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Respirable Dust Control 147

10.4.5 Remote Operation

This has become feasible and is an excellent tool in reducing longwall shearer opera-
tor’s dust exposure. Remote operation allows the shearer operator to stay in the intake
air away from much higher dust concentrations downstream from the shearer.

10.5 Dust Control for Roof Bolters

Roof bolters are an essential part of mining operation. It is a drilling rig that can drill
5e10-ft-deep boreholes in the roof for the installation of a steel bolt that strengthens
the roof and prevents roof fall. Because it drills into the roof that is mostly shale or
sandstone, it creates a dust cloud that is high in silica concentration. Control of the
dust at this location is very important.

10.5.1 Wet Drilling

Drilling the roof with a small quantity of water reduces dust generation considerably.
As high as 95% reduction has been obtained on certain drill rigs [13]. Typically, less
than 1 gpm of water (often mixed with a surfactant) is used for this purpose. The
collection efficiency appears to increase as the water flow is increased from 0.25 to
1 gpm [9]. Besides keeping the dust down, wet drilling also prolongs the life of the
drill bits by keeping them cool and hence sharp. It is highly recommended even if it
may be difficult to do in some situations.

10.5.2 Dust Collection Systems
Almost all roof bolters use a dust collection system. It is mostly a dry collection sys-
tem. An enclosure is created around the borehole being drilled, which is hooked to a
fan and a filtration system. The negative pressure created by the fan helps contain the
dust within the enclosure. The filtration system collects most of the dust, and clean air
is exhausted to the mine atmosphere.

10.6 Personal Protective Equipment

In many countries, approved respiratory protection equipment is required for those
working in an area where the respirable dust concentration exceeds the statutory limit.
They are basically a filtration system that cleans the air to be inhaled or they provide
filtered air with a positive pressure to the mine workers.

10.6.1 Replaceable Filter Respirator

Arespiratorconsistsofamask that fits a miner’s face and forms a seal against the
dusty air. Dirty air is drawn through replaceable filters than can collect 80%e98%