TM

RI 9668 

REPORT OF INVESTIGATIONS/2006 

Effectiveness of Selected 

Diesel Particulate Matter Control 

Technologies for Underground Mining 

Applications: Isolated Zone Study, 2004 

Department of Health and Human Services

Centers for Disease Control and Prevention

National Institute for Occupational Safety and Health
Report of Investigations 9668 

Effectiveness of Selected Diesel Particulate Matter Control 

Technologies for Underground Mining Applications: 

Isolated Zone Study, 2004 

By Aleksandar D. Bugarski, Ph.D., George H. Schnakenberg, Jr., Ph.D., 

 Steven E. Mischler, James D. Noll, Ph.D., Larry D. Patts, and Jon A. Hummer 

DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Centers for Disease Control and Prevention 

National Institute for Occupational Safety and Health
 

Pittsburgh Research Laboratory 

Pittsburgh, PA 

August 2006 
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 e-mail: pubstaft@cdc.gov 

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This document is in the public domain and may be freely copied or reprinted. 

————————————————————— 

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to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or their programs 

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DHHS (NIOSH) Publication No. 2006–138 
CONTENTS 

Page 

Abstract............................................................................................................................... 1 

Introduction......................................................................................................................... 2 

Objective............................................................................................................................. 3 

Methodology....................................................................................................................... 5 

Vehicles and engines....................................................................................................... 5 

 Preparation of the vehicle for the study .......................................................................... 6 

Tested fuel formulations ................................................................................................. 6 

Tested aftertreatment systems......................................................................................... 8 

ArvinMeritor (AM) DPF System................................................................................ 8 

Clean Air Power/ETG catalytic particulate oxidizer (CPO) system......................... 10 

Filtration system with disposable filter element from Donaldson (model 

P604516).................................................................................... 11 

Filtration system with disposable filter element from Filter Service & Testing 

Corp. ...................................................................................................................... 12 

Fueling procedures........................................................................................................ 12 

Isolated zone testing...................................................................................................... 14 

Test site ..................................................................................................................... 14 

Duty cycles................................................................................................................ 17 

Ventilation................................................................................................................. 17 

Sampling and measurements methodology .................................................................. 18 

Sampling stations...................................................................................................... 18 

Sampling strategy...................................................................................................... 20 

Sampling methodology and instrumentation ............................................................ 20 

Analysis of samples ...................................................................................................... 25 

Analysis of DPM samples collected using standard and high-volume sampling 

 methods for elemental carbon content ................................................................... 25 

Gravimetric analysis of DPM samples ..................................................................... 26 

Analysis of filter samples for sulfate ion concentrations.......................................... 26 

Calculation of the effects of control technologies ........................................................ 27 

Results and discussion ...................................................................................................... 29 

Effects of fuel formulations .......................................................................................... 30 

Ventilation airflow rates for the test on fuel formulations........................................ 30 

Effects of fuel formulations on aerosols ................................................................... 32 

Effects of fuel formulations on concentrations of NO, NO2, CO, and CO2 ............. 45 

Effects of filtration systems .......................................................................................... 48 

Ventilation airflow rates for filtration systems tests................................................. 48 

Effects of filtration systems on aerosols ................................................................... 49 

Effects of filtration systems on exhaust temperature and engine back pressure....... 60 

Summary........................................................................................................................... 63 

Acknowledgments............................................................................................................. 65 

References......................................................................................................................... 66 
ILLUSTRATIONS 

1. ArvinMeritor DPF system............................................................................................ 9 

2. Clean Air Power/ETG CPO system........................................................................... 10 

3. Filtration system used in testing high-temperature disposable elements from

 Donaldson and Filter Service.................................................................................. 11 

4. Fueling station in the isolated zone............................................................................ 13 

5. Auxiliary tank on LHD 1 ........................................................................................... 13 

6. Isolated zone, 52E entry, SMC Nye mine.................................................................. 15 

7. LHDs in the isolated zone.......................................................................................... 16 

8. Downstream sampling station showing instrumentation and wire grid supporting 

 DPM samplers, anemometer, iTX gas monitor, and RKI Eagle CO2 monitor ....... 19 

9. Ventilation rates measured at the downstream sampling station during the 

baseline fuel test...................................................................................................... 31 

10. Contributions of fuel formulation to concentrations of EC and gravimetrically 

 and TEOM-determined TPM.................................................................................. 33 

11. Changes in average concentrations of EC and TPM for tested fuel formulations..... 34 

12. Effects of water emulsions on mass concentrations of TPM at downstream 

 sampling station measured by TEOM..................................................................... 36 

13. Effects of biodiesel blends on mass concentrations of TPM at downstream 

 sampling station measured by TEOM..................................................................... 37 

14. Effects of ULS fuel on mass concentrations of TPM at downstream sampling 

 station measured by TEOM .................................................................................... 38 

15. Aerosol size distributions at downstream and upstream stations observed during 

 water emulsion tests................................................................................................ 41 

16. Effects of water emulsions on the size distributions of aerosols ............................... 41 

17. Effects of soy biodiesel blends on the size distributions of aerosols......................... 42 

18. Effects of yellow grease biodiesel blends on the size distributions of aerosols ........ 43 

19. Effects of ULS diesel on the size distributions of aerosols ....................................... 44 

20. Effects of tested DOC on concentrations of NO2 at vehicle sampling station 

 observed from the test with 50% soy biodiesel ...................................................... 47 

21. Ventilation rates measured at the downstream sampling station during the baseline filter test ........................................................................................................... 49 

22. VR-adjusted average concentrations of EC and gravimetrically and TEOM- 

 determined TPM ..................................................................................................... 50 

23. Changes in average concentrations of EC and TPM with implementation of 

 filtration systems..................................................................................................... 51 

24. Effects of filtration systems on mass concentrations of TPM measured throughout the tests by TEOM ............................................................................................ 53 

25. Effects of filtration systems on aerosol size distribution........................................... 54 

26. Effects of filtration systems on NO2 concentrations at downstream sampling 

station...................................................................................................................... 58 

27. Effects of filtration systems on NO2 concentrations at vehicle sampling station...... 59 

28. LHD 2 exhaust temperature and engine back pressure during muffler test............... 60 

ii 
29. LHD 2 exhaust temperatures and engine back pressure during testing with an 

 AM DPF and Pd DOC ............................................................................................ 61 

30. LHD 2 exhaust temperature and engine back pressure during testing with 

 Filter Service DFE .................................................................................................. 61 

TABLES 

1. Control technologies evaluated in the study ................................................................ 4 

2. Test vehicles and engines............................................................................................. 5 

3. Fuel formulation properties.......................................................................................... 7 

4. Aftertreatment systems ................................................................................................ 8 

5. Tests conducted during the study............................................................................... 29 

6. Average VRs at the downstream sampling station for the fuel tests ......................... 31 

7. Effects of fuel formulations on EC, gravimetrically and TEOM-determined 

TPM, and sulfate (SO4) concentrations .................................................................. 32 

8. Effects of fuel formulations on ventilation-adjusted average net vehicle contri- 

 butions to concentrations of EC at the vehicle sampling station ............................ 35 

9. Effects of fuel formulations on size distribution and concentrations of aerosols 

 in mine air ............................................................................................................... 40
 

10. Net contributions of fuel formulations to average and peak NO, NO2, CO, and 

CO2 concentrations at the downstream sampling station........................................ 45 

11. Net contributions of fuel formulations to average and peak NO, NO2, CO, and 

CO2 concentrations at the vehicle sampling station................................................ 46 

12. Average VRs at the downstream sampling station for the filter tests........................ 49 

13. Effects of filtration system on average EC, gravimetrically and TEOM- 

 determined TPM, and sulfate (SO4) concentrations ............................................... 50 

14. Effects of diesel particulate matter filtration systems on size distribution and 

 concentrations of aerosols in mine air .................................................................... 55 

15. Net contributions of filtration system to average and peak NO, NO2, CO, and 

CO2 concentrations at the downstream sampling station........................................ 57 

16. Net contributions of filtration system to average and peak NO, NO2, CO, and 

CO2 concentrations at the vehicle sampling station................................................ 57 

17. Peak exhaust temperatures and engine back pressures measured during the 

 filter tests................................................................................................................. 62 

iii 
 

 

 

 

 

 

 

 

ACRONYMS AND ABBREVIATIONS USED IN THIS REPORT 

ACGIH American Conference of Governmental Industrial Hygienists 

AM ArvinMeritor, Inc. (Columbus, IN) 

ASTM American Society for Testing and Materials 

CAP Clean Air Power, Ltd. (Houston, TX) 

CFR Code of Federal Regulations 

CH4 methane 

Ci net contribution of the tested vehicle to air concentrations of 

pollutant for control technology test 

Ci BL net contribution of the tested vehicle to air concentrations of 

pollutant for baseline test 

ci measured concentration 

ci,VR ventilation-adjusted concentrations 

ci,VR,,DOWN ventilation-adjusted concentrations at the downstream sampling 

station 

ci,UP measured concentration at the upstream sampling station 

CO carbon monoxide 

CO2 carbon dioxide 

CPO catalytic particulate oxidizer 

CV coefficient of variation 

D_p particle diameter 

DFE disposable filter element 

dN/(d log D_p) normalized particle number concentration 

DOC diesel oxidation catalyst 

DPF diesel particulate filter 

DPM diesel particulate matter 

EC elemental carbon 

ETG Emission Technology Group AB (Gothenburg, Sweden) 

Fed. Reg. Federal Register 

FID flame ionization detector 

GMD geometric mean diameter 

GSD geometric standard deviation 

HV high-volume 

IC ion chromatography 

LHD load-haul-dump 

MARG Methane Advisory Research Group 

MSHA Mine Safety and Health Administration 

N/A not available 

NIOSH National Institute for Occupational Safety and Health 

NO nitric oxide 

NO2 nitrogen dioxide 

O2 oxygen 

OC organic carbon 

PAH polycyclic aromatic hydrocarbon 

iv 
PAS Photoelectric Aerosol Sensor (EcoChem Analytics) 

PC personal computer 

Pd palladium 

Pd DOC diesel oxidation catalyst with palladium-based formulation 

PRL Pittsburgh Research Laboratory (NIOSH) 

Pt platinum 

Pt DOC diesel oxidation catalyst with platinum-based formulation 

SMC Stillwater Mining Co. 

SMPS scanning mobility particle sizer 

SSM standard sampling method 

TEOM tapered-element oscillating microbalance 

TLV threshold limit value (ACGIH) 

TPM total particulate matter 

ULS ultralow sulfur (diesel) 

USBM U.S. Bureau of Mines 

VR ventilation rate 

VRbaseline LHD 1 average ventilation rate for the LHD 1 baseline tests 

VRbaseline LHD 2 average ventilation rate for the LHD 2 baseline tests 

YG yellow grease (biodiesel) 

v 
 

 

 

 

 

UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 

cm2 square centimeter 

cm3 cubic centimeter 

ft foot 

ft3

/min cubic foot per minute 

g/m3 gram per cubic meter 

g/mL gram per milliliter 

hp horsepower 

hr hour 

Hz hertz 

in H2O inches of water 

kJ/kg kilojoule per kilogram 

kPa kilopascal 

kW kilowatt 

L/min liter per minute 

m meter 

m3/s cubic meter per second 

mbar millibar 

min minute 

mm millimeter 

mm

2

/s square millimeter per second 

nm nanometer 

Pa pascal 

ppm part per million 

s second 

μg microgram 

μg/cm3 microgram per cubic centimeter 

μg/m3 microgram per cubic meter 

μm micrometer 

% vol percent by volume 

% wt percent by weight 

#/cm3 particle number per cubic centimeter 

°C degree Celsius 

°F degree Fahrenheit 

vi 
EFFECTIVENESS OF SELECTED 

DIESEL PARTICULATE MATTER CONTROL TECHNOLOGIES 

FOR UNDERGROUND MINING APPLICATIONS: 

ISOLATED ZONE STUDY, 2004 

By Aleksandar D. Bugarski, Ph.D.,1

 

1

Mechanical engineer. 

George H. Schnakenberg, Jr., Ph.D.,2

2

Research physicist. 

Steven E. Mischler,3
 

Larry D. Patts,3

3

Physical scientist. 

James D. Noll, Ph.D.,4

4

Research chemist. 

and Jon A. Hummer5
 

5

Engineering technician. 

Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health, Pittsburgh, PA. 

ABSTRACT 

The National Institute for Occupational Safety and Health conducted a study to determine the 

effects of selected, state-of-the-art emission control technologies on the ambient concentrations 

of particulate matter and gases emitted by underground diesel-powered mining equipment. 

Tests were conducted in an isolated zone of an underground mine to evaluate the effectiveness 

of alternative fuel formulations, namely, water-fuel emulsions, blended biodiesel fuels, ultralow 

sulfur diesel fuel, and #1 diesel; and selected exhaust aftertreatment devices, namely, diesel 

oxidation catalysts (DOCs), diesel particulate filter (DPF) systems, and filtration systems 

designed around high-temperature disposable filter elements. 

The results showed that using a cold-weather and warm-weather water-fuel emulsion 

formulation reduced mass concentrations of elemental carbon (EC) by about 70% and 

85%, respectively. The 20% and 50% soy biodiesel blends reduced EC by 49% and 66%, 

respectively. The reductions were slightly less pronounced for the 20% and 50% yellow 

grease biodiesel blends—33% and 56%, respectively. EC concentrations were unaffected 

by using ultralow sulfur diesel in place of #1 diesel. Use of the reformulated fuels did not 

substantially alter the concentrations of nitric oxide and carbon monoxide. However, 

a measurable increase in the nitrogen dioxide (NO2) peak concentration was observed 

during the biodiesel tests. 

The ArvinMeritor (AM) fuel-burner DPF system with a palladium-catalyzed DOC 

reduced EC concentrations by 92%. The diesel filter elements from Donaldson Co., Inc., 

and Filter Service & Testing Corp. reduced the EC concentration of the mine air by 92% 

and 70%, respectively. When the palladium-based DOC was used with the AM DPF, 

it raised the average and peak downstream NO2 concentrations by a factor of three. 

Tests of the AM DPF system with a platinum-catalyzed DOC and CAP/ETG catalytic 

particulate oxidizer system had to be terminated because the elevated NO2 concentrations 

threatened to overexpose the operator. The tests with only a selected DOC also resulted 

in increased NO2 concentrations in mine air. 
2
 

INTRODUCTION 

 

In January 2001, the Mine Safety and Health Administration (MSHA) promulgated rule 

30 CFR6

6

Code of Federal Regulations. See CFR in references. 

 57.5060, which limits exposures of underground metal and nonmetal miners to 

diesel particulate matter (DPM). As a result of this rule, the underground mining 

community is currently working on identifying technically and economically feasible 

controls for curtailing DPM and gaseous emissions from existing and new dieselpowered vehicles in underground mines. To date, the replacement of older diesel engines 

with cleaner modern engines, improvements in mine ventilation, diesel engine 

maintenance, and the implementation of various diesel emission control technologies, 

including diesel particulate filters (DPFs) and reformulated fuels, are some of the tools 

showing potential to control DPM emissions. 

Previous laboratory evaluations [Mayer et al. 1999; Larsen et al. 1999] and underground 

mine tests [Watts et al. 1995; McGinn et al. 2002; Bugarski and Schnakenberg 2001, 

2002] have shown that current DPF technologies can be used to effectively control 

particulate matter emissions from diesel engines. This was further corroborated by the 

results of a series of tests conducted in an isolated zone at Stillwater Mining Co.’s (SMC) 

Nye Mine in southern Montana during the summer of 2003 [Bugarski et al. 2004]. The 

study showed that tested DPF systems caused an undesired increase in the ambient 

concentration of nitrogen dioxide (NO2), potentially introducing a known health hazard. 

This increase in NO2 emissions can be related to the processes promoted by a platinumbased catalyst used by these systems to promote the regeneration of the DPF at relatively 

low exhaust temperatures. This NO2 increase is one of the major technical problems 

affecting implementation of DPFs in underground mines. In addition, the biodiesel 

results from the SMC study [Bugarski et al. 2004] corroborated results of others that neat 

(100% biodiesel) and biodiesel blends with regular diesel fuels were found to reduce the 

concentration of DPM [McDonald et al. 1997] and elemental carbon [Watts et al. 1998; 

68 Fed. Reg.7

7

Federal Register. See Fed. Reg. in references. 

48667 (2003)] in underground mines. 

New control technologies have emerged recently as a result of the high demand for 

aftertreatment systems to control diesel emissions from on-road and off-road vehicles. 

Some of these technologies are in wide use in on-road applications, but have not yet been 

tested for underground mining applications. Two relatively novel technologies, a DPF 

system with a diesel fuel burner developed by ArvinMeritor, Inc., and a flow-through 

catalytic particulate oxidizer (CPO) filtration system distributed in the United States by 

Clean Air Power Ltd., were found to be worth evaluating. In addition, filter systems 

using high-temperature disposable filter elements from Donaldson Co., Inc., and Filter 

Service & Testing Corp., both of which are currently used by the coal mining industry, 

were also selected for close examination in this study. 
Other DPM control strategies of interest are water-fuel emulsions, biodiesel blends, and 

ultralow sulfur diesel fuel. These alternative fuels are currently used by some metal and 

nonmetal underground mines, and there is evidence of their effectiveness from surveys 

conducted by MSHA, but their effectiveness must still be accurately quantified. 

