4
before every test run, using a hand-held hydraulic driller
with a chipper set at the end. The part of the concrete that
had contact with the coal dust and was coming in the way
of the pick cutter was chipped off. This guaranteed that
most dust particles collected for the FE-SEM study were
coal dust.
Two approaches were used to collect representa-
tive breathing dust from the rock cutting test. The first
approach used nylon 10-mm Dorr-Oliver cyclones, which
have a 50% limit on aerodynamic diameter of 4 m particles.
The second method was a Tsai Diffusion Sampler (TDS), a
device that can detect particles with a cutoff aerodynamic
diameter of 3.8 m (C S J Tsai &D Theisen, 2017).
The dust collector in this research study consists of an
automated apparatus that gathers respirable dust during
coal-cutting, minimizing manual error and allowing for
high-quantity and quality dust sampling. This automated
small apparatus consists of Pumps, a touch-screen HMI,
motorized ball valves, and a HEPA-filter shop vacuum.
The apparatus collects dust reliably and efficiently, ensur-
ing clean air flows in the post-cutting phase through a cal-
ibration-based on-and-off mechanism. A laser sensor keeps
track of cutting distances, making the cutting test more
precise.
The equipment uses Dorr-Oliver cyclones to whittle
out dust larger than 10 m, leaving respirable dust on PVC
or polycarbonate (PC) filters. The configuration consists
of three cyclones and a TDS (Tsai Diffusion Sampler)
mounted around the pick saddle, where individual filters
are used to measure dust levels. Tygon tubing links the dust
trap to air pumps, with cyclone pumps set at 1.7 liters per
minute and the TDS pump at 1.0 liters per minute for
maximum collection.
The measurements were performed in an experimen-
tally controlled laboratory, with a humidity of 20–24% and
an average temperature of 62°F. The system also includes
boundary markers to standardize the area for collecting fine
material, ensuring consistency across tests. Dust from the
first and last relief cuts was excluded from sampling so that
samples would not get contaminated by dust particles and
other coal dust.
To adhere to the sampling technique, the chips and
larger material between the boundary lines had to be physi-
cally gathered at first. The vacuum then collected the finer,
looser material. The researcher used a 5-gallon bucket with
a Bucket Head installed on top. Once the vacuum had col-
lected the fines, the particles removed from the filter were
pass the no. 200 mesh because of their size. After collecting
the resulting particles of every test set, the bucket was prop-
erly cleaned, and the filter was changed.
The sampling procedure is followed by a collection of
larger fines and chips within the boundary lines, initially
gathered manually. For better efficiency, finer, loose mate-
rial was collected using a vacuum pump. The research team
utilized a 5-gallon bucket fitted with a Bucket Head attach-
ment. As determined by a sieve, particles remaining on the
filter were classified as those passing through a no. 200 mesh
because of their size. After vacuuming the fines and chips,
the particles collected were preserved for further particle
size distribution analysis. After completing each test set, the
filter was replaced to maintain accuracy and consistency.
Specific Energy and Wear Condition
In rock and coal cutting operations, the interrelationships
between specific energy, bit wear, dust generation, and par-
ticle size distribution are critical and multifaceted, influ-
encing operational efficiency and environmental health.
Specific energy, which quantifies the energy required to
remove a unit volume of material, is inversely related to
cutting efficiency. The specific energy (SE) was calculated
during cutting tests using the measured drag or rolling
forces.
The specific energy can be calculated using the formula.
SE V
FrL =
Fr =rolling force,
L =cutting distance
V =volume of material removed
Assuming optimal performance, the cutting volume can
be expressed in terms of the penetration depth (p) and the
spacing (s).
Therefore,
/s ()SE pLs
FrL Fr
p hp hr/yd 3 ==-
Here, the ratio of penetration to spacing (p/s) is a suitable
metric for investigating the cutting efficiency of Tunnel
Boring Machines (TBMs) (Rostami, 1997 &2008).
NIOSH Manual of Analytical Methods (NMAM)
The research team tested each cassette using the NMAM
7500 method, reporting the percent and density of dust in
each set of tests. A copy was taken of each test set to ensure
consistency, and the findings were examined to verify com-
pliance with the test protocol.
