rock excavation, different open cast or open pit excavation machinery, application, limitations, highwall miner, bucket wheel excavatorr, bucket chain excavator, shovels

1. ROCK EXCAVATION MACHINES -
SURFACE MINING
U.Siva Sankar
Sr. Under Manager
Project Planning
Singareni Collieries Company Ltd
E-Mail :ulimella@gmail.com or
uss_7@yahoo.com
Visit at:
www.slideshare.net/sankarsulimella
SURFACE MINE EXCAVATION
1

2. Typical open cast mine
SELECTION CRETERIA FOR OC EQPT.
Selection of HEMM for OC Mines depends upon several factors
• Extent of deposit i.e., the strike and dip rise widths.
• Coal reserves and OB volumes and annual production
capacity required.
• Geological disturbances.
• Inter seam partings.
• Gradient of deposits.
• Number and thickness of the seams.
• Hardness of the coal and overburden strata.
• Location of deposit with respective surface structure,
forest land etc.
2

3. SELECTION CRETERIA FOR OC EQPT.
Shovel dumper combination:
• This is the most commonly used equipment in
Opencast mines.
• Basically two variants – Rope shovels and Hydraulic
shovels.
• Electric and diesel driven equipments are available.
• Bucket capacities vary from 0.9 Cum to 40 Cum.
• Selection depends on the parting – wise volumes to
be removed.
SELECTION CRETERIA FOR OC EQPT.
Hydraulic shovels:
• Versatile – easy to march from place to place.
• Productivity is higher than rope shovels.
• Can march on steep gradient.
• Can be deployed for removal wedge portions in the
last OB bench (Over coal seams).
• Can be used for preparation sumps and drains.
• Can load on dumper placed at the same level as that
of the shovel or on a dumper placed below the shovel
level.
• Can be used for removal of soft coal/ strata without
blasting.
• Can be deployed for removal of thin seams.
• The life of shovel is around 9 to 12 years only and
requires a mid-life overhaul.
• Initial capital is low compared to Rope shovels.
3

4. SELECTION CRETERIA FOR OC EQPT.
Rope shovels:
• Life is large compared to Hydraulic shovels (20 to 25
years).
• Initial capital is high compared to Hydraulic shovels.
• Can work only on mild gradient of around 1 in 10.
• Can be deployed where less margins are required.
Stripping shovel – Equipped with an especially long
boom and stick enabling the shovel to reach farther and
pile higher.
POWER SHOVEL
4

5. HYDRAULIC SHOVEL –
Backhoe or Pull Shovel
Backhoe-pull shovel – A shovel with a boom-and stick- mounted bucket that digs
toward itself.
Hydraulic Shovel- Front End Loader
5

6. Hydraulic Shovel & Dumper
Rope Shovel & Dumper
6

7. Rope Shovel & Dumper
Rope Shovel & Dumper
7

8. Fig: Shovel Dipper
or Bucket
Draglines:
• 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.
• There are two draglines working at RGOC-I and RG OC-III with
bucket size of 24 Cum and 30.6 Cum respectively.
• A dragline bucket system consists of a large bucket which is
suspended from a boom with wire ropes.
• The bucket is maneuvered by means of a number of ropes and
chains.
• Normally, the dragline can be considered for large deposits in
view of its longer life.
• Dragline can be planned in mines where coal seams gradient of
1 in 6 or flatter.
• Buckets capacities of 4 to 32 cum are in use at CIL Mines.
8

9. DRAGLINE
Dragline – Revolving shovel that carries a
bucket attached only by cables and digs by
pulling the bucket toward itself.
DRAGLINE BUCKET
9

10. LINE DIAGRAM OF DRAGLINE
SELECTION CRETERIA FOR OC EQPT.
Rock breaker technology:
• Presently rock breaker technology is used in certain
cements quarries.
• Rock breaker technology can be applied for breaking
of rock/coal/ore even more than 500 kg/sq.cm.
• It can be used wherever it is not possible to go for
blasting – near vicinity of structures and habitations.
• However the noise pollution is more compared to
shovels – but within DGMS permitted levels.
10

11. SELECTION CRETERIA FOR OC EQPT.
Ripper Technology:
• Dozers fitted with rippers are being used for ripping
of thin seams. Ripped coal will be lifted by front end
loaders or excavator.
• High capacity ripper dozers can also be used for
ripping of the deposit where blasting could not be
done due to vicinity of structures.
11

