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The world needs the metals of northeastern Minnesota

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Jim Miller
Jim Miller is an associate professor of geology at the University of Minnesota-Duluth.
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By Jim Miller

Mother Nature has endowed northern Minnesota with not only pristine lakes and forests, but also with incredible mineral resources. While mining of the iron ores of the Mesabi Range has supported the economy of northern Minnesota and built the steel infrastructure of much of our nation for over 125 years, a new type of mineral resource -- rich in copper, nickel and precious metals -- is being considered for development at the east end of the Mesabi Range.

With the public release of the draft environmental impact statement (EIS) for the PolyMet project late last year, an intense debate has ensued about the wisdom of mining this type of ore deposit. 

Unfortunately, the debate has largely settled on what I see as a false choice -- jobs or the environment (see the MPRNewsQ Today's Question for March 10). Responsible stewardship requires an honest and informed discussion about how, where and when to develop our resources for current and future generations. 

I would argue that when all facts are considered, responsible and forward-thinking stewardship compels us to develop these metal resources with the highest environmental standards and to do so now. As a geologist, I will leave discussion of the potential economic impact of this development to the economists and the potential environmental pitfalls to the environmental engineers.  Instead, I will focus largely on the geology of this special metallic resource.

Trace amounts of metals occur in every type of earth material, but their occurrence near the Earth's surface where we can get at them is rare, especially in concentrations sufficient to economically extract and refine. 

The deposits of copper, nickel and precious metals situated near Babbitt and Hoyt Lakes occur along the margin of an enormous igneous mass called the Duluth Complex, which underlies most of northeastern Minnesota. 

These ore deposits formed over a billion years ago, when metal-bearing magmas came into contact with sulfur-bearing rocks a couple of miles below the surface. Subsequent erosion has now exposed these deposits along a 40-kilometer band that runs adjacent to the eastern end of the Mesabi Range. What these geologic processes have produced is one of the largest undeveloped metal deposits on Earth, with significant amounts of copper, nickel and precious metals (mostly palladium, platinum and gold). 

Copper, nickel and palladium are metals that are fundamental to living in a modern world and will be even more important as we move into a green economy. All these metals are key components in hybrid cars and wind turbines, for example. Hybrid cars contain about 75 pounds of copper, compared to 40-50 pounds in a standard automobile. All-electric cars will use even more. 

Like other earth resources, all these metals are non-renewable (we can't grow more).  But unlike petroleum, most base and precious metals are largely recyclable and reusable. According to the U.S. Geological Survey, the United States consumed over 3 million tons of copper in 2008, of which 31 percent came from recycled scrap and 33 percent from imports.  Most nickel is used in stainless steel and metal alloys to make them strong and corrosion-resistant. The United States consumed over 200,000 tons of nickel in 2008, all of it from imported or recycled sources.  Palladium, the main precious metal in Duluth Complex ores, is primarily used in catalytic converters to clean pollutants from car exhaust. 

Today, about two-thirds of the world's palladium comes from the Noril'sk deposit in Russia.  Ironically, more than half of the sulfur dioxide pollution in the northern hemisphere in the 1990s was traced to Soviet-era smelters that liberated this "environmental metal" from its sulfur host by "roasting" sulfide ores. Thankfully, new metal sulfide mines are adopting recently developed hydrometallurgical technologies to separate metals from sulfur.  Rather than allowing the sulfur to escape into the atmosphere as sulfur dioxide or into the ground as sulfuric acid, this new process oxidizes the sulfur with lime to create calcium sulfate. This is a material that literally surrounds us.  Also known by its mineral name -- gypsum -- it is the main component of wall board.

The mining of these metals is commonly referred to as "sulfide mining," though the material being sought is not the sulfur, but rather the metals that are bound to sulfur in sulfide minerals. One of the little mentioned realities of this debate is that sulfur is the reason these metal deposits even exist.  Sulfur is the main concentrator of most metals on earth. To get access to these necessary metals, we have little choice but to mine sulfide ore deposits. The challenge is to figure out how to do this in ways that minimize the impact on our environment now and into the future.

The anti-mining message is simple and easy -- Be Afraid, Be Very Afraid.  It offers us another false choice -- prevent mining and save our precious wilderness, or allow mining and almost assuredly guarantee its destruction. The detractors' main argument against mining relies on pointing out the many mistakes and irresponsible behavior made by mining companies throughout the 20th century, which most companies now readily admit to and are working diligently to rectify.

The mining companies have no one but themselves to blame for the negative perception that most people have of them. However, this backward-looking approach alone doesn't help us in fully assessing the risks and benefits of the current situation. I would pose a few questions that we should also consider if we are to act as responsible stewards of ALL of the precious resources with which our state has been endowed:

Is it responsible (and moral) stewardship to rely on the rest of the world to supply our resource needs, especially from countries with abysmal environmental standards, especially when we are one of the world's principal consumers, and especially when we are sitting on one of the largest metal deposits on earth?

Is it responsible stewardship to delay the inevitable mining of this enormous resource while the infrastructure and workforce for mining exists today in northern Minnesota? Because someday this world class ore deposit will be mined; that's guaranteed. Doesn't it make more sense to mine the copper, nickel and precious metals now, while the 100-year-old taconite industry next door continues its operations for another half century?    

Is it responsible stewardship to make the false claim that environmental devastation is inevitable? It will happen only if all the stakeholders in this endeavor -- the mining companies, the state and federal regulators and the citizens of Minnesota -- allow it to. We are all obligated to see that this resource is developed responsibly and with the highest environmental standards. 

Indeed, we have the opportunity here to show the rest of the world how it's done.  And when it is done, we can reclaim and restore this area to its natural state and pass it on to future generations as a legacy of our responsible stewardship. 

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Jim Miller is an associate professor of geology at the University of Minnesota-Duluth.  He has studied the geology and mineral deposits of the Duluth Complex for over 30 years.