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