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

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

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  • Dear Mr Soren,

    The Journal of Mines, Metals & Fuels, is organsing the 2nd Intl Conf. on 'Surface miner' at Kolkata between 17-18 Aug 2012. If you are interested to know about this conf and interested to participate in this conf. as a delegate or contributor of paper, kindly send me your e-mail ID so that I can provide more details on the subject.

    Looking forward to hearing from you.

    P K Chanda
    JMMF; pradipchanda@yahoo.co.uk
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    Oc mechanical excavation Oc mechanical excavation Document Transcript

    • 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
    • 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
    • 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
    • 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
    • HYDRAULIC SHOVEL – Backhoe or Pull ShovelBackhoe-pull shovel – A shovel with a boom-and stick- mounted bucket that digstoward itself. Hydraulic Shovel- Front End Loader 5
    • Hydraulic Shovel & DumperRope Shovel & Dumper 6
    • Rope Shovel & DumperRope Shovel & Dumper 7
    • Fig: Shovel Dipper or BucketDraglines: • 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
    • DRAGLINE Dragline – Revolving shovel that carries a bucket attached only by cables and digs by pulling the bucket toward itself.DRAGLINE BUCKET 9
    • 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
    • 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
    • DOZERA bulldozer is a crawler (Continuous tracked tractor) equipped with a substantialmetal plate (known as a blade) used to push large quantities of soil, sand, rubble,etc., 12
    • DOZER OPERATION OF DOZERIt 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 mountedDozers also used)the pusher blade can be raised lowered or tilted through smallangles 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 / gradingand compacting the ground, for laying haul roads, for toeingdumpers etc., for pushing boulders trees etc.,There is different capacity of Dozers ranging from 100HP to 800HP and normally used are 400 HP, which costs app. 1.2 Cr. 13
    • 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
    • WHEEL DOZER 1968 Caterpillar 824 Wheel Dozer WHEEL DOZERtractors outfitted with dozer blades or push blocks.used as push tractors in scraper applications.Though these machines can be converted from wheel loaders byreplacing the loader’s bucket with a dozer blade, this configurationis only successful for light-duty tasks.Used for clearing and grading land, wheel dozers are frequentlyused in mining applications and reclamation jobs.The wheel dozers’ advantage over crawler dozers is their ability tomove quickly.Additionally, they can travel between multiple job sites withoutdamaging paved roads. 15
    • RIPPER DOZERThe ripper is the long claw-like device on the back of the bulldozer. Rippers cancome as a single (single shank/giant ripper) or in groups of two or more (multishank rippers). Usually, a single shank is preferred for heavy ripping. The rippershank is fitted with a replaceable tungsten steel alloy tip. RIPPER DOZER 16
    • RIPPER DOZER RIPPER DOZERtractors 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 rippersoperates like a plough to loosen moderately hard rockcan be also used to extract thin seams where the thickness isless 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 knownas pipe layer for transporting pumps, pipes and laying pipes. 17
    • Fig: (a) Radial ripper, (b) Parallelogram ripper, (c) Adjustable Parallelogram ripperRippability is determined by:• Compressive strength• Bedding planes, joints and fractures;• Brittleness;• Softness (from weathering). 18
    • 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 MinerSurface 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
    • 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 MinerMachine with frontBoom 20
    • Types of SurfaceMiner 21
    • 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
    • A modern surface miner –heres how it works VIDEO Wirtgen SM 2100 SCHEMATIC DIAGRAM 23
    • Technical highlight:Clever design with central cutting drum 24
    • 25
    • 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
    • Fig: Extraction with Surface MinerSurface miner may be operated in three modes Front or rear loading to dumper or truck Sidecasting Windrowing 27