The study reported here was conducted to evaluate the effectiveness of the state-of-the-art 

technologies for controlling DPM and gaseous emissions from underground dieselpowered mining equipment using the isolated zone approach. The study was sponsored 

by the Metal/Nonmetal Diesel Partnership, an industry/labor/government partnership 

formed by the National Institute for Occupational Safety and Health (NIOSH), the 

National Mining Association, the National Stone, Sand and Gravel Association, the 

United Steelworkers of America, the MARG Diesel Coalition, and the Industrial 

Minerals Association–North America. The testing was conducted at the SMC Nye Mine 

in southern Montana from August 31, 2004, to September 9, 2004, by a team of 

researchers from NIOSH and SMC. The suppliers of the filtration systems and the 

reformulated fuels, and the instrumentation manufacturers contributed with technical 

support and in-kind contributions. 

3
 

OBJECTIVE 

The objective of this study was to determine the effects of selected state-of-the-art 

emission control technologies (see Table 1) on the ambient concentrations of diesel 

particulate matter (DPM) and gases emitted by underground diesel-powered mining 

equipment. The technologies were tested in an underground mine using mining vehicles 

that were operated under conditions that closely resembled actual production scenarios. 

This short-term study addressed some limited issues related to the selection and 

implementation of the control technologies on the test vehicles used in the study. 

However, it was not designed to address other important issues related to the 

implementation and operation of diesel particulate filters (DPFs), including cost, the 

integration of various DPF system regeneration schemes into the production cycle, and 

their long-term reliability and durability. Addressing these issues will require long-term 

studies with continuous monitoring of performance of the DPF systems and periodic 

emissions testing. 

The effects of the selected control technologies on concentrations of DPM and gases in 

the mine air were assessed by conducting two groups of tests in the isolated zone at the 

SMC Nye Mine in southern Montana (see Table 1). The first group of tests evaluated 

alternative fuel formulations, namely, water-fuel emulsions, blended biodiesel fuels, 

ultralow sulfur diesel fuel, and #1 diesel. Included in this group were two tests in 

which the muffler was replaced with a standard diesel oxidation catalyst (DOC). 

The second group of tests evaluated DPF systems, namely, the two systems supplied 

by ArvinMeritor and Clean Air Power/Emission Technology Group (CAP/ETG) 

and high-temperature disposable filter elements (DFEs) from Donaldson Co., Inc., and 

Filter Service & Testing Corp. 
Table 1.—Control technologies evaluated in the study 

Test Group 

(Test Vehicle) Exhaust System Fuel Formulation 

Fuel Formulations 50% soy biodiesel and by Muffler 50% #1 diesel blend 

B 

50% soy biodiesel and DOC from DCL International 50% #1 diesel blend 

20% yellow grease biodiesel and Muffler 80% #1 diesel blend 

50% yellow grease biodiesel and Muffler 50% #1 diesel blend 

Muffler ULS (10-ppm sulfur) diesel 

DOC from DCL International ULS (10-ppm sulfur) diesel 

(LHD 1 powered 

Caterpillar 3126

DITA AA) 

Muffler #1 diesel

Muffler 

PuriNOx cold-weather water-fuel 

emulsion 

Muffler PuriNOx warm-weather water-fuel 

emulsion 

Muffler 80% #1 diesel bl

20% soy biodiesel and 

end 

Filtration systems 

(LHD 2 powered by Donaldson disposable filtration 3 #1 diesel element P604516 

Filter Service disposable filtration #1 diesel element 

Clean Air Power/ETG catalytic 

particulate oxidizer (CPO) DPF #1 diesel 

system 

Deutz BF4M101

FC/MVS) 

Muffler #1 diesel

ArvinMeritor fuel-burner DPF 

system with platinum (Pt) DOC #1 diesel 

ArvinMeritor fuel-burner DPF 

system with palladium (Pd) DO #1 diesel C 

4
 
METHODOLOGY 

5
 

VEHICLES AND ENGINES 

SMC selected two load-haul-dump (LHD) vehicles, designated as “LHD 1” and 

“LHD 2,” to serve as test platforms for the study. These Gs were selected because they 

are typical of the SMC Nye Mine production fleet and they were found to be suitable for 

the control technologies to be tested. These LHDs are classified as heavy-duty 

production machines, and their engines are routinely heavily loaded in the course of their 

normal duty cycle. 

The basic specifications for the vehicles and engines are shown in Table 2. 

Table 2.—Test vehicles and engines 

Vehicle 

(Test 

Group) 

Vehicle 

Type 

Vehicle 

Make 

Vehicle 

Model 

Engine 

Make 

Engine 

Model 

Engine 

Displacement, L 

Engine 

Rating, 

kW (hp) 

Engine Type 

LHD 1 

(Fuels) LHD Wagner ST–3.5 Caterpillar 

3126B 

DITA 

AA 

7.243 149 

(200) 

Fully Electronic 

Controlled, 

Turbocharged, 

Air to Air After 

Cooled 

LHD 2 

(Filters) LHD Wagner ST–2D Deutz 

BF4M 

1013 

FC/ 

MVS 

4.764 113 

(151) 

Fully Electronic 

Controlled, 

Turbocharged, 

Air to Air After 

Cooled 

LHD 1, which was powered by a Caterpillar 3126B DITA engine, was selected as a test 

platform for conducting the fuel tests after Caterpillar representatives confirmed that 

engine performance would not be affected by the alternative fuels to be tested. In 

addition, the components of the fuel system on that engine were found to be compatible 

with all of the fuels targeted in this study. The vehicles powered by Deutz engines were 

ruled out as potential test vehicles because these engines were not compatible with waterfuel emulsions. 

LHD 2, used during the study for testing filtration systems, was selected several 

months before the study by mine representatives as a test platform for evaluating the 

ArvinMeritor (AM) DPF system with a diesel fuel burner. The other tested filter systems 

were fitted to vehicle LHD 2, as temporary installations, only for the purpose of 

conducting specific tests. This approach allowed testing of the filtration systems on the 

same vehicle and direct comparison of their performance. 
PREPARATION OF THE VEHICLE FOR THE STUDY 

The Caterpillar 3126B DITA AA engine in LHD 1 was equipped with its original muffler 

for 8 of the 10 tests on fuel formulations. For two of the fuel tests, the engine was fitted 

with a DCL MINE–X catalytic converter, Model #3206–MD. The Caterpillar 3126B 

DITA AA engine has an open crankcase breather that was not filtered in this study. For 

the testing on fuels, the exhaust and oil fumes escaping from the breather are an 

insignificant fraction of total emissions. The different fuels would equally affect the 

exhaust blowby and the main engine exhaust. 

The modifications to LHD 2 for the filter tests were related to the temporary installation 

of various exhaust system configurations. The ArvinMeritor (AM) DPF system had been 

installed on vehicle LHD 2 in January 2004. The other filter systems tested were fitted to 

vehicle LHD 2 as temporary replacements for the AM DPF system specifically for the 

purpose of conducting these tests. A muffler was fitted in place of the AM DPF for the 

test that was conducted to establish a baseline for DPM and gases against which the other 

systems would be compared. The Deutz BF4M1013 FC/MVS engine used in LHD 2 is 

designed with a closed-loop crankcase breather system, which eliminated spurious DPM 

emissions. 

At SMC, skilled maintenance personnel, using an emissions-assisted maintenance 

program, service all vehicles and engines regularly. They made the necessary 

preparations for the tests, including changes on the exhaust systems, in the Nye Mine 

surface shop. 

TESTED FUEL FORMULATIONS 

6
 

The series of tests, which was conducted to evaluate eight different fuel formulations, is 

shown in Table 1. LHD 1 powered by a Caterpillar 3126B DITA AA engine was used 

for the tests. The effects of each fuel formulation were determined by comparing the 

airborne DPM and gas concentrations measured when LHD 1 was fueled with each fuel 

formulation to the concentrations measured when it was fueled with #1 diesel fuel. 

The #1 diesel fuel used in these tests was supplied to the mine by a local refinery (Cenex, 

Columbus, MT). This particular fuel exceeds MSHA requirements (30 CFR 57.5065) for 

diesel fuels used in underground mines. In order to control experimental variation, all of 

the #1 diesel fuel used in this study was obtained from the same process batch. 

Lubrizol Corp., Wickliffe, OH, supplied two formulations of water-in-diesel fuel 

emulsions with the trade name “PuriNOx.” The warm-weather formulation contains 

approximately 77% #2 diesel fuel, 20% water, and 3% proprietary PuriNOx emulsifying 

agent. This formulation is suitable for fueling vehicles when there is no risk of freezing. 

The cold-weather formulation contains approximately 86% #2 diesel fuel, 10% water, 

2% methanol, and 2% of the proprietary emulsifying agent. It is formulated for colder 

climates. The emulsions are prepared in a specialized blending unit developed by 
Lubrizol. It is important to note that, depending on operating conditions and engine 

settings, use of water emulsion can result in a reduction in peak horsepower and torque. 

The samples of cold- and warm-weather formulations were sent to Core Laboratories, 

Inc., Houston, TX, for analysis. The results of the analysis are summarized in Table 3. 

Table 3.—Fuel formulation properties 

Fuel Formulations PuriNOx 

ColdWeather 

PuriNOx 

WarmWeather 

20% Soy 

Biodiesel 

50% Soy 

Biodiesel ULS Fuel 

Properties Method Units 

Aromatics ASTM 

D1319 % vol 22.4 23.7 — — 26.4 

Olefins ASTM 

D1319 % vol 2.3 2.4 — — 1.2 

Saturates ASTM 

D1319 % vol 75.3 73.9 — — 72.4 

Density at 

16 °C 

ASTM 

D4052 g/mL 0.853 0.866 0.836 0.854 0.850 

Sulfur Content ASTM 

D2622 ppm 300 279 205 129 4 

Oxygen By difference % wt 7.8 15.3 4.4 7.4 1.3 

Heat of 

Combustion 

ASTM 

D240 kJ/kg 39,549 36,995 42,042 40,828 42,875 

Flash Point ASTM 

D93 °C 47 — 68 70 64 

Neat soy biodiesel, supplied by Sustainable Systems, LLC, Missoula, MT, was tested as a 

20% and 50% blend with #1 diesel fuel. The neat biodiesel was blended in the desired 

volumetric fractions with #1 diesel at the site using an electronic volumetric flow meter 

from Great Plains Industries, Inc., Wichita, KS. Each fuel blend was stored in a 

designated tank. Samples of each soy fuel blend were collected from the designated fuel 

tank and sent to Core Laboratories, Houston, TX, for analysis. Results of the blends are 

presented in Table 3. West Central, Ralston, IA, the producer of the soy biodiesel, 

reported the following properties for the neat soy biodiesel fuel: free glycerin, 

0.00135%; total glycerin, 0.1995%; flashpoint, 153 °C; sulfur (by ultraviolet fluorescence), 0.00014% by mass; kinematic viscosity, 4.20 mm2

/s; cetane number, 52.7. 

The neat yellow grease biodiesel (Biodiesel G–3000) used in this study was supplied by 

Griffin Industries, Inc., Cold Spring, KY. 20% and 50% blends were obtained by 

blending neat biodiesel with #1 diesel at the site using an electronic volumetric flow 

meter. Each fuel blend was stored in a designated tank. Griffin Industries provided a 

certificate of analysis for the neat Biodiesel G–3000. The properties of this fuel reported 

on the certificate are: free glycerin, 0.01%; total glycerin, 0.096%; flashpoint, >130 °C; 

sulfur, 0.004% by mass; kinematic viscosity, 4.81 mm2

/s at 40 °C; cetane number, 53.9. 

Blends made with yellow grease biodiesel supplied by Griffin Industries were previously 

7
 
evaluated as part of the 2003 isolated zone study at the SMC Nye Mine [Bugarski et al. 

2004]. 

Federated Co-operatives Ltd., Saskatoon, Saskatchewan, Canada, supplied ultralow 

sulfur (ULS) diesel fuel. After the test, a sample of the ULS diesel was collected from 

the auxiliary fuel tank and sent to Core Laboratories for analysis. The results of the 

analysis are shown in Table 3. 

TESTED AFTERTREATMENT SYSTEMS 

The aftertreatment systems evaluated in this study are shown in Table 4. The mine 

vehicle used for these tests was LHD 2 powered by a Deutz BF4M1013 FC/MVS engine. 

Table 4.—Aftertreatment systems 

Filtration System Media Type Catalyst DOC 

ArvinMeritor (AM) 

with Pt DOC Ceramic, Cordierite N/A 

Metal Substrate 

Platinum-Based 

Catalyst 

ArvinMeritor (AM) 

with Pd DOC Ceramic, Cordierite N/A 

Metal Substrate with 

Palladium-Based 

Catalyst 

Donaldson P604516 

High-Temperature 

Disposable Filter 

Element 

N/A N/A 

Filter Service 

High-Temperature 

Disposable Filter 

Element 

N/A N/A 

Clean Air Power/ETG 

CPO 

Deep-Bed Fiber, Quartz 

Silica Fiber 

Precious Metal 

Catalyst-Coated Fibers 

Ceramic Monolith 

Substrate with Precious 

Metal Catalyst 

ArvinMeritor (AM) DPF System 

The DPF system from ArvinMeritor, Inc. (AM), Columbus, IN, (Figure 1) uses an 

integrated fuel burner to perform automatic regeneration of the filter element. In January 

2004, SMC installed this system on LHD 2 for use in production as part of a long-term 

evaluation. Prior to the isolated zone study, this system had accumulated approximately 

470 hr in production. During that period, the fuel burner, acting automatically, 

successfully regenerated the filter element at regular intervals. 

8
 
Figure 1.—ArvinMeritor DPF system. 

DPM filtration by the AM DPF system occurs in an uncatalyzed ceramic wall-flow 

monolith filter element—the DuraTrap RC (Corning, Inc., Corning, NY). The computercontrolled diesel fuel burner is integrated on the inlet side of the DPF element. When 

activated, the burner ignites diesel fuel injected into the combustion chamber to heat the 

engine exhaust and filter element to about 650 °C, a temperature sufficient to consume all 

of the soot that has accumulated on the filter element. This process is called regeneration. The regeneration process can be initiated at predetermined time intervals, or it can 

be triggered by predetermined levels of engine back pressure. The former approach was 

adopted for the system installed on LHD 2. The operation of this system is completely 

automated and transparent to the operator. 

The AM DPF system was tested twice in order to evaluate two different catalyst 

formulations for the DOC following the filter element. The original DOC, used with the 

system on LHD 2, had a platinum-based formulation washcoated onto a substrate. This 

DOC accumulated approximately the same number of hours as the other components of 

the AM DPF system. An earlier study at the Nye Mine [Bugarski et al., forthcoming] 

showed that platinum-based, catalyst-coated DPFs and DPFs in combination with 

platinum-based, catalyst-coated DOCs tend to increase the NO2 concentration in diesel 

exhaust. An alternative DOC, using a palladium-based catalyst applied to a metal 

substrate, was designed to mitigate the NO2 problem. After installing a new Pd DOC 

and prior to testing, LHD 2 was operated for approximately 11⁄2 hr to condition the new 

catalyst. 

9
 
Clean Air Power/ETG Catalytic Particulate Oxidizer (CPO) System 

A Clean Air Power/ETG CPO system Model CPO180 was installed temporarily on 

LHD 2, as shown in Figure 2. The manufacturer, the Emission Technology Group (ETG) 

based in Gothenburg, Sweden, states that the catalytic particulate oxidizer (CPO) uses 

filter cartridges made of catalyzed silica fibers that are able to catalytically oxidize 

carbon particles at low temperatures without actually trapping them on a filter. The 

system consists of two units, a CPO followed by a DOC, and was installed under the 

guidance of the distributor. 

After installing the system, the Clean Air Power/ETG CPO was conditioned by operating 

the vehicle for approximately 2 hr outside of the mine. After testing, the system was 

removed from the vehicle. 

10
 

Figure 2.—Clean Air Power/ETG CPO system. 
Filtration System With Disposable Filter Element 

From Donaldson (Model P604516) 

In order to test the high-temperature disposable filter element (DFE) (part No. P604516 

from Donaldson Co., Inc., Minneapolis, MN), it was installed temporarily on LHD 2, 

as shown in Figure 3. The DFE was contained within a stainless steel housing that was 

originally designed for filter elements from Filter Service & Testing Corp., Price, UT. 

The dimensions of the Filter Service DFE are almost identical to those of the Donaldson 

element. The housing was designed and built by Mac’s Mining Repair of Huntington, UT, 

and was supplied for this study by SMC East Boulder Mine personnel, who were 

evaluating the disposable filter concept for reducing miners’ exposures to DPM. 

 Figure 3.—Filtration system used in testing high-temperature disposable 

elements from Donaldson and Filter Service. 

