Iron (Fe) is the fourth most common element found in the Earth’s crust. There are several kinds of iron, which are distinguished by their composition and use. The main categories are pig irons, which form the basic foundation for the manufacture of steel, and cast irons, which are are used for the production of semi-manufactured products such as pipes, machines, various castings, and cookware. Many iron alloys are created with differing properties suited for these various applications, so it is important to be able to accurately analyze these materials to confirm that their chemical specifications are correct for their purpose. Elemental analysis using a handheld x-ray fluorescence (XRF) analyzer is an excellent choice for this type of testing.
With so many applications, more sources of iron ore are always needed to keep up with global demand. The KU LEUVEN website reports that an international team of researchers from institutions including KU Leuven, Leibniz University Hannover, and ULiège may have discovered new iron ore deposits for mining by studying magma.
The article explains that while most iron ore deposits are found in sedimentary rocks, others are mined in volcanic complexes such as El Laco in Chile and Kiruna in Sweden. These iron ore deposits, called Kiruna-type deposits, account for about 10% of the global production of iron. The researchers have discovered that these iron ore deposits are formed when magma splits into two separate liquids. Author Olivier Namur from the Department of Earth and Environmental Sciences at KU Leuven, Belgium, explains.
“We wanted to reproduce the conditions found in magma chambers, where molten rock accumulates when it cannot rise to the surface of the Earth. This is also where the iron ore deposits beneath volcanoes are formed, so reproducing the temperature and pressure of the magma chambers seemed well worth examining.”
“That’s why we produced a mixture of iron-rich ore samples and typical lavas surrounding Kiruna-type deposits. This created a bulk magma composition that we believe exists in the deep magma chamber beneath volcanoes. We placed the mixture in a furnace and raised the temperature to 1,000-1,040°C. We also increased the pressure to about 1000 times the atmospheric pressure of Earth. These are the conditions of a magma chamber.”
“We were surprised to find that, under these conditions, the magma split into two separate liquids. This process is known as immiscibility. Just think of what happens when oil spills into the ocean: the water becomes streaked with oil because oil and water cannot mix.”
“One of these liquids contained a lot of silica, whereas the other was extremely rich in iron — up to 40% — and phosphorus. When this iron-rich liquid starts to cool down, you get iron-phosphorus Kiruna-type ore deposits.”
“This is the first evidence that immiscibility is key to the formation of iron ore deposits such as the ones mined in El Laco. If we’re right, these findings may help to find new iron ore deposits.”
The findings were presented in Nature Communications.
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