I wrote a long response and it got ozoned but the short answer is that new mills will require a feasibilty study and new small mills like 1500 tpd can be built in less than a year or the company can buy an existing mill and they do exist. This would add to the 300 tpd and 60 tpd mills which ECU owns and which can be upgraded to 400 tpd and 100 tpd very easily.

The other question is feed or muck (ore) availability and this is why the large ramp is being driven to get better access for mining on level 18 and lower. It also wouldn't take much to start mining at Chicago and San Diego and new Teneras veins.