The pleated DFE is classified as a deep-bed filter consisting of a thin felt or woven mat of 

fibers. The fibers collect soot throughout their depth and as a rule become more efficient 

as the filter loading increases and the pathways through the filter become smaller and 

more restrictive. The filter medium is highly porous and creates relatively low exhaust 

back pressure when new. Because the filter material can withstand temperatures as high 

as 760 °C (1,400 °F), this DFE is finding use in some applications for filtering relatively 

hot exhaust that is not cooled by a water scrubber or other types of heat exchangers. 

At the time of the test, this DFE was on the MSHA list of DPM control technologies, 

with a recommended temperature limit of less than 343 °C (650 °F) [MSHA 2005]. 

Prior to testing, the vehicle was operated for approximately 2 hr inside the mine to 

condition the new filter element. 

11
 
Filtration System With Disposable Filter Element 

From Filter Service & Testing Corp. 

A prototype of the high-temperature DFE from Filter Service was similar in dimensions, 

design, and physical properties to the Donaldson P604516 DFE. The filter material was 

constructed from high-temperature fiberglass medium. At the time of the isolated zone 

testing, the Filter Service DFE was not on the MSHA list of DPM control technologies 

[MSHA 2005]. 

For testing, the Filter Service DFE was placed in a housing temporarily installed on the 

LHD 2 test vehicle, the same installation used to test the Donaldson DFE (Figure 3). 

Prior to testing, the vehicle was operated for approximately 3 hr outside and inside the 

mine to condition the new DFE. 

FUELING PROCEDURES 

For the fuel tests, the LHD 1 tank was filled with test fuels at a fueling station (Figure 4) 

located in a crosscut in the isolated zone approximately midway between the upstream 

and downstream sampling stations. Having test fuels in the test zone eliminated the need 

for dismantling the upstream sampling station between consecutive reformulated fuel 

tests. For the filter tests, fueling of LHD 2 with #1 diesel was done from a temporary 

fueling station established outside the portal. 

A hand pump, with an electronic fuel flow meter from Great Plains Industries, Inc., 

Wichita, KS, was used to transfer fuels from the drums to the auxiliary fuel tank on the 

test vehicle (Figure 5). The auxiliary tank was topped off after the warmup cycles were 

completed and just before the start of the test run. Fuel consumed during each test was 

roughly determined by subtracting, at the end of the test, the volume of fuel remaining in 

the auxiliary tank from the tank capacity. This method was not found to be sufficiently 

accurate to provide meaningful data on fuel consumption. Results are therefore not 

reported. 

12
 
Figure 4.—Fueling station in the isolated zone. 

Figure 5.—Auxiliary tank on LHD 1. 

13
 
Precautions were taken to avoid cross-contamination of the fuels from consecutive fuel 

tests. Between tests, the auxiliary tank was drained and the fuel filter was replaced with a 

new one. After filling the emptied auxiliary tank with the desired test fuel, the vehicle 

fuel system was purged by operating the vehicle for two full cycles in the isolated zone 

prior to the start of the test. During this process, the excess fuel from the fuel system was 

diverted to the primary vehicle fuel tank. After completing two purge cycles, the 

auxiliary tank was refilled with test fuel, the return line was diverted back to the auxiliary 

tank, and the test run was started. 

ISOLATED ZONE TESTING 

The objective of this study was to evaluate the performance of selected control 

technologies using isolated zone testing. Isolated zone tests are designed to be a 

compromise between the genuineness of in situ measurements of concentrations and 

corresponding exposures, and the repeatability and accuracy of the emission 

measurements obtained under research laboratory conditions. When carefully designed, 

as were the tests at the SMC Nye Mine, isolated zone tests allow the operation of vehicles 

under conditions and over duty cycles that closely mimic actual production duty cycles. 

In addition, artifacts usually generated under laboratory conditions while attempting to 

simulate real-life conditions and processes do not compromise such tests in an isolated 

zone in a mine. Finally, isolated zone test measurements are not confounded by 

emissions from other vehicles and variability in ventilation as would occur in tests 

conducted in real production areas. 

The effects of each of the selected control technologies on DPM and gas concentrations 

in the mine air were estimated from the measurements taken while each test vehicle was 

operated within the isolated zone with and without control technologies. In general, 

corrections for the background concentrations of the pollutants were made by subtracting 

the results of measurements performed at the upstream end of the zone from the 

corresponding results obtained at the downstream end of the isolated zone or on the 

vehicle. The efficiency of any technology tested was determined by comparing the 

pollutant concentrations determined when the technology was used to those 

concentrations resulting from operating the same vehicle over the same duty cycle with a 

standard muffler and fuel, i.e., the baseline configuration. 

Test Site 

The 530-m (1,739-ft) isolated zone was located in 52E ramp in the east section of the 

SMC Nye Mine. The upstream end of the zone was situated approximately 150 m 

(492 ft) from the portal and the entry point of fresh air. The elevation of the portal is 

approximately 1,525 m (5,000 ft) above sea level. The location of the isolated zone 

relative to the portal is shown in Figure 6. The average cross-sectional dimensions of the 

isolated zone drift were approximately 2.7 m (9 ft) wide by 3.6 m (12 ft) high. The ramp 

has a 9% rise toward the downstream end. 

14
 
Figure 6.—Isolated zone, 52E entry, SMC Nye Mine. 

The site selected for the isolated zone met the following requirements: 

1.	 It is isolated from other parts of the mine where diesel-powered equipment is 

used. 

2.	 It is ventilated with fresh air directly from the mine portal. 

3.	 The quality and quantity of the air are not compromised by portal traffic. 

4.	 The zone is sufficiently long and the opening is relatively small to ensure 

thorough air mixing at the planned ventilation rates and uniform contaminant 

distribution across the drift at the downstream sampling station. 

5.	 The ventilation controls allow for adjustment and maintenance of relatively 

constant average air quantities during the tests. 

6.	 Electric power to operate equipment and instrumentation is available at the 

downstream and upstream sampling stations. 

A schematic of the isolated zone is shown in Figure 7. The two tested LHD vehicles 

were operated over a simulated duty cycle between two stopes, one at the upstream and 

one at the downstream load/dump points, which were approximately 300 m (984 ft) apart. 

The upstream sampling station was located approximately 90 m (295 ft) upstream of the 

upstream load/dump point. The downstream sampling station was located approximately 

140 m (459 ft) downstream of downstream load/dump point. A third sampling point was 

located on the vehicle. The ventilation control doors were located approximately 60 m 

(197 ft) downstream of the downstream sampling station. The stopes at the upstream and 

downstream load/dump points were approximately 8 m (26.2 ft) deep. Sufficient 

quantities of waste rock were available in the stopes to support load and dump actions. 

The refueling station was located in one of the sealed stopes approximately halfway 

between the upstream and downstream load/dump points. 

15
 
Figure 7.—LHDs in the isolated zone (not to scale). 

16
 
Duty Cycles 

A defined, conservative, simple, and repeatable duty cycle for the LHD vehicles, 

schematically represented in Figure 7, was developed by NIOSH personnel and 

experienced vehicle operators from the SMC Nye Mine. The test cycle simulated a 

production cycle typical for the LHD equipment. 

The duty cycle consisted of two very similar load/dump tasks, one occurring at each of 

the load/dump points, and two tramming events, occurring between those points. The 

LHD started its cycle just upstream of the upstream load/dump point with the bucket, 

loaded with waste rock, facing downstream. The operator first turned the vehicle into the 

upstream stope, unloaded the bucket, retreated for the length of the vehicle, then 

advanced forward and loaded the bucket again. Next, the operator backed the vehicle out 

of the stope, retraced its path, and then advanced up the ramp (downstream) for two 

vehicle lengths beyond the stope just vacated, and then stopped. At this location, the 

operator raised the bucket (engaging the hydraulics) to simulate loading of an imaginary 

truck but without dumping the bucket, then lowered the bucket and backed the vehicle to 

the starting point of the cycle. This upstream loading operation was repeated three times. 

After the third execution, the loaded LHD vehicle trammed up the ramp to the 

downstream load/dump point. The LHD executed the same three load/dump tasks that 

had been performed at the upstream location. After the final load/dump task at the 

downstream point, the loaded vehicle trammed down the ramp to the upstream starting 

point, thus completing one test cycle. The next cycle was started immediately. 

In each test, two full warmup cycles were executed prior to the start of sampling. The 

duration of a typical cycle for LHD 2 was 13–15 min depending on the operator; the 

duration for LHD 1 was 11–12 min. The duration of a test was dictated by the time 

required for collecting sufficient DPM samples. When it was determined that the test had 

run for a sufficient time, it was terminated after completion of the next full cycle. 

The same operator operated LHD 1 throughout all fuel tests, including the baseline test. 

Two operators drove LHD 2. One miner operated the vehicle for both tests of the 

AM DPFs (with platinum and palladium DOCs). The other miner operated the vehicle 

for the baseline test, the tests of the disposable filter elements from Donaldson and Filter 

Service, and the Clean Air Power/ETG CPO system test. 

Ventilation 

The isolated zone was ventilated with fresh air from the portal. Since diesel-powered 

vehicles were not operated upstream of the test zone during the tests, the level of 

diesel contamination of the ventilation air upstream of the test zone was expected to 

be very low. The intent was to maintain the same ventilation rate of about 19 m3

/s 

(40,259 ft3

/min) for all tests. This amount of air was assumed to provide relatively stable 

airflow and good mixing of the pollutants. It is important to note that the ventilation rate 

maintained in the main drift during these tests was significantly higher than the 

17
 
ventilation rate supplied by the mine for similar vehicles/engines during production. 

Auxiliary ventilation was not supplied to the stopes at the upstream and downstream 

load/dump points. 

SAMPLING AND MEASUREMENTS METHODOLOGY 

Sampling Stations 

For this study, three sampling stations were established in the isolated zone: the upstream 

station, the downstream station, and the vehicle station. 

Upstream Sampling Station 

The upstream sampling station was located approximately 90 m (295 ft) upstream of 

the upstream load/dump point. The following methods were used to determine 

concentrations of the particulate matter in the incoming fresh air at the upstream station: 

1.	 A standard sampling method (SSM) was used to collect particulate samples for 

carbon analysis (NIOSH Analytical Method 5040) [Schlecht and O’Connor 

2003a]. 

2.	 A high-volume (HV) sampling method was used to collect particulate samples for 

carbon analysis (NIOSH Analytical Method 5040). 

3.	 A standard sampling method was used to collect filter samples for sulfate ion 

analysis (NIOSH Analytical Method 6004) [Schlecht and O’Connor 2003b]. 

4.	 A TEOM Series 1400a ambient particulate monitor from Rupprecht & Patashnick 

Co., Albany, NY, was used for real-time measurements of total particulate matter 

under 0.8 μm. 

5.	 The scanning mobility particle sizer (SMPS) from TSI, Inc., St. Paul, MN, was 

used to measure size distribution and count concentrations of aerosols. 

The following instrumentation was used to measure concentrations of the selected gases 

at the upstream station: 

1.	 The ITX multigas monitor from Industrial Scientific, Oakdale, PA, was used for 

real-time measurements and recording of concentrations of carbon monoxide 

(CO), nitric oxide (NO), and nitrogen dioxide (NO2). 

2.	 The RKI Eagle monitor from RKI Instruments, Inc., Hayward, CA, was used for 

measuring concentrations of carbon dioxide (CO2). 

Downstream Sampling Station 

The downstream sampling station (see Figure 8) was established approximately 140 m 

(459 ft) downstream of the downstream load/dump point and 60 m (197 ft) upstream of 

the ventilation doors. The following methods were used to determine concentrations of 

particulate matter in the contaminated air at the downstream station: 

18
 
1.	 The SSM procedure was used to collect particulate samples for carbon analysis 

(NIOSH Analytical Method 5040). 

2.	 The HV sampling procedure was used to collect particulate samples for carbon 

analysis (NIOSH Analytical Method 5040). 

3.	 The HV sampling procedure was used to collect particulate samples for 

gravimetric analysis. 

4.	 The SSM procedure was used to collect filter samples for sulfate ion analysis 

(NIOSH Analytical Method 6004). 

5.	 The TEOM Series 1400a ambient particulate monitor was used for real-time 

measurements of total particulate matter under 0.8 μm. 

6.	 The SMPS was used to measure size distribution and count concentrations of 

aerosols. 

7.	 A Photoelectric Aerosol Sensor (PAS) 2000 real-time polycyclic aromatic 

hydrocarbon (PAH) monitor from EcoChem Analytics, West Hills, CA, was used 

for qualitative monitoring of elemental carbon (EC) concentrations in real time by 

virtue of PAHs attached to the carbon particles. 

The following instrumentation was used to measure concentrations of the selected gases 

at the downstream station: 

1.	 The iTX multigas monitor was used for real-time measurements and recording of 

concentrations of CO, NO, and NO2. 

2.	 The RKI Eagle monitor was used for real-time measurements and recording of 

CO2 concentrations. 

19
 

 Figure 8.—Downstream sampling station showing instrumentation and wire grid supporting DPM 

samplers, anemometer, iTX gas monitor, and RKI Eagle CO2 monitor. 
Vehicle Sampling Stations 

A vehicle sampling station was established on each test vehicle. The stations were 

located approximately 2 ft from the operator. At this sampling location, the standard 

sampling procedure was used to collect particulate samples for carbon analysis. The iTX 

multigas monitor and RKI Eagle CO2 monitor were used to sample and record gas 

concentrations. 

Sampling Strategy 

The following procedure was established for sampling in the isolated zone: 

1.	 The vehicle was driven to the fueling station prior to the test and the auxiliary 

tank topped off with fuel. While the vehicle was fueled, the operator was briefed 

on the details of the test protocol and instructed on the duty cycles. 

2.	 After refueling was completed, the operator performed two warmup cycles. 

3.	 As the vehicle passed the fueling station near the end of the second warmup cycle, 

the auxiliary tank was topped off and the vehicle proceeded to the upstream 

load/dump point, where it was stopped. The particulate matter samplers and all 

real-time sampling instrumentation on the vehicle were turned on. At this time, 

the test officially began. 

4.	 At approximately the same time, the upstream sampling systems were turned on. 

5.	 After a short delay, sampling at the downstream station was started. The realtime trace of the EC concentration measured by the PAS 2000 instrument was 

used to determine start time. 

6.	 The objective was to collect at least 30 μg of elemental carbon on the HV 

sampling filters used at the downstream sampling station. The duration of a test 

was estimated from the real-time measurements of particulate concentrations at 

the downstream sampling station using the TEOM 1400a. The actual stop time 

was determined by using the real-time trace of EC concentrations from the PAS. 

7.	 Shortly thereafter, when the vehicle reached the upstream load/dump point, 

the vehicle and the upstream sampling stations were stopped and the test was 

terminated. 

8.	 The actual start and stop times and total sampling times were recorded. 

Sampling Methodology and Instrumentation 

Following is a description of the various equipment, instrumentation, and methods used 

in this study to collect particulate samples and directly measure concentrations of 

particulates and selected gases. 

Standard Sampling of DPM for Carbon Analysis 

A standard sampling method similar to the one used by MSHA for DPM compliance 

monitoring was used to collect DPM samples for carbon analysis at the downstream, 

upstream, and vehicle sampling stations during the fuel tests. The samples on the vehicle 

were collected in duplicate; the samples at the upstream and downstream stations were 

20
 
collected in triplicate. The 1.7 L/min sampling flow rate used by this method is 

inadequate for obtaining DPM samples in cases where the concentration of DPM is low 

and sampling times are short. Therefore, this method was not used to collect samples 

during the tests on the filtration systems. 

The sampling train used at the vehicle sampling station consisted of a flow-controlled 

Escort ELF Sampling Pump from Mine Safety Appliances Co. (MSA), Pittsburgh, PA; 

and a 10-mm Dorr-Oliver Cyclone and SKC DPM Cassette, both from SKC, Inc., 

Eighty Four, PA. The SKC DPM Cassette contains a single-stage impactor and two 

stacked 37-mm-diam tissue quartz-fiber filters. The pumps were operated at 1.7 L/min. 

At this flow rate, only aerosols with an average aerodynamic diameter (D50) smaller than 

0.820 μm reached the collection filter [Olson 2001]. The pumps were calibrated at the 

mine at the beginning of the study. The flow rate for each of the sampling pumps was 

measured and recorded daily using a Gilibrator-2 bubble flow meter from Sensidyne, 

Clearwater, FL. 

At the downstream and upstream sampling stations, a Model 0523–101Q high-volume 

rotary vane pump from Gast Manufacturing, Inc., Benton Harbor, MI, and a manifold 

with a bank of critical orifices with a nominal flow rate of 1.7 L/min were used instead of 

an MSA Escort ELF Sampling Pump to maintain and control the flow rate. 

High-volume (HV) Method for Sampling DPM for Carbon Analysis 

During all tests conducted in this study, an HV sampling method was used to collect three 

DPM samples at the downstream and two DPM samples at the upstream sampling 

stations. This high-volume sampling train, described in detail elsewhere [Bugarski et al. 