In the NMAM 7500/0600 analysis, 57 cassettes were
used to calculate the dust concentration. Testing measured
an average temperature of 62°F and an average air humid-
ity of 21%, with the pump operating at a flow rate of
1.7 L/min.
before every test run, using a hand-held hydraulic driller
with a chipper set at the end. The part of the concrete that
had contact with the coal dust and was coming in the way
of the pick cutter was chipped off. This guaranteed that
most dust particles collected for the FE-SEM study were
coal dust.
Two approaches were used to collect representa-
tive breathing dust from the rock cutting test. The first
approach used nylon 10-mm Dorr-Oliver cyclones, which
have a 50% limit on aerodynamic diameter of 4 m particles.
The second method was a Tsai Diffusion Sampler (TDS), a
device that can detect particles with a cutoff aerodynamic
diameter of 3.8 m (C S J Tsai &D Theisen, 2017).
The dust collector in this research study consists of an
automated apparatus that gathers respirable dust during
coal-cutting, minimizing manual error and allowing for
high-quantity and quality dust sampling. This automated
small apparatus consists of Pumps, a touch-screen HMI,
motorized ball valves, and a HEPA-filter shop vacuum.
The apparatus collects dust reliably and efficiently, ensur-
ing clean air flows in the post-cutting phase through a cal-
ibration-based on-and-off mechanism. A laser sensor keeps
track of cutting distances, making the cutting test more
precise.
The equipment uses Dorr-Oliver cyclones to whittle
out dust larger than 10 m, leaving respirable dust on PVC
or polycarbonate (PC) filters. The configuration consists
of three cyclones and a TDS (Tsai Diffusion Sampler)
mounted around the pick saddle, where individual filters
are used to measure dust levels. Tygon tubing links the dust
trap to air pumps, with cyclone pumps set at 1.7 liters per
minute and the TDS pump at 1.0 liters per minute for
maximum collection.
The measurements were performed in an experimen-
tally controlled laboratory, with a humidity of 20–24% and
an average temperature of 62°F. The system also includes
boundary markers to standardize the area for collecting fine
material, ensuring consistency across tests. Dust from the
first and last relief cuts was excluded from sampling so that
samples would not get contaminated by dust particles and
other coal dust.
To adhere to the sampling technique, the chips and
larger material between the boundary lines had to be physi-
cally gathered at first. The vacuum then collected the finer,
looser material. The researcher used a 5-gallon bucket with
a Bucket Head installed on top. Once the vacuum had col-
lected the fines, the particles removed from the filter were
pass the no. 200 mesh because of their size. After collecting
the resulting particles of every test set, the bucket was prop-
erly cleaned, and the filter was changed.
The sampling procedure is followed by a collection of
larger fines and chips within the boundary lines, initially
gathered manually. For better efficiency, finer, loose mate-
rial was collected using a vacuum pump. The research team
utilized a 5-gallon bucket fitted with a Bucket Head attach-
ment. As determined by a sieve, particles remaining on the
filter were classified as those passing through a no. 200 mesh
because of their size. After vacuuming the fines and chips,
the particles collected were preserved for further particle
size distribution analysis. After completing each test set, the
filter was replaced to maintain accuracy and consistency.
Specific Energy and Wear Condition
In rock and coal cutting operations, the interrelationships
between specific energy, bit wear, dust generation, and par-
ticle size distribution are critical and multifaceted, influ-
encing operational efficiency and environmental health.
Specific energy, which quantifies the energy required to
remove a unit volume of material, is inversely related to
cutting efficiency. The specific energy (SE) was calculated
during cutting tests using the measured drag or rolling
forces.
The specific energy can be calculated using the formula.
SE V
FrL =
Fr =rolling force,
L =cutting distance
V =volume of material removed
Assuming optimal performance, the cutting volume can
be expressed in terms of the penetration depth (p) and the
spacing (s).
Therefore,
/s ()SE pLs
FrL Fr
p hp hr/yd 3 ==-
Here, the ratio of penetration to spacing (p/s) is a suitable
metric for investigating the cutting efficiency of Tunnel
Boring Machines (TBMs) (Rostami, 1997 &2008).
NIOSH Manual of Analytical Methods (NMAM)
The research team tested each cassette using the NMAM
7500 method, reporting the percent and density of dust in
each set of tests. A copy was taken of each test set to ensure
consistency, and the findings were examined to verify com-
pliance with the test protocol.
In the NMAM 7500/0600 analysis, 57 cassettes were
used to calculate the dust concentration. Testing measured
an average temperature of 62°F and an average air humid-
ity of 21%, with the pump operating at a flow rate of
1.7 L/min.