About the Event
Aggregate produced from Minnesota taconite products - including low-grade ore, waste rock, and tailings - has outstanding microwave absorption properties. The researchers have proposed several applications in which a mobile microwave generator could be deployed to take advantage of these properties:
- Permanent repair of potholes under winter conditions. Heat generated by microwave absorption could produce the equivalent of a hot-mix repair in situ. It may also improve the speed and durability of cold-bonded repairs.
- Chemical-free deicing of roads, bridge decks, airport runways, etc. By concentrating the generated heat at the ice-roadway interface, microwaves have the potential to be the most energy-efficient of all proposed non-chemical deicing techniques.
- Annealing, recompaction, and sealing of joints in asphalt roadways.
Tests conducted to date on typical magnetite-rich taconite materials have shown microwave absorption to be directly proportional to magnetite content. In the next phase, the researchers plan to extend the testing to waste rock horizons that contain other microwave-absorbing minerals such as hematite and graphite. As funding becomes available, the team intends to mount a microwave generator on mobile equipment and take it into the field for realistic demonstration and testing.
David M. Hopstock, Ph.D, Independent Consultant, Roseville, MN
Lawrence M. Zanko, Research Fellow, Natural Resources Research Institute (NRRI), University of Minnesota Duluth