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DRAGLINE• Walking draglines are for many years the most popular machine for opencast mining due to their flexibility, utility and availability.• their low operating costs for waste mining• 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- cost of OB removal is cheaper than shovel dumper technology.• There are two draglines working at RGOC-I and RG OC-III with bucket size of 24 Cum and 30.6 Cum respectively.• Both these draglines are performing very well.• The bucket is maneuvered by means of a number of ropes and chains. ISN
DRAGLINEThe dragline is a typical combined cyclic excavator and material carrier since it both excavates material and dumps it without the use of trucks or conveyor belts. The dragline sits above the waste or overburden block, usually 50m or so wide, on the highwall side and excavates the material in front of itself, to dump it on the low-wall or spoil side of the strip to uncover the coal seam below it. ISN
OPERATION OF DRAGLINEIn a typical cycle of excavation, the bucket is positionedabove the material to be excavated.The bucket is then lowered and the dragrope is then drawn sothat the bucket is dragged along the surface of the material.The bucket is then lifted by using the hoist rope.A swing operation is then performed to move the bucket tothe place where the material is to be dumped.The dragrope is then released causing the bucket to tilt andempty. This is called a dump operation.It is a independent machine unlike a shovel.A 30 cum Dragline can handle 40 Lakh cum of OB per annum.The dragline works on the immediate OB bench above coaland the benches from the surface to the Dragline are normallyhandled by Shovel & Dumper combination. Hence adequatecapacity of Shovel & Dumper ISN capacity should be provided toprevent idling of the Dragline.
OPERATION OF DRAGLINEThe Dragline has a long boom with a bucket capacity rangingfrom 15 to 50 cum.It can swing in 360 degrees, after dragging the loose materialbelow its level.It swings normally between 90 to 120 degrees and side castthe material in to the de-coaled area.The nomenclature of the Dragline usually called as 24/99which means 24 cum of bucket capacity and 96 m is the boomlength.The same Dragline can have about 32 cum of bucket capacityif the boom length of 71 m. normallythe Draglines is electrically driven with 6.6 KV power with 2main motors of 1750 HP each. These motors inturn drive theGenerators and the Generators drive DC motorsNormally there are 7 DC motors for different operations like ISNmarching, dragging, hoisting, swinging etc.,
APPLICATION OF DRAGLINE1. Gradients flatter than 1 in 6 (if gradient is more the dumped OB will slide towards the coal face and particularly in rainy season the extraction of coal become dangerous)2. Seams should be free of faults & other geological disturbances3. Deposits with Larger Strike length (>2 km) so that frequent shifting of the Dragline from one end to another can be reduced.4. Present cost of the Dragline is above 100 Cr and the life of the Dragline is 1.50 Lakh hours hence, the property should be large enough ensuring the life of about 25 yr or more.5. A hilly property is not suitable ISN6. Property should have atleast 15 years life
DRAGLINE – Methods of Working– Simple casing method with or without rehandling.– Extended bench method.– Horse shoe /Spoil Bank/Across Pit method.– Continuous bench two pass method.– Tandem dragline working i.e., two draglines working together, one dealing with part of the material dumped by the other. ISN
Simple CastingThis is simple method of Dragline working. In this method the Dragline is sitedon immediate OB bench above Coal and removes the OB and dumps it in thede-coaled area of previous cut.The width of the cut normally less than 40 m so that re-handling of the OB willbe negligible. The method is extremely suitable for singly thin seam mining. ISN
Extended Bench Method• As the name is suggested, the Dragline bench is extended by dumping a part of OB by dragline into de- coal area and the space is levelled by dozing and the same Dragline can be sited in 2nd position on the dumped and dozzed OB.• This enables the distance between 1st and 2nd position to be more when compared with simple casting method.• The increasing distance increases the capability of the Dragline to dump OB further away in de-coaled area, so that sliding of OB on to the coal bench is to be minimized.• A Dragline has to do more re handling now. This method is suitable for exposing relatively thicker seams. ISN
Spoil Bank Method• The method is adapted when there are 2 seams and having parting between 10 to 12 m.• In the first position, the Dragline exposes the top seam by side casting the OB above the top seam.• The side casting material is dozed and leveled.• After extraction of the top seam the parting OB is loosened by blasting and the Dragline is placed on the already side casted leveled material and the remaining parting OB of above bottom seam is removed by the dragline and side casted exposing the bottom seam. ISN
Tandem Working of Draglines• In this method 2 Draglines are put into in tandem operation one above the other with a minimum horizontal distance of 100 m between them. This method is adopted where the coal seam thickness is more than 30 m and to handle the OB bench of 60 m above the coal seam. ISN
Tandem Working of Draglines Dragline Cut Dump Area m2 (solid) D/L 10/70 is 10/70 ABCD abcd 285.0 150-200m ahead of 20/90 CDEF kmnofci 570.0 (Dig) D/L 20/90 Ijkl (R.H.) 9.6 Ebf (R.H.) ISN 1.0
Variables with Draglines•Swing and boom angle of a dragline.•Increase or decrease of bucket size (withinlimits) with consequent decrease or increase ofboom length.•Cut width and height of dragline bench.•Method of use of dragline/draglines.•More than one position of a dragline.•Adopting cast-blasting to the desired extent. ISN
Technical specifications of Dragline (24 x 96) - Boom length : 74 - 95 m - Boom angle : 30°- 38° - Bucket Capacity (nominal): 26 - 34 cu m - Dump height : 38 - 40 m - Digging depth : 44.3 - 53.4 m - Operating radius : 64.6 - 88.2 m - Walking speed : 0.24 kmph - Bearing Pressure : 0.95 kg/cm2 ISN
SPECIFICATIONS OF OC-I DRAGLINE MAKE Ranson & Rapier Bucket Capacity M3 24 Annual capacity mm3 3.31 Boom Length Mtrs 95.6 Operating Radius Mtrs 88 Dumping Height Mtrs 39.6 Base Dia Mtrs 16 Shoe Length Mtrs 17 Shoe Width Mtrs 2.8 Movement of Machine Mtrs 2.2 Weight of Machine Tonnes 2000 Total H.P H.P. 3500 ISN