Direct reduced iron is a BIG deal.
And not just because it’s about three times higher value than taconite pellets. Also, not just because it’s the feedstock for modern and more efficient electric arc furnace steelmaking.
It is those things. But direct reduced iron – commonly called DRI – is a big deal because the direct reducing shaft furnaces are huge. In the U.S., Cleveland Cliffs’ Toledo DRI furnace reactor is more than 40 stories high. Nucor Steel’s DRI plant in Texas is some-30 stories high. Workers use elevators to get to the top.
So it’s risky and expensive – in increments of billions of dollars – when changes need to be made in such a big production process. And changes are coming. NRRI has a team of metallurgical engineers leading cutting-edge research to improve DRI pellet productivity and energy efficiency. And to do this, the team has designed, and is now constructing, a first-of-its-kind, experimental-scale DRI furnace to precisely simulate process improvements and reduce risk.
This research apparatus will provide timely and affordable experimental capability to provide basic data for computer models to leverage artificial intelligence and machine learning.
Filling a Need
In 2016, NRRI met with government and industry leaders to discuss the future of iron and steelmaking and what it means to Minnesota.
“We were really looking for any missing links in critical research capabilities to support the transition from the blast furnace to electric arc furnace steelmaking and alternative steel making technologies,” said Kevin Kangas, NRRI Director of Technical Operations and DRI Simulator project manager.
With $250,000 in seed funding from the Minnesota Legislature, NRRI began working on conceptual design in collaboration with several steel companies and major technology providers. NRRI completed detailed engineering in 2019 and was set to begin equipment procurement in early 2020 when the COVID19 pandemic slowed the project down. NRRI used that time to continue meeting remotely with industry and technology providers to refine and improve the original design. In 2022, the project was infused and reinvigorated with $2.1 million in federal funding from the US Department of Energy and $1.6 million in matching funds from NRRI. It is currently under construction at Ajax Tocco Magnethermic’s Pillar Induction plant in Brookfield, WI and is expected to be commissioned at NRRI Coleraine Labs later this year.
Minnesota provides about 80 percent of the iron mined in the United States. The DRI Simulator and the related research to improve the chemistry and efficiency of the DRI process positions Minnesota – and its important iron ore deposits – as a leader in iron ore research and sustainable iron and steel technologies.
Improving DRI
Producing direct reduced iron from iron ore (oxidized iron) requires a reduction reaction to essentially remove the oxygen from the iron oxide ore, producing metallic, or direct reduced) iron. Today, this reduction is carried out using carbon (coal or natural gas) as the reductant, producing carbon dioxide as a waste product. Looking forward, hydrogen may be used as a reductant, resulting in the same reaction, but with water as the waste product. Ultimately, the industry seeks means to onboard hydrogen as a reductant in a transition from natural gas to hydrogen DRI.
NRRI will be able to simulate the entire DRI shaft furnace from top to bottom in this 6-foot-tall unit. The researchers will experiment with feedstock pellet chemistry, pellet coatings to prevent sticking, temperature profiles in three distinct heating zones, pressure from 14.5 pounds per square inch (psi) to 116 psi, and a variety of reducing gas mixtures, including varying levels of hydrogen.
“NRRI’s DRI Simulator fills a critical gap in applied research for industry,” explained Brett Spigarelli, metallurgical engineer and lead principal investigator on the project. “There’s nothing like it in the world.”
Because the DRI Simulator is unique, it was complex to design and difficult to procure the components to build it. The diverse team of engineers and scientists selected domestic suppliers for most of the reactor components and is working with several local engineering firms, industry, and technology providers to bring it all together. Key engineering and equipment suppliers include: Krech Ojard and Associates, WSF Technologies, Ajax Tocco Magnethermic-Pillar, Gradient Technologies, Hallberg Engineering, Architectural Advantage, Marshal Nelson and Associates.
“The maximum temperature that we can achieve in the simulator is approximately 2012 degrees F, which is about 212 degrees greater than what industry can currently do at the commercial scale,” said Kangas. “DRI shaft furnace operators are always pushing the temperature envelope to achieve productivity and efficiency gains while operating just below the temperature where the pellets start to soften and stick together.”
This tool allows us to anticipate where industry wants to go, explore new operating conditions for increased efficiency and productivity.
Over time, the DRI Simulator will help pave the way for production of a higher quality iron product from lower quality, oxidized Minnesota iron ore.
What’s Next
NRRI’s DRI Simulator project team is in the finishing stages of procurement and expects to begin on-site construction this summer with commissioning before the end of the year. NRRI’s initial research and development will validate the results from the Simulator compared to commercial scale operations. When that step is completed, NRRI will begin doing applied research funded by federal grants and private industry.
PHOTO TOP: NRRI's Jeff Kinkel, Kevin Kangas (left) and Brett Spigarelli (far right) stand by the newly built DRI Simulator with Josh Welsh (second right) of Ajax Tocco Magnethermic, the equipment manufacturer.