Settling Tanks Flashcards

1
Q

what is the basic principle that settling tanks are created on?

A

terminal settling velocity

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2
Q

where are settling tanks used?

A

mining (slurries, large amount of liquid to filter)

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3
Q

Thickener

A

desired product is settled particles at bottom

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4
Q

Clarifier

A

desired product is clear liquid off the top

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5
Q

purpose of rake in settling tank

A

to push solids towards underflow exit

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6
Q

purpose of a well in settling tanks

A

prevents solids from flowing to the sides immediately, usually (1-2 m)
Can also be where add floculants which causes particles to agglomerate
Can also be used to remove surface charges (charged particles will repel each other causing increased settling time)

*tank depth usually 3-3.5m (so large portion of tank)

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7
Q

Solid exiting concentration

A

typically less than 10 wt% (too high concentration means increased settling area, and more costs)

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8
Q

Settling assumption

A

Stokes regime (particles moving slowly)

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9
Q

Methods of estimating settling velocity

A

empirical correlations for terminal velocity

batch testing (necessary for porous or agglomerating particles as empirical estimates are not good)

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