    • ADVANTAGES OF SURFACE MINERImprovement of quality by selective mining of coalEco-Friendly mining of coalImproved coal recovery especially in areas sensitiveto blastingLess coal loss and dilutionPrimary crushing and fragmentation of coal WORKING PRINCIPLE OF SURFACE MINER (SM 2100 / 2200)The surface miner features a drum shaped cutting ormilling head fitted with a number of tungsten carbidetipped replaceable picks extending across the full widthof the machine in the form of a helix which facilitatespropelling of the cut materials towards the center of themachine.The cutting drum is located between the two sets of thecrawlers and is centrally positioned making the machinecompact.The milling drum is mechanically driven by the directdrive system through transmission V-belts directly via amechanical clutch on the flywheel side of the dieselengine. 28
    • 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 thesecondary conveyer, which in turn loads the material finally ontothe truck or side casted in the mine.The cutting drum is followed by a scraper blade which gathers anymaterial left on the floor.This ensures a clean and smooth floor without any Undulations.Dust suppression is ensured by means of water spray arranged onthe cutting drum, which also serves the dual purpose of cooling ofpicks, thus prolonging their useful life.The surface miner has two sets of crawlers, each individual crawlerunit in front set has its own steering cylinder facilitatingnegotiation on the sharp turns. 29
    • Each crawler unit and the cutting head can be raised or lowered bymeans of hydraulic cylinders provided for the purpose.The surface miner is equipped with an air- conditioned operatorscabin, which has all machine controls within comfortable reach ofthe operator.The depth is adjusted through electronically controlled depthregulator located at the side of the machine which is operated bythe co-operator at the floor of the machine.The surface miner is also equipped with flood light for nightoperation 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
    • 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
    • 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). SafetyEco – friendly Mining – No fatigue.Less Man power and No HEMM.No blasting.There is no fire hazard to the coal seam as itnever leaves behind any material amenableto spontaneous heating.The road becomes smooth after even cutand thus facilitates easy movement oftippers and other equipment. 32
    • The safety features of the surface miner are as under.Five Nos. of engine kill switches, one in control panel, one eachabove the crawler units.Scraper door limit switch - If the scraper door is lifted advance drivedrum drive and conveyor drive will be cut off.Milling drum side plate warning light:-If the side plate is lifted, redwarning light will start to blink to caution the co-operator.Reverse motion warning horn.Discharge conveyor slewing operation gets cut off when windrowingoperation starts. Conveyor slewing can be cut off formarching/transport for a long distance.Four warning horn switches one in control panel, one each abovefront 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
    • 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
    • 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
    • Highwall Mining Methods - Continuous Highwall Miner (CHM)Consisting of a remotely operated continuous miner followed by a seriesof material transfer cars, creating rectangular entries Highwall Miner Highwall miner Cutter head 36
    • 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 TypeDUAL HEAD AUGER 37
    • SCRAPERScraper – Machine used in digging, hauling, and grading. Has acutting edge, carrying bowl, movable apron, anddumping/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
    • 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
    • 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
    • Fig: Bucket cutting and dischargeAdvantages 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
    • Equipments Installed on BWECrawler DriveBucket wheelRotary PlateBoom Conv. SystemsSlew SystemsBoom 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
    • 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 Tonnes700 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
    • Bucket Wheel The Bucket Wheel is used fordigging and feeding theoverburden to the conveyorsystem of the bucket wheelboom. 45
    • Bucket WheelIt is dimensioned to achieve the designed machine capacity of 1400 m³per hour. BucketsFourteen buckets eachhaving six replacable teethare installed on the bucketwheel.The buckets are attached tothe bucket wheel with pins attheir front end and withwedges at their rear end.Chain mats are provided atthe back side of the bucketsto prevent material fromcaking to the buckets. 46
    • 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
    • Bucket chain ExcavatorsFig: Rock quality classification in relation to excavation processes. 48
    • Table: Excavation Characteristics in relation to rock hardness andstrengthTable: Excavation Characteristics in relation to joint spacing 49
    • Application of Different Surface Mining Excavation Machines Fig: Seismic velocities in relation to ripping 50