Ann: Quarterly Activities/Appendix 5B Cash Flow Report, page-107

That would be an ideal scenario for shareholders ... however I doubt Malian gov would allow FFX to leave too much debt into the abandoned Morila subsidiary because it'll create massive social issues for unpaid creditors/local contractors, plus getting rid off all local workers. Surely a legal fight from Malian Gov is expected.
Not as simple as just walk away I guess.
In any country, there are always some legal limitation or implementation against the parent company.