Steel Without Coal: This is Big

Steelmaking was the defining technology of the Industrial Revolution. We may be witnessing the beginning of a new, carbon free era.

Episode Summary:

Steelmaking is possibly the most important single technical innovation of the last thousand years. Almost all modern technology can trace its roots back to the unique properties of iron with carefully controlled amounts of carbon. Steel allowed everyone from James Watt to the village blacksmith alter the hardness of the material at will, creating the ability to cut and shape steel into everything from bridges to submarines. But it generates a lot of CO2. A modest industrial truck from Volvo Group is the prototype for what may be entirely new, carbon free way of making this essential material.

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Transcript of this week’s show:

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This modest little dump wagon, designed for use in quarries and open pit mines, is hardly an impressive sight. It’s made by Sweden’s Volvo Group and it’s not particularly impressive even by the standards of the company’s other industrial vehicles. But I expect that this little wagon will be behind velvet ropes in a museum someday. Why? Not because of what it is, but because of the steel from which it’s made. The steel was not made using metallurgical coal, but hydrogen, and represents the first commercial use of steel made with this technology.

This is a very big deal. Steel has been made for about 4000 years, but in the manufacturing sense as we know it, it really began in the 1850s when Henry Bessemer invented a process for producing it from pig iron in large quantities, quantities large enough and in a process efficient enough that steel could cost-effectively replace wood for major structures such as bridges. Now I won’t get into the metallurgy of steelmaking, but it begins with pig iron, and it make pig iron is necessary to start with iron ore.

The problem with iron ore is that in its natural form, it exists as oxides. We’ve all seen iron oxides and their characteristic red colour as rust. But in the form of iron ore, the challenge is to get the oxygen out, and it’s bound tightly to every atom of iron. The commercial processes uses blast furnaces, which take advantage of really useful property of metallurgical coal. Reacted with air, the coal, in the form of coke, produces carbon monoxide, which when reacted with iron oxides, produces relatively pure iron, and lots of CO2. Fluxes such as limestone are added to purify the iron, with chemical reactions that also produce CO2.

In the Bessemer process, that pig iron, which contains far too carbon to make steel, is heated and reacted with a blast of air, today oxygen, which reacts with the excess carbon and carries much if it away as, you guessed it, CO2. Now the chemistry is little more complex than this, but you get the picture. How much CO2 is produced? Just under two tons of it for every ton of steel produced. About 7% all global CO2 emissions come from steelmaking.

So what do we do about it? Well, the chemistry is clear: we either remediate the CO2 produced, or find another way to create that chemical reduction process to strip the oxygen from iron ore. And hydrogen has its own very useful property: react hydrogen gas from oxygen, and we get heat and water vapour. Can this be used to replace coke derived from metallurgical coal? Is it scalable and economical?

Swedish steelmaker SSAB thinks so, and since 2016 has led a joint venture to create a process using hydrogen and electricity called HYBRIT. Using green electricity and hydrogen gas, the plan is to convert all the firms steelmaking processes and reduce Sweden’s CO2 emissions by 10% and Finland’s by 7%. Now the key to making this work is of course low cost, green electricity. Scandinavia is blessed with hydropower resources, and everyone knows about the quality of Swedish iron ores.

For Europe, this looks like a practical process. But can it compete with traditional steelmaking in jurisdictions where carbon free power is neither cheap nor readily available, and metallurgical coal is available at low cost? That’s a bigger question, and a key driver may be carbon pricing. That’s a political decision, but the key obstacle to decarbonizing steel production has always been technological.

And Volvo Group’s little dump wagon is a lot more significant than it looks. It’s the coming-out party for an entirely new way of making the world’s most important metal.

Written by

James Anderton

Jim Anderton is the Director of Content for ENGINEERING.com. Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.