2004], was used to enhance the collection of samples for carbon analysis by increasing 

the sampling flow rate and decreasing the collection area of the filter. The sampling flow 

rate was increased by merging into a single stream flows from five preclassifiers, each 

consisting of a 10-mm Dorr-Oliver Cyclone followed by a U.S. Bureau of Mines 

(USBM) single-stage diesel impactor. A flow rate of approximately 2.0 L/min was 

maintained through each cyclone and impactor pair. At this sampling flow rate, only 

particles with geometric mean smaller then 0.775 μm were deposited on the filters [Olson 

2001]. All five preclassifiers were attached to a symmetrical plenum that distributed a 

total flow rate of approximately 10.0 L/min uniformly among the five streams. Each 

preclassifier assembly was connected to the plenum chamber by a 3-ft-long section of 

conductive tubing. The outlet of the plenum was directly connected to a stainless steel 

25-mm-diam filter holder containing two stacked 25-mm tissue quartz-fiber filters 

(Tissuquartz 2500 QAT–UP, Pall Corp., Ann Arbor, MI). 

The total sampling mass flow rates were maintained using a Model HFC 302 mass 

flow controller from Teledyne, Hampton, VA, in each of the three sampling lines from 

the 25-mm-diam filter holders. The total volumetric flow rates through each of the 

sampling streams were measured periodically by inserting a Gilibrator-2 bubble flow 

meter inline, between filter holders and mass flow controllers. The volumetric flow 

rates measured during this study were all corrected to ambient conditions. A Model 

0523–101Q high-volume rotary vane pump from Gast Manufacturing was used to draw 

the sample through the filter. 

21
 
Sampling DPM for Gravimetric Analysis 

A similar high-volume sampling method was used to collect gravimetric samples. These 

were collected using a sampling train consisting of a 10-mm Dorr-Oliver Cyclone, 

a USBM single-stage impactor, and a cassette filter holder with a single 37-mm-diam 

Teflon filter (Teflo, 2.0 μm) from Pall Corp. A manifold with five critical orifices, each 

with a nominal flow rate of 1.7 L/min, was used to maintain a constant flow rate. The 

inlets of the five orifices were connected to a common sampling line to yield a total flow 

of 8.5 L/min through the 37-mm-diam filter. A Model 0523–101Q high-volume rotary 

vane pump from Gast Manufacturing provided suction to the manifold. The total 

particulate matter (TPM) collected on the filters had a D50 smaller than 0.820 μm. The 

total flow rate through the sampling train was determined at the NIOSH Pittsburgh 

Research Laboratory (PRL) and checked periodically during the study using a 

Gilibrator-2 bubble flow meter. 

Sampling DPM for Sulfate Analysis 

The sampling train for sulfate samples consisted of a 10-mm Dorr-Oliver Cyclone; 

a USBM single-stage impactor; a cassette filter holder with a single 37-mm-diam 

cellulose ester membrane filter Model AAWP03700, Millipore Corp., Bedford, MA; 

a critical orifice with a nominal flow rate of 1.7 L/min; and the Model 0523–101Q highvolume rotary vane pump from Gast Manufacturing. The DPM collected on the filters 

had a D50 smaller than 0.820 μm. The total flow rate through the sampling system was 

calibrated at NIOSH PRL and checked periodically during the study using a Gilibrator-2 

bubble flow meter. 

DPM Concentration Measurements With a TEOM Series 1400a 

Ambient Particulate Monitor 

Two TEOM Series 1400a ambient particulate monitors from Rupprecht & Patashnick 

Co. were used to continuously measure concentrations of TPM with a D50 smaller than 

0.820 μm. One TEOM was located at the upstream station, the other at the downstream 

sampling station. 

The TEOM draws air through a filter at a constant flow rate while continuously 

measuring the mass accumulating on the filter and calculating near-real-time mass 

concentrations. The sample stream is drawn through the filter from a hollow tapered 

element that is connected to the suction side of the sampling system. The vibration 

frequency of the tapered element decreases as particulate mass collected on the filter 

increases. By frequently measuring the tapered-element frequency, the TEOM calculates 

the increase in mass of the sample that has accumulated on the filter. The concentration 

of TPM is calculated by dividing the accumulated mass by the volume of airflow across 

the filter during the period over which the frequency change is measured. 

The flow through the instrument is maintained at a constant rate by a mass flow 

controller. The flow is corrected for temperature and barometric pressure. Internal 

22
 
instrument temperatures are controlled to minimize the effects of ambient temperature. 

To prevent condensation and ensure that the sample filter always collects particulates 

under similar conditions, the TEOM intake is heated to maintain the sampling stream at 

50 °C. 

During this study, the flow rates on both the upstream and downstream TEOM were set at 

1.7 L/min. A cyclone and impactor were used as preclassifiers to the TEOM, allowing 

only particles with an average aerodynamic diameter (D50) smaller than 0.820 μm to 

reach the collection filter. The average ambient concentrations of TPM were recorded 

and saved every 10 s. The reported average concentrations for a test were obtained from 

the difference in filter masses recorded at the same start and stop times used by the 

particulate samples for carbon analysis. 

Measurement of Size Distribution and Particle Number Concentrations 

Using a Scanning Mobility Particle Sizer (SMPS) 

Two SMPSs, one at the downstream sampling station and the other at the upstream 

sampling station, were used to periodically measure the size distribution and number of 

particles in the range of 10–392 nm. The SMPS at the upstream end of the isolated zone 

was built by TSI, Inc., and consisted of a Model 3080L electrostatic classifier and a 

Model 3010 condensation particle counter (CPC), both from TSI, Inc. The SMPS at the 

downstream sampling station consisted of a Model 3080L electrostatic classifier and a 

Model 3025A CPC, both from TSI, Inc. 

The flows of monodispersed aerosol in both electrostatic classifiers were maintained at 

0.6 L/min throughout the study. At the established polydispersed aerosol flow rate of 

6 L/min, the inlet impactor had a cutoff point of 460 nm. The CPC was operated in highflow mode to minimize diffusion losses. The sampling was performed using a 90-s 

up-scan and a 15-s down-scan. The instrument was operated using a dedicated laptop 

computer and Aerosol Instrument Manager Software from TSI, Inc. 

Although the vehicle duty cycles for all tests were transient, the resulting aerosol 

distributions in the mine air were made quasisteady by relative movements of the 

vehicles and ventilation air. The effects of the tested control technologies on size 

distribution and count concentrations of aerosols in mine air were assessed based on the 

analysis performed on the measurements conducted while the test vehicle was performing 

the portion of the duty cycle at the downstream load/dump point—a point closest to the 

location of the SMPS. 

The measurements performed during other portions of the duty cycle showed that the 

distributions and count concentrations of aerosols were extremely dependent on the 

position of the vehicles relative to the downstream instrument. This was a result of many 

time-dependent factors such as the engine emissions, the velocity of the air, the velocity 

of the vehicle, the ventilating of the upstream and downstream load/dump points, and the 

travel time of the plume. 

23
 
Measurement of Concentration of O2, CO, NO, and NO2 Using an 

Industrial Scientific iTX Multigas Monitor 

The ambient concentrations of oxygen (O2), carbon monoxide (CO), nitric oxide (NO), 

and nitrogen dioxide (NO2) were measured at all three sampling locations using Industrial 

Scientific iTX multigas monitors. One iTX multigas monitor was dedicated to each 

sampling location for the duration of the isolated zone testing. The iTX measured 

ambient concentrations every 10 s and stored them in its memory. 

The iTX is a diffusion gas monitor based on electrochemical cell technology 

implemented in such a way as to measure concentrations independent of atmospheric 

pressure. The instrument continuously monitors and simultaneously displays all gases 

sampled. The concentration data were downloaded to a laptop PC at the end of each 

test day. 

The iTX gas monitors were calibrated with certified concentrations of Industrial 

Scientific calibration gases prior to and upon completion of the isolated zone testing. 

Each iTX was checked daily using the iTX DS1000 Docking Station. The iTX DS1000 

Docking Station is an automated instrument management system that consists of a master 

control and PC interface station. The Docking Station provides automatic calibration and 

instrument diagnostics and maintains instrument database records. 

Measurement of CO2 Concentration Using an RKI Eagle CO2 Monitor 

The ambient concentrations of carbon dioxide (CO2) were measured at all three sampling 

stations using an RKI Eagle infrared CO2 monitor. Ambient concentrations were 

measured every 60 s and recorded using data-logging capabilities of the instrument. The 

data were downloaded to a laptop PC at the end of each day. 

Since the instrument uses the infrared method, it reports the CO2 partial pressure at the 

prevailing barometric pressure (~84 kPa). In the postprocessing procedure, the results of 

the measurements were corrected to represent the equivalent CO2 concentrations at the 

standard barometric pressure conditions (105

 Pa). The correction was made using the 

results of calibration at NIOSH PRL and periodic checks in the isolated zone with 

2,000 ppm CO2 calibration gas supplied by RKI. 

Measurement of Exhaust Temperatures and Engine Back Pressure 

During tests, the exhaust temperatures upstream of the DPF systems were measured 

continuously using a Model KMQSS–125G–6, K-type thermocouple from Omega 

Engineering, Inc., Stamford, CT. The engine back pressure was measured using a 

Kavlico Model P356 differential pressure sensor from Kavlico Corp., Moorpark, CA. 

The output from the thermocouples and pressure sensors were logged at a rate of 0.2 Hz 

using a MiniLogger portable data-logging system from Logic Beach, Inc., La Mesa, CA. 

The logged data were retrieved using a laptop PC and the supplied HyperWare software. 

24
 
Measurement of Ambient Temperature and Barometric Pressure 

The ambient temperature and barometric pressure were measured and recorded by the 

TEOM 1400a. 

Measurements of Ventilation Rate 

Air velocities in the isolated zone were measured continuously during the tests in the 

approximate center of the drift at the downstream sampling station using an Anemosonic 

UA6 digital ultrasonic anemometer from Airflow Developments Ltd., High Wycombe, 

United Kingdom. The anemometer sensor was located in the center of the steel grid 

supporting the DPM samplers. Anemometer output was sampled every 2 s. A fivesample average was computed and stored into memory, creating a log of 10-s averages 

using a MiniLogger portable data-logging system from Logic Beach, Inc. The logged 

data were retrieved using a laptop PC and the supplied HyperWare software. 

The logged air velocities were converted to air quantities by adding or subtracting the 

correction factor to the velocity obtained and then multiplying that velocity by the crosssectional area of the entry at the point of measurement. The average air velocity for a test 

was determined by averaging all of the downstream air velocity readings over the period 

for downstream DPM sampling. All measured concentrations of particulate matter and 

gases for a control technology test were adjusted for differences between the prevailing 

test ventilation and that of the corresponding baseline test. This adjustment enabled the 

comparison of the results obtained from different tests. 

The air velocities were periodically verified using a vane anemometer to conduct a 

moving traverse across the entry. 

ANALYSIS OF SAMPLES 

Analysis of DPM Samples Collected Using 

Standard and High-volume Sampling Methods 

for Elemental Carbon Content 

The samples that were collected on quartz-fiber filters, using the standard and the highvolume sampling procedures, were analyzed by the NIOSH PRL analytical laboratory for 

elemental carbon content using the NIOSH Analytical Method 5040 [Schlecht and 

O’Connor 2003a; Birch and Cary 1996]. The analysis was performed following the 

carbon analyzer procedures from Sunset Laboratories, Forest Grove, OR. A blank (heattreated quartz-fiber filter) and a sugar standard were run daily before analysis of the 

samples. 

Calibrated punches were used to remove a section from the exposed area of each sample 

filter. A punch with a surface area of 0.72 cm2

 was used for heavily loaded samples, 

while a 1.5-cm2

 punch was used for all other samples. The resulting section was placed 

into the oven of the carbon analyzer and analyzed following the procedure described in 

25
 
the NIOSH Manual of Analytical Methods [Schlecht and O’Connor 2003a] and by Birch 

and Cary [1996]. 

The temperature steps for the organic carbon (OC) portion were set to 200, 450, 650, and 

870 °C. The time spent at each temperature step was increased from that specified in the 

NIOSH method so that peaks for both the OC and elemental carbon (EC) could be fully 

resolved. This is a standard procedure at NIOSH PRL and has been determined to give 

results identical to the method specified in the NIOSH Manual of Analytical Methods. 

NIOSH Analytical Method 5040 analyzes for OC and EC in two different stages. In the 

first stage, the OC evolves as the instrument ramps the oven temperature up over four 

progressively higher temperature steps in a pure helium (He) atmosphere. The EC does 

not evolve in the pure helium atmosphere. The evolved OC is oxidized to carbon dioxide 

(CO2), reduced to methane (CH4), and finally measured using a flame ionization detector 

(FID). 

In the second stage, the oven temperature is reduced to approximately 600 °C. The EC is 

evolved as the instrument steps the oven temperature back up to approximately 900 °C in 

a He/O2 atmosphere. Because of the O2, EC is oxidized to CO2, which is consequently 

reduced to CH4 and measured with the FID. NIOSH Analytical Method 5040 also 

corrects for the pyrolysis of OC and carbonates. 

Gravimetric Analysis of DPM Samples 

The filters collected for gravimetric analysis were weighed in the NIOSH PRL weighing 

room. The cassettes with exposed filters were brought into the environmental chamber/ 

weighing room where they were unsealed, desiccated for at least 30 min, and then 

conditioned at 20 °C and 50% relative humidity for at least another 30 min. After the 

equilibration, the filters were removed from the cassettes and weighed. Each filter was 

placed on an NRD Model 2U500 antistatic strip for 30 s and finally onto a Mettler Model 

MT5 balance. The reading of the balance was recorded after a 60-s period. 

Each of the filters was preweighed after conditioning prior to the tests, then reconditioned 

and weighed twice in a 2-week period after the tests. 

Analysis of Filter Samples for Sulfate Ion Concentrations 

Sulfate ion concentrations on filter samples were analyzed by DataChem Laboratories, 

Inc., Salt Lake City, UT, by ion chromatography (IC) according to NIOSH Analytical 

Method 6004. The samples were analyzed using a Dionex Model DX300 ion 

chromatograph equipped with a Hewlett-Packard 1050 autosampler and TotalChrom 

Client/Server chromatography software from PerkinElmer, Inc. 

26
 
 

CALCULATION OF THE EFFECTS OF CONTROL TECHNOLOGIES 

The effects of each of the tested control technologies were determined by comparing 

the results of tests with and without control technologies. Each of the comparisons 

contrasted tests using the same vehicle, with the same duty cycle and operator, 

if possible, and the same ventilation rate. The test of LHD 1 using #1 diesel and a 

standard muffler was used to establish a baseline for the fuel tests. The test with LHD 2 

using #1 diesel with a muffler was used to establish a baseline for the filter tests. The 

effects of a specific control technology were quantified by comparing the contaminant 

concentrations observed for the test when the vehicle was operated with a control 

technology with those observed for the baseline test. 

The concentrations of selected pollutants at the upstream, downstream, and vehicle 

sampling stations were determined using various sampling and measurement methods. 

Due to the nature of the test environment and methods, small variations in operating 

conditions were possible between tests, including variations in the ventilation rate, air 

temperature, etc. The data show that ventilation rate differences between tests could be 

the greatest source of uncertainty for the concentration measurements. However, this 

factor of uncertainty can be eliminated by correcting all measured concentrations for 

ventilation rate. The calculations for these corrections are presented below. 

For the purpose of these analyses, the tests conducted in this study were divided into two 

groups, as shown in Table 1 and described earlier. In order to allow a direct comparison 

of the results between the tests within each test group, the measured concentrations (ci) 

were corrected to the average ventilation rate (VR) for the baseline tests for each of the 

two groups (VRbaseline LHD 1 and VRbaseline LHD 2) using Equation 1: 

3

m VR [ ] g g i 

s ci,VR [ 3 ] = ci [ 3 ]× 3 Equation 1 

m m m VR [ ] baseline 

s 

The net contribution of the tested vehicle/technology configuration to the air 

concentrations of pollutants (Ci) was calculated by subtracting the concentrations 

measured at the upstream sampling station (ci,UP) from the ventilation-adjusted 

concentrations at the downstream sampling station (ci, VR,,DOWN): 

g g g Ci [ 3 ] = ci,VR,DOWN [ 3 ] − ci,UP [ 3 ] Equation 2

m m m 

Similarly, the net contribution of the tested configuration to the exposure of the operator 

was estimated by subtracting the upstream concentrations from the ventilation-adjusted 

concentrations measured at the vehicle. 

27
 
In cases where the analysis of the upstream data showed that the upstream concentrations 

of the measured pollutant were below the detection limit of the method or instrumentation, the background concentrations were assumed to be negligible. 

The net contributions were then used to calculate the relative effects of the tested control 

technologies on the concentrations of the monitored pollutants: 

⎛ C ⎞ ControlTechnologyEffect for C [%] =
 ⎜1 −
 i ⎟ i ×100
 Equation 3 ⎜ C ⎟ ⎝ i BL ⎠

where Ci is the net contribution of the vehicle to the air concentrations of pollutant for the 

control technology test and Ci BL is the net contribution of the vehicle to the air concentrations of pollutant for the baseline test. 

