3. All four vehicles equipped with DPFs showed
visible signs of exhaust leaks between the ex-
haust manifold and the filter. It was not pos-
sible to quantify these leaks, but assumption
is that they contributed significantly to the
concentration of DPM in the mine air.

4.2 Particle distribution measurement

A scanning mobility particle sizer was used to
measure size distributions of the particles in mine air
at the downstream end of the zone. The measure-
ments were performed for all tested vehicles three
times during each of the 8-minute load-haul-dump
cycles: while vehicles were (1) performing load cy-
cle, (2) tramming from load to dump point, and (3)
performing dump cycle. During the four-hour test
period, more than thirty sets of data were collected
per vehicle for each of the aforementioned instances
in the duty cycle. The obtained concentrations were
corrected for fluctuations in the ventilation rate that
occurred between the tests. Figure 6 shows results of
size distribution measurements obtained while vehi-
cle VH181 was exercised over load cycles during
the four-hour testing. The excellent repeatability of
measurements, observed for all vehicles, indicates
stability of test parameters influencing distributions,
such as ventilation rates, duty cycle, ambient condi-
tions, etc.

The measurements showed that size distribution
of particles emitted by vehicles retrofitted with DPFs
are bimodal (see Figure 7) with relatively high con-
centrations of nanoparticles (below 50 nm). The
emissions from vehicles equipped with DOCs were
characterized with relatively high concentrations of
particles below the 100 nm size range.

The efficiencies of tested aftertreatment tech-
nologies in curtailing DPM emissions were com-
pared on a basis of the averaged integral number and
volume concentrations (see Figures 4 and 5). The re-
sults showed that all filtration systems except the
one installed on VL247 demonstrated excellent effi-

1408607

1206407

1006407

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‘0068

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Particles count, {#/em*3)

2008108

0.0600: J
Vuas4”VL244

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[Houmwcrte fi tontcrie lf pr annoina rot

Figure 4. Particle concentrations by number.

2s0e+12.

1 s0ee2

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Particles count, [#/em*3}

s.00e+11

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[ome cre

oe

Figure 5. Particle concentrations by volume.

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i como

wise

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Figure 6. VH181 load cycle size distributions.

1 00606 p—~

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4 00607 | a

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1.00608,

“Tucks. Keita PF

1 one0s SE U0 1, boc.

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Ls 2, Cwamie OFF

ua, sic ORF

Figure 7. Load cycle particle size distributions.

ciency in reducing the number of particles emitted.
For the LHD retrofitted with that particular system,
the concentrations of particles by number were even
higher than for the similar LHD equipped with the
DOC. In addition, according to the SMPS measure-
ments, the filter system on VL247, as well as the fil-
ter system on VH183 truck did not offer expected
reductions in particle volume of DPM emitted. The

437


Carder DK [1999]. Performance Evaluation of Exhaust After-
treatment Devices Used for Emissions Control on Diesel
Engines Employed in Underground Coal Mines. West Vir-
ginia University, Morgantown WV.

Czerwinski J, Jaussi F, Wyser M, and Mayer A [2000]. Particu-
late Traps for Construction Machines: Properties and Field
Experience. SAE Technical Paper 2000-01-1923.

Grenier M and Butler K [1996]. Respirable Combustible Dust
(RCD) Sampling and Analysis Protocol. Natural Resources
Canada, Mining and Mineral Sciences Laboratories,
sional Report MMSL 96-029 (TR).

Jelles SJ, Makkee M, Moulijn JA, Acres GJK, and Peter-
Hoblyn JD [1999]. Diese! Particulate Control. Application
of an Activated Particulate Trap in Combination with Fuel
Additives at an Ultra Low Dose Rate. SAE Paper 1999-
010-0113.

Kahlert B [1999]. First Use of Additive-Regenerated Diesel
Particulate Filters in Germany Mines. The Proceedings of
the Mining Diesel Emissions Conference (MDEC), To-
ronto, Canada, November 3 and 4.