12. DOZER
A bulldozer is a crawler (Continuous tracked tractor) equipped with a substantial
metal plate (known as a blade) used to push large quantities of soil, sand, rubble,
etc.,
12

13. DOZER
OPERATION OF DOZER
It is the vital equipment in Open cast mining.
tractor with a pusher blade attached to the front portion.
Diesel operated with crawler chain (some times tyre mounted
Dozers also used)
the pusher blade can be raised lowered or tilted through small
angles horizontally by rams operated by hydraulic pressure.
The Dozer blade is used for pushing loose material, digging earth,
soft weathered rock, for pushing scrapers, for levelling / grading
and compacting the ground, for laying haul roads, for toeing
dumpers etc., for pushing boulders trees etc.,
There is different capacity of Dozers ranging from 100HP to 800
HP and normally used are 400 HP, which costs app. 1.2 Cr.
13

14. The bulldozer blade is a heavy metal plate on the front of the
tractor, used to push objects, and shoving sand, soil and
debris.
Dozer blades usually come in three varieties:
A Straight Blade ("S-Blade") which is short and has no lateral
curve, no side wings, and can be used for fine grading.
A Universal Blade ("U-Blade") which is tall and very curved,
and has large side wings to carry more material.
A "S-U" combination blade which is shorter, has less curvature,
and smaller side wings. This blade is typically used for pushing
piles of large rocks, such as at a quarry.
14

15. WHEEL DOZER
1968 Caterpillar 824 Wheel Dozer
WHEEL DOZER
tractors outfitted with dozer blades or push blocks.
used as push tractors in scraper applications.
Though these machines can be converted from wheel loaders by
replacing the loader’s bucket with a dozer blade, this configuration
is only successful for light-duty tasks.
Used for clearing and grading land, wheel dozers are frequently
used in mining applications and reclamation jobs.
The wheel dozers’ advantage over crawler dozers is their ability to
move quickly.
Additionally, they can travel between multiple job sites without
damaging paved roads.
15

16. RIPPER DOZER
The ripper is the long claw-like device on the back of the bulldozer. Rippers can
come as a single (single shank/giant ripper) or in groups of two or more (multi
shank rippers). Usually, a single shank is preferred for heavy ripping. The ripper
shank is fitted with a replaceable tungsten steel alloy tip.
RIPPER DOZER
16

17. RIPPER DOZER
RIPPER DOZER
tractors outfitted with dozer blades or push blocks.
A Dozer equipped with fork like attachment is known as “Ripper”
can be mounted either with one or two rippers
operates like a plough to loosen moderately hard rock
can be also used to extract thin seams where the thickness is
less than 1.2 m where blasting is not effectively done.
It rippes the thin seams and later can be loaded by the Shovel &
Dumper combination.
There are other crane attachments for the Dozer which is known
as pipe layer for transporting pumps, pipes and laying pipes.
17

18. Fig: (a) Radial ripper, (b) Parallelogram ripper, (c) Adjustable
Parallelogram ripper
Rippability is determined by:
• Compressive strength
• Bedding planes, joints and fractures;
• Brittleness;
• Softness (from weathering).
18

19. SELECTION CRETERIA FOR OC EQPT.
Surface Miner Technology:
• Presently being used in KOCP-I for selective mining.
• Can work safely on a gradient of 1 in 10. However, presently
being worked in KOCP-1 in gradient of 1 in 4.
• Annual productivity of the model 2000 SM is around 2.00 MT per
annum however high capacity of surface miner are also
available.
• Larger strike length of about 600 m – 1000 m and widths of
around 300 m are ideally suited for surface miner.
• Does not need drilling and blasting.
• Can crush coal up to -100 mm.
• Cutting size can be varied by selection of equipment, speed etc.
• Two methods of coal removal are available – Wind rowing i.e.,
loading the crushed coal by front and loader on to trucks and
dispatch of the cut material by gathering arms on to a belt
conveyor and thence to a waiting trucks.
• At KOCP-I, Grade improved from F to E by this technology.
Surface Miner
Surface Miner is :
- continuously operating mobile opencast machine
- it cuts consolidated soils and semi – solid rocks
without drilling and blasting
- the cut material is pre-crushed and suitable for belt
conveying, loading, transporting and transferred to
down stream means of transportation
19

20. Operation:
Surface Miner operates:
- according to the “Rock cutting technology”
- the cutting drum is provided with point attack picks
- which cut the mining face during the continuous
advance of the machine on crawler track assemblies.
Types of Surface
Miner
Machine with front
Boom
20

