The subject deals with High Wall Mining Technology - it use and limitations in Indian mining conditions.

1. HIGHWALL MINING AN OVERVIEW
K. D. PRASADB.TECH.(MINING) GM(Mining), BCCL(CIL)

2. HISTORY OF HIGHWALL MINING
HighwallminingintheformofAugerminingstartedin1983inUSA.
ADDCARsystemofhighwallminerstartedin1990.
SuperiorHighwallminersstartedmanufacturingHighwallminerin1994.
TotalcoalproductionfromhighwallmininginUSA=5o–55milliontonnesperannum.
Totalpopulationofhighwallminerallovertheworldin2011–90Nos.
.

3. WHAT IS HIGHWALL MINING?
HighwallMiningisaremotelyoperatedminingmethodtoextractcoalfromthinseamsorcoalfromunderlyingseamsintheHighwallofsurfacecoalmine.
Condition:Surfacemininghasuneconomicalstrippingratioorduetolocalsurfaceconstraintswhichlimitfurthersurfaceminingoperation.
Equipmentsarecloselyrelatedtoundergroundminingmachinery.
miningmethodishybridofsurface&UGcoalminingmethods.

4. ADVANTAGES OF HIGHWALL MINING
ThismethodreliesuponextractingcoalfromaseriesofparallelentriesdrivenintheseamfromthefaceoftheHighwallwithoutroofsupport.
nomanpowerisrequiredtoentertheentriesmadebyHighwallminerthusmakingitasafeminingoperation.
Operationareunmanned&remote.
Highwallisoneofthesafest&economicalminingmethods

5. LIMITATIONS OF HIGHWALL MINING TECHNOLOGY
Flatseams8to12degree,
Seamsfreefromgeologicaldisturbances,
Seamsdepthof200mtr.,
Seamthicknessbetween0.9to5.0mtr.,
strongroofandfloor,
Moderatemakeofwater.
Lengthofpushbeamwhichisgenerally300ms.

6. APPLICABILITY CONDITION
CoalblockedinHighwallduetoun-economicstrippingratio
Coalblockedinboundariesofopencast.
Coalinthinseamsforwhichnoconventionalminingmethodisavailableoreconomicallyviable
Coalseamsavailableinhillsandforestareas.
Suitableforthecoalblockedbelowtheroads, permanentsurfacestructures,villages.

7. HIGHWALL MINING EQUIPMENT
Base Unit / Advancing launcher
Reels & chains
Controls
Push beams
Cutter Unit
Anchoring
Right angle conveyor
Generator.

8. BASE UNIT/ADVANCING LAUNCHER

9. Mainbaseunitisplacedatsurfacewheremostofthedrivesandallcontrolsarepositioned.
Closedoperator’smaincontrolcabinisontopoftheBaseUnit.
ItalsohouseshydraulicPower-PacktofeedpowertoPush-beamsandcutter-heads.
BASE UNIT/ADVANCING LAUNCHER

10. Reels and Chains

11. REELS & CHAIN
Reelautomaticallyunwindsandwindsconsideringthemovementofthepushbeamanditcontains:-
Powercableforcutterhead.
Controlcableforcutterhead
Methanesensorcable
Hydraulicpressurehoseforcutter
Coolingwaterhoseforcuttermotor

12. CONTROLS
Total operation can either be by automatic through programmable logic controller or-
Manual through touch screen technology or
Fully manual.
Contains self-diagnostic health monitoring system for the machine and u/g environment.

13. PUSH BEAM
Push beam plays an important role for parallel drivageof entries.
contains two contra-rotating augurs for transportation of coal from the coal face.
Articulating in-joint of two push beams provides vertical movement.
It allows the cutter head to negotiate the undulating con-tour of the coal seam.
Normal length of push beam is about 6.0 m.

14. PUSH BEAM (FRONT)

15. PUSH BEAM (BACK)

16. CUTTER UNIT
Cutterunitisbasicallythecutterheadofcontinuousminer.
Operationisfullyremotecontrolledfromthesurfaceoperator’scabin.
Cuttermodulesarechosenasperthicknessofcoalseam.
powerofcuttermotorsvariesfrom240KWto350KW.
Theentirecuttermodulesareinterchangeablewiththemachine.

17. CUTTER HEAD

18. ANCHORING SYSTEM
Two machines mounted on the front of the machine used for drilling into the pit.
Two high strength pins are inserted through the base frame of the miner into the pit floor.
During the mining cycle and retract cycle the anchoring systems stabilizes the HighwallMiner.

19. ANCHORING SYSTEM

20. CONVEYOR UNIT
Conveyor unit facilitates loading/stacking of coal on to truck/on the ground.
A new development at HighwallMiners is the Right Angle Discharge Conveyor.
It can be mounted to discharge coal on the right or left side of the HighwallMiner.
The advantage of the right angle conveyor system is the miner can work on bench of narrow width also.

