COAL MINE PLANNING & DESIGN -A.V.REDDY,ADDL.MANAGERThe Singareni Collieries Company Limited

Mining Methods Generally Coal is being mined by two main methods Surface or Opencast mining Underground mining.

The choice of method is largely determined by the depth, thickness and no. of coal seams, geology of the coal deposit and other factors.

Reconnaissance Survey To plan for winning any coal deposit, the required data/Information is

Geological Report of the BlockSurface features exists in and around the deposit

1.Geological Report / Geo-Model Geological Report will be generated basing on the detailed exploration of the deposit.The Borehole data generated with detailed exploration will be used for preparation of Geological Report.Many soft wares are available for generating geological report and the report generated through soft ware is called Geo-Model.MINEX, SURPAC, DATAMINE are some of the soft wares currently being used for preparation of Geo-Model.

What is Geological Report / Geo-Model? Geological Report / Geo-Model consists of

Surface Topography Hills, contours, rivers of Flats Geological Map in crops, Faults Graphic Lithologs Graphic correlation charts Floor/Roof contour plans of all seamsSeam folio plans of all seams (seam out cop, floor contours, faults, Iso-UHV, Iso-chore, Iso-depth). Geological cross sections Seam structure of all seams ISO parting plansISO excavation plan for lower seam (surface constraints, boundaries, faults at seam level, excavation area)

Additional data Geological Report

Geo-technical data - Diggability of materials, slope geometry and stability of Working/permanent slopes, spoil pile configuration for outside/inside dump, stability, grainsizes after blasting etc.

Ground Water - Dewatering and depressurization Hydrology Impact of dewatering on surrounding areas - Impact on water quality

Surface Hydrology - Water quality - make off water - Mine flood protection - Options for discharge of dirty water and various discharge systems.

2.Study of Surface FeaturesFor opening up of any deposit, it is necessary to study the surface features within and around the deposit and the data which consists ofPresence of villages/habitats - Densely populated areasPresence of rivers/Jores/nalahs/railway lines/roads etc.Type of land including land use - Forest/Non ForestEcologically Sensitive areas like wild life sanctuaries, Bio reserves, National Parks and archeologically important structures/monumentsInter state/National boundariesCritically Polluted areas/Environmentally fragile areas

Conceptual StageAfter detailed study of Geological Report coupled with study of detailed surface features, a Conceptual Report will be prepared with various options. A detailed review on Conceptual Report will be taken up before finalising the method of work to be adopted and the technology to be used.After finalising the method of work, Detailed Project Report will be prepared which includes Technical and Financial feasibility.

DepositTech-AspectsEconomic aspectsResources GR/MR Mining depthStrata SequaThickness of - coal - waste - inter burdenCoal QualitySlope stabilityWaterMining Technology Options andSuggestions Equipment Surface Constraints Production requirements Minelife requirementsLogistics, Roads etc. Cash out flow Cash inflowRequired rate of ReturnCut-off SR Conceptual Mine Plan

Pre-Feasibility StudyModification of conceptand or optimizationNot accepted New attemptManagement Accepted DPR

Opencast MiningShovel Dumper TechnologyDrag line-Shovel Dumper TechnologyExtended Bench methodSpoil Bank methodIn-pit Crusher & Conveyor TechnologySurface Miner TechnologyRipper - Shovel TechnologyRock Breaker TechnologyHigh Wall Mining Technology

Underground Mining

Two types of access to the coal deposit for winning the coal with underground technology

InclineShaftAdit

Underground Mining Different technologies

Bord & Pillar TechnologyManual MiningSemi Mechanisation with SDLs/LHDs/ScrapersDepillaring with cavingDepillaring with stowing

Longwall Mining TechnologyLongwall advancingLongwall retreatingShortwall Mining

Blasting Gallery Technology

Continuous Miner Technology

InclineExcavatorShaft MineIncline MineAdit MineOpencast MineMining Methods

OPENCAST MINE PLANNING & DESIGNING

Thickness of coal seams-> 5m

Flat gradient-< 1 in 6

Strike length-> 1 km

No.of seams-Less the better, with higher thicknessCoal without stone bands

Free from surface structures / features.