Kauffeldt TH and Schmidt-Ott A [1998]. Investigation of the
Influence of Exhaust Aftertreatment on the Particulate
Phase in Diesel Exhaust Gases. Journal of Aerosol Science,
Vol. 29, Suppl.1, pp. $625 - $626.

Larsen CA, Levendis YA, and Shimato K (1999). Filtration
‘Assessment and Thermal Effects of Aerodynamic Regen-

440

eration in Silicon Carbide and Cordierite Particulate Filters.
SAE Paper 1999-01-0466.

Lani T, Conway R, Chatterjee S, Windawi H, Rosenblatt D,
Bush CW, Lowell DM, Evans J, and Mclean RO (2001).
Particulate matter Emissions Test Results from Urban Tran-
sit buses Equipped with Continuously Regenerating Diese!
Particulate Filters. SAE Technical Paper 2001-01-0511.

Mayer A [2000]. Particulate Traps Used in City-Buses in Swit-
zerland, SAE Technical Paper 2000-01-1927.

Mayer A, Matter U, Czerwinski J, and Heeb N [1999]. Effec-
tiveness of Particulate Traps on Construction Site Engines:
VERT Final Measurements. DieseINet Technical Report.
[URL=http://www.dieselnet.com/papers/9903mayer/index.
html], March.

‘New Brunswick [1996], Regulations 96-105 under the Occupa-
tional Health and Safety Act (O.C. 96-968)

Postnikoff JA [1999]. Diesel Particulate Matter Minimization
at Agrium, The Proceedings of the Mining Diesel Emis-
sions Conference (MDEC), Toronto, Canada, November 3
and 4.

Watts WF, Cantrell BK, Bickel KL, Olson KS, Rubow KL,
Baz-Dresch JJ, and Carlson DH [1995]. In-Mine Evaluation
of Catalyzed Diesel Particulate Filters at Two Underground
Metal Mines., U.S. Department of the Interior, Bureau of
Mines RI 9571.



the most downstream end of the zone were the
heaviest with the most uniform spatial and temporal
distribution.

The team from the NIOSH Pittsburgh laboratories
used the Scanning Mobility Particle Sizer (SMPS)
(TSI, Inc.) and real time PAH monitor, the PAS
2000 (EcoChem Analytics), to measure concentra-
tions of airborne particles at the sampling station lo-
cated at the most downstream end of the zone. The
SMPS instrument was used for direct measurement
of ambient concentrations of particles with electrical
mobility diameter ranging from 10 — 392 nm. The
measurements were performed at three instances
during each of the repetitions of the duty cycle: (1)
while vehicle was performing load cycle at the most
upstream section of the zone, (2) while vehicle was
tramming from load to dump location, and (3) while
vehicle was performing dump cycle at the most
downstream section of the zone. The quasi steady-
state measurements were performed using 90-second
scans. The results shown in Figure 4 are based on in-
tegral count concentrations for each vehicle and the
sampling instance averaged over number of meas-
urements performed during the four-hour test period.
The PAS 2000 was used to measure in real-time
concentrations of DPM at the same location. The in-
strument uses a photoelectric aerosol sensor to indi-
rectly measure concentration of elemental carbon
particles by measuring concentration of particle-
bound PAH.

4.1 Results of EC/OC analysis

A total of 15 DPM samples for EC/OC analysis were
gathered for each of the tested vehicles. Five sam-
ples were collected at each of the following stations:
(1) The fresh air intake, (2) at the vehicle operator,
and (3) exhaust sampling station. The DPM samples
were analyzed for total carbon (TC) by CANMET’s
Laboratory using NIOSH Analytical Method 5040
[NIOSH 1999]. The analysis showed that the fresh
air inlet to the zone had very low concentrations of
TC. The analysis also showed that the TC concentra-
tions were slightly higher at the exhaust sampling
station than at the vehicle operator.

The results of analysis of the five samples col-
lected at the exhaust sampling station are presented
in Figures 2 and 3. The results are presented as aver-
age concentrations for the 5 samples analyzed per
vehicle. In order to illustrate the potential of the DPF
systems to reduce DPM concentrations in mine air
and to correlate measured concentrations to the cur-
rent regulations [MSHA 2001] based on TC limits
and recommended limits [ACGIH 2001] based on
EC limits, results of EC/OC analysis are presented in
Figures 2 and 3 as concentrations of total and ele-
mental carbon, respectively. The current and rec-
ommended limits appear on the graphs.

