Mining Tailings Flashcards
how long are tailings storage facilities designed for
eternity or (10 000 years)
How are tailings risk levels usually qunatified
by the number of fatalities the risk will cause
Is upstream method stable
no it has the highest likelihood for collapse
What are other disposal methods of mine waste
*co disposal (where overburden is mixed in)
*filtered where the solids content is 85% and water is removed from tailings
*paste that is thickened tailings
How many TSF on average fail per year
2
How many reported TSF failures have occured in Australia and where
3
Captains Flat x 2 (1939 and 1942)
Cadia Mine
(both NSW)
What does effective stress control with tailings
It controls the tailings strength and controls the particle contact forces which strength comes from.
It also controls how much skeleton deformation occurs
Study the stress strain graphs
pending
What occurs with liquification
it occurs at 0 effective stress giving 0 strength.
It can occur though heavy machinery causing a rise in sigma 1.
How do you limit liquification
control the water if the water level rises there are issues (for examples when drains block up)
You want to keep the surface dry and the water is the killer for tailings dams
What dose sand tailings offer in embankments
it can keep critcal water levels low as sand provides drainage
What happens with the mechanics to cause liquification
Sand above slimes distorts laterally and when this happens under undrained loading a pore pressure where the build up occurs reducing the effective stress to near zero causing liquification
What tailings can liquify
most tailings
Most common - saturated, undrained and compressible soil
Less common - nearly saturated and drained with medium density
Rare - dry or moist that is very dense with altered stress behaviour
