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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Boxhole equipment.<br />
Mine requirements<br />
BOxHOle BOring aT el TenienTe<br />
El Teniente tendered for the purchase of<br />
two boxhole boring units to excavate<br />
the draw bell slot holes for the panel ca-<br />
ving operation. These units would also<br />
be used to bore ventilation raises <strong>and</strong><br />
ore passes between the production <strong>and</strong><br />
the haulage level. The vertical draw bell<br />
slots are generally 15 m-long <strong>and</strong> 692<br />
mm-diameter. A total of 800 m, comprising<br />
45-50 shafts, are bored annually.<br />
Because drifts have not been deve-<br />
loped on the production level, all venti-<br />
lation raises <strong>and</strong> ore passes are bored<br />
from the haulage level <strong>and</strong> upwards<br />
using the boxhole boring technique. The<br />
average length of the vertical <strong>and</strong> in-<br />
clined ventilation raises is 25-50 m. The<br />
inclined ore passes average 25 m-long,<br />
but this varies up to 75 m-long. The total<br />
annual requirement for 1.5 m-diameter<br />
bored raises is 1,000 m.<br />
Restrictions are placed on the machine<br />
design by the size of the underground<br />
sections. Work sites measure<br />
3.6 x 3.6 m, <strong>and</strong> maximum transportation<br />
dimensions are 2.5 m-wide x 2.5 mhigh<br />
x 4.8 m-long. The machines must<br />
either be self-propelled or transported<br />
on rail, <strong>and</strong> have to have tramming <strong>and</strong><br />
directional lights, as well as a fire extinguisher<br />
system. The mine electrical in-<br />
stallations provide power at 575-4,000<br />
V, 3-phases at 50 Hz, <strong>and</strong> 24-220 V, sin-<br />
gle phase at 50 Hz. Each machine is de-<br />
signed for three, or less, operators per<br />
shift.<br />
The operating environment is 2,300 m<br />
above sea level, with teperatures from<br />
+25 degrees C to 0 degrees C. Relative<br />
humidity varies from 15% to 90% in<br />
the mine, where acid water <strong>and</strong> occa-<br />
sional blast vibrations may be experi-<br />
enced. Both machines are operated 24<br />
h/day, 7 days/week, with a maximum<br />
machine utilization of 15-16 h/day.<br />
evaluation period<br />
An evaluation period of three months<br />
was established to study the performance<br />
capabilities of each machine. Target per-<br />
formance criteria for the smaller slot<br />
hole machine was set at 264 m bored<br />
during the three month period, <strong>and</strong> 330<br />
m for the larger boxhole machine.<br />
This performance target was based<br />
on a 24 h/day operation, with net av-<br />
ailable operating time of 15-16 h. The<br />
number of operating personnel required,<br />
set-up <strong>and</strong> moving time, the rate of pe-<br />
netration <strong>and</strong> machine availability were<br />
all recorded during evaluation period.<br />
Atlas Copco boxhole boring units<br />
Robbins 34RH <strong>and</strong> 53RH were found<br />
to meet the requirements of the up-hole<br />
boring tender, <strong>and</strong> were selected by the<br />
mine. Built on the experience of the<br />
52R, the 53RH multi-purpose machine<br />
has been developed since the early<br />
1980s. The 34RH has been used as a<br />
raiseboring <strong>and</strong> downreaming machine<br />
for a similar period, <strong>and</strong> was first introduced<br />
in the boxhole configuration in<br />
1998. To accommodate the restricted<br />
working space in the mine, the already<br />
low-profile 34RH <strong>and</strong> 53RH had to be<br />
redesigned to further decrease the working<br />
height. Both machines are selfpropelled,<br />
<strong>and</strong> equipped with efficient<br />
muck collectors, remote-controlled pipe<br />
h<strong>and</strong>ling <strong>and</strong> automatic data logging.<br />
atlas Copco robbins 34rH<br />
The Robbins 34RH is a low profile,<br />
small diameter raise drill, designed for<br />
applications such as slot raises, backfills<br />
<strong>and</strong> narrow-vein mining. This multi-<br />
purpose, lightweight raise drill can be<br />
used for downreaming <strong>and</strong> upward<br />
boxhole boring, as well as for conventional<br />
raise boring.<br />
The machine features a variable<br />
speed hydraulic drive with a two stage<br />
planetary gearbox, <strong>and</strong> hollow-centre<br />
shaft to enable pilot-hole flushing. To<br />
change boring methods, the Robbins<br />
34RH is easily turned upside down, to<br />
orient the drive head into either upward<br />
or downward boring position.<br />
The Robbins 34RH was already a<br />
true low-profile raise drill. However, to<br />
accommodate the restricted site dimensions,<br />
<strong>and</strong> to allow room for a muckh<strong>and</strong>ling<br />
system on top of the machine,<br />
the maximum working height had to<br />
be lowered further. This was achieved<br />
through the use of shorter high-thrust<br />
telescopic cylinders, <strong>and</strong> by utilizing<br />
750 mm-long by 254 mm-diameter drill<br />
rods.<br />
This reduced the working height of<br />
the assembly to 3.6 m, including the<br />
muck h<strong>and</strong>ling system.<br />
The new muck h<strong>and</strong>ling arrange-<br />
ment, which had been fitted on two ear-<br />
lier Robbins 34RH machines commis-<br />
sioned in 1998 <strong>and</strong> 1999, has been<br />
further developed for efficient muck<br />
collection in the boxhole boring mode.<br />
The remote controlled <strong>and</strong> hydraulically<br />
operated muck collector is fully<br />
integrated into the derrick assembly, <strong>and</strong><br />
remains on the machine, even during<br />
transportation.<br />
92 underground mining methods