The company is now clearing and stabilising the El Tirito shaft area, located approximately 300 meters from the adit entrance of the past-producing mine.
Workers are clearing and stabilising cross cuts and stopes, as well as access to the internal shaft, Minaurum said.
They are also working on preparing a staging area outside the adit entrance, and draining water from the main haulage level.
Workers have removed approximately 200 tonnes of ballast and 50 tonnes of backfill from the first 300 meters of the haulage level. This has been stockpiled outside the main entrance.
Workings of the mine are in good condition, Minaurum said.
The dewatering of the newly accessed areas of Promontorio allowed Minaurum to identify new underground drill collars. Minaurum drilled five service holes, which intercepted 5.8 meters of 98 g/t of gold, 3.6% lead, and 7.9% zinc.
"Getting underground where no one has been for decades allows us to improve our geological understanding of the silver shoots in the district and provides the ability to commence underground drilling," Minaurum chief executive Darrell Rader said.
The company first decided to rehabilitate the Promontorio mine in August. The mine produced approximately 70 million ounces of silver. Promontorio was closed in 1896, and remained abandoned until the 1960s, when material was processed from surface dumps and underground backfill.