With one year of research under their collective belts, researchers have removed some of the barriers to using bio-based carbon in the electric arc steelmaking process. The research is being conducted at the University of Minnesota's Natural Resources Research Institute (NRRI) as a $4.5M research project funded by a $2.9M grant from the U.S. Department of Energy with a match of $1.6M from NRRI internal funds with industry assistance.
A recent trip by research leaders to the European Biocarbon Summit revealed that steelmakers are ready and waiting for a biocarbon product that can replace fossil coal in the steel-making process. Steel production accounts for about eight percent of global carbon emissions.
“Every major steel producer we talked to wants to lower the carbon impact of their product,” said Eric Singsaas, NRRI Materials and Bioeconomy Research Group Leader. “In some markets, it’s driven by regulation, in others, it’s customer-driven.”
And while planet Earth has been very effective at turning biomass into coal over millions of years under high pressure and heat, replicating that above ground in real time offered some interesting challenges.
Steel 101
Steel is basically an alloy of carbon and iron. It is a critical material for national security and economic prosperity. In the electric arc furnace steelmaking process, pulverized fossil coal is injected into the molten slag near the end of the melting process. It produces a foaming reaction that provides insulation to the molten steel, holding in heat; helps to remove impurities, like sulfur; and protects the slag lining in the refractory.
The limitation of pyrolysis-processed biomass (biocarbon) is that it’s not a dense material. And the injection process uses pneumatic pressure to get the material through the slag. The carbon source has to be robust enough to survive transfer into the furnace.
In addition to conveyance, biocarbon behavior in the slag is not ideal, according to Matt Young, NRRI biomass research engineer.
“On its own, the foaming reaction of biocarbon is too violent. It raises quickly – like mints in a cola – and dissipates too quickly,” he explained. “Foaming with injected coal raises the slag up a few inches and holds that foam reaction. The time and height, the kinetics, that’s what we’re trying to engineer.”
The challenge for NRRI researchers is to densify porous, low density biocarbon to work as well as fossil coal. By experimenting with different performance modifiers and testing various binders, they engineered a biocarbon that mimics this coal-like reaction at the bench and pilot scale. The pelletized biocarbon material was successfully tested in intermediate scale-up trials of 25 kilograms at a steel recycling plant electric arc furnace.
Next Up: Charge Carbon
The next target for the research is developing “charge carbon” which is added to the scrap steel and metallic iron at the beginning of the melting process to provide energy and act as a reducing agent.
The goal is to successfully demonstrate biocarbon in these steelmaking steps at the commercial scale at a full-scale electric arc furnace steel producer in 2026.
“While the global steel industry knows they need to use biocarbon, they don’t know how to use biocarbon. So that’s the focus of this Department of Energy grant,” said Singsaas. “Over the past decade, we’ve become leaders in biocarbon densification, though this is a much more complex, more finessed, product than we’ve tried in the past.”
NRRI’s integrated research teams are uniquely qualified to develop bio-based industrial solutions. Twelve scientists on the Materials & Bioeconomy team work with 10 engineers and technicians on the Minerals & Metallurgy team. And NRRI’s Forests & Lands research team can provide critical analysis of the U.S. wood basket to inform biomass availability.
A life cycle analysis is also part of the project to understand the environmental impacts of biocarbon in steelmaking, as well as a techno-economic analysis to inform industry cost impacts.
Seeking Global Partners
The researchers are actively seeking research partnerships across the globe to accelerate these innovations; steel companies, biomass providers, biocarbon producers or other interested parties.
“NRRI is really at the forefront of developing industrial metallurgical carbon because of the broad expertise across many disciplines that intersect here,” said Brett Spigarelli, NRRI lead metallurgical engineer. “Decades of past research is paving the way for this critically important innovation in steelmaking. NRRI is ready to lead.”
The Natural Resources Research Institute is a state-chartered, University of Minnesota System research unit with three sites in Northern Minnesota, fulfilling a mission to deliver integrated research solutions that value our resources, environment and economy for a sustainable and resilient future.
*Note: This article was also published in Biomass Magazine.