‘NIOSH 5040 Total Carbon Concentrations
gin

480 7 —

400 sna a2
= ‘oo ono
soo
20
g bed (MSHA 2006
10
ean
100
° ACG 122 opnes
; ‘Boon

‘utes wHtea v1e W258 zee 247
‘VEHICLES

Figure 2. Total carbon DPM concentration.

‘NIOSH 5040 Elemental Carbon Concentration
‘ugim3

EC ug
ga 8

8

ACEH 2001 orapceed)
Buys

vies” wHie9” water 254 vLzae | L247
‘VEHICLES

Figure 3. Elemental carbon DPM concentration.

Both LHDs retrofitted with DPFs emitted signifi-
cantly less TC and EC than the LHD equipped with
a DOC. It is important to note that the observed con-
centrations at the exhaust station for LHDs retrofit-
ted with DPFs were slightly higher than ACGIH
recommended limits of 0.05 mg/m? of TC or 0.02
mg/m? of EC.

The differences in concentrations of TC and EC
emitted by the trucks equipped with DPFs and the
one equipped with a DOC were somewhat less pro-
nounced. The ambient concentrations of TC meas-
ured when filter equipped truck VH183 was oper-
ated in the zone were much higher than expected.
VHI81 truck equipped with a DPF exhibited much
lower emissions than the baseline truck, VH188
equipped with a DOC. The concentrations measured
when VH181 was operated in the zone were the
lowest observed and very close to the ACGIH rec-
ommended limits.

In interpreting these results it is also seen as im-
portant to take the following into account:

1. The zone was ventilated at a rate below the
mandated 106 cfm/bhp by the provincial gov-
emmment [New Brunswick, 1996] but above
the certified ventilation rates for the engines
of 63 cfin/bhp

2. Time averaged concentrations obtained on the
exhaust sampling station should be higher than
those measured at the operator. Therefore, ob-
tained values should represent the worst-case
scenario used in exposure assessment.

436


relatively low efficiency of the VL247 system was
attributed to sizeable exhaust leaks between the tur-
bocharger and filter. The results showing poor per-
formance of the system on VH183 truck are in good
agreement with the results of carbon analysis.

The measurements with real-time PAH monitor
PAS 2000 (EcoChem Analytics 1998) were per-
formed at the same place as those with SMPS. As a
real-time instrument, PAS 2000 was used to measure
concentrations of elemental carbon particles in mine
air throughout the total length of the tests for each of
the vehicles. In the instrument, the particles laden
sample is passed through a quartz tube and particles
coated with PAHs are photo charged (EcoChem
Analytics 1998). The charged particles are then col-
lected on the filter element and electrical currents
associated with the ion current are measured. Per-
formances of the tested aftertreatment devices are
compared on a basis of the integral instrument read-
ing averaged over the test period.

Avg Rdg- £4

aaa

“="VH188" VH183 VHI81” VL254~ VL244"VL247

Figure 8. PAS 2000 results.

The overall results shown in Figure 8 illustrates that
the particulate traps installed on three of the four ve-
hicles offered significant reductions in particle con-
centrations when compared to a DOC exhaust con-
figuration. High concentrations of particles observed
for vehicle VH183 demonstrated a serious failure of
the filter installed on that vehicle.

5 TAILPIPE EFFICIENCY MEASUREMENT

After completion of the four-hour testing inside the
isolated zone, each of the vehicles retrofitted with
DPFs was subjected to stationary tailpipe emissions
measurements. The testing station was set up at the
entrance to the isolated zone. The direct tailpipe
emissions measurements were conducted after ambi-
ent tests to avoid background interference problems.
Three methods were used to measure diesel particu-
late concentration in the tailpipe upstream and
downstream of the filters. The results were used to

438

assess the filtration efficiency of the DPFs with re-
spect to raw undiluted exhaust.