Preferably non-forest land.

Availability of adequate place for dumping.

9.Stripping ratio depending on quality of the coalIdeal conditions for Opencast Mining

There will be some overlap between various studies/reports.

Every step deals with Mining Technology, equipment, production scheduling, capital cost, revenue cost, internal rate of return, dispatches etc. However the degree of accuracy of data on the above aspects increases with each step.

Generally After F.R. approval, there is need to go in for long term planning, medium term planning (about 5 years) and S.T.P. Short-term planning (6 months one year).

These reports should adapt circular analysis approach by considering various aspects like additional information available while operating the mine, slippages occurred, reserves, pit-slopes, pit-limits, pit scheduling to control faster rate of extraction from coal inventory which otherwise may lead to reduction in coal production in subsequent years or more equipment for higher OB removal to maintain targeted production.

Basis for the initial study is Geological Report

Study of deposit exploration (GR)Final pit limits.Development sequence. Design of Access Ramp and Haul RoadsPit designAnnual production capacity system availability Mining technologyMain Mining Equipment Matching to Mining PlanOptimizing Dumping strategy and balancingYear-wise / Stage Wise plansFinancial viability (Capital & Revenue)Coal WashingEnvironment Stipulations

Steps in designing of Opencast

Extent of deposit i.e. strike and dip rise widths.Geology Geological succession, sequence of beds, drilling, logging, no. of seams, sequence of coal seams, description. Inter seam partings.Structure No. of faults, Throws, dip of seams and beds Reserves Quality wise/seam wise/depth-wise etc. based on Block model, Gridded seam model & polygonal Model O.B. volumes & S.R. Sector-wise, depth-wise etc. Coal seam analysis, proximate and ultimate , Ash etc. & OB strata hardness etc. Drilling details (Lithology)Physiography Climate and Vegetation Preliminary EMP informationSalient InformationA. Study of GR on the deposit Exploration

Rise side boundary - Usually incrop of the bottom most seam Lateral sides- Usually by Geological disturbances like faults, surface structures / features like nalah, river etc or limitation of the strike length of the deposits.

Dip side- Depends on the economical stripping ratio, in absence of natural constraintsThe criteria for delineation of boundaries of an Opencast ProjectB. Final pit limits Haul analysis Lead, lift increase cost - Decides mode of transport Dump area -100m from mine boundaryDump limits - Dump area - 50 m from internal access road. - Dump area - 80-100 m. from mine infrastructure Mineable Reserves - various losses, batter, barrier etc. - dilution etc (50 Cm against Roof, floor) Maximum depth - increases haul cost (30-40% of total cost at 1 1/2 Km lead)

Estimation of Coal, OB & Stripping ratio Rough assessment is given below Assuming Pit slopes of 450, the Quarry floor and Quarry surface are delineated

Volume of Coal & OB= Average area x Average depth - (A)

Average area= (Quarry surface area + Quarry floor area) / 2

Average depth = (Minimum depth + maximum depth) / 2

Volume of Coal=(Quarry floor area x Cumulative thickness of all coal seams) - (B)

Coal in tonnes= Volume of coal x Specific gravity (C)

OB Volume= Coal + OB Volume (A) Coal Volume (B) - (D)

Stripping ratio= OB Volume (D) / Coal in tones (C) For accurate S.R,the volumes of OB and coal are to be made seam wise Contd.B. Final pit limits

The boundaries are firmed up based on the economic stripping ratio.Economic stripping ratio varies with:

Average sales realization i.e. higher the quality of coal, higher the realization.Capital investment requirementsOperating cost.Also surface constraints The following thumb rules may be of some Help (with outsourcing OB removal):Projects are likely to be economically viable upto a maximum SR indicated against the grade of coalB. Final pit limits Contd.

