Boston Metal, a spin off from MIT, has developed a technique for making high-strength steel alloy using an electrolytic cell rather than a blast furnace. The process does not release the huge quantities of carbon dioxide produced in the traditional process.
In the traditional process, iron oxide is placed into a blast furnace with coke, which is nearly pure carbon made by heating coal in the absence of air. At high temperatures, the coke burns producing carbon monoxide. The carbon monoxide reacts with the iron ore producing carbon dioxide and “pig iron”.
Worldwide, this process releases about 1.7 gigatons of carbon dioxide into the atmosphere annually, adding up to around 5% percent of global carbon dioxide emissions.
The new electrolytic cell process uses electricity, rather than carbon, to process the iron ore and releases no carbon dioxide.
The electrolytic cell is a squat metal cylinder, with a chimney-like tube emerging from the top and an oval opening in front.
The “chimney” is actually an anode. A thin layer of metal along the bottom forms a cathode. These positive and negative electrodes together act like a sort of pump, pushing electrons through the electrolyte in the chamber, a mix of metallic minerals and other oxides.
As the electric current melts the metallic electrolyte, oxygen freed from the iron bubbles up to the top, and the resulting metal accumulates at the bottom. Once operators “tap,” or crack through, a lining through the hole in the front, molten metal pours forth.
Boston Metal’s three-year plan is to build a demonstration facility to produce ferroalloys. The company will also start designing and engineering a cell for producing steel at an industrial scale which they expect to achieve within seven years.