The experts from CANMET used the NanoMet
instrument (Matter Engineering AG) to measure par-
ticulate concentrations upstream and downstream of
each of the tested filters. Two sensors are incorpo-
rated in the instrument, a diffusion charger (DC) for
measuring concentrations of the particles by virtue
of their active surface and a PAS 2000 for measuring
concentrations of elemental carbon particles. The
sampling stream is diluted using a spinning disk di-
luter, MD19-2E (Matter Engineering AG). In order
to minimize thermophoretic losses, the samples are
acquired through heated sampling lines. The results
of these measurements were used to assess effi-
ciency of the filters.

Measurements were also made using a newly de-
veloped method. The method was developed as a re-
sult of a search for a relatively inexpensive, simple
but still accurate method for evaluating DPFs. The
method used for sampling with an ECOM AC
(ECOM America) gas analyzer and Bacharach
Smoke Number Analysis was slightly modified for
collecting DPM samples for EC/OC analysis. The
samples were collected on quartz fiber filters and
analyzed by CANMET’s laboratory using NIOSH
Analytical Method 5040. The results of the analysis
on filter efficiencies using NIOSH 5040 method are
presented in Figure 9.

Comparison of NIOSH 5040 to NanoMet

88seessse

[mt Avg Nano¥et
jw NNOSHSO40

‘L244 VL247 VH181 VH183

Figure 9. Filtration efficiency determined through NanoMet
and NIOSH 5040 analysis.

The results of raw tailpipe measurements were found
to correlate well with the results of the airborne con-
centration measurements. What did become evident
during the tailpipe efficiency tests was that the effi-
ciencies of the filters determined on a basis of tail-
pipe measurements were much higher than those de-
termined on a basis of ambient measurements. This
can be mainly attributed to the earlier discussed
leaks in the exhaust systems upstream of the filters.
When particulate filters were working properly they
offered efficiencies in removing elemental carbon
particles in the range from 98 to 99% as seen in the
NanoMet results shown in Figure 9. What is not ac-


Mine Ventilation, De Souza (ed.)
© 2002 Swets & Zeitlinger, Lisse, ISBN 90 5809 387 5

Performance evaluation of diesel particulate filter technology in the
underground environment

S. McGinn
Noranda Inc., Technology Centre, Pointe Claire, Québec, Canada

M. Grenier
Natural Resources Canada, CANMET, Sudbury, Ontario, Canada

A. Bugarski & G. Schnakenberg
NIOSH - Pittsburgh Research Laboratory, Pittsburgh, Pennsylvania, United States of America

D. Petrie
Noranda Inc., Brunswick Mine, Bathurst, New Brunswick, Canada

ABSTRACT: As part of the Diesel Emissions Evaluation Program (DEEP) consortium, Noranda Inc. has un-
dertaken a field project to evaluate the overall performance of the latest diesel particulate filter technology
(DPF) at its Brunswick Mine in Bathurst, New Brunswick. Performance of the filtration systems is evaluated
with respect to their ability to reduce tailpipe emissions and concentrations of diesel particulate matter (DPM)
and noxious gases in mine air, efficiency of filter regeneration process, maintenance requirements, reliability,
and acceptance. Four different particulate filter systems deployed on heavy production vehicles are subjected
to an 18-month field evaluation. Over the evaluation period the vehicles will have accumulated approximately
4000 operating hours in production.

This paper presents the results of testing conducted mid way through the 18-month field trials. The 400-
meter section of the mine drift at 525-5 sub level, hereinafter referred to as the “isolated zone” was isolated
between intake and exhaust fan systems and sealed with bulkheads against leakage. The isolated zone was
ventilated at the rate required per CSA Standards and issued by CANMET for the engines tested. Four vehi-
cles, two load-haul-dumps (LHDs) and two trucks, retrofitted with particulate filter systems were tested along
with a new identical model LHD and truck equipped with exhaust systems consisting of a catalytic converter
(DOC) and muffler. The test vehicles were operated individually inside the isolated zone for approximately 4
hours over simulated production duty cycles.

