Supplementary NPRI reporting guide for the base metal smelting and refining sector

This document provides information to help you estimate emissions of certain National Pollutant Release Inventory (NPRI) substances related to operations at facilities in the base metal smelting and refining sector (BMS). It provides estimation methods and factors, as well as links to useful tools.  

For complete information about the NPRI reporting requirements (all substances and sources), refer to the Canada Gazette Notice and the Guide for reporting to the NPRI. 

Background

Environmental performance agreements between ECCC and base metals smelting and refining companies came into effect on January 5, 2018, and will remain in effect until December 31, 2025. 

In October 2012, federal, provincial and territorial environment ministers took action to better protect human health and the environment by endorsing and implementing the Air Quality Management System (AQMS). The AQMS includes Canadian Ambient Air Quality Standards (CAAQS) for fine particulate matter (PM_2.5) and ground-level ozone, Base Level lndustrial Emissions Requirements (BLIERs) and local Air Zone Management by the provincial/territorial jurisdictions. The BLIERs are quantifiable requirements aiming to ensure that all significant industrial sources of pollutants in Canada meet a good base level of environmental performance.  For the BMS sector, performance agreements (PA’s) were chosen to implement the BLIERs that were developed for releases of sulphur dioxide (SO₂) and particulate matter (PM). When the BLIERs were being developed, the expert group recommended BLIERs with the same stringency as the targets presented in the 2006 pollution prevention planning notice for base metals smelters and refineries and zinc plants which was set to end in 2015. One of the recommendations from the BLIERs development was for facilities to agree to continual improvement, where reasonably feasible, to further reduce emissions of SO₂ and PM, as well as reduce emissions of metals and fugitive emissions of PM. Within the agreements themselves, under Section 9.3, each signatory agreed to participate in a working group, with representatives from ECCC, provincial governments, other companies in the base metal sector, and the Mining Association of Canada, to assess the consistency and robustness of the data reported to the NPRI. This included developing sector-wide recommendations with respect to:

• quantifying emissions of condensable PM
• quantifying emissions of PM_2.5 
• quantifying fugitive emissions of PM
• reporting fugitive emissions of PM
• quantifying emissions of key metals^{Footnote 1}

Due to the complex processes taking place at some BMS facilities and some facilities having numerous sources of air releases, for the purposes of reporting to the NPRI, BMS facilities use one or more of the methods presented below: 

• continuous emission monitoring systems (CEMS)
• predictive emission monitoring (PEM)
• source testing
• mass balance 
• site-specific emission factors
• published emission factors
• engineering estimates
• speciation profiles 
• remote quantification

The efforts undertaken by the working group have resulted in the recommendations presented below that focus on the quantification of fugitive emissions of PM, emissions of PM_2.5 and emissions of metals as well as the reporting of fugitive emissions of PM. The recommendations were developed to clarify where certain sources of PM emissions should be reported and the best way to quantify the emissions from those sources. This guide also presents a tiered approach as to the best method(s) to quantify fugitive emissions of PM, emissions of filterable PM_2.5 and emissions of metals. Tier 1 is presented as the preferred method to estimate emissions from each source. Tier 2 is the next best choice and so on. Each facility should use the method(s) that best represents their situation.

Quantifying emissions of condensable PM

The formation of condensable PM is not unique to BMS facilities; all industrial facilities that combust fuel(s) create condensable PM. Condensable PM is considered to be PM_2.5. ^{Footnote 2}  Quantification methods for PM_2.5 are presented in the next section.

The current NPRI requirements are to report only filterable PM and not condensable PM. In some cases, it may only be possible to generate a PM estimate that includes condensable PM.  When this occurs, the facility can identify (via the reporting application) that the PM estimate includes condensable PM. 

The NPRI is considering adding a new category that would be specific for condensable PM. This potential new category is for future consideration because of several reasons, including a lack of appropriate sampling methods for condensable PM across all sectors, as well as the need to maintain consistency with international reporting obligations (NPRI data is used to help compile air pollutant inventories under programs such as UNECE Convention on Long-range Transboundary Air Pollution). ECCC Scientists and Experts are working to develop appropriate methods.   

If NPRI reporting requirements are changed to include the requirement to report condensable PM, this document will be updated to provide information on estimation methods for this substance. 

Quantifying stack/point source emissions of PM_2.5

Typically, filterable PM_2.5 is released via stack/point sources. For BMS facilities, the majority of PM_2.5 releases are from stack/ point sources but there are instances where facilities report PM_2.5 as fugitives as well. The fugitive quantification portion of this guidance also covers the quantification of fugitive emissions of PM_2.5. Quantification of PM_2.5 from stack/point sources are set by each province through provincial regulations and/or operational permits. 

