Teutraker has it right..

Revemin is of little value to KRY now as they don't have enough high grade ore left in their deposit to run it profitably, but MIBAM needs the mill to process ore from the small local miners who have their own small operations. If that ore is not processed properly it adds to the environmental problems, mercury contamination and tailings disposal issues.

Obviously if KRY can horse trade with MINBAM and give up part or all of the Revemin mill and the almost worked out areas back to MIBAM then they can placate the small miners and let them continue scratching around for the odd few ounces that remain. A mill in exchange for a permit and a clear deal to progress at LC might suit everyone (except Ortega of course, but I doubt anyone can please her).