Measurements of ambient concentrations of particulate matter, tailpipe emissions, and engine parameters
were performed for each of the tested vehicles. The DPM samples for carbon were collected at the most up-
stream end of the isolated zone, at the vehicle next to the operator, and at the most downstream or exhaust end
of the isolated zone. The DPM samples were analyzed for total (organic and elemental) carbon using NIOSH
Analytical Method 5040. Ambient concentrations of particulate matter at the exhaust end of the zone were
also measured using Scanning Mobility Particle Sizer (SMPS), and real time PAH monitor (PAS 2000). Effi-
ciency of the filters was also evaluated on a basis of tailpipe measurements performed using raw exhaust in-
struments the NanoMet and the UGAS. In addition, relevant engine parameters were obtained using Detroit
Diesel Diagnostic Link (DDDL) and from exhaust backpressure and temperature measurements. Results from
the tests proved conclusively that diesel particulate filters can significantly reduce the concentrations of air-
borne DPM, but not without careful monitoring of both ambient and tailpipe emissions and not without care-
ful attention with respect to maintaining the integrity of the DPF systems.

1 INTRODUCTION

The long-term objective of the diesel particulate filter
(DPF) evaluation project at Brunswick Mine is to
prove the overall performance of the technology in
underground mining applications. The performance
of the filters is evaluated with respect to their ability
to reduce tailpipe emissions and concentrations of
particulate matter and noxious gases in mine air, effi-
ciency of the filter regeneration process, maintenance
requirements, reliability and acceptance. The criteria
with most impact are certainly the efficiency of the
filter systems in reducing tailpipe emissions and con-

433

sequently concentrations of particulate matter and
noxious gases in mine air. In 1996 the American
Congress of Governmental Industrial Hygienists
(ACGIH) derived and recommended the TLV-TWA
for diesel particulate matter of 0.15 mg/m’ based on
total carbon (TC). In the notice of intended change
for 1998 the proposed limit was lowered again to
0.05 mg/m’ TC. In the notice of intended change for
2001 ACGIH [ACGIH 2001] recommended an
equivalent TLV-TWA of 0.02 mg/m’ based on ele-
mental carbon (EC). Recently the United States Mine
Safety and Health Administration (MSHA) promul-
gated new regulations [66 Fed. Reg. 5706 and cor-


counted for are the potential leaks in the exhaust sys-
tem between the exhaust manifold and the inlet to
the particulate filter. The NanoMet measurements
confirmed that three of four tested filters offer above
95% reductions in particulate matter concentrations.
The DPF installed on VH183 exhibited efficiencies
that are much lower than expected confirming the
hypothesis about compromised filter media.

6 CONCLUSIONS

The isolated zone study showed that significant re-
ductions in concentrations of diesel particulate mat-
ter in underground mines are achievable with diesel
particulate filter technology. The study also demon-
strated several measurement and analysis methods
available to the underground mining industry for
evaluating performance of filter technology.

The extensive measurements showed that three
out of four tested filters offered excellent reductions
in DPM concentrations, The measurements also
showed poor filtration efficiency of the fourth filter
indicating premature failure of the filter. The post-
test investigation revealed that the filter media had
been cracked internally. Traces of black soot were
identified at the outlet face of the filter. The prema-
ture failure was attributed to uncontrolled regenera-
tion during which exhaust temperatures inside the
filter had exceeded 1500°C for an extended period
of time.

The comparison of the results of SMPS and tail-
pipe measurements revealed certain important issues
with the complex filter efficiency evaluation proc-
ess. The SMPS measurements in mine air indicated
high number and volume concentrations of particles
emitted by VL247 LHD retrofitted with a DPF,
which had shown high filtration efficiencies accord-
ing to tailpipe emissions measurements. This alarm-
ing discrepancy in the results of filter evaluation
processes based on tailpipe emission measurements
and on measurements of ambient concentrations of
particles was explained by sizeable leaks discovered
in the exhaust system between the engine and the
DPF. Apparently estimating the effects of the filter
on ambient concentrations of particulates on a basis
of tailpipe emissions is not a straightforward proc-
ess. Introducing a DPF into the exhaust system sig-
nificantly increases engine exhaust backpressure,
which can have the consequence of increased tail-
pipe emissions. This emphasizes the importance of
maintaining integrity of the exhaust system upstream
of the filter.

