Why stop at Hisarna? Let your imagination run wild! Add on two more new processes (one is actually not all that new anymore) and do away with carbon altogether!
First borrow a trick from the SEWGS process, developed by ECN. SEWGS has been a promising technology for some 10 years now. The part that is useful here is getting a stream of pure CO2 by absorbing it out of the off-gases in a bed of hydrotalcite and then desorbing it with steam, thus regenerating the bed. Now reduce the CO2 to CO electrochemically in a cell with an anode that consists of porous copper hollow fibers using renewable electricity (solar or wind) and use the CO to produce more steel. The end result can be summed up as “Look ma, no carbon!”
Just remember those twenty-five years…..