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Comment by hendry | Hacker News Reader

Umm... Electric arc furnaces have been around a while.

https://en.wikipedia.org/wiki/Electric_arc_furnace

Electric arc furnaces are recycling, they cannot produce steal from raw iron. Iron requires carboninzation to become Steel. Thus is done using coal both to produce the heat plus the carbon. Arc furnaces are big business because we've been producing Steel for over a century and Steel only rusts a bit. Thus most of the world historic steel can still be reused once reshaped.

Infact Nucor the largest steel producer in the US, uses arc furnaces to produce most of the steel.

The question is: what are Nucor's inputs. As I understand it, their input is scrap metal, not ore. (I lived down the road from one of their plants, and work with someone who used to work there, but I don't have extensive first hand knowledge)

Nucor steel mills in the US are set up to melt scrap with electric arc furnaces. A varying amount of semi-processed iron (pig iron or direct reduced iron) is added to a batch; they get this iron by shipment instead of producing it on site.

As of time of writing they have one facility in the US that makes direct reduced iron from iron ore and natgas; this plant is in Louisiana at (30.08, -90.86).

I think you mean iron ore not raw iron, there isn't really raw iron (at least not enough). I think you could simply re-melt "raw iron" with scrap steel in an electric arc furnace.

I just saw a random video the other day about aluminum recycling. For many uses they have to add rather a large amount of virgin aluminum in order to get the alloys right. Especially troublesome were alloys with heavy metals, which you have to keep out of food container feedstocks. I can’t imagine steel recycling being much different.

This video was about a plant that ground the aluminum to roughly inch sized pieces (sorting out anything bigger or smaller) then using X-rays and air jets to sort the alloys based on transmissivity of the trace elements. Their goal was to make aluminum billets out of 100% recycled material (although the video claimed the goal was 100% recycling, which is clearly not happening if you are culling pieces from the input stream. Might have been an error in translation or wishful thinking.)

I wonder if someone will do the same with steel.

Although EAFs aren't exactly 0 carbon either - even if the electricity and transportation are zero-carbon, the graphite electrodes they use are consumed in the melting operation. Approximately 5 Kg of Carbon is burned for each tonne of iron, releasing 20 Kg of CO2.

This article is mostly about hydrogen-fuelled direct reduction, the step before the the EAF. Some iron is already produced using DR but using conventional fossil fuels, and this plant would use renewable hydrogen instead of fossil carbon as the reducing agent.

Yes? And now Mitsubishi are saying they've built the world's largest. Is that a problem?

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