The measurement methods employed in the iso-
lated zone study provided consistent and valuable
data necessary for better understanding of processes
governing the formation and transformation of diesel
particulate matter in mine air. The NIOSH Analyti-
cal Method 5040 proved to be a very accurate

439

method for assessment of the exposure levels
achievable by DPF technology with respect to both
total carbon and elemental carbon. SMPS and PAS
2000 were found to be valuable instruments for ob-
taining information necessary for better understand-
ing of the processes. The study demonstrated several
methods available to the underground mining indus-
try for assessing the efficiency of DPF systems. The
methods of different levels of sophistication, varying
from simple to very sophisticated offered acceptable
levels of accuracy. The down side of relying on tail-
pipe measurements for evaluations was evidenced
with VL247 LHD where the system with a 99% effi-
cient filter offered significantly lower overall system
efficiency due to leaks in the exhaust system. The
tailpipe measurement instruments were able to
measure the 99% efficiency quite accurately but
only the ambient measurements were able to detect
the effects of the leaks.
The principal conclusions to be drawn from the
testing done inside the isolated zone are:
1. Diesel particulate filter technologies were
demonstrated to be very efficient in reducing
DPM concentrations. At a ventilation rate ap-
propriate for the engine, the ambient DPM
concentrations achieved during this study are
well below the current and final MSHA regu-
latory limits and almost meet recommended
diesel particulate exposure limits.
to attain and sustain diesel equip-
ment within these limits would depend on the
ability of operators to measure performance
and maintain the systems accordingly.
Filter efficiency must be evaluated using both
tailpipe and ambient measurements. These two
types of measurement complement each other.
The importance of maintenance cannot be
overemphasized — undetected failures and
leaks in the DPF system can potentially result
in particulate exposure levels that can be
higher than current levels.

REFERENCES

66 Fed. Reg. 5706 and corrections 66 Fed. Reg. 35518 [2001].
Mine Safety and Health Administration: 30 CFR Part 57
Diesel Particulate Matter Exposure of Underground Metal
and Nonmetal Miners; Final Rule.

ACGIH. American Conference of Governmental Industrial
Hygienists [2001]. Notice of Intended Change for 2001.
TLVs® and BEIs®. Trashold Limit Values for Chemical
Substances and Physical Agents. Biological Exposure Indi-
ces. p.62

Baz-Dresch JJ, Bickel KL, and Watts WF [1993]. Evaluation
of Catalyzed Diesel Particulate Filters in an Underground
Metal Mine. Report of Investigation 9478, U.S. Department
of the Interior, Bureau of Mines.

Bugarski A [1999]. Characterization of Particulate Matter and
Hydrocarbon Emissions from In-Use Heavy-Duty Diesel
Engine. Doctoral Dissertation, West Virginia University,
Morgantown, West Virginia, December.


rections 66 Fed. Reg. 35518 2001] setting an interim
limit of DPM exposure for underground metal and
nonmetal miners to 0.40 mg/m’ of total carbon (TC).
The rule sets the final limit, effective January 19,
2006 at 0.16 mg/m’® TC. All current regulations in
Canada, where mining is regulated by provincial
governments, set the limit for DPM TLV-TWA at
1.50 mg/m’ determined as the equivalent to TC and
measured using the Respirable Combustible Dust
(RCD) method [Grenier et al. 1996]. In anticipation
of changes in provincial DPM regulations the Cana-
dian mining industry, labor, manufacturers, Canadian
and U.S. government agencies formed the Diesel
Emissions Evaluation Program (DEEP) consortium.

