Making concrete and steel are both incredibly carbon intensive. As such, this new process appears to be really important. By throwing old concrete into steel processing furnaces, not only purifies iron, but also reactivates cement as a bi-product. If the furnace is heated using carbon neutral electricity, then both of these incredibly important items (for the modern human world) can be made without emitting carbon at all.
At the moment, not only is cement the worlds most used building material, but it emits 8% of the worlds carbon emissions in the process of being made. Unfortunately, at the current time, there is still work that needs to be done, in order to get to the point where the concrete that comes out of this process is as high grade as brand new concrete