21. Types of Surface
Miner
21

22. Fig: Capacity of KSM in relation to compressive strength and tensile strength
Of these three types of machines the machines with middle
drum configuration ( the SM type machines from Wirtgen ) find
the widest range of applications specially in small scale
operations below 1000 t/h required output.
The KSM type machine from Krupp Fördertechnik is three times
bigger than the largest SM type machine and specially designed
for large scale operations in overburden and coal.
22

23. A modern surface miner –
here's how it works
VIDEO
Wirtgen SM 2100 SCHEMATIC DIAGRAM
23

24. Technical highlight:
Clever design with central cutting drum
24

25. 25

26. Working principle of Surface Miner:
the surface miner is crawler-mounted machine having a
cutting drum located b/w two sets of crawlers and
positioned at the center of the machine.
the drum is lowered and raised by hydraulic system with
powerful hydraulic motors therby varying the depth of cut.
the material cut is loaded onto the primary and secondary
discharge conveyors for loading the same onto the loading
/transporting equipment.
the rear crawler travel at lower level then the front crawlers
to adjust to the required depth.
26

27. Fig: Extraction with Surface Miner
Surface miner may be operated in three modes
Front or rear loading to dumper or truck
Sidecasting
Windrowing
27

28. ADVANTAGES OF SURFACE MINER
Improvement of quality by selective mining of coal
Eco-Friendly mining of coal
Improved coal recovery especially in areas sensitive
to blasting
Less coal loss and dilution
Primary crushing and fragmentation of coal
WORKING PRINCIPLE OF SURFACE MINER
(SM 2100 / 2200)
The surface miner features a drum shaped cutting or
milling head fitted with a number of tungsten carbide
tipped replaceable picks extending across the full width
of the machine in the form of a helix which facilitates
propelling of the cut materials towards the center of the
machine.
The cutting drum is located between the two sets of the
crawlers and is centrally positioned making the machine
compact.
The milling drum is mechanically driven by the direct
drive system through transmission V-belts directly via a
mechanical clutch on the flywheel side of the diesel
engine.
28

29. The milling drum holds cutting tool holders welded on the
drum body and cutting tools are fixed on to these holders
by circlip.
The milling drum 0perates in Up-milling direction and
cuts the material slice-by-slice on the floor of the bench.
The cut materials are picked up by a tool and flight
system centrally on the primary conveyer belt which
during transportation further reduces the size of the
material.
The primary conveyor further transports the material to the
secondary conveyer, which in turn loads the material finally onto
the truck or side casted in the mine.
The cutting drum is followed by a scraper blade which gathers any
material left on the floor.
This ensures a clean and smooth floor without any Undulations.
Dust suppression is ensured by means of water spray arranged on
the cutting drum, which also serves the dual purpose of cooling of
picks, thus prolonging their useful life.
The surface miner has two sets of crawlers, each individual crawler
unit in front set has its own steering cylinder facilitating
negotiation on the sharp turns.
29

30. Each crawler unit and the cutting head can be raised or lowered by
means of hydraulic cylinders provided for the purpose.
The surface miner is equipped with an air- conditioned operator's
cabin, which has all machine controls within comfortable reach of
the operator.
The depth is adjusted through electronically controlled depth
regulator located at the side of the machine which is operated by
the co-operator at the floor of the machine.
The surface miner is also equipped with flood light for night
operation
Machine Operation
The machine is operated by an operator in side the cabin. and a co-
operator on ground level who is responsible for smooth operation
and control of the machine.
The operator In the cabin controls the speed, position of the belt
conveyor for proper loading into the tippers.
The machine normally loads on to tippers directly by slewing the belt
conveyor in case of failure of the mechanism of belt conveyor the
machine can produce coal/mineral by windrowing operation.
In Windrowing the machine moves at a faster rate and cuts the
slices and leaves behind conical section cut material which can be
loaded by deploying pay-loaders on to the tippers.
30

31. The comparison of specifications of the Writgen Surface Miner 2200SM & 2100SM
2200SM 2100SM
Overall length 18200 mm 15500 mm
Overall width 3800 mm 2500 mm
Overall height 4500 mm 4500 mm
Milling/Cutting Width- 3800 mm 2100 mm
Milling/Cutting depth- 0 – 300 mm 0 – 250 mm
Engine output 670 KW/900 HP 448 KW/610 HP
Make of the Engine CATER PILLAR CATER PILLAR
Engine Model 3412 E 3412 E
Maximum longitudinal tilting while milling: 5 Degrees
No. of crawlers 4 4
MAJOR ADVANTAGES OF SURFACE
MINER TECHNOLOGY
Direct excavation of hard material without
need for drilling and blasting.
High productivity
Low cost for multi seam mining including
hard coal and overburden.
Possibility to link the machine directly to
continuous conveyor transport systems.
Higher recovery rate of coal
31

