[BabyPeanut]

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How to make steelmaking 'green?' Add some plastic

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At first blush, chucking plastics into a furnace hardly sounds environmentally responsible. Indeed, researchers note that not all plastics would be suitable.

But Sahajwalla, a professor of materials science and engineering at the University of New South Wales in Sydney, explains that in their most basic form, plastics are made of hydrogen, oxygen, and carbon. And it's the carbon that she has her eye on as she considers the use of plastics in electric steelmaking furnaces.

Before coal can be used in refining iron or making steel, it must be turned into coke - a carbonized form of coal with the impurities baked out of it. During the baking process, the coal releases a range of noxious compounds, such as mercury and other metals, as well as sulfur and nitrogen oxides - the building blocks of acid rain and smog.

In the torrid heat of the furnace, coke's carbon reacts with the liquid metal, carrying away the oxygen in iron ore or rusty scrap as carbon monoxide or carbon dioxide gas.

While she acknowledges that carbon-dioxide emissions don't go away when plastics are used, plastics give off less CO2 than equivalent amounts of coal. And they don't produce the other noxious byproducts. In the lab, she and her research team have found that a 50/50 mixture of coke and plastic works just as well as a furnace filled with coke.

The approach wouldn't require manufacturing plastics specifically for steelmaking. "Let's put it this way," she says, grinning. "You definitely have enough plastics" in the world's landfills.

[gg3]

Oooh, I like that!

Now strictly speaking, those plastics are petrochemicals, and of course we'd do well to short-path recycle as much of the plastic waste as possible. However, that still leaves the majority of plastic wastes as suitable for use in steelmaking. This will help us stretch resources a bit further, and every bit counts.

BTW, old tires are currently used as fuel for the kilns in cement mills.

So now we have two of the the three primary building materials produced with energy derived from waste, and the third (wood) can be harvested sustainably in the manner that oldschool timber companies did and some still do.

[The_Virginian]

look for this to be used in the cheaper/lower grade mills ASAP.

Great find.