GradeStripping ratio(Cum/T)F6E7D 8C 10

Opening the deposit Access trench Box cut - To accommodate all equipment Mine phases - Depends on the shape of the propertyProgress of Benches Coal production schedules OB excavation schedules Note:- Maximize inventory of coal in the initial years Differ OB stripping requirements as much as possible Average SR versus natural SR Income generated in the first 5 to 10 years but not remote economics will either make or break the project. Profits for in the future have practically no impact on the project NPV. Each successive phase will be less profitable and the ultimate limit will be loss even after ploughing in earlier profits. C. Development Sequence

Location of Access ramp is guided by the following:

Generally located at the minimum depth of incrop of bottom most seam So as to reduce initial waste stripping (unproductive work)

Should facilitate maximizing of internal dumping and sectional working.

Should be near the External dump / Coal yard / Mine service facilities etc.Main haul road upto the pit limit should be planned in the beginning only.Since haul costs constitute about more than 40% and tyre costs about 10% of the total mining costs,priority for design,construction and maintenance should be given.Gradient,width,drainage,curves,super elevation,base,sub base,type and thickness of top dressing should be like that of national high ways for heavy traffic.D. Design of Access Ramp & Haul roads

D Contd.D. Design of Access Ramp & Haul roads

Sl.NoParticulars1WidthShould facilities two way traffic, dozer movement, formation of drains, lighting arrangement (Normal width 30m, but depends on capacity of dumpers).2Gradient1 in 163Lesser number of curves4In flat seams of larger strike length Haul roads can be formed over the floor of the seam 5In steep seams Haul road for Coal & OB benches can be planned along highwall slopes say every 30m. This will also facilitate internal dumping.

General design parameters and planning data Density of seams, total coal column thicknessThickness of partings GradientGeological disturbances Strike lengths, shape of propertyGeological Reserves Surface constraints/adjacent habitat Dump yards availability with lead and lift Mining system, optimum mining concept Depth of operation, mineable reserves after various losses, OB volumes, SR Spoil characteristics Work practices in the Area Diggability characteristics E. Pit design

As per Regulation 98 of CMR 1957,

In alluvial soil etc. - Sides shall be sloped at 450 or Benched height not more than 1.5m Width not less than height

In hard ground- Sides adequately benched/sloped so as to prevent danger from fall of sides

Coal- Sides shall be sloped at 450 or Benched height not more than 3m

However, exemption can be sought from Inspectorate.E Contd.E. Pit design

Overall slope of a pit depends on several factors of the pit slope:

Geological disturbances like faults etc.

Hydrological condition of strata

Orientation of slip planes

Nature of strata i.e. hardness, material consolidation etc.

Depth of workings

Design of haul roads & ramps in the highwall

Stratigraphy thickness, spacing of the clay bands or other weak layers E Contd.E. Pit design

In general for OC mines upto a depth of 200m, overall slope angle of 450 is permitted.E Contd.E. Pit design

For deeper mines flatter highwall slopes will be necessary from safety point of view (for 35 T dumpers & above)E Contd.E. Pit design

For deeper mines flatter highwall slopes will be necessary from safety point of view (dumpers below 35T capacity)E Contd.E. Pit design

Typical High wall layoutE Contd.E. Pit design

Working benches

1) General Width - 40 45mHeight - Generally equal to height of the boom or in some cases upto 3m above the boom height. In case of Backhoe digging height of machine Bench slope - 560 to 700

2) Dragline:Width of the cut -60mHeight of bench-maximum digging depth

3) In order to even out the yearly OB removal quantities and the economics sometimes alternative workings and non-working benches (around 25 m wide) are proposed.E Contd.E. Pit design

After defining the boundaries, the annual production capacity will be fixed based on the following criteria :The available mineable coal reserves

Geometry of the deposit - Strike & dip rise lengths

Structure of the deposit - Thickness of seams, partings, faults, gradient etc.

