What is deep sea tailings placement?
Metal ore mining produces large amounts of waste rock and mine tailings. Mine tailings are the wastes produced after extracting the desired metal from the ore. This special case is referred to as Deep Sea Tailings Placement (DSTP) in which the tailings deposition is sufficiently deep as to be below the euphotic zone.
Is deposition of mine tailings?
6.5 Tailings Impoundments. Mine tailings are the finely ground residue from ore extraction. The method of deposition affects the distribution of tailings particles within the impoundment.
Why do companies dump their tailings into the ocean?
Acid Mine Drainage can have a toxic impact on ground and surface water around mines. Mining companies also argue that marine life at these depths is not so abundant and it is not important to the human food chain. By pumping their tailings into the sea, mining companies remove unsightly tailings on land.
How tailings are formed?
Tailings consist of ground rock and process effluents that are generated in a mine processing plant. Mechanical and chemical processes are used to extract the desired product from the run of the mine ore and produce a waste stream known as tailings. The challenges associated with tailings storage are ever increasing.
How are tailings disposed of?
The traditional means of tailings disposal is typically an impound method, often stored in a constructed dam in diluted form. Additionally, tailings dams occupy vast landmass, require large quantities of water to dilute the tailings for storage, and often have a limited capacity.
Why is deep sea mining bad?
The scraping of the ocean floor by machines can alter or destroy deep-sea habitats, leading to the loss of species and fragmentation or loss of ecosystem structure and function. This is one of the biggest potential impacts from deep-sea mining.
Why is deep sea mining important?
Why are there such valuable materials in the deep ocean? Natural hydrothermal geysers on the deep ocean floor regularly vent rich concentrations of metals and minerals from the earth’s core, forming valuable seams on the ocean floor that can yield up to 10 times the precious metals as in comparable land-based mining.
What is the purpose of tailings?
Tailings are the waste products from mining. Mechanical and chemical processes are used to grind up rock into a fine sand to extract the valuable mineral or metal from the rock ore. All the unrecoverable and uneconomic remnants from this process are waste.
Where do tailings settle in the deep sea?
‘Deep’ STP should be distinguished by the discharge of tailings slurry into deeper waters, – well below the mixed layer and the reach of sunlight in the water column (the so-called ‘euphotic zone’), with tailings settling below a depth of 1000m or more.
How does single point deposition work on tailings?
Single point deposition can place the tailings in fairly thick layers causing the tailings to remain saturated for years if not dried before new layers are deposited (Norman 1998).
Where do tailings go in a water body?
Ideally the tailings need to be deposited under the euphotic zone, which is the upper layer of a water body where photosynthesis and reproduction of marine plants occur, and below the surface mixed layer, which is the zone of turbulence caused by the wind and waves (MMSD 2002).
What are the objectives of offshore tailings disposal?
One objective of offshore disposal is to place tailings where ambient dissolved oxygen levels are minimal to prevent oxidation and mobilisation of contaminants (Norman 1998). This type of tailings disposal technique also reduces engineering requirements and reduces or prevents the tailings storage footprint onshore (EC 2004).