Mexico-focused miner may be unable to meet a looming debt payment despite recent asset sales, with talks continuing over a possible divestment of its San Dimas gold-silver mine.
The two South American countries have had a mining treaty in place since the 1990s.
Milpo and three other local zinc miners improved their bottom line in the third quarter, as base metals prices surged.
Minera IRL, which seeks to line up financing for a second gold mine after state development bank Cofide scrapped a US$240mn bailout, raised 2017 production guidance and extended the life of its aging Corihuarmi mine following a successful exploration campaign.
Among those originally charged in October 2016 in relation to the collapse of the company's tailing dam are executives from Samarco, Vale and BHP Billiton.
Peru, Colombia, Ecuador and Bolivia all took action to curb their burgeoning informal mining sectors.
Minsur plans to add a copper mine to its tin, gold and niobium-tantalum operations.