coal seam into the
de-coaled area.
• It is very cost effective technology- cost of OB
removal is cheaper than shovel dumper technology.
• There are two draglines working at RGOC-I and RG
OC-III with bucket size of 24 Cum and 30.6 Cum
respectively.
• Both these draglines are performing very well.
• The bucket is maneuvered by means of a number of
ropes and chains.
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4. DRAGLINE
The dragline is a typical combined cyclic excavator and
material carrier since it both excavates material and
dumps it without the use of trucks or conveyor
belts. The dragline sits above the waste or
overburden block, usually 50m or so wide, on the
highwall side and excavates the material in front of
itself, to dump it on the low-wall or spoil side of the
strip to uncover the coal seam below it.
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5. OPERATION OF DRAGLINE
In a typical cycle of excavation, the bucket is positioned
above the material to be excavated.
The bucket is then lowered and the dragrope is then drawn so
that the bucket is dragged along the surface of the material.
The bucket is then lifted by using the hoist rope.
A swing operation is then performed to move the bucket to
the place where the material is to be dumped.
The dragrope is then released causing the bucket to tilt and
empty. This is called a dump operation.
It is a independent machine unlike a shovel.
A 30 cum Dragline can handle 40 Lakh cum of OB per annum.
The dragline works on the immediate OB bench above coal
and the benches from the surface to the Dragline are normally
handled by Shovel & Dumper combination. Hence adequate
capacity of Shovel & Dumper ISN capacity should be provided to
prevent idling of the Dragline.
6. OPERATION OF DRAGLINE
The Dragline has a long boom with a bucket capacity ranging
from 15 to 50 cum.
It can swing in 360 degrees, after dragging the loose material
below its level.
It swings normally between 90 to 120 degrees and side cast
the material in to the de-coaled area.
The nomenclature of the Dragline usually called as 24/99
which means 24 cum of bucket capacity and 96 m is the boom
length.
The same Dragline can have about 32 cum of bucket capacity
if the boom length of 71 m. normally
the Draglines is electrically driven with 6.6 KV power with 2
main motors of 1750 HP each. These motors inturn drive the
Generators and the Generators drive DC motors
Normally there are 7 DC motors for different operations like
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marching, dragging, hoisting, swinging etc.,
10. APPLICATION OF DRAGLINE
1. Gradients flatter than 1 in 6 (if gradient is more the
dumped OB will slide towards the coal face and
particularly in rainy season the extraction of coal
become dangerous)
2. Seams should be free of faults & other geological
disturbances
3. Deposits with Larger Strike length (>2 km) so that
frequent shifting of the Dragline from one end to
another can be reduced.
4. Present cost of the Dragline is above 100 Cr and the
life of the Dragline is 1.50 Lakh hours hence, the
property should be large enough ensuring the life of
about 25 yr or more.
5. A hilly property is not suitable
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6. Property should have atleast 15 years life
11. DRAGLINE – Methods of Working
– Simple casing method with or without
rehandling.
– Extended bench method.
– Horse shoe /Spoil Bank/Across Pit
method.
– Continuous bench two pass method.
– Tandem dragline working i.e., two
draglines working together, one dealing
with part of the material dumped by the
other.
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12. Simple Casting
This is simple method of Dragline working. In this method the Dragline is sited
on immediate OB bench above Coal and removes the OB and dumps it in the
de-coaled area of previous cut.
The width of the cut normally less than 40 m so that re-handling of the OB will
be negligible. The method is extremely suitable for singly thin seam mining.
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22. Extended Bench Method
• As the name is suggested, the Dragline bench is
extended by dumping a part of OB by dragline into de-
coal area and the space is levelled by dozing and the
same Dragline can be sited in 2nd position on the
dumped and dozzed OB.
• This enables the distance between 1st and 2nd position to
be more when compared with simple casting method.
• The increasing distance increases the capability of the
Dragline to dump OB further away in de-coaled area, so
that sliding of OB on to the coal bench is to be minimized.
• A Dragline has to do more re handling now. This method
is suitable for exposing relatively thicker seams.
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29. Spoil Bank Method
• The method is adapted when there are 2 seams
and having parting between 10 to 12 m.
• In the first position, the Dragline exposes the top
seam by side casting the OB above the top
seam.
• The side casting material is dozed and leveled.
• After extraction of the top seam the parting OB is
loosened by blasting and the Dragline is placed
on the already side casted leveled material and
the remaining parting OB of above bottom seam
is removed by the dragline and side casted
exposing the bottom seam.
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34. Tandem Working of Draglines
• In this method 2 Draglines are put into in
tandem operation one above the other
with a minimum horizontal distance of 100
m between them. This method is adopted
where the coal seam thickness is more
than 30 m and to handle the OB bench of
60 m above the coal seam.
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35. Tandem Working of Draglines
Dragline Cut Dump Area m2
(solid) D/L 10/70 is
10/70 ABCD abcd 285.0
150-200m ahead of
20/90 CDEF kmnofci 570.0
(Dig)
D/L 20/90
Ijkl (R.H.) 9.6
Ebf (R.H.) ISN 1.0
36. Variables with Draglines
•Swing and boom angle of a dragline.
•Increase or decrease of bucket size (within
limits) with consequent decrease or increase of
boom length.
•Cut width and height of dragline bench.
•Method of use of dragline/draglines.
•More than one position of a dragline.
•Adopting cast-blasting to the desired extent.
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37. Technical specifications of Dragline
(24 x 96)
- Boom length : 74 - 95 m
- Boom angle : 30°- 38°
- Bucket Capacity (nominal): 26 - 34 cu m
- Dump height : 38 - 40 m
- Digging depth : 44.3 - 53.4 m
- Operating radius : 64.6 - 88.2 m
- Walking speed : 0.24 kmph
- Bearing Pressure : 0.95 kg/cm2
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38. SPECIFICATIONS OF OC-I DRAGLINE
MAKE Ranson & Rapier
Bucket Capacity M3 24
Annual capacity mm3 3.31
Boom Length Mtrs 95.6
Operating Radius Mtrs 88
Dumping Height Mtrs 39.6
Base Dia Mtrs 16
Shoe Length Mtrs 17
Shoe Width Mtrs 2.8
Movement of Machine Mtrs 2.2
Weight of Machine Tonnes 2000
Total H.P H.P. 3500
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