January 15, 1997
updated February 9, 1998
In view of the recent review of health effects of diesel particulate matter (DPM) by the American Conference of Governmental Industrial Hygienists (ACGIH) and their notification that the Threshold Limit Value for DPM will be set at 0.15 mg/m3, the Diesel Emissions Evaluation Program (DEEP) is being formed by the collaboration of industry, labour, government and researchers in Canada and the United States with the goal of reducing underground miners’ exposure to diesel emissions. This goal will be achieved by focusing on two primary research objectives: 1) evaluating aerosol sampling and analytical methods for DPM, as well as developing means to distinguish between DPM and oil mist; and 2) evaluating the in-mine performances and costs of various diesel exhaust control strategies.
This document provides an overall framework for DEEP, out of which individual projects at specific mine sites will be defined and sponsored. Each shareholder of DEEP will make annual financial commitments to DEEP, but will decide which specific projects it wishes to sponsor.
It is imperative that all affected and interested parties participate fully in individual project planning and execution. The DEEP organizational structure consists of a Program Management Committee, a Technical Committee, a secretariat and treasurer. CAMIRO Mining Division acts as treasurer while the secretariat duties are performed by Natural Resources Canada.
This document provides a description of the Diesel Emissions Evaluation Program (DEEP). Rather than being a proposal for conducting work, this description provides the framework from which specific research proposals will be solicited. The overall purpose of DEEP is to evaluate: (1) aerosol sampling methods for diesel particulate matter (DPM) and (2) strategies to reduce miners’ exposure to diesel exhaust pollutants.
The Canadian ad hoc Diesel Committee met in Markham, Ontario, on March 26-27, 1996 to discuss issues pertaining to diesel exhaust exposure and control in mining. A major topic of discussion at this meeting, and three Diesel Workshops sponsored by the U.S. Mine Safety and Health Administration (MSHA) in the Fall of 1995, was the addition by the American Conference of Governmental Industrial Hygienists (ACGIH) of DPM and oil mist to the Notice of Intended Changes for 1995-96. For the first time the ACGIH proposed, after reviewing available animal and human health studies, a threshold limit value (TLV) of 0.15 mg/m3 for DPM and a reduction to 0.2 mg/m3 for some oil mists. If these values are adopted as permissible exposure limits, many mines in Canada and the U.S. would have difficulty meeting this limit at all times.
The ad hoc Diesel Committee agreed that the goal of reducing exposure to diesel emissions was best accomplished by collaboration of the several sectors having a stake in reducing exposure. These sectors include: mine operators, labour, regulators, fuels and additive producers, equipment (machine, engine and exhaust emission controls) manufacturers, and Canadian and U.S. research agencies. The Committee further endorsed the concept of a North American consortium to conduct diesel research and appointed a Steering Committee to guide the formation of the consortium and to specify objectives of DEEP.
The goal of DEEP is to reduce miners’ exposure to diesel exhaust pollutants by systematically testing and evaluating control strategies to reduce diesel emissions at specific mine sites. Specific objectives include:
It will also be necessary to carry out laboratory evaluations of promising, but untested, emission control methods to determine their safety, feasibility, and effectiveness.
Specific research priorities were identified by the ad hoc Committee in Markham. These included evaluation of: DPM aerosol measurement methods, modern engine technology, alternative fuels and fuel additives, exhaust emission control technologies, and engine maintenance.
The Steering Committee recognizes that the formation of DEEP will be done according to the requirements of its sponsors. However, in order to give potential sponsors some understanding of how DEEP is currently being viewed by interested stakeholders, the following potential organizational structure is presented.
Organization of Research Activities: The large scale and complexity of the program require that research be coordinated to avoid duplication and that the research teams collect a minimum set of data to allow sampling and control strategies to be accurately evaluated and compared. Each site-specific, demonstration project team will collect similar types of data using questionnaires and on-site data collection techniques, as follows.
The first requirement will be to identify mines willing to participate as sites for various DEEP projects. Data on potential sites will be collected by using detailed questionnaires for both mine management and miners covering the nature of diesel operations and other mine characteristics that will influence the decision on whether to include the mine in the overall DEEP framework.
Air quality measurements will be carried out on constituents such as: CO, CO2, NO, NO2, SO2, DPM, drill oil mist, hydrocarbons, sulfate fraction of DPM, respirable dust, respirable quartz and particle size distribution data. DPM measurements will be made using respirable combustible dust (RCD), size selective (SS) and elemental carbon (EC) methods.