4) Linkage - Basket, Captive use etc.

5) HEMM configuration - Capacity of HEMM.

6) Surface structures - Limits the material to be blasted.F. Fixing annual production capacity

G Contd.Based on ,-Dipper cycle time -Waiting time for truck spotting -Bad blast factor -Truck loading time etc.Annual capacity is based on -Equipment available hours -Utilization percentage Proper fragmentation,less throw off material,bench height,bench slopes ,avoiding toes and secondary blasting,improves shovel efficiency Optimum fragmentation-cost of drilling,blasting vis--vis cost of dozing,loading,hauling and dumping.

G. Excavator machine productivity

G Contd.12% - Crusher + 1 Conveyor2% Drop for each BeltEffective Operating Time

5559/3730

System availability as a function of individual components Calendar hours-(365x24) (Figures are Indicative only)8760Holidays and bad weather2.5%-scheduled working hours(SSH) 8463 / 6140Operational delays-blasting, relocations,shift change,Lunch etc1 Hour/Shift(8%)Scheduled operating time or Equipment available hours6563/4390Preventive maintenance-i.e annual,weekly,daily,shift wise and unexpected break downs15% of SSHAvailabilty- 100%Shovel,dumper system 97%Effective Operating Time6366/3960 85%

73%System Availability4804/3160

Note: In seam Mining is always practiced in flat seams while in case of steep seams Horizon mining, with its disadavntages, may have to be followed.

G Contd.

This is the most commonly used technology in Opencast mines.

Basically two variants Rope shovels and Hydraulic shovels.

Shovel used for excavation & Dumper for transport of material.

Bucket capacities vary from 0.9 Cum to 40 Cum with matching Trucks/Dumpers of 16 Cum to more than 240 T.

Can be deployed for removal of varying thickness of materials.

Harder materials require blasting.

Can be deployed for removal of steep & thin seams (hydraulic shovels). 1)Shovel dumper technology: G. Main mining equipment G Contd.

A dragline bucket system consists of a large bucket which is suspended from a boom with wire ropes.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 & can be deployed in flatter seams.2)Draglines:3)In pit crusher conveyor technology:

The drilled & blasted OB is loaded by shovels and transported by dumpers to Crushers. The crushed OB is then transported by a series of conveyors into a spreader for dumping.Can be used in steep seams where laying of transport roads for the trucks is difficult.

While S.R indicates volumes,cut off ratio indicates depth and reflects in dumper haulage cost,which increase with depth and may become prohibitive where in alternative haulage system may have to thought off.

Ideally suited where material has to be transported over a large distance & lift.4)Continuous Miner Technology:- Bucket Wheel Excavators Presently being used in Naveyali, Lignite Opencast mines, having soft strata.The buck wheel excavates the material without blasting which is transported by a series of belt conveyors to spreader.G. Main mining equipment G Contd.

Rock breaker technology can be applied for breaking of rock/coal/ore even about 500 kg/sq.cm.It can be used wherever it is not possible to go for blasting near vicinity of structures and habitations. 5)Rock breaker technology: 6)Surface Miner Technology:Used for selective mining.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. The machine cuts the coal & loads into trucks for onward transportation to Surface Other common mining equipment to all the technologies DrillsDozers ,Graders & CompactorsWater SprinklersPumps etc.Electrical equipment Crushers & Conveyors for Coal/OBG. Main mining equipmentG Contd.

Rope Shovel & Dumper

Hydraulic Shovel & Dumper

An opencast mine with dragline

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IN-PIT CRUSHER CONVEYOR TECHNOLOGY (Spreader in Operation)

Surface Miner

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Rock breaker

Internal dumping:

Depends on the steepness of the seams.

As the gradient increases, the percentage of dumping reduces.

