Iron ore mined in Minnesota could have an unexpected future beyond steelmaking.
Scientists have discovered that relatively low-purity ore from the state’s Iron Range can be turned directly into semiconductor-quality pyrite, potentially providing a cheaper and more sustainable material for electronics, solar panels and other technologies.
Researchers at the University of Minnesota Twin Cities made the discovery while studying pyrite, an iron sulfide mineral commonly known as “fool’s gold.”
Their findings were published in Physical Review Applied.
Minnesota is a major center of US iron production, supplying about 75% of the nation’s iron ore and generating billions of dollars in annual economic activity. Much of that production comes from the Mesabi Iron Range and its enormous deposits of taconite, a relatively low-grade iron ore.
Normally, low purity would seem to make such material a poor choice for producing semiconductors. Semiconductor performance can be extremely sensitive to tiny amounts of contamination and defects, which is why manufacturers often rely on highly purified materials.
Pyrite, however, appears to behave differently.
The mineral has attracted interest as a semiconductor because it absorbs light extremely well. It is also made from iron and sulfur, two abundant and relatively inexpensive elements that are considered less toxic than some materials used in conventional semiconductor technologies.
Researchers had generally assumed that making high-quality semiconducting pyrite would require highly purified starting materials. But the Minnesota team questioned that assumption after earlier experiments suggested pyrite was unusually resistant to impurities.
To test the idea, the researchers collected three types of iron ore directly from Minnesota’s Iron Range and attempted to convert them into semiconductor-quality pyrite using relatively simple processing techniques.
To their surprise, it worked.
The low-purity ores could be transformed into high-quality semiconducting pyrite without requiring additional purification steps. Even more encouragingly, the best-performing material was Direct Reduced Grade Taconite, one of the more commonly available grades in Minnesota.
The finding suggests that some of the costly purification normally associated with semiconductor production might not be necessary when making pyrite from these ores.
That could potentially reduce both the cost and environmental impact of producing the material while creating new uses for an abundant natural resource.
The researchers believe semiconductor-quality pyrite could eventually have applications across several industries. Possible uses include solar cells, batteries, electronic devices and technologies for purifying water.
The discovery could also create new economic opportunities for iron-producing regions. Instead of supplying ore mainly for traditional industries such as steelmaking, mines could potentially provide raw materials for clean energy and advanced electronics.
There is still considerable work ahead before Minnesota iron ore begins appearing in commercial electronic devices.
The researchers now plan to test a wider range of iron ores to determine which grades work best. They also want to move from producing larger pyrite crystals toward manufacturing thin films, which are much more useful for practical semiconductor devices.
If those efforts succeed, a resource that has supported Minnesota’s steel industry for generations could find an entirely new role—helping build the electronics and clean-energy technologies of the future.
Source: University of Minnesota.