28
 
RESULTS AND DISCUSSION 

An overview of the two groups of tests conducted during this study is presented in 

Table 5. Results of those tests are reported in two separate sections. The first section 

discusses results from the 10 tests designed to evaluate the effects of selected fuel 

formulations on concentrations and characteristics of particulate matter and selected 

gases. The second section discusses results of filter tests conducted to establish the 

effects of selected diesel particulate filter (DPF) systems and disposable filtration 

elements on concentrations and characteristics of the same pollutants. 

29
 

Table 5.—Tests conducted during the study 

Test Type Exhaust System Fuel Formulation Comments 

Fuel Tests 

(LHD 1) 

Muffler #1 diesel Completed

Muffler PuriNOx cold-weather 

water emulsion Completed 

Muffler PuriNOx warm-weather 

water emulsion Completed 

Muffler 20% soy biodiesel and 

80% #1 diesel blend Completed 

Muffler 50% soy biodiesel and 

50% #1 diesel blend Completed 

DOC (DCL International) 50% soy biodiesel and 

50% #1 diesel blend Completed 

Muffler 20% yellow grease biodiesel and 

80% #1 diesel blend Completed 

Muffler 50% yellow grease biodiesel and 

50% #1 diesel blend Completed 

Muffler ULS (10 ppm sulfur) diesel Completed 

DOC (DCL International) ULS (10 ppm sulfur) diesel Completed 

Filter 

Tests 

(LHD 2) 

Muffler #1 diesel Completed

DPF system with Pt DOC 

(ArvinMeritor) #1 diesel Test prematurely terminated 

DPF system with Pd DOC 

(ArvinMeritor) #1 diesel Completed 

Disposable filtration element 

(Donaldson P604516) #1 diesel Completed 

Disposable filtration element 

(Filter Service) #1 diesel Completed 

DPF system (Clean Air Power/ 

ETG CPO) #1 diesel Test prematurely terminated 
Two of the sixteen tests were not completed. The tests on the AM DPF system with a 

Pt DOC and the Clean Air Power/ETG catalytic particulate oxidizer (CPO) DPF system 

were terminated prematurely to prevent overexposure of the vehicle operator to nitrogen 

dioxide (NO2). During the initial stages of these two tests, the gas monitor at the vehicle 

sampling station recorded concentrations of NO2 that were close to, or exceeded, the 

1973 American Conference of Governmental Industrial Hygienists (ACGIH) threshold 

limit value (TLV) of 5 ppm. This limit is currently used by MSHA as a ceiling limit to 

regulate exposure of underground metal and nonmetal miners to NO2 (30 CFR 57.5001). 

It is important to note that elevated concentrations were observed only when the test 

vehicle was performing the part of the duty cycle within and in front of the downstream 

stope. During the other parts of the duty cycle when the vehicle was in the main drift 

where the ventilation rate exceeded 19 m3

/s (40,258 ft3/min), the NO2 did not approach 

the ceiling limit. The Pt-based catalysts used in those systems most likely caused 

elevated NO2 concentrations. 

EFFECTS OF FUEL FORMULATIONS 

Ten fuel tests, shown in Table 5, were conducted during this study. The objective of 

eight of the tests was to assess the effects of selected fuel formulations on the 

concentrations of DPM and selected gases in mine air. Test results with seven alternative 

fuel formulations were compared with those of #1 diesel, selected as baseline fuel. The 

objective of the two remaining tests was to evaluate the effects of a DOC when used with 

alternative fuels. The effects of the vehicle equipped with a DOC and fueled with 50% 

soy biodiesel blend or ULS diesel were compared with those of the same vehicle fitted 

with a muffler and fueled with #1 diesel. 

LHD 1, powered by a Caterpillar 3126B DITA engine, was used as the test vehicle for 

the fuel tests. This engine was fitted with a regular muffler for eight tests and with a 

DOC for two of the tests. The same miner operated the test vehicle for each of the 

10 tests. 

The results of fuel tests are presented and discussed in three sections: ventilation rates, 

effects on particulate matter (aerosols), and effects on selected gases. The results 

presented in the particulate matter section are organized with respect to the results of 

EC analyses, gravimetric analyses, TEOM measurements, and aerosol size and number 

measurements. 

Ventilation Airflow Rates for the Test on Fuel Formulations 

Air velocities in the center of the drift were continuously measured at the downstream 

and upstream sampling stations during each of the tests. Ventilation rates (VRs) were 

calculated by multiplying corrected air velocities by the corresponding cross-sectional 

area of the drift. The VRs were strongly influenced by the movement of the vehicle 

inside the isolated zone during the tests as illustrated in Figure 9, which presents an 

example of the baseline fuel test. However, the average VRs among the tests were 

nonetheless very consistent, as indicated in Table 6. 

30
 
 

22.00 

20.00 

18.00 

16.00 

Figure 9.—Ventilation rates measured at the downstream sampling station during the baseline 

fuel test. Ventilation Rate [m^3/s] 

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 

Time [s] 

Table 6.—Average VRs at the downstream sampling station for the fuel tests 

Fuel Tests (LHD 1) Average Ventilation Rates 

m3

/sec ft3/min 

#1 Diesel/Muffler 19.28 40,851 

PuriNOx Cold-Weather/Muffler 19.39 41,077 

PuriNOx Warm-Weather/Muffler 19.59 41,498 

20% Soy Biodiesel Blend/Muffler 19.25 40,782 

50% Soy Biodiesel Blend/Muffler 19.16 40,601 

50% Soy Biodiesel Blend/DOC 19.84 42,040 

20% Yellow Grease Biodiesel Blend/Muffler 19.60 41,531 

50% Yellow Grease Biodiesel Blend/Muffler 18.99 40,230 

ULS Diesel/Muffler 19.19 40,671 

ULS Diesel/DOC 19.44 41,181 

The average VRs presented in Table 6 were used to adjust all measured concentrations of 

particulate matter and gases to those that would prevail if the average VRs for those tests 

were equal to the average baseline fuel test VR of 19.28 m3

/s (40,851 ft3/min). The 

adjustment of measured concentrations to a common VR allowed a direct comparison of 

the results obtained from different tests. 

31 
Effects of Fuel Formulations on Aerosols 

Table 7 summarizes the results of the analyses on the effects of each of the eight fuel 

formulations on concentrations of EC, TPM, and sulfate. The results are presented as the 

ventilation rate-adjusted average net contributions of the test vehicle to the downstream 

mass concentrations. The results of EC, gravimetric, and TEOM analyses are graphically 

presented in Figure 10. Two sets of results are shown for EC analyses. One set of results 

is from analyses performed on samples collected using an HV sampling method. Another 

set is from analyses performed on the samples collected by the SSM. Results on aerosol 

concentrations, measured by an SMPS, are presented at the end of this section. 

32
 

Table 7.—Effects of fuel formulations on EC, gravimetrically and TEOM-determined TPM, 

and sulfate (SO4) concentrations
 

(common ventilation rate = 19.28 m3

/s) 

Fuel Tests 

(LHD 1) 

VR-Adjusted Average Net Contributions to Concentrations 

EC 

NIOSH 5040 3 HV, μg/m

EC 

NIOSH 5040 3 SSM, μg/m

TPM 

Gravimetric 

Analysis, 3 μg/m

TPM 

TEOM, 3 μg/m

SO4 

IC Analysis, 3 μg/m

#1 Diesel/Muffler 275 262 361 388 5.5 

PuriNOx Cold-Weather/ 

Muffler 90 99 200 207 5.4 

PuriNOx Warm-Weather/ 

Muffler 40 40 157 129 5.8 

20% Soy Biodiesel/ 

Muffler 141 166 243 244 3.2 

50% Soy Biodiesel/ 

Muffler 93 108 183 192 2.6 

50% Soy Biodiesel/DOC 87 103 155 — 6.6 

20% YG Biodiesel/ 

Muffler 184 177 262 278 4.6 

50% YG Biodiesel/ 

Muffler 120 121 196 212 2.4 

ULS Diesel/Muffler 250 243 341 405 0.3 

ULS Diesel/DOC 188 187 249 278 0.8 
Effects of Fuels on the Mass Concentration of EC 

The average net contributions of a tested configuration to the mass concentration of EC 

at the downstream station during fuel formulation tests are shown in the first two data 

columns of Table 7. EC concentrations measured at the upstream sampling station were 

below the limits of detection (0.9 μg/sample for HV and 1.6 μg/sample for SKC) and 

thus were considered to be zero for each of the fuel tests. 

Results shown in Table 7 and Figure 10 were used to calculate the relative effects of 

alternative fuel formulations and a DOC on EC and TPM concentrations shown in 

Figure 11. Relative effects were calculated by comparing the net contributions from each 

of the fuel tests with those from the baseline test (a muffler with #1 diesel fuel). Positive 

values indicate reductions in concentrations. 

33
 

EC HV EC SSM TPM Gravimetric TPM TEOM 

500 

Concentrations [μg/m^3] 

400 

300 

200 

100 

0 

275 

90 

40 

141 

93

87 

184 

120 

250 

188 

262 

99 

40 

166 

108

103 

177 

121 

243 

187 

361 

200 

157 

243 

183

155 

262 

196 

341 

249 

388 

207 

129 

244 

192 

278 

212 

405 

278 

D 

a 

t 

a 

n 

o 

t 

a 

v 

a 

i 

l 

a 

b 

l 

e 

#1 Diesel / PuriNOx PuriNOx 20% Soy 50% Soy 50% Soy 20% YG 50% YG ULS Diesel ULS Diesel 

Muffler Cold- Warm- Biodiesel / Biodiesel / Biodiesel / Biodiesel / Biodiesel / / Muffler / DOC 

Weather / Weather / Muffler Muffler DOC Muffler Muffler 

Muffler Muffler 

 Figure 10.—Contributions of fuel formulation to concentrations of EC and gravimetrically and 

TEOM-determined TPM (common ventilation rate = 19.28 m3

/s). 
 

-20 

0 

20 

40 

60 

80 

100 

Reduction from Baseline [%] EC HV 67 85 49 66 68 33 56 9 32 

EC SSM 62 85 37 59 61 33 54 7 29 

TPM GRAV 45 58 32 48 60 30 44 5 32 

TPM TEOM 46 66 37 50 27 46 -3 27 

PuriNOx ColdWeather / 

Muffler 

PuriNOx 

WarmWeather / 

20% Soy 

Biodiesel / 

Muffler 

50% Soy 

Biodiesel / 

Muffler 

50% Soy 

Biodiesel / 

DOC 

20% YG 

Biodiesel / 

Muffler 

50% YG 

Biodiesel / 

Muffler 

ULS Diesel / 

Muffler 

ULS Diesel / 

DOC 

D 

a 

t 

a 

n 

o 

t 

a 

v 

a 

i 

l 

a 

b 

l 

e 

Figure 11.—Changes in average concentrations of EC and TPM for tested fuel formulations. 

Positive values indicate reductions in concentrations. 

Results of the EC analysis on the HV samples show that the cold- and warm-weather 

water-fuel emulsions reduced concentrations of EC by 67% and 85%, respectively. The 

EC analysis performed on SSM samples showed fairly comparable results with a 62% 

and 85% reduction in net EC contribution for those two water-fuel blends, respectively. 

The 20% soy biodiesel blend reduced EC concentrations by 49% (HV) and 37% (SSM). 

An increase in the soy biodiesel fraction to 50% resulted in further reductions in the 

concentrations of EC (66% for HV and 59% for SSM). The results for the yellow grease 

(YG) biodiesel blends indicated that EC reductions were slightly less pronounced than 

those for the corresponding soy biodiesel blends. 

Results indicated very little difference in the effects of ULS diesel fuel and baseline #1 

fuel on EC concentrations. However, when ULS fuel was used with a DOC in the 

exhaust system, there was about a 30% reduction in EC concentrations. It is important to 

note that the sulfur content of #1 diesel fuel was approximately 255 ppm, and the sulfur 

content of ULS diesel was 10 ppm. 

The contributions of tested configurations to the concentrations of EC at the vehicle 

sampling station are summarized in Table 8. These contributions were found to be 

generally higher than those for the downstream sampling station. This can be attributed 

to the fact that during parts of the duty cycle, the vehicle sampling station was in a poorly 

diluted exhaust plume. Nonetheless, the relative changes in EC concentrations are 

comparable to those found for the downstream location. 

34
 
Table 8.—Effects of fuel formulations on ventilation-adjusted average net vehicle contributions 

to concentrations of EC at the vehicle sampling station
 

(common ventilation rate = 19.28 m3

/s) 

Fuel Tests (LHD 1) 

Adjusted Average 

EC Concentrations, 

NIOSH 5040 

SSM, 3 μg/m

Reductions in 

Adjusted Average 

Contribution to EC 

Concentration, 

% 

#1 Diesel/Muffler 362 — 

PuriNOx Cold-Weather/Muffler 137 62 

PuriNOx Warm-Weather/Muffler 84 77 

20% Soy Biodiesel Blend/Muffler 179 51 

50% Soy Biodiesel Blend/Muffler 123 66 

50% Soy Biodiesel Blend/DOC 111 69 

20% Yellow Grease Biodiesel Blend/Muffler 257 29 

50% Yellow Grease Biodiesel Blend/Muffler 162 55 

ULS Diesel/Muffler 365 –1 

ULS Diesel/DOC 213 41 

Effects of Fuels on the Mass Concentration of TPM Determined by 

Gravimetric Analysis 

The average net contributions of tested configurations to the mass concentration of TPM, 

determined by gravimetric analysis, are shown in the third data column of Table 7. The 

observed reductions in net contributions relative to the baseline case are presented in the 

third row of the Figure 11 data table (labeled “TPM GRAV”). 

The TPM mass on most downstream samples was found to be above a quantification 

limit of 85 μg/sample for gravimetric analysis. The results presented in Table 7 show 

that the TPM concentrations determined by gravimetric analysis agree reasonably well 

with those measured by the TEOM. 

Gravimetric analysis showed that the cold-weather emulsion reduced TPM 

concentrations by 45%. The warm-weather emulsion contributed to a 58% reduction. 

Fueling the test vehicle with a 20% blend of soy and a 20% blend of yellow grease 

biodiesel reduced TPM concentrations by 32% and 30%, respectively. When the vehicle 

was fueled with 50% blends of soy and yellow grease biodiesel, the reductions were 48% 

and 44%, respectively. 

When the muffler was replaced by a DOC, the gravimetric analysis also showed 

reductions in TPM concentrations. For example, using a DOC with a 50% blend of soy 

biodiesel increased the reduction of TPM from 48% to 60%. In the case of ULS diesel, 

the DOC increased the reduction in TPM from 5% to 32%. 

35
 
Effects of Fuels on the Mass Concentration of TPM Measured Using the 

TEOM 1400a 

Results of continuous TPM mass concentration measurements with the TEOM 1400a 

instruments at the downstream sampling stations during the fuel tests are shown in 

Figures 12–14. 

TPM concentrations at the upstream sampling station were found to be very low. In 

several instances, due to external vibration and shocks imposed on the instrument, the 

readings were found to be negative. Therefore, upstream concentrations were assumed to 

be negligible and the net vehicle contributions to TPM concentrations were assumed to 

be equal to downstream concentrations. 

The graphs presented in Figures 12–14 illustrate the transient nature of the TPM 

concentrations at the downstream sampling station. The primary cause of this 

phenomenon is the cyclic nature of the vehicle duty cycle and ventilation flow. 

The average concentrations of TPM were calculated as differences between the reported 

TEOM filter masses at the start and end of the sampling period. The ventilation-adjusted 

average concentrations of TPM are presented in the fourth data column of Table 7. The 

calculated reductions relative to the baseline case are presented in the fourth row of the 

data table in Figure 11 (labeled “TPM TEOM”). 

36
 

700 

600 

500 

400 

300 

200 

100 

0 

TPM Mass Concentration [ug/cm^3] 

0 1000 2000 3000 4000 5000 

Time [s] 

#1 Diesel / Muffler Downstream PuriNOx Cold-Weather / Muffler Downstream 

PuriNOx Warm-Weather / Muffler Downstream 

6000 

 Figure 12.—Effects of water emulsions on mass concentrations of TPM at downstream sampling 

station measured by TEOM. 
 

Mass concentrations of TPM observed at the downstream sampling station during the 

baseline test as well as tests with cold- and warm-weather water emulsions are shown 

in Figure 12. The peak concentrations and cumulative net contributions to TPM 

concentrations, measured by the TEOM, were substantially lower in the cases where 

water emulsions were used. The relative reductions in net TPM concentrations were 

calculated to be 46% and 66% for cold- and warm-weather water emulsions, respectively 

(see Figure 11). 

Real-time TPM measurements of biodiesel blend tests taken at the downstream sampling 

stations are plotted along with baseline results in Figure 13. Due to problems with the 

instrument at the downstream sampling station, results are not available for the test 

during which the vehicle was equipped with a DOC and operated with a 50% soy 

biodiesel blend. The net contributions of the TPM concentrations, measured by the 

TEOM, were found to be substantially reduced when #1 diesel was substituted with soy 

and yellow grease biodiesel blends. The reductions were found to be slightly higher for 

soy than for yellow grease blends. 