Recently DPFs have been widely accepted and
proven as a very effective technology for curtailment
of DPM emissions from diesel powered vehicles
[Mayer et al. 1999, Czerwinski et al. 2000, Mayer
2000, Lani et al. 2001]. Unfortunately, very limited
data is available on performance of diesel particulate
filters working in underground mines [Watts et al.
1995, Postnikoff 1999, Kahlert 1999, Carder 1999].
Although the efficiency of the DPFs was extensively
investigated in numerous laboratory and field studies
[Larsen 1999, Bugarski 1999], there is almost no
data available on the potential effects of DPFs in re-
ducing concentrations of DPM in underground
mines. This information is vital in assessing the po-
tential of diesel particulate filters for reducing miner’s
exposure to DPM.

2 ISOLATED ZONE AND TEST CYCLE

Accurately quantifying the effects of DPFs on con-
centrations of particles in mine air required isolating
an operating zone in the mine with well-defined and
controlled ventilation and eliminating interference
from other diesel powered vehicles.

The study was conducted at the 525-5 sub level of
Brunswick Mine. The mine provided an entire oper-
ating level in the mine, which had ceased production
activity yet, maintained effective ground control and
capabilities for efficient control of ventilation pa-
rameters. A 400 meter section of drift on 525-5 sub
level, hereinafter referred to as the “isolated zone,”
was completely isolated from the other parts of the
mine by installing two bulkheads and ventilated with
fresh, diesel particulate matter free air from the V3
intake fan system. (See Figure 1)

The ventilation flow rate was maintained as close
as possible to 30,000 cfm staying above the CSA
certified ventilation rate of 63 cfim/bhp yet below the
standard ventilation rate at Brunswick Mine of 106
cfm/bhp.

DPM sampling stations were set up inside the
zone at the following locations: (1) at the air intake

side of the zone, (2) on the vehicles at the operator’s
compartment, and (3) at the exhaust side of the zone.
An additional station was set up at the exhaust side
of the zone for measurement of particulate with re-
spect to particle count and size distribution.

All ventilation and vehicle operation parameters
relevant for the study were closely monitored and
controlled.

Figure 1. Isolated zone.

2.1 Test cycle

A zone was sectioned off between the V3 intake
raise and the exhaust raise as shown in Figure 1.
Each of the vehicles tested in this study was oper-
ated inside the 400-meter zone while repeating an
identical simulated cycle. The vehicles were oper-
ated with the bucket / box-filled with ore. The cy-
cle, developed exclusively for this study, simulated
duty cycles observed for LHD vehicles in normal
operation at the mine. The cycle consisted of the
following operations: (1) At the air intake side of
the zone the vehicle was parked for a period of 2
minutes and operated for four times under steady
state conditions for 15 seconds at full throttle with
torque converter and hydraulic stalled steady state
followed by 15 seconds at full throttle with trans-
mission in neutral and no load on engine. This
simulated the mucking cycle in repeatable and con-
sistent fashion without producing dust interference
normally associated with mucking. (2) The vehicle
then trammed for 400 meters atong the drift to the
exhaust end of the zone where the vehicle was
turned around and parked to simulate the dump por-
tion of the cycle; (3) The dump cycle was simply a
steady state 30-second run at full throttle with
transmission in neutral and no load on engine; (4)
After finishing with the dump cycle the vehicle
then returned to the fresh air intake gate to repeat
the full cycle. The vehicle was operated for a pe-
riod of 4 hours repeating the described 8-minute
cycle, In order to minimize the effects of human er-
ror, all tested vehicles were operated in similar
fashion, by a single experienced operator.

434


3 VEHICLES AND PARTICULATE TRAPS

In order to assess the potential of the filter systems
to improve air quality in the mine over current exist-
ing conditions, emissions from four vehicles
equipped with DPFs were compared with emissions
from two vehicles equipped with diesel oxidation
catalyst (DOC) and silencer as mandated by current
New Brunswick provincial regulations [New Bruns-
wick, 1996]. The vehicles being used to test the die-
sel particulate filter (DPF) technology in the project
are the Wagner ST8-B LHDs (Load, haul, dump ve-
hicles also known as Scooptram) and the Wagner
MT436-B dump trucks. The LHDs use Detroit Die-
sel Series 60 model engines rated at 325 HP. The
trucks use similar Series 60 model engines with
slightly higher output rated at 375 HP. All vehicles
are equipped with torque converters and automatic
transmissions.

