Mining_Methods_UnderGround_Mining - Mining and Blasting

Mine inFraSTruCTure
underground mining infrastructure
Maximizing
recovery
The underground mine aims for
maximum economic recovery of
minerals contained in the bedrock.
The orebody is the recovered
volume containing valuable
minerals, taking ore losses and
dilution into account. The amount
of ore losses in pillars and remnants,
and the effects of waste
dilution, will largely depend on
the mining method to be applied.
Waste dilutes the ore, so miners
try to leave it in place, wherever
possible, especially when expensive
mineral dressing methods
are applied. Flotation of sulphide
ore is more expensive than magnetic
separation of iron ore. Ore
close to the surface is mined by
open pit techniques, in which the
waste rock can be separated by
selective blasting and loading,
and trucked to the waste dump
instead of entering and diluting
the ore flow into the concentra-
tor. Subsurface orebodies are exploited
by underground mining,
for which techniques are more
complex. A combination of open
pit mining and preparation for
future underground mining is
commonly used.
underground infrastructure
Mining methods used underground are
adapted to the rock conditions, and the
shape, dimensions, strength and stability
of the orebody. In order to work the
underground rock mass, infrastructure
is required for access to work places, ore
production, power supply, transport of
ore, ventilation, drainage and pumping
as well as maintenance of equipment.
Traditionally, the most common method
to transport men, material, ore and
waste is via vertical shafts. The shaft
forms the access to the various main un-
derground levels, and is the mine’s main
artery for anything going up or down.
Shaft stations, drifts and ramps connect
Ramp access for transport and haulage.
stopes with orepasses, tramming levels,
and workshops for movement of miners
and equipment.
Efficient ore handling is important.
The blasted ore is loaded from production
stopes, via orepasses to a main hau-
lage level, commonly railbound, and
thence to the crusher at the hoisting
shaft.
The crushed ore is then stored in a
silo before transfer by conveyor to the
measuring pocket at the skip station,
from where it is hoisted to the surface
stockpile. To decide on the shaft bottom
and main haulage level elevations are
crucial, as these are permanent installations
offering little or no flexibility in
the event that mining progresses below
these levels. Consequently extensive
exploration drilling has to be conducted
to identify sufficient ore reserves above
the main haulage level before final design
of the permanent installations can
progress.
There is currently a strong tendency to
avoid shaft sinking by extending ramps
from the surface successively deeper, to
depths exceeding 1,000 m. There are a
number of locations where the deeper
ore is hauled by trucks up ramps to an
existing railbound haulage system to
the main crusher, from where it can be
hoisted to the surface.
Services
Electric power is distributed throughout
the mine, and is used to illuminate work
underground mining methods 21