U.S. Steel announced Monday it secured permission from the Allegheny County Health Department to build a $100 million slag recycler at the Edgar Thomson Works.
A critical air quality permit arrived Friday, U.S. Steel said, allowing the company to start site preparation at the facility straddling Braddock and North Braddock. Construction is slated to begin this summer and take about a year.
U.S. Steel revealed plans in September to modernize how it processes slag, a byproduct of smelting iron ore, at the Edgar Thomson Works.
The $100 million price tag is just a fraction of the $2.4 billion Nippon Steel committed to upgrades at the Mon Valley Works when it purchased U.S. Steel in June.
The Japanese steelmaker also plans to shut down the hot strip mill at the Irvin Works in West Mifflin and replace it with a new one at Edgar Thomson.
The slag recycler is the first of these projects to earn regulatory approval. All sources of air pollution in Allegheny County must obtain permits to operate, install new units or modify existing equipment.
Allegheny County Health Department did not immediately respond to a request for comment.
Slag is currently diverted into one of two open pits and cooled with water before being sent to a landfill, where it may leach contaminants into the soil.
The new process takes the slag and turns it into a marketable materials. Cement manufacturers are major buyers of slag, using it to make their product easier to work with and more durable.
U.S. Steel also claims the fully enclosed system will reduce emissions of sulfur dioxide and hydrogen sulfide — both harmful to human health — from slag processing by as much as 50%.