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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Ore left in stope<br />
Drawpoints<br />
or chutes<br />
STeeP <strong>Mining</strong><br />
Sublevel drifts are located within the<br />
orebody, between the main levels, for<br />
longhole drilling of blast patterns. The<br />
drill pattern accurately specifies where<br />
the blastholes are collared, <strong>and</strong> the depth<br />
<strong>and</strong> angle of each hole.<br />
VCR primary stoping.<br />
Transport drift<br />
Shrinkage stoping layout.<br />
Crater<br />
blasting<br />
charges<br />
Drill<br />
overcut<br />
Primary<br />
stope no1<br />
in production<br />
Raise<br />
Cross cut for loading<br />
Drawpoints are located below the<br />
stope to enable safe mucking by LHD<br />
machines, which may tip into an adjacent<br />
orepass, or into trucks or rail cars.<br />
The trough-shaped stope bottom is ty-<br />
pical, with loading drifts at regular<br />
Loading draw<br />
points<br />
Primary stope no2<br />
undercut <strong>and</strong> drilling<br />
done<br />
Timbered manway<br />
(also ventilation)<br />
intervals. Nowadays, the loading level<br />
can be integrated with the undercut, <strong>and</strong><br />
mucking out performed by a remote<br />
control LHD working in the open stope.<br />
This will reduce the amount of drift<br />
development in waste rock.<br />
Sublevel stoping requires a straightforward<br />
shape of stopes <strong>and</strong> ore boundaries,<br />
within which only ore is drilled.<br />
In larger orebodies, modules of ore may<br />
be mined along strike, as primary <strong>and</strong><br />
secondary stopes.<br />
Bighole stoping<br />
Bighole stoping is an up-scaled variant<br />
of sublevel open stoping, using longer,<br />
larger-diameter DTH blastholes, ranging<br />
from 140 to 165 mm. Blast patterns<br />
are similar to SLOS, but with holes up<br />
to 100 m-long. A pattern with 140 mm<br />
blastholes will break a rock slice 4 m-<br />
thick, with 6 m toe spacing. DTH drilling<br />
is more accurate than tophammer<br />
drilling, allowing the vertical spacing<br />
between sublevels to be extended, from<br />
40 m with SLOS mining, to 60 m with<br />
bighole stoping. However, the risk of<br />
damage to the rock structures has to be<br />
taken into account by the mine planners,<br />
as the larger holes contain more<br />
explosives.<br />
Shrinkage stoping<br />
In shrinkage stoping, traditionally a<br />
common mining method, ore is excavated<br />
in horizontal slices, starting from the<br />
stope bottom <strong>and</strong> advancing upwards.<br />
Part of the blasted ore is left in the stope,<br />
to serve as a working platform, <strong>and</strong> to<br />
give support to the stope walls.<br />
<strong>Blasting</strong> swells the ore by about 50%,<br />
which means that a substantial amount<br />
has to be left in the stope until mining<br />
has reached the top section, following<br />
which final extraction can take place.<br />
Shrinkage stoping can be used for ore-<br />
bodies with: steep dips; comparatively<br />
stable ore <strong>and</strong> sidewall characteristics;<br />
regular ore boundaries; <strong>and</strong> ore unaf-<br />
fected by storage (some sulphide ores<br />
oxidize, generating excessive heat).<br />
The development consists of: haulage<br />
drift <strong>and</strong> crosscuts for mucking at stope<br />
bottom; establishment of drawpoints <strong>and</strong><br />
undercut; <strong>and</strong> a raise from the haulage<br />
level passing through the undercut to the<br />
34 underground mining methods