An Electrifying New Ironmaking Method Could Slash Carbon Emissions
taylorvich writes:
By extracting metallic iron without producing carbon dioxide, the new process could even be carbon negative, at least for part of the world's iron production
Making iron, the main ingredient of steel, takes a toll on Earth's delicate atmosphere, producing 8% of all global greenhouse gas emissions. Now, a team of chemists has come up with a way to make the business much more eco-friendly. By using electricity to convert iron ore and salt water into metallic iron and other industrially useful chemicals, researchers report today in Joule that their approach is cost effective, works well with electricity provided by wind and solar farms, and could even be carbon negative, consuming more carbon dioxide (CO2) than it produces.
"It's a very clever approach," says Karthish Manthiram, a chemical engineer at the California Institute of Technology who was not involved with the study. He notes that the process has other advantages, including working at a low temperature, and being amenable to working with intermittent renewable electricity. "It checks all the boxes."
Iron is one of the most abundant elements on Earth, but in its natural state is bound to oxygen in the various minerals that make up iron ore. To extract metallic iron from this ore, workers typically mix it with a high-carbon form of coal called coke and heat the combination to about 1500C in a blast furnace. At that temperature, the carbon atoms strip the oxygen atoms from the iron, producing CO2 that wafts into the atmosphere and leaves behind the molten metal. Steelmakers then combine this iron with a small amount of carbon and other trace metals to forge steel.
Although this way to make iron and steel is cheap and time tested, it produces significant amounts of CO2. The world mines 2.5 billion tons of iron every year, and reducing it to iron emits as much CO2 as the tailpipes of all passenger vehicles combined. So, scientists are looking for economically viable ways to produce metallic iron that don't generate greenhouse gases.
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