Highwall mining

HIGH WALL MINING
TECHNOLOGY

CHANDAN CHAMAN

What is HIGHWALL Mining
Mining Coal from

 a visible, horizontal or inclined coal seam, making
 rectangular, parallel, unsupported entries, with
 unmanned cutter head and coal transport system, which
 is remotely controlled from a
 mining unit positioned outside the drive, in front of highwall.

When to Highwall Mining
• When economic strip limits are reached.
• When strip limits are reached by surface conditions.
• Extend operational life of mine
• Transition from surface mining to underground mining
• Specific Highwall Mining situations
Contour Mining
Open Cast Mining
Trench Mining
Augered seams

Advantage of Highwall Mining
COST : Highwall mining is clearly cheaper, due to the lower
establishment and development costs. No in-seam support or
transport systems are required, the cost of ventilation measures
is negligible and the capital cost is a fraction of that of a
longwall.

FLEXIBILTY : Highwall mining can economically access smaller
blocks of coal and is more readily able to avoid geological
structures or other impediments to production. The mobility of
the highwall mining equipment makes it easy to move around a
pit, from pit to pit or from mine to mine.

Advantage of Highwall Mining
APPLICABILITY : Because it operates by remote control, highwall
mining equipment can work in thin seams without having to cut
stone to make height for people to move around, or it can
selectively extract a high-quality segment of a seam. The
equipment can operate on steeper dips than miners and shuttle
cars, and can mine multiple seams without subsidence.

SAFETY : Remotely controlled operations, so all personnel
remain outside the entries & therefore not exposed to
underground hazards such as roof falls, gas, dust, irrespirable
atmospheres, flooding, vehicle movements in confined
spaces, etc. With the use of ventilation or inert gas, highwall
mining can continue in gassy seam conditions that would stop or
impede underground mining.

Production & Productivity
PRODUCTION : Modern highwall mining equipment operate in
seam heights of 0.76 meter to 3.05 meter in one pass and seam
dips of up to 12 degrees. Coal production per machine ranges
from 0.5 million tons per year for low seams to 1.5 million tons
per year for high seams, in a continuous operation.

PRODUCTIVITY : Highwall mining requires fewer personnel can
produce 1.5 million tonne pa, compared to around 90 people (3
shifts) to get the same output from an underground mine.

When factoring the lower capital and labour costs of highwall
mining, the cost per tonne is much less than underground
mining.

Requirement for Highwall Mining
 Competent coal.
 Competent immediate overburden. If overburden is not
competent, coal may be left as roof.
 Coal seams dipping from -12 to + 5 degrees.
 Relative flat seams, no faults
 Coal seams thicker than 80cm.

Web and Barrier Pillars
 Web pillars ensure support of OB
 Barrier pillars prevent cascading collapse
 Barrier pillar typically every 10 to 20 drives
 Calculation method to be approved by local Mine Safety
Authorities.

WEB PILLAR BARRIER PILLAR

Cycle of Operation
• Seam is penetrated by a Continuous Miner propelled by a
Hydraulic Pushbeam Transfer Mechanism (PTM).

• Cycle includes pushing forward, raising and lowering of the
Cutter head boom to cut entire length of coal.

• Pushbeams of 6 m is placed between the cutter head and
power head as depth of penetration increases.

• Using Video imaging and gamma detector, the Cutter head
moves inside the seam and cuts only coal.

• All functioning is controlled from a touch screen panel
located in operators cabin.

Safety Consideration
• Highwall Hazard
- Resulting from crushing of Pillar or Failures associated with
insitu structures.
- Avoided by developing 2 Zones i.e. General Safety Zone and
Vertical Drop Zone.

Safety Consideration
• Roof Span Collapse Hazard
- Successful and Safe Operation can be Achieved with Rapid
Entry and Retraction. Otherwise HM Could Readily be
Buried in Rock.
• Explosion Hazards
- To Minimize the Explosion FLP enclosure of Machinery
and Instrumentation Entering the Highwall Drives.
Methane Monitoring Equipments Installed.

Key Features
 Penetration upto 300 meters
 Dip +5 to -12 degrees
 Production up to 120,000 t / month
 Up to 75% seam recovery
 Operates with a 4 / 5 man crew per shift
 Personnel safety
 Low establish cost
 Lower production cost than underground
 No external contamination or product dilution.

