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Red Dog Operations Update

Red Dog Mine Sulfur Dioxide Update

Sulfur Dioxide (SO2) emissions are naturally present at Red Dog due to the nature of the ore. Recently, increased iron sulfide in the material being mined has led to higher emission levels.

Teck is actively managing Sulfur Dioxide (SO2) at our Red Dog Operations. First and foremost, the health and safety of our personnel is our top value. Monitoring and Mine Safety and Health Administration (MSHA) inspections show that emission levels are within federal mine safety and health standards for SO2 exposures.

This increase, coupled with recent low temperatures and low winds, has caused emissions to settle in lower-lying areas near the mining operation.

Red Dog is working closely with NANA, external experts and the federal Mine Safety and Health Administration (MSHA), to monitor emission levels and take actions to reduce emissions and protect continued health and safety for workers. This includes:

  • Increased monitoring
  • Raising fresh air intakes for buildings to higher elevation
  • Installing carbon air filters in air handling units to reduce concentrations in facilities 
  • Fitting all personnel with respirators 
  • Limiting the number of personnel on site
  • Cooling reactive ore using water trucks to reduce the SO2 generating reaction 
  • Exploring options for disposal of highly reactive waste rock in ways that minimize the potential for oxidation and SO2 release.
  • Reducing production from certain areas of the pit

Monitoring is being conducted to confirm emission levels are within federal mine safety and health standards for SO2 exposures. Monitoring data and mitigation plans were reviewed with MSHA during recent inspections.  No citations related to SO2 were issued. 

As mitigation efforts have progressed, the criteria to return all employees to site have now been met. Employees who were temporarily relocated offsite have resumed their regular schedules.

The Incident Management Team (IMT), which was activated until the health risk to personnel was sufficiently reduced, has now stood down. SO₂ Management Meetings, which include Red Dog senior leadership, select department representatives, and NANA leadership, will continue to meet to develop and advance actions to mitigate SO₂ generation at the mine.

For any questions or concerns, please contact us at rd-ca@teck.com or 907-754-5168

