Sustainable inland and offshore aggregate production requires modern dredging equipment
Type:
Presented during:
CEDA Dredging Days 2007 - The Day After we Stop Dredging, Rotterdam
Authors:
van Muijen H, von Allwörden and de Boer T, MTI Holland, The Netherlands
Abstract: World wide, the aggregate industry is one of the most important primary raw material activities. Not only in volumes, but certainly also in market values. Our modern society can not do without the use of aggregates. Prime sources for aggregates are quarries, but dredging sand and gravel gains more and more importance. A lot of sand is dredged for land reclamation and beach nourishment, but huge volumes are also required for filling sand, as industrial sands for concrete production and for masonry purposes, as glass sand and industrial minerals. Gravel is used for road construction, in asphalt, for concrete production as well as for decoration purposes.
Sand and gravel is a typical bulk product. Large volumes have to be handled and transportation costs form an important part of the total cost price. Dry operations with relatively low capacities have a disadvantage in this respect. Dredge operations favor large unit operations with low unit costs and often transportation over water is
possible which reduces the costs even more. Whenever dredging is possible, it often presents by far the cheapest way of winning and moving bulk materials. This is not only true for the large reclamation projects using jumbo trailing suction hopper dredgers, but also applies for other aggregate products.
Another important aspect of aggregate production is the relation between market price and product quality. In general a higher quality allows a higher market price, which in its turn allows for a longer transportation distance, thereby generating a larger market area potential. However, deposit quality, operational restrictions and processing possibilities play an important role as well.
We can make a distinction between inland and offshore application of aggregate dredging equipment. Land based operations are mostly executed by stationary dredges like grab dredgers, plain suction dredgers, cutter and wheel dredgers. For marine based deposits specially adapted trailing suction hopper dredgers are deployed. In some cases, deposit conditions require the use of other type of dredging equipment like bucketladder dredgers.
All types of dredging methods have their own constraints. Besides operational considerations, governmental regulations, market demands and environmental impact have to be taken into account. Sustainable extraction of aggregates is a necessity nowadays which should be balanced with feasible ways of operation.
This paper will review typical inland and offshore aggregate dredging operations and show that a sustainable way of production requires modern dredging technology.
Keywords: aggregate dredging, sand, gravel, sustainable dredging, inland aggregate winning, offshore aggregate winning