Dragline excavation systems are heavy equipment used in civil engineering and surface mining. Engineering vehicles, known by the other terms construction Equipment, earth movers heavy equipment or just plain equipment are machines specifically designed to execute Civil engineering is a professional engineering discipline that deals with the design construction and maintenance of the physical and naturally built Mining is the extraction of valuable Minerals or other geological materials from the earth usually (but not always from an Ore body In civil engineering the smaller types are used for road and port construction. Civil engineering is a professional engineering discipline that deals with the design construction and maintenance of the physical and naturally built A road is an identifiable route, way or path between two or more places. The larger types are used in strip-mining operations to move overburden above coal, and for tar-sand mining. Surface mining is a type of Mining in which soil and rock overlying the mineral deposit are removed Overburden is the term used in Mining to describe material that lies above the area of economic interest e Draglines are amongst the largest mobile equipment (not water-borne), and weigh in the vicinity of 2000 metric tonnes, though specimens weighing up to 13,000 metric tonnes have also been constructed. This article is about the tonne or metric ton For other tons see Ton.
A dragline bucket system consists of a large bucket which is suspended from a boom (a large truss-like structure) with wire ropes. In Architecture and Structural engineering, a truss is a structure comprising one or more triangular units constructed with straight slender members whose Wire rope consists of several strands laid (or 'twisted' together like a helix The bucket is maneuvered by means of a number of ropes and chains. The hoistrope, powered by large diesel or electric motors, supports the bucket and hoist-coupler assembly from the boom. Diesel or Diesel fuel (ˈdiːzəl in general is any Fuel used in Diesel engines The most common is a specific fractional distillate of petroleum An electric motor uses Electrical energy to produce Mechanical energy. The dragrope is used to draw the bucket assembly horizontally. By skillful maneuver of the hoist and the dragropes the bucket is controlled for various operations. A schematic of a large dragline bucket system is shown below.
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Operation
In a typical cycle of excavation, the bucket is positioned above the material to be excavated. The bucket is then lowered and the dragrope is then drawn so that 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 to the place where the material is to be dumped. The dragrope is then released causing the bucket to tilt and empty. This is called a dump operation.
The bucket can also be 'thrown' by winding up to the jib and then releasing a clutch on the drag cable. This would then swing the bucket like a pendulum. Once the bucket had passed the vertical, the hoist cable would be released thus throwing the bucket. On smaller draglines, a skilled operator could make the bucket land about one-half the length of the jib further away than if it had just been dropped. On larger draglines, only a few extra metres may be reached.
Draglines in mining
A large dragline system used in the open pit mining industry costs approximately US$50-100 million. Dragline excavation systems are Heavy equipment used in Civil engineering and surface Mining. Open-pit mining, also known as opencast mining and open-cut mining and strip mining, refers to a method of extracting rock or Minerals The United States dollar ( sign: $; code: USD) is the unit of Currency of the United States; it has also been A typical bucket has a volume ranging from 30 to 60 cubic metres, though extremely large buckets have ranged up to 168 cubic metres. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International [1] The length of the boom ranges from 45 to 100 metres. In a single cycle it can move up to 450 metric tonnes of material.
Most mining draglines are not fuel powered like most other mining equipment. Fuel is any material that is burned or altered in order to obtain energy Their power consumption is so great that they have a direct connection to the high-voltage grid at voltages of between 6. The term high voltage characterizes electrical circuits in which the voltage used is the cause of particular safety concerns and insulation requirements 6 to 22 kV. A typical dragline, with a 55 cubic metre bucket, can use up to 6 megawatts during normal digging operations. Because of this, many (possibly apocryphal) stories have been told about the blackout-causing effects of mining draglines. For instance, there is a long-lived story that, back in the 1970s, if all seven of the Peak Downs (a very large coal mine in central Queensland, Australia) draglines turned simultaneously, they would black out all of North Queensland. This article is about the Decade 1970-1979 For the Year 1970 see 1970. Shire of Peak Downs is a Local Government Area located in the Central Highlands of Queensland, Australia, 320km west of both Rockhampton and Queensland is a state of Australia, occupying the north-eastern corner of the mainland continent For a topic outline on this subject see List of basic Australia topics. A power outage (also known as power cut, power failure, power loss, or blackout) is the loss of the Electricity supply to an
In all but the smallest of draglines, movement is accomplished by "walking" using feet or pontoons, as caterpillar tracks place too much pressure on the ground, and have great difficultly under the immense weight of the dragline. A pontoon is a flat-bottomed Boat or the floats used to support a structure on water Continuous tracks are large (modular tracks used on the so-called caterpillar Tanks construction equipment and certain other off-road vehicles Maximum speed is only at most a few hundred metres per hour since the feet must be repositioned for each step. If travelling medium distances, (about 30-100 km), a special dragline carrier can be brought in to transport the dragline. Above this distance, disassembly is generally required.
Researchers at CSIRO in Australia have a long-term research project into automating draglines and have moved over 250,000 tonnes of overburden under computer control. The Commonwealth Scientific and Industrial Research Organisation ( CSIRO) is the national government body for scientific research in Australia.
Limitations
The primary limitations of draglines are their boom height and boom length, which limits where the dragline can dump the waste material. Another primary limitation is their dig depth, which is limited by the length of rope the dragline can utilize. Inherent with their construction, a dragline is most efficient excavating material below the level of their base. While a dragline can dig above itself, it does so inefficiently and is not suitable to load piled up material (like a rope shovel can). A steam shovel is a large steam-powered excavating machine designed for lifting and moving material such as rock and Soil.
Despite their limitations, and their extremely high capital cost, draglines remain popular with many mines, due to their reliability, and extremely low waste removal cost.
