Mixing old concrete in steel furnaces purifies iron and makes reactivated cement

Headline was click-baity "'Absolute miracle' breakthrough provides recipe for zero-carbon cement" but science is interesting.

Paper's title is "Electric recycling of Portland cement at scale"

https://www.nature.com/articles/s41586-024-07338-8

There was some discussion yesterday [0] (16 points, 3 comments)

[0]: https://news.ycombinator.com/item?id=40446764