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Download FAQs 

  • SO2 is a colorless gas that is heavier than air and has a pungent order. It is not flammable. SO2 is generated when oxygen in air reacts with iron-rich rock (oxidation).
  • Normally this would not be an issue while in the ground, however when the rock is mined and exposed to air, it heats up and can release SO2 gas.
  • A similar reaction occurs with packet-style hand warmers, which contain iron. When opened, they are exposed to oxygen in the air, which reacts with the iron and creates heat.
  • Sulfur Dioxide (SO2) emissions are naturally present due to the nature of the ore at Red Dog. Recently, increased iron sulfide in the ore currently being mined has led to higher emission levels.
  • When ore and waste rock are mined, the rocks are exposed to air and generate heat energy, resulting in the release of SO2, and if water is present, steam.
  • While SO2 emissions have been present at Red Dog since the 1990s, current deposit ore and waste rock contain high iron levels, creating “hot spots” within the pit. These hot spots release SO2 gasses and recent low temperatures, and low winds have allowed emissions to settle in lower-lying areas.
  • At Red Dog, the safety and health of the personnel on site is our top value. Red Dog is working closely with the federal Mine Safety and Health Administration (MSHA), as well as external experts, to monitor emission levels and take actions to reduce emissions and protect continued health and safety for workers, and keeping NANA informed.
  • This includes increased monitoring, raising fresh air intakes to higher elevation, and installing carbon air filters on air handling units in buildings, including the camp residence, to reduce concentrations in facilities.
  • We are also fitting all personnel with respirators, limiting the number of personnel on site, cooling reactive ore using water trucks to reduce the SO2 generating reaction, and reducing production from certain areas of the pit.
  • Monitoring is being conducted to confirm emission levels are within federal mine safety and health standards for SO2 exposures. Monitoring data and mitigation plans were reviewed with MSHA during recent inspections.  No citations related to SO2 were issued.
  • In the event SO2 levels exceed mine safety and health standards, emergency response personnel have protocols in place to move personnel from an area of higher concentration to safe muster areas of low concentration until the SO2 levels reduce sufficiently.
  • Out of an abundance of caution, we are reducing the number of personnel on site until key mitigation measures are in place, which we anticipate to be in the near future.
  • Personnel who are required to work onsite but have concern for potential health risks will be evaluated by Medics to determine whether they have elevated risks to exposure.
    • If the Medic finds the employee has an elevated risk from exposure, they will be put on Administrative Leave with Pay until the human health risk to employees is sufficiently resolved.
    • If the Medic finds the employee does not have an elevated risk of exposure, they have the option to be put on unpaid leave.
  • Red Dog adheres to the NIOSH exposure limits of 10 hours TWA (Time Weighted Average at 2ppm and 15 minutes STEL (Short Term Exposure Limit) at 5ppm. This is a stricter (more conservative) exposure limit than federal standards require.
  • Red Dog is working closely with NANA, external experts, and the federal Mine Safety and Health Administration (MSHA), to monitor emission levels and take actions to reduce emissions and ensure continued health and safety for workers.
  • An SO2 management team meets 4 times a week to develop and advance actions to mitigate SO2 generation in the mine and potential exposure to the workforce.  This includes a representative from NANA leadership.
  • Main Pit Dump #4 (MPD4) has been identified as a hot spot for SO2 emissions. To reduce emissions, a water truck is being used to cool MPD4. A pipe bench is also being developed to provide an increase of water to the area.
  • All air handlers have been moved to recirculation mode with only the minimal make up air being drawn to maintain positive pressure in the facilities.
  • Air intakes for the Personnel Accommodation Complex (PAC) are being relocated to reduce ingress of SO2 into the living accommodations.
  • Activated carbon filters have been installed in the air handler units in support of enhanced SO2 removal.
  • We are securing enhanced media filtration systems to install in the HVAC to scrub more SO2 out of the air intakes.
  • Numerous monitoring systems have been installed to support early detection of SO2, and we are procuring more.
  • We currently have nine (9) SO2 portable detectors stationed inside the PAC, Mill and Service Complex areas for continuous monitoring. In addition, the Safety and Health Department team is performing manual readings using handheld SO2 monitoring devices across fifteen (15) locations outside the PAC, Mill and Service complex areas on day and night shifts. Monitoring around the Mine, Airport and Construction Camp locations is also being performed by the Red Dog Fire Department.
  • To further transition from manual readings to real-time stationary monitors, fifteen (15) outdoor semi-stationary monitors, twenty-eight (28) indoor stationary monitors and twenty-six (26) HVAC intake duct monitors have been ordered with an expected delivery date in mid-January.
  • The Mine Safety and Health Administration (MSHA) has completed two separate inspections onsite to ensure compliance with federal regulations. 
  • Monitoring and MSHA inspections show that emission levels are within federal mine safety and health standards for SO2 exposures.
  • Additionally, the MSHA inspector reviewed Red Dog’s risk assessment for the mitigation plan to cool the material reacting in Main Pit Dump 4 (MPD4). The inspector was satisfied with the methodology and risk controls proposed to mitigate the hazards and protect the miners while performing mitigation activities.
  • In addition to monitoring and mitigation efforts, Red Dog is preparing for potential elevated SO2 events. 
  • Incident Management Team (IMT) Drills and Tabletop Exercises are being developed to refine our response to potential events.
  • Critical roles such as the Mill Control Room Operator and Powerhouse Operators have staged personal protective equipment (PPE).
  • Yes. The Food and Drug Administration (FDA) allows SO2 and other sulfites as food preservatives but requires mandatory labeling if food items contain greater than 10 parts per million (ppm). No readings in the food preparation and distribution areas have exceeded 10 ppm.
  • Out of an abundance of caution, NMS has engaged the Alaska Department of Environmental Conservation (ADEC) to determine whether any additional controls should be considered at this time.
  • Impacts of SO2 may be determined by several factors including the dose (amount) and method of contact (for example, by breathing, eating, drinking, or touching). Other considerations include your age, sex, diet, family history, lifestyle, and health.
  • Under low concentrations (<5ppm), inhaling SO2 can cause irritation to the nose, eyes, throat, and lungs. Those with preexisting respiratory conditions may experience symptoms at concentrations as low as 0.25ppm.
  • Unprotected exposure to high concentrations of SO2 can cause permanent damage to the lungs.
  • Symptoms can be worsened by preexisting health conditions like asthma.
  • Health effects can be prevented or mitigated with respiratory protection equipment with appropriate cartridges.
  • Monitoring and MSHA inspections show that emission levels are within federal mine safety and health standards for SO2 exposures.

For any questions or concerns, please contact us at rd-ca@teck.com or 907-754-5168