37
 

700 

600 

500 

400 

300 

200 

100 

0 

TPM Mass Concentration [ug/cm^3] 

0 1000 2000 3000 4000 5000 6000 

Time [s] 

#1 Diesel / Muffler Downstream 20% Soy Biodiesel Blend / Muffler Downstream 

50% Soy Biodiesel Blend / Muffler Downstream 20% Yellow Grease Biodiesel Blend / Muffler Downstream 

50% Yellow Grease Biodiesel Blend / Muffler Downstream 

 Figure 13.—Effects of biodiesel blends on mass concentrations of TPM at downstream sampling 

station measured by TEOM. 
0 

100 

200 

300 

400 

500 

600 

700 

TPM Mass Concentration [ug/cm^3] 

0 1000 2000 3000 4000 5000 6000 

Time [s] 

#1 Diesel / Muffler Downstream ULS Diesel / Muffler Downstream ULS Diesel / DOC Downstream 

 Figure 14.—Effects of ULS fuel on mass concentrations of TPM at downstream sampling station 

measured by TEOM. 

Effects of Fuels on the Mass Concentrations of Sulfates 

Net contributions to the sulfate mass concentrations at the downstream sampling station 

during the fuel tests are summarized in the fifth column of Table 7. The concentrations 

reported for the samples collected at the upstream sampling station were found to be 

slightly above the 0.3-μg/sample limit of detection for the applied method. Therefore, 

those concentrations were used in the calculation of net contributions to the downstream 

SO4 concentration. Several of the concentrations reported for the samples collected at 

the downstream sampling station were found to be between the limit of detection and the 

1.0-μg/sample limit of quantification, but most were found to be above the limit of 

quantification. 

Results show that cold-weather (300 ppm sulfur) and warm-weather (279 ppm sulfur) 

water emulsions had minor effects on the net contributions of sulfate concentrations. 

These data also show quantifiable reduction in the concentrations of sulfates in mine air 

in the case of soy biodiesel blends (200 ppm sulfur for the 20% blend and 129 ppm sulfur 

for the 50% blend) and yellow grease biodiesel (approximately 40 ppm sulfur neat YG 

blended with 255 ppm sulfur #1 diesel) that were roughly proportional to the sulfur 

content in the blends. The same analysis revealed that ULS diesel fuel (4 ppm sulfur) 

reduced the vehicle’s contribution to the sulfate concentrations from 5.5 μg/m3

, observed 

for the test with #1 diesel, to 0.3 μg/m3

. When the muffler was replaced with a DOC, the 

net contributions of the vehicle to the concentrations of sulfates increased from 2.6 to 

6.6 μg/m3

 in the case of 50% soy biodiesel, and from 0.3 to 0.8 μg/m3 in the case of 

38
 
ULS diesel. This increase was most likely due to the creation of sulfates by catalytic 

processes in the DOC. 

Effects of Fuel Formulations on Size Distribution and Number 

Concentration of Aerosols 

The size-selective measurements performed at the downstream and upstream sampling 

stations during the tests with 10 different fuel formulations were used to assess the effects 

of those formulations on the physical characteristics of diesel aerosols in mine air. These 

characteristics included the average geometric mean diameter (GMD), geometric 

standard deviation (GSD), peak concentration, and total concentration of the aerosols. 

The concentration distributions were adjusted for differences in the VR between the tests 

by adjusting them to the common VR of 19.28 m3

/s, the average VR maintained during 

the baseline test. 

The results of the statistical analyses performed on the data, including GMDs, GSDs, and 

ventilation-adjusted total aerosol number concentration, are summarized in Table 9. 

Each aerosol number concentration presented is the ventilation rate-adjusted average of 

several measurements performed during a test. The net contributions of the vehicle 

emissions to the aerosol concentration values are obtained by subtracting concentrations 

measured at the upstream sampling station from those measured at the downstream 

station. The relative changes in the net contributions were calculated using the baseline 

case as the reference. 

The results of measurements at the upstream sampling station, presented in the seventh 

data column in Table 9, showed that the background number concentrations of aerosols 

entering the isolated zone during the tests were relatively low. The peak aerosol 

concentrations at the upstream end of the isolated zone were found to be approximately 

three orders of magnitude lower then those at the downstream end. Those differences in 

downstream and upstream concentrations are illustrated in Figure 15, which shows the 

size distributions measured during water emulsion tests. Despite their almost negligible 

effects on the results, the upstream concentrations were included in the calculations of the 

net contribution of the tested configurations to the aerosol concentrations at the 

downstream station. However, when aerosol size distributions were analyzed, the size 

distributions of the upstream aerosols were neglected because of their small effects on 

the results. 

39
 
Table 9.—Effects of fuel formulations on size distribution 

and concentrations of aerosols in mine air 

(common ventilation rate = 19.28 m3

/s) 

Fuel Tests 

(LHD 1) 

Downstream Upstream Net Contribution 

Average 

GMD, 

nm 

Average 

GSD 

Adjusted 

Average 

Total 

Number, 

×107 

3 #/cm

Average 

GMD, 

nm 

Average 

GSD 

Adjusted 

Average 

Total 

Number, 

×107 

3 #/cm

Adjusted 

Average 

Total 

Number, 

×107 

3 #/cm

Change 

(increase 

is 

positive), 

% 

#1 Diesel/ 

Muffler 95.1 1.76 4.2930 — — 0.0264 4.2667 

PuriNOx 

ColdWeather/ 

Muffler 

68.4 1.69 4.8899 — — 0.0173 4.8726 14.2 

PuriNOx 

WarmWeather/ 

Muffler 

54.9 1.72 4.9816 — — 0.0145 4.9671 16.4 

20% Soy 

Biodiesel 

Blend/ 

Muffler 

80.6 1.67 3.7668 — — 0.0100 3.7567 –12.0 

50% Soy 

Biodiesel 

Blend/ 

Muffler 

70.3 1.68 3.3994 — — 0.0090 3.3904 –20.5 

50% Soy 

Biodiesel 

Blend/ 

DOC 

67.0 1.73 3.1971 — — 0.0082 3.1889 –25.3 

20% 

Yellow 

Grease 

Biodiesel 81.0 1.63 4.7291 — — 0.0249 4.7042 10.3 

Blend/ 

Muffler 

50% 

Yellow 

Grease 

Biodiesel 61.4 1.67 3.1690 — — 0.0366 3.1324 –26.6 

Blend/ 

Muffler 

ULS 

Diesel/ 

Muffler 

93.0 1.73 3.7749 — — 0.0558 3.7191 –12.8 

ULS 

Diesel/ 

DOC 

89.3 1.71 3.4450 — — 0.0065 3.4385 –19.4 

40
 
dN/dlog(D_p) [#/cm^3] 

1.00E+07 

1.00E+06 

1.00E+05 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01 

10 100 1000 

D_p [nm] 

PuriNOx Cold-Weather with Muffler, Downstream 

PuriNOx Warm-Weather with Muffler, Downstream 

PuriNOx Cold-Weather with Muffler, Upstream 

PuriNOx Warm-Weather with Muffler, Upstream 

 

 

Figure 15.—Aerosol size distributions at downstream and upstream stations observed during 

water emulsion tests (common ventilation rate = 19.28 m3

/s). 

1.60E+06
 

1.40E+06
 

dN/dlog(D_p) [#/cm^3] 1.20E+06 

1.00E+06 

8.00E+05 

6.00E+05 

4.00E+05 

2.00E+05 

0.00E+00 

#1 Diesel with Muffler PuriNOx Cold-Weather with Muffler 

PuriNOx Warm-Weather with Muffler 

10 100 1000 

D_p [nm] 

 Figure 16.—Effects of water emulsions on the size distributions of aerosols (common ventilation 

rate = 19.28 m3

/s). 

41 
Figure 16 shows the effects of the two water emulsions on the aerosol size distributions 

downstream of the test zone. The size distributions of the particles observed during the 

tests with water emulsions are characterized by lower GMDs and higher peak 

concentrations than the size distributions observed during the baseline test with #1 diesel 

(see Table 9 and Figure 16). The GMD of the baseline particles was 95 nm, while the 

GMDs for the cold- and warm-weather water-fuel emulsions were 68 and 55 nm, 

respectively. The peak particle number concentration for the baseline test with #1 diesel 

was 1,065,000/cm3 and was lower than those observed for cold-weather (1,449,000/cm3

) 

and warm-weather (1,324,000/cm3

) emulsions. The relative increases in total aerosol 

number concentrations were 14% and 16% for the cold- and warm-weather water-fuel 

emulsions, respectively. 

0.00E+00 

2.00E+05 

4.00E+05 

6.00E+05 

8.00E+05 

1.00E+06 

1.20E+06 

1.40E+06 

dN/dlog(D_p) [#/cm^3] 

10 100 

D_p [nm] 

1000 

#1 Diesel with Muffler 

50% Soy Biodiesel with Muffler 

20% Soy Biodiesel with Muffler 

50% Soy Biodiesel with DOC 

 Figure 17.—Effects of soy biodiesel blends on the size distributions of aerosols (common ventilation rate = 19.28 m3

/s). 

Figure 17 shows the downstream particle size distributions for the baseline test and tests 

using soy-based biodiesel blends. The number concentration and GMD for each test are 

shown in Table 9. Figure 17 shows that the particles from the biodiesel blends have 

lower GMDs and somewhat lower peak concentrations than those for the baseline fuel. 

The GMD distributions of particles for the tests with 20% and 50% soy biodiesel blends 

were 81 and 70 nm, respectively, whereas the baseline particle GMD was 95 nm. The 

peak particle number concentration was 1,058,000/cm3

 for the 20% soy blend and 

962,000/cm3

 for the 50% soy blend versus the baseline particle number concentration of 

1,065,000/cm3

. The total aerosol concentrations were found to be reduced by 12% and 

42
 
 

21% when 20% and 50% soy biodiesel blends, respectively, were used. The DOC, when 

used with the 50% soy biodiesel blend, caused a further decrease in the GMD (67 nm vs. 

70 nm), the peak concentrations, and the total concentration of aerosols (by 25%) (see 

Table 9 and Figure 17). 

The aerosol size distributions for the baseline test and tests using yellow grease biodiesel 

blends are shown in Figure 18. Corresponding data are shown in Table 9. The data 

revealed that the distributions observed during tests with yellow grease biodiesel blends 

exhibited lower GMDs than those observed during the baseline fuel test. GMDs for the 

tests with 20% and 50% yellow grease biodiesel blends were 81 and 61 nm, respectively, 

whereas the baseline particle GMD was 95 nm. The peak particle number concentration 

for 20% yellow grease blend was 1,394,000/cm3

 and, unlike that observed for the soybased blend, was higher than that for the 50% yellow grease blend (962,000/cm3

) and the 

baseline fuel (1,065,000/cm3

). The total aerosol number concentration relative to the 

baseline fuel increased by 10% when the 20% yellow grease fuel blend was used, but 

showed a decrease of 27% when the 50% yellow grease fuel blend was used. 

43
 

0.00E+00 

2.00E+05 

4.00E+05 

6.00E+05 

8.00E+05 

1.00E+06 

1.20E+06 

1.40E+06 

1.60E+06 

dN/dlog(D_p) [#/cm^3] 

10 100 

D_p [nm] 

#1 Diesel with Muffler 20% Yellow Grease Biodiesel with Muffler 

50% Yellow Grease Biodiesel with Muffler 

1000 

 Figure 18.—Effects of yellow grease biodiesel blends on the size distributions of aerosols (common ventilation rate = 19.28 m3

/s). 
 

When the vehicle was fueled with ULS diesel, the particle size distributions were 

characterized by slightly lower GMDs and higher peak concentrations than those 

observed during the baseline test with #1 diesel (see Table 9 and Figure 19). While 

the particle distributions generated by vehicles fueled with #1 diesel fuel were 

characterized by a GMD of 95 nm, the GMD for the particle distributions from ULS fuel 

was 93 nm. The peak concentration of 1,065,000/cm3

 and total net contribution to 

aerosol concentrations of 42,667,000/cm3

 for the test with #1 diesel were found to be 

slightly higher than those observed for ULS diesel (994,000/cm3 and 37,191,000/cm3

, 

respectively). The GMD, peak concentration, and total concentration of aerosols were 

found to be further reduced when a ULS diesel was used in the vehicle that was fitted 

with a selected DOC (Table 9 and Figure 19). 

44
 

0.00E+00 

2.00E+05 

4.00E+05 

6.00E+05 

8.00E+05 

1.00E+06 

1.20E+06 

1.40E+06 

dN/dlog(D_p) [#/cm^3] 

10 100 

D_p [nm] 

#1 Diesel Muffler ULS Diesel with Muffler ULS Diesel with DOC 

1000 

 Figure 19.—Effects of ULS diesel on the size distributions of aerosols (common ventilation rate = 

19.28 m3

/s). 
Effects of Fuel Formulations on Concentrations of NO, NO2, CO, and CO2 

During fuel tests, NO, NO2, CO, and CO2 concentrations were measured continuously at 

the upstream, downstream, and vehicle sampling stations. During these tests, the 

concentrations of NO, NO2, and CO at the upstream sampling station were found to be 

under the detection limit of the iTX multigas instrument. Therefore, the net contributions 

of the vehicles to those gases were assumed to be equal to their concentrations at the 

downstream and vehicle locations. Continuous measurements with the RKI Eagle CO2 

monitor at the upstream sampling station showed that the background concentration of 

CO2 remained relatively constant throughout the tests, averaging 321 ppm when 

corrected for local atmospheric pressure. This value was used during the analysis as the 

average background concentration of CO2 for all tests. 

Gas data were adjusted to the common average ventilation rate of the baseline fuel test. 

The ventilation-adjusted net contributions of fuel formulations and diesel oxidation 

catalyst to average and maximum peak concentrations of NO, NO2, CO, and CO2 are 

summarized for the downstream and vehicle sampling stations in Tables 10 and 11, 

respectively. 

Table 10.—Net contributions of fuel formulations to average and peak NO, NO2, CO, and CO2

 concentrations at the downstream sampling station
 

(common ventilation rate = 19.28 m3

/s) 

Fuel Tests 

(LHD 1) 

NO, ppm NO2, ppm CO, ppm CO2, ppm 

Avg. Max. Avg. Max. Avg. Max. Avg. Max. 

#1 Diesel/Muffler 3.7 13.0 0.1 0.4 2.2 10.0 808 2,258 

PuriNOx ColdWeather/Muffler N/A N/A N/A N/A N/A N/A 816 2,270 

PuriNOx WarmWeather/Muffler N/A N/A N/A N/A N/A N/A 778 2,320 

20% Soy Biodiesel 

Blend/Muffler 4.2 13.0 0.1 0.6 1.8 7.0 844 2,307 

50% Soy Biodiesel 

Blend/Muffler 4.1 12.9 0.1 0.6 1.6 7.0 852 2,349 

50% Soy Biodiesel 

Blend/DOC 4.4 13.4 0.3 1.1 0.0 0.0 859 2,269 

20% YG Biodiesel 

Blend/Muffler N/A N/A N/A N/A N/A N/A 843 2,269 

50% YG Biodiesel 

Blend/Muffler N/A N/A N/A N/A N/A N/A 861 2,301 

ULS Diesel/ 

Muffler N/A N/A N/A N/A N/A N/A 877 2,300 

ULS Diesel/DOC 3.5 11.1 0.2 0.9 0.0 0.0 855 2,303 

NO, NO2, and CO results collected at the downstream sampling station during the tests 

on PuriNOx water emulsions, yellow grease biodiesel blends, and ULS diesel are not 

available due to problems in data acquisition. The results of measurements conducted at 

the vehicle sampling station with the PuriNOx warm-weather water emulsion and 20% 

45 
yellow grease biodiesel blends are also not available due to problems encountered during 

the data-recording process. 

Table 11.—Net contributions of fuel formulations to average and peak of NO, NO2, CO, and CO2
 

concentrations at the vehicle sampling station
 

(common ventilation rate = 19.28 m3

/s) 

Fuel tests 

(LHD 1) 

NO, ppm NO2, ppm CO, ppm CO2, ppm 

Avg. Max. Avg. Max. Avg. Max. Avg. Max. 

#1 Diesel/Muffler 5.2 14.0 0.4 1.4 2.8 11.0 804 2,413 

PuriNOx ColdWeather/Muffler 5.1 15.1 0.4 1.3 1.9 8.0 807 1,892 

PuriNOx WarmWeather/Muffler N/A N/A N/A N/A N/A N/A 886 1,963 

20% Soy Biodiesel 

Blend/Muffler 5.2 16.0 0.5 1.9 1.7 9.0 844 2,030 

50% Soy Biodiesel 

Blend/Muffler 6.1 16.9 0.5 1.4 1.6 8.0 853 2,021 

50% Soy Biodiesel 

Blend/DOC 6.4 18.5 0.7 2.7 0.0 0.0 916 2,197 

20% YG Biodiesel 

Blend/Muffler N/A N/A N/A N/A N/A N/A 999 2,145 

50% YG Biodiesel 

Blend/Muffler 6.5 16.7 0.4 1.7 1.7 10.8 874 2,027 

ULS Diesel/Muffler 6.6 16.9 0.5 1.8 2.8 11.9 950 2,705 

ULS Diesel/DOC 5.2 16.1 0.6 2.8 0.0 0.0 924 3,020 

Effects of Fuels on the Concentrations of NO, NO2, and CO 

An examination of the results obtained for the downstream location (Table 10) and on the 

vehicle (Table 11) showed little difference in the NO, NO2, and CO concentrations 

between the baseline and the fuel formulation cases for which data are available. 