32. Precrushing of coal and elimination of primary
crushing plants high selective mining capabilities
to eliminate interbands to improve coal quality.
Surface Miner shall be very much needed for
future mining due to higher productivity, less
hazard, eco-friendliness, better quality of
product, better exploitation of mining property
and also considering the poor quality of coal
from future coal seams to have an economic
solution for producing low ash coal as per
government regulations for power plants (less
than 34 % ash for transporting distance > 1000
km).
Safety
Eco – friendly Mining – No fatigue.
Less Man power and No HEMM.
No blasting.
There is no fire hazard to the coal seam as it
never leaves behind any material amenable
to spontaneous heating.
The road becomes smooth after even cut
and thus facilitates easy movement of
tippers and other equipment.
32

33. The safety features of the surface miner
are as under.
Five Nos. of engine kill switches, one in control panel, one each
above the crawler units.
Scraper door limit switch - If the scraper door is lifted advance drive
drum drive and conveyor drive will be cut off.
Milling drum side plate warning light:-If the side plate is lifted, red
warning light will start to blink to caution the co-operator.
Reverse motion warning horn.
Discharge conveyor slewing operation gets cut off when windrowing
operation starts. Conveyor slewing can be cut off for
marching/transport for a long distance.
Four warning horn switches one in control panel, one each above
front crawler units.
Constraints.
Steeper Gradient (> 1 in 4)
Danger of Machine sliding along the High Wall.
Coal Seams Containing minute dirt bands
(< 5cms)
Dimensions of the coal bench.
33

34. Table: Cost Comparison with other technologies
SELECTION CRETERIA FOR OC EQPT.
Continuous Miner Technology:
• Presently being used in Neyvali, Lignite Opencast
mines.
• Can be deployed only in soft strata.
• Coal is being cut by bucket wheel excavator
transported by belt conveyors.
34

35. Highwall Mining Technology:
• Highwall mining is a technology that extracts available coal from the
highwall faces of the existing opencast mines, which have reached
their final limit due to uneconomic stripping ratio or due to local
constraints (which limit further mining by normal surface/ opencast
technology), by deploying remote operated equipment.
• This method relies upon the self supporting capacity of the strata
above the series of parallel entries driven mechanically to a
considerable depth without artificial roof support and ventilation in
the seam horizon.
• This technology provides an economical way to extract coal reserves
locked up in the highwall.
• The extent of an opencast project is limited by the financial viability,
though coal seam continues to exist beyond the quarry limits.
• Non-replenishable coal is getting lost forever within the highwalls of
the opencast projects.
• This technology is being practiced in USA, Australia and Indonesia
• Limiting gradient – 1 in 3.5 and maximum penetrating depth (in level
gradient) is around 500 m
Highwall Mining system
35

36. Highwall Mining Methods -
Continuous Highwall Miner (CHM)
Consisting of a remotely operated continuous miner followed by a series
of material transfer cars, creating rectangular entries
Highwall
Miner
Highwall miner
Cutter head
36

37. High wall Mining Technology – Auger Type
• Consisting of single or dual cutting heads with coal being cleared
by spiraled flights, creating circular entries
High wall Mining Technology – Auger Type
DUAL HEAD AUGER
37

38. SCRAPER
Scraper – Machine used in digging, hauling, and grading. Has a
cutting edge, carrying bowl, movable apron, and
dumping/ejecting mechanism.
Scraper machine for moving earth over short distances (up to about
two miles) over relatively smooth areas.
Either self-propelled or towed, it consists of a wagon with a gate
having a bladed bottom.
The blade scrapes up earth as the wagon pushes forward and forces
the excavated material into the wagon.
When the wagon is filled, the gate is closed, and the material is
carried to the place of disposal.
• excavation cum transport equipment
• suitable for soft material
• generally used for top soil removal
• Diesel operated with pneumatic tyre wheels
38