Internal dumping can be increased by sectorial working of the pit which may reduce the annual output.

Toe of the dump generally kept at a distance of 100 m from the working benches.

Floor of the pit to be roughened by blasting for increasing dump stability.General design of dumps:

Deck height 30m Berm width 30m Deck slope 370 Overall slope 280 Swell factor for OB-1.38,for coal 1.40 Swell compact after initial settling 1.20 Note:-Dump yard management and control is essential for the success of open cast mining. In case of more than one External Dump yards, balancing the excavation volume to either of the dump yard should be based on lead & lift and size of the Dump yards.H. Dumping strategy and balancing

Total dump height- 90mDeck height 30mBerm width 30mDeck slope-37 0 Overall slope-280H Contd.H. Dumping strategy and balancing

Total dump height- 90mDeck height 15mBerm width 15mDeck slope-37 0 Overall slope-24.830H Contd.H. Dumping strategy and balancing

Internal Dumping reduces with the increase in the gradient of the seam.H Contd.

I) Stage plansStage plans are prepared based on Year-wise production requirements (rated out put)

Stage plans at the end of years 1, 2, 3, 4, 5 & in intervals of 5 years are prepared.

Also plans are prepared where any specific land mark like a new box-cut, change in layout will take place.

I. Designing the year-wise / stage wise plans

The requirement of HEMM & its capital is estimated.

Other capital like developmental works, CHP etc are worked out.3) Operating expenses are worked out to arrive at cost of production.4) Financial viability including profit & loss , IRR etc is estimated. 5) Based on required IRR, anticipated selling price is also worked out.J. Financial Viability

As per EP Act 1986Environmentincludes water, air and land and the inter-relationship which exists among and between water, air and land and human beings, other living creatures, plants, micro organism and propertyL. Environment stipulations

AirImpacts: Dust is generated from drilling, blasting, excavation, crushing and transportation operations. This dust becomes air borne and gets carried away to surrounding areas.Mitigative Measures Extensive water spray arrangements at the Coal handling sites.Wet-drilling methods are to be adopted. Water spraying on haul roads and permanent transport routes at required frequencies. Provision for mobile water sprinklers has to be made for this purpose.Extensive Green Belt development around the quarry and OB dumpBlack topping the transport routes and avenue plantation on these roads.L Contd.

Water spraying on the haul road

Continuous water spraying on the haul road

WaterImpacts: Pollution of the surface water bodies with the mine discharge water and domestic sewage.

Mitigative Measures:The Mine Discharge water is to be treated in settling tanks before discharging it into the surface water bodies.Effluent from workshop is to be treated in ETPs.Sewerage treatment plant to be provided for treating the domestic sewage from the colony.L Contd.

ImpactThe main sources of noise in the project are electrical and diesel-powered machines, compressors, pumps, drilling machines, dumpers, etc. During blasting operations blast vibrations will take place. Control MeasuresControlled blasting techniques using NONELs are to be adopted . Creation of green belts of dense foliage in three rows between mine areas and residential colonies.Proper maintenance of machinery including transport vehicles.Protective devices like earplugs and earmuffs are to be provided to the needy workers.Sound and dust proof cabins are to be provided in the machines like dozers, shovels, dumpers and feeder breakers at CHP etc.L Contd.Impacts and Mitigative Measures

Topsoil excavated from the quarry is to be dumped separately at predetermined place and has to be subsequently spread on external dumps for plantation. Top soil dump is to be kept not more than 10m height.Top soil has to be vegetated with grasses and leguminous species to maintain its fertility.The reclamation of O.B dumps is to be done by using Biological Engineering techniques for stability of slopes and prevention of soil erosion from O.B dumps.Construction of crib structures, Gabion structures, forming of staggered Contour trenches are to be practiced for stability of slopes. Over Burden ManagementL Contd.

