Direct Hydrogen Reduction of Iron Ore Concentrate and Net-shaped Fabrication of Linear Cellular Alloy Steels

(Funded by ARPA-E; Faculty: Kacher, Thadhani, Speyer, & Goldman)

We are working on a novel technology for producing net-shaped engineered lattice and cellular structures of alloy steels by solid-state H2-based direct reduction of extruded structures made from fine taconite ore concentrate-containing pastes. Mined taconite acquired from the MinTech mine is refined to remove gangue minerals and obtain finely ground sinter-grade hematite and magnetite powders. The fine iron oxide powder combined with other oxide powders (based on desired alloy composition) and polymeric binder are then extruded using a commercial extruder, or additive manufacturing (AM), into desired lattice/cellular structures. The extruded structures reduced in a flowing atmosphere containing hydrogen are solid-state sintered to obtain the final net-shaped alloy steel products.

Direct hydrogen reduction of the extruded green bodies of the hematite/magnetite containing pastes will allow zero process emissions fabrication of lightweight net-shaped alloy steel products with less total energy consumption due to lower process temperature requirements and avoidance of subtractive metal working processes. The direct ore-to-steelmaking process will also enable use of domestically available fine taconite tailings often rejected in traditional iron and steelmaking processes due to their fine size and chemistry. We are collaborating with Atlanta-based Applied Ceramics Inc., a leading manufacturer of ceramic honeycomb structures, to leverage its capabilities and expertise, and demonstrate direct oxide to steel making and net-shaped fabrication.

The project is an “out-of-the-box” concept providing a pathway for direct “ore to steelmaking” utilizing fine rejected taconite mine tailings and hydrogen-based reduction process with zero emissions, to produce net-shaped lightweight cellular solid products of advanced steels for use in automotive, aerospace, construction, and defense applications.