39. OPERATION OF SCRAPER
A scraper is self propelled or towed by a Dozer
It’s blade cuts a thin slice of a earth usually between 100 mm to 250
mm thick over a distance of nearly 30 m.
The earth is automatically collected in the bowl located at the
centre of the machine.
The bowl capacity ranges from 5 cum to 20 cum and takes nearly
half to one minute for loading.
When the scraper is fully loaded its bottom opening is closed
through a table operated by the operator.
At the dumping yard as the Scraper moves, the bottom opening of
bowl is opened, and the contents of earth are unloaded in the layer
150 mm to 250 mm thick over a distance of 30 to 50 m.
Bucket wheel excavators
Originally designed for relatively easy digging materials (gravel, sand, loam,
marl, clays, and lignites), bucket wheel excavators (BWEs) can now dig in
relatively hard material.
These have included compact sediments such as shales, black coal, some
limestones, and tar sands.
The machine digs out the material using a large wheel with buckets that
revolve as the wheel turns. The teeth on the individual buckets are the
primary ground engaging tools that break out the material from the ground.
BWEs are most often attached to a conveyor network where waste material
is sent to a spreader or to an ore stockpile.
BWE considerations:
• Hard consolidated materials, large boulders or blocky material cannot be
handled
• Sticky material build up in buckets and can gum up the conveyor (although,
with modern systems, sticky material can be handled);
39

40. BWE considerations:
Abrasive material produces excessive wear on the teeth (some modern
tooth design can significantly increase tooth life).
The digging face should be stable
Actual output is usually only 45-110% of theoretical
Very limited flexibility (can be flexible in certain geological and equipment
situations)
High capital costs but may be the most economical method of mining
weak flat tabular deposits.
Some advantages in direct reclamation (environmental benefit);
Relatively little manpower
Must closely match downstream equipment (as in all mining operations)
Low total costs
Long life
There must be a matched system linking BWE, side-slewage conveyor
belt system and spreaders
Fig: Bucketwheel nomenclature
40

41. Fig: Bucket cutting and discharge
Advantages of Continuous Excavators
Have lower impact loading than comparable single-bucket machines
Tends to reduce dynamic stresses, machine mass, maintenance
costs,power consumption
Reduced slewing (swing) speed, reduced digging impacts, reduction in
ground bearing pressure
BWE can mine both thin overburden and deeper overburden Conditions
possible where single bucket (dragline) is impossible
41

42. Equipments Installed on BWE
Crawler Drive
Bucket wheel
Rotary Plate
Boom Conv. Systems
Slew Systems
Boom Hoist System
1400 LITRE BRIDGE TYPE BWE
Rated Production : 2250 m3/hr
Outreach from BW boom to Discharge boom : 130 ± 12 metres
Maximum High Cut height : 30 metres
Service Weight : 3193 Tonnes
42

43. 1400 LITRE BWE
Rated Production : 2250 m3/hr
Outreach from BW boom to Discharge boom : 61.3 metres
Maximum High Cut height : 26 metres
Service Weight : 2170 Tonnes
700 LITRE BWE WITH DEEP CUT FACILITY
Rated Production : 1100 m3/hr
Outreach from BW boom to Discharge boom : 63.8 metres
Maximum High Cut height : 18 metres
Service Weight : 1450 Tonnes
43

44. 44

45. Bucket Wheel
The Bucket Wheel is used for
digging and feeding the
overburden to the conveyor
system of the bucket wheel
boom.
45

46. Bucket Wheel
It is dimensioned to achieve the designed machine capacity of 1400 m³
per hour.
Buckets
Fourteen buckets each
having six replacable teeth
are installed on the bucket
wheel.
The buckets are attached to
the bucket wheel with pins at
their front end and with
wedges at their rear end.
Chain mats are provided at
the back side of the buckets
to prevent material from
caking to the buckets.
46

47. EXCAVATION WITH LOCAL DEPRESSURISATION
GROUND WATER PUMPING FROM MINES - 110 Mm3 / ANNUM
45 NUMBERS OF 1000 GPM PUMPS (20” DIA) ARE IN OPERATION
BUCKET CHAIN EXCAVATORS
Bucket chain excavators (BCEs) are similar in structure
and function to BWEs.
However, instead of the buckets being placed in a ring,
they are strung out in a manner reminiscent of a
trencher.
They remove material from below their plane of
movement, which is useful if the pit floor is unstable or
underwater
47

48. Bucket chain
Excavators
Fig: Rock quality classification in relation to excavation processes.
48

49. Table: Excavation Characteristics in relation to rock hardness and
strength
Table: Excavation Characteristics in relation to joint spacing
49

50. Application of Different Surface Mining Excavation Machines
Fig: Seismic velocities in relation to ripping
50