Jerry Lien with the prototype Ferrous Wheel in 1992.
Natural ore mining (the precursor to today’s taconite mining) has long ended on Minnesota’s Iron Range, but the tailings piles — waste rock leftover from the process — remains. Since it’s already blasted, it makes sense to pull any remaining iron ore from it. All that’s needed is an efficient way to extract it.
Alan Fritz of Grand Rapids had an idea, and with some assistance from NRRI, a business partner, and a bit of serendipity, it has grown beyond the initial idea to a new Iron Range industry.
As a mine superintendent at the now-defunct J & L mine, Fritz witnessed poor attempts at reclaiming ore from their two tailings plants. Then he heard that MIT (Massachusetts Institute of Technology) found a way to recover iron oxides from previously mined taconite. But when he saw the MIT equipment, he wasn’t impressed.
"So I started fooling around in my garage with different tailings from around the Iron Range. And I found out, yes, I could do this with rather high intensity magnets," Fritz said.
This led to an invention he called the Ferrous Wheel which proved to be successful at extracting good iron ore from waste tailings piles. NRRI Technician Jerry Lien helped to machine the parts and they built a pilot-scale model from scratch at NRRI’s Coleraine Minerals Lab.
Basically, the Ferrous Wheel used the magnets and a screen matrix to separate the good ore from the worthless rock.
"Al made some models of the process and we just made it bigger," said Lien of the invention.
With only 20-30 percent weight recovery, however, "it wasn’t the greatest in the world," Fritz admitted.
But that early research eventually led to a new Minnesota Iron Range business, Magnetation, Inc., with business partner Larry Lehtinen as chairman. Lehtinen became interested in the idea of recovering ore from natural ore tailings. In the end, however, the Ferrous Wheel proved to be difficult to operate and maintain.
"The Ferrous Wheel got us started, but we needed to reinvent," said Lehtinen. "We learned things from it, but now we have a new process, the Rev3 Separator, with very high uptime and a very efficient process."
Lehtinen’s engineers took out their pencils and reconfigured the process so that the materials flow with the natural pull of gravity on a turntable style, instead of upright like the Ferrous Wheel, among other innovative changes.
In early 2011 Cargill signed an agreement to jointly develop the technology with Magnetation and market the iron concentrate internationally. Cargill’s investment enabled Magnetation to boost production from 150,000 to 450,000 tons per year on two Rev3 Separators.
"NRRI offered support and Jerry Lien did a lot of work with me on the Ferrous Wheel," said Fritz of starting the project.
"Now we’re growing rapidly and our technology continues to improve, but it all started with Al’s early work on the original Ferrous Wheel," said Lehtinen. "If it wasn’t for his persistence we wouldn’t be where we are today."