21. GENERATOR

22. GENERATOR
TheHighwallminingsystemcanbepoweredfromeitherhighlinepowerorbyutilizingtheHighwallminerelectricgenerator.
Themobilegeneratorishousedinasupersilencedcontainer.
Themobilegeneratorismountedoncrawlersforhighmaneuverabilityinroughterrain.

23. MECHANISM OF WORKING
In high wall mining the coal seam is penetrated by a continuous miner propelled by a hydraulic push beam transfer mechanism.
cycle includes sumping(launch pushing forward) and shearing (raising and lower the cutter head boom to cut the entire height of the coal seam).
the push beam transfer mechanism (PTM) automatically inserts a 6.01m long rectangular push beam (screw conveyor segment) into the centersection of the machine between the power head and the cutter head.

24. MECHANISM OF WORKING (contd)
The push beam system can penetrate nearly 300m into the coal seam.
High wall mining system use auger enclosed inside the push beam that prevent the mined coal from being contaminated by rock debris during the conveyance process.
Using a video imaging and/or a gamma ray sensor and/or other geo radar system like a coal-rock interface detection sensor the operator can see ahead projection of the seam rock interface and guide the continuous miner’s progress.

25. METHOD OF MINING
Contour mining
Trench mining
Bench mining, and
Highwallmining.

26. CONTOUR MINING

27. Contour Mining (contd)
Highwallminingfollowsthecontourofthecoalseam,methodisknownascontourminingbyHighwallmethod.
Whenanycoalseam,particularlythinseamappearsatincrop/outcrop,conventionalmethodofminingcontourminingcanbedoneeconomicallyandsafely.

28. TRENCH MINING

29. TRENCH MINING
Entries can be made by excavating a trench to expose the coal seam and Highwallmining can be done both along the exposed coal seam available at dip and rise side.
This is commonly known as trench mining.

30. BENCH MINING
Mining by preparation of benches in each seam for multi-seam working is called bench mining.
For working multi seam deposit, a bench is prepared in the top seam and mining operation is taken top downwards.
Highwallmining can also be done by preparation of benches from bottom upwards but there is a possibility of damages to the coal of upper seams if there is any failure of web pillars at the bottom seams.

31. Bench Mining

32. Mine Floor Coal

33. Highwall Mine Seam

34. Highwall Mine Seam

35. Blast 2nd Bench

36. Blast 2nd Bench

37. Mine Floor Coal Bench 2

38. Highwall Mine Seam 2

39. Highwall Mine Seam 2

40. STRIP SEAM 3

41. Strip Seam 3

42. Strip Seam 3

43. Highwall Mine Seam 3

44. Highwall Mine Seam 3

45. Ready!

46. Blast Bench

47. HIGHWALL MINING
Whentheopenpitmininghasreachedbeyondthestrippingratioorthelimitofminingoperation,thecoalblockedintheHighwall,canbetakenouteconomicallyandsafelybythismethod.

48. HIGHWALL MINING

49. SPECIAL FEATURES
MachineisfittedwithFOG(FiberOpticGyro) navigationsystem.
Ensurestheparalleldrivagesautomatically.
MachineiscontrolledbyPLC,toavoidhumanerror.
Augersystemisuniqueforthewetcoaltransportation.
GPSensuresfasterpositioningofthemachineatdesiredangleofdrivages.
Aninbuiltdevicetomeasuretheroll,pitch,andCutterheadangle.

50. SAFETY
Operationsarecarriedoutbyremotecontrol.
Operator’scabinat6mtrheightandabout20mtrawayfromHighwall.
Nopersonisrequiredtogoinsidethedrivages.
Personsarenotexposedtohazardslikerooffalls, gas,dust,irrespirableatmospheres,etc.
Manpowerrequirementforthewholeoperationisaslowas4pershift.
Oneofthesafestminingmethods.

51. PROTECTION AGAINST METHANE CONCENTRATION
ContinuousmonitoringofthemethanebyDGMSapprovedmethaneSensors
Intrinsicallysafe&failsafeindesign
MethanesensordeviceinterlockedwithPLCcontrolsystem

52. PowertoUGwillbe“ON”onlyif:
TheMethanesensoris“ON”
Workingproperly
Methanelevelisbelow1.25%
Protection Against Methane Concentration

53. WhenMethanelevel: =0.8%Operatorgetaudio-visualalarm>1.25%U/Gpartofthemachinewillbepowered“OFF”
Protection Against Methane Concentration
Incasemethanesensorswitchedofforisinfaultmodeallelectricalpowersourcesincludingsignal&controlwillbeshutoff(failsafe)

54. COAL DUST SUPPRESSION
Water spraying on the cutter head –at a flow rate of 19 litreper minute at a pressure of approx 20 Bar.
It is interlocked with power supply to the cutter head

55. PROTECTION AGAINST FALL OF OBJECTS
The construction of the operator’s cabin protects operator
Area of operation of the grounds man is below the steel structure of the machine

56. NAVIGATION SYSTEM
The machine is capable of making parallel drivageswithout navigation system.
However, FibreOptic Gyro (FOG) system can be provided for auto Steer control

57. THANK YOU