Engine maintenance, duty cycle, fuel consumption, exhaust temperature and back pressure, and production data for vehicles used in the test section will be documented.
Ventilation data on the test section will be collected.
The metal and nonmetal mine sites selected as hosts for DEEP projects should represent a variety of mining operations from the point of view of diesel fleet, mining method, size and production parameters. The mines should produce different types of products (metal and nonmetal) to ensure the entire spectrum of diesel equipment is represented. The type of orebody will affect the selection of the aerosol methods used to evaluate DPM control. For example, one of the sites selected should have a high sulfide orebody, because this type of ore is suspected to interfere with the RCD analytical method. Other mine settings (salt, nickel/copper, zinc/lead) may reveal problems with the other sampling and analytical methods. Prospective mines will be expected to comply with all standards governing diesel usage before studies will commence. Studies will not be conducted at mines which do not meet these standards.
Objective: The objective is to compare and evaluate three currently available methods for sampling and analyzing DPM. Past research conducted in Canada and the U.S. has raised questions concerning the accuracy and precision of the three aerosol methods (RCD, SS and EC) used to sample for DPM. The Canadian ad hoc Committee strongly recommended that these methods be compared and evaluated underground. The results of this comparison will permit proper interpretation of exposure data and evaluation of the control methods. It is unlikely that any one method will, by itself, be completely satisfactory for evaluating all control strategies, thus it is likely that more than one aerosol measurement method will be required in the control evaluation portion of the research program.
Approach: Arrays of DPM aerosol samplers (RCD, SS and EC) will be installed at selected locations in the mine test section, such as the test section intake and exhaust airways and on the diesel production equipment. The exact number of samplers deployed will depend on the number required to yield satisfactory statistical results and will be determined through preliminary tests. Additional aerosol samplers such as micro-orifice uniform deposit impactors (MOUDI’s), real-time aerosol monitors (RAM) and an array of dichotomous samplers will likely be used to collect additional data necessary to interpret the results accurately. Ore samples will be analyzed for sulfur and carbon content, and accurate records will be maintained regarding mining activity, and diesel use.
Each method provides slightly different information which will assist in interpreting results. RCD provides estimates of the respirable mine aerosol concentration and the fraction of the aerosol that is combustible (assumed to be mainly diesel in origin). The RCD method provides a measurement of the entire DPM fraction of the respirable aerosol, plus other respirable aerosols which are combustible such as oil mist. The SS method separates the respirable aerosol into two size fractions. The portion of the respirable aerosol less than 0.8 µm is assumed to be mainly diesel in origin. Both the RCD and SS methods are limited by the error associated with gravimetric analysis.
The elemental carbon method measures the carbon fractions of the respirable aerosol using thermo-optical analysis. Estimates of the elemental carbon (EC), organic carbon (OC) and the total carbon (TC) are obtained, with nearly all of the EC portion of the respirable aerosol coming from diesel exhaust. This method is extremely sensitive and provides a surrogate measurement of DPM. Since the EC method is limited by filter loading, the sampling array may include the impactor used in the SS method.
None of these methods directly measures the respirable oil mist fraction apart from other respirable aerosols. Analytical methods developed by Inco at their Central Process Technology laboratory and by NIOSH will be evaluated to determine this portion of the aerosol.
Objective: The intent of this research program is to demonstrate and evaluate control strategies that are commercially available, or that have been demonstrated through laboratory testing to be safe and ready for field evaluation. With respect to previously proven technology, however, it is the intent of this program to duplicate past research only when necessary to obtain additional data to quantify exposure reduction effectiveness, and cost. The following strategies are possible candidates for evaluation either singly or in combination (the list is not intended to be comprehensive, nor does the order of the list indicate priority):
Experimental approach: Due to the site specific nature of the demonstration projects, the complexity, the heavy involvement of the mine and the need for thorough coordination amongst all participants, a detailed approach is not included here, but instead will be spelled out in each site specific project workplan.
Generally, it is envisioned that DPM, oil mist aerosols and selected gases (CO, CO2, NO, NO2, SO2) will be measured before and after each control strategy is implemented. In the simplest scenario, measurements will be made in the section intake airway, on the production vehicle near the vehicle operators location and in the section exhaust airway. Since the concentration of DPM and gaseous pollutants generated within the selected section depends on ventilation airflow and vehicle duty cycle, data will be recorded to monitor these parameters.