The combinations of the four different DPF tech-
nologies and vehicles are shown in Table 1. All
other vehicles at Brunswick Mine are equipped with
mandated [New Brunswick, 1996] exhaust system
configurations consisting of diesel oxidation cata-
lysts (DOC) and in some cases optional silencers. In
order to assess the potential for improving the qual-
ity of mine air by replacing existing exhaust systems
with DPFs, two additional vehicles, an LHD and a
truck, each equipped with original DOC configura-
tion were also included in the study. The emissions
from vehicles equipped with DPFs were compared
to those from identical vehicles equipped with a
DOC.

Table 1. Vehicles and exhaust systems.

Vehicle Exhaust DPF Technology
‘VAI88 Truck DOC =
SiC Monolith with
VH183 Truck DPF Fuel Borne Catalyst —
Passive Regeneration
Wound Fiber Car-
tridges with Fuel,
VHI81 Truck DPF Bone Catalyst — Pas-
sive Regeneration
Vi254 LHD DOC =
Ceramic Monolith —
‘VL244 LHD DPF Passive Regeneration
SiC Monolith - Active
VL247 LHD DPF Regeneration with.
Electric Heater

At Brunswick Mine all LHDs and trucks are com-
missioned with identical specifications and configu-
rations. Engine, power train, hydraulic, frame and all
other vehicle systems are exactly identical across the
ST8-B LHD fleet and similarly for the MT436-B
truck fleet. All vehicles tested in the isolated zone
study accumulated relatively low total operating
hours prior to the testing. The four vehicles equipped
with the DPFs had accumulated between 1200 and

435,

2200 total operating hours since delivery from the
vehicle manufacturer. The LHD and truck equipped
with DOCs were almost brand new with only 500
and 200 operating hours, respectively.

The DPFs (see Table 1) evaluated in this project
represents a cross section of the most widely ac-
cepted technology being employed in diesel applica-
tions around the world.

Wall flow monolith filters have been in use since
the 1980s. Three of the four systems in this study
employed either ceramic cordierite or silicon carbide
(SiC) monoliths as shown in Table 1. The fourth
system employs a promising wound fiber technol-
ogy. In addition to evaluating efficiency of the filters
this study also had for an objective to investigate
suitability of different filter regeneration schemes
for underground mining applications. Three of the
tested filter systems, two retrofitted on trucks and
one on an LHD, are regenerated passively, using ex-
haust heat generated during regular duty cycles to
combust the soot accumulated inside the filter. In
order to lower the regeneration temperature both
trucks used a fuel containing a fuel-borne catalyst.
The fourth vehicle, VL247 LHD uses an electric
heater to actively regenerate the filter between shifts.
Diese! oxidation catalyst (DOC) technology in gen-
eral reduces the carbon monoxide and hydrocarbon
emissions and offers relatively small reductions in
diesel particulate matter (DPM) emissions, mostly in
it’s organic fraction. The down side is that DOCs,
depending on catalyst activity and engine load, can
increase emissions of nitrogen dioxide.

4 MEASUREMENT OF AMBIENT
CONCENTRATIONS OF DIESEL
PARTICULATE MATTER

A total of seven samples were collected at each of
the three sampling stations inside the isolated zone.
Five of the samples were collected for carbon analy-
sis using NIOSH Analytical Method 5040. The sam-
pling trains consisted of a cyclone as pre-separator,
37-mm cassette with quartz fiber filter, tubing, and
sampling pump calibrated at 1.7 L/min. At the fresh
air intake and exhaust sampling stations the samplers
were hung onto a 6 X 12 screen positioned to give a
cross section representation of the drift ventilation
flow across the samplers. The samplers on the vehi-
cle were placed in a screen basket mounted on top of
the engine compartment directly in front of and
within one meter of the operator. The experts from
CANMET’s Sudbury U/G Mine Environment Team
conducted all DPM sampling and analysis.

In addition, extensive ambient measurements
were taken at the exhaust sampling station of the
zone. Because of the structured vehicle cycles and
the controlled ventilation rate inside the zone, the
concentration of airborne diesel particulate matter at