DIMENSIONS

Length base : 16.6 m

Width base : 8.3 m

Weight miner : 225 t

Length of push Beam : 6 m

Weight of push beam : 5150 kg

50 push beams per miner

Max. Push Force:
in: 136 t : out: 276 t

Cutter Head
Low Seam Cutter Module
Seam height : 75 cm to 1.50 m
Width : 2.90 m

High Seam Cutter Module
Seam height : 1.20 m to 3.05 m
Width : 3.50 m

Push Beam
Pushing / Pulling cutter module

 Coal Convey modules
 Sturdy, simple, 2 moving parts only
 Enclosed -no External Contamination
 Low Ground Pressure
 Protect cables/hoses
 Structural rigidity that ensures
mining in parallel drives

Inter-Connecting

 Horizontally rigid : Straight Drives
 Vertically hinged : Follow the seam
undulations

Push Beam
Push beams are 6 m long , rectangular , reinforced steel box
structures joined together to form a string, which connects the
highwall mining system to the cutter assembly.

The push beam string is the backbone of the machine; pushing
and pulling the cutter module in and out of the highwall with
retract forces up to 363 tonnes (400 tons) at 345 bars.

The push beams also transport mined coal and support the hose
chain that supplies control and power to the cutter.

Moving coal inside the push beam (via a pair of screw conveyors)
protects the coal from contamination and the moving
mechanical parts from rock debris, resulting in higher
availability.

Reel & Chain

 Power chain for cutter
module
o Electrical cables
o Hydraulic lines
o Cooling water lines
o Methane sensor cable
o Control cables
 Hoses / cabling protected
by steel plating
 Auto unwinds/winds in
trough on push beams
 > 300 m

Anchoring System
Stabilizes the Highwall Miner
Two Machine mounted drills
Two high strength 2.5 m pins

Controls
 Operated from the cabin
 Fully graphical touch screen
interface
 Automated mining mode
 Automatic seam following:
o Cutter motor current
o Gamma Ray Sensor (Optional)

 All machine diagnostics
 Accurate heading:
o Precise alignment
o FOG (fiber optic gyro) guided
steering (Optional)

Generator

 By the grid via a
transformer
 1500 kW Generator Set
 80 kW auxiliary set
 Build in a sound
attenuated 20 ft
container
 Mounted on tracks
 Tropical / Arctic version

Tracks

• 4 Hydraulically powered tracks
articulate 90 degrees for straight
and cross travel
• Circle mode for accurate heading
• Each track 1 meter vertical
movement for adjusting seam dip
and floor contour
• Turning of each track is achieved
automatically

Mobility
 For quick relocation over long distances, the highwall
mining system can be taken apart in modules.
 Rapid disassembly and reassembly is facilitated by
convenient hydraulic and electrical connectors
 All modules are sized for transport using regular public
roads
 Tracks for positioning in
the mine, relative short
distances.
 Longer distances on heavy
weight special transport
low loader.

Safety Features
 Elevated cab with cameras
 Above-ground operation
 Small-crew size for its operation
 Remote operation
 Anchoring system
 Continuous monitoring of the methane by DGMS approved
methane Sensors
 Intrinsically safe & fail safe in design
 Methane sensor device interlocked with PLC control system

Protection Against Methane
 Continuous monitoring of the methane by DGMS approved
methane Sensors
 Intrinsically safe & fail safe in design
 Methane sensor device interlocked with PLC control system
 Power to UG will be “ON” only if:
 The Methane sensor is “ON” & Working properly
 Methane level is below 1.25%
 When Methane level:
 =0.8% - Operator get audio-visual alarm
 >1.25% - U/G part of the machine will be powered “OFF

Optional Features of HM
 Push beam holding device for operation in seams dipping
in access of 8 degrees
 Water pump on cutter module for operation in seams with
ingress of big volumes of water.
 Inert gas system for operation in gaseous seams.
 Arctic and Tropical execution of the miner / genet.
 Second air-conditioned cabin for personnel working on
push beam launch platform.
 Stacker belt for stockpiling mined coal.

Concluding…
Highwall Mining as a coal mining method :
- increases your mine-able reserves,
- mine coal cost effectively,
- with maximum safety
- with minimum risk,
that otherwise would be unrecovered.

BECAUSE RESOURCES ARE LIMITED

Highwall miner @ assembly line

THANK YOU

chandanchaman@gmail.com

Highwall mining

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