Raising of seedlings on both top and slopes of the dumps in the staggered contour trenches.By dibbling seeds of various species like Avisa, Subabool, Babul, Neem etc.Safe disposal of rainwater by construction of garland drains. Garland drains are to be provided around the quarry and overburden dumps .Over Burden ManagementL Contd.Impacts and Mitigative Measures

Safe disposal of water from Top of OB

UNDERGROUND MINE PLANNING & DESIGNING

Conventional underground miningSDL & LHDRoad HeadersLongwallBlasting GalleryContinuous Miners

36 UG MinesCoal: 11.9 MTDepths operated: 400 mtsDepths Planned: 600 Mts.

Our Technology Under GroundTechnologyOperational Profile

Bord & Pillar (Manual Mining)Coal is broken by drilling and BlastingBlasted coal is manually loaded in to tubsCoal tubs are hauled to surface

Bord & Pillar (Semi-Mechanisation)Coal is broken by drilling and BlastingBlasted coal is lifted by machines and unloaded in to tubs or on to belt conveyors.Loading MachinesSDL Side Dump Loader (for 140 and flat gradients)LHD Load Haul Dumper(for 100 and flat gradients)SDLLHDCapacity : 1.0 Cu.MAvg. Production : 140 Tn/day Capacity : 1.5 2.7 Cu.MAvg. Production : 120 - 180 Tn/day

Suitable for Thick seams around 10.0m at 100 and flat gradient.Layout is more or less like Bord & PillarDevelopment of Large rectangular pillars is done in bottom section (3.0m height) by drilling & blasting. Loading by LHDLHD in a Blasting Gallery mine

Roof coal is taken while extracting pillars by heavy blasting.Coal from Goaf is lifted safely by remotely operated LHD.Annual output is around 3.0 Lt

Ring hole Blasting

Two long Roadways are driven parallel to each other by machines and connected at the end to form a Longwall face.The long rectangular block thus created is cut in to slices by Shearer. Coal from Longwall face is transported by series of Chain conveyors and Belt conveyors.

Face ConveyorShearerSupportsRoad header

Rate of drivage 50 meters/dayProduction 1500 Tonnes/day For seams of 1 in 5 gradient and flatterThickness of 3.0 m to 4.0 m

Bolting -240 bolts/day For seams of 1 in 5 gradient and flatterThickness of 2.0 m to 5.0 mContinuous minerShuttle carRoof BolterContinuous Miner The following mines are identified for Introduction of Continuous miners in SCCL:VK 7 InclineGDK-11A InclineWith Shuttle/Ram cars as Backup

Our Technology - Opencast

DraglineShovel & DumperSurface MinerInpit crushing Conveying SpreadingHighwall

13 OC MinesCoal: 25.8 MT OB: 140 M Cu MStripping Ratio: upto 1:6Gradients operated : upto 18Depths operated: 170 Mts.Depths Planned: 400 Mts.

TechnologyOperational Profile fuelling growthThe Singareni Collieries Company Limited(A Govt. Company)

Seams which are available at shallow depths and where stripping ratio is economically favourable Open Cast Mining is practicedSeams which are uneconimical due to high stripping ratio are mined by Under ground methodsThese coal seams are approached by vertical shafts and inclinesInclines are preferred when the coal seams are available at a depth of100 to 250 mts from the surface.Shafts are preferred when the coal seams occur at deeper depths

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Thank You

Power Houses consume about 75% of coal.

Power Houses are designed to accept Coal of E Grade & above (UHV>3300).

The percentage of production of coal below E Grade is increasing .

MoEF stipulation Presently the onus of responsibility is on end user for using Coal of not more than 34% ash if he is located over 1000Km away.

Hence, the need to upgrade coals below E Grade so as to suit the requirements of Power houses.

Cost of washing is around Rs 120-130/T of raw coal.Need for WashingK. Coal Washing

Photograph of STP

Treatment plant for Work shop effluent

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