ECCC recommends choosing the most appropriate of the following for each stack/point source of PM_2.5: 

Tier 1  

• Use US EPA Method 201A 

Tier 2 

• Use a modified US EPA Method 201A (or approved provincial methodologies (such as ON-7 Determination of Size Distribution of Particulate Matter from Stationary Sources)) 

Tier 3a  

• Use site specific emission factors based on previous stack testing results  

Tier 3b 

• Use site specific emission factors based on analysis of collected particulate to determine metals fraction 

Tier 4  

• Use published emission factors for appropriate sources

Identifying sources of fugitive emissions of PM

For the NPRI, fugitive emissions of PM are considered to be releases to air that do not occur through a confined air stream, i.e., releases that do not pass through a stack, chimney, vent, or other functionally equivalent opening designed to direct or control its flow. Typically, these releases do not pass through pollution control equipment. More specifically, for the BMS sector, sources of emissions of fugitive PM are: 

• Releases to air from building general exhaust ventilation systems that use dilution air to disperse and exhaust process emissions and that do not pass through control equipment, or a vent designed to direct or control flow prior to being released to the atmosphere. These exhaust systems include:
  • Roof fans
  • Roof vents
  • Roof monovents
• Releases to air from wind erosion from both open storage piles and open areas (materials include ore, ore concentrate, tailings and waste rock, etc.)
• Releases to air from loading and unloading of materials
• Releases to air from movement of materials (conveying, transferring, hauling)
• Releases to air from processing of materials (screening, crushing, grinding, spreading)
• Releases to air from enclosed storage of solids inside silos and bunkers, and related transfer and loading/unloading operations
• Releases to air from paved roads (for future consideration only since this is not currently an NPRI requirement)
• Releases to air from individual small release points that cannot be practically inventoried separately because they are too small, too numerous or too geographically dispersed 
• Releases to air (including evaporative losses) from any other land treatment, tailings, waste rock, space heating, cooling towers, solvent use, wastewater treatment, etc.

Note that while releases of PM from vehicular traffic on unpaved roads are a type of fugitive release, these are reported to the NPRI under a separate category: unpaved road dust. 

The following sources have been identified as being potential sources of fugitive emissions of PM from the BMS sector:

• Buildings (i.e. general exhaust ventilation systems)
• Wind erosion from storage piles and open areas
• Materials Transfers – lifting and dropping 
• Crushing 
• Dumping & Spreading 
• Screening & Belt Conveying
• Paved Roads
• Plant Heating 
• Cooling Towers

Quantifying and reporting fugitive emissions of PM

Table 1 contains recommendations for quantification of identified fugitive emissions of PM sources within the BMS sector. These recommended quantification methods include guidance for all PM size fractions (Total particulate matter (TPM), PM with a diameter less than or equal to 10 micrometers (PM₁₀) and PM with a diameter less than or equal to 2.5 micrometers (PM_2.5)). Each facility should also ensure that all potential sources of fugitive emissions of PM are quantified and reported.

Quantifying stack/point source emissions of metals

Metals are released via stack/point and fugitive sources. The fugitive quantification portion of this guidance also covers the quantification of fugitive metals. Quantification of metals from stack/point sources are set by each province through provincial regulations and/or operational permits. 

ECCC recommends choosing the most appropriate of the following for each stack/point source of metals:  

Tier 1  

• Use US EPA Method 29 

Tier 2 

• Use a modified US EPA Method 29 

Tier 3  

• Use CEMS or opacity for PM and correlate back to metals fraction within PM 

Tier 4a 

• Use site specific emission factors based on previous stack testing results  

Tier 4b  

• Use site specific emission factors based on analysis of collected particulate to determine metals fraction 

Tier 5 

• Use published emission factors for appropriate sources

References

• [U.S EPA, 2020] United States Environmental Protection Agency. 2020. Air Emission Measurement Center (EMC), Method 201A - PM₁₀ and PM_2.5 - Constant Sampling Rate Procedure. Available on-line at: Method 201A - PM₁₀ and PM_2.5 - Constant Sampling Rate Procedure (epa.gov).
• [U.S EPA, 2006] United States Environmental Protection Agency. 2006. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 13, Miscellaneous Sources, section 13.2.5: Industrial Wind Erosion. Available on-line at: AP-42, CH 13.2.5: Industrial Wind Erosion (epa.gov).
• [U.S EPA, 2011] United States Environmental Protection Agency. 2011. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 13, Miscellaneous Sources, section 13.2.1: Paved Roads. Available on-line at: AP42 13.2.1 Paved Roads (epa.gov).
• [U.S EPA, 2006b] United States Environmental Protection Agency. 2006. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 13, Miscellaneous Sources, section 13.2.4: Aggregate Handling and Storage Piles. Available on-line at: AP42 13.2.4 Aggregate Handling and Storage Piles (epa.gov).
• [U.S EPA, 1995] United States Environmental Protection Agency. 1995. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 11, Mineral Products Industry, section 11.24: Metallic Minerals Processing. Available on-line at: AP42 11.24 Metallic Minerals Processing (epa.gov).
• [U.S EPA, 1998] United States Environmental Protection Agency. 1998. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 11, Mineral Products Industry, section 11.9: Western Surface Coal Mining. Available on-line at: AP42 11.9 Western Surface Coal Mining (epa.gov).
• [U.S EPA, 2004] United States Environmental Protection Agency. 2004. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 11, Mineral Products Industry, section 11.19.2: Crushed Stone Processing and Pulverized Mineral Processing. Available on-line at: AP42 11.19.2 Crushed Stone Processing and Pulverized Mineral Processing (epa.gov).
• [U.S EPA, 1998b] United States Environmental Protection Agency. 1998. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 1, External Combustion Sources, section 1.4: Natural Gas Combustion. Available on-line at: AP42 1.4 Natural Gas Combustion (epa.gov).
• [U.S EPA, 1995] United States Environmental Protection Agency. 1995. AP-42, Fifth Edition Compilation of Air Pollutant Emissions Factors, Volume 1: Stationary Point and Area Sources, Chapter 13, Miscellaneous Sources, section 13.4: Wet Cooling Towers. Available on-line at: AP42 13.4 Wet Cooling Towers (epa.gov).