Underground Mining

Front 1

How do you access underground ore?

Back 1

1: Make DECLINES: spiral tunnels circling around the deposit
2: Sink SHAFTS: vertical excavations adjacent to the ore body, best location would be in the footwall
If the ore body is horizontal in nature, make Adits, excavations in the side of a hill or mountain.

Front 2

What are the 2 principle phases of UG mining?

Back 2

DEVELOPMENTAL MINING: removing waste rock, unstable rocks, stabilizing foundations to gain access to ore body

PRODUCTION MINING:
-Short hole: excavation of ore
-long hole: requires two excavations within the ore at different elevations below the surface. holes are drilled between the excavations and loaded with explosives. holes are blasted and ore is removed from the bottom excavation.

Front 3

What are some features of UG mining that distinguishes it from OP mining?

Back 3

Ventilation and Ground support

Front 4

What are two types of ground support?

Back 4

Area Support: prevention of major ground failure. holes are drilled into the ceiling and walls and long steel rod is installed to hold the ground together

Local ground support- prevention of rocks from falling from the backs and walls using shortcrete, latex membranes, or welded wire mesh.

Front 5

Describe unsupported/bulk mining methods, and list different types of this method.

Back 5

The stope remains OPEN for the duration of active production. The host rock must be SUPPORTING.
-Room and pillar
-Shrinkage Stoping
-Blasthole Stoping (Sublevel)
-Vertical Retreat mining ( sublevel )
-Ring Drilling ( sublevel )

Front 6

Describe Supported mining methods, and list some different types.

Back 6

This requires active support/backfill to maintain stability, the host rock is not supporting, this provides great ore stability.
-Cut and fill mining
-sublevel caving
-block caving

Front 7

Describe Room and pillar mining

Back 7

mined material is extracted across a horizontal place leaving "pillars" of untouched material to support the roof
overburden leaving rooms underground. good for flat-lying deposits or gently dipping bedded orebodies

Front 8

Describe Shrinkage Stoping

Back 8

-entry method
-short hole mining methods for steeply dipping ore bodies. similar to cut and fill, but after blasting, the broken
ore is left in the stope where it is used to support the surrounding rock. only enough ore is removed from the
stope to allow drilling/blasting the next slice. stope is emptied when all of the ore has been blasted.

Front 9

Describe the Blasthole Stoping

Back 9

Blast hole: -non-entry method
-blastholes may be parallel/ring-drilled
-used when the drip of a deposit is steep (> 55 degrees)
-drift is driven along the bottom of the orebody
-vertical slot is created at an open end of the stope
-radial pattern of drill holes are drilled in the sub levels of the stope which are then loaded with explosives==>
blasted ore

Front 10

Describe Vertical Retreat Mining

Back 10

-non entry method
-blastholes are parallel. ore is blasted in horizontal slices retreating upward

Front 11

Describe Ring Drilling

Back 11

-ore is drilled from one or more sub levels using long hole drills
-ore is blasted in vertical slices called rings. stope is left open.

Front 12

Describe Cut and Fill Mining

Back 12

-short hole mining used in steeply dipping/irregular ore zones
-ore is mine in horizontal/near-horizontal slices upward. ore is completely extracted from the stope.
-the space then filled with waste rock/tailings, which is consolidated with concrete.
-expensive, but selective method with low ore loss and dilution (good recovery)

Front 13

Describe block Caving

Back 13

-used for large deposits that are capable. Ore must fracture to manageable size.
-orebody is sleep or with a large vertical extend
-expensive development but low operational costs
-undercut with haulage access is driven under the orebody. "draw bells" is where caving rocks fall into and is
located between the top of haulage level and bottom of the undercut. orebody is drilled and blasted above the
undercut and is removed via the haulage access.

Front 14

How is ore removed from the underground mine?

Back 14

-ore is removed from the stope using LHD (Load, Haul, Dump) trucks
-ore is dumped into a truck to be hauled to the surface (shallow mines). OR ore is dumped down an ore pass (i.e.
vertical excavation) and it falls to a collection level (deep mines).
-2 scenarios:
1.At collection level, primary crushing using cone crusher might occur. ore is moved by conveyor belts/trucks to the
shaft to be brought to the surface in buckets and emptied into bins beneath the surface head frame. This will be
transported to the mill.
2.OR underground primary crusher brings ore to inclined convertor belt delivering it to an inclined shaft directed to
the surface.

Front 15

What are some of the things you have to consider before doing an UG mine?

Back 15

-proximity of other orebodies
-safety
-DIP of deposit
-shape
-Grade (i.e. whether selective mining should be used<- for high grade)