  • SO2 is a colorless gas that is heavier than air and has a pungent order. It is not flammable. SO2 is generated when oxygen in air reacts with iron-rich rock (oxidation).
  • Normally this would not be an issue while in the ground, however when the rock is mined and exposed to air, it heats up and can release SO2 gas.
  • A similar reaction occurs with packet-style hand warmers, which contain iron. When opened, they are exposed to oxygen in the air, which reacts with the iron and creates heat.
  • Sulfur Dioxide (SO2) emissions are naturally present due to the nature of the ore at Red Dog. Recently, increased iron sulfide in the ore currently being mined has led to higher emission levels.
  • When ore and waste rock are mined, the rocks are exposed to air and generate heat energy, resulting in the release of SO2, and if water is present, steam.
  • While SO2 emissions have been present at Red Dog since the 1990s, current deposit ore and waste rock contain high iron levels, creating “hot spots” within the pit. These hot spots release SO2 gasses and recent low temperatures, and low winds have allowed emissions to settle in lower-lying areas.
  • At Red Dog, the safety and health of the personnel on site is our top value. Red Dog is working closely with the federal Mine Safety and Health Administration (MSHA), as well as external experts, to monitor emission levels and take actions to reduce emissions and protect continued health and safety for workers, and keeping NANA informed.
  • This includes increased monitoring, raising fresh air intakes to higher elevation, and installing carbon air filters on air handling units in buildings, including the camp residence, to reduce concentrations in facilities.
  • We are also fitting all personnel with respirators, limiting the number of personnel on site, cooling reactive ore using water trucks to reduce the SO2 generating reaction, and reducing production from certain areas of the pit.
  • Monitoring is being conducted to confirm emission levels are within federal mine safety and health standards for SO2 exposures. Monitoring data and mitigation plans were reviewed with MSHA during recent inspections.  No citations related to SO2 were issued.
  • In the event SO2 levels exceed mine safety and health standards, emergency response personnel have protocols in place to move personnel from an area of higher concentration to safe muster areas of low concentration until the SO2 levels reduce sufficiently.
  • Out of an abundance of caution, we are reducing the number of personnel on site until key mitigation measures are in place, which we anticipate to be in the near future.
  • Personnel who are required to work onsite but have concern for potential health risks will be evaluated by Medics to determine whether they have elevated risks to exposure.
    • If the Medic finds the employee has an elevated risk from exposure, they will be put on Administrative Leave with Pay until the human health risk to employees is sufficiently resolved.
    • If the Medic finds the employee does not have an elevated risk of exposure, they have the option to be put on unpaid leave.
  • Red Dog adheres to the NIOSH exposure limits of 10 hours TWA (Time Weighted Average at 2ppm and 15 minutes STEL (Short Term Exposure Limit) at 5ppm. This is a stricter (more conservative) exposure limit than federal standards require.
  • Red Dog is working closely with NANA, external experts, and the federal Mine Safety and Health Administration (MSHA), to monitor emission levels and take actions to reduce emissions and ensure continued health and safety for workers.
  • An SO2 management team meets 4 times a week to develop and advance actions to mitigate SO2 generation in the mine and potential exposure to the workforce.  This includes a representative from NANA leadership.
  • Main Pit Dump #4 (MPD4) has been identified as a hot spot for SO2 emissions. To reduce emissions, a water truck is being used to cool MPD4. A pipe bench is also being developed to provide an increase of water to the area.
  • All air handlers have been moved to recirculation mode with only the minimal make up air being drawn to maintain positive pressure in the facilities.
  • Air intakes for the Personnel Accommodation Complex (PAC) are being relocated to reduce ingress of SO2 into the living accommodations.
  • Activated carbon filters have been installed in the air handler units in support of enhanced SO2 removal.
  • We are securing enhanced media filtration systems to install in the HVAC to scrub more SO2 out of the air intakes.
  • Numerous monitoring systems have been installed to support early detection of SO2, and we are procuring more.
  • We currently have nine (9) SO2 portable detectors stationed inside the PAC, Mill and Service Complex areas for continuous monitoring. In addition, the Safety and Health Department team is performing manual readings using handheld SO2 monitoring devices across fifteen (15) locations outside the PAC, Mill and Service complex areas on day and night shifts. Monitoring around the Mine, Airport and Construction Camp locations is also being performed by the Red Dog Fire Department.
  • To further transition from manual readings to real-time stationary monitors, fifteen (15) outdoor semi-stationary monitors, twenty-eight (28) indoor stationary monitors and twenty-six (26) HVAC intake duct monitors have been ordered with an expected delivery date in mid-January.
  • The Mine Safety and Health Administration (MSHA) has completed two separate inspections onsite to ensure compliance with federal regulations. 
  • Monitoring and MSHA inspections show that emission levels are within federal mine safety and health standards for SO2 exposures.
  • Additionally, the MSHA inspector reviewed Red Dog’s risk assessment for the mitigation plan to cool the material reacting in Main Pit Dump 4 (MPD4). The inspector was satisfied with the methodology and risk controls proposed to mitigate the hazards and protect the miners while performing mitigation activities.
  • In addition to monitoring and mitigation efforts, Red Dog is preparing for potential elevated SO2 events. 
  • Incident Management Team (IMT) Drills and Tabletop Exercises are being developed to refine our response to potential events.
  • Critical roles such as the Mill Control Room Operator and Powerhouse Operators have staged personal protective equipment (PPE).
  • Yes. The Food and Drug Administration (FDA) allows SO2 and other sulfites as food preservatives but requires mandatory labeling if food items contain greater than 10 parts per million (ppm). No readings in the food preparation and distribution areas have exceeded 10 ppm.
  • Out of an abundance of caution, NMS has engaged the Alaska Department of Environmental Conservation (ADEC) to determine whether any additional controls should be considered at this time.
  • Impacts of SO2 may be determined by several factors including the dose (amount) and method of contact (for example, by breathing, eating, drinking, or touching). Other considerations include your age, sex, diet, family history, lifestyle, and health.
  • Under low concentrations (<5ppm), inhaling SO2 can cause irritation to the nose, eyes, throat, and lungs. Those with preexisting respiratory conditions may experience symptoms at concentrations as low as 0.25ppm.
  • Unprotected exposure to high concentrations of SO2 can cause permanent damage to the lungs.
  • Symptoms can be worsened by preexisting health conditions like asthma.
  • Health effects can be prevented or mitigated with respiratory protection equipment with appropriate cartridges.
  • Monitoring and MSHA inspections show that emission levels are within federal mine safety and health standards for SO2 exposures.

For any questions or concerns, please contact us at rd-ca@teck.com or 907-754-5168