Ice breaking iorn ore carrier Hyundai Heavy Industries is building such a fleet very soon:
https://english.yonhapnews.co.kr/n_feature/2012/09/20/94/4901000000AEN20120920003800315F.HTML
320m and 190 000 to loading capacity !
The shipping window for non ice breaking iron ore carrier is 60 days. The port loading capacity (FS, p.307) is 10 000 to/h. AXI needs about 30 vessels of 172 000 to loading capacity to ship out 5,5 MTPA.
It takes you about 17,2 hours to load one vessel. Let's say they need 24 hours. So AXI needs to load and ship one vessel every two days for the period of 60 days. As the FS says AXI is trying to expand the shipping window with ice breaking vessels.
I actually see no problem at the moment. (production of 5,5 MTPA)
Anyway I totally agree that the maximum capacity withing the 60 days shipping window would be around 10 Mio to ! The new fleet of ice breaking vessels should be ready in a few years.