The Iron Range mining firm United Taconite has agreed to pay more than $500,000 to settle a federal lawsuit over air pollution from its processing plant in Forbes in northern Minnesota.

The company was accused by federal prosecutors of emitting particulate matter into the air from early 2010 and into 2016. United agreed to pay a $50,000 cash penalty and $489,000 to replace an existing "wet scrubber" control system for one of its crushers with a more efficient dry fabric control system.

The nature of the particulate emissions isn't detailed in the documents, which only indicate they resulted from burning coal and gas, and handling taconite pellets. But according to the U.S. Environmental Protection Agency (EPA), particulates from taconite plants include hazardous metal compounds such as lead and mercury.

The documents also don't specify whether the pollution caused any health risks to residents of the area.

United Taconite's emissions exceeded the limits allowed under its air-quality permit at least 13 times from January 2012 through June 2015, according to the lawsuit and the consent decree, filed by the U.S. Department of Justice on behalf of the EPA.

The complaint also accused the company of misusing pollution-control equipment for at least 700 days from January 2010 through December 2016. That equipment is used to limit emissions from machinery such as ore crushers.

Both documents were filed Thursday in federal court in Minnesota. The consent decree will be open for public comment for 30 days.

United Taconite is owned by Cleveland-Cliffs Inc., an Ohio-based iron and steel producer that generated over $1.1 billion in income in 2018.

The company called the settlement a "reasonable outcome."

"These are old alleged violations dating back more than five years that were largely administrative in nature and related to past record keeping for our dust collection equipment and pellet furnace, and they've been corrected," said Cleveland-Cliffs spokeswoman Patricia Persico.

The company has bought the new equipment but hasn't installed it yet, Persico said.

Such settlements are a common tool for enforcing federal environment regulations across the country, although they are not always speedy.

The EPA officially notified United Taconite of the Clean Air Act violations in February 2014.

Eric Schaeffer, a former director of the EPA's Office of Civil Enforcement who now directs the nonprofit Environmental Integrity Project, said the settlement is inadequate given the serious nature of the violations.

"It reads like a bad joke" Schaeffer said.

"On its face, this one lets polluters know it's a lot cheaper to save money by running your plants without controls for years at a time," Schaeffer said. "Because the worst thing that can happen is you'll be told to try harder, and pay a penalty that's a fraction of the amount you saved through noncompliance."

The new air pollution settlement is separate from an enforcement action Minnesota pollution regulators took against United Taconite involving the same facility in 2016, in which the company agreed to pay the state $50,000 for fugitive dust emissions from 2013 to 2015. There were no health effects from those dust emissions, state officials said Friday.

Brandon Stahl • 612-673-4626 brandon.stahl@startribune.com Jennifer Bjorhus • 612-673-4683 jennifer.bjorhus@startribune.com