Carbon Dioxide (CO2) 

According to the results presented in Table 10, differences in downstream average and 

peak concentrations of CO2 between the tests were relatively minor. The computed 

coefficient of variation (CV) was 4% for the average and 1% for the peak CO2 

concentrations. The small differences signify the ability of the vehicle operator to 

replicate the fuel consumption and load on the engine during the duty cycle throughout 

all of the fuel tests. The results of measurements at the vehicle sampling station show 

much less agreement in average (CV = 7%) and peak CO2 concentrations (CV = 16%). 

This could have been caused by high variability in the dilution rate at the vehicle 

sampling station, particularly during the parts of the duty cycle performed in the stope. 

46
 
Effects of a Diesel Oxidation Catalyst (DOC) 

To assess the effects of a DOC on vehicle emissions, the tests using the 50% soy biodiesel blend and ULS diesel were conducted twice, once when the vehicle was equipped 

with a muffler and once when the vehicle was equipped with a DOC. As Tables 10–11 

and Figure 20 illustrate, during the tests with a DOC the average and peak NO2 concentrations at the downstream and vehicle sampling stations were found to be higher than in 

those cases when the vehicle was equipped with a muffler. The tests with 50% soy 

biodiesel showed that use of the DOC increased the net ventilation-adjusted average and 

peak NO2 at the vehicle by 31% and 92%, respectively. Similarly, the tests with ULS 

diesel showed that use of the DOC increased the equivalent NO2 concentrations by 24% 

and 58%, respectively. During both DOC tests, peak concentrations of NO2 at the 

vehicle sampling station approached 3 ppm. Use of the DOC rendered downstream and 

on-vehicle CO concentrations undetectable. 

47
 

 NO2 Concentration [ppm] 3.0 

2.5 

2.0 

1.5 

1.0 

0.5 

0.0 

0 1000 2000 3000 4000 5000 6000 

Time [s] 

Muffler DOC 

Figure 20.—Effects of tested DOC on concentrations of NO2 at vehicle sampling station observed 

from the test with 50% soy biodiesel (common ventilation rate = 19.28 m3

/s). 
EFFECTS OF FILTRATION SYSTEMS 

This section presents the results of the tests on selected filtration systems (see Table 5). 

Six tests, of which four were successfully completed, were conducted in the isolated zone 

with the objective of assessing the effects of selected diesel particulate filter (DPF) 

systems and disposable filter elements (DFEs) on concentrations of DPM and gases in 

mine air. Two of the tests were on the ArvinMeritor (AM) DPF system with a fuel 

burner, followed by a DOC catalyzed, in one case, with a proprietary platinum (Pt) based 

formulation and, in the other case, with a proprietary palladium (Pd) based formulation. 

Two tests were conducted to evaluate DFEs from Donaldson and Filter Service. One test 

was conducted to evaluate a Clean Air Power/ETG flow-through catalytic particulate 

oxidizer (CPO). The baseline was established using data generated during the test with 

the vehicle equipped with a regular muffler. 

The tests with the AM with the Pt-based DOC and the Clean Air Power/ETG CPO 

system were terminated in the early phase of the tests, and only gas data gathered in that 

period were available for the analysis. The test on the AM system with the Pd-catalyzed 

DOC was extended for an additional three full cycles to assess the effects of the diesel 

fuel burner supported regeneration process. The results of the measurements obtained 

during these three additional cycles are reported separately from those of the filter test. 

The vehicle used for these tests was LHD 2 powered by a Deutz BF41013FC/MVS 

engine. It was not possible to use the same operator for all of the tests. 

Ventilation Airflow Rates for Filtration Systems Tests 

The ventilation rates (VRs) were obtained from air velocity measurements performed at 

the downstream station. During the filter tests, VRs were also found to be strongly 

influenced by vehicle movement inside the isolated zone, as illustrated by the example of 

the VR recorded during the baseline filter test (see Figure 21). The VRs averaged over 

the length of the individual filter tests are summarized in Table 12. The average VRs 

among the tests were found to be very consistent, as indicated in Table 12. 

48
 
 

Ventilation Rate [m^3/sec] 

22.00 

20.00 

18.00 

16.00 

0 1000 2000 3000 4000 5000 6000 7000 

Time [s] 

Figure 21.—Ventilation rates measured at the downstream sampling station during the baseline 

filter test. 

Table 12.—Average VRs at the downstream sampling station 

for the filter tests 

Filter Tests Average Ventilation Rates 

(LHD 2) m3

/sec ft3/min 

Muffler 19.29 40,874

AM Pd DOC 19.27 40,827 

Donaldson 19.36 41,016

Filter Service 19.57 41,467 

The average VRs presented in Table 12 were used to adjust all measured concentrations 

of particulate matter and gases to the average VR of the baseline fuel test, 19.29 m3

/s 

(40,874 ft3

/min). Adjustment of the measured concentrations to a common VR is 

required to make a direct comparison of the results between the tests. 

Effects of Filtration Systems on Aerosols 

The VR-adjusted average net contributions of the vehicle tested during the filter tests to 

the downstream mass concentrations of EC, TPM, and SO4 are summarized in Table 13. 

The EC and TPM concentrations for each test are graphically presented in Figure 22. 

49
 
Table 13.—Effects of filtration system on average EC, gravimetrically and TEOM-determined TPM,
 

and sulfate (SO4) concentrations
 

(common ventilation rate = 19.29 m3

/s) 

Filter Tests 

(LHD 2) 

VR-Adjusted Average Contributions to Concentrations 

EC 

NIOSH 5040, 3 μg/m

TPM 

Gravimetric 

Analysis, 3 μg/m

TPM 

TEOM, 3 μg/m

SO4 

IC Analysis, 3 μg/m

Muffler 105 172 180 3.4 

AM Pd DOC 8 54 51 15.3 

Donaldson 9 27 43 1.4 

Filter Service 31 65 62 0.5 

AM Pd DOC 

Regeneration N/A N/A 183 N/A 

EC HV TPM GRAV TPM TEOM 

200 

Concentrations [ug/m^3] 

150 

100 

50 

0 

105 

8

9 

31 

172 

54 

27 

65 

180 

51 

43 

62 

Muffler AM Pd DOC Donaldson Filter Service 

 Figure 22.—VR-adjusted average concentrations of EC and gravimetrically and TEOM-determined 

TPM (common ventilation rate = 19.29 m3

/s). 

Figure 23 shows the relative effects of the filtration systems on the aerosol concentrations 

expressed as percentages of reduction relative to the baseline case. 

50
 
 

0 

10 

20 

30 

40 

50 

60 

70 

80 

90 

100 

Reduction from Baseline [%] 

EC HV 92 92 70 

TPM GRAV 69 85 62 

TPM TEOM 72 76 65 

AM Pd DOC Donaldson Filter Service

 Figure 23.—Changes in average concentrations of EC and TPM with implementation of filtration 

systems. Values indicate reductions in concentrations. 

Effects of Filtration Systems on Mass Concentration of EC 

The results presented in Figure 23 show that two systems, the AM DPF system with a 

palladium (Pd) catalyzed DOC and the Donaldson DFE, reduced the net contribution of 

vehicle to mass concentrations of EC by 92%. The disposable filter element from Filter 

Service reduced the contribution by 70%. 

Effects of Filtration Systems on Mass Concentration of TPM 

Determined by Gravimetric Analysis 

The ventilation rate-adjusted results of the gravimetric analyses performed on the 

samples collected at the downstream sampling station during the filter tests are presented 

in Table 13. The mass of the samples collected during these tests was found to be above 

the 25-μg/sample detection limit, but below the 85-μg/sample quantification limit. 

The results presented in the Figure 23 data table show that the AM DPF system with a 

Pd-catalyzed DOC reduced downstream TPM concentrations by 69%. The disposable 

elements from Donaldson and Filter Service reduced downstream TPM concentrations by 

85% and 62%, respectively. 

51
 
All three filter systems more efficiently reduced EC concentrations than TPM 

concentrations in the mine air. The most pronounced difference between EC and TPM 

efficiencies was observed with the AM DPF system. This difference can be partially 

attributed to an increase in sulfate formation due to catalytic processes in the DOC. 

Effects of Filtration Systems on the Mass Concentration of TPM Measured 

With the TEOM 1400a 

During filter tests, continuous measurements of mass concentrations of TPM from the 

TEOM 1400a instruments at the downstream and upstream sampling stations are shown 

in Figure 24. TPM concentrations at the upstream sampling station were much lower 

than the downstream concentrations and thus were not used in the calculations. The 

average concentrations of TPM were calculated using the differences between the 

reported TEOM filter masses at the start and end of the sampling period. The ventilationadjusted averages are presented in Table 13 and Figures 22–23. 

Generally, results obtained from TEOM measurements are in agreement with the 

gravimetric results. TEOM results show that downstream TPM concentrations were 

reduced from those observed during the baseline test by 72% in the case of the AM DPF 

system with the Pd-catalyzed DOC, by 76% in the case of the Donaldson DFE, and by 

65% in the case of the Filter Service DFE. 

Throughout the tests, continuous monitoring with the TEOM instrument revealed 

differences in the effects of the tested filtration systems on TPM concentrations at the 

downstream sampling station, as shown in Figure 24. Although the concentrations of 

TPM during the test with the Donaldson DFE steadily declined throughout the duration 

of the test, the TPM concentrations during the test with the Filter Service DFE generally 

increased throughout the test. It can be hypothesized that the relatively clean filtration 

element from Donaldson, which had operated for only a couple of hours prior to the test, 

gained efficiency while accumulating DPM throughout test. The available data were 

insufficient to draw any conclusion as to the reasons for the loss in efficiency observed 

with the Filter Service DFE. 

52
 
0.0 

50.0 

100.0 

150.0 

200.0 

250.0 

300.0 

350.0 

TPM Mass Concentration [ug/cm^3] 

0 1000 2000 

Muffler Downstream 

3000 4000 

Time [s] 

5000 6000 7000 

AM Pd DOC Downstream 

8000 

Donaldson Downstream Filter Service Downstream 

 Figure 24.—Effects of filtration systems on mass concentrations of TPM measured throughout the 

tests by TEOM (common ventilation rate = 19.29 m3

/s). 

Effects of Filtration Systems on Mass Concentration of Sulfates 

The results of the sulfate analysis performed on the filter samples collected at the 

downstream and upstream sampling stations during the filter tests are summarized in 

Table 13. The concentrations of sulfates at the upstream sampling station were found to 

be between the 0.3-μg/sample limit of detection and the 1.0-μg/sample limit of 

quantification for the applied method. The downstream sulfate concentrations were 

found to be above the 1.0-μg/sample limit of quantification during all tests except the 

Filter Service DFE test, where sulfate concentrations were between the limit of detection 

and limit of quantification. 

Results indicate that when the muffler was replaced with the AM DPF system having the 

Pd DOC, the net vehicle contributions to sulfate concentrations increased from 3.4 to 

15.3 μg/m3

. It seems that catalytic processes in the DOC enhanced the oxidation of sulfur 

dioxide, resulting in sulfate production. On the other hand, the sulfate results show 

reductions in sulfate concentration relative to the baseline when the Donaldson and Filter 

Service DFEs were used. 

53
 
Effects of Filtration Systems on Size Distribution and Number 

Concentration of Aerosols 

The results of size-selective measurements performed at the downstream and upstream 

sampling stations during the filter tests are shown in Figure 25. The upstream 

measurements showed that the background number concentrations of aerosols entering 

the isolated zone during these tests were relatively low when compared to contribution 

from the tested vehicles (see Figure 25). Despite their almost negligible effects on the 

results, the upstream concentrations were included in the calculations of the net 

contribution of the tested configurations to the aerosol concentrations at the downstream 

station. However, when aerosol size distributions were analyzed, the size distributions of 

the upstream aerosols were neglected because of their small effects on the results. 

1.00E+07 

1.00E+06 

1.00E+05 

1.00E+04 

1.00E+03 

1.00E+02 

1.00E+01
 

10 100
 

D_p [nm] 

Muffler Downstream Muffler Upstream 

AM Pd DOC Downstream AM Pd DOC Upstream 

Donaldson Downstream Donaldson Upstream 

Filter Service Downstream Filter Service Upstream 

AM Pd DOC Regeneration Downstream

 Figure 25.–Effects of filtration systems on aerosol size distribution (common ventilation rate = 

19.29 m3

/s). 

dN/dlog(D_p) [#/cm^3] 

1000 

A summary of the statistical analysis results performed on measured size distributions is 

given in Table 14. This table provides the average geometric mean diameters (GMDs), 

average geometric standard deviations (GSDs), and ventilation-adjusted average total 

number concentrations of aerosols for observed size distributions. Two GMDs and GSDs 

are shown for the bimodal distributions. 

54
 
The size distributions measured during the AM DPF with Pd DOC test were found to be 

single-modal distributions with substantially smaller geometric mean and higher peak 

concentrations than that observed for the baseline case (see Figure 25 and Table 14). The 

net contribution of the system to the total particle number was also found to be 105% 

higher (see Table 14) than that of the muffler. During the regeneration of the DPF 

system, the peak aerosol number concentration increased from about 1,666,000/cm3

, 

observed during normal operation, to approximately 3,177,000/cm3

. During the 

regeneration process, the aerosol number concentrations were found to be approximately 

280% higher than those found when the vehicle equipped with a muffler was tested. 

Table 14.—Effects of diesel particulate matter filtration systems on size distribution 

and concentrations of aerosols in mine air 

(common ventilation rate = 19.29 m3

/s) 

Filter 

Tests 

(LHD 2) 

Downstream Upstream Net Contribution 

Avg. GMD, 

nm Avg. GSD Adjusted 

Avg. 

Total 

Number, 

×107-+ 

#/cm3 

Avg. 

GMD 

Avg. 

GSD 

Adjusted 

Avg. 

Total 

Number, 

×107 

#/cm3 

Adjusted 

Avg. 

Total 

Number, 

×107 

#/cm3 

Change, 

Mode %

1 

Mode 

2 

Mode 

1 

Mode 

2 

Muffler 34.2 86.0 1.52 1.69 2.2098 — — 0.0101 2.1997 0.0 

AM DPF 

with Pd 

DOC 

42.5 1.49 4.5337 — — 0.0208 4.5128 –105.2 

Donaldson 24.2 68.3 1.48 1.70 1.6952 — — 0.0692 1.6260 26.1 

Filter 

Service 35.8 73.6 2.14 1.70 1.0360 — — 0.0131 1.0229 53.5 

AM DPF 

with Pd 

DOC, 

Regeneration 

72.2 1.52 8.3654 — — 0.0208 8.3446 –279.3 

Results of measurements obtained with the Donaldson DFE are summarized in Table 14 

and Figure 25. The bimodal size distributions observed during this test were 

characterized by a pronounced nucleation mode peak that was not observed during the 

baseline test. The Donaldson DFE reduced total aerosol number concentrations by 

approximately 26% relative to the baseline case. 

Particles measured during the Filter Service DFE test were also found to have a bimodal 

distribution with a small nucleation mode peak. The Filter Service DFE reduced the 

vehicle’s contribution to total particulate number by approximately 54% relative to the 

baseline. 

The effects of the Donaldson and the Filter Service DFEs on size distribution and aerosol 

concentration were found to be quite different. The size distribution of the particles 

measured during the test with the Donaldson DFE was characterized by much lower 

concentrations in the larger particle size range. By contrast, the size distributions during 

the Filter Service DFE test were characterized by significantly fewer nucleation-mode 

55
 
particles (see Figure 25). This is in agreement with the results of the EC, gravimetric, 

and TEOM measurements, which showed higher EC and TPM reductions for the 

Donaldson versus the Filter Service DFE. 

A substantial increase in the number of particles in the nanoparticle range was observed 

for the Donaldson DFE, but not for the Filter Service DFE. Since carbon analysis shows 

very low EC mass concentrations for the Donaldson element, one can hypothesize that 

these nanoparticles contain primarily other known constituents of DPM emitted in 

ambient air such as organic carbons, sulfates, and water. All of these constituents would 

likely nucleate and/or condense near the tailpipe after passing through the DFE. 

Effects of Filtration Systems on Concentrations of NO, NO2, CO, and CO2 

During the filter tests, concentrations of NO, NO2, CO, and CO2 were measured 

continuously at the upstream, downstream, and vehicle sampling stations. As with the 

fuel tests, concentrations of NO, NO2, and CO at the upstream sampling station were 

found to be below the detection limit of the iTX multigas instrument used in this study. 

Therefore, the net vehicle contributions to gas concentrations were assumed to be equal 

to their concentrations measured at both the downstream and vehicle sampling stations. 

Continuous measurements with the RKI Eagle CO2 monitor at the upstream sampling 

station showed that the CO2 concentration remained relatively constant throughout the 

tests, averaging 321 ppm. This was used as the average background CO2 concentration 

for all tests. 