Draglines have different cutting sequences. The first is the side cast method using offset benches; this involves throwing the overburden sideways onto blasted material to make a bench. The second is a key pass. This pass cuts a key at the toe of the new highwall and also shifts the bench further towards the low-wall. This may also require a chop pass if the wall is blocky. A chop pass involves the bucket being dropped down onto an angled highwall to scale the surface. The next sequence is the slowest operation, the blocks pass. However, this pass moves most of the material. It involves using the key to access to bottom of the material to lift it up to spoil or to an elevated bench level. The final cut if required is a pull back, pulling material back further to the low-wall side.
Examples
The British firm of Ransomes & Rapier produced a few large (1400-1800 ton) excavators, the largest in Europe at the time. Ransomes Sims and Jeffries Engineers of Ipswich were a major British agricultural machinery maker Power was from internal combustion engines driving generators. One, named SUNDEW, was used in a quarry from 1957 to 1974. Sundew was a large electrically powered Dragline excavator used in mining operations in Rutland and Northamptonshire in the United Kingdom After its working life at the first site in Rutland was finished it walked 13 miles to a new life at Corby; the walk took 9 weeks. Rutland is a county of mainland England, bounded on the west and north by Leicestershire, northeast by Lincolnshire, and southeast by Corby is an industrial town and a local government district located 13km north of Kettering in Northamptonshire, England.
Smaller draglines were also commonly used before hydraulic machines become widespread. Firms such as Ruston and Bucyrus made models such as the RB10 which were popular for small building works and drainage work. Ruston was an industrial equipment manufacturer in Lincoln, England, the company's history going back to 1840 Bucyrus International Inc is a manufacturer of heavy mining equipment Several of these can still be seen in the English Fens of Cambridgeshire, Lincolnshire and parts of Norfolk. The Fens, also known as the Fenland, is a geographic area in eastern England, in the United Kingdom. History Cambridgeshire is noted as the site of some of the earliest known Neolithic permanent settlement in the United Kingdom, along with sites at Fengate Lincolnshire (abbreviated Lincs) is a county in the east of England. Norfolk (ˈnɔrfək is a low-lying county in East Anglia, England, United Kingdom. Ruston's are a company also associated with drainage pumping engines.
The coal mining dragline known as Big Muskie, owned by the Central Ohio Coal Company (a division of American Electric Power), was the world's largest mobile earth-moving machine, weighing nearly 13,000 metric tons and standing nearly 22 stories tall. Big Muskie was a Coal mining Bucyrus-Erie Dragline owned by the Central Ohio Coal Company (a division of American Electric Power) American Electric Power ( is a major investor-owner Electric utility in various parts of the United States. [2] It operated in Guernsey County, in the U. Guernsey County is a County located in the state of Ohio. As of 2000 the population was 40792 S. state of Ohio from 1969 to 1991, and was powered by 13,800 volts of electricity. Ohio ( is a Midwestern state of the United States. As part of the Great Lakes region, Ohio has long been a cultural and geographical crossroads It was dismantled in 1999. [3]
History
The dragline was invented in 1904 by John W. Page of Page Schnable Contracting for use digging the Chicago Canal. The Chicago Sanitary and Ship Canal, historically known as the Chicago Drainage Canal, is the only shipping link between the Great Lakes (specifically Lake In 1912 it became the Page Engineering Company, and a walking mechanism was developed a few years later, providing draglines with mobility. Page also invented the arched dragline bucket, a design still commonly used today by draglines from many other manufacturers, and in the 1960s pioneered an archless bucket design.
In 1910 Bucyrus entered the dragline market with the purchase of manufacturing rights for the Heyworth-Newman dragline excavator. Their "Class 14" dragline was introduced in 1911 as the first crawler mounted dragline. In 1912 Bucyrus helped pioneer the use of electricity as a power source for large stripping shovels and draglines used in mining.
In 1914 Harnischfeger Corporation, (established as PH Mining in 1884 by Alonzo Pawling and Henry Harnischfeger), introduced the world’s first gasoline engine-powered dragline. An Italian company, Fiorentini, produced dragline excavators from 1919 licensed by Bucyrus. The Fiorentini are a noble Italian family from the Valsugana.
In 1939 the Marion Steam Shovel Dredge Company (established in 1880) built its first walking dragline. The company changed its name to the Marion Power Shovel Company in 1946 and was acquired by Bucyrus in 1997. In 1988 Page was acquired by the Harnischfeger Co. , makers of the PH line of shovels, draglines, and cranes. A Power shovel (also called a Stripping or Front Shovel in some markets is a bucket equipped machine usually electrically powered used for digging and loading earth or fragmented A crane is a lifting machine equipped with a Winder, Wire ropes or Chains and sheaves that can be used both to lift and lower materials and to
Simulation software
Since draglines are typically large, complicated and very expensive, training new operators can be a tricky process. In the same way that flight simulators have developed to train pilots, mining simulator software has been developed to assist new operators in learning how to control the machines. A flight simulator is a system that tries to copy or simulate, the experience of flying an aircraft A mining simulator is a system used to replicate elements of Mining operations for Training or efficiency analysis
References
- K. Pathak, K. Dasgupta, A. Chattopadhyay, "Determination of the working zone of a dragline bucket - A graphical approach", Doncaster, The Institution of mining engineers, 1992.
- Peter Ridley, Peter Corke, "Calculation of Dragline bucket pose under gravity loading", Mechanism and machine theory, Vol. 35, 2000.
See also
- Big Muskie
- Marion Power Shovel
- Steam Shovel
- Bucket wheel excavator
- Electric shovel
- Bucyrus International – Manufacturer of draglines
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