What is an upstream tailing dam?
An upstream tailings dam consists of trapezoidal embankments being constructed on top but toe to crest of another, moving the crest further upstream. This creates a relatively flat downstream side and a jagged upstream side which is supported by tailings slurry in the impoundment.
What is the purpose of a tailings dam?
Tailings dams are used to store water and waste that come as by products from the mining process. It is estimated there are at least 3,500 tailings dams around the world.
What are the problems with tailings?
Tailings can contaminate aquatic life with toxic heavy metals and milling chemicals. Some metals, particularly mercury, may bioaccumulate up the food chain, ultimately harming humans. It causes turbidity (murkiness from suspended particles) and reduces oxygen levels which directly impacts aquatic life.
What are the causes of tailings?
The causes of mine tailings dam failure are different as each failure is always site-specific, although common themes always emerge around:
- Poor site investigation.
- Inappropriate engineering design.
- Lack of risk assessment especially consequence analysis.
- Deficient dam construction.
What is upstream and downstream of dam?
Definition of Dam is as an obstruction constructed across a stream or river. At the back of this barrier water is collected forming a pool. The side on which water is collected is called upstream side and the other side of the barrier is called downstream side.
What is upstream embankment?
Upstream raised construction
Beach refers to the surface slope of the tailings after being deposited by water from a discharge point. The beach becomes the foundation of the next embankment raise. In some applications, the embankments are mechanically placed, and the discharge is used to build the beach only.
What happens to tailings after mining is finished?
The leftover pulverized rock and liquid slurry become tailings, which often are acidic and contain high concentrations of arsenic, mercury and other toxic substances. Mining companies store tailings forever, frequently behind earth-filled embankment dams.
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. This form of waste storage poses a number of concerns, the biggest of which is safety.
Are tailings toxic?
Tailings aren’t “toxic.” They are a natural byproduct to be kept in a lined facility and returned to the pit at closure. All pyritic tailings will be backhauled to the pit for permanent underwater storage. They will present no failure risk and offer no threat to downstream habitat.
How can we reduce the impact of tailings?
Accordingly, there is increasing interest by mining companies in ways to reduce the size of their tailings ponds, develop alternatives to maintaining large ponds of water, or even eliminate them entirely. This can help them move towards the elusive goal of “walk-away closure.”
What are downstream dams?
The downstream design refers to the successive raising of the embankment that positions the fill and crest further downstream. A centerlined dam has sequential embankment dams constructed directly on top of another while fill is placed on the downstream side for support and slurry supports the upstream side.
What happens downstream of a dam?
Downstream of the dam the flow rate in the river will depend on the amount of thecompensation flow. Water volume is considerably reduced during the dry season. As a result the downstream may change to pools alternating with dry stretches for about nine months from November to June.
What is upstream and downstream in dam?
What are the two sides of a dam called?
Face – Upstream or downstream side slope of dam.
Can tailings be recycled?
By reprocessing tailings, dewatering them and then storing them in a dry stack, mines can remove some of the economic, environmental and societal risks associated with tailings stored in slurry. The water recovered can then be reused, helping to drive down abstraction and logistics costs.
Why are tailings so controversial?
Research from Canada’s environmental agency has shown that tailings ponds in the tar sands region have leached potentially deadly toxins into land and groundwater, and First Nations tribes and environmentalists have blamed those leaching chemicals from the tar sands on rare cancer clusters.
What does upstream and downstream mean?
Upstream refers to the material inputs needed for production, while downstream is the opposite end, where products get produced and distributed.
What are downstream effects?
relating to or happening at a later stage in a process. downstream effects/costs. Synonyms and related words. Late or too late.
What is upstream and downstream of a dam?
How do dams impact upstream and downstream?
Dams alter aquatic ecology and river hydrology upstream and downstream, affecting water quality, quantity and breeding grounds (Helland-Hansen et al., 1995). They create novel and artificial types of aquatic environment for the life span of the dam.
What is the difference between upstream and downstream?
What is the water behind a dam called?
Impoundment (Pool/Lake/Reservoir) – Water held back by a dam; water on the upstream side of the dam.
Are tailings valuable?
Researchers know there remains economic value in tailings. Natural Resources Canada estimated that there is $10B in total metal value in Canadian gold mining waste. Rio Tinto has produced borates from a mine in the Mojave Desert which has left behind more than 90 years’ worth of tailings.
What is the difference between upstream and downstream in water?
Stream- The water that is moving in the river is called a stream. Upstream- When the boat is flowing in the opposite direction of the stream, it is called Upstream. Downstream- When the boat is flowing in the same direction as the stream, it is called Downstream.
What is difference between upstream and downstream?
Simply put, upstream works include the exploration and production of crude oil and natural gas, whilst downstream refers to the processes applied after extraction through to it being delivered to the customer in whatever format required.