The net contributions of vehicles equipped with the tested filtration systems to the NO, 

NO2, CO, and CO2 concentrations at the downstream and vehicle sampling stations are 

summarized in Tables 15 and 16, respectively. The average and peak concentrations are 

reported for all successfully completed tests. In addition, peak concentrations recorded 

prior to the premature termination of tests with the AM DPF with a Pt DOC and the 

CAP/ETG CPO system, as well as peak concentrations recorded during the regeneration 

process of the AM DPF system with a Pd DOC, are reported in Tables 15–16. The 

durations of these shortened tests preclude calculating meaningful averages. 

As noted earlier, the peak gaseous concentrations at both the downstream and vehicle 

sampling stations were recorded while the vehicle was performing the part of the duty 

cycle inside and in front of the stope at the downstream load/dump point. 

56
 
Nitric Oxide (NO) 

NO concentrations at the downstream and vehicle sampling locations were found to be 

generally lower during tests with the AM DPF having Pt and Pd DOCs and the CAP/ETG 

CPO system than those during the baseline case. The slight reduction in NO is partially 

attributable to the conversion of NO to NO2 by the DOC. Increases in NO were observed 

during tests using the Donaldson and the Filter Service DFEs. 

Nitrogen Dioxide (NO2) 

NO2 results, presented in Tables 15–16, show that the test vehicle equipped with the 

AM DPF and a Pt DOC increased peak NO2 concentrations at the downstream and 

vehicle sampling stations approximately three times from the baseline concentrations. 

A substantially smaller increase in NO2 concentration was observed when the vehicle was 

fitted with the AM DPF and a Pd DOC. 

Table 15.—Net contributions of filtration system to average and peak NO, NO2, CO, and CO2 

concentrations at the downstream sampling station
 

(common ventilation rate = 19.29 m3

/s) 

Filter Tests 

(LHD 2) 

NO, ppm NO2, ppm CO, ppm CO2, ppm 

Avg. Max. Avg. Max. Avg. Max. Avg. Max. 

Muffler 3.5 12.0 0.1 0.6 0.6 4.0 572 1,574 

AM Pt DOC N/A 8.0 N/A 1.9 N/A 0.0 N/A N/A 

AM Pd DOC 3.1 11.0 0.2 0.8 0.0 0.0 487 1,335 

AM Pd DOC 

Regeneration N/A 11.0 N/A 1.1 N/A 0.0 N/A N/A 

Donaldson 3.6 13.0 0.0 0.2 0.7 4.0 551 1,658 

Filter Service 4.1 13.2 0.0 0.2 0.7 4.1 590 1,783 

CAP/ETG CPO N/A 9.0 N/A 2.9 N/A N/A N/A N/A 

Table 16.—Net contributions of filtration system to average and peak NO, NO2, CO, and CO2
 

concentrations at the vehicle sampling station
 

(common ventilation rate = 19.29 m3/s) 

Filter Tests 

(LHD 2) 

NO, ppm NO2, ppm CO, ppm CO2, ppm 

Avg. Max. Avg. Max. Avg. Max. Avg. Max. 

Muffler 5.4 26.0 0.2 1.6 1.2 9.0 774 3,552 

AM Pt DOC N/A 18.0 N/A 5.7 N/A 0.0 N/A N/A 

AM Pd DOC 3.9 17.0 0.2 1.9 0.0 0.0 554 2,031 

AM Pd DOC 

Regeneration N/A 13.0 N/A 1.6 N/A 0.0 N/A N/A 

Donaldson 6.3 21.1 0.1 0.9 2.2 10.0 747 3,057 

Filter Service 6.3 21.3 0.0 0.5 1.4 9.1 897 2,911 

CAP/ETG CPO N/A 10 N/A 4.1 N/A N/A N/A N/A 

It is important to note that the 19.29 m3

/s (40,874 ft3/min) average ventilation rate 

maintained in the main drift during these tests was significantly higher than the MSHAestablished 5.3 m3

/s (12,000 ft3/min) ventilation rate for the Deutz BF4M1013FC 

57
 
engine. However, despite this relatively high air quantity supplied to the main drift, the 

peak NO2 concentration at the vehicle sampling location exceeded 5 ppm when the LHD 

with the AM DPF and Pt DOC was operated within and in front of the downstream stope. 

In addition, it is then reasonable to assume that if the vehicle with the AM DPF and 

Pd DOC was operated at the MSHA ventilation rate, the peak NO2 concentrations at the 

vehicle sampling location would be approximately 2.5 ppm. 

Figures 26–27 illustrate similar elevated NO2 concentrations recorded during the initial 

test stages on the CAP/ETG CPO system. These situations resulted in a premature 

termination of tests on the AM DPF with Pt DOC and CAP/ETG CPO systems to prevent 

overexposure of the vehicle operator. 

58
 

 

3.5 

3 

2.5 

2 

1.5 

1 

0.5 

0 

0 1000 2000 3000 4000 5000 6000 7000 8000 

Time [s] 

Muffler AM Pt DOC AM Pd DOC CAP/ETG CPO 

Figure 26.—Effects of filtration systems on NO2 concentrations at downstream sampling station 

(common ventilation rate = 19.29 m3

/s). 

NO2 Concentration [ppm] 
 

NO2 Concentration [ppm] 6 

5 

4 

3 

2 

1 

0 

0 1000 2000 3000 4000 5000 6000 7000 8000 

Time [s] 

Muffler AM Pt DOC AM Pd DOC CAP/ETG CPO

 Figure 27.—Effects of filtration systems on NO2 concentrations at vehicle sampling station 

(common ventilation rate = 19.29 m3

/s). 

Carbon Monoxide (CO) 

The net contribution of the vehicle equipped with either an AM DPF and a Pt or Pd DOC 

or the CAP/ETG CPO system to the concentration of CO at the downstream and vehicle 

sampling stations was found to be negligible. CO reductions can be attributed to the 

DOC’s catalytic processes. The DFEs from Donaldson and Filter Service had no 

measurable effect on CO concentration. 

Carbon Dioxide (CO2) 

According to the results of measurements performed at the downstream and vehicle 

sampling stations, the differences in the average and maximum peak concentrations of 

CO2 were much more pronounced between the filter tests than between the fuel tests. 

This can be explained by the fact that the same miner operated the LHD 1 vehicle during 

all of the fuel tests, whereas two different operators operated the LHD 2 vehicle during 

the filter tests. One miner operated the vehicle during the tests on the AM DPF system 

with a Pt or Pd DOC. However, a different miner operated the vehicle during the 

baseline test and the tests on the Donaldson and the Filter Service DFEs. Operator 

driving styles can affect fuel consumption and thus CO2 emissions. 

59
 
Effects of Filtration Systems on Exhaust Temperature 

and Engine Back Pressure 

Results of continuous exhaust temperature and engine back pressure measurements are 

presented in Figures 28–30. Due to equipment problems, results are not available for the 

Donaldson or the Filter Service DFE tests. 

During the test on the AM DPF with a Pd DOC, the exhaust temperatures and engine 

back pressure were recorded during the filter test and during the fuel burner-controlled 

regeneration process. The results are shown in Figure 29. 

450 15 

14 

400 13 

350 12 

Temperature [oC] 

11 

300 10 

9 

250 8 

200 7 

6 

150 5 

4 

100 3 

50 2 

1 

0 0 

0 1000 2000 3000 4000 5000 6000 7000 

Time [s] 

Temperature Back Pressure 

Figure 28.—LHD 2 exhaust temperature and engine back pressure during muffler test. 

Back Pressure [in H2O] 

Peak exhaust temperatures at the filter inlet and outlet and peak engine back pressure 

measured during the filter tests are summarized in Table 17. 

60
 
Exhaust Temperature [oC] 

600.0 

Regeneration

90.0 

100.0 

400.0 

500.0 

Normal Operation 

70.0 

80.0 

60.0 

300.0 50.0 

40.0 

200.0 

30.0 

100.0 

20.0 

10.0 

0.0 

0 2000 4000 6000 8000 10000 12000 14000 16000 

0.0 

Time [s] 

Inlet Temperature Outlet Temperature Back Pressure 

Back Pressure [in H2O] 

 Figure 29.—LHD 2 exhaust temperatures and engine back pressure during testing with an AM DPF 

and Pd DOC. 

450 10 

400 9 

350 8 

Temperature [oC] 300 

7 

200 

250 

4 

5 

6 

150 

3 

100 2 

50 1 

0 

0 1000 2000 3000 4000 5000 6000 7000 

0 

Time [s] 

Inlet Temperature Back Pressure

Back Pressure [in H2O] 

 Figure 30.—LHD 2 exhaust temperature and engine back pressure during testing with Filter 

Service DFE. 

61
Table 17.—Peak exhaust temperatures and engine back pressures measured during the filter tests 

Peak Exhaust Temperature Peak Engine Back Pressure 

Outlet From Start Filter Tests Inlet to Filter Start of End of End of 

Filter of (LHD 2) Test, Test, Test, Test, °C °F °C °F in H2O mbar in H2O mbar 

Muffler 393 740 N/A N/A 16.2 6.5 18.7 7.5 

AM Pd DOC 407 765 332 630 56.2 22.6 87.3 35.1 

Donaldson N/A N/A N/A N/A 10.0 4.0 15.4 6.2 

Filter Service 407 765 N/A N/A 6.2 2.5 6.7 2.7 

AM Pd DOC 408 766 530 985 83.6 33.6 57.2 23.0 Regeneration 

The inlet exhaust temperatures were found to be slightly higher when the vehicle was 

operated with the filter systems instead of a muffler (see Figures 28–30 and Table 17). 

It is important to note that the exhaust temperatures at the inlet filter face of the DFEs 

often exceeded 260 °C (500 °F), the maximum temperature recommended by the 

manufacturers for these elements. 

During the regeneration process, the exhaust temperature at the outlet of the AM DPF 

system with a Pd DOC peaked at 530 °C (985 °F), exceeding the peak exhaust 

temperature of 332 °C (630 °F) observed during normal operation. During regeneration, 

the maximum engine back pressure was reduced to the values measured at the beginning 

of the test. 

Relatively clean DFEs from Donaldson and Filter Service caused less engine back 

pressure than the ceramic filter element used in the AM DPF. Engine back pressure 

imposed by the disposable elements was found to be even lower than that caused by the 

restriction in the muffler. The increase in engine back pressure during the tests with 

DFEs was also less than the increase measured during the test with the AM DPF system. 

62
 
SUMMARY
 

Seven alternative fuel formulations and four filtration systems were tested in the isolated 

zone at the SMC Nye Mine to evaluate the effectiveness of these technologies in 

controlling DPM and gaseous emissions from underground diesel-powered mining 

equipment. The results showed that using the cold-weather water-fuel emulsion 

formulation reduced mass concentrations of EC by about 70%, TPM determined by 

gravimetric analysis by 45%, and TPM determined by the TEOM by 46%. Size 

distribution measurements performed by an SMPS showed a 14% increase in total 

aerosol number concentration. The warm-weather water-fuel emulsion formulation 

reduced EC by about 85%, gravimetric TPM by 58%, and TEOM TPM by 66%. SMPS 

measurements showed about a 16% increase in aerosol number concentration. The 

sulfate results show that both formulations produced similar concentrations as #1 diesel. 

The four tested biodiesel fuel blends, 20% and 50% blends of neat soy biodiesel and 20% 

and 50% blends of neat yellow grease (YG) biodiesel with #1 diesel fuel were found to 

reduce EC and TPM concentrations in mine air. The results showed EC reductions of 

49% and 66% for 20% and 50% soy biodiesel blends, respectively. The reductions were 

slightly less pronounced for the 20% and 50% YG blends (33% and 56%, respectively). 

The 20% YG blend reduced gravimetric TPM concentration by 32%, whereas the 

50% YG blend reduced TPM concentration by 48%. Replacing the muffler with a DOC 

further reduced the TPM concentration of the 50% YG blend to 60%. The results of 

TEOM analysis showed similar reductions in TPM. Sulfate concentrations for all four 

blends tested were reduced roughly in proportion to the lower sulfur content of the 

blended fuel (biodiesel fuel is free of sulfur). The DOC used with the 50% YG blend 

increased the sulfate concentration from 2.6 to 6.6 μg/m3

. The SMPS results indicated 

that the total aerosol number concentrations for the 20% and 50% soy blend were reduced 

by 12% and 21%, respectively; however, the 20% YG blend increased the concentration 

by 10% versus a 27% reduction for the 50% YG blend. Use of the DOC with the 50% 

soy blend reduced the number concentration by 25% compared to the baseline. 

EC and TPM concentrations were unaffected by using ULS diesel in place of #1 diesel, 

whereas the sulfate concentrations decreased from 5.5 to 0.3 μg/m3

. Using a DOC with 

ULS diesel increased the sulfate concentration to 0.8 μg/m3

. SMPS results showed a 

12.8% lower net total aerosol number concentration for the ULS diesel, and using a DOC 

led to further reduction in the number concentration. 

Use of the reformulated fuels and the baseline #1 diesel fuel exhibited similar 

downstream and on-vehicle concentrations of NO and CO. However, a measurable 

increase in the NO2 peak concentration was observed during the biodiesel tests. 

The DOC increased both the average and peak NO2 concentrations at the downstream 

and on-vehicle locations. The tests with 50% soy biodiesel showed that use of the DOC 

increased the net ventilation-adjusted average and peak NO2 at the vehicle by 31% 

and 92%, respectively. Similarly, the tests with ULS diesel showed that use of the 

DOC increased the equivalent NO2 concentrations by 24% and 58%, respectively. The 

63
 
peak concentrations that had been approaching 3 ppm occurred while the vehicle was in a 

short stope off the main drift during the loading/dumping simulation. When those peaks 

occurred, the ventilation rate in main drift was over 19 m3

/s (40,258 ft3/min), a quantity 

that is more than double the accepted minimum for this engine. Use of the DOC 

rendered downstream and on-vehicle CO concentrations undetectable. 

The ArvinMeritor (AM) fuel-burner DPF system with a palladium (Pd) catalyzed DOC 

reduced EC concentrations by 92%. The same system reduced downstream concentrations of TPM by 69% (gravimetric) and by 72% (TEOM). The Pd-catalyzed DOC 

increased the sulfate concentration from 3.4 to 15.3 μg/m3

. SMPS results indicated a 

105% increase in the total particle number, possibly corroborating the hypothesis of 

increased concentrations of sulfate aerosols. During the regeneration of the AM DPF 

system, the peak aerosol number concentration increased from about 1,666,000/cm3

, 

observed during the normal operation, to approximately 3,177,000/cm3

. 

The DFEs from Donaldson and Filter Service reduced the vehicle EC contribution by 

92% and 70%, respectively. The same DFEs reduced downstream TPM concentrations 

determined by gravimetric analysis by 84% and 58%, respectively. TEOM-determined 

TPM concentrations were reduced by 76% and 65%, respectively. Sulfate concentrations 

were reduced by both DFE systems. SMPS results for the Donaldson DFE showed a 

bimodal distribution characterized by significantly smaller particles compared to the 

baseline and reduced the total number of particles by 26%. The Filter Service DFE 

reduced the total particle number by 54%. 

The AM DPF with the Pd DOC system reduced the NO concentrations at the downstream 

and vehicle stations. The DFEs, on the other hand, increased the NO concentrations. 

When the Pt-based DOC was used with the AM DPF, it raised the peak downstream NO2 

concentrations by a factor of three (from 0.6 to 1.9 ppm). The prevailing ventilation rate 

in the main drift during that test was about 3.3 times the MSHA rate (5.3 m3

/s (12,000 

ft3

/min)) for the test engine. Nevertheless, the on-vehicle peak NO2 for the AM DPF 

Pt DOC system exceeded the 5-ppm MSHA ceiling limit (30 CFR 57.5001). When the 

Pd-based DOC was used with the AM DPF, however, the average downstream NO2 only 

increased from 0.6 to 0.8 ppm. Tests of the AM DPF system with Pt DOC and CAP/ETG 

CPO system had to be terminated because the elevated NO2 concentrations threatened to 

overexpose the operator. 

The AM DPF with either DOC as well as the CAP/ETG CPO system rendered the 

downstream and on-vehicle CO concentrations undetectable. The DFEs from Donaldson 

and Filter Service were found to have no measurable effect on CO concentration. 

Finally, our study also revealed a number of potential challenges related to economic and 

technical aspects of implementing the studied control technologies into underground 

mines. The successful implementation of control technologies was found to be 

predicated on addressing a number of issues that are relatively unique to each mine and 

even to individual applications within a given mine. Those issues need to be further 

researched. 

64
 
ACKNOWLEDGMENTS 

We gratefully acknowledge the contribution of Stillwater Mining Co., which hosted the 

study. Special thanks go to Richard Anderson, Daniel Milton, and Cody Cline for 

preparing the test vehicles, installing aftertreatment systems, and securing the fuel supply 

and to Carla Allen for preparing the test site. We also thank Richard Ivie, Dave Boyd, 

and Pat Brady for operating the vehicles during the isolated zone tests. 

65
 
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67
 
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