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Miami | Sulfur Dioxide (SO2) Nonattainment Area

County Affected:

Parts of Gila County  | View on a Map >

Nonattainment Area Designation Date:

Aug. 5, 2013
(78 FR 47191)

Pollutant of Concern:

Sulfur Dioxide (2010 standard)


The concentration of SO2 in the air in Miami has been above federal standards for several years.  ADEQ submitted a nonattainment State Implementation Plan (SIP) to the EPA in March 2017. Freeport McMoRan made numerous improvements to the Miami Operations in 2017 as a part of $250 million expansion project to substantially reduce SO2 emissions. 

Some of the controls implemented at the smelter to reduce SO2 emissions include:• Capture of fugitive emissions from converters and anode furnaces rooflines, and routing of these to new caustic aisle scrubber

• Routing of emissions from the anode furnace baghouse to aisle scrubber
• Upgrade of the vent fume scrubber, and acid plant tail gas scrubber to caustic use.
• Improvements in capture of fugitive emissions from IsaSmelt furnace feed port and matte taping
• Stringent SO2 emission limits established to meet federal standards

Source of Pollutant:

  • Smelting Metal

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