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Comment by ghastmaster | Hacker News Reader

Using natural gas introduces carbon. After the DRI stage, further treatments would be required to remove the carbon as it oxidizes. With less carbon there should be more consistent oxidizing of the iron, especially since it looks like carbon monoxide(from the natural gas) is not required which would introduce unwanted oxygen. I wish there were more details as well.

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The thing is you usually WANT Carbon in your Iron, so if you use Hydrogen DRI you have to further process the Iron to add the Carbon back in. There's a lot of potential for using mixtures of Hydrogen and Natural Gas to produce Iron with the exact desired Carbon content.

It seems to me that, when you want carbon in your iron (to make steel), you want a lot of control over how much carbon is in that steel. To start from a base iron that has no carbon in it whatsoever seems like it would be better for being more precise in your steel production.

While you certainly can add or remove Carbon during processing, you get the lowest costs if your input Iron is as close as possible to the desired Carbon content for your application.

Again, it seems to me that, if you care about extreme precision in your steel-making process, cost is the least of your worries.

Carbon is wanted for steel production, but at specific levels. DRI is further worked to oxidize carbon and remove it before processing. Eliminating the carbon/oxygen from natural gas reduction allows a more controlled introduction of carbon and or less processing to make ready for steel production.

Steel is an incredible massive category. For high quality steels (duplex, maraging, PH stainless), you actually don't want much carbon. Since they talk about "aging properties" in the article, I'd imagine they're targeting the nicer stuff. This doesn't seem like a process intended for cheap steel.

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