Dredger
A dredger , also known as a floating dredger , is a water construction vehicle that has special equipment for dredging harbors, estuaries, sea bays or the like. As is often the case in shipping, the English expression dredger is common .
background
A distinction is made between production dredging such as the Elbe deepening and the constantly required maintenance dredging. This dredging is repeatedly necessary in the estuaries of many rivers , as these waters deposit sediments that lead to shoals that can impair shipping .
Also for the extraction of bulk raw materials , e.g. B. in gravel and sand works , floating dredgers are used when the drainage of the mining area is not possible ( quarry pond ). The extraction of mineral resources (metals / ores, minerals, gemstones, ...) from soap deposits , e.g. B. with gold excavators .
Another possible use is the extraction of sand from the seabed for the purpose of flushing, that is, in the context of land reclamation for airports or building areas or for the creation of ports.
Dredging process and operation
In the dredging industry , a distinction is made between bucket chain dredgers , cutting head and cutting wheel suction dredgers and suction dredgers , as well as rope or hydraulic dredgers with grab shovels anchored on ships or non-powered barges or pontoons for smaller jobs. The suction excavators have largely replaced the bucket chain excavators due to their high performance, simpler technology and better work results. Nowadays, bucket chain excavators are only used in special situations, such as loosening very solid types of soil such as marl, and primarily on rivers, canals and in ports. In the case of suction excavators, a distinction is made between cutter excavators and hopper excavators . Modern dredgers are equipped with powerful suction and pumping systems, such as the Vasco da Gama . They can convey the dredged material in various ways and usually have their own cargo holds or are accompanied by barges (often collapsible barges ) that transport the dredged material to its destination.
Around 1200 dredgers are in use worldwide. They are divided (roughly) into 40% hopper excavators, 30% cutting head and cutting wheel suction excavators, 20% backhoe excavators and the remaining types account for around 10%.
If the dredged material is heavily polluted by human activity such as industry, agriculture and sewer systems, it cannot be dumped in open waters , but is cleaned, for example in Hamburg or in specially built disposal basins (for example off the Dutch coast off Rotterdam ) or at Land deposited. Rinsing fields are set up on land , in particular for suction dredging operations close to the coast , onto which the suctioned sand-water suspension is washed via pipelines. The dredged material has also often been used in dike construction in sand pit oaks or to raise port areas.
Operating companies
Dredging ships are used, among others, by the company Royal Boskalis Westminster , which operates around 300 dredging ships worldwide and whose main competitors are the Belgian Dredging International NV and the Dutch company Van Oord as well as Volker Stevin Marine Contracting (VSMC) and the Luxembourgish Jan de Nul Group (with Dutch Roots) are to be counted.
See also
When it comes to deepening the fairway of a flowing body of water in which loose sediments have settled, water injection devices are used to stir up the sediments so that they are carried on by the current.
Web links
Individual evidence
- ↑ Different Types of Dredgers Used in the Maritime Industry. In: Marine Insight. July 29, 2019, Retrieved August 31, 2019 (American English).
- ↑ dredging-in-germany.de ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