Analysis of data and costs of controls: Data will be collected on the mine’s diesel fleet to determine if the control option being tested could be used at other sites in the mine and to project the costs of the control. Useful information that will be collected includes: equipment type, manufacturer, model, engine type, emission controls, age, general location and use.
To ensure that the control strategies being demonstrated receive a fair evaluation the duty cycle of the production vehicles will be observed. Observers will record the production activities of these vehicles in the test section by breaking the production cycle into the various elements. The time needed to complete each element will be recorded. This information will be used to ensure that improvements in air quality observed in subsequent phases of the project are due to reductions in emissions and not due to changes in vehicular duty cycle. Fuel consumption, production and exhaust parameters will also be monitored to provide further information on duty cycles. This information will assist in data interpretation and in cost projection.
Pre- and post-engine inspection: Inadequate engine maintenance can significantly increase diesel exhaust emissions and interfere with the accurate evaluation of control strategies. Prior to the evaluation and demonstration of the control strategies, project staff, in conjunction with mine maintenance personnel and perhaps an authorized dealer representative, will determine the state of engine maintenance of the production vehicles to be used in the test section. Deficiencies will be fixed prior to the start of the study.
To ensure the control strategy had no ill effect on the test vehicle engines, a postengine inspection will be conducted.
Engine Emission Testing: Tail pipe exhaust emissions measurements, especially DPM measurements, are useful to establish an emission reference for comparison during the air quality study. Before and after the engine inspections, the test vehicles emissions may be measured either with portable equipment such as the “tail pipe sniffers” being developed by Noranda and others, laboratory grade equipment brought underground, or from engines removed from the vehicle and tested in the laboratory. If possible, this evaluation will include an evaluation of emissions before the in-mine studies begin, and at periodic intervals after the completion of the tests, to determine the impact of maintenance on emissions. Emissions will be evaluated using portable instrumentation while operating the engine on a dynamometer (if available) or during torque converter stall.
Diesel fuel and oil chemical analysis: The quality of both the diesel fuel and the lubrication oil is important in an engine maintenance program. Fuel contamination can occur during the transfer process from a mine’s bulk storage to vehicle fuelling. To assure proper transfer of fuel, samples will be taken from the mine’s bulk fuel storage above ground, main storage tank underground, and from the nozzle of underground fuel vehicles. All fuel samples will be analyzed for sulfur content. This is particularly important if the mine is using catalytic exhaust emission control devices which perform most effectively with low sulfur fuel. Irregularities will be noted and recommendations made to correct deficiencies.
Information on the type of drill oil will also be collected, and if necessary, samples will be collected for chemical analysis. This information will assist in differentiating drill oil mist aerosol from DPM aerosol.
Ventilation: Ventilation is the primary means of reducing contaminant concentrations. Since airflow dilutes contaminant concentrations, including diesel aerosol, knowledge of ventilation parameters are necessary for the interpretation of pollutant data. Prior to the start of the study, the mine operator will provide ventilation data for the test section to ensure that all required air volumes are met. If the ventilation data shows that the section has inadequate air quantity, the mine operator will be requested to correct this condition before further studies are conducted. In certain instances, it may be desirable to acquire additional ventilation data that could be useful in optimizing fresh air distribution without increasing the total air volume provided to the mine.
Project support by the mine: Co-operation of each host mine is critical to the success of the DEEP program. The selected mines will generally provide basic safety training and equipment for visiting personnel, required electrical power for instruments, and space for sampler pump recharging and calibration. The mines will also provide vehicles for the transportation of personnel, equipment and materials on a daily basis. Mine management will provide personnel to facilitate the study and ensure safety.
A significant portion of the anticipated impact of this research program rests on the knowledge and technology which will be transferred to the mine sites and mine personnel involved with the project. Project technical staff will train mine personnel, including worker representatives, in the methods to be used during the air quality surveys and control evaluation portions of the research. The objective of the training is to familiarize these staff with the methods so that they can participate fully in the underground mine study, and pass along the information to other mine personnel. Subject matter would be presented to selected mine engineers, technologists and representatives of the safety and health committees prior to the start of the study. The content of the presentations would include: project overview, aerosol sampling basics, and control strategy information.
Results from this research program will be published and presented in technical papers and meetings and reported in contract reports. Emphasis will be placed on presentations before the Canadian ad hoc Diesel Committee and publication in refereed mining journals.