U.S. Steel’s Big River complex in Arkansas is getting a nearly $2 billion advanced ironmaking facility, the Pittsburgh-based company announced Wednesday.

The plant will use the direct reduction method to purify iron ore from U.S. Steel’s Minnesota mines. Iron is traditionally smelted in blast furnaces fueled by coke. This newer technology involves passing hot gases, in this case methane, over the ore to remove oxygen, leaving behind a porous “sponge iron.”

The iron will then be fed into Big River’s four electric arc furnaces to produce steel. U.S. Steel says the operation will be the first in the country to move direct reduced iron into furnaces while it’s still at high temperatures.

Construction is expected to start right away and take about 2½ years.

Big River is the “natural home” for the direct reduced iron plant, said Amanda Malkowski, a spokeswoman for U.S. Steel, because it contains a majority of the company’s electric arc furnaces.

U.S. Steel’s Mon Valley Works in Southwestern Pennsylvania and Gary Works in Indiana strictly use blast furnaces, producing nearly 6 million tons a year of specialized steel for automobiles and other products that can’t be made with electric arc furnaces, according to Malkowski.

United Steelworkers represents employees at the Mon Valley Works and Gary Works, but not at Big River, where no union has taken hold. Bernie Hall, the union’s Pennsylvania director, expressed disapproval of the Big River plans.

“We’re disappointed that (U.S. Steel) continues to prioritize its Big River complex, allocating nearly $2 billion that could be invested in ensuring its existing facilities continue producing world-class steel,” he said in a statement. “Moving forward, we urge management to demonstrate this same kind of commitment to the long-term future of these operations and the surrounding communities that have supported the company for 125 years.”

The direct reduced iron facility is a piece of the $11 billion in investments that Nippon Steel, the Japanese steelmaker that bought U.S. Steel last year, plans for its new holdings by 2029. This money is allowing the Big River investment to happen “years sooner than would have otherwise been possible,” U.S. Steel CEO David Burritt said in a statement.

Responding to Hall’s criticism, Malkowski noted U.S. Steel has announced two major projects at the Mon Valley Works “that will protect and create jobs while producing higher-quality steel more efficiently.”

Nippon is sinking $100 million into a new slag recycler at the Edgar Thomson Works, the 151-year-old steel plant in Braddock and North Braddock. The Allegheny County Health Department granted a critical air quality permit for the project in February.

The plant is also slated to receive a new hot strip mill that will cost at least $1 billion to build.

A total of $2.4 billion will go toward the Mon Valley Works. U.S. Steel has yet to announce how the remaining Mon Valley Works money will be spent.