6
The DPM percent reduction, as measured by both the
APS and NanoScan, ranges from approximately 88% in the
center to less than 10% on the edges. However, a large area
under the DCAC provides protection of greater than 50%.
This is an important factor since underground blasters will
be moving around under the canopy as they are loading
the face.
For each instrument used to measure DPM in these
experiments, the results were similar with all showing per-
cent reductions above 80% in the center of the DCAC.
Thus, when using the DCAC and conservatively assuming
an 80% reduction, an underground blaster could work in
DPM concentrations as high as 800 μg/m3 and still not
exceed the PEL of 160 μg/m3.
Additional research in working mines is necessary
to confirm the reductions measured in this laboratory
study and to better understand the miners’ movements
while completing their tasks. For instance, in an ANFO
loader operating in an underground mine, two plenums
would need to be attached side by side on the canopy of
the ANFO loader to cover the whole area of the ANFO
platform/basket. Each plenum would use its own blower
(rated at 1,800 cfm) and operate independently. Because
the reduction in exposure is dependent on the area under
the DCAC where the miner is positioned, field-based mea-
surement results may differ from these lab-based results.
However, the results reported here show the potential of
this control technology for significantly reducing exposure
of underground blasters to DPM. Figure 7. Averaged Airtec data collected in the center of the
DCAC
Figure 8. Heatmap showing average particle number reduction over the three tests
using the NanoScan across the operating DCAC
The DPM percent reduction, as measured by both the
APS and NanoScan, ranges from approximately 88% in the
center to less than 10% on the edges. However, a large area
under the DCAC provides protection of greater than 50%.
This is an important factor since underground blasters will
be moving around under the canopy as they are loading
the face.
For each instrument used to measure DPM in these
experiments, the results were similar with all showing per-
cent reductions above 80% in the center of the DCAC.
Thus, when using the DCAC and conservatively assuming
an 80% reduction, an underground blaster could work in
DPM concentrations as high as 800 μg/m3 and still not
exceed the PEL of 160 μg/m3.
Additional research in working mines is necessary
to confirm the reductions measured in this laboratory
study and to better understand the miners’ movements
while completing their tasks. For instance, in an ANFO
loader operating in an underground mine, two plenums
would need to be attached side by side on the canopy of
the ANFO loader to cover the whole area of the ANFO
platform/basket. Each plenum would use its own blower
(rated at 1,800 cfm) and operate independently. Because
the reduction in exposure is dependent on the area under
the DCAC where the miner is positioned, field-based mea-
surement results may differ from these lab-based results.
However, the results reported here show the potential of
this control technology for significantly reducing exposure
of underground blasters to DPM. Figure 7. Averaged Airtec data collected in the center of the
DCAC
Figure 8. Heatmap showing average particle number reduction over the